title: Endothelial nitric oxide synthase is a key mediator of interleukin-2-induced hypotension and vascular leak syndrome.
abstract: Despite increasing use of "targeted therapy," interleukin-2 (IL-2) is unique, because this cytokine can induce long-term remissions in 5% to 7% of patients with metastatic melanoma and renal cancer. Clinical use of IL-2 is limited by severe toxicities, such as hypotension and vascular leak syndrome (VLS). Nitric oxide seems to be involved in the pathogenesis of these toxicities. On the basis of previous studies, we hypothesized that the endothelial nitric oxide synthase (eNOS) is the major source of nitric oxide. Mice with a knockout of the eNOS isoenzyme were treated with IL-2 (800,000 IU twice daily for 5 d). Blood pressure and vascular leak were measured. Inhibitors of superoxide, nitric oxide, and soluble guanylate cyclase were used to probe the mechanism. These experiments showed that IL-2 treatment increased eNOS messenger ribonucleic acid expression and nitric oxide metabolite excretion in eNOS knockout mice. Unlike normal and inducible nitric oxide synthase knockout mice, eNOS knockout mice proved resistant to IL-2-induced hypotension and vascular leak. Although hypotension seems to be mediated by superoxide or peroxynitrite, vascular leak seemed to be mediated by nitric oxide. Inhibition of guanylate cyclase and cyclic guanylate monophosphate formation during IL-2 treatment using methylene blue (MB)-inhibited vascular leak. MB treatment did not interfere with IL-2-induced antitumor mechanisms. Our experiments established that eNOS is a key mediator of IL-2-induced VLS and hypotension. A clinical trial of MB infusion during IL-2 therapy is currently being planned.
authors.affiliation: Section of Melanoma, Renal Cancer and Immunotherapy, Nevada Cancer Institute, Las Vegas, USA. wolf.samlowski@usoncology.com
authors.forename: Wolfram E
authors.initials: WE
authors.lastname: Samlowski
authors.forename: Muralidhar
authors.initials: M
authors.lastname: Kondapaneni
authors.forename: Shweta
authors.initials: S
authors.lastname: Tharkar
authors.forename: John R
authors.initials: JR
authors.lastname: McGregor
authors.forename: Victor E
authors.initials: VE
authors.lastname: Laubach
authors.forename: Daniela
authors.initials: D
authors.lastname: Salvemini
mesh_terms: D000818:Animals; D001794:Blood Pressure / Q000187:drug effects; D019559:Capillary Leak Syndrome / Q000139:chemically induced / Q000378:metabolism; D002292:Carcinoma, Renal Cell / Q000188:drug therapy; D006152:Cyclic GMP / Q000378:metabolism; D004791:Enzyme Inhibitors / Q000494:pharmacology; D006162:Guanylate Cyclase / Q000037:antagonists & inhibitors / Q000378:metabolism*; D006801:Humans; D007022:Hypotension / Q000139:chemically induced / Q000378:metabolism; D007376:Interleukin-2 / Q000009:adverse effects / Q000494:pharmacology; D008345:Manganese; D008545:Melanoma / Q000188:drug therapy; D008751:Methylene Blue / Q000494:pharmacology; D051379:Mice; D008815:Mice, Inbred Strains; D018345:Mice, Knockout; D009569:Nitric Oxide / Q000378:metabolism; D052250:Nitric Oxide Synthase Type III / Q000037:antagonists & inhibitors / Q000172:deficiency / Q000235:genetics; D009942:Organometallic Compounds / Q000494:pharmacology; D012333:RNA, Messenger / Q000096:biosynthesis; D018160:Receptors, Cytoplasmic and Nuclear / Q000037:antagonists & inhibitors / Q000378:metabolism*; D000071756:Soluble Guanylyl Cyclase; D013481:Superoxides / Q000378:metabolism; D019323:omega-N-Methylarginine / Q000494:pharmacology
chemical_list: D004791:Enzyme Inhibitors; D007376:Interleukin-2; D009942:Organometallic Compounds; D012333:RNA, Messenger; D018160:Receptors, Cytoplasmic and Nuclear; D013481:Superoxides; D019323:omega-N-Methylarginine; C121876:imisopasem manganese; D009569:Nitric Oxide; D008345:Manganese; D052250:Nitric Oxide Synthase Type III; C496315:Nos3 protein, mouse; D006162:Guanylate Cyclase; D000071756:Soluble Guanylyl Cyclase; D006152:Cyclic GMP; D008751:Methylene Blue