Mycobacterium avium-intracellulare complex activates nuclear transcription factor-kappaB in different cell types through reactive oxygen intermediates.
Mycobacterium avium-intracellulare complex (MAC) is one of the most common opportunistic pathogens in HIV-infected patients. Their synergistic interaction leads to a rapid deterioration of the host defense. In vivo, MAC manifests as a disseminated granulomatous disease that produces a massive inflammatory tissue response perhaps through its activation of inflammatory cytokines. The intracellular signaling following interaction of the mycobacterium with host cells is incompletely understood. Because the response is dependent, in part, on the activation of NF-kappaB, we investigated the effect of MAC on this nuclear transcription factor in cells of macrophage and nonmacrophage lineage. We demonstrate that both high and low virulence strains of MAC potently and rapidly activated NF-kappaB. In supershift assays, using specific Abs against the NF-kappaB subunits, we identified a p50/p65 heterodimer that was formed within 5 min after incubation with the bacterium too rapidly for cytokines to be involved in the activation. This activation was instead mediated through the generation of reactive oxygen intermediates, inasmuch as preincubation of cells with a variety of antioxidants inhibited NF-kappaB activation. Likewise, the transfection of cells with Mn-superoxide dismutase blocked the NF-kappaB activation induced by the bacterium. These data suggest that NF-kappaB activation is a consequence of interaction of host cells with the bacterium and that the interaction may play a pivotal role in the pathogenesis of the disease.
Giri
D K
DK
Department of Molecular Oncology, University of Texas M. D. Anderson Cancer Center, Houston 77030, USA.
Mehta
R T
RT
Kansal
R G
RG
Aggarwal
B B
BB
D000975:Antioxidants / Q000494:pharmacology; D001943:Breast Neoplasms / Q000473:pathology; D002478:Cells, Cultured; D005260:Female; D005347:Fibroblasts / Q000187:drug effects; D005786:Gene Expression Regulation / Q000187:drug effects; D006801:Humans; D019169:Jurkat Cells / Q000187:drug effects; D015479:Leukemia, Myelomonocytic, Acute / Q000473:pathology; D008070:Lipopolysaccharides / Q000037:antagonists & inhibitors / Q000494:pharmacology; D008264:Macrophages / Q000187:drug effects; D008297:Male; D015269:Mycobacterium avium Complex / Q000472:pathogenicity / Q000502:physiology*; D016328:NF-kappa B / Q000737:chemistry / Q000378:metabolism*; D018384:Oxidative Stress; D011112:Polymyxin B / Q000494:pharmacology; D011518:Proto-Oncogene Proteins / Q000032:analysis / Q000502:physiology; D020569:Proto-Oncogene Proteins c-rel; D017382:Reactive Oxygen Species / Q000378:metabolism*; D015398:Signal Transduction / Q000502:physiology; D013482:Superoxide Dismutase / Q000235:genetics / Q000502:physiology; D051841:Transcription Factor RelB; D014157:Transcription Factors / Q000502:physiology; D014162:Transfection; D014407:Tumor Cells, Cultured; D014409:Tumor Necrosis Factor-alpha / Q000378:metabolism; D020298:U937 Cells / Q000187:drug effects; D014774:Virulence
D000975:Antioxidants; D008070:Lipopolysaccharides; D016328:NF-kappa B; D011518:Proto-Oncogene Proteins; D020569:Proto-Oncogene Proteins c-rel; C497593:RELB protein, human; D017382:Reactive Oxygen Species; D014157:Transcription Factors; D014409:Tumor Necrosis Factor-alpha; D051841:Transcription Factor RelB; D013482:Superoxide Dismutase; D011112:Polymyxin B