Association Between Arterial Stiffness and Skin Microvascular Function: The SUVIMAX2 Study and The Maastricht Study

Skin Microvascular Dysfunction in Type 2 Diabetes Mellitus Using Laser Speckle Contrast Analysis and Association with Carotid Intima-Media Thickness

Background: It is established that diabetes mellitus (DM) is characterized by increased cardiovascular risk associated with subclinical atherosclerosis as well as microvascular alterations. Laser speckle contrast analysis (LASCA) is an innovative, non-invasive method for assessing skin microvascular function. Objectives: We sought to assess skin microvascular function in patients with type 2 DM and matched controls. Methods: Consecutive patients with DM and individuals matched for age, sex and BMI were included in the study. Skin microvascular perfusion was assessed, using LASCA, during baseline, a 5 min occlusion period and a 5 min reperfusion period. Carotid intima-media thickness (cIMT) was measured as a surrogate marker of macrocirculation. Results: In total, 18 patients with DM and 22 in the control group were enrolled. No statistically significant differences were observed in baseline flux, peak flux and percentage decrease during arterial occlusion. During reperfusion, individuals with DM exhibited a smaller peak magnitude compared to controls (147.0 ± 64.7% vs. 189.4 ± 46.0%, respectively; p < 0.05). Moreover, cIMT was higher in patients with DM compared to controls (0.68 ± 0.09 mm vs. 0.60 ± 0.08 mm, respectively, p < 0.01) and was negatively correlated with skin microvascular reactivity in the univariate analysis. In the multivariate analysis, glucose and office systolic blood pressure levels remained significant predictors of microvascular reactivity. Conclusions: Our study shows that patients with type 2 DM exhibit impaired skin microvascular function compared to controls. Furthermore, glucose levels and blood pressure play a key role in microvascular dysfunction. However, additional studies are needed to address the clinical significance of early microvascular changes in DM.

An observational study of microcirculation among healthy individuals by age and sex

OBJECTIVE

This study measured normal ranges of microcirculatory parameters in healthy individuals and investigated differences in parameters by age and sex.

METHODS

Participants were enrolled into three groups with equal numbers of male and female: young (20-39 years), middle-aged (40-59 years), and elderly (60-79 years). Sublingual microcirculation images were obtained using the incident dark field (IDF).

RESULTS

A total of 75 female and 75 male healthy individuals were enrolled. The elderly group had a higher TVD (26.5 [2] vs. 25.2 [1.8]; p = 0.019) and a lower PPV (97 [2] vs. 98 [3]; p = 0.03) than did the young group. In the elderly group, systolic blood pressure (SBP) and mean arterial pressure (MAP) were moderately and positively correlated with MFI score (r = 0.407, p < 0.05, and r = 0.403, p < 0.05, respectively). The female participants had a lower MFI score than did the male participants (2.9 [2.8-3] vs. 3.0 [2.9-3]; p = 0.015).

CONCLUSIONS

This study revealed the range of microcirculatory parameters between different ages and sexes in healthy individuals. We found that blood pressure levels were correlated with microcirculatory parameters, especially in elders and female.

The Role of Systemic Microvascular Dysfunction in Heart Failure with Preserved Ejection Fraction

Heart failure with preserved ejection fraction (HFpEF) is a condition with increasing incidence, leading to a health care problem of epidemic proportions for which no curative treatments exist. Consequently, an urge exists to better understand the pathophysiology of HFpEF. Accumulating evidence suggests a key pathophysiological role for coronary microvascular dysfunction (MVD), with an underlying mechanism of low-grade pro-inflammatory state caused by systemic comorbidities. The systemic entity of comorbidities and inflammation in HFpEF imply that patients develop HFpEF due to systemic mechanisms causing coronary MVD, or systemic MVD. The absence or presence of peripheral MVD in HFpEF would reflect HFpEF being predominantly a cardiac or a systemic disease. Here, we will review the current state of the art of cardiac and systemic microvascular dysfunction in HFpEF (Graphical Abstract), resulting in future perspectives on new diagnostic modalities and therapeutic strategies.

Vascular risk factors for optical coherence tomography-detected macular cysts: The Maastricht Study

PURPOSE

To investigate whether higher blood pressure and greater arterial stiffness are associated with the presence of macular cysts and whether this association is already present in the absence of micro-aneurysms in individuals with and without type 2 diabetes.

METHODS

Using spectral domain optical coherence tomography (OCT), we performed a macular volume scan in 2647 individuals (mean age 60 ± 8 years, 50% men, 27% type 2 diabetes). The association between macular cysts and 24-hour systolic and diastolic blood pressure, pulse pressure, mean arterial blood pressure, carotid-femoral pulse wave velocity and carotid distensibility was assessed by use of logistic regression.

RESULTS

Twenty-four hours systolic blood pressure was associated with the presence of macular cysts [OR = 1.03 (95% CI 1.00-1.05) per 1 mmHg, p = 0.03]. 24 hr pulse pressure [OR = 1.61 (95% CI 1.11-2.34) per 10 mmHg, p = 0.01] and carotid-femoral pulse wave velocity [OR = 1.16 (95% CI 1.02-1.32) per 1 m/s, p = 0.02] were associated with macular cysts, while carotid distensibility was not [OR = 1.03 (95% CI 0.96-1.11) per 1.0*10^-3 /kPa, p = 0.45]. Associations were similar in individuals with and without type 2 diabetes and were already present in the absence of micro-aneurysms.

CONCLUSION

Twenty-four hours systolic blood pressure, 24 hr pulse pressure and carotid-femoral pulse wave velocity are associated with the presence of OCT-detected macular cysts in individuals with and without type 2 diabetes, even in the absence of micro-aneurysms. Therefore, blood pressure and aortic stiffness are potential factors contributing to macular cysts.

Greater daily glucose variability and lower time in range assessed with continuous glucose monitoring are associated with greater aortic stiffness: The Maastricht Study

AIMS

CVD is the main cause of morbidity and mortality in individuals with diabetes. It is currently unclear whether daily glucose variability contributes to CVD. Therefore, we investigated whether glucose variability is associated with arterial measures that are considered important in CVD pathogenesis.

METHODS

We included participants of The Maastricht Study, an observational population-based cohort, who underwent at least 48 h of continuous glucose monitoring (CGM) (n = 853; age: 59.9 ± 8.6 years; 49% women, 23% type 2 diabetes). We studied the cross-sectional associations of two glucose variability indices (CGM-assessed SD [SD_CGM] and CGM-assessed CV [CV_CGM]) and time in range (TIR_CGM) with carotid-femoral pulse wave velocity (cf-PWV), carotid distensibility coefficient, carotid intima-media thickness, ankle-brachial index and circumferential wall stress via multiple linear regression.

RESULTS

Higher SD_CGM was associated with higher cf-PWV after adjusting for demographics, cardiovascular risk factors and lifestyle factors (regression coefficient [B] per 1 mmol/l SD_CGM [and corresponding 95% CI]: 0.413 m/s [0.147, 0.679], p = 0.002). In the model additionally adjusted for CGM-assessed mean sensor glucose (MSG_CGM), SD_CGM and MSG_CGM contributed similarly to cf-PWV (respective standardised regression coefficients [st.βs] and 95% CIs of 0.065 [-0.018, 0.167], p = 0.160; and 0.059 [-0.043, 0.164], p = 0.272). In the fully adjusted models, both higher CV_CGM (B [95% CI] per 10% CV_CGM: 0.303 m/s [0.046, 0.559], p = 0.021) and lower TIR_CGM (B [95% CI] per 10% TIR_CGM: -0.145 m/s [-0.252, -0.038] p = 0.008) were statistically significantly associated with higher cf-PWV. Such consistent associations were not observed for the other arterial measures.

CONCLUSIONS

Our findings show that greater daily glucose variability and lower TIR_CGM are associated with greater aortic stiffness (cf-PWV) but not with other arterial measures. If corroborated in prospective studies, these results support the development of therapeutic agents that target both daily glucose variability and TIR_CGM to prevent CVD.

Peripheral microcirculatory abnormalities are associated with cardiovascular risk in systemic sclerosis: a nailfold video capillaroscopy study

INTRODUCTION

Microvascular dysfunction is the key element in the pathogenesis of systemic sclerosis (SSc), whereas the contribution of large and medium size vessel abnormalities is yet to be established. The aim of the present study is to assess the association between micro- and macrovascular function by utilizing a broad spectrum of assessments of vascular performance.

METHODS

We included consecutive, consenting SSc patients who underwent nailfold video capillaroscopy (NVC) for microcirculation evaluation. Peripheral and central systolic and diastolic blood pressure, carotid intima-media thickness (cIMT), aortic augmentation index (AIx) corrected for a heart rate of 75 beats per minute (AIx-75), and carotid-femoral pulse wave velocity (PWV) were also performed to assess macrovascular function. Cardiovascular risk disease (CVD) algorithms were also calculated and included in the analysis.

RESULTS

A total of 81 patients (6 males) were studied with mean age 55.44 ± 13.40 years. Reduced capillary density was inversely correlated with arterial stiffness (Alx-75) and augmentation pressure (r =  - 0.262, p = 0.018, and r =  - 0.249, p = 0.025 respectively). Alx was significantly lower in the early compared to late pattern (28.24 ± 11.75 vs 35.63 ± 10.47, p = 0.036). A significant trend was found among NVC patterns with Alx-75 values being higher with the progression of microangiopathy towards the "late" group (26.36 ± 10.90 vs 30.81 ± 11.59 vs 35.21 ± 7.90, p = 0.027 for trend). Similarly, Framingham risk score and Atherosclerotic Cardiovascular Disease score were progressively higher across the worsening NVC patterns (4.10 ± 4.13 vs 2.99 ± 2.72 vs 6.36 ± 5.65, p = 0.023, and 6.99 ± 7.18 vs 5.63 ± 4.41 vs 12.09 ± 9.90, p = 0.019, respectively, for trends). Finally, QRISK3 (10-year cardiovascular disease risk) and ASCVD (Atherosclerotic Cardiovascular Disease) scores were inversely correlated with the number of capillaries (r =  - 0.231, p = 0.048, and r =  - 0.260, p = 0.038 respectively).

CONCLUSION

These data suggest that CVD risk scores and macrovascular parameters are strongly correlated with microvasculopathy in patients with SSc. Key Points • Microangiopathy is the hallmark of SSc, but the relationship between subclinical atherosclerosis and small vessel disease remains unknown. • Arterial stiffening and CVD risk scores are positively associated with the degree of progression of peripheral microvasculopathy assessed with NVC. • The results of the study suggest an association between NVC abnormalities and higher CVD risk in SSc patients.

Blood pressure variability and microvascular dysfunction: the Maastricht Study

BACKGROUND

Microvascular dysfunction (MVD) contributes to stroke, dementia, depression, retinopathy and chronic kidney disease. However, the determinants of MVD are incompletely understood. Greater blood pressure variability (BPV) may be one such determinant.

METHODS AND RESULTS

We used cross-sectional data of The Maastricht Study (n = 2773, age 59.9 years; 51.9% men) to investigate whether greater very short- to mid-term BPV is associated with various MVD measures. We standardized and averaged within-visit, 24-h and 7-day BPV into a systolic and a diastolic BPV composite score. MVD measures included a composite score of MRI cerebral small vessel disease (CSVD) features (total brain parenchymal volume, white matter hyperintensity volume, lacunar infarcts and cerebral microbleeds), a composite score of flicker light-induced retinal arteriolar and venular dilation response, albuminuria, heat-induced skin hyperemia and a composite score of plasma biomarkers of MVD (sICAM-1, sVCAM-1, sE-selectin and von Willebrand Factor). We used linear regression adjusted for age, sex, glucose metabolism status, mean 24-h systolic or DBP, cardiovascular risk factors and antihypertensive medication. We found that higher systolic and diastolic BPV composite scores (per SD) were associated with higher albuminuria [higher ratio, 1.04 (95% CI 1.00-1.08) and 1.07 (1.03-1.11), respectively], but not with other measures of MVD tested.

CONCLUSION

Greater systolic and diastolic BPV was associated with higher albuminuria, but not with CSVD features, flicker light-induced retinal arteriolar and venular dilation response, heat-induced skin hyperemia and plasma biomarkers of MVD. This suggests that the microvasculature of the kidneys is most vulnerable to the detrimental effects of greater BPV.

Intermittent compression induces transitory hypoxic stimuli, upstream vasodilation and enhanced perfusion of skin capillaries, independent of age and diabetes

The benefit of enhanced shear stress to the vascular endothelium has been well-documented in conduit arteries but is less understood in skin microcirculation. The aim of this study was to provide physiological evidence of the vascular changes in skin microcirculation induced by intermittent pneumatic compression (IPC) of 1 s cuff inflation (130 mmHg) every 20 s to the palm of the hand for 30 min. The oxygenation and hemodynamics of dorsal mid-phalangeal finger skin microcirculation were assessed by laser Doppler fluximetry and reflectance spectroscopy before, during, and after IPC in 15 young (18-39 years old) and 39 older (40-80 years old) controls and 32 older subjects with type 2 diabetes mellitus. Each individual cuff inflation induced: 1) brief surge in flux immediately after cuff deflation followed by 2) transitory reduction in blood oxygen for ∼4 s, and 3) a second increase in perfusion and oxygenation of the microcirculation peaking ∼11 s after cuff deflation in all subject groups. With no significant change in blood volume observed by reflectance spectroscopy, despite the increased shear stress at the observed site, this second peak in flux and blood oxygen suggests a delayed vasoactive response upstream inducing increased arterial influx in the microcirculation that was higher in older controls and subjects with diabetes compared to young controls (P < 0.001, P < 0.001, respectively) and achieving maximum capillary recruitment in all subject groups. Transitory hypoxic stimuli with conducted vasodilation may be a mechanism through which IPC enhances capillary perfusion in skin microcirculation independent of age and type 2 diabetes mellitus.NEW & NOTEWORTHY This study demonstrates that hand intermittent pneumatic compression evokes transitory hypoxic stimuli in distal finger skin microcirculation inducing vasodilation of arterial inflow vessels, enhanced perfusion, and maximum capillary recruitment in young and older subjects and older subjects with type 2 diabetes mellitus. Enhanced shear stress in the microcirculation did not appear to induce local skin vasodilation.

The presence of diabetes mellitus further impairs structural and functional capillary density in patients with chronic kidney disease

OBJECTIVE

Endothelial dysfunction has been associated with increased cardiovascular events and overall mortality. Microvascular damage is prevalent both in diabetes mellitus (DM) and chronic kidney disease (CKD). Our aim was to compare microcirculatory function parameters in diabetic and non-diabetic CKD patients via nailfold video-capillaroscopy.

METHODS

We included 48 diabetic and 48 non-diabetic adult CKD patients. All participants underwent nailfold video-capillaroscopy, during which capillary density was measured at normal conditions (baseline), after a 4-minute arterial occlusion (postocclusive reactive hyperemia), and at the end of a 2-minute venous occlusion (congestion phase).

RESULTS

Diabetic patients presented significantly lower capillary density during reactive hyperemia (36.3 ± 3.8 vs 38.3 ± 4.3 capillaries/mm² , P = .022) and at venous congestion (37.8 ± 4.0 vs 39.8 ± 4.2 capillaries/mm² , P = .015). When stratified according to CKD stages, only in stage 3b capillary density was significantly lower in diabetic compared to non-diabetic subjects at baseline, during postocclusive hyperemia (36.8 ± 2.7 vs 40.0 ± 4.3 capillaries/mm² , P = .037) and venous congestion (38.3 ± 2.8 vs 41.5 ± 3.5 capillaries/mm² , P = .022).

CONCLUSIONS

Capillary density during postocclusive hyperemia and after venous congestion is lower in diabetic compared to non-diabetic CKD patients, a finding indicative that diabetes is an additional factor contributing to microcirculatory structural and functional impairment in CKD. These differences are more prominent in CKD stage 3b.

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.

Cerebral microvascular complications of type 2 diabetes: stroke, cognitive dysfunction, and depression

Adults with type 2 diabetes are at an increased risk of developing certain brain or mental disorders, including stroke, dementia, and depression. Although these disorders are not usually considered classic microvascular complications of diabetes, evidence is growing that microvascular dysfunction is one of the key underlying mechanisms. Microvascular dysfunction is a widespread phenomenon in people with diabetes, including effects on the brain. Cerebral microvascular dysfunction is also apparent in adults with prediabetes, suggesting that cerebral microvascular disease processes start before the onset of diabetes. The microvasculature is involved in the regulation of many cerebral processes that when impaired predispose to lacunar and haemorrhagic stroke, cognitive dysfunction, and depression. Main drivers of diabetes-related cerebral microvascular dysfunction are hyperglycaemia, obesity and insulin resistance, and hypertension. Increasing amounts of data from observational studies suggest that diabetes-related microvascular dysfunction is associated with a higher risk of stroke, cognitive dysfunction, and depression. Cerebral outcomes in diabetes might be improved following treatments targeting the pathways through which diabetes damages the microcirculation. These treatments might include drugs that reduce dicarbonyl compounds, augment cerebral insulin signalling, or improve blood-brain barrier permeability and cerebral vasoreactivity.

The oral glucose tolerance test-derived incremental glucose peak is associated with greater arterial stiffness and maladaptive arterial remodeling: The Maastricht Study

Background

Daily glucose variability may contribute to vascular complication development irrespective of mean glucose values. The incremental glucose peak (IGP) during an oral glucose tolerance test (OGTT) can be used as a proxy of glucose variability. We investigated the association of IGP with arterial stiffness, arterial remodeling, and microvascular function, independent of HbA_1c and other confounders.

Methods

IGP was calculated as the peak minus baseline plasma glucose value during a seven-point OGTT in 2758 participants (age: 60 ± 8 years; 48% women) of The Maastricht Study, an observational population-based cohort. We assessed the cross-sectional associations between IGP and arterial stiffness (carotid-femoral pulse wave velocity [cf-PWV], carotid distensibility coefficient [carDC]), arterial remodeling (carotid intima-media thickness [cIMT]; mean [CWS_mean] and pulsatile [CWS_puls] circumferential wall stress), and microvascular function (retinal arteriolar average dilatation; heat-induced skin hyperemia) via multiple linear regression with adjustment for age, sex, HbA_1c, cardiovascular risk factors, lifestyle factors, and medication use.

Results

Higher IGP was independently associated with higher cf-PWV (regression coefficient [B]: 0.054 m/s [0.020; 0.089]) and with higher CWS_mean (B: 0.227 kPa [0.008; 0.446]). IGP was not independently associated with carDC (B: − 0.026 10⁻³/kPa [− 0.112; 0.060]), cIMT (B: − 2.745 µm [− 5.736; 0.245]), CWS_puls (B: 0.108 kPa [− 0.054; 0.270]), retinal arteriolar average dilatation (B: − 0.022% [− 0.087; 0.043]), or heat-induced skin hyperemia (B: − 1.380% [− 22.273; 19.513]).

Conclusions

IGP was independently associated with aortic stiffness and maladaptive carotid remodeling, but not with carotid stiffness, cIMT, and microvascular function measures. Future studies should investigate whether glucose variability is associated with cardiovascular disease.

Endothelial Function, Adipokine Serum Levels, and White Matter Hyperintesities in Subjects With Diabetic Foot Syndrome

CONTEXT

No study has analyzed the prevalence of white matter hyperintensities (WMHs) in subjects with diabetic foot syndrome (DFS) and their relationship to adipokine serum levels and indexes of endothelial and cognitive performance.

OBJECTIVE

To evaluate omentin and vaspin serum levels and the prevalence of WMHs in subjects with DFS and to analyze their relationship with other endothelial, arterial stiffness, and cognitive functions.

DESIGN

Case-control study enrolling 40 subjects with DFS, 40 diabetic subjects without foot complications, 40 controls with foot lesions without diabetes, and 40 patients without diabetes mellitus.

MAIN OUTCOME MEASURES

Pulse wave velocity (PWV), augmentation index, reactive hyperemia index (RHI), serum vaspin and omentin levels, Fazekas score, and Mini-Mental State Examination (MMSE).

RESULTS

Subjects with DFS showed higher mean PWV values when compared with diabetic controls and lower RHI values when compared with controls. They also showed a lower mean MMSE score, significantly lower omentin serum levels, and a higher prevalence of grade 2 severity of periventricular hyperintensities (PVHs). We observed a significant positive correlation between PWV and PVH and between Fazekas score and PWV among diabetic subjects, whereas among subjects with diabetic foot we observed a significant negative correlation between PVH and RHI.

CONCLUSIONS

Diabetes seems to be more associated with endothelial function disturbance in comparison with patients with diabetic foot that exhibit a more strict association with microvascular brain damage as indicated by our significant finding of an association with PVHs.

Matrix stiffness regulates arteriovenous differentiation of endothelial progenitor cells during vasculogenesis in nude mice

Objectives

The aim of the study was to investigate the effect of matrix stiffness on arteriovenous differentiation of endothelial progenitor cells (EPCs) during vasculogenesis in nude mice.

Materials and methods

Dextran hydrogels of differing stiffnesses were first prepared by controlling the crosslinking reaction to generate different thioether bonds. Hydrogels with stiffnesses matching those of the arterial extracellular matrix and venous extracellular matrix were separately combined with mouse bone marrow‐derived EPCs and subcutaneously implanted on either side of the backs of nude mice. After 14 days, artery‐specific marker Efnb2 and vein‐specific marker Ephb4 in the neovasculature were detected to determine the effect of matrix stiffness on the arteriovenous differentiation of EPCs in vivo.

Results

Fourteen days after the implantation of the EPC‐loaded dextran hydrogels, new blood vessels were observed in both types of hydrogels. We further verified that matrix stiffness regulated the arteriovenous differentiation of EPCs during vasculogenesis via the Ras/Mek pathway.

Conclusions

Matrix stiffness regulates the arteriovenous differentiation of EPCs during vasculogenesis in nude mice through the Ras/Mek pathway.

Microvascular Dysfunction and Hyperglycemia: A Vicious Cycle With Widespread Consequences

Microvascular and metabolic physiology are tightly linked. This Perspective reviews evidence that 1) the relationship between hyperglycemia and microvascular dysfunction (MVD) is bidirectional and constitutes a vicious cycle; 2) MVD in diabetes affects many, if not all, organs, which may play a role in diabetes-associated comorbidities such as depression and cognitive impairment; and 3) MVD precedes, and contributes to, hyperglycemia in type 2 diabetes (T2D) through impairment of insulin-mediated glucose disposal and, possibly, insulin secretion. Obesity and adverse early-life exposures are important drivers of MVD. MVD can be improved through weight loss (in obesity) and through exercise. Pharmacological interventions to improve MVD are an active area of investigation.

Dermal capillary rarefaction as a marker of microvascular damage in patients with rheumatoid arthritis: Association with inflammation and disorders of the macrocirculation

OBJECTIVE

Capillary rarefaction is observed in various cardiovascular diseases, yet it remains understudied in RA, a chronic inflammatory disease accompanied by excess cardiovascular risk. We quantified capillary density in RA patients and explored potential associations with macrocirculatory disorders, inflammation, and cardiovascular risk.

METHODS

Dermal capillary density was assessed with nailfold capillaroscopy in RA and non-RA individuals, using specifically designed semiautomated software. Macrocirculation assessments included large artery stiffening, evaluated with PWV, and myocardial blood flow, calculated as cardiac index from impedance cardiography. Cardiovascular risk score was estimated from the Framingham Heart Study.

RESULTS

The number of capillaries per visual field was lower in patients (n = 99) compared to controls (n = 35) (132.6 ± 30.3 vs 152.9 ± 25.2, P = .001). In the RA group, capillary density negatively correlated with CRP and PWV, and positively with HDL and cardiac index. In the multivariate analysis, CRP independently predicted capillary rarefaction (P = .044). Capillary density significantly correlated with cardiovascular risk, even after adjustment for inflammation (P = .030).

CONCLUSION

Capillary rarefaction appears pronounced in RA and correlates with lower cardiac output, increased arterial stiffness, and cardiovascular risk. However, the associations with macrocirculatory disorders may be obscured by inflammation, which appears as the major contributor to capillary rarefaction in RA.

Inflammatory and Angiogenic Factors Linked to Longitudinal Microvascular Changes in Hemodialysis Patients Irrespective of Treatment Dose Intensity

BACKGROUND

Cardiovascular disease is a major contributor to the poor outcomes observed in hemodialysis. We investigated the relationship between hemodialysis intensity and vascular parameters in high-dose (HDHD; >12hrs/week) and Conventional (CHD; ≤12hrs/week) hemodialysis intensity over a 6-month period.

METHODS

We present the 6-month longitudinal analysis of a 2-year multicenter study investigating the effects of HDHD on cardiovascular parameters. We used pulse wave velocity, 24hr ambulatory blood pressure and sublingual dark field capillaroscopy measurements to assess macro- and microcirculation on 6-monthly basis. Pro-inflammatory and endothelial biomarkers were also measured at 6-monthly intervals.

RESULTS

47 participants (21 HDHD, 26 CHD) were studied. CHD were older (63.5±14.2 vs 53.7±12.6 yr; p=0.018), with shorter dialysis vintage (median 23 vs 61 months; p=0.001). There was considerable variability in the degree and direction of change of circulatory measurements over a 6-month period. Hemodialysis intensity (hrs/week) did not correlate to these changes, when adjusted for age, dialysis vintage and comorbidity. Higher levels of Interleukin (IL)-8 measured at baseline independently predicted an increase in the Perfused Boundary Region (5-25μm) of the endothelial glycocalyx (p=0.010) whilst higher levels of soluble Flt-1 had a significant inverse effect (p=0.002) in an adjusted linear model.

CONCLUSION

Hemodialysis intensity did not predict changes in either macro- or microvascular parameters. Inflammation mediated through the IL-8 pathway predicted microvascular injury while Flt-1, a potential marker of angiogenesis and endothelial repair, might have a significant protective role. Further understanding of these pathways will be necessary to improve dialysis outcomes.

Prospects of Laser Doppler flowmetry application in assessment of skin microcirculation in diabetes

This review includes results of scientific and clinical use of laser Doppler flowmetry (LDF) in patients with diabetes mellitus. LDF is a non-invasive method for the quantitative evaluation of microcirculation, which can assess microcirculatory rhythms and conduct functional tests with various impacts, allowing the exploration of regulatory mechanisms of microcirculation. LDF reveals specific diabetes changes in the regulatory function of microcirculation. Microcirculation disturbances, which are traditionally associated with the pathogenesis of complications, also occur in patients with early disorders of carbohydrate metabolism and may precede the manifestation of diabetes. However, this method is still not applied in clinical practice. In this review, we analysed factors limiting the implementation of LDF in practical medicine and suggest ways to improve its clinical significance.

Extracellular overhydration linked with endothelial dysfunction in the context of inflammation in haemodialysis dependent chronic kidney disease

BACKGROUND

Haemodialysis (HD) patients are predisposed to dysregulated fluid balance leading to extracellular water (ECW) expansion. Fluid overload has been closely linked with outcome in these patients. This has mainly been attributed to cardiac volume overload, but the relation between abnormalities in fluid status with micro- and macrovascular dysfunction has not been studied in detail. We studied the interaction of macro- and microvascular factors in states of normal and over- hydration in HD-dependent CKD.

METHODS

Fluid compartments [total body water (TBW) and ECW] and overhydration index (OH) were measured with Multifrequency bio-impedance (BCM). Overhydration was defined as OH/ECW>7%. Overhydration was also assessed using the ECW/TBW ratio. Macrocirculation was assessed by pulse-wave velocity (PWV) and mean arterial pressure (MAP) measurements while microcirculation through sublingual capillaroscopy assessment of the Perfused Boundary Region of the endothelial glycocalyx (PBR 5-25mcg). A panel of pro-inflammatory and vascular serum biomarkers and growth factors was analysed.

RESULTS

Of 72 HD participants, 30 were in normohydration (N) range and 42 overhydrated according to the OH/ECW ratio. Average ECW/TBW was 0.48±0.03. Overhydrated patients had higher MAP (122.9±22.5 v 111.7±22.2mmHg, p = 0.04) and comorbidities (median Davies score 1.5 v 1.0, p = 0.03). PWV (p = 0.25) and PBR 5-25mcg (p = 0.97) did not differ between the 2 groups. However, Vascular Adhesion Molecule (VCAM)-1, Interleukin-6 and Thrombomodulin, and reduced Leptin were observed in the overhydrated group. Elevation in VCAM-1 levels (OR 1.03; 95% CI 1.01-1.06; p = 0.02) showed a strong independent association with OH/ECW>7% in an adjusted logistic regression analysis and exhibited a strong linear relationship with ECW/TBW (Bata = 0.210, p = 0.03) in an also adjusted model.

CONCLUSION

Extracellular fluid overload is significantly linked to microinflammation and markers of endothelial dysfunction. The study provides novel insight in the cardiovascular risk profile associated with overhydration in uraemia.

Skin Autofluorescence and Pentosidine Are Associated With Aortic Stiffening: The Maastricht Study

Arterial stiffening, as characterized by an increase in carotid-femoral pulse-wave velocity or pulse pressure, increases the risk of cardiovascular disease, especially among individuals with type 2 diabetes mellitus. Advanced glycation end products are hypothesized to play a role in the development of arterial stiffness. Therefore, we investigated the association between skin autofluorescence, an estimate of tissue advanced glycation end products, and plasma advanced glycation end products on the one hand and arterial stiffening on the other in 862 participants of The Maastricht Study (mean age of 60 years; 45% women) with normal glucose metabolism (n=469), impaired glucose metabolism (n=140), or type 2 diabetes (n=253). Associations were analyzed with linear regression analysis and adjusted for potential confounders. We found that higher skin autofluorescence as measured by the AGE Reader and plasma pentosidine were independently associated with higher carotid-femoral pulse-wave velocity (sβ 0.10; 95% confidence interval, 0.03-0.17 and 0.10; 0.04-0.16, respectively) and central pulse pressure (sβ 0.08; 95% confidence interval 0.01-0.15 and 0.07; 0.01-0.13, respectively). The associations between skin autofluorescence and pentosidine, and carotid-femoral pulse-wave velocity were more pronounced in individuals with type 2 diabetes mellitus (P-interaction<0.10). These results support the hypothesis that accumulation of advanced glycation end products is involved in arterial stiffening and may explain part of the increased risk of cardiovascular disease in individuals with type 2 diabetes mellitus.

Role of eNOS- and NOX-containing microparticles in endothelial dysfunction in patients with obesity

OBJECTIVE

To explore the pathophysiological profile of patients who have obesity and to investigate the potential role of circulating microparticles (MPs) in endothelial dysfunction in patients who have obesity.

METHODS

The inflammatory and oxidative status and the cutaneous microvascular blood flow were characterized in 69 patients with android obesity and 46 subjects with normal weight (controls) by using laser Doppler flowmetry. Circulating MP levels were measured by flow cytometry, and endothelial nitric oxide synthase (eNOS) and NADPH oxidase (NOX) expression in MPs was investigated by Western blotting. MP effect on vascular reactivity was assessed in rat aorta rings.

RESULTS

Patients with obesity showed endothelial dysfunction, hyperglycemia, inflammation, and oxidative stress. In controls, low MP levels were positively correlated with normal microvascular function. Western blot analysis revealed reduced eNOS and increased NOX4D expression in MPs from subjects with obesity compared with controls. However, this was not correlated with endothelial dysfunction parameters and did not impair ex vivo endothelium-dependent vasodilation.

CONCLUSIONS

These results suggest that MPs do not contribute directly to endothelial dysfunction associated with obesity. Conversely, eNOS- and NOX-containing MPs could be involved in the compensatory mechanism of vascular endothelial cells to counteract the pathologic mechanisms underlying endothelial dysfunction.