Effects of Metabolites Derived From Gut Microbiota and Hosts on Pathogens

Abstract

Intestinal metabolites participate in various physiological processes, including energy metabolism, cell-to-cell communication, and host immunity. These metabolites mainly originate from gut microbiota and hosts. Although many host metabolites are dominant in intestines, such as free fatty acids, amino acids and vitamins, the metabolites derived from gut microbiota are also essential for intestinal homeostasis. In addition, some metabolites are only generated and released by gut microbiota, such as bacteriocins, short-chain fatty acids, and quorum-sensing autoinducers. In this review, we summarize recent studies regarding the crosstalk between pathogens and metabolites from different sources, including the influence on bacterial development and the activation/inhibition of immune responses of hosts. All of these functions would affect the colonization of and infection by pathogens. This review provides clear ideas and directions for further exploring the regulatory mechanisms and effects of metabolites on pathogens.

Lactobacillus acidophilus and L. plantarum improve health status, modulate gut microbiota and innate immune response of marron (Cherax cainii)

“…Modulation of gut microbiota and their interactive networks results in production of several types of metabolites, vitamins and antimicrobial agents that affect largely on the host physiology and immune response [48][49][50] . The gut microbes of freshwater fish are commonly dominated by phyla Proteobacteria, Firmicutes, Bacteroidetes, Actinobacteria, and Fusobacteria 51,52 .…”

“…Briefly, the dissected transverse segments (~1 mm long) of intestinal specimens were bathed immediately in 3% glutaraldehyde containing 0.1 M cacodylate buffer followed by overnight (24 h) incubation at 4 °C. Samples were then rinsed briefly with cacodylate buffer and PBS prior to secondary fixation using 1% OsO4, followed by three consecutive washes in deionized distilled water for 5 min, followed by dehydration in ethanol (50,70,95 and 100% at 250 W, 5 min each). The samples were dried by washing in a series of 50%, 75% and 100% (twice) hexamethyldisilizane (HMDS) in ethanol solutions for 5 min.…”

Nutritional Status and the Influence of the Vegan Diet on the Gut Microbiota and Human Health

“…Indeed, low-fiber, high-protein, and high-fat diets have been documented to increase both intestinal inflammation and permeability by altering the translocation of bacterial populations and metabolites that modulate inflammation [69]. In addition, metabolites derived from gut microbiota including bacteriocins, SCFAs, microbial amino acids, and vitamins seem to play a vital role in activating the intestinal immune response thus defending against external pathogens [70]. Recently, the term "metabolic endotoxemia" was introduced to describe a significant increase in bacterial lipopolysaccharide (LPS) plasma levels observed both in animals and humans in high-fat diets [71,72].…”

DJ-1 (Park7) affects the gut microbiome, metabolites and the development of innate lymphoid cells (ILCs)

“…Thus, metabolic stress induced by malonate and trimethylamine could be involved in the neurodegenerative process slowly in DJ-1 −/− mice potentially generated from bacterial metabolism or colon tissue. The vast majority of amino acids in the intestines are derived from the metabolism of ingested dietary proteins, host tissue proteins or the conversion of other nitrogenous substances, whereas a small amount of amino acids is de novo synthesized by the gut bacteria 101 . Amino acids, such as glutamine function as a double-edged sword for gut health as they can sponsor the expression of pathogenic virulence genes as well as protect against disease 101 .…”