The Role of Microbial Metabolites in Cancer and Inflammatory Diseases: Interaction with the Immune System

Microbiota is an aggregate of microorganisms that live in mammals including humans. These microorganisms, which include bacteria, viruses and fungi, reside in large numbers in the human intestine. Microbial metabolites resulting from microbiota play an important role in various types of cancer, including colorectal cancers, prostate, ovaries, and other types of cancers, and in various inflammatory diseases such as Inflammatory bowel disease (IBD), chronic kidney disease, cardiovascular diseases, etc. Types of microbial metabolites include reboxamycin, trimethylamine oxide (TMAO), lactacystine, and short-chain fatty acids which include butyrate, acetate, and propionate. All of these microbial metabolites play an important role in the physiological activity of the body and in inflammatory and cancerous diseases. Among various microbial metabolites, short-chain fatty acids have been studied and their role in immune cells, inflammatory diseases such as inflammatory bowel disease and cancers, is more pronounced than other microbial metabolites. In this regard, immune cells, especially those of acquired immunity, such as regulatory T-lymphocytes, play an important role in suppressing inflammation caused by inflammatory diseases and contribute to microbial metabolites in maintaining intestinal hemostasis. Microbial metabolites are effective elements in the development of gastrointestinal hemostasis and prevent unwanted inflammation after microbial infections, pathogens or any inflammatory disorders as far as possible. Microbial metabolites can help eliminate tumor cells by induction of apoptosis and specific mechanisms that will be discussed in this article. This review looks at the role of microbial metabolites in cancer and inflammatory diseases, especially IBD, and their association with the immune system.