Effects of glucose control and variability on endothelial function and repair in adolescents with type 1 diabetes

Exposure to air pollution and cardiovascular risk in young children - a pilot project

OBJECTIVE

To examine relationships between traffic-related air pollution (TRAP) and markers of pre-clinical cardiovascular risk in young children.

STUDY DESIGN

We studied a cohort of healthy children ages 2-5 recruited from pediatric primary care sites (n = 122). We obtained child weight, height, blood pressure and hair nicotine levels. A blood sample was obtained for biomarkers of systemic inflammation, oxidation, and prevalence of circulating endothelial progenitor cells. This manuscript represents a secondary analysis. TRAP exposure (particulate levels, nitrogen dioxide, nitrogen oxides, and proximity to major roadways) was assessed using national air pollution data based on child's census tract of residence.

RESULTS

TRAP exposure had significant positive associations with prevalence of two of the three EPC subtypes (CD34 + /CD133 + /CD45- and CD133 + /CD45-) in unadjusted correlations. In a linear regression model, adjusting for sex, age, race, ethnicity, body mass index, parental education, child insurance, and secondhand smoke exposure, one EPC subtype (CD133 + /CD45-) had a positive significant correlation to every TRAP measure. No significant relationships between air pollution and measures of inflammation and oxidation was found.

CONCLUSION

Our findings of the upregulation of EPCs may signal a response to early vascular damage during early childhood due to air pollution exposure.

IMPACT

Traffic-related air pollution (TRAP) - known cardiovascular risk factor during adulthood Current pilot study in very young children shows upregulation of cells which protect the endothelial lining of blood vessels (endothelial progenitor cells, EPCs) Upregulation of EPCs aligns with other cardiovascular risks during childhood (obesity, prematurity, type 1 diabetes) Demonstrated with TRAP exposure lower than EPA threshold Response to air pollution may be protective of cardiovascular damage during early childhood.

Women Have Greater Endothelin-B Receptor Function and Lower Mitochondrial Capacity Compared to Men With Type 1 Diabetes

CONTEXT

Type 1 diabetes (T1D) negatively affects both the endothelin system and muscle oxidative capacity. The endothelin pathway is a critical regulator of microcirculatory function and may exhibit sexual dichotomy by which healthy premenopausal women have greater endothelin-B receptor (ETBR) function compared to men. Moreover, T1D may differentially alter muscle oxidative capacity in men and women; however, whether ETBR function is impaired in women compared to men with T1D and its relationship with muscle oxidative capacity has yet to be explored.

OBJECTIVE

The purpose of this investigation was to determine if ETBR-mediated dilation is impaired in women compared to men with T1D and if this is related to their skeletal muscle oxidative capacity.

METHODS

Men (n = 9; glycated hemoglobin A1c [HbA1c] = 7.8 ± 1.0%) and women (N = 10 women; HbA1c = 8.4 ± 1.3%) with uncomplicated T1D were recruited for this investigation. Near-infrared spectroscopy (NIRS) and intradermal microdialysis (750 nM BQ-123 + ET-1 [10-20-10-8 mol/L]) were used to evaluate skeletal muscle oxidative capacity and assess ETBR-mediated vasodilation, respectively.

RESULTS

Skeletal muscle oxidative capacity was significantly lower (P = .031) in women compared with men with T1D. However, ETBR-mediated dilation induced a significantly greater (P = .012) vasodilatory response in women compared to men with T1D, and the area under the curve was negatively associated with skeletal muscle oxidative capacity (r = -.620; P = .042).

CONCLUSION

Compared to men with uncomplicated T1D, muscle oxidative capacity was lower and ETBR-mediated vasodilation was higher in women with uncomplicated T1D. ETBR-induced vasodilatory capacity was inversely related to skeletal muscle oxidative capacity, suggesting there may be compensatory mechanisms occurring to preserve microvascular blood flow in women with T1D.

Oscillating Glucose Induces the Increase in Inflammatory Stress through Ninjurin-1 Up-Regulation and Stimulation of Transport Proteins in Human Endothelial Cells

Clinical data implicate fluctuations of high levels of plasma glucose in cardiovascular diseases. Endothelial cells (EC) are the first cells of the vessel wall exposed to them. Our aim was to evaluate the effects of oscillating glucose (OG) on EC function and to decipher new molecular mechanisms involved. Cultured human ECs (EA.hy926 line and primary cells) were exposed to OG (5/25 mM alternatively at 3 h), constant HG (25 mM) or physiological concentration (5 mM, NG) for 72 h. Markers of inflammation (Ninj-1, MCP-1, RAGE, TNFR1, NF-kB, and p38 MAPK), oxidative stress (ROS, VPO1, and HO-1), and transendothelial transport proteins (SR-BI, caveolin-1, and VAMP-3) were assessed. Inhibitors of ROS (NAC), NF-kB (Bay 11-7085), and Ninj-1 silencing were used to identify the mechanisms of OG-induced EC dysfunction. The results revealed that OG determined an increased expression of Ninj-1, MCP-1, RAGE, TNFR1, SR-B1, and VAMP-3 andstimulated monocyte adhesion. All of these effects were induced bymechanisms involving ROS production or NF-kB activation. NINJ-1 silencing inhibited the upregulation of caveolin-1 and VAMP-3 induced by OG in EC. In conclusion, OG induces increased inflammatory stress, ROS production, and NF-kB activation and stimulates transendothelial transport. To this end, we propose a novel mechanism linking Ninj-1 up-regulation to increased expression of transendothelial transport proteins.

Early Endothelial Dysfunction in Type 1 Diabetes Is Accompanied by an Impairment of Vascular Smooth Muscle Function: A Meta-Analysis

Background: A large yet heterogeneous body of literature exists suggesting that endothelial dysfunction appears early in type 1 diabetes, due to hyperglycemia-induced oxidative stress. The latter may also affect vascular smooth muscles (VSM) function, a layer albeit less frequently considered in that pathology. This meta-analysis aims at evaluating the extent, and the contributing risk factors, of early endothelial dysfunction, and of the possible concomitant VSM dysfunction, in type 1 diabetes. Methods: PubMed, Web of Sciences, Cochrane Library databases were screened from their respective inceptions until October 2019. We included studies comparing vasodilatory capacity depending or not on endothelium (i.e., endothelial function or VSM function, respectively) in patients with uncomplicated type 1 diabetes and healthy controls. Results: Fifty-eight articles studying endothelium-dependent function, among which 21 studies also assessed VSM, were included. Global analyses revealed an impairment of standardized mean difference (SMD) (Cohen's d) of endothelial function: -0.61 (95% CI: -0.79, -0.44) but also of VSM SMD: -0.32 (95% CI: -0.57, -0.07). The type of stimuli used (i.e., exercise, occlusion-reperfusion, pharmacological substances, heat) did not influence the impairment of the vasodilatory capacity. Endothelial dysfunction appeared more pronounced within macrovascular than microvascular beds. The latter was particularly altered in cases of poor glycemic control [HbA_1c > 67 mmol/mol (8.3%)]. Conclusions: This meta-analysis not only corroborates the presence of an early impairment of endothelial function, even in response to physiological stimuli like exercise, but also highlights a VSM dysfunction in children and adults with type 1 diabetes. Endothelial dysfunction seems to be more pronounced in large than small vessels, fostering the debate on their relative temporal appearance.

Predictive Value of Blood Glucose Range for Onset of Complications in Patients with Diabetes Mellitus Type 1

Background and aims: to develop a prognostic mathematical model for risk of microangiopathy in patients with diabetes mellitus type 1 (T1DM). Materials and methods: 62 T1DM patients were divided into 2 groups according to НвА1с level: group 1 (n=18) with НвА1с ≤ 7.0% and group 2 (n=44) with НвА1с > of 7.0%. HbA1c, Cpeptide, blood creatinine, estimated glomerular filtration rate (eGFR) CKD-EPI, first morning urinary albumin excretion (AU) were determined. Blood glucose levels were conducted by CGMS (Continuous Glucose Monitoring System). All patients were followed for 3 months. Rank correlation method was used. Results: We established the direct correlation between HbA1c the AU level ρ=0.29 (р<0.016) at the beginning and ρ=0.4 (р=0.021) after 3 months. AU level has a direct correlation with blood glucose range, at the beginning ρ=0.51 (р<0.001) and after 3 months ρ=0.48 (р=0.004) visits. We made the mathematical description of this dependence. Each additional unit of blood glucose range is accompanied by increasing an average level AU level by 0.4816 mg/l. Conclusion: our mathematical equation of dependence between AU level and blood glucose range gives the opportunities to predict diabetic kidney disease progression in T1DM patients.

Glycemic variability predicts inflammation in adolescents with type 1 diabetes

BACKGROUND

Adolescents with type 1 diabetes (T1D) have increased risk of cardiovascular disease as well as elevations in biomarkers of systemic inflammation, plasma protein oxidation and vascular endothelial injury. It is unclear whether hyperglycemia itself, or variations in blood glucose are predictors of these abnormalities.

METHODS

This study was designed to determine the relationship of inflammatory (C-reactive protein, CRP), oxidative (total anti-oxidative capacity, TAOC) and endothelial injury (soluble intracellular adhesion molecule 1, sICAM1) markers to glycemic control measures from 3 days of continuous glucose monitoring (CGM) and to hemoglobin A1c (HbA1c), and HbA1c×duration area under the curve (A1cDur).

RESULTS

Seventeen adolescents (8 F/9M; age, 13.1±1.6 years (mean±SD); duration, 4.8±3.8 years, BMI, 20.3±3.1 kg/m2; A1c, 8.3±1.2%) were studied. Log CRP but was not related to age, duration, body mass index (BMI), HbA1c, or A1cDUR. TAOC increased as logA1cDUR increased (n=13, r=0.61, p=0.028). CRP and sICAM were not related to CGM average glucose but log CRP increased as 3 day glucose standard deviation increased (r=0.66, p=0.006). TAOC increased as glucose standard deviation increased (r=0.63, p=0.028).

CONCLUSIONS

Increased glucose variability is associated with increased inflammation in adolescents withT1D. Increased TAOC with increasing variability may be an effort to compensate for the ongoing oxidative stress.

Assessing endothelial dysfunction in adolescents and young adults with type 1 diabetes mellitus using a non-invasive heat stimulus

BACKGROUND

Microvascular dysfunction is a key event in the development of atherosclerosis, which predates the clinical manifestations of vascular disease including stroke and myocardial infarction. Dysfunction of the microvasculature can be measured as a decreased microperfusion in response to heat.

OBJECTIVE

We sought to evaluate the microvasculature using heat among adolescents and young adults with type 1 diabetes (T1D) compared to healthy non-diabetic controls. We hypothesized that youth with T1D would have impaired microvascular function measured as decreased perfusion.

METHODS

We studied 181 adolescents and young adults with T1D and 96 age-, race-, and sex-matched healthy controls (mean age 19 yr). Patients were seen at an in-person study visit where demographics, anthropometrics, and laboratory data was obtained. Skin microvascular perfusion was measured on the volvar surface of the right forearm using a standard laser flow Doppler. Measurements were taken at baseline and after heating to 44° C.

RESULTS

Youth with T1D had decreased microvascular perfusion as measured by lower percent change of perfusion units (1870 ± 945 vs. 2539 ± 1255, p < 0.01) and percent change in area under the curve (1870 ± 945 vs. 2539 ± 1255, p < 0.01) compared to controls. Glycosylated hemoglobin A1c (HbA1c) was found to be an independent determinant of microvascular function (p < 0.05).

CONCLUSIONS

Adolescents and young adults with T1D have evidence of microvascular dysfunction that can be detected using heat, a non-invasive physiologic stimulus. HbA1c appears to play an independent role in determining microvascular perfusion suggesting tight glycemic control is probably important for the development of vascular disease.

Circulating Dipeptidyl Peptidase-4 Activity is Associated with Diabetic Retinopathy in Type 1 Diabetic Patients

Purpose

Diabetic retinopathy (DR) is the most frequent complication among patients with type 1 diabetes mellitus (T1DM). Dipeptidyl peptidase–4 (DPP4) is a protease with elevated activity in patients with T1DM. Several studies indicate that DPP4 inhibitors might have beneficial effect on nonproliferative retinopathy (NPR) development as well as on its progression to proliferative retinopathy (PR). We aimed to explore the relationship between serum DPP4 activity and DR in patients with T1DM.

Methods

This cross-sectional study recruited 44 patients with T1DM. The DPP4 activity was measured by colorimetric assay in a microplate reader. Photodocumented retinopathy status was made according to the EURODIAB protocol.

Results

A total of 28 (63.6%) patients were men, mean age 45.36 years, diabetes duration 23.71 years, glycated hemoglobin A1c (HbA1c) 7.4%. Patients were stratified into 2 groups according to retinopathy prevalence. Group 1 comprised 14 (31.85%) patients with DR absence while the second group consisted of 30 (68.15%) patients with both PR and NPR. Group 1 had lower fasting serum DPP4 activity (25.85 vs 33.84 U/L, p<0.001) when compared to the second group. In the binary logistic regression model adjusted for age, sex, diabetes duration, and HbA1c level, DPP4 activity was associated with DR prevalence (odds ratio 1.887 [1.073-3.321]).

Conclusions

Serum DPP4 activity may be independently associated with both DR types in patients with T1DM. Further study is warranted to elucidate whether there is an association between DPP4 activity and DR severity and/or progression.