The plasma levels of soluble P-selectin in subjects with prediabetes

Low-grade endotoxemia, gut permeability and platelet activation in patients with impaired fasting glucose

BACKGROUND AND AIM

Impaired fasting glucose (IFG) is associated with an increased risk of cardiovascular disease but the underlying mechanisms are still unclear. Aim of the study was to investigate the interplay between platelet activation, lipopolysaccharides (LPS) and markers of oxidative stress in patients with IFG and control subjects.

METHODS AND RESULTS

We performed a cross-sectional study including 35 patients with IFG and 35 control subjects who were well comparable for age, sex, body mass index and smoking history. Serum levels of LPS, zonulin (a marker of gut permeability), oxidized LDL and plasma levels of soluble P-selectin, were measured. Patients with IFG had significantly higher levels of sP-selectin, LPS, zonulin and oxLDL compared to control subjects. The IFG status (beta coefficient: 0.518, p < 0.001), higher LPS (beta coefficient: 0.352, p = 0.001) and female sex (beta coefficient: 0.179, p = 0.042) were independently associated with higher sP-selectin; in addition, oxLDL was positively associated with sP-selectin (r = 0.530, p < 0.001) and LPS (r = 0.529, p = 0.001). In IFG patients, we found a significant association between LPS and zonulin (r = 0.521, p = 0.001); this association was confirmed at multivariable analysis (beta coefficient: 0.512, p = 0.007).

CONCLUSION

Our study provides evidence that patients with IFG have increased platelet activation, and suggests LPS as a potential trigger for in vivo platelet activation in this patient population.

Serum Markers of Endothelial Dysfunction and Inflammation Increase in Hypertension with Prediabetes Mellitus

AIMS

The aim of this study was to examine endothelial dysfunction and inflammation in hypertension and prediabetes by studying adhesion molecules and inflammatory factors.

METHODS AND RESULTS

This study included 133 outpatients. Participants were categorized into three groups based on the presence or absence of hypertension and prediabetes: control subjects without prediabetes and hypertension (N group, n = 39); patients with hypertension only (H group, n = 34); and patients with hypertension and prediabetes (HD group, n = 60). Hypertension was diagnosed according to JNC7 criteria. Prediabetes was defined according to 2010 American Diabetes Association criteria. Plasma was isolated from overnight fasting blood samples for enzyme-linked immunosorbent assay (ELISA) analysis of concentrations of intercellular adhesion molecule-1 (ICAM-1), tumor necrosis factor-α (TNF-α), P-selectin, and interleukin-6 (IL-6) as indicators of endothelial function and inflammation. We found that the H and HD groups showed significantly higher levels of all four biomarkers compared with the N group (all p < 0.01). The HD group also showed significantly higher levels of ICAM-1 (p = 0.042) and TNF-α (p < 0.01) compared with the H group; no significant differences in P-selectin (p = 0.59) and IL-6 (p = 0.70) levels were observed among these groups.

CONCLUSIONS

Prediabetes and hypertension induce endothelial dysfunction and inflammation by elevating levels of soluble adhesion molecules and inflammatory cytokines. The comorbidity of these diseases may exacerbate inflammation and endothelial dysfunction by enhancing the expression of ICAM-1 and TNF-α.

Platelet counts and platelet activation markers in obese subjects

OBJECTIVE

In this work we studied the correlation between platelet count, platelet activation, and systemic inflammation in overweight, obese, and morbidly obese individuals.

METHODS AND SUBJECTS

A total of 6319 individuals participated in the study. Complete blood counts, high sensitivity C-reactive protein (hs-CRP) serum levels, and body mass index (BMI) were measured during routine checkups. Platelet activation markers were studied among 30 obese (BMI = 41 +/- 8 kg/m(2)) and 35 nonobese (BMI = 24 +/- 3 kg/m(2)) individuals. Platelet activation status was evaluated by flow cytometry using specific antibodies against the activated platelet membrane glycoprotein IIb/IIIa, p-selectin (CD-62 p), and binding of Annexin-V to platelet anionic phospholipids.

RESULTS

Overweight, obese, and morbidly obese females had significantly elevated platelet counts ( P < .0001) compared with normal-weight females. No significant elevation of platelet counts was observed in the male subgroups. A significant age adjusted correlation between BMI and platelet counts ( P < .0001) was found among females. This correlation was attenuated (P = .001) after adjustment for hs-CRP concentrations. The flow cytometry analysis of platelets showed no significant differences in activation marker expression between nonobese and obese individuals.

DISCUSSION

Obesity may be associated with elevated platelet counts in females with chronic inflammation. Obesity is not associated with increased platelet activation.

The relationship between endothelial dysfunction and oxidative stress in diabetes and prediabetes

OBJECTIVE

Diabetes mellitus is associated with endothelial dysfunction and oxidative stress (OS). The aim of the present study was to determine whether increased OS and impaired endothelial function, are present in early states of diabetes, such as impaired glucose tolerance (IGT) and impaired fasting glucose (IFG).

METHODS

Brachial artery flow-mediated dilatation (FMD) and nitrate-induced dilatation were measured in 133 subjects with carbohydrate abnormalities (45 IGT, 44 IFG and 44 Type 2 diabetes mellitus) and in 46 subjects with normal glucose tolerance (NGT). Waist circumference, body mass index, blood pressure and fasting lipid profiles were obtained, and glucose and insulin values in response to a 75-g oral glucose load were also measured. Plasma malondialdehyde (MDA) and superoxide dismutase (SOD) activity were determined.

RESULTS

Patients with diabetes and prediabetes had a higher plasma MDA concentration, but a lower plasma SOD activity than the NGT group (p = 0.006) and SOD activity was positively associated with FMD (p = 0.039). FMD were significantly reduced in the groups of subjects with abnormal carbohydrate metabolism compared with the NGT group (p = 0.035). Among the subjects with diabetes and prediabetes, FMD showed a negative correlation with fasting glucose and/or plasma glucose level at 120 min after oral glucose tolerance test (p = 0.028).

CONCLUSIONS

The results showed that endothelial dysfunction and increased OS were present in subjects with IGT and IFG, indicating endothelial damage in these stages.

Plasma visfatin levels in patients with newly diagnosed and untreated type 2 diabetes mellitus and impaired glucose tolerance

Visfatin, a new adipokine, facilitates adipogenesis and has insulin-mimetic properties. We aimed to investigate the plasma visfatin levels in patients with newly diagnosed and untreated type 2 diabetes mellitus (T2DM) and impaired glucose tolerance (IGT), who had no obesity or hypertension. Twenty-two patients with T2DM, 18 subjects with IGT and 40 healthy controls were enrolled. Visfatin levels were measured along with the BMI, blood pressure, lipids, glucose, insulin, adiponectin and hsCRP levels, and HOMA-IR indexes. Age, sex and BMI were similar in all groups. Visfatin levels were higher in the diabetic group than the controls (p=0.01). There was no significant difference in the visfatin levels between the T2DM and IGT groups as well as IGT group and healthy controls. Plasma visfatin concentrations did not differ between men and women. Visfatin levels did not correlate with BMI, blood pressure, plasma adiponectin, insulin, hsCRP, glucose and lipid levels or HOMA-IR indexes in the three groups. These results indicate that hyperglycemia causes an increase in plasma visfatin levels and, as in people with T2DM but not with IGT, this increase gets more prominent as the glucose intolerance worsens.

Platelet aggregation is not enhanced in patients with prediabetes

Prediabetes [impaired glucose tolerance (IGT) and/or impaired fasting glucose (IFG)] is a major risk factor for T2DM as well as for cardiovascular disease and mortality. In the present study, the platelet aggregation and fibrinogen levels were investigated in prediabetic subjects who had no confounding factors such as hypertension, obesity or dyslipidemia. Thirty-nine subjects with prediabetes (24 IFG and 15 IGT) and age, sex and BMI matched 36 healthy controls were enrolled. Platelet aggregation, fibrinogen and hsCRP levels, HOMA-IR and HOMA-beta indexes were determined. Platelet aggregation induced by collagen, epinephrine or ADP was not different (p=0.93, p=0.90 and p=0.29, respectively) between two groups, whereas fibrinogen levels were significantly higher (p=0.006) in the prediabetics when compared to controls. hsCRP levels, HOMA-IR and HOMA-beta indexes in the two groups were not different. The power of the study was calculated according to the results and established as 0.97 for collagen, 0.95 for epinephrine and 0.83 for ADP. Despite the high plasma fibrinogen levels, the platelet aggregation in prediabetics was not different when compared to healthy controls. These data suggest that platelet aggregation may not be involved in the mechanism of prothrombotic state in prediabetic state.