Role Of TREM-1 Gene In Immunity Against Inflammatory Diseases

Inflammation is the major cause producing sepsis resulting in multiorgan dysfunction, indicting multiorgan injury leading to the death. Triggering receptor expressed on myeloid cells (TREM-1) gene is very important mediator in inflammation as it acts as its amplifier. It encodes a receptor belongs to the Ig superfamily that is expressed on myeloid cells. Furthermore it’sprotein amplifies neutrophil and monocyte-mediated inflammatory responses triggered by bacterial and fungal infections hence stimulating release of pro-inflammatory chemokines and cytokines, as well as increased surface expression of cell activation markers.The objective of our study was to elucidate the role of TREM-1 gene in immunity against inflammatory diseases, and find important single nucleotide polymorphisms (SNPs) in dairy cow and associate its role with disease and validate our findings experimentally.We utilize the previous GWAS data from our laboratory and reanalyzed for our directed aim. The results indicate change in position of SNPs and were associated to important traits including immunity and milk yield. We further performed gene annotation studies which reveal its involvement in biological processes, molecular function including binding and catalysis as well as cellular component.The nsSNPs were retrieved from Ensembl Data base for Bos taurus TREM-1 gene. The potential effects of these nsSNPs were calculated using the degree of evolutionary conservation for all the amino acid sites in the TREM-1 protein using the ConSurf web server, which is webserver that employs an empirical Bayesian method to evaluate the evolutionary conservation that identify putative structural and functional residues. The analysis was focused on amino acid sites that coincide in location with the nsSNPs; however, ConSurf also identified several other residues that might be functionally relevant. Furthermore functional characterization with the post translational modifications affected by these nsSNPs was also carried out.In bovine, mastitis is an example of inflammatory diseases in which mammary gland inflams that is generally caused by bacteria. TREM-1 is recognized as key player in the innate immune system play a significant role in the recognition of infectious agents, particularly, bacteria. The hypothesis was that the single nucleotide polymorphism variation in TREM-1 gene may affect individual susceptibility to mastitis. The genotype distribution of alleles for TREM-1 (rs 109937179 and rs208224995) gene polymorphisms was investigated in 364 and 320 Chinese Holstein cows respectively. We found that GG genotype of the rs 109937179 polymorphism and rs208224995 genotype CA within TREM-1 gene is associated with an increased risk of mastitis. Furthermore rs109937179 is predicted in the splicing region of TREM-1 and rs208224995 is having miRNA binding region for bta-miR-2329-3p in 3’UTR might plays critical roles in gene expression regulation.LPS mediates the proinflammatory cytokines that are initiated by TLR4 and TREM-1 is considered as a potent amplifier in TLR mediated inflammatory diseases. The inhibition of TREM-1 is reported to have an association with increased survival rates. We aim to determine the effect of resveratrol on the expression of TREM-1 in RAW 264.7 cells. The results demonstrate that LPS markedly increased the expression of TREM-1 in RAW 264.7 cells. When the cells were transfected with siRNA anti-TREM-1, it responds to have lower expression of TREM-1 and the cells treated with resveratrol further decreased expression of TREM-1. This demonstrated that resveratrol can help reduce expression of TREM-1.Furthermore, the relative gene expression of TLR4, the proinflammatory cytokines IL-6 and TNFa and anti-inflammatory cytokine IL-10 is also determined. The marked increase in LPS treated cells for TLR4 was observed which was significantly lower in siRNA anti-TREM-1 transfected cells and resveratrol treated cells. This observation shows that TREM-1 plays a role in amplifying the effect of TLR4 and further increases the production of proinflammatory cytokines.