RESUMO
Sepsis is characterized by an inappropriate host immune-inflammatory response and sustained oxidative damage. Nrf2, a bZIP oxidant-responsive transcription factor, regulates a battery of cytoprotective genes including antioxidants and maintains cellular redox homeostasis. Mouse studies have demonstrated a critical role of Nrf2 in improving survival during sepsis. This preclinical ex vivo study using neutrophils and peripheral blood mononuclear cells (PBMCs) as a surrogate cells evaluates the efficacy of CDDO-Im and CDDO-Me [imidazole and methyl ester derivative of 2-cyano-3,12-dioxooleana-1,9(11)-dien-28-oic acid (CDDO)] to activate the Nrf2 pathway and protect from lipopolysaccharide (LPS)-induced inflammatory response in humans. CDDO-Im treatment significantly induced Nrf2-dependent antioxidative genes (HO-1, GCLC, GCLM, and NQO1) in PBMCs isolated from six normal subjects. CDDO-Im increased nuclear accumulation of Nrf2 protein. Pretreatment of PBMC by CDDO-Im significantly attenuated LPS-induced cytokine expression. Similar increases in levels of antioxidant genes and suppression of LPS-induced cytokine expression was observed after CDDO-Me pretreatment. CDDO-Im also greatly inhibited LPS, fMLP, TNF-alpha, and TPA-induced ROS generation in neutrophils. In conclusion, these results demonstrate that activation of the Nrf2-dependent antioxidative pathway by CDDO-Im or CDDO-Me protects against the LPS-induced inflammatory response and suggest that they can be potential therapeutic candidates for intervening sepsis syndrome.
Assuntos
Citocinas/metabolismo , Imidazóis/farmacologia , Leucócitos Mononucleares/imunologia , Fator 2 Relacionado a NF-E2/fisiologia , Neutrófilos/imunologia , Ácido Oleanólico/análogos & derivados , Avaliação Pré-Clínica de Medicamentos , Regulação da Expressão Gênica/efeitos dos fármacos , Humanos , Inflamação/induzido quimicamente , Inflamação/genética , Inflamação/imunologia , Leucócitos Mononucleares/efeitos dos fármacos , Lipopolissacarídeos/toxicidade , Fator 2 Relacionado a NF-E2/genética , Neutrófilos/efeitos dos fármacos , Ácido Oleanólico/farmacologia , RNA Mensageiro/metabolismo , Espécies Reativas de Oxigênio/metabolismo , Receptores de Formil Peptídeo/metabolismo , Fatores de Tempo , Fator de Necrose Tumoral alfa/metabolismoRESUMO
The beta zipper (bZip) transcription factor, nuclear factor erythroid 2, like 2 (Nrf2), acting via an antioxidant/electrophile response element, regulates the expression of several antioxidant enzymes and maintains cellular redox homeostasis. Nrf2 deficiency diminishes pulmonary expression of several antioxidant enzymes, rendering them highly susceptible to various mouse models of prooxidant-induced lung injury. We recently demonstrated that Nrf2 deficiency impairs primary cultured pulmonary epithelial cell proliferation and greatly enhances sensitivity to prooxidant-induced cell death. Glutathione (GSH) supplementation rescued cells from these defects associated with Nrf2 deficiency. To further delineate the mechanisms by which Nrf2, via redox signaling, regulates cellular protection and proliferation, we compared the global expression profiling of Nrf2-deficient cells with and without GSH supplementation. We found that GSH regulates the expression of various networks of transcriptional programs including 1) several antioxidant enzymes involved in cellular detoxification of reactive oxygen species and recycling of thiol status and 2) several growth factors, growth factor receptors, and integrins that are critical for cell growth and proliferation. We also found that Nrf2 deficiency enhances the expression levels of several genes encoding proinflammatory cytokines; however, GSH supplementation markedly suppressed their expression. Collectively, these findings uncover an important insight into the nature of genes regulated by Nrf2-dependent redox signaling through GSH that are involved in cellular detoxification and proliferation.
Assuntos
Perfilação da Expressão Gênica , Pulmão/citologia , Pulmão/fisiologia , Fator 2 Relacionado a NF-E2/deficiência , Fator 2 Relacionado a NF-E2/genética , Transcrição Gênica , Animais , Divisão Celular , Sobrevivência Celular , Glutationa/farmacologia , Glutationa/fisiologia , Pulmão/efeitos dos fármacos , Camundongos , Camundongos Knockout , Fator 2 Relacionado a NF-E2/fisiologia , Análise de Sequência com Séries de Oligonucleotídeos , Reação em Cadeia da Polimerase , RNA/genética , RNA/isolamento & purificação , Transdução de SinaisRESUMO
Sepsis induced lethality is characterized by amplified host innate immune response. Nrf2, a bZIP transcription factor, regulates a battery of cellular antioxidative genes and maintains cellular redox homeostasis. This study demonstrates that increasing Nrf2 activity by a potent small molecule activator, CDDO-Im (1-[2-cyano-3-,12-dioxooleana-1,9(11)-dien-28-oyl]imidazole), protects from deregulation of lipopolysaccharide (LPS) induced innate immune response. In response to LPS stimuli, nrf2-deficient (nrf2 -/-) peritoneal neutrophils showed increased NADPH oxidase-dependent ROS generation, proinflammatory cytokines (Tnf-alpha and Il-6) and chemokines (Mip2 and Mcp-1) relative to wild-type (nrf2 +/+) cells. Pretreatment of peritoneal neutrophils with CDDO-Im induced antioxidative genes (Ho-1, Gclc, Gclm, and Nqo1) and attenuated LPS induced ROS generation as well as expression of proinflammatory cytokines exclusively in nrf2 +/+ neutrophils but not in nrf2 -/- cells. In corroboration with in vitro studies, pretreatment with CDDO-Im induced Nrf2-dependent antioxidative genes, attenuated LPS induced proinflammatory cytokine expression, and decreased mortality specifically in the nrf2 +/+ mice. In conclusion, the results suggest that Nrf2 is associated with oxidative regulation of LPS induced innate immune response in neutrophils. Activation of Nrf2-dependent compensatory antioxidative pathways by CDDO-Im protects from LPS induced inflammatory response and mortality.
