Fig. 1

Nos2^−/− strain exhibited higher neurobehavioral score and increased inflammatory cell infiltrate in the brain compared to C3HeB/FeJ strain post-i.c.vent. infection with M.tb CDC1551. a Neurobehavioral scores were significantly higher in infected Nos2^−/− mice at 4 and 8 week p.i. compared with infected C3HeB/FeJ mice. Parameters assessed include tremors, twitches and appearance of eyes, with higher neurobehavioral scores reflecting an increasing severity of neurological deficits. Statistical analysis conducted using two-way ANOVA with post-hoc Tukey’s multiple comparisons test. ****p < 0.0001. b M.tb colony forming units (CFU) in the brain and lung of Nos2^−/− is higher compared to C3HeB/FeJ mice at day 56 p.i., analyzed using Mann–Whitney test. c Macroscopic assessment of brain, lung and spleen of M.tb infected Nos2^−/− and C3HeB/FeJ mice were similar to saline controls. Images are representative of 2–4 mice per condition. Scale bar = 1 cm. d Hematoxylin and eosin (H&E) stain of a representative brain section from each group is shown, demonstrating normal brain histology in saline control mice and histopathology in infected mice. High-power views (insets) demonstrate more inflammatory cell infiltrate in the brain of infected Nos2^−/− compared to C3HeB/FeJ mice. Scale bar = 200 µm. e and f Infected Nos2^−/− have increased concentrations of (e) ICAM-1 and (f) p-selectin in the brain compared to C3HeB/FeJ mice. Adhesion molecule concentrations were normalised to total protein concentration and compared using two-way ANOVA with Sidak’s multiple comparisons test. Bars represent median and IQR. *p < 0.05; **p < 0.01; ***p < 0.001. Inf  infected, Sal  saline. Nos2^−/− saline: n = 2; Nos2^−/− infected: n = 3; C3HeB/FeJ saline: n = 4; C3HeB/FeJ infected: n = 4