PURPOSE:Microcirculation is essential for maintaining tissue viability and organ function by delivering oxygen and nutrients. Impaired microvascular perfusion may result in tissue dysfunction despite apparently normal macrocirculatory parameters. However, comprehensive experimental characterization of entire microvascular networks remains technically challenging, limiting quantitative assessment of network-level perfusion. This study aimed to develop a data-efficient computational framework for reconstructing microcirculatory network structure and estimating blood perfusion from sparse local vascular measurements. METHODS:Rat mesenteric microvascular networks, which share selected quasi-two-dimensional structural characteristics with human sublingual microcirculation, were used for methodological validation. Morphological and flow information was extracted from individual vessel segments, and three datasets, each containing 10 randomly selected venous bifurcations, were used to emulate limited data availability. A conditional generative adversarial network (cGAN) was pretrained on a larger source corpus and fine-tuned using each sparse target dataset. Venous trees were subsequently generated and integrated with derived arterial trees and capillary connections to reconstruct complete microvascular networks. Initial flow rates were assigned from local measurements, followed by network optimization using a structural adaptation model. RESULTS:Five microcirculatory networks were generated for each sparse bifurcation dataset, enabling quantification of network-level perfusion descriptors, including blood-flow fractal dimension, multifractal spectrum, and capillary-flow heterogeneity. Under controlled distribution shift at the bifurcation-generation level, fine-tuning successfully shifted the distributions of generated bifurcation exponent and asymmetry ratio toward the corresponding sparse target data. The reconstructed networks exhibited broadly similar diameter-conditioned velocity and pressure trends to those in the reference network. Structural adaptation further differentiated the diameter-flow relationships in arterial and venous, with the fitted slopes approaching the corresponding reference values. CONCLUSION:The proposed framework provides a data-efficient framework for physiologically plausible reconstruction of microcirculatory networks and estimation of network-level perfusion from sparse local bifurcation data. Validation in rat mesenteric microvascular networks demonstrates the methodological feasibility of the framework and highlights its potential as a quantitative tool for perfusion analysis and advancing translational studies of microcirculatory modeling.
Endomucin (EMCN), a highly glycosylated type I transmembrane sialomucin, is predominantly expressed on the luminal surface of venous and capillary endothelial cells and serves as a critical guardian of vascular homeostasis and immunological silencing. Its highly extended, O-glycosylated extracellular domain provides significant steric hindrance and electrostatic repulsion, functioning as a dual physical barrier that prevents nonspecific leukocyte tethering and adhesion. Beyond its anti-adhesive role, EMCN is a pivotal orchestrator of angiogenesis, modulating the vascular endothelial growth factor signaling cascade by facilitating vascular endothelial growth factor receptor 2 autophosphorylation at the Y1175 residue and subsequent receptor internalization. Furthermore, EMCN has emerged as a specialized marker for type H vessels and human hematopoietic stem cells, playing indispensable roles in vessel-bone coupling and hematopoietic development. Clinical evidence indicates that the dysregulation of EMCN expression or post-translational modifications contributes to the pathogenesis of diabetic complications, atherosclerosis, bone metabolic disorders, and tumor metastasis. This review systematically summarizes structural characteristics, expression patterns, and multifaceted biological functions of EMCN, providing a theoretical foundation for the development of novel therapeutic strategies for microvascular and metabolic diseases.
The blood-brain barrier (BBB) is a dynamic endothelial interface that protects the brain from harmful agents while regulating molecular exchange. Human immunodeficiency virus (HIV) compromises BBB integrity, promoting neurological damage. Antiretroviral (ARV) therapies suppress HIV replication, preventing immune system deterioration and progression to AIDS. Although Tenofovir-based ARV regimens are vital for HIV treatment and prevention, their impact on cerebrovascular function remains unclear. AIM:This study examined Tenofovir's effects on murine brain endothelial cells using an in vitro BBB model. METHODS:Brain endothelial cells (bEnd.5) were treated with Tenofovir Disoproxil Fumarate (TDF; 9.8-98 ng/mL) or Tenofovir Alafenamide (TAF; 1-10 ng/mL) for 24-96 h. Cell proliferation, cell cycle progression (via flow cytometry) and monolayer permeability (via Transendothelial Electrical Resistance) were evaluated. RESULTS:Both TDF and TAF treatments suppressed cell division by S-phase disruption of the cell cycle and increased monolayer permeability. CONCLUSION:These findings suggest that prolonged TDF or TAF exposure compromises BBB integrity by inhibiting endothelial cell division and altering barrier function, which could have implications for HIV-ARV-induced neurodegeneration in individuals receiving long-term Tenofovir-based therapy.
OBJECTIVE:Large conductance calcium-activated potassium channels (BKCa) play an important role in the regulation of vascular tone. However, the properties of BKCa channels in smooth muscle of pulmonary arteries are poorly understood. Previous experimental studies demonstrated that pulmonary hypoxic vasoconstriction as a normal physiological response to decreased oxygen levels was impaired in diabetic animals due to abnormal activation of BKCa channels. The aim of this study was to identify mechanisms of diabetes-induced activation of BKCa channels in freshly isolated smooth muscle cells from rat pulmonary arteries. METHODS:Type 1 diabetes was induced by streptozotocin (STZ). Whole-cell potassium currents were recorded using the patch-clamp method. Expression levels of BK-α and BK-β1 subunits were measured by real-time PCR. RESULTS:Our results demonstrate that the amplitude of whole-cell current through BKCa channels in rat pulmonary artery smooth muscle cells is significantly increased during STZ-induced diabetes without altering the expression of BK-α and BK-β1 subunits and channel calcium sensitivity. The slow component of BKCa current deactivation time constant and spontaneous transient outward current amplitude were increased in diabetic animals compared to healthy animals. CONCLUSIONS:We conclude that abnormal activation of the BKCa channel in pulmonary arterial smooth muscle during diabetes is associated with alterations in the local control mechanism of the BKCa pore-gate domain.
HYPOTHESIS:We hypothesize that the dynamics of O2-mediated blood flow responses in skeletal muscle capillaries are altered under different tissue carbon dioxide concentrations ([CO2]) due to the interaction of overlapping mechanisms. METHODS:Eight male Sprague Dawley rats (164-215 g) were anesthetized and instrumented for systemic monitoring. The extensor digitorum longus muscle was isolated and reflected over a microfluidic gas exchange chamber mounted in an inverted microscope stage. 4-min intravital video recordings of capillary blood flow during O2 challenges consisted of a 1-min baseline at 7% O2 concentration ([O2]), followed by 3 min at 2% [O2], under constant background [CO2] at 2%, 5%, and 8%. Recordings were analyzed offline using custom MATLAB software. Time transients (τ) of capillary hemodynamic responses were determined using a least squared regression fit to single- and double-exponential models. RESULTS:Fast component τ of the O2-mediated capillary red blood cell (RBC) velocity response was 2.1 s for 2% [CO2], 3.8 s for 5% [CO2], and 7.0 s for 8% [CO2]. Third minute low [O2] capillary RBC supply rate increases from baseline were greater for 8% [CO2] (5% [CO2]: 6.4 ± 8.7 cells/s vs. 8% [CO2]: 8.5 ± 10.7 cells/s, p = 0.0007). CONCLUSION:The fast component τ of O2-mediated capillary hemodynamic responses was found to be slower with increasing background tissue [CO2], suggesting that multiple interacting mechanisms are involved to appropriately regulate O2 delivery under different CO2 conditions in partial support of the hypothesis.
INTRODUCTION:Red blood cells (RBCs) possess distinct biomechanical properties that enable their survival and efficient oxygen delivery. Cancer-associated anemia, frequently compounded by chemotherapy, is a major clinical challenge, yet little is known about how RBC biomechanics contribute to its pathophysiology. This study evaluates the biomechanical properties of RBCs in patients with cancer compared to controls and within patients before and after chemotherapy. METHODS:Biomechanical properties of RBCs were assessed in 110 women with breast, ovarian, or endometrial cancer, measured before and after chemotherapy, and compared findings with 35 healthy female controls. Thirteen biomechanical parameters were assessed using the MIZAR automated rheometer. RESULTS:Relative to controls, pre-chemotherapy cancer patients exhibited significantly higher RBC aggregation and elasticity. Within the cancer cohort, anemic patients demonstrated more deformable and elastic RBCs, with increased aggregation compared to non-anemic patients. Following chemotherapy, patients displayed reduced RBC deformability but further increased elasticity, consistent with chemotherapy-induced alterations to membrane structure and function; these effects were most pronounced in anemic patients. CONCLUSION:We report novel rheological observations indicating that both cancer and chemotherapy are associated with alterations in RBC biomechanics, and that anemia further amplifies these changes. Importantly, cancer-associated anemia appears to involve impaired RBC quality. Recognition of biomechanical dysfunction may provide new insights into the mechanisms of cancer-related anemia and support the development of more comprehensive diagnostic and management strategies.
OBJECTIVE:Zinc finger E-box-binding homeobox 1 (ZEB1) is a transcription factor primarily known for its regulatory roles in epithelial-to-mesenchymal transition (EMT) and cell fate determination. Recent studies suggest that endothelial ZEB1 signaling promotes blood vessel growth and reduces junctional integrity, although the underlying mechanisms remain unclear. Notably, the role of ZEB1 in the lymphatic vasculature is unknown, and the regulation of lymphatic integrity by VE-cadherin remains poorly defined. METHODS:Here, using an integrated proteomic and transcriptomic approach, we identify ZEB1-dependent signaling pathways associated with cell-cell junction reorganization in lymphatic endothelial cells (LECs). RESULTS:Loss of ZEB1 reduced VE-cadherin phosphorylation at pY731 and pY685 and was accompanied by decreased monolayer resistance and impedance, together with increased leukocyte transendothelial migration. ZEB1 knockdown also reduced YES tyrosine kinase expression and altered YAP1 expression and junctional localisation, changes that were associated with reduced VE-cadherin phosphorylation. Silencing YAP1 in HDLECs similarly reduced VE-cadherin phosphorylation and impaired barrier integrity, recapitulating aspects of the phenotype observed following ZEB1 knockdown. CONCLUSIONS:Collectively, these findings suggest that ZEB1 contributes to lymphatic endothelial barrier maintenance in association with altered YAP1 and YES signaling.
BACKGROUND:Pulmonary microcirculatory dysfunction is a hallmark of sepsis, contributing to hypoxemia, pulmonary edema, and multiple organ failure. Anisodamine hydrobromide (ADM), a natural alkaloid with anti-inflammatory and endothelial-protective properties, has been used clinically in China for septic shock. However, its effects on pulmonary microcirculatory dysfunction in septic shock remain unclear. METHODS:A rat model of sepsis was established via cecal ligation and puncture (CLP). Rats were treated with low, medium, or high doses of ADM. Seven-day survival rates and arterial blood gas parameters were monitored. Pulmonary microvascular leakage was evaluated using Evans blue extravasation and FITC-dextran imaging. Histological analysis, immunofluorescence, and Western blotting were performed to assess leukocyte adhesion, inflammatory cell infiltration, endothelial junction proteins, basement membrane proteins, and matrix metalloproteinases. RESULTS:ADM treatment significantly improved 7-day survival and restored arterial partial pressure of oxygen (PaO2), oxygen saturation (SaO2), and pH in CLP rats. High-dose ADM markedly reduced Evans blue and FITC-dextran leakage, attenuated pulmonary edema, and preserved alveolar architecture. ADM inhibited leukocyte adhesion in pulmonary microvessels and decreased infiltration of MPO- and CD68-positive inflammatory cells. Mechanistically, ADM suppressed CLP-induced Caveolin-1 upregulation, restored the expression of VE-Cadherin, Occludin, and Claudin-5, and prevented degradation of Collagen IV and Laminin. Additionally, ADM significantly downregulated MMP-9 expression, while MMP-2 levels remained unchanged, suggesting a role in limiting junctional and basement membrane degradation. CONCLUSION:ADM protects against CLP-induced pulmonary microcirculation dysfunction in rats by attenuating inflammatory cell infiltration, preserving pulmonary endothelial junctions, and maintaining basement membrane integrity. These results provide mechanistic insight into ADM's therapeutic potential in sepsis-induced pulmonary microcirculation dysfunction and support its use for sepsis in clinic.
OBJECTIVE:This study investigated the relationship between sublingual microcirculatory tortuosity, frailty index scores, and endothelial glycocalyx blood biomarkers in individuals with chronic kidney disease (CKD). METHODS:Sublingual microcirculatory videos were analyzed using a 0-4 tortuosity scoring scale. Plasma concentrations of syndecan-1 and soluble thrombomodulin were quantified using enzyme-linked immunosorbent assay (ELISA). Frailty status was assessed using a short-form frailty index questionnaire. RESULTS:The study included 44 patients (median age 53 years, IQR 45-64) attending a kidney transplant assessment clinic, with equal representation of males and females. The median frailty index was 0.19 (IQR: 0.15-0.30), with 63.5% of participants having an FI score < 0.25. Intraclass correlation coefficient (ICC) analysis demonstrated excellent inter-observer reliability for tortuosity scoring. Frailty index scores were significantly higher in participants with tortuosity scores of 3/4 compared to those with a score of 0. No significant differences were observed in syndecan-1 or soluble thrombomodulin levels across tortuosity scores. Ordinal logistic regression identified frailty index score as the only significant predictor of tortuosity, independent of age, dialysis type, or sex. CONCLUSIONS:Higher frailty index scores were associated with increased sublingual microcirculatory capillary tortuosity, though this relationship did not extend to endothelial glycocalyx biomarkers. These findings highlight the potential value of incorporating tortuosity assessment alongside density and perfusion measures in microcirculatory evaluation.
OBJECTIVES:Recent clinical studies have suggested that glucagon-like peptide-1 receptor (GLP-1R) agonists may be effective therapies to treat or reduce the risk of developing secondary lymphedema. In this study, we aimed to (1) determine if GLP-1Rs are present in the lymphatic vasculature and characterize their expression, and (2) assess the effects of GLP-1R agonism on the contractile function of collecting lymphatic vessels. METHODS:We assessed the expression of GLP-1Rs in and around the lymphatic vasculature by single-cell RNA sequencing and fluorescence confocal microscopy, and evaluated the direct effects of GLP-1R agonist, semaglutide, on modulating lymphatic contractility using pressure myography. RESULTS:Expression of Glp1r (encoding GLP-1Rs) was detected exclusively in lymphatic endothelial cells. Pharmacological activation of GLP-1Rs led to robust vasodilation and an increase in the pumping capacity of isolated collecting lymphatics from WT, diet-induced obese, and hypercholesterolemic ApoE KO mice. The GLP-1R-mediated response was in part facilitated by nitric oxide and its potential interaction with NaV channels; however, additional signaling remains to be elucidated. CONCLUSIONS:Our results revealed a direct, beneficial effect of GLP-1R agonism on lymphatic pumping capacity mediated by robust vasodilation, allowing lymphatics to accommodate and displace larger fluid volumes while maintaining strong and highly efficient contractions.
Glycans encode molecular information, but the endothelial glycocalyx is an organized, multicomponent supramolecular structure whose architecture integrates glycan cues into coherent vascular responses in vivo. The vascular endothelial glycocalyx (eGCX) is a flow-conditioned, membrane-coupled surface layer that mediates mechanotransduction, selective permeability control under the revised Starling principle, and anticoagulant and anti-inflammatory functions central to hemostasis and thrombo-inflammation. However, "glycocalyx" is often conflated with individual glycans or mucins, causing conceptual drift in study design, assay selection, and biomarker interpretation. Here, we provide a hierarchical synthesis that distinguishes glycans as molecular building blocks, mucins as specialized, densely O-glycosylated glycoproteins (secreted gel-forming or transmembrane), and the eGCX as a supramolecular assembly organized around membrane-anchored proteoglycans bearing glycosaminoglycans and associated plasma constituents. Although glycocalyces exist on nearly all mammalian cells, this review focuses on the vascular eGCX. We explain why emergent eGCX functions-shear-dependent signaling, nitric oxide pathways, molecular sieving, and local regulation of coagulation-cannot be inferred from glycan motifs or mucin expression alone. We also clarify how commonly used readouts measure distinct biological processes: imaging-derived thickness and coverage, the perfused boundary region as a hydrodynamic exclusion index, and circulating shedding products such as syndecan-1, hyaluronan, and heparan sulfate as systemic markers of endothelial injury. Anchoring terminology to hierarchy and matching assays to targets should improve reproducibility and clinically meaningful translation in vascular disease, sepsis, trauma, and diabetes.
BACKGROUND:Hypoxia is a critical determinant of neuronal function and vulnerability in the brain. While neuronal density has been extensively characterized across cortical regions, the spatial relationship between neurons and the microvasculature represents an additional structural constraint on oxygen diffusion and metabolic support. In particular, the distance between neurons and nearby capillaries influences local oxygen availability required to sustain neuronal activity and maintain ionic homeostasis. METHODS:In this study, we quantified neuron-capillary spatial relationships across cortical layers in the human primary visual cortex. Postmortem tissue from three neuropathologically normal individuals (ages 55-75 years) was analyzed using dual-label immunohistochemistry for NeuN (neurons) and CD34 (vascular endothelial cells). Regions of interest corresponding to neocortical layers were delineated by a neuropathologist. Automated image analysis in QuPath was used to segment neurons using object-based classification and capillaries using pixel-based classification. Distances between neuronal and vascular centroids were corrected for tissue shrinkage using a linear scaling factor of 1.20. Centroids of segmented objects were extracted, and nearest-neighbor relationships were computed using a quad tree spatial search algorithm. RESULTS:Across more than 155 000 neurons and 84 000 vascular objects, we observed a consistent laminar gradient in neuron-capillary distance. Neurons in superficial and deep layers were located farther from capillaries, whereas neurons in the central layers exhibited shorter distances, with layers III and IV demonstrating median distances of ~30-45 μm. CONCLUSIONS:These findings demonstrate that neuron-capillary spatial relationships vary systematically across cortical depth, suggesting that cortical microvascular architecture is consistent with layer-specific metabolic demands.
OBJECTIVE:Perivascular adipose tissue (PVAT) surrounds most peripheral blood vessels and exerts an anti-contractile influence through paracrine mediators. Although numerous vasoactive factors have been identified, the mechanisms linking adipocyte metabolism to PVAT-dependent modulation of vascular tone remain poorly defined. Because adipocytes store energy as triglycerides hydrolyzed by adipose triglyceride lipase (ATGL) and hormone-sensitive lipase (HSL) to generate free fatty acids, we hypothesized that lipolysis-derived fatty acids may contribute to PVAT's anti-contractile actions through activation of long-chain fatty acid-sensing G protein-coupled receptors, Gpr40 and/or Gpr120. METHODS:Mesenteric resistance arteries (MRAs) from adult Wistar rats were studied using wire myography, with or without PVAT, and pharmacological agonists/antagonists and endothelial denudation were used to study signaling. To examine changes in hypertension, PVAT and MRAs from spontaneously hypertensive rats (SHRs) were analyzed by western blotting, and plasma from non-fasting or fasting SHR was assessed by untargeted lipidomics. RESULTS:In Wistar rats, inhibition of ATGL, but not HSL, abolished PVAT's anti-contractile effect, and blockade of Gpr40, but not Gpr120, similarly diminished this response, identifying ATGL and Gpr40 as important mediators. Activation of Gpr40 in PVAT- and endothelium-denuded MRAs further recapitulated the anti-contractile effect in a β-arrestin-dependent manner. In SHR, PVAT ATGL expression was significantly upregulated and MRA Gpr40 expression tended to increase. However, circulating Gpr40 ligand abundance was largely unchanged between strains, suggesting that impaired ligand availability is unlikely to underlie PVAT dysfunction in hypertension. CONCLUSIONS:These findings identify a previously unrecognized ATGL-Gpr40 signaling axis linking adipocyte triglyceride metabolism to PVAT-mediated regulation of vascular tone.
BACKGROUND:Impaired opisthenar microvessel area (OMA) has been associated with adverse cardiac outcomes in acute myocardial infarction (AMI) patients. Here, we compared the characteristics of OMA of ischemic stroke (AIS) patients, National Institutes of Health Stroke Scale (NIHSS) positive, AIS recurrence, and AMI patients. METHODS:OMA was investigated using optical coherence tomography (OCT) in AIS patients with mild or no neurological deficit (MND, NND) and recurrence or recurrence-free (RG, RFG). The characteristics of microvessel were compared to those of AMI patients. Brachial-ankle pulse wave velocity (baPWV) was also measured with Omron Instrument. RESULTS:Compared to controls (Con), OMA, total and average vessel length (TVL, AVL) were smaller but End points (EPs) were greater in AIS at room temperature (RT). Both heat and cold stimulation (HS and CS) increased vessel length and area. However, significantly increased EPs and Lacunarity were observed at CS in AIS patients. As for the effect of neurological deficiency, OMA, TVL, and AVL were smaller, and EPs were markedly increased in MND with CS. OMA and TVL were smaller in the RG group at RT, but CS or HS did not change microvascular characteristics. Between AIS and AMI patients, baPWV was significantly greater in AIS, microvessel area and length were comparable between the two groups, and EPs were significantly increased in AIS. Furthermore, baPWV showed a positive correlation with OMA in CON, a negative correlation in AMI, but no correlation in AIS. CONCLUSIONS:Greater EPs and lacunarity of microvasculature are indicative of discordancy in AIS patients. Disrupted macrovascular-microvascular association in AIS suggests distinctive pathology to those of AMI.
Objective Acute ischemic stroke (AIS) is one of the leading causes of death and disabilities, and as such, it is of utmost importance to identify novel treatment options. Remote ischemic conditioning (RIC) is a promising non-invasive treatment that is thought to activate the body's own protective mechanisms against damaging ischemia. Here, we study the transcriptomic impact of microRNAs (miRNAs) that are upregulated by RIC.Methods Using RNA sequencing, we investigated the transcriptional changes in human brain microvascular endothelial cells (HBMECs) transfected with four selected RIC-upregulated miRNAs (RIC-miRNAs), miR-16-5p, miR-144-3p, miR-182-5p, and miR-451a, under oxygen and glucose deprivation (OGD) and reoxygenation-mimicking the initial stages of AIS.Results Pronounced transcriptional changes were present after RIC-miRNA transfection, with 149 unique downregulated and 212 upregulated differentially expressed genes in HBMECs after OGD and RIC-miRNA transfection compared to all other conditions. These genes were involved in pathways of energy metabolism and cell cycle regulation.Conclusion Our study suggests that the selected RIC-miRNAs regulate pathways that may facilitate endothelial cell survival, recovery, and remodeling events from ischemic damage, adding to the knowledge of the pathways affected by RIC during stroke.
OBJECTIVE:Microvascular hyperpermeability and blood-brain barrier (BBB) dysfunction is a key consideration in neurological disorders, particularly tauopathies, a group of neurodegenerative disorders driven by misfolded and aggregated tau protein. Tau pathology has been shown to activate microglial NLRP3 inflammasome, an innate immune system sensor that responds to changes in the microenvironment, including cellular stress. Increases in reactive oxygen species (ROS), for example, activate NLRP3 inflammasome signaling, which provides a platform for the maturation of caspase-1 enzyme. Mature caspase-1 can cleave and release pro-inflammatory IL-1β cytokine. Both NLRP3 inflammasome and IL-1β may activate downstream MMP-9 enzyme, a known inducer of endothelial cell barrier hyperpermeability. Endothelial cells make up the innermost layer of the BBB and as such, largely govern BBB structural and functional integrity. Whether tau can activate NLRP3 inflammasome signaling in cerebral endothelial cells is unknown. The objective of this study is therefore to understand the role of tau, in various states of aggregation, on endothelial cell permeability and to investigate if NLRP3 inflammasome signaling occurs in this context. METHODS:Human brain microvascular endothelial cells (HBMECs) were grown as a monolayer in Transwell inserts and exposed to various tau polymorphs, including tau monomers, tau oligomers (oTau), and tau fibrils (fTau). Barrier permeability was measured using FITC-dextran fluorescent tracer (10 kDa) and Trans-Endothelial Electrical Resistance (TEER). Relative changes in gene expression were measured using RT-qPCR and normalized to GAPDH. Levels of NLRP3 sensor protein and IL-1β were measured by ELISA. Relative activity of caspase-1 and MMP-9 enzymes was calculated using fluorometry. Cell viability was reported using calcein AM, a measure of cell membrane integrity, and by measuring the redox potential of XTT. ROS formation, apoptosis, and necrosis were determined using commercially available kits. An NLRP3 inflammasome inhibitor, MCC950, was applied in blocking studies prior to tau treatments. RESULTS:Tau oligomers, but not monomers or fibrils, induced endothelial cell hyperpermeability in a dose-independent manner. At concentrations that compromised barrier function (100 nM; overnight), oTau did not alter cell viability and did not increase apoptosis or necrosis. Tau oligomers increased the formation of ROS and increased levels of both NLRP3 sensor protein and IL-1β cytokine. Enzymatic activity of caspase-1 and MMP-9 also increased in response to oTau, without changes in gene expression. These alterations were attenuated when NLRP3 inflammasome signaling was inhibited via MCC950, strongly suggesting that oTau activates NLRP3 inflammasome signaling in cerebral endothelial cells. CONCLUSIONS:Our study is the first to document a role for NLRP3 inflammasome signaling in cerebral endothelial cells following exposure to tau oligomers. Given the importance of endothelial cell functioning in BBB integrity, these data are significant in that they demonstrate a key role for endothelial cell signaling in tau pathogenicity and propose a mechanism by which tauopathies compromise BBB functional integrity. Taken together, these findings warrant future investigation into the therapeutic potential of NLRP3 inflammasome inhibition to ameliorate tauopathy-related barrier breach.
OBJECTIVE:To investigate choroidal hemodynamic changes after a hemodialysis (HD) session in the initiation versus maintenance phases in patients with diabetic nephropathy (DN) and diabetic retinopathy (DR). METHODS:This study included 38 eyes of 20 patients with DN-related end-stage renal disease and DR, stratified into initiation (first HD session; 12 eyes) and maintenance (26 eyes) groups. Choroidal hemodynamics were quantified using laser speckle flowgraphy (LSFG). Macular mean blur rate (M_MBR; index of blood flow) parameters, macular beat strength (M_BS; index of pulsatility), and central choroidal thickness (CCT) were evaluated. RESULTS:In the initiation group, M_MBR parameters significantly decreased after HD, whereas mean changes in M_BS and CCT were not significant. A comparable significant reduction in ocular perfusion pressure was observed in both cohorts. The initiation group exhibited significantly greater reductions in choroidal circulation and thickness. Higher ultrafiltration volume was linked to greater flow pulsatility reductions in the initiation group, with no volume-dependent correlation in the maintenance group. CONCLUSIONS:Choroidal circulation exhibits dialysis phase-dependent hemodynamic patterns. The initiation phase is characterized by volume-dependent flow pulsatility reductions, whereas the maintenance phase displays an attenuated response, indicating vascular adaptation. LSFG-derived monitoring may serve as a noninvasive biomarker for assessing microcirculatory responses.
OBJECTIVE:Diabetes is associated with microvascular complications in multiple tissues. Nailfold capillaries (NFCs) provide a noninvasive window for assessing microvascular alterations; however, their temporal association with skeletal muscle microvascular changes during diabetes progression remains unclear. This study aimed to determine whether NFC structural changes reflect skeletal muscle microvascular alterations and muscle-type-specific vulnerability in a non-obese type 2 diabetes model. METHODS:Spontaneously Diabetic Torii (SDT) rats, a non-obese type 2 diabetes model, and age-matched Sprague-Dawley rats were studied. NFC morphology was evaluated by capillaroscopy at 12, 18, and 28 weeks of age. Soleus and plantaris muscles were collected for histological and gene expression analyses, and glucose tolerance was evaluated by oral glucose tolerance testing at each time point. RESULTS:At 12 weeks of age, SDT rats exhibited mild glucose intolerance without significant abnormalities in NFC morphology or skeletal muscle capillary indices. At 18 weeks, when glucose intolerance became evident in the absence of persistent hyperglycemia, NFC narrowing and reduced density were observed, accompanied by capillary rarefaction in the predominantly fast-twitch plantaris muscle, whereas the slow-twitch soleus muscle remained relatively preserved. By 28 weeks, persistent hyperglycemia was present, and overt muscle atrophy was observed exclusively in the plantaris muscle. CONCLUSION:NFC structural alterations emerge alongside skeletal muscle microvascular rarefaction at the stage of glucose intolerance and precede overt muscle atrophy in fast-twitch muscle. NFC assessment may serve as a noninvasive indicator of early microvascular alterations relevant to diabetes-associated skeletal muscle deterioration.
OBJECTIVE:Sepsis is associated with hypotension, tissue hypoperfusion, and microcirculatory dysfunction leading to multi-organ failure and mortality. Pentoxifylline (PTX), a phosphodiesterase inhibitor, is reported to improve blood flow and viscosity. The aim of this study was to investigate the efficacy of PTX on peripheral and renal microcirculatory alterations in sepsis. METHODS:Fully instrumented Wistar albino rats were randomized as the control group (only surgery), only lipopolysaccharide (LPS) group without treatment (T1), LPS group with PTX treatment (LPS + PTX), LPS group treated with only fluid resuscitation (Ringer's acetate; RA), LPS + RA, LPS group with combined treatment with PTX and RA (LPS + PTX + RA) for 3 h (T2, T3 and T4). The systemic hemodynamics, renal oxygenation, leg muscle microcirculation, histological damage, and inflammatory and endothelial injury markers were analyzed. RESULTS:The renal cortical microvascular oxygen pressure (cμPO2) was improved by the PTX, RA, and PTX + RA treatments compared to the LPS group (p < 0.05). The proportions of perfused vessels (PPV) and red blood cell velocity (RBCv) were significantly restored by PTX and RA compared with the LPS group at T4 (p < 0.05). Renal damage and inflammatory cell infiltration were reduced by PTX and RA together compared with RA alone (p < 0.05). CONCLUSION:In this study, we found that PTX may protect renal oxygenation, peripheral (muscle) microcirculation, renal damage, and tissue inflammatory cell infiltration in a rat model of LPS-induced sepsis.
Objective: This study demonstrates the impact of alterations in pressure, vascular compliance, arterial pulsatility, and autoregulation on tissue perfusion following middle cerebral artery (MCA) occlusion using mathematical modeling. Methods: Our previous mathematical model of the cerebral circulation is expanded to include vessel compliance and pulsatility of blood flow. An experimentally-obtained pressure waveform is used as an incoming boundary condition to simulate the effects of vascular compliance and pulsatility of flow on perfusion following MCA occlusion. The waveform is adjusted to model the effects of elevated mean arterial pressure. Results: Increased distensibility reduces the amplitude of oscillations in the time-dependent pressure solutions, whereas decreased distensibility produces more variation in these pressures. Occlusion significantly alters the magnitude of flow changes when incoming pressure is varied. The addition of the pulsatile pressure boundary condition and capacitances in the arteries and veins shifts the autoregulation plateau to higher pressures. Conclusions: This study reveals how changes in incoming pressure affect compensatory responses to ischemic stroke caused by MCA occlusion. Boundary conditions corresponding to elevated mean arterial pressures are associated with lower degrees of ischemia, an improvement that is supported by changes in autoregulation patterns following occlusion. The results also demonstrate how increases in arterial stiffness associated with aging can inhibit the ability of the vasculature to accommodate pulsatile flow by analyzing resulting patterns such as larger amplitudes of pressure and flow oscillations in the microcirculation. The study provides a foundation for modeling the relationships among vessel compliance, arterial blood pressure, and cerebrovascular conditions.
