Taurine Attenuates Streptococcus uberis-Induced Bovine Mammary Epithelial Cells Inflammation via Phosphoinositides/Ca(2+) Signaling

Taurine may alleviate the inflammatory injury induced by Streptococcus uberis (S. uberis) infection by regulating intracellular Ca(2+) levels. However, the underlying mechanisms remain unclear. Infection leads to subversion of phosphoinositides (PIs) which are closely related to Ca(2+) signaling. In order to investigate whether taurine regulates inflammation by means of PIs/ Ca(2+) systems, competitive inhibitors of taurine (β-alanine) siTauT, siPAT1, siPLC, siCaN, siPKC, and inhibitors of PLC (U73122), PKC (RO31-8220), and CaN (FK 506) were used. The results indicate that taurine transfers the extracellular nutrient signal for intercellular innate immunity to phosphoinositides without a need to enter the cytoplasm while regulating intracellular Ca(2+) levels during inflammation. Both the Ca(2+)-PKCα-NF-κB, and Ca(2+)-CaM-CaN-NFAT signaling pathways of S. uberis infection and the regulatory roles of taurine follow activation of PIs/Ca(2+) systems. These data increase our understanding on the mechanisms of multifunctional nutrient, taurine attenuated inflammatory responses caused by S. uberis infection, and provide theoretical support for the prevention of this disease.