TLR9 and RIG-I Signaling in Human Endocervical Epithelial Cells Modulates Inflammatory Responses of Macrophages and Dendritic Cells In Vitro

Abstract

The innate immune system has evolved to recognize invading pathogens through pattern recognition receptors (PRRs).Among PRRs, Toll like receptors (TLRs 3, 7/8,9) and RIG-I like receptors (RLRs) have been shown to recognize viral components. Mucosal immune responses to viral infections require coordinated actions from epithelial as well as immune cells. In this respect, endocervical epithelial cells (EEC's) play an important role in initiating innate immune responses via PRRs. It is unknown whether EEC's can alter immune responses of macrophages and dendritic cells (DC's) like its counterparts in intestinal and respiratory systems. In this study, we show that endocervical epithelial cells (End1/E6E7) express two key receptors, TLR9 and RIG-I involved in anti-viral immunity. Stimulation of End1/E6E7 cells lead to the activation of NF-κB and increased secretion of pro-inflammatory cytokines, IL-6 and IL-8. Polarized End1/E6E7 cells responded to apical stimulation with ligands of TLR9 and RIG-I, CpG-ODN and Poly(I:C)LL respectively, without compromising End1/E6E7 cell integrity. At steady state, spent medium from End1/E6E7 cells significantly reduced secretion of pro-inflammatory cytokines from LPS treated human primary monocyte derived macrophages (MDMs) and DC:T cell co-cultures. Spent medium from End1/E6E7 cells stimulated with ligands of TLR9/RIG-I restored secretion of pro-inflammatory cytokines as well as enhanced phagocytosis and chemotaxis of monocytic U937 cells. Spent medium from CpG-ODN and Poly(I:C)LL stimulated End1/E6E7 cells showed significant increased secretion of IL-12p70 from DC:T cell co-cultures. The anti-inflammatory effect of spent media of End1/E6E7 cell was observed to be TGF-β dependent. In summary, the results of our study indicate that EEC's play an indispensable role in modulating anti-viral immune responses at the female lower genital tract.

In Vitro Activity of Quaternary Ammonium Surfactants against Streptococcal, Chlamydial, and Gonococcal Infective Agents

“…The QAS toxicity ranking for both cell lines was C 12 PB Ϸ C 12 BZK Ͼ C 12 TAB. Despite the fact that, contrary to HeLa cells, End1 cells can be fully polarized in vitro, resembling the morphological characteristics of epithelial cells of the vaginal mucosa (14), maturity of tight junctions is achieved only after 8 to 10 days in culture (22). Consequently, under our experimental conditions, End1 cells lack mature nonleaky tight junctions, justifying the similar IC 50 s determined for End1 and HeLa cells.…”

Wogonin inhibits Varicella-Zoster (shingles) virus replication via modulation of type I interferon signaling and adenosine monophosphate-activated protein kinase activity

“…TLR9 is a DNA sensor involved in IFN production and inflammation pathways induced by viral infections (Sathe & Reddy, 2014;Uematsu & Akira, 2007). Therefore, we investigated TLR9 expression in HFFs infected with VZV, for the indicated times.…”

Mucosal Dendritic Cells

“…Nevertheless, virus infection is likely sensed by both the hematopoietic and nonhematopoietic compartments for the full induction of T cell-mediated adaptive immunity against genital HSV-2 infection (Sato and Iwasaki, 2004). TLR9 and RIG-I stimulation of human cervical epithelial cells are shown to induce DC activation and phagocytosis in a coculture system (Sathe and Reddy, 2014).…”