Background Cerebral ischemia-reperfusion injury (CIRI) refers to a secondary brain injury that can occur when the blood supply to the ischemic brain tissue is restored. However, the mechanism underlying such injury remains elusive. Methods The 150 male C57 mice underwent middle cerebral artery occlusion (MCAO) for 1 h and reperfusion for 24 h, Among them, 50 MCAO mice were further treated with Mitochondrial division inhibitor 1 (Mdivi-1) and 50 MCAO mice were further treated with N-acetylcysteine (NAC). SH-SY5Y cells were cultured in a low-glucose culture medium for 4 h under hypoxic conditions and then transferred to normal conditions for 12 h. Then, cerebral blood flow, mitochondrial structure, mitochondrial DNA (mtDNA) copy number, intracellular and mitochondrial reactive oxygen species (ROS), autophagic flux, aggresome and exosome expression profiles, cardiac tissue structure, mitochondrial length and cristae density, mtDNA and ROS content, as well as the expression of Drp1-Ser616/Drp1, RIP1/RIP3, LC3 II/LC3 I, TNF-α, IL-1β, etc., were detected under normal or Drp1 interference conditions. Results The mtDNA content, ROS levels, and Drp1-Ser616/Drp1 were elevated by 2.2, 1.7 and 2.7 times after CIRI (P < 0.05). However, the high cytoplasmic LC3 II/I ratio and increased aggregation of p62 could be reversed by 44% and 88% by Drp1 short hairpin RNA (shRNA) (P < 0.05). The low fluorescence intensity of autophagic flux and the increased phosphorylation of RIP3 induced by CIRI could be attenuated by ROS scavenger, NAC (P < 0.05). RIP1/RIP3 inhibitor Necrostatin-1 (Nec-1) restored 75% to a low LC3 II/LC3 I ratio and enhanced 2 times to a high RFP-LC3 after Drp1 activation (P < 0.05). In addition, although CIRI-induced ROS production caused no considerable accumulation of autophagosomes (P > 0.05), it increased the packaging and extracellular secretion of exosomes containing p62 by 4 – 5 times, which could be decreased by Mdivi-1, Drp1 shRNA, and Nec-1 (P < 0.05). Furthermore, TNF-α and IL-1β increased in CIRI-derived exosomes could increase RIP3 phosphorylation in normal or oxygen–glucose deprivation/reoxygenation (OGD/R) conditions (P < 0.05). Conclusions CIRI activated Drp1 and accelerated the p62-mediated formation of autophagosomes while inhibiting the transition of autophagosomes to autolysosomes via the RIP1/RIP3 pathway activation. Undegraded autophagosomes were secreted extracellularly in the form of exosomes, leading to inflammatory cascades that further damaged mitochondria, resulting in excessive ROS generation and the blockage of autophagosome degradation, triggering a vicious cycle.

Objective. This study is aimed at identifying the potential diagnostic markers for circulating endothelial cells (CECs) for acute myocardial ischemia (AMI) and exploring the regulatory mechanisms of the selected biomarker in mitochondrial oxidative damage and vascular inflammation in AMI pathology. Methods. Utilizing the Gene Expression Omnibus dataset GSE66360, we scanned for differentially expressed genes (DEGs) in 49 AMI patients and 50 healthy subjects. To discover possible biomarkers, LASSO regression and support vector machine recursive feature elimination examinations were conducted. Using the GSE60993 and GSE123342 datasets and AMI rat models, the expression levels and diagnostic accuracy of the biomarkers in AMI were thoroughly verified. CIBERSORT was employed to evaluate the compositional patterns of 22 distinct immunological cell percentages in AMI according to combined cohorts. The oxidative-damaged mitochondria were detected by confocal microscopy observation of MitoTracker, ROS-DCFH-DA, and mCherry-GFP-LC3B. Results. In total, 122 genes were identified. The identified DEGs primarily contributed in arteriosclerosis, arteriosclerotic cardiovascular disorders, bacterial infectious disorder, coronary artery disease, and myocardial infarction. Nine features (NR4A2, GABARAPL1 (GEC1), CLEC4D, ITLN1, SNORD89, ZFP36, CH25H, CCR2, and EFEMP1) of the DEGs were shared by two algorithms, and GABARAPL1 (GEC1) was identified and verified as a diagnostic mitochondrial biomarker for AMI. Confocal results showed that there existed mitochondrial damage and oxidative stress in cardiac CMECs after AMI, and the blocked autophagy flux could be released by exosome burst in cardiac CMECs and blood CECs. Immune cell infiltration testing declared that elevated GEC1 expression in blood CECs was linked to the rise of monocytes and neutrophils. Functional tests revealed that high GEC1 expression in CMECs and CECs could activate the vascular inflammatory response by stimulating NLRP3 inflammasome production after AMI. Conclusion. Oxidative-damaged mitochondria in cardiac CMECs activate GEC1-mediated autophagosomes but block autophagy flux after AMI. The exfoliated cardiac CMECs evolve into abnormal blood CECs, and the undegraded GEC1 autophagosomes produce a large number of NLRP3 inflammasomes by exosome burst, stimulating the increase in monocytes and neutrophils and ultimately triggering vascular inflammation after AMI. Therefore, GEC1 in blood CECs is a highly specific diagnostic mitochondrial biomarker for AMI.

Mitochondria get caught in the crossfire of coronavirus disease 2019 (COVID-19) and antiviral immunity. The mitochondria-mediated antiviral immunity represents the host’s first line of defense against viral infection, and the mitochondria are important targets of COVID-19. However, the specific manifestations of mitochondrial damage in patients with COVID-19 have not been systematically clarified. This study comprehensively analyzed one single-cell RNA-sequencing dataset of lung tissue and two bulk RNA-sequencing datasets of blood from COVID-19 patients. We found significant changes in mitochondrion-related gene expression, mitochondrial functions, and related metabolic pathways in patients with COVID-19. SARS-CoV-2 first infected the host alveolar epithelial cells, which may have induced excessive mitochondrial fission, inhibited mitochondrial degradation, and destroyed the mitochondrial calcium uniporter (MCU). The type II alveolar epithelial cell count decreased and the transformation from type II to type I alveolar epithelial cells was blocked, which exacerbated viral immune escape and replication in COVID-19 patients. Subsequently, alveolar macrophages phagocytized the infected alveolar epithelial cells, which decreased mitochondrial respiratory capacity and activated the ROS–HIF1A pathway in macrophages, thereby aggravating the pro-inflammatory reaction in the lungs. Infected macrophages released large amounts of interferon into the blood, activating mitochondrial IFI27 expression and destroying energy metabolism in immune cells. The plasma differentiation of B cells and lung-blood interaction of regulatory T cells (Tregs) was exacerbated, resulting in a cytokine storm and excessive inflammation. Thus, our findings systematically explain immune escape and excessive inflammation seen during COVID-19 from the perspective of mitochondrial quality imbalance.

Septic cardiomyopathy (SCM) is associated with an imbalance in mitochondrial quality and high mortality rates, and an effective treatment has not been developed to date. Curcumin provides antioxidant, anti-inflammatory, cardiovascular, and mitochondrial protection. However, it has not been confirmed to improve cardiac dysfunction in sepsis and reduce abnormal inflammatory responses by improving mitochondrial function. Herein, we explore novel mechanisms by which curcumin improves SCM using an in vivo male C57BL/6 mice sepsis model and in vitro HL-1 cells stimulated with lipopolysaccharide. Curcumin’s effects on sepsis-induced cardiac dysfunction, inflammatory responses, and mitochondrial quality of cardiac cells were observed using qPCR, western blotting, echocardiography, and transmission electron microscopy. Curcumin-activated sirtuin 1 (SIRT1) increased the expression of mitochondrial biogenesis-related genes PGC-1α, TFAM, and Nrf2, reduced dynamin-related protein 1 (Drp1) translocation from the cytoplasm to mitochondria, and restored the mitochondrial morphology and function in cardiac cells, thus protecting heart function after septic shock and alleviating the effects of SCM. SIRT1 knockdown reversed the protective effects of curcumin on mitochondria. Curcumin promotes mitochondrial biogenesis and inhibits mitochondrial fragmentation by activating SIRT1, thereby improving the mitochondrial quality and reducing oxidative stress in cardiomyocytes and sepsis-induced cardiac dysfunction. These findings provide new evidence supporting the use of curcumin to treat SCM.