ABSTRACT
Objective To investigate the lipoteichoic acid(LTA) induced apoptosis and the expression of inflammatory cytokines in human alveolar macrophage (AM) and the anti-apoptotic and anti-inflamatory effect of moxifloxacin (MXF).Methods Obtained human AM from bronchoalveolar lavage and used MTT assay to observe the effects of LTA and MXF on cell activity,optical microscope to investigate the change of the cell morphology,flow cytometry to assess cell apoptosis,RT-PCR to detect the mRNA levels of TLR2,IL-1 β,IL-8 and TNF-α,ELISA for the production of IL-8 to exam RT-PCR.Results LTA showed cytotoxicity on AM in a dose-dependent manner ( P＜0.05 ) ; MXF inhibited the effect of LTA without cytotoxicicy ( P＜0.05 ).LTA promoted apoptosis ( P＜0.05 ) and the mRNA expressions of TRL2,IL-1 β,IL-8 and TNF-α significantly in AM (P＜0.05),the peaks and peak time ofthe above factors were (3.56±0.03) at 12 h,(46.63±7.06) at 6 h,(28.07±1.24) at 12 h and (2.34 ±0.50) at 3 h respectively and increased the release of IL-8 protein level at 24 h (P＜0.05).MXF inhibited the cell apoptosis and the above mRNA expression at 12h ( P＜0.05 ),and inhibited the IL-8 protein level at 24 h( P＜0.05 ).Conclusion LTA showed cytotoxicity on AM,induced AM apoptosis and increased the expression of TLR2,IL-I β,IL-8 and TNF-α of AM ; MXF could protect AM through inhibiting of the above effects and may play a key role beside bactericidal effect in gram-positive bacteria pneumonia.
ABSTRACT
BACKGROUND: Endotoxin or lipopolysaccharide(LPS) can prime phagocytic cells such as polymorphonuclear leukocytes, monocytes or animal peritoneal macrophages to generate increased amounts of secretory products such as oxygen free radicals and tumor necrosis factor, which play an important role in developing adult respiratory distress syndrome in gram negative sepsis. Human alveolar macrophages(HAM) are continuously exposed to various stimuli inhaled into the alveoli, and the response to LPS might be different in HAM. Therefore, we investigated the effect of LPS pre-exposure on HAM adhered to plastic surface and A549 cell(type II human alveolar epithelial cell line) monolayer. METHODS: HAM were isolated from bronchoalveolar lavage fluid from normal lung of the patients with localized lung cancer and esophageal cancer. LPS was exposed to HAM for 2hrs before or after adherence to plastic surface of 24-well Linbro plate and A549 cell monolayer. And then HAM was stimulated with PMA(phorbol myristate acetate) or fMLP(N-formyl-methionyl- leucyl-phenylalanine). The amount of hydrogen peroxide(H2O2) production in the supernatant was measured on the principle of peroxidase-dependent oxidation of phenol red by hydrogen peroxide. RESULTS: LPS pre-exposure could not enhance H2O2 production in neither HAM adhered to plastic surface nor one to A549 cell monolayer. But LPS even in the absence of PMA or fMLP stimulation directly increased H2O2 release in HAM if added after the adherence to A549 cell monolayer. CONCLUSION: Endotoxin does not prime HAM, but may directly activate HAM adhered to alveolar epithelial cells. Further investagation will be necessary.