The Impact of High Adiposity on Endometrial Progesterone Response and Metallothionein Regulation.

Context: Obesity is a disease with deleterious effects on the female reproductive tract, including the endometrium.

Objective: We sought to understand the effects of excess adipose on the benign endometrium.

Methods: A physiologic in vitro coculture system was developed, consisting of multicellular human endometrial organoids, adipose spheroids, and menstrual cycle hormones. Native human endometrial tissue samples from women with and without obesity were also analyzed. Benign endometrial tissues from premenopausal women ages 33 to 53 undergoing hysterectomy were obtained following written consent at Northwestern University Prentice Women's Hospital, Chicago, Illinois. Gene expression, protein expression, chromatin binding, and expression of DNA damage and oxidative damage markers were measured.

Results: Under high adiposity conditions, endometrial organoids downregulated endometrial secretory phase genes, suggestive of an altered progesterone response. Progesterone specifically upregulated the metallothionein (MT) gene family in the epithelial cells of endometrial organoids, while high adiposity significantly downregulated the MT genes. Silencing MT genes in endometrial epithelial cells resulted in increased DNA damage, illustrating the protective role of MTs. Native endometrium from women with obesity displayed increased MT expression and oxidative damage in the stroma and not in the epithelium, indicating the cell-specific impact of obesity on MT genes.

Conclusion: Taken together, the in vitro and in vivo systems used here revealed that high adiposity or obesity can alter MT expression by decreasing progesterone response in the epithelial cells and increasing oxidative stress in the stroma.