Journal
MICROBIAL PATHOGENESIS
Volume 29, Issue 4, Pages 231-244Publisher
ACADEMIC PRESS LTD
DOI: 10.1006/mpat.2000.0383
Keywords
gelatinases; matrix metalloproteinases; tuberculosis; granuloma; lung cavitation
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Funding
- NIAID NIH HHS [1 RO1 AI37937] Funding Source: Medline
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Mycobacterium tuberculosis (Mtb) infection induces the expression of host matrix metalloproteinases (MMPs) capable of tissue degradation. We show that infection of mice with Mtb results in differential expression of MMPs in the lung. MMP-9 activity increased by week 1 post-infection, while MMP-2 activity increased after week 2. RT-PCR analysis for gene expression of gelatinases and their respective inhibitors showed: a small increase in MMP-9 by week 1, no change in TIMP-1 and MMP-2, and a significant decrease in TIMP-2 by week 4. The increase in MMP-2 could be due to a decrease in TIMP-2 expression. Addition of 4-aminophenylmercuric acid to lung extracts increased MMP-9 activity, suggesting that its regulation could be due to endogenous activation by proteases. in vitro, attenuated and virulent Mtb strains equally induced MMP-9 expression in U937 monocytes. The inducer of MMP-9 in Mtb was present in culture filtrates, and was active after paraformaldehyde fixation. LAM stimulated MMP-9 expression in THP-1 cells, but not U937 cells. However, LAM-free extracts also induced MMP-9 activity in THP-1 cells. Fractionation of Mtb extracts by chromatography revealed fractions of 17 and 156 kDa with MMP-9 inducing activity. In conclusion, LAM and other components of Mtb induce the expression of MMP-9.
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