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

ABSTRACT: 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.

ORGANISM(S): Bos taurus

PROVIDER: GSE108163 | GEO | 2018/07/01

REPOSITORIES: GEO

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Project description:Background: Physiological inflammation of the uterus postpartum is essential for the reparative processes of involution after calving. In the majority of cows, this inflammation is resolved and homeostasis is restored. However, in a significant subset, inflammation persists and contributes to tissue damage, pathology and subfertility. Transcriptomic differences of immune genes between cattle that resolve inflammation and those that develop uterine disease have been detected as early as 7 days postpartum (DPP) suggesting that the host immune response plays an important role in disease outcome. Results: Here, we extensively characterise the immune response at the transcriptomic level in endometrial epithelial cells from post-partum dairy cows phenotyped for both clinical and sub-clinical forms of uterine disease. We address the hypothesis that excessive expression of endometrial inflammatory molecules contributes to development of endometritis. Classification of cattle (n=112) as healthy or with uterine disease (purulent vaginal discharge; PVD and cytological endometritis; CYTO) was based on vaginal mucus score and >18% polymorphonuclear cell infiltrate into the endometrium at 21 DPP. RNA-seq analysis of endometrial epithelial cells collected using cytobrushes identified differential expression of 294 genes (FDR <0.05) between cows that subsequently resolved inflammation (n=10) and those that developed disease (n=20). Pathway over-representation analysis of differentially expressed genes (DEG) identified significant changes in immune-related pathways, including the NOD-like receptor signalling pathway, cytokine-cytokine receptor interaction pathway and the Toll-like receptor signalling pathway which were up-regulated in cattle that subsequently developed disease. The majority of the DEG were upregulated in cows that developed PVD, and included all genes upregulated in CYTO cows, suggesting a core inflammatory gene signature early post-partum contributes to the onset of uterine disease. This inflammatory signature was validated by qPCR in an independent group of cows (n=56) and included upregulation of pro-inflammatory genes (including TLR2, TLR4, NLRP3, IL1A, IL1B, IL8, and S100A8) at day 7 postpartum in cows that failed to resolve inflammation. Conclusions: Despite a large amount of inter-animal heterogeneity, these results suggest that excessive activation and inappropriate regulation of the inflammatory response early postpartum is a key feature of the subsequent development of uterine disease. Keywords: Endometritis, Inflammation, Transcriptome, Next generation sequencing, Dairy cattle, Uterine involution, Immune response

Project description:Purpouse: Aims of this study were (1) to characterize the endometrial transcriptome, (2) to identify functional pathways, and (3) to molecularly characterize selected pathways overrepresented in the endometrium of day 7 post-ovulation induction of cows treated to ovulate larger versus smaller follicles Methods: Seventy-four multiparous, nonlactating, presynchronized Nelore cows received a progesterone-releasing device and estradiol benzoate on Day–10 (D?10). Animals received cloprostenol (large follicle-large CL group; LF-LCL; N = 35) or not (small follicle-small CL group; SF-SCL; N = 39) on D?10. Progesterone devices were withdrawn and cloprostenol administered 42 to 54 hours (LF-LCL) or 30 to 36 hours (SF-SCL) before GnRH treatment (D0). Tissues were collected at slaughter on D7. Transcriptional profiling of the endometrial tissue was performed by RNA-seq and protein markers for proliferation and apoptosis were identified by immunohistochemistry. Results: Functional enrichment data indicated that LF-LCL endometrium expressed greater abundance of genes associated with biosynthetic and metabolic processes, whereas SF-SCL endometrium .gene expression profile was biased towards cell proliferation. Extracellular matrix-related genes were also upregulated in the SF-SCL endometrium suggesting reorganization of the ECM towards a proliferation permissive phenotype. Immunohistochemistry data confirmed the greater proliferative activity observed in SF-SCL endometrium I comparison to LF-LCL counterparts, and indicated a time-related transition within experimental group. In conclusion, the periovulatory endocrine milieu regulates bovine endometrial gene expression. Furthermore, timing and amplitude of ovarian steroid secretion pattern seem to determine the transition from a proliferation permissive to a biosynthetic and metabolically active endometrial phenotype, which may be associated with the preparation of an optimally receptive uterine environment. Conclusion: the periovulatory endocrine milieu affected D7 endometrial molecular signature. Main pathways affected were related to cell proliferation, ECM composition and remodeling, biosynthetic and metabolic processes. Reported data further suggest that the endometrial tissue from LF-LCL cows experienced an early proliferative phase (D4), whereas the SF-SCL endometrium, exposed to a distinct periovulatory endocrine environment, expressed a delayed onset of the proliferative activity (D7). endometrial mRNA profiles of endocrine manipulated cows were generated by deep sequencing using Illumina HiScanSQ platform

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

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