No association between the -1031 polymorphism in the TNF-alpha promoter region and type 1 diabetes

Antidiabetic and hypolipidemic potentials of Solidago virgaurea extract in alloxan-induced diabetes type 1

OBJECTIVES

The aim of the current study is to investigate the antidiabetic and hypolipidemic potentials of Solidago virgaurea extract in alloxan-induced diabetic rats.

MATERIALS AND METHODS

Alloxan-induced diabetic rats were orally administered a dose of Solidago virgaurea extract (250 mg/kg body weight) daily for 15 days. Then blood glucose, insulin, serum lipid profile, amylase, tumour necrosis factor-α (TNF- α), and liver glycogen were determined. Besides, superoxide dismutase (SOD), catalase activities, and malondialdehyde (MDA) levels in pancreatic tissue were assessed.

RESULTS

Solidago virgaurea extract significantly reduced blood glucose level, serum amylase activity, TNF-α level, and pancreatic MDA level as well as increasing the serum insulin, liver glycogen level, pancreatic SOD, and catalase activities in comparison with their corresponding diabetic rats, p < .05.

CONCLUSION

The findings of this study support the ethnomedicinal use of Solidago virgaurea extract as an antidiabetic and antihyperlipidemic in the management of diabetes mellitus.

Hypoglycemic and pancreatic protective effects of Portulaca oleracea extract in alloxan induced diabetic rats

BACKGROUND

Diabetes is a major public health concern. In spite of continuous new drug development to treat diabetes, herbal remedies remain a potential adjunct therapy to maintain better glycemic control while also imparting few side-effects. Portulaca oleracea has been traditionally used to manage several diseases due to the anti-oxidant and anti-atherogenic effects it imparts. To better understand the mechanisms associated with potential protective effect of P. oleracea extract against diabetes, alloxan-induced diabetic rats were used in this study.

METHODS

Forty Wistar rats (male, 7-8-wk-old, 140-160 g) were divided into four groups (n = 10/group): Group I (control), Group II (P. oleracea-treated; gavaged with P. oleracea extract daily [at 250 mg/kg] for 4 weeks), Group III (diabetic control; daily IP injection of alloxan [at 75 mg/kg] for 5 days) and Group IV (P. oleracea-pre-treated diabetic; gavaged with P. oleracea extract daily [at 250 mg/kg] for 4 weeks and then daily IP injection of alloxan [at 75 mg/kg] for 5 days). Body weight, food consumption, blood (serum) levels of glucose, C peptide, Hb A1C, insulin, tumor necrosis factor (TNF)-α and interleukin (IL)-6 were determined for all groups.

RESULTS

The results indicated that while Hb A1C, serum levels of glucose, TNF-α and IL-6 were all significantly decreased in the P. oleracea-pre-treated diabetic rats, these hosts also had significant increases in C peptide and insulin compared to levels in the counterpart diabetic rats. These results were confirmed by the histopathological assessments which showed marked improvement of the destructive effect on pancreatic islet cells induced by alloxan.

CONCLUSION

P. oleracea extract is a general tissue protective and regeneartive agent, as evidenced by increasing β-cell mass and therefore improved the glucose metabolism. Thus, stimulation of Portulaca oleracea signaling in β- cells may be a novel therapeutic strategy for diabetes prevention.

Associations between TNF gene polymorphisms (-308 A/G, -238 A/G, -1031 C/T and -857 T/C) and genetic susceptibility to T1D: a meta-analysis

The aim of this study was to estimate the associations between tumor necrosis factor (TNF) gene polymorphisms and type 1 diabetes (T1D) using meta-analysis. Relevant studies were searched using PubMed and Embase up to August 2013. A total of 32 comparisons from 21 studies examining the associations between TNF polymorphisms and T1D were included in the present meta-analysis. Our meta-analysis identified a significant association between TNF -308 A/G polymorphism A allele and T1D in all subjects [odds ratio (OR) 2.001, 95 % confidence interval (CI) 1.732-2.312). Significant associations of AA and AA+AG genotype of TNF -308 A/G polymorphism with genetic susceptibility to T1D were also found (OR 3.203, 95 % CI 2.373-4.324; OR 2.232, 95 % CI 1.881-2.649). After stratification by ethnicity, significant associations of T1D with TNF -308 A/G polymorphism under all genetic models (A allele and AA, AA+AG genotype) were still detected in European (OR 1.952, 95 % CI 1.675-2.274; OR 3.108, 95 % CI 2.169-4.455; OR 2.249, 95 % CI 1.870-2.706, respectively) and non-European populations (OR 2.152, 95 % CI 1.488-3.112; OR 3.439, 95 % CI 2.000-5.914; OR 2.207, 95 % CI 1.496-3.257, respectively). Our meta-analysis also revealed an association of TNF -857 T/C polymorphism T allele with T1D risk (OR 1.647, 95 % CI 1.431-1.896). Furthermore, analysis of TT and TT+TC genotype indicated the same result patterns as shown by the TNF -857 T/C polymorphism T allele (OR 2.206, 95 % CI 1.467-3.317; OR 1.762, 95 % CI 1.490-2.083). In conclusion, our meta-analysis results indicate that TNF -308 A/G and -857 T/C polymorphisms are involved in the genetic background of T1D.

Tumor necrosis factor-associated susceptibility to type 1 diabetes is caused by linkage disequilibrium with HLA-DR3 haplotypes

Tumor necrosis factor-α (TNF-α) is an important proinflammatory cytokine involved in the pathogenesis of autoimmune type 1 diabetes (T1D). The TNF gene locus is located in the major histocompatibility complex (MHC) class III region and its genetic polymorphisms have been reported to be associated with T1D. However, it is not clear whether these associations are primary or caused by their linkage disequilibrium with other predisposing genes within the MHC. We have tested 2 TNF-α single nucleotide polymorphisms at positions -308G/A and -238G/A in the 5' untranslated region and a (GT)n microsatellite TNFa in the North Indian healthy population and T1D patients with known HLA-A-B-DR-DQ haplotypes. The allele frequencies of TNFa5, -308A, and -238G were determined to be significantly increased among patients compared with controls. Although the observed positive association of -238G was caused by its presence on all 3 DR3(+) groups, namely, B8-DR3-DQ2, B50-DR3-DQ2, and B58-DR3-DQ2 haplotypes associated with T1D in this population, the increase of the -308A allele was caused by its association with the latter 2 haplotypes. On the other hand, TNF -308G occurred on B8-DR3 haplotypes along with -238G and TNFa5 alleles, particularly in T1D patients with late disease onset (at >20 years of age). These results indicate that TNF associations with T1D are caused by their linkage disequilibrium with specific HLA-DR3-DQ2 haplotypes in the Indian population. Because polymorphisms in the promoter region regulate TNF expression levels (e.g., -308A), they retain crucial immunological significance in the development of T1D and its management.