Human {beta}-defensin 2 is expressed and associated with Mycobacterium tuberculosis during infection of human alveolar epithelial cells.
To determine the role of human beta-defensin 2 (HBD-2) in human tuberculosis, we studied the in vitro induction of HBD-2 gene expression by Mycobacterium tuberculosis H37Rv infection in the human lung epithelial cell line A549, in alveolar macrophages (AM), and in blood monocytes (MN) by reverse transcription-PCR. We also studied the induction of HBD-2 gene expression by mannose lipoarabinomannan (manLAM) from M. tuberculosis. Intracellular production of HBD-2 peptide was detected by immunocytochemistry and electron microscopy. Our results demonstrated that there was induction of HBD-2 mRNA in A549 cells after infection with M. tuberculosis at various multiplicities of infection (MOI) and that there was stimulation with manLAM. AM expressed the HBD-2 gene only at a high MOI with M. tuberculosis. MN did not express HBD-2 at any of the experimental M. tuberculosis MOI. Immunostaining revealed the presence of intracellular HBD-2 peptide in A549 cells following infection with M. tuberculosis, and the staining was more intense in areas where there were M. tuberculosis clusters. By using electron microscopy we also demonstrated production of HBD-2 after M. tuberculosis infection and adherence of HBD-2 to the membranes of M. tuberculosis. Alveolar epithelial cells are among the first cells to encounter M. tuberculosis following aerogenic infection. As HBD-2 has been shown to control growth of M. tuberculosis and has chemotactic activity, our results suggest that HBD-2 induction by M. tuberculosis may have a role in the pathogenesis of human tuberculosis.
Rivas-Santiago
Bruno
B
Department of Microbiology, Instituto Nacional de Enfermedades Respiratorias, Mexico City, Mexico.
Schwander
Stephan K
SK
Sarabia
Carmen
C
Diamond
Gill
G
Klein-Patel
Marcia E
ME
Hernandez-Pando
Rogelio
R
Ellner
Jerrold J
JJ
Sada
Eduardo
E
D005786:Gene Expression Regulation / Q000502:physiology; D006801:Humans; D007150:Immunohistochemistry; D016253:Microscopy, Immunoelectron; D009169:Mycobacterium tuberculosis / Q000276:immunology / Q000378:metabolism* / Q000648:ultrastructure; D011650:Pulmonary Alveoli / Q000276:immunology / Q000378:metabolism / Q000382:microbiology* / Q000648:ultrastructure; D020545:Respiratory Mucosa / Q000276:immunology / Q000378:metabolism / Q000382:microbiology / Q000648:ultrastructure; D014397:Tuberculosis, Pulmonary / Q000276:immunology / Q000378:metabolism*; D023083:beta-Defensins / Q000235:genetics* / Q000276:immunology / Q000378:metabolism
C106641:DEFB4A protein, human; D023083:beta-Defensins