Transcription Profiling of Monocyte-Derived Macrophages Infected In Vitro With Two Strains of Streptococcus agalactiae Reveals Candidate Pathways Affecting Subclinical Mastitis in Cattle

Abstract

Macrophages are key cells of innate immune response and serve as the first line of defense against bacteria. Transcription profiling of bacteria-infected macrophages could provide important insights on the pathogenicity and host defense mechanisms during infection. We have examined transcription profiles of bovine monocyte-derived macrophages (bMDMs) isolated from the blood of 12 animals and infected in vitro with two strains of Streptococcus agalactiae . Illumina sequencing of RNA from 36 bMDMs cultures exposed in vitro to either one of two sequence types of S. agalactiae (ST103 or ST12) for 6 h and unchallenged controls was performed. Analyses of over 1,656 million high-quality paired-end sequence reads revealed 5,936 and 6,443 differentially expressed genes ( p < 0.05) in bMDMs infected with ST103 and ST12, respectively, versus unchallenged controls. Moreover, 588 genes differentially expressed between bMDMs infected with ST103 versus ST12 were identified. Ingenuity pathway analysis of the differentially up-regulated genes in the bMDMs infected with ST103 revealed significant enrichment for granulocyte adhesion and diapedesis, while significant enrichment for the phagosome formation pathway was found among down-regulated genes. Moreover, Ingenuity pathway analysis of the differentially up-regulated genes in the bMDMs infected with ST12 showed significant enrichment for type 1/type 2 T helper cell activation, while the complement activation pathway was overrepresented in the down-regulated genes. Our study identified pathogen-induced regulation of key genes and pathways involved in the immune response of macrophages against infection but also likely involved in bacterial evasion of the host immune system. These results may contribute to better understanding of the mechanisms underlying subclinical infection such as bovine streptococcal mastitis.

Identification of novel molecular markers of mastitis caused by Staphylococcus aureus using gene expression profiling in two consecutive generations of Chinese Holstein dairy cattle

“…It can activate JAK2 tyrosine kinase that, in turn, activates a range of intracellular pathways. A previous study observed that the IL9 gene emerged as a central node in the network associated with Streptococcus agalactiae-induced subclinical mastitis [46]. In this regard, we have also identified IL9 as a key gene associated with S. aureus-induced subclinical mastitis.…”

Expression analysis of candidate genes for chronic subclinical mastitis in Norwegian Red cattle

“…The most frequent genes involved in several canonical pathways associated with several defined traits or unique genes were analyzed. The genes were located within converted bovine topologically associated domains (as converted from mouse and human) containing single nucleotide polymorphisms that were significantly associated with several novel defined SCM traits described previously (Kirsanova et al, 2019).…”

“…Genomic estimated breeding values (GEBV) for lactation average somatic cell scores (LSCS) are included in the routine genetic evaluation of NR and in the total merit index used for selection (Geno SA, 2018). Recent research has shown significant differentially expressed genes between groups of NR cows with high and low GEBV for LSCS, respectively (Lewandowska-Sabat et al, 2019). In the group of animals with high GEBV for LSCS, myosin IF (MYO1F) was found to be upregulated, and peptidyl arginine deiminase 4 (PADI4) was downregulated in bovine monocyte-derived macrophages stimulated with S. agalactiae strain ST103 or strain ST12, respectively.…”

“…Studies on expression profiles have been performed to identify genes associated with susceptibility to mastitis in dairy cattle (Fonseca et al, 2009;Lewandowska-Sabat et al, 2018). MicroRNA and mRNA expression profiles of bovine monocyte-derived macrophages stimulated in vitro with different strains of S. agalactiae have been analyzed on Norwegian Red (NR) cattle (Lewandowska-Sabat et al, 2018;Lewandowska-Sabat et al, 2019).…”

“…In a previous study (Kirsanova et al, 2019), we defined novel alternative chronic SCM traits for NR by analyzing genotype data from NR bulls with corresponding test day SCC records of their daughters. Moreover, genes associated with the novel defined traits were identified (Kirsanova et al, 2020).…”