Qing Xu’s research while affiliated with Capital Medical University and other places

Exposure to PM2.5 is correlated with cardiac remodeling, of which cardiac hypertrophy is one of the main clinical manifestations. Ferroptosis plays an important role in cardiac hypertrophy. However, the potential mechanism of PM2.5-induced cardiac hypertrophy through ferroptosis remains unclear. This study aimed to explore the molecular mechanism of cardiac hypertrophy caused by PM2.5 and the intervention role of MitoQ involved in this process. The results showed that PM2.5 could induce cardiac hypertrophy and dysfunction in mice. Meanwhile, the characteristics of ferroptosis were observed, such as iron homeostasis imbalance, lipid peroxidation, mitochondrial damage and abnormal expression of key molecules. MitoQ treatment could effectively mitigate these alternations. After treating human cardiomyocyte AC16 with PM2.5, ferroptosis activator (Erastin) and inhibitor (Fer-1), it was found that PM2.5 could promote ferritinophagy and lead to lipid peroxidation, mitochondrial dysfunction as well as the accumulation of intracellular and mitochondrial labile iron. Subsequently, mitophagy was activated and provided an additional source of labile iron, enhancing the sensitivity of AC16 cells to ferroptosis. Furthermore, Fer-1 alleviated PM2.5-induced cytotoxicity and iron overload in the cytoplasm and mitochondria of AC16 cells. It was worth noting that during the process of PM2.5 caused ferroptosis, abnormal iron metabolism mediated the activation of ferritinophagy and mitophagy in a temporal order. In addition, NCOA4 knockdown reversed the iron homeostasis imbalance and lipid peroxidation caused by PM2.5, thereby alleviating ferroptosis. In summary, our study found that iron homeostasis imbalance-mediated the crosstalk of ferritinophagy and mitophagy played an important role in PM2.5-induced ferroptosis and cardiac hypertrophy.

Fine particulate matter (PM2.5) exposure has been proved to increase the cardiovascular disease risk. However, there is a lack of comprehensive knowledge on whether a high-fat diet (HFD) affects PM2.5-induced cardiovascular disease. The purpose of this study was to investigate the impairment of lipid metabolism and vascular function by PM2.5 and HFD exposure in ApoE-/- mice. Oil red O staining indicated that co-treatment of PM2.5 and HFD resulted in markedly lipid deposition in the mice aorta. Blood biochemical analysis demonstrated that co-exposure of PM2.5 and HFD could cause dyslipidemia in vivo. Vascular Doppler ultrasound and histopathological analysis found that the functional and structural alterations with fibrosis and calcified remodeling of the vessels were detected after PM2.5 and HFD exposure. For in-depth study, the genome-wide transcriptional analysis performed in macrophages was further revealed that the endoplasmic reticulum stress, immune system process, regulation of cell proliferation etc. were response to PM2.5 exposure; while Lipid and atherosclerosis signaling pathways had a critical role in PM2.5-induced vascular injury. Results from validation experiments manifested that the release of supernatant in PM2.5- or ox-LDL-treated macrophages could decrease the cell viability and increase the lipid ROS in vascular smooth muscle cells (VSMCs). Moreover, the up-regulations of CCL2, IL-6 and IL-1β in aortic arch of mice were observed after co-exposure with PM2.5 and HFD. Our data hinted that PM2.5 could affect the lipid metabolism reprogramming and induce vascular remodeling, accompanied with synergistic effects of HFD.

Background: Exposure to fine particulate matter (PM2.5) is associated with the risk of developing metabolic-associated fatty liver disease (MAFLD). Melatonin is the main secreted product of the pineal gland and has been reported to prevent hepatic lipid metabolism disorders. However, it remains uncertain whether melatonin could protect against PM2.5-induced MAFLD. Methods and results: The purpose of our study was to investigate the mitigating effects of melatonin on hepatic fatty degeneration accelerated by PM2.5 in vivo and in vitro. Histopathological analysis and ultrastructural images showed that PM2.5 induced hepatic steatosis and lipid vacuolation in ApoE-/- mice, which could be effectively alleviated by melatonin administration. Increased ROS production and decreased expression of antioxidant enzymes were detected in the PM2.5-treated group, whereas melatonin showed recovery effects after PM2.5-induced oxidative damage in both the liver and L02 cells. Further investigation revealed that PM2.5 induced oxidative stress to activate PTP1B, which in turn had a positive feedback regulation effect on ROS release. When a PTP1B inhibitor or melatonin was administered, SP1/SREBP-1 signalling was effectively suppressed, while Nrf2/Keap1 signalling was activated in the PM2.5-treated groups. Conclusion: Our study is the first to show that melatonin alleviates the disturbance of PM2.5-triggered hepatic steatosis and liver damage by regulating the ROS-mediated PTP1B and Nrf2 signalling pathways in ApoE-/- mice. These results suggest that melatonin administration might be a prospective therapy for the prevention and treatment of MAFLD associated with air pollution.

Epidemiological studies demonstrate that fine particulate matter (PM2.5) promotes the development of atherosclerosis. However, the mechanism insight of PM2.5-induced atherosclerosis is still lacking. The aim of this study was to explore the biological effects of hypoxia-inducible factor 1α (HIF-1α) on PM2.5-triggered atherosclerosis. The vascular stiffness, carotid intima-media thickness (CIMT), lipid and atherosclerotic lesion were increased when von Hippel-Lindau (VHL)-null mice were exposed to PM2.5. Yet, knockout of HIF-1α markedly decreased the PM2.5-triggered atherosclerotic lesion. We firstly performed microarray analysis in PM2.5-treated bone morrow-derived macrophages (BMDMs), which showed that PM2.5 significantly changed the genes expression patterns and affected biological processes such as phagocytosis, apoptotic cell clearance, cellular response to hypoxia, apoptotic process and inflammatory response. Moreover, the data showed knockout of HIF-1α remarkably relieved PM2.5-induced defective efferocytosis. Mechanistically, PM2.5 inhibited the level of genes and proteins of efferocytosis receptor c-Mer tyrosine kinase (MerTK), especially in VHL-null BMDMs. In addition, PM2.5 increased the genes and proteins of a disintegrin and metallopeptidase domain 17 (ADAM17), which caused the MerTK cleavage to form soluble MerTK (sMer) in plasma and cellular supernatant. The sMer was significantly up-regulated in plasma of VHL-null PM2.5-exposed mice. Moreover, PM2.5 could induce defective efferocytosis and activate inflammatory response through MerTK/IFNAR1/STAT1 signaling pathway in macrophages. Our results demonstrate that PM2.5 could induce defective efferocytosis and inflammation by activating HIF-1α in macrophages, ultimately resulting in accelerating atherosclerotic lesion formation and development. Our data suggest HIF-1α in macrophages might be a potential target for PM2.5-related atherosclerosis.

It is reported that oxidative stress homeostasis was involved in PM2.5-induced foam cell formation and progression of atherosclerosis, but the exact molecular mechanism is still unclear. Melatonin is an effective antioxidant that could reverse the cardiopulmonary injury. The main purpose of this study is to investigate the latent mechanism of PM2.5-triggered atherosclerosis development and the protective role of melatonin administration. Vascular Doppler ultrasound showed that PM2.5 exposure reduced aortic elasticity in ApoE−/- mice. Meanwhile, blood biochemical and pathological analysis demonstrated that PM2.5 exposure caused dyslipidemia, elicited oxidative damage of aorta and was accompanied by an increase in atherosclerotic plaque area; while the melatonin administration could effectively alleviate PM2.5-induced macrophage M1 polarization and atherosclerosis in mice. Further investigation verified that NADPH oxidase 2 (NOX2) and mitochondria are two prominent sources of PM2.5-induced ROS production in vascular macrophages. Whereas, the combined use of two ROS-specific inhibitors and adopted with melatonin markedly rescued PM2.5-triggered macrophage M1 polarization and foam cell formation by inhibiting NOX2-mediated crosstalk of Keap1/Nrf2/NF-κB and TLR4/TRAF6/NF-κB signaling pathways. Our results demonstrated that NOX2-mediated oxidative stress homeostasis is critical for PM2.5-induced atherosclerosis and melatonin might be a potential treatment for air pollution-related cardiovascular diseases.

Ambient fine particulate matter (PM2.5) and high-fat diet (HFD) are linked to the development of atherosclerosis. However, there is still unknown about the PM2.5-induced atherosclerosis formation on vascular endothelial injury after co-exposed to PM2.5 and HFD. Thus, the aim of this study was to evaluate the effects of PM2.5 on atherogenesis in C57BL/6 mice and endothelial cells, as well as the co-exposure effect of PM2.5 and HFD. In vivo study, C57BL/6 mice exposed to PM2.5 and fed with standard chow diet (STD) or HFD for 1 month. PM2.5 could increase vascular stiffness accessed by Doppler ultrasound, and more serious in co-exposure group. PM2.5 impaired vascular endothelial layer integrity, exfoliated endothelial cells, and inflammatory cells infiltration through H&E staining. PM2.5 reduced the expression of platelet/endothelial cell adhesion molecule-1 (PECAM-1) in vessel. Moreover, PM2.5 could induce systemic inflammation detected by Mouse Inflammation Array. In vitro study, PM2.5 triggered markedly mitochondrial damage by transmission electron microscope (TEM) and flow cytometer. Inflammatory cytokines were significantly increased in PM2.5-exposed group. The cell viability and migration of endothelial cells were significantly suppressed. In addition, PM2.5 remarkably declined the expression of vascular endothelial growth factor receptor 2 (VEGFR2) and increased the expression of somatostatin (SST) and its receptor. In conclusion, co-exposure of PM2.5 and HFD might induce systemic inflammation and endothelial dysfunction in normal mice. Moreover, PM2.5 could reduce vascular endothelial repair capacity through inhibiting the proliferation and migration of endothelial cells.

Short-term PM2.5 exposure is related to vascular remodeling and stiffness. Mitochondria-targeted antioxidant MitoQ is reported to improve the occurrence and development of mitochondrial redox-related diseases. At present, there is limited data on whether MitoQ can alleviate the vascular damage caused by PM2.5. Therefore, the current study was aimed to evaluate the protective role of MitoQ on aortic fibrosis induced by PM2.5 exposure. Vascular Doppler ultrasound manifested PM2.5 damaged both vascular function and structure in C57BL/6J mice. Histopathological analysis found that PM2.5 induced aortic fibrosis and disordered elastic fibers, accompanied by collagen I/III deposition and synthetic phenotype remodeling of vascular smooth muscle cells; while these alterations were partially alleviated following MitoQ treatment. We further demonstrated that mitochondrial dysfunction, including mitochondrial reactive oxygen species (ROS) overproduction and activated superoxide dismutase 2 (SOD2) expression, decreased mitochondrial membrane potential (MMP), oxygen consumption rate (OCR), ATP and increased intracellular Ca²⁺, as well as mitochondrial fragmentation caused by increased Drp1 expression and decreased Mfn2 expression, occurred in PM2.5-exposed aorta or human aortic vascular smooth muscle cells (HAVSMCs), which were reversed by MitoQ. Moreover, the enhanced expressions of LC3II/I, p62, PINK1 and Parkin regulated mitophagy in PM2.5-exposed aorta and HAVSMCs were weakened by MitoQ. Transfection with PINK1 siRNA in PM2.5-exposed HAVSMCs further improved the effects of MitoQ on HAVSMCs synthetic phenotype remodeling, mitochondrial fragmentation and mitophagy. In summary, our data demonstrated that MitoQ treatment had a protective role in aortic fibrosis after PM2.5 exposure through mitochondrial quality control, which regulated by mitochondrial ROS/PINK1/Parkin-mediated mitophagy. Our study provides a possible targeted therapy for PM2.5-induced arterial stiffness.

Fine particulate matter (PM2.5) exposure is correlated with the risk of developing cardiac fibrosis. Melatonin is a major secretory product of the pineal gland that has been reported to prevent fibrosis. However, whether melatonin affects the adverse health effects of PM2.5 exposure has not been investigated. Thus, this study was aimed to investigate the protective effect of melatonin against PM2.5‐accelerated cardiac fibrosis. The echocardiography revealed that PM2.5 had impaired both systolic and diastolic cardiac function in ApoE‐/‐ mice. Histopathological analysis demonstrated that PM2.5 induced cardiomyocyte hypertrophy and fibrosis, particularly perivascular fibrosis. While the melatonin administration was effective in alleviating PM2.5‐induced cardiac dysfunction and fibrosis in mice. Results of electron microscopy and confocal scanning laser microscope confirmed that melatonin had restorative effects against impaired mitochondrial ultrastructure and augmented mitochondrial ROS generation in PM2.5‐treated group. Further investigation revealed melatonin administration could significantly reverse the PM2.5‐induced phenotypic modulation of cardiac fibroblasts into myofibroblasts. For the first time, our study found that melatonin effectively alleviates PM2.5‐induced cardiac dysfunction and fibrosis via inhibiting mitochondrial oxidative injury and regulating SIRT3‐mediated SOD2 deacetylation. Our findings indicate that melatonin could be a therapy medicine for prevention and treatment of air pollution associated cardiac diseases.