Multi-omics reveals a relationship between endometrial amino acid metabolism and autophagy in women with recurrent miscarriage

Deterioration of the endometrial environment is an essential cause of recurrent miscarriage (RM). However, current studies in terms of endometrial amino acid metabolic characterization and autophagy are still inadequate. This study aimed to assess differences in the endometrial amino acid metabolism and autophagy between normal pregnant and RM women to reveal the association between amino acid metabolism, autophagy, and the endometrial microenvironment. We tried to (1) identify the alternation in metabolite profiles in the RM endometrium; (2) investigate the expression of autophagy-related proteins in RM; (3) elucidate the association between amino acid metabolism and autophagy in RM. Our results showed that glutamine metabolites were upregulated while glutamate metabolites were downregulated in the endometrium of RM women. The levels of autophagy-associated proteins, including LC3B, ATG12, and Beclin-1, were significantly higher in the endometrium of RM women. Hemostasis, autophagy and IFNα signaling were the top three differentially activated signaling pathways between women with RM and normal pregnancy. Interestingly, we also found that the expression of AMPK and GCN2 was significantly up-regulated in the endometrium of women with RM, and the same expression trend was also observed in the human endometrial stromal cells cultured in glutamine deprivation medium. Furthermore, inhibition of AMPK decreased the level of GCN2, indicating a positive correlation between GCN2 and AMPK. The expression of GCN2 was consistent with the expression of ATG12 and beclin-1; however, it was opposite to that of p62. Exposure to glutamine deprivation increased the level of LC3B, GCN2, ATG12 and beclin-1. Altogether, these findings suggested significant crosstalk between amino acid metabolism and autophagy. In summary, our data suggested that aberrant crosstalk between amino acid metabolism and autophagy may contribute to the impaired endometrial microenvironment of RM. Our study may provide new insight into the diagnosis of recurrent miscarriage due to endometrial factors.