Increased Risk of Atherosclerosis Is Confined to CagA-Positive Helicobacter pylori Strains

Abstract

Background and Purpose— Accumulating evidence indicates that a variety of infections contribute to the pathogenesis of atherosclerosis, but there is controversy concerning the impact of Helicobacter pylori infections in atherosclerosis. Methods— We evaluated seropositivity to H pylori and to its cytotoxin-associated gene A (CagA) product in a large, prospective, population-based study (n=684). Intima-media thickness and atherosclerosis of carotid arteries were thoroughly assessed by high-resolution duplex scanning. Results— In our study population, H pylori infections defined by seropositivity have no relationship with levels of classic cardiovascular risk factors or markers of systemic inflammation, except for elevated levels of immune reactions to mycobacterial heat shock protein 65. The latter showed a trend toward highest levels in those harboring virulent H pylori strains ( P =0.08). Common carotid artery intima-media thickness—both absolute values and changes between 1995 and 2000—were significantly enhanced in subjects seropositive to CagA but not in those infected with CagA-negative H pylori strains. There was a clear dose-response relation between anti-CagA antibodies and both intima-media thickness and atherosclerosis risk. Notably, the risk of atherosclerosis associated with CagA seropositivity was amplified by elevated C-reactive protein levels. Conclusions— Infections with virulent CagA-bearing H pylori strains may contribute to the pathogenesis of early atherosclerosis by aggravating immune-inflammatory reactions.