Genetic predisposition to ischaemic stroke by RAGE and HMGB1 gene variants in Chinese Han population

Target Gene-Based Association Study of High Mobility Group Box Protein 1 in Intracranial Aneurysms in Koreans

Objective: We investigated the effect of high mobility group box 1 (HMGB1) on intracranial aneurysms (IAs) by analyzing single-nucleotide polymorphisms (SNPs) based on genome-wide association study (GWAS) data. HMGB1 mRNA and protein expression levels in plasma were also analyzed. Methods: This study was a comprehensive analysis of a GWAS dataset, including 250 patients with IAs and 294 controls. The HMGB1 gene region was targeted within SNP rs3742305 ± 10 kbp. Multivariate logistic regression analysis determined its association with IAs after adjusting for relevant clinical factors. HMGB1 mRNA expression was analyzed in the plasma of 24 patients selected from the GWAS dataset. The HMGB1 protein was analyzed by Western blotting. Results: A total of seven polymorphisms, including rs1360485, rs185382445, rs2039338, rs1045411, rs3742305, rs2249825, and rs189034241, were observed. Two SNPs, including rs1045411 (UTR-3) and rs3742305 (intron), showed strong linkage disequilibrium (r2 = 0.99). However, none of the seven SNPs associated with IAs had an adjusted p-value of < 0.0016 on multiple comparison analysis. HMGB1 mRNA levels (2-ΔCt) did not differ significantly between patients with IAs and the control subjects [1.07 (1.00-1.15) in patients with IAs vs. 1.05 (0.94-1.12) in controls; p = 0.67)]. Also, no significant difference in the degree of plasma HMGB1 protein expression was seen between the two groups (p = 0.82). Conclusions: The number of SNPs associated with HMGB1 and the degree of HMGB1 mRNA and protein expression were not significantly different between patients diagnosed with IAs and the controls.

Polymorphisms of Calgranulin Genes and Ischemic Stroke in a Chinese Population

Background

The S100/calgranulin gene appears to modulate neuroinflammation following cerebral ischemia and could be a valuable biomarker for stroke prognosis, according to growing research. This study aimed at evaluating the correlation between calgranulin gene variants and susceptibility to ischemic stroke (IS) in the Southern Chinese population.

Methods

Using an enhanced multi-temperature ligase detection reaction genotyping, 310 IS patients and 324 age-matched healthy controls were genotyped to identify five calgranulin gene variants.

Results

According to the obtained results, the S100A8 rs3795391, rs3806232, and S100A12 rs2916191 variants were linked to a higher risk of IS, while the S100A9 rs3014866 variant was associated with a lower risk of IS. Moreover, the T-T-C-A-T, T-T-C-G-T, or C-C-C-G-C haplotypes have been linked to a greater risk of developing IS, according to haplotype analysis. The occurrence of the variant C allele there in S100A8 rs3795391, rs3806232, and S100A12 rs2916191 variants may impart a greater risk of stroke in the LAA subtype, according to further stratification by IS subtypes, while the T allele of the S100A9 rs3014866 variant may be linked to a reduced risk of stroke of all subtypes. Furthermore, patients with the variant C allele of the S100A8 rs3795391, rs3806232, and S100A12 rs2916191 variants presented with increased circulating S100A8 and S100A12 levels and larger infarct volumes relative to those with the major TT genotype.

Conclusion

Our findings suggest that calgranulin gene variants are linked to IS susceptibility, implying that the calgranulin gene may be a potential biomarker for IS prevention and personalized treatment.

AGER gene variant as a risk factor for juvenile idiopathic arthritis

BACKGROUND

The AGER gene encodes a cell surface multiligand receptor of advanced glycation end-products that is also capable of binding other molecules and is involved in numerous pathways related to inflammation, apoptosis, immunity and so on. In the present study, we aimed to investigate whether the AGER rs1035798 (G>A) intronic polymorphism, showing an association with multiple sclerosis and rheumatoid arthritis in adults, is related to juvenile idiopathic arthritis (JIA).

METHODS

Caucasian children from the Belarusian population were enrolled in the study. In total, there were 201 cases with JIA, 37 with juvenile systemic lupus erythematosus, 222 children with the articular syndrome of non-autoimmune etiology (positive control for JIA) and 365 negative controls (children without any autoimmune or inflammatory diseases). Genomic DNA samples from the patients and controls were genotyped by a real-time polymerase chain reaction.

RESULTS

A marked association of the homozygous AA rs1035798 genotype with JIA (p = 5 × 10^-4 ) was found. Allele A was also associated with JIA (p = 0.0058), as well as with the articular syndrome of non-autoimmune etiology (p = 0.0264). The highest frequencies of the AA genotype were found in the subgroups of JIA patients with polyarthritis or severe oligoarthritis. The AA genotype patients also had the smallest mean age of the JIA onset.

CONCLUSIONS

Our results demonstrate that the AGER rs1035798 AA genotype is a risk factor for JIA in Belarusian children. They also suggest a link between the AGER AA genotype and the risk of JIA early onset and severity. However, the functional relevance of the rs1035798 polymorphism is still unclear.

Association of DIAPH1 gene polymorphisms with ischemic stroke

DIAPH1 is a formin protein involved in actin polymerization with important roles in vascular remodeling and thrombosis. To investigate potential associations of DIAPH1 single-nucleotide polymorphisms (SNPs) with hypertension and stroke, 2,012 patients with hypertension and 2,210 controls, 2,966 stroke cases [2,212 ischemic stroke (IS), 754 hemorrhagic stroke (HS)] and 2,590 controls were enrolled respectively in the case-control study. A total of 4,098 individual were included in the cohort study. DIAPH1 mRNA expression was compared between 66 IS [43 small artery occlusion (SAO) and 23 large-artery atherosclerosis (LAA)] and 58 controls. Odds ratio (OR), hazard ratio (HR) and 95% confidence interval (CI) were calculated by logistic and cox regression analysis. Rs7703688 T>C variation was significantly associated with an increased risk of IS [OR (95% CI) was 1.721 (1.486-1.993), P=4.139×10^-12]. Association of rs7703688 with stroke risk was further validated in the cohort study [adjusted HRs (95% CIs) for additive and recessive models were 1.385 (1.001-1.918), P=0.049, and 2.882 (1.038-8.004), P=0.042, respectively)]. DIAPH1 mRNA expression was significantly downregulated in IS. In SAO stroke subtype, DIAPH1 expression has an increased trend among rs251019 genotypes (P_trend=0.048). These novel findings suggest that DIAPH1 variation contributes to genetic susceptibility to stroke risk, especially the SAO subtype of IS.

The Receptor for Advanced Glycation End Products (RAGE) and DIAPH1: Implications for vascular and neuroinflammatory dysfunction in disorders of the central nervous system

The Receptor for Advanced Glycation End Products (RAGE) is expressed by multiple cell types in the brain and spinal cord that are linked to the pathogenesis of neurovascular and neurodegenerative disorders, including neurons, glia (microglia and astrocytes) and vascular cells (endothelial cells, smooth muscle cells and pericytes). Mounting structural and functional evidence implicates the interaction of the RAGE cytoplasmic domain with the formin, Diaphanous1 (DIAPH1), as the key cytoplasmic hub for RAGE ligand-mediated activation of cellular signaling. In aging and diabetes, the ligands of the receptor abound, both in the central nervous system (CNS) and in the periphery. Such accumulation of RAGE ligands triggers multiple downstream events, including upregulation of RAGE itself. Once set in motion, cell intrinsic and cell-cell communication mechanisms, at least in part via RAGE, trigger dysfunction in the CNS. A key outcome of endothelial dysfunction is reduction in cerebral blood flow and increased permeability of the blood brain barrier, conditions that facilitate entry of activated leukocytes into the CNS, thereby amplifying primary nodes of CNS cellular stress. This contribution details a review of the ligands of RAGE, the mechanisms and consequences of RAGE signal transduction, and cites multiple examples of published work in which RAGE contributes to the pathogenesis of neurovascular perturbation. Insights into potential therapeutic modalities targeting the RAGE signal transduction axis for disorders of CNS vascular dysfunction and neurodegeneration are also discussed.

Association between RAGE variants and the susceptibility to atherosclerotic lesions in Chinese Han population

Receptor for advanced glycation end products (RAGE) is a major proinflammatory receptor and its role in atherosclerosis has only been emphasized recently. Increasing evidence has demonstrated an association between RAGE and the susceptibility to atherosclerosis development. Therefore, the role of RAGE in atherogenesis and the possible impact of genetic variations in RAGE on the atherosclerotic process in subjects with coronary artery disease (CAD) was investigated in the present study. The RAGE expression in carotid specimens was analyzed by immunohistochemistry and sequence variations of the RAGE gene selected from the Hapmap database were also screened. The plasma levels of S100 calcium binding protein B (S100B) were determined by ELISA. Immunohistochemical staining of tissue samples demonstrated an increased RAGE expression in atherosclerotic carotid plaques compared with that in normal arteries. Furthermore, compared with the corresponding wild-type genotype, the rs2269422 single-nucleotide polymorphism of RAGE was associated with the susceptibility of patients with CAD to atherosclerosis. Furthermore, reverse transcription polymerase chain reaction and western blot analyses indicated increased coronary artery RAGE mRNA levels and protein expression, respectively, in CAD patients vs. control subjects. Furthermore, the plasma levels of S100B in CAD patients that were carriers of the AA/AT genotype of the rs2269422 variant of RAGE was increased compared with that in TT genotype carriers; as this was also identified in control subjects, it may not be CAD-specific. The RAGE rs2269422 variant is therefore significantly associated with an increased occurrence of CAD in the present Han Chinese population. Thus, RAGE variants significantly impact the risk of CAD in Han Chinese subjects.