Lipopolysaccharide endotoxin triggers inflammatory responses that disrupt granulosa cell function and alter cell growth dynamics

Abstract

Gram-negative bacterial release of the endotoxin lipopolysaccharide (LPS) perturbs granulosa cell signaling resulting in reduced estradiol synthesis and disrupted folliculogenesis thereby compromising fertility. While elevated LPS from clinical infections impairs female reproduction, the effects of low-level LPS from subclinical infections remain poorly defined. This study examined increasing LPS concentrations on granulosa cell growth dynamics, immune responses, and steroidogenesis. Human granulosa (KGN) cells were cultured for 48 h with vehicle or LPS (0.0001–10 µg/mL), with or without follicle-stimulating hormone (FSH). No significant LPS × FSH interaction was detected on steroidogenic gene expression (all P ≥ 0.95). LPS increased STAR mRNA abundance with the greatest expression at 10 µg/mL LPS compared to lower concentrations (P ≤ 0.04). Cells treated with FSH demonstrated decreased CTNNB1 (P = 0.0007) and increased CYP19A expression (P = 0.003), while LPS alone had no effect on either gene. Pro-inflammatory gene expression was affected by LPS. LPS dose-dependently increased IL-6, IL-8 and MCP-1 expression in KGN cells, at 1 and 10 µg/mL, while NF-κB expression was unaffected by LPS, FSH or their interaction. Media progesterone (P₄; P = 0.99) and estradiol (E₂: P = 0.50) concentrations were unaffected by LPS. Live imaging revealed no change in cell confluency at 0.01 µg/mL or 0.1 µg/mL LPS, while 1 µg/mL and 10 µg/mL LPS reduced confluency over 48 h (P = 0.06 and P = 0.02, respectively). KGN cells responded to low-dose LPS with elevated pro-inflammatory cytokine expression. In conclusion, higher LPS concentrations suppress granulosa cell proliferation, an effect mitigated by FSH, indicating that gonadotropic input may protect against LPS-induced ovarian dysfunction.