Notably, enzymes required for the generation of NO, (nitric oxide synthase [iNOS]) [3], CO (heme oxygenase-1 [HO-1]) [2,4,5], and H2S (cystathionine β-synthase [CBS] [6], cystathionine γ-lyase [CSE] [6], and 3-mercaptopyruvate sulfur transferase [3-MPST]) [6], are upregulated in the lungs of Mtb-infected mice and human TB patients. This evidence concerns the gene HMOX1 and tuberculosis.