Effect of Single Nucleotide Polymorphisms of Toll-Like Receptor 4 (TLR 4) on Reproductive Performance and Immune Function in Dairy Cows.

In dairy cows, inflammatory diseases caused by infection with pathogenic bacteria post calving affect ovarian functions. This study examined the relationship between single-nucleotide polymorphisms (SNPs) of Toll-like receptor 4 (TLR4), reproductive performances [the number of artificial insemination (AI) application and days open], and immune cell functions (apoptosis and migration). Two hundred Holstein cows from the Obihiro University farm were included. The SNPs of TLR4 were genotyped by PCR-restriction fragment length polymorphism (PCR-RFLP) method. Polymorphonuclear leukocytes (PMNs) and peripheral blood mononuclear cells (PBMCs) were isolated from whole blood. The number of AI application in the animals with T/C genotype in the TLR4 exon3 was lower than that in animals with C/C genotype (1.6 ± 0.2 and 2.2 ± 0.2, respectively). Among the animals with TLR4 exon3 polymorphisms, the days open was shorter for the T/C cows than that for C/C cows (100.7 ± 6.9 days and 136.6 ± 9.0 days, respectively). The SNPs in the TLR4 intron did not affect the number of AI and days open. The apoptosis percentage of PMNs treated with lipopolysaccharide (LPS; 0.001 and 1 μg/ml) tended to be lower in the T/C genotype compared to that in the C/C genotype. The transmigration rates of PMNs, and IL-1β production in PBMCs were tended to be higher for the animals with the T/C genotype compared to those for animals with the C/C genotype. Taken together, these results suggest that TLR4 polymorphisms offer a meaningful tool to judge the reproductive potential and immune activity in individual cows.