Greenberg S S, Xie J, Kolls J, Mason C, Didier P
Department of Medicine, Louisiana State University Medical Center, New Orleans 70112, USA.
Proc Soc Exp Biol Med. 1995 May;209(1):46-53. doi: 10.3181/00379727-209-43876.
Mycobacterium avium complex (MAC) organisms are among the most common bacterial cause of disseminated infection in patients with acquired immune deficiency syndrome (AIDS). An increase in the incidence of virulent Mycobacterium tuberculosis (MTB) is also occurring throughout the world. In vitro data suggest that nitric oxide (NO) may be important in restricting the growth of MAC. However, the ability of MTB to stimulate NO production and the susceptibility of MTB to the bactericidal activity of NO produced by murine alveolar macrophages (AM) is controversial. This study tested the hypothesis that in vivo administration of heat-killed MAC (strain 100 and 101) and human virulent MTB (strain F1) to rats stimulated NO production by rat AM, ex vivo. We show that heat-killed MTB instilled into rat lungs rapidly induced mRNA for NO synthase (iNOS) II in AM obtained by bronchoalveolar lavage (BAL). In contrast, expression of AM iNOS mRNA was only found in 40% of the rats given MAC. Moreover, the change in iNOS mRNA in the AM obtained from rats given MTB and MAC correlated with the production of the reactive nitrogen intermediates (RNI) NO2- and NO3- in BAL fluid, lung homogenate, and the spontaneous generation of RNI by isolated AM ex vivo and occurred without measurable increases in BAL fluid tumor necrosis factor-alpha (TNF-alpha). L-NG-monomethylarginine (50 mg/kg, ip) given 30 min before MAC or MTB attenuated the increase in RNI in lung homogenates and BAL fluid. This is the first demonstration that in vivo exposure to MTB results in rapid upregulation of gene expression for iNOS which is associated with functional RNI production by rat AM. These results show that MTB human virulent strain 1 has the ability to rapidly upregulate iNOS mRNA in AM. If human AM generate NO from L-arginine by either iNOS or other NADPH oxidases then NO may play a role in the overall host-defense response of the lung to MAC and MTB.
鸟分枝杆菌复合体（MAC）是获得性免疫缺陷综合征（AIDS）患者播散性感染最常见的细菌病因之一。世界各地毒力强的结核分枝杆菌（MTB）发病率也在上升。体外数据表明，一氧化氮（NO）可能在限制MAC生长方面起重要作用。然而，MTB刺激NO产生的能力以及MTB对小鼠肺泡巨噬细胞（AM）产生的NO杀菌活性的敏感性存在争议。本研究检验了以下假设：给大鼠体内注射热灭活的MAC（菌株100和101）和人源毒力MTB（菌株F1）可在体外刺激大鼠AM产生NO。我们发现，将热灭活的MTB注入大鼠肺部后，通过支气管肺泡灌洗（BAL）获得的AM中，NO合酶（iNOS）II的mRNA迅速诱导表达。相比之下，仅40%给予MAC的大鼠中发现AM的iNOS mRNA表达。此外，从给予MTB和MAC的大鼠获得的AM中，iNOS mRNA的变化与BAL液、肺匀浆中活性氮中间体（RNI）NO2-和NO3-的产生以及离体分离的AM自发产生RNI相关，且BAL液中肿瘤坏死因子-α（TNF-α）无明显增加。在给予MAC或MTB前30分钟腹腔注射L-NG-单甲基精氨酸（50 mg/kg）可减弱肺匀浆和BAL液中RNI的增加。这首次证明体内暴露于MTB会导致iNOS基因表达迅速上调，这与大鼠AM产生功能性RNI有关。这些结果表明，人源毒力MTB菌株1有能力迅速上调AM中的iNOS mRNA。如果人AM通过iNOS或其他NADPH氧化酶从L-精氨酸产生NO，那么NO可能在肺部对MAC和MTB的整体宿主防御反应中发挥作用。
