Drp-1 as Potential Therapeutic Target for Lipopolysaccharide-Induced Vascular Hyperpermeability

Twist2 knockdown alleviates renal ischemia-reperfusion injury by maintaining mitochondrial function and enhancing mitophagy through Bnip3

Renal ischemia-reperfusion injury (IRI) is a major cause of acute kidney injury (AKI). Twist-related protein 2 (Twist2) is a basic helix/loop/helix transcription factor. However, the underlying effects of Twist2 in IRI remain to be elucidated. Herein, we found that the expression of Twist2 was significantly upregulated in renal tissues of mice induced by ischemia/reperfusion (I/R) and in human renal tubular epithelial cell HK-2 exposed to hypoxia-reoxygenation. We silenced Twist2 with RNAi technology. Twist2 knockdown alleviated renal pathological damage in mice. Twist2 depletion ameliorated IRI-induced mitochondrial dysfunction, such as increasing ATP content and mitochondrial DNA copy number and restoring mitochondrial membrane potential in the kidneys of mice, and similar results were observed in in vitro experiments. Twist2 interference increased the expression of LC3B and decreased the expression of p62 and mitochondrial membrane proteins TIMM23 and TOMM20 both in vivo and in vitro. Electron microscope and the co-localization of LC3B and mitotracker DsRed suggested the induction of autophagy and mitophagy after Twist2 knockdown in kidneys or cells. Mechanism studies revealed that Twist2 exerted a direct inhibitory effect on BCL2 interacting protein 3 (Bnip3) transcriptional activity by targeting the Bnip3 promoter. In hypoxia/reoxygenation-induced renal tubular epithelial cells, the interference of Bnip3 reversed the effect of Twist2 depletion on mitochondrial function and mitophagy. In conclusion, our findings suggest that the depletion of Twist2 exerts renoprotective effect in I/R-induced AKI. Twist2 regulates mitochondrial function and mitophagy in part by targeting and downregulating Bnip3. Our study provides new insights into the pathological mechanisms of I/R-induced AKI.

Vascular endothelial cell injury: causes, molecular mechanisms, and treatments

Vascular endothelial cells form a single layer of flat cells that line the inner surface of blood vessels, extending from large vessels to the microvasculature of various organs. These cells are crucial metabolic and endocrine components of the body, playing vital roles in maintaining circulatory stability, regulating vascular tone, and preventing coagulation and thrombosis. Endothelial cell injury is regarded as a pivotal initiating factor in the pathogenesis of various diseases, triggered by multiple factors, including infection, inflammation, and hemodynamic changes, which significantly compromise vascular integrity and function. This review examines the causes, underlying molecular mechanisms, and potential therapeutic approaches for endothelial cell injury, focusing specifically on endothelial damage in cardiac ischemia/reperfusion (I/R) injury, sepsis, and diabetes. It delves into the intricate signaling pathways involved in endothelial cell injury, emphasizing the roles of oxidative stress, mitochondrial dysfunction, inflammatory mediators, and barrier damage. Current treatment strategies-ranging from pharmacological interventions to regenerative approaches and lifestyle modifications-face ongoing challenges and limitations. Overall, this review highlights the importance of understanding endothelial cell injury within the context of various diseases and the necessity for innovative therapeutic methods to improve patient outcomes.

Activating Sig-1R inhibits microvascular permeability by reducing LRRK2 expression in lipopolysaccharide-induced acute lung injury

BACKGROUND

Endothelial cells are the first and most damaged target cells during acute lung injury (ALI). Endothelial dysfunction increases pulmonary microvascular permeability, subsequently leading to pulmonary oedema and organ dysfunction; however, clinical treatments against microvascular permeability show poor efficacy. Herein, we aimed to explore the role of the Sigma-1 receptor (Sig-1R) in pulmonary microvascular permeability by constructing ALI animal and cell models, and further investigated the specific mechanisms.

METHODS

The effects of Sig-1R on lung injury and endothelial barrier disruption were examined in lipopolysaccharide (LPS)-induced mice and human umbilical vein endothelial cells (HUVECs), respectively. Transcriptome sequencing was carried out to identify possible targets of Sig-1R, and the specific mechanisms of Sig-1R action were investigated using RNA interference and plasmid transfection.

RESULTS

Analysis of a Gene expression omnibus dataset suggested that Sig-1R plays a protective role against vascular hyperpermeability in ALI. Downregulation of Sig-1R expression and endothelial barrier disruption were both observed in mice and HUVECs upon LPS stimulation. Sig-1R agonists attenuated vascular hyperpermeability in vivo and in vitro, further improving ALI. Sig-1R activation downregulated Leucine-rich repeat kinase 2 (LRRK2) expression in mice and HUVECs. LRRK2 knockdown ameliorated endothelial barrier disruption in mice and HUVECs. Overexpression of LRRK2 reversed the protective effect of Sig-1R activation on LPS-induced endothelial hyperpermeability. Furthermore, Sig1r knockdown exacerbated LPS-induced microvascular hyperpermeability, which was rescued by inhibition of LRRK2.

CONCLUSIONS

Sig-1R activation exerts a protective effect against LPS-induced microvascular hyperpermeability by downregulating LRRK2 expression, which could lead to the development of novel therapeutic strategies for treating ALI.

Pim-1 kinase protects the liver from ischemia reperfusion injury by regulating dynamics-related protein 1

Hepatic ischemia-reperfusion (IR) injury significantly impacts liver transplantation success, yet current treatments remain inadequate. This study explores the role of Proto-oncogene serine/threonine-protein kinase (Pim-1) in liver IR, an area previously unexplored. Utilizing a mouse liver IR in vivo model and a MIHA cell hypoxia-reoxygenation in vitro model, we observed that Pim-1 expression increases following IR, inversely correlating with serum alanine aminotransferase (ALT) and aspartate aminotransferase (AST) levels. Increased Pim-1 expression stabilizes mitochondrial membranes by modifying Drp1 phosphorylation, reducing mitochondrial fission and apoptosis, thereby mitigating liver damage. Additionally, we discovered that elevated Pim-1 expression is dependent on the trimethylation of histone H3 lysine 9 during liver IR. These findings underscore the importance and potential clinical application of targeting Pim-1 in treating hepatic IR, presenting a novel therapeutic avenue.

The mitochondrial quality control system: a new target for exercise therapeutic intervention in the treatment of brain insulin resistance-induced neurodegeneration in obesity

Obesity is a major global health concern because of its strong association with metabolic and neurodegenerative diseases such as diabetes, dementia, and Alzheimer's disease. Unfortunately, brain insulin resistance in obesity is likely to lead to neuroplasticity deficits. Since the evidence shows that insulin resistance in brain regions abundant in insulin receptors significantly alters mitochondrial efficiency and function, strategies targeting the mitochondrial quality control system may be of therapeutic and practical value in obesity-induced cognitive decline. Exercise is considered as a powerful stimulant of mitochondria that improves insulin sensitivity and enhances neuroplasticity. It has great potential as a non-pharmacological intervention against the onset and progression of obesity associated neurodegeneration. Here, we integrate the current knowledge of the mechanisms of neurodegenration in obesity and focus on brain insulin resistance to explain the relationship between the impairment of neuronal plasticity and mitochondrial dysfunction. This knowledge was synthesised to explore the exercise paradigm as a feasible intervention for obese neurodegenration in terms of improving brain insulin signals and regulating the mitochondrial quality control system.

The mitochondrial signature of cultured endothelial cells in sepsis: Identifying potential targets for treatment

Sepsis is the most common cause of death from infection in the world. Unfortunately, there is no specific treatment for patients with sepsis, and management relies on infection control and support of organ function. A better understanding of the underlying pathophysiology of this syndrome will help to develop innovative therapies. In this regard, it has been widely reported that endothelial cell activation and dysfunction are major contributors to the development of sepsis. This review aims to provide a comprehensive overview of emerging findings highlighting the prominent role of mitochondria in the endothelial response in in vitro experimental models of sepsis. Additionally, we discuss potential mitochondrial targets that have demonstrated protective effects in preclinical investigations against sepsis. These promising findings hold the potential to pave the way for future clinical trials in the field.

Polydatin improves vascular endothelial function by maintaining mitochondrial homeostasis under high glucose conditions

Previous studies have shown that polydatin (Poly) confer cardioprotective effects. However, its underlying mechanisms remain elusive. This study showed that Poly (10 µM) treatment reversed the high glucose (HG)-induced decrease in acetylcholine-elicited vasodilation in aortas. Poly also improved the acetylcholine-induced vasodilation of aortic vessels isolated from diabetic rats. Meanwhile, Poly ameliorated the morphological damage of the thoracic aorta and improved the viability of HUVECs under HG conditions. Furthermore, analysis of the vasoprotective effect of Poly under HG conditions by transmission electron microscopy, Western blotting, and qPCR revealed that Poly improved endothelial pyroptosis through the NLRP3/Caspase/1-IL-1β pathway, enhanced dynamin-related protein 1-mediated mitochondrial fission, and increased the mitochondrial membrane potential under HG conditions. In conclusion, Poly restored acetylcholine-induced vasodilation impaired by HG incubation, which was associated with reduced oxidation, inflammation, and pyroptosis, the recovery of the mitochondrial membrane potential and maintenance of mitochondrial dynamic homeostasis of endothelial cells in the aortas.

DRP1 knockdown and atorvastatin alleviate ox-LDL-induced vascular endothelial cells injury: DRP1 is a potential target for preventing atherosclerosis

Vascular endothelial cells (VECs) injury is the first step in the pathogenesis of atherosclerosis (AS). Mitochondrial dysfunction plays a significant role in VECs injury, but the underlying mechanisms are still unclear. Here, the human umbilical vein endothelial cells were exposed to 100 μg/mL oxidized low-density lipoprotein for 24 h to establish AS model in vitro. We reported that mitochondrial dynamics disorder is a prominent feature of VECs in AS models and associated with mitochondrial dysfunction. Moreover, the knockdown of dynamin-related protein 1 (DRP1) in AS model significantly alleviated the mitochondrial dynamics disorder and VECs injury. On the contrary, DRP1 overexpression significantly aggravated this injury. Interestingly, atorvastatin (ATV), a classical anti-atherosclerotic drug, prominently inhibited the expression of DRP1 in AS models and similarly alleviated the mitochondrial dynamics disorder and VECs injury in vitro and in vivo. At the same time, we found that ATV alleviated VECs damage but did not significantly reduce lipid concentration in vivo. Our findings provide a potential therapeutic target of AS and a new mechanism of the anti-atherosclerotic effect of ATV.

Trimethylamine-N-oxide (TMAO) promotes balloon injury-induced neointimal hyperplasia via upregulating Beclin1 and impairing autophagic flux

BACKGROUND AND AIMS

TMAO is a microbiota-dependent metabolite associated with increased risk of various cardiovascular diseases. However, the relationship between TMAO and vascular injury-related neointimal hyperplasia is unclear. This study aimed to explore whether TMAO promotes neointimal hyperplasia after balloon injury and elucidate the underlying mechanism.

METHODS AND RESULTS

Through hematoxylin and eosin staining and immunohistochemistry staining, we found that supplementary TMAO promoted balloon injury-induced neointimal hyperplasia, while reducing TMAO by antibiotic administration produced the opposite result. TMAO showed limited effect on rat aortic vascular smooth muscle cells (RAOSMCs) proliferation and migration. However, TMAO notably induced dysfunction of rat aortic vascular endothelial cells (RAOECs) in vitro and attenuated reendothelialization of carotid arteries after balloon injury in vivo. Autophagic flux was measured by fluorescent mRFP-GFP-LC3, transmission electron microscopy, and western blot. TMAO impaired autophagic flux, as evidenced by the accumulation of p62 and LC3II and high autophagosome to autolysosome ratios. Furthermore, we confirmed that Beclin1 level increased in TMAO-treated RAOECs and carotid arteries. Knocking down Beclin1 alleviated TMAO-induced autophagic flux impairment and neointimal hyperplasia.

CONCLUSIONS

TMAO promoted neointimal hyperplasia through Beclin1-induced autophagic flux blockage, suggesting that TMAO is a potential target for improvement of vascular remodeling after injury.

Differential Transcriptomic Profiles Following Stimulation with Lipopolysaccharide in Intestinal Organoids from Dogs with Inflammatory Bowel Disease and Intestinal Mast Cell Tumor

Lipopolysaccharide (LPS) is associated with chronic intestinal inflammation and promotes intestinal cancer progression in the gut. While the interplay between LPS and intestinal immune cells has been well-characterized, little is known about LPS and the intestinal epithelium interactions. In this study, we explored the differential effects of LPS on proliferation and the transcriptome in 3D enteroids/colonoids obtained from dogs with naturally occurring gastrointestinal (GI) diseases including inflammatory bowel disease (IBD) and intestinal mast cell tumor. The study objective was to analyze the LPS-induced modulation of signaling pathways involving the intestinal epithelia and contributing to colorectal cancer development in the context of an inflammatory (IBD) or a tumor microenvironment. While LPS incubation resulted in a pro-cancer gene expression pattern and stimulated proliferation of IBD enteroids and colonoids, downregulation of several cancer-associated genes such as Gpatch4, SLC7A1, ATP13A2, and TEX45 was also observed in tumor enteroids. Genes participating in porphyrin metabolism (CP), nucleocytoplasmic transport (EEF1A1), arachidonic acid, and glutathione metabolism (GPX1) exhibited a similar pattern of altered expression between IBD enteroids and IBD colonoids following LPS stimulation. In contrast, genes involved in anion transport, transcription and translation, apoptotic processes, and regulation of adaptive immune responses showed the opposite expression patterns between IBD enteroids and colonoids following LPS treatment. In brief, the crosstalk between LPS/TLR4 signal transduction pathway and several metabolic pathways such as primary bile acid biosynthesis and secretion, peroxisome, renin-angiotensin system, glutathione metabolism, and arachidonic acid pathways may be important in driving chronic intestinal inflammation and intestinal carcinogenesis.

Empagliflozin attenuates cardiac microvascular ischemia/reperfusion through activating the AMPKα1/ULK1/FUNDC1/mitophagy pathway

Mitophagy preserves microvascular structure and function during myocardial ischemia/reperfusion (I/R) injury. Empagliflozin, an anti-diabetes drug, may also protect mitochondria. We explored whether empagliflozin could reduce cardiac microvascular I/R injury by enhancing mitophagy. In mice, I/R injury induced luminal stenosis, microvessel wall damage, erythrocyte accumulation and perfusion defects in the myocardial microcirculation. Additionally, I/R triggered endothelial hyperpermeability and myocardial neutrophil infiltration, which upregulated adhesive factors and endothelin-1 but downregulated vascular endothelial cadherin and endothelial nitric oxide synthase in heart tissue. In vitro, I/R impaired the endothelial barrier function and integrity of cardiac microvascular endothelial cells (CMECs), while empagliflozin preserved CMEC homeostasis and thus maintained cardiac microvascular structure and function. I/R activated mitochondrial fission, oxidative stress and apoptotic signaling in CMECs, whereas empagliflozin normalized mitochondrial fission and fusion, neutralized supraphysiologic reactive oxygen species concentrations and suppressed mitochondrial apoptosis. Empagliflozin exerted these protective effects by activating FUNDC1-dependent mitophagy through the AMPKα1/ULK1 pathway. Both in vitro and in vivo, genetic ablation of AMPKα1 or FUNDC1 abolished the beneficial effects of empagliflozin on the myocardial microvasculature and CMECs. Taken together, the preservation of mitochondrial function through an activation of the AMPKα1/ULK1/FUNDC1/mitophagy pathway is the working mechanism of empagliflozin in attenuating cardiac microvascular I/R injury.

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Empagliflozin reduces I/R-induced microvascular damage.

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Empagliflozin suppresses I/R-induced endothelial cell damage.

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Empagliflozin activates FUNDC1-dependent mitophagy through the AMPKα1/ULK1 pathway.

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Ablation of FUNDC1 or AMPKα1 abolishes the protective effects of empagliflozin against I/R-induced microvascular damage.

Zonisamide Ameliorates Microglial Mitochondriopathy in Parkinson’s Disease Models

Mitochondrial dysfunction and exacerbated neuroinflammation are critical factors in the pathogenesis of both familial and non-familial forms of Parkinson’s disease (PD). This study aims to understand the possible ameliorative effects of zonisamide on microglial mitochondrial dysfunction in PD. We prepared 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine and lipopolysaccharide (LPS) co-treated mouse models of PD to investigate the effects of zonisamide on mitochondrial reactive oxygen species generation in microglial cells. Consequently, we utilised a mouse BV2 cell line that is commonly used for microglial studies to determine whether zonisamide could ameliorate LPS-treated mitochondrial dysfunction in microglia. Flow cytometry assay indicated that zonisamide abolished microglial reactive oxygen species (ROS) generation in PD models. Extracellular flux assays showed that LPS exposure to BV2 cells at 1 μg/mL drastically reduced the mitochondrial oxygen consumption rate (OCR) and extracellular acidification rate (ECAR). Zonisamide overcame the inhibitory effects of LPS on mitochondrial OCR. Our present data provide novel evidence on the ameliorative effect of zonisamide against microglial mitochondrial dysfunction and support its clinical use as an antiparkinsonian drug.

Endothelial Dysfunction in Atherosclerotic Cardiovascular Diseases and Beyond: From Mechanism to Pharmacotherapies

The endothelium, a cellular monolayer lining the blood vessel wall, plays a critical role in maintaining multiorgan health and homeostasis. Endothelial functions in health include dynamic maintenance of vascular tone, angiogenesis, hemostasis, and the provision of an antioxidant, anti-inflammatory, and antithrombotic interface. Dysfunction of the vascular endothelium presents with impaired endothelium-dependent vasodilation, heightened oxidative stress, chronic inflammation, leukocyte adhesion and hyperpermeability, and endothelial cell senescence. Recent studies have implicated altered endothelial cell metabolism and endothelial-to-mesenchymal transition as new features of endothelial dysfunction. Endothelial dysfunction is regarded as a hallmark of many diverse human panvascular diseases, including atherosclerosis, hypertension, and diabetes. Endothelial dysfunction has also been implicated in severe coronavirus disease 2019. Many clinically used pharmacotherapies, ranging from traditional lipid-lowering drugs, antihypertensive drugs, and antidiabetic drugs to proprotein convertase subtilisin/kexin type 9 inhibitors and interleukin 1β monoclonal antibodies, counter endothelial dysfunction as part of their clinical benefits. The regulation of endothelial dysfunction by noncoding RNAs has provided novel insights into these newly described regulators of endothelial dysfunction, thus yielding potential new therapeutic approaches. Altogether, a better understanding of the versatile (dys)functions of endothelial cells will not only deepen our comprehension of human diseases but also accelerate effective therapeutic drug discovery. In this review, we provide a timely overview of the multiple layers of endothelial function, describe the consequences and mechanisms of endothelial dysfunction, and identify pathways to effective targeted therapies. SIGNIFICANCE STATEMENT: The endothelium was initially considered to be a semipermeable biomechanical barrier and gatekeeper of vascular health. In recent decades, a deepened understanding of the biological functions of the endothelium has led to its recognition as a ubiquitous tissue regulating vascular tone, cell behavior, innate immunity, cell-cell interactions, and cell metabolism in the vessel wall. Endothelial dysfunction is the hallmark of cardiovascular, metabolic, and emerging infectious diseases. Pharmacotherapies targeting endothelial dysfunction have potential for treatment of cardiovascular and many other diseases.

Dual Role of Mitophagy in Cardiovascular Diseases

ABSTRACT

Mitophagy is involved in the development of various cardiovascular diseases, such as atherosclerosis, heart failure, myocardial ischemia/reperfusion injury, and hypertension. Mitophagy is essential for maintaining intracellular homeostasis and physiological function in most cardiovascular origin cells, such as cardiomyocytes, endothelial cells, and vascular smooth muscle cells. Mitophagy is crucial to ensuring energy supply by selectively removing dysfunctional mitochondria, maintaining a balance in the number of mitochondria in cells, ensuring the integrity of mitochondrial structure and function, maintaining homeostasis, and promoting cell survival. Substantial research has indicated a "dual" effect of mitophagy on cardiac function, with inadequate and increased mitochondrial degradation both likely to influence the progression of cardiovascular disease. This review summarizes the main regulatory pathways of mitophagy and emphasizes that an appropriate amount of mitophagy can prevent endothelial cell injury, vascular smooth muscle cell proliferation, macrophage polarization, and cardiomyocyte apoptosis, avoiding further progression of cardiovascular diseases.