Análises funcionais in silico de genes diferencialmente expressos em resposta a infecção por Streptococcus agalactiae em úberes extracorpóreos bovinos

Abstract

Mastitis is an inflammatory response of the mammary gland characterized by an influx of somatic cells, composed mainly of neutrophils, macrophages and lymphocytes, in response to infection by pathogens. The speed and efficacy of the host immune response to pathogens affect the establishment, persistence, and severity of the infection. Among the pathogens that cause mastitis, Streptococcus agalactiae is one of the major and in cattle, the only disease associated with Streptococcus agalactiae infection is mastitis. It is known that biological pathways related to the development and occurrence of mastitis and the immune response of the host are concentrated in the mammary gland. In this sense, gene expression studies have been used to better understand their genetic basis and the development of genetic improvement strategies. In previous studies, a group of differentially expressed genes in response to Streptococcus agalactiae infection in bovine extracorporeal udders was identified using the Seq RNA technique. In the present study, we investigated which transcription factors and miRNAs are more related to differentially expressed genes in the mammary tissue, contributing to the understanding of the molecular mechanisms related to the development of mastitis. Genetic networks related to the inflammatory response were established in crossbred bovine extracorporeal udders infected with Streptococcus agalactiae. Genes (TRL2, CD14, CXCL8 and CCL5) that are part of important biological processes for the inflammatory response, such as cellular response to triacylated bacterial lipopeptide, cellular response to bacterial lipoprotein, cellular response to molecules of bacterial origin, TLR4 signaling pathways and response cell by IL1 were identified. In addition, the gene-FT network analysis allowed to highlight genes (LOC515333, SAA3, CD14, NFKBIA, APOC2 and LOC100335608) and transcription factors (STAT3, PPARG, EGR1 and NFKB1) with biological roles related to the immune response. It was also possible to highlight which genes could be regulated post-transcriptionally by miRNAs, through analysis of the gene-miRNA network, as evidenced by the relationship between the CCL5 gene and the miRNA bta-miR-363. From these functional analyzes, it was possible to identify genes and regulatory elements of the gene expression (FT and miRNA) with evident relation in the inflammatory processes of mammary glands infected by Streptococcus agalactiae and thus, possible candidate genes for mastitis resistance in cattle were presented.