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Matrix metalloproteinases contribute to brain damage in experimental pneumococcal meningitis
S L Leib1, D Leppert, J Clements
1Institute for Medical Microbiology, University of Berne, Berne, Switzerland. sleib@imm.unibe.ch
Abstract:
The present study was performed to evaluate the role of matrix metalloproteinases (MMP) in the pathogenesis of the inflammatory reaction and the development of neuronal injury in a rat model of bacterial meningitis. mRNA encoding specific MMPs (MMP-3, MMP-7, MMP-8, and MMP-9) and the inflammatory cytokine tumor necrosis factor alpha (TNF-alpha) were significantly (P < 0.04) upregulated, compared to the beta-actin housekeeping gene, in cortical homogenates at 20 h after infection. In parallel, concentrations of MMP-9 and TNF-alpha in cerebrospinal fluid (CSF) were significantly increased in rats with bacterial meningitis compared to uninfected animals (P = 0.002) and showed a close correlation (r = 0.76; P < 0. 001). Treatment with a hydroxamic acid-type MMP inhibitor (GM6001; 65 mg/kg intraperitoneally every 12 h) beginning at the time of infection significantly lowered the MMP-9 (P < 0.02) and TNF-alpha (P < 0.02) levels in CSF. Histopathology at 25.5 +/- 5.7 h after infection showed neuronal injury (median [range], 3.5% [0 to 17.5%] of the cortex), which was significantly (P < 0.01) reduced to 0% (0 to 10.8%) by GM6001. This is the first report to demonstrate that MMPs contribute to the development of neuronal injury in bacterial meningitis and that inhibition of MMPs may be an effective approach to prevent brain damage as a consequence of the disease.
Insights
Matrix metalloproteinases (MMPs) contribute to brain damage in bacterial meningitis. Inhibiting MMPs, like with GM6001, reduced inflammation and neuronal injury in a rat model, offering a potential therapeutic strategy.
Area of Science:
- Neuroscience
- Pathology
- Pharmacology
Background:
- Bacterial meningitis triggers inflammatory responses and neuronal damage.
- Matrix metalloproteinases (MMPs) are implicated in inflammatory conditions.
Purpose of the Study:
- To investigate the role of MMPs in bacterial meningitis pathogenesis.
- To assess the therapeutic potential of MMP inhibition in reducing neuronal injury.
Main Methods:
- Utilized a rat model of bacterial meningitis.
- Measured mRNA expression of MMPs (MMP-3, -7, -8, -9) and TNF-alpha.
- Quantified MMP-9 and TNF-alpha levels in cerebrospinal fluid (CSF).
- Administered MMP inhibitor GM6001 and evaluated histopathological outcomes.
Main Results:
- Upregulation of MMPs and TNF-alpha observed in infected rat cortices and CSF.
- Significant correlation between MMP-9, TNF-alpha levels, and meningitis severity.
- GM6001 treatment reduced MMP-9 and TNF-alpha in CSF.
- GM6001 significantly attenuated neuronal injury in the cortex.
Conclusions:
- MMPs play a critical role in the inflammatory cascade and neuronal injury during bacterial meningitis.
- MMP inhibition represents a promising therapeutic avenue for preventing brain damage in bacterial meningitis.