Cross-sectional study: CagA-positive Helicobacter pylori infection, acute coronary artery disease and systemic levels of B-type natriuretic peptide

Background B-type natriuretic peptide (BNP) determination is routinely used to evaluate the severity of congestive heart failure, a possible consequence of coronary artery disease (CAD). CAD originates from vascular atherosclerotic processes and is stimulated by inflammatory events, which may also be triggered by chronic bacterial infections. Aim To explore the effect of Helicobacter pylori infection upon systemic BNP, tumour necrosis factor-a (TNF-alpha) and interleukin-6 (IL-6) levels and linear homology between cardiac peptides and H pylori. Methods A group of 103 consecutive patients with a diagnosis of non-ST elevation acute CAD (ACAD) and no other concomitant pathology was examined. BNP was measured by a commercial solid-phase sandwich immunoradiometric assay. H pylori infection, CagA serological status and circulating levels of IL-6 and TNF-alpha, were determined by ELISA assays. Amino acid sequence homology between human cardiac and H pylori peptides was investigated by Basic Local Alignment Search Tool (BLAST) analysis. Results Circulating levels of BNP and IL-6, in pg/mL (interquartile difference), among infected patients with anti-CagA serum antibodies, respectively 781 (1899) and 37.7 (137.6), were significantly increased in respect to those measured in uninfected patients, respectively 325 (655) and 7.7 (23.5), (p<0.01 and p=0.025), and, with regard to BNP alone, also in patients infected by CagA negative H pylori strains, 305 (593), (p<0.01). TNF-a levels were raised in CagA positive in respect to uninfected patients. Tropomyosin and Ca2+ transporting ATPases showed strong similarities to H pylori proteins, suggesting the existence of molecular mimicry phenomena. Conclusions Chronic infection by H pylori expressing CagA correlates with high circulating levels of BNP and IL-6 in patients with ACAD.