Evidence for a contributory role of a xenogeneic immune response in experimental epidermolysis bullosa acquisita.

Autoimmune diseases affect a large fraction of the population in Western countries. To elucidate the underlying causes, autoantibody transfer-induced mouse models have been established that greatly contributed to the understanding of the pathophysiology of these diseases. However, the role of a potentially co-occurring murine xenogeneic immune response to commonly utilized rabbit anti-mouse IgG remains poorly understood. Using the established rabbit anti-mouse type VII collagen (COL7) IgG-induced mouse model of the mucocutaneous blistering disorder epidermolysis bullosa acquisita (EBA), we found in this study a profound T- and B-cell response along with an altered cytokine expression profile in draining lymph nodes of mice injected with the xenogeneic IgG. This was associated with the formation of circulating and skin-bound mouse anti-rabbit IgG in wild-type but not CD154-deficient or B-cell-deficient JHT mice challenged with pathogenic rabbit IgG. Development of EBA skin lesions was attenuated in the two mouse strains lacking a B-cell response at later observation time points, but was not affected in mice treated with the T-cell trafficking blocker FTY720. Collectively, our results implicate a host's xenoreactive immune response to rabbit anti-mouse COL7 IgG, a confounding effect that may contribute to immune complex-driven inflammation and tissue damage in this antibody transfer-induced EBA mouse model, especially at later time points. In this regard, it may be recommended to finish the evaluation of results obtained by experiments employing antibody-transferred mouse models within the first 2 weeks after the pathogenic antibody injection.

Nanoparticles prepared from porcine cells support the healing of cutaneous inflammation in mice and wound re-epithelialization in human skin.

Previous reports have demonstrated that cell-derived nanoparticles (CDNPs) composed of bovine or porcine protein complexes exerted therapeutic effects against viral infections and cancer in mice and humans. Based on these observations, we asked whether CDNPs would improve inflammatory skin disorders. To address this, we utilized two distinct mouse models of cutaneous inflammation: the autoimmune skin-blistering disease epidermolysis bullosa acquisita (EBA) as an example of an autoantibody-induced cutaneous inflammation, and Leishmania major (L. major) infection as an example of a pathogen-induced cutaneous inflammation. In both models, we observed that CDNPs increased mRNA expression of the Th2 cytokine IL-4. Clinically, CDNPs decreased inflammation due to EBA and increased L. major-specific IgG1 levels without major effects on infected skin lesions. In addition, CDNPs supported the growth of keratinocytes in human skin cultures. In vitro studies revealed that CDNPs were taken up predominantly by macrophages, leading to a shift towards the expression of anti-inflammatory cytokine genes. Altogether, our data demonstrate that treatment with porcine CDNPs may be a new therapeutic option for the control of autoimmune-mediated inflammatory skin disorders.

Caspase-1-independent IL-1 release mediates blister formation in autoantibody-induced tissue injury through modulation of endothelial adhesion molecules.

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-1ß in both mice with experimental EBA induced by injection of anti-COL7 IgG and in EBA patients. Increased IL-1α and IL-1ß 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-1ß. 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-1ß 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.