Microbiota and the Immune System—Actors in the Gastric Cancer Story

Abstract

Gastric cancer remains one of the most commonly diagnosed cancers in the world, with a relatively high mortality rate. Due to the heterogeneous course of the disease, its diagnosis and treatment are limited and difficult, and it is associated with a reduced prognosis for patients. That is why it is so important to understand the mechanisms underlying the development and progression of this cancer, with particular emphasis on the role of risk factors. According to the literature data, risk factors include: changes in the composition of the stomach and intestinal microbiota (microbiological dysbiosis and the participation of Helicobacter pylori), improper diet, environmental and genetic factors, and disorders of the body’s immune homeostasis. Therefore, the aim of this review is to systematize the knowledge on the influence of human microbiota dysbiosis on the development and progression of gastric cancer, with particular emphasis on the role of the immune system in this process.

The role of microbiota in gastric cancer: A comprehensive review

“…101 In addition, microorganisms can enhance the efficacy of PD-1 inhibitor immunotherapy by modulating glycerophospholipid metabolism and SCFA metabolism. 102,103 Moreover, some bacteria have been reported to be associated with reactions and toxicity or nonresponse/lack of response. Enterococcus hirae and Lactobacillus johnsonii, for example, can enhance the cyclophosphamide (CTX) response by influencing the promotion of the Th1 spleen memory and the activation of the Th17 response.…”

Intratumor microbiome: selective colonization in the tumor microenvironment and a vital regulator of tumor biology

“…Last, the tumor microenvironment is usually immune suppressive, which may protect the bacteria against the clearance by immune system 51 . Different immune subtypes may thus select different bacteria 52–54 . In colon cancer models, depletion of neutrophils led to increased number of bacteria in tumors and proliferation of tumor cells accompanied by increased tumor cell DNA damage and an inflammatory response mediated by interleukin‐17 (IL‐17), 55 indicating that the intratumor microbiome is under the active surveillance of immune system and that the immune suppressive microenvironment may contribute to the colonization of bacteria.…”

“… 51 Different immune subtypes may thus select different bacteria. 52 , 53 , 54 In colon cancer models, depletion of neutrophils led to increased number of bacteria in tumors and proliferation of tumor cells accompanied by increased tumor cell DNA damage and an inflammatory response mediated by interleukin‐17 (IL‐17), 55 indicating that the intratumor microbiome is under the active surveillance of immune system and that the immune suppressive microenvironment may contribute to the colonization of bacteria. Conversely, neutrophilic inflammation seems to be permissive for tumor‐promoting bacteria growth in squamous cell vulvar carcinoma, 33 indicating the context‐dependent role of immune cells.…”

Revisión bibliográfica: cáncer gástrico: estrategias quirúrgicas actuales y futuras

“…La pérdida de una copia del gen CDH1 causa cáncer gástrico difuso hereditario (HDGC), una herencia autosómica dominante en la que las células malignas pasan por debajo del revestimiento del estómago y posteriormente hacen metástasis. (Majewski et al, 2022) La correlación entre los factores dietéticos y el riesgo de desarrollar CG ha sido ampliamente estudiada, estudios demuestran que las frutas y las verduras son protectoras contra Brazilian Journal of Health Review, Curitiba, v. 6, n. 1, p.1778-1789, jan./feb., 2023 el desarrollo de este, mientras que las carnes de animales asadas y al carbón, los alimentos conservados en sal y los alimentos ahumados aumentan la progresión de CG. (Kim et al, 2014) Los carcinógenos alimentarios podrían interactuar con las células epiteliales gástricas y provocar cambios en los genes y su expresión.…”