Serological evidence of association between <i>Helicobacter pylori</i> infection and coronary artery disease

Abstract

Background: Studies have reported relationship between chronic  Helicobacter pylori infection and coronary artery disease (CAD). The  cytotoxin-associated gene A product (CagA) is an immunodominant protein which indicates infection with virulent H. pylori strains. Significant  associations of CagA-positive H. pylori strains with coronary artery disorders have been widely reported. H. pylori is also known to produce different heat shock proteins (HSPs) which can stimulate the production of specific  antibody against microbial proteins and capable of eliciting autoimmune reaction against human tissue expressing HSPs such as vascular  endothelial cells. The objectives of this study are to investigate the  association between H. pylori and CagA with coronary atherosclerosis and CAD, and to determine the possible role of H. pylori HSP60 protein in increasing the risk of CAD development.

Methods: This study included 70 patients with stable angina and 70 age and gender-matched controls. Each group was evaluated by clinical history, physical examination, cardiac echocardiography (ECHO) and electrocardiography (ECG) with and without exercise. Fasting blood glucose, total cholesterol (TC), low density lipoprotein (LDL), high density lipoprotein (HDL) and triglycerides (TG) were estimated by automated enzymatic methods. H. pylori IgG, CagA IgG and HSP60 IgG were measured by enzyme-linked immunosorbent assay (ELISA) for both groups.

Results: The seroprevalence of H. pylori infection was high in both groups; 75.7% in case and 68.6% in control (p=0.346). Serum IgG levels were significantly higher for CagA (p=0.028) and HSP60 (p<0.001) in cases than in controls. There was significant association between H. pylori and CagA IgGs in cases (p=0.007) but no association in controls (p=0.700). Higher HSP60 IgG level was significantly associated with both positive H. pylori IgG (p<0.001) and CagA IgG (p<0.001) in cases but no significant association was found with H. pylori (p=0.815) or CagA (p=0.332) IgG levels in the control group. Serum values were significantly higher for TC (p<0.001), TG (p<0.001) and LDL (p=0.004) while value for HDL was significantly lower (p<0.001) in H. pylori IgG-positive subjects (case and control).

Conclusion: There is serological evidence that H. pylori infection may pose a significant risk factor for CAD. Since H. pylori can be eliminated by specific treatment, this may be a good preventive approach for CAD.

Key words: H. pylori, coronary artery disease, CagA, HSP60, serology.