Expression of many immunologically important genes in Mycobacterium tuberculosis-infected macrophages is independent of both TLR2 and TLR4 but dependent on IFN-alphabeta receptor and STAT1.
Macrophages respond to several subcellular products of Mycobacterium tuberculosis (Mtb) through TLR2 or TLR4. However, primary mouse macrophages respond to viable, virulent Mtb by pathways largely independent of MyD88, the common adaptor molecule for TLRs. Using microarrays, quantitative PCR, and ELISA with gene-disrupted macrophages and mice, we now show that viable Mtb elicits the expression of inducible NO synthase, RANTES, IFN-inducible protein 10, immune-responsive gene 1, and many other key genes in macrophages substantially independently of TLR2, TLR4, their combination, or the TLR adaptors Toll-IL-1R domain-containing adapter protein and Toll-IL-1R domain-containing adapter inducing IFN-beta. Mice deficient in both TLR2 and TLR4 handle aerosol infection with viable Mtb as well as congenic controls. Viable Mtb also up-regulates inducible NO synthase, RANTES, IFN-inducible protein 10, and IRG1 in macrophages that lack mannose receptor, complement receptors 3 and 4, type A scavenger receptor, or CD40. These MyD88, TLR2/4-independent transcriptional responses require IFN-alphabetaR and STAT1, but not IFN-gamma. Conversely, those genes whose expression is MyD88 dependent do not depend on IFN-alphabetaR or STAT1. Transcriptional induction of TNF is TLR2/4, MyD88, STAT1, and IFN-alphabetaR independent, but TNF protein release requires the TLR2/4-MyD88 pathway. Thus, macrophages respond transcriptionally to viable Mtb through at least three pathways. TLR2 mediates the responses of a numerically minor set of genes that collectively do not appear to affect the course of infection in mice; regulation of TNF requires TLR2/4 for post-transcriptional control, but not for transcriptional induction; and many responding genes are regulated through an unknown, TLR2/4-independent pathway that may involve IFN-alphabetaR and STAT1.
Shi
Shuangping
S
Program in Immunology and Microbial Pathogenesis, Weill Graduate School of Medical Sciences of Cornell University, New York, NY 10021, USA.
Blumenthal
Antje
A
Hickey
Christopher M
CM
Gandotra
Sheetal
S
Levy
David
D
Ehrt
Sabine
S
D048868:Adaptor Proteins, Signal Transducing; D033942:Adaptor Proteins, Vesicular Transport / Q000502:physiology; D000818:Animals; D000943:Antigens, Differentiation / Q000502:physiology; D018821:CD18 Antigens / Q000502:physiology; D019013:CD40 Antigens / Q000502:physiology; D018946:Chemokine CCL5 / Q000235:genetics; D004268:DNA-Binding Proteins / Q000502:physiology*; D008264:Macrophages / Q000276:immunology* / Q000378:metabolism; D008562:Membrane Glycoproteins / Q000502:physiology; D008565:Membrane Proteins / Q000502:physiology*; D051379:Mice; D008810:Mice, Inbred C57BL; D009169:Mycobacterium tuberculosis / Q000276:immunology*; D053594:Myeloid Differentiation Factor 88; D019001:Nitric Oxide Synthase / Q000235:genetics; D052247:Nitric Oxide Synthase Type II; D053633:Receptor, Interferon alpha-beta; D011971:Receptors, Immunologic / Q000502:physiology*; D017471:Receptors, Interferon / Q000502:physiology*; D017472:Receptors, Interleukin-1 / Q000502:physiology; D050794:STAT1 Transcription Factor; D051195:Toll-Like Receptor 2; D051197:Toll-Like Receptor 4; D015534:Trans-Activators / Q000502:physiology*; D014409:Tumor Necrosis Factor-alpha / Q000502:physiology
D048868:Adaptor Proteins, Signal Transducing; D033942:Adaptor Proteins, Vesicular Transport; D000943:Antigens, Differentiation; D018821:CD18 Antigens; D019013:CD40 Antigens; D018946:Chemokine CCL5; D004268:DNA-Binding Proteins; D008562:Membrane Glycoproteins; D008565:Membrane Proteins; D053594:Myeloid Differentiation Factor 88; D019001:Nitric Oxide Synthase; D052247:Nitric Oxide Synthase Type II; D053633:Receptor, Interferon alpha-beta; D011971:Receptors, Immunologic; D017471:Receptors, Interferon; D017472:Receptors, Interleukin-1; D050794:STAT1 Transcription Factor; D051195:Toll-Like Receptor 2; D051197:Toll-Like Receptor 4; D015534:Trans-Activators; D014409:Tumor Necrosis Factor-alpha; C507780:Myd88 protein, mouse; C494080:Stat1 protein, mouse; C476286:Ticam1 protein, mouse; C499045:TIRAP protein, mouse; C493486:Tlr2 protein, mouse; C493487:Tlr4 protein, mouse; C496317:Nos2 protein, mouse