Berberine alleviates inflammation in polycystic ovary syndrome by inhibiting hyaluronan synthase 2 expression

Abstract

Background: Polycystic ovary syndrome (PCOS) is a heterogeneous metabolic and endocrine disorder that causes anovulatory infertility and abnormal folliculogenesis in women of reproductive age. Several studies have revealed inflammation in PCOS follicles, and recent evidence suggests that Berberine (BBR) effectively reduces inflammatory responses in PCOS, however, the underlying mechanisms remain unclear.

Purpose: To determine the underlying mechanisms by which BBR alleviates inflammation in PCOS.

Study design: Primary human GCs from healthy women and women with PCOS, and KGN cells were used for in vitro studies. ICR mice were used for in vivo studies.

Methods: Gene expression was measured using RT-qPCR. HAS2, inflammatory cytokines, and serum hormones were assayed by ELISA. Protein expression profiles were assayed by Western blot. Chronic low-grade inflammatory mouse models were developed by intraperitoneal injection with LPS, and PCOS mouse models were established by subcutaneous intraperitoneal injection of DHEA. BBR and 4-MU were administered by gavage. Ovarian morphologic changes were evaluated using H&E staining. HAS2 expression in the ovary was assayed using Western blot and immunohistochemistry.

Results: Our results confirmed that HAS2 expression and hyaluronan (HA) accumulation are closely associated with inflammatory responses in PCOS. Data obtained from in vitro studies showed that HAS2 and inflammatory genes (e.g., MCP-1, IL-1β, and IL-6) are significantly upregulated in PCOS samples and LPS-induced KGN cells compared to their control groups. In addition, these effects were reversed by blocking HAS2 expression or HA synthesis using BBR or 4-MU, respectively. Furthermore, HAS2 overexpression induces the expression of inflammatory genes in PCOS. These results were further confirmed in LPS- and DHEA-induced mouse models, where inflammatory genes were reduced by BBR or 4-MU, and ovarian morphology was restored.

Conclusions: Our results define previously unknown links between HAS2 and chronic low-grade inflammation in the follicles of women with PCOS. BBR exerts its anti-inflammatory effects by down-regulating HAS2. This study provides a novel therapeutic target for alleviating ovarian inflammation in women with PCOS.

Keywords: Berberine; Granulosa cell; HAS2; Inflammation; PCOS.