Loci of TCF7L2, HHEX and IDE on chromosome 10q and the susceptibility of their genetic polymorphisms to type 2 diabetes.

TCF7L2, HHEX and IDE on chromosome 10q23-25 reside within the linkage region for type 2 diabetes (T2D). Previous studies including ours have demonstrated that genetic polymorphisms in these three loci are associated with T2D, respectively. But, it is unclear whether TCF7L2, independently or interactively with HHEX and IDE, confer the susceptibility to T2D. In the present study, we first replicated genetic association study of the TCF7L2 gene in a Swedish cohort including 528 non-diabetic healthy controls and 243 T2D patients and then evaluated combining effect from common risk polymorphisms in TCF7L2-HHEX-IDE loci. T2D patients were diagnosed in the intermediate study time. To avoid influence from anti-diabetic treatment, baseline data in all T2D patients were used for analysis. We found that SNPs rs7901695, rs4506565, rs7903146 and rs12255372 in the TCF7L2 gene were strongly associated with T2D (p<0.004). In rs7903146, T2D patients carrying genotypes CT or TT had higher fasting plasma glucose (FPG) levels (p=0.042) and lower HOMA-beta index (p=0.015) and BMI (p=0.015) compared to the patients carrying CC genotype. Furthermore, the risk alleles from TCF7L2 rs7903146 polymorphism either with IDE rs2251101 polymorphism (p=0.0257, OR=1.398) or with HHEX rs1544210 polymorphism (p=0.0024, OR=1.514) were significantly associated with T2D. When risk alleles from three loci were combined, the association with T2D remained significant (p=0.0018, OR=1.506). The present study thus provides evidence that TCF7L2, as the main gene, together with HHEX and IDE loci have combining effects on genetic predisposition to T2D.

Genetic variation of the adenylyl cyclase 3 (AC3) locus and its influence on type 2 diabetes and obesity susceptibility in Swedish men.

OBJECTIVE: Our previous study using the Goto-Kakizaki rat implicates that the adenylyl cyclase 3 (AC3) is a candidate gene for genetic study of metabolic disorders. The present study aimed to investigate the susceptibility of genetic variation of the AC3 gene in type 2 diabetes (T2D) patients and obese subjects. SUBJECTS AND METHODS: Variation screening in the putative promoter and validation of single nucleotide polymorphisms (SNPs) covering the AC3 gene were performed. In total, 630 Swedish men, including 243 T2D patients (BMI from 18.4 to 45.6 kg m(-2)), 199 obese subjects with normal glucose tolerance (NGT, BMI> or =30 kg m(-2)) and 188 control subjects (NGT, BMI< or =26 kg m(-2)), were genotyped. RESULTS: A novel variant -17A/T in the promoter was identified, but no significant association of this polymorphism with T2D was found. SNPs rs2033655 C/T and rs1968482 A/G were found to be significantly associated with obesity when T2D patients had BMI> or =30 kg m(-2) (P=0.003 and 0.005). The significance was borderline in T2D patients with BMI<30 kg m(-2) (P=0.051 and 0.084) and disappeared in T2D patients with BMI< or =26 kg m(-2). Importantly, analysis in obese subjects with NGT demonstrated that these two polymorphisms were strongly associated with obesity per se (P=0.028 and 0.003). Furthermore, analyses for diplotypes (haplotypic genotypes) predicted an association with BMI in obese subjects. CONCLUSIONS: The present study provides the first evidence that AC3 polymorphisms confer the risk susceptibility to obesity in Swedish men with and without type 2 diabetes.

Leu7Pro polymorphism in the neuropeptide Y (NPY) gene is associated with impaired glucose tolerance and type 2 diabetes in Swedish men.

The neuropeptide Y (NPY) is a neuropeptide with a role in the regulation of satiety and energy balance of body weight, insulin release, cardiovascular and central endocrine systems. In order to evaluate whether the NPY gene variations contribute to development of type 2 diabetes (T2DM), we have performed a genetic association study for Leu7Pro (T1128 C) polymorphism of the NPY gene in impaired glucose tolerance (IGT) and T2DM. Genotyping experiments for this non-synonymous single nucleotide polymorphism (SNP) in 263 patients with T2DM, 309 subjects with IGT and 469 non-diabetic healthy individuals in Swedish Caucasians were performed by using Dynamic Allele Specific Hybridisation (DASH). We found that the frequencies of the "risk" allele C in the subjects with IGT and the patients with T2DM in Swedish men were 13 % (p = 0.002, OR = 3.70, 1.65 - 8.29 95 % CI) and 10 % (p = 0.007, OR = 4.80, 1.47 - 11.33 95 % CI) respectively, which were significantly higher than the C allele frequency in non-diabetic controls (6 %). Furthermore, we found that the carriers with TC and CC genotypes in the subjects with IGT in Swedish men had significantly higher fasting plasma glucose in comparison with the TT carriers (5.6 +/- 0.7 mmol/l vs. 5.2 +/- 0.7 mmol/l, p = 0.021). The present study thus provides the evidence that Leu7Pro polymorphism in the NPY gene is associated with IGT and T2DM in Swedish men, and indicates that the NPY gene variations contribute to development of T2DM. Questions of gender specificity may be explained by genetic backgrounds, sense of coherence for stress and other factors in environment.

Whole blood chemiluminescence as a systemic inflammatory parameter in asthma.

Blood phagocytes from patients with asthma not treated with antiinflammatory drugs have an increased capacity to produce reactive oxygen metabolites. We studied the phenomenon in a group of patients with asthma receiving inhaled steroids with whole blood chemiluminescence (CL), a simple reactive oxygen metabolite assay suitable for routine use. There was no difference in CL values between patients with stable asthma and no current obstruction (n = 19; mean CL +/- SD = 26.01 +/- 6.51 mV x min) and healthy control subjects (n = 20; mean CL +/- SD = 27.37 +/- 6.15 mV x min), whereas the patients with asthma and current obstruction (n = 27) had significantly higher CL responses (mean CL +/- SD = 41.10 +/- 14.79 mV x min) than both the patients with nonobstructive asthma and the healthy control subjects (p < 0.0005). There was a negative correlation between whole blood CL and the forced expiratory volume in 1 second of the patients with asthma (Spearman's r = -0.47). When the CL values were corrected for the number of phagocytes present in the reactions, the patients with nonobstructive asthma had significantly lower values than the healthy control subjects (p < 0.05). We suggest that the CL values of the patients with nonobstructive asthma reflect the result of effective antiinflammatory treatment and that whole blood CL may be useful as a systemic parameter in the follow-up of the inflammatory process in asthma.

Increased mineral dust-induced production of reactive oxygen species by blood monocytes from patients with malignant diseases.

Mononuclear leukocytes were isolated from the peripheral blood of 15 patients with malignant pulmonary diseases, 17 patients with pulmonary infections, 18 patients with chest film abnormalities of non-malignant, non-infectious etiology, and 15 healthy persons. The cells were exposed to zymosan yeast, BCG vaccine, quartz, or chrysotile asbestos, and the subsequent production of reactive oxygen species (ROS) was measured by luminol-dependent chemiluminescence. All the stimulants caused significantly higher ROS production in the patient groups than in the healthy control group, and the asbestos-induced ROS production was significantly more pronounced in the cancer group than in the two non-cancer patient groups combined. After one-year follow-up, 5 of the 15 cancer patients were alive, and these patients had significantly lower mineral dust-induced ROS responses at the time of diagnosis than were found in the patients who died. This result was verified in a subsequent study comprising 19 patients with malignant pulmonary disorders (6 alive after one year). In conclusion, monocytes from patients with malignant diseases seem to be primed for an increased ROS production, and high ROS responses seem to correlate with a poor one-year survival of the patients.

Increased PMA-induced chemiluminescence from whole blood of patients with bronchial hyperreactivity.

Blood phagocytes from patients with asthma have an increased capacity to produce reactive oxygen metabolites. We studied whether whole blood luminol-dependent chemiluminescence could detect this phenomenon in patients with a normal spirometry but bronchial hyperreactivity as determined with a methacholine bronchial challenge test. Whole blood chemiluminescence, serum eosinophilic cationic protein (ECP), and serum myeloperoxidase (MPO) were determined from 50 patients referred for a methacholine challenge due to prolonged cough and/or dyspnoea. The chemiluminescence results were compared to those from 15 healthy persons. The hyperreactive patients (n = 18) had significantly higher phorbol 12-myristate 13-acetate (PMA)-induced whole blood chemiluminescence values (mean 18.8 mV.min-1; 95% confidence limits (C.L.) 16.3-21.3 mV.min-1) than the normoreactive patients (mean 14.2 mV.min-1; 95% C.L. 13.0-15.5 mV.min-1;) and the healthy controls (mean 12.8 mV.min-1; 95% C.L. 11.7-13.9 mV.min-1). There was no significant difference in PMA-induced chemiluminescence between the normoreactive patients and the controls. The hyperreactive patients had higher serum ECP values than the normoreactive patients, but there was no correlation between whole blood chemiluminescence and serum ECP levels or total eosinophil count. There was no significant difference in monocyte reactive oxygen metabolite production or serum MPO values between the normoreactive and the hyperreactive patients. We suggest that the increased PMA-induced whole blood chemiluminescence in bronchial hyperreactivity is due mainly to an activation of neutrophils, and that the assay might be useful as a systemic inflammatory marker in patients with pulmonary inflammatory processes resulting in bronchial hyperreactivity.

A synergistic interaction between Bacillus Calmette-Guérin (BCG) and NADPH oxidase stimulants on the production of reactive oxygen metabolites by human mononuclear phagocytes.

Bacillus Calmette-Guérin (BCG) was added simultaneously with known NADPH oxidase stimulants to suspensions of human mononuclear leukocytes, and the subsequent production of reactive oxygen metabolites (ROMs) was studied by luminol-dependent chemiluminescence. BCG significantly amplified the ROM responses induced by zymosan, phorbol myristate acetate (PMA), and quartz, but not by concanavalin A and asbestos fibers. The stimulatory effect occurred rapidly when BCG was added to cells already phagocytosing zymosan, and vanished rapidly when extracellular BCG was removed from adherent monocyte cultures by washing prior to the addition of zymosan. The stimulatory effect of BCG could not be reproduced with recombinant interferon-gamma, tuberculin PPD, muramyl dipeptide, nor with the apathogenic Mycobacterium tuberculosis strain RV37. BCG and zymosan or PMA that had been incubated together prior to addition to the mononuclear cell suspensions caused ROM production with faster kinetics than if the reagents were added separately without preincubation. In conclusion, the synergy between BCG and some of the NADPH oxidase stimulants seems to be due to an interaction between BCG and the NADPH oxidase stimulants rather than to an interaction between BCG and the ROM-producing cells. Such interactions between mycobacteria and NADPH oxidase stimulants may be of importance as a factor affecting the individual susceptibility to tissue damage in tuberculosis, for example in silicotuberculosis.