Epidermolysis bullosa acquisita (EBA) is an autoimmune blistering disease, characterized by antibodies to type VII collagen (COL7). EBA can be induced in mice by immunization with a fragment of the non-collagenous 1 domain of murine COL7. Contrary to other autoimmune diseases, e.g., rheumatoid arthritis, little is known about the genetic susceptibility for EBA. We therefore used the EBA mouse model to address the hypothesis that disease induction depends on the major histocompatibility complex (MHC) haplotype. Mice from different inbred strains were immunized with recombinant murine COL7. Five distinct responses were observed: induction of (i) severe disease in SJL/J (H2s) and female MRL/MpJ (H2k), (ii) mild and transient disease in C57Bl/10.s (H2s), (iii) microscopic blistering in DBA/1J (H2q), (iv) only presence of non-pathogenic autoantibodies in C57Bl/6J (H2b), NZM2410/J (H2z), BXD2 (H2b), and male MRL/MpJ, and (v) complete resistance to EBA in NOD/ShiLtJ (H2g7) and C57Bl/10.q (H2q) mice. Overall, susceptibility to EBA was strongly associated with H2s. In addition, the diseased phenotype was associated with autoantibodies to specific regions of COL7. Our findings show that induction of antibodies with a distinct specificity is linked to the MHC haplotype in experimental EBA. Furthermore, our data are the basis for future studies with the goal of identifying non-MHC EBA susceptibility genes.
Host defense against pathogens relies on neutrophil activation. Inadequate neutrophil activation is often associated with chronic inflammatory diseases. Neutrophils also constitute a significant portion of infiltrating cells in chronic inflammatory diseases; eg psoriasis and multiple sclerosis. Fumarates improve the latter diseases, which so far has been attributed to effects on lymphocytes and dendritic cells. Here, we focused on effects of dimethyl fumarate (DMF) on neutrophils. In vitro, DMF inhibited neutrophil activation, including changes in surface marker expression, reactive oxygen species production, formation of neutrophil extracellular traps and migration. Phagocytic ability and autoantibody-induced, neutrophil-dependent tissue injury ex vivo was also impaired by DMF. Regarding the mode of action, DMF modulates -in a stimulus-dependent manner- neutrophil activation using the PI3K/Akt-p38 MAPK- and ERK 1/2 pathways. For in vivo validation, mouse models of epidermolysis bullosa acquisita (EBA), an organ-specific autoimmune disease caused by autoantibodies to type VII collagen (COL7), were employed. In the presence of DMF, blistering induced by injection of anti-COL7 antibodies into mice was significantly impaired. DMF treatment of mice with clinically already manifested EBA led to disease improvement. Collectively, we demonstrate a profound inhibitory activity of DMF on neutrophil functions. These findings encourage wider use of DMF in patients with neutrophil-mediated diseases.Journal of Investigative Dermatology accepted article preview online, 05 October 2015. doi:10.1038/jid.2015.361.
This study has identified QTLs and putative candidate genes of murine AIP. Their functional role and relevance to human AIP will be studied further.
GM-CSF activates hematopoietic cells and recruits neutrophils and macrophages to sites of inflammation. Inhibition of GM-CSF attenuates disease activity in models of chronic inflammatory disease. Effects of GM-CSF blockade were linked to modulation of the effector phase, whereas effects on early pathogenic events, for example, Ab production, have not been identified. To evaluate yet uncharacterized effects of GM-CSF on early pathogenic events in chronic inflammation, we employed immunization-induced epidermolysis bullosa acquisita (EBA), an autoimmune bullous disease caused by autoantibodies to type VII collagen. Compared to wild-type mice, upon immunization, GM-CSF−/− mice produced lower serum autoantibody titers, which were associated with reduced neutrophil numbers in draining lymph nodes. The same effect was observed in neutrophil-depleted wild-type mice. Neutrophil depletion in GM-CSF−/− mice led to a stronger inhibition, indicating that GM-CSF and neutrophils have additive functions. To characterize the contribution of GM-CSF specifically in the effector phase of EBA, disease was induced by transfer of anti–type VII collagen IgG into mice. We observed an increased GM-CSF expression, and GM-CSF blockade reduced skin blistering. Additionally, GM-CSF enhanced reactive oxygen species release and neutrophil migration in vitro. In immunization-induced murine EBA, treatment with anti–GM-CSF had a beneficial effect on established disease. We demonstrate that GM-CSF modulates both autoantibody production and skin blistering in a prototypical organ-specific autoimmune disease.
Autoimmune diseases are rare, but their incidence has increased over the past decades. Interestingly, the co-occurrence of autoimmune diseases is well documented; however, data on the presence of more than one specific autoantibody in healthy individuals are not available. Here, we investigated the prevalence of several autoantibodies in a cohort of over 6000 healthy persons. While individual autoantibodies were rarely detected (i.e. ranging from 0.3% for ANCA to 4.6% for anti-TPO), the cumulative prevalence of the tested autoantibodies was as high as 10%. Furthermore, our results demonstrate co-occurrence of ANA with specific autoantibodies that target TPO, CCP and Dsg1/3, while ANCA and autoantibodies to PCA and BP180/BP230 were not more frequent in ANA-positive compared to ANA-negative samples. This indicates that shared and independent mechanisms influence loss of tolerance to distinct sets of self-antigens.
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