Pellino1 promotes immunity in the skin during infection with herpes simplex virus (HSV)

Abstract Pellino1 (Peli1) is a ubiquitin ligase involved in IL-1 and Toll-like receptor signaling; however, the role of Pellino1 in skin immunity against HSV is unknown. Here, using the mouse flank HSV-1 skin infection model, we demonstrate that Pellino1 has several critical functions during active viral replication. Analyses of single cell genome wide gene expression data (RNA-seq) revealed expression of Peli1mRNA throughout the skin including in epithelial, fibroblast and immune cells. Both histology and RNA-seq demonstrated normal development of the epidermis and dermis in Pellino1 knockout (KO) mice. The median survival of Pellino1 KO mice was 12 days compared to greater than 16 days in wild type mice. Pellino1 deficient mice also developed larger zosteriform skin lesions along affected dermatomes. During infection HSV-1 did not replicate in the dermis. Immunohistochemistry revealed delayed recruitment of myeloid and T cells to early infected epidermis in Pellino1 deficient mice. This correlated with lower expression of the inflammatory IL-1 and IL-36 cytokines and the poorly understood chemokine Grp15l. In Pellino1 KO mice, the virus spread extensively through the epidermis, follicular infundibulum into sebaceous glands where sebocytes were found positive for the virus. Histological analyses for HSV-1 and neuronal axons revealed nerve endings throughout the epidermis and axons wrapped around the hair follicles. Dissemination of HSV-1 into the sebaceous glands did not appear to involve a shift in how the virus migrated through these nerve axons as early lesions were only found in the interfollicular epidermis. In conclusion, Pellino1 plays important roles in restricting viral dissemination. Supported by grant from NIH (R01 AI125111)