Matrix metalloproteinase expression in sheep with listerial meningoencephalitis.

Matrix metalloproteinases (MMPs) have been implicated in the pathogenesis of several central nervous system (CNS) diseases. In this study, we investigated the presence of Listeria monocytogenes antigens and detected the expression of MMP-9 and MMP-7 in the brains of 22 sheep with clinical signs and histopathological findings characteristic of listerial meningoencephalitis. Archived sections from the brainstem, cerebrum, and cerebellum were stained for immunohistochemistry. L. monocytogenes antigens were located mainly in the cytoplasm of neutrophils and some macrophages and/or extracellularly within microabscesses of the brainstem. MMP-9 was mainly immunolocalised in the endothelial cells, microglial cells, and neurons especially in inflammatory areas. MMP-7 immunoreactivity was detected in perivascular cuffs, microglial cells, and only a few neurons. Overall, immunohistochemistry in formalin-fixed, paraffin-embedded tissues is a useful tool for the diagnosis of encephalitic listeriosis caused by L. monocytogenes, and MMP-9 and MMP-7 may contribute to the pathogenesis of listerial meningoencephalitis.

[A case of listeria meningitis showed high levels of adenosine deaminase in cerebrospinal fluid].

An 83-year-old woman developed high fever and headache for four days. She had disturbance of consciousness and was admitted to our hospital. A lumbar puncture was performed and cerebrospinal fluid (CSF) analysis revealed a white blood cell count of 268/mm3 and culture became positive for Listeria monocytogenes. Six days after admission, the adenosine deaminase (ADA) level in CSF markedly elevated (43.3 IU/L) with pleocytosis, but a negative PCR test for tuberculosis in CSF, sputum, gastric fluid. She recovered by antibiotics for 45 days and ADA level in CSF was normalized. She was diagnosed as listeria meningitis. High levels of ADA in CSF have high sensitivity and high specificity for tuberculous meningitis, but there are some reports that high ADA levels in CSF in other meningitis. The main biological role of ADA is related to proliferation and differentiation of lymphocytes, and specific activity of this enzyme is slightly higher in T-lymphocytes than in B-lymphocytes. Protective immunity to Listeria monocytogenes is exclusively exhibited by T-lymphocytes. We consider that increased ADA levels in listeria meningitis associated with elevation of T-lymphocytes in CSF. This report suggests that listeria meningitis must be included in the differential diagnosis of high levels of ADA in CSF.