l-Glutamate in Middlebrook 7H9 culture medium upregulates matrix metalloproteinase-2 secretion from human astrocytoma cells

Matrix metalloproteinases (MMPs) are implicated in the pathology of CNS tuberculosis. Whilst investigating the secretion of MMP-2 from human U373-MG astrocytoma cells, we observed elevated MMP-2 secretion in response to Middlebrook 7H9 media but not to Mycobacterium tuberculosis itself. Middlebrook 7H9 media did not stimulate MMP-1 or MMP-9 secretion from astrocytoma cells. The excitatory neurotransmitter l-glutamate, at concentrations found in Middlebrook 7H9 media, induced significant astrocytoma MMP-2 secretion (p < 0.05). l-Glutamate-induced MMP-2 activity may contribute to neuropathology in various CNS diseases and may generate misleading data in pathogen studies where Middlebrook 7H9 is the culture medium.