Toll‐Like Receptor Expression and Function in the COV434 Granulosa Cell Line

Abstract

Bacterial infections perturb ovarian follicle function, despite the lack of immune cells such as macrophages within healthy ovarian follicles. This study examined whether the granulosa cells that line ovarian follicles could, like macrophages, use Toll-like receptors (TLRs) to detect pathogen-associated molecular patterns (PAMPs) and initiate inflammation. The COV434 human granulosa and THP-1 macrophage cell lines were used to determine the expression of TLRs and measure the production of cytokines, chemokines and estradiol in response to the PAMPs lipopolysaccharide, peptidoglycan, lipoteichoic acid and flagellin from bacteria. The THP-1 and granulosa cells expressed mRNA for TLR1-10 and TLR4-10, respectively. The supernatants of THP-1 cells accumulated IL-1β, IL-6, IL-8 and CCL5 in response to PAMPs. Treatment of granulosa cells with PAMPs increased expression of IL1B mRNA after 3hr, but did not change the accumulation of IL-1β, IL-6, IL-8, CCL5 or estradiol. Granulosa cells produced IL-8 constitutively, and this was reduced using chemical inhibitors for p38 and JNK mitogen-activated protein kinases. The COV434 human granulosa cell line expresses TLRs and constitutively secretes IL-8 but only mounts an inflammatory response to PAMPs at the transcriptional level.