Uterine microbiome in postpartum dairy cows: Associations with ovarian cyclicity and endometrial transcriptome at five and nine weeks after calving

We hypothesized that the uterine microbiome postpartum would affect the endometrial transcriptome in “real-time” (implicating a direct interaction between microbial products and the endometrium and also that the microbiome could program the future function of the endometrium (implicating a uterine programming perhaps through mechanisms similar to inflammatory memory). To test this hypothesis, we performed 16S rRNA gene sequencing of the endometrial microbiome at one, five and nine weeks after calving and tested for an effect of the microbial population on the endometrial transcriptome at five and nine weeks after calving using mRNA-sequencing. As expected, the initiation of cyclicity and elevated circulating progesterone (P4) affected the endometrial transcriptome. We also report evidence for both “real-time” and long-term programming of the endometrial transcriptome by the microbiome. An unexpected result was that some of the affected genes in the endometrial microbiome on the endometrial transcriptome were identical to those affected by ovarian cyclicity. This unexpected observation may implicate an indirect mechanism through which the endometrial microbiome can act in a systemic manner to mediate endometrial function through a pathway that involves restoration of ovarian cyclicity postpartum. Overall design: To test this hypothesis, we performed 16S rRNA gene sequencing of the endometrial microbiome at one, five and nine weeks after calving and tested for an effect of the microbial population on the endometrial transcriptome at five and nine weeks after calving using mRNA-sequencing.