1262 HSP70iQ435A-encoding DNA repigments vitiligo lesions in Sinclair swine

Abstract

HSP70iQ435A carries an amino acid modification within the substrate binding domain, resulting in a stress protein that can tolerize dendritic cells in vitro. Introduced by gene gun, an expression plasmid encoding HSP70iQ435A can both prevent and treat autoimmune disease in mouse models of vitiligo. Here we tested the efficacy and safety of human HSP70iQ435A encoding DNA in human-like skin. We compared available methods of introducing DNA to porcine skin before subcloning HSP70iQ435A into clinically suitable vector pUMVC3. Next, vitiligo lesions in a substrain of Sinclair swine were treated with up to 5 mg plasmid DNA (N=6 lesions) or vehicle (N=4) weekly for 4 weeks to measure changes in lesional area, CD4 and CD8 T cell infiltration and serum HSP70 content and HSP70 antiserum titers in monthly biopsies and blood samples. After the gene gun, jet injection demonstrated greatest plasmid-encoded gene expression. Whereas untreated lesions continued to enlarge, significant repigmentation in response to HSP70iQ435A-encoding DNA lasted throughout the 6 months follow-up. Thus, serial samples of repigmenting, human-like skin and associated serum samples are now available to study the repigmentation process. Repigmentation was accompanied by an initial influx of CD4 T cells, followed by a significant reduction in perilesional T cells 3 months after treatment. Ta99+ melanocytes were 50% less plentiful but not absent from repigmenting skin, suggesting that melanocyte repopulation precedes skin melanization. No treatment-related changes in HSP70 or anti-HSP70 titers were observed. Importantly, treatment did not interfere with but rather supported melanoma immunosurveillance. These data encourage clinical testing of HSP70iQ435A.