Does oxidized LDL contribute to atherosclerotic plaque formation and microvascular complications in patients with type 1 diabetes?

Risk factors for pre-clinical atherosclerosis in adolescents with type 1 diabetes

AIMS

To assess whether, besides "traditional" risk factors, overall oxidative stress, oxidized lipoproteins, and glycemic variability are associated with early macro-vascular damage in type 1 diabetes (T1D).

METHODS

In 267 children/adolescents with T1D (130 girls, age 9.1-23.0 years) we evaluated: derivatives of reactive oxygen metabolites [d-ROMs], serum total antioxidant capacity [TAC] and oxidized LDL-cholesterol [oxLDL]; markers of early vascular damage (Lipoprotein-associated phospholipase A2 [Lp-PLA2], z-score of carotid intima-media thickness [z-cIMT] and carotid-femoral pulse wave velocity [z-PWV]); CGM metrics of four weeks preceding the visit, central systolic/diastolic blood pressures (cSBP/cDBP), and HbA1c, z-score of BP (z-SBP/z-DBP) and circulating lipids longitudinally collected since T1D onset.. Three general linear models were built with z-cIMT, z-PWV adjusted for current cDBP, and Lp-PLA2 as independent variables.

RESULTS

The z-cIMT was associated with male gender (B = 0.491, η² = 0.029, p = 0.005), cSBP (B = 0.023, η² = 0.026, p = 0.008) and oxLDL (B = 0.022, η² = 0.022, p = 0.014). The z-PWV was associated with diabetes duration (B = 0.054, η² = 0.024, p = 0.016), daily insulin dose (B = 0.52, η² = 0.018, p = 0.045), longitudinal z-SBP (B = 0.18, η² = 0.018, p = 0.045) and dROMs (B = 0.003, η² = 0.037, p = 0.004). Lp-PLA2 was associated with age (B = 0.221, η² = 0.079, p = 3*10^-6), oxLDL (B = 0.081, η² = 0.050, p = 2*10^-4), longitudinal LDL-cholesterol (B = 0.031, η² = 0.043, p = 0.001) and male gender (B = -1.62, η² = 0.10, p = 1.3*10⁷).

CONCLUSIONS

Oxidative stress, male gender, insulin dose, diabetes duration and longitudinal lipids and blood pressure, contributed to the variance of early vascular damage in young patients with T1D.

Heparin-binding epidermal growth factor (EGF)-like growth factor in pediatric patients with type 1 diabetes mellitus

Heparin-binding EGF-like growth factor (HB-EGF) is involved in atherosclerosis progression. We investigated association between plasma HB-EGF levels and lipid, oxidative stress and inflammatory biomarkers in pediatric patients with type 1 diabetes mellitus (T1DM). Levels of HB-EGF, high-sensitive C-reactive protein (hsCRP), prooxidant-antioxidant balance (PAB), total antioxidant status (TAS), oxidized low-density lipoproteins (oxLDL), metabolic control and serum lipid parameters and paraoxonase 1 (PON1) activity were determined in 74 patients and 40 controls. In comparison to controls, patients had significantly higher levels (p < 0.01) of HB-EGF, hsCRP, PAB and oxLDL particles (p < 0.001), but lower levels of TAS and PON1 activity. In T1DM group, HB-EFG levels were positively associated with hsCRP, PAB and oxLDL levels. hsCRP and oxLDL levels were independent predictors of HB-EGF concentration. We demonstrated that oxidative modifications of LDL particles and low-grade inflammation are main determinants of increased plasma HB-EGF levels, which indicates an interactive role of oxidative stress, dyslipidemia and inflammation.

Serum cathelicidin as a marker for diabetic nephropathy in patients with type 1 diabetes

BACKGROUND

The aim of the study was to evaluate the relationship between serum cathelicidin level and diabetic nephropathy (DN) in patients with type 1 diabetes mellitus (T1DM).

METHODS

The study group consisted of 76 patients with T1DM (47 men), aged 36 ± 7 years, and with duration of T1DM 14 (7-18) years. Serum cathelicidin was measured by ELISA test in healthy controls (n = 20) and in 76 T1DM patients grouped as follows: G1 = patients with normal urinary albumin excretion (n = 20), G2 = patients with microalbumin excretion (n = 19), G3 = patients with macroalbumin excretion but normal serum creatinine level (n = 19), and G4 = patients with macroalbumin excretion with increased serum creatinine (n = 18).

RESULTS

There was no significant difference in serum cathelicidin levels between healthy controls and G1 diabetic patients, but serum levels were progressively increased from the stage of microalbuminuria to frank nephropathy (P < .001). Positive correlation between serum cathelicidin level and the presence of DN, thyroid-stimulating hormone, total cholesterol, and negative with male sex and fasting plasma glucose, was found. In multiple regression analysis, serum cathelicidin level was associated with the presence of DN after adjustment of sex, waist-to-hip ratio, total cholesterol, and thyroid-stimulating hormone.

CONCLUSIONS

Patients with T1DM and DN are characterized by increased serum cathelicidin level. There was an independent relationship between serum cathelicidin level and DN. Serum cathelicidin level can be used as an early marker for the presence and progression of DN in T1DM patients.

Is cathelicidin a novel marker of diabetic microangiopathy in patients with type 1 diabetes?

AIM

The aim was to evaluate the relationship between higher serum cathelicidin levels with the occurrence of chronic microangiopathic complications in patients with diabetes mellitus type 1 (DM1).

METHODS

The study group consisted of 62 patients with DM1 (35 men), aged 30 (24-38) years and with duration of DM1 12 (9-17) years. Patients were divided into two groups depending on the level of cathelicidin, with cut-off point 24.5ng/ml (median value for the whole group) and according to the presence or absence of any microangiopathy.

RESULTS

The group with higher serum level of cathelicidin (n=31) in comparison with patients with lower levels (n=31) had higher serum level of total cholesterol [5.0(4.5-5.6) vs 4.5(3.9-5.0) mmol/l; p=0.04], HDL cholesterol [1.9(1.5-2.1) vs 1.4(1.3-1.8) mmol/l; p=0.009], LDL cholesterol [2.6(2.2-3.1) vs 2.3(1.9-2.8) mmol/l; p=0.03] and higher TSH value [1.8(1.5-2.6) vs 1.4(0.9-2.1) mIU/L; p=0.01]. Moreover, higher serum levels of cathelicidin were in women than men (58% vs 29%, p=0.02) and in patients with vs without microangiopathy (45% vs 19%, p=0.03). In the multiple regression model higher serum level of cathelicidin was related to the presence of microangiopathy, independently from sex, waist to hip ratio, serum total cholesterol level and TSH.

CONCLUSIONS

Patients with type 1 diabetes and presence of microangiopathy characterize higher level of serum cathelicidin. This observation may have important clinical implication and needs further investigations.

Elevated atherosclerosis-related gene expression, monocyte activation and microparticle-release are related to increased lipoprotein-associated oxidative stress in familial hypercholesterolemia

Objective

Animal and in vitro studies have suggested that hypercholesterolemia and increased oxidative stress predisposes to monocyte activation and enhanced accumulation of oxidized LDL cholesterol (oxLDL-C) through a CD36-dependent mechanism. The aim of this study was to investigate the hypothesis that elevated oxLDL-C induce proinflammatory monocytes and increased release of monocyte-derived microparticles (MMPs), as well as up-regulation of CD36, chemokine receptors and proinflammatory factors through CD36-dependent pathways and that this is associated with accelerated atherosclerosis in subjects with heterozygous familial hypercholesterolemia (FH), in particular in the presence of Achilles tendon xanthomas (ATX).

Approach and Results

We studied thirty FH subjects with and without ATX and twenty-three healthy control subjects. Intima-media thickness (IMT) and Achilles tendon (AT) thickness were measured by ultrasonography. Monocyte classification and MMP analysis were performed by flow cytometry. Monocyte expression of genes involved in atherosclerosis was determined by quantitative PCR. IMT and oxLDL-C were increased in FH subjects, especially in the presence of ATX. In addition, FH subjects had elevated proportions of intermediate CD14++CD16+ monocytes and higher circulating MMP levels. Stepwise linear regression identified oxLDL-C, gender and intermediate monocytes as predictors of MMPs. Monocyte expression of pro-atherogenic and pro-inflammatory genes regulated by oxLDL-C-CD36 interaction was increased in FH, especially in ATX+ subjects. Monocyte chemokine receptor CX₃CR1 was identified as an independent contributor to IMT.

Conclusions

Our data support that lipoprotein-associated oxidative stress is involved in accelerated atherosclerosis in FH, particularly in the presence of ATX, by inducing pro-inflammatory monocytes and increased release of MMPs along with elevated monocyte expression of oxLDL-C-induced atherosclerosis-related genes.

Relationship between oxidized low-density lipoprotein antibodies and obesity in different glycemic situations

BACKGROUND

Autoantibodies to oxidized low-density lipoprotein (oxLDL) are a heterogeneous group of antibodies that are controversially discussed to be either pathogenic or protective. Biochemical and anthropometric measurements correlated with increased levels of these antibodies are also controversial, especially in conditions of impaired glucose tolerance and type 2 diabetes mellitus. The present study was conducted to evaluate levels of oxLDL antibodies and their correlation with obesity in different glycemic situations.

METHODS

Two hundred and seventy-four adult males were classified into three subgroups: group 1 (n=125), comprising a control group of nondiabetic subjects; group 2 (n=77), comprising subjects with impaired glucose tolerance; and group 3 (n=72), comprising patients with type 2 diabetes mellitus. Body mass index was calculated, and measurement of oxLDL and oxLDL antibodies was performed.

RESULTS

Higher mean concentrations of oxLDL were found in the type 2 diabetes mellitus and impaired glucose tolerance groups (143.5±21.9 U/L and 108.7±23.7 U/L, respectively). The mean value for the control group was 73.5±27.5 U/L (P<0.001). Higher mean concentrations of anti-oxLDL antibodies were observed in the type 2 diabetes mellitus and impaired glucose tolerance groups (55.7±17.8 U/L and 40.4±17.6 U/L, respectively). The mean value for the control group was 20.4±10 U/L (P<0.001). Levels of anti-oxLDL antibodies were found to be positively and significantly correlated with body mass index in the control group (r=0.46), impaired glucose tolerance (r=0.51), type 2 diabetes mellitus group (r=0.46), and in the whole study population (r=0.44; P<0.001).

CONCLUSION

Anti-oxLDL antibody levels were increased in subjects with type 2 diabetes mellitus and impaired glucose tolerance and were positively correlated with obesity and body mass index.