The Association Between Cytotoxin-associated Gene A And Ischemic Stroke

Objective Cytotoxin-associated gene A (CagA) is one of proteins produced by Helicobacter pylori which prompts a stronger pathogenicity. Chronic infection by Cytotoxin-associated gene A (CagA) has been regarded as a possible etiological factor for vascular diseases. There is contrasting evidence on the relevance of chronic infection by Cytotoxin-associated gene A (CagA) as a risk factor for ischemic stroke. The present study was done to systematically review the relationship between CagA and ischemic stroke. Methods We searched MEDLINE, EMbase and CJFD, VIP database, search the relevant case-control study with the time limit of January 1997 to July 2010, and then Meta-analyses were performed for the included studies using RevMan 5.0 software after strict screening. We also performed heterogeneity test, sensitivity analysis and publication bias assessment. Results Nine studies were included in this study consisting of 1045 patients with ischemia stroke and 1070 health controls, the results of Meta analysis showed the CagA-positive infection rate between case and control was statistically significant (OR=2.35,95% CI:1.96-2.82, P<0.01), CagA-positive and cerebral infarction subtypes showed that the correlation between Hp infection with CagA and Large artery atherosclerosis stroke was also significant(OR=2.95,95%CI:2.18-3.98, P<0.01); as aresult of the diversity of etiological factor in case-control study, further studies are given after the standardization of the case group, then total effect was recalculated, the results showed that significant differences still existed between the two groups(OR=2.60,95%CI:2.10-3.22, P<0.01), the relationship of CagA and Large artery atherosclerosis stroke are still apparent (OR=3.06, 95%CI:2.23-4.18, P<0.01). Conclusions 1) Hp with CagA-positive infection is a risk factor for stroke, especially for the Large artery atherosclerotic stroke.2) The strength of evidence in case-control studies are weak and more prospective studies are still needed to define whether the infection by CagA-positive H. pylori strains is to be considered a novel risk factor for stoke and its subtypes. Objective Cytotoxin-associated gene-A (CagA) is one of proteins produced by Helicobacter pylori which prompts a stronger patho-genicity. Chronic infection by more virulent H. pylori strains, bearing the cytotoxin-associated gene-A (CagA) antigen has been linked to extradi-gestive pathologies.There is contrasting evidence on the association with stroke. Therefore,we performed a case-control study to assess associat-ion between CagA-bearing strains of H. pylori, with different types of stroke. Methods The seroprevalence of anti-H. pylori IgG anti-bodies and anti-CagA antibodies were assessed by ELISA in 123 patients and 131control subjects without history of stroke and relevant vascular dise-ases.Analyses were stratified for etiologic stroke subtypes according to 2007 modified TOAST criteria (94 patients with AT,14 patients with CE, 12 patients with SAD).Risk factors for ischemic stroke were recorded in all subjects.Conditional logistic regression was used. Results A trend to-ward a higher CagA-IgG was observed in cases with respect to controls without reaching a statistical significance(39.8% vs 38.9%, OR:1.039,95%Cl:0.628-1.719).This result remained nonsignificant after adjusting for potential risk factors for Hp infection and known risk factors for ischemic stroke (OR:1.062,95%CI:0.595-1.895).Subgroup analyses yielded similar results in all etiologic stroke subtypes, with the result of multivariateanalysis:AT:OR=0.941,95%CI:0.491-1.803; CE: OR=1.176,95%CI:0.389-4.741; SAD:OR=2.391,95%CI:0.580-9.853. Conclusion Our case-control study dose not provide evidence of any strong association between CagA-bearing strains of H. pylori chronic infection and subgroups of ischemic stroke. There is still need for prospective studies investigating the contribution of CagA-bearing strains of H. pylori infection to stroke risk.