Human granulosa–luteal cells initiate an innate immune response to pathogen-associated molecules

Abstract

The microenvironment of the ovarian follicle is key to the developmental success of the oocyte. Minor changes within the follicular microenvironment can significantly disrupt oocyte development, compromising the formation of competent embryos and reducing fertility. Previously described as a sterile environment, the ovarian follicle of women has been shown to contain colonizing bacterial strains, whereas in domestic species, pathogen-associated molecules are concentrated in the follicular fluid of animals with uterine infection. The aim of this study is to determine whether human granulosa-luteal cells mount an innate immune response to pathogenassociated molecules, potentially disrupting the microenvironment of the ovarian follicle. Human granulosa-luteal cells were collected from patients undergoing assisted reproduction. Cells were cultured in the presence of pathogen-associated molecules (LPS, FSL-1 and Pam3CSK4) for 24 h. Supernatants and total RNA were collected for assessment by PCR and ELISA. Granulosa-luteal cells were shown to express the molecular machinery required to respond to a range of pathogen-associated molecules. Expression of TLR4 varied up to 15-fold between individual patients. Granulosa-luteal cells increased the expression of the inflammatory mediators IL1B, IL6 and CXCL8 in the presence of the TLR4 agonist E. coli LPS. Similarly, the TLR2/6 ligand, FSL-1, increased the expression of IL6 and CXCL8. Although no detectable changes in CYP19A1 or STAR expression were observed in granulosa-luteal cells following challenge, a significant reduction in progesterone secretion was measured after treatment with FSL-1. These findings demonstrate the ability of human granulosa-luteal cells to respond to pathogen-associated molecules and generate an innate immune response.Reproduction (2016) 152 261-270

Effects of LPS on the accumulation of lipid droplets, proliferation, and steroidogenesis in goat luteinized granulosa cells

“…In the current study, LPS‐induced decrease in E 2 and P 4 were accompanied by the decreased 3β‐HSD expression, the key enzyme associated with P 4 synthesis. Our finding that LPS had no effect on the expression of CYP19A1 protein was similar to the study that no changes in the CYP19A1 expression in granulosa‐luteal cells following LPS treatment . This discrepancy from the mentioned reported changes to CYP19A1 expression might be due to that our experiment was carried out in goat LGCs, not GCs.…”

Age‐related changes in the bovine corpus luteum function and progesterone secretion

“…Our in vitro experiment showed that a low dose of LPS (100 ng/ml) had no effect on P4 secretion or StAR expression, but it stimulated the mRNA expression of 3β-HSD in the CL tissue culture both in young and aged groups. Similar with our results, no detectable changes in P4 secretion and StAR expression were observed in human granulosa-luteal cells following low-dose LPS treatment (100 ng/ml; Ibrahim et al, 2016). In contrast, it has been reported that highdose LPS treatment (1 µg/ml) reduced P4 secretion from bovine granulosa cells (Bromfield & Sheldon, 2011;Price et al, 2013), and in vivo administration of LPS (0.5 µg/kg) induced a transient increase in P4 concentration within the first 3 hr but it declined subsequently (Herzog et al, 2012) 2011;Ibrahim et al, 2016;Price et al, 2013).…”

“…LPS from Gram‐negative bacteria is the main pathogen causing metritis and mastitis in cows (Luttgenau, Lingemann, et al, ; Luttgenau, Wellnitz, et al, ), and it is used as a major factor for the induction of inflammation and pathology both in vivo and in vitro (Bromfield & Sheldon, ; Herzog et al, ; Ibrahim, Kramer, Williams, & Bromfield, ; Price, Bromfield, & Sheldon, ). Therefore, we used LPS to induce inflammatory responses because the LPS/Toll‐like receptor 4 (receptor for LPS) system has a potential to regulate the luteal function (Bromfield & Sheldon, ; Ibrahim et al, ; Price et al, ). Our in vitro experiment showed that a low dose of LPS (100 ng/ml) had no effect on P4 secretion or StAR expression, but it stimulated the mRNA expression of 3β‐HSD in the CL tissue culture both in young and aged groups.…”

“…The differences in various effects of LPS on P4 secretion are not fully explainable, we suggest that certain experimental differences, such as doses of LPS, duration of LPS treatment, and experimental conditions of in vitro and in vivo tests, could be responsible for various responses to LPS. On the other hand, it has been demonstrated that LPS treatment significantly stimulated the secretion of SASP‐related cytokines and expression of IL‐8 , IL‐6 and IL‐1β in a dose‐ and time‐dependent manner in bovine and human granulosa cells (Bromfield & Sheldon, ; Ibrahim et al, ; Price et al, ). The present study also showed that LPS treatment increases IL‐8 mRNA expression in the CL tissue, whereas there was no difference in their expression between young and aged cows.…”

Lipopolysaccharide and tumor necrosis factor‐alpha alter gene expression of oocytes and cumulus cells during bovine in vitro maturation

“…In parallel, Toll-like receptors (TLRs) are involved in the immune response to pathogens, and when activated by bacterial LPS increase expression of cytokines such as interleukin (IL)-1β, IL-6, IL-8, and TNF-α. Granulosa cells of hens, pigs, cows, mice, and humans express TLRs and respond to bacterial LPS to increase expression of proinflammatory cytokines (Alvarez et al, 2006;Bromfield & Sheldon, 2011;Ibrahim, Kramer, Williams, & Bromfield, 2016;Price, Bromfield, & Sheldon, 2013). Uterine infections are common in cows, and subsequently LPS accumulates in follicular fluid, altering the microenvironment of oocyte development (Herath et al, 2007;Piersanti et al, 2019).…”