{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,9,17]],"date-time":"2026-09-17T03:22:07Z","timestamp":1789615327943,"version":"build-2803163510"},"reference-count":51,"publisher":"Frontiers Media SA","license":[{"start":{"date-parts":[[2026,5,8]],"date-time":"2026-05-08T00:00:00Z","timestamp":1778198400000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"content-domain":{"domain":["frontiersin.org"],"crossmark-restriction":true},"short-container-title":["Front. Microbiol."],"abstract":"<jats:sec>\n                    <jats:title>Background<\/jats:title>\n                    <jats:p>\n                      <jats:italic>Pseudomonas aeruginosa<\/jats:italic>\n                      is a ubiquitous organism that adapts well in different environments. It is an opportunistic bacterial pathogen that produces a wide range of virulence factors, colonizes lungs to cause pneumonia, causes non-healing wounds especially in burn victims, and is a major culprit in destructive keratitis. It can reach the cornea through reusable, extended-use contact lenses and by contaminated eyedrops and artificial tears. Secreted proteases of\n                      <jats:italic>P. aeruginosa<\/jats:italic>\n                      together with pyocyanin metabolite, which inhibits Serine Protease Inhibitors (Serpins) activity contribute to severe tissue damage during infection.\n                    <\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Methods<\/jats:title>\n                    <jats:p>\n                      <jats:italic>Pseudomonas aeruginosa<\/jats:italic>\n                      strains isolated from different clinical sites were obtained from different researchers and clinicians for this study. We examined\n                      <jats:italic>P. aeruginosa<\/jats:italic>\n                      strains and secretion defective and prpL knockout mutants in PA64481 strain for lysyl endopeptidase (PrpL, a serine protease that cleaves after a lysine residue) activity using serine protease specific D-Val-Leu-Lys -p-nitroanalide substrate. We also determined pyocyanin production in these strains.\n                    <\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Results<\/jats:title>\n                    <jats:p>\n                      Examination of secreted milieu from\n                      <jats:italic>P. aeruginosa<\/jats:italic>\n                      showed that 41 corneal isolates had detectable lysyl endopeptidase activity associated with PrpL at levels significantly higher than by 27 non-corneal isolates. We found that PrpL is secreted by the\n                      <jats:italic>xcp-<\/jats:italic>\n                      based type II secretion system. Bacterial culture supernatants displaying higher PrpL activity and not low secreted PrpL levels disrupted corneal epithelial cell monolayers\n                      <jats:italic>in vitro,<\/jats:italic>\n                      which is consistent with a role of this protease in destructive keratitis. Many examined strains also produced high levels of pyocyanin.\n                    <\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Conclusion<\/jats:title>\n                    <jats:p>\n                      This retrospective examination of clinical\n                      <jats:italic>P. aeruginosa<\/jats:italic>\n                      suggests that high levels of PrpL and pyocyanin-producing isolates are more prevalent among corneal isolates and could enhance tissue damage during infection. Supporting this premise, corneal epithelial cell monolayers disrupted by high PrpL-producing strains but remained intact after treatment with\n                      <jats:italic>P. aeruginosa<\/jats:italic>\n                      mutants culture supernatants that lack or have reduced secreted PrpL.\n                    <\/jats:p>\n                  <\/jats:sec>","DOI":"10.3389\/fmicb.2026.1824817","type":"journal-article","created":{"date-parts":[[2026,5,8]],"date-time":"2026-05-08T05:56:38Z","timestamp":1778219798000},"update-policy":"https:\/\/doi.org\/10.3389\/crossmark-policy","source":"Crossref","is-referenced-by-count":2,"title":["Retrospective analysis of secreted PrpL protease activity in clinical isolates of Pseudomonas aeruginosa and its association with corneal tissue damage"],"prefix":"10.3389","volume":"17","author":[{"given":"Douglas S.","family":"Parker","sequence":"first","affiliation":[{"name":"Department of Microbiology and Physiological Systems, University of Massachusetts Medical School","place":["Worcester, MA, United States"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Onyedikachi C.","family":"Azuama","sequence":"additional","affiliation":[{"name":"Department of Microbiology, Biochemistry and Molecular Genetics, Rutgers-New Jersey Medical School","place":["Newark, NJ, United States"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Kashaf","family":"Zafar","sequence":"additional","affiliation":[{"name":"Department of Microbiology, Biochemistry and Molecular Genetics, Rutgers-New Jersey Medical School","place":["Newark, NJ, United States"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Jon D.","family":"Goguen","sequence":"additional","affiliation":[{"name":"Department of Microbiology and Physiological Systems, University of Massachusetts Medical School","place":["Worcester, MA, United States"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"John M.","family":"Leong","sequence":"additional","affiliation":[{"name":"Department of Molecular Biology and Microbiology, Tufts University School of Medicine","place":["Boston, MA, United States"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Nikhat","family":"Parveen","sequence":"additional","affiliation":[{"name":"Department of Microbiology, Biochemistry and Molecular Genetics, Rutgers-New Jersey Medical School","place":["Newark, NJ, United States"]}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1965","published-online":{"date-parts":[[2026,5,8]]},"reference":[{"key":"ref1","doi-asserted-by":"publisher","first-page":"5565","DOI":"10.1128\/IAI.71.10.5565-5575.2003","article-title":"Mucin degradation mechanisms by distinct Pseudomonas aeruginosa isolates in vitro","volume":"71","author":"Aristoteli","year":"2003","journal-title":"Infect. 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