Stevens-Johnson syndrome (SJS) and toxic epidermal necrolysis (TEN) are life-threatening mucocutaneous adverse drug reactions characterized by massive epidermal detachment. Cytotoxic T cells and associated effector molecules are known to drive SJS/TEN pathophysiology, but the contribution of innate immune responses is not well understood. We describe a mechanism by which neutrophils triggered inflammation during early phases of SJS/TEN. Skin-infiltrating CD8+ T cells produced lipocalin-2 in a drug-specific manner, which triggered the formation of neutrophil extracellular traps (NETs) in early lesional skin. Neutrophils undergoing NETosis released LL-37, an antimicrobial peptide, which induced formyl peptide receptor 1 (FPR1) expression by keratinocytes. FPR1 expression caused keratinocytes to be vulnerable to necroptosis that caused further release of LL-37 by necroptotic keratinocytes and induced FPR1 expression on surrounding keratinocytes, which likely amplified the necroptotic response. The NETs-necroptosis axis was not observed in less severe cutaneous adverse drug reactions, autoimmune diseases, or neutrophil-associated disorders, suggesting that this was a process specific to SJS/TEN. Initiation and progression of SJS/TEN keratinocyte necroptosis appear to involve a cascade of events mediated by innate and adaptive immune responses, and understanding these responses may contribute to the identification of diagnostic markers or therapeutic targets for these adverse drug reactions.
Summary Background More than half of patients with pemphigus experience relapse during the disease course. The risk factors and clinical and immunological characteristics of relapse remain largely unclear. Objectives To elucidate the risk factors and clinical features of pemphigus relapse. Methods We carried out a retrospective review of the clinical records of 42 cases of pemphigus at a single centre. Results Sixty‐two per cent of patients experienced relapse, usually when oral prednisolone was tapered to around 0·1 mg kg−1. In mucocutaneous pemphigus vulgaris (mcPV), the initial doses (mean ± SD) of prednisolone were significantly lower in patients with relapse (0·78 ± 0·24 mg kg−1) than in those without relapse (1·01 ± 0·01 mg kg−1). At relapse, mcPV shifted to mucosal dominant PV (mPV; 40%), pemphigus foliaceus (PF) (20%) or ‘other’ (20%). In contrast, relapsing mPV and PF had the same clinical phenotypes as the initial phenotypes. Patients with both anti‐desmoglein (Dsg)1 and anti‐Dsg3 antibodies at onset had recurrence with anti‐Dsg3 antibodies alone (40%), with both anti‐Dsg1 and anti‐Dsg3 antibodies (30%), with anti‐Dsg1 antibody alone (20%) or were subthreshold (10%). Conclusions mcPV shows transitions in clinical phenotype and autoantibody profile at relapse. At least 1 mg kg−1 daily of prednisolone, especially for patients with mcPV, and prudent tapering around 0·1 mg kg−1 may lead to better outcomes.
Mucous membrane pemphigoid (MMP) is a rare organ-specific autoimmune subepithelial blistering disease with predominantly mucosal erosions, most frequently affecting the gingiva. Erosions in the oral cavity usually result in markedly decreased quality of life. The major autoantigens are BP180 and laminin332, which are components of basement membrane proteins in the skin and mucosa. Diagnosis is usually difficult due to histological destruction of the tissue and low autoantibody titers. In this study, we evaluated the diagnostic value of direct immunofluorescence (DIF) using non-lesional buccal mucosa in seven cases of MMP. In all seven patients, gingival lesions were clinically observed, and in one of the seven patients, buccal lesions were also clinically observed. First, we performed DIF to detect tissue-bound autoantibodies and complement. DIF from non-lesional buccal mucosa revealed linear deposits of IgG and C3 at the basement membrane zone in all cases. To detect autoantibodies, indirect immunofluorescence (IIF), BP180-NC16A ELISA and immunoblotting were performed. Surprisingly, circulating autoantibodies were unable to be detected in any of the cases by ELISA, IIF, or immunoblotting. Furthermore, histological separation was observed in one patient. In conclusion, DIF using non-lesional buccal mucosa was found to be superior to histological and serological tests for diagnosing mucous membrane pemphigoid. The procedure is technically easy and has high diagnostic value.
We successfully established iPSC-derived MSCs from keratinocytes (KC-iPSC-MSCs) of a normal human and an RDEB patient. KC-iPSC-MSCs may have potential in therapies for RDEB.
These results suggest that fluctuations in chemokine levels may contribute in a coordinated way to the wound-healing process and lend clues toward efficient cell therapies for EB.
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