Enhanced Lipopolysaccharide Induced Monocyte Activation by Recombinant Human Soluble Cluster of Differentiation 14

Abstract

Introduction: CD14 is the first described pattern recognition receptors that detect LPS. It has two form, one is membrane-bound form and the other is soluble form. Over the past few decades, a considerable number of studies have been conducted on soluble CD14. But the exact physiological role of soluble CD14 is still controversial. In this thesis, I would like to investigate the precise physiological role of soluble CD14 on human blood monocytes activation. Methods: To investigate the physiological role of soluble CD14, Recombinant human soluble CD14 was cloning, expression, and purified. Then, pro-inflammatory cytokine IL-6 and TNF-a secretion level from human PBMC was checked by CBA assay. After that, Phosphorylation level of NF-kB was measured by western blot from THP-1 human monocytic cell line. Results: The following results were obtained. First, soluble CD14 increased pro-inflammatory cytokine IL-6 and TNF-a secretion in human PBMC at steady state (10 pg/ml) and septic state (1ng/ml) concentration of LPS. Second, soluble CD14 augmented LPS-induced phosphorylation of NF-kappa B in THP-1 cell line. Conclusions: Taken together, these results lead to the conclusion that soluble CD14 can increase LPS-induced immune responses like pro-inflammatory cytokine secretion, and phosphorylation of NF-kappa B. Therefore, it seems to be reasonable to conclude that soluble CD14 can augment LPS-induced immune responses.