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| Regulation of Rapamycin on Nitric Oxide in the Process of Mouse(Mus musculus) RAW264.7 Cells Infected by Bacillus Calmette-Guerin (BCG) |
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Abstract Nitric oxide(NO) produced by macrophages plays a crucial role in the process of resisting and killing pathogenic microorganisms. In order to demonstrate the effect of mammalian target of rapamycin(mTOR) signaling pathway on NO in the process of host macrophages infected by Mycobacterium tuberculosis, BALB/c mouse (Mus musculus) macrophage cell line RAW264.7 was infected by Bacillus Calmette-Guérin (BCG), which were cultured in the presence of mTOR specific inhibitor rapamycin. The production of NO and the mRNA and protein expression of inducible nitric oxide synthase (iNOS) were detected by the methods of Griess, qRT-PCR and Western blot, meanwhile the lipopolysaccharide (LPS) was used as reference. The results showed that the production of NO was significantly increased in the RAW264.7 cells which were treated by BCG and LPS for 6, 12 and 24 h compared with the untreated?control?group, the expression levels of mRNA and protein of iNOS were extremely significantly increased (P＜0.01). The production of NO and the expression of iNOS were extremely significantly inhibited by 10 nmol/L rapamycin after BCG infection for 6 and 12 h (P＜0.01) compared with the control group; however, after infection for 24 h, the inhibition effect by rapamycin was not significant (P＞0.05), but the expression of iNOS was extremely significantly inhibited (P＜0.01). Moreover, after the RAW264.7 cells were treated by LPS for 6 and 24 h, 10 nmol/L rapamycin could extremely significantly inhibit the production of NO and the expression of iNOS (P＜0.01); the production of NO was significantly inhibited after the treatment for 12 h (P＜0.05). Further more, when the cells were treated by LPS for 6 h, the inhibition of rapamycin on the expression of iNOS was not significant difference (P＞0.05), but extremely significant difference after treatment for 12 and 24 h (P＜0.01). The present findings showed that rapamycin has important regulation effect on the production of NO in the process of Mycobacterium tuberculosis infection of host macrophages; these data may provide an important theoretical basis for the role of mTOR signaling pathway in the genesis and development of the tuberculosis.
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Received: 18 February 2014
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