In Vitro Silencing of MHC-I in Keratinocytes by Herpesvirus US11 Protein to Model Alloreactive Suppression.

Abstract

Background: Secondary rejection remains a major obstacle in skin allografting. Some viruses, such as human herpesvirus and cytomegalovirus, evade immune detection through proteins like the unique short glycoprotein 11 (US11), which down-regulates major histocompatibility complex (MHC) class I expression. This study explores the use of recombinant US11 protein as a biopharmaceutical approach to reduce MHC-I expression and thus decrease alloreactivity in human primary keratinocytes.

Methods: Human keratinocytes were treated with recombinant US11 protein, and MHC-I expression was assessed via Western blot and flow cytometry. To evaluate immunomodulatory effects, US11-stimulated keratinocytes were co-cultured with peripheral blood mononuclear cells (PBMCs), and interferon-gamma (IFN-γ) levels were measured by ELISA. Additionally, ex vivo human skin tissue was stimulated with US11 to assess long-term MHC-I modulation.

Results: US11 treatment significantly reduced MHC-I surface expression in keratinocytes. Co-cultures showed decreased IFN-γ secretion, indicating lower T cell activation. Human skin tissue stimulated with US11 exhibited reduced MHC-I expression after 7 days.

Conclusions: This proof-of-concept study suggests that recombinant US11 protein may serve as an effective biopharmaceutical to reduce keratinocyte immunogenicity. Further in vitro and in vivo studies are warranted to validate its potential for clinical application in skin transplantation.