Transcriptome Profiling Analysis of Bovine Vaginal Epithelial Cell Response to an Isolated Lactobacillus Strain

Lactobacillus strain SQ0048 isolated from bovine vagina has been shown to exhibit specific adherence to the epithelium and to produce inhibitory substances; however, the underlying mechanisms remain unclear. We cultured and identified primary bovine vaginal epithelial cells treated with SQ0048 to investigate the pathways involved in host cell responses using transcriptome sequencing (RNA-seq). Transcription profiling showed 296 significantly altered differentially expressed genes (DEGs), of which 170 were upregulated and 126 downregulated. Gene Ontology (GO) enrichment analysis of the DEGs revealed significant enrichment of 424 GO terms throughout the differentiation process (P < 0.05). Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis showed that the DEGs were successfully annotated as members of 171 pathways, with 23 significantly enriched KEGG pathways (P < 0.05). A relatively high number of genes were enriched for the endoplasmic reticulum protein processing and interleukin-17 (IL-17) signaling pathways and for antigen processing and presentation. DEGs were verified by quantitative reverse transcription-PCR (RT-qPCR) and determination of which were most enriched for endoplasmic reticulum protein processing pathways, the activation of which might be a major factor underlying Lactobacillus adhesion to cells and pathogenic inhibition. IMPORTANCE Bovine bacterial vaginitis causes infertility, abortion, and postpartum uterine diseases, causing serious economic loss to the dairy industry. The large-scale use of antibiotics destroys normal genital tract flora and hinders the defense mechanisms of the host. Recent research suggests that lactobacilli present in the vaginal microflora of healthy cows constitute the primary microbiological barrier to infection by genital pathogens, exerting a protective role on the reproductive tract via specific adherence to the epithelium and the production of inhibitory substances. Our research identified the mechanisms for Lactobacillus adhesion and pathogenic inhibition, providing valuable information for the development of new probiotics and the discovery of novel therapeutic targets for the prevention of infections in dairy cows.