Figure 4: NOS2 expression is required for the bacterial load reduction mediated by pharmacologic HO-1 inhibition in vivo.

(A) CFU loads in lung homogenates of C57BL/6 and NOS2^−/− Mtb-infected mice treated or not for 15 days with SnPP (N = 3 mice/group); (B) HO-1 quantification by ELISA in lung homogenates obtained from C57BL/6 and NOS2^−/− mice at 4 weeks post-infection (wpi) with Mtb (n = 4 and 3 mice/group); (C) HO-1 expression measured by flow cytometry in mCherry Mtb⁺ donor alveolar macrophages (AM), parenchymal neutrophils (Neut) or parenchymal myeloid mononuclear cells (MMC) recovered from the lungs of infected receptor mice at 4 wpi and gated as detailed in Fig. S1 (bone marrow chimeras were generated as described for Fig. 2F, but reconstituted with bone marrow from B6/SJL (CD45.1) and NOS2^−/− (CD45.2) mice) (n = 3 mice/group); (D) Representative dot plots from data depicted in Fig. 4C, showing gating of Mtb⁺ cells in left hand panels and HO-1 expression in gated cells in right hand panels flow cytometry data concatenated from 3 samples). Data expressed as mean ± standard error of mean (A and B), paired individual samples (C) or dot plots from concatenated data (D). Data shown are representative of 2 (B, C and D) or 3 (A) independent experiments. Statistical analyses: unpaired (A and B) and paired (C) Student’s t test. ** = p<0.01, **** = p<0.0001, n.s. = non-significant.