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

Identification of novel biomarkers to monitor β-cell function and enable early detection of type 2 diabetes risk

A decline in β-cell function is a prerequisite for the development of type 2 diabetes, yet the level of β-cell function in individuals at risk of the condition is rarely measured. This is due, in part, to the fact that current methods for assessing β-cell function are inaccurate, prone to error, labor-intensive, or affected by glucose-lowering therapy. The aim of the current study was to identify novel circulating biomarkers to monitor β-cell function and to identify individuals at high risk of developing β-cell dysfunction. In a nested case-control study from the Relationship between Insulin Sensitivity and Cardiovascular disease (RISC) cohort (n = 1157), proteomics and miRNA profiling were performed on fasting plasma samples from 43 individuals who progressed to impaired glucose tolerance (IGT) and 43 controls who maintained normal glucose tolerance (NGT) over three years. Groups were matched at baseline for age, gender, body mass index (BMI), insulin sensitivity (euglycemic clamp) and β-cell glucose sensitivity (mathematical modeling). Proteomic profiling was performed using the SomaLogic platform (Colorado, USA); miRNA expression was performed using a modified RT-PCR protocol (Regulus Therapeutics, California, USA). Results showed differentially expressed proteins and miRNAs including some with known links to type 2 diabetes, such as adiponectin, but also novel biomarkers and pathways. In cross sectional analysis at year 3, the top differentially expressed biomarkers in people with IGT/ reduced β-cell glucose sensitivity were adiponectin, alpha1-antitrypsin (known to regulate adiponectin levels), endocan, miR-181a, miR-342, and miR-323. At baseline, adiponectin, cathepsin D and NCAM.L1 (proteins expressed by pancreatic β-cells) were significantly lower in those that progressed to IGT. Many of the novel prognostic biomarker candidates were within the epithelial-mesenchymal transition (EMT) pathway: for example, Noggin, DLL4 and miR-181a. Further validation studies are required in additional clinical cohorts and in patients with type 2 diabetes, but these results identify novel pathways and biomarkers that may have utility in monitoring β-cell function and/ or predicting future decline, allowing more targeted efforts to prevent and intercept type 2 diabetes.

Obesity-dependent association of TNF-LTA locus with type 2 diabetes in North Indians

Six common genetic variants (rs2229094, rs1041981, rs1800630, rs1800629, rs361525, and rs1800610) in the TNF-LTA locus encoding the pro-inflammatory cytokines tumor necrosis factor-alpha (TNF-alpha) and lymphotoxin-alpha have been shown to be associated with various metabolic traits including susceptibility to type 2 diabetes, metabolic syndrome, insulin resistance, and increased body mass index (BMI) in Caucasians from different geographic locations and have yielded mixed results. We tested for the association of these variants with type 2 diabetes in North Indians by studying 2,115 participants comprising of 1,073 type 2 diabetes patients and 1,042 controls. We report the association of a promoter region variant of TNF: rs1800630 and non-synonymous LTA variant: rs2229094 with type 2 diabetes [OR = 0.83 (95% CI 0.72-0.95), P = 0.005 and OR = 0.86 (95% CI 0.75-0.98), P = 0.02, respectively]. Although these associations were BMI-dependent, no interactive effect of BMI and variants on type 2 diabetes was detectable. Further, the haplotype carrying all the six major alleles conferred susceptibility to type 2 diabetes [OR = 1.23 (95% CI 1.06-1.42), P = 0.005; P (permuted) = 0.02], with the effect much enhanced in non-obese subjects [OR = 1.45 (95% CI 1.19-1.78), P = 2 x 10(-4): P (permuted) = 3 x 10(-4)]. The minor allele of rs2229094 was associated with lower hsCRP, BMI, and waist circumference (WC), while the minor allele of rs1800630 showed association with lower BMI and WC (all P < 0.01). This is the first report demonstrating association of rs1800630 and rs2229094 with type 2 diabetes in any population, suggesting an important role of the TNF-LTA locus in type 2 diabetes in North Indians.

Tumor necrosis factor alpha -238G>A genotype alters postprandial plasma levels of free fatty acids in obese individuals with type 2 diabetes mellitus

Tumor necrosis factor alpha (TNF-alpha) is a proinflammatory cytokine that impairs insulin action and alters lipid metabolism. We investigated the effects of genetic polymorphisms of TNF-alpha on circulating biomarkers of insulin resistance and lipid metabolism during an 8-hour metabolic profile test and a 2-hour oral glucose tolerance test in subjects with type 2 diabetes mellitus. Subjects (N = 123) recruited were type 2 diabetic men (n = 56) and women (n = 67) aged 36 to 75 years with a body mass index of at least 25 kg/m(2). Blood samples were collected to determine postprandial changes in circulating lipid levels and biomarkers of insulin resistance. Subjects were genotyped by polymerase chain reaction-restriction fragment length polymorphism for the TNF-alpha -238G>A, -308G>A, and -863C>A polymorphisms. Compared with subjects who were homozygous for the -238G allele, carriers of the -238A allele had an altered ability to suppress postprandial free fatty acids as shown by an increased net incremental area under the curve (0.26 +/- 2.44 vs -1.33 +/- 2.71 mEq h(-1) L(-1), P = .002) during the 8-hour metabolic profile test. This effect was observed in obese (1.04 +/- 2.42 vs -1.68 +/- 2.70 mEq h(-1) L(-1), P = .0004) but not in non-obese (-0.63 +/- 2.20 vs -0.95 +/- 2.71 mEq h(-1) L(-1), P = .6) individuals. Among obese subjects, carriers of the -308A allele had greater insulin resistance as estimated by the homeostasis model assessment of insulin resistance index (4.36 +/- 2.83 vs 2.85 +/- 1.75, P = .01), but no differences were observed among non-obese subjects (2.19 +/- 1.24 vs 1.97 +/- 0.90, P = .6). Our findings suggest that the -238G>A and -308G>A polymorphisms of TNF-alpha alter circulating free fatty acids and insulin resistance in obese subjects with type 2 diabetes mellitus.

Changes in inflammatory cytokines are related to impaired glucose tolerance in offspring of type 2 diabetic subjects

OBJECTIVE

We sought to determine whether levels of inflammatory markers and different cytokines are abnormal in nondiabetic offspring of type 2 diabetic subjects.

RESEARCH DESIGN AND METHODS

Cytokine levels were measured in 19 healthy control subjects and 129 offspring of patients with type 2 diabetes (109 with normal glucose tolerance [NGT] and 20 with impaired glucose tolerance [IGT]). Insulin sensitivity was determined with the hyperinsulinemic-euglycemic clamp, insulin secretion with the intravenous glucose tolerance test, and abdominal fat distribution with computed tomography.

RESULTS

Levels of C-reactive protein and inflammatory cytokines were elevated in nondiabetic offspring of type 2 diabetic subjects. Interleukin (IL)-1beta was increased in the NGT group and decreased in the IGT group. In contrast, levels of IL-1 receptor antagonist (IL-1Ra) were increased in both groups. IL-1beta and -Ra levels correlated inversely (P < 0.05) with rates of whole-body glucose uptake and IL-1beta positively with visceral fat mass (P < 0.05) in normoglycemic offspring.

CONCLUSIONS

Nondiabetic offspring of type 2 diabetic subjects have changes in the levels of inflammatory cytokines. The level of IL-1Ra seems to be the most sensitive marker of cytokine response in the pre-diabetic state.

Interleukin-10 and Tumor Necrosis Factor–α Single Nucleotide Gene Polymorphism Frequency in Paracoccidioidomycosis

Allelic variants of cytokine genes seem to be involved in mechanisms of resistance or susceptibility to several diseases. The aim of this study was to investigate the frequency of genotypes with the tumor necrosis factor-alpha TNF-alpha gene polymorphism G/A at position -308 and the IL-10 gene polymorphism G/A at position -1082, and to verify a possible association of these polymorphisms with paracoccidioidomycosis (PCM) caused by Paracoccidioides brasiliensis. Genotyping was performed by allele-specific polymerase chain reaction (ASPCR) and restriction fragment length polymorphism (RFLP) on genomic DNA isolated of granulocytes from 54 PCM patients and 31 noninfected individuals. The analysis of SNP at position -1082 IL-10 showed a high frequency of GA genotype in both patients and controls (51% and 55%, respectively), while the allelic frequency showed 54% of G allele in the patients and 66% of A allele in the controls. The GG genotype was more frequent in patients (85%) and controls (68%) when we analyze the SNP at position -308 of TNF-alpha gene. Otherwise, 91% of PCM patients and 84% of noninfected individuals carried the G allele in -308 TNF-alpha SNP. Stimulation of cells from individuals with PCM phenotyped as A+ (GA or AA genotypes) presented elevation of TNF-alpha producing cells when compared with IL-10-producer cells. These findings reinforce the critical role of IL-10 and TNF-alpha in the paracoccidioidomycosis and can strongly suggest that the genetic screening of the -308G/A and -1082G/A polymorphisms may be a valid tool for identification of subjects needing a more appropriate therapy.

Plasma Cell Membrane Glycoprotein-1 K121Q Polymorphism in Preeclampsia

BACKGROUND

Preeclampsia is a common hereditary disease with unclear aetiology and various genetic and environmental components. We wanted to determine whether genetic variability in the gene encoding plasma cell membrane glycoprotein-1 (PC-1) contributes to individual susceptibility to the development of preeclampsia.

METHODS

The case-control study involved 133 women with preeclampsia and 115 healthy controls. They were genotyped for the K121Q polymorphism in the PC-1 gene. chi(2) analysis was used to assess genotype and allele frequency differences between preeclamptic and control women.

RESULTS

The frequency of the PC-1 gene 121K allele was found to be equal in the two groups, being 90.2% among women with preeclampsia and 90.4% among controls (p = 0.937; OR = 1.024; 95% CI = 0.564-1.861). Also the genotype distribution of the PC-1 K121Q polymorphism was similar (p = 0.516) in the preeclamptic and control groups.

CONCLUSIONS

The K121Q polymorphism of the PC-1 gene is unlikely to be a major genetic factor predisposing to preeclampsia in Finnish women.

TNFalpha genotype affects TNFalpha release, insulin sensitivity and the severity of liver disease in HCV chronic hepatitis

BACKGROUND/AIMS

TNFalpha induces insulin resistance and promoter polymorphisms of TNFalpha gene affect the release of this cytokine, implicated in the pathogenesis of HCV-related diabetes and fatty liver. The aim was to define whether in patients with HCV chronic hepatitis TNFalpha genotype influences TNFalpha activity, insulin resistance, and the severity of the disease.

METHODS

186 patients, 65% with steatosis, 17% with diabetes. TNFalpha and sTNFR2 were determined by ELISA, insulin resistance by HOMA-R index and TNFalpha -238, -308, and -863 polymorphisms by restriction analysis.

RESULTS

TNFalpha, sTNFR2, and insulin resistance were higher in patients than in 89 controls. TNFalpha pathway activity was correlated with LDL cholesterol, steatosis, and insulin resistance, which, in turn, was correlated with the severity of liver damage. Patients subdivided according to TNFalpha genotype significantly differed for TNFalpha release, insulin sensitivity and the prevalence of cirrhosis. The -308 and -238 TNFalpha polymorphisms, characterized by increased promoter activity, were associated with higher TNFalpha activity, insulin resistance and severity of the disease, whereas the -863 polymorphism, characterized by reduced promoter activity, with lower TNFalpha activity, and higher insulin sensitivity.

CONCLUSIONS

TNFalpha genotype modulates the activity of the TNFalpha pathway, influences insulin sensitivity and the severity of HCV chronic hepatitis.

Inflammation, stress, and diabetes

Over the last decade, an abundance of evidence has emerged demonstrating a close link between metabolism and immunity. It is now clear that obesity is associated with a state of chronic low-level inflammation. In this article, we discuss the molecular and cellular underpinnings of obesity-induced inflammation and the signaling pathways at the intersection of metabolism and inflammation that contribute to diabetes. We also consider mechanisms through which the inflammatory response may be initiated and discuss the reasons for the inflammatory response in obesity. We put forth for consideration some hypotheses regarding important unanswered questions in the field and suggest a model for the integration of inflammatory and metabolic pathways in metabolic disease.

Inflammation, stress, and diabetes

Over the last decade, an abundance of evidence has emerged demonstrating a close link between metabolism and immunity. It is now clear that obesity is associated with a state of chronic low-level inflammation. In this article, we discuss the molecular and cellular underpinnings of obesity-induced inflammation and the signaling pathways at the intersection of metabolism and inflammation that contribute to diabetes. We also consider mechanisms through which the inflammatory response may be initiated and discuss the reasons for the inflammatory response in obesity. We put forth for consideration some hypotheses regarding important unanswered questions in the field and suggest a model for the integration of inflammatory and metabolic pathways in metabolic disease.

Inflammation, stress, and diabetes

Over the last decade, an abundance of evidence has emerged demonstrating a close link between metabolism and immunity. It is now clear that obesity is associated with a state of chronic low-level inflammation. In this article, we discuss the molecular and cellular underpinnings of obesity-induced inflammation and the signaling pathways at the intersection of metabolism and inflammation that contribute to diabetes. We also consider mechanisms through which the inflammatory response may be initiated and discuss the reasons for the inflammatory response in obesity. We put forth for consideration some hypotheses regarding important unanswered questions in the field and suggest a model for the integration of inflammatory and metabolic pathways in metabolic disease.

Differential regulation of insulin action and tumor necrosis factor alpha system activity by metformin

BACKGROUND

Tumor necrosis factor alpha has a key role in insulin resistance. We study the effects of metformin on glucose tolerance, insulin resistance, beta cell function, and soluble tumor necrosis factor receptor (sTNFR) levels.

METHODS

We performed a double-blind, randomized metformin-placebo study. Twenty-three subjects with impaired glucose tolerance or impaired fasting glucose were studied. Oral glucose tolerance, homeostasis model assessment, and continuous infusion of glucose with model assessment tests were used to evaluate glucose tolerance, insulin sensitivity, and beta cell function, respectively. Soluble tumor necrosis factor receptor levels were measured before and after therapy. Repeated measures analysis of variance was used for statistical analysis.

RESULTS

After 12-week treatment, fasting glucose (110.1 +/- 9.9 to 98.9 +/- 15.7 mg/dl, P < .001), fasting insulin (11.6 +/- 5.4 to 8.8 +/- 3.5 mU/L, P = .05), fasting C-peptide (2.5 +/- 0.7 to 1.8 +/- 0.5 ng/mL, P < .05), and achieved C-peptide (5.2 +/- 1.2 to 4.2 +/- 1 ng/mL, P < .05) levels decreased in the metformin group. In addition, there was an improvement in insulin sensitivity (37.4% +/- 15.2% to 50.4% +/- 23.2%, P < .05) with unchanged sTNFR1 (2.0 +/- 0.8 to 2.3 +/- 1.2 microg/L, P = NS) and sTNFR2 (4.8 +/- 1.7 to 4.4 +/- 1.2 microg/L, P = NS) levels.

CONCLUSIONS

Metformin is able to reverse insulin resistance and hyperglycemia in high-risk subjects for type 2 diabetes mellitus independently of the effects on tumor necrosis factor alpha system activity.