Mesenchymal stem cells improve ovarian function by suppressing fibrosis through CTGF/FAK signalling in systemic lupus erythematosus

OBJECTIVE: SLE is a multisystem autoimmune disease characterised by chronic inflammation and progressive organ damage, including ovarian dysfunction. This study investigated the therapeutic efficacy of umbilical cord-derived mesenchymal stem cells (UC-MSCs) in ameliorating ovarian impairment and restoring ovarian function through the inhibition of fibrosis in a lupus mouse model. METHODS: Serum levels of sex hormones were quantified via ELISA. Ovarian tissue samples were histologically evaluated for follicle count and fibrosis via H&E and Masson's trichrome staining. Quantitative reverse-transcriptase-PCR, western blot, immunofluorescence and immunohistochemistry were employed to evaluate inflammatory cytokines, fibrotic factors, hormone receptors and signalling proteins. Primary granulosa cells (GCs) isolated from lupus mice (MRL/lpr) were cocultured with MSCs and the expression of fibrotic factors was analysed by western blot. Additionally, a human GC line (KGN) was used to further explore the relationships among connective tissue growth factor (CTGF), focal adhesion kinase (FAK)/FAK-Tyr576/577 phosphorylation and fibrosis. This was achieved through stimulation with recombinant CTGF, the CTGF antagonist FG-3019 or the FAK inhibitor SU6656. RESULTS: UC-MSC transplantation significantly downregulated the expression of proinflammatory cytokines (Tnf-α, Il-1β) and fibrotic markers (Ctgf, α-Sma) while upregulating the expression of key hormone receptors (Amh, Esr1, Esr2). Additionally, a reduction in CD3(+)/CD4(+) T-cell infiltration, C3 complement deposition and IgG levels was observed, accompanied by an increase in regulatory T cells. Further analysis revealed that fibrotic markers and FAK-Tyr576/577 phosphorylation were markedly suppressed in primary ovarian GCs following MSC transplantation. In vitro experiments demonstrated that recombinant CTGF promoted fibrogenesis in the human GC line KGN. Conversely, MSC treatment inhibited phosphorylated FAK-Tyr576/577 and downregulated the expression of Collagen 1 and α-SMA, suggesting that UC-MSCs alleviate ovarian fibrosis by suppressing FAK-Tyr576/577 phosphorylation. CONCLUSION: This study demonstrated that UC-MSC treatment ameliorated ovarian dysfunction and attenuated ovarian fibrosis in lupus mice by modulating the CTGF/FAK-Tyr576/577 phosphorylation pathway.