In an in vitro model of human tuberculosis,monocyte-microglial networks regulate matrix metalloproteinase-1 and -3 gene expression and secretion via a p38 mitogen activated protein kinase-dependent pathway

Background: tuberculosis (tb) of the central nervous system (cns) is characterized by extensive tissue inflammation,driven by molecules that cleave extracellular matrix such as matrix metalloproteinase (mmp)-1 and mmp-3. however,relatively little is known about the regulation of these mmps in the cns.methods: using a cellular model of cns tb,we stimulated a human microglial cell line (chme3) with conditioned medium from mycobacterium tuberculosis-infected primary human monocytes (comtb). mmp-1 and mmp-3 secretion was detected using elisas confirmed with casein zymography or western blotting. key results of a phospho-array profile that detects a wide range of kinase activity were confirmed with phospho-western blotting. chemical inhibition (sb203580) of microglial cells allowed investigation of expression and secretion of mmp-1 and mmp-3. finally we used promoter reporter assays employing full length and mmp-3 promoter deletion constructs. student's t-test was used for comparison of continuous variables and multiple intervention experiments were compared by one-way anova with tukey's correction for multiple pairwise comparisons.results: comtb up-regulated microglial mmp-1 and mmp-3 secretion in a dose- and time-dependent manner. the phospho-array profiling showed that the major increase in kinase activity due to comtb stimulation was in p38 mitogen activated protein kinase (mapk),principally the α and γ subunits. p38 phosphorylation was detected at 15 minutes,with a second peak of activity at 120 minutes. high basal extracellular signal-regulated kinase activity was further increased by comtb. secretion and expression of mmp-1 and mmp-3 were both p38 dependent. comtb stimulation of full length and mmp-3 promoter deletion constructs demonstrated up-regulation of activity in the wild type but a suppression site between -2183 and -1612 bp.conclusions: monocyte-microglial network-dependent mmp-1 and mmp-3 gene expression and secretion are dependent upon p38 mapk in tuberculosis. p38 is therefore a potential target for adjuvant therapy in cns tb. © 2013 green et al.; licensee biomed central ltd.