TY - JOUR T1 - Liver X receptors contribute to the protective immune response against Mycobacterium tuberculosis in mice. JF - J Clin Invest Y1 - 2009 A1 - Korf, Hannelie A1 - Vander Beken, Seppe A1 - Marta Romano A1 - Steffensen, Knut R A1 - Stijlemans, BenoƮt A1 - Gustafsson, Jan-Ake A1 - Grooten, Johan A1 - Huygen, Kris KW - Animals KW - Disease Models, Animal KW - DNA-Binding Proteins KW - Immunity, Innate KW - Kinetics KW - Liver X Receptors KW - mice KW - Mice, Inbred C57BL KW - Mice, Knockout KW - Mycobacterium tuberculosis KW - Orphan Nuclear Receptors KW - Receptors, Cytoplasmic and Nuclear KW - Tuberculosis, Pulmonary AB -

Liver X receptors (LXRs) are key regulators of macrophage function, controlling transcriptional programs involved in lipid homeostasis and inflammation. However, exactly how LXRs modulate inflammation during infection remains unknown. To explore this, we used a mouse model of Mycobacterium tuberculosis infection. Upon intratracheal infection with M. tuberculosis, LXRs and LXR target genes were induced in CD11c+ lung and alveolar cells. Furthermore, mice deficient in both LXR isoforms, LXRalpha and LXRbeta (Lxra-/-Lxrb-/- mice), were more susceptible to infection, developing higher bacterial burdens and an increase in the size and number of granulomatous lesions. Interestingly, mice solely deficient in LXRalpha, but not those lacking only LXRbeta, mirrored the susceptibility of the Lxra-/-Lxrb-/- animals. Lxra-/-Lxrb-/- mice failed to mount an effective early neutrophilic airway response to infection and showed dysregulation of both pro- and antiinflammatory factors in CD11c+ lung cells. T cell responses were strongly affected in Lxra-/-Lxrb-/- mice, showing near-complete abrogation of the infection-induced Th1 function - and even more so Th17 function - in the lungs. Treatment of WT mice with the LXR agonists TO901317 and GW3965 resulted in a 10-fold decrease of the pulmonary bacterial burden and a comparable increase of Th1/Th17 function in the lungs. The dependence of LXR signaling on the neutrophil IL-17 axis represents what we believe to be a novel function for these nuclear receptors in resistance to M. tuberculosis infection and may provide a new target for therapeutics.

VL - 119 CP - 6 U1 - http://www.ncbi.nlm.nih.gov/pubmed/19436111?dopt=Abstract M3 - 10.1172/JCI35288 ER -