Pathogenesis of ANCA-associated vasculitis: An update

    Pathogenesis of ANCA-associated vasculitis: An update Pierre-Andr´e Jarrot, Gilles Kaplanski PII: DOI: Reference:

S1568-9972(16)30055-6 doi: 10.1016/j.autrev.2016.03.007 AUTREV 1846

To appear in:

Autoimmunity Reviews

Received date: Accepted date:

26 February 2016 1 March 2016

Please cite this article as: Jarrot Pierre-Andr´e, Kaplanski Gilles, Pathogenesis of ANCA-associated vasculitis: An update, Autoimmunity Reviews (2016), doi: 10.1016/j.autrev.2016.03.007

This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.

ACCEPTED MANUSCRIPT Pathogenesis of ANCA-associated vasculitis : An update Pierre-André Jarrot1, 2 (MD), Gilles Kaplanski1, 2 (MD/PhD) Division of Internal Medicine and Clinical Immunology, Assistance Publique-Hôpitaux

PT

1

de Marseille (AP-HM), Hôpital de la Conception, Marseille, France

Aix-Marseille Université, INSERM UMR S-1076, Vascular Research Center of Marseille

SC RI

2

(VRCM), Marseille, France Corresponding author

NU

Pr. Gilles Kaplanski (MD/PhD)

Service de médecine interne et d’immunologie Clinique

MA

Hôpital de la Conception, Assistance-Publique-Hôpitaux de Marseille (AP-HM) 147 boulevard Baille 13005 Marseille

ED

France

Phone number: +33 4 91 38 35 22

PT

Email: [email protected]

CE

Disclosures: The authors have no conflicts of interest to declare.

AC

Financial supports: The authors have received no financial supports.

1

ACCEPTED MANUSCRIPT Abstract Antineutrophil cytoplasmic antibody (ANCA)–associated vasculitis (AAV) constitutes a group of rare diseases characterized by necrotizing inflammation of small blood vessels

PT

and the presence of ANCA. Although these auto-antibodies were initially used to classify pauci-immune vasculitis, increasing clinical and experimental evidence now supports

SC RI

their pathogenic role, mainly through ANCA-induced activation of primed-neutrophils and monocytes leading to destructive vascular necrosis. The mechanisms of ANCA generation remain however unclear. Neutrophils play a central role in the pathophysiological process of AAV since they are both effector cells responsible for

NU

endothelial damage, and targets of autoimmunity. Another role of neutrophils is due to their ability to generate neutrophil extracellular traps, which support the presentation

MA

of ANCA auto-antigens, could break immune tolerance and induce autoantibody generation. Alternatively, the ANCA autoimmune response is facilitated by insufficient T-cell and B-cell regulation and the role of complement alternative pathway has recently

ED

been emphasized. This review summarizes the main pathogenesis concepts of AAV as

PT

well as the putative mechanisms for the origin of ANCA autoimmune response.

Keywords

CE

Antineutrophil cytoplasmic autoantibodies, antineutrophil cytoplasmic antibody-

AC

associated vasculitis, immune response, neutrophil extracellular traps

2

ACCEPTED MANUSCRIPT Contents 1. Introduction 2. Overview of ANCA 2.2. Emergence of ANCA

SC RI

3. ANCA-induced neutrophils and monocytes activation

PT

2.1. Pathogenicity of ANCA

3.1. Main mechanisms 3.2. Neutrophil extracellular traps

4. Regulation of the immune response inducing ANCA

NU

4.1. B cells 4.2. T cells

MA

4.3. Neutrophils 5. Alternative complement pathway

AC

CE

PT

ED

6. Conclusion

3

ACCEPTED MANUSCRIPT Abbreviations ANCA, anti-neutrophil cytoplasmic antibody; AAV, ANCA-associated vasculitis; GPA, granulomatosis with polyangiitis; EGPA, eosinophilic granulomatosis with polyangiitis;

PT

MPA, microscopic polyangiitis; IgG, immunoglobulin G; c-ANCA, cytoplasmic-ANCA; pANCA, perinuclear-ANCA; MPO, myeloperoxidase; PR3, proteinase 3; NETs, neutrophil

SC RI

extracellular traps; DNA, desoxyribonucleic acid; GN, glomerulonephritis; GWAS, genome-wide association study; SLE, systemic lupus erythematosus; BVAS, Birmingham vasculitis activity score; RNA, ribonucleic acid; LAMP-2, lysosomal-associated membrane-2; TLR, toll-like receptor; ROS, reactive oxygen species; TNF, tumour factor;

IL,

interleukin;

HMGB-1,

high

NU

necrosis

mobility

group

box-1;

GPI,

glycosylphosphatidylinositol; MAC-1, macrophage integrin-1; PECAM-1, platelet

MA

endothelial cell adhesion molecule-1; ITIM, immunoreceptor tyrosine-based inhibitory; FcγR, FC-gamma receptor; NSP, neutrophil serine protease; DPPI, dipeptidyl peptidase I; NADPH, nicotinamide adenine dinucleotide phosphate; NOX-2, nicotinamide adenine

ED

dinucleotide phosphate-oxidase-2; ICAM-1, intercellular adhesion molecule-1; APC, antigen-presenting cell; DNAse-1, desoxyribonuclease-1; PD-1, programmed cell death

PT

protein-1; TRAIL, TNF-related apoptosis inducing ligand; Bregs, regulatory B-cells; TH, helper T-cells; FOXP3, forkhead box P3; Tregs, regulatory T-cells; BAFF, B-cell-activating

CE

factor; BLyS, B lymphocyte stimulator; APRIL, A proliferation inducing ligand; C,

AC

complement fraction; KO, knockout; C5aR, C5a receptor; CFH, complement factor H.

4

ACCEPTED MANUSCRIPT 1. Introduction Antineutrophil cytoplasmic antibody (ANCA)–associated vasculitis (AAV) is a lifethreatening group of multisystemic diseases characterized by a small vessel pauci-

PT

immune vasculitis and the presence of circulating pathogenic ANCA [1]. Contrary to immune-complex-mediated vasculitis, AAV has an absence or a paucity of

SC RI

immunoglobulin deposition in injured vessels [1]. AAV patients are clinically and pathologically subclassified into granulomatosis with polyangiitis (GPA, formerly Wegener’s granulomatosis), eosinophilic granulomatosis with polyangiitis (EGPA, also known as Churg-Strauss syndrome), microscopic polyangiitis (MPA), or organ-limited [1-4]. ANCA are predominantly

NU

diseases especially for lungs and kidneys

immunoglobulin G (IgG) autoantibodies directed against constituents of neutrophil’s

MA

primary granules and lysosomes of monocytes. Two different kinds of ANCA can be distinguished according to their fluorescence pattern: cytoplasmic (c)-ANCA and perinuclear (p)-ANCA. Although several ANCA antigenic targets have been identified, the

ED

two-best-characterized with a clinical relevance consist in myeloperoxidase (MPO) and proteinase 3 (PR3) [5-7]. Beyond a diagnostic serological marker, clinical and

PT

experimental data support a pathogenic role for ANCA, which promote activation of primed neutrophils and monocytes, and their adhesion to the endothelium, leading to

CE

subsequent tissue damage [8, 9]. Although various hypotheses with different kinds of triggers have been suggested concerning ANCA formation, none has been confirmed to

AC

date. Neutrophils play a central role in AAV pathogenesis since they are both effector cells responsible for endothelial damage, and targets of autoimmunity. Another feature of neutrophils is their ability to generate neutrophils extracellular traps (NETs), a process widely denoted as “NETosis” [10]. Apart from their initial antibacterial functions, these fibrous networks of desoxyribonucleic acid (DNA) decorated with antimicrobial peptide can be deleterious for endothelium and display auto-antigens to dendritic cells leading to the pathogenic ANCA immune response [11, 12]. Recently, new cellular protagonists have been involved in the pathogenesis of AAV participating to the break of immune tolerance and suggesting a complex disorder. Indeed, the ANCA autoimmune response is facilitated by a defect of adaptive immunity with insufficient Tcell and B-cell regulation [13, 14]. Furthermore, the role of the alternative complement pathway has been recognized [15]. In this review, we propose to summarize the main

5

ACCEPTED MANUSCRIPT concepts of AAV pathogenesis as well as the putative mechanisms explaining the origin of ANCA autoimmune response.

PT

2. Overview of ANCA 2.1. Pathogenicity of ANCA

SC RI

ANCA were unexpectedly discovered in 1982, while studying antinuclear antibodies in serum sample from patients with segmental necrotizing glomerulonephritis (GN). They were subsequently associated with GPA in 1985 [16, 17]. Because of their association

NU

with small-vessel vasculitis, a pathogenic role for ANCA has always been suspected. In vitro, ANCA stimulate primed-neutrophils to undergo a respiratory burst, degranulation of toxic proteins and adhesion to endothelium [8, 18].

MA

Apart from in vitro studies, the most compelling evidence that ANCA are pathogenic derives from first, a human case of transplacental transfer of anti-MPO antibodies with

ED

subsequent neonatal MPA and second, various animal models [19]. To date, the most convincing model is an acute passive transfer model using purified antibody or splenocytes derived from MPO-deficient mice immunized with purified murine MPO,

PT

which were injected into wild-type animals [20]. These mice developed over the course of 6-13 days, a necrotizing pauci-immune GN with associated pulmonary capillaritis in

CE

some cases. Although the disease can also be induced with injection of anti-MPO IgG into RAG2-/- mice (that lacked B and T cells) strengthening the prominent role of antibodies,

AC

neutrophils appear to be strictly required for anti-MPO-induced vasculitis [21]. Pathogenicity of anti-PR3 antibodies is less well-established and there are no unequivocal models of anti-PR3-ANCA disease, possibly because of quantitative and proteomic differences between human and rodent’s PR3 [22-24]. Two main models were however described, using other transgenic rodents and transfer methods. The first one was developed from a rapid transfer of reactive splenocytes into autoimmune prone non-obese diabetic mice which lack endogenous T and B cells and the second, was based on a human-mouse chimeric immune system [25, 26]. Recently, genome-wide association studies (GWAS) have suggested that different AAV subtypes especially GPA and MPA are underpinned by distinct genetic risk factors, with GPA being associated with HLA-DP, SERPINA1 (encoding α1-antitrypsin), PRTN3 (encoding PR3) and semaphorin 6A, whereas MPA is mainly associated with HLA-DQ polymorphisms [27, 28]. Interestingly, the European GWAS mainly reported a peculiar 6

ACCEPTED MANUSCRIPT ANCA-specificity associated single nucleotide polymorphism, strengthening the central role of MPO and PR3 as auto-antigens in AAV [27]. ANCA are not always pathogenic. Indeed, low titers of circulating auto-antibodies

PT

against MPO and PR3 have been reported in healthy individuals and designated as “natural” or nonpathogenic autoantibodies [29]. Although these auto-antibodies have

SC RI

lower avidity and less capability to activate neutrophils, it remains unclear however, whether ANCA targeting these epitopes would remain truly nonpathogenic at higher concentrations such as those observed in AAV [30]. Interestingly, detectable MPO and PR3 ANCA, but also ANCA directed against other auto-antigens contained in primary

NU

granules such as lactoferrine or bactericidal permeability increasing protein, have been also described in different kinds of non-vasculitic disorders, such as inflammatory bowel

MA

diseases and systemic lupus erythematosus (SLE) with a controversial clinical relevance [31-33].

Considering that autoantigens can have multiple epitopes specificities, a highly sensitive

ED

epitope excision study with a mass spectrometry approach identified 25 different epitopes bound by anti-MPO antibodies [34]. The authors found a significant MPO-ANCA

PT

diversity with detection of exclusive epitopes associated with active disease, distinct epitopes non specific of active disease, and epitopes which are not associated with the

CE

disease at all. In addition, the same study demonstrated that immunoglobulins purified from patients with ANCA-negative vasculitis, were able to bind to a specific MPO

AC

epitope. The absence of ANCA detection in some of these patients may be explained by binding competition with a fragment of ceruloplasmin, the natural inhibitor of MPO. The 3D structure of MPO revealed a close proximity between the epitopes associated with active disease and those of healthy individuals, suggesting a first autoimmune reaction against natural epitopes with subsequent spreading to pathogenic epitopes [34]. Another study examined the relationships between 6 recombinant linear epitopes of MPO-ANCA and clinico-pathological features of AAV patients. Birmingham Vasculitis Activity Score (BVAS) and serum creatinine were found significantly higher in patients with a positive binding to the whole 6 epitopes. During disease remission, the number of epitopes recognized was lower than at initial onset, confirming that epitope specificities were associated with disease activity and some clinico-pathological features of AAV patients [35]. Finally, this pathogenic transformation of ANCA could be multifactorial, with genetics and immunological events, facilitating the break of immune tolerance. 7

ACCEPTED MANUSCRIPT 2.2. Emergence of ANCA Although the mechanisms of auto-antibodies formation in AAV remain unclear, following the hypothesis concerning of SLE, numerous theories have been postulated

PT

with molecular mimicry being one of the most discussed [36]. The first attractive theory suggests that generation of PR3-ANCA could be attributable to the so-called complementarity

theory”.

Contrary

to

the

SC RI

“autoantigen

sense

peptide,

the

complementary peptide has an amino acid sequence (read 3’ to 5’) that is coded by the complementary (antisense) strand of DNA or by complementary ribonucleic acid (mRNA) [37]. These two peptides are able to specifically interact by pairwise relations

NU

between amino acid residues [38]. Thus, adaptive immune response against a complementary peptide can lead to the production of antibodies, which will trigger an

MA

anti-idiotype response, and the latter antibodies will also react against the original autoantigen. AAV patients were reported to have not only PR3-ANCA, but also antibodies directed against complementary PR3 [39]. In the same study, immunization

ED

of mice with human PR3 complementary peptide resulted in the production of either antibodies to the peptide or antibodies to the sense peptide, strengthening this theory.

PT

This complementary peptide may emerge from the transcription of endogenous antisense strand of DNA, or could be a mimic of an antisense peptide that is produced by

CE

a pathogen. Interestingly, several sequence homologies of complementary PR3 with GPA previously associated-pathogens, such as Entamoeba Histolytica or Staphylococcus

AC

Aureus have been described [39-41]. No direct evidence however, that complementary PR3-antibodies cross-reacted with bacterial proteins has been provided to date, and their presence in PR3-ANCA associated patients was not confirmed [42]. Further studies are thus needed to prove the concept of autoantigen complementarity theory in the emergence of pathogenic ANCA. Another hypothesis based on molecular mimicry comes from sequence homology between FimH, a gram-negative bacillus adhesion and lysosomal membrane associated protein-2 (LAMP-2). Indeed, LAMP-2 antibodies were reported in 90% of patients with pauci-immune GN including patients with positive ELISA for PR3 or MPO and others who were negative for both. Moreover, rats immunized with FimH developed crossreactive LAMP-2 antibodies and a pauci-immune GN suggesting a FimH-triggered LAMP2 autoimmunity [43]. Another study however failed to reproduce this experimental

8

ACCEPTED MANUSCRIPT animal model and reported a weak prevalence of LAMP-2 antibodies in AAV, which was subsequently confirmed in a different cohort of MPA [44]. These 2 main hypotheses are summarized in figure 1.

PT

Considering the association of Staphylococcus Aureus carriage with AAV, one possible hypothesis could involve the ability of this bacteria to activate neutrophils via the

SC RI

monocyte/macrophage toll-like receptor (TLR) pathways [45]. Interestingly, TLR-9 ligands consisting in gram-positive bacteria components, have been demonstrated to trigger in vitro ANCA production by peripheral blood-derived B cells from AAV patients, neutrophil MPO release and increased neutrophil membranous PR3 expression [46, 47].

NU

Recently, a candidate gene study speculated that TLR-9 may have an effect on GPA susceptibility and clinical manifestations, but the authors cannot provide reliable

MA

evidence for ANCA formation [48].

Apart from the potential pathogen starting-point of pathogenic ANCA formation, numerous drugs such as hydralazine, propylthiouracil and levamisole-adultered cocaine

ED

have been reported to be strongly associated with AAV onset [49]. The underlying mechanisms of drug-induced ANCA formation are not fully understood. Hydralazine is a

PT

DNA methylation inhibitor with suspected reverse epigenetic silencing properties, leading to increased expression of MPO and PR3 autoantigens in neutrophils [50, 51].

CE

Another study proposed that reactive intermediate species formed by propylthiouracil could act as a MPO substrate [52]. These non-infectious triggers could thus participate

AC

to the break of immune tolerance and promote the autoimmune reaction. In addition, several studies have highlighted the importance of HLA class II polymorphisms for autoantibody emergence. This is well known in celiac disease where antibody formation is strictly dependant on a specific HLA genotype [53]. Similarly, AAV seems to associate two distinct genetically subset of vasculitis according to ANCA specificity [27]. These data suggested that distinct T cell specificities account for the association of different HLA alleles with particular autoantibodies formation. Postulated mechanisms for induction of autoimmunity by interplaying with predisposing HLA molecules, may involve post-translational or small molecules-based modifications of peptide presented to T cells [54].

9

ACCEPTED MANUSCRIPT 3. ANCA-induced neutrophil and monocyte activation 3.1. Main mechanisms The full activation of leukocytes by ANCA IgG is facilitated by cell pre-activation, through

PT

a process called priming, which can be mediated by pro-inflammatory stimuli such as tumour necrosis factor-α (TNF-α), bacterial lipopolysaccharide, interleukin (IL)-18,

SC RI

complement anaphylatoxin C5a, or high mobility group box-1 (HMGB-1) [15, 55-58]. Indeed, ANCA-induced superoxide release and degranulation were enhanced after TNFα priming in vitro [55]. Interestingly, TNF-α and HMGB-1 priming were shown to increase ANCA auto-antigens membrane expression via enzyme migration from the

NU

granules, thus facilitating the binding of ANCA [58, 59]. Although the signaling pathways involved in priming are not fully known, activation of the p38 mitogen activated protein

MA

kinase, extra signal regulated-kinase and phosphoninositol-3 kinase appear to be important steps in the translocation of ANCA antigens to the cell membrane [60, 61]. ANCA target antigens membrane expression appears not to be solely mediated by

ED

priming. Variable amount of constitutive PR3 are expressed on the surface of neutrophils, with inter-individual differences [23]. Some studies have reported that AAV

PT

patients have a higher PR3 membrane expression on their neutrophils than healthy individuals [23, 62]. Furthermore, within the ANCA group, the percentage of PR3

CE

membrane expression was higher in patients with relapsing diseases [63]. Two main hypotheses involving the neutrophil antigen B1 (NB1/CD177) have been proposed to

AC

explain this phenomenon. CD177, a glycosylphosphatidylinositol (GPI)-anchored protein with a bimodal surface expression, has been shown to present PR3 on the membrane of a neutrophil subset. CD177 may directly mediate a higher surface expression of PR3 leading to a stronger binding of ANCA IgG to neutrophil surfaces and subsequent activation via CD177-CD11b/CD18 (macrophage antigen-1 (MAC-1)) receptor interactions [64, 65]. CD177 has also been described as a novel heterophilic counter-receptor for the endothelial junction protein, platelet endothelial cell adhesion molecule-1 (PECAM-1) [66]. Through suppression of PECAM-1 functions by an immunoreceptor tyrosine-based inhibition motif (ITIM) phosphorylation and subsequent selective disruption of the endothelial cell junctions, CD177-PECAM-1 interactions may facilitate neutrophil diapedesis [67]. Primed neutrophils from CD177-negative individuals however, have been shown to express PR3 and to be susceptible to anti-PR3-induced activation, 10

ACCEPTED MANUSCRIPT suggesting that PR3 recruitment may occur in part, independently of CD177 [68]. Nevertheless, CD177-induced higher expression of PR3 facilitating neutrophil endothelial transmigration, could participate to stronger vascular damages in AAV.

PT

Auto-antigens membrane expression may also be genetically determined. Patients with AAV have been demonstrated to aberrantly express PR3 and MPO-encoding genes due

SC RI

to epigenetic modifications with defective gene silencing [69]. In addition, an alternative PR3 transcript allowing the binding of ANCA IgG was recently described in AAV patients, suggesting an increased auto-antigen repertoire [70]. Aberrant or alternative transcription of PR3 and MPO could lead to auto-antigen mistargeting and may

NU

participate to the suspected break of tolerance in AAV pathogenesis. The binding of ANCA results in full neutrophil activation through the engagement of

MA

constitutively expressed Fcγ receptors (FCγR) by ANCA-containing immune complexes, as well as by ANCA Fab’2 binding to antigens on neutrophil surface [71-73]. Not all FcγR, however, are activators, since FCγRIIB for example contains an ITIM unit and has been

ED

recently shown to negatively regulate anti-MPO auto-immunity, as well as GN induction [74]. In addition, glycosylation of CH2 domains constitutive of the IgG Fc fragment

PT

appears to be critical to allow complete interactions with FCγR and seems to be required for ANCA-mediated effects. Indeed, treatment with endoglycosidase S significantly

CE

decreased ANCA ability to activate neutrophils, without interfering with their antigenbinding capacity [75].

AC

ANCA-induced neutrophil and monocyte activation (Figure 2) leads to the release of toxic granule proteins, especially neutrophil serine proteases (NSP) [76]. NSP activation requires a proteolytic cleavage by the lysosomal enzyme dipeptidyl peptidase I (DPPI), also known as cathepsin C. A detrimental role of NSP has been recently reported in an animal model of anti-MPO-induced GN. DPPI-deficient mice were protected against vasculitis via a massive reduction of IL-1β production by ANCA-stimulated leukocytes, and reduced renal IL-1β concentrations, suggesting a pivotal role for NSP-mediated IL1β signaling pathway in the induction of ANCA-mediated GN [76]. Moreover, animals treated with the IL-1 receptor antagonist were protected against anti-MPO induced-GN [76]. ANCA-induced ROS release in vitro is mediated by the nicotinamide adenine dinucleotide phosphate- (NADPH) oxidase (NOX-2). Although NOX-2-induced ROS has been shown to cause oxidative tissue damage through lipid and protein oxidation in several animal models, the role of NOX-2 in AAV has not been established yet [77]. 11

ACCEPTED MANUSCRIPT Furthermore, in an anti-MPO GN animal model, a study elegantly demonstrated that NOX-2 deficient mice have a more severe phenotype, associated with increased kidney IL-1β concentrations. NOX-2 acts by down-regulating caspase-1, thereby limiting

PT

inflammasome-induced IL-1b processing and ANCA-induced inflammation [78]. Thus two different ANCA-mediated pathways alternatively regulate IL-1β generation in

SC RI

myeloid cells: the NSP dependent pathway first, leading to “caspase-1-independent” IL1β processing and the NOX-2 dependent pathway, negatively regulating caspase-1 activation and IL-1β generation. These recent data also suggest that IL-1 receptor blockade could be a promising strategy in AAV.

NU

Apart from ANCA-induced neutrophils activation, a recent study demonstrated that expression of PR3 on apoptotic neutrophils may participate in disrupting immune

MA

silencing in AAV. Indeed, phagocytosis of PR3-expressing apoptotic cells stimulates macrophages to produce inflammatory chemokines, thus promoting the recruitment of inflammatory cells expressing PR3 and inducing an amplification loop of sustained

ED

inflammation [79].

Under physiologic conditions, neutrophils do not interact with resting endothelium.

PT

Binding of ANCA promotes a firm adhesion of primed neutrophils to the endothelium via a β2-integrin/intercellular adhesion molecule-1 (ICAM-1) interaction [18]. The main

CE

consequences of this firm adhesion are first, a higher level of neutrophil membrane PR3 accessible for ANCA and second, an endothelial cell activation consisting in endothelial

AC

cytosolic calcium rise and cytoskeletal changes leading to increased microvascular permeability and neutrophil diapedesis [80, 81]. Moreover, in vitro experiments have shown that ANCA-activated neutrophils cause endothelial cell injury and cell death [82]. Similarly to neutrophils, monocytes express MPO and PR3. Numerous monocytes and macrophages were identified in the kidneys and lungs of patients with AAV [83]. Expression of CD14 on monocytes from patients with active AAV is increased, compared with patients in remission or healthy donors and correlates with both MPO or PR3 membrane expression, reflecting monocyte/macrophage activation in AAV [84]. ANCA have also been shown to stimulate ROS production and to induce IL-1β secretion of by monocytes [85, 86]. 3.2. Neutrophil extracellular traps (NETs) Another peculiar function of activated neutrophils is the extrusion of NETs, a phenomenon called NETosis. NETs were first described in 2004 initially associated with 12

ACCEPTED MANUSCRIPT an antibacterial role consisting in bacteria trapping [10] and are composed of decondensed fibers of chromatin decorated with antimicrobial peptides, such as neutrophil elastase, MPO, PR3 and others. Excessive NETosis is however deleterious for

PT

tissues and seems to be involved in AAV pathogenesis [87]. In 2009, a first study demonstrated that NETs released after in vitro ANCA-induced neutrophil activation,

SC RI

contained MPO and PR3. Co-localization of MPO, PR3 and extracellular DNA indicating NETs deposition was also observed in kidneys of patients with AAV GN. In addition, circulating NETs biomarkers were reported in serum of AAV patients with active GN [88].

NU

A common hypothesis is that NETs could trigger adaptive autoimmunity through exposure of extracellular autoantigens to antigen-presenting cells (APC). A recent study

MA

showed MPO and PR3 transfer from NETting neutrophils into dendritic cells, with subsequent generation of anti-MPO ANCA and development of autoimmune vasculitis in animals [12]. The kind of interactions involving NETs and APC which may be

ED

responsible for B and T cell co-stimulation remains however, unclear. In addition, in a propylthiouracil-induced MPO-AAV rat model, disordered NETs may participate in AAV through

desoxyribonuclease-1

abnormal

PT

pathogenesis

(DNAse-1)

conformation

[89].

and

Furthermore,

impaired a

recent

degradation human

by

study

CE

demonstrated that MPO ANCA have a high ability to generate NETs in vitro, and confirmed their impaired degradation in AAV patients through a weaker DNAse-1

AC

activity, with a potential supplementary inhibitory effect in case of anti-NETs antibodies are present in patients [90]. NETs could also provide a new link between innate immunity and thrombosis by stimulating platelets adhesion and coagulation [91, 92]. They were identified in experimental deep vein thrombosis animal models and recently in a thrombus from a MPA patient [93]. Finally, NETs induce endothelial cell death through histone-dependent cytotoxicity and may participate in vascular damage in patient with AAV [11]. Emerging concepts concerning the role of NETs in AAV pathogenesis are depicted in figure 2, 3 and 4.

13

ACCEPTED MANUSCRIPT 4. Regulation of the immune response inducing ANCA 4.1. B cells An important role of B-cells in AAV pathogenesis was underscored by first, animal

PT

models demonstrating the pathogenic role of ANCA, second, the detection of activated Bcells infiltrates in endo-nasal inflammatory lesions from GPA patient [20, 94] and was

SC RI

recently confirmed by successful treatment using anti-CD20 chimeric antibody (rituximab), which is now currently used in induction and maintenance regimen of patients with both GPA and MPA [95, 96].

Several studies have reported an abnormal distribution of circulating B-cells subsets in

NU

active AAV patients compared to patients in remission or healthy donors, notably a significant increase of CD38+ B-cells in active GPA [97]. Similarly to SLE, higher

MA

expression of CD19 on memory B-cells associated with higher autoantibody production have been identified in AAV, suggesting the presence of autoreactive B-cells [98]. Alternatively, no functional B cell defects has been reported in AAV to date [99].

ED

Regulatory B-cells (Bregs) are characterized by the production of IL-10 and their ability to suppress the immune response [14, 100]. Recent reports have shown that Bregs

PT

inhibit the differentiation of naïve T cells into TH-1 or TH-17 and promote the development of regulatory T-cells (Tregs) [101]. Bregs also enhance activated T-cells

CE

apoptosis through different signaling pathways involving programming death domain-1 (PD-1), Fas-L, and tumour necrosis factor-related apoptosis-inducing ligand (TRAIL)

AC

[102]. Although Bregs complete phenotype is not fully defined, some markers including CD5, CD24, CD37 and CD38 seem to be associated with regulatory functions. Several studies reported a quantitative defect of Breg subsets in active AAV patients compared with healthy controls, but correlations with IL-10 production remain controversial [103105]. A recent report showed that peripheral CD5+ Bregs correlated with disease activity in patients treated with rituximab suggesting CD5+ Bregs count may be an interesting biomarker in AAV [106]. Thus, B-cells may play an important role in AAV pathogenesis by participating in ANCA generation and ANCA immune response regulation. Further investigations are however, needed to clarify the complete Bregs phenotype and the role of B-cell regulation in AAV.

14

ACCEPTED MANUSCRIPT 4.2. T cells As with B-cells, infiltrating T-cells were detected in inflammatory lesions of AAV patients (kidneys, lungs and nasal biopsies) suggesting a pathogenic contribution of T

PT

cell-mediated immune response [83, 107]. In addition, soluble IL-2 receptor and soluble CD30 were increased in plasma of AAV patients and correlated with disease activity

SC RI

[108].

Aberrant helper T-cells (TH) polarization was described in patients with AAV and revealed a shift toward a TH2-type response in patients with active generalized disease, whereas a TH1-type response was predominant in patients with localized disease [109,

NU

110]. More recently, TH17 cells have emerged as a new CD4+ T-cells subsets characterized by a pro inflammatory profile with secretion of IL-17A, IL-21, IL-22 or IL-

MA

23 [111]. An in vitro study demonstrated that MPO-ANCA activated-neutrophils promoted TH17-mediated autoimmunity through IL-17A and IL-23 production [112]. In addition, IL-17A was shown to play a role in anti-MPO-induced GN murine model by

ED

mobilizing neutrophils and promoting the recruitment of injurious macrophages into the kidney, supporting a functional role of the TH17 in AAV [113]. TH17-cells may thus

PT

be a major effector subset in the development of AAV, but further studies are required to determine whether IL-17A could be a promising therapeutic target.

CE

The actions of TH cells can be balanced by Tregs, which are characterized by a high expression of CD25 and forkhead box P3 (FoxP3) that is required for both their

AC

development and function [114]. Although different studies reported conflicting results regarding the frequency of Tregs in AAV compared to healthy controls, all of these studies revealed impaired suppressive functions of circulating Tregs [115, 116]. Indeed, contrary to healthy controls and ANCA-negative patients, Tregs from AAV patients failed to suppress PR3-induced T-cells proliferation [13]. Moreover, Tregs from patients with active disease were shown to disproportionately used a FoxP3 isoform lacking exon 2, which might alter Tregs functions [117]. Thus, qualitative disturbances in Tregs may contribute to insufficient suppression of ANCA-producing B cells in patients with ANCA diseases. Finally, a recent study showed an increase of circulating T effector memory cells and their detection in urinary analysis of patients with active renal disease, strongly suggesting their role in determining kidney damage and their use as a potential biomarker of renal disease activity in AAV [118]. 15

ACCEPTED MANUSCRIPT The main mechanisms of ANCA-immune response regulation are summarized in figure 3. 4.3. Neutrophils

PT

Activated neutrophils also represent an important source of TNF-ligands superfamily members including B-cell activating factor (BAFF)/B lymphocyte stimulator (BLyS) and

SC RI

A proliferation inducing ligand (APRIL), known to play important roles in B-cell differentiation, proliferation and immunoglobulin production [119]. To date, some studies reported that patients with AAV have elevated serum levels of BAFF/BLyS, but

NU

not APRIL, compared with healthy controls [120, 121]. Interestingly, circulating serum levels of BAFF/BLyS seem to diminish after treatment [120]. Although one recent study

MA

demonstrated a correlation between BAFF/BLyS concentrations and disease activity, BAFF levels were not related to MPO-ANCA levels [122]. BAFF seems to be a promising target for the treatment of AAV, but further studies are needed to assess its potential use

ED

as a biomarker of the disease [123].

PT

5. Alternative complement pathway

Because the pathological hallmark of ANCA-associated GN consists in pauci-immune

CE

necrotizing crescentic GN and since AAV is not associated with serum complement consumption, it was previously assumed that complement did not play a significant role

AC

in AAV pathogenesis [124, 125]. A detailed study using electron microscopy from 126 renal biopsies of ANCA-associated GN however, identified positive immunofluorescent C3 deposits in 57% of the cases [126]. To date, increasing evidence suggest an important role of complement activation in the pathogenesis of AAV. First, using a previously described anti-MPO GN animal model, it was demonstrated that C5- and factor Bdeficient mice were both protected against vasculitis, whereas C4-deficient or wild-type mice developed the disease [127]. Interestingly, mice pretreated with a C5-inhibiting monoclonal antibody were also protected against the disease [128], suggesting a critical role for the alternative pathway of complement and C5 activation in the emergence of ANCA-associated GN. Two other studies confirmed the importance of C5 activation and demonstrated requirement of the C5a receptor (C5aR) engagement for the development of MPO ANCAinduced GN using a C5aR-deficient mice or a human C5aR pharmacological antagonist, named CCX168 [15, 129]. In addition, generation of C5a which is able to prime and 16

ACCEPTED MANUSCRIPT recruit neutrophils, was identified in the supernatants of ANCA-activated neutrophils, suggesting an amplification loop involving complement during ANCA-mediated neutrophils activation [15].

PT

The human plasmatic complement activation profile revealed higher plasma levels of C3a, C5a, soluble C5b-9, Bb and lower complement factor H (CFH) concentrations in

SC RI

patients with active AAV compared with patients in remission. Moreover, the plasmatic levels of factor Bb in patients with active AAV correlated with crescentic glomerular and disease activity, whereas CFH concentrations inversely correlated with disease activity biomarkers of disease activity [130, 131].

NU

of kidney involvement, suggesting that circulating Bb and CFH may be interesting Although neutrophil membranes and neutrophil-derived microparticles could activate

MA

the alternative complement pathway, a recent study identified in vitro deposition of alternative complement pathway components on NETs [132, 133]. In addition, higher levels of C3a, C5a and C5b-9 were reported in the supernatants of ANCA-induced

ED

NETosis compared to primed neutrophils, strengthening the putative role of NETs and alternative complement pathway in AAV pathogenesis [133]. The activation and effector

PT

mechanisms of the alternative complement pathway in AAV are depicted in figure 4. To date, numerous studies confirmed the role of alternative complement pathway and

CE

C5a/C5aR interactions in the pathogenesis of AAV, other studies are however required to investigate the link between complement activation and NETosis. Nevertheless, these

AC

observations concerning the role of complement in AAV pathogenesis provide a rationale for the use of eculizumab (a C5-inhibitor) and the C5aR antagonist in these diseases.

6. Conclusion AAV is a complex disease involving the immune system (innate/adaptive) and extraimmune factors (environmental/genetics). Although AAV pathogenesis remains incompletely understood, some questions have moved closer to resolution and new protagonists were recently identified. To date, mechanisms of ANCA formation stay unclear, but molecular mimicry remains an attractive hypothesis. New concepts were emerging such as NETs, which facilitate ANCA antigens exposure and may participate to the break of immune tolerance followed by autoantibody generation. Neutrophils play a central and dual role in the pathogenesis of AAV since they are both target of ANCA and contribute to endothelial damage. ANCA-activated neutrophils also release factors, 17

ACCEPTED MANUSCRIPT which activate alternative complement pathway, with a subsequent inflammatory amplification loop, exacerbating necrotizing vascular inflammation. Finally, an impaired regulation of ANCA immune response with quantitative and qualitative abnormalities

PT

affecting both T and B-cells has been recently identified, but further studies are needed to investigate all the defective mechanisms of regulation. In the last few years, the

SC RI

highlighting of new therapeutic targets promotes the development of promising therapy

NU

such as C5 inhibitors, BAFF inhibitors and DNase-1.

Take-home messages

AAV is a complex disorder with interactions between immune system and non-

MA



immune factors. 

Numerous studies are strengthening a pathogenic role of ANCA via activation of



ED

circulating primed neutrophils and damage the endothelium. Neutrophils play a central role in the pathophysiological process of AAV since they

PT

are both targets of ANCA as well as effector cells producing reactive oxygen species and enzyme degranulation, which are responsible for endothelial damage. Neutrophil extracellular traps and alternative complement pathway activation are

CE



emerging concepts in the pathogenesis of AAV. Adaptive immune cells seem to participate in AAV pathogenesis through insufficient

AC



regulation.

References [1]

[2] [3]

J.C. Jennette, R.J. Falk, P.A. Bacon, N. Basu, M.C. Cid, F. Ferrario, L.F. Flores-Suarez, W.L. Gross, L. Guillevin, E.C. Hagen, G.S. Hoffman, D.R. Jayne, C.G. Kallenberg, P. Lamprecht, C.A. Langford, R.A. Luqmani, A.D. Mahr, E.L. Matteson, P.A. Merkel, S. Ozen, C.D. Pusey, N. Rasmussen, A.J. Rees, D.G. Scott, U. Specks, J.H. Stone, K. Takahashi and R.A. Watts, 2012 revised International Chapel Hill Consensus Conference Nomenclature of Vasculitides, Arthritis Rheum 65 (2013) 1-11. C. Comarmond and P. Cacoub, Granulomatosis with polyangiitis (Wegener): clinical aspects and treatment, Autoimmun Rev 13 (2014) 1121-5. A. Greco, M.I. Rizzo, A. De Virgilio, A. Gallo, M. Fusconi, G. Ruoppolo, G. Altissimi and M. De Vincentiis, Churg-Strauss syndrome, Autoimmun Rev 14 (2015) 341-8. 18

ACCEPTED MANUSCRIPT

[10] [11]

[12]

[13] [14] [15] [16] [17] [18] [19]

PT

SC RI

NU

[9]

MA

[8]

ED

[7]

PT

[6]

CE

[5]

A. Greco, A. De Virgilio, M.I. Rizzo, A. Gallo, G. Magliulo, M. Fusconi, G. Ruoppolo, M. Tombolini, R. Turchetta and M. de Vincentiis, Microscopic polyangiitis: Advances in diagnostic and therapeutic approaches, Autoimmun Rev 14 (2015) 837-44. R.J. Falk and J.C. Jennette, Anti-neutrophil cytoplasmic autoantibodies with specificity for myeloperoxidase in patients with systemic vasculitis and idiopathic necrotizing and crescentic glomerulonephritis, N Engl J Med 318 (1988) 1651-7. D.E. Jenne, J. Tschopp, J. Ludemann, B. Utecht and W.L. Gross, Wegener's autoantigen decoded, Nature 346 (1990) 520. J.C. Jennette, J.R. Hoidal and R.J. Falk, Specificity of anti-neutrophil cytoplasmic autoantibodies for proteinase 3, Blood 75 (1990) 2263-4. R.J. Falk, R.S. Terrell, L.A. Charles and J.C. Jennette, Anti-neutrophil cytoplasmic autoantibodies induce neutrophils to degranulate and produce oxygen radicals in vitro, Proc Natl Acad Sci U S A 87 (1990) 4115-9. S.L. Nolan, N. Kalia, G.B. Nash, D. Kamel, P. Heeringa and C.O. Savage, Mechanisms of ANCA-mediated leukocyte-endothelial cell interactions in vivo, J Am Soc Nephrol 19 (2008) 973-84. V. Brinkmann, U. Reichard, C. Goosmann, B. Fauler, Y. Uhlemann, D.S. Weiss, Y. Weinrauch and A. Zychlinsky, Neutrophil extracellular traps kill bacteria, Science 303 (2004) 1532-5. M. Saffarzadeh, C. Juenemann, M.A. Queisser, G. Lochnit, G. Barreto, S.P. Galuska, J. Lohmeyer and K.T. Preissner, Neutrophil extracellular traps directly induce epithelial and endothelial cell death: a predominant role of histones, PLoS One 7 (2012) e32366. S. Sangaletti, C. Tripodo, C. Chiodoni, C. Guarnotta, B. Cappetti, P. Casalini, S. Piconese, M. Parenza, C. Guiducci, C. Vitali and M.P. Colombo, Neutrophil extracellular traps mediate transfer of cytoplasmic neutrophil antigens to myeloid dendritic cells toward ANCA induction and associated autoimmunity, Blood 120 (2012) 3007-18. M.D. Morgan, C.J. Day, K.P. Piper, N. Khan, L. Harper, P.A. Moss and C.O. Savage, Patients with Wegener's granulomatosis demonstrate a relative deficiency and functional impairment of T-regulatory cells, Immunology 130 (2010) 64-73. N. Dumoitier, B. Terrier, J. London, S. Lofek and L. Mouthon, Implication of B lymphocytes in the pathogenesis of ANCA-associated vasculitides, Autoimmun Rev 14 (2015) 996-1004. A. Schreiber, H. Xiao, J.C. Jennette, W. Schneider, F.C. Luft and R. Kettritz, C5a receptor mediates neutrophil activation and ANCA-induced glomerulonephritis, J Am Soc Nephrol 20 (2009) 289-98. D.J. Davies, J.E. Moran, J.F. Niall and G.B. Ryan, Segmental necrotising glomerulonephritis with antineutrophil antibody: possible arbovirus aetiology?, Br Med J (Clin Res Ed) 285 (1982) 606. F.J. van der Woude, Anticytoplasmic antibodies in Wegener's granulomatosis, Lancet 2 (1985) 48. D.J. Radford, N.T. Luu, P. Hewins, G.B. Nash and C.O. Savage, Antineutrophil cytoplasmic antibodies stabilize adhesion and promote migration of flowing neutrophils on endothelial cells, Arthritis Rheum 44 (2001) 2851-61. D.J. Schlieben, S.M. Korbet, R.E. Kimura, M.M. Schwartz and E.J. Lewis, Pulmonaryrenal syndrome in a newborn with placental transmission of ANCAs, Am J Kidney Dis 45 (2005) 758-61.

AC

[4]

19

ACCEPTED MANUSCRIPT

[25] [26]

[28]

[29] [30]

[31]

PT

AC

CE

[27]

SC RI

[24]

NU

[23]

MA

[22]

ED

[21]

H. Xiao, P. Heeringa, P. Hu, Z. Liu, M. Zhao, Y. Aratani, N. Maeda, R.J. Falk and J.C. Jennette, Antineutrophil cytoplasmic autoantibodies specific for myeloperoxidase cause glomerulonephritis and vasculitis in mice, J Clin Invest 110 (2002) 955-63. H. Xiao, P. Heeringa, Z. Liu, D. Huugen, P. Hu, N. Maeda, R.J. Falk and J.C. Jennette, The role of neutrophils in the induction of glomerulonephritis by antimyeloperoxidase antibodies, Am J Pathol 167 (2005) 39-45. B. Korkmaz, D.E. Jenne and F. Gauthier, Relevance of the mouse model as a therapeutic approach for neutrophil proteinase 3-associated human diseases, Int Immunopharmacol 17 (2013) 1198-205. V. Witko-Sarsat, P. Lesavre, S. Lopez, G. Bessou, C. Hieblot, B. Prum, L.H. Noel, L. Guillevin, P. Ravaud, I. Sermet-Gaudelus, J. Timsit, J.P. Grunfeld and L. HalbwachsMecarelli, A large subset of neutrophils expressing membrane proteinase 3 is a risk factor for vasculitis and rheumatoid arthritis, J Am Soc Nephrol 10 (1999) 1224-33. O. Wiesner, R.D. Litwiller, A.M. Hummel, M.A. Viss, C.J. McDonald, D.E. Jenne, D.N. Fass and U. Specks, Differences between human proteinase 3 and neutrophil elastase and their murine homologues are relevant for murine model experiments, FEBS Lett 579 (2005) 5305-12. V.C. Primo, S. Marusic, C.C. Franklin, W.H. Goldmann, C.G. Achaval, R.N. Smith, M.A. Arnaout and B. Nikolic, Anti-PR3 immune responses induce segmental and necrotizing glomerulonephritis, Clin Exp Immunol 159 (2010) 327-37. M.A. Little, B. Al-Ani, S. Ren, H. Al-Nuaimi, M. Leite, Jr., C.E. Alpers, C.O. Savage and J.S. Duffield, Anti-proteinase 3 anti-neutrophil cytoplasm autoantibodies recapitulate systemic vasculitis in mice with a humanized immune system, PLoS One 7 (2012) e28626. P.A. Lyons, T.F. Rayner, S. Trivedi, J.U. Holle, R.A. Watts, D.R. Jayne, B. Baslund, P. Brenchley, A. Bruchfeld, A.N. Chaudhry, J.W. Cohen Tervaert, P. Deloukas, C. Feighery, W.L. Gross, L. Guillevin, I. Gunnarsson, L. Harper, Z. Hruskova, M.A. Little, D. Martorana, T. Neumann, S. Ohlsson, S. Padmanabhan, C.D. Pusey, A.D. Salama, J.S. Sanders, C.O. Savage, M. Segelmark, C.A. Stegeman, V. Tesar, A. Vaglio, S. Wieczorek, B. Wilde, J. Zwerina, A.J. Rees, D.G. Clayton and K.G. Smith, Genetically distinct subsets within ANCA-associated vasculitis, N Engl J Med 367 (2012) 214-23. G. Xie, D. Roshandel, R. Sherva, P.A. Monach, E.Y. Lu, T. Kung, K. Carrington, S.S. Zhang, S.L. Pulit, S. Ripke, S. Carette, P.F. Dellaripa, J.C. Edberg, G.S. Hoffman, N. Khalidi, C.A. Langford, A.D. Mahr, E.W. St Clair, P. Seo, U. Specks, R.F. Spiera, J.H. Stone, S.R. Ytterberg, S. Raychaudhuri, P.I. de Bakker, L.A. Farrer, C.I. Amos, P.A. Merkel and K.A. Siminovitch, Association of granulomatosis with polyangiitis (Wegener's) with HLA-DPB1*04 and SEMA6A gene variants: evidence from genome-wide analysis, Arthritis Rheum 65 (2013) 2457-68. Z. Cui, M.H. Zhao, M. Segelmark and T. Hellmark, Natural autoantibodies to myeloperoxidase, proteinase 3, and the glomerular basement membrane are present in normal individuals, Kidney Int 78 (2010) 590-7. P.C. Xu, Z. Cui, M. Chen, T. Hellmark and M.H. Zhao, Comparison of characteristics of natural autoantibodies against myeloperoxidase and anti-myeloperoxidase autoantibodies from patients with microscopic polyangiitis, Rheumatology (Oxford) 50 (2011) 1236-43. J. Savige, W. Dimech, M. Fritzler, J. Goeken, E.C. Hagen, J.C. Jennette, R. McEvoy, C. Pusey, W. Pollock, M. Trevisin, A. Wiik and R. Wong, Addendum to the International Consensus Statement on testing and reporting of antineutrophil

PT

[20]

20

ACCEPTED MANUSCRIPT

[37] [38] [39] [40] [41] [42] [43]

[44]

[45]

PT

SC RI

NU

MA

[36]

ED

[35]

PT

[34]

CE

[33]

AC

[32]

cytoplasmic antibodies. Quality control guidelines, comments, and recommendations for testing in other autoimmune diseases, Am J Clin Pathol 120 (2003) 312-8. C.J. Ooi, B.L. Lim, W.K. Cheong, A.E. Ling and H.S. Ng, Antineutrophil cytoplasmic antibodies (ANCAs) in patients with inflammatory bowel disease show no correlation with proteinase 3, lactoferrin, myeloperoxidase, elastase, cathepsin G and lysozyme: a Singapore study, Ann Acad Med Singapore 29 (2000) 704-7. H.J. Chin, C. Ahn, C.S. Lim, H.K. Chung, J.G. Lee, Y.W. Song, H.S. Lee, J.S. Han, S. Kim and J.S. Lee, Clinical implications of antineutrophil cytoplasmic antibody test in lupus nephritis, Am J Nephrol 20 (2000) 57-63. A.J. Roth, J.D. Ooi, J.J. Hess, M.M. van Timmeren, E.A. Berg, C.E. Poulton, J. McGregor, M. Burkart, S.L. Hogan, Y. Hu, W. Winnik, P.H. Nachman, C.A. Stegeman, J. Niles, P. Heeringa, A.R. Kitching, S. Holdsworth, J.C. Jennette, G.A. Preston and R.J. Falk, Epitope specificity determines pathogenicity and detectability in ANCAassociated vasculitis, J Clin Invest 123 (2013) 1773-83. S.J. Gou, P.C. Xu, M. Chen and M.H. Zhao, Epitope analysis of anti-myeloperoxidase antibodies in patients with ANCA-associated vasculitis, PLoS One 8 (2013) e60530. N. Agmon-Levin, M. Blank, Z. Paz and Y. Shoenfeld, Molecular mimicry in systemic lupus erythematosus, Lupus 18 (2009) 1181-5. J.R. Heal, G.W. Roberts, J.G. Raynes, A. Bhakoo and A.D. Miller, Specific interactions between sense and complementary peptides: the basis for the proteomic code, Chembiochem 3 (2002) 136-51. A.D. Miller, Sense-antisense (complementary) peptide interactions and the proteomic code; potential opportunities in biology and pharmaceutical science, Expert Opin Biol Ther 15 (2015) 245-67. W.F. Pendergraft, 3rd, G.A. Preston, R.R. Shah, A. Tropsha, C.W. Carter, Jr., J.C. Jennette and R.J. Falk, Autoimmunity is triggered by cPR-3(105-201), a protein complementary to human autoantigen proteinase-3, Nat Med 10 (2004) 72-9. D.J. Pudifin, J. Duursma, V. Gathiram and T.F. Jackson, Invasive amoebiasis is associated with the development of anti-neutrophil cytoplasmic antibody, Clin Exp Immunol 97 (1994) 48-51. E.R. Popa, C.A. Stegeman, C.G. Kallenberg and J.W. Tervaert, Staphylococcus aureus and Wegener's granulomatosis, Arthritis Res 4 (2002) 77-9. H. Tadema, C.G. Kallenberg, C.A. Stegeman and P. Heeringa, Reactivity against complementary proteinase-3 is not increased in patients with PR3-ANCAassociated vasculitis, PLoS One 6 (2011) e17972. R. Kain, M. Exner, R. Brandes, R. Ziebermayr, D. Cunningham, C.A. Alderson, A. Davidovits, I. Raab, R. Jahn, O. Ashour, S. Spitzauer, G. Sunder-Plassmann, M. Fukuda, P. Klemm, A.J. Rees and D. Kerjaschki, Molecular mimicry in pauciimmune focal necrotizing glomerulonephritis, Nat Med 14 (2008) 1088-96. A.J. Roth, M.C. Brown, R.N. Smith, A.K. Badhwar, O. Parente, H. Chung, D.O. Bunch, J.G. McGregor, S.L. Hogan, Y. Hu, J.J. Yang, E.A. Berg, J. Niles, J.C. Jennette, G.A. Preston and R.J. Falk, Anti-LAMP-2 antibodies are not prevalent in patients with antineutrophil cytoplasmic autoantibody glomerulonephritis, J Am Soc Nephrol 23 (2012) 545-55. K. Takeda and S. Akira, Toll-like receptors in innate immunity, Int Immunol 17 (2005) 1-14.

21

ACCEPTED MANUSCRIPT

[52] [53] [54] [55]

[56] [57] [58]

[59]

[60]

PT

SC RI

NU

[51]

MA

[50]

ED

[49]

PT

[48]

CE

[47]

H. Tadema, P. Heeringa and C.G. Kallenberg, Bacterial infections in Wegener's granulomatosis: mechanisms potentially involved in autoimmune pathogenesis, Curr Opin Rheumatol 23 (2011) 366-71. J.U. Holle, M. Windmoller, C. Lange, W.L. Gross, K. Herlyn and E. Csernok, Toll-like receptor TLR2 and TLR9 ligation triggers neutrophil activation in granulomatosis with polyangiitis, Rheumatology (Oxford) 52 (2013) 1183-9. C.A. Husmann, J.U. Holle, F. Moosig, S. Mueller, B. Wilde, J.W. Cohen Tervaert, L. Harper, G. Assmann, W.L. Gross, J.T. Epplen and S. Wieczorek, Genetics of toll like receptor 9 in ANCA associated vasculitides, Ann Rheum Dis 73 (2014) 890-6. M. Radic, D. Martinovic Kaliterna and J. Radic, Drug-induced vasculitis: a clinical and pathological review, Neth J Med 70 (2012) 12-7. E. De la Cruz-Hernandez, C. Perez-Plasencia, E. Perez-Cardenas, A. GonzalezFierro, C. Trejo-Becerril, A. Chavez-Blanco, L. Taja-Chayeb, S. Vidal, O. Gutierrez, G.I. Dominguez, J.E. Trujillo and A. Duenas-Gonzalez, Transcriptional changes induced by epigenetic therapy with hydralazine and magnesium valproate in cervical carcinoma, Oncol Rep 25 (2011) 399-407. W.F. Pendergraft, 3rd and J.L. Niles, Trojan horses: drug culprits associated with antineutrophil cytoplasmic autoantibody (ANCA) vasculitis, Curr Opin Rheumatol 26 (2014) 42-9. L. Waldhauser and J. Uetrecht, Antibodies to myeloperoxidase in propylthiouracil-induced autoimmune disease in the cat, Toxicology 114 (1996) 155-62. S. Bjorck, C. Brundin, E. Lorinc, K.F. Lynch and D. Agardh, Screening detects a high proportion of celiac disease in young HLA-genotyped children, J Pediatr Gastroenterol Nutr 50 (2010) 49-53. L.M. Sollid, W. Pos and K.W. Wucherpfennig, Molecular mechanisms for contribution of MHC molecules to autoimmune diseases, Curr Opin Immunol 31 (2014) 24-30. D. Reumaux, P.L. Hordijk, P. Duthilleul and D. Roos, Priming by tumor necrosis factor-alpha of human neutrophil NADPH-oxidase activity induced by antiproteinase-3 or anti-myeloperoxidase antibodies, J Leukoc Biol 80 (2006) 142433. Y. Aida and M.J. Pabst, Priming of neutrophils by lipopolysaccharide for enhanced release of superoxide. Requirement for plasma but not for tumor necrosis factoralpha, J Immunol 145 (1990) 3017-25. P. Hewins, M.D. Morgan, N. Holden, D. Neil, J.M. Williams, C.O. Savage and L. Harper, IL-18 is upregulated in the kidney and primes neutrophil responsiveness in ANCA-associated vasculitis, Kidney Int 69 (2006) 605-15. C. Wang, H. Wang, D.Y. Chang, J. Hao, M.H. Zhao and M. Chen, High mobility group box 1 contributes to anti-neutrophil cytoplasmic antibody-induced neutrophils activation through receptor for advanced glycation end products (RAGE) and Toll-like receptor 4, Arthritis Res Ther 17 (2015) 64. D. Reumaux, P.J. Vossebeld, D. Roos and A.J. Verhoeven, Effect of tumor necrosis factor-induced integrin activation on Fc gamma receptor II-mediated signal transduction: relevance for activation of neutrophils by anti-proteinase 3 or antimyeloperoxidase antibodies, Blood 86 (1995) 3189-95. A. Mavropoulos, T. Orfanidou, C. Liaskos, D.S. Smyk, C. Billinis, M. Blank, E.I. Rigopoulou and D.P. Bogdanos, p38 mitogen-activated protein kinase (p38 MAPK)-mediated autoimmunity: lessons to learn from ANCA vasculitis and pemphigus vulgaris, Autoimmun Rev 12 (2013) 580-90.

AC

[46]

22

ACCEPTED MANUSCRIPT

[67] [68]

[69]

[70]

[71] [72] [73]

[74]

PT

SC RI

NU

[66]

MA

[65]

ED

[64]

PT

[63]

CE

[62]

J. Hao, L.Q. Meng, P.C. Xu, M. Chen and M.H. Zhao, p38MAPK, ERK and PI3K signaling pathways are involved in C5a-primed neutrophils for ANCA-mediated activation, PLoS One 7 (2012) e38317. A.P. van Rossum, A.A. Rarok, M.G. Huitema, G. Fassina, P.C. Limburg and C.G. Kallenberg, Constitutive membrane expression of proteinase 3 (PR3) and neutrophil activation by anti-PR3 antibodies, J Leukoc Biol 76 (2004) 1162-70. A.A. Rarok, C.A. Stegeman, P.C. Limburg and C.G. Kallenberg, Neutrophil membrane expression of proteinase 3 (PR3) is related to relapse in PR3-ANCAassociated vasculitis, J Am Soc Nephrol 13 (2002) 2232-8. A. Schreiber, F.C. Luft and R. Kettritz, Membrane proteinase 3 expression and ANCA-induced neutrophil activation, Kidney Int 65 (2004) 2172-83. U. Jerke, S. Rolle, G. Dittmar, B. Bayat, S. Santoso, A. Sporbert, F. Luft and R. Kettritz, Complement receptor Mac-1 is an adaptor for NB1 (CD177)-mediated PR3-ANCA neutrophil activation, J Biol Chem 286 (2011) 7070-81. B. Bayat, S. Werth, U.J. Sachs, D.K. Newman, P.J. Newman and S. Santoso, Neutrophil transmigration mediated by the neutrophil-specific antigen CD177 is influenced by the endothelial S536N dimorphism of platelet endothelial cell adhesion molecule-1, J Immunol 184 (2010) 3889-96. C.J. Kuckleburg, S.B. Tilkens, S. Santoso and P.J. Newman, Proteinase 3 contributes to transendothelial migration of NB1-positive neutrophils, J Immunol 188 (2012) 2419-26. N. Hu, J. Westra, M.G. Huitema, M. Bijl, E. Brouwer, C.A. Stegeman, P. Heeringa, P.C. Limburg and C.G. Kallenberg, Coexpression of CD177 and membrane proteinase 3 on neutrophils in antineutrophil cytoplasmic autoantibody-associated systemic vasculitis: anti-proteinase 3-mediated neutrophil activation is independent of the role of CD177-expressing neutrophils, Arthritis Rheum 60 (2009) 1548-57. D.J. Ciavatta, J. Yang, G.A. Preston, A.K. Badhwar, H. Xiao, P. Hewins, C.M. Nester, W.F. Pendergraft, 3rd, T.R. Magnuson, J.C. Jennette and R.J. Falk, Epigenetic basis for aberrant upregulation of autoantigen genes in humans with ANCA vasculitis, J Clin Invest 120 (2010) 3209-19. E.A. McInnis, A.K. Badhwar, A. Muthigi, O.M. Lardinois, S.C. Allred, J. Yang, M.E. Free, J.C. Jennette, G.A. Preston, R.J. Falk and D.J. Ciavatta, Dysregulation of autoantigen genes in ANCA-associated vasculitis involves alternative transcripts and new protein synthesis, J Am Soc Nephrol 26 (2015) 390-9. A.J. Porges, P.B. Redecha, W.T. Kimberly, E. Csernok, W.L. Gross and R.P. Kimberly, Anti-neutrophil cytoplasmic antibodies engage and activate human neutrophils via Fc gamma RIIa, J Immunol 153 (1994) 1271-80. M. Kocher, M.E. Siegel, J.C. Edberg and R.P. Kimberly, Cross-linking of Fc gamma receptor IIa and Fc gamma receptor IIIb induces different proadhesive phenotypes on human neutrophils, J Immunol 159 (1997) 3940-8. J.M. Williams, A. Ben-Smith, P. Hewins, S.K. Dove, P. Hughes, R. McEwan, M.J. Wakelam and C.O. Savage, Activation of the G(i) heterotrimeric G protein by ANCA IgG F(ab')2 fragments is necessary but not sufficient to stimulate the recruitment of those downstream mediators used by intact ANCA IgG, J Am Soc Nephrol 14 (2003) 661-9. J.D. Ooi, P.Y. Gan, T. Chen, P.J. Eggenhuizen, J. Chang, M.A. Alikhan, D. Odobasic, S.R. Holdsworth and A.R. Kitching, FcgammaRIIB regulates T-cell autoreactivity, ANCA production, and neutrophil activation to suppress anti-myeloperoxidase glomerulonephritis, Kidney Int 86 (2014) 1140-9.

AC

[61]

23

ACCEPTED MANUSCRIPT

[81] [82] [83]

[84]

[85] [86]

[87] [88] [89]

PT

SC RI

NU

[80]

MA

[79]

ED

[78]

PT

[77]

CE

[76]

M.M. van Timmeren, B.S. van der Veen, C.A. Stegeman, A.H. Petersen, T. Hellmark, M. Collin and P. Heeringa, IgG glycan hydrolysis attenuates ANCA-mediated glomerulonephritis, J Am Soc Nephrol 21 (2010) 1103-14. A. Schreiber, C.T. Pham, Y. Hu, W. Schneider, F.C. Luft and R. Kettritz, Neutrophil serine proteases promote IL-1beta generation and injury in necrotizing crescentic glomerulonephritis, J Am Soc Nephrol 23 (2012) 470-82. R.J. Johnson, W.G. Couser, E.Y. Chi, S. Adler and S.J. Klebanoff, New mechanism for glomerular injury. Myeloperoxidase-hydrogen peroxide-halide system, J Clin Invest 79 (1987) 1379-87. A. Schreiber, F.C. Luft and R. Kettritz, Phagocyte NADPH oxidase restrains the inflammasome in ANCA-induced GN, J Am Soc Nephrol 26 (2015) 411-24. A. Millet, K.R. Martin, F. Bonnefoy, P. Saas, J. Mocek, M. Alkan, B. Terrier, A. Kerstein, N. Tamassia, S.K. Satyanarayanan, A. Ariel, J.A. Ribeil, L. Guillevin, M.A. Cassatella, A. Mueller, N. Thieblemont, P. Lamprecht, L. Mouthon, S. Perruche and V. Witko-Sarsat, Proteinase 3 on apoptotic cells disrupts immune silencing in autoimmune vasculitis, J Clin Invest 125 (2015) 4107-21. S. Brachemi, A. Mambole, F. Fakhouri, L. Mouthon, L. Guillevin, P. Lesavre and L. Halbwachs-Mecarelli, Increased membrane expression of proteinase 3 during neutrophil adhesion in the presence of anti proteinase 3 antibodies, J Am Soc Nephrol 18 (2007) 2330-9. A. Rahman and F. Fazal, Hug tightly and say goodbye: role of endothelial ICAM-1 in leukocyte transmigration, Antioxid Redox Signal 11 (2009) 823-39. C.O. Savage, G. Gaskin, C.D. Pusey and J.D. Pearson, Anti-neutrophil cytoplasm antibodies can recognize vascular endothelial cell-bound anti-neutrophil cytoplasm antibody-associated autoantigens, Exp Nephrol 1 (1993) 190-5. S. Weidner, M. Carl, R. Riess and H.D. Rupprecht, Histologic analysis of renal leukocyte infiltration in antineutrophil cytoplasmic antibody-associated vasculitis: importance of monocyte and neutrophil infiltration in tissue damage, Arthritis Rheum 50 (2004) 3651-7. R.M. Tarzi, J. Liu, S. Schneiter, N.R. Hill, T.H. Page, H.T. Cook, C.D. Pusey and K.J. Woollard, CD14 expression is increased on monocytes in patients with antineutrophil cytoplasm antibody (ANCA)-associated vasculitis and correlates with the expression of ANCA autoantigens, Clin Exp Immunol 181 (2015) 65-75. S. Weidner, W. Neupert, M. Goppelt-Struebe and H.D. Rupprecht, Antineutrophil cytoplasmic antibodies induce human monocytes to produce oxygen radicals in vitro, Arthritis Rheum 44 (2001) 1698-706. E.C. O'Brien, W.H. Abdulahad, A. Rutgers, M.G. Huitema, V.P. O'Reilly, A.M. Coughlan, M. Harrington, P. Heeringa, M.A. Little and F.B. Hickey, Intermediate monocytes in ANCA vasculitis: increased surface expression of ANCA autoantigens and IL-1beta secretion in response to anti-MPO antibodies, Sci Rep 5 (2015) 11888. B. Pinegin, N. Vorobjeva and V. Pinegin, Neutrophil extracellular traps and their role in the development of chronic inflammation and autoimmunity, Autoimmun Rev (2015). K. Kessenbrock, M. Krumbholz, U. Schonermarck, W. Back, W.L. Gross, Z. Werb, H.J. Grone, V. Brinkmann and D.E. Jenne, Netting neutrophils in autoimmune small-vessel vasculitis, Nat Med 15 (2009) 623-5. D. Nakazawa, U. Tomaru, A. Suzuki, S. Masuda, R. Hasegawa, T. Kobayashi, S. Nishio, M. Kasahara and A. Ishizu, Abnormal conformation and impaired degradation of propylthiouracil-induced neutrophil extracellular traps:

AC

[75]

24

ACCEPTED MANUSCRIPT

AC

CE

PT

ED

MA

NU

SC RI

PT

implications of disordered neutrophil extracellular traps in a rat model of myeloperoxidase antineutrophil cytoplasmic antibody-associated vasculitis, Arthritis Rheum 64 (2012) 3779-87. [90] D. Nakazawa, H. Shida, U. Tomaru, M. Yoshida, S. Nishio, T. Atsumi and A. Ishizu, Enhanced Formation and Disordered Regulation of NETs in MyeloperoxidaseANCA-Associated Microscopic Polyangiitis, J Am Soc Nephrol 25 (2014) 990-7. [91] T.A. Fuchs, A. Brill, D. Duerschmied, D. Schatzberg, M. Monestier, D.D. Myers, Jr., S.K. Wrobleski, T.W. Wakefield, J.H. Hartwig and D.D. Wagner, Extracellular DNA traps promote thrombosis, Proc Natl Acad Sci U S A 107 (2010) 15880-5. [92] M.L. von Bruhl, K. Stark, A. Steinhart, S. Chandraratne, I. Konrad, M. Lorenz, A. Khandoga, A. Tirniceriu, R. Coletti, M. Kollnberger, R.A. Byrne, I. Laitinen, A. Walch, A. Brill, S. Pfeiler, D. Manukyan, S. Braun, P. Lange, J. Riegger, J. Ware, A. Eckart, S. Haidari, M. Rudelius, C. Schulz, K. Echtler, V. Brinkmann, M. Schwaiger, K.T. Preissner, D.D. Wagner, N. Mackman, B. Engelmann and S. Massberg, Monocytes, neutrophils, and platelets cooperate to initiate and propagate venous thrombosis in mice in vivo, J Exp Med 209 (2012) 819-35. [93] D. Nakazawa, U. Tomaru, C. Yamamoto, S. Jodo and A. Ishizu, Abundant neutrophil extracellular traps in thrombus of patient with microscopic polyangiitis, Front Immunol 3 (2012) 333. [94] J. Voswinkel, A. Mueller, J.A. Kraemer, P. Lamprecht, K. Herlyn, K. Holl-Ulrich, A.C. Feller, S. Pitann, A. Gause and W.L. Gross, B lymphocyte maturation in Wegener's granulomatosis: a comparative analysis of VH genes from endonasal lesions, Ann Rheum Dis 65 (2006) 859-64. [95] J.H. Stone, P.A. Merkel, R. Spiera, P. Seo, C.A. Langford, G.S. Hoffman, C.G. Kallenberg, E.W. St Clair, A. Turkiewicz, N.K. Tchao, L. Webber, L. Ding, L.P. Sejismundo, K. Mieras, D. Weitzenkamp, D. Ikle, V. Seyfert-Margolis, M. Mueller, P. Brunetta, N.B. Allen, F.C. Fervenza, D. Geetha, K.A. Keogh, E.Y. Kissin, P.A. Monach, T. Peikert, C. Stegeman, S.R. Ytterberg and U. Specks, Rituximab versus cyclophosphamide for ANCA-associated vasculitis, N Engl J Med 363 (2010) 22132. [96] L. Guillevin, C. Pagnoux, A. Karras, C. Khouatra, O. Aumaitre, P. Cohen, F. Maurier, O. Decaux, J. Ninet, P. Gobert, T. Quemeneur, C. Blanchard-Delaunay, P. Godmer, X. Puechal, P.L. Carron, P.Y. Hatron, N. Limal, M. Hamidou, M. Ducret, E. Daugas, T. Papo, B. Bonnotte, A. Mahr, P. Ravaud and L. Mouthon, Rituximab versus azathioprine for maintenance in ANCA-associated vasculitis, N Engl J Med 371 (2014) 1771-80. [97] E.R. Popa, C.A. Stegeman, N.A. Bos, C.G. Kallenberg and J.W. Tervaert, Differential B- and T-cell activation in Wegener's granulomatosis, J Allergy Clin Immunol 103 (1999) 885-94. [98] D.A. Culton, M.W. Nicholas, D.O. Bunch, Q.L. Zhen, T.B. Kepler, M.A. Dooley, C. Mohan, P.H. Nachman and S.H. Clarke, Similar CD19 dysregulation in two autoantibody-associated autoimmune diseases suggests a shared mechanism of B-cell tolerance loss, J Clin Immunol 27 (2007) 53-68. [99] T. Dorner, C. Giesecke and P.E. Lipsky, Mechanisms of B cell autoimmunity in SLE, Arthritis Res Ther 13 (2011) 243. [100] C. Mauri, Regulation of immunity and autoimmunity by B cells, Curr Opin Immunol 22 (2010) 761-7. [101] F. Flores-Borja, A. Bosma, D. Ng, V. Reddy, M.R. Ehrenstein, D.A. Isenberg and C. Mauri, CD19+CD24hiCD38hi B cells maintain regulatory T cells while limiting TH1 and TH17 differentiation, Sci Transl Med 5 (2013) 173ra23. 25

ACCEPTED MANUSCRIPT

AC

CE

PT

ED

MA

NU

SC RI

PT

[102] M.W. Klinker and S.K. Lundy, Multiple mechanisms of immune suppression by B lymphocytes, Mol Med 18 (2012) 123-37. [103] S.K. Todd, R.J. Pepper, J. Draibe, A. Tanna, C.D. Pusey, C. Mauri and A.D. Salama, Regulatory B cells are numerically but not functionally deficient in antineutrophil cytoplasm antibody-associated vasculitis, Rheumatology (Oxford) 53 (2014) 1693-703. [104] N. Lepse, W.H. Abdulahad, A. Rutgers, C.G. Kallenberg, C.A. Stegeman and P. Heeringa, Altered B cell balance, but unaffected B cell capacity to limit monocyte activation in anti-neutrophil cytoplasmic antibody-associated vasculitis in remission, Rheumatology (Oxford) 53 (2014) 1683-92. [105] B. Wilde, M. Thewissen, J. Damoiseaux, S. Knippenberg, M. Hilhorst, P. van Paassen, O. Witzke and J.W. Cohen Tervaert, Regulatory B cells in ANCAassociated vasculitis, Ann Rheum Dis 72 (2013) 1416-9. [106] S. Unizony, N. Lim, D.J. Phippard, V.J. Carey, E.M. Miloslavsky, N.K. Tchao, D. Ikle, A.L. Asare, P.A. Merkel, P.A. Monach, P. Seo, E.W. St Clair, C.A. Langford, R. Spiera, G.S. Hoffman, C.G. Kallenberg, U. Specks and J.H. Stone, Peripheral CD5+ B cells in antineutrophil cytoplasmic antibody-associated vasculitis, Arthritis Rheumatol 67 (2015) 535-44. [107] A. Muller, A. Trabandt, K. Gloeckner-Hofmann, U. Seitzer, E. Csernok, U. Schonermarck, A.C. Feller and W.L. Gross, Localized Wegener's granulomatosis: predominance of CD26 and IFN-gamma expression, J Pathol 192 (2000) 113-20. [108] J.S. Sanders, M.G. Huitma, C.G. Kallenberg and C.A. Stegeman, Plasma levels of soluble interleukin 2 receptor, soluble CD30, interleukin 10 and B cell activator of the tumour necrosis factor family during follow-up in vasculitis associated with proteinase 3-antineutrophil cytoplasmic antibodies: associations with disease activity and relapse, Ann Rheum Dis 65 (2006) 1484-9. [109] U. Schonermarck, E. Csernok, A. Trabandt, H. Hansen and W.L. Gross, Circulating cytokines and soluble CD23, CD26 and CD30 in ANCA-associated vasculitides, Clin Exp Rheumatol 18 (2000) 457-63. [110] G. Wang, H. Hansen, E. Tatsis, E. Csernok, H. Lemke and W.L. Gross, High plasma levels of the soluble form of CD30 activation molecule reflect disease activity in patients with Wegener's granulomatosis, Am J Med 102 (1997) 517-23. [111] J.D. Ooi, A.R. Kitching and S.R. Holdsworth, Review: T helper 17 cells: their role in glomerulonephritis, Nephrology (Carlton) 15 (2010) 513-21. [112] A. Hoshino, T. Nagao, N. Nagi-Miura, N. Ohno, M. Yasuhara, K. Yamamoto, T. Nakayama and K. Suzuki, MPO-ANCA induces IL-17 production by activated neutrophils in vitro via classical complement pathway-dependent manner, J Autoimmun 31 (2008) 79-89. [113] P.Y. Gan, O.M. Steinmetz, D.S. Tan, K.M. O'Sullivan, J.D. Ooi, Y. Iwakura, A.R. Kitching and S.R. Holdsworth, Th17 cells promote autoimmune antimyeloperoxidase glomerulonephritis, J Am Soc Nephrol 21 (2010) 925-31. [114] J.D. Fontenot, M.A. Gavin and A.Y. Rudensky, Foxp3 programs the development and function of CD4+CD25+ regulatory T cells, Nat Immunol 4 (2003) 330-6. [115] W.H. Abdulahad, C.A. Stegeman, Y.M. van der Geld, B. Doornbos-van der Meer, P.C. Limburg and C.G. Kallenberg, Functional defect of circulating regulatory CD4+ T cells in patients with Wegener's granulomatosis in remission, Arthritis Rheum 56 (2007) 2080-91. [116] M. Rimbert, M. Hamidou, C. Braudeau, X. Puechal, L. Teixeira, H. Caillon, A. Neel, M. Audrain, L. Guillevin and R. Josien, Decreased numbers of blood dendritic cells

26

ACCEPTED MANUSCRIPT

[122] [123] [124] [125] [126] [127] [128]

[129]

[130]

PT

SC RI

NU

MA

[121]

ED

[120]

PT

[119]

CE

[118]

AC

[117]

and defective function of regulatory T cells in antineutrophil cytoplasmic antibody-associated vasculitis, PLoS One 6 (2011) e18734. M.E. Free, D.O. Bunch, J.A. McGregor, B.E. Jones, E.A. Berg, S.L. Hogan, Y. Hu, G.A. Preston, J.C. Jennette, R.J. Falk and M.A. Su, Patients with antineutrophil cytoplasmic antibody-associated vasculitis have defective Treg cell function exacerbated by the presence of a suppression-resistant effector cell population, Arthritis Rheum 65 (2013) 1922-33. W.H. Abdulahad, C.G. Kallenberg, P.C. Limburg and C.A. Stegeman, Urinary CD4+ effector memory T cells reflect renal disease activity in antineutrophil cytoplasmic antibody-associated vasculitis, Arthritis Rheum 60 (2009) 2830-8. P. Scapini, F. Bazzoni and M.A. Cassatella, Regulation of B-cell-activating factor (BAFF)/B lymphocyte stimulator (BLyS) expression in human neutrophils, Immunol Lett 116 (2008) 1-6. M. Krumbholz, U. Specks, M. Wick, S.L. Kalled, D. Jenne and E. Meinl, BAFF is elevated in serum of patients with Wegener's granulomatosis, J Autoimmun 25 (2005) 298-302. M. Nagai, K. Hirayama, I. Ebihara, H. Shimohata, M. Kobayashi and A. Koyama, Serum levels of BAFF and APRIL in myeloperoxidase anti-neutrophil cytoplasmic autoantibody-associated renal vasculitis: association with disease activity, Nephron Clin Pract 118 (2011) c339-45. G. Xin, M. Chen, Y. Su, L.X. Xu, M.H. Zhao and K.S. Li, Serum B-cell activating factor in myeloperoxiase-antineutrophil cytoplasmic antibodies-associated vasculitis, Am J Med Sci 348 (2014) 25-9. A. Lenert and P. Lenert, Current and emerging treatment options for ANCAassociated vasculitis: potential role of belimumab and other BAFF/APRIL targeting agents, Drug Des Devel Ther 9 (2015) 333-47. C. Rahmattulla, J.A. Bruijn and I.M. Bajema, Histopathological classification of antineutrophil cytoplasmic antibody-associated glomerulonephritis: an update, Curr Opin Nephrol Hypertens 23 (2014) 224-31. P.M. Lutalo and D.P. D'Cruz, Diagnosis and classification of granulomatosis with polyangiitis (aka Wegener's granulomatosis), J Autoimmun 48-49 (2014) 94-8. M. Haas and J.A. Eustace, Immune complex deposits in ANCA-associated crescentic glomerulonephritis: a study of 126 cases, Kidney Int 65 (2004) 214552. H. Xiao, A. Schreiber, P. Heeringa, R.J. Falk and J.C. Jennette, Alternative complement pathway in the pathogenesis of disease mediated by anti-neutrophil cytoplasmic autoantibodies, Am J Pathol 170 (2007) 52-64. D. Huugen, H. Xiao, A. van Esch, R.J. Falk, C.J. Peutz-Kootstra, W.A. Buurman, J.W. Tervaert, J.C. Jennette and P. Heeringa, Aggravation of anti-myeloperoxidase antibody-induced glomerulonephritis by bacterial lipopolysaccharide: role of tumor necrosis factor-alpha, Am J Pathol 167 (2005) 47-58. H. Xiao, D.J. Dairaghi, J.P. Powers, L.S. Ertl, T. Baumgart, Y. Wang, L.C. Seitz, M.E. Penfold, L. Gan, P. Hu, B. Lu, N.P. Gerard, C. Gerard, T.J. Schall, J.C. Jaen, R.J. Falk and J.C. Jennette, C5a receptor (CD88) blockade protects against MPO-ANCA GN, J Am Soc Nephrol 25 (2014) 225-31. S.J. Gou, J. Yuan, M. Chen, F. Yu and M.H. Zhao, Circulating complement activation in patients with anti-neutrophil cytoplasmic antibody-associated vasculitis, Kidney Int 83 (2013) 129-37.

27

ACCEPTED MANUSCRIPT

AC

CE

PT

ED

MA

NU

SC RI

PT

[131] S.F. Chen, F.M. Wang, Z.Y. Li, F. Yu, M.H. Zhao and M. Chen, Plasma complement factor H is associated with disease activity of patients with ANCA-associated vasculitis, Arthritis Res Ther 17 (2015) 129. [132] L. Camous, L. Roumenina, S. Bigot, S. Brachemi, V. Fremeaux-Bacchi, P. Lesavre and L. Halbwachs-Mecarelli, Complement alternative pathway acts as a positive feedback amplification of neutrophil activation, Blood 117 (2011) 1340-9. [133] H. Wang, C. Wang, M.H. Zhao and M. Chen, Neutrophil extracellular traps can activate alternative complement pathways, Clin Exp Immunol 181 (2015) 51827.

28

PT

ED

MA

NU

SC RI

PT

ACCEPTED MANUSCRIPT

CE

Figure 1: Main hypothesis concerning ANCA generation. The “autoantigen complementary peptide” theory is based on an anti-idiotype immune

AC

response from the complementary peptide PR3 (C-PR3), which leads to the production of autoantibodies against the original peptide PR3 (PR3). C-PR3 may emerge from the transcription of endogenous antisense strand of deoxyribonucleic acid (DNA), or could be a mimic of an antisense peptide. Molecular mimicry is also implicated in another theory, with a sequence homology between bacterial adhesin (FimH) and Lysosomal membrane positive-2 (LAMP-2) leading to an immune response to LAMP-2. The binding of anti-PR3 and anti-LAMP-2 antibodies to autoantigens targets, result in neutrophil activation.

29

CE

PT

ED

MA

NU

SC RI

PT

ACCEPTED MANUSCRIPT

Figure 2: Main mechanisms explaining ANCA-induced neutrophil activation.

AC

The priming of neutrophils by different inflammatory stimuli results in a pre-activation state with expression of ANCA antigens on the cell surface. Full neutrophil activation requires both FCγR engagement by ANCA complexed to antigens and Fab’2 binding to auto-antigens on neutrophil surface. ANCA-activated neutrophils undergo a respiratory burst, a degranulation of toxic granules, a diapedesis and adhesion to endothelium, leading to fibrinoid necrosis. The release of neutrophil serine protease (NSP) activates caspase-1-independent IL-1β production, whereas the respiratory burst performs a negative feedback on caspase-1 dependent generation. Activated neutrophils also generate NETs, which participate to endothelial cell damage, and may trigger adaptive immunity. Neutrophils play a prominent role in AAV pathogenesis by orchestrating the multiple steps of tissue damage. Monocytes, which can also be primed and activated by ANCA, are not illustrated in this figure.

30

CE

PT

ED

MA

NU

SC RI

PT

ACCEPTED MANUSCRIPT

Figure 3: Proposed pathophysiological mechanisms of ANCA-immune response

AC

regulation.

ANCA-immune response regulation is complex and multifactorial. Activated neutrophils generate NETs, which can then activate dendritic cells and trigger adaptive immunity. Quantitative and qualitative abnormalities of T-cells are reported in AAV such as an imbalance between T effector memory cells (TEM) and T regularoy cells (TREG) leading to direct endothelial cytotoxicity, an aberrant T helper (TH) polarization with a shift toward a TH1 or TH2-type response according to the clinical form of the disease, or an impaired TREG suppressive function of ANCA-producing B-cells. The decrease of regulatory B-cells (BREG) may disrupt the negative feedback on TH cells polarization and activated TH cells by reducing their BREG-induced apoptosis. Activated neutrophils also represent an important source of B-cell activating factor (BAFF)/B lymphocyte stimulator (BLyS) increasing ANCA synthesis.

31

PT

ED

MA

NU

SC RI

PT

ACCEPTED MANUSCRIPT

Figure 4: Pathophysiological mechanisms involving alternative complement

CE

pathway in AAV.

ANCA-activated neutrophils release C5a, which not only recruits additional neutrophils

AC

through chemotaxis, but also primes these cells and facilitates their activation by ANCA. The interaction between C5a and its receptor C5a receptor (C5aR) causes a proinflammatory amplification loop for AAV. Complement activating factors are also released leading to an additional production of C5a and membrane attack complex with subsequent direct endothelial cytotoxicity. NETs may activate alternative complement pathway suggesting an additional role in AAV pathogenesis.

32