Postbiotics and host–microbe interactions

Postbiotics are defined as nonviable microbial cells or cell components that confer health benefits to the host. This term encompasses a diverse range of microbial by-products, such as short-chain fatty acids, exopolysaccharides, vitamins, teichoic acids, bacteriocins, cell surface proteins, organic acids, enzymes, and peptides, which are derived from the metabolic processes of live microorganisms. These components possess a spectrum of health-promoting properties, including antibacterial, antiinflammatory, antioxidant, anticarcinogenic, and immunomodulatory effects. They play a significant role in various physiological and immunological pathways, including immunomodulation, gene expression regulation, competitive binding of pathogens, fortification of the intestinal barrier, and modulation of carcinogenesis and pathogenic infections. Emerging scientific evidence suggests that postbiotics may offer a safer alternative to live microbial preparations, particularly in vulnerable populations such as immunocompromised patients, infants, and premature neonates. Although research on postbiotics is relatively nascent compared to that on prebiotics and probiotics, recent advancements in human microbiome studies have highlighted the profound potential impact of postbiotics on human health. The intricate and synergistic interactions between microbes and their host organisms underscore the complexity of these relationships. This chapter aims to delineate the pivotal role of postbiotics in mediating the intricate interactions between the microbiota and the host. It synthesizes the latest research findings on the mechanisms through which postbiotics exert their effects and the dynamic interplay between postbiotic compounds and host cellular pathways. As the investigation into postbiotics continues to unfold, it is poised to redefine our understanding of the microbial contribution to improved physiological function and overall host well-being.