Identification of genes associated with endometrial cell aging.

Aging of the uterine endometrium is a critical factor that affects reproductive success, but the mechanisms associated with uterine aging are unclear. In this study, we conducted a qualitative examination of age-related changes in endometrial tissues and identified candidate genes as markers for uterine aging. Gene expression patterns were assessed by twice RNA sequencing of uteri tissues from wild type (WT) C57BL/6 mice. First experimental samples were obtained from 5, 8 and 60-75 (aged) week-old WT (n=2, each). Second experimental samples were obtained from 5, 8 and 79 (aged) week-old WT (n=5, each). Gene expression data obtained by RNA-sequencing were validated by real-time PCR. Genes expressing the pro-inflammatory cytokines Il17rb and chemokines Cxcl12 and Cxcl14 showed differential expression between a group, which was composed of 5-week-old WT and 8-week-old WT (young), and aged WT mice. Protein expression levels of the above genes and IL-8, which functions downstream of IL17RB, were analyzed by quantitative immunohistochemistry of healthy human endometrium tissue samples from patients in their 20?s and 40?s (10 cases each). In these secretory phase samples, 3,3?- diaminobenzidine (DAB) staining intensity of IL17RB, CXCL12 and CXCL14 for patients in their 40?s was significantly higher than that for patients in their 20?s, as detected by a Mann Whitney U test. These results suggest that these genes are candidate markers for endometrial aging and for prediction of age-related infertility, although confirmation of these findings is needed in larger studies involving fertile and infertile women. Uterus mRNA profiles of 5 weeks, 8 weeks, 60-75 weeks and 79 weeks of age wild type (WT) mice were generated by deep sequencing, using Illumina HiSeq1500 or NovaSeq 6000.