RESUMO
BACKGROUND: Efferocytosis is an activity of macrophages that is pivotal for the resolution of inflammation in hypertension. The precise mechanism by which macrophages coordinate efferocytosis and internalize apoptotic cardiomyocytes remains unknown. The aim of this study was to determine whether SIRT3 (sirtuin-3) is required for both apoptotic cardiomyocyte engulfment and anti-inflammatory responses during efferocytosis. METHODS: We generated myeloid SIRT3 knockout mice and FXN (frataxin) knock-in mice carrying an acetylation-defective lysine to arginine K189R mutation (FXNK189R). The mice were given Ang II (angiotensin II) infusion for 7 days. We analyzed cardiac macrophages' mitochondrial iron levels, efferocytosis activity, and phenotype both in vivo and in vitro. RESULTS: We showed that SIRT3 deficiency exacerbated Ang II-induced downregulation of the efferocytosis receptor MerTK (c-Mer tyrosine kinase) and proinflammatory cytokine production, accompanied by disrupted mitochondrial iron homeostasis in cardiac macrophages. Quantitative acetylome analysis revealed that SIRT3 deacetylated FXN at lysine 189. Ang II attenuated SIRT3 activity and enhanced the acetylation level of FXNK189. Acetylated FXN further reduced the synthesis of ISCs (iron-sulfur clusters), resulting in mitochondrial iron accumulation. Phagocytic internalization of apoptotic cardiomyocytes increased myoglobin content, and derived iron ions promoted mitochondrial iron overload and lipid peroxidation. An iron chelator deferoxamine improved the levels of MerTK and efferocytosis, thereby attenuating proinflammatory macrophage activation. FXNK189R mice showed improved macrophage efferocytosis, reduced cardiac inflammation, and suppressed cardiac fibrosis. CONCLUSIONS: The SIRT3-FXN axis has the potential to resolve cardiac inflammation by increasing macrophage efferocytosis and anti-inflammatory activities.
Assuntos
Miócitos Cardíacos , Sirtuína 3 , Animais , Camundongos , c-Mer Tirosina Quinase/genética , Lisina , Sirtuína 3/genética , FrataxinaRESUMO
ABSTRACT Acute retinal pigment epitheliitis (ARPE) is an idiopathic, self-limiting inflammatory retinal disorder that particularly affects healthy young individuals. The characteristic fundoscopic appearance of the acute retinal pigment epitheliitis includes a fine pigment stippling surrounded by a yellow-white hypopigmented halos in the macula. Although the exact pathogenesis of the disease remains unknown, some reports have suggested a relationship between a viral infection and acute retinal pigment epitheliitis. Acute retinal pigment epitheliitis is a rare disorder, and only single case reports or case series are found in the literature. The clinical and demographic characteristics of patients with this disease are not fully understood because of its rarity. In this study, we searched the literature to collect clinical and demographic features of the reported cases. We detail the characteristics of acute retinal pigment epitheliitis were pointed and discuss the pathogenesis of the disease.(AU)
RESUMO A epitelite pigmentar retiniana aguda (EPRA) é uma doença inflamatória idiopática e autolimitada da retina, que afeta especialmente indivíduos jovens e saudáveis. À fundoscopia, a aparência característica dessa entidade é de um pontilhado fino do pigmento, cercado de halos hiperpigmentados branco-amarelados na mácula. A patogênese exata da doença ainda é desconhecida, mas alguns relatos apontam uma relação entre epitelite pigmentar retiniana aguda e infecções virais. A epitelite pigmentar retiniana aguda é uma condição rara e na literatura há apenas relatos de casos individuais ou séries de casos. As características clínicas e demográficas da doença não são totalmente compreendidas, devido à sua raridade. Para este relato, foi feita uma busca na literatura para coletar os dados clínicos e demográficos dos casos relatados. Finalmente, são apontadas as características da epitelite pigmentar retiniana aguda e discute-se a patogênese da doença.(AU)