An ovine model shows that subcutaneous adipose tissue fibrosis occurs early in polycystic ovary syndrome (PCOS).

Prenatally androgenised (PA) sheep are a clinically realistic model of polycystic ovary syndrome (PCOS). They have dysfunctional subcutaneous adipose tissue (SAT) with reduced adipogenesis in adolescence and enlarged adipocytes with increased inflammation in adulthood. We hypothesised that analysis of SAT in young adults, after adipogenesis is complete but before inflammation is apparent, would give insights into the evolution of adipose tissue dysfunction. Pregnant sheep were treated intramuscularly with 100 mg testosterone propionate or vehicle control (C) twice weekly from day 62-102 of gestation. Weight-matched female offspring (PA = 10; C = 10) were studied up to 22 months of age. Glucose tolerance testing was performed, and at sacrifice SAT was fixed for histological analysis and frozen for RNA sequencing (RNAseq) and gene expression analysis. There was no difference in the average size of SAT adipocytes between PA and C young adults. There were no differences in the expression of the adipogenesis markers PPARG, CEBPA and CEBPB, or the inflammatory markers TNF and IL6, although PA sheep were already hyperinsulinaemic. RNAseq identified 792 potentially differentially expressed (P < 0.05) genes in PA sheep SAT (406 upregulated; 386 downregulated). Ingenuity Pathway Analysis highlighted upregulation of fibrotic pathways in the SAT of PA sheep. POSTN, associated with tissue fibrosis, and COL1A1, COL1A2 and COL3A1 were significantly elevated, and histochemistry showed significantly increased SAT fibrosis in PA sheep. Early fibrotic changes in SAT occur before inflammatory gene expression in PA sheep. A fibrotic barrier to healthy adipocyte expansion may have a mechanistic role in the development of inflammation in PCOS.