The Flavonoid Luteolin Inhibits Fcγ-Dependent Respiratory Burst in Granulocytes, but Not Skin Blistering in a New Model of Pemphigoid in Adult Mice

Abstract

Bullous pemphigoid is an autoimmune blistering skin disease associated with autoantibodies against the dermal-epidermal junction. Passive transfer of antibodies against BP180/collagen (C) XVII, a major hemidesmosomal pemphigoid antigen, into neonatal mice results in dermal-epidermal separation upon applying gentle pressure to their skin, but not in spontaneous skin blistering. In addition, this neonatal mouse model precludes treatment and observation of diseased animals beyond 2–3 days. Therefore, in the present study we have developed a new disease model in mice reproducing the spontaneous blistering and the chronic course characteristic of the human condition. Adult mice were pre-immunized with rabbit IgG followed by injection of BP180/CXVII rabbit IgG. Mice pre-immunized against rabbit IgG and injected 6 times every second day with the BP180/CXVII-specific antibodies (n = 35) developed spontaneous sustained blistering of the skin, while mice pre-immunized and then treated with normal rabbit IgG (n = 5) did not. Blistering was associated with IgG and complement C3 deposits at the epidermal basement membrane and recruitment of inflammatory cells, and was partly dependent on Ly-6G-positive cells. We further used this new experimental model to investigate the therapeutic potential of luteolin, a plant flavonoid with potent anti-inflammatory and anti-oxidative properties and good safety profile, in experimental BP. Luteolin inhibited the Fcγ-dependent respiratory burst in immune complex-stimulated granulocytes and the autoantibody-induced dermal-epidermal separation in skin cryosections, but was not effective in suppressing the skin blistering in vivo. These studies establish a robust animal model that will be a useful tool for dissecting the mechanisms of blister formation and will facilitate the development of more effective therapeutic strategies for managing pemphigoid diseases.

Passive transfer of collagen XVII-specific antibodies induces sustained blistering disease in adult mice

“…In addition, they recruited murine leukocytes and induced skin blistering thus reproducing the human BP at the clinical, immunological and histopathological levels. These findings are in line with similar results of inflammatory blistering in another newly developed passive antibody transfer model of pemphigoid disease in which we pre-immunized adult mice with rabbit IgG followed by injection of collagen XVII-specific rabbit IgG [43]. While having the advantage of an increased inflammatory reaction and more extensive disease in mice compared with the mouse model presented here, the model reported by Oswald et al , has some limitations due to the active immunization with the rabbit IgG, which pose constraints for designing studies addressing the pathophysiology of the pemphigoid disease in patients.…”

Neutrophils in animal models of autoimmune disease

“…To model both the initiation phase and the effector phase of these diseases, models in adult animals relying on extensive immunization with BP180 or collagen VII have been established. In the immunization models, neutrophil depletion is partially effective in reducing disease [85]. Interestingly, in the immunization-induced EBA model, chronic depletion of neutrophils (or use of GM-CSF knockout mice) leads to reduced autoantibody titers, with reduced skin inflammation [86].…”

Innate Immune Cell–Produced IL-17 Sustains Inflammation in Bullous Pemphigoid

“…Animal model studies showed the critical role of autoimmune complexes in triggering the inflammatory process leading to the DEJ disruption and subsequently to blister formation (Liu et al 1993)(Hirose et al 2011)(Oswald et al 2012). …”