Autophagy in Vascular Disease

A Novel Function of NaV Channel β3 Subunit in Endothelial Cell Alignment Through Autophagy Modulation

Endothelial cells (EC) play a pivotal role in vascular homeostasis. By sensing shear stress generated by blood flow, EC endorse vasculoprotection through mechanotransduction signaling pathways. Various ion channels are involved in mechanosignaling, and here, we investigated the endothelial voltage-gated Na+ channels (NaV channels), since their mechanosensitivity has been previously demonstrated in cardiomyocytes. First, we showed that EC from aorta (TeloHAEC) behave as EC from umbilical vein (HUVEC) under laminar shear stress (LSS). For both EC models, cell alignment and elongation occurred with the activation of the KLF2/KLF4 atheroprotective signaling pathways. We found that LSS decreased the expression of SCN5A, encoding NaV1.5, while LSS increased that of SCN3B, encoding NaVβ3. We demonstrated that the KLF4 transcription factor is involved in SCN3B expression under both static and LSS conditions. Interestingly, SCN3B silencing impaired EC alignment induced by LSS. The characterization of NaVβ3 interactome by coimmunoprecipitation and proteomic analysis revealed that mTOR, implicated in autophagy, binds to NaVβ3. This result was evidenced by the colocalization between NaVβ3 and mTOR inside cells. Moreover, we showed that SCN3B silencing led to the decrease in LC3B expression and the number of LC3B positive autophagosomes. Furthermore, we showed that NaVβ3 is retained within the cell and colocalized with LAMP1 and LC3B. Finally, we found that resveratrol, a stimulating-autophagy and vasculoprotective molecule, induced KLF4 together with NaVβ3 expression. Altogether, our findings highlight a novel role of NaVβ3 in endothelial function and cell alignment as an actor in shear stress vasculoprotective intracellular pathway through autophagy modulation.

Hypoxia impairs autophagy of cardiomyocytes via p38/MAPK/MAP4 pathway

BACKGROUND

Myocardial hypoxia occurs in severe burns and may cause severe cardiac dysfunction, in which the blockage of the autophagy flux plays an important role. Previous studies indicates that the p38/MAPK pathway is involved in regulating the microtubule structure by regulating MAP4 phosphorylation, and the microtubule structure affects the autophagy. However, as a complex degradation process, how autophagy is specifically affected by microtubules remains unknown. An in-depth understanding of hypoxia-related autophagy disorders is critical for the treatment of myocardial injury.

METHODS

Cardiomyocytes (CMs) were isolated from the ventricles of neonatal Sprague-Dawley rats and cultured in an incubator filled with 1 % O2, 5 % CO2, and 94 % N2. SB203580 and MKK6 (Glu) recombinant adenovirus were used to specifically inhibit and activate the p38/MAPK pathway, respectively. The adeno-associated viruses (AAVs) encoding MAP4 gene and MAP4 siRNA were used to up-regulate and down-regulate the expression of MAP4, respectively. After infection of cells with AAV encoding GFP-LC3 fusion proteins, the number of green spots under fluorescence microscopy shows the quantity of autophagosomes. Western blots access the expression of LC3-II, LC3-I and p62. The ratio of LC3-II to LC3-I (LC3-II/I) tells the quantity of autophagosomes, and the expression of p62 indicates the extent of autophagosome degradation. Cell Counting Kit 8 was used to detect cell viability. Rapamycin was used to recover the autophagy.

RESULTS

Hypoxia reduced the viability of cardiomyocytes, in which the quantity of autophagosomes is increased, while the degradation is reduced, and the p38/MAPK pathway is activated. Activation of the p38/MAPK pathway could block the autophagy pathway. The phosphorylation of MAP4 did not affect the quantity of autophagosomes, but hindered its degradation. The p38/MAPK pathway could regulate the phosphorylation of MAP4. Finally, when the autophagy pathway was restored, cell viability has partially recovered.

CONCLUSIONS

Hypoxia regulates the phosphorylation of MAP4 through the p38/MAPK pathway, thereby hindering the degradation of autophagosomes, rather than the quantity, blocking autophagic flux and ultimately affecting cell viability.

Oscillatory shear stress activates integrin β3, blocking autophagic flux in endothelial cells and promoting endothelial cells senescence

Atherosclerosis is an age-related cardiovascular disease. The intersections and bends of blood vessels under the direct action of oscillatory shear stress (OSS) are susceptible to atherosclerotic plaque formation, and the expression of age-related factors is significantly increased in plaques. However, the molecular mechanism by which OSS promotes vascular senescence is still unclear. In this study, we found that the expression of age-related factors, such as P16 and P21, was increased in human aortic endothelial cells (HAECs) exposed to OSS. We also found that the expression of autophagy-related gene 5 (ATG5), microtubule-associated protein 1 light chain 3β (MAP1LC3B), and beclin 1 (BECN1) was increased in HAECs exposed to OSS. The expression of sequestosome-1 (SQSTM1/P62) was also increased. Immunofluorescence confirmed that OSS impaired autophagic flux in HAECs by inhibiting the binding of autophagosomes to lysosome, thereby promoting endothelial cell (EC) senescence. The OSS-sensitive gene integrin β3 (ITGB3), which is closely related to EC autophagy and senescence, was screened by proteomics analysis of HAECs in the control and OSS-treated groups. The protein and mRNA expression of ITGB3 was significantly increased in HAECs exposed to OSS. ITGB3 overexpression in HAECs significantly affected the autophagic flux of ECs and promoted EC senescence, resulting in an increase in cells in the G0/G1 phase and cell cycle arrest. ITGB3 knockdown significantly inhibited the block of OSS-induced autophagic flux and senescence in ECs. In addition, in vivo studies showed that treatment with the ITGB3 inhibitor Cyclo(arginine-glycine-aspartate-tyrosine-lysine) [Cyclo(RGDyK)] significantly inhibited high-fat diet-induced plaque formation in the aortae of apolipoprotein E (ApoE)-/- mice. In conclusion, OSS blocks HAECs autophagic flux and promotes senescence via ITGB3 activation, thereby affecting the development of atherosclerosis.

Identification and Verification of the Driver Genes for the Formation and Development of Intracranial Aneurysms

BACKGROUND

Research on driver genes that can be used to diagnose and control the formation and development of intracranial aneurysms (IAs) is still limited, and bioinformatics and machine learning approaches are implemented in the study in an aim to identify and validate them.

METHODS

By applying datasets from the Gene Expression Omnibus database for human cerebrovascular tissue, 47 cases of ruptured IA, 71 cases of ruptured IA, and 64 cases of normal control intracranial vessels were analyzed. Apply bioinformatics and machine learning methods to screen for the driver genes that contribute to the occurrence and development of IAs. Construct animal models to verify them.

RESULTS

STX17 was identified as a key driver gene for the occurrence and development of IAs (AUC: 0.724). The animal model of IA was successfully constructed. Immunohistochemistry: The average optical density values of vascular smooth muscle and STX17 antibodies in the model group were significantly decreased compared with those in the normal group (P < 0.001). reverse transcription - polymerase chain reaction: The mRNA expression level of the STX17 gene in the model group was significantly lower than that in the normal group (P < 0.001). Western blot: The protein expression level of the STX17 gene in the model group was significantly decreased compared with that in the normal group (P < 0.001).

CONCLUSIONS

STX17-mediated changes in the smooth muscle cell phenotype are new driver genes for IA formation and progression, providing a new approach for the early screening, diagnosis, and treatment of IA.

Insight into the Mechanistic role of Colchicine in Atherosclerosis

PURPOSE OF REVIEW

Globally, the prevalence of atherosclerosis (AS) is rising. Currently, there is no specific drug for AS. Therefore, this review aims to discuss the protective mechanisms of colchicine against the development and progression of atherosclerosis (AS).

RECENT FINDINGS

Many studies highlighted that the anti-inflammatory drug colchicine reduces the severity of AS, although the underlying mechanism for the beneficial effect of colchicine was not fully clarified. AS is a chronic progressive vascular disorder characterized by the formation of atherosclerotic plaques. Endothelial dysfunction is an initial stage in the pathogenesis of AS that is induced by oxidized low-density lipoprotein (oxLDL). Engulfment of oxLDL by macrophages triggers the development of inflammation due to the release of pro-inflammatory cytokines and growth factors. Inflammatory and adhesion molecules are involved in the pathogenesis of AS. Infiltration and accumulation of leukocytes provoke erosion, rupture, and thrombosis of the atherosclerotic plaque. Therefore, targeting inflammation and leukocyte infiltration by anti-inflammatory agents may reduce AS progression and complications. The anti-inflammatory drug colchicine reduces the severity of AS, although the underlying mechanism for the beneficial effect of colchicine was not fully elucidated.

IN CONCLUSION

colchicine through inhibition of vascular inflammation, oxidative stress, platelet aggregation and the modulation of autophagy reduces the development and progression of AS.

Lysosomes in the immunometabolic reprogramming of immune cells in atherosclerosis

Lysosomes have a central role in the disposal of extracellular and intracellular cargo and also function as metabolic sensors and signalling platforms in the immunometabolic reprogramming of macrophages and other immune cells in atherosclerosis. Lysosomes can rapidly sense the presence of nutrients within immune cells, thereby switching from catabolism of extracellular material to the recycling of intracellular cargo. Such a fine-tuned degradative response supports the generation of metabolic building blocks through effectors such as mTORC1 or TFEB. By coupling nutrients to downstream signalling and metabolism, lysosomes serve as a crucial hub for cellular function in innate and adaptive immune cells. Lysosomal dysfunction is now recognized to be a hallmark of atherogenesis. Perturbations in nutrient-sensing and signalling have profound effects on the capacity of immune cells to handle cholesterol, perform phagocytosis and efferocytosis, and limit the activation of the inflammasome and other inflammatory pathways. Strategies to improve lysosomal function hold promise as novel modulators of the immunoinflammatory response associated with atherosclerosis. In this Review, we describe the crosstalk between lysosomal biology and immune cell function and polarization, with a particular focus on cellular immunometabolic reprogramming in the context of atherosclerosis.

Circulating autophagy regulator Rubicon is linked to increased myocardial infarction risk

Background

The identification of new biomarkers that improve existing cardiovascular risk prediction models for acute coronary syndrome is essential for accurately identifying high-risk patients and refining treatment strategies. Autophagy, a vital cellular degradation mechanism, is important for maintaining cardiac health. Dysregulation of autophagy has been described in cardiovascular conditions such as myocardial ischemia-reperfusion injury, a key factor in myocardial infarction (MI). Recently, Rubicon (Run domain Beclin-1-interacting and cysteine-rich domain-containing protein), a key negative regulator of autophagy, has been identified in the modulation of cardiac stress response.

Objectives

This study aimed to explore the relationship between circulating Rubicon levels and MI, and to evaluate the incremental predictive value of Rubicon when integrated into a clinical risk prediction model for MI.

Results

We analyzed plasma Rubicon concentrations in 177 participants, comprising type I MI patients and high-risk control subjects. Our results revealed significantly elevated plasma Rubicon levels in MI patients compared to the control group (126.5 pg/mL vs. 53 pg/mL, p < 0.001). Furthermore, Rubicon levels showed a positive correlation with cardiovascular risk factors such as total cholesterol and LDL cholesterol. Multivariate analysis confirmed that Rubicon levels were independently associated with an increased risk of MI. The inclusion of Rubicon in traditional cardiovascular risk models notably enhanced predictive accuracy for MI, with the area under the curve (AUC) rising from 0.868 to 0.905 (p < 0.001).

Conclusions

These findings suggest that Rubicon is a valuable biomarker associated with MI risk, providing additional predictive value beyond standard cardiovascular risk factors. This highlights the importance of Rubicon's critical role in the pathophysiology of CVD.

Natural Polyamine Spermidine Inhibits the In Vitro Oxidation of LDL

Spermidine is a natural autophagy-inducer and anti-aging compound. Herein, we investigated a potential autophagy-independent mechanism of spermidine, namely its capability to directly impede LDL oxidation, an early step in atherogenesis. In our in vitro-model, LDL oxidation was induced by the addition of CuCl2 in the presence of increasing concentrations of spermidine, and the degree of oxidation of the lipid, as well as of the protein part of LDL, was measured. We found that spermidine concentration-dependently inhibited the production of lipid hydroperoxides, malondialdehyde, and oxidation-specific immune epitopes in the LDL particle, associated with decreased relative electrophoretic mobilities, respectively. For example, the LPO content was significantly lower when LDL was oxidized in the presence of 500 µg/mL spermidine (26.9 ± 1.6 nmol/mg LDL) than in the absence of spermidine (180.6 ± 7.7 nmol/mg LDL, p < 0.0001). When oxLDL was obtained under increasing spermidine concentrations, its cytotoxicity in EA.hy926 cells concentration-dependently decreased. Quantum chemical calculations show that the reaction between spermidine and hydroxyl radicals is exergonic. We conclude that spermidine is a direct inhibitor of LDL oxidation due to its capability to scavenge hydroxyl radicals. Thus, spermidine supplementation might be a suitable tool to impede atherogenesis and associated (cardio)vascular diseases. Further prospective clinical studies are needed to evaluate the potential atheroprotective/health-promoting effects of spermidine-rich diets.

GYY4137 ameliorates blood brain barrier damage by inhibiting autophagy mediated occludin degradation in cardiac arrest and resuscitation

Cardiopulmonary resuscitation (CPR) after cardiac arrest (CA) is an important cause of neurological impairment and leads to considerable morbidity and mortality. The stability of the blood-brain barrier (BBB) is crucial for minimizing secondary neurological damage and improving long-term prognosis. However, the precise mechanisms and regulatory pathways that contribute to BBB dysfunction after CPR remain elusive. GYY4137 is an innovative hydrogen sulfide slow-release agent with excellent properties as a hydrogen sulfide substitute. The aim of this study was to investigate the protective effects of GYY4137 on CA/CPR and the underlying mechanisms of BBB protection. The effects of GYY4137 on systemic inflammation, BBB integrity, and autophagy were evaluated using a mouse CA/CPR model. The underlying mechanisms of occludin changes associated with GYY4137 were investigated using oxygen-glucose deprivation / reoxygenation (OGD/R) model. ELISA, neurological function and other tests showed that GYY4137 ameliorates systemic inflammation and neurological prognosis. Western blotting, transwell migration and tube formation assays showed that GYY4137 improves BBB function both in vivo and in vitro. The detection of autophagy flow and protein degradation pathways showed the inhibition of occludin reduction by GYY4137 was mainly achieved by suppressing autophagy mediated degradation. Taken together, GYY4137 may improve BBB dysfunction following CPR by increasing occludin content. This effect was achieved by inhibiting autophagic degradation rather than promoting synthesis. GYY4137 also mitigated systemic inflammation and improved neurological outcomes after CA/CPR. In summary, our study provides valuable insights into protecting the integrity of BBB and improving neurological outcomes after CPR.

Dapagliflozin improves the dysfunction of human umbilical vein endothelial cells (HUVECs) by downregulating high glucose/high fat-induced autophagy through inhibiting SGLT-2

OBJECTIVE

To investigate the effect of Dapagliflozin (Da) on the disorders of human umbilical vein endothelial cells (HUVECs) induced by high glucose and high fat (HG/HF).

METHODS

Immunohistochemistry and immunofluorescence were used to detect the SGLT-2 expression in thoracic aortic tissues. After transfected with overexpressed plasmid SLC5A2, autophagy and cell functions of HUVECs were detected with the treatment of autophagy inhibitor 3-MA (5 mM). HUVECs were exposed to mannitol (MAN), glucose/palmitate (Hg/PA), and Hg/PA/Da for 24 h, and the proliferation of HUVECs was detected by CCK-8. The protein expression levels, endothelial cell functions (cell proliferation, migration, tubular formation, apoptosis, and autophagy) in endothelial cells were evaluated.

RESULTS

The SGLT-2 expression was found in atherosclerotic human thoracic aorta tissues and HG/PA induced HUVECs (P < 0.05). After the overexpression of SGLT-2 in HUVECs, the proliferation, migration and tubule formation ability of HUVECs were inhibited, and autophagy and apoptosis were increased, which were reversed by 3-MA (P < 0.05). After the addition of Sodium-glucose co-transporters 2 inhibitor, Dapagliflozin, the proliferation of HUVECs, the tubule formation, autophagy, apoptosis and migration ability of cells inhibited by HG/PA were significantly improved (P < 0.05). Moreover, the increased protein expression levels of autophagy and apoptosis in HG/PA induced HUVECs were also decreased by the treatment of Dapagliflozin (P < 0.05).

CONCLUSIONS

Dapagliflozin can improve the dysfunction of high glucose/high fat-induced human umbilical vein endothelial cells by downregulate autophagy through inhibiting SGLT-2.

Columbianadin Ameliorates Myocardial Injury by Inhibiting Autophagy Through the PI3K/Akt/mTOR Signaling Pathway in AMI Mice and Hypoxic H9c2 Cells

Acute myocardial infarction (AMI) is a leading cause of mortality among cardiovascular diseases, yet effective therapies for AMI are limited. Previous studies have suggested cardioprotective effects of columbianadin (CBN), but its specific role in AMI and the underlying mechanisms remain unclear. This study aims to investigate whether CBN influences AMI and to elucidate the underlying mechanisms. We conducted a network pharmacology analysis to investigate the relationship between CBN and AMI. The AMI model was established by ligating the left anterior descending (LAD) artery in C57BL/6J mice, which were subsequently administered CBN. Hypoxic H9c2 cells were utilized to evaluate the effects of CBN in vitro. Our study revealed that CBN treatment significantly reduced myocardial infarction in AMI mice. It enhanced mitochondrial function and suppressed autophagy flux in hypoxic H9c2 cells. Furthermore, CBN downregulated the expression of LC3, Beclin1, and Atg 5 genes and proteins. In response to CBN treatment, the phosphorylation levels of PI3K, Akt, and mTOR increased. Notably, RAPA attenuated the protective effect of CBN in enhancing the survival of hypoxic H9c2 cells and abolished its regulation of autophagy-related proteins via the PI3K/Akt/mTOR signaling pathway. In conclusion, CBN reduces myocardial damage by suppressing autophagy via the PI3K/Akt/mTOR signaling pathway in AMI mice and hypoxic H9c2 cells.

PCSK9 promotes vascular neointimal hyperplasia through non-lipid regulation of vascular smooth muscle cell proliferation, migration, and autophagy

We aim to explore the impact of Proprotein convertase subtilisin-kexin type 9 (PCSK9) and its inhibitor evolocumab on neointimal hyperplasia. Wild type and PCSK9 knockout (PCSK9-/-) mice were subjected to ligation of the common carotid artery, with or without subcutaneous injection of evolocumab. Mouse aortic vascular smooth muscle (MOVAS) cells were pretreated with evolocumab or under siRNA-mediated suppression of PCSK9, and then exposed to platelet-derived growth factor type BB(PDGF-BB), a major promoter of MOVAS transformation to a proliferative phenotype. PCSK9 was upregulated in ligated carotid arteries and PDGF-BB-treated MOVAS cells. PCSK9-/- mice showed decreased intimal area and intimal/media area ratio, downregulation of proliferation and autophagy, which was coincidence with wild-type mice treated with evolocumab. In MOVAS cells fortified with evolocumab or silencing of PCSK9, PCNA, Beclin1, p62, LC3 were downregulated, additionally, EdU-positive cells decreased, cell viability reduced, migration ability was weakened, and the number of autophagosomes and autolysosomes decreased after the treatment. We also identified the PI3K/AKT/mTOR signaling molecules as potential PCSK9 targets mediating proliferative effect in MOVAS cells. To sum up, our results suggest that PCSK9 has intrinsic properties to promote proliferation, migration and autophagy in VSMCs independent of its lipid-regulating role. The proliferative effects of PCSK9 may be mediated by the PI3K/AKT/mTOR signaling pathway. These data provide additional evidence for PCSK9i in cardiovascular disease beyond the low-density lipoprotein (LDL)-lowering benefit.

Amino Acid Metabolism and Autophagy in Atherosclerotic Cardiovascular Disease

Cardiovascular disease is the most common cause of mortality globally, accounting for approximately one out of three deaths. The main underlying pathology is atherosclerosis, a dyslipidemia-driven, chronic inflammatory disease. The interplay between immune cells and non-immune cells is of great importance in the complex process of atherogenesis. During atheroprogression, intracellular metabolic pathways, such as amino acid metabolism, are master switches of immune cell function. Autophagy, an important stress survival mechanism involved in maintaining (immune) cell homeostasis, is crucial during the development of atherosclerosis and is strongly regulated by the availability of amino acids. In this review, we focus on the interplay between amino acids, especially L-leucine, L-arginine, and L-glutamine, and autophagy during atherosclerosis development and progression, highlighting potential therapeutic perspectives.

Vasicine attenuates atherosclerosis via lipid regulation, inflammation inhibition, and autophagy activation in ApoE-/- mice

Atherosclerosis is marked with the accumulation of low-density lipoproteins and chronic inflammation. The anti-inflammatory therapies exert protective effects on atherosclerosis. Vasicine is a bioactive alkaloid with anti-inflammatory activity from a medicinal plant in Ayurveda and Unani. In this study, the effects of vasicine were evaluated on atherosclerosis in vivo and in vitro. The results showed that vasicine alleviated atherosclerotic lesions and regulated the lipid synthesis by reducing the levels of TC, TG, LDL-C and inhibiting the expresses of scavenger receptors (SR-A, CD36 and LOX-1) to inhibit foam cell formations. And vasicine decreased the levels of IL-1β, IL-6, MCP-1, and TNF-α to modulate inflammatory response. Besides, vasicine downregulated MAPK and PI3K/AKT/mTOR pathway to activated autophagy, which inhibited the procession of atherosclerosis.

Emerging role of IRE1α in vascular diseases

A mounting body of evidence suggests that the endoplasmic reticulum stress and the unfolded protein response are involved in the underlying mechanisms responsible for vascular diseases. Inositol-requiring protein 1α (IRE1α), the most ancient branch among the UPR-related signaling pathways, can possess both serine/threonine kinase and endoribonuclease (RNase) activity and can perform physiological and pathological functions. The IRE1α-signaling pathway plays a critical role in the pathology of various vascular diseases. In this review, we provide a general overview of the physiological function of IRE1α and its pathophysiological role in vascular diseases.

Role of ROS and autophagy in the pathological process of atherosclerosis

Activation of autophagy and production of reactive oxygen species occur at various stages of atherosclerosis. To clarify the role and mechanism of autophagy and reactive oxygen species in atherosclerosis is of great significance to the prevention and treatment of atherosclerosis. Recent studies have shown that basal autophagy plays an important role in protecting cells from oxidative stress, reducing apoptosis and enhancing atherosclerotic plaque stability. Autophagy deficiency and excessive accumulation of reactive oxygen species can impair the function of endothelial cells, macrophages and smooth muscle cells, trigger autophagic cell death, and lead to instability and even rupture of plaques. However, the main signaling pathways regulating autophagy, the molecular mechanisms of autophagy and reactive oxygen species interaction, how they are initiated and distributed in plaques, and how they affect atherosclerosis progression, remain to be clarified. At present, there is no autophagy inducer used to treat atherosclerosis clinically. Therefore, it is urgent to clarify the mechanism of autophagy and find new targets for autophagy. Antioxidant agents generally have defects such as low reactive oxygen species scavenging efficiency and high cytotoxicity. Highly potent autophagy inducers and reactive oxygen species scavengers still need to be further developed and validated to provide more possibilities for innovative treatments for atherosclerosis.

White matter hyperintensity genetic risk factor TRIM47 regulates autophagy in brain endothelial cells

White matter hyperintensity (WMH) is strongly correlated with age-related dementia and hypertension, but its pathogenesis remains obscure. Genome-wide association studies identified TRIM47 at the 17q25 locus as a top genetic risk factor for WMH formation. TRIM family is a class of E3 ubiquitin ligase with pivotal functions in autophagy, which is critical for brain endothelial cell (ECs) remodeling during hypertension. We hypothesize that TRIM47 regulates autophagy and its loss-of-function disturbs cerebrovasculature. Based on transcriptomics and immunohistochemistry, TRIM47 is found highly expressed by brain ECs in human and mouse, and its transcription is upregulated by artificially induced autophagy while downregulated in hypertension-like conditions. Using in silico simulation, immunocytochemistry and super-resolution microscopy, we predicted a highly conserved binding site between TRIM47 and the LIR (LC3-interacting region) motif of LC3B. Importantly, pharmacological autophagy induction increased Trim47 expression on mouse ECs (b.End3) culture, while silencing Trim47 significantly increased autophagy with ULK1 phosphorylation induction, transcription, and vacuole formation. Together, we demonstrate that TRIM47 is an endogenous inhibitor of autophagy in brain ECs, and such TRIM47-mediated regulation connects genetic and physiological risk factors for WMH formation but warrants further investigation.

Dynamic changes in Beclin-1, LC3B, and p62 in aldose reductase-knockout mice at different time points after ischemic stroke

Ischemic stroke is a brain injury caused by cerebral blood circulation disorders and is closely related to oxidative stress. Aldose reductase (AR) is a critical enzyme involved in oxidative stress. Autophagy has previously been found to play a key role in cerebral ischemia‒reperfusion injury. However, it is still unclear how autophagy molecules change after cerebral ischemia‒reperfusion injury in AR knockout mice (AR-/-). A transient middle cerebral artery occlusion (tMCAO) model was generated in AR-/- mice, and the neurological deficit scores of the mice were observed and recorded on Days 1, 3 and 5 after tMCAO. Neuronal damage in the ischemic penumbra was observed by TTC, HE, and Nissl staining. The expression of the autophagy-related molecules Beclin-1, LC3II/I, and P62 as well as that of molecules related to inflammation, oxidative stress, and neurological damage was detected by RT‒qPCR, western blotting, and immunofluorescence. Autophagosomes were observed using a transmission electron microscope. Cerebral ischemia‒reperfusion injury caused neurological deficits and ischemic infarction in tMCAO mice (P < 0.01). Beclin-1, Bcl2/Bax, SOD, GSH-px, P62, PSD95, and TOM20 levels decreased (P < 0.05), while IL-6, LC3II/I, and GFAP levels increased (P < 0.01) in the AR-/- tMCAO-1d group and the AR-/- tMCAO-3d group, compared to those in the sham group. Beclin-1, Bcl2/Bax, NOX4, GSH-px, P62, and PSD95 levels increased (P < 0.01), while IL-6, LC3II/I, and GFAP levels decreased (P < 0.01) in the AR-/- tMCAO-5d group compared to those in the AR-/- tMCAO-1d group. Autophagosome formation was observed in tMCAO mice. In summary, the changes in autophagy proteins in the brain tissue of the AR-/- mice after tMCAO were more obvious on Days 1 and 3 after tMCAO. The expression of Beclin-1 and P62 decreased, and the expression of LC3B increased after cerebral ischemia‒reperfusion injury in AR-/- mouse brain tissue.

Nrf2 Connects Cellular Autophagy and Vascular Senescence in Atherosclerosis: A Mini-Review

Nuclear factor erythroid 2-related factor 2 (Nrf2), a transcriptional factor that maintains intracellular redox equilibrium, modulates the expression of antioxidant genes, scavenger receptors, and cholesterol efflux transporters, all of which contribute significantly to foam cell development and plaque formation. Nrf2 has recently emerged as a key regulator that connects autophagy and vascular senescence in atherosclerosis. Autophagy, a cellular mechanism involved in the breakdown and recycling of damaged proteins and organelles, and cellular senescence, a state of irreversible growth arrest, are both processes implicated in the pathogenesis of atherosclerosis. The intricate interplay of these processes has received increasing attention, shedding light on their cumulative role in driving the development of atherosclerosis. Recent studies have revealed that Nrf2 plays a critical role in mediating autophagy and senescence in atherosclerosis progression. Nrf2 activation promotes autophagy, which increases lipid clearance and prevents the development of foam cells. Meanwhile, the activation of Nrf2 also inhibits cellular senescence by regulating the expression of senescence markers to preserve cellular homeostasis and function and delay the progression of atherosclerosis. This review provides an overview of the molecular mechanisms through which Nrf2 connects cellular autophagy and vascular senescence in atherosclerosis. Understanding these mechanisms can provide insights into potential therapeutic strategies targeting Nrf2 to modulate cellular autophagy and vascular senescence, thereby preventing the progression of atherosclerosis.

Geniposide for treating atherosclerotic cardiovascular disease: a systematic review on its biological characteristics, pharmacology, pharmacokinetics, and toxicology

In recent years, the prevalence and fatality rates of atherosclerotic cardiovascular disease have not only shown a consistent rise that cannot be ignored, but have also become a pressing social health problem that requires urgent attention. While interventional surgery and drug therapy offer significant therapeutic results, they often come with common side effects. Geniposide, an active component extracted from the Chinese medicine Gardenia jasminoides Ellis, shows promise in the management of cardiac conditions. This review comprehensively outlines the underlying pharmacological mechanisms by which geniposide exerts its effects on atherosclerosis. Geniposide exhibits a range of beneficial effects including alleviating inflammation, inhibiting the development of macrophage foam cells, improving lipid metabolism, and preventing platelet aggregation and thrombosis. It also demonstrates mitochondrial preservation, anti-apoptotic effects, and modulation of autophagy. Moreover, geniposide shows potential in improving oxidative stress and endoplasmic reticulum stress by maintaining the body's antioxidant and oxidative balance. Additionally, this review comprehensively details the biological properties of geniposide, including methods of extraction and purification, as well as its pharmacokinetics and toxicological characteristics. It further discusses the clinical applications of related biopharmaceuticals, emphasizing the potential of geniposide in the prevention and treatment of atherosclerotic cardiovascular diseases. Furthermore, it highlights the limitations of current research, aiming to provide insights for future studies.

Multimodal Imaging-Assisted Intravascular Theranostic Photoactivation on Atherosclerotic Plaque

BACKGROUND

Atherosclerosis is a chronic inflammatory disease causing a fatal plaque rupture, and its key aspect is a failure to resolve inflammation. We hypothesize that macrophage-targeted near-infrared fluorescence emitting photoactivation could simultaneously assess macrophage/lipid-rich plaques in vivo and facilitate inflammation resolution.

METHODS

We fabricated a Dectin-1-targeted photoactivatable theranostic agent through the chemical conjugation of the near-infrared fluorescence-emitting photosensitizer chlorin e6 and the Dectin-1 ligand laminarin (laminarin-chlorin e6 [LAM-Ce6]). Intravascular photoactivation by a customized fiber-based diffuser after administration of LAM-Ce6 effectively reduced inflammation in the targeted plaques of atherosclerotic rabbits in vivo as serially assessed by dual-modal optical coherence tomography-near-infrared fluorescence structural-molecular catheter imaging after 4 weeks.

RESULTS

The number of apoptotic macrophages peaked at 1 day after laser irradiation and then resolved until 4 weeks. Autophagy was strongly augmented 1 hour after the light therapy, with the formation of autophagolysosomes. LAM-Ce6 photoactivation increased the terminal deoxynucleotidyl transferase dUTP (deoxyuridine triphosphate) nick end labeling/RAM11 (rabbit monocyte/macrophage antibody)- and MerTK (c-Mer tyrosine kinase)-positive cells in the plaques, suggesting enhanced efferocytosis. In line with inflammation resolution, photoactivation reduced the plaque burden through fibrotic replacement via the TGF (transforming growth factor)-β/CTGF (connective tissue growth factor) pathway.

CONCLUSIONS

Optical coherence tomography-near-infrared fluorescence imaging-guided macrophage Dectin-1-targetable photoactivation could induce the transition of macrophage/lipid-rich plaques into collagen-rich lesions through autophagy-mediated inflammation resolution and TGF-β-dependent fibrotic replacement. This novel strategy offers a new opportunity for the catheter-based theranostic strategy.

The effects of fine particulate matter on the blood-testis barrier and its potential mechanisms

With the rapid expansion of industrial scale, an increasing number of fine particulate matter (PM2.5) has bringing health concerns. Although exposure to PM2.5 has been clearly associated with male reproductive toxicity, the exact mechanisms are still unclear. Recent studies demonstrated that exposure to PM2.5 can disturb spermatogenesis through destroying the blood-testis barrier (BTB), consisting of different junction types, containing tight junctions (TJs), gap junctions (GJs), ectoplasmic specialization (ES) and desmosomes. The BTB is one of the tightest blood-tissue barriers among mammals, which isolating germ cells from hazardous substances and immune cell infiltration during spermatogenesis. Therefore, once the BTB is destroyed, hazardous substances and immune cells will enter seminiferous tubule and cause adversely reproductive effects. In addition, PM2.5 also has shown to cause cells and tissues injury via inducing autophagy, inflammation, sex hormones disorder, and oxidative stress. However, the exact mechanisms of the disruption of the BTB, induced by PM2.5, are still unclear. It is suggested that more research is required to identify the potential mechanisms. In this review, we aim to understand the adverse effects on the BTB after exposure to PM2.5 and explore its potential mechanisms, which provides novel insight into accounting for PM2.5-induced BTB injury.

Elucidating the crosstalk between endothelial-to-mesenchymal transition (EndoMT) and endothelial autophagy in the pathogenesis of atherosclerosis

Atherosclerosis, a chronic systemic inflammatory condition, is implicated in most cardiovascular ischemic events. The pathophysiology of atherosclerosis involves various cell types and associated processes, including endothelial cell activation, monocyte recruitment, smooth muscle cell migration, involvement of macrophages and foam cells, and instability of the extracellular matrix. The process of endothelial-to-mesenchymal transition (EndoMT) has recently emerged as a pivotal process in mediating vascular inflammation associated with atherosclerosis. This transition occurs gradually, with a significant portion of endothelial cells adopting an intermediate state, characterized by a partial loss of endothelial-specific gene expression and the acquisition of "mesenchymal" traits. Consequently, this shift disrupts endothelial cell junctions, increases vascular permeability, and exacerbates inflammation, creating a self-perpetuating cycle that drives atherosclerotic progression. While endothelial cell dysfunction initiates the development of atherosclerosis, autophagy, a cellular catabolic process designed to safeguard cells by recycling intracellular molecules, is believed to exert a significant role in plaque development. Identifying the pathological mechanisms and molecular mediators of EndoMT underpinning endothelial autophagy, may be of clinical relevance. Here, we offer new insights into the underlying biology of atherosclerosis and present potential molecular mechanisms of atherosclerotic resistance and highlight potential therapeutic targets.

New insight into air pollution-related cardiovascular disease: an adverse outcome pathway framework of PM2.5-associated vascular calcification

Despite the air quality has been generally improved in recent years, ambient fine particulate matter (PM2.5), a major contributor to air pollution, remains one of the major threats to public health. Vascular calcification is a systematic pathology associated with an increased risk of cardiovascular disease. Although the epidemiological evidence has uncovered the association between PM2.5 exposure and vascular calcification, little is known about the underlying mechanisms. The adverse outcome pathway (AOP) concept offers a comprehensive interpretation of all of the findings obtained by toxicological and epidemiological studies. In this review, reactive oxygen species generation was identified as the molecular initiating event (MIE), which targeted subsequent key events (KEs) such as oxidative stress, inflammation, endoplasmic reticulum stress, and autophagy, from the cellular to the tissue/organ level. These KEs eventually led to the adverse outcome, namely increased incidence of vascular calcification and atherosclerosis morbidity. To the best of our knowledge, this is the first AOP framework devoted to PM2.5-associated vascular calcification, which benefits future investigations by identifying current limitations and latent biomarkers.

Programmed death of macrophages in atherosclerosis: mechanisms and therapeutic targets

Atherosclerosis is a progressive inflammatory disorder of the arterial vessel wall characterized by substantial infiltration of macrophages, which exert both favourable and detrimental functions. Early in atherogenesis, macrophages can clear cytotoxic lipoproteins and dead cells, preventing cytotoxicity. Efferocytosis - the efficient clearance of dead cells by macrophages - is crucial for preventing secondary necrosis and stimulating the release of anti-inflammatory cytokines. In addition, macrophages can promote tissue repair and proliferation of vascular smooth muscle cells, thereby increasing plaque stability. However, advanced atherosclerotic plaques contain large numbers of pro-inflammatory macrophages that secrete matrix-degrading enzymes, induce death in surrounding cells and contribute to plaque destabilization and rupture. Importantly, macrophages in the plaque can undergo apoptosis and several forms of regulated necrosis, including necroptosis, pyroptosis and ferroptosis. Regulated necrosis has an important role in the formation and expansion of the necrotic core during plaque progression, and several triggers for necrosis are present within atherosclerotic plaques. This Review focuses on the various forms of programmed macrophage death in atherosclerosis and the pharmacological interventions that target them as a potential means of stabilizing vulnerable plaques and improving the efficacy of currently available anti-atherosclerotic therapies.

Exacerbation of atherosclerosis by STX17 knockdown: Unravelling the role of autophagy and inflammation

Syntaxin 17 (STX17) has been identified as a crucial factor in mediating the fusion of autophagosomes and lysosomes. However, its specific involvement in the context of atherosclerosis (AS) remains unclear. This study sought to elucidate the role and mechanistic contributions of STX17 in the initiation and progression of AS. Utilizing both in vivo and in vitro AS model systems, we employed ApoE knockout (KO) mice subjected to a high-fat diet and human umbilical vein endothelial cells (HUVECs) treated with oxidized low-density lipoprotein (ox-LDL) to assess STX17 expression. To investigate underlying mechanisms, we employed shRNA-STX17 lentivirus to knock down STX17 expression, followed by evaluating autophagy and inflammation in HUVECs. In both in vivo and in vitro AS models, STX17 expression was significantly upregulated. Knockdown of STX17 exacerbated HUVEC damage, both with and without ox-LDL treatment. Additionally, we observed that STX17 knockdown impaired autophagosome degradation, impeded autophagy flux and also resulted in the accumulation of dysfunctional lysosomes in HUVECs. Moreover, STX17 knockdown intensified the inflammatory response following ox-LDL treatment in HUVECs. Further mechanistic exploration revealed an association between STX17 and STING; reducing STX17 expression increased STING levels. Further knockdown of STING enhanced autophagy flux. In summary, our findings suggest that STX17 knockdown worsens AS by impeding autophagy flux and amplifying the inflammatory response. Additionally, the interaction between STX17 and STING may play a crucial role in STX17-mediated autophagy.

The Mediterranean Diet, Its Microbiome Connections, and Cardiovascular Health: A Narrative Review

The Mediterranean diet (MD), rich in minimally processed plant foods and in monounsaturated fats but low in saturated fats, meat, and dairy products, represents one of the most studied diets for cardiovascular health. It has been shown, from both observational and randomized controlled trials, that MD reduces body weight, improves cardiovascular disease surrogates such as waist-to-hip ratios, lipids, and inflammation markers, and even prevents the development of fatal and nonfatal cardiovascular disease, diabetes, obesity, and other diseases. However, it is unclear whether it offers cardiovascular benefits from its individual components or as a whole. Furthermore, limitations in the methodology of studies and meta-analyses have raised some concerns over its potential cardiovascular benefits. MD is also associated with characteristic changes in the intestinal microbiota, mediated through its constituents. These include increased growth of species producing short-chain fatty acids, such as Clostridium leptum and Eubacterium rectale, increased growth of Bifidobacteria, Bacteroides, and Faecalibacterium prausnitzii species, and reduced growth of Firmicutes and Blautia species. Such changes are known to be favorably associated with inflammation, oxidative status, and overall metabolic health. This review will focus on the effects of MD on cardiovascular health through its action on gut microbiota.

Natural products targeting autophagy and apoptosis in NSCLC: a novel therapeutic strategy

Lung cancer is the leading cause of cancer-related mortality worldwide, with non-small cell lung cancer (NSCLC) being the predominant type. The roles of autophagy and apoptosis in NSCLC present a dual and intricate nature. Additionally, autophagy and apoptosis interconnect through diverse crosstalk molecules. Owing to their multitargeting nature, safety, and efficacy, natural products have emerged as principal sources for NSCLC therapeutic candidates. This review begins with an exploration of the mechanisms of autophagy and apoptosis, proceeds to examine the crosstalk molecules between these processes, and outlines their implications and interactions in NSCLC. Finally, the paper reviews natural products that have been intensively studied against NSCLC targeting autophagy and apoptosis, and summarizes in detail the four most retrieved representative drugs. This paper clarifies good therapeutic effects of natural products in NSCLC by targeting autophagy and apoptosis and aims to promote greater consideration by researchers of natural products as candidates for anti-NSCLC drug discovery.

Amino Acid Metabolism and Atherosclerotic Cardiovascular Disease

Despite significant advances in medical treatments and drug development, atherosclerotic cardiovascular disease (ASCVD) remains a leading cause of death worldwide. Dysregulated lipid metabolism is a well-established driver of ASCVD. Unfortunately, even with potent lipid-lowering therapies, ASCVD-related deaths have continued to increase over the past decade, highlighting an incomplete understanding of the underlying risk factors and mechanisms of ASCVD. Accumulating evidence over the past decades indicates a correlation between amino acids and disease state. This review explores the emerging role of amino acid metabolism in ASCVD, uncovering novel potential biomarkers, causative factors, and therapeutic targets. Specifically, the significance of arginine and its related metabolites, homoarginine and polyamines, branched-chain amino acids, glycine, and aromatic amino acids, in ASCVD are discussed. These amino acids and their metabolites have been implicated in various processes characteristic of ASCVD, including impaired lipid metabolism, endothelial dysfunction, increased inflammatory response, and necrotic core development. Understanding the complex interplay between dysregulated amino acid metabolism and ASCVD provides new insights that may lead to the development of novel diagnostic and therapeutic approaches. Although further research is needed to uncover the precise mechanisms involved, it is evident that amino acid metabolism plays a role in ASCVD.

Association of Circulating Autophagy Proteins ATG5 and Beclin 1 with Acute Myocardial Infarction in a Case-Control Study

INTRODUCTION

Acute myocardial infarction (AMI) is a main contributor of sudden cardiac death worldwide. The discovery of new biomarkers that can improve AMI risk prediction meets a major clinical need for the identification of high-risk patients and the tailoring of medical treatment. Previously, we reported that autophagy a highly conserved catabolic mechanism for intracellular degradation of cellular components is involved in atherosclerotic plaque phenotype and cardiac pathological remodeling. The crucial role of autophagy in the normal and diseased heart has been well described, and its activation functions as a pro-survival process in response to myocardial ischemia. However, autophagy is dysregulated in ischemia/reperfusion injury, thus promoting necrotic or apoptotic cardiac cell death. Very few studies have focused on the plasma levels of autophagy markers in cardiovascular disease patients, even though they could be companion biomarkers of AMI injury. The aims of the present study were to evaluate (1) whether variations in plasma levels of two key autophagy regulators autophagy-related gene 5 (ATG5) and Beclin 1 (the mammalian yeast ortholog Atg6/Vps30) are associated with AMI and (2) their potential for predicting AMI risk.

METHODS

The case-control study population included AMI patients (n = 100) and control subjects (n = 99) at high cardiovascular risk but without known coronary disease. Plasma levels of ATG5 and Beclin 1 were measured in the whole population study by enzyme-linked immunosorbent assay.

RESULTS

Multivariate analyses adjusted on common cardiovascular factors and medical treatments, and receiver operating characteristic curves demonstrated that ATG5 and Beclin 1 levels were inversely associated with AMI and provided original biomarkers for AMI risk prediction.

CONCLUSION

Plasma levels of autophagy regulators ATG5 and Beclin 1 represent relevant candidate biomarkers associated with AMI.

Circular RNAs: Regulators of endothelial cell dysfunction in atherosclerosis

Endothelial cell (EC) dysfunction is associated with atherosclerosis. Circular RNAs (circRNAs) are covalently closed loops formed by back-splicing, are highly expressed in a tissue-specific or cell-specific manner, and regulate ECs mainly through miRNAs (mircoRNAs) or protein sponges. This review describes the regulatory mechanisms and physiological functions of circRNAs, as well as the differential expression of circRNAs in aberrant ECs. This review focuses on their roles in inflammation, proliferation, migration, angiogenesis, apoptosis, senescence, and autophagy in ECs from the perspective of signaling pathways, such as nuclear factor κB (NF-κB), nucleotide-binding domain, leucine-rich-repeat family, pyrin-domain-containing 3 (NLRP3)/caspase-1, Janus kinase/signal transducer and activator of transcription (JAK/STAT), and phosphoinositide-3 kinase/protein kinase B (PI3K/Akt). Finally, we address the issues and recent advances in circRNAs as well as circRNA-mediated regulation of ECs to improve our understanding of the molecular mechanisms underlying the progression of atherosclerosis and provide a reference for studies on circRNAs that regulate EC dysfunction and thus affect atherosclerosis.

Reactive Carbonyl Species and Protein Lipoxidation in Atherogenesis

Atherosclerosis is a multifactorial disease of medium and large arteries, characterized by the presence of lipid-rich plaques lining the intima over time. It is the main cause of cardiovascular diseases and death worldwide. Redox imbalance and lipid peroxidation could play key roles in atherosclerosis by promoting a bundle of responses, including endothelial activation, inflammation, and foam cell formation. The oxidation of polyunsaturated fatty acids generates various lipid oxidation products such as reactive carbonyl species (RCS), including 4-hydroxy alkenals, malondialdehyde, and acrolein. RCS covalently bind to nucleophilic groups of nucleic acids, phospholipids, and proteins, modifying their structure and activity and leading to their progressive dysfunction. Protein lipoxidation is the non-enzymatic post-translational modification of proteins by RCS. Low-density lipoprotein (LDL) oxidation and apolipoprotein B (apoB) modification by RCS play a major role in foam cell formation. Moreover, oxidized LDLs are a source of RCS, which form adducts on a huge number of proteins, depending on oxidative stress intensity, the nature of targets, and the availability of detoxifying systems. Many systems are affected by lipoxidation, including extracellular matrix components, membranes, cytoplasmic and cytoskeletal proteins, transcription factors, and other components. The mechanisms involved in lipoxidation-induced vascular dysfunction are not fully elucidated. In this review, we focus on protein lipoxidation during atherogenesis.

The SGLT2 inhibitor empagliflozin attenuates atherosclerosis progression by inducing autophagy

Cardiovascular disease due to atherosclerosis is one of the leading causes of death worldwide; however, the underlying mechanism has yet to be defined. The sodium-dependent glucose transporter 2 inhibitor (SGLT2i) empagliflozin is a new type of hypoglycemic drug. Recent studies have shown that empagliflozin not only reduces high glucose levels but also exerts cardiovascular-protective effects and slows the process of atherosclerosis. The purpose of this study was to elucidate the mechanism by which empagliflozin ameliorates atherosclerosis. Male apolipoprotein E-deficient (ApoE-/-) mice were fed a high-fat Western diet to establish an atherosclerosis model. The area and size of atherosclerotic lesions in ApoE-/- mice were then assessed by performing hematoxylin-eosin (HE) staining after empagliflozin treatment. Concurrently, oxidized low-density lipoprotein (oxLDL) was used to mimic atherosclerosis in three different types of cells. Then, following empagliflozin treatment of macrophage cells (RAW264.7), human aortic smooth muscle cells (HASMCs), and human umbilical vein endothelial cells (HUVECs), western blotting was applied to measure the levels of autophagy-related proteins and proinflammatory cytokines, and green fluorescent protein (GFP)-light chain 3 (LC3) puncta were detected using confocal microscopy to confirm autophagosome formation. Oil Red O staining was performed to detect the foaming of macrophages and HASMCs, and flow cytometry was used for the cell cycle analysis. 5-ethynyl-2'-deoxyuridine (EdU), cell counting kit-8 (CCK-8), and scratch assays were also performed to examine the proliferation and migration of HASMCs. Empagliflozin suppressed the progression of atherosclerotic lesions in ApoE-/- mice. Empagliflozin also induced autophagy in RAW246.7 cells, HASMCs, and HUVECs via the adenosine monophosphate-activated protein kinase (AMPK) signaling pathway, and it significantly increased the levels of the Beclin1 protein, the LC3B-II/I ratio, and p-AMPK protein. In addition, empagliflozin decreased the expression of P62 and the protein levels of inflammatory cytokines, and it inhibited the foaming of RAW246.7 cells and HASMCs, as well as the expression of inflammatory factors by inducing autophagy. Empagliflozin activated autophagy through the AMPK signaling pathway to delay the progression of atherosclerosis. Furthermore, the results of flow cytometry, EdU assays, CCK-8 cell viability assays, and scratch assays indicated that empagliflozin blocked HASMCs proliferation and migration. Empagliflozin activates autophagy through the AMPK signaling pathway to delay the evolution of atherosclerosis, indicating that it may represent a new and effective drug for the clinical treatment of atherosclerosis.

Plasma levels of autophagy regulator Rubicon are inversely associated with acute coronary syndrome

Background

The discovery of novel biomarkers that improve current cardiovascular risk prediction models of acute coronary syndrome (ACS) is needed for the identification of very high-risk patients and therapeutic decision-making. Autophagy is a highly conserved catabolic mechanism for intracellular degradation of cellular components through lysosomes. The autophagy process helps maintain cardiac homeostasis and dysregulated autophagy has been described in cardiovascular conditions. Rubicon (Run domain Beclin-1-interacting and cysteine-rich domain-containing protein) is a key regulator of autophagy with a potential role in cardiac stress.

Objectives

The aims of the present study were to assess whether changes in circulating Rubicon levels are associated with ACS and to evaluate the added value of Rubicon to a clinical predictive risk model.

Methods and results

The study population included ACS patients (n = 100) and control subjects (n = 99) at high to very high cardiovascular risk but without known coronary event. Plasma Rubicon levels were measured in the whole study population by enzyme-linked immunosorbent assay. Multivariate logistic regression analyses established that Rubicon levels were inversely associated with ACS. A receiver operating characteristic curve analysis demonstrated that the addition of Rubicon improved the predictive performance of the model with an increased area under the curve from 0.868 to 0.896 (p = 0.038).

Conclusions

Plasma levels of the autophagy regulator Rubicon are associated with ACS and provide added value to classical risk markers for ACS.

White matter hyperintensity genetic risk factor TRIM47 regulates autophagy in brain endothelial cells

White matter hyperintensity (WMH) is strongly correlated with age-related dementia and hypertension, but its pathogenesis remains obscure. GWAS identified TRIM47 at 17q25 locus as a top genetic risk factor for WMH formation. TRIM family is a class of E3 ubiquitin ligase with pivotal functions in autophagy, which is critical for brain endothelial cell (ECs) remodeling during hypertension. We hypothesize that TRIM47 regulates autophagy and its loss-of-function disturbs cerebrovasculature. Based on transcriptomics and immunohistochemistry, TRIM47 is found selectively expressed by brain ECs in human and mouse, and its transcription is upregulated by artificially-induced autophagy while downregulated in hypertension-like conditions. Using in silico simulation, immunocytochemistry and super-resolution microscopy, we identified the highly conserved binding site between TRIM47 and the LIR (LC3-interacting region) motif of LC3B. Importantly, pharmacological autophagy induction increased Trim47 expression on mouse ECs (b.End3) culture, while silencing Trim47 significantly increased autophagy with ULK1 phosphorylation induction, transcription and vacuole formation. Together, we confirm that TRIM47 is an endogenous inhibitor of autophagy in brain ECs, and such TRIM47-mediated regulation connects genetic and physiological risk factors for WMH formation but warrants further investigation.

SUMMARY STATEMENT

TRIM47, top genetic risk factor for white matter hyperintensity formation, is a negative regulator of autophagy in brain endothelial cells and implicates a novel cellular mechanism for age-related cerebrovascular changes.

KLF15 Transcriptionally Activates ATG14 to Promote Autophagy and Attenuate Damage of ox-LDL-Induced HAECs

Kruppel-like factor 15 (KLF15) is involved in many cardiovascular diseases and is abnormally expressed in atherosclerosis (AS), but the regulatory mechanism of KLF15 in AS has not been reported so far. RT-qPCR was used to detect the expression of KLF15 and ATG14 in AS patients. Subsequently, human aortic endothelial cells (HAECs) were induced by oxidized low densitylipoprotein (ox-LDL), and the expression of KLF15 in model cells was detected. KLF15 was overexpressed in cells by lipofection transfection, and then CCK8, flow cytometry, Western blot, ELISA, and related assay kits were used to detect cell viability, apoptosis, inflammatory response as well as oxidative stress, respectively. The targeted regulatory relationship between KLF15 and autophagy-related 14 (ATG14) was detected by ChIP and luciferase reporter assays. Following ATG14 silencing in KLF15-overexpressing cells, immunofluorescence and Western blot were used to detect the autophagy. Finally, after the addition of 3-Methyladenine (3-MA), an autophagy inhibitor, the aforementioned experiments were conducted again to further explore the mechanism. The expression of KLF15 and ATG14 were decreased in AS patients and ox-LDL-induced HAECs. Overexpression of KLF15 protected ox-LDL-induced HAECs from damage, which might be achieved through transcriptional regulation of ATG14. In addition, KLF15 could promote autophagy through transcriptional activation of ATG14. KLF15 transcriptionally activated ATG14 to promote autophagy and attenuate damage of ox-LDL-induced HAECs.

A biochemomechanical model of collagen turnover in arterial adaptations to hemodynamic loading

The production, removal, and remodeling of fibrillar collagen is fundamental to mechanical homeostasis in arteries, including dynamic morphological and microstructural changes that occur in response to sustained changes in blood flow and pressure under physiological conditions. These dynamic processes involve complex, coupled biological, chemical, and mechanical mechanisms that are not completely understood. Nevertheless, recent simulations using constrained mixture models with phenomenologically motivated constitutive relations have proven able to predict salient features of the progression of certain vascular adaptations as well as disease processes. Collagen turnover is modeled, in part, via stress-dependent changes in collagen half-life, typically within the range of 10-70 days. By contrast, in this work we introduce a biochemomechanical approach to model the cellular synthesis of procollagen as well as its transition from an intermediate state of assembled microfibrils to mature cross-linked fibers, with mechano-regulated removal. The resulting model can simulate temporal changes in geometry, composition, and stress during early vascular adaptation (weeks to months) for modest changes in blood flow or pressure. It is shown that these simulations capture salient features from data presented in the literature from different animal models.

Long Noncoding RNA Gpr137b-ps Promotes Advanced Atherosclerosis via the Regulation of Autophagy in Macrophages

BACKGROUND

Current therapies cannot completely reverse advanced atherosclerosis. High levels of amino acids, induced by Western diet, stimulate mTORC1 (mammalian target of rapamycin complex 1)-autophagy defects in macrophages, accelerating atherosclerotic plaque progression. In addition, autophagy-lysosomal dysfunction contributes to plaque necrotic core enlargement and lipid accumulation. Therefore, it is essential to investigate the novel mechanism and molecules to reverse amino acid-mTORC1-autophagy signaling dysfunction in macrophages of patients with advanced atherosclerosis.

METHODS

We observed that Gpr137b-ps (G-protein-coupled receptor 137B, pseudogene) was upregulated in advanced atherosclerotic plaques. The effect of Gpr137b-ps on the progression of atherosclerosis was studied by generating advanced plaques in ApoE-/- mice with cardiac-specific knockout of Gpr137b-ps. Bone marrow-derived macrophages and mouse mononuclear macrophage cell line RAW264.7 cells were subjected to starvation or amino acid stimulation to study amino acid-mTORC1-autophagy signaling. Using both gain- and loss-of-function approaches, we explored the mechanism of Gpr137b-ps-regulated autophagy.

RESULTS

Our results demonstrated that Gpr137b-ps deficiency led to enhanced autophagy in macrophages and reduced atherosclerotic lesions, characterized by fewer necrotic cores and less lipid accumulation. Knockdown of Gpr137b-ps increased autophagy and prevented amino acid-induced mTORC1 signaling activation. As the downstream binding protein of Gpr137b-ps, HSC70 (heat shock cognate 70) rescued the impaired autophagy induced by Gpr137b-ps. Furthermore, Gpr137b-ps interfered with the HSC70 binding to G3BP (Ras GTPase-activating protein-binding protein), which tethers the TSC (tuberous sclerosis complex) complex to lysosomes and suppresses mTORC1 signaling. In addition to verifying that the NTF2 (nuclear transport factor 2) domain of G3BP binds to HSC70 by in vitro protein synthesis, we further demonstrated that HSC70 binds to the NTF2 domain of G3BP through its W90-F92 motif by using computational modeling.

CONCLUSIONS

These findings reveal that Gpr137b-ps plays an essential role in the regulation of macrophage autophagy, which is crucial for the progression of advanced atherosclerosis. Gpr137b-ps impairs the interaction of HSC70 with G3BP to regulate amino acid-mTORC1-autophagy signaling, and these results provide a new potential therapeutic direction for the treatment of advanced atherosclerosis.

Mechanisms and effects of metformin on skeletal muscle disorders

Skeletal muscle disorders are mostly genetic and include several rare diseases. With disease progression, muscle fibrosis and adiposis occur, resulting in limited mobility. The long course of these diseases combined with limited treatment options affect patients both psychologically and economically, hence the development of novel treatments for neuromuscular diseases is crucial to obtain a better quality of life. As a widely used hypoglycemic drug in clinical practice, metformin not only has anti-inflammatory, autophagy-regulating, and mitochondrial biogenesis-regulating effects, but it has also been reported to improve the symptoms of neuromuscular diseases, delay hypokinesia, and regulate skeletal muscle mass. However, metformin's specific mechanism of action in neuromuscular diseases requires further elucidation. This review summarizes the evidence showing that metformin can regulate inflammation, autophagy, and mitochondrial biogenesis through different pathways, and further explores its mechanism of action in Duchenne muscular dystrophy, statin-associated muscle disorders, and age-related sarcopenia. This review clarifies the directions of future research on therapy for neuromuscular diseases.

New Dawn for Atherosclerosis: Vascular Endothelial Cell Senescence and Death

Endothelial cells (ECs) form the inner linings of blood vessels, and are directly exposed to endogenous hazard signals and metabolites in the circulatory system. The senescence and death of ECs are not only adverse outcomes, but also causal contributors to endothelial dysfunction, an early risk marker of atherosclerosis. The pathophysiological process of EC senescence involves both structural and functional changes and has been linked to various factors, including oxidative stress, dysregulated cell cycle, hyperuricemia, vascular inflammation, and aberrant metabolite sensing and signaling. Multiple forms of EC death have been documented in atherosclerosis, including autophagic cell death, apoptosis, pyroptosis, NETosis, necroptosis, and ferroptosis. Despite this, the molecular mechanisms underlying EC senescence or death in atherogenesis are not fully understood. To provide a comprehensive update on the subject, this review examines the historic and latest findings on the molecular mechanisms and functional alterations associated with EC senescence and death in different stages of atherosclerosis.

Microorganism-regulated autophagy in gastrointestinal cancer

Gastrointestinal cancer has always been one of the most urgent problems to be solved, and it has become a major global health issue. Microorganisms in the gastrointestinal tract regulate normal physiological and pathological processes. Accumulating evidence reveals the role of the imbalance in the microbial community during tumorigenesis. Autophagy is an important intracellular homeostatic process, where defective proteins and organelles are degraded and recycled under stress. Autophagy plays a dual role in tumors as both tumor suppressor and tumor promoter. Many studies have shown that autophagy plays an important role in response to microbial infection. Here, we provide an overview on the regulation of the autophagy signaling pathway by microorganisms in gastrointestinal cancer.

Sirt6 enhances macrophage lipophagy and improves lipid metabolism disorder by regulating the Wnt1/β-catenin pathway in atherosclerosis

Lipid metabolism disorders are considerably involved in the pathology of atherosclerosis; nevertheless, the fundamental mechanism is still largely unclear. This research sought to examine the function of lipophagy in lipid metabolism disorder-induced atherosclerosis and its fundamental mechanisms. Previously, Sirt6 has been reported to stimulate plaque stability by promoting macrophage autophagy. However, its role in macrophage lipophagy and its relationship with Wnt1 remains to be established. In this study, ApoE-/-: Sirt6-/- and ApoE-/-: Sirt6Tg mice were used and lipid droplets were analysed via transmission electron microscopy and Bodipy 493/503 staining in vitro. Atherosclerotic plaques in ApoE-/-: Sirt6-/- mice showed greater necrotic cores and lower stability score. Reconstitution of Sirt6 in atherosclerotic mice improved lipid metabolism disorder and prevented the progression of atherosclerosis. Furthermore, macrophages with Ac-LDL intervention showed more lipid droplets and increased expression of adipophilin and PLIN2. Reconstitution of Sirt6 recruited using SNF2H suppressed Wnt1 expression and improved lipid metabolism disorder by promoting lipophagy. In addition, downregulation of Sirt6 expression in Ac-LDL-treated macrophages inhibited lipid droplet degradation and stimulated foam cell formation. Innovative discoveries in the research revealed that atherosclerosis is caused by lipid metabolism disorders due to downregulated Sirt6 expression. Thus, modulating Sirt6's function in lipid metabolism might be a useful therapeutic approach for treating atherosclerosis.

Genetic inhibition of CARD9 accelerates the development of atherosclerosis in mice through CD36 dependent-defective autophagy

Caspase recruitment-domain containing protein 9 (CARD9) is a key signaling pathway in macrophages but its role in atherosclerosis is still poorly understood. Global deletion of Card9 in Apoe-/- mice as well as hematopoietic deletion in Ldlr-/- mice increases atherosclerosis. The acceleration of atherosclerosis is also observed in Apoe-/-Rag2-/-Card9-/- mice, ruling out a role for the adaptive immune system in the vascular phenotype of Card9 deficient mice. Card9 deficiency alters macrophage phenotype through CD36 overexpression with increased IL-1β production, increased lipid uptake, higher cell death susceptibility and defective autophagy. Rapamycin or metformin, two autophagy inducers, abolish intracellular lipid overload, restore macrophage survival and autophagy flux in vitro and finally abolish the pro-atherogenic effects of Card9 deficiency in vivo. Transcriptomic analysis of human CARD9-deficient monocytes confirms the pathogenic signature identified in murine models. In summary, CARD9 is a key protective pathway in atherosclerosis, modulating macrophage CD36-dependent inflammatory responses, lipid uptake and autophagy.

Lipid-laden foam cells in the pathology of atherosclerosis: shedding light on new therapeutic targets

INTRODUCTION

Lipid-laden foam cells within atherosclerotic plaques are key players in all phases of lesion development including its progression, necrotic core formation, fibrous cap thinning, and eventually plaque rupture. Manipulating foam cell biology is thus an attractive therapeutic strategy at early, middle, and even late stages of atherosclerosis. Traditional therapies have focused on prevention, especially lowering plasma lipid levels. Despite these interventions, atherosclerosis remains a major cause of cardiovascular disease, responsible for the largest numbers of death worldwide.

AREAS COVERED

Foam cells within atherosclerotic plaques are comprised of macrophages, vascular smooth muscle cells, and other cell types which are exposed to high concentrations of lipoproteins accumulating within the subendothelial intimal layer. Macrophage-derived foam cells are particularly well studied and have provided important insights into lipid metabolism and atherogenesis. The contributions of foam cell-based processes are discussed with an emphasis on areas of therapeutic potential and directions for drug development.

EXERT OPINION

As key players in atherosclerosis, foam cells are attractive targets for developing more specific, targeted therapies aimed at resolving atherosclerotic plaques. Recent advances in our understanding of lipid handling within these cells provide insights into how they might be manipulated and clinically translated to better treat atherosclerosis.

An Autophagy-Associated MITF-GAS5-miR-23 Loop Attenuates Vascular Oxidative and Inflammatory Damage in Sepsis

BACKGROUND

Sepsis induces GAS5 expression in the vascular endothelium, but the molecular mechanism is unclear, as is the role of GAS5 in sepsis.

METHODS AND RESULTS

We observed that GAS5 expression in the endothelium was significantly upregulated in a sepsis mouse model. ChIP-PCR and EMSA confirmed that the oxidative stress (OS)-activated MiT-TFE transcription factor (MITF, TFE3, and TFEB)-mediated GAS5 transcription. In vitro, GAS5 overexpression attenuated OS and inflammation in endothelial cells (ECs) while maintaining the structural and functional integrity of mitochondria. In vivo, GAS5 reduced tissue ROS levels, maintained vascular barrier function to reduce leakage, and ultimately attenuated sepsis-induced lung injury. Luciferase reporter assays revealed that GAS5 protected MITF from degradation by sponging miR-23, thereby forming a positive feedback loop consisting of MITF, GAS5, and miR-23. Despite the fact that the OS-activated MITF-GAS5-miR-23 loop boosted MITF-mediated p62 transcription, ECs do not need to increase mitophagy to exert mitochondrial quality control since MITF-mediated Nrf2 transcription exists. Compared to mitophagy, MITF-transcribed p62 prefers to facilitate the autophagic degradation of Keap1 through a direct interaction, thereby relieving the inhibition of Nrf2 by Keap1, indicating that MITF can upregulate Nrf2 at both the transcriptional and posttranscriptional levels. Following this, ChIP-PCR demonstrated that Nrf2 can also transcribe MITF, revealing that there is a reciprocal positive regulatory association between MITF and Nrf2.

CONCLUSION

In sepsis, the ROS-activated MITF-GAS5-miR-23 loop integrated the antioxidant and autophagy systems through MITF-mediated transcription of Nrf2 and p62, which dynamically regulate the level and type of autophagy, as well as exert antioxidant and anti-inflammatory effects.

Mechanisms of neutrophil extracellular trap in chronic inflammation of endothelium in atherosclerosis

Cardiovascular diseases are a primary cause of morbidity and mortality around the world. In addition, atherosclerosis (AS)-caused cardiovascular disease is the primary cause of death in human diseases, and almost two billion people suffer from carotid AS worldwide. AS is caused by chronic inflammation of the arterial vessel and is initiated by dysfunction of vascular endothelial cells. Neutrophils protect against pathogen invasion because they function as a component of the innate immune system. However, the contribution of neutrophils to cardiovascular disease has not yet been clarified. Neutrophil extracellular traps (NETs) represent an immune defense mechanism that is different from direct pathogen phagocytosis. NETs are extracellular web-like structures activated by neutrophils, and they play important roles in promoting endothelial inflammation via direct or indirect pathways. NETs consist of DNA, histones, myeloperoxidase, matrix metalloproteinases, proteinase 3, etc. Most of the components of NETs have no direct toxic effect on endothelial cells, such as DNA, but they can damage endothelial cells indirectly. In addition, NETs play a critical role in the process of AS; therefore, it is important to clarify the mechanisms of NETs in AS because NETs are a new potential therapeutic target AS. This review summarizes the possible mechanisms of NETs in AS.

Autophagy-related genes analysis reveals potential biomarkers for prediction of the impaired walking capacity of peripheral arterial disease

BACKGROUND

The role of autophagy and autophagy-related genes in peripheral arterial disease (PAD) remains unknown and may be of diagnostic and prognostic value. The aim of this study is to investigate the relationship between autophagy and PAD, and identify potential diagnostic or prognostic biomarkers for medical practice.

METHODS

Differentially expressed autophagy-related genes in PAD were explored from GSE57691 and validated in our WalkByLab registry participants by quantitative real-time polymerase chain reaction (qRT-PCR). The level of autophagy in peripheral blood mononuclear cells (PBMCs) of WalkByLab participants was assessed by analyzing autophagic marker proteins (beclin-1, P62, LC3B). Single sample gene set enrichment analysis (ssGSEA) was used to evaluate the immune microenvironment within the artery wall of PAD patients and healthy persons. Chemokine antibody array and enzyme-linked immunosorbent assay were used to assess the chemokines in participants' plasma. Treadmill testing with Gardner protocol was used to evaluate participants' walking capacity. Pain-free walking distance, maximum walking distance, and walking time were recorded. Finally, a nomogram model based on logistic regression was built to predict impaired walking performance.

RESULTS

A total of 20 relevant autophagy-related genes were identified, and these genes were confirmed to be expressed at low levels in our PAD participants. Western blotting demonstrated that the expression of autophagic marker proteins beclin-1 and LC3BII were significantly reduced in PAD patients' PBMCs. ssGSEA revealed that most of the autophagy-related genes were strongly correlated with immune function, with the largest number of associated genes showing interaction between cytokine-and-cytokine receptors (CCR). In this context, the chemokines growth-related oncogene (GRO) and neutrophil activating protein2 (NAP2) are highly expressed in the plasma of WalkByLab PAD patients and were significantly negatively correlated with the walking distance assessed by Gardner treadmill testing. Finally, the plasma NAP2 level (AUC: 0.743) and derived nomogram model (AUC: 0.860) has a strong predictive potential to identify a poor walking capacity.

CONCLUSIONS

Overall, these data highlight both the important role of autophagy and autophagy-related genes in PAD and link them to vascular inflammation (expression of chemokines). In particular, chemokine NAP2 emerged as a novel biomarker that can be used to predict the impaired walking capacity in PAD patients.

Prophylaxis of posterior capsule opacification through autophagy activation with indomethacin-eluting intraocular lens

Posterior capsule opacification (PCO) is the most common long-term postoperative complication of cataract surgery, leading to secondary vision loss. Optimized intraocular lens (IOL) structure and appropriate pharmacological intervention, which provides physical barriers and biological inhibition, respectively, can block the migration, proliferation, and epithelial-mesenchymal transition (EMT) of lens epithelial cells (LECs) for PCO prophylaxis. Herein, a novel indomethacin-eluting IOL (INDOM-IOL) with an optimized sharper edge and a sustained drug release behavior was developed for PCO prevention. Indomethacin (INDOM), an ophthalmic non-steroidal anti-inflammatory drug (NSAID) used for postoperative ocular inflammation, was demonstrated to not only be able to suppress cell migration and down-regulate the expression of cyclooxygenase-2 (COX-2) and EMT markers, including alpha-smooth muscle actin (α-SMA) and cyclin D1, but also promote the autophagy activation in LECs. Additionally, autophagy was also verified to be a potential therapeutic target for the down-regulation of EMT in LECs. The novel IOL, serving as a drug delivery platform, could carry an adjustable dose of hydrophobic indomethacin with sustained drug release ability for more than 28 days. In the rabbit PCO model, the indomethacin-eluting IOL showed excellent anti-inflammatory and anti-PCO effects. In summary, indomethacin is an effective pharmacological intervention in PCO prophylaxis, and the novel IOL we developed prevented PCO in vivo under its sustained indomethacin release property, which provided a promising approach for PCO prophylaxis in clinical application.

Hypertension and cellular senescence

Essential or primary hypertension is a wordwide health problem. Elevated blood pressure (BP) is closely associated not only with increased chronological aging but also with biological aging. There are various common pathways that play a role in cellular aging and BP regulation. These include but not limited to inflammation, oxidative stress, mitochondrial dysfunction, air pollution, decreased klotho activity increased renin angiotensin system activation, gut dysbiosis etc. It has already been shown that some anti-hypertensive drugs have anti-senescent actions and some senolytic drugs have BP lowering effects. In this review, we have summarized the common mechanisms underlying cellular senescence and HT and their relationships. We further reviewed the effect of various antihypertensive medications on cellular senescence and suggest further issues to be studied.

Green Tea Catechol (-)-Epigallocatechin Gallate (EGCG) Conjugated with Phenylalanine Shows Enhanced Autophagy Stimulating Activity in Human Aortic Endothelial Cells

(-)-Epigallocatechin gallate (EGCG) is one of the autophagy stimulators that have been reported to protect vascular endothelial cells from oxidative stress-induced damage. In this study, we attempted potentiation of the autophagy-stimulating activity of EGCG in human aortic epithelial cells (HAECs) by using the EGCG-phenylalanine conjugate, E10. Autophagy-stimulating activity of E10 was evaluated by LC3-II measurement in the absence and presence of the lysosomal blocker chloroquine, CTYO-ID staining, and reporter assay using tandem fluorescence-tagged LC3. These experiments revealed significantly enhanced autophagic flux stimulation in HAECs by E10 compared with EGCG. Further elaboration of E10 showed that activation of AMPK through phosphorylation as the major mechanism of its autophagy stimulation. Like other autophagy stimulators, E10 protected HAECs from lipotoxicity as well as accompanying endothelial senescence. Finally, stimulation of autophagy by E10 was shown to protect HAECs from oxidative stress-induced apoptosis. These findings collectively suggest potential clinical implications of E10 for various cardiovascular complications through stimulation of autophagy.