Toll-like receptor-4 (TLR-4) expression on polymorphonuclear neutrophil leukocytes during perinatal period of dairy cow

Abstract

To establish a foundation for further researches on the improvement of polymorphonuclear neutrophil leukocytes (PMN) functions in dairy cow during perinatal period, the counting of PMN, as well as the mRNA and protein expression of toll-like receptor-4 (TLR-4) on PMN was studied during this critical period. Blood samples were taken 21, 14 and 7 days, and at calving (0) day before expected calving time, and 7, 14 and 21 days after calving. The PMN changes were measured by automatic blood cell analyzer, and mRNA and protein expression of TLR-4 were analyzed by quantity real-time PCR (RT-PCR) and western blot. The results show that the quantity of neutrophil leukocytes reached the peak (3.12 ± 0.26 × 10 9 , p<0.05) at 0 day. The mRNA expression of TLR-4 was down-regulated from the -21days before calving to the 14 day after calving (P<0.01). The protein of expression TLR-4 was lower from 7 to 14 days. The down-regulation of TLR-4 expression may be the major factor of PMN dysfunction of cows from 7 to 14 days after calving.