Wiesława Rudnicka

Serological indicators of Helicobacter pylori infection in adult dyspeptic patients and healthy blood donors.

The levels of IgM, IgG and IgA antibodies reacting with two Helicobacter pylori antigens (glycine acid extract (GE) and a recombinant CagA protein) were determined in the sera from adult dyspeptic patients, positive (H.p.(+)) or negative (H.p.(‐)) for H. pylori urease/culture, and from healthy blood donors. All sera were also examined against GE by Western blot (immunoblot) technique. Similar levels of anti‐GE IgG were detected in the sera from all H.p.(+) and almost all H.p.(‐) patients and from over 40% of the healthy volunteers. In contrast, higher levels of anti‐GE IgA were found in the sera from patients than that from healthy subjects, although such antibodies were not detected in the sera from 30% of the H.p.(+) patients. In general, our results suggest that a combination of ELISA and immunoblot may be more sensitive in the detection of H. pylori infection in dyspeptic patients than the examination of biopsy specimens by culturing or histology.

Detection of Phospholipase C in Nontuberculous Mycobacteria and Its Possible Role in Hemolytic Activity

ABSTRACT Phospholipase C plays a key role in the pathogenesis of several bacterial infections, for example, those caused by Clostridium perfringens and Listeria monocytogenes. Previous studies have reported multiple copies of plc genes homologous to Pseudomonas aeruginosa plcH andplcN genes encoding the hemolytic and nonhemolytic phospholipase C enzymes in the genomes of Mycobacterium tuberculosis, M. marinum, M. bovis, and M. ulcerans. In this study we analyzed the possible relationship between phospholipase C and hemolytic activity in 21 strains of nontuberculous mycobacteria representing nine different species. Detection of phospholipase C enzymatic activity was carried out using thin-layer chromatography to detect diglycerides in the hydrolysates of radiolabeled phosphatidylcholine. DNA sequences of M. kansasii and M. marinum homologous to the genes encoding phospholipase C from M. tuberculosis and M. ulcerans were identified by DNA-DNA hybridization and sequencing. Finally, we developed a direct and simple assay to detect mycobacterial hemolytic activity. This assay is based on a modified blood agar medium that allows the growth and expression of hemolysis of slow-growing mycobacteria. Hemolytic activity was detected in M. avium, M. intracellulare, M. ulcerans, M. marinum, M. tuberculosis, andM. kansasii mycobacteria with phospholipase C activity, but not in M. fortuitum. No hemolytic activity was detected inM. smegmatis, M. gordonae, and M. vaccae. Whether or not phospholipase C enzyme plays a role in the pathogenesis of nontuberculous mycobacterial diseases needs further investigation.

A link between Helicobacter pylori and/or Chlamydia spp. infections and atherosclerosis

Antibodies to Helicobacter pylori, Chlamydia spp. and Mycobacterium bovis were determined in patients with coronary heart disease, H. pylori-related dyspepsia, and tuberculosis, and healthy controls. Enzyme-linked immunosorbent assay was conducted with a glycine extract and CagA protein of H. pylori, chlamydial lipopolysaccharide and mycobacterial heat shock protein Hsp65. The prevalence of anti-glycine extract IgG in coronary heart disease patients was higher than in the tuberculosis group and controls, and the same as in dyspeptic patients. Anti-chlamydial IgG were more prevalent in the coronary heart disease group than in healthy subjects. There was no difference in the prevalence of anti-CagA IgG in the coronary heart disease group and controls or anti-Hsp65 IgG in the patients with coronary heart disease, dyspepsia, tuberculosis, and controls. Anti-glycine extract IgA (like anti-glycine extract IgG) were more prevalent in the coronary heart disease group than in the healthy group. The highest anti-glycine extract IgG/IgA and anti-chlamydial IgG titers were more frequent in coronary heart disease patients as compared with controls. Infections with H. pylori and Chlamydia spp. and enhanced production of antibodies to these pathogens may predispose to human atherosclerosis.

Detection of specific Helicobacter pylori DNA and antigens in stool samples in dyspeptic patients and healthy subjects

In this study stool samples from dyspeptic patients and healthy subjects were used for detection of specific Helicobacter pylori antigens and DNA by immunoenzymatic test (PPHpSA) and semi‐nested PCR (ureA‐PCR), respectively. The H. pylori status was estimated by invasive endoscopy‐based rapid urease test and histology or noninvasive urea breath test (UBT), and by serology (ELISA, Western blot). The coincidence of H. pylori‐negative invasive tests or UBT and negative antigen or DNA stool tests was very high (mean 95%). The PPHpSA results were found positive for 56% and ureA‐PCR for 26% of individuals with H. pylori infection confirmed by invasive tests or UBT. The detection of specific H. pylori antigens and especially DNA in feces is not sufficient as a one‐step diagnosis of H. pylori infection.

The role of heparan sulphate-binding activity of Helicobacter pylori bacteria in their adhesion to murine macrophages.

The aim of this study was to determine the role of heparan sulphate (HS)‐binding activity of Helicobacter pylori microbes in their adhesion to and ingestion by inflammatory peritoneal macrophages. Two H. pylori strains expressing sialic acid‐specific haemagglutinins but differing in the expression of heparan sulphate‐binding capacity were chosen for investigation. The attachment to an ingestion by macrophages of the H. pylori bacteria were estimated by ELISA using anti‐H. pylori antibodies. The adhesion of both H. pylori strains could be inhibited by pretreatment of the bacteria with heparin (H), HS or fetuin, as well as by preincubation of the macrophages with heparinase or neuraminidase. However, detailed analysis of the data on the inhibition of bacterial adhesion to macrophages led to the conclusion that the attachment of H. pylori 25 bacteria, which expressed a high heparan sulphate binding, was mainly determined by HS‐binding structures. In contrast, the adhesion to macrophages of H. pylori bacteria 17874 microbes, which expressed a weak heparan sulphate binding, was more dependent on the exhibition of sialic acid‐dependent haemagglutinins. The described variation in H. pylori bacterial surface structures mediating their adhesion to macrophages could suggest a similar variation in bacterial adhesion to stomach mucosa and maybe in the pathogenicity of H. pylori strains.

Interleukin 18 (IL-18) as a target for immune intervention

Interleukin 18 (IL-18) is a pleiotropic cytokine involved in the regulation of innate and acquired immune response. In the milieu of IL-12 or IL-15, IL-18 is a potent inducer of IFN-gamma in natural killer (NK) cells and CD4 T helper (Th) 1 lymphocytes. However, IL-18 also modulates Th2 and Th17 cell responses, as well as the activity of CD8 cytotoxic cells and neutrophils, in a host microenvironment-dependent manner. It is produced by various hematopoietic and nonhematopoietic cells, including dendritic cells and macrophages. In an organism, bioactivity of the cytokine depends on the intensity of IL-18 production, the level of its natural inhibitory protein - IL-18BP (IL-18 binding protein) and the surface expression of IL-18 receptors (IL-18R) on the responding cells. This review summarizes the biology of the IL-18/IL-18BP/IL-18R system and its role in the host defense against infections. The prospects for IL-18 application in immunotherapeutic or prophylactic interventions in infectious and non-infectious diseases are discussed.

Helicobacter pylori antigens as potential modulators of lymphocytes' cytotoxic activity

Helicobacter pylori (H.p) colonizes human gastric mucosa and causes gastric and duodenal ulcer disease or gastric cancer. Various H.p compounds may modulate the host immune response in regards to tolerance of the infection or disease development. The aim of this study was to determine whether H.p lipopolysaccharide (LPS) and glycine acid extract antigens (GE) or E. coli LPS influence the cytotoxic activity of peripheral blood lymphocytes from H.p infected – H.p (+) or uninfected – H.p (−) individuals, in the presence or absence of exogenous interleukin (IL)12. Individual H.p status was defined by the urea breath test. Lymphocytes, stimulated or not with H.p, and control antigens, with or without IL‐12, were used as effector cells and epithelial HeLa cells as targets. The cytotoxicity of lymphocytes was expressed as the percentage of dead target cells unable to reduce tetrazolium salt. The supernatants from HeLa/lymphocyte cultures were used for detection of the cellular cytotoxicity markers granzyme B and caspase 8. The natural cytotoxic activity of lymphocytes from H.p (+) was less than that of H.p (−) donors. This may have been due to fewer natural killer cells of CD3−CD56+Nkp46+ phenotype in H.p (+) in comparison to H.p (−) subjects. H.p GE and standard E. coli LPS enhanced the cytotoxicity of lymphocytes towards target cells whereas H.p LPS downregulated this activity. The decrease in lymphocyte cytotoxicity in response to H.p LPS correlated with a lack of IL‐2 and IL‐12 production, inhibition of interferon‐γ production, and low IL‐10 secretion by mononuclear leukocytes. IL‐12 significantly enhanced the natural as well as H.p LPS and H.p GE driven cytotoxic capacity of lymphocytes. In conclusion, H.p LPS may negatively modulate natural cytotoxic activity and cytokine secretion by immunocompetent cells and thus be involved in the maintenance of infection and development of gastric pathologies.

Interaction of Helicobacter pylori with C-Type Lectin Dendritic Cell-Specific ICAM Grabbing Nonintegrin

In this study we asked whether Helicobacter pylori whole cells and lipopolysaccharide (LPS) utilize sugar moieties of Lewis (Le) antigenic determinants to interact with DC-SIGN (dendritic cell specific ICAM grabbing nonintegrin) receptor on dendritic cells (DCs). For this purpose the soluble DC-SIGN/Fc adhesion assay and the THP-1 leukemia cells with induced expression of DC-SIGN were used. We showed that the binding specificity of DC-SIGN with H. pylori LeX/Y positive whole cells and H. pylori LPS of LeX/Y type was fucose dependent, whereas in LeXY negative H. pylori strains and LPS preparations without Lewis determinants, this binding was galactose dependent. The binding of soluble synthetic LeX and LeY to the DC-SIGN-like receptor on THP-1 cells was also observed. In conclusion, the LeXY dependent as well as independent binding of H. pylori whole cells and H. pylori LPS to DC-SIGN was described. Moreover, we demonstrated that THP-1 cells may serve as an in vitro model for the assessment of H. pylori-DC-SIGN interactions mediated by LeX and LeY determinants.

Monocyte Signal Transduction Receptors in Active and Latent Tuberculosis

The mechanisms that promote either resistance or susceptibility to TB disease remain insufficiently understood. Our aim was to compare the expression of cell signaling transduction receptors, CD14, TLR2, CD206, and β2 integrin LFA-1 on monocytes from patients with active TB or nonmycobacterial lung disease and healthy individuals with M.tb latency and uninfected controls to explain the background of the differences between clinical and subclinical forms of M.tb infection. A simultaneous increase in the expression of the membrane bound mCD14 receptor and LFA-1 integrin in patients with active TB may be considered a prodrome of breaking immune control by M.tb bacilli in subjects with the latent TB and absence of clinical symptoms.

ANTI-LEWIS X ANTIBODY AND LEWIS X-ANTI-LEWIS X IMMUNE COMPLEXES IN HELICOBACTER PYLORI INFECTION

A molecular similarity of Lewis antigens expressed by Helicobacter pylori bacteria and those present in human gastric mucosa has been recognised as a cause of autoimmunity involved in the pathogenesis of chronic type B gastritis and gastric and duodenal ulcers. In this study, the expression of Lewis X determinants was found on 56% of H. pylori strains isolated from patients with chronic gastritis/gastroduodenitis. Anti-Lewis X IgG as well as Lewis X-anti-Lewis X IgG complexes were detected in the sera from patients and even more frequently in the sera from healthy blood donors producing antibodies against surface antigens of H. pylori. It suggested that the initial H. pylori-induced lesions were independent of anti-Lewis X antibody production. When H. pylori bacteria expressing Lewis X antigen were treated with anti-Lewis X monoclonal antibody (mAb) of IgM isotype, they were more susceptible to ingestion by polymorphonuclear leukocytes (PMN) than untreated bacteria. This fact may lead us to believe that anti-Lewis X antibody limits the growth of H. pylori on gastric mucosa.