Type 1 diabetes susceptibility determined by HLA alleles and CTLA-4 and insulin genes polymorphisms in Brazilians

Cluster of differentiation molecules in the metabolic syndrome

Metabolic syndrome (MetS) represents a significant public health concern due to its association with an increased risk of cardiovascular disease, type 2 diabetes, and other serious health conditions. Despite extensive research, the underlying molecular mechanisms contributing to MetS pathogenesis remain elusive. This review aims to provide a comprehensive overview of the molecular mechanisms linking MetS and cluster of differentiation (CD) markers, which play critical roles in immune regulation and cellular signaling. Through an extensive literature review with a systematic approach, we examine the involvement of various CD markers in MetS development and progression, including their roles in adipose tissue inflammation, insulin resistance, dyslipidemia, and hypertension. Additionally, we discuss potential therapeutic strategies targeting CD markers for the management of MetS. By synthesizing current evidence, this review contributes to a deeper understanding of the complex interplay between immune dysregulation and metabolic dysfunction in MetS, paving the way for the development of novel therapeutic interventions.

The Relationship between insulin variable number of tandem repeats (INS-VNTR) -23 A/T and cytotoxic Tlymphocyte associated protein-4 (CTLA-4) +49 A/G polymorphisms with islet autoantibodies in persons with diabetes

Background: Both genetic and environmental factors are important in pathogenesis of diabetes. Non HLA (Human Leukocyte Antigen) genes such as INS-VNTR and CTLA-4 in addition of HLA genes have influence on genetic susceptibility for diabetes mellitus. In this study the association of +49 A/G CTLA-4 and -23 A/T INS-VNTR polymorphisms with diabetes and their association with islet autoantibodies were investigated. Methods: Thirty four autoantibody positive adult persons with diabetes mellitus and 39 persons with Type 1diabetes mellitus (T1DM), 40 autoantibody negative Type 2 diabetes mellitus (T2DM) patients and 40 healthy controls were studied using Polymerase Chain Reaction-Restriction Fragment Length Polymorphism (PCR-RFLP) technique. Results: The frequencies of -23 A/T INS-VNTR genotypes were not significantly different among study groups. It was shown that the distribution of the +49A/G CTLA-4 allele and genotype frequencies did not differ between T1DM patients, autoantibody positive adult patients and controls. With increasing CTLA-4 G allele and GG/AG genotypes, the frequency of Glutamic Acid Decarboxylase Autoantibody (GADA), Islet Cell Autoantibody (ICA) and Islet Antigen 2 Antibody (IA2A) positive patients were increased. Conclusion: Our results suggest that susceptibility allele A of -23A/T INS-VNTR does not have any role in the pathogenesis of diabetes in our patients and susceptibility allele G of +49 A/G CTLA-4 if not, has a small role in pathogenesis of diabetes in T1DM and autoantibody positive adult patients and in spite of significant increase in autoantibody negative T2DM group it does not have any role in disease pathogenesis.

Insulin gene VNTR polymorphisms -2221MspI and -23HphI are associated with type 1 diabetes and latent autoimmune diabetes in adults: a meta-analysis

AIMS

A variable number of tandem repeat (VNTRs) region in the insulin gene (INS) possibly influences the progression of type 1 diabetes (T1D) and latent autoimmune diabetes in adults (LADA). However, effects of INS VNTR polymorphisms in these contexts remain inconclusive.

METHODS

We performed a systematic review of work on the INS VNTR -2221MspI and -23HphI polymorphisms to estimate the overall effects thereof on disease susceptibility; we included 17,498 T1D patients and 24,437 controls, and 1960 LADA patients and 5583 controls.

RESULTS

For T1D, the C allele at -2221MspI and the A allele at -23HphI were associated with estimated relative risks of 2.13 (95 % CI 1.94, 2.35) and 0.46 (95 % CI 0.44, 0.48), which contributed to absolute increases of 46.76 and 46.98 % in the risk of all T1D, respectively. The estimated lambda values were 0.44 and 0.42, respectively, suggesting that a co-dominant model most likely explained the effects of -2221MspI and -23HphI on T1D. For -23HphI, the A allele carried an estimated relative risk of 0.55 (95 % CI 0.50, 0.61) for LADA and increased the risk of all LADA by 36.94 %. The λ value was 0.43, suggesting that a co-dominant model most likely explained the effect of -23HphI on LADA.

CONCLUSIONS

Our results support the existence of associations of INS with T1D and LADA.

Elevated CD8 T cell responses in type 1 diabetes patients to a 13 amino acid coeliac-active peptide from α-gliadin

Some type 1 diabetes (T1D) patients have been reported to exhibit T cell reactivity to wheat gluten. We tested the hypothesis that this T cell reactivity could be abolished by using prolyl-endopeptidase (PEP), an enzyme that cleaves peptide bonds after proline. Peripheral blood mononuclear cells (PBMCs) were isolated from T1D patients and healthy controls. PBMCs were stimulated with a peptic-tryptic digest of wheat gluten; a peptic-tryptic-PEP digest of wheat gluten; and a 13 amino acid peptide from wheat gluten. Fluorescent-labelled antibodies to CD3, CD4 and CD8 cell marker proteins were utilized to determine proliferative responses of CD3, CD4 and CD8 T cells. There were no significant differences in proliferative responses of CD3 or CD4 T cells to the wheat gluten antigens. A significantly higher proportion of CD8(+) T cells from T1D patients proliferated in the presence of the 13 amino acid peptide than when challenged with the peptic-tryptic or the peptic-tryptic-PEP digests of wheat gluten. PEP treatment had no significant effect on CD8 T cell reactivity to the peptic-trytic digest of wheat gluten. Our results suggest that wheat gluten-derived peptides, containing ≤ 13 amino acids, may evoke T cell responses in T1D patients.

Association between the CTLA-4 +49A/G polymorphism and type 1 diabetes: a meta-analysis

BACKGROUND

+49A/G polymorphism of the cytotoxic T-lymphocyte-associated antigen-4 gene (CTLA-4) has been associated with type 1 diabetes (T1D). However, results were inconsistent. The aim of this study was to quantitatively summarize the evidence for CTLA-4 +49A/G polymorphism and T1D.

METHODS

Electronic search of PubMed was conducted to select studies. Case-control studies containing available genotype frequencies of CTLA-4 +49 were chosen, and the odds ratio (OR) with 95% confidence interval (CI) was used to assess the strength of this association.

RESULTS

49 case-control studies, including 8976 cases and 11012 controls, were identified. 8 studies were eliminated from the total 49 studies because of p<0.05 (p value for Hardy-Weinberg equilibrium in the control group) in these studies, which induce significant publication bias. The overall results suggested that the variant genotypes were highly associated (p<0.01) with T1D risk in all genetic models (additive model: OR 1.345, 95% CI 1.249-1.448, p<0.001; recessive model: OR 1.530, 95% CI 1.370-1.708, p<0.001; dominant model: OR 1.409, 95% CI 1.263-1.572 p<0.001). Similarly, in subgroup analyses for ethnicity (Caucasian, Asian), the results were positive.

CONCLUSION

This meta-analysis suggests that the CTLA-4 +49A/G polymorphism is highly associated (p<0.01) with increased risk of T1D, especially in Caucasians and Asians. To validate this association, further studies with more participants worldwide are needed to examine associations between this polymorphism and T1D. Otherwise, we found that the studies of Africans are rare. More studies in Africans are needed especially.

HLA-DQB1* alleles and genetic susceptibility to type 1 diabetes mellitus

AIM: To determine human leukocyte antigen (HLA)-DQB1 allele association with susceptibility to type 1 diabetes (T1D) and to clinical and laboratory findings.

METHODS: This study was conducted on 85 unrelated Egyptian children with T1D recruited consecutively from the Pediatric Diabetes Endocrinology outpatients Clinic; Mansoura University Children’s Hospital, Egypt. Patient mean follow up period was 2.5 years. Patients were subdivided according to level of HbA1c (optimal/suboptimal control < 8.5% and poor control ≥ 8.5%). The control group consisted of 113 unrelated age- and sex-matched healthy subjects without T1D or other autoimmune diseases. Genomic DNA extraction was done for all subjects using a DNA isolation kit. HLA-Class II-DQB1 allele typing was carried out with a polymerase chain reaction-sequence-specific oligonucleotide probe using a INNO-LiPA HLA-DQB1 update kit.

RESULTS: Significant differences were detected between Egyptian patients with T1D and control groups in the frequencies of DQB1*02 [44.4% vs 18.6%, corrected P value (Pc) < 0.001] and DQB1*03 (41.2% vs 24.4%, Pc < 0.001). Significant differences were also observed between control groups and T1D patients in the frequencies of DQB1*05 (14.6% vs 7.2%, P = 0.029) and DQB1*06 (34.1% vs 7.2%, P < 0.001). However, after correction for multiple comparisons, the significance was retained for HLA-DQB1*06 (Pc < 0.001) but lost for HLA-DQB1*05. HLA-DQB1*0201, *0202, *030201 were positively associated with T1D (Pc = 0.014, Pc < 0.001, and Pc < 0.001 respectively), while HLA-DQB1*060101 was negatively associated (Pc < 0.001) with the condition. Although the HLA-DQB1 alleles 030101 and 050101 were significantly higher in controls (P = 0.016, P = 0.025 respectively), both of them lost statistical significance after correction of P value. The frequency of the HLA-DQB1 genotypes 02/02, 02/03, and 03/03 was higher in T1D patients, and the frequency of the genotypes 03/06, 05/06, and 06/06 was higher in controls, these differences being statistically significant before correction. After correction, the genotypes 02/02, 02/03 in T1D, and the genotypes 03/06, 06/06 in controls were still significant (Pc = 0.01, Pc < 0.001, Pc < 0.001, and Pc = 0.04, respectively). Non-significant associations were found between the frequency HLA-DQB1 alleles and genotypes in T1D in relation to the grade of diabetic control, Microalbuminuria, age, gender, age of presentation, weight, height, frequency of diabetic ketoacidosis (P = 0.42), serum cholesterol, and fasting and post-prandial level of C-peptide (P = 0.83, P = 0.9, respectively).

CONCLUSION: The Current work suggests that HLA-DQB1 alleles *030201, *0202, *0201, and genotypes 02/03, 02/02 may be susceptibility risk factors for development of T1D in Egyptian children, while the HLA-DQB1*060101 allele, and 03/06, 06/06 genotypes may be protective factors. HLA-DQB1 alleles and genotypes do not contribute to microalbuminuria or grade of diabetic control.

Association of cytotoxic T-lymphocyte associated antigen 4 gene polymorphism with type 1 diabetes mellitus: a meta-analysis

To evaluate the association between costimulatory molecule cytotoxic T-lymphocyte-associated antigen-4 (CTLA-4) gene polymorphism and type 1 diabetes mellitus(T1DM), sixty-three published studies before December, 2011 were included. Meta-analysis was performed for each genotype in a random/fixed effect model. The combined odds ratio (OR) with 95% confidence interval (95%CI) was calculated to estimate the strength of the association. Overall, significant correlation was noted between CTLA-4 gene polymorphism (i.e. +49A/G, CT60A/G in a per-allele model) and the risk of T1DM (for +49A/G: OR=1.47, 95%CI=1.36-1.60, P<0.001; for CT60A/G: OR=1.31, 95%CI=1.18-1.45, P<0.001). However, no significant association was noted between C(-318)T polymorphism and T1DM. In the subgroup analysis, for +49A/G and CT60A/G, the statistically significant associations were also demonstrated in diverse racial descents (Caucasian and Asian) and age of onset (<20 years and >20 years). In conclusion, our results suggest that CTLA-4 polymorphism contributes to the susceptibility of T1DM.