Upregulated-gene expression of pro-inflammatory cytokines (TNF-α, IL-1β and IL-6) via TLRs following NF-κB and MAPKs in bovine mastitis

Abstract

Mastitis is the inflammation of mammary glands which causes huge economic loss in dairy cows. Inflammation, any tissue injury and pathogens in cow udder activate Toll-like Receptors (TLRs). Staphylococcus aureus (S. aureus) is the major cause of mastitis. In mastitis, activated TLRs initiate the NF-κB/MAPKs pathways which further trigger the gene expression associated with mastitis followed by innate immune response. In this study, pathogenic-induced gene expression profile of pro-inflammatory cytokines in mammary gland tissues, was investigated in mastitis. The Hematoxylin and Eosin (H & E) results indicated severe histopathological changes in infected tissues. Western blot results suggested the over expressions of TLR2/TLR4 with NF-κB/MAPKs pathways activation in infected tissues. qRT-PCR results revealed the gene expression associated with TLR2/TLR4-mediated NF-κB/MAPKs pathways in infected tissues in comparison with non-infected. Statistical analysis of mRNA and relative protein expression levels indicated the up-regulation of pro-inflammatory cytokines (TNF-α, IL-1β and IL-6) in infected tissues rather than non-infected tissues. These results suggested that the up-regulation of gene expression levels implicated the underlying regulatory pathways for proper immune function in mammary glands. In conclusion, our study might give new insights for investigation and better understanding of mammary gland pathophysiology and TLRs and NF-κB/MAPKs-mediated gene expression of pro-inflammatory cytokines.

Keywords: Cytokines; MAPKs; Mastitis; NF-κB; S. aureus; TLRs.