Granulocyte‐derived elastase and gelatinase B are required for dermal–epidermal separation induced by autoantibodies from patients with epidermolysis bullosa acquisita and bullous pemphigoid

Abstract

Epidermolysis bullosa acquisita (EBA) and bullous pemphigoid (BP) are two clinically and immunologically distinct autoimmune subepidermal blistering skin diseases associated with IgG autoantibodies against the dermal-epidermal junction. BP antibodies are directed against the hemidesmosomal antigens BP180 and BP230, and those in patients with EBA target type VII collagen, a major component of anchoring fibrils. While the pathogenetic mechanisms of subepidermal blistering in BP have been previously studied using a passive transfer mouse model, the effector pathways of blister formation in EBA are largely unknown. Autoantibodies to type VII collagen and BP180 have recently been shown to induce leucocyte-mediated subepidermal cleavage in cryosections of human skin. The aim of the present study was to identify human leucocyte protease(s) instrumental in dermal-epidermal separation induced by autoantibodies to type VII collagen and BP180. When incubated with cryosections of human skin pretreated with IgG from patients with EBA or BP but not from patients with anti-laminin 5 mucous membrane pemphigoid or healthy controls, granulocytes were recruited to the dermal-epidermal junction and induced subepidermal splits. A combination of broad-range protease inhibitors as well as inhibitors of serine and matrix metalloproteases completely abolished dermal-epidermal separation induced by EBA or BP autoantibodies. When characterizing the proteases involved more specifically, selective inhibition of human leucocyte elastase or gelatinase B/MMP-9 was also found to result in suppression of blistering. These findings strongly suggest that elastase and gelatinase B are essential for granulocyte-mediated proteolysis resulting in dermal-epidermal separation in EBA and BP patients' skin.

Identification and Characterization of Circulating Variants of CXCL12 from Human Plasma: Effects on Chemotaxis and Mobilization of Hematopoietic Stem and Progenitor Cells

“…In contrast, CXCL12 was not identified in our in vitro CXCL12-processing experiments performed with human granulocytes and was not identified in the purified material from blood filtrate, although the CXCL12[26-88]-producing protease MMP-9 is primarily expressed in granulocytes. This discrepancy may be correlated to insufficient proteolytic activation, as MMP-9 is released as an inactive zymogen [36,37]. Although human neutrophil elastase is suggested to prime activation of proMMP-9 [38], the activation of MMP-9 in the context of granulocyte activation on the hemofilter membranes may not be sufficient for the generation of FIG.…”

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

“…Only cell preparations with viability above 95% as assessed by trypan blue exclusion were used. These consisted of Ͼ90% granulocytes as revealed by Giemsa staining and by flow cytometry as described previously (8). Granulocytes were defined as Gr-1 high CD11b high using mAb specific to murine Gr-1 (RB6-8C5) and to CD11b (M1/70) (both from BD Biosciences).…”

Tissue inhibitor of metalloproteinase 1, matrix metalloproteinase 9, αlpha-1 antitrypsin, metallothionein and urokinase type plasminogen activator receptor in skin biopsies from patients affected by autoimmune blistering diseases

“…Some involve plasminogen activation, desmoglein compensation, acetylcholine receptor antibodies, and intracellular signal control of autoantibodies [1]. Moreover, human autoantibodies and the presence of complement are primary factors in producing the blisters of human autoimmune skin blistering diseases and are thought to exert their pathogenic effect via proteases [2,3]. Few studies have tested for proteases and protease inhibitors in lesional skin from patients affected by ABDs [4,5].…”