Alzheimer's disease and type 2 diabetes: the association study of polymorphisms in tumor necrosis factor-alpha and apolipoprotein E genes

Inherited Thrombophilia Associated With Ischemic Pediatric Stroke in Parent-Child Pairs

BACKGROUND

We aimed to examine inherited thrombophilia frequencies by extending genetic profile to previously rarely or not investigated polymorphisms in children with ischemic pediatric stroke (IPS) and their parents.

METHODS

The study included 33 children: 23 with perinatal arterial ischemic stroke (PAIS), eight with childhood arterial ischemic stroke (CAIS), and two with sinovenous thrombosis and their parents (33 mother-child, 12 father-child, and 12 mother-father-child pairs). Genotyping of FV-Leiden, FV-H1299R, FII-G20210A, β-fibrinogen-455G>A, FXIII-A-Val34Leu, PAI-1(4G/5G), HPA-1, MTHFR-C677T, MTHFR-A1298C, ACE(I/D), and APOE(ε2-4) was performed using CVD Strip assay (ViennaLab, Austria).

RESULTS

At least one and up to seven simultaneously present polymorphisms were observed in all children with IPS, mothers, and fathers. More than five simultaneously present polymorphisms were identified threefold more frequently in children with IPS (10 of 33; 30%) compared with the child control group (17 of 150; 11%), yielding a statistically significant difference between the two groups (odds ratio [OR] = 3.40; 95% confidence interval [CI] = 1.39 to 8.35; P = 0.012). Stronger association was revealed for PAIS (OR = 4.17; 95% CI = 1.55 to 11.29; P = 0.008) and CAIS subgroups (OR = 7.82; 95% CI = 1.79 to 34.20; P = 0.012). Complete match of polymorphisms was not identified in any parent-child pair. A partial match (one to four mutual polymorphisms) was found in 11 of 12 parent-child pairs where until three mutual polymorphisms was present in 11 of 12 (91.7%) father-child compared with 21 of 33 (63.6%) mother-child pairs.

CONCLUSIONS

According to obtained results the simultaneous presence of more than five polymorphisms is associated with a higher risk for IPS occurrence, suggesting the risk enhancement for PAIS in the presence of pregnancy complications or for CAIS in conjunction with maternal comorbidity and positive family history. The presence of up to three mutual polymorphisms more frequently in father-child than mother-child pairs suggests significant paternal contribution of inherited thrombophilia to increased risk of IPS.

IL-1β, IL-6, IL-10, and TNFα Single Nucleotide Polymorphisms in Human Influence the Susceptibility to Alzheimer's Disease Pathology

BACKGROUND

Neuroinflammation plays an important role in Alzheimer's disease (AD). During this process, activated microglia release pro-inflammatory cytokines such as interleukin (IL)-1α, IL-1β, IL-6, and tumor necrosis factor α (TNFα) that participate in neuron damage, but also anti-inflammatory cytokines (such as IL-10), which maintain homeostasis of immune response. Previous studies showed the association of IL-1α -889C/T (rs1800587), IL-1β-1473G/C (rs1143623), IL-6 -174C/G (rs1800795), IL-10 -1082G/A (rs1800896), and TNFα -308A/G (rs1800629) polymorphisms with AD.

OBJECTIVE

We aimed to investigate whether people with certain IL-1α, IL-1β, IL-6, IL-10, and TNFα genotypes in these polymorphisms are more prone to develop AD-related pathology, reflected by pathological levels of cerebrospinal fluid (CSF) AD biomarkers including amyloid-β1-42, total tau (t-tau), tau phosphorylated at Thr 181 (p-tau181), Ser 199 (p-tau199), and Thr 231 (p-tau231), and visinin-like protein 1 (VILIP-1).

METHODS

The study included 115 AD patients, 53 patients with mild cognitive impairment, and 11 healthy controls. The polymorphisms were determined using real-time polymerase chain reaction. Levels of CSF biomarkers were determined by enzyme-linked immunosorbent assay.

RESULTS

A significant increase in p-tau CSF levels was found in patients with the AA IL-10 -1082G/A and GG TNFα -308A/G genotypes, and in carriers of a G allele in IL-1β -1473C/G and IL-6 -174C/G polymorphisms. t-tau levels were increased in carriers of a G allele in IL-1β -1473C/G polymorphism. An increase in VILIP-1 levels was observed in patients with CG and GG IL-1β -1473C/G, GC IL-6 -174C/G, and GG TNFα -308A/G genotype.

CONCLUSION

These results suggest that persons carrying certain genotypes in IL10 (-1082G/A), IL1β (1473C/G), IL6 (-174C/G), and TNFIα (-308A/G) could be more vulnerable to development of neuroinflammation, and consequently of AD.

The association of tumor necrosis factor alpha, lymphotoxin alpha, tumor necrosis factor receptor 1 and tumor necrosis factor receptor 2 gene polymorphisms and serum levels with periodontitis and type 2 diabetes in Serbian population

OBJECTIVES

Aiming to show that periodontitis (PD) and type 2 diabetes (T2D) are bidirectionally related and potentially linked by inflammatory cytokines, we searched for association between -308 G/A Tumor necrosis factor-alpha (TNFα), +252A/G Lymphotoxin-alpha (LTα), +36A/G Tumor necrosis factor receptor 1 (TNFR1) and +676 T/G tumor necrosis factor receptor 2 (TNFR2) single nucleotide polymorphisms (SNPs) and: risk of PD or PD + T2D; periodontitis parameters in PD and PD + T2D; serum levels of cytokines/their receptors. Relationship between periodontal inflammation and serum cytokine/receptor levels was also assessed.

DESIGN

Subjects were stratified as: 57 healthy controls (HC); 58 PD; 65 PD + T2D. Sociodemographic, environmental, behavioral and periodontal clinical data were recorded. SNPs were genotyped using polymerase chain reaction-restriction fragment length polymorphism, while cytokines/receptors levels were quantified by enzyme-linked immunosorbent assay. Impact of periodontal inflammation was measured using periodontal inflamed surface area (PISA).

RESULTS

TNFα AA genotype showed protective effect in T2D + PD compared to PD, even adjusted for behavioral/environmental factors (OR 0.18; 95 %CI 0.037-0.886; p = 0.035). LTα AG heterozygotes had increased risk of PD (OR 3.27; 95 %CI 1.35-7.96; p = 0.016), while TNFR2 TG genotype had protective effect (OR = 0.44; 95 %CI 0.954-0.9794; p = 0.043). TNFR1 AA was predictor of periodontal pocket depth and clinical attachment loss in PD. Correlation between TNFR2 concentration and PISA was negative in PD, positive in PD + T2D.

CONCLUSIONS

None of the SNPs showed cross-susceptibility between PD and T2D. + 252A/G LTα and +676 T/G TNFR2 SNPs are associated with PD risk. Periodontal destruction in healthy individuals is influenced by TNFR1 genotype. Impact of periodontal on systemic inflammation is masked by T2D.

The association of TNF-α -308G/A and -238G/A polymorphisms with type 2 diabetes mellitus: a meta-analysis

Tumor necrosis factor-α (TNF-α) is involved in insulin resistance and has long been a candidate gene implicated in type 2 diabetes mellitus (T2DM), however the association between TNF-α polymorphisms -308G/A and -238G/A and T2DM remains controversial. The present study sought to verify associations between these polymorphisms and T2DM susceptibility using a meta-analysis approach. A total of 49 case-control studies were selected up to October 2018. Statistical analyses were performed by STATA 15.0 software. The odds ratios (ORs) and 95% confidence intervals were calculated to estimate associations. Meta-analyses revealed significant associations between TNF-α -308G/A and T2DM in the allele model (P=0.000); the dominant model (P=0.000); the recessive model (P=0.001); the overdominant model (P=0.008) and the codominant model (P=0.000). Subgroup analyses also showed associations in the allele model (P=0.006); the dominant model (P=0.004) and the overdominant model (P=0.005) in the Caucasian and in the allele model (P=0.007); the dominant model (P=0.014); the recessive model (P=0.000) and the codominant model (P=0.000) in the Asian. There were no associations between TNF-α -238G/A and T2DM in the overall and subgroup populations. Meta-regression, sensitivity analysis and publication bias analysis confirmed that results and data were statistically robust. Our meta-analysis suggests that TNF-α -308G/A is a risk factor for T2DM in Caucasian and Asian populations. It also indicates that TNF-α -238G/A may not be a risk factor for T2DM. More comprehensive studies will be required to confirm these associations.

The neuroprotective role of melatonin in neurological disorders

Melatonin is a neurohormone secreted from the pineal gland and has a wide-ranging regulatory and neuroprotective role. It has been reported that melatonin level is disturbed in some neurological conditions such as stroke, Alzheimer's disease, and Parkinson's disease, which indicates its involvement in the pathophysiology of these diseases. Its properties qualify it to be a promising potential therapeutic neuroprotective agent, with no side effects, for some neurological disorders. This review discusses and localizes the effect of melatonin in the pathophysiology of some diseases.

Bosnian study of APOE distribution (BOSAD): a comparison with other European populations

BACKGROUND

The ε2, ε3 and ε4 alleles of APOE gene have been associated with several diseases in different populations. Data on the frequency of alleles are used in both a clinical and evolutionary context. Although the data on frequency of these alleles are numerous, there are no reports for the population of Bosnia and Herzegovina.

AIM

To estimate the frequency of APOE alleles in a healthy Bosnian population and compare it to data for other European populations.

SUBJECTS AND METHODS

Overall, 170 unrelated Bosnian subjects (108 female and 62 male), aged 53.0 (±5.0) years were included in this study. Genotypes were determined by real-time PCR.

RESULTS

In our group the prevalence of heterozygotes E2/E3, E2/E4 and E3/E4 was 20.6%, 3.5% and 12.9%, respectively, while the prevalence of homozygotes E2/E2, E3/E3, E4/E4 was 0.6%, 61.2% and 1.2%, respectively, with a mean frequency of ε2, ε3 and ε4 alleles of 12.6%, 78.0% and 9.4%, respectively.

CONCLUSIONS

In studied European populations we observed a linear, gradually increasing trend in the frequency of ε4 allele from South to North (Pearson's test 0,7656, p value <0.00001), and the Bosnian population fits into this pattern perfectly.

APOE Genotypes Associate With Cognitive Performance but Not Cerebral Structure: Diabetes Heart Study MIND

OBJECTIVE

Dementia is a debilitating illness with a disproportionate burden in patients with type 2 diabetes (T2D). Among the contributors, genetic variation at the apolipoprotein E locus (APOE) is posited to convey a strong effect. This study compared and contrasted the association of APOE with cognitive performance and cerebral structure in the setting of T2D.

RESEARCH DESIGN AND METHODS

European Americans from the Diabetes Heart Study (DHS) MIND (n = 754) and African Americans from the African American (AA)-DHS MIND (n = 517) were examined. The cognitive battery assessed executive function, memory, and global cognition, and brain MRI was performed.

RESULTS

In European Americans and African Americans, the APOE E4 risk haplotype group was associated with poorer performance on the modified Mini-Mental Status Examination (P < 0.017), a measure of global cognition. In contrast to the literature, the APOE E2 haplotype group, which was overrepresented in these participants with T2D, was associated with poorer Rey Auditory Verbal Learning Test performance (P < 0.032). Nominal associations between APOE haplotype groups and MRI-determined cerebral structure were observed.

CONCLUSIONS

Compared with APOE E3 carriers, E2 and E4 carriers performed worse in the cognitive domains of memory and global cognition. Identification of genetic contributors remains critical to understanding new pathways to prevent and treat dementia in the setting of T2D.

TNF-alpha G308A polymorphism and the susceptibility to Alzheimer's disease: an updated meta-analysis

BACKGROUND AND AIMS

Tumor necrosis factor (TNF)-alpha G308A polymorphism has been reported in the association with susceptibility to Alzheimer's disease (AD); however, results have been contradictory. We conducted an updated meta-analysis to evaluate the role of TNF-alpha G308A in the occurrence of AD.

METHODS

Relevant articles were retrieved from online databases. The combined odds ratio, odds ratio in different genetic models, and the related 95% confidence intervals were calculated. Publication bias and homogeneity among individual studies were estimated. Subgroup analyses and sensitivity analyses were also performed.

RESULTS

In overall analyses, no risk of AD was associated with TNF-alpha G308A under different genetic models. However, in the subgroup analyses, a significant association between TNF-alpha G308A and AD risk was observed in Chinese. In addition, a significant protective effect of TNF-alpha -308A was found in the occurrence of AD among North European populations under a dominant model.

CONCLUSIONS

The result of this meta-analysis suggests that TNF-alpha G308A polymorphism may be associated with the increased risk of AD in Chinese and decreased risk of AD in northern European populations.

Genetic polymorphisms of cytokine genes in type 2 diabetes mellitus

Diabetes mellitus is a combined metabolic disorder which includes hyperglycemia, dyslipidemia, stroke and several other complications. Various groups all over the world are relentlessly working out the possible role of a vast number of genes associated with type 2 diabetes (T2DM). Inflammation is an important outcome of any kind of imbalance in the body and is therefore an indicator of several diseases, including T2DM. Various ethnic populations around the world show different levels of variations in single nucleotide polymorphisms (SNPs). The present review was undertaken to explore the association of cytokine gene polymorphisms with T2DM in populations of different ethnicities. This will lead to the understanding of the role of cytokine genes in T2DM risk and development. Association studies of genotypes of SNPs present in cytokine genes will help to identify risk haplotype(s) for disease susceptibility by developing prognostic markers and alter treatment strategies for T2DM and related complications. This will enable individuals at risk to take prior precautionary measures and avoid or delay the onset of the disease. Future challenges will be to understand the genotypic interactions between SNPs in one cytokine gene or several genes at different loci and study their association with T2DM.

Association of IL-6, TNF-α and IL-10 gene polymorphisms with type 2 diabetes mellitus

Type 2 diabetes mellitus (T2DM) is a metabolic pro-inflammatory disorder characterized by chronic hyperglycemia and increased levels of circulating cytokines suggesting a causal role of inflammation in its etiology. Polymorphism of cytokine genes including interleukin-6 (IL-6), tumour necrosis factor-α (TNF-α) and interleukin-10 (IL-10) were studied in T2DM patients as well as in normal healthy controls. Genomic DNA was isolated from both T2DM patients and controls followed by quantification and genotyping by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) using suitable primers. The genotypic, allelic and carriage rate frequency distribution in patients and controls were analyzed by SPSS (version 15.0). Odd ratios with 95 % confidence interval was determined to describe the strength of association by logistic regression model. Double and triple combinations of genotypes were analyzed by χ(2) test. Gene-gene interaction and linkage disequilibrium tests were performed using SHEsis software. Individually, IL-6, TNF-α and IL-10 did not show any association. In double combination, IL-6 -597 GA and TNF-α -308 GG genotypes increased the risk up to 21 times and in triple combination IL-6 -597 AA, TNF-α -308 GG and IL-10 -592 CA increased the risk of T2DM up to 314 times. In gene-gene interaction allele 'A' of all studied polymorphisms increased the risk of T2DM up to 1.41 times. Our results suggest that individuals having a haplotype combination of AA, GG and CA for IL-6, TNF-α and IL-10 gene polymorphisms will have higher susceptibility and be at greater risk of developing T2DM.

Melatonin in Alzheimer's disease

Alzheimer’s disease (AD), an age-related neurodegenerative disorder with progressive cognition deficit, is characterized by extracellular senile plaques (SP) of aggregated β-amyloid (Aβ) and intracellular neurofibrillary tangles, mainly containing the hyperphosphorylated microtubule-associated protein tau. Multiple factors contribute to the etiology of AD in terms of initiation and progression. Melatonin is an endogenously produced hormone in the brain and decreases during aging and in patients with AD. Data from clinical trials indicate that melatonin supplementation improves sleep, ameliorates sundowning and slows down the progression of cognitive impairment in AD patients. Melatonin efficiently protects neuronal cells from Aβ-mediated toxicity via antioxidant and anti-amyloid properties. It not only inhibits Aβ generation, but also arrests the formation of amyloid fibrils by a structure-dependent interaction with Aβ. Our studies have demonstrated that melatonin efficiently attenuates Alzheimer-like tau hyperphosphorylation. Although the exact mechanism is still not fully understood, a direct regulatory influence of melatonin on the activities of protein kinases and protein phosphatases is proposed. Additionally, melatonin also plays a role in protecting the cholinergic system and in anti-inflammation. The aim of this review is to stimulate interest in melatonin as a potentially useful agent in the prevention and treatment of AD.

A meta-analysis of the association between TNF-α -308G>A polymorphism and type 2 diabetes mellitus in Han Chinese population

Objective

A meta-analysis was applied to evaluate the associations between tumor necrosis factor-α (TNF-α) −308G>A (rs1800629) polymorphism and type 2 diabetes mellitus (T2DM).

Methods

Hardy-Weinberg equilibrium (HWE) was employed to test genetic equilibrium among the genotypes of the selected literature. Power analysis was performed with the Power and Sample Size Calculation (PS) program. A fixed or random effect model was used on the basis of heterogeneity. Publication bias was quantified and examined with the Begg's funnel plot test and Egger's linear regression test. The meta-analysis was performed with Review Manager 5.1 and Stata 11.0.

Results

There were 10 studies including 1425 T2DM patients and 1116 healthy control subjects involved in this meta-analysis. No significant publication bias was found in the studies. The pooled ORs (95% CIs) for TNF-α −308G>A of A vs. G allele and GA+AA vs. GG genotype were 1.63 (1.17–2.25) and 1.47 (1.17–1.85), respectively.

Conclusion

This meta-analysis result suggested that TNF-α −308G>A polymorphism was strongly associated with T2DM risk, and A allele at this locus might be a susceptibility allele for the development of T2DM in Han Chinese population.