Topically applied flightless I neutralizing antibodies improve healing of blistered skin in a murine model of epidermolysis bullosa acquisita.

Epidermolysis bullosa (EB) is a chronic inheritable disease that leads to severe blistering and fibrosis. Previous studies have shown that the actin cytoskeletal protein flightless I (Flii) impairs wound healing associated with EB. Using a mouse model of EB acquisita (EBA), the effect of "mopping up" Flii using Flii-neutralizing antibodies (FnAbs) before, during, and after blister formation was determined. FnAbs, incorporated into a cream vehicle and applied topically to the skin, penetrated into the basal epidermis and upper papillary dermis but were not detected in serum or other organs and did not alter neutrophil or macrophage infiltration into the blistered skin. Histological assessment of blister severity showed that treatment of early-stage blisters with FnAb cream reduced their severity and improved their rate of healing. Treatment of established blisters with FnAb cream also improved healing and restored the skin's tensile strength toward that of normal skin. Repeated application of FnAbs to EBA skin before the onset of blistering reduced the severity of skin blistering. Independent of when the FnAbs were applied, skin barrier function and wound healing were improved and skin fragility was reduced, suggesting that FnAbs could potentially improve healing of patients with EB.