ABSTRACT
Objective:To investigate the effects and regulation mechanism of lipid-associated membrane proteins (LAMPs) derived from Mycoplasma pneumoniae( Mp) on the expression of quinine oxidoreductase 1 (NQO-1) in human monocyte cell line THP-1 cells, and to know the effect of NQO-1 to interleukin 8 secretion in LAMPs stimulated cells, so as to better understand the regulation mechanism upon Mp infection. Methods:Mp were cultivated and the precipitate was collected to extract LAMPs. The cytotoxicity of LAMPs to THP-1 cells was analyzed by using CCK8 test. THP-1 cells were cultured in vitro with different concentrations of LAMPs for different times, and the expression of NQO-1 protein was detected by Western blot. Nrf2 siRNA was used to investigate the role of Nrf2 in NQO-1 expression in LAMPs induced cells, and NQO-1 inhibitor Diminutol was performed to test whether they blocked interleukin 8 (IL-8) secretion when treated with LAMPs in THP-1 cells. Results:LAMPs extracted from Mp had no cytotoxicity to THP-1 cells. The expression of NQO-1 protein in LAMPs-stimulated THP-1 cells showed a dose-dependent and time-dependent manner. The production of NQO-1 protein reached peaks when treated with 5.0 μg/ml or 7.5 μg/ml of LAMPs for 12 h. Silencing of Nrf2 by siRNA significantly decreased NQO-1 production, and blocking NQO-1 by Dim increased the level of IL-8 in LAMPs-stimulated cells. Conclusions:LAMPs derived from Mp induced the expression of NQO-1 protein in THP-1 cells via Nrf2, and NQO-1 can inhibit IL-8 secretion in LAMPs stimulated monocytes.
ABSTRACT
Objective To investigate the effects of lipid-associated membrane proteins ( LAMPs) derived from Mycoplasma pneumoniae ( M.pneumoniae) strains on the expression of heme oxygenase 1 ( HO-1) in a human monocyte cell line (THP-1).Methods THP-1 cells were in vitro cultured with different concentrations of LAMPs for different times.The cytotoxicity of LAMPs to THP-1 cells was analyzed by using lactate dehydrogenase ( LDH) releasing test.The expression of HO-1 at protein and mRNA levels were de-tected by Western blot and real-time RT-PCR, respectively.The enzymatic activity of HO-1 protein was ex-amined by colorimetric assay.THP-1 cells stimulated with PBS and LPS were set up as the negative and pos-itive controls, respectively.Results A significantly enhanced LDH releasing rate was observed in THP-1 cells treated with 10 μg/ml of LAMPs.The expression of HO-1 at protein and mRNA levels in THP-1 cells were induced by LAMPs in a dose-dependent and time-dependent manner.The highest level of HO-1 protein was detected in THP-1 cells treated with 5.0 μg/ml of LAMPs.The transcriptional levels of HO-1 induced by LAMPs were significantly elevated at 3 h, peaked at 9 h and were decreased at 12 h.The expression of HO-1 protein in THP-1 cells was enhanced after 8 h of treatment with LAMPs and a significant decrease was observed at 20 h after reaching peaks at 12 h and 16 h.The activity of HO-1 protein was significantly en-hanced along with the increased expression of HO-1 protein.Conclusion The LAMPs derived from M.pneumoniae strains induced the expression of HO-1 at mRNA and protein levels.Moreover, the enzyme activity of HO-1 protein was enhanced in LAMPs treated THP-1 cells.
ABSTRACT
Objective To investigate whether nuclear transcription factor κB(NF-κB) through Toll-like receptors 2(TLR2) was activated by lipid-associated membrane proteins(LAMPs) of Mycoplasma genitalium.Methods LAMPs were extractded and THP-1 cells were stimulated.The activation of NF-κBp65 was detected by ELISA and the expression of TLR2 mRNA was detected by RT-PCR.Effects of TLR2 neutralizing antibody on LAMPs induced the activation of NF-κBp65 was analyzed by ELISA.After LAMPs stimulated 293T cells with the co-transfection pFLAG-TLR2,pNF-κB-luc,pRL-TK,the activity of NF-κB firefly luciferase and pRL-TK Renilla luciferase were detected by the dual-luciferase reporter gene,to analyzed the role of TLR2-mediated NF-κB activation by LAMPs in 293T cells.Results The activation of NF-κBp65 was mediated in LAMPs induced THP-1 cells and was significantly increased by LAMPs in a dose dependent manner.when LAMPs was 4.0 μg/ml,the activation of NF-κBp65 was the highest level.TLR2 mRNA expression was up-regulated by LAMPs in THP-1 cells.TLR2 neutralizing antibody could inhibit the activation of NF-κB by 60% in LAMPs stimulated THP-1.NF-κB fluorescence was significantly increased by co-transfection pFLAG-TLR2 in a dose-dependent manner. ConclusionMycoplasma genitalium-derived lipid-associated membrane proteins activate NF-κB via TLR2 and the activation of TLR2-mediated play an important role in pathogenic process of LAMPs.