Microvascular dysfunction: a potential mechanism in the pathogenesis of obesity-associated insulin resistance and hypertension

Back to the Basics of SARS-CoV-2 Biochemistry: Microvascular Occlusive Glycan Bindings Govern Its Morbidities and Inform Therapeutic Responses

Consistent with the biochemistry of coronaviruses as well established over decades, SARS-CoV-2 makes its initial attachment to host cells through the binding of its spike protein (SP) to sialylated glycans (containing the monosaccharide sialic acid) on the cell surface. The virus can then slide over and enter via ACE2. SARS-CoV-2 SP attaches particularly tightly to the trillions of red blood cells (RBCs), platelets and endothelial cells in the human body, each cell very densely coated with sialic acid surface molecules but having no ACE2 or minimal ACE2. These interlaced attachments trigger the blood cell aggregation, microvascular occlusion and vascular damage that underlie the hypoxia, blood clotting and related morbidities of severe COVID-19. Notably, the two human betacoronaviruses that express a sialic acid-cleaving enzyme are benign, while the other three-SARS, SARS-CoV-2 and MERS-are virulent. RBC aggregation experimentally induced in several animal species using an injected polysaccharide caused most of the same morbidities of severe COVID-19. This glycan biochemistry is key to disentangling controversies that have arisen over the efficacy of certain generic COVID-19 treatment agents and the safety of SP-based COVID-19 vaccines. More broadly, disregard for the active physiological role of RBCs yields unreliable or erroneous reporting of pharmacokinetic parameters as routinely obtained for most drugs and other bioactive agents using detection in plasma, with whole-blood levels being up to 30-fold higher. Appreciation of the active role of RBCs can elucidate the microvascular underpinnings of other health conditions, including cardiovascular disease, and therapeutic opportunities to address them.

Role of Perivascular Adipose Tissue in Aorta Reactivity from Obese and Hyperglycemic CD-1 Mice: New Insights into Perivascular Adipose Tissue

Background: Perivascular adipose tissue (PVAT) plays an essential role in cardiovascular homeostasis. However, during obesity and diabetes, its role in vascular tone regulation is unclear. This study aimed to evaluate the function of the PVAT on aorta reactivity in the lean and cafeteria (CAF) diet-induced obese-hyperglycemic mice model. Methods: Aorta reactivity to phenylephrine, KCl, and acetylcholine was analyzed in lean (n = 6) and obese mice (n = 6). Also, nitric oxide (NO-) and cyclooxygenase participation, in the presence (n = 6) and absence (n = 6) of PVAT, were examined in the aortas. Results: After a CAF diet for 19 weeks, obese mice showed increased body weight, glucose intolerance, and hypercholesterolemia concerning lean mice. Vascular reactivity to phenylephrine was reduced significantly in the aorta of obese mice. In contrast, the contraction produced by KCl (80 mM) was increased in the aorta of obese mice independent of PVAT. Acetylcholine-induced vasorelaxation diminished in the aortas of obese mice in the presence of PVAT. Nonselective inhibition of cyclooxygenases likely shows that PVAT and endothelium release vasorelaxant prostanoids. Conclusions: The results suggest that PVAT modulates aorta reactivity by releasing NO-, decreasing the α₁-adrenergic response to phenylephrine, and probably releasing vasorelaxant prostanoids. The data suggest that PVAT regulates the vascular smooth muscle and endothelial function in a CAF diet-induced obese-hyperglycemic mice model.

Dysregulated insulin secretion is associated with pancreatic β-cell hyperplasia and direct acinar-β-cell trans-differentiation in partially eNOS-deficient mice

eNOS-deficient mice were previously shown to develop hypertension and metabolic alterations associated with insulin resistance either in standard dietary conditions (eNOS-/- homozygotes) or upon high-fat diet (HFD) (eNOS+/- heterozygotes). In the latter heterozygote model, the present study investigated the pancreatic morphological changes underlying the abnormal glycometabolic phenotype. C57BL6 wild type (WT) and eNOS+/- mice were fed with either chow or HFD for 16 weeks. After being longitudinally monitored for their metabolic state after 8 and 16 weeks of diet, mice were euthanized and fragments of pancreas were processed for histological, immuno-histochemical and ultrastructural analyses. HFD-fed WT and eNOS+/- mice developed progressive glucose intolerance and insulin resistance. Differently from WT animals, eNOS+/- mice showed a blunted insulin response to a glucose load, regardless of the diet regimen. Such dysregulation of insulin secretion was associated with pancreatic β-cell hyperplasia, as shown by larger islet fractional area and β-cell mass, and higher number of extra-islet β-cell clusters than in chow-fed WT animals. In addition, only in the pancreas of HFD-fed eNOS+/- mice, there was ultrastructural evidence of a number of hybrid acinar-β-cells, simultaneously containing zymogen and insulin granules, suggesting the occurrence of a direct exocrine-endocrine transdifferentiation process, plausibly triggered by metabolic stress associated to deficient endothelial NO production. As suggested by confocal immunofluorescence analysis of pancreatic histological sections, inhibition of Notch-1 signaling, likely due to a reduced NO availability, is proposed as a novel mechanism that could favor both β-cell hyperplasia and acinar-β-cell transdifferentiation in eNOS-deficient mice with impaired insulin response to a glucose load.

Metabolically healthy versus unhealthy obese phenotypes in relation to hypertension incidence; a prospective cohort study

Background

Although obesity increases the risk of hypertension, the effect of obesity based on metabolic status on the incidence of hypertension is not known. This study aimed to determine the association between obesity phenotypes including metabolically unhealthy obesity (MUO) and metabolically healthy obesity (MHO) and the risk of hypertension incidence.

Methods

We conducted a prospective cohort study on 6747 adults aged 35–65 from Ravansar non-communicable diseases (RaNCD) study. Obesity was defined as body mass index above 30 kg/m² and metabolically unhealthy was considered at least two metabolic disorders based on the International Diabetes Federation criteria. Obesity phenotypes were categorized into four groups including MUO, MHO, metabolically unhealthy non obesity (MUNO), and metabolically healthy non obesity (MHNO). Cox proportional hazards regression models were applied to analyze associations with hypertension incidence.

Results

The MHO (HR: 1.37; 95% CI: 1.03–1.86) and MUO phenotypes (HR: 2.44; 95% CI: 1.81–3.29) were associated with higher hypertension risk compared to MHNO. In addition, MUNO phenotype was significantly associated with risk of hypertension incidence (HR: 1.65; 95% CI: 1.29–2.14).

Conclusions

Both metabolically healthy and unhealthy obesity increased the risk of hypertension incidence. However, the increase in metabolically unhealthy phenotype was higher.

Long-term high-fructose high-fat diet feeding elicits insulin resistance, exacerbates dyslipidemia and induces gut microbiota dysbiosis in WHHL rabbits

The metabolic syndrome (MetS) has become a global public health burden due to its link to cardiovascular disease and diabetes mellitus. The present study was designed to characterize the metabolic and cardiovascular disturbances, as well as changes in gut microbiota associated with high-fructose high-fat diet (HFFD)-induced MetS in Watanabe heritable hyperlipidemic (WHHL) rabbits. Twenty-one Watanabe rabbits were assigned to a control (n = 9) and HFFD (n = 12) groups, receiving a chow diet and a HFFD, respectively. During a 12-weeks protocol, morphological parameters were monitored; plasma fasting levels of lipids, glucose and insulin were measured and a glucose tolerance test (GTT) was performed. HOMA-IR was calculated. Cardiac function and vascular reactivity were evaluated using the Langendorff isolated heart and isolated carotid arteries methods, respectively. 16S rRNA sequencing of stool samples was used to determine gut microbial composition and abundance. HFFD-fed Watanabe rabbits exhibited increased fasting insulin (p < 0.03, 12^th week vs. Baseline), HOMA-IR (p < 0.03 vs. Control), area under the curve of the GTT (p < 0.02 vs. Control), triglycerides (p < 0.05, 12^th week vs. Baseline), TC (p < 0.01 vs. Control), LDL-C (p < 0.001 vs. Control). The HFFD group also displayed a significant decrease in intestinal microbial richness, evenness and diversity (FDR < 0.001, FDR < 0.0001, FDR < 0.01, respectively vs. Control group) and an increase in its Firmicutes/Bacteroidetes ratio (R = 3.39 in control vs. R = 28.24 in the HFFD group) indicating a shift in intestinal microbial composition and diversity. Our results suggest that HFFD induces insulin resistance and gut microbiota dysbiosis and accentuates dyslipidemia; and that, when subjected to HFFD, Watanabe rabbits might become a potential diet-induced MetS animal models with two main features, dyslipidemia and insulin resistance.

Skeletal Muscle Microvascular Dysfunction in Obesity-Related Insulin Resistance: Pathophysiological Mechanisms and Therapeutic Perspectives

Obesity is a worrisomely escalating public health problem globally and one of the leading causes of morbidity and mortality from noncommunicable disease. The epidemiological link between obesity and a broad spectrum of cardiometabolic disorders has been well documented; however, the underlying pathophysiological mechanisms are only partially understood, and effective treatment options remain scarce. Given its critical role in glucose metabolism, skeletal muscle has increasingly become a focus of attention in understanding the mechanisms of impaired insulin function in obesity and the associated metabolic sequelae. We examined the current evidence on the relationship between microvascular dysfunction and insulin resistance in obesity. A growing body of evidence suggest an intimate and reciprocal relationship between skeletal muscle microvascular and glucometabolic physiology. The obesity phenotype is characterized by structural and functional changes in the skeletal muscle microcirculation which contribute to insulin dysfunction and disturbed glucose homeostasis. Several interconnected etiologic molecular mechanisms have been suggested, including endothelial dysfunction by several factors, extracellular matrix remodelling, and induction of oxidative stress and the immunoinflammatory phenotype. We further correlated currently available pharmacological agents that have deductive therapeutic relevance to the explored pathophysiological mechanisms, highlighting a potential clinical perspective in obesity treatment.

CD8+T Cell-Related Gene Biomarkers in Macular Edema of Diabetic Retinopathy

BACKGROUND

CD8+T lymphocytes have a strong pro-inflammatory effect in all parts of the tissue, and some studies have demonstrated that its concentration in the vitreous increased significantly, suggesting that CD8+T cells play a pivotal role in the inflammatory response of diabetic retinopathy (DR). However, the infiltration of CD8+T cells in the DR retina, especially in diabetic macular edema (DME), and its related genes are still unclear.

METHODS

Download the GSE16036 dataset from the Gene Expression Omnibus (GEO) database. The ImmuCellAI program was performed to evaluate the abundance of 24 immune cells including CD8+T cells. The CD8+T cell-related genes (DECD8+TRGs) between non-proliferative diabetic retinopathy (NPDR) and DME were detected via difference analysis and correlation analysis. Enrichment analysis and protein-protein interaction (PPI) network mapping were implemented to explore the potential function of DECD8+TRGs. Lasso regression, support vector machine recursive feature elimination (SVM-RFE), CytoHubba plug-in and MCODE plug-in in Cytoscape software, and Weighted Gene Co-Expression Network Analysis (WGCNA) were performed to comprehensively analyze and obtain Hub DECD8+TRGs. Hub DECD8+TRGs expression patterns were further validated in other two DR-related independent datasets. The CD8+TRG score was defined as the genetic characterization of Hub DECD8+TRGs using the GSVA sample scoring method, which can be administered to distinguish early and advanced diabetic nephropathy (DN) as well as normal and DN. Finally, the transcription level of DECD8+TRGs in DR model mouse were verified by quantitative real-time PCR (qPCR).

RESULTS

A total of 371 DECD8+TRGs were identified, of which 294 genes were positively correlated and only 77 genes were negatively correlated. Eight genes (IKZF1, PTPRC, ITGB2, ITGAX, TLR7, LYN, CD74, SPI1) were recognized as Hub DECD8+TRGs. DR and DN, which have strong clinical correlation, have been proved to be associated with CD8+T cell-related hub genes by multiple independent data sets. Hub DECD8+TRGs can not only distinguish PDR from normal and DN from normal, but also play a role in the early and progressive stages of the two diseases (NPDR vs DME, Early DN vs Advanced DN). The qPCR transcription level and trend of Hub DECD8+TRGs in DR mouse model was basically the same as that in human transcriptome.

CONCLUSION

This study not only increases our understanding of the molecular mechanism of CD8+T cells in the progression of DME, but also expands people's cognitive vision of the molecular mechanism of crosstalk of CD8+T cells in the eyes and kidneys of patients with diabetes.

Aerobic Exercise Attenuates Pressure Overload-Induced Cardiac Dysfunction through Promoting Skeletal Muscle Microcirculation and Increasing Muscle Mass

Background

Aerobic exercise has been proven to have a positive effect on cardiac function after hypertension; however, the mechanism is not entirely clarified. Skeletal muscle mass and microcirculation are closely associated with blood pressure and cardiac function.

Objective

This study was designed to investigate the effects of aerobic exercise on the skeletal muscle capillary and muscle mass, to explore the possible mechanisms involved in exercise-induced mitigation of cardiac dysfunction in pressure overload mice.

Methods

In this study, 60 BALB/C mice aged 8 weeks were randomly divided into 3 groups: control (CON), TAC, and TAC plus exercise (TAE) group and utilized transverse aortic constriction (TAC) to establish hypertensive model; meanwhile, treadmill training is used for aerobic exercise. After 5 days of recovery, mice in the TAE group were subjected to 10-week aerobic exercise. Carotid pressure and cardiac function were examined before mice were executed by Millar catheter and ultrasound, respectively. Muscle mass of gastrocnemius was weighed; cross-sectional area and the number of capillaries of gastrocnemius were detected by HE and immunohistochemistry, respectively. The mRNA and protein levels of VEGF in skeletal muscle were determined by RT-PCR and western blot, respectively.

Results

We found that ① 10-week aerobic exercise counteracted hypertension and attenuated cardiac dysfunction in TAC-induced hypertensive mice; ② TAC decreased muscle mass of gastrocnemius and resulted in muscle atrophy, while 10-week aerobic exercise could reserve transverse aortic constriction-induced the decline of muscle mass and muscle atrophy; and ③ TAC reduced the number of capillaries and the protein level of VEGF in gastrocnemius, whereas 10-week aerobic exercise augmented the number of capillaries, the mRNA and protein levels of VEGF in mice were subjected to TAC surgery.

Conclusions

This study indicates that 10-week aerobic exercise might fulfill its blood pressure-lowering effect via improving skeletal muscle microcirculation and increasing muscle mass.

Supplemental Watermelon Juice Attenuates Acute Hyperglycemia-Induced Macro-and Microvascular Dysfunction in Healthy Adults

BACKGROUND

Acute hyperglycemia reduces NO bioavailability and causes macro- and microvascular dysfunction. Watermelon juice (WMJ) is a natural source of the amino acid citrulline, which is metabolized to form arginine for the NO cycle and may improve vascular function.

OBJECTIVES

We examined the effects of 2 weeks of WMJ compared to a calorie-matched placebo (PLA) to attenuate acute hyperglycemia-induced vascular dysfunction.

METHODS

In a randomized, placebo-controlled, double-blind, crossover trial, 6 men and 11 women (aged 21-25; BMI, 23.5 ± 3.2 kg/m2) received 2 weeks of daily WMJ (500 mL) or a PLA drink followed by an oral-glucose-tolerance test. Postprandial flow-mediated dilation (FMD) was measured by ultrasound (primary outcome), while postprandial microvascular blood flow (MVBF) and ischemic reperfusion were measured by near-infrared spectroscopy (NIRS) vascular occlusion test (VOT).

RESULTS

The postprandial FMD area AUC was higher after WMJ supplementation compared to PLA supplementation (838 ± 459% · 90 min compared with 539 ± 278% · 90 min; P = 0.03). The postprandial MVBF (AUC) was higher (P = 0.01) following WMJ supplementation (51.0 ± 29.1 mL blood · 100 mL tissue-1 · min-1 · 90 min) compared to the PLA (36.0 ± 20.5 mL blood · 100 mL tissue-1 · min-1 · 90 min; P = 0.01). There was a significant treatment effect (P = 0.048) for WMJ supplementation (71.2 ± 1.5%) to increase baseline tissue oxygen saturation (StO2%) when compared to PLA (65.9 ± 1.7%). The ischemic-reperfusion slope was not affected by WMJ treatment (P = 0.83).

CONCLUSIONS

Two weeks of daily WMJ supplementation improved FMD and some aspects of microvascular function (NIRS-VOT) during experimentally induced acute hyperglycemia in healthy adults. Preserved postprandial endothelial function and enhanced skeletal muscle StO2% are likely partially mediated by increased NO production (via citrulline conversion into arginine) and by the potential antioxidant effect of other bioactive compounds in WMJ.

INERTIA: A pilot study of the impact of progressive resistance training on blood pressure control in older adults with sarcopenia

Sarcopenia, and high blood pressure are highly prevalent, preventable conditions that pose significant burden for older adults and on the healthcare system. Current prevention and treatment of high blood pressure in sarcopenia, by non-pharmacological approaches remain limited and are far from optimal. Clinical trials and mechanistic studies provide encouraging evidence of a plausible therapeutic effect of progressive resistance training (PRT) on blood pressure in younger, and pre-hypertensive and hypertensive older adults. The impact of PRT on blood pressure has not been empirically tested in older adults with sarcopenia. This pilot study aims to provide effect size confidence intervals, clinical trial and intervention feasibility data, and procedural materials for a full-scale randomized controlled trial that will determine the efficacy of PRT intervention as a therapeutic strategy for blood pressure control in older adults with sarcopenia. Participants (N = 90) will be randomized to receive exercise educational materials or the PRT intervention consisting of 24 supervised exercise sessions over 12-weeks. Follow-up assessments will occur at 12-weeks and one-year later. The primary outcome is systolic blood pressure and diastolic blood pressure, analyzed separately. Microvascular mechanisms linking muscle (perfusion, strength, function) to changes in blood pressure will be explored at baseline and 12-weeks. This study will provide new evidence for the therapeutic effect of PRT as a non-pharmacological strategy for improving blood pressure. Insights gained may also inform of the potential role of muscle strength as a novel target for blood pressure control, and future exercise prescription guidelines related to muscle strengthening in high-risk older adults.

Trends in the prevalence of hypertension according to severity and phenotype in Chinese adults over two decades (1991-2015)

Until recently, few studies have reported the secular trend and associated factors of hypertension severities and phenotypes in China. In this study, the authors aimed to assess the trend in the prevalence of hypertension according to severity and phenotype in Chinese adults from 1991 to 2015 and to explore potential cardiometabolic factors. From the China Health and Nutrition Survey (CHNS), the authors included 164 682 records of adults (≥18 years). The prevalence of hypertension by severity (stage 1 and stage 2 hypertension) and by phenotype (isolated systolic hypertension [ISH], isolated diastolic hypertension [IDH], and systolic-diastolic hypertension [SDH]), during 1991-2015 was explored. The potential effects of demographic, socioeconomic, geographic, and cardiometabolic factors on hypertension severities and phenotypes were assessed by multivariable logistic regression. During 1991-2015, the overall prevalence of hypertension increased dramatically from 15.7% to 23.3%. For stage 1 and stage 2 hypertension, the age-standardized prevalence increased from 10.1% to 15.6% and from 5.5% to 7.4%, respectively. For ISH and SDH, the age-standardized prevalence rates rose from 3.6% to 6.4% and from 6.9% to 10.4%, respectively. Advanced age and medium/high urbanization were positively associated factors, whereas females, higher educational attainments, and residing in Southern China were negatively associated factors. Additionally, general obesity, central obesity, diabetes, and elevated triglyceride levels were linked to ISH, IDH, and SDH. The present study documents an increasing trend in the prevalence of hypertension, including different severities and phenotypes, among Chinese adults over more than two decades. Efforts for the prevention and management of hypertension are in urgent need in China.

Microvascular imaging and monitoring of hemodynamic changes in the skin during arterial-venous occlusion using multispectral raster-scanning optoacoustic mesoscopy

The ability to monitor oxygen delivery in microvasculature plays a vital role in measuring the viability of skin tissue and the probability of recovery. Using currently available clinical imaging tools, it is difficult to observe non-invasive hemodynamic regulation in the peripheral vessels. Here we propose the use of a novel multispectral raster-scanning optoacoustic mesoscopy (RSOM) system for noninvasive clinical monitoring of hemodynamic changes in the skin microvasculature's oxy- (HbO₂) and deoxy-hemoglobin (Hb), total hemoglobin (HbT) and oxygen saturation (rsO₂). High resolution images of hemoglobin distribution in the skin microvasculature from six healthy volunteers during venous and arterial occlusion, simulating systemic vascular diseases are presented. During venous occlusion, Hb and HbO₂ optoacoustic signals showed an increasing trend with time, followed by a drop in the values after cuff deflation. During arterial occlusion, an increase in Hb value and decrease in HbO₂ values was observed, followed by a drop in Hb and jump in HbO₂ values after the cuff deflation. A decrease in rsO₂ values during both venous and arterial occlusion was observed with an increase in value after occlusion release. Using this proof of concept study, hereby we propose multispectral RSOM as a novel tool to measure high resolution hemodynamic changes in microvasculature for investigating systemic vascular diseases on peripheral tissues and also for monitoring inflammatory skin diseases, and its therapeutic interventions.

Skin microvascular function and renal hemodynamics in overweight patients with type 2 diabetes: A cross-sectional study

OBJECTIVE

Diabetic kidney disease is a microvascular complication of diabetes. Here, we assessed the association between skin microvascular function and renal hemodynamic function in a cohort of well-phenotyped adults with type 2 diabetes (T2D).

METHODS

We included 81 overweight/obese adults (age: 62 ± 8 years; BMI: 32 ± 4 kg/m² ) with well-controlled T2D and no renal impairment. Skin microvascular function was assessed by nailfold capillary density in rest and after arterial occlusion (ie, peak capillary density). Renal hemodynamic functions (ie, measured glomerular filtration rate [mGFR], effective renal blood flow [ERBF], filtration fraction [FF], and effective renal vascular resistance [ERVR]) were assessed by combined inulin and para-aminohippurate clearances and blood pressure measurements.

RESULTS

Skin capillary density was 45 ± 10 capillaries/mm² at baseline and 57 ± 11 capillaries/mm² during post-occlusive peak; mGFR averaged 108 ± 20 ml/min. In multivariable regression analyses, positive associations between capillary density during post-occlusive peak and mGFR (β = 0.224; p = 0.022) and ERBF (β = 0.203; p = 0.020) and a positive trend for hyperemia and mGFR (β = 0.391; p = 0.053) were observed, while a negative association for post-occlusive capillary density with ERVR (β = -0.196; p = 0.027) was found.

CONCLUSION

These findings indicate that microvascular dysfunction in overweight adults with T2D is associated with lower mGFR and ERPF and higher ERVR. We hypothesize that increased renal vascular resistance may contribute to glomerular dysfunction due to impaired renal perfusion.

Pancreatic Microcirculation Profiles in the Progression of Hypertension in Spontaneously Hypertensive Rats

BACKGROUND

Emerging evidence indicates that the pancreas serves as a major source of degrading protease activities and that uncontrolled proteolytic receptor cleavage occurs under hypertensive conditions, which leading to systemic dysfunction and end-organic damage. However, changes in pancreatic microcirculation profiles during the progression of hypertension remain unknown.

METHODS

Pancreatic microcirculatory blood distribution patterns and microvascular vasomotion of spontaneously hypertensive rats (SHRs) and normotensive control Wistar Kyoto rats at 5, 8, 13, and 18 weeks of age were determined. Wavelet transform analysis was performed to convert pancreatic microhemodynamic signals into time-frequency domains and construct 3-dimensional spectral scalograms. The amplitudes of characteristic oscillators including endothelial, neurogenic, myogenic, respiratory, and cardiac oscillators were compared among groups. Plasma nitrite/nitrate levels were measured using a Griess reaction. Additionally, endothelin-1, malondialdehyde, superoxide dismutase, and interleukin-6 levels were determined by enzyme-linked immunosorbent assay.

RESULTS

SHRs exhibited a reduced blood distribution pattern with progressively decreased average blood perfusion, amplitude, and frequency of microvascular vasomotion. Wavelet transform spectral analysis revealed significantly reduced amplitudes of endothelial oscillators from 8- to 18-week-old SHRs. Additionally, the blood microcirculatory chemistry complements explained the microhemodynamic profiles partially, as demonstrated by an increase in plasma nitrite/nitrate, endothelin-1, malondialdehyde, and interleukin-6 levels and a decreased superoxide dismutase level in SHRs.

CONCLUSIONS

Pancreatic microcirculation profiles are abnormal in the progression of hypertension in SHRs, including a disarranged blood distribution pattern, impaired microvascular vasomotion, and reduced amplitudes of endothelial oscillators.

Impairment of microvascular blood flow in patients with type 2 diabetes and cardiovascular autonomic neuropathy

BACKGROUND: Diabetic autonomic neuropathy is the reason for early morbidity and mortality on diabetic patients. The pathology not only cardiac innervation but microvascular is presented.

AIMS: We estimated the parameters of skin microvascular blood flow in accordance with cardiovascular autonomic neuropathy (CAN) staging in diabetic patients. We also assessed other risk factors of CAN in patients with diabetes.

MATERIALS AND METHODS: We included 76 patients with type 2 diabetes in the study (24 patients with resent-onset diabetes and/or diabetes without microvascular complications, 26 with diabetic sensorimotor neuropathy (SMN) and 26 with SMN and previous history of diabetic foot amputation). The SMN was diagnosed on the basis of patients complaints, anamnesis and data of clinical neurological examinations. CAN was detected using several cardiovascular autonomic reflex tests (CART) as a gold standard of diagnosis: the tilt-table test, a deepbreathing and Valsalva Maneuver, handgrip test, cold-stress vasoconstriction. According to the Toronto Diabetic Neuropathy Expert Group Recommendation all patients was separated on the groups: CAN 0 (all CARTs were normal), CAN 1 (possible/early CAN — one abnormal CART was presented), CAN 2 (definite/confirmed CAN –at least two abnormal CARTs were found), CAN 3 (severe/advanced CAN — in the cases of orthostatic hypotension in addition to CARTs abnormalities). Microvascular blood flow of skin at the nail roller of fingers skin was valuated at rest as well as in functional cold test by the method of High-frequency Ultrasonic Dopplerography using the “Minimax Doppler K” device (LLC JV “Minimax”, St. Petersburg, Russia).

RESULTS: CAN 1 was found in 8% diabetic patients without microvascular complications, 42 and 21% patients with SMN and diabetic foot amputations respectively. CAN 2 was diagnosed in 27% patients with SMN and 58% patients history of diabetic foot amputations. CAN 3 in 8% and 19% cases in patients with SMN and history of diabetic foot amputations respectively. The parameters of microvascular blood flow at rest were significantly decreased in patients with confirmed/severe CAN in comparison with early staging of CAN and patients without CAN (Vm=2.5±0.66 sm/sec vs. 4.4±0.54 sm/sec and 5.1±1.01 sm/sec respectively; p=0.0033). The abnormal result of cold test was detected in 94% patients with confirmed/ severe CAN and 26% patients with CAN 1.

CONCLUSIONS: This investigation has demonstrated in a cohort with type 2 diabetes patients with/without SMN and with/ without history of previously foot amputations that decrease the Vm (the variable of microvascular blood flow assessed by High-frequency Ultrasonic Dopplerography) lower than 2.4 sm/sec is associated with 6.4 times increased likelihood of confirmed/severe CAN as well as positive cold test result. That the patients with positive cold test results were 28.6 times more likely have confirmed/severe CAN.

Comparison of pancreatic microcirculation profiles in spontaneously hypertensive rats and Wistar-kyoto rats by laser doppler and wavelet transform analysis

Pancreatic microcirculatory dysfunction emerged as a novel mechanism in the development of hypertension. However, the changes of pancreatic microcirculation profiles in hypertension remain unknown. Pancreatic microcirculatory blood distribution pattern and microvascular vasomotion of spontaneously hypertensive rats (SHRs) and Wistar Kyoto rats (WKYs) were determined by laser Doppler. Wavelet transform analysis was performed to convert micro-hemodynamic signals into time-frequency domains, based on which amplitude spectral scalograms were constructed. The amplitudes of characteristic oscillators were compared between SHRs and WKYs. The expression of eNOS was determined by immunohistochemistry, and plasma nitrite/nitrate levels were measured by Griess reaction. Additionally, endothelin-1, malondialdehyde, superoxide dismutase and interleukin-6 were determined by enzyme-linked immunosorbent assay. SHRs exhibited a lower scale blood distribution pattern with decreased average blood perfusion, frequency and amplitude. Wavelet transform spectral analysis revealed significantly reduced amplitudes of endothelial oscillators. Besides reduced expression of eNOS, the blood microcirculatory chemistry complements micro-hemodynamic profiles as demonstrated by an increase in plasma nitrite/nitrate, endothelin-1, malondialdehyde, interleukin-6 and a decrease of superoxide dismutase in SHRs. Here, we described abnormal pancreatic microcirculation profiles in SHRs, including disarranged blood distribution pattern, impaired microvascular vasomotion and reduced amplitudes of endothelial oscillators.

Effects of high intensity interval training on neuro-cardiovascular dynamic changes and mitochondrial dysfunction induced by high-fat diet in rats

BACKGROUND AND AIMS

Mitochondrial swelling is involved in the pathogenesis of many human diseases associated with oxidative stress including obesity. One of the strategies for prevention of deleterious effects related to obesity and overweight is engaging in regular physical activity, of which high intensity interval training (HIIT) is efficient in promoting biogenesis and improving the function of mitochondria. Therefore, our aims were to investigate the effects of HIIT on metabolic and neuro-cardiovascular dynamic control and mitochondrial swelling induced by high-fat diet (HFD).

METHODS AND RESULTS

Twenty-three male Wistar rats (60 - 80g) were divided into 4 subgroups: control (C), HIIT, HFD and HFD+HIIT. The whole experimentation period lasted for 22 weeks and HIIT sessions were performed 5 days a week during the last 4 weeks. At the end of the experiments, fasting glucose and insulin tolerance tests were performed. Cerebral microcirculation was analyzed using cortical intravital microscopy for capillary diameter and functional density. Cardiac function and ergoespirometric parameters were also investigated. Mitochondrial swelling was evaluated on brain and heart extracts. HFD promoted an increase on body adiposity (p<0.001), fasting glucose levels (p<0.001), insulin resistance index (p<0.05), cardiac hypertrophy index (p<0.05) and diastolic blood pressure (p<0.05), along with worsened cardiac function (p<0.05), reduced functional cerebral capillary density (p<0.05) and its diameter (p<0.01), and heart and brain mitochondrial function (p<0.001). HFD did not affect any ergoespirometric parameter. After 4 weeks of training, HIIT was able to improve cardiac hypertrophy index, diastolic blood pressure, cerebral functional capillary density (p<0.01) and heart and brain mitochondrial swelling (p<0.001).

CONCLUSION

In animals subjected to HFD, HIIT ameliorated both cerebral mitochondrial swelling and functional capillary density, but it did not improve cardiovascular function suggesting that the cardiovascular dysfunction elicited by HFD was not due to heart mitochondrial swelling.

Treatment of microcirculation dysfunction in type 2 diabetic mellitus with Shenqi compound prescription: A protocol of systematic review and meta-analysis of randomized clinical trials

INTRODUCTION

Type 2 diabetic mellitus (T2DM) is a chronic disease. In 2013, the International Diabetes Federation showed that the total number of diabetic patients aged 20 to 79 years in China was 89 million, and it is expected to increase to 143 million by 2035. The incidence of T2DM and its complications in patients with blood glucose is gradually increasing, and there are low awareness rate, low diagnosis rate and high disability rate, which has become a global public health problem. Microcirculation Dysfunction in Type 2 diabetic mellitus (MDT2DM) plays an important role in the development of diabetic nephropathy, diabetic retinopathy, diabetic neuropathy and diabetic foot disease. It is 1 of the common etiological mechanisms of diabetic chronic complications. Patients with MDT2DM, serious complications, increase the quality of life of patients with social impact. Diabetic lower extremity microcirculation disease (dlemd) is the main cause of the occurrence, development and difficult healing of diabetic foot. Microvascular disease is microcirculation dysfunction. It has been proved that Shenqi compound prescription can treat T2DM macrovascular disease and microvascular dysfunction. However, due to the lack of evidence and no specific methods or suggestions, it is necessary to conduct a systematic evaluation of Shenqi compound prescription to provide effective evidence for further research.

METHODS AND ANALYSIS

The following databases will be searched from their inception to August 2020: Electronic database includes PubMed, Embase, Cochrane Library, Web of Science, Nature, Science online, Chinese Biomedical Database WanFang, VIP medicine information, and China National Knowledge Infrastructure. PRIMARY OUTCOMES:: superoxide dismutase, malondialdehyde, C-reactiveprotein, HOMA-IR, advanced glycation end products , FPG, 2hBG, glycosylated hemoglobinA1c, fasting insulin ; ADDITIONAL OUTCOMES:: low density lipoprotein, high density lipoprotein, triglycerides, total serum cholesterol. Data will be extracted by 2 researchers independently, risk of bias of the meta-analysis will be evaluated based on the Cochrane Handbook for Systematic Reviews of Interventions. All data analysis will be conducted by data statistics software Review Manager V.5.3. and Stata V.12.0.

RESULTS

The results of this study will systematically evaluate the efficacy and safety of Shenqi compound prescription in treating patients with MDT2DM CONCLUSION:: The systematic review of this study will summarize the current published evidence of Shenqi compound prescription in the treatment of MDT2DM, and further guide its popularization and application.

ETHICS AND DISSEMINATION

This study is a systematic review, the outcomes are based on the published evidence, so examination and agreement by the ethics committee are not required in this study. We intend to publish the study results in a journal or conference presentations.

OPEN SCIENCE FRA MEWORK (OSF) REGISTRATION NUMBER

August 24, 2020.osf.io/es6z7. (https://osf.io/es6z7).

Arterial stiffness and pressure wave reflection in the development of isolated diastolic hypertension

OBJECTIVES

This prospective study was conducted to clarify the significance of augmented pressure wave reflection without accompanying increased arterial stiffness in the development of isolated diastolic hypertension (IDHT).

METHODS

A total of 3022 Japanese men without hypertension at the start of this study were included in the analyses. The blood pressure, brachial--ankle pulse wave velocity (brachial-ankle PWV), and radial augmentation index (rAI) were measured annually from year 2007 through year 2015.

RESULTS

At the end of the study period, 129 participants were diagnosed as having systolic/diastolic hypertension (SDHT), 112 as having isolated systolic hypertension (ISHT), and 74 as having IDHT. Both the brachial--ankle PWV and rAI showed significant individual odds ratios for new onset of SDHT and new onset of ISHT. However, only rAI, but not the brachial--ankle PWV, showed a significant odds ratio (1.44, P < 0.01) for new onset of IDHT. This association was significant in participants without elevated brachial--ankle PWV values at the start of the study, but not in those with elevated brachial--ankle PWV at the start of the study. Generalized estimating equation analyses demonstrated a significant longitudinal association of the rAI, but not brachial--ankle PWV, with the development of IDHT.

CONCLUSION

Although increased arterial stiffness and augmented pressure wave reflection present concomitantly may be associated with the development of SDHT and ISHT, augmented pressure wave reflection alone, which may be related to isolated peripheral vascular damage, in the absence of accompanying increase of the arterial stiffness, may be a significant factor in the development of IDHT.

Microvascular Phenotyping in the Maastricht Study: Design and Main Findings, 2010-2018

Microvascular dysfunction (MVD) is a common pathophysiological change that occurs in various diseases, such as type 2 diabetes mellitus (T2DM), heart failure, dementia, and depression. Recent technical advances have enabled noninvasive measurement and quantification of microvascular changes in humans. In this paper, we describe the protocols of the microvascular measurements applied in the Maastricht Study, an ongoing prospective, population-based cohort study of persons aged 40–75 years being carried out in the southern part of the Netherlands (baseline data assessment, November 2010–January 2020). The study includes a variety of noninvasive measurements in skin, retina, brain, and sublingual tissue, as well as plasma and urine biomarker assessments. Following this, we summarize our main findings involving these microvascular measurements through the end of 2018. Finally, we provide a brief perspective on future microvascular investigations within the framework of the Maastricht Study.

TRAF3IP2 (TRAF3 Interacting Protein 2) Mediates Obesity-Associated Vascular Insulin Resistance and Dysfunction in Male Mice

Insulin resistance in the vasculature is a characteristic feature of obesity and contributes to the pathogenesis of vascular dysfunction and disease. However, the molecular mechanisms underlying obesity-associated vascular insulin resistance and dysfunction remain poorly understood. We hypothesized that TRAF3IP2 (TRAF3 interacting protein 2), a proinflammatory adaptor molecule known to activate pathological stress pathways and implicated in cardiovascular diseases, plays a causal role in obesity-associated vascular insulin resistance and dysfunction. We tested this hypothesis by employing genetic-manipulation in endothelial cells in vitro, in isolated arteries ex vivo, and diet-induced obesity in a mouse model of TRAF3IP2 ablation in vivo. We show that ectopic expression of TRAF3IP2 blunts insulin signaling in endothelial cells and diminishes endothelium-dependent vasorelaxation in isolated aortic rings. Further, 16 weeks of high fat/high sucrose feeding impaired glucose tolerance, aortic insulin-induced vasorelaxation, and hindlimb postocclusive reactive hyperemia, while increasing blood pressure and arterial stiffness in wild-type male mice. Notably, TRAF3IP2 ablation protected mice from such high fat/high sucrose feeding-induced metabolic and vascular defects. Interestingly, wild-type female mice expressed markedly reduced levels of TRAF3IP2 mRNA independent of diet and were protected against high fat/high sucrose diet-induced vascular dysfunction. These data indicate that TRAF3IP2 plays a causal role in vascular insulin resistance and dysfunction. Specifically, the present findings highlight a sexual dimorphic role of TRAF3IP2 in vascular control and identify it as a promising therapeutic target in vasculometabolic derangements associated with obesity, particularly in males.

Association of triglycerides to high-density lipoprotein-cholesterol ratio with risk of incident hypertension

The triglyceride to high-density lipoprotein-cholesterol (TG/HDL-C) ratio is considered a simple surrogate of insulin resistance. The aim of this study was to explore the association of the TG/HDL-C ratio with the risk of incident hypertension and whether the TG/HDL-C ratio mediates the obesity-incident hypertension association. The study analyzed 9679 participants from a rural Chinese population. Demographic and anthropometric and laboratory data were collected at baseline (2007-2008) and follow-up (2013-2014) examinations. A multivariate logistic regression model was used to analyze the association of the TG/HDL-C ratio with incident hypertension, estimating odds ratios (ORs) and 95% confidence intervals (CIs). Mediation analysis was performed to examine the contribution of the TG/HDL-C ratio to obesity-related incident hypertension. During a median follow-up of 6.00 years, hypertension developed in 1880/9679 participants (19.42%). The risk of incident hypertension was higher in the highest TG/HDL-C ratio quartile than in the lowest quartile (OR = 1.21, 95% CI = 1.02-1.42). Subgroup analyses showed that the risk of incident hypertension was increased by 30%, 36%, and 33% among women, participants < 60 years old and those with prehypertension at baseline, respectively. The TG/HDL-C ratio partially mediated the obesity-incident hypertension association (indirect effect: OR = 1.04, 95% CI: 1.01-1.07; direct effect: OR = 1.36, 95% CI: 1.16-1.62). The TG/HDL-C ratio may be a risk factor for incident hypertension, especially in women, participants < 60 years old and those with prehypertension. The TG/HDL-C ratio may also play a mediating role in obesity-related incident hypertension.

Mechanistic Links Between Obesity, Diabetes, and Blood Pressure: Role of Perivascular Adipose Tissue

Obesity is increasingly prevalent and is associated with substantial cardiovascular risk. Adipose tissue distribution and morphology play a key role in determining the degree of adverse effects, and a key factor in the disease process appears to be the inflammatory cell population in adipose tissue. Healthy adipose tissue secretes a number of vasoactive adipokines and anti-inflammatory cytokines, and changes to this secretory profile will contribute to pathogenesis in obesity. In this review, we discuss the links between adipokine dysregulation and the development of hypertension and diabetes and explore the potential for manipulating adipose tissue morphology and its immune cell population to improve cardiovascular health in obesity.

Plin5/p-Plin5 Guards Diabetic CMECs by Regulating FFAs Metabolism Bidirectionally

Background

Hyper-free fatty acidemia (HFFA) impairs cardiac capillaries, as well as type 2 diabetes mellitus (T2DM). Perilipin 5 (Plin5) maintains metabolic balance of free fatty acids (FFAs) in high oxidative tissues via the states of nonphosphorylation and phosphorylation. However, when facing to T2DM-HFFA, Plin5's role in cardiac microvascular endothelial cells (CMECs) is not defined.

Methods

In mice of WT or Plin5^−/−, T2DM models were rendered by high-fat diet combined with intraperitoneal injection of streptozocin. CMECs isolated from left ventricles were incubated with high glucose (HG) and high FFAs (HFFAs). Plin5 phosphorylation was stimulated by isoproterenol. Plin5 expression was knocked down by small interfering RNA (siRNA). We determined cardiac function by small animal ultrasound, apoptotic rate by flow cytometry, microvessel quantity by immunohistochemistry, microvascular integrity by scanning electron microscopy, intracellular FFAs by spectrophotometry, lipid droplets (LDs) by Nile red staining, mRNAs by quantitative real-time polymerase chain reaction, proteins by western blots, nitric oxide (NO) and reactive oxygen species (ROS) by fluorescent dye staining and enzyme-linked immunosorbent assay kits.

Results

In CMECs, HFFAs aggravated cell injury induced by HG and activated Plin5 expression. In mice with T2DM-HFFA, Plin5 deficiency reduced number of cardiac capillaries, worsened structural incompleteness, and enhanced diastolic dysfunction. Moreover, in CMECs treated with HG-HFFAs, both ablation and phosphorylation of Plin5 reduced LDs content, increased intracellular FFAs, stimulated mitochondrial β-oxidation, added ROS generation, and reduced the expression and activity of endothelial nitric oxide synthase (eNOS), eventually leading to increased apoptotic rate and decreased NO content, all of which were reversed by N-acetyl-L-cysteine.

Conclusion

Plin5 preserves lipid balance and cell survival in diabetic CMECs by regulating FFAs metabolism bidirectionally via the states of nonphosphorylation and phosphorylation.

Magnesium lithospermate B ameliorates microcirculation perfusion in rats by promoting vascular NO production via activating the PI3K/AKT pathway

Microcirculation morphologically refers to the blood flow in vessels of less than 150 μm in diameter, including arterioles, capillaries and venules, which provides nutrients and removes metabolic byproducts within tissues. Microcirculation dysfunction is involved in the pathological progress of many diseases, such as obesity, hypertension, and insulin resistance. In this study we investigated the effects of magnesium lithospermate B (MLB), an active compound of the traditional Chinese medicine Slavia miltiorrhiza, on the microcirculation dysfunction in rats and the underlying molecular mechanisms. The effects of MLB on microcirculation were assessed in vivo by measuring the hindlimb blood perfusion in dextran-induced microcirculation dysfunction rats and mesentery blood flow in anesthetized rats. We demonstrated that administration of MLB restored the impaired rat hindlimb blood flow and promoted the mesenteric micoperfusion in vivo. We further revealed in these two animal models that MLB treatment significantly increased the production of total nitrite in vascular tissues (mesentery, aorta, and heart), which was confirmed in human microvascular endothelial cells (HMEC-1) treated with MLB in vitro. Moreover, we showed that MLB treatment significantly increased the phosphorylation of endothelium nitric oxide synthase (eNOS) via inducing AKT phosphorylation in vivo and in vitro. Co-administration of the eNOS inhibitor L-NAME (20 mg/kg) abolished the protective effects of MLB against dextran-induced microcirculation dysfunction in rats, whereas pretreatment with PI3K inhibitor LY294002 (10 μM) prevented eNOS activation in MLB-treated HMEC-1 cells. Our results suggest that MLB can restore the microcirculation dysfunction via activating eNOS, and in turn enhancing the vascular nitric oxide production, which is medicated by MLB-caused activation of the PI3K/AKT pathway.

Vascular Dysfunction and Insulin Resistance in Aging

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Insulin was discovered in 1922 by Banting and Best. Since that time, extensive research on the mechanisms of insulin activity and action has continued. Currently, it is known that the role of insulin is much greater than simply regulating carbohydrate metabolism. Insulin in physiological concentration is also necessary to maintain normal vascular function.

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Insulin resistance is defined as a pathological condition characterized by reduced sensitivity of skeletal muscles, liver, and adipose tissue, to insulin and its downstream metabolic effects under normal serum glucose concentrations. There are also selective forms of insulin resistance with unique features, including vascular insulin resistance. Insulin resistance, both classical and vascular, contributes to vascular impairment resulting in increased risk of cardiovascular disease. Furthermore, in the elderly population, additional factors including redistribution of fat concentrations, low-grade inflammation, and decreased self-repair capacity [or cell senescence] amplify the vascular abnormalities related to insulin resistance.

Body mass index percentiles and elevated blood pressure among children and adolescents

It is well established that obesity is associated with an increased risk of elevated and high blood pressure (BP) in children and adolescents. However, it is uncertain whether there is an increase in the risk of elevated and high BP associated with an increase of body mass index (BMI) among children and adolescents whose BMI is in the accepted normal range. Data were available for 58 899 children and adolescents aged 6-17 years from seven national cross-sectional surveys in China, India, Iran, Korea, Poland, Tunisia, and the United States. The subjects were divided into eight percentile subgroups according to their BMI levels based on the World Health Organization recommendations. Elevated BP and high BP were defined using the 2016 international child BP criteria. Compared with the reference subgroup of the 5th-24th percentiles, the odds ratios (ORs) for high BP were 1.27 (95% confidence interval [CI], 1.14-1.41; P < 0.001) in the 25th-49th percentile subgroup, 1.55 (95% CI, 1.39-1.73; P < 0.001) in the 50th-74th percentile subgroup, and 2.17 (95% CI, 1.92-2.46; P < 0.001) in the 75th-84th percentile subgroup, respectively, after adjustment for sex, age, race/ethnicity, height and country. Additionally, the corresponding ORs for elevated BP were 1.21 (95% CI, 1.10-1.32; P < 0.001), 1.55 (95% CI, 1.42-1.69; P < 0.001), and 1.80 (95% CI, 1.62-2.01; P < 0.001), respectively. In conclusion, a BMI in the 25th-84th percentiles, within the accepted normal weight range, was associated with an increased risk of elevated and high BP among children and adolescents. It is important for children and adolescents to keep a BMI at a low level in order to prevent and control hypertension.

Low-Fat Diet Designed for Weight Loss But Not Weight Maintenance Improves Nitric Oxide-Dependent Arteriolar Vasodilation in Obese Adults

Obesity is associated with microvascular dysfunction. While low-fat diet improves cardiovascular risk, its contributions on microvascular function, independent of weight loss, is unknown. We tested the hypothesis that nitric oxide (NO)-dependent vasodilation in microvessels is improved by low-fat diets designed for weight loss (LFWL) compared to low-fat weight maintenance (LFWM) diet. Obese adults were randomly assigned to either a LFWL diet (n = 11) or LFWM diet (n = 10) for six weeks. Microvessels were obtained from gluteal subcutaneous fat biopsies before and after the intervention for vascular reactivity measurements to acetylcholine (Ach) and flow, with and without L-NAME or indomethacin. Vascular and serum NO and C-reactive protein (CRP) were also measured. LFWL diet increased flow-induced (FID) and ACh-induced dilation (AChID); an effect that was inhibited by L-NAME. Conversely, LFWM diet did not affect FID or AChID. Indomethacin improved FID and AChID in the baseline and this effect was minimized in response to both diets. Serum NO or CRP did not change in response to either diet. In conclusion, LFWL diet improves microvascular reactivity compared to LFWM diet and increased vascular NO contribution to the improved microvascular dilation. These data suggest that weight reduction on low fat diet is critical for microvascular health.

Microangiopathy in Naifold Videocapillaroscopy and Its Relations to sE- Selectin, Endothelin-1, and hsCRP as Putative Endothelium Dysfunction Markers among Adolescents with Raynaud's Phenomenon

The aim of this study was to analyze the relationship between the qualitative abnormalities on nailfold videocapillaroscopy (NVC), and the concentrations of selected biomarkers (sE-selectin, endothelin-1, high-sensitivity c-reactive protein (hsCRP)) and lipid metabolism parameters in children and adolescents with Raynaud’s phenomenon (RP). Raynaud’s phenomenon, to assess whether nailfold capillary changes may reflect the degree of systemic blood vessel abnormalities. The study group included 66 patients (34 undifferentiated—uRP and 32 secondary—sRP) aged 6–19 years and the control group. In both groups, NVC was performed and the selected biomarkers were measured (sE-selectin, endothelin-1, hsCRP) and lipid profile. Endothelin-1, sE-selectin and hsCRP concentrations in patients from both RP groups were significantly higher; concentration of HDL fraction was significantly lower compared with the control group. The analysis of multiple linear regression demonstrated that megacapillaries most strongly determine the sE-selectin value (p = 0.04) and hsCRP (p = 0.03). Both the total cholesterol and low-density lipoprotein (LDL) fraction concentrations were determined by the presence of avascular areas (p = 0.02). In conclusion, specific pathologic NVC changes were associated with higher endothelial damage biomarkers concentration and adverse changes in the lipid profile.

Microvascular imaging of the skin

Despite our understanding that the microvasculature plays a multifaceted role in the development and progression of various conditions, we know little about the extent of this involvement. A need exists for non-invasive, clinically meaningful imaging modalities capable of elucidating microvascular information to aid in our understanding of disease, and to aid in the diagnosis/monitoring of disease for more patient-specific care. In this review article, a number of imaging techniques are summarized that have been utilized to investigate the microvasculature of skin, along with their advantages, disadvantages and future perspectives in preclinical and clinical settings. These techniques include dermoscopy, capillaroscopy, Doppler sonography, laser Doppler flowmetry (LDF) and perfusion imaging, laser speckle contrast imaging (LSCI), optical coherence tomography (OCT), including its Doppler and dynamic variant and the more recently developed OCT angiography (OCTA), photoacoustic imaging, and spatial frequency domain imaging (SFDI). Attention is largely, but not exclusively, placed on optical imaging modalities that use intrinsic optical signals to contrast the microvasculature. We conclude that whilst each imaging modality has been successful in filling a particular niche, there is no one, all-encompassing modality without inherent flaws. Therefore, the future of cutaneous microvascular imaging may lie in utilizing a multi-modal approach that will counter the disadvantages of individual systems to synergistically augment our imaging capabilities.

Myogenic oxidative imbalance interferes with antral motility in obese subjects

BACKGROUND

Obesity is characterized by a systemic low-grade chronic inflammatory oxidative condition that affects vascular and cardiac smooth muscle relaxation. In human antrum, relaxation is mediated by vasoactive intestinal peptide (VIP) through cAMP and cGMP signaling pathways. A genome-wide association study has demonstrated an association between VIP and obesity.

AIM

To evaluate smooth muscle activity in human obese antrum, both in in vitro preparations as well as in vivo.

METHODS

Antral muscle strips and cells were isolated from surgical gastric samples from obese and normal weight subjects. Muscle contraction and relaxation, myogenic oxidative stress and inflammatory status were analyzed in vitro. Distal antral motility was evaluated in vivo by magnetic resonance imaging.

RESULTS

Obese antral muscle cells showed an oxidative-inflammatory imbalance with overexpression of NLRP3 inflammasome, increased IL-1β secretion and caspase1-activation, and reduced antioxidant capacity associated with a myogenic motor impairment of VIP-induced relaxation. The intracellular alterations were characterized by a decreased activation of the cAMP-signaling pathway and a decreased expression of eNOS. These in vitro alterations coincided with the hindering of antral motor activity observed in vivo. Apocynin treatment, counteracting oxidative stress, reverted alterations observed in obese antral muscle.

CONCLUSION

Antral myogenic activity of obese subjects can be impaired by alterations of signaling pathways induced by oxidative stress.

Impact of insulin on the intestinal microcirculation in a model of sepsis-related hyperglycemia

BACKGROUND

Sepsis involves dysfunctional glucose metabolism. Among patients with sepsis, hyperglycemia is frequent and insulin administration has been evaluated for glycemic control to improve patient outcomes. Only few studies have examined the hyperglycemic microcirculation and the impact of insulin on the microvasculature in sepsis.

OBJECTIVE

To study the functional capillary density (FCD) and leukocyte activation within the intestinal microcirculation in endotoxin-induced experimental sepsis.

METHODS

In 50 male Lewis rats, endotoxemia was induced with lipopolysaccharide (LPS; 5 mg/kg). Low dose (LD) glucose was administered to avoid insulin-induced hypoglycemia. High dose (HD) glucose was administered to model sepsis-related hyperglycemia. Animals in LD and HD glucose groups received an insulin bolus (1.4 IU/kg). Two hours after LPS administration, intravital microscopy (IVM) of the terminal ileum was performed, and FCD and leukocyte adherence were measured in a blinded fashion. Blood glucose levels were measured every 30 min following the onset of endotoxemia. Plasma samples were collected 3 h after the onset of endotoxemia to measure IFN-γ, TNF-α, IL-1α, IL-4, GM-CSF and MCP-1 levels using multiplex bead immunoassay.

RESULTS

Endotoxemia significantly reduced FCD and increased leukocyte adherence within the intestinal microvasculature. LD and HD glucose administration combined with insulin improved the FCD and decreased the adherence of leukocytes in endotoxemic animals as did HD glucose administration alone. Consistent with these results, IL-4, IL-1α, GM-CSF and IFN-γ levels were decreased following combined HD glucose and insulin administration in endotoxemic animals.

CONCLUSIONS

Insulin administration, as well as an endogenous insulin response triggered by HD glucose administration, improved the FCD and decreased leukocyte activation in endotoxemic rats. The results of this study give insight into the immune and vaso-modulatory role of insulin administration during experimental endotoxemia, and may be extrapolated for clinical sepsis and other critical illnesses with marked microcirculatory dysfunction.

High-intensity interval training or continuous training, combined or not with fasting, in obese or overweight women with cardiometabolic risk factors: study protocol for a randomised clinical trial

INTRODUCTION

Physical inactivity and increased caloric intake play important roles in the pathophysiology of obesity. Increasing physical activity and modifying eating behaviours are first-line interventions, frequently hampered by lack of time to exercise and difficulties in coping with different diets. High-intensity interval training (HIIT) may be a time-efficient method compared with moderate-intensity continuous training (CT). Conversely, diets with a fasting component may be more effective than other complex and restrictive diets, as it essentially limits caloric intake to a specified period without major diet composition changes. Therefore, the combination of HIIT and fasting may provide incremental benefits in terms of effectiveness and time efficiency in obese and sedentary populations. The aim of this study is to determine the effect of HIIT versus CT, combined or not with fasting, on microcirculatory function, cardiometabolic parameters, anthropometric indices, cardiorespiratory fitness and quality of life in a population of sedentary overweight or obese women with cardiometabolic risk factors.

METHODS AND ANALYSIS

Sedentary women aged 30-50 years, with a body mass index ≥25 kg/m2 and cardiometabolic risk factors, will be randomised to HIIT performed in the fasting state, HIIT performed in the fed state, CT in the fasting state or CT in the fed state. Cardiometabolic parameters, anthropometric indices, cardiorespiratory fitness, quality of life and microvascular function (cutaneous capillary density and microvascular reactivity evaluated by laser speckle contrast imaging) will be evaluated before initiation of the interventions and 16 weeks thereafter.

ETHICS AND DISSEMINATION

The trial complies with the Declaration of Helsinki and has been approved by the local ethics committee (Instituto Nacional de Cardiologia, Rio de Janeiro, Brazil). All patients provide written informed consent before enrolment and randomisation. The study's results will be disseminated to the healthcare community by publications and presentations at scientific meetings.

TRIAL REGISTRATION NUMBER

NCT03236285.

Laser Doppler: A Tool for Measuring Pancreatic Islet Microvascular Vasomotion In Vivo

As a functional status of microcirculation, microvascular vasomotion is important for the delivery of oxygen and nutrients and the removal of carbon dioxide and waste products. The impairment of microvascular vasomotion might be a crucial step in the development of microcirculation-related diseases. In addition, the highly vascularized pancreatic islet is adapted to support endocrine function. In this respect, it seems possible to infer that the functional status of pancreatic islet microvascular vasomotion might affect pancreatic islet function. Analyzing the pathological changes of the functional status of pancreatic islet microvascular vasomotion may be a feasible strategy to determine contributions that pancreatic islet microcirculation makes to related diseases, such as diabetes mellitus, pancreatitis, etc. Therefore, this protocol describes using a laser Doppler blood flow monitor to determine the functional status of pancreatic islet microvascular vasomotion, and to establish parameters (including average blood perfusion, amplitude, frequency, and relative velocity of pancreatic islet microvascular vasomotion) for evaluation of the microcirculatory functional status. In a streptozotocin-induced diabetic mouse model, we observed an impaired functional status of pancreatic islet microvascular vasomotion. In conclusion, this approach for assessing pancreatic islet microvascular vasomotion in vivo may reveal mechanisms relating to pancreatic islet diseases.

Evaluation of microvascular endothelial function and capillary density in patients with infective endocarditis using laser speckle contrast imaging and video-capillaroscopy

OBJECTIVE

To evaluate the systemic microcirculation of patients with infective endocarditis (IE).

METHODS

This is a comparative study of patients with definite IE by the modified Duke criteria admitted to our center for treatment. A reference group of sex- and age-matched healthy volunteers was included. Microvascular flow was evaluated in the forearm using a laser speckle contrast imaging system, for noninvasive measurement of cutaneous microvascular perfusion, in combination with skin iontophoresis of acetylcholine (ACh) and sodium nitroprusside (SNP) to test microvascular reactivity. Microvascular density was evaluated using skin video-capillaroscopy.

RESULTS

We studied 22 patients with IE; 15 were male and seven female. The mean age and standard deviation (SD) were 45.5 ± 17.3 years. Basal skin microvascular conductance was significantly increased in patients with IE, compared with healthy individuals (0.36 ± 0.13 versus 0.21 ± 0.08 APU/mmHg; P < 0.0001). The increase in microvascular conductance induced by ACh in patients was 0.21 ± 0.17 and in the reference group, it was 0.37 ± 0.14 APU/mmHg (P = 0.0012). The increase in microvascular conductance induced by SNP in patients was 0.18 ± 0.14 and it was 0.29 ± 0.15 APU/mmHg (P = 0.0140) in the reference group. The basal mean skin capillary density of patients (135 ± 24 capillaries/mm²) was significantly higher, compared with controls (97 ± 21 capillaries/mm²; P < 0.0001).

CONCLUSIONS

The main findings in the microcirculation of patients with IE were greater basal vasodilation and a reduction of the endothelium-dependent and -independent microvascular reactivity, as well as greater functional skin capillary density compared to healthy individuals.

Association of body mass index and weight gain patterns with albumin excretion in pregnancy

AIM

We examined body mass index (BMI) and gestational weight gain (GWG) patterns of pregnant women and investigated the impact of these factors on the urinary albumin-creatinine ratio (ACR) during pregnancy.

METHODS

The data of 163 women whose basal BMI and ACR were measured during the first trimester were used in this study. Body weight alone between 12-16 weeks and body weight together with ACR after 37 weeks of gestation were measured.

RESULTS

Overall, 46% of women were overweight or obese, 60.7% had excessive weight gain and 16.6% had inadequate weight gain. Only 22.7% of women gained weight within the recommended range. There was no difference in weight gain patterns with respect to BMI. ACR during the third trimester was significantly higher than during the first trimester (7.08 [0.00-1180.90] mg/g vs 4.73 [0.00-275.00] mg/g, respectively; P = 0.001). The ACR of obese women was higher than in normal weight subjects during the third trimester (16.79 mg/g [0.01-1180.90] vs 8.07 mg/g [0.10-402.14] respectively; adjusted P = 0.015). Both ACR change and third trimester ACR were weakly but significantly correlated with basal BMI (r: 0.228 P: 0.003 and r: 0.301 P < 0.001, respectively) but not with GWG or GWG rate. Basal BMI was not associated with first-trimester ACR.

CONCLUSION

Obesity is associated with an increase in urinary albumin excretion during the course of pregnancy. Distinction of this relationship during pregnancy offers an opportunity for further research on pathophysiological mechanisms. The alarmingly high rate of non-compliance with IOM guidelines in pregnant women is a concern. Prompt measures for counseling of women before and during pregnancy in order to maintain healthy weight are needed.

Functional status of microvascular vasomotion is impaired in spontaneously hypertensive rat

Accumulating evidence demonstrates that microcirculation plays a role in the pathogenesis of hypertension. In the current study, we demonstrated that pancreatic islet microvascular vasomotion of spontaneously hypertensive rats (SHRs) lost the ability to regulate blood flow perfusion and exhibited a lower microvascular blood perfusion pattern which was negative correlated with blood glucose level. SHRs administrated with insulin revealed an improvement of pancreatic islet microvascular vasomotion and blood perfusion pattern. In vitro, the expressions of endothelial nitric oxide synthase (eNOS) and phospho-eNOS^ser1177 (p-eNOS^ser1177) were significantly decreased in high glucose exposed islet endothelial cells (iECs), accompanied with a higher ratio of eNOS monomer to eNOS dimer and a significantly increased malondialdehyde and nitrite levels. Meanwhile, barrier function, tube formation and migration capacities of high glucose exposed iECs were significantly inhibited. In contrast, iECs dysfunction induced by glucose toxicity and oxidative stress was attenuated or improved by supplement with insulin, L-arginine and β-mercaptoethanol. In summary, our findings suggest that functional status of pancreatic islet microvascular vasomotion is impaired in SHRs and provide evidence that treatment with insulin, L-arginine and β-mercaptoethanol improves endothelium-dependent microvascular vasomotion and meliorates iECs function due to anti-hyperglycemic and anti-oxidative effects, partly through mechanism involving regulation of eNOS and p-eNOS^ser1177.

Multiorgan, Multimodality Imaging in Cardiometabolic Disease

Cardiometabolic disease, spanning conditions such as obesity to type 2 diabetes mellitus with excess cardiovascular risk, represents a major public health burden. Advances in preclinical translational science point to potential targets across multiple organ systems for early intervention to improve cardiometabolic health. Validation in clinical trials and translation to care would benefit from in vivo diagnostic techniques that facilitate therapeutic advancements. This review provides a state-of-the-art, multimodality perspective spanning the multiple organ systems that contribute to cardiometabolic disease.

Evaluation of microvascular endothelial function in patients with infective endocarditis using laser speckle contrast imaging and skin video-capillaroscopy: research proposal of a case control prospective study

OBJECTIVE

Infective endocarditis is a severe condition with high in-hospital and 5-year mortality. There is increasing incidence of infective endocarditis, which may be related to healthcare and changes in prophylaxis recommendations regarding oral procedures. Few studies have evaluated the microcirculation in patients with infective endocarditis, and so far, none have utilized laser-based technology or evaluated functional capillary density. The aim of the study is to evaluate the changes in the systemic microvascular bed of patients with both acute and subacute endocarditis. This is a cohort study that will include adult patients with confirmed active infective endocarditis according to the modified Duke criteria who were admitted to our center for treatment. A control group of sex- and age-matched healthy volunteers will be included. Functional capillary density, which is defined as the number of spontaneously perfused capillaries per square millimeter of skin, will be assessed by video-microscopy with an epi-illuminated fiber optic microscope. Capillary recruitment will be evaluated using post-occlusive reactive hyperemia. Microvascular flow will be evaluated in the forearm using a laser speckle contrast imaging system for the noninvasive and continuous measurement of cutaneous microvascular perfusion changes. Laser speckle contrast imaging will be used in combination with skin iontophoresis of acetylcholine, an endothelium-dependent vasodilator, or sodium nitroprusside (endothelium independent) to test microvascular reactivity.

RESULTS

The present study will contribute to the investigation of microcirculatory changes in infective endocarditis and possibly lead to an earlier diagnosis of the condition and/or determination of its severity and complications. Trial registration ClinicalTrials.gov ID: NCT02940340.