Toll-like receptor 4 gene Asp299Gly and Thr399Ile polymorphisms in type 2 diabetes mellitus: a meta-analysis of 15,059 subjects

Molecular Effect of Variants in Toll-like Receptor 4 Gene in Saudi Patients with Type 2 Diabetes Mellitus

Single-nucleotide polymorphisms (SNPs) in the Toll-like receptor 4 (TLR4) gene have been documented in type 2 diabetes mellitus (T2DM) and other diseases in the Saudi population. We investigated the relationship between rs11536889, rs4986790, and rs4986791 SNPs in the TLR4 gene and T2DM in the Saudi population; 105 patients with T2DM and 105 healthy controls were analyzed. The TLR4 gene was amplified through PCR, followed by restriction fragment length polymorphism analysis for rs4986791 and Sanger sequencing for rs11536889 and rs4986790 SNPs. The clinical and biochemical characteristics were associated with T2DM (p < 0.05). The rs11536889, rs4986790, and rs4986791 SNPs in control subjects followed the Hardy-Weinberg equilibrium (p > 0.05). Alleles were associated with rs11536889, rs4986791, heterozygous codominant, and dominant models (p < 0.05). However, the rs4986790 SNP was not associated with T2DM (p > 0.05). Logistic regression analysis showed that high-density lipoprotein cholesterol (HDLc) levels were associated with T2DM (p < 0.001). Analysis of variance showed that waist (p = 0.0005) and hip circumferences (p = 0.002) in rs4986790 and rs4986791 SNPs, in SBP (p = 0.001), DBP (p = 0.002), and HDLc levels (p = 0.003), were associated with T2DM subjects. T2DM was also associated with the haplotype (p < 0.001) but not with linkage disequilibrium. The gene-gene interaction was associated with the three SNPs studied in patients with T2DM according to the generalized multifactor dimensionality reduction model (p < 0.0001). Dendrogram and graphical depletion analysis revealed a moderate association in patients with T2DM. The results suggest that rs11536889 and rs4986790 SNPs are genotypically and allelically associated with T2DM in Saudi patients. Future functional studies are recommended to validate the genetic roles of these SNPs in the pathogenesis and progression of diseases.

Toll like receptor 4 gene Asp299Gly polymorphism increases the risk of diabetic microvascular complications: a meta analysis

OBJECTIVE

The relationship between Toll like receptor 4(TLR4) gene Asp299Gly polymorphism and diabetic microvascular complications (DMI) is unclear. Therefore, the aim of this meta analysis was to explore the relationship between TLR4 Asp299Gly polymorphism and DMI.

METHODS

System search PubMed, Web of science, Springer, Cochrane library, ELSEVIER, Wanfang database, VIP, CNKI, a case-control study of the correlation between TLR4 gene Asp299Gly polymorphism and DMI published before June 2020 was collected.

RESULTS

We included 6 articles, a total of 11 studies involving patients with type 2 diabetes mellitus (T2DM) complicated by microvascular complications 1834 cases, without corresponding microvascular complications 4069 cases. TLR4 gene Asp299Gly polymorphism increased the risk of microvascular complications in T2DM (dominant model OR = 1.52, 95% CI 1.10-2.09, p = 0.01; allelic model OR = 1.42, 95% CI 1.02-1.96, p = 0.04). Subgroup analysis by race and different type of microvascular complications, we found that TLR4 gene Asp299Gly polymorphism was associated with increased risk of microvascular complications in the Caucasian population (dominant model OR = 1.69, 95% CI 1.22-2.35, P = 0.002; allelic model OR = 1.56, 95% CI 1.10-2.21, P = 0.01) and increased the risk of retinopathy in patients with T2DM(dominant model OR = 1.81, 95% CI 1.04-3.14, P = 0.03; allelic model OR = 1.77, 95% CI 1.05-2.98, P = 0.03).

CONCLUSION

TLR4 gene Asp299Gly polymorphism was associated with increased risk of microvascular complications in patients with T2DM, especially diabetic retinopathy (DR).

Quantitative assessment of TLR4 gene polymorphisms and T2DM risk: A meta-analysis

BACKGROUND

Numerous studies have evaluated the association between TLR4 gene polymorphisms and T2DM risk. However, the findings were inconsistent and controversial.

METHODS

In order to drive a more precise estimation, we carried out a meta-analysis based on 41 studies involving 23,250 cases and 24,760 controls. Pooled odds ratios (ORs) with 95% confidence intervals (CIs) were calculated to assess the strength of association.

RESULTS

Our meta-analysis provides evidence that rs4986790 polymorphism was associated with an increased risk of T2DM in Asian (AG vs. AA, OR = 1.23, 95% CI = 1.01-1.50, p = 0.042; G vs. A, OR = 1.21, 95% CI = 1.01-1.44, p = 0.041). Rs4986791 polymorphism was related to an increased risk of T2DM both in Asian (AG vs. AA, OR = 1.76, 95% CI = 1.11-2.80, p = 0.017; G vs. A, OR = 1.63, 95% CI = 1.04-2.55, p = 0.034) and Caucasian (GG vs. AA, OR = 2.42, 95% CI = 1.23-4.75, p = 0.010). Rs11536889 polymorphism may have a protective effect on T2DM in Chinese populations (CC vs. GG, OR = 0.62, 95% CI = 0.40-0.96, p = 0.031; GC vs. GG, OR = 0.77, 95% CI = 0.61-0.98, p = 0.034; CC vs. GC/GG, OR = 0.81, 95% CI = 0.69-0.96, p = 0.013; C vs. G, OR = 0.76, 95% CI = 0.59-0.97, p = 0.027), whereas rs1927911 may have no impact.

CONCLUSIONS

These findings supported that rs4986790, rs4986791, and rs11536889 may contribute to the risk of T2DM.

TLR4 Polymorphisms (896A>G and 1196C>T) Affect the Predisposition to Diabetic Nephropathy in Type 2 Diabetes Mellitus

PURPOSE

Type 2 diabetes mellitus (T2DM) is a disease with a steadily increasing incidence throughout the world. Some molecules regulating the innate immune responses such as toll-like receptor 4 (TLR4) have shown to be involved in late diabetic complications. This study aimed to investigate the association of TLR4 gene polymorphisms with clinicopathological aspects of T2DM in the Iranian population.

PATIENTS AND METHODS

Two TLR4 896A>G and 1196C>T polymorphisms were assessed in 100 T2DM patients and 100 healthy controls using sequence-specific primers PCR. Demographic, anthropometric, and biochemical parameters were obtained from the participants.

RESULTS

After logistic regression, in 1196C>T, a significant association was shown between diabetic nephropathy (DN) and CT genotype (P= 0.04, OR= 4.35, CI= (1.04-18.1)). TG level has increased significantly in both T2DM and control subjects with CT genotype (P= 0.027, OR= 1.005, 95% CI= (1.001-1.01)). For 896A>G variant, a significant association was also detected between AG genotype and increased oral glucose tolerance test (OGTT) level (P= 0.048, OR= 1.003, 95% CI= (1.00-1.005)).

CONCLUSION

Although minor alleles of 1196C>T and 896A>G variants have not directly been associated with type 2 diabetes, by involving in the dysregulation of serum TG and blood sugar levels, they might increase the risk of DN.

TLR4 polymorphisms seem not to be associated with prediabetes and type 2 diabetes but predispose to diabetic retinopathy; TLR4 polymorphisms in glucose continuum

OBJECTIVES

Compared to type 1 diabetes, the role of the immune and autoimmune pathogenetic mechanisms is much less studied in the type 2 diabetes. Toll-like receptors 4 (TLR4) have a leading role in inflammation, insulin resistance, and vascular damage. This study aimed to analyze the relationship between the polymorphisms in TLR4 gene and different stages in the glucose continuum from prediabetes to the type 2 diabetes and chronic microvascular complications.

MATERIALS AND METHODS

The study included 113 patients with the type 2 diabetes, 29 participants with prediabetes, and 28 controls. Polymerase chain reaction (PCR) was used for genotyping Asp299Gly and Thr399Ile polymorphism, followed by restriction analysis.

RESULTS

The difference in the genotype frequency for both polymorphisms in patients with the type 2 diabetes or prediabetes compared to that in controls was not significant. Patients with heterozygous genotype of Asp299Gly polymorphism had a higher prevalence of diabetic retinopathy (42.9%) than participants with homozygous genotype (9.0%) (OR [95%CI]=7.61 [1.41-41.08]; p=0.018). No association was established for diabetic polyneuropathy and nephropathy. Prevalence of chronic diabetes complications was not related to Thr399Ile polymorphism.

CONCLUSION

Our study demonstrates that Asp299Gly and Thr399Ile polymorphisms seem not to be associated with the type 2 diabetes and prediabetes but Asp299Gly may contribute to diabetic retinopathy predisposition.

TLR4 triggered complex inflammation in human pancreatic islets

Type 2 Diabetes (T2D) is strongly associated with obesity and inflammation. Toll-like receptor-4 (TLR-4) is the major pro-inflammatory pathway with its ligands and downstream products increased systemically in T2D and in at-risk individuals. Detailed mechanisms of the complex proinflammatory response in pancreatic islets remain unknown. In isolated human islets LPS induced IL-1β, IL-6, IL-8 and TNF production in a TLR4-dependent manner and severely impaired β-cell survival and function. IL-6 antagonism improved β-cell function. IL-8, which was identified specifically in α-cells, initiated monocyte migration, a process fully blocked by IL-8 neutralization. The TLR4 response was potentiated in obese donors; with higher IL-1β, IL-6 and IL-8 expression than in non-obese donors. TLR4 activation leads to a complex multi-cellular inflammatory response in human islets, which involves β-cell failure, cytokine production and macrophage recruitment to islets. In obesity, the amplified TLR4 response may potentiate β-cell damage and accelerate diabetes progression.

Testing an association between TLR4 and CXCR1 gene polymorphisms with susceptibility to urinary tract infection in type 2 diabetes in north Indian population

BACKGROUND

Genetic variations of Toll like receptor 4 (TLR4) and CXC-chemokine receptor type1 (CXCR1), the key elements of innate immune system and their association with urinary tract infection (UTI) were studied in general population. In present study we investigate genetic variation of these genes in diabetic patients (3 to 4 times higher prevalence of UTI in comparison to general population).

METHODS

A total 1100 subjects (318 diabetic patients with UTI, 324 diabetic patients without UTI, 200 non-diabetic UTI patients and 260 age matched healthy control) were enrolled in the study. SNPs of TLR4 rs4986790, rs4986791 and CXCR1 rs2234671 was assessed by PCR-RFLP and PCR-SSP respectively.

RESULTS

Statistical analysis revealed that A/G genotype and G allele of TLR4 rs4986790 are significantly associated with UTI in both diabetics and nondiabetic patients in comparison to healthy control. Similarly CT genotype and T allele of TLR4 rs4986791 are also significantly associated with UTI in both groups. We also found that prevalence of A/G genotype of TLR4 rs4986790 and CT genotype of TLR4 rs4986791 are significantly higher in patients of diabetes with UTI in comparison to diabetic patients without UTI. We did not find any association of CXCR1 rs2234671 polymorphism with UTI by comparing with any group.

CONCLUSION

We found that TLR4 rs4986790 and rs4986791 gene polymorphism is a risk for UTI development in both diabetic and nondiabetic patients in north Indian population.

Development of gene polymorphisms in meditators of nonalcoholic fatty liver disease

Nonalcoholic fatty liver disease (NAFLD) is the most prevalent liver disease worldwide, the morbidity of which closely correlates with diversity of ethnicity, minority, family and location. Its histology spans from simple steatosis, to nonalcoholic steatohepatitis, which ultimately results in fibrosis, cirrhosis and hepatocellular carcinoma. The accelerating prevalence of NAFLD is due to an incremental incidence of metabolic syndrome that is distinguished by dyslipidemia, glucose impairment, obesity, excessive oxidative stress and adipocytokine impairment. Additionally, the pathogenesis of NAFLD is thought to be a multifactorial and complicated disease associated with lifestyle habits, nutritional factors and genetics. However, the pathogenesis and underlying mechanism in the development of NAFLD caused by genetics remains unclear. People have been increasingly emphasizing on the relationship between NAFLD and gene polymorphisms in recent years, with the aim of having a comprehensive elucidation of associated gene polymorphisms influencing the pathogenesis of the disease. In the current article, the authors attempted to critically summarize the most recently identified gene polymorphisms from the facets of glucose metabolism, fatty acid metabolism, oxidative stress and related cytokines in NAFLD that contribute to promoting the progression of the disease.

Significant Association between Toll-Like Receptor Gene Polymorphisms and Posttransplantation Diabetes Mellitus

<b><i>Background:</i></b> Posttransplantation diabetes mellitus (PTDM) is an important metabolic complication after renal transplantation. Activation of the innate immune system via toll-like receptors (TLRs) is implicated in the pathogenesis of insulin resistance and deficiency. Although links between diabetes, dysregulated innate immune responses, and the TLR signaling pathway have been reported, no study so far has investigated their associations with PTDM. In this study, we ascertained whether single nucleotide polymorphisms (SNPs) in TLRs are associated with PTDM in the Korea population. <b><i>Methods:</i></b> A total of 305 patients who received renal transplants without previously diagnosed diabetes were included. We analyzed the association between PTDM development and 6 SNPs within 2 genes of <i>TLR2</i>, 1 gene of <i>TLR4</i>, and 3 genes of <i>TRL6</i>. <b><i>Results:</i></b> Of 305 patients, PTDM developed in 51 patients (16.6%). Patients in the PTDM group were older than those in the non-PTDM group (45.56 ± 1.28 vs. 38.28 ± 0.71 years). Patients with PTDM had significantly higher allele frequency compared to those without PTDM for the <i>TLR</i>4 rs1927914*T, <i>TLR6 </i>rs3775073*A, <i>TLR6</i> rs3821985*C, and <i>TLR6</i> rs1039559*C alleles. Of the 6 SNPs, rs1927914 in the <i>TLR4</i> gene and rs1039559 in the <i>TLR6</i> gene were significantly associated with the development of PTDM after adjustment for age, gender, and tacrolimus usage. <b><i>Conclusions:</i></b> Our study demonstrates a significant association between SNPs<i> rs1927914</i> in <i>TLR4</i> and rs1039559 in <i>TLR6</i> and PTDM in the renal transplantation recipient group. These data suggest that the activation of the innate immune system and inflammation via TLR activation might have an essential role in the pathogenesis of PTDM in renal transplantation.