Effect of bilirubin on expression of toll-like receptor 4 in cord blood monocytes

Abstract:

OBJECTIVE: To study the effect of different concentrations of bilirubin on expression of toll-like receptor 4 (TLR4) in cord blood monocytes (CBMC). METHODS: Under the sterile condition, umbilical vein blood samples were obtained from normal full-term newborns, and the monocytes were in vitro separated by the method of gelatin/plasma coated flasks. The monocytes were preincubated with various concentrations (0-307.8 μmol/L) of bilirubin dissolved in bovine albumin solution for 1 hr. Bilirubin-treated CBMC were further cultured with LPS (1 μg/mL) to induce cellular activation for 24 hrs, and then the CBMC were collected. The expression of TLR4 in monocytes was measured by indirect immunofluorescence method. RESULTS: Bilirubin at the concentrations of 102.6, 153.9, 220.6 and 307.8 μmol/L inhibited the expression of TLR4 of CBMC. The inhibition effect increased with the increasing concentration of bilirubin. CONCLUSIONS: Bilirubin can inhibit the TLR4 expression of CBNC in a dose-dependent manner.