title: Anthrax lethal toxin downregulates claudin-5 expression in human endothelial tight junctions.
abstract: Vascular leakage pathologies such as pleural effusion and hemorrhage are hallmarks of anthrax pathogenesis. We previously reported that anthrax lethal toxin (LT), the major virulence factor of anthrax, reduces barrier function in cultured primary human microvascular endothelial cells. Here, we show that LT-induced barrier dysfunction is accompanied by the reduced expression of the endothelial tight junction (TJ) protein claudin-5 but no change in the expression of other TJ components occludin, ZO-1, ZO-2, or the adherens junction (AJ) protein VE-cadherin. The downregulation of claudin-5 correlated temporally and dose-dependently with the reduction of transendothelial electrical resistance. LT-induced loss of claudin-5 was independent of cell death and preceded the appearance of actin stress fibers and altered AJ morphology. Pharmacological inhibition of MEK-1/2, two kinases that are proteolytically inactivated by LT, showed a similar reduction in claudin-5 expression. We found that LT reduced claudin-5 mRNA levels but did not accelerate the rate of claudin-5 degradation. Mice challenged with LT also showed significant reduction in claudin-5 expression. Together, these findings support a possible role for LT disruption of endothelial TJs in the vascular leakage pathologies of anthrax.
authors.affiliation: Laboratory of Biochemistry and Vascular Biology, Division of Hematology, Center for Biologics Evaluation and Research, Food and Drug Administration, Bethesda, Maryland, United States of America. felice.dagnillo@fda.hhs.gov
authors.forename: Felice
authors.initials: F
authors.lastname: D'Agnillo
authors.forename: Matthew C
authors.initials: MC
authors.lastname: Williams
authors.forename: Mahtab
authors.initials: M
authors.lastname: Moayeri
authors.forename: Jason M
authors.initials: JM
authors.lastname: Warfel
mesh_terms: D000818:Animals; D000942:Antigens, Bacterial / Q000494:pharmacology*; D015703:Antigens, CD / Q000235:genetics* / Q000378:metabolism; D001427:Bacterial Toxins / Q000494:pharmacology*; D015820:Cadherins / Q000235:genetics* / Q000378:metabolism; D016923:Cell Death / Q000187:drug effects; D004305:Dose-Response Relationship, Drug; D042783:Endothelial Cells / Q000187:drug effects / Q000378:metabolism; D004730:Endothelium, Vascular / Q000378:metabolism*; D005260:Female; D005786:Gene Expression Regulation / Q000187:drug effects*; D008099:Liver / Q000187:drug effects / Q000378:metabolism; D051379:Mice; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism; D059748:Proteolysis / Q000187:drug effects; D012333:RNA, Messenger / Q000235:genetics; D015398:Signal Transduction / Q000187:drug effects; D019108:Tight Junctions / Q000378:metabolism*; D000099152:Cadherin 5
chemical_list: D000942:Antigens, Bacterial; D015703:Antigens, CD; D001427:Bacterial Toxins; D015820:Cadherins; D020928:Mitogen-Activated Protein Kinases; D012333:RNA, Messenger; D000099152:Cadherin 5; C030325:anthrax toxin