The Alternative Pathway of Complement Activation Is Critical for Blister Induction in Experimental Epidermolysis Bullosa Acquisita

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Although reports documented aberrant cytokine expression in autoimmune bullous dermatoses (AIBDs), cytokine-targeting therapies have not been established in these disorders. We showed previously that IL-6 treatment protected against tissue destruction in experimental epidermolysis bullosa acquisita (EBA), an AIBD caused by autoantibodies to type VII collagen (COL7). The anti-inflammatory effects of IL-6 were mediated by induction of IL-1ra, and prophylactic IL-1ra administration prevented blistering. In this article, we demonstrate elevated serum concentrations of IL-1β in both mice with experimental EBA induced by injection of anti-COL7 IgG and in EBA patients. Increased IL-1α and IL-1β expression also was observed in the skin of anti-COL7 IgG-injected wild-type mice compared with the significantly less diseased IL-1R–deficient or wild-type mice treated with the IL-1R antagonist anakinra or anti–IL-1β. These findings suggested that IL-1 contributed to recruitment of inflammatory cells into the skin. Accordingly, the expression of ICAM-1 was decreased in IL-1R–deficient and anakinra-treated mice injected with anti-COL7. This effect appeared to be specifically attributable to IL-1 because anakinra blocked the upregulation of different endothelial adhesion molecules on IL-1–stimulated, but not on TNF-α–stimulated, cultured endothelial cells. Interestingly, injection of caspase-1/11–deficient mice with anti-COL7 IgG led to the same extent of skin lesions as in wild-type mice. Collectively, our data suggest that IL-1, independently of caspase-1, contributes to the pathogenesis of EBA. Because anti–IL-1β in a prophylactic setting and anakinra in a quasi-therapeutic setting (i.e., when skin lesions had already developed) improved experimental EBA, IL-1 appears to be a potential therapeutic target for EBA and related AIBDs.

Section: Discussionmentioning

confidence: 99%

Caspase-1–Independent IL-1 Release Mediates Blister Formation in Autoantibody-Induced Tissue Injury through Modulation of Endothelial Adhesion Molecules

Sadeghi

Lockmann

Hund

et al. 2015

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“…Classically, IgG Ab have been shown to be able to activate the classical pathway of complement. However, in a growing list of Ab-induced autoimmune diseases, such as Ab-mediated arthritis (16), subepidermal blistering disease (17), anti-phospholipid syndrome (12), ischemia/reperfusion injury (18), and cryoglobulin-induced immune-complex glomerulonephritis (19), alternative pathway involvement has been implicated. Secondly, Abs can also induce injury through activation of IgG Fc receptors (Fc␥R) (20).…”

mentioning

confidence: 99%

Both Complement and IgG Fc Receptors Are Required for Development of Attenuated Antiglomerular Basement Membrane Nephritis in Mice

Otten

Groeneveld

Flierman

et al. 2009

To elucidate the mechanisms of glomerulonephritis, including Goodpasture’s syndrome, mouse models are used that use heterologous Abs against the glomerular basement membrane (GBM) with or without preimmunization with foreign IgG from the same species. These studies have revealed the requirement of either FcγR or complement, depending on the experimental model used. In this study, we provide evidence that both FcγR and complement are obligatory for a full-blown inflammation in a novel attenuated passive model of anti-GBM disease. We demonstrate that administration of subnephritogenic doses of rabbit anti-GBM Abs followed by a fixed dose of mouse mAbs to rabbit IgG, allowing timing and dosing for the induction of glomerulonephritis, resulted in reproducible complement activation via the classical pathway of complement and albuminuria in wild-type mice. Because albuminuria was absent in FcR-γ-chain−/− mice and reduced in C3−/− mice, a role for both FcγR and complement is postulated. Because C1q−/− and C4−/− mice lacking a functional classical and lectin pathway did develop albuminuria, we suggest involvement of the alternative pathway of complement. Anti-GBM glomerulonephritis occurs acutely following the administration of mouse anti-rabbit IgG, and proceeds in a chronic fashion dependent on both FcγR and complement. This novel attenuated model allows elucidating the relative contribution of different mediator systems of the immune system to the development of renal injury, and also provides a platform for the assessment of different treatment protocols and evaluation of drugs that ultimately may be beneficial for the treatment of anti-GBM mediated glomerulonephritides.

“…Additionally, these data identified a suitable donor/recipient pair to investigate the contribution of radiosensitive and nonradiosensitive cells to the observation of a strain dependency in autoantibody transfer-induced blistering in, more specifically, EBA-resistant MRK/MpJ (H2k) and EBA-susceptible B6.AK-H2k/FlaEgJ (B6.k) mice. We assumed that both cell types contribute to blistering because radiosensitive cells [i.e., Gr-1 + myeloid cells (35)] and nonradiosensitive cells [i.e., complement proteins produced resident tissue cells and hepatocytes (33,39)] have been shown to be required for blister induction. Interestingly, when hematopoietic cells from EBA-susceptible mice were used to rescue irradiated recipient mice, blistering was induced independent of the donor genotype.…”

Section: Discussionmentioning

confidence: 99%

Radiosensitive Hematopoietic Cells Determine the Extent of Skin Inflammation in Experimental Epidermolysis Bullosa Acquisita

Iwata

Witte

Samavedam

et al. 2015

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Animal models have enhanced our understanding of the pathogenesis of autoimmune diseases. For these models, genetically identical, inbred mice have commonly been used. Different inbred mouse strains, however, show a high variability in disease manifestation. Identifying the factors that influence this disease variability could provide unrecognized insights into pathogenesis. We established a novel Ab transfer-induced model of epidermolysis bullosa acquisita (EBA), an autoimmune disease characterized by (muco)-cutaneous blistering caused by anti-type VII collagen (COL7) autoantibodies. Blistering after anti-COL7 IgG (directed against the von Willebrand factor A–like domain 2) transfer showed clear variability among inbred mouse strains, that is, severe cutaneous blistering and inflammation in C57BL/6J and absence of skin lesions in MRL/MpJ mice. The transfer of anti-COL7 IgG into irradiated, EBA-resistant MRL/MpJ mice, rescued by transplantation with bone marrow from EBA-susceptible B6.AK-H2k mice, induced blistering. To the contrary, irradiated EBA-susceptible B6.AK-H2k mice that were rescued using MRL/MpJ bone marrow were devoid of blistering. In vitro, immune complex activation of neutrophils from C57BL/6J or MRL/MpJ mice showed an impaired reactive oxygen species release from the latter, whereas no differences were observed after PMA activation. This finding was paralleled by divergent expression profiles of immune complex–activated neutrophils from either C57BL/6J or MRL/MpJ mice. Collectively, we demonstrate that radiosensitive cells determine the varying extent of skin inflammation and blistering in the end-stage effector phase of EBA.