title: 1,4-Naphthoquinone, a pro-oxidant, suppresses immune responses via KEAP-1 glutathionylation.
abstract: Low levels of oxidative stress have been shown to activate Nrf-2, an important anti-inflammatory transcription factor, by us and also by several other investigators. Earlier we showed that pro-oxidants protect normal lymphocytes against radiation injury by activating Nrf-2. In the present study, we have investigated the effect of oxidative stress on immune responses and delineated the underlying mechanism. Hydrogen peroxide, tert-butylhydroquinone and 1,4-naphthoquinone (NQ) inhibited mitogen induced proliferation of lymphocytes. NQ also inhibited mitogen (Concanavalin A) induced cytokine secretion by murine T cells and lipopolysaccharide induced release of cytokines, nitric oxide and cyclooxygenase-2 expression by macrophages. NQ modulated cellular redox by decreasing GSH/GSSG ratio and the immunosuppressive effects of NQ were significantly abrogated by thiol containing antioxidants and not by non-thiol antioxidants. This redox perturbation led to activation of Nrf-2 pathway and inhibition of NF-κB. NQ treatment increased total protein S-thiolation, induced glutathionylation of KEAP-1 protein and decreased IKKβ levels in lymphocytes. Molecular docking studies revealed that NQ can disrupt KEAP-1/Nrf-2 interaction by directly blocking the binding site of Nrf-2 in the KEAP-1 protein. Further, inhibitors of Nrf-2 and HO-1 abrogated the anti-inflammatory effects of NQ. T cells isolated from spleen and gut associated lymphoid tissue of NQ administered mice also showed suppression of NF-κB activation and were hyporesponsive to mitogenic stimulation. These results demonstrate that pro-oxidants modulate inflammatory and immune responses via oxidative stress mediated KEAP-1 glutathionylation and IKKβ degradation.
authors.affiliation: Radiation Biology & Health Sciences Division, Bio-science Group, Mumbai, Maharashtra, India.
authors.forename: Lokesh
authors.initials: L
authors.lastname: Gambhir
authors.affiliation: Radiation Biology & Health Sciences Division, Bio-science Group, Mumbai, Maharashtra, India.
authors.forename: Rahul
authors.initials: R
authors.lastname: Checker
authors.affiliation: Radiation Biology & Health Sciences Division, Bio-science Group, Mumbai, Maharashtra, India.
authors.forename: Maikho
authors.initials: M
authors.lastname: Thoh
authors.affiliation: Radiation Biology & Health Sciences Division, Bio-science Group, Mumbai, Maharashtra, India.
authors.forename: R S
authors.initials: RS
authors.lastname: Patwardhan
authors.affiliation: Radiation Biology & Health Sciences Division, Bio-science Group, Mumbai, Maharashtra, India.
authors.forename: Deepak
authors.initials: D
authors.lastname: Sharma
authors.affiliation: Solid State Physics Division, Physics Group, Bhabha Atomic Research Centre, Trombay, Mumbai, Maharashtra, India.
authors.forename: Mukesh
authors.initials: M
authors.lastname: Kumar
authors.affiliation: Radiation Biology & Health Sciences Division, Bio-science Group, Mumbai, Maharashtra, India. Electronic address: sskumar@barc.gov.in.
authors.forename: Santosh K
authors.initials: SK
authors.lastname: Sandur
mesh_terms: D048868:Adaptor Proteins, Signal Transducing / Q000378:metabolism*; D000818:Animals; D000893:Anti-Inflammatory Agents / Q000494:pharmacology*; D002460:Cell Line; D049109:Cell Proliferation / Q000187:drug effects; D016207:Cytokines / Q000276:immunology / Q000378:metabolism*; D003598:Cytoskeletal Proteins / Q000378:metabolism*; D005978:Glutathione / Q000378:metabolism*; D000072019:Kelch-Like ECH-Associated Protein 1; D008214:Lymphocytes / Q000187:drug effects / Q000276:immunology / Q000378:metabolism; D008297:Male; D051379:Mice; D008807:Mice, Inbred BALB C; D062105:Molecular Docking Simulation; D051267:NF-E2-Related Factor 2 / Q000378:metabolism*; D009285:Naphthoquinones / Q000494:pharmacology*; D009569:Nitric Oxide / Q000378:metabolism; D018384:Oxidative Stress / Q000187:drug effects* / Q000276:immunology
chemical_list: D048868:Adaptor Proteins, Signal Transducing; D000893:Anti-Inflammatory Agents; D016207:Cytokines; D003598:Cytoskeletal Proteins; C117301:Keap1 protein, mouse; D000072019:Kelch-Like ECH-Associated Protein 1; D051267:NF-E2-Related Factor 2; D009285:Naphthoquinones; C495636:Nfe2l2 protein, mouse; D009569:Nitric Oxide; D005978:Glutathione; C035342:1,4-naphthoquinone
keywords: Cytokines; Hemeoxygenase-1; IKKβ, NF-κB; Nrf-2; T cells