Humanization of autoantigen (1)
Vertebrates are capable of both adaptive and innate immunity, which is common to all metazoans, and are consequently exposed to autoimmune diseases—in which an aberrant, adaptive immune system recognizes a self-component as an autoantigen. transgenic mice expressing disease- associated human HLA alleles and T-cell receptors have been gener- ated, which have the potential to provide further insight into the pathogenesis of many diseases.
Col17-knockout (COL17 ) mice were born, blisters and erosions at sites of trauma were easily created by applying mild friction, and some pups exhibited spontaneous blister formation on their paws. The adult mice show genital erosions, hemorrhagic blisters around the digits, and diffuse, nonpigmented hair growth associated with hair loss.
Rescued COL17- humanized mice showed none of the abnormal manifestations seen in COL17m–/– mice. The COL17-humanized mice received intraperitoneal injections of both total and affinity-purified IgG directed against COL17, and developed diffuse erythema and a positive Nikolsky sign (epidermal separation elicited by gentle skin friction) at 48 h after injection. Histopathologic studies of lesional skin revealed a separation between the epidermis and the dermis, and an inflammatory cell infiltrate including neutrophils and lymphocytes.
The suppression efficacy of R1 was increased after fusion of glutathione S-transferase (GST). This R1-GST peptide reduced index values of BP-IgG in a dose-dependent manner in an in vitro binding assay. For in vivo studies, after intraperitoneal injection of 1 mg/g (body weight) total IgG from individuals with BP, the COL17- humanized mice were treated with R1-GST peptide (total dose of 600 ug, injected subcutaneously). This resulted in a marked reduction in blister formation, in contrast to controls treated with GST alone. BP antibody index value was also significantly decreased in the treated group.
A new model was developed by administering IgG fractions from individuals with BP into human skin grafted onto adult severe combined immunodeficient (SCID) mice. No blister formation was observed, however, although human IgG and mouse C3 were both deposited at the epidermal basement membrane zone of the grafted human skin.