Identification of key genes in immune-response post-endurance run in horses.

Intense physical activity in endurance horses triggers complex immune and inflammatory responses, yet the molecular mechanisms underlying these adaptations remain unclear. This study investigated immune-related transcriptomic changes following a 160 km endurance ride, focusing on sex-based differences. Using a bioinformatics approach, differentially expressed genes (DEGs), pathways, microRNAs (miRNAs), and transcription factors (TFs) were analyzed before (T0) and after (T1) the ride. A protein-protein interaction (PPI) analysis was conducted to identify key regulatory genes. Pathway enrichment analysis revealed significant activation of immune-regulatory and ribosomal pathways. Notably, TLR4, CXCL8, and CCL5 were identified as key hub genes involved in immune modulation post-exercise. Comparisons between female (FT1 vs FT0) and gelding (GT1 vs GT0) horses revealed distinct molecular responses. Female horses exhibited upregulation of ribosomal protein genes, suggesting enhanced protein synthesis and muscle recovery. In contrast, geldings showed increased expression of inflammatory and stress-related genes, indicating a heightened immune response. Notably, sex-based differences were observed, with FT1 vs FT0 and GT1 vs GT0 comparisons revealing distinct KEGG pathway enrichments. Additionally, miRNA and TF analyses revealed regulatory elements influencing endurance-related immune responses. Our findings demonstrated sex-specific molecular mechanisms underlying endurance exercise adaptation, with females prioritizing protein synthesis and recovery, while geldings exhibit stronger inflammatory responses and stress-related pathways. This study provides critical insights into how sex influences exercise physiology at the transcriptomic level, with potential applications in training and recovery strategies for endurance horses.