Macrophages are novel sites of expression and regulation of retinol binding protein-4 (RBP4)

Obesity is linked to a low-level chronic inflammatory state that may contribute to the development of associated metabolic complications. Retinol-binding protein 4 (RBP4) is an adipokine associated with parameters of obesity including insulin resistance indices, body mass index, waist circumference, lipid profile, and recently, with circulating inflammatory factors. Due to the infiltration of adipose tissue in obesity by macrophages derived from circulating monocytes and, on the other hand, the existence of a close genetic relationship between adipocytes and macrophages, we decided to examine if RBP4 is expressed in monocytes and/or primary human macrophages. While we did not detect expression of RBP4 in undifferentiated monocytes, RBP4 expression became evident during the differentiation of monocytes into macrophages and was highest in differentiated macrophages. Once we demonstrated the expression of RBP4 in macrophages, we checked if RBP4 expression could be regulated by inflammatory stimuli such as tumor necrosis factor-alpha (TNF-alpha), interleukin-6 (IL-6), or the endotoxin lipopolysaccharide (LPS). We observed that while RBP4 expression was strongly inhibited by TNF-alpha and LPS, it was not affected by IL-6. Our results highlight the complexity behind the regulation of this adipokine and demonstrate that RBP4 expression in macrophages could be modulated by inflammatory stimuli.

Adult subjects with Prader-Willi syndrome show more low-grade systemic inflammation than matched obese subjects

AIM

Adult subjects with Prader-Willi syndrome (PWS) may show several conditions that are associated with an activation of innate immunity such as obesity, deficient GH secretion or hypogonadism. Our aim was to study whether obese adult PWS subjects show an additional low-grade systemic inflammation (LGSI) in relation to obese adult non-PWS subjects and lean healthy control subjects before and after a standardized liquid meal.

METHODS

Seven obese adult PWS subjects, 7 matched obese non-PWS subjects and 7 lean healthy control subjects were studied for 6 h from the administration of a standard liquid meal.

RESULTS

Compared to non-PWS, PWS subjects showed higher plasma concentrations of C-reactive protein (CRP) (p=0.030), complement component C3 (p=0.018), interleukin(IL)-18 (p=0.048), and IL-6 (p=0.041) that persisted post-prandially elevated for CRP (p<0.0001), C3 (p=0.015), and IL-18 (p=0.003). Tumor necrosis factor(TNF)-alpha did not differ between the 3 groups. These results were independent from IGF-I levels, homeostasis model assessment index, and body mass index (BMI). In male subjects with PWS, testosterone levels correlated to IL-18 (r=-0,646, p=0.041).

CONCLUSIONS

Compared to matched non-PWS subjects, the obese PWS subjects in this study showed an additional LGSI that persisted postprandially and was independent from BMI, insulin resistance, and deficient GH secretion. However, in PWS males, high IL-18 levels were related to low testosterone concentrations.

Effect of weight loss induced by gastric bypass on proinflammatory interleukin-18, soluble tumour necrosis factor-alpha receptors, C-reactive protein and adiponectin in morbidly obese patients

OBJECTIVE

Interleukin-18 (IL-18) is a potent proinflammatory cytokine whose role in human obesity has recently been suggested. The aim of our study was to analyse in morbidly obese patients undergoing gastric bypass, the relationship of IL-18 with insulin resistance and with proinflammatory cytokines (tumour necrosis factor-alpha receptors, sTNFR), C-reactive protein (CRP) and with adiponectin.

DESIGN

Observational and prospective study.

PATIENTS

Sixty-five morbidly obese patients, aged 45 +/- 8.9 years, were studied before and 12 months after gastric bypass.

MEASUREMENTS

We analysed plasma concentrations of IL-18, sTNFR, CRP and adiponectin.

RESULTS

Plasma concentrations of sTNFR2, IL-18 and CRP were decreased and adiponectin significantly increased after bypass surgery. In the multiple regression analysis, preoperative values of IL-18 remained significantly associated with preoperative triglycerides (beta = 0.47, P = 0.005) and TNFR2 (beta = 0.47, P = 0.004). R(2) for the model = 0.38. Postoperative IL-18 concentrations in the multiple regression analysis were significantly associated with postoperative homeostasis model assessment of insulin resistance (HOMA-IR) (beta = 0.092, P = 0.019) and triglycerides (beta = 0.40, P = 0.036). R(2) for the model = 0.46. IL-18 did not correlate with body mass index, fat mass, fat-free mass or body fat. No relationship was either found between adiponectin and IL-18, TNFR1 and -2 and CRP.

CONCLUSIONS

Massive weight loss induced by gastric bypass reduces IL-18, TNFR2 and CRP. IL-18 might be a marker of the chronic inflammatory process underlying insulin resistance but its lack of association with anthropometric and body composition parameters does not support a major secretion by human adipocytes. IL-18 and sTNFR1 and -2 do not play a main role in the inhibition of the secretion of adiponectin.

Lower heart rate variability is associated with higher plasma concentrations of IL-6 in type 1 diabetes

OBJECTIVE

In type 1 diabetes, cardiovascular autonomic neuropathy (CAN) is associated with cardiovascular risk factors related to insulin resistance, which in turn are associated with low-grade systemic inflammation. Reduced heart rate variability (HRV) is considered one of the first indicators of CAN. Since the autonomic nervous system interacts with systemic inflammation, we evaluated CAN to study its possible association with low-grade systemic inflammation.

DESIGN

Cross-sectional study of a group of 120 subjects diagnosed with type 1 diabetes mellitus 14 years before.

METHODS

Information recorded: 1) clinical characteristics: sex, age, body mass index, waist-to-hip ratio (WHR), blood pressure (BP), smoking, alcohol intake, insulin dose, HbA1c, and lipid profile; 2) plasma levels of soluble fractions of tumour necrosis factor alpha receptors 1 and 2, IL-6, and C-reactive protein; 3) insulin resistance by estimation of the glucose disposal rate (eGDR); and 4) tests for CAN: HRV in response to deep breathing (E/I ratio), HRV in response to the Valsalva maneuver, and changes in systolic BP responding to standing.

RESULTS

A significant negative correlation was found between E/I ratio and plasma concentrations of IL-6 (r=-0.244, P=0.032), which remained significant after adjusting for potential confounding factors (age, sex, HbA1c, WHR, diastolic BP, triglycerides, HDL-cholesterol, retinopathy, nephropathy, peripheral neuropathy, insulin dose, and smoking; r=-0.231, P=0.039). No other significant associations were found between inflammation-related proteins, tests for CAN, and eGDR.

CONCLUSIONS

These findings suggest a link between low-grade inflammation and early alterations of CAN in type 1 diabetes and may be of importance in the pathogenesis of CAN and/or its clinical implications.

IL-18: relationship with anthropometry, body composition parameters, leptin and arterial hypertension

OBJECTIVE

Interleukin-18 (IL-18) is a potent pro-inflammatory cytokine with potential atherogenic properties whose role in human obesity has been recently suggested. The aim of our study was to analyze the physiologic distribution of IL-18 among sexes and all decades of the adult life in a healthy population randomly selected and to study its relationship with anthropometric, body composition measurements and leptin concentrations. We also studied the relationship of IL-18 with smoking and arterial hypertension, known risk factors implicated in atherogenesis.

MATERIALS AND METHODS

One hundred and thirty four men and 127 healthy women were included in the study. Plasma concentrations of IL-18 and leptin were determined in all subjects. Body composition was evaluated by bioelectrical impedanciometry.

RESULTS

IL-18 was distributed similarly in men and women and throughout decades. No significant differences were found in IL-18 between obese and normal-weight men and women according to their body mass index and body fat content. Higher IL-18 concentrations were found in subjects with arterial hypertension. In the bivariate correlation analysis only waist to hip ratio correlated weakly with IL-18 in the whole population (r=0.12, p=0.04). In the multiple regression analysis the relationship between IL-18 and waist to hip ratio lost significance after adjusting for age, sex and body mass index. However, IL-18 remained associated with arterial hypertension (adjusted r2=0.25, p=0.023).

CONCLUSIONS

The lack of correlation between IL-18 with anthropometric, body composition variables and leptin in our healthy population argues against a role of this cytokine in obesity. Moreover, our findings suggest the implication of this interleukin in the atherogenic process induced by arterial hypertension.

The tumour necrosis factor (TNF)-alpha system is activated in accordance with pulse pressure in normotensive subjects with type 1 diabetes mellitus

OBJECTIVE

Pulse pressure (PP) and inflammation are important predictors of cardiovascular disease (CVD), even in the normotensive. The age-related increase in PP can be diagnosed up to 20 years earlier in subjects with type 1 diabetes mellitus (T1DM) than in the general population. Some evidence suggests that PP can stimulate inflammation. Our aim was to study the relationship between PP and plasma inflammatory proteins in normotensive subjects with T1DM.

DESIGN

This was a cross-sectional study of a group of normotensive (<140/80 mmHg) subjects diagnosed with T1DM 14 years before. None of them had clinically proven CVD or inflammatory conditions or were on antiplatelet, antihypertensive, anti-inflammatory or lipid-lowering treatment.

METHODS

The following information was recorded: sex, age, body-mass index (BMI), waist-to-hip ratio (WHR), systolic blood pressure (SBP), diastolic blood pressure (DBP), PP, mean blood pressure (MBP), smoking, alcohol intake, insulin dose, lipid profile, HbA1c, microvascular complications, and plasma concentrations of soluble receptor types 1 and 2 of tumour necrosis factor (TNF)-alpha (sTNFR1 and sTNFR2, respectively), interleukin-6, C-reactive protein, adiponectin and leptin.

RESULTS

A total of 112 subjects were evaluated (aged 27.4+/-6.6 years, 52.7% women, BMI: 20.4+/-2.7 kg/m2, WHR: 0.82+/-0.09, SBP: 112+/-12 mmHg, DBP: 68+/-9 mmHg, PP: 45+/-9 mmHg, MBP: 82+/-9 mmHg, HbA1c: 8.2% (7.3-9.0%), 41.1% microvascular complications). After adjusting for potential confounders, only inflammatory markers of the TNF-alpha system correlated significantly with PP (Pearson correlation coefficient between sTNFR1 and PP: r = 0.215, P = 0.030; and between PP and sTNFR2: r = 0.238, P = 0.020).

CONCLUSION

In normotensive subjects with T1DM after 14 years of diagnosis, the activation of the TNF-alpha system is positively associated with PP levels. This finding might suggest a pathogenic role of the TNF-alpha system in the development of cardiovascular disease in T1DM.

Diabetic neuropathy is associated with activation of the TNF-alpha system in subjects with type 1 diabetes mellitus

OBJECTIVE

The development of diabetic neuropathy (DN) is predicted by cardiovascular risk factors associated with insulin resistance. As inflammation seems to be implicated in the pathogenesis of insulin resistance, we investigated whether subjects with type 1 diabetes mellitus (T1DM) and DN have an increase in plasma concentrations of inflammatory proteins involved in insulin resistance.

DESIGN

Cross-sectional. Patients One hundred twenty subjects, all diagnosed with T1DM 14 years before.

MEASUREMENTS

(1) Sex, age, body mass index, waist-to-hip ratio (WHR), blood pressure, smoking, alcohol intake, insulin dose, HbA1c and lipid profile; (2) DN (peripheral and cardiac autonomic), retinopathy and nephropathy; (3) plasma concentrations of soluble fractions of tumour necrosis factor alpha receptors 1 and 2 (sTNFR1 and sTNFR2), interleukin-6, high-sensitive C-reactive protein, adiponectin and leptin; and (4) insulin resistance (by way of a mathematical estimation of the glucose disposal rate - eGDR-).

RESULTS

Thirty-six subjects had DN and 84 did not. Subjects with DN received higher insulin doses (57.6 +/- 16.7 vs. 49.2 +/- 15.0 IU/day; P = 0.008) and had higher WHR (0.85 +/- 0.07 vs. 0.81 +/- 0.10; P = 0.007) and HbA1c values (8.5 (7.6-9.6) vs. 7.7 (7.3-8.9)%; P = 0.049) than subjects without DN. They also had higher values of sTNFR1 (2.42 +/- 0.60 vs. 1.96 +/- 0.66 microg/l; P = 0.001) and sTNFR2 (4.73 +/- 1.33 vs. 4.14 +/- 1.09 microg/l; P = 0.015), and were more insulin resistant (eGDR values: 7.28 (5.83-8.03) vs. 8.30 (7.17-9.03) mg kg(-1) min(-1); P = 0.003). The relationship between DN and either sTNFR1 or sTNFR2 remained essentially unchanged after adjusting for several confounders, including glycaemic control, WHR, lipid profile, blood pressure and other microvascular complications (OR for sTNFR1: 2.592 (1.222-5.498), P = 0.013; OR for sTNFR2: 2.124 (1.258-3.587), P = 0.005).

CONCLUSIONS

The activity of the TNF-alpha system is increased in subjects with type 1 diabetes mellitus and diabetic neuropathy, regardless of their glycaemic control and cardiovascular risk factors associated with insulin resistance. These results suggest that TNF-alpha may play a pathogenic role in the development of diabetic neuropathy.

Tumour necrosis factor receptors (TNFRs) in Type 2 diabetes. Analysis of soluble plasma fractions and genetic variations of TNFR2 gene in a case-control study

AIMS

We have studied the relationships between soluble fractions of tumour necrosis factor receptors (sTNFR1 and sTNFR2) in Type 2 diabetes (DM2) and its chronic microvascular complications. Likewise, we have analysed the genetic susceptibility of 196T > G exon6/CA-repeat intron 4 mutations in the TNFR2 gene in this population.

METHODS

A case-control study was conducted to examine the role of sTNFRs in 345 DM2 patients and 173 healthy subjects. The mutations were studied in all healthy subjects and in a subset of 232 patients.

RESULTS

sTNFRs levels were similar in healthy and DM2 patients. A positive correlation between age and both sTNFRs was observed in healthy subjects. In DM2 patients, sTNFR1 showed a positive correlation with age, systolic blood pressure and leptin levels (r = 0.53, P < 0.0001; r = 0.28, P = 0.005; r = 0.46, P < 0.0001, respectively) and sTNFR2 was positively correlated with age, triglycerides and leptin levels (r = 0.34, P < 0.0001; r = 0.21, P < 0.0001; r = 0.28, P = 0.002, respectively). Patients with micro- or macroalbuminuria showed higher plasma levels of sTNFR1 and sTNFR2 than normoalbuminuric patients, after adjusting for confounding variables (B = 0.85, P = 0.022, 95% CI: 0.12-1.58 for sTNFR1 and B = 1.50, P < 0.001, 95% CI: 0.67-2.33 for sTNFR2). In DM2 patients, TT-exon 6 homozygous showed lower levels of sTNFR1 [2,4 (1.1) vs. 3.4 (1.2) ng/ml], and the CA273-allele tracked with elevated plasma HDL-cholesterol [1.8 (0.7), 1.4 (0.3) and 1.3 (0.3) mm, for CA273/273, CA273/- and CA-/-, respectively]. No association was seen with other analysed variables.

CONCLUSIONS

Our findings suggest that chronic TNF activation may have some pathogenic role in diabetic nephropathy in DM2 patients. Genetic variations in exon 6/intron 4 of the TNFR2 gene do not predispose to a major risk for DM2 or its microvascular complications.

Smoking, fat mass and activation of the tumor necrosis factor-alpha pathway

OBJECTIVE

Obesity may be associated with increased markers of inflammation that could be triggered by metabolic, physical, infectious or environmental processes. As smoking significantly increases cytokine production, we aimed to study how smoking influences the relationship between fat mass and soluble tumor necrosis factor-alpha (TNF-alpha) receptors 1 and 2 (sTNFR1 and sTNFR2).

DESIGN

Cross-sectional, clinical observational study.

SUBJECTS

A total of 133 healthy men (age: 27-53 y, body mass index (BMI): 24-30.2 kg/m(2)), 80 of whom were never-smokers and 53 smokers, matched for age, BMI and waist-to-hip ratio.

MEASUREMENTS

Circulating soluble fractions of the TNF-alpha receptors sTNFR1 and sTNFR2 were measured to study their relationship with fat mass (bioelectric impedance).

RESULTS

Smokers had significantly lower fat mass, lower fasting glucose, insulin and leptin concentrations than nonsmokers. Despite lower fat mass and insulin, smokers showed significantly increased circulating sTNFR2 levels (3.7+/-0.8 vs 3.4+/-0.7 ng/ml, P=0.03). The slopes of the relationships between sTNFR1 and fat mass, and between sTNFR2 and fat mass, were significantly steeper in smokers than in nonsmokers. In a stepwise multiple linear regression analysis, both fat mass (P<0.00001) and smoking (P=0.025) independently contributed to 13% of sTNFR1 variance and to 4% of sTNFR2 variance (P=0.03).

CONCLUSION

Both fat mass and smoking are related to increased activity of the TNF-alpha axis.

Lower rate of tumor necrosis factor-alpha -863A allele and higher concentration of tumor necrosis factor-alpha receptor 2 in first-degree relatives of subjects with type 2 diabetes

Allelic variants of the tumor necrosis factor-alpha (TNF-alpha) gene seem to contribute to insulin resistance increasing the transcription rate of TNF-alpha. The TNF-alpha -863A allele is associated with a lower expression of TNF-alpha gene and less secretion of the cytokine. To investigate whether an abnormal TNF-alpha system regulation may contribute to early impairment of insulin action in first-degree relatives of patients with type 2 diabetes mellitus (DM), we studied the TNF-alpha -863C/A polymorphism and the soluble fraction of TNF-alpha receptor-2 (sTNFR2) concentration in these subjects in comparison to a control group. A total of 52% of subjects in the relatives' group showed an abnormal oral glucose tolerance (either as impaired glucose tolerance [IGT] or diabetes) and had more features of the insulin resistance syndrome, despite showing similar body composition as controls. The plasma concentration of the sTNFR2 was higher and insulin sensitivity (%S) was lower in the relatives' group than in the controls. Likewise, the TNF-alpha -863A allele was more commonly detected in the control group (10 of 41) than in the relative's group (2 of 36, P =.029). In a multivariate linear regression analysis, neither TNF-alpha -863A allele nor sTNFR2 independently determined %S. Only body mass index (BMI) and the presence of a positive family history of DM were independent determinants of insulin resistance. In summary, our study showed a lower rate of TNF-alpha -863A allele and higher concentrations of sTNFR2 in first-degree relatives of DM subjects. These findings could be included among the genetic, metabolic, and clinical heterogeneity that characterizes the pathophysiology of DM. The presence of abnormalities in the TNF-alpha pathway could predispose to the development of DM in subjects at risk for the disease.

Bone mineral mass is associated with interleukin 1 receptor autoantigen and TNF-alpha gene polymorphisms in post-menopausal Mediterranean women

Bone mass is known to be under genetic control. Interleukin-1 (IL-1), interleukin-6 (IL-6) and TNF-alpha are strong inductors of bone resorption. The estrogenic deficiency that occurs during menopause leads to an increase in the production of these cytokines. We analyzed the genetic susceptibility of several polymorphisms of the interleukin-1 receptor antagonist (IL-1ra), IL-6 and TNF-alpha genes in lumbar spine and hip bone mass in a sample of post-menopausal Caucasian Mediterranean women with osteoporosis. 104 post-menopausal osteoporotic women (58.6+/-4.8 yr) and 51 post-menopausal women without osteoporosis as the control group (57.2+/-4.5 yr) were studied. The osteoporotic group was in turn sub-classified into severe and non-severe osteoporosis. The variable number of tandem repeats IL1-ra, IL-6 SfaNI and TNF-alpha NcoI genetic polymorphisms were studied. Biochemical markers of bone turnover were measured in blood and urine. Women carrying the A2 allele (A2+) of the IL-1ra gene showed greater BMD in the lumbar spine (p=0.02) and hip (p=0.006), compared to those not carrying the allele (A2-). The IL-6 polymorphism studied in its 5' flanking region did not show any association with BMD values. The TNF-alpha gene G allele was associated with a greater bone mass in the non-severe osteoporotic subgroup, both in the lumbar spine (p=0.0007) and in the hip (p=0.02). Likewise, genotype combination A2+GG was associated to a greater hip BMD at the femoral neck and Ward triangle levels (p=0.02). We conclude that both IL-1ra and TNF-alpha can be candidate loci to be studied in the susceptibility to develop post-menopausal osteoporosis.

Circulating interleukin 6 levels, blood pressure, and insulin sensitivity in apparently healthy men and women

There is increasing evidence that systemic inflammation and insulin resistance constitute interrelated events that contribute to atherosclerosis. We studied the effect of the association between circulating interleukin 6 (IL-6) levels, one of the major mediators of inflammation, and C-reactive protein on insulin resistance and blood pressure in 228 healthy volunteers. The plasma IL-6 concentration was significantly and similarly associated with systolic (SBP) and diastolic (DBP) blood pressure, fasting insulin, and the fasting insulin resistance index (FIRI) in all subjects. When smokers were excluded from the analysis, plasma IL-6 levels correlated with percent fat mass (r = 0.19; P = 0.02), absolute fat mass (r = 0.17; P = 0.03), SBP, DBP, fasting insulin levels, and FIRI. The latter associations persisted after controlling for body mass index (r = 0.15 and r = 0.19; P = 0.02 and P: = 0.0004 for SBP and DBP, respectively; r = 0.24 and r = 0.19, P = 0.004 and P = 0.03, for fasting insulin and FIRI, respectively). Gender and smoking status significantly influenced the results. Although IL-6 levels were significantly associated with fasting insulin and FIRI in men, these significant correlations were not observed in women. Conversely, although IL-6 levels were significantly associated with SBP and DBP in women, these coefficients were not statistically significant in men. All of these associations were lost among smokers and remained significant in nonsmokers. As IL-6 is the major mediator of the acute phase response by hepatocytes and induces the synthesis of C-reactive protein (CRP), we also controlled for the latter. Serum CRP levels correlated significantly with IL-6 in all the subjects, but mainly in nonsmokers and men. Of note was that this significant relationship was lost among smokers. CRP was associated with fasting insulin (r = 0.28; P < 0.0001) and FIRI (r = 0.25; P < 0.0001), but not with SBP or DBP (P = NS), in all subjects. Unlike IL-6, the associations between CRP and these parameters were similar in men and women and in smokers and nonsmokers. For insulin and FIRI they were stronger in women and in nonsmokers. CPR significantly correlated with the WHR only in men (r = 0.22; P = 0.01). Using multiple linear regression in a stepwise manner to predict circulating IL-6 levels, smoking status (P = 0.0059) and FIRI (P = 0.03), but not fat mass or SBP, independently contributed to 11% of its variance in men. When CRP was introduced into the model, the latter (P < 0.0001) and smoking status (P = 0.02), but not FIRI, fat mass, or SBP, contributed to 33% of the variance in IL-6 levels. In women, only SBP (P = 0.04) contributed to 5% of its variance. When CRP was introduced into the model, again only SBP (P = 0.01) contributed to 10% of the variance in IL-6 levels. In 25 of these subjects, insulin sensitivity was determined using the frequently sampled iv glucose tolerance test with minimal model analysis, and circulating IL-6 levels were strongly associated with the insulin sensitivity index (r = -0.65; P < 0.0001). Again, this relationship was even stronger in men (r = -0.75; P < 0.001) and was not significant in women (r = -0.26; P = NS). In all of these subjects, only insulin sensitivity (P = 0.0037), not fat mass, contributed to 21% of the variance of IL-6 levels in a multiple linear regression analysis. In summary, circulating IL-6 levels, by inducing either hypertension in women or insulin resistance in men, constitute a significant proatherogenic cytokine. The mechanisms of these associations should be further investigated.

Circulating interleukin 6 levels, blood pressure, and insulin sensitivity in apparently healthy men and women

There is increasing evidence that systemic inflammation and insulin resistance constitute interrelated events that contribute to atherosclerosis. We studied the effect of the association between circulating interleukin 6 (IL-6) levels, one of the major mediators of inflammation, and C-reactive protein on insulin resistance and blood pressure in 228 healthy volunteers. The plasma IL-6 concentration was significantly and similarly associated with systolic (SBP) and diastolic (DBP) blood pressure, fasting insulin, and the fasting insulin resistance index (FIRI) in all subjects. When smokers were excluded from the analysis, plasma IL-6 levels correlated with percent fat mass (r = 0.19; P = 0.02), absolute fat mass (r = 0.17; P = 0.03), SBP, DBP, fasting insulin levels, and FIRI. The latter associations persisted after controlling for body mass index (r = 0.15 and r = 0.19; P = 0.02 and P: = 0.0004 for SBP and DBP, respectively; r = 0.24 and r = 0.19, P = 0.004 and P = 0.03, for fasting insulin and FIRI, respectively). Gender and smoking status significantly influenced the results. Although IL-6 levels were significantly associated with fasting insulin and FIRI in men, these significant correlations were not observed in women. Conversely, although IL-6 levels were significantly associated with SBP and DBP in women, these coefficients were not statistically significant in men. All of these associations were lost among smokers and remained significant in nonsmokers. As IL-6 is the major mediator of the acute phase response by hepatocytes and induces the synthesis of C-reactive protein (CRP), we also controlled for the latter. Serum CRP levels correlated significantly with IL-6 in all the subjects, but mainly in nonsmokers and men. Of note was that this significant relationship was lost among smokers. CRP was associated with fasting insulin (r = 0.28; P < 0.0001) and FIRI (r = 0.25; P < 0.0001), but not with SBP or DBP (P = NS), in all subjects. Unlike IL-6, the associations between CRP and these parameters were similar in men and women and in smokers and nonsmokers. For insulin and FIRI they were stronger in women and in nonsmokers. CPR significantly correlated with the WHR only in men (r = 0.22; P = 0.01). Using multiple linear regression in a stepwise manner to predict circulating IL-6 levels, smoking status (P = 0.0059) and FIRI (P = 0.03), but not fat mass or SBP, independently contributed to 11% of its variance in men. When CRP was introduced into the model, the latter (P < 0.0001) and smoking status (P = 0.02), but not FIRI, fat mass, or SBP, contributed to 33% of the variance in IL-6 levels. In women, only SBP (P = 0.04) contributed to 5% of its variance. When CRP was introduced into the model, again only SBP (P = 0.01) contributed to 10% of the variance in IL-6 levels. In 25 of these subjects, insulin sensitivity was determined using the frequently sampled iv glucose tolerance test with minimal model analysis, and circulating IL-6 levels were strongly associated with the insulin sensitivity index (r = -0.65; P < 0.0001). Again, this relationship was even stronger in men (r = -0.75; P < 0.001) and was not significant in women (r = -0.26; P = NS). In all of these subjects, only insulin sensitivity (P = 0.0037), not fat mass, contributed to 21% of the variance of IL-6 levels in a multiple linear regression analysis. In summary, circulating IL-6 levels, by inducing either hypertension in women or insulin resistance in men, constitute a significant proatherogenic cytokine. The mechanisms of these associations should be further investigated.

Polymorphism of the tumor necrosis factor-alpha receptor 2 gene is associated with obesity, leptin levels, and insulin resistance in young subjects and diet-treated type 2 diabetic patients

OBJECTIVE

Mice lacking the tumor necrosis factor-alpha receptor 2 (TNFR2) gene fed a high-fat diet gain less weight and display reduced leptin and insulin levels. In humans, plasma levels of the soluble fraction of TNFR2 (sTNFR2) circulate in proportion to the degree of insulin resistance. The purpose of this study was to evaluate a polymorphism in the 3' untranslated region of the TNFR2 gene on chromosome 1 in relation to BMI, leptin levels, and insulin resistance.

RESEARCH DESIGN AND METHODS

Using single-strand conformation polymorphism, the polymorphism was analyzed in 107 nondiabetic subjects (60 women, 47 men) and in 110 consecutive patients with type 2 diabetes (79 women, 31 men). In a subset of 33 healthy subjects, insulin sensitivity (minimal model analysis) was also evaluated.

RESULTS

Four alleles of the TNFR2 gene were identified (A1, A2, A3, and A4). BMI and serum leptin levels were significantly increased in young carriers of the A2 allele. Plasma sTNFR2 levels were similar among the different TNFR2 gene variants. However, in subjects who did not carry the A2 allele, in young subjects, and in women, plasma sTNFR2 levels were proportional to BMI and leptin levels. In the study sample, carriers of the A2 allele (n = 18) showed significantly increased BMI, fat mass, waist-to-hip ratio, serum total and VLDL triglyceride levels, and leptin levels and had a lower insulin sensitivity index than noncarriers of the A2 variant (n = 15). The frequency of the different alleles among diabetic subjects was similar to that in the control population. However, diet-treated diabetic subjects (n = 49) who were carriers of the A2 allele exhibited significantly higher BMI and leptin levels than diet-treated noncarriers of the A2 allele.

CONCLUSIONS

The presence of the A2 allele in the TNFR2 gene may predispose subjects to obesity and higher leptin levels, which may in turn predispose them to insulin resistance or vice versa. The TNFR2 gene may be involved in weight-control mechanisms.

Left ventricular hypertrophy in hypertensive patients with autosomal dominant polycystic kidney disease: influence of blood pressure and humoral and neurohormonal factors

Left ventricular hypertrophy (LVH) is a common finding in hypertensive autosomal dominant polycystic kidney disease (ADPKD) patients. There are few studies on the influence of blood pressure (BP) and nonhemodynamic factors on LVH in these patients. The aim of this study was to evaluate the relationship between BP, humoral and neurohormonal factors and left ventricular mass (LVM) in hypertensive ADPKD patients. In 20 hypertensive ADPKD patients, ambulatory BP was monitored for 24 h, left ventricular dimensions were estimated by echocardiography, and plasma renin activity (PRA), plasma noradrenaline (NA), angiotensin II (Ang II), aldosterone, atrial natriuretic peptide (ANP) and insulin-like growth factor I (IGF-I) were also determined. Twenty age- and sex-matched essential hypertensive subjects served as controls. Ambulatory BP and LVM index were similar in the two groups, although male ADPKD patients had higher LVM indices than their matched controls. Eight ADPKD patients (40%) and 6 essential hypertensives (30%) showed LVH. PRA, Ang II, aldosterone, ANP and IGF-I levels were similar in the two groups, but plasma NA levels were higher in ADPKD patients than in controls (281 +/- 158 vs. 160 +/- 62 pg/ml, p = 0.004). ADPKD patients with LVH did not differ from those without LVH with regard to humoral and neurohormonal parameters, but had higher ambulatory BP levels. In ADPKD patients, correlation analysis revealed a significant association between LVM index and 24-hour systolic and diastolic BP, but not with any of the hormonal factors evaluated. On multiple regression analysis, 24-hour diastolic BP was the only independent variable linked to LVM index. In conclusion, ambulatory BP is one of the most important determinants of LVM in hypertensive ADPKD patients. Further studies are warranted to elucidate the role of nonhemodynamic factors in the pathogenesis of LVH in this population.

Genetic polymorphism of alcohol dehydrogenase in europeans: the ADH2*2 allele decreases the risk for alcoholism and is associated with ADH3*1

Polymorphism at the ADH2 and ADH3 loci of alcohol dehydrogenase (ADH) has been shown to have an effect on the predisposition to alcoholism in Asian individuals. However, the results are not conclusive for white individuals. We have analyzed the ADH genotype of 876 white individuals from Spain (n = 251), France (n = 160), Germany (n = 184), Sweden (n = 88), and Poland (n = 193). Peripheral blood samples from healthy controls and groups of patients with viral cirrhosis and alcohol-induced cirrhosis, as well as alcoholics with no liver disease, were collected on filter paper. Genotyping of the ADH2 and ADH3 loci was performed using polymerase chain reaction-restriction fragment length polymorphism methods on white cell DNA. In healthy controls, ADH2*2 frequencies ranged from 0% (France) to 5.4% (Spain), whereas ADH3*1 frequencies ranged from 47. 6% (Germany) to 62.5% (Sweden). Statistically significant differences were not found, however, between controls from different countries, nor between patients with alcoholism and/or liver disease. When all individuals were grouped in nonalcoholics (n = 451) and alcoholics (n = 425), ADH2*2 frequency was higher in nonalcoholics (3.8%) than in alcoholics (1.3%) (P =.0016), whereas the ADH3 alleles did not show differences. Linkage disequilibrium was found between ADH2 and ADH3, resulting in an association of the alleles ADH2*2 and ADH3*1, both coding for the most active enzymatic forms. In conclusion, the ADH2*2 allele decreases the risk for alcoholism, whereas the ADH2*2 and ADH3*1 alleles are found to be associated in the European population.

Interleukin-6 gene polymorphism and insulin sensitivity

Type 2 diabetes and the insulin resistance syndrome have been hypothesized to constitute manifestations of an ongoing acute-phase response. We aimed to study an interleukin-6 (IL-6) gene polymorphism in relation to insulin sensitivity (IL-6 is the main cytokine involved in an acute-phase response). Subjects homozygous for the C allele at position -174 of the IL-6 gene (SfaNI genotype), associated to lower plasma IL-6 levels, showed significantly lower integrated area under the curve of serum glucose concentrations (AUCglucose) after an oral glucose tolerance test, lower blood glycosylated hemoglobin, lower fasting insulin levels, lower total and differential white blood cell count (a putative marker of peripheral IL-6 action), and an increased insulin sensitivity index than carriers of the G allele, despite similar age and body composition. A gene dosage effect was especially remarkable for AUCglucose (6.4 vs. 9.3 vs. 9.7 mmol/l in C/C, C/G, and G/G individuals, respectively). The serum concentration of fully glycosylated cortisol binding globulin (another marker of IL-6 action), suggested by concanavalin A adsorption, was lower in C/C subjects than in G/G individuals (32.6+/-2.9 vs. 37.6+/-4.6 mg/l, P = 0.03). In summary, a polymorphism of the IL-6 gene influences the relationship among insulin sensitivity, postload glucose levels, and peripheral white blood cell count.

Interleukin-6 gene polymorphism and lipid abnormalities in healthy subjects

Several lines of evidence indicate that interleukin-6 (IL-6) is involved not only in the hepatic acute phase response but also in adipose tissue metabolism, lipoprotein lipase activity, and hepatic triglyceride secretion. A polymorphism in the IL-6 gene, associated with differences in IL-6 transcription rate, has been recently described. We aimed to study whether this IL-6 gene polymorphism leads to differences in fasting and postglucose load plasma lipids in healthy subjects. Subjects with G at position -174 of the IL-6 gene were similar in age, sex, body mass index, and waist to hip ratio in comparison with carriers of the C allele. However, G carriers showed almost twice plasma triglycerides (1.5 +/- 0.9 vs. 0.90 +/- 0.37 mmol/L; P = 0.01), very low-density lipoprotein (VLDL)-triglycerides (0.97 +/- 0.69 vs. 0.42 +/- 0.2 mmol/L; P = 0.002), higher fasting (881 vs. 458 micromol/L; P = 0.01), and postglucose load free fatty acids (299 vs. 90.5 micromol/L; P = 0.03), slightly lower high-density lipoprotein-2 cholesterol (0.25 +/- 0.14 vs. 0.39 +/- 0.26 mmol/L; P = 0.058), and similar cholesterol and LDL-cholesterol levels than carriers of the C allele. Serum IL-6 levels correlated positively with fasting triglycerides, VLDL-triglycerides, and postload free fatty acids (r = 0.61, 0.65 and 0.60, respectively; P < 0.001) and negatively with high-density lipoprotein-cholesterol (r = -0.42, P < 0.05). A tendency toward higher serum IL-6 levels was observed among G carriers (9.9 +/- 6.9 vs. 6.85 +/- 1.7 pg/mL; P = 0.09). The -174G construct was recently reported to show higher expression of IL-6 in He La cells and was associated with higher plasma IL-6 levels than the -174C allele. Thus, the results of the present study suggest that subjects with the G allele, associated to higher IL-6 secretion, are prone to lipid abnormalities. Whether this polymorphism contributes to lipid alterations associated with other metabolic disorders awaits additional studies.

Tumor necrosis factor system activity is associated with insulin resistance and dyslipidemia in myotonic dystrophy

Myotonic dystrophy (MyD) is a multisystem autosomal dominant disorder associated with progressive muscle wasting and weakness. The striking metabolic abnormality in MyD is insulin resistance. The mechanism by which target tissues are insensitive to insulin action remains uncertain. In a recent study, plasma soluble tumor necrosis factor receptor (sTNFR)2 levels were found to be associated with muscle tissue mass and insulin resistance. Given these associations, we speculated that disorders of the muscle cell membrane could lead simultaneously to insulin insensitivity and sTNFR2 leakage in MyD. To test this hypothesis, we measured the levels of circulating sTNFR1 and sTNFR2 and insulin resistance in MyD patients. We studied 22 MyD patients and 24 age-, BMI-, and fat mass-matched control subjects. Both MyD men and women showed higher plasma insulin levels in the presence of comparable glucose concentrations than did control subjects. sTNFR2, but not sTNFR1, levels were approximately 1.5-fold higher in MyD patients. In parallel with these findings, the fasting insulin resistance index (FIRI) was also higher in MyD patients. In fact, in the whole population, fasting insulin and FIRI strongly correlated with sTNFR2 in both men (r = 0.77 and r = 0.81, P<0.0001, respectively) and women (r = 0.67 and r = 0.64, P = 0.001, respectively). sTNFR2 levels were also associated with the insulin sensitivity index (S(I)), calculated from an oral glucose tolerance test (OGTT) according to the method by Cederholm and Wibell (r = -0.43, P = 0.006). We constructed a multiple linear regression to predict FIRI, with BMI, waist-to-hip ratio, and sTNFR2 as independent variables. In this model, both BMI (P = 0.0014) and sTNFR2 (P = 0.0048) levels contributed independently to 46% of the variance of FIRI. In another model, in which FIRI was substituted for S(I) from the OGTT, both BMI (P = 0.0001) and sTNFR2 (P = 0.04) levels contributed independently to 48% of the variance of S(I) from the OGTT. Plasma cholesterol and triglyceride concentrations were significantly increased in MyD patients. sTNFR1 and sTNFR2 levels were found to be strongly associated with plasma cholesterol, LDL cholesterol, and triglycerides. sTNFR1 and sTNFR2 also correlated with serum creatine kinase activity in MyD patients (r = 0.57, P = 0.006; r = 0.75, P<0.0001, respectively). In conclusion, here we describe, for the first time to our knowledge, a relationship between insulin action and plasma sTNFR2 concentration in MyD patients. We have also found increased concentrations of plasma triglycerides and cholesterol levels in parallel with sTNFR1 and sTNFR2 concentrations in MyD patients. We speculate that the latter associations are dependent on, and secondary to, increased tumor necrosis factor (TNF)-alpha action. Whether TNF action is implicated in the pathogenesis of MyD or is a simple marker of disease activity awaits further studies.

Genetic heterogeneity within ulcerative colitis determined by an interleukin-1 receptor antagonist gene polymorphism and antineutrophil cytoplasmic antibodies

BACKGROUND

Although there is strong evidence implicating genetic predisposition in the pathogenesis of the chronic inflammatory bowel diseases, the number and identity of susceptibility genes remain uncertain. Cytokine genes are tentative candidate loci, but data regarding association studies in different populations are conflicting.

AIMS

To determine potential associations of interleukin-1 receptor antagonist (IL-1ra), tumour necrosis factor alpha (TNF alpha), and tumour necrosis factor beta (TNF beta) gene polymorphisms with ulcerative colitis or subsets of ulcerative colitis in a Spanish population.

METHODS

Genotyping for IL-1ra, TNF alpha and TNF beta gene polymorphisms was performed by the polymerase chain reaction in 95 patients with ulcerative colitis and 74 healthy controls. A variable number of tandem repeats (VNTR) in the IL-1ra gene, and a single base pair polymorphism in the TNF alpha gene promoter region (-308) and in the first intron of the TNF beta gene were analysed. Anti-neutrophil cytoplasmic antibodies (ANCA) were detected using an indirect immunofluorescence assay.

RESULTS

There were no significant differences between ulcerative colitis patients and controls in either polymorphism analysed, nor between ulcerative colitis subgroups as a function of the clinical disease pattern. However, when stratified by their ANCA status, perinuclear ANCA (p-ANCA) ulcerative colitis showed an increased frequency of the genotype 1,2 of the IL-1ra gene compared with ANCA-negative ulcerative colitis (52% versus 28%; P = 0.02, Pcorr = 0.1). Furthermore, p-ANCA ulcerative colitis had a statistically significant increase of this genotype compared with cytoplasmic ANCA (c-ANCA)/ANCA-negative ulcerative colitis (52% versus 26.5%; P = 0.01, Pcorr = 0.05).

CONCLUSIONS

In the Spanish population studied, the polymorphisms analysed in the IL-1ra, TNF alpha and TNF beta genes are unlikely to be important in the overall susceptibility to ulcerative colitis. However, the combination of a subclinical (p-ANCA) and a genetic (IL-1ra gene) marker identified a distinct ulcerative colitis subgroup (p-ANCA; IL-1ra genotype 1,2). These findings provide further evidence of genetic heterogeneity within ulcerative colitis, and support the concept that ANCA may represent a subclinical marker of genetic heterogeneity.

Beta 3-adrenoreceptor gene polymorphism and leptin. Lack of relationship in type 2 diabetic patients

INTRODUCTION

The beta 3-Adrenergic receptor (beta 3AR) and leptin are molecules involved in the regulation of energy balance. Recently, a mutation in the beta 3AR gene (Trp64Arg) has been reported to be associated with features of insulin resistance, weight gain and early onset of Type 2 Diabetes Mellitus. The aim of this study was to determine the frequency and clinical characteristics of the Trp64Arg mutation in the beta 3AR gene in Type 2 diabetic patients, its relationship with leptin levels, and its role in microangiopathic complications.

SUBJECTS AND METHODS

187 Type 2 diabetic patients and 100 unrelated non-diabetic subjects were studied. There was no difference between the diabetic and nondiabetic subjects in the frequency of the Trp64 and Arg64 alleles (92.5% vs. 92.3% and 7.5% vs. 7.7%, respectively). Type 2 diabetic patients were divided into two groups according to the presence (n = 27) or absence of the mutation (n = 160).

RESULTS

Mutation of the beta 3AR gene was not associated with any differences either in the clinical and metabolic parameters or microangiopathic complications. Type 2 diabetic patients carrying the Arg64 allele tended to have a lower diabetes duration, but this was not statistically significant. Plasma leptin levels were not different according to the beta 3AR genotype.

CONCLUSIONS

The Trp64Arg mutation is not a major determinant of Type 2 diabetes and its microangiopathic complications. Moreover, this mutation was not clinically relevant in leptin regulation.

Plasma levels of the soluble fraction of tumor necrosis factor receptor 2 and insulin resistance

Recent studies have shown that the tumor necrosis factor (TNF) system is implicated in the insulin resistance of human obesity. Plasma concentrations of the soluble fraction of the TNF receptors 1 and 2 (sTNFR1 and sTNFR2) are thought to reflect the degree of activation of the TNF system. The purpose of this study was to explore whether this activation, as measured by the levels of circulating sTNFR1 and sTNFR2, is associated with insulin resistance. A total of 19 men (mean age 36.2 +/- 1.9; BMI 28.8 +/- 1.2, range 22.2-35.7) and 17 premenopausal women (age 34.9 +/- 1.4; BMI 28.1 +/- 0.8, range 19-37.9) were studied. Men showed higher levels of plasma sTNFR1 and sTNFR2 than women. However, obese men showed increased levels of sTNFR2 but similar levels of sTNFR1 in comparison with obese women. In fact, sTNFR2 levels correlated with BMI (r = 0.50, P = 0.002), fat-free mass (FFM) (r = 0.61, P < 0.0001), and waist-to-hip ratio (WHR) (r = 0.39, P = 0.02), but not with fat mass or percent fat mass. sTNFR2 levels correlated with basal glucose levels (r = 0.45, P = 0.007), area under the curve (AUC) for glucose during an oral glucose tolerance test (r = 0.42, P = 0.013), and with the quotient AUC glucose/log AUC insulin (r = 0.41, P = 0.015). sTNFR2 also correlated negatively with insulin sensitivity (S(I)), evaluated using the frequently sampled intravenous glucose tolerance test with minimal model analysis (r = -0.38, P = 0.02). Plasma sTNFR1 levels were not associated with any of these variables. Because WHR influenced both S(I) and sTNFR2 levels, we constructed a multiple linear regression to predict S(I), with WHR and sTNFR2 as independent variables. In this model, both WHR (P = 0.0078) and sTNFR2 levels (P = 0.025) contributed to 47% of the variance in S(I). In parallel with higher FFM, lean and obese men showed a lower S(I) (2.9 +/- 0.9 vs. 5.2 +/- 1.3 min(-1) x mU x l(-1), P = 0.001; and 1.15 +/- 1.1 vs. 1.8 +/- 0.8 min(-1) x mU x l(-1), P = 0.035, respectively) and higher sTNFR2 levels in comparison with lean and obese women, respectively. After controlling for FFM, the correlation between S(I) and sTNFR2 levels disappeared, indicating that FFM was significantly influencing these associations. In summary, plasma sTNFR2 levels, but not sTNFR1, were proportional to BMI, WHR, FFM (a well-known confounder in the evaluation of insulin sensitivity), basal and postload glucose levels, and insulin resistance. These findings support TNF-alpha as a system regulating insulin action in human obesity.

GLUT1 gene polymorphism in non-insulin-dependent diabetes mellitus: genetic susceptibility relationship with cardiovascular risk factors and microangiopathic complications in a Mediterranean population

OBJECTIVE

It has been suggested that the polymorphic variation of GLUT1 glucose transporter may contribute to genetic susceptibility to type 2 diabetes in some populations. We have evaluated the GLUT1-XbaI polymorphism in an association study of a Caucasian Mediterranean population and its role in the susceptibility to displaying either microangiopathic complications or any of the risk factors associated with type 2 diabetes.

RESEARCH DESIGN AND METHODS

A total of 193 type 2 diabetic patients (104 women and 89 men, 31-82 years of age, diabetes duration 13.2 +/- 6.2 years) and 90 healthy subjects (48 women and 42 men, 20-72 years of age) were recruited for the association study. For the evaluation of nephropathy and retinopathy, type 2 diabetic patients were matched with those not having microangiopathic complications.

RESULTS

Genotypic or allelic frequencies did not differ significantly between controls and type 2 diabetic patients. Regarding the distribution of clinical or metabolic parameters according to GLUT1 genotype, patients with X1X1 genotype tended to have higher diastolic blood pressure levels compared with the remaining genotypes (P = 0.008). There were no differences in genotypic or allelic distribution among patients for either the presence or absence of retinopathy or nephropathy.

CONCLUSIONS

We conclude that GLUT1 loci did not contribute significantly to type 2 diabetes in this cohort and is not a determinant for cardiovascular risk factors or chronic microangiopathic complications associated with type 2 diabetes. The weak association with diastolic hypertension must be confirmed in other populations.

Influence of chronic alcohol abuse and liver disease on hepatic aldehyde dehydrogenase activity

Alcohol metabolism results in the production of acetaldehyde, a compound that is much more toxic than ethanol itself. Hepatic aldehyde dehydrogenase (ALDH) is the main enzymatic system responsible for acetaldehyde clearance from the hepatocyte. The objective of this study was to determine the modifications in ALDH activity due to chronic alcohol abuse and liver disease. ALDH activity was determined in samples of liver tissue from 69 alcoholic and 82 nonalcoholic subjects, with and without liver disease. According to the results of liver pathology examination, alcoholic patients were classified into the following groups: controls, with no liver disease (group 1), noncirrhotic liver disease patients (group 2), and cirrhotics (group 3). Nonalcoholic subjects were categorized, using the same criteria, into groups 4, 5, and 6, respectively. ALDH activity was determined spectrophotometrically at two substrate concentrations: 18 mM for total activity and 180 microM for low Km activity. High Km activity was calculated by subtracting the low Km activity value from that of total ALDH activity. Results obtained in each group were expressed as the mean +/- SD of mU of g of wet weight. There were no significant differences when the total ALDH activity from the alcoholic and the nonalcoholic patients with a similar degree of liver pathology were compared: group 1, 1257 +/- 587 vs. group 4, 1328.1 +/- 546.2 (p: NS); group 2, 919.1 +/- 452.4 vs. group 5, 753.5 +/- 412 (p: NS); and group 3, 430.2 +/- 162.4 vs. group 6, 473.2 +/- 225.3 (p: NS). On the other hand, total ALDH activity was significantly lower in cirrhotics than in controls, both among alcoholics (p < 0.01) and among nondrinkers (p < 0.05). The low Km activity was severely reduced in cirrhotics, both alcoholics and nonalcoholics (p < 0.01). High Km activities in cirrhotic patients were low, compared to controls, both in alcoholics and nonalcoholics, although the difference was nonsignificant. The results of the present study suggests that chronic alcohol abuse does not depress ALDH activity. A reduction in the ALDH activity detected in patients with severe liver disease (cirrhotics) was clearly a consequence of liver damage. This reduction was due mainly to a decrease of the low Km ALDH activity, but a trend to a decrease in the high Km ALDH activity was also detected.

Angiotensin I-converting enzyme and angiotensinogen gene polymorphisms in non-insulin-dependent diabetes mellitus. Lack of relationship with diabetic nephropathy and retinopathy in a Caucasian Mediterranean population

Genotypic abnormalities of the renin-angiotensin system have been suggested as a risk factor for the development of microangiopathic complications in diabetic patients. We studied the relationship of either an insertion-deletion polymorphism in the angiotensin-converting enzyme (ACE) gene and the M235T and T174M variant polymorphisms of the angiotensinogen (AGT) gene in non-insulin-dependent diabetes mellitus (NIDDM) patients and its relationship with cardiovascular complications. A total of 193 NIDDM patients (89 men and 104 women aged 59.2 +/- 10.0 years; diabetes duration, 13.2 +/- 6.2 years) and 90 control subjects (42 men and 48 women aged 45.4 +/- 12.6 years) were recruited for the association study. Distribution of the genotype or allelic frequencies for all the studied polymorphisms did not differ significantly between controls and NIDDM patients. ACE and AGT genes did not display any difference in clinical or metabolic parameters according to each gene's genotype for either the control or the NIDDM group. For evaluation of nephropathy and retinopathy, NIDDM patients were matched with subjects not having microangiopathic complications. Thus, a total of 60 patients had diabetic nephropathy and were compared with 100 patients with normoalbuminuria. Sixty-eight NIDDM patients had diabetic retinopathy, and 92 patients presented no signs of retinopathy. There were no differences in genotypic or allelic distribution between NIDDM patients for either the presence or absence of retinopathy or nephropathy. We conclude that the ACE and AGT polymorphisms do not contribute to the genetic susceptibility to diabetic nephropathy and retinopathy in a caucasian Mediterranean population.

The TNF-beta gene Nco I polymorphism is not associated with hypertriglyceridemia or insulin resistance in lean and obese subjects

Interindividual differences in TNF-alpha monocyte responses can be accounted for by genetic polymorphisms at the TNF-beta locus defined by the Nco I restriction enzyme. Higher triglyceride levels in non-insulin-dependent diabetic patients homozygous at the 10.5-kb fragment of the TNF-beta gene have been described. The aim of this study was to investigate whether the Ncol polymorphism of the TNF-beta gene influences the relationship between insulin resistance and triglyceride levels. Thirty-eight healthy volunteers were divided into two groups according to the absence [homozygous for class 1 allele (1/1), n=16] or presence of the class 2 allele [n=22; 19 heterozygous (1/2), and 3 homozygous (2/2)]. Both groups were comparable in sex, age, BMI, waist/hip ratio, fat mass and percentage of body fat as measured by bioelectric impedance, skinfold measurements, and blood pressure (all p>0.05). There were no differences in serum cholesterol (total, or HDL and VLDL fractions) or in total or VLDL triglycerides between the groups (all p>0.05). The insulin sensitivity index (Minimal Model method) was comparable for the two groups. In summary, the 10.5-kb homozygous genotype of the TNF-beta locus does not contribute to differences in triglyceride levels or insulin sensitivity among nondiabetic subjects.

[Apolipoprotein AI-CIII, B, and CII gene polymorphisms in patients with non-insulin dependent diabetes mellitus. Association with hyperlipemia]

BACKGROUND

Dislipidaemia is an usual feature in patients affected by non insulin dependent diabetes mellitus. Several studies show that this disease could be genetically determined. The aim of this study was to ascertain whether any of the genetic polymorphism remaining in three apolipoprotein loci (apolipoprotein AI-CIII, B100 and CII) is related with the presence of dislipidaemia in non insulin dependent diabetes mellitus patients.

PATIENTS AND METHODS

53 non insulin dependent diabetes mellitus patients with less than 5 years evolution and treated only with diet, were included. 86 healthy persons were included as the control group. The lipidic parameters analyzed were: cholesterol, LDL cholesterol, HDL cholesterol, triglycerides, apolipoprotein AI, B and lipoprotein (a). The following polymorphic variants were analyzed: RFLP-Sacl of the apolipoprotein AI-CIII-AIV cluster, RFLP-Xbal of the apolipoprotein B100 region and the RFLP-Taql of the apolipoprotein E-CI-CII cluster.

RESULTS

There were no genetic nor allelic differences in the distribution of the genes, between controls and diabetic patients. Regarding the apolipoprotein CII gen, the diabetic patients with the T2T2 genotype had higher triglyceride levels (p < 0.01) compared with the remaining genotypes and compared with the control group having the same genotype (p < 0.01) matched for sex, age and body mass index. There was no difference in the metabolic parameters' distribution related to the genotypic distribution of the apolipoproteins AI-CIII and B100 genes.

CONCLUSIONS

The apolipoprotein CII can be related with the presence of hypertriglyceridaemia in non insulin dependent diabetes mellitus patients.