NADPH oxidase is required for neutrophil‐dependent autoantibody‐induced tissue damage

Abstract

The contribution of phagocyte-derived reactive oxygen species to tissue injury in autoimmune inflammatory diseases is unclear. Here we report that granulocyte nicotinamide adenine dinucleotide phosphate (NADPH) oxidase crucially contributes to tissue injury in experimental models of the antibody-mediated autoimmune disease epidermolysis bullosa acquisita. Neutrophil cytosolic factor 1-deficient mice lacking functional NADPH oxidase were resistant to skin blistering by the passive transfer of antibodies against type VII collagen. Pharmacological inhibition or deficiency of human NADPH oxidase abolished dermal-epidermal separation caused by autoantibodies and granulocytes ex vivo. In addition, recruitment of granulocytes into the skin was required for tissue injury, as demonstrated by the resistance to experimental blistering of wild-type mice depleted of neutrophils and of CD18-deficient mice. Transfer of neutrophil cytosolic factor 1-sufficient granulocytes into neutrophil cytosolic factor 1-deficient mice demonstrated that granulocytes provide the NADPH oxidase required for tissue damage. Our findings identify granulocyte-derived NADPH oxidase as a key molecular effector engaged by pathogenic autoantibodies and provide relevant targets for prevention of tissue damage in granulocyte-mediated autoimmune diseases.

GM-CSF Modulates Autoantibody Production and Skin Blistering in Experimental Epidermolysis Bullosa Acquisita

“…In line with this observation, CD18-deficient mice with impaired leukocyte extravasation into the skin (45) are also completely resistant to blister induction (41). Additionally, impaired release of ROS (41) or proteolytic enzymes (46) from neutrophils has similar protective effects. In this context, our findings provide novel insights into EBA pathogenesis: GM-CSF contributes to EBA-associated tissue injury by modulating several neutrophil functions (Fig.…”

“…For the effector phase of experimental EBA, that is, autoantibody-induced tissue injury, neutrophil depletion has been shown to protect mice from induction of skin blisters (41). In line with this observation, CD18-deficient mice with impaired leukocyte extravasation into the skin (45) are also completely resistant to blister induction (41).…”

“…Third, IC-mediated activation of neutrophils is also enhanced by GM-CSF, similar to that described for many, but not all, known neutrophil agonists (42). This enhancement of IC-induced neutrophil activation contributes to reactive oxygen release by neutrophils, which is required for autoantibody-induced tissue injury in different models of EBA (41). Additionally, GM-CSF may also enhance other effector functions of neutrophils, such as release of proinflammatory mediators or proteolytic enzymes (Fig.…”

“…Given the pivotal role of neutrophils in the development of autoantibody-induced tissue injury in this EBA model (41) and the effects of GM-CSF on neutrophil activation (5, 42), levels of circulating neutrophils were determined in both mouse strains 12 d after the injection of either anti-COL7 or NR-IgG. In NRIgG-injected C57BL/6 and GM-CSF 2/2 mice the proportion of circulating neutrophils was comparable, that is, 16.6 6 2.2 and 13.4 6 1.4%, respectively.…”

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

“…In vitro experiments extended these findings to additional endothelial adhesion molecules, such as VCAM-1 and E-selectin. Dependence on adhesion molecule expression in the pathogenesis of EBA was demonstrated by the observed absence of skin lesions in CD18-deficient mice after the injection of anti-COL7 IgG (23). Collectively, these data suggest that interactions of leukocyte b2 integrins (CD18) with endothelial adhesion molecules of the Ig superfamily are indispensable for blister formation in experimental EBA.…”