Antibodies crossreacting with human TNF-alfa receptor induced in the patients with coronary heart disease by Helicobacter pylori CagA positive strains

Abstract

Abstract Introduction Coronary heart disease (CHD) is associated with inflammation and atherosclerosis. The hypothesis of autoimmune origin of CHD has been suggested. Chronic infection with gastric pathogen Helicobacter pylori may induce antibodies, potentially autoreactive, due to molecular mimicry between H. pylori cytotoxin associated gene A (CagA) protein and tumor necrosis factor (TNF)-α receptor (TNFR). Purpose To evaluate presence of antibodies against synthetic c peptide (P1), which mimics the common sequence of TNFR and H. pylori CagA, in the sera of CHD patients and healthy donors (HD), uninfected or infected with H. pylori. Furthermore, guinea pigs (Caviae porcellus), sensitive to H. pylori infection, were used to confirm the induction of antibodies crossreacting with TNFR by this pathogen. Material and methods Serum samples from CHD patients infected with H. pylori CagA(+) strain (43) or H.pylori CagA(−) strain (12), and uninfected HD (16) without symptoms of gastritis or CHD were selected. Moreover, the serum samples from control (10) or H. pylori infected guinea pigs, 7, 28 and 60 days from inoculation were used (10, 20, 10, respectively). The H. pylori status in humans was confirmed by 13C urea breath testing and anti-H. pylori antibody production whereas in Cavia porcellus by histological examination of gastric tissue, detection of H. pylori antigens in stool as well as serum anti-H. pylori antibodies. The ELISA assay with the surface H. pylori antigens – glycine acid extract (GE), recombinant CagA (IRIS, Siena, Italy), synthetic P1 or P2 peptides (Lipopharm, Gdansk, Poland), with or without common CagA/TNFR sequence, respectively, were used for detection of antibodies. Complement activation by P1-anti-P1 IgG complexes was determined by complement fixation assay with sheep erythrocytes (SRBC) and anti-SRBC antibodies. Results :Anti-P1 IgG were detected only in CHD patients infected with H. pylori CagA(+) but not CagA(−) strain. Such antibodies were not detected in H. pylori uninfected HD. Anti-P1 IgG were found in the sera of Cavia porcellus infected with H. pylori, 7 and 28 but not 60 days from inoculation. This may suggest the clearance of such antibodies during the course of infection or their early deposition. The role of H. pylori in anti-P1 IgG induction was confirmed by deletion of such antibodies by absorption of sera, which were positive for anti-P1 IgG, with heat inactivated H. pylori. Anti-P1 IgG present in human and animal sera were biologically active. They formed the immune complexes (IC) with P1 in vitro, which were able to activate complement, suggesting a pro-inflammatory potential of such IC in vivo. Conclusions During H. pylori infection in CHD patients the CagA protein of this pathogen may induce antibodies cross reacting with TNFR. They can potentially increase the inflammatory response by IC dependent activation of complement or due to modulation of TNFR-driven cell signaling pathways. Funding Acknowledgement Type of funding source: Public Institution(s). Main funding source(s): Statutory Fund of University of Lodz, Poland