{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,10,7]],"date-time":"2026-10-07T15:23:48Z","timestamp":1791386628896,"version":"4.3.3"},"reference-count":29,"publisher":"Springer Science and Business Media LLC","issue":"1","content-domain":{"domain":["link.springer.com"],"crossmark-restriction":false},"short-container-title":["BMC Microbiol"],"published-print":{"date-parts":[[2006,12]]},"abstract":"<jats:title>Abstract<\/jats:title>\n          <jats:sec>\n            <jats:title>Background<\/jats:title>\n            <jats:p>Granulomatous amoebic encephalitis due to <jats:italic>Acanthamoeba<\/jats:italic> is often a fatal human disease. However, the pathogenesis and pathophysiology of <jats:italic>Acanthamoeba<\/jats:italic> encephalitis remain unclear. In this study, the role of extracellular <jats:italic>Acanthamoeba<\/jats:italic> proteases in central nervous system pathogenesis and pathophysiology was examined.<\/jats:p>\n          <\/jats:sec>\n          <jats:sec>\n            <jats:title>Results<\/jats:title>\n            <jats:p>Using an encephalitis isolate belonging to T1 genotype, we observed two major proteases with approximate molecular weights of 150 KD and 130 KD on SDS-PAGE gels using gelatin as substrate. The 130 KD protease was inhibited with phenylmethylsulfonyl fluoride (PMSF) suggesting that it is a serine protease, while the 150 KD protease was inhibited with 1, 10-phenanthroline suggesting that it is a metalloprotease. Both proteases exhibited maximal activity at neutral pH and over a range of temperatures, indicating their physiological relevance. These proteases degrade extracellular matrix (ECM), which provide structural and functional support to the brain tissue, as shown by the degradation of collagen I and III (major components of collagenous ECM), elastin (elastic fibrils of ECM), plasminogen (involved in proteolytic degradation of ECM), as well as casein and haemoglobin. The proteases were purified partially using ion-exchange chromatography and their effects were tested in an <jats:italic>in vitro<\/jats:italic> model of the blood-brain barrier using human brain microvascular endothelial cells (HBMEC). Neither the serine nor the metalloprotease exhibited HBMEC cytotoxicity. However, the serine protease exhibited HBMEC monolayer disruptions (trypsin-like) suggesting a role in blood-brain barrier perturbations.<\/jats:p>\n          <\/jats:sec>\n          <jats:sec>\n            <jats:title>Conclusion<\/jats:title>\n            <jats:p>Overall, these data suggest that <jats:italic>Acanthamoeba<\/jats:italic> proteases digest ECM, which may play crucial role(s) in invasion of the brain tissue by amoebae.<\/jats:p>\n          <\/jats:sec>","DOI":"10.1186\/1471-2180-6-42","type":"journal-article","created":{"date-parts":[[2006,5,3]],"date-time":"2006-05-03T18:22:01Z","timestamp":1146680521000},"update-policy":"https:\/\/doi.org\/10.1007\/springer_crossmark_policy","source":"Crossref","is-referenced-by-count":59,"title":["Identification and properties of proteases from an Acanthamoeba isolate capable of producing granulomatous encephalitis"],"prefix":"10.1186","volume":"6","author":[{"given":"James","family":"Sissons","sequence":"first","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Selwa","family":"Alsam","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Graham","family":"Goldsworthy","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Mary","family":"Lightfoot","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Edward L","family":"Jarroll","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Naveed Ahmed","family":"Khan","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"297","published-online":{"date-parts":[[2006,5,3]]},"reference":[{"key":"255_CR1","doi-asserted-by":"publisher","first-page":"583","DOI":"10.1111\/j.1750-3639.1997.tb01076.x","volume":"7","author":"AJ Martinez","year":"1997","unstructured":"Martinez AJ, Visvesvara GS: Free-living, amphizoic and opportunistic amebas. 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