Estradiol‐regulated Innate Antiviral Responses of Human Endometrial Stromal Fibroblasts

ProblemThe contribution of fibroblasts to innate immune protection of the human female reproductive tract (FRT) against viral pathogens is relatively unknown.Method of StudyEndometrial (EM), endocervical (Cx) and ectocervical (ECx) fibroblasts were isolated from hysterectomy patients and grown in vitro. Fibroblasts were treated with the viral mimic poly (I:C) in the presence or absence of the sex hormone estradiol (E2), with gene expression measured by real‐time RT‐PCR and protein secretion by ELISA.ResultsPoly (I:C) induced the expression of the interferon‐stimulated genes (ISG) MxA, OAS2 and APOBEC3G, and the cytokines MCP‐1, IL‐8, IL‐6, CCL20, IFNβ and RANTES by fibroblasts from all three sites. ISG upregulation was dependent upon Type I IFN signaling. E2 inhibited the poly (I:C)‐induced upregulation of MxA and OAS2 in EM fibroblasts, but not Cx or ECx fibroblasts. E2 upregulated SDF‐1α by EM fibroblasts but had no effect on secretion of other cytokines either alone or in the presence of poly (I:C). Conditioned media (CM) from poly (I:C)‐treated or E2‐treated fibroblasts significantly reduced HIV infection of CD4+ T cells.ConclusionStromal fibroblasts represent a level of innate immune protection against viral pathogens in the FRT beyond that seen with epithelial cells and immune cells. Our findings indicate that fibroblasts FRT are selectively responsive to E2, capable of initiating an antiviral response against viral pathogens and may play a role in preventing HIV infection of CD4+ T cells.