Integrative Analysis of Differentially Expressed miRNAs and Noncoding RNA Networks Reveals Molecular Mechanisms Underlying Metritis in Postpartum Dairy Cows.

Postpartum metritis in dairy cows compromises reproductive performance and leads to substantial economic losses. This study investigated the molecular mechanisms underlying metritis by integrating high-throughput circulating microRNA (miRNA) profiling with systems-level bioinformatics. Previously, 30 differentially expressed miRNAs, 16 upregulated and 14 downregulated, were identified in metritis-affected cows compared to healthy controls. Building on these findings, this study predicted miRNA target genes and constructed regulatory networks involving miRNAs, mRNAs, circRNAs, lncRNAs, and snRNAs, alongside protein-protein interaction networks. Functional annotation and KEGG pathway analysis revealed that upregulated miRNAs influenced genes involved in immune activation, apoptosis, and metabolism, while downregulated miRNAs were associated with angiogenesis, immune suppression, and tissue repair. Hub genes such as AKT3, VEGFA, and HIF1A were central to immune and angiogenic signaling, whereas UBE3A and ZEB1 were linked to immune inhibition. Interferon-stimulated genes (e.g., ISG15, RSAD2, CXCL chemokines) were shown to regulate solute carriers, contributing to immune dysregulation. Key pathways included PI3K-Akt, NF-κB, JAK-STAT, insulin resistance, and T cell receptor signaling. Noncoding RNAs such as NEAT1, KCNQ1OT1, and XIST, along with miRNAs like bta-miR-15b and bta-miR-148a, emerged as pro-inflammatory regulators, while bta-miR-199a-3p appeared to exert immunosuppressive effects. These findings offer new insights into the complex regulatory networks driving metritis and suggest potential targets for improving fertility in dairy cows.