Transcriptome analysis of miRNA and mRNA in porcine skeletal muscle following Glaesserella parasuis challenge

Glaesserella parasuis (G. parasuis) causes systemic infection in pigs, but its effects on skeletal muscle and underlying mechanisms are poorly understood. We investigated G. parasuis infection in colostrum-deprived piglets, observing decreased weight gain and upregulation of inflammatory factors in skeletal muscle. Muscle fiber area and diameter were significantly reduced in the treated group, accompanied by increased expression of FOXO1, FBXO32, TRIM63, CTSL and BNIP3. Through mRNA and microRNA (miRNA) sequencing, we identified 1,642 differentially expressed (DE) mRNAs and 19 DE known miRNAs in skeletal muscle tissues between the treated and control groups. We predicted target genes with opposite expression patterns to the 19 miRNAs and found significant enrichment and activation of the FoxO signaling pathway. Upregulated core effectors FOXO1 and FOXO4 were targeted by downregulated ssc-miR-486, ssc-miR-370, ssc-miR-615 and ssc-miR-224. And their downstream genes involved in protein degradation were also targeted by four downregulated miRNAs (ssc-miR-370, ssc-miR-615, ssc-miR-194a-5p and ssc-miR-194b-5p) and showed significantly increased expression. These findings suggest that G. parasuis infection causes skeletal muscle atrophy in piglets through accelerated protein degradation mediated by the "miRNAs-FOXO1/4" axis. This study enhances our understanding of systemic inflammation mechanisms caused by G. parasuis and the role of miRNAs in bacterial infection pathogenesis.