IL4 and susceptibility to pneumonia measurement: Infected animals with the H37Rv strain and treated with the HO-1 inhibitor ZnPp administered during the second and third week of the infection, and euthanizing mice after 60 days of infection showed lower bacillary loads and pneumonia, as well as higher expression of IFN-γ and lower transcription of IL-4 and TGF-β, but only the transcription of TGF-β was significant (Supplementary Figure S5A).