Fig. 1

Neutrophils secrete MMP-9 and are present in CNS-TB. a M.tb infection with MOI of 1 upregulates neutrophil MMP-9 secretion. b Neutrophils from healthy volunteers secrete MMP-9 in response to CoMTB. c Kinetics of Neutrophil MMP-9 gene expression after CoMTB stimulation. d M.tb and CoMTB stimulation have an additive effect on neutrophil MMP-9 secretion. e NGAL and MMP-9 concentrations closely correlate despite being located in different neutrophil granules. f–h Neutrophils expressing MMP-9 are present in CNS TB granulomas and present in vessel walls and perivascular interstitial space. f H&E, scale bar 250 μm. g Elastase immunoperoxidase, scale bar 250 μm and h MMP-9 immunoperoxidase, ×20 magnification, scale bar 50 μm. Inset shows neutrophils within lesions (×40). Positive control on acute appendicitis with i elastase, scale bar 50 μm and j MMP-9 on blood vessel wall and interstitium, scale bar 200 μm. k Negative control with omission of primary antibodies, scale bar represents 100 μm. Bars represent mean ± s.d and represent at least two independent experiments performed in triplicate. *P < 0.05; **P < 0.01; ***P < 0.001; ****P < 0.0001