Alternative activation deprives macrophages of a coordinated defense program to Mycobacterium tuberculosis.
A potent Th1 immune response is critical to the control of tuberculosis. The impact of an additive Th2 response on the course of disease has so far been insufficiently characterized, despite increased morbidity after co-infection with Mycobacterium tuberculosis and Th2-eliciting helminths and possible involvement of Th2 polarization in reactivation of latent tuberculosis. Here, we describe the gene expression profile of murine bone marrow-derived macrophages alternatively activated by IL-4 in response to infection with M. tuberculosis. Comparison of transcriptional profiles of infected IL-4- and IFN-gamma-activated macrophages revealed delayed and partially diminished responses to intracellular bacteria in alternatively activated macrophages, characterized by reduced exposure to nitrosative stress and increased iron availability, respectively. Alternative activation of host macrophages correlated with elevated expression of the M. tuberculosis iron storage protein bacterioferritin as well as reduced expression of the mycobactin synthesis genes mbtI and mbtJ. The extracellular matrix-remodeling enzyme matrix metalloproteinase (MMP)-12 was induced in alternatively activated macrophages in vitro, and MMP-12-expressing macrophages were abundant at late, but not early, stages of tuberculosis in murine lungs. Our findings emphasize that alternative activation deprives macrophages of control mechanisms that limit mycobacterial growth in vivo, thus supporting intracellular persistence of M. tuberculosis.
Max-Planck Institute for Infection Biology, Department of Immunology, Berlin, Germany. antje.kahnert@mpiib-Berlin.mpg.de
Antje
A
Kahnert
Peter
P
Seiler
Maik
M
Stein
Silke
S
Bandermann
Karin
K
Hahnke
Hans
H
Mollenkopf
Stefan H E
SH
Kaufmann
D000818:Animals; D000970:Antineoplastic Agents / Q000494:pharmacology; D001426:Bacterial Proteins / Q000276:immunology; D001854:Bone Marrow Cells / Q000276:immunology* / Q000382:microbiology / Q000473:pathology; D005786:Gene Expression Regulation / Q000187:drug effects / Q000276:immunology*; D015964:Gene Expression Regulation, Bacterial / Q000187:drug effects / Q000235:genetics / Q000276:immunology; D006373:Helminthiasis / Q000276:immunology / Q000473:pathology; D007371:Interferon-gamma / Q000494:pharmacology; D015847:Interleukin-4 / Q000494:pharmacology; D007501:Iron / Q000276:immunology; D008168:Lung / Q000276:immunology / Q000382:microbiology / Q000473:pathology; D008262:Macrophage Activation / Q000187:drug effects / Q000276:immunology*; D008264:Macrophages / Q000276:immunology* / Q000382:microbiology / Q000473:pathology; D053508:Matrix Metalloproteinase 12; D008666:Metalloendopeptidases / Q000276:immunology; D051379:Mice; D009169:Mycobacterium tuberculosis / Q000235:genetics / Q000276:immunology*; D010080:Oxazoles / Q000276:immunology; D018417:Th1 Cells / Q000276:immunology; D018418:Th2 Cells / Q000276:immunology; D014397:Tuberculosis, Pulmonary / Q000235:genetics / Q000276:immunology* / Q000473:pathology
D000970:Antineoplastic Agents; D001426:Bacterial Proteins; D010080:Oxazoles; C018608:mycobactins; D015847:Interleukin-4; D007371:Interferon-gamma; D007501:Iron; D008666:Metalloendopeptidases; D053508:Matrix Metalloproteinase 12