Microvascular Integrity Research Articles

Regional cerebral blood flow reflects both neurodegeneration and microvascular integrity across the Alzheimer's continuum.

Alzheimer's disease (AD) typically involves both neurodegenerative and vascular pathologies, each associated with reductions in cerebral blood flow (CBF). However, it remains unclear whether vascular and neural contributions to regional CBF can be differentiated. Using 3D background-suppressed arterial spin labeled perfusion magnetic resonance imaging, we evaluated regional CBF in a cohort of 257 participants across the AD continuum and assessed the impact of risk factors for both AD and small vessel disease (SVD) on regional CBF. Vascular risk factors (VRFs) were associated with reduced CBF in normal-appearing periventricular white matter, while amyloid positivity was associated with reduced CBF in the posterior cingulate cortex and precuneus. Putative SVD-sensitive regions in white matter exhibited diagnosis-related CBF changes comparable to those in typical AD cortical regions. Spatial patterns of hypoperfusion may differentiate AD and VRF-related effects on regional CBF. Our findings also support the contribution of SVD in AD pathogenesis. We used 3D background-suppressed pCASL MRI to evaluate CBF across the AD continuum. Putative SVD-sensitive regions in white matter exhibited diagnosis-related CBF changes. AD and/or SVD risk correlated with reduced CBF in AD and/or SVD-related regions. VRFs were associated with more widespread CBF reductions than amyloid positivity. Spatial patterns of hypoperfusion may differentiate AD and VRF-related effects.

Increased Levels of Circulating Methylglyoxal Have No Consequence for Cerebral Microvascular Integrity and Cognitive Function in Young Healthy Mice.

Diabetes and other age-related diseases are associated with an increased risk of cognitive impairment, but the underlying mechanisms remain poorly understood. Methylglyoxal (MGO), a by-product of glycolysis and a major precursor in the formation of advanced glycation end-products (AGEs), is increased in individuals with diabetes and other age-related diseases and is associated with microvascular dysfunction. We now investigated whether increased levels of circulating MGO can lead to cerebral microvascular dysfunction, blood-brain barrier (BBB) dysfunction, and cognitive impairment. Mice were supplemented or not with 50mM MGO in drinking water for 13weeks. Plasma and cortical MGO and MGO-derived AGEs were measured with UPLC-MS/MS. Peripheral and cerebral microvascular integrity and inflammation were investigated. Cerebral blood flow and neurovascular coupling were investigated with laser speckle contrast imaging, and cognitive tests were performed. We found a 2-fold increase in plasma MGO and an increase in MGO-derived AGEs in plasma and cortex. Increased plasma MGO did not lead to cerebral microvascular dysfunction, inflammation, or cognitive decline. This study shows that increased concentrations of plasma MGO are not associated with cerebral microvascular dysfunction and cognitive impairment in healthy mice. Future research should focus on the role of endogenously formed MGO in cognitive impairment.

Loss of Nr4a1 ameliorates endothelial cell injury and vascular leakage in lung transplantation from circulatory-death donor

BackgroundIschemia-reperfusion injury (IRI) stands as a major trigger for primary graft dysfunction (PGD) in lung transplantation (LTx). Especially in LTx from donation after cardiac death (DCD), effective control of IRI following warm ischemia (WIRI) is crucial to prevent PGD. This study aimed to identify the key factors affecting WIRI in LTx from DCD. MethodsPreviously reported RNA-sequencing dataset of lung WIRI was reanalyzed to identify nuclear receptor subfamily 4 group A member 1 (NR4A1) as the immediate early gene for WIRI. Dynamics of NR4A1 expression were verified using a mouse hilar clamp model. To investigate the role of NR4A1 in WIRI, a mouse model of LTx from DCD was established using Nr4a1 knockout (Nr4a1-/-) mice. ResultsNR4A1 was located around vascular cells, and its protein levels in the lungs increased rapidly and transiently during WIRI. LTｘ from Nr4a1-/- donors significantly improved pulmonary graft function compared to wild-type donors (P < 0.001). Histological analysis showed decreased microvascular endothelial cell death (P = 0.007), neutrophil infiltration (P < 0.001), and albumin leakage (P < 0.001). Evans blue permeability assay demonstrated maintained pulmonary microvascular barrier integrity in grafts from Nr4a1-/- donors, correlating with diminished pulmonary edema (P < 0.001). However, NR4A1 did not significantly affect the inflammatory response during WIRI, and IRI was not suppressed when a wild-type donor lung was transplanted into the Nr4a1-/- recipient. ConclusionsDonor NR4A1 plays a specialized role in the positive regulation of endothelial cell injury and microvascular hyperpermeability. These findings demonstrate the potential of targeting NR4A1 interventions to alleviate PGD and improve outcomes in LTx from DCD.

Indoxyl sulfate induces retinal microvascular injury via COX-2/PGE2 activation in diabetic retinopathy

BackgroundDiabetic retinopathy (DR), the principal cause of acquired blindness among the working-age population, is the most frequent microvascular complication of diabetes. Although metabolic disorders are hypothesized to play a role in its pathogenesis, the underlying mechanism remains largely elusive.MethodsTo elucidate the mechanism, we initially compared metabolite profiles of vitreous fluid between 23 patients with DR and 12 non-diabetic controls using liquid chromatography/tandem mass spectrometry, identifying the distinct metabolite indoxyl sulfate (IS). Subsequently, streptozotocin (STZ)-induced diabetic and IS-injected rat models were established to examine the effects of IS on retinal microvasculature. RNA sequencing was conducted to identify potential regulatory mechanisms in IS-treated human retinal endothelial cells (HREC). Finally, target gene knockdown in HREC and treatment of IS-injected rats with inhibitors (targeting IS production or downstream regulators) were employed to elucidate the detailed mechanisms and identify therapeutic targets for DR.ResultsMetabolomics identified 172 significantly altered metabolites in the vitreous humor of diabetics, including the dysregulated tryptophan metabolite indoxyl sulfate (IS). IS was observed to breach the blood-retinal barrier and accumulate in the intraocular fluid of diabetic rats. Both in vivo and in vitro experiments indicated that elevated levels of IS induced endothelial apoptosis and disrupted cell junctions. RNA sequencing pinpointed prostaglandin E2 (PGE2) synthetase-cyclooxygenase 2 (COX-2) as a potential target of IS. Validation experiments demonstrated that IS enhanced COX-2 expression, which subsequently increased PGE2 secretion by promoting transcription factor EGR1 binding to COX-2 DNA following entry into cells via organic anion transporting polypeptides (OATP2B1). Furthermore, inhibition of COX-2 in vivo or silencing EGR1/OATP2B1 in HREC mitigated IS-induced microcapillary damage and the activation of COX-2/PGE2.ConclusionOur study demonstrated that indoxyl sulfate (IS), a uremic toxin originating from the gut microbiota product indole, increased significantly and contributed to retinal microvascular damage in diabetic retinopathy (DR). Mechanistically, IS impaired retinal microvascular integrity by inducing the expression of COX-2 and the production of PGE2. Consequently, targeting the gut microbiota or the PGE2 pathway may offer effective therapeutic strategies for the treatment of DR.Graphical

Neferine inhibits BMECs pyroptosis and maintains blood–brain barrier integrity in ischemic stroke by triggering a cascade reaction of PGC-1α

Blood–brain barrier disruption is a critical pathological event in the progression of ischemic stroke (IS). Most studies regarding the therapeutic potential of neferine (Nef) on IS have focused on neuroprotective effect. However, whether Nef attenuates BBB disruption during IS is unclear. We here used mice underwent transient middle cerebral artery occlusion (tMCAO) in vivo and bEnd.3 cells exposed to oxygen–glucose deprivation/reoxygenation (OGD/R) injury in vitro to simulate cerebral ischemia. We showed that Nef reduced neurobehavioral dysfunction and protected brain microvascular endothelial cells and BBB integrity. Molecular docking, short interfering (Si) RNA and plasmid transfection results showed us that PGC-1α was the most binding affinity of biological activity protein for Nef. And verification experiments were showed that Nef upregulated PGC-1α expression to reduce mitochondrial oxidative stress and promote TJ proteins expression, further improves the integrity of BBB in mice. Intriguingly, our study showed that neferine is a natural PGC-1α activator and illustrated the mechanism of specific binding site. Furthermore, we have demonstrated Nef reduced mitochondria oxidative damage and ameliorates endothelial inflammation by inhibiting pyroptosis to improve BBB permeability through triggering a cascade reaction of PGC-1α via regulation of PGC-1α/NLRP3/GSDMD signaling pathway to maintain the integrity of BBB in ischemia/reperfusion injury.

Young blood-mediated cerebromicrovascular rejuvenation through heterochronic parabiosis: enhancing blood-brain barrier integrity and capillarization in the aged mouse brain.

Age-related cerebromicrovascular changes, including blood-brain barrier (BBB) disruption and microvascular rarefaction, play a significant role in the development of vascular cognitive impairment (VCI) and neurodegenerative diseases. Utilizing the unique model of heterochronic parabiosis, which involves surgically joining young and old animals, we investigated the influence of systemic factors on these vascular changes. Our study employed heterochronic parabiosis to explore the effects of young and aged systemic environments on cerebromicrovascular aging in mice. We evaluated microvascular density and BBB integrity in parabiotic pairs equipped with chronic cranial windows, using intravital two-photon imaging techniques. Our results indicate that short-term exposure to young systemic factors leads to both functional and structural rejuvenation of cerebral microcirculation. Notably, we observed a marked decrease in capillary density and an increase in BBB permeability to fluorescent tracers in the cortices of aged mice undergoing isochronic parabiosis (20-month-old C57BL/6 mice [A-(A)]; 6 weeks of parabiosis), compared to young isochronic parabionts (6-month-old, [Y-(Y)]). However, aged heterochronic parabionts (A-(Y)) exposed to young blood exhibited a significant increase in cortical capillary density and restoration of BBB integrity. In contrast, young mice exposed to old blood from aged parabionts (Y-(A)) rapidly developed cerebromicrovascular aging traits, evidenced by reduced capillary density and increased BBB permeability. These findings underscore the profound impact of systemic factors in regulating cerebromicrovascular aging. The rejuvenation observed in the endothelium, following exposure to young blood, suggests the existence of anti-geronic elements that counteract microvascular aging. Conversely, pro-geronic factors in aged blood appear to accelerate cerebromicrovascular aging. Further research is needed to assess whether the rejuvenating effects of young blood factors could extend to other age-related cerebromicrovascular pathologies, such as microvascular amyloid deposition and increased microvascular fragility.

ASSOCIATIONS BETWEEN GENETICALLY PREDICTED PULSE PRESSURE AND TARGET ORGAN DAMAGE: A MENDELIAN RANDOMIZATION STUDY

Objective: Large-artery stiffness (LAS) leads to an increased pulse pressure (PP) and is thought to induce target organ damage (TOD). However, causal associations of PP have not been unequivocally assessed in humans. We aimed to investigate the bi-directional associations between genetically predicted increased PP and phenotypes of TOD using Mendelian randomization (MR). Design and method: Bi-directional MR analyses were performed to investigate associations between genetically predicted PP and: left ventricular mass (LVM), myocardial interstitial fibrosis, heart failure (HF), chronic kidney disease (CKD), cognitive performance, brain white matter hyperintensities (WMH), type 2 diabetes (T2D) and preeclampsia (PrE). Multivariable MR was conducted to investigate the effect of PP on significant outcomes, independently of mean arterial pressure (MAP). Results: For a 10-mmHg increase in genetically-predicted PP, the odds ratios (ORs) were 1.113 (95%CI=1.085-1.137, P&lt;0.001) for HF, 1.075 (95%CI=1.048-1.103, P&lt;0.001) for CKD, 1.137 (95%CI=1.102-1.173, P&lt;0.001) for T2D, and 1.435 (95%CI=1.256-1.638, P&lt;0.001) for PrE. Similarly, a 10-mmHg increase in genetically-predicted PP was associated with a greater LVM (beta estimate=3.527 g/m2, 95%CI=3.026-4.028, P&lt;0.001). The association of genetically predicted PP on risk of HF, CKD and T2D was independent of genetically-predicted MAP. Bidirectional MR also supported a causal effect of genetically predicted log-odds of T2D on PP (beta estimate=0.527 mmHg, 0.396-0.658, P&lt;0.001), and PrE on PP (beta estimate=2.365 mmHg, 0.783-3.947, P=0.003) indicating a potential bidirectional relationship. Conclusions: We provide evidence supporting causal associations between PP and T2D, CKD, HF and increased risk of LV hypertrophy in humans, consistent with the deleterious effects of LAS on LV afterload and on microvascular integrity in low-resistance target organs. Early interventions aimed at lowering LAS may lead to lowering the risk of adverse outcomes.

Bibliometric and visual analysis of ACE2/Ang 1–7/MasR axis in diabetes and its microvascular complications from 2000 to 2023

BackgroundThe pathogenesis of diabetes and its microvascular complications are intimately associated with renin angiotensin system dysregulation. Evidence suggests the angiotensin converting enzyme 2 (ACE2)/angiotensin 1-7 (Ang 1–7)/Mas receptor (MasR) axis regulates metabolic imbalances, inflammatory responses, reduces oxidative stress, and sustains microvascular integrity, thereby strengthening defences against diabetic conditions. This study aims to conduct a comprehensive analysis of the ACE2/Ang 1–7/MasR axis in diabetes and its microvascular complications over the past two decades, focusing on key contributors, research hotspots, and thematic trends. MethodsThis cross-sectional bibliometric analysis of 349 English-language publications was performed using HistCite, VOSviewer, CiteSpace, and Bibliometrix R for visualization and metric analysis. Primary analytical metrics included publication count and keyword trend dynamics. ResultsThe United States, contributing 105 articles, emerged as the most productive country, with the University of Florida leading institutions with 18 publications. Benter IF was the most prolific author with 14 publications, and Clinical Science was the leading journal with 13 articles. A total of 151 of the 527 author's keywords with two or more occurrences clustered into four major clusters: diabetic microvascular pathogenesis, metabolic systems, type 2 diabetes, and coronavirus infections. Keywords such as “SARS”, “ACE2”, “coronavirus”, “receptor” and “infection” displayed the strongest citation bursts. The thematic evolution in this field expanded from focusing on the renin angiotensin system (2002–2009) to incorporating ACE2 and diabetes metabolism (2010–2016). The latter period (2017–2023) witnessed a significant surge in diabetes research, reflecting the impact of COVID-19 and associated conditions such as diabetic retinopathy and cardiomyopathy. ConclusionsThis scientometric study offers a detailed analysis of the ACE2/Ang 1–7/MasR axis in diabetes and its microvascular complications, providing valuable insights for future research directions.

Chronic Estrogen Treatment Promotes Human Microvascular Endothelial Dysfunction Through Sex-Specific Regulation of Ceramide Formation

Risk for cardiovascular disease (CVD) is elevated in individuals assigned female at birth and women of trans experience (assigned male at birth) undergoing long-term estrogen therapy (e.g. contraception, gender-affrmation). We have previously shown that chronic estrogen treatment induces microvascular endothelial dysfunction in human arterioles collected from those assigned male and female at birth. The mechanism via which estrogen causes microvascular damage remains unknown. Estrogen can increase expression of the ceramide-forming enzyme neutral sphingomyelinase (NSmase), and elevated ceramides promote cellular oxidative stress. Together, we hypothesize that estrogen induces microvascular endothelial dysfunction via NSmase-mediated ceramide formation. Human arterioles from otherwise healthy adults were treated with 17β-estradiol (E2; 100nM) +/- NSmase inhibitor (GW4869; 4μM, 24hrs). Vascular response to increasing flow rates was assessed using live videomicroscopy. Sex-specific human umbilical vein endothelial cells were treated with E2+/-GW4869 (48hrs), and H2O2 levels were measured using the fluorescent indicator peroxy yellow 1 (PY1). Endothelial ceramide levels were measured using liquid chromatography, tandem mass spectrometry. Exposure to estrogen impaired dilation to flow in arterioles from those assigned male and female at birth, an effect that was prevented by inhibition of NSmase (%Mean Dilation±SE; E2 vs E2+GW4869; male: 11.20±4.99% vs 48.43±7.15%, n=3 both, p=0.037; female: 1.78±1.99% vs 40.35±8.46%, n=5 both, p=0.006; two-way ANOVA). Estrogen treatment increased endothelial H2O2 production in cells from both sexes which was diminished by GW4869 treatment (%Change from control±SE; E2 vs E2+GW4869; male: 20.90±5.86% vs 2.85±1.99%, n=11 both, p=0.009*; female: 63.33±13.65%, n=10 vs 25.25±7.64%, n=9, p=0.031*, unpaired t-test*). Endothelial long-chain ceramide levels were higher in cells from biological males compared to females (pmol/nmol phosphate; male 5.90±2.19, n=4 vs female 2.18±0.86, n=5; p=0.009*). While estrogen treatment increased cellular ceramides in both sexes, ceramide accumulation was greater in cells from biological males compared to females (%change from baseline: 65.97±53.64% vs 6.08±7.86%, p=0.041*). Together, these results show that estrogen-induced microvascular endothelial dysfunction can be prevented through inhibition of NSmase-mediated ceramide formation. There is also notable sexual dimorphism in endothelial ceramide levels both at baseline and in response to estrogen. This study offers mechanistic insight into how chronic estrogen therapy may contribute to microvascular dysfunction and elevate the risk of CVD in patients. Furthermore, it presents the inhibition of NSmase as a plausible therapeutic approach to safeguard microvascular integrity during estrogen therapy. NHLBI R01HL160752 (J.K.F.), NHLBI K08HL141562 (J.K.F.), and AHA predoctoral fellowship grant 909315 (G.S.). This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

Hemorrhagic transformation of cerebral infarction: risk factors, diagnosis, and new approaches to treatment

Background. Hemorrhagic transformation (HT) is a frequent complication of acute cerebral infarction, which is unfavo­rable for the treatment and prognosis of patients. It can be divided into two main subtypes, hemorrhagic infarction, and parenchymal hematoma, depending on the type of hemorrhage. Although the pathophysiological mechanism of HT is still unclear, hypotheses have been proposed about the loss of microvascular integrity and impaired neurovascular homeostasis. The purpose of the study was to analyze the current scientific literature on risk factors, diagnosis, and new approaches to the treatment of hemorrhagic transformation of cerebral infarction. Materials and methods. A literature search using keywords was conducted in Web of Science, Scopus, PubMed, and Elsevier databases. Results. Ischemic tissues have a natural tendency to bleed. In addition, the first trials of recanalization using intravenous thrombolysis showed an increase in the incidence of mild to severe intracranial hemorrhages. Symptomatic intracerebral hemorrhage is closely associated with poor outcomes and is an important factor in recanalization decisions. The development of HT after stroke involves numerous interrelated pathological processes from peripheral blood cells to neurovascular units such as hyperactive ischemic cascades with increased levels of matrix metalloproteinases, excessive reactive oxygen species, coagulopathy, blood-brain barrier breakdown, and reperfusion injury. A number of risk factors or prognostic factors for HT after cerebral infarction have been identified, namely the use of antiplatelet agents or anticoagulants, infarct size, atrial fibrillation, hypertension, age, gender, heart failure, coronary artery disease, diabetes mellitus, lipid profile, reperfusion therapy, and white matter hyperintensity load. The incidence of HT is reported mainly in clinical studies using brain imaging techniques such as computed tomography or magnetic resonance imaging, diffusion weighted imaging, and perfusion weighted imaging. Recombinant tissue plasminogen activator therapy and mechanical thrombectomy are currently the main treatments for ischemic stroke, but reperfusion injury due to revascula­rization increases the risk of cerebral hemorrhage. Understanding the risk factors and in-depth evaluation of predictors can significantly help physicians develop strategies to reduce the occurrence of HT, as well as provide insight into the pathophysiological mechanism of the disease. Conclusions. Patients at risk of hemorrhagic transformation require invasive and non-invasive neuromonitoring to help make decisions in decompressive neurosurgery for large cerebellar infarction, specific cardiorespiratory treatment, nutrition, blood pressure control, biochemical parameters, and the choice of an individual management strategy.

Recombinant IGF-1/BP3 protects against intestinal injury in a neonatal mouse NEC model.

Recombinant human IGF-1/binding protein-3 (rhIGF-1/BP3) is currently being tested in phase II clinical trials in premature infants to prevent bronchopulmonary dysplasia, but its impact on the neonatal intestine remains unclear. The aim of this study was to determine whether rhIGF-1/BP3 protects against necrotizing enterocolitis (NEC) in mice and to investigate the mechanisms involved. Neonatal mice were dam fed or injected intraperitoneally with rhIGF-1/BP3 (or vehicle) and submitted to an experimental NEC model. Serum IGF-1 was assessed by ELISA and intestinal vascular endothelial growth factor (VEGF) and VEGF receptor 2 (VEGFR2) expression by Western blot. Intestinal endothelial cell proliferation, and enterocyte proliferation and migration were examined by immunofluorescence. Pup survival and histological intestinal injury were determined. In pups exposed to experimental NEC, serum IBP3-bound IGF-1 level was decreased. Exogenous rhIGF-1/BP3 preserved VEGF and VEGFR2 protein expression, decreased vascular permeability, and preserved endothelial cell proliferation in the small intestine. Furthermore, rhIGF-1/BP3 promoted enterocyte proliferation and migration, which effects were attenuated by inhibiting VEGFR2 signaling, decreased enterocyte apoptosis and decreased systemic and intestinal inflammation. rhIGF-1/BP3 improved survival and reduced the incidence of severe intestinal injury in experimental NEC. Exogenous rhIGF-1/BP3 protects neonatal mice against experimental NEC via multiple mechanisms. Exogenous rhIGF-1/BP3 preserves intestinal microvascular development and integrity, promotes enterocyte proliferation and migration, decreases local and systemic inflammation, and protects neonatal mice against NEC. The article adds pre-clinical evidence of a protective role for rhIGF-1/BP3 on the premature gut. It provides evidence supporting the use of rhIGF1/BP3 in premature neonates to protect against NEC.

Endothelial Robo4 suppresses endothelial-to-mesenchymal transition induced by irradiation and improves hematopoietic reconstitution

Bone marrow ablation is routinely performed before hematopoietic stem cell transplantation (HSCT). Hematopoietic stem and progenitor cells (HSPCs) require a stable bone marrow microenvironment to expand and refill the peripheral blood cell pool after ablation. Roundabout guidance receptor 4 (Robo4) is a transmembrane protein exclusive to endothelial cells and is vital in preserving vascular integrity. Hence, the hypothesis is that Robo4 maintains the integrity of bone marrow endothelial cells following radiotherapy. We created an endothelial cell injury model with γ-radiation before Robo4 gene manipulation using lentiviral-mediated RNAi and gene overexpression techniques. We demonstrate that Robo4 and specific mesenchymal proteins (Fibronectin, Vimentin, αSma, and S100A4) are upregulated in endothelial cells exposed to irradiation (IR). We found that Robo4 depletion increases the expression of endoglin (CD105), an auxiliary receptor for the transforming growth factor (TGF-β) family of proteins, and promotes endothelial-to-mesenchymal transition (End-MT) through activation of both the canonical (Smad) and non-canonical (AKT/NF-κB) signaling pathways to facilitate Snail1 activation and its nuclear translocation. Endothelial Robo4 overexpression stimulates the expression of immunoglobulin-like adhesion molecules (ICAM-1 and VCAM-1) and alleviates irradiation-induced End-MT. Our coculture model showed that transcriptional downregulation of endothelial Robo4 reduces HSPC proliferation and increases HSC quiescence and apoptosis. However, Robo4 overexpression mitigated the damaged endothelium’s suppressive effects on HSC proliferation and differentiation. These findings indicate that by controlling End-MT, Robo4 preserves microvascular integrity after radiation preconditioning, protects endothelial function, and lessens the inhibitory effect of damaged endothelium on hematopoietic reconstitution.

Changes in wider field swept-source OCT angiography vascular metrics with anti-vascular endothelial growth factor therapy in central retinal vein occlusion.

To investigate the impact of anti-VEGF therapy on vascular metrics in eyes with macular edema secondary to central retinal vein occlusion (CRVO) using wider field swept-source OCT angiography (WF SS-OCTA). We included 23 eyes with macular edema associated with non-ischemic CRVOfrom 22 patients treated with anti-VEGF therapy (median number of injections: 5 [2-9]). Changes in vessel density (VD), vessel skeletonized density (VSD), and foveal avascular zone (FAZ) parameters were measured using WF SS-OCTA. Visual acuity (VA) and central subfield thickness (CST) were also measured. Median CST decreased significantly from 369µm (305-531) to 267µm (243-300, p < 0.001). VD and VSD parameters in 12 × 12mm images showed significant reductions. For instance, VSD in the whole retina decreased from a median of 13.37 (11.22-13.74) to 11.29 (9.36-12.97, p = 0.013). Additionally, a significant increase in FAZ circularity was found, suggesting improved microvascular integrity. Significant inverse correlations were found between the number of anti-VEGF injections and all VSD and VD parameters on the 12 × 12mm images (p < 0.05). Notably, the reductions in VSD and VD on 12 × 12mm angiograms in the deep capillary plexus (DCP) after each injection significantly correlated with increased logMAR VA (worse VA). Anti-VEGF therapy in CRVO patients not only mitigates macular edema but also alters the overall microvascular morphology and functionality as revealed by WF SS-OCTA.

The benefit of favorable venous outflow profile is mediated through reduced microvascular dysfunction in acute ischemic stroke.

Venous outflow (VO) is emerging as a marker of microvascular integrity in acute ischemic stroke. Using hemorrhagic transformation (HT) and infarct growth as mediators, we tested whether a favorable VO profile benefited functional outcome by reducing consequences of microvascular dysfunction. Patients receiving thrombectomy in three comprehensive stroke centers due to acute anterior circulation occlusion were included. VO was assessed semi-quantitatively by the opacification of ipsilateral vein of Labbé, Trolard and superficial middle cerebral vein. HT was graded on follow-up CT. Infarct growth volume (IGV) was the difference of final infarct volume and baseline core volume. The association of VO and functional independence (90-day modified Rankin Scale ⩽ 2) was examined by logistic regression. Mediation analysis was performed among VO, HT or IGV, and functional outcome in patients with or without recanalization, respectively. In 242 patients analyzed, VO was strongly correlated with functional independence and VO ⩾ 4 was defined favorable. In 175 patients recanalized, favorable VO was associated with a reduced risk of HT (OR = 0.82, 95% CI 0.71-0.95, p = 0.008), which accounted for 13.1% of the association between VO and favorable outcome. In 67 patients without recanalization, favorable VO was associated with decreased IGV (β = -0.07, 95% CI -0.11 to -0.02, p = 0.007). The association of favorable VO and functional independence was no longer significant (aOR = 4.84, 95% CI 0.87-38.87, p = 0.089) after including IGV in the model, suggesting a complete mediation. In patients with acute anterior large vessel occlusion, the clinical benefit of VO may be mediated through reduced microvascular dysfunction.

Myocardial Oedema as a Consequence of Viral Infection and Persistence-A Narrative Review with Focus on COVID-19 and Post COVID Sequelae.

Microvascular integrity is a critical factor in myocardial fluid homeostasis. The subtle equilibrium between capillary filtration and lymphatic fluid removal is disturbed during pathological processes leading to inflammation, but also in hypoxia or due to alterations in vascular perfusion and coagulability. The degradation of the glycocalyx as the main component of the endothelial filtration barrier as well as pericyte disintegration results in the accumulation of interstitial and intracellular water. Moreover, lymphatic dysfunction evokes an increase in metabolic waste products, cytokines and inflammatory cells in the interstitial space contributing to myocardial oedema formation. This leads to myocardial stiffness and impaired contractility, eventually resulting in cardiomyocyte apoptosis, myocardial remodelling and fibrosis. The following article reviews pathophysiological inflammatory processes leading to myocardial oedema including myocarditis, ischaemia-reperfusion injury and viral infections with a special focus on the pathomechanisms evoked by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection. In addition, clinical implications including potential long-term effects due to viral persistence (long COVID), as well as treatment options, are discussed.

Loss of filamentous actin, tight junction protein expression, and paracellular barrier integrity in frataxin-deficient human brain microvascular endothelial cells-implications for blood-brain barrier physiology in Friedreich's ataxia.

Introduction: Friedreich's Ataxia (FRDA) is the most prevalent inherited ataxia. FRDA results from loss of Frataxin (FXN), an essential mitochondrial iron trafficking protein. FRDA starts with an early burst of neurodegeneration of the dorsal root ganglion and cerebellar dentate nuclei, followed by progressive brain iron accumulation in the latter. End stage disease includes cardiac fibrosis that contributes to hypertrophic cardiomyopathy. The microvasculature plays an essential barrier role in both brain and heart homeostasis, thus an investigation of this tissue system in FRDA is essential to the delineation of the cellular dysfunction in this genetic disorder. Previous reports have identified cytoskeletal alterations in non-barrier forming FRDA cell models, but physiological consequences are limited. Methods: We investigated brain microvascular endothelial cell integrity in FRDA in a model of the blood-brain barrier (BBB). We have knocked down FXN in immortalized human brain microvascular endothelial cells (hBMVEC), which compose the microcapillaries of the BBB, by using shRNA. We confirmed known cellular pathophysiologies of FXN-knockdown including decreased energy metabolism, markers of oxidative stress, and increased cell size. Results: We investigated cytoskeletal architecture, identifying decreased filamentous actin and Occludin and Claudin-5 tight junction protein expression in shFXN hBMVECs. This was consistent with decreased transendothelial electrical resistance (TEER) and increased paracellular tracer flux during early barrier formation. shFXN hBMVEC start with only 67% barrier integrity of the controls, and flux a paracellular tracer at 800% of physiological levels. Discussion: We identified that insufficient FXN levels in the hBMVEC BBB model causes changes in cytoskeletal architecture and tight junction protein abundance, co-incident with increased barrier permeability. Changes in the integrity of the BBB may be related to patient brain iron accumulation, neuroinflammation, neurodegeneration, and stroke. Furthermore, our findings implicate other barrier cells, e.g., the cardiac microvasculature, loci of disease pathology in FRDA.

Nicorandil alleviates cardiac microvascular ferroptosis in diabetic cardiomyopathy: Role of the mitochondria-localized AMPK-Parkin-ACSL4 signaling pathway

Mitochondria-associated ferroptosis exacerbates cardiac microvascular dysfunction in diabetic cardiomyopathy (DCM). Nicorandil, an ATP-sensitive K+ channel opener, protects against endothelial dysfunction, mitochondrial dysfunction, and DCM; however, its effects on ferroptosis and mitophagy remain unexplored. The present study aimed to assess the beneficial effects of nicorandil against endothelial ferroptosis in DCM and the underlying mechanisms. Cardiac microvascular perfusion was assessed using a lectin perfusion assay, while mitophagy was assessed via mt-Keima transfection and transmission electron microscopy. Ferroptosis was examined using mRNA sequencing, fluorescence staining, and western blotting. The mitochondrial localization of Parkin, ACSL4, and AMPK was determined via immunofluorescence staining. Following long-term diabetes, nicorandil treatment improved cardiac function and remodeling by alleviating cardiac microvascular injuries, as evidenced by the improved microvascular perfusion and structural integrity. mRNA-sequencing and biochemical analyses showed that ferroptosis occurred and Pink1/Parkin-dependent mitophagy was suppressed in cardiac microvascular endothelial cells after diabetes. Nicorandil treatment suppressed mitochondria-associated ferroptosis by promoting the Pink1/Parkin-dependent mitophagy. Moreover, nicorandil treatment increased the phosphorylation level of AMPKα1 and promoted its mitochondrial translocation, which further inhibited the mitochondrial translocation of ACSL4 via mitophagy and ultimately suppressed mitochondria-associated ferroptosis. Importantly, overexpression of mitochondria-localized AMPKα1 (mitoAα1) shared similar benefits with nicorandil on mitophagy, ferroptosis and cardiovascular protection against diabetic injury. In conclusion, the present study demonstrated the therapeutic effects of nicorandil against cardiac microvascular ferroptosis in DCM and revealed that the mitochondria-localized AMPK-Parkin-ACSL4 signaling pathway mediates mitochondria-associated ferroptosis and the development of cardiac microvascular dysfunction.

Donor-Derived Engineered Microvessels for Cardiovascular Risk Stratification of Patients with Kidney Failure.

Cardiovascular disease is the cause of death in ≈50% of hemodialysis patients. Accumulation of uremic solutes in systemic circulation is thought to be a key driver of the endothelial dysfunction that underlies elevated cardiovascular events. A challenge in understanding the mechanisms relating chronic kidney disease to cardiovascular disease is the lack of in vitro models that allow screening of the effects of the uremic environment on the endothelium. Here, a method is described for microfabrication of human blood vessels from donor cells and perfused with donor serum. The resulting donor-derived microvessels are used to quantify vascular permeability, a hallmark of endothelial dysfunction, in response to serum spiked with pathophysiological levels of indoxyl sulfate, and in response to serum from patients with chronic kidney disease and from uremic pigs. The uremic environment has pronounced effects on microvascular integrity as demonstrated by irregular cell-cell junctions and increased permeability in comparison to cell culture media and healthy serum. Moreover, the engineered microvessels demonstrate an increase in sensitivity compared to traditional 2D assays. Thus, the devices and the methods presented here have the potential to be utilized to risk stratify and to direct personalized treatments for patients with chronic kidney disease.

Impaired cerebral microvascular endothelial cells integrity due to elevated dopamine in myasthenic model

Myasthenia gravis is an autoimmune disease characterized by pathogenic antibodies that target structures of the neuromuscular junction. However, some patients also experience autonomic dysfunction, anxiety, depression, and other neurological symptoms, suggesting the complex nature of the neurological manifestations. With the aim of explaining the symptoms related to the central nervous system, we utilized a rat model to investigate the impact of dopamine signaling in the central nervous and peripheral circulation. We adopted several screening methods, including western blot, quantitative PCR, mass spectrum technique, immunohistochemistry, immunofluorescence staining, and flow cytometry. In this study, we observed increased and activated dopamine signaling in both the central nervous system and peripheral circulation of myasthenia gravis rats. Furthermore, changes in the expression of two key molecules, Claudin5 and CD31, in endothelial cells of the blood–brain barrier were also examined in these rats. We also confirmed that dopamine incubation reduced the expression of ZO1, Claudin5, and CD31 in endothelial cells by inhibiting the Wnt/β-catenin signaling pathway. Overall, this study provides novel evidence suggesting that pathologically elevated dopamine in both the central nervous and peripheral circulation of myasthenia gravis rats impair brain–blood barrier integrity by inhibiting junction protein expression in brain microvascular endothelial cells through the Wnt/β-catenin pathway.Graphical

Cigarette smoking abolishes the mediterranean diet benefit on exercise capacity, coronary physiology and target organ damage in hypertensive males with erectile dysfunction

Abstract Background Erectile dysfunction (ED) often coexists impairing quality of life in the hypertensive aging male population. The Mediterranean diet (Med-diet) benefits cardiovascular health. Coronary flow reserve (CFR) displays the ability of the coronary circulation to increase flow. Central vascular stiffness and microalbuminuria (UMALb) represent hypertension-related target organ damage (TOD). Purpose To investigate cigarette smoking adverse effects on the Med-diet benefit in exercise capacity, coronary physiology and TOD in hypertensive males with ED. Methods We enrolled 290 hypertensive ED males (mean age: 57 yo) with no history of diabetes mellitus or overt cardiovascular disease. 121 (42%) were current cigarette smokers. Intensity of smoking referred in packs/year. All underwent a treadmill stress test (Bruce protocol), exercise capacity was validated as metabolic equivalents (METs). We measured the CFR of the LAD artery (2D echo) by performing an adenosine protocol (max dose 140μg/Kg/min over 6 min). PW Doppler measurements were achieved at the middle/distal LAD (color Doppler flow mapping). CFR was validated as ratio between peak diastolic flow velocity following drug infusion and rest. Ratios ≥ 2 indicate macro and microvascular coronary integrity. Participants were screened for the presence of UMALb (urinary albumin loss 30 – 300 mg /24 h urine volume collection). Finally a non-invasive evaluation of the carotid – femoral pulse wave velocity (PWV), estimation of central pressures and augmentation index (AIx) a parameter of wave reflection amplification were performed (Sphygmocor device). ED severity and the Med-diet adherence were assessed by the SHIM-5 (range:0-25) and the Med-diet (range:0-55) scores. Higher values indicate a better erectile ability and Med-diet compliance respectively. Results In bivariate analysis the Med-diet score was positively associated with METs, CFR and the SHIM-5 score and negatively with PWV, AIx and UMALb (p&amp;lt; 0,05). CFR, METs and the SHIM-5 score were also positively related (p&amp;lt; 0,03). In linear regression analysis the Med-diet relation remained significant after correction for age, BMI, LDL, total cholesterol and systolic blood pressure. However introducing cigarette smoking as a cofounder abolished the above relations. Packs/year were positively related to AIx, UMALb and negatively to the SHIM-5 score (p&amp;lt; 0,05). We also divided our population according to the mean Med-diet score (27) in high and low Med-diet groups .The high score group had higher METs and SHIM-5 score and lower PWV. Smokers had higher AIx and lower SHIM-5 score (pictures). Conclusion Cigarette smoking influences microvascular physiology and peripheral wave reflection and so abolishes Med-diet benefit on exercise capacity, coronary physiology, target organ damage and erectile ability in hypertensive males with ED. It is of vital importance consult this population avoiding smoking to restore cardiovascular health and quality of life.