Epigenetics enters the stage in vascular malformations.

Cerebral arteriovenous malformations represent the most common form of vascular malformations and can cause recurrent bleeding and hemorrhagic stroke. The current issue of the JCI features an article by Zhao et al. describing a mouse model of cerebral arteriovenous malformations. Endothelial cells lacking matrix Gla protein, a BMP inhibitor, underwent epigenetic changes characteristic of an endothelial-to-mesenchymal fate transition. The authors uncovered a two-step process for this transition controlled by the epigenetic regulator histone deacetylase 2 (HDAC2), which controls endothelial cell differentiation, and by enhancer of zeste homolog 1 (EZH1), which suppressed mesenchymal fate. This discovery provides a promising entry point for preventive pharmacological interventions.

FLI-1-driven regulation of endothelial cells in human diseases.

Endothelial cells (ECs) are widely distributed in the human body and play crucial roles in the circulatory and immune systems. ECs dysfunction contributes to the progression of various chronic cardiovascular, renal, and metabolic diseases. As a key transcription factor in ECs, FLI-1 is involved in the differentiation, migration, proliferation, angiogenesis and blood coagulation of ECs. Imbalanced FLI-1 expression in ECs can lead to various diseases. Low FLI-1 expression leads to systemic sclerosis by promoting fibrosis and vascular lesions, to pulmonary arterial hypertension by promoting a local inflammatory state and vascular lesions, and to tumour metastasis by promoting the EndMT process. High FLI-1 expression leads to lupus nephritis by promoting a local inflammatory state. Therefore, FLI-1 in ECs may be a good target for the treatment of the abovementioned diseases. This comprehensive review provides the first overview of FLI-1-mediated regulation of ECs processes, with a focus on its influence on the abovementioned diseases and existing FLI-1-targeted drugs. A better understanding of the role of FLI-1 in ECs may facilitate the design of more effective targeted therapies for clinical applications, particularly for tumour treatment.

Cell Death in Pulmonary Arterial Hypertension.

Pulmonary arterial hypertension (PAH) is a severe pulmonary vascular disease characterized by increased pulmonary vascular resistance because of vascular remodeling and vasoconstriction. Subsequently, PAH leads to right ventricular hypertrophy and heart failure. Cell death mechanisms play a significant role in development and tissue homeostasis, and regulate the balance between cell proliferation and differentiation. Several basic and clinical studies have demonstrated that multiple mechanisms of cell death, including pyroptosis, apoptosis, autophagy, ferroptosis, anoikis, parthanatos, and senescence, are closely linked with the pathogenesis of PAH. This review summarizes different cell death mechanisms involved in the death of pulmonary artery smooth muscle cells (PASMCs) and pulmonary artery endothelial cells (PAECs), the primary target cells in PAH. This review summarizes the role of these cell death mechanisms, associated signaling pathways, unique effector molecules, and various pro-survival or reprogramming mechanisms. The aim of this review is to summarize the currently known molecular mechanisms underlying PAH. Further investigations of the cell death mechanisms may unravel new avenues for the prevention and treatment of PAH.

Spock2 Functions as a Key Time-Series Gene of Endothelial Cells in Sepsis-Induced Cardiomyopathy.

ABSTRACT: The study aimed to investigate the pathogenesis of sepsis-induced cardiomyopathy, a leading cause of mortality in septic patients. Transcriptome data from cecal ligation and puncture-induced septic mice were analyzed at different time points (24, 48, and 72 hours) using GSE171546 data. Through weighted gene co-expression network analysis, time series, and differential expression analyses, key time-series differentially expressed genes were identified. In addition, single-cell sequencing data (GSE207363) were used for both differential and pseudotime analyses to pinpoint differentially expressed genes specific to endothelial cells. The study highlighted Spock2, S100a9, S100a8, and Xdh as differential genes specific to endothelial cells in a time-dependent manner. Immunofluorescence validation confirmed the increased expression of SPOCK2 in the endothelial cells of cecal ligation and puncture-induced septic mice. Furthermore, in vitrostudies showed that deletion of Spock2 significantly increased LPS-induced apoptosis and necrosis in human umbilical vein endothelial cells. In conclusion, SPOCK2 expression was increased in septic cardiac endothelial cells and LPS-induced human umbilical vein endothelial cells and may play a protective role.

miRNA-Driven Regulation of Endothelial-to-Mesenchymal Transition Differs among Thoracic Aortic Aneurysms.

Thoracic aortic aneurysms (TAAs) represent a serious health concern, as they are associated with early aortic dissection and rupture. TAA formation is triggered by genetic conditions, in particular Marfan syndrome (MFS) and bicuspid aortic valve (BAV). During the aneurysmatic process, aortic endothelial cells can undergo endothelial-to-mesenchymal transition (End-MT) with consequent phenotypic and functional alterations. We previously documented that MFS TAA is characterized by miR-632-driven End-MT exacerbation, whereas in BAV aortopathy, the occurrence of this process remains still controversial. We investigated the End-MT process and the underlined regulatory mechanisms in BAV, TAV and MFS TAA tissues. Gene expression and immunohistochemical analysis were performed in order to analyze some important miRNAs and genes characterizing End-MT. We documented that BAV endothelium maintains the expression of the endothelial homeostasis markers, such as ERG, CD31 and miR-126-5p, while it shows lower levels of miR-632 and mesenchymal markers compared with MFS. Interestingly, we also found higher levels of miR-632 in MFS patients' blood. Our findings definitively demonstrate that the End-MT process does not characterize BAV that, among the other TAAs, better maintains the endothelial features. In addition, our results suggest miR-632 as a promising diagnostic/prognostic factor in MFS aortopathy.

The Future of Kawasaki Disease Diagnosis: Liquid Biopsy May Hold the Key.

Kawasaki disease (KD) is a febrile illness characterised by systemic inflammation of small- and medium-sized blood vessels, which commonly occurs in young children. Although self-limiting, there is a risk of developing coronary artery lesions as the disease progresses, with delay in diagnosis and treatment. Unfortunately, the diagnosis of KD continues to remain a clinical dilemma. Thus, this article not only summarises the key research gaps associated with KD, but also evaluates the possibility of using circulating endothelial injury biomarkers, such as circulating endothelial cells, endothelial microparticles and vascular endothelial cell-free DNA, as diagnostic and prognostic tools for KD: a "liquid biopsy" approach. The challenges of translating liquid biopsies to use in KD and the opportunities for improvement in its diagnosis and management that such translation may provide are discussed. The use of endothelial damage markers, which are easily obtained via blood collection, as diagnostic tools is promising, and we hope this will be translated to clinical applications in the near future.

Aging kidneys reveal underlying mechanisms of endothelial dysfunction.

Jiang et al. show that zinc finger FYVE-type containing 21, a Rab5 effector in glomerular endothelial cells is involved in the maintenance of glomerular filtration barrier homeostasis through the stabilization of activated endothelial nitric oxide synthase on subcellular vesicles. The study demonstrates that zinc finger FYVE-type containing 21 could modulate the levels of caveolin-1 in glomerular endothelial cells using vesicle-based trafficking, thereby supporting endothelial nitric oxide synthase activity. The authors provide evidence that decreased zinc finger FYVE-type containing 21 expression in glomerular endothelial cells could play a role in aging-related glomerular filtration barrier dysfunction.

Cellular senescence in the pathogenesis of pulmonary arterial hypertension: the good, the bad and the uncertain.

Senescence refers to a cellular state marked by irreversible cell cycle arrest and the secretion of pro-inflammatory and tissue-remodeling factors. The senescence associated secretory phenotype (SASP) impacts the tissue microenvironment and provides cues for the immune system to eliminate senescent cells (SCs). Cellular senescence has a dual nature; it can be beneficial during embryonic development, tissue repair, and tumor suppression, but it can also be detrimental in the context of chronic stress, persistent tissue injury, together with an impairment in SC clearance. Recently, the accumulation of SCs has been implicated in the pathogenesis of pulmonary arterial hypertension (PAH), a progressive condition affecting the pre-capillary pulmonary arterial bed. PAH is characterized by endothelial cell (EC) injury, inflammation, and proliferative arterial remodeling, which leads to right heart failure and premature mortality. While vasodilator therapies can improve symptoms, there are currently no approved treatments capable of reversing the obliterative arterial remodeling. Ongoing endothelial injury and dysfunction is central to the development of PAH, perpetuated by hemodynamic perturbation leading to pathological intimal shear stress. The precise role of senescent ECs in PAH remains unclear. Cellular senescence may facilitate endothelial repair, particularly in the early stages of disease. However, in more advanced disease the accumulation of senescent ECs may promote vascular inflammation and occlusive arterial remodeling. In this review, we will examine the evidence that supports a role of endothelial cell senescence to the pathogenesis of PAH. Furthermore, we will compare and discuss the apparent contradictory outcomes with the use of interventions targeting cellular senescence in the context of experimental models of pulmonary hypertension. Finally, we will attempt to propose a framework for the understanding of the complex interplay between EC injury, senescence, inflammation and arterial remodeling, which can guide further research in this area and the development of effective therapeutic strategies.

Mycoplasma pneumoniae-induced Kawasaki disease via PINK1/Parkin-mediated mitophagy.

Kawasaki disease (KD) is a systemic vasculitis with an unknown cause that primarily affects children. The objective of this study was to explore the function and underlying mechanism of mitophagy in Mycoplasma pneumoniae (MP)-induced KD. To create MP-induced KD models, Human coronary endothelial cells (HCAECs) and DBA/2 mice were employed and treated with Mp-Lipid-associated membrane proteins （LAMPs）. Lactate dehydrogenase (LDH) levels were tested to determine cellular damage or death. The inflammatory cytokines tumor necrosis factor (TNF)--α and interleukin (IL)-6 were measured using the Enzyme-Linked Immunosorbent Assay (ELISA) method. RT-qPCR and Western blotting were used to determine the expression of Intercellular Adhesion Molecule(ICAM)-1, vascular cell adhesion molecule (VCAM)-1, inducible nitric oxide synthase(iNOS), LC3, p62, PINK1(a mitochondrial serine/threonine-protein kinase), and PARKIN(a cytosolic E3-ubiquitin ligase). The adenosine triphosphate （ATP）, reactive oxygen species （ROS）, and mitochondrial membrane potential（MMP） levels were measured to determine mitochondrial function. Mitophagy was investigated using immunofluorescence and a mitophagy detection test. Autophagosome and mitochondrial morphology were examined using transmission electron microscopy. To identify inflammatory cell infiltration, hematoxylin and eosin staining was utilized. Mp-LAMPs increased the levels of TNF-α, IL-6, ICAM-1, VCAM-1, and iNOS in an HCAEC cell model, along with LDH release. After Mp-LAMPs exposure, there was a rise in LC3 and a reduction in p62. Meanwhile, the expression of PINK1 and Parkin was increased. Cyclosporin A dramatically increased ATP synthesis and MMP in HCAEC cells treated with Mp-LAMPs, while suppressing ROS generation, demonstrating excessive mitophagy-related mitochondrial dysfunction. Additionally, neither body weight nor artery tissue were affected due to PINK1 and Parkin suppression Cyclosporin A in Mp-LAMPs-treated mice. These findings indicated that PINK1/Parkin-mediated mitophagy inhibition may be a therapeutic target for MP-induced KD.

Endothelial cell heterogeneity in colorectal cancer: tip cells drive angiogenesis.

This study aims to uncover the heterogeneity of endothelial cells (ECs) in colorectal cancer (CRC) and their crucial role in angiogenesis, with a special focus on tip cells. Using single-cell RNA sequencing to profile ECs, our data suggests that CRC ECs predominantly exhibit enhanced angiogenesis and decreased antigen presentation, a shift in phenotype largely steered by tip cells. We also observed that an increase in the density and proportion of tip cells correlates with CRC occurrence, progression, and poorer patient prognosis. Furthermore, we identified endothelial cell-specific molecule 1 (ESM1), specifically expressed in tip cells, sustains a VEGFA-KDR-ESM1 positive feedback loop, promoting angiogenesis and CRC proliferation and migration. We also found the enrichment of KDR in tip cells and spotlight a unique long-tail effect in VEGFA expression: while VEGFA is primarily expressed by epithelial cells, the highest level of VEGFA expression is found in individual myeloid cells. Moreover, we observed that effective PD-1 blockade immunotherapy significantly reduced tip cells, disrupting the VEGFA-KDR-ESM1 positive feedback loop in the process. Our investigation into the heterogeneity of ECs in CRC at a single-cell level offers important insights that may contribute to the development of more effective immunotherapies targeting tip cells in CRC.

Myelin endocytosis by brain endothelial cells causes endothelial iron overload and oligodendroglial iron hunger in hypoperfusion-induced white matter injury.

AIMS: Hypoperfusion induces significant white matter injury in cerebral vascular disorders, including arteriosclerotic cerebral small vessel disease (aCSVD), which is prevalent among the elderly. Iron transport by blood vessel endothelial cells (BVECs) from the periphery supports oligodendrocyte maturation and white matter repair. This study aims to elucidate the association between iron homeostasis changes and white matter injury severity, and explore the crosstalk between BVECs and oligodendroglial lineage cells. METHODS: In vivo: C57BL/6 mice were subjected to unilateral common carotid artery occlusion (UCCAO). In vitro: BVECs with myelin pretreatment were co-cultured with oligodendrocyte progenitor cells (OPCs) or organotypic cerebellar slices subjected to oxygen and glucose deprivation. RESULTS: Circulatory iron tends to be stored in aCSVD patients with white matter injury. Myelin debris endocytosis by BVECs impairs iron transport, trapping iron in the blood and away from the brain, worsening oligodendrocyte iron deficiency in hypoperfusion-induced white matter injury. Iron accumulation in BVECs triggers ferroptosis, suppressing iron transport and hindering white matter regeneration. Intranasal holo-transferrin (hTF) administration bypassing the BBB alleviates oligodendrocyte iron deficiency and promotes myelin regeneration in hypoperfusion-induced white matter injury. CONCLUSION: The iron imbalance between BVECs and oligodendroglial lineage cells is a potential therapeutic target in hypoperfusion-induced white matter injury.

Unveiling the role of RhoA and ferroptosis in vascular permeability: Implications for osteoarthritis.

Abnormal angiogenesis and increased vascular permeability of subchondral bone are key mechanisms related to osteoarthritis (OA). However, the precise mechanisms responsible for heightened vascular permeability in OA remain unclear. The present study used proteomics to identify protein expression in damaged subchondral bone compared with normal subchondral bone. The results suggest that Ras homolog family member A (RhoA) may be associated with the vascular permeability of subchondral bone and ferroptosis in OA. The results of analysis of clinical samples indicated a significant increase in expression of RhoA in the subchondral bone of OA. This were consistent with the proteomics findings. We found through western blotting, RT­PCR, and immunofluorescence that RhoA significantly increased the permeability of endothelial cells (ECs) by inhibiting inter­EC adhesion proteins (zona occludens­1, connexin 43 and Vascular endothelial­Cadherin) and actin filaments. Furthermore, RhoA induced ferroptosis core proteins (glutathione peroxidase 4,  solute carrier family 7 member 11 and acyl­CoA synthase long­chain family member 4, ACSL4) by influencing lipid peroxidation and mitochondrial function, leading to ferroptosis of ECs. This suggested an association between RhoA, ferroptosis and vascular permeability. Ferroptosis significantly increased permeability of ECs by inhibiting inter­EC adhesion proteins. RhoA increased vascular permeability by inducing ferroptosis of ECs. In vivo, inhibition of RhoA and ferroptosis significantly mitigated progression of OA by alleviating cartilage degeneration and subchondral bone remodeling in mice with destabilization of the medial meniscus. In conclusion, the present findings indicated that RhoA enhanced vascular permeability in OA by inducing ferroptosis. This may serve as a novel strategy for the early prevention and treatment of OA.

HCC-1 Accelerates Atherosclerosis by Inducing Endothelial Cell and Macrophage Pyroptosis and Serves as an Early Diagnostic Biomarker.

BACKGROUND: HCC-1 (hemofiltrate CC chemokine-1), a CC-type chemokine, exerts function to change intracellular calcium concentration, induce leukocyte, and manipulate enzyme release especially in monocytes. It has been reported that HCC-1 can predict the persistent acute kidney injury or suppress hepatocellular carcinoma by modulating cell cycle and promoting apoptosis; however, the effect of HCC-1 on atherosclerosis is poorly understood. Here, we aimed to clarify the function and mechanism of HCC-1 in atherosclerosis and whether it could serve as a novel biomarker for the diagnosis of atherosclerosis. METHODS: HCC-1 expression in serum, atherosclerotic plaques, and normal arterial tissue from patients with atherosclerosis and control group was assessed by ELISA, immunohistochemistry and confocal microscope, and bioinformatic analysis. The atherosclerotic model of HCC-1 overexpressing and control mice was generated by tail vein injection of adeno-associated virus serotype 9-HCC-1 on an ApoE-/- background. Cell adhesion, polarization, and pyroptosis were evaluated in vitro. The relationship between HCC-1 concentration in serum and atherosclerosis was analyzed in patients with atherosclerosis. RESULTS: HCC-1 expression was positively correlated with the occurrence and stable-unstable switch of atherosclerosis under bioinformatic analysis, which is further supported by the results of increased HCC-1 expression in atherosclerosis patients both in serum and atherosclerotic plaque. adeno-associated virus serotype 9-HCC-1 mice had higher levels of inflammatory factors, increased macrophage accumulation and pyroptotic rate in plaque, and decreased atherosclerotic plaque stability. In vitro, HCC-1 promoted monocyte adhesion and M1 polarization and induced inflammation and pyroptosis both in endothelial cells and macrophages. CONCLUSIONS: HCC-1 expression was increased in patients with atherosclerosis, and HCC-1 overexpression accelerated atherosclerotic burden via an enhancement in monocyte recruitment, M1 polarization, and pyroptosis both in endothelial cells and macrophages. Our findings suggested that HCC-1 may serve as an early biomarker for the diagnosis of atherosclerosis, with the capacity to reflect the degree of stenosis.

Impaired instructive and protective barrier functions of the endothelial cell glycocalyx pericellular matrix is impacted in COVID-19 disease.

The aim of this study was to review the roles of endothelial cells in normal tissue function and to show how COVID-19 disease impacts on endothelial cell properties that lead to much of its associated symptomatology. This places the endothelial cell as a prominent cell type to target therapeutically in the treatment of this disorder. Advances in glycosaminoglycan analytical techniques and functional glycomics have improved glycosaminoglycan mimetics development, providing agents that can more appropriately target various aspects of the behaviour of the endothelial cell in-situ and have also provided polymers with potential to prevent viral infection. Thus, promising approaches are being developed to combat COVID-19 disease and the plethora of symptoms this disease produces. Glycosaminoglycan mimetics that improve endothelial glycocalyx boundary functions have promising properties in the prevention of viral infection, improve endothelial cell function and have disease-modifying potential. Endothelial cell integrity, forming tight junctions in cerebral cell populations in the blood-brain barrier, prevents the exposure of the central nervous system to circulating toxins and harmful chemicals, which may contribute to the troublesome brain fogging phenomena reported in cognitive processing in long COVID disease.

Senescent endothelial cells promote liver metastasis of uveal melanoma in single-cell resolution.

BACKGROUND: Uveal melanoma (UM), the most common adult intraocular tumor, is characterized by high malignancy and poor prognosis in advanced stages. Angiogenesis is critical for UM development, however, not only the role of vascular endothelial dysfunction in UM remains unknown, but also their analysis at the single-cell level has been lacking. A comprehensive analysis is essential to clarify the role of the endothelium in the development of UM. METHODS: By using single-cell RNA transcriptomics data of 11 cases of primary and liver metastasis UM, we analyzed the endothelial cell status. In addition, we analyzed and validated ECs in the in vitro model and collected clinical specimens. Subsequently, we explored the impact of endothelial dysfunction on UM cell migration and explored the mechanisms responsible for the endothelial cell abnormalities and the reasons for their peripheral effects. RESULTS: UM metastasis has a significantly higher percentage of vascular endothelial cells compared to in situ tumors, and endothelial cells in metastasis show significant senescence. Senescent endothelial cells in metastatic tumors showed significant Krüppel-like factor 4 (KLF4) upregulation, overexpression of KLF4 in normal endothelial cells induced senescence, and knockdown of KLF4 in senescent endothelium inhibited senescence, suggesting that KLF4 is a driver gene for endothelial senescence. KLF4-induced endothelial senescence drove tumor cell migration through a senescence-associated secretory phenotype (SASP), of which the most important component of the effector was CXCL12 (C-X-C motif chemokine ligand 12), and participated in the composition of the immunosuppressive microenvironment. CONCLUSION: This study provides an undesirable insight of senescent endothelial cells in promoting UM metastasis.

Unraveling the molecular architecture of autoimmune thyroid diseases at spatial resolution.

Autoimmune thyroid diseases (AITD) such as Graves' disease (GD) or Hashimoto's thyroiditis (HT) are organ-specific diseases that involve complex interactions between distinct components of thyroid tissue. Here, we use spatial transcriptomics to explore the molecular architecture, heterogeneity and location of different cells present in the thyroid tissue, including thyroid follicular cells (TFCs), stromal cells such as fibroblasts, endothelial cells, and thyroid infiltrating lymphocytes. We identify damaged antigen-presenting TFCs with upregulated CD74 and MIF expression in thyroid samples from AITD patients. Furthermore, we discern two main fibroblast subpopulations in the connective tissue including ADIRF+ myofibroblasts, mainly enriched in GD, and inflammatory fibroblasts, enriched in HT patients. We also demonstrate an increase of fenestrated PLVAP+ vessels in AITD, especially in GD. Our data unveil stromal and thyroid epithelial cell subpopulations that could play a role in the pathogenesis of AITD.

Stretch-induced damage in endothelial monolayers.

Endothelial cells are constantly exposed to mechanical stimuli, of which mechanical stretch has shown various beneficial or deleterious effects depending on whether loads are within physiological or pathological levels, respectively. Vascular properties change with age, and on a cell-scale, senescence elicits changes in endothelial cell mechanical properties that together can impair its response to stretch. Here, high-rate uniaxial stretch experiments were performed to quantify and compare the stretch-induced damage of monolayers consisting of young, senescent, and aged endothelial populations. The aged and senescent phenotypes were more fragile to stretch-induced damage. Prominent damage was detected by immunofluorescence and scanning electron microscopy as intercellular and intracellular void formation. Damage increased proportionally to the applied level of deformation and, for the aged and senescent phenotype, induced significant detachment of cells at lower levels of stretch compared to the young counterpart. Based on the phenotypic difference in cell-substrate adhesion of senescent cells indicating more mature focal adhesions, a discrete network model of endothelial cells being stretched was developed. The model showed that the more affine deformation of senescent cells increased their intracellular energy, thus enhancing the tendency for cellular damage and impending detachment. Next to quantifying for the first-time critical levels of endothelial stretch, the present results indicate that young cells are more resilient to deformation and that the fragility of senescent cells may be associated with their stronger adhesion to the substrate.

Endothelial Autophagy Promotes Atheroprotective Communication Between Endothelial and Smooth Muscle Cells via Exosome-Mediated Delivery of miR-204-5p.

BACKGROUND: Cellular communication among different types of vascular cells is indispensable for maintaining vascular homeostasis and preventing atherosclerosis. However, the biological mechanism involved in cellular communication among these cells and whether this biological mechanism can be used to treat atherosclerosis remain unknown. We hypothesized that endothelial autophagy mediates the cellular communication in vascular tissue through exosome-mediated delivery of atherosclerosis-related genes. METHODS: Rapamycin and adeno-associated virus carrying Atg7 short hairpin RNA under the Tie (TEK receptor tyrosine kinase) promoter were used to activate and inhibit vascular endothelial autophagy in high-fat diet-fed ApoE-/- mice, respectively. miRNA microarray, in vivo and in vitro experiments, and human vascular tissue were used to explore the effects of endothelial autophagy on endothelial function and atherosclerosis and its molecular mechanisms. Quantitative polymerase chain reaction and miRNA sequencing were performed to determine changes in miRNA expression in exosomes. Immunofluorescence and exosome coculture experiments were conducted to examine the role of endothelial autophagy in regulating the communication between endothelial cells and smooth muscle cells (SMCs) via exosomal miRNA. RESULTS: Endothelial autophagy was inhibited in thoracic aortas of high-fat diet-fed ApoE-/- mice. Furthermore, rapamycin alleviated high-fat diet-induced atherosclerotic burden and endothelial dysfunction, while endothelial-specific Atg7 depletion aggravated the atherosclerotic burden. miRNA microarray, in vivo and in vitro experiments, and human vascular tissue analysis revealed that miR-204-5p was significantly increased in endothelial cells after high-fat diet exposure, which directly targeted Bcl2 to regulate endothelial cell apoptosis. Importantly, endothelial autophagy activation decreased excess miR-204-5p by loading miR-204-5p into multivesicular bodies and secreting it through exosomes. Moreover, exosomal miR-204-5p can effectively transport to SMCs, alleviating SMC calcification by regulating target proteins such as RUNX2 (runt-related transcription factor 2). CONCLUSIONS: Our study revealed the exosomal pathway by which endothelial autophagy protects atherosclerosis: endothelial autophagy activation transfers miR-204-5p from endothelial cells to SMCs via exosomes, both preventing endothelial apoptosis and alleviating SMC calcification. REGISTRATION: URL: https://www.chictr.org.cn/; Unique identifier: ChiCTR2200064155.

Krüppel-like factor 2 is an endoprotective transcription factor in diabetic kidney disease.

Diabetic kidney disease (DKD) is a microvascular complication of diabetes, and glomerular endothelial cell (GEC) dysfunction is a key driver of DKD pathogenesis. Krüppel-like factor 2 (KLF2), a shear stress-induced transcription factor, is among the highly regulated genes in early DKD. In the kidney, KLF2 expression is mostly restricted to endothelial cells, but its expression is also found in immune cell subsets. KLF2 expression is upregulated in response to increased shear stress by the activation of mechanosensory receptors but suppressed by inflammatory cytokines, both of which characterize the early diabetic kidney milieu. KLF2 expression is reduced in progressive DKD and hypertensive nephropathy in humans and mice, likely due to high glucose and inflammatory cytokines such as TNF-α. However, KLF2 expression is increased in glomerular hyperfiltration-induced shear stress without metabolic dysregulation, such as in settings of unilateral nephrectomy. Lower KLF2 expression is associated with CKD progression in patients with unilateral nephrectomy, consistent with its endoprotective role. KLF2 confers endoprotection by inhibition of inflammation, thrombotic activation, and angiogenesis, and thus KLF2 is considered a protective factor for cardiovascular disease (CVD). Based on similar mechanisms, KLF2 also exhibits renoprotection, and its reduced expression in endothelial cells worsens glomerular injury and albuminuria in settings of diabetes or unilateral nephrectomy. Thus KLF2 confers endoprotective effects in both CVD and DKD, and its activators could potentially be developed as a novel class of drugs for cardiorenal protection in diabetic patients.