Genetics studies in ischaemic stroke

Pien-Tze-Huang, a Chinese patent formula, attenuates NLRP3 inflammasome-related neuroinflammation by enhancing autophagy via the AMPK/mTOR/ULK1 signaling pathway

NLRP3 inflammasome is a key mediator in ischemic stroke-induced neuroinflammation and subsequent brain injury. Our previous study demonstrated the potent activity of Pien-Tze-Huang (PTH), a well-known Chinese patent formula, in reducing mitochondria-mediated neuronal apoptosis in cerebral ischemia/reperfusion impaired rats. This study aims to elucidate the mechanistic action of PTH related to neuroinflammation in LPS-induced BV2 microglial cells and cerebral ischemia/reperfusion impaired rats. BV2 cells were stimulated with LPS for 12 h and treated with PTH with various concentrations. Modulation by PTH of relevant genes (IL-6, IL-1β, IL-18, TNF-α, COX-2 and iNOS mRNA) and proteins (NLRP3 inflammasome, autophagy and AMPK/mTOR/ULK signaling) was analyzed by real-time PCR and western blot, respectively. Similar analyses were conducted in middle cerebral artery occlusion rat model including neurological deficit, infarct volume, microglial activation, and key genes and proteins in modulating autophagy and NLRP3. Our results showed that PTH significantly inhibited the production of key proinflammatory mediators and protein expressions of NLRP3 and caspase-1 p20 in LPS induced BV2 cells. It also enhanced the autophagy response by modulating the key autophagy proteins via AMPK/mTOR/ULK related pathway. The reduced inflammatory responses and NLRP3 expressions by PTH were partially blocked by the autophagy inhibitor (3-MA) and AMPK blocker (compound C). In rats, PTH significantly reduced infarct size, suppressed microglial activation, and improved neuron deficit. It also promoted autophagy and reduced NLRP3 activity. Our study demonstrated that PTH inhibited NLRP3 inflammasome-mediated neuroinflammation, which was associated with enhanced autophagy via AMPK/mTOR/ULK1 pathway in vitro and in vivo.

Two Novel SNPs in the PLCL2 Gene Associated with Large Artery Atherosclerotic Stroke Identified by Fine-Mapping

A genome-wide association study (GWAS) reported that the single nucleotide polymorphism (SNP) rs4618210 in the PLCL2 gene is related to myocardial infarction (MI) in the Japanese population, but no study has examined the correlation of PLCL2 with ischemic stroke (IS). The present study was designed to investigate whether the genetic variation in PLCL2 is associated with large artery atherosclerotic (LAA) stroke in a Han Chinese population. Tagging SNPs (tSNPs) of the PLCL2 gene were determined by a fine-mapping strategy and were genotyped by improved multiplex ligation detection reaction (iMLDR) technology in 669 LAA stroke patients and 668 healthy controls. A logistic regression model was used to analyze the associations between genetic variation at PLCL2 and the risk of LAA stroke. Two SNPs were significantly associated with the risk of LAA stroke after adjusting for potential confounders: for rs4685423, the AA genotype and CA genotype decreased the risk of LAA stroke compared with the CC genotype (multivariate-adjusted, P = 0.001); for rs4618210, the AA genotype and GA genotype decreased the risk of LAA stroke compared with the GG genotype (multivariate-adjusted, P = 0.007). In addition, haplotype analysis indicated that compared with haplotype TTT, haplotype TAT decreased the risk of LAA stroke in block 2 (adjusted OR, 0.706; 95% CI, 0.550-0.907; P = 0.006). The analysis of SNP-SNP interactions showed that rs4685423 was the most influential contributor to LAA stroke risk. SNPs rs4685423 and rs4618210 in the PLCL2 gene may be related to the risk of LAA stroke in Han Chinese.

An rs13293512 polymorphism in the promoter of let-7 is associated with a reduced risk of ischemic stroke

The expression of let-7 family members was differentiated in ischemic stroke (IS), functioning as an important regulating molecular in the pathophysiology of stroke. We hypothesized that genetic polymorphism in the promoters of let-7 family may be associated with the risk of IS. To test this hypothesis, we investigated the association of the rs10877887 and rs13293512 in the promoters of let-7 family with the susceptibility to IS. A hospital-based case-control study was performed. The rs10877887 genotype was determined by using a polymerase chain reaction-restriction fragment length polymorphism assay, and the rs13293512 genotype was determined by using a TaqMan assay. We found that the rs13293512CC genotype was associated with a reduced risk of IS (CC vs. TT: adjusted OR = 0.43, 95 % CI 0.26-0.71; dominant model: adjusted OR = 0.70, 95 % CI 0.49-0.98; recessive model: adjusted OR = 0.45, 95 % CI, 0.28-0.73). Stratification analysis showed that the rs10877887TT carriers had a higher level of total cholesterol compared to rs10877887TC/CC carriers (P = 0.03). Combined analysis showed that the rs10877887TC/CC and rs13293512TC/CC genotypes had a reduced risk of IS risk (adjusted OR = 0.58, 95 % CI 0.36-0.95). Our findings suggest that the rs13293512 polymorphism may be a protective factor for the development of IS.

Genome-wide association study identifies a variant in HDAC9 associated with large vessel ischemic stroke

Genetic factors have been implicated in stroke risk, but few replicated associations have been reported. We conducted a genome-wide association study (GWAS) for ischemic stroke and its subtypes in 3,548 affected individuals and 5,972 controls, all of European ancestry. Replication of potential signals was performed in 5,859 affected individuals and 6,281 controls. We replicated previous associations for cardioembolic stroke near PITX2 and ZFHX3 and for large vessel stroke at a 9p21 locus. We identified a new association for large vessel stroke within HDAC9 (encoding histone deacetylase 9) on chromosome 7p21.1 (including further replication in an additional 735 affected individuals and 28,583 controls) (rs11984041; combined P = 1.87 × 10(-11); odds ratio (OR) = 1.42, 95% confidence interval (CI) = 1.28-1.57). All four loci exhibited evidence for heterogeneity of effect across the stroke subtypes, with some and possibly all affecting risk for only one subtype. This suggests distinct genetic architectures for different stroke subtypes.