Vitamin D binding protein gene polymorphisms and risk of type 1 diabetes mellitus among Egyptians

Type 1 diabetes [T1DM] is a multifactorial autoimmune disease in which both genetic predisposition and environmental factors participate in its development. Many cellular and epidemiological studies suggest a role for vitamin D in pathogenesis and prevention of T1DM. Polymorphisms of the genes involved in the metabolism of vitamin D may predispose to T1DM. Vitamin D-binding protein [DBP] is the main systemic transporter of vitamin D and is essential for its cellular endocytosis. There are two known polymorphisms in exon 11 of the DBP gene resulting in amino acid variants: GAT->GAG substitution replaces aspartic acid by glutamic acid in codon 416; and ACG->AAG substitution in codon 420 leads to an exchange of threonine for lysine. These DBP variants lead to differences in the affinity for vitamin D. Few published studies, about the correlation between these alleles and T1DM, yielded conflicting results. Therefore, we investigated the association of these polymorphisms with T1DM in Egyptian subjects. Unrelated 59 children with T1DM and 65 healthy controls were included in this study. The sequence of DBP exon 11, which contains both examined variants, was amplified by polymerase chain reaction [PCR]. Alleles and genotypes were determined using Restriction Fragment Length Polymorphism analysis [RFLP]. At codon 416 the frequency of Glu/Asp alleles was 64.4/35.6% in T1DM patients and 55.4/44.6% in controls [P >0.05]. At codon 420 the frequency of Thr/Lys alleles were 88.1/11.9% and 87.7/12.3% [P >0.05] respectively. Distributions of genotypes at both loci, and the common haplotypes constructed by them, were also very similar in both groups [P >0.05]. It could be concluded that the studied DNA polymorphisms in the DBP gene are not associated with T1DM in Egyptian patients

Enhanced apoptosis of peripheral blood mononuclear cells from chronic hcv patients is associated with reduced caspase 3 activity

Background: Infection with hepatitis C virus [HCV] is a major cause of chronic liver disease throughout the world. Down-regulation of the immune response plays a major role in HCV persistence. Recent investigation suggest that apoptosis of peripheral blood mononuclear cells [PBMCs] contributes to such down-regulation

Objective: The current study investigates apoptotic changes in PBMCs and their relation to caspase-3 and -8 activities in patients with chronic HCV infection

Methods: Apoptosis were investigated by measuring annexin-V binding using flowcytometry and DNA fragmentation using agarose gel electrophoresis, and caspases-3 and -8 specific activities were also measured in 43 chronic HCV patients and 10 normal control subjects

Results: A significantly higher percent of annexin-V positive PBMCs was found in chronic HCV patients than controls [p<0.0001]. DNA fragmentation was detected in PBMCs from 20/43 patients [46.5%] but not from controls. There was no statistically significant difference between HCV-PCR positive and negative patients as regards the degree of PBMCs apoptosis. Caspase-3 activity was significantly lower in patients than controls [p=0.001], was significantly lower in HCV-PCR positive than controls [p=0.001] and was significantly higher in patients with PBMCs DNA fragmentation [p=0.005]. On the other hand, caspase-8 activity was comparable in both patients and control groups. However, patients with PBMCs DNA fragmentation showed statistically significant higher activity than those without [p=0.023]. There was a statistically significant direct correlation between caspase-3 and caspase-8 activities in the patients groups [r=0.56,p<0.0001]

Conclusion: Chronic HCV infection is associated with PBMCs apoptosis irrespective of the presence of viremia. However, this apoptosis is independent on activation of either caspase-3 or caspase-8