We aimed to determine whether mycoplasmas are present in Korean chronic gastritis, and to understand their roles in gastric cancer tumorigenesis, because mycoplasmas resemble Helicobacter pylori in terms of ammonia production and induction of inflammatory cytokines in immune and non-immune cells. The presence and identity of mycoplasmas were assessed by semi-nested PCR and sequencing, and the results were compared with pathologic data. Fifty-six samples collected from Korean chronic gastritis patients were used for this study. Twenty-three (41.1%) were positive for mycoplasmas. Eighteen sequenced samples contained a single human mycoplasma or two mycoplasmas, which were identified as Mycoplasma faucium ( astric cancer can be caused by chronic Helicobacter pylori infection, which induces inflammatory cytokines and oxidative stress, and results in the accumulation of genetic alterations leading to transformation. However, only a proportion of H. pylori-positive patients develop a tumor, and it has been shown that vac A and cag A of H. pylori and host factors, such as single nucleotide polymorphisms (SNPs) in the promoter region of interleukin-1β (IL-1β) and IL-1β receptor antagonist (IL-1β Ra), are not related to gastric tumorigenesis [1][2][3][4] ; it therefore remains worthwhile to investigate other risk factors.Mycoplasmas are the smallest self-replicating bacteria. Although mycoplasmas are generally commensal parasites in humans, some species are real pathogens and are capable of causing a wide variety of diseases.5) Mycoplasmas present in the human oropharynx include Mycoplasma orale, M. salivarium, M. faucium, which produce ammonia and cause tissue damage, 6, 7) and M. fermentans, which induces inflammatory cytokines from macrophages 8) and epithelial cells. 9) Among them, M. salivarium and M. orale are major mycoplasmas found in throat specimens of adults, but M. faucium is relatively rare.
6)The presence of mycoplasmas in gastritis and gastrointestinal tumors has been reported. [10][11][12] These reports provoked concern about the epidemiological role of mycoplasmas in gastric cancer, though the fact that the identified species was of porcine origin, M. hyorhinis, was unexpected.10-12) Pathobiological similarities between mycoplasmas and H. pylori, and questions on additional risk factors in the tumorigenesis of Korean gastric cancer encouraged us to further investigate the detection and identification of mycoplasmas in chronic gastritis.
2)In this study, we investigated whether human mycoplasmas are associated with chronic gastritis by means of semi-nested PCR and direct sequencing. The results were then compared with pathologic data. Here, we report that human mycoplasmas are present in a high proportion of chronic gastritis (41.1%) cases, and the mycoplasma profiles are different from those of the oropharynx. In addition, mycoplasma-infected chronic gastritis recruits significantly more neutrophils than uninfected chronic gastritis (P<0.05), with no significant differences in the load of H. pylori (P>0....
