title: Chlamydial lung infection induces transient IL-9 production which is redundant for host defense against primary infection.
abstract: IL-9/Th9 responses are recently found to be important for innate and adaptive immunity particularly in parasitic infections. To date, the study on the role of IL-9 in bacterial infections is limited and the reported data are contradictory. One reported function of IL-9/Th9 is to modulate Th1/Th17 responses. Since our and others' previous work has shown a critical role of Th1 and Th17 cells in host defense against chlamydial lung infection, we here examined the role of IL-9 responses in Chlamydia muridarum (Cm) lung infection, particularly its effect on Th1 and Th17 responses and outcome infection. Our data showed quick but transient IL-9 production in the lung following infection, peaking at day 3 and back to baseline around day 7. CD4+ T cell was the major source of IL-9 production in the lung infection. Blockade of endogenous IL-9 using neutralizing antibody failed to change Interferon-γ (IFN-γ) and IL-17 production by cultured spleen mononuclear cells isolated from Cm infected mice. Similarly, in vivo neutralization of IL-9 failed to show significant effect on T cell (Th1 and Th17) and antibody responses (IgA, IgG1 and IgG2a). Consistently, the neutralization of IL-9 had no significant effect on disease process, including body weight change, bacterial burden and histopathological score. The data suggest that IL-9 production following chlamydial lung infection is redundant for host defense against the intracellular bacteria.
authors: Departments of Immunology and Medical Microbiology, University of Manitoba, Winnipeg, Manitoba, Canada.
authors: Ying
authors: Y
authors: Peng
authors: Departments of Immunology and Medical Microbiology, University of Manitoba, Winnipeg, Manitoba, Canada.
authors: Xiaoling
authors: X
authors: Gao
authors: Departments of Immunology and Medical Microbiology, University of Manitoba, Winnipeg, Manitoba, Canada.
authors: Jie
authors: J
authors: Yang
authors: Departments of Immunology and Medical Microbiology, University of Manitoba, Winnipeg, Manitoba, Canada.
authors: Sudhanshu
authors: S
authors: Shekhar
authors: Departments of Immunology and Medical Microbiology, University of Manitoba, Winnipeg, Manitoba, Canada.
authors: Shuhe
authors: S
authors: Wang
authors: Departments of Immunology and Medical Microbiology, University of Manitoba, Winnipeg, Manitoba, Canada.
authors: Yijun
authors: Y
authors: Fan
authors: Departments of Immunology and Medical Microbiology, University of Manitoba, Winnipeg, Manitoba, Canada.
authors: Xi
authors: X
authors: Yang
mesh_terms: D000818:Animals; D002690:Chlamydia Infections / Q000276:immunology* / Q000378:metabolism*; D016906:Interleukin-9 / Q000096:biosynthesis*; D042541:Intracellular Space / Q000382:microbiology; D008168:Lung / Q000276:immunology / Q000382:microbiology / Q000473:pathology; D008171:Lung Diseases / Q000276:immunology* / Q000378:metabolism*; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL
chemical_list: D016906:Interleukin-9
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