Lipopolysaccharide(LPS),the principal component of the outer membrane of Gram-negative bacteria,stimulates various cell types to release numerous proinflammatory mediators such as TNF-α,IL-6 and IL-12,which may damag...Lipopolysaccharide(LPS),the principal component of the outer membrane of Gram-negative bacteria,stimulates various cell types to release numerous proinflammatory mediators such as TNF-α,IL-6 and IL-12,which may damage cells and lead to organ injury,even sepsis and septic shock.Toll-like receptor 4(TLR4) has been identified as the receptor involved in the recognition of LPS,but the role of LPS uptake in activating signal transduction remains controversial.In the present study,TNF-α was used as a marker of macrophages/ monocytes activated by LPS,and CQ was used as an inhibitor of endosome mature in order to definitude what stage of the signal transduction elicited by LPS was interrupted.We found that there indeed existed internalization of LPS and internalization partially participated in LPS signaling since CQ inhibited cytokine release,and decreased accumulation of FITC-LPS in hPBMCs.In contrast,anti-hTLR4 antibody could decrease cytokine release,but had no inhibition on accumulation of FITC-LPS.This result revealed that inhibition of cytokine release was related to reduction of FITC-LPS accumulation in the cells.But TLR4 on the cell surface couldn't participate in internalization of LPS.Thus,LPS signaling and internalization couldn't be viewed as mutually independent processes.Cellular & Molecular Immunology.2004;1(5):373-377.展开更多
基金This work was supported by a grant from the National Natural Science Foundation of China 30271512(to Zhou Hong)by a grant from National Kcy Technologies R&D Program G1999054203(to Zheng Jiang and Zhou Hong).
文摘Lipopolysaccharide(LPS),the principal component of the outer membrane of Gram-negative bacteria,stimulates various cell types to release numerous proinflammatory mediators such as TNF-α,IL-6 and IL-12,which may damage cells and lead to organ injury,even sepsis and septic shock.Toll-like receptor 4(TLR4) has been identified as the receptor involved in the recognition of LPS,but the role of LPS uptake in activating signal transduction remains controversial.In the present study,TNF-α was used as a marker of macrophages/ monocytes activated by LPS,and CQ was used as an inhibitor of endosome mature in order to definitude what stage of the signal transduction elicited by LPS was interrupted.We found that there indeed existed internalization of LPS and internalization partially participated in LPS signaling since CQ inhibited cytokine release,and decreased accumulation of FITC-LPS in hPBMCs.In contrast,anti-hTLR4 antibody could decrease cytokine release,but had no inhibition on accumulation of FITC-LPS.This result revealed that inhibition of cytokine release was related to reduction of FITC-LPS accumulation in the cells.But TLR4 on the cell surface couldn't participate in internalization of LPS.Thus,LPS signaling and internalization couldn't be viewed as mutually independent processes.Cellular & Molecular Immunology.2004;1(5):373-377.
