RESUMO
Mycobacterium tuberculosis (Mtb), the etiological agent of tuberculosis, kills 1.5 to 1.7 million people every year. Macrophages are Mtb's main host cells and their inflammatory response is an essential component of the host defense against Mtb. However, Mtb is able to circumvent the macrophages' defenses by triggering an inappropriate inflammatory response. The ability of Mtb to hinder phagolysosome maturation and acidification, and to escape the phagosome into the cytosol, is closely linked to its virulence. The modulation of the host inflammatory response relies on Mtb virulence factors, but remains poorly studied. Understanding macrophage interactions with Mtb is crucial to develop strategies to control tuberculosis. The present study aims to determine the inflammatory response transcriptome and miRNome of human macrophages infected with the virulent H37Rv Mtb strain, to identify macrophage genetic networks specifically modulated by Mtb virulence. Using human macrophages infected with two different live strains of mycobacteria (live or heat-inactivated Mtb H37Rv and M. marinum), we quantified and analyzed 184 inflammatory mRNAs and 765 micro(mi)RNAs. Transcripts and miRNAs differently modulated by H37Rv in comparison with the two other conditions were analyzed using in silico approaches. We identified 30 host inflammatory response genes and 37 miRNAs specific for H37Rv virulence, and highlight evidence suggesting that Mtb intracellular-linked virulence depends on the inhibition of IL-1ß-dependent pro-inflammatory response, the repression of apoptosis and the delay of the recruitment and activation of adaptive immune cells. Our findings provide new potential targets for the development of macrophage-based therapeutic strategies against TB.
Assuntos
Citocinas/metabolismo , Mediadores da Inflamação/metabolismo , Pulmão/microbiologia , Macrófagos/microbiologia , Mycobacterium tuberculosis/patogenicidade , Tuberculose/microbiologia , Imunidade Adaptativa , Apoptose , Citocinas/genética , Regulação da Expressão Gênica , Interações Hospedeiro-Patógeno , Humanos , Pulmão/imunologia , Pulmão/metabolismo , Macrófagos/imunologia , Macrófagos/metabolismo , MicroRNAs/genética , MicroRNAs/metabolismo , Infecções por Mycobacterium não Tuberculosas/imunologia , Infecções por Mycobacterium não Tuberculosas/metabolismo , Infecções por Mycobacterium não Tuberculosas/microbiologia , Mycobacterium marinum/imunologia , Mycobacterium marinum/patogenicidade , Mycobacterium tuberculosis/imunologia , Transdução de Sinais , Células THP-1 , Transcriptoma , Tuberculose/genética , Tuberculose/imunologia , Tuberculose/metabolismo , VirulênciaRESUMO
The historical view of ß-lactams as ineffective antimycobacterials has given way to growing interest in the activity of this class against Mycobacterium tuberculosis (Mtb) in the presence of a ß-lactamase inhibitor. However, most antimycobacterial ß-lactams kill Mtb only or best when the bacilli are replicating. Here, a screen of 1904 ß-lactams led to the identification of cephalosporins substituted with a pyrithione moiety at C3' that are active against Mtb under both replicating and nonreplicating conditions, neither activity requiring a ß-lactamase inhibitor. Studies showed that activity against nonreplicating Mtb required the in situ release of the pyrithione, independent of the known class A ß-lactamase, BlaC. In contrast, replicating Mtb could be killed both by released pyrithione and by the parent ß-lactam. Thus, the antimycobacterial activity of pyrithione-containing cephalosporins arises from two mechanisms that kill mycobacteria in different metabolic states.