FIGURE 1.

Alteration in the gut microbiota provokes susceptibility to Tuberculosis. (A) Experimental design to test the importance of gut microbiota in control of M. tuberculosis infection and TB pathology. M. tuberculosis-infected mice were treated with sterilized water only (N = 6) or with broad-spectrum antibiotics (N = 6) [ampicillin (1 mg/ml), neomycin (1 mg/ml), metronidazole (1 mg/ml) and vancomycin (0.5 mg/ml)] in their drinking water for 4 weeks until mice were sacrificed for immunological, pathological, and bacillus burden analyses. (B) M. tuberculosis CFU quantitative analyses in the lungs (per gram) and cecum (per gram) in M. tuberculosis-infected mice with or without drinking antibiotics. (C) Hematoxylin and eosin (H&E) staining of representative lungs of M. tuberculosis-infected mice with or without drinking broad-spectrum antibiotics. Yellow arrows mark extensive damages of pulmonary structures and unresolved hemorrhage, and extensive infiltration of inflammatory cells in the pulmonary compartments observed in the lung sections derived from M. tuberculosis-infected mice with drinking antibiotics. (D) The values of wet lung weight (g) for six representative lungs derived from M. tuberculosis-challenged mice with drinking antibiotics or water. (E) Quantitative representation of the lung histopathology in mice with antibiotics treatment or water treatment after infection with M. tuberculosis analyzed after hematoxylin and eosin (H&E) staining using histopathology score scale shown in Supplementary Figure 4. The histopathology score was averaged for six mice per each experimental group per time point. Data shown as mean ± SEM are representative of two independent experiments (N = 6 animals/group), *p < 0.05, **p < 0.01, non-parametric Mann–Whitney U-test.