RESUMO
Silicosis is a lethal pneumoconiosis for which no therapy is available. Silicosis is a global threat, and more than 2.2 million people per year are exposed to silica in the United States. The initial response to silica is mediated by innate immunity. Phagocytosis of silica particles by macrophages is followed by recruitment of mitochondria to phagosomes, generation of mitochondrial reactive oxygen species, and cytokine (IL-1ß, TNF-α, IFN-ß) release. In contrast with LPS, the metabolic remodeling of silica-exposed macrophages is unclear. This study contrasts mitochondrial and metabolic alterations induced by LPS and silica on macrophages and correlates them with macrophage viability and cytokine production, which are central to the pathogenesis of silicosis. Using high-resolution respirometer and liquid chromatography-high-resolution mass spectrometry, we determined the effects of silica and LPS on mitochondrial respiration and determined changes in central carbon metabolism of murine macrophage cell lines RAW 264.7 and IC-21. We show that silica induces metabolic reprogramming of macrophages. Silica, as well as LPS, enhances glucose uptake and increases aerobic glycolysis in macrophages. In contrast with LPS, silica affects mitochondria respiration, reducing complex I and enhancing complex II activity, to sustain cell viability. These mitochondrial alterations are associated in silica, but not in LPS-exposed macrophages, with reductions of tricarboxylic acid cycle intermediates, including succinate, itaconate, glutamate, and glutamine. Furthermore, in contrast with LPS, these silica-induced metabolic adaptations do not correlate with IL-1ß or TNF-α production, but with the suppressed release of IFN-ß. Our data highlight the importance of complex II activity and tricarboxylic acid cycle remodeling to macrophage survival and cytokine-mediated inflammation in silicosis.
Assuntos
Ativação de Macrófagos/efeitos dos fármacos , Macrófagos/efeitos dos fármacos , Macrófagos/imunologia , Dióxido de Silício/química , Dióxido de Silício/farmacologia , Silicose/imunologia , Animais , Sobrevivência Celular/efeitos dos fármacos , Ciclo do Ácido Cítrico/efeitos dos fármacos , Cristalização , Citocinas/biossíntese , Inflamação/imunologia , Inflamação/metabolismo , Lipopolissacarídeos/farmacologia , Macrófagos/metabolismo , Camundongos , Mitocôndrias/efeitos dos fármacos , Mitocôndrias/metabolismo , Fagocitose/efeitos dos fármacos , Fagossomos/metabolismo , Células RAW 264.7 , Transdução de Sinais/efeitos dos fármacos , Silicose/metabolismoAssuntos
COVID-19 , Pulmão , Células Mieloides/patologia , Pneumonia Viral , SARS-CoV-2 , Replicação Viral , Anticorpos Antivirais/análise , COVID-19/imunologia , COVID-19/fisiopatologia , COVID-19/terapia , COVID-19/virologia , Proteínas do Nucleocapsídeo de Coronavírus/imunologia , Tomografia com Microscopia Eletrônica , Feminino , Humanos , Imunidade nas Mucosas , Pulmão/imunologia , Pulmão/patologia , Pulmão/virologia , Masculino , Microscopia Eletrônica , Pessoa de Meia-Idade , Neutrófilos/patologia , Fosfoproteínas/imunologia , Pneumonia Viral/imunologia , Pneumonia Viral/virologia , Respiração Artificial/métodos , Mucosa Respiratória/imunologia , Mucosa Respiratória/virologia , SARS-CoV-2/isolamento & purificação , SARS-CoV-2/fisiologiaRESUMO
OBJECTIVE: Congenital bicuspid aortic valve (BAV) is distinctly associated with the development of ascending aortopathy in adulthood, portending risk of both ascending aortic aneurysm and dissection. Our previous work implicated deficiency in oxidative stress response as a mediator of the BAV-associated aortopathy. We hypothesize that reactive oxygen species generation invokes elevated local oxidative tissue damage in ascending aorta of patients with BAV. METHODS: Ascending aortic specimens were obtained from patients undergoing elective aortic replacement and/or aortic valve replacement and during heart transplant operations. Levels of superoxide anion were measured via high-pressure liquid chromatography-based detection of 2-hydroxyethidium in aortic specimens. Lipid peroxidation and enzymatic activity of superoxide dismutase and peroxidase were quantified in aortic specimens. RESULTS: Superoxide anion production was elevated in aortic specimens from patients with nonaneurysmal BAV (n = 59) compared with specimens from patients with the morphologically normal tricuspid aortic valve (TAV, n = 38). Total superoxide dismutase activity was similar among aortic specimens from patients with TAV versus BAV (n = 27 and 26, respectively), whereas peroxidase activity was increased in aortic specimens from patients with BAV compared with specimens from patients with TAV (n = 14 for both groups). Lipid peroxidation was elevated in aortic specimens from BAV patients compared with TAV patients (n = 14 and 11, respectively). CONCLUSIONS: Superoxide anion accumulation and increased lipid peroxidation demonstrate that, despite increased peroxidase activity, the ascending aortopathy of patients with BAV involves oxidative stress. In addition, the absence of increased superoxide dismutase activity in BAV specimens indicates a deficiency in antioxidant defense. This suggests that the characteristic smooth muscle cell loss observed in BAV aortopathy may be a consequence of superoxide-mediated cell damage.