Remote ischemic postconditioning protects the brain from focal ischemia/reperfusion injury by inhibiting autophagy through the mTOR/p70S6K pathway.

OBJECTIVE: Remote ischemic postconditioning (RIPostC) has been recognized as an applicable strategy for protecting against cerebral ischemia/reperfusion (I/R) injury. This study was performed to examine the effect of RIPostC on cerebral I/R and to explore its underlying mechanism. METHODS: Healthy male SD rats (N = 36) were assigned randomly into 3 groups of 12 each: sham group, I/R model group and RIPostC group. Animal models were performed by filament insertion for 2 h with middle cerebral artery occlusion(MCAO) followed by 24 h of reperfusion. RIPostC was induced by 15 min occlusion of femoral arteries followed by 15 min of reperfusion for 3 cycles at the beginning of middle cerebral artery reperfusion. The neurological deficits, infarct size and brain edema were determined. Autophagy was examined by transmission electron microscopy (TEM). The protein levels of microtubule-associated protein light chain 3 (LC3-II), mammalian target of rapamycin (mTOR), serine/threonine kinase p70S6 kinase (p70S6K), and their phosphorylation (p-mTOR and p-p70S6K) in the brain tissue of the rats were determined by western blotting. RESULTS: Our results suggested that RIPostC significantly reduced I/R-induced brain injury, as exhibited by a significantly decreased infarct size, mitigated brain edema and improved neurological deficits. RIPostC also significantly reduced the LC3-II/LC3-I ratio and protein expression of Beclin 1. Much less severe neuronal injury and fewer autophagosomes were observed by TEM in the RIPostC group. CONCLUSIONS: These results suggest that RIPostC attenuates cerebral I/R injury by inhibiting autophagy through the activation of the mTOR/p70S6K signaling pathway.

Cyclooxygenase-2 genetic polymorphism and stroke subtypes in Chinese.

BACKGROUND: Cyclooxygenase-2 (COX-2) catalyzes the formation of prostaglandins that contribute to the inflammation in atherosclerosis. The aim of the present study was to investigate the relationship between two polymorphisms (-1195G>A and -765G>C) in the COX-2 gene and subtypes of ischemic stroke in a Chinese population. METHODS: Genomic DNA of 224 patients with large artery atherosclerosis (LAA), 329 patients with small vessel occlusion (SVO), and 450 controls were genotyped for the COX-2 1195G>A (rs689466) and -765G>C (rs20417) polymorphisms using polymerase chain reaction-restriction fragment length polymorphism. Chi-square test and logistic regression analysis were performed for association analysis. RESULTS: The frequencies of variant allele with -1195G>A and -765G>C polymorphisms were 0.46 and 0.22, respectively. The -1195GA genotype and 1195A allele carriers were identified independently to be related with ischemic stroke (adjusted OR = 1.51, 95 % CI: 1.09-2.10, P = 0.02; OR = 1.45, 95 % CI: 1.06-1.97, P = 0.02) and SVO (adjusted OR = 1.57, 95 % CI: 1.07-2.30, P = 0.02; OR = 1.50, 95 % CI: 1.05-2.16, P = 0.03). In contrast, the 1195G>A polymorphism was not associated with LAA. No relationship between the -765G>C polymorphism and risk of either ischemic stroke was observed. The linkage disequilibrium analysis showed that -1195G>A and -765G>C SNPs are moderate linkage disequilibrium in this study population (D' = 0.72, r (2) = 0.16). Compared with G-1195-G-765 haplotype, the haplotype of A-1195-G-765 showed significant increased risk of ischemic stroke (OR = 1.27, 95 % CI: 1.05-1.54, P = 0.02) and SVO (OR = 1.27, 95 % CI: 1.02-1.58, P = 0.03) but not LAA. CONCLUSIONS: In conclusion, we found that -1195G>A polymorphism and A-1195-G-765 haplotype of COX-2 were associated with susceptibility to ischemic stroke in a Chinese population. The effects were confined to SVO among the stroke subtypes rather than to LAA.

Cyclooxygenase 2 genetic polymorphism may increase the risk of developing leukoaraiosis in Chinese.

Cyclooxygenase-2 (COX-2) is a key enzyme involved in the conversion of arachidonic acid into prostaglandins, which are important mediators of inflammation. To clarify the role of inflammation in the pathogenesis of cerebral small vessel disease (SVD), we investigate the possible modulating effect of the functional COX-2 polymorphisms -1195G > A (rs689466) and -765G > C (rs20417) on the risk for development of cerebral SVD in a Chinese population. Genomic DNA of 116 patients with lacunar infarction (LI), 334 patients with leukoaraiosis (LA) and 450 control subjects was genotyped for the COX-2 -1195G > A and -765G > C polymorphisms using polymerase chain reaction-restriction fragment length polymorphism. Distribution of genotypes and haplotypes in patients and controls were compared. The genotype distribution of the -765G > C polymorphism was not different between the patients with LI or LA and the control group. The 1195A allele carriers was identified independently to be related with LA (adjusted OR = 1.41, 95 % confidence interval (CI) = 1.09-2.10, P = 0.03) but not associated with LI. The linkage disequilibrium analysis showed that -1195G > A and -765G > C SNPs are moderate linkage disequilibrium in this study population (D' = 0.70, r(2) = 0.16). Compared with G-1195-G-765 haplotype, the haplotype of A-1195-G-765 showed significantly increased the risk of LA (OR = 1.24, 95 % CI = 1.10-1.55, P = 0.04) but not LI. In conclusion, we found that -1195G > A polymorphism and A-1195-G-765 haplotype of COX-2 were associated with susceptibility to LA in a Chinese population.

The haplotype of the TGFß1 gene associated with cerebral infarction in Chinese.

BACKGROUND: Transforming growth factor beta1 (TGFß1) is a multifunctional cytokine involved in inflammation and pathogenesis of atherosclerosis. The aim of the present study was to investigate the relationship between human TGFß1 gene +869T>C (rs1800470), -509C>T (rs1800469) single nucleotide polymorphisms (SNPs) and haplotypes and cerebral infarction (CI) in a Chinese population. METHODS: The genetic association study was performed in 450 Chinese patients (306 male and 144 female) with CI and 450 control subjects (326 male and 124 female). TGFß1 gene +869T>C and -509C>T polymorphisms were identified with amplification refractory mutation system polymerase chain reaction and DNA sequencing method. RESULTS: The individual SNPs analysis showed the +869T and -509C in an additive model (+869T vs +869C; -509 C vs T), +869TT genotype in a recessive model (TT vs TC+CC) and 509CC genotype in a dominant model (CC+ CT vs TT) were identified to be related to CI (P<0.05). +869T>C and -509C>T SNPs were in strong linkage disequilibrium (d'=0.87, R2=0.75). Haplotype analysis showed that +869C/-509T haplotype was associated with a significant decreased risk of CI (OR= 0.86, 95%CI, 0.70-0.92; P=0.007). Furthermore,+869T/-509C haplotype was associated with a significant increased risk of CI (OR=1.31, 95%CI, 1.10-2.03; P=0.019). CONCLUSIONS: The results of this study indicate that polymorphisms and the haplotypes in the TGFß1 gene might be genetic markers for CI in the Chinese population.

TGF-beta 1 codon 10 polymorphism is associated with cerebral SVD.

BACKGROUND: To clarify the role of inflammation in the pathogenesis of cerebral small vessel disease (SVD), we investigated whether the gene encoding transforming growth factor-beta 1(TGF-beta 1) is a risk factor for cerebral SVD as a whole, and for two different SVD subtypes. METHODS: TGF-beta 1 codon10 (T+29C) genotype was determined in 441 Chinese patients (313 male and 128 female) with cerebral SVD and 450 control subjects (326 male and 124 female). Cerebral SVD patients were retrospectively classified into two groups based on neuroimaging findings: lacunar infarction group with 112 patients and ischaemic leukoaraiosis group with 329 patients. RESULTS: Subjects carrying TT homozygote were susceptible to cerebral SVD [adjusted odds ratio (OR) =1.44, 95% confidence interval (CI), 1.05-1.98; P=0.026]. Further analysis of SVD subtypes revealed a moderate association with the ischaemic leukoaraiosis group [OR= 1.60, 95% CI, 1.14-2.25; P=0.007]. CONCLUSIONS: Codon 10 of TGF-beta 1 might be a risk factor for SVD, specifically in ischaemic leukoaraiosis phenotype.

TGF-ß1 869T/C polymorphism and ischemic stroke: sex difference in Chinese.

BACKGROUND: Inflammation plays a pivotal role in the pathogenesis of atherosclerosis and of cerebrovascular complications. Transforming growth factor-ß (TGF-ß) is a pleiotropic cytokine with a central role in inflammation. To investigate whether polymorphisms of the TGF-ß1 gene can modify the risk of ischemic stroke (IS) in Chinese population, we conduct this hospital-based, case-control study. METHODS: Transforming growth factor-ß1 genotype was determined in 450 Chinese patients (306 male and 144 female) with IS and 450 control subjects (326 male and 124 female). RESULTS: Subjects carrying 869TT were susceptible to IS (odds ratio [OR] =1.58; P=0.003). Further analysis of IS data partitioned by gender revealed the female-specific association with 869T/C (OR=2.64; P=0.001). CONCLUSIONS: Findings suggest that the TT genotype of 869T/C might be a risk factor of IS in Chinese, especially in females.

Endothelial NO synthase gene polymorphisms and risk of ischemic stroke: a meta-analysis.

Polymorphisms in the endothelial nitric oxide synthase (eNOS) gene may influence the risk of ischemic stroke, but data from published studies with individually low statistical power are conflicting. To evaluate the role of eNOS gene polymorphisms in ischemic stroke, we considered all available studies in a meta-analysis. Case-control studies evaluating the association between the G894T, 4b/a polymorphisms and ischemic stroke were searched in MEDLINE, EMBASE, HuGEnet, CBMdisc and CNKI up to December 2008. Pooled odds ratios (ORs) with 95% confidence intervals (CIs) from random- and fixed-effect models were calculated. Data were available for 5516 cases and 6150 controls from 18 studies. We found that homozygosity for the 4a allele of the eNOS gene was not associated with increase in the risk of ischemic stroke (OR, 1.67; 95% CI, 0.81-3.45). A marginal association was observed for homozygosity for the 894T allele with ischemic stroke (OR, 1.14; 95% CI, 0.99-1.31). This analysis provides strong evidence that the eNOS 4b/a gene polymorphisms is not associated with ischemic stroke, the G894T polymorphisms might be associated with ischemic stroke. Further research is warranted to clarify the relevance of G894T polymorphisms to ischemic stroke.

Meta-analysis of the ACE gene polymorphism in cerebral infarction.

BACKGROUND: The angiotensin-1 converting enzyme (ACE) gene is known to have two polymorphic alleles insertion/deletion (I/D). People with the DD genotype have been shown to be at greater risk of cerebral infarction, but only in some studies. Identification of cerebral infarction susceptibility genes and quantification of associated risks have been hampered by conflicting results from underpowered case-control studies. This meta-analysis was made to look specifically into the genetics of cerebral infarction among Han Chinese population. METHODS: Genetic associations studies published from January 1, 1990 to December 30, 2007 were collected from databases of MEDLINE, EMBASE, CBM and CNKI. Data were extracted using standardised forms and pooled odds ratios (ORs) with 95% confidence intervals (CIs) were calculated. RESULTS: Twenty-nine original case-control studies of Han Chinese population, comprising 3654 patients with cerebral infarction and 3058 controls were included in the meta-analysis. Using the random effects model, the pooled ORs of ACE DD genotype VS ID+ II was 1.91 (95% CI 1.56 to 2.34, P<0.00001). CONCLUSIONS: These data suggest that the ACE DD genotype may be a risk factor for cerebral infarction in Han Chinese population. A large scale case-control study is needed to clarify the functional effect of the polymorphism of the ACE I/D gene in the pathogenesis of cerebral infarction in Han Chinese population.