RESUMO
Nitric oxide (NO) donors may be useful for treating pulmonary hypertension (PH) complicating sickle cell disease (SCD), as endogenous NO is inactivated by hemoglobin released by intravascular hemolysis. Here, we investigated the effects of the new NO donor NCX1443 on PH in transgenic SAD mice, which exhibit mild SCD without severe hemolytic anemia. In SAD and wild-type (WT) mice, the pulmonary pressure response to acute hypoxia was similar and was abolished by 100 mg/kg NCX1443. The level of PH was also similar in SAD and WT mice exposed to chronic hypoxia (9% O2) alone or with SU5416 and was similarly reduced by daily NCX1443 gavage. Compared with WT mice, SAD mice exhibited higher levels of HO-1, endothelial NO synthase, and PDE5 but similar levels of lung cyclic guanosine monophosphate. Cultured pulmonary artery smooth muscle cells from SAD mice grew faster than those from WT mice and had higher PDE5 protein levels. Combining NCX1443 and a PDE5 inhibitor suppressed the growth rate difference between SAD and WT cells and induced a larger reduction in hypoxic PH severity in SAD than in WT mice. By amplifying endogenous protective mechanisms, NCX1443 in combination with PDE5 inhibition may prove useful for treating PH complicating SCD.
Assuntos
Anemia Falciforme/tratamento farmacológico , Anti-Hipertensivos/farmacologia , Pressão Arterial/efeitos dos fármacos , Hipertensão Pulmonar/prevenção & controle , Doadores de Óxido Nítrico/farmacologia , Óxido Nítrico/metabolismo , Artéria Pulmonar/efeitos dos fármacos , Anemia Falciforme/complicações , Anemia Falciforme/metabolismo , Animais , Anti-Hipertensivos/metabolismo , Proliferação de Células/efeitos dos fármacos , Células Cultivadas , GMP Cíclico/metabolismo , Nucleotídeo Cíclico Fosfodiesterase do Tipo 5/metabolismo , Modelos Animais de Doenças , Heme Oxigenase-1/metabolismo , Hipertensão Pulmonar/etiologia , Hipertensão Pulmonar/metabolismo , Hipertensão Pulmonar/fisiopatologia , Hipóxia/complicações , Masculino , Proteínas de Membrana/metabolismo , Camundongos Endogâmicos C57BL , Camundongos Transgênicos , Músculo Liso Vascular/efeitos dos fármacos , Músculo Liso Vascular/metabolismo , Músculo Liso Vascular/patologia , Miócitos de Músculo Liso/efeitos dos fármacos , Miócitos de Músculo Liso/metabolismo , Miócitos de Músculo Liso/patologia , Doadores de Óxido Nítrico/metabolismo , Óxido Nítrico Sintase Tipo III/metabolismo , Inibidores da Fosfodiesterase 5/farmacologia , Artéria Pulmonar/metabolismo , Artéria Pulmonar/fisiopatologiaRESUMO
Chronic obstructive pulmonary disease (COPD) is a highly prevalent and devastating condition for which no curative treatment is available. Exaggerated lung cell senescence may be a major pathogenic factor. Here, we investigated the potential role for mTOR signaling in lung cell senescence and alterations in COPD using lung tissue and derived cultured cells from patients with COPD and from age- and sex-matched control smokers. Cell senescence in COPD was linked to mTOR activation, and mTOR inhibition by low-dose rapamycin prevented cell senescence and inhibited the proinflammatory senescence-associated secretory phenotype. To explore whether mTOR activation was a causal pathogenic factor, we developed transgenic mice exhibiting mTOR overactivity in lung vascular cells or alveolar epithelial cells. In this model, mTOR activation was sufficient to induce lung cell senescence and to mimic COPD lung alterations, with the rapid development of lung emphysema, pulmonary hypertension, and inflammation. These findings support a causal relationship between mTOR activation, lung cell senescence, and lung alterations in COPD, thereby identifying the mTOR pathway as a potentially new therapeutic target in COPD.
Assuntos
Pulmão/patologia , Doença Pulmonar Obstrutiva Crônica/patologia , Enfisema Pulmonar/patologia , Serina-Treonina Quinases TOR/metabolismo , Idoso , Animais , Estudos de Casos e Controles , Células Cultivadas , Senescência Celular/efeitos dos fármacos , Feminino , Humanos , Pulmão/citologia , Pulmão/efeitos dos fármacos , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Transgênicos , Pessoa de Meia-Idade , Cultura Primária de Células , Enfisema Pulmonar/genética , Sirolimo/farmacologia , Serina-Treonina Quinases TOR/antagonistas & inibidores , Serina-Treonina Quinases TOR/genética , Fumar Tabaco/patologia , Proteína 1 do Complexo Esclerose Tuberosa/deficiência , Proteína 1 do Complexo Esclerose Tuberosa/genéticaRESUMO
Constitutive activation of the mammalian target of rapamycin (mTOR) complexes mTORC1 and mTORC2 is associated with pulmonary hypertension (PH) and sustained growth of pulmonary artery (PA) smooth muscle cells (SMCs). We investigated whether selective mTORC1 activation in SMCs induced by deleting the negative mTORC1 regulator tuberous sclerosis complex 1 gene (TSC1) was sufficient to produce PH in mice. Mice expressing Cre recombinase under SM22 promoter control were crossed with TSC1(LoxP/LoxP) mice to generate SM22-TSC1(-/-) mice. At 8 weeks of age, SM22-TSC1(-/-) mice exhibited PH with marked increases in distal PA muscularization and Ki67-positive PASMC counts, without systemic hypertension or cardiac dysfunction. Marked activation of the mTORC1 substrates S6 kinase and 4E-BP and the mTORC2 substrates p-Akt(Ser473) and glycogen synthase kinase 3 was found in the lungs and pulmonary vessels of SM22-TSC1(-/-) mice when compared with control mice. Treatment with 5 mg/kg rapamycin for 3 weeks to inhibit mTORC1 and mTORC2 fully reversed PH in SM22-TSC1(-/-) mice. In chronically hypoxic mice and SM22-5HTT(+) mice exhibiting PH associated with mTORC1 and mTORC2 activation, PH was maximally attenuated by low-dose rapamycin associated with selective mTORC1 inhibition. Cultured PASMCs from SM22-TSC1(-/-), SM22-5HTT(+), and chronically hypoxic mice exhibited similar sustained growth-rate enhancement and constitutive mTORC1 and mTORC2 activation; both effects were abolished by rapamycin. Deletion of the downstream mTORC1 effectors S6 kinase 1/2 in mice also activated mTOR signaling and induced PH. We concluded that activation of mTORC1 signaling leads to increased PASMC proliferation and subsequent PH development.
Assuntos
Deleção de Genes , Hipertensão Pulmonar/metabolismo , Músculo Liso/metabolismo , Transdução de Sinais , Serina-Treonina Quinases TOR/metabolismo , Proteínas Supressoras de Tumor/metabolismo , Animais , Proliferação de Células/efeitos dos fármacos , Células Cultivadas , Doença Crônica , Hiperplasia , Hipertensão Pulmonar/diagnóstico por imagem , Hipóxia/complicações , Hipóxia/metabolismo , Hipóxia/patologia , Pulmão/irrigação sanguínea , Pulmão/patologia , Masculino , Metformina/farmacologia , Camundongos , Proteínas dos Microfilamentos/metabolismo , Proteínas Musculares/metabolismo , Músculo Liso/efeitos dos fármacos , Miócitos de Músculo Liso/efeitos dos fármacos , Miócitos de Músculo Liso/metabolismo , Artéria Pulmonar/patologia , Proteínas Quinases S6 Ribossômicas 90-kDa/metabolismo , Transdução de Sinais/efeitos dos fármacos , Sirolimo/farmacologia , Proteína 1 do Complexo Esclerose TuberosaRESUMO
Cellular senescence--defined as a stable cell-cycle arrest combined with stereotyped phenotypic changes--might play a causal role in various lung diseases, including chronic obstructive pulmonary disease (COPD), which is predicted to become the third leading cause of death worldwide by 2020. COPD is characterized by slowly progressive airflow obstruction and emphysema due to destruction of the lung parenchyma and is often complicated by pulmonary hypertension (PH). No curative treatment is available. Senescent cells, which accumulate with age, are increased in lungs from patients with COPD and express a robust senescence-associated secretory phenotype (SASP), which is proinflammatory. The aim of this review is to show how senescent cells can drive the lung alterations seen in COPD, which mechanisms may be involved, and whether therapeutic interventions may slow or delay the in vitro cell-senescence process and in vivo lung alterations.