- Email: [email protected]
Mannose Receptor and the Mystery of Nonhealing Leishmania major Infection
TREPAR 1747 No. of Pages 3
Spotlight
Mannose Receptor and the Mystery of Nonhealing Leishmania major Infection Yahya Sohrabi1,2,* and Marie Lipoldová2,* Scientists have long puzzled over the ability of Leishmania major Seidman (LmSd) to form nonhealing cutaneous lesions in the face of a strong Th1 response. A recent study identified a population of dermal macrophages that are preferentially infected by LmSd in a mannose receptor 1-, C-type 1 (MRC1/CD206)-dependent manner.
LmSd, while exhibiting a strong Th1 response that was characterized by high levels of IFN-g and an absence of IL-4 and IL-13 [4]. Interestingly, it was shown that the Nlrp3 inflammasome, IL-1b, and neutrophil recruitment were required for susceptibility to LmSd [5], but the trigger for these processes was unclear. The answer has now been provided in a new study by Lee and colleagues [6]. These authors identified a population of MRC1hi dermal macrophages that were preferentially infected by LmSd. Infection was dependent on the mannose receptor 1, C-type 1 (MRC1/CD206), and promoted a nonhealing cutaneous disease.
uptake of LmSd but no change in LmFn. MRC1 was previously described as a marker of M2 macrophages, a subgroup of macrophages with anti-inflammatory phenotypes; by contrast, macrophages with proinflammatory effects are often referred to as M1. It is important to notice that the M1 versus M2 paradigm is utilized in mice and could be translated to some degree to humans [8]. The authors treated BMDMs with M1 stimuli [lipopolysaccharide (LPS) or IFN-g plus LPS]. This led to the decrease of MRC1 expression and a loss of difference between LmSd and LmFn uptake. On the other hand, treatment of BMDMs with IL-10, or IL-4 and IL-10, enhanced MRC1 expression and favored uptake of LmSd. In addition, these cytokines are prerequired for the [54_TD$IF]local maintenance of a P4 macrophage population during infection.
MRC1 is an endocytic receptor that recognizes sulfated and mannosylated sugars and is involved in neutralization of pathogens, antigen presentation, cell–cell recognition, serum glycoprotein turnover, Control and prevention of leishmaniasis is and other biological processes. It is The next step was characterization of hi a major challenge in more than 98 coun- expressed mainly by subpopulations of MRC [5_TD$IF] macrophages from the dermis. These cells were identified as P4 dermal tries on five continents. Environmental macrophages and dendritic cells [7]. macrophages, which are defined by their factors, mammalian host genetic backThe authors [6] first compared uptake and profile of cell-surface markers as ground, and the species and/or strain replication of LmSd and L. major Friedlin CD11b+MRChiLy6CintCD64+CCR2lowMcharacteristics of the parasite make the host–parasite interaction very complex. In (MHOM/IL/80/Friedlin) (LmFn), which HCII . They showed characteristics of general, cutaneous leishmaniasis is char- cause nonhealing and healing lesions in mature macrophages with abundant cytoacterized by a self-healing lesion, which C57BL/6 mice, respectively, using M- plasmic vacuoles and melanin granules, bone-marrow-derived and they exhibited high phagocytic activity. heals over a period of time [1]. However, CSF-induced in rare cases, infection can result in a macrophages (BMDMs). The uptake of P4 was the predominant subset infected nonhealing form of the disease that can LmSd was higher than the uptake of by LmSd after infection in the mouse ear. persist for several years and does not LmFn, whereas replication of both L. Analysis of the ontogeny of this P4 popularespond to any of the existing chemo- major strains was similar. Various recep- tion during infection indicated that dermal int hi therapies [2]. One of the strains that cause tors, including MRC1, fibronectin recep- Ly6C MR macrophages are radio-resisthis serious form of the disease – Leish- tor, or complement receptor 3, can tant with the ability of self-renewal, and did mania major Seidman (MHOM/SN/74/ mediate phagocytosis of parasites by not originate from bone-marrow-derived SD) (LmSd) – was isolated 45 years ago macrophages, therefore the individual progenitors. from a Peace Corps volunteer in Senegal. receptors were blocked before infection. The patient exhibited chronic cutaneous There was no difference between uptake Previous data on infection with the ‘heallesions with persisting parasites despite a via fibronectin or complement receptor 3 ing’ strain LmFn in C57BL/6 (Mrc1–/–) strong cell-mediated immune response to of either strain, whereas blocking of mice indicated that MRC1 participates Leishmania antigens [3]. This enigmatic MRC1 led to decreased uptake of LmSd. in Leishmania uptake, but did not influresponse was reproduced in mice; the The role of this receptor in uptake of ence clinical outcome of the infection [9]. mouse strain C57BL/6, which is typically LmSd was confirmed by using BMDMs To evaluate the role of MRC1 in the nonresistant to L. major, developed nonheal- from MRC1-deficient mice (Mrc1 / ), healing infection, Lee et al. [6] infected ing cutaneous lesions after infection with which exhibited dramatically low parasite MRC1-deficient C57BL/6 (Mrc1–/–) and
Trends in Parasitology, Month Year, Vol. xx, No. yy
1
TREPAR 1747 No. of Pages 3
wild-type (WT) mice with the ‘healing’ strain LmFn and the ‘nonhealing’ strain LmSd. The Mrc1–/– mice were as resistant to LmSd as the WT mice with LmFn with respect to lesion size and parasite burden in the ear 15 weeks after infection. To further examine the role of P4 macrophages in the development of nonhealing infection,the authors generated chimeras between CD45.1+WT and CD45.2 Mrc1–/– animals, taking advantage of the fact that P4 is the only radio-resistant population of MRC1-expressing cells in the skin. They determined chimerism 16 weeks after irradiation and 12 weeks postinfection and found that most of the myeloid and lymphoid population recovered from
the inoculation site had been completely replaced by bone-marrow-derived cells of donor origin. The exceptions were the T cells and the P4 dermal macrophages that remained of recipient origin (at 25% and 75%, respectively). Observation of disease development showed that the donor cells were unable to change the healing or nonhealing phenotype of the recipient (Figure 1A). Thus, the resident P4 macrophages of the recipient were able to promote the original phenotypes.
treated mice gained the ability to control LmSd infection and became resistant at levels comparable to LmFn-infected mice (Figure 1B). These findings might have potential clinical applications in the future to treat nonhealing cases of leishmaniasis in humans. Nonetheless, further investigation will be required to understand how depletion of MRC1hi cells could regulate the outcome of the diseases in human patients without impairing skin repair or causing other unexpected complications.
Very interesting results came from an experiment on selective depletion of dermal macrophages using an antibody (M279) against mouse CSF-1R. M279-
Another potential clinical application has the above described redifferentiation of dermis M2-like macrophages to M1-like macrophages with M1 stimuli that
(A)
IrradiaƟon
MRC1 on P4 macrophages
CD45.2+mrc1−/− BM
CD45.1+ WT
LmSd infecƟon 4 weeks
IrradiaƟon
12 weeks PI SuscepƟble to LmSd
CD45.1+ WT BM
CD45.2+mrc1−/−
4 weeks
No MRC1 on P4 macrophages LmSd infecƟon
12 weeks PI Resistant to LmSd
(B)
No P4 macrophages LmSd infecƟon
M279 3 weeks
15 weeks PI
Resistant to LmSd
Figure 1. Nonhealing Infection with Leishmania major Seidman (LmSd) Is Dependent upon the Mannose Receptor C1 and P4 Macrophages. (A) Reciprocal chimeras were generated between CD45.1+WT and CD45.2 Mrc1–/– mice by irradiation and reconstitution with donor bone marrow (BM). Four weeks after transfer, chimeras were infected by injecting the LmSd parasite into the ear. Lesion development was monitored for 12 weeks postinfection. Reconstituted CD45.1+WT mice developed nonhealing lesions, whereas mice reconstituted with CD45.2 Mrc1–/– were resistant to the infection. (B) Mice were treated with the anti-CSF-1R antibody, M279, for 3 weeks in order to deplete P4 dermal macrophages. Mice were then infected with the LmSd parasite in the ear. P4-macrophage-depleted mice became resistant to LmSd infection.
2
Trends in Parasitology, Month Year, Vol. xx, No. yy
TREPAR 1747 No. of Pages 3
resulted in clearance of the LmSd parasite in infected cells. Repolarization of M2-like macrophages to an M1-like phenotype is already being considered as a therapeutic strategy in tumor immunotherapy [10].
cells and to establish whether these or different mechanisms are responsible for other nonhealing leishmaniases. Acknowledgments Support from the Czech Science Foundation (Grants
In summary, the study by Lee et al. [6] provides new insights into the longstanding puzzle of nonhealing infection with the L. major strain LmSd. As yet unidentified adaptations by this parasite promote a sustained, long-term persistence in the dermis that is resistant to the strong Th1 response. This suggests that the LmSd parasite may have evolved by changing its cell-surface oligosaccharide structures to infect and survive in a specific niche – the MRC1hi P4 dermal macrophages. Looking forward, it will be interesting to identify the LmSd epitope responsible for the invasion of MRC1hi
GACR 14-30186S, GACR 16-22346S) and COST Action
BM1404
Mye-EUNITER
is
gratefully
acknowledged. 1
Molecular and Translational Cardiology, Department of Cardiovascular Medicine, University Hospital Münster,
Germany 2 Laboratory of Molecular and Cellular Immunology, Institute of Molecular Genetics of the Czech Academy of ská 1083, 14220 Prague, Czech Republic Sciences, Víden *Correspondence: [email protected] (Y. Sohrabi) and [email protected] (M. Lipoldová).
2. Tolouei, S. et al. (2013) TLR2 and TLR4 in cutaneous leishmaniasis caused by Leishmania major. Scand. J. Immunol. 78, 478–484 3. Neva, F.A. et al. (1979) Cutaneous leishmaniasis – a case with persistent organisms after treatment in presence of normal immune response. Am. J. Trop. Med. Hyg. 28, 467–471 4. Anderson, C.F. et al. (2005) Nonhealing infection despite Th1 polarization produced by a strain of Leishmania major in C57BL/6 mice. J. Immunol. 174, 2934–2941 5. Charmoy, M. et al. (2016) The Nlrp3 inflammasome, IL-1b, and neutrophil recruitment are required for susceptibility to a nonhealing strain of Leishmania major in C57BL/6 mice. Eur. J. Immunol. 46, 897–911 6. Lee, S.H. et al. (2018) Mannose receptor high, M2 dermal macrophages mediate nonhealing Leishmania major infection in a Th1 immune environment. J. Exp. Med. 215, 357–375 7. Martinez-Pomares, L. (2012) The mannose receptor. J. Leukoc. Biol. 92, 1177–1186 8. Martinez, F.O. and Gordon, S. (2014) The M1 and M2 paradigm of macrophage activation: time for reassessment. F1000Prime Rep. 6, 13
https://doi.org/10.1016/j.pt.2018.03.006
9. Akilov, O.E. et al. (2007) The role of mannose receptor during experimental leishmaniasis. J. Leukoc. Biol. 81, 1188–1196
References 1. Kobets, T. et al. (2012) Leishmaniasis: prevention, parasite detection and treatment. Curr. Med. Chem. 19, 1443–1474
10. Zheng, X. et al. (2017) Redirecting tumor-associated macrophages to become tumoricidal effectors as a novel strategy for cancer therapy. Oncotarget 8, 48436–48452
Trends in Parasitology, Month Year, Vol. xx, No. yy
3
Spotlight
Mannose Receptor and the Mystery of Nonhealing Leishmania major Infection Yahya Sohrabi1,2,* and Marie Lipoldová2,* Scientists have long puzzled over the ability of Leishmania major Seidman (LmSd) to form nonhealing cutaneous lesions in the face of a strong Th1 response. A recent study identified a population of dermal macrophages that are preferentially infected by LmSd in a mannose receptor 1-, C-type 1 (MRC1/CD206)-dependent manner.
LmSd, while exhibiting a strong Th1 response that was characterized by high levels of IFN-g and an absence of IL-4 and IL-13 [4]. Interestingly, it was shown that the Nlrp3 inflammasome, IL-1b, and neutrophil recruitment were required for susceptibility to LmSd [5], but the trigger for these processes was unclear. The answer has now been provided in a new study by Lee and colleagues [6]. These authors identified a population of MRC1hi dermal macrophages that were preferentially infected by LmSd. Infection was dependent on the mannose receptor 1, C-type 1 (MRC1/CD206), and promoted a nonhealing cutaneous disease.
uptake of LmSd but no change in LmFn. MRC1 was previously described as a marker of M2 macrophages, a subgroup of macrophages with anti-inflammatory phenotypes; by contrast, macrophages with proinflammatory effects are often referred to as M1. It is important to notice that the M1 versus M2 paradigm is utilized in mice and could be translated to some degree to humans [8]. The authors treated BMDMs with M1 stimuli [lipopolysaccharide (LPS) or IFN-g plus LPS]. This led to the decrease of MRC1 expression and a loss of difference between LmSd and LmFn uptake. On the other hand, treatment of BMDMs with IL-10, or IL-4 and IL-10, enhanced MRC1 expression and favored uptake of LmSd. In addition, these cytokines are prerequired for the [54_TD$IF]local maintenance of a P4 macrophage population during infection.
MRC1 is an endocytic receptor that recognizes sulfated and mannosylated sugars and is involved in neutralization of pathogens, antigen presentation, cell–cell recognition, serum glycoprotein turnover, Control and prevention of leishmaniasis is and other biological processes. It is The next step was characterization of hi a major challenge in more than 98 coun- expressed mainly by subpopulations of MRC [5_TD$IF] macrophages from the dermis. These cells were identified as P4 dermal tries on five continents. Environmental macrophages and dendritic cells [7]. macrophages, which are defined by their factors, mammalian host genetic backThe authors [6] first compared uptake and profile of cell-surface markers as ground, and the species and/or strain replication of LmSd and L. major Friedlin CD11b+MRChiLy6CintCD64+CCR2lowMcharacteristics of the parasite make the host–parasite interaction very complex. In (MHOM/IL/80/Friedlin) (LmFn), which HCII . They showed characteristics of general, cutaneous leishmaniasis is char- cause nonhealing and healing lesions in mature macrophages with abundant cytoacterized by a self-healing lesion, which C57BL/6 mice, respectively, using M- plasmic vacuoles and melanin granules, bone-marrow-derived and they exhibited high phagocytic activity. heals over a period of time [1]. However, CSF-induced in rare cases, infection can result in a macrophages (BMDMs). The uptake of P4 was the predominant subset infected nonhealing form of the disease that can LmSd was higher than the uptake of by LmSd after infection in the mouse ear. persist for several years and does not LmFn, whereas replication of both L. Analysis of the ontogeny of this P4 popularespond to any of the existing chemo- major strains was similar. Various recep- tion during infection indicated that dermal int hi therapies [2]. One of the strains that cause tors, including MRC1, fibronectin recep- Ly6C MR macrophages are radio-resisthis serious form of the disease – Leish- tor, or complement receptor 3, can tant with the ability of self-renewal, and did mania major Seidman (MHOM/SN/74/ mediate phagocytosis of parasites by not originate from bone-marrow-derived SD) (LmSd) – was isolated 45 years ago macrophages, therefore the individual progenitors. from a Peace Corps volunteer in Senegal. receptors were blocked before infection. The patient exhibited chronic cutaneous There was no difference between uptake Previous data on infection with the ‘heallesions with persisting parasites despite a via fibronectin or complement receptor 3 ing’ strain LmFn in C57BL/6 (Mrc1–/–) strong cell-mediated immune response to of either strain, whereas blocking of mice indicated that MRC1 participates Leishmania antigens [3]. This enigmatic MRC1 led to decreased uptake of LmSd. in Leishmania uptake, but did not influresponse was reproduced in mice; the The role of this receptor in uptake of ence clinical outcome of the infection [9]. mouse strain C57BL/6, which is typically LmSd was confirmed by using BMDMs To evaluate the role of MRC1 in the nonresistant to L. major, developed nonheal- from MRC1-deficient mice (Mrc1 / ), healing infection, Lee et al. [6] infected ing cutaneous lesions after infection with which exhibited dramatically low parasite MRC1-deficient C57BL/6 (Mrc1–/–) and
Trends in Parasitology, Month Year, Vol. xx, No. yy
1
TREPAR 1747 No. of Pages 3
wild-type (WT) mice with the ‘healing’ strain LmFn and the ‘nonhealing’ strain LmSd. The Mrc1–/– mice were as resistant to LmSd as the WT mice with LmFn with respect to lesion size and parasite burden in the ear 15 weeks after infection. To further examine the role of P4 macrophages in the development of nonhealing infection,the authors generated chimeras between CD45.1+WT and CD45.2 Mrc1–/– animals, taking advantage of the fact that P4 is the only radio-resistant population of MRC1-expressing cells in the skin. They determined chimerism 16 weeks after irradiation and 12 weeks postinfection and found that most of the myeloid and lymphoid population recovered from
the inoculation site had been completely replaced by bone-marrow-derived cells of donor origin. The exceptions were the T cells and the P4 dermal macrophages that remained of recipient origin (at 25% and 75%, respectively). Observation of disease development showed that the donor cells were unable to change the healing or nonhealing phenotype of the recipient (Figure 1A). Thus, the resident P4 macrophages of the recipient were able to promote the original phenotypes.
treated mice gained the ability to control LmSd infection and became resistant at levels comparable to LmFn-infected mice (Figure 1B). These findings might have potential clinical applications in the future to treat nonhealing cases of leishmaniasis in humans. Nonetheless, further investigation will be required to understand how depletion of MRC1hi cells could regulate the outcome of the diseases in human patients without impairing skin repair or causing other unexpected complications.
Very interesting results came from an experiment on selective depletion of dermal macrophages using an antibody (M279) against mouse CSF-1R. M279-
Another potential clinical application has the above described redifferentiation of dermis M2-like macrophages to M1-like macrophages with M1 stimuli that
(A)
IrradiaƟon
MRC1 on P4 macrophages
CD45.2+mrc1−/− BM
CD45.1+ WT
LmSd infecƟon 4 weeks
IrradiaƟon
12 weeks PI SuscepƟble to LmSd
CD45.1+ WT BM
CD45.2+mrc1−/−
4 weeks
No MRC1 on P4 macrophages LmSd infecƟon
12 weeks PI Resistant to LmSd
(B)
No P4 macrophages LmSd infecƟon
M279 3 weeks
15 weeks PI
Resistant to LmSd
Figure 1. Nonhealing Infection with Leishmania major Seidman (LmSd) Is Dependent upon the Mannose Receptor C1 and P4 Macrophages. (A) Reciprocal chimeras were generated between CD45.1+WT and CD45.2 Mrc1–/– mice by irradiation and reconstitution with donor bone marrow (BM). Four weeks after transfer, chimeras were infected by injecting the LmSd parasite into the ear. Lesion development was monitored for 12 weeks postinfection. Reconstituted CD45.1+WT mice developed nonhealing lesions, whereas mice reconstituted with CD45.2 Mrc1–/– were resistant to the infection. (B) Mice were treated with the anti-CSF-1R antibody, M279, for 3 weeks in order to deplete P4 dermal macrophages. Mice were then infected with the LmSd parasite in the ear. P4-macrophage-depleted mice became resistant to LmSd infection.
2
Trends in Parasitology, Month Year, Vol. xx, No. yy
TREPAR 1747 No. of Pages 3
resulted in clearance of the LmSd parasite in infected cells. Repolarization of M2-like macrophages to an M1-like phenotype is already being considered as a therapeutic strategy in tumor immunotherapy [10].
cells and to establish whether these or different mechanisms are responsible for other nonhealing leishmaniases. Acknowledgments Support from the Czech Science Foundation (Grants
In summary, the study by Lee et al. [6] provides new insights into the longstanding puzzle of nonhealing infection with the L. major strain LmSd. As yet unidentified adaptations by this parasite promote a sustained, long-term persistence in the dermis that is resistant to the strong Th1 response. This suggests that the LmSd parasite may have evolved by changing its cell-surface oligosaccharide structures to infect and survive in a specific niche – the MRC1hi P4 dermal macrophages. Looking forward, it will be interesting to identify the LmSd epitope responsible for the invasion of MRC1hi
GACR 14-30186S, GACR 16-22346S) and COST Action
BM1404
Mye-EUNITER
is
gratefully
acknowledged. 1
Molecular and Translational Cardiology, Department of Cardiovascular Medicine, University Hospital Münster,
Germany 2 Laboratory of Molecular and Cellular Immunology, Institute of Molecular Genetics of the Czech Academy of ská 1083, 14220 Prague, Czech Republic Sciences, Víden *Correspondence: [email protected] (Y. Sohrabi) and [email protected] (M. Lipoldová).
2. Tolouei, S. et al. (2013) TLR2 and TLR4 in cutaneous leishmaniasis caused by Leishmania major. Scand. J. Immunol. 78, 478–484 3. Neva, F.A. et al. (1979) Cutaneous leishmaniasis – a case with persistent organisms after treatment in presence of normal immune response. Am. J. Trop. Med. Hyg. 28, 467–471 4. Anderson, C.F. et al. (2005) Nonhealing infection despite Th1 polarization produced by a strain of Leishmania major in C57BL/6 mice. J. Immunol. 174, 2934–2941 5. Charmoy, M. et al. (2016) The Nlrp3 inflammasome, IL-1b, and neutrophil recruitment are required for susceptibility to a nonhealing strain of Leishmania major in C57BL/6 mice. Eur. J. Immunol. 46, 897–911 6. Lee, S.H. et al. (2018) Mannose receptor high, M2 dermal macrophages mediate nonhealing Leishmania major infection in a Th1 immune environment. J. Exp. Med. 215, 357–375 7. Martinez-Pomares, L. (2012) The mannose receptor. J. Leukoc. Biol. 92, 1177–1186 8. Martinez, F.O. and Gordon, S. (2014) The M1 and M2 paradigm of macrophage activation: time for reassessment. F1000Prime Rep. 6, 13
https://doi.org/10.1016/j.pt.2018.03.006
9. Akilov, O.E. et al. (2007) The role of mannose receptor during experimental leishmaniasis. J. Leukoc. Biol. 81, 1188–1196
References 1. Kobets, T. et al. (2012) Leishmaniasis: prevention, parasite detection and treatment. Curr. Med. Chem. 19, 1443–1474
10. Zheng, X. et al. (2017) Redirecting tumor-associated macrophages to become tumoricidal effectors as a novel strategy for cancer therapy. Oncotarget 8, 48436–48452
Trends in Parasitology, Month Year, Vol. xx, No. yy
3