Association of adenosine deaminase, superoxide dismutase, and catalase activities with Helicobacter pylori

Crosstalk Between DNA Damage and Inflammation in the Multiple Steps of Gastric Carcinogenesis

Over the last years, intensive investigations in molecular biology and cell physiology extended tremendously the knowledge about the association of inflammation and cancer. In frame of this paradigm, the human pathogen Helicobacter pylori triggers gastritis and gastric ulcer disease, and contributes to the development of gastric cancer. Mechanisms, by which the bacteria-induced inflammation in gastric mucosa leads to intestinal metaplasia and carcinoma, are represented in this review. An altered cell-signaling response and increased production of free radicals by epithelial and immune cells account for the accumulation of DNA damage in gastric mucosa, if infection stays untreated. Host genetics and environmental factors, especially diet, can accelerate the process, which offers the opportunity of intervention based on a balanced nutrition. It is supposed that inflammation might influence stem- or progenitor cells in gastric tissue predisposing for metaplasia or tumor relapse. Herein, DNA is strongly mutated and labile, which restricts therapy options. Thus, the understanding of the mechanisms that underlie gastric carcinogenesis will be of preeminent importance for the development of strategies for screening and early detection. As most gastric cancer patients face late-stage disease with a poor overall survival, the development of multi-targeted therapeutic intervention strategies is a major challenge for the future.

Adenosine: Direct and Indirect Actions on Gastric Acid Secretion

Composed by a molecule of adenine and a molecule of ribose, adenosine is a paradigm of recyclable nucleoside with a multiplicity of functions that occupies a privileged position in the metabolic and regulatory contexts. Adenosine is formed continuously in intracellular and extracellular locations of all tissues. Extracellular adenosine is a signaling molecule, able to modulate a vast range of physiologic responses in many cells and organs, including digestive organs. The adenosine A1, A2A, A2B, and A3 receptors are P1 purinergic receptors, G protein-coupled proteins implicated in tissue protection. This review is focused on gastric acid secretion, a process centered on the parietal cell of the stomach, which contains large amounts of H⁺/K⁺-ATPase, the proton pump responsible for proton extrusion during acid secretion. Gastric acid secretion is regulated by an extensive collection of neural stimuli and endocrine and paracrine agents, which act either directly at membrane receptors of the parietal cell or indirectly through other regulatory cells of the gastric mucosa, as well as mechanic and chemic stimuli. In this review, after briefly introducing these points, we condense the current body of knowledge about the modulating action of adenosine on the pathophysiology of gastric acid secretion and update its significance based on recent findings in gastric mucosa and parietal cells in humans and animal models.

Stimulation of gastric acid secretion by rabbit parietal cell A2B adenosine receptor activation

Adenosine modulates different functional activities in many cells of the gastrointestinal tract; some of them are believed to be mediated by interaction with its four G protein-coupled receptors. The renewed interest in the adenosine A2B receptor (A2BR) subtype can be traced by studies in which the introduction of new genetic and chemical tools has widened the pharmacological and structural knowledge of this receptor as well as its potential therapeutic use in cancer and inflammation- or hypoxia-related pathologies. In the acid-secreting parietal cells of the gastric mucosa, the use of various radioligands for adenosine receptors suggested the presence of the A2 adenosine receptor subtype(s) on the cell surface. Recently, we confirmed A2BR expression in native, nontransformed parietal cells at rest by using flow cytometry and confocal microscopy. In this study, we show that A2BR is functional in primary rabbit gastric parietal cells, as indicated by the fact that agonist binding to A2BR increased adenylate cyclase activity and acid production. In addition, both acid production and radioligand binding of adenosine analogs to isolated cell membranes were potently blocked by selective A2BR antagonists, whereas ligands for A1, A2A, and A3 adenosine receptors failed to abolish activation. We conclude that rabbit gastric parietal cells possess functional A2BR proteins that are coupled to Gs and stimulate HCl production upon activation. Whether adenosine- and A2BR-mediated functional responses play a role in human gastric pathophysiology is yet to be elucidated.

Serum adenosine deaminase activity in cutaneous anthrax

BACKGROUND

Adenosine deaminase (ADA) activity has been discovered in several inflammatory conditions; however, there are no data associated with cutaneous anthrax. The aim of this study was to investigate serum ADA activity in patients with cutaneous anthrax.

MATERIAL AND METHODS

Sixteen patients with cutaneous anthrax and 17 healthy controls were enrolled. We measured ADA activity; peripheral blood leukocyte, lymphocyte, neutrophil, and monocyte counts; erythrocyte sedimentation rate; and C reactive protein levels.

RESULTS

Serum ADA activity was significantly higher in patients with cutaneous anthrax than in the controls (p<0.001). A positive correlation was observed between ADA activity and lymphocyte counts (r=0.589, p=0.021) in the patient group.

CONCLUSIONS

This study suggests that serum ADA could be used as a biochemical marker in cutaneous anthrax.

Mn-SOD and CuZn-SOD polymorphisms and interactions with risk factors in gastric cancer

AIM

To investigate the effects of superoxide dismutase (SOD) polymorphisms (rs4998557, rs4880), Helicobacter pylori (H. pylori) infection and environmental factors in gastric cancer (GC) and malignant potential of gastric precancerous lesions (GPL).

METHODS

Copper-zinc superoxide dismutase (SOD1, CuZn-SOD)-G7958A (rs4998557) and manganese superoxide dismutase (SOD2, Mn-SOD)-Val16Ala (rs4880) polymorphisms were genotyped by SNaPshot multiplex polymerase chain reaction (PCR) in 145 patients with GPL (87 cases of gastric ulcer, 33 cases of gastric polyps and 25 cases of atrophic gastritis), 140 patients with GC and 147 healthy controls. H. pylori infection was detected by immunoblotting analysis.

RESULTS

The SOD1-7958A allele was associated with a higher risk of gastric cancer [odds ratio (OR) = 3.01, 95% confidence intervals (95% CI): 1.83-4.95]. SOD2-16Ala/Val genotype was a risk factor for malignant potential of GPL (OR = 2.04, 95% CI: 1.19-3.49). SOD2-16Ala/- genotype increased the risk of gastric cancer (OR = 2.85, 95% CI: 1.66-4.89). SOD1-7958A/- genotype, SOD2-16Ala/- genotype, alcohol drinking, positive family history and type I H. pylori infection were associated with risk of gastric cancer, and there were additive interactions between the two genotypes and the other three risk factors. SOD2-16Ala/Val genotype and positive family history were associated with malignant potential of GPL and jointly contributed to a higher risk for malignant potential of GPL (OR = 7.71, 95% CI: 2.10-28.22). SOD1-7958A/- genotype and SOD2-16Ala/- genotype jointly contributed to a higher risk for gastric cancer (OR = 6.43, 95% CI: 3.20-12.91).

CONCLUSION

SOD1-7958A/- and SOD2-16Ala/-genotypes increase the risk of gastric cancer in Chinese Han population. SOD2-16Ala/-genotype is associated with malignant potential of GPL.

A study of oxidative stress parameters in anti-helicobacter pylorus immunoglobulin g positive and negative gastric cancer patients

PURPOSE

Helicobacter pylorus (HP) is a Gram-negative spiral-shaped microaerophilic bacterium, which colonizes in the gastric mucosa of humans. The gastric human pathogen HP causes chronic gastritis and ulcers, and has a strong relationship with gastric cancer. The aim of this study was to determine advanced oxidation protein products (AOPP) levels, activities of myeloperoxidase (MPO) and catalase (CAT) in two groups.

MATERIALS AND METHODS

For this aim, one group included 30 patients with gastric cancer (Group 1) and the other included 30 subjects with non-gastric cancer and Anti-HP immunoglobulin (Ig) G antibody positive (group 2). Anti-HP IgG antibody test values were found as positive in fifty percent of group 1 and all of the group 2 patients.

RESULTS

Significantly increased AOOP levels were found in group 1 (p < 0.05) compared to group 2. There were no significant differences between the groups in regard to activities of MPO and CAT. In addition, AOPP level, MPO and CAT activities were similar among the Anti-HP IgG positive and negative subgroups of group 1 patients.

CONCLUSION

The result of this study indicated that gastric cancer patients were characterized by increased protein oxidation, whereas there was no significant difference in oxidative stress parameters and antioxidant enzyme activity between the Anti-HP IgG positive and negative gastric cancer patients.