Cancro gástrico: Para além da infecção por Helicobacter pylori

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Cancro gástrico: Para além da infecção por Helicobacter pylori

Sexta, 28.09.2018

O cancro do estômago é um dos mais incidentes e mortais no mundo. A infecção por Helicobacter pylori tem um papel fundamental nas fases iniciais do processo que leva ao desenvolvimento de cancro. Neste estudo, os autores mostram que há uma alteração no perfil do microbioma gástrico de doentes com com gastrite crónica para doentes com cancro do estômago. O microbioma dos doentes com cancro é disbiótico, apresentando diminuição da diversidade bacteriana, bem como diminuição da abundância de H. pylori, em paralelo com aumento da abundância de outras espécies de bactérias. Os autores também mostram que o microbioma gástrico dos doentes com cancro tem potencial genotóxico. A descoberta do envolvimento de bactérias, para além de H. pylori, no desenvolvimento de cancro gástrico, poderá vir a ter impacto no acompanhamento clínico de doentes com lesões pré-cancerosas e contribuir para a prevenção do cancro do estômago.

Este estudo enquadra-se num projecto financiado pela Worldwide Cancer Research (https://www.worldwidecancerresearch.org/project/what-role-do-bacteria-in-our-stomach-play-in-the-development-of-cancer/).

 

Autores e Afiliações:

Rui M Ferreira1,2, Joana Pereira-Marques1,2,3, Ines Pinto-Ribeiro1,2,4, Jose L Costa1,2,4, Fatima Carneiro1,2,4,5, Jose C Machado1,2,4, Ceu Figueiredo1,2,4

1i3S – Instituto de Investigação e Inovação em Saúde, Universidade do Porto; 

2Ipatimup – Institute of Molecular Pathology and Immunology of the University of Porto;

3Institute of Biomedical Sciences Abel Salazar (ICBAS), University of Porto;

4Faculty of Medicine, University of Porto;

5Department of Pathology, Centro Hospitalar São João; Porto, Portugal.

 

Abstract:

Objective: Gastric carcinoma development is triggered by Helicobacter pylori. Chronic H. pylori infection leads to reduced acid secretion, which may allow the growth of a different gastric bacterial community. This change in the microbiome may increase aggression to the gastric mucosa and contribute to malignancy. Our aim was to evaluate the composition of the gastric microbiota in chronic gastritis and in gastric carcinoma.

Design: The gastric microbiota was retrospectively investigated in 54 patients with gastric carcinoma and 81 patients with chronic gastritis by 16S rRNA gene profiling, using next-generation sequencing. Differences in microbial composition of the two patient groups were assessed using linear discriminant analysis effect size. Associations between the most relevant taxa and clinical diagnosis were validated by real-time quantitative PCR. Predictive functional profiling of microbial communities was obtained with PICRUSt.

Results: The gastric carcinoma microbiota was characterised by reduced microbial diversity, by decreased abundance of Helicobacter and by the enrichment of other bacterial genera, mostly represented by intestinal commensals. The combination of these taxa into a microbial dysbiosis index revealed that dysbiosis has excellent capacity to discriminate between gastritis and gastric carcinoma. Analysis of the functional features of the microbiota was compatible with the presence of a nitrosating microbial community in carcinoma. The major observations were confirmed in validation cohorts from different geographic origins.

Conclusions: Detailed analysis of the gastric microbiota revealed for the first time that patients with gastric carcinoma exhibit a dysbiotic microbial community with genotoxic potential, which is distinct from that of patients with chronic gastritis.

 

Revista: Gut, Volume 67, issue 2, 2018

 

Link: https://gut.bmj.com/content/67/2/226