The role of Gch1 and Nos2 in the macrophage response to BCG infection. The role of Gch1 and Nos2 in the macrophage response to BCG infection

Inducible nitric oxide synthase (iNOS) plays a crucial role in controlling growth of mycobacteria, presumed to be via nitric oxide (NO) mediated killing. However, NOS enzymes can also signal through NO-independent pathways, and production of NO by NOS requires the cofactor tetrahydrobiopterin (BH4). We compared Nos2-/- mice to mice with macrophage BH4 deficiency (Gch1fl/flTie2cre), due to a leukocyte-specific deletion of Gch1, to uncover the specific contribution of NO-independent NOS functions to anti-mycobacterial immunity. We used microarrays to detail the global programme of gene expression in uninfected and BCG infected macrophages that were either deficient in iNOS (Nos2-/- vs C57bl6/J) or BH4/Gch1 (GCHfl/flTie2cre vs GCHfl/fl) Overall design: Bone Marrow Derived Macrophages (BMDM) were cultured form C57bl6/J (Nos2+/+), Nos2-/-, GCHfl/fl and GCHfl/flTie2cre bone marrow. Differentiated macrophages from 4 animals per genotype were infected with BCG (Pasteur) in the presence of interferon gamma or left uninfected for 24 hours as control samples.