X chromosome monosomy in primary and overlapping autoimmune diseases

Autoimmunity Reviews 11 (2012) 301–304

Contents lists available at ScienceDirect

Autoimmunity Reviews j o u r n a l h o m e p a g e : w w w. e l s ev i e r. c o m / l o c a t e / a u t r ev

Review

X chromosome monosomy in primary and overlapping autoimmune diseases Yevgeniya Svyryd a, Gabriela Hernández-Molina b, Florencia Vargas c, Jorge Sánchez-Guerrero b, Donato Alarcón Segovia b,1, Osvaldo M. Mutchinick a,⁎ a b c

Department of Genetics, Instituto Nacional de Ciencias Médicas y Nutrición “Salvador Zubirán”, México Department of Immunology and Rheumatology, Instituto Nacional de Ciencias Médicas y Nutrición “Salvador Zubirán”, México Department of Gastroenterology, Instituto Nacional de Ciencias Médicas y Nutrición “Salvador Zubirán”, México

a r t i c l e

i n f o

a b s t r a c t

Article history: Received 1 March 2010 Accepted 9 March 2010 Available online 15 March 2010

Female predominance is a common characteristic for autoimmune diseases attributed to the combined effect of hormonal influence and genetic factors. Since X chromosome has immunologically important genes, the age related X chromosome loss could contribute to the development of autoimmunity. X chromosome monosomy (XCM) has been associated with primary biliary cirrhosis (PBC) and systemic sclerosis. Herein, using fluorescence in situ hybridization (FISH) with specific centromeric probes, we report the rate of XCM in interphase nuclei in women with Reynolds syndrome (RS), an overlapping condition of PBC and systemic sclerosis (SSc). Frequency of nuclei with XCM was 12.1% (CI 95%, 8.5–17.1) in RS, 10% (7.1–13.9) in PBC, 9.2% (6.0–13.9) in SSc and 6.4% (5.1–8) in age-matched healthy controls. We found a significantly higher XCM frequency in RS PBC and SSc groups of patients when compared with controls, p b 0.01, p b 0.05 and p b 0.05 respectively. XCM was highest in the RS group but not statistically different from PBC and SSc patients. Fetal– maternal microchimerism prevalence evaluated by Q-PCR for SRY sequences varies among groups, although no statistical differences were observed. Besides the above, we found an apparently important additive effect (89.1%) of PBC and SSc on the prevalence of XCM cells in RS patients. Another interesting finding was that the prevalence of XCM cells seems not to be dependent on the time of evolution of the AID studied. Moreover, the shorter time of evolution and the higher prevalence of XCM interphase nuclei observed in RS patients sustain our hypothesis of the additive effect abovementioned. © 2010 Elsevier B.V. All rights reserved.

Keywords: X chromosome monosomy Reynolds syndrome PBC SSc Microchimerism

Contents 1. 2.

Introduction . . . . . . . . . . . Materials and methods . . . . . . 2.1. Subjects studied . . . . . . 2.2. Cytogenetic analysis . . . . 2.3. Microchimerism analysis . . 2.4. Statistical analysis . . . . . 3. Results . . . . . . . . . . . . . 3.1. X chromosome monosomy . 3.2. Fetal male microchimerism 4. Discussion . . . . . . . . . . . . Take-home messages . . . . . . . . . References . . . . . . . . . . . . . .

. . . . . . . . . . . .

. . . . . . . . . . . .

. . . . . . . . . . . .

. . . . . . . . . . . .

. . . . . . . . . . . .

. . . . . . . . . . . .

. . . . . . . . . . . .

. . . . . . . . . . . .

. . . . . . . . . . . .

. . . . . . . . . . . .

. . . . . . . . . . . .

. . . . . . . . . . . .

. . . . . . . . . . . .

. . . . . . . . . . . .

. . . . . . . . . . . .

. . . . . . . . . . . .

. . . . . . . . . . . .

. . . . . . . . . . . .

. . . . . . . . . . . .

. . . . . . . . . . . .

. . . . . . . . . . . .

. . . . . . . . . . . .

. . . . . . . . . . . .

. . . . . . . . . . . .

. . . . . . . . . . . .

. . . . . . . . . . . .

. . . . . . . . . . . .

. . . . . . . . . . . .

. . . . . . . . . . . .

. . . . . . . . . . . .

. . . . . . . . . . . .

. . . . . . . . . . . .

. . . . . . . . . . . .

. . . . . . . . . . . .

. . . . . . . . . . . .

. . . . . . . . . . . .

. . . . . . . . . . . .

. . . . . . . . . . . .

. . . . . . . . . . . .

. . . . . . . . . . . .

. . . . . . . . . . . .

. . . . . . . . . . . .

. . . . . . . . . . . .

. . . . . . . . . . . .

. . . . . . . . . . . .

. . . . . . . . . . . .

. . . . . . . . . . . .

. . . . . . . . . . . .

. . . . . . . . . . . .

. . . . . . . . . . . .

. . . . . . . . . . . .

301 302 302 302 302 303 303 303 303 303 304 304

1. Introduction ⁎ Corresponding author. Instituto Nacional de Ciencias Médicas y Nutrición “Salvador Zubirán,” Vasco de Quiroga 15, Sección 16, Tlalpan, D.F. Mexico, 14000 México. Tel.: + 52 55 5655 6138. E-mail address: [email protected] (O.M. Mutchinick). 1 In memoriam. 1568-9972/$ – see front matter © 2010 Elsevier B.V. All rights reserved. doi:10.1016/j.autrev.2010.03.001

Almost all systemic and organ-specific autoimmune diseases (AIDs) have a conspicuous female predominance [1]. Female prevalence ranges from 35% in primary glomerulonephritis to more than 85% in primary biliary cirrhosis (PBC), systemic sclerosis (SSc), systemic lupus

302

Y. Svyryd et al. / Autoimmunity Reviews 11 (2012) 301–304

erythematosus (SLE) and Sjögren syndrome [2]. However, except for SLE, no association between sex and disease severity has been documented [3]. Sex-ratio differences have been most frequently attributed to the combined effect of genetic determinants, sex-specific receptors activity and influence of estrogenic hormones [4]. Among the genetic factors leading to autoimmunity, fetal– maternal microchimerism (f-MMC), skewed X chromosome inactivation (sXCI), loss of epigenetic control and most recently acquired X chromosome monosomy (XCM) have been proposed [5–7]. Persistence of male fetal cells in maternal circulation after delivery, known as f-MMC, has been found in patients with SSc [8], PBC [9] and SLE [10]. A skewed pattern of XCI has also been reported in patients with SSc [11] and autoimmune thyroid disease (AITD) [12]. Invernizzi et al., described the presence of XCM in patients with PBC [13], SSc and AITD [14] these findings being independent of fMMC. However, an increase in XCM was not observed in SLE patients [15]. The same group of authors concludes that the X chromosome loss in PBC patients occurs in a preferential fashion, involving only one parentally-derived inactive homologue [16]. It is well known, that features of two or more autoimmune diseases may coexist in the same patient, as has been observed in patients with SSc and SLE, rheumatoid arthritis, polymyositis or autoimmune liver disease, such as PBC, being considered as overlapping autoimmune diseases (OAIDs) [17]. Of these the presence of systemic sclerosis (SSc) and PBC in the same patient was first described by Murray-Lyon et al. in 1970, and almost simultaneously by Reynolds et al. in 1971, and is currently known as Reynolds syndrome (RS) [18,19]. Despite of the small number of cases reported, it has been suggested that these two diseases have a common autoimmune origin, although it is not clear if both diseases have the same genetic background. [20]. The abovementioned, prompted us to hypothesize that female patients with RS, may show a higher proportion of X chromosome monosomic cells than age-matched healthy women and with agematched women with PBC or SSc. Herein, we report the results of the analysis of X chromosome monosomy and f-MMC in female patients with RS, PBC and SSc and their sex- and age-matched healthy controls. We discuss our findings trying to understand the differences in the increased number of X chromosome monosomic cells observed in these AIDs, and the apparent null effect of XY cells microchimerism on the proportion of X chromosome monosomy. 2. Materials and methods

Table 1 Demographic and clinical characteristics of study women. Characteristic

RS n = 12

PBC n = 11a

SSc n = 12

Controls n = 24

Age, years Male offspring Miscarriage Older male sibling Transfusion Disease duration, years

59.2 ± 10.8 10 6 8 5 4.4 ± 3

58.8 ± 9.5 9 4 8 6 7.4 ± 5

58.7 ± 9.9 8 4 10 6 17.8 ± 10

59.2 ± 10.6 20 11 12 10 –

Quantitative variables are summarized as mean ± standard deviation; qualitative variables as absolute frequency. a One blood sample failed to grow.

chromosome preparations were analyzed to avoid the inclusion of patients with X chromosome number or structural aberrations. Fluorescent in situ hybridization (FISH) was performed using DXZ1 alpha satellite probe (CEPX SpectrumGreen, Visys®) and D15Z4 alpha satellite control probe (CEP15 SpectrumOrange, Visys®). Both probes and target DNA were processed simultaneously according to manufacturer specifications and cell preparations were counterstained with DAPI. Fluorescent signals were visualized using a Leica® DM RXAII cytogenetic work station. Five hundred interphase nuclei (IN) per sample were analyzed. The presence of two green and two orange fluorescent signals was considered as a normal nucleus and one green and two orange signals as an XCM nucleus (Fig. 1). Nuclei with less than two red (Chr-15) and nuclei with more than two green (Chr-X) fluorescent signals were discarded. All preparations were coded to allow a double blind cytogenetic analysis. 2.3. Microchimerism analysis Genomic DNA was obtained from 3 mL of peripheral blood by the conventional salting-out technique. Detection of male DNA was made by amplifying a SRY gene fragment using the Quantifiler Y Human Male DNA Quantification Kit (Applied Biosystems®). As a reference locus, RNase P gene was simultaneously amplified in an independent row. Quantitative PCR (Q-PCR) was carried out using an ABI PRISM® 7000 sequence detection system (Applied Biosystems®). Separate eight-point standard curves were generated for SRY and reference genes. The assay detection level is 1 male cell in 107 female cells. Relative quantification of male f-MMC was calculated according to ΔΔCT method. Three replicates from two independent aliquots of all

2.1. Subjects studied Twelve female patients with a diagnosis of Reynolds syndrome and three comparison groups consisting of i) 12 female patients with PBC, ii) 12 with SSc and iii) 24 female controls were studied. Since the rate of XCM is known to increase with female age [21], all subjects were groupmatched by age with a tolerance interval of ±3 years. Information regarding pregnancies, spontaneous or induced abortions, male offspring and older brothers was collected from all subjects studied (Table 1). The diagnosis of PBC was accepted if typical clinical, biochemical, serological and histopathological changes were present [22], SSc was diagnosed according to the ACR criteria [23]. Except for women with RS, overlapping of any other AID with SSc or PBC was excluded. Controls should not have a history of AID or cancer. The study was approved by the Institutional Committee of Biomedical Research and informed consent was obtained from all participants. 2.2. Cytogenetic analysis Whole peripheral blood lymphocytes were cultured in RPMI 1640 medium (Gibco®) and PHA (Gibco®) for 72 h at 37 °C. GTG banded

Fig. 1. Identification of X chromosome monosomic nuclei by FISH. A picture of a microscopy field stained with probe CEP X (green) and probe CEP 15 (red) using a Leica DRXII cytogenetic workstation. Nuclei with two green and two red fluorescent signals were considered normal (N). Nuclei with one green and two red signals were considered as monosomic for the X chromosome (XCM).

Y. Svyryd et al. / Autoimmunity Reviews 11 (2012) 301–304

samples were blindly analyzed for possible male f-MMC scores and diagnostic. 2.4. Statistical analysis Categorical variables were summarized in terms of frequencies and compared by the X2 or Fisher's exact test. Age was expressed as means and standard deviations and compared with the Student's t test. Percentages of XCM interphase nuclei were log-transformed to normalize their distributions. XCM frequencies attributable only to PBS, SSc and RS were estimated by subtracting to their XCM frequency, the one observed in the healthy controls. Multiple regression analysis was used to control for potential confounders. A two tailed p b 0.05 was considered as statistically significant. The Stata 5.0 package (Stata Corporation, College Station, TX) was used to conduct the statistical analysis. 3. Results Demographic and clinical characteristics of participants are summarized in Table 1. Mean age was 58.9 ± 9.8 in AIDs patients and 59.2 ± 10.5 years in controls. Child scores of liver dysfunction were comparable between RS and PBC groups. Severity of skin manifestations was similar among patients with RS and SSc (modified Rodnan score 6.7 ± 1 and 9.3 ± 6 respectively). Patients with SSc had the longest disease duration (Table 1). In six patients with RS, PBC and SSc were diagnosed simultaneously, in four PBC was diagnosed before and in two patients, SSc was diagnosed before PBC. The frequency of male offspring, miscarriages, brothers and transfusions was similarly distributed among groups (Table 1). 3.1. X chromosome monosomy The mean frequency of XCM in 500 IN analyzed per RS, PBC, SSc and control subjects was of 12.08%, 9.97%, 9.79% and 6.36% respectively (Table 2). The number of monosomic IN of patients with RS and PBC was significantly higher (p = 0.002 and p = 0.024 respectively) and tended to be higher in SSc patients (p = 0.081) than in controls. Multiple regression analysis to control possible sources of male f-MMC such as number of male offspring, miscarriage, older male siblings and transfusions, showed that they were not significant confounders, but interestingly, the difference between SSc and the control group became statistically significant (p b 0.05). The XCM prevalence attributable to RS, PBC and SSc, estimated by subtracting to the XCM frequency of each, the one observed in the healthy controls, was 5.72%; 3.61% and 2.81% respectively. The sum of the latter two differences (i.e. 3.61% and 2.81%) results in 6.42%, which only exceeds by 0.7% the XCM prevalence attributable to RS, suggesting an important (89.1%) additive effect (5.72%/6.42%) for the occurrence of XCM, when PBC and SSc, coexist in the same individual. Although the proportion of X monosomic IN was highest in the RS than in PBC and SSc patients, the differences were not statistically significant.

Table 2 Prevalence of XCM interphase nuclei and male f-MMC.

Total IN analyzed, n XCM IN, n XCM IN, % (95% CI) Male f-MMC, n

RS n = 12

PBC n = 11a

SSc n = 12

Controls n = 24

6000 839 12.08 (8.54–17.10) 2

5500 620 9.97 (7.14–13.94) 4

6000 746 9.79 (6.96–13.76) 2

12,000 866 6.36 (5.08–7.95) 7

IN, interphase nuclei; 95% CI, 95% confidence interval. a One blood culture failed to grow.

303

3.2. Fetal male microchimerism The proportion of subjects that were positive for SRY sequences is shown in Table 2. The highest number of women with male f-MMC was observed among PBC patients and control subjects, 33.3% and 29.2% respectively. The relative amount of male DNA in positive cases was highest and more homogeneous in the PBC group than in RS, SSc and controls. No statistically significant difference was found between groups when male f-MMC was measured by Q-PCR methods. 4. Discussion In the present study we showed that the prevalence of X chromosome monosomy in interphase nuclei of cultured peripheral lymphocyte of patients with RS (an overlapping AID of PBC and SSc), PBC and SSc is significantly higher than sex- and age-matched controls. Furthermore, our results strongly suggest an important additive effect (89.1%) on the XCM prevalence in RS as the outcome of the overlapping event. We also found that the presence of male fetal– maternal microchimerism is not an alternative explanation for the significant increased frequency of XCM observed in the studied AID groups. Clinical and epidemiological experience showed that many AIDs affect more frequently women than men [24]. However, a convincing explanation for this finding is still uncertain. Some studies suggest differences in X chromosome inactivation patterns [11,12], while others suggest the presence of male f-MMC as a possible cause [8–10]. X chromosome does not contain sex-related genes only, but also genes that maintain the immune balance [7]. Mutations of specific Xlinked genes may cause immunodeficiency conditions, frequently associated to autoimmune diseases [25]. The hypothesis that susceptibility to AID and their predominant presentation in females may be related to a gene dose-effect of the two X chromosomes is, nowadays, most accepted [26]. A progressive loss of an X chromosome in female peripheral lymphocytes, known as acquired XCM, has been demonstrated to have a highly significant (p b 0.00001) quadratic relationship with ageing [27]. This phenomenon has been proposed recently as an alternative explanation to the occurrence of AIDs. The first description of XCM associated to AIDs was done by Invernizzi et al. in patients with PBC [13]. Soon after, the same authors also reported a high prevalence of XCM in autoimmune thyroid disease and scleroderma [14]. Like in Invernizzi et al.'s studies, we found a significantly higher acquired frequency of XCM than controls in patients with PBC and SSc, and an even higher in patients with Reynolds syndrome where both PBC and SSc coexist. The loss of an X chromosome suggests that haploinsufficiency for a subset of X-linked genes may be associated to these particular AIDs. Important to mention is, that haploinsufficiency of sex chromosome-linked genes, was reported recently in males with PBC following the loss of the Y chromosome. This suggests that X chromosome inactivation escaping genes and their Y chromosome homologues may play a role in immune homeostasis and the possible effect of their loss in AIDs [28]. The coexistence in the same subject of SSc with PBC occurs in 4% to 19% of PBC patients [29]. The coexistence of two AIDs in the same patient suggests that they may share similar genetic and environmental susceptibility risk factors or that they may have a common causal immunologic dysfunction. Only two studies addressed these questions in the Reynolds syndrome [30,31], but none of them was able to demonstrate a similar genetic, environmental or immunologic background. To our knowledge, no reports on XCM in RS or in any other OAIDs were made previously. Besides a higher prevalence of XCM interphase nuclei in RS, PBC and SSc patients, an important additive effect (89.1%) was observed on the XCM cells attributable to the prevalence of RS. Another interesting finding was that the prevalence of XCM seems not to be

304

Y. Svyryd et al. / Autoimmunity Reviews 11 (2012) 301–304

dependent on the time of duration of the AIDs studied (Table 1). Moreover, the shorter time of evolution (Table 1) together with the higher prevalence of XCM interphase nuclei observed in RS patients (Table 2) also sustain our hypothesis of the additive effect abovementioned. More research with RS, PCB and SSc are needed to confirm our findings, as well as studies concerning other overlapping AIDs. Take-home messages • Loss of an X chromosome occurs in peripheral lymphocytes of female with autoimmune diseases such as PBC, SSc and according to our study also in RS at a higher proportion than in healthy controls of similar ages. • The proportion of XCM interphase nuclei was higher in RS than in isolated PBC and isolated SSc patients. • The presence of PBC and SSc in the same patient, strongly suggests an additive effect on the proportion of XCM cells observed in RS. • Exploration of similar findings in other overlapping autoimmune diseases would be of interest.

References [1] Zandman-Goddard G, Peeva E, Shoenfeld Y. Gender and autoimmunity. Autoimmun Rev 2007;6:366–72. [2] Cooper GC, Stroehla BC. The epidemiology of autoimmune diseases. Autoimmun Rev 2002;2:119–25. [3] Lleo A, Battezzati PM, Selmi C, Gershwin ME, Podda M. Is autoimmunity a matter of sex? Autoimmun Rev 2008;7:626–30. [4] Freire de Carvalho J, Pereira RM, Shoenfeld Y. The mosaic of autoimmunity: the role of environmental factors. Front Biosci 2009;1:501–9. [5] Selmi C, Invernizzi P, Miozzo M, Podda M, Gershwin ME. Primary biliary cirrhosis: does X mark the spot? Autoimmun Rev 2004;3:493–9. [6] Invernizzi P. The X chromosome in female-predominant autoimmune diseases. Ann N Y Acad Sci 2007;1110:57–64. [7] Hernández-Molina G, Svyryd Y, Sánchez-Guerrero J, Mutchinick OM. The role of the X chromosome in immunity and autoimmunity. Autoimmunity Rev 2007;6: 218–22. [8] Lambert N, Erickson T, Yan Z, Pang J, Guthrie K, Furst D, et al. Quantification of maternal microchimerism by HLA-specific real-time polymerase chain reaction. Arthritis Rheum 2004;50:906–14. [9] Fanning P, Jonsson J, Clouston A, Edward-Smith C, Balderson G, Mcdonald G, et al. Detection of male DNA in the liver of female patients with primary biliary cirrhosis. J Hepatology 2000;33:690–5. [10] Kremer IC, Koopmans M, Baelde HJ, de Heer E, Brujin JA, Bajema IM. Tissue chimerism in systemic lupus erythematosus is related to injury. Ann Rheum Dis 2007;66:1568–73.

[11] Özbalkan Z, Bagisiar S, Kiraz S, Akyerli CB, Özer HT, Yavuz S, et al. Skewed X chromosome inactivation in blood cells of women with scleroderma. Arthritis Rheum 2005;52:1564–70. [12] Brix TH, Knudsen GP, Kristiansen M, Kyvik K, Orstavik KH, Hegedus L. High frequency of skewed X-chromosome inactivation in females with autoimmune thyroid disease: a possible explanation for the female predisposition to thyroid autoimmunity. J Clin Endocrinol Metab 2005;90:5949–53. [13] Invernizzi P, Miozzo M, Battezati M, Bianchi I, Grati FR, Simoni G, et al. Frequency of monosomy X in women with primary biliary cirrhosis. Lancet 2004;363:533–4. [14] Invernizzi P, Miozzo M, Selmi C, Persani L, Battezzati P, Zuin M, et al. X chromosome monosomy: a common mechanism for autoimmune diseases. J Immunol 2005;175:575–8. [15] Invernizzi P, Miozzo M, Oertel-Prigione S, Meroni P, Persani L, Selmi C, et al. X monosomy in female systemic lupus erythematosus. Ann N Y Acad Sci 2007;1110: 84–9. [16] Miozzo M, Selmi C, Gentilin B, Grati F, Sirchia S, Oertelt S, et al. Preferential X chromosome loss but random inactivation characterize primary biliary cirrhosis. Hepatology 2007;46:256–62. [17] Jablonska S, Blaszczyk M. Scleromyositis: a scleroderma/polymyositis overlap syndrome. Clin Rheumatol 1998;17:465–7. [18] Murray-Lyon IM, Thompson RPM, Ansell ID, Williams R. Scleroderma and primary biliary cirrhosis. Brit Med J 1970;3:258–9. [19] Reynolds TF, Denison EK, Frankl HD, Lieberman FL, Peters RL. Primary biliary cirrhosis with scleroderma, Raynaud's phenomenon and telangiectasia. Am J Med 1971;50(3):302–12. [20] Abraham S, Begum S, Isenberg D. Hepatic manifestations of autoimmune rheumatic diseases. Ann Rheum Dis 2004;63:123–9. [21] Guttenbach M, Koschotz B, Bernthaler J, Grimm T, Schmid M. Sex chromosome loss and aging in situ hybridization studies on human interphase nuclei. Am J Hum Genetic 1995;57:1143–5. [22] Kaplan M, Gershwin E. Primary biliary cirrhosis. N Engl J Med 2005;353:1261–73. [23] Subcommittee for Scleroderma Criteria of the American Rheumatism Association Diagnostic and Therapeutic Criteria Committee. Preliminary criteria for the classification of systemic sclerosis (scleroderma). Arthritis Rheum 1980;23: 581–90. [24] Lockshin M. Sex differences in autoimmune disease. Lupus 2006;15:753–6. [25] Gartler SM, Goldman MA. Biology of the X chromosome. Curr Opin Pediatr 2001;13:340–5. [26] Invernizzi P. Future directions in genetic for autoimmune diseases. J Autoimmunity 2009;33:1–2. [27] Russell LM, Strike P, Browne CE, Jacobs PA. X chromosome loss and ageing. Cytogenet Genome Res 2007;116(3):181–5. [28] Pasini S, Miozzo M, Bianchi I, Monti V, Rosa Rizzotto E, Floreani A, et al. Males with primary biliary cirrhosis manifest enhanced rates of Y chromosome loss compared to healthy subjects. Digest Liver Dis 2009;41(3):A43. [29] Youssef W, Tavill A. Connective tissue diseases and the liver. J Clin Gastroenterol 2002;35:345–9. [30] Akiyama Y, Tanaka M, Takeishi M, Adachi D, Mimori A, Suzuki T. Clinical, serological and genetic study in patients with CREST syndrome. Intern Med 2000;39:451–6. [31] Mayo M, Jenkins R, Combes B, Lipsky P. Association of clonally expanded T cells with the syndrome of primary biliary cirrhosis and limited scleroderma. Hepatology 1999;29:1635–42.

The resistance to immune-modulation of Systemic Lupus Erythematosus nephritis in NZB/W F1 mice treated with IFN-α The critical role of interferon-α (IFN-α) in the pathogenesis of Systemic Lupus Erythematosus (SLE) has been highlighted in recent years. IFN-α induces maturation of myeloid dendritic cells that provide co-stimulation for naïve CD4+ T cells and produce IL-6 and BAFF; a cytokine that enhances selection, survival and class switching of autoreactive B cells. It has been previously reported that, in young NZB/W F1 mice, the exposure to IFN-α leads to an accelerated SLE phenotype that is T cells dependent and is associated with high levels of BAFF, IL-6, TNF and large germinal centers formation with generation of short-lived plasma-cells, that produce IgG2a and IgG3 antibodies, which cause glomerulonephritis1. Liu Z et al (J Immunol 2011; 187:1506-13), used a murine model in which 12 weeks old NZB/W F1 mice were pre-treated with Ad-IFN-α. IFN-α-treated NZB/W F1 mice and conventional NZB/W F1 mice underwent to treatment with ciclophosphamide (CTX), CTLA4-Ig, and TACIIg, alone or in combination. In this study, both CTLA4-Ig and TAC-Ig are shown to be able to delay SLE onset in IFN-α induced NZB/W F1 mice, but a higher CTLA4-Ig dose than in conventional mice was required. These effects were achieved in a different manner by the two drugs. High dose CLTA4-Ig attenuates both IgG2a and IgG3 autoantibody production and significantly attenuates nephritis-associated mortality. TACI-Ig, even if it does not reduce the production of ant-dsDNA autoantibodies, attenuates the renal inflammatory response to immune complex deposition. Finally, IFN-α induced mice, when treated with CTX, CTLA4-Ig and TACI-Ig showed a depletion of autoantibodyproducing plasma-cells and clinical remission, similarly to conventional mice. However, in IFN-α induced mice, relapse occurred more rapidly. The Authors conclude that IFN-α not only accelerates the progress of SLE, but also renders NZB/W F1 mice more resistant to immune-modulation. 1 Liu Z et al. Interferon-α accelerates murine sistemi lupus erythematosus in a T cell-dependent manner. Arthritis Reum 2011; 63:219-29. Luca Iaccarino