Role of Lactobacillus reuteri in Human Health and Diseases

Abstract

Lactobacillus reuteri (L. reuteri) is a well-studied probiotic bacterium that can colonize a large number of mammals. In humans, L. reuteri is found in different body sites, including the gastrointestinal tract, urinary tract, skin, and breast milk. The abundance of L. reuteri varies among different individuals. Several beneficial effects of L. reuteri have been noted. First, L. reuteri can produce antimicrobial molecules, such as organic acids, ethanol, and reuterin. Due to its antimicrobial activity, L. reuteri is able to inhibit the colonization of pathogenic microbes and remodel the commensal microbiota composition in the host. Second, L. reuteri can benefit the host immune system. For instance, some L. reuteri strains can reduce the production of pro-inflammatory cytokines while promoting regulatory T cell development and function. Third, bearing the ability to strengthen the intestinal barrier, the colonization of L. reuteri may decrease the microbial translocation from the gut lumen to the tissues. Microbial translocation across the intestinal epithelium has been hypothesized as an initiator of inflammation. Therefore, inflammatory diseases, including those located in the gut as well as in remote tissues, may be ameliorated by increasing the colonization of L. reuteri. Notably, the decrease in the abundance of L. reuteri in humans in the past decades is correlated with an increase in the incidences of inflammatory diseases over the same period of time. Direct supplementation or prebiotic modulation of L. reuteri may be an attractive preventive and/or therapeutic avenue against inflammatory diseases.

Heat‐killed Lactobacillus reuteri and cell‐free culture supernatant have similar effects to viable probiotics during interaction with Porphyromonas gingivalis

“…In addition, we have shown that L reuteri cell‐free supernatant was as effective in inhibiting P gingivalis as living bacteria, suggesting that microbial growth reduction was mainly due to the substances produced by the probiotic. Besides reuterin, L reuteri strains produce a series of other antimicrobial substances, including lactic acid, acetic acid, ethanol, and reutericyclin . The literature has also shown the importance of the acidic environment in the interactions between L reuteri and other microorganisms .…”

“…The literature has also shown the importance of the acidic environment in the interactions between L reuteri and other microorganisms . Additional well‐studied metabolites such as histamine, vitamins, and exopolysaccharides contribute to L reuteri probiotic action and can be found in the culture supernatant . However, L reuteri metabolites are present in different concentrations in live bacterial suspension and in the supernatant, since special conditions of time and substrate addition (glycerol) were offered to the culture to prepare the supernatant.…”

“…Besides reuterin, L reuteri strains produce a series of other antimicrobial substances, including lactic acid, acetic acid, ethanol, and reutericyclin. 3,31,32 The literature has also shown the importance of the acidic environment in the interactions between L reuteri and other microorganisms. 33 Additional well-studied metabolites such as histamine, vitamins, and exopolysaccharides contribute to L reuteri probiotic action and can be found in the culture supernatant.…”

“…In the presence of glycerol, L reuteri can synthesize reuterin (β‐hydroxy propionaldehyde), a small compound with antimicrobial activity for a range of pathogens, including gram‐positive and gram‐negative bacteria, fungi, and parasites . Moreover, L reuteri inhibits the colonization of pathogenic microbes, influences the host microbiota composition, benefits the host immune system to reduce pro‐inflammatory cytokine production, and strengthens the intestinal barrier, decreasing microbial translocation from the gut lumen to the tissues …”

“…2 Moreover, L reuteri inhibits the colonization of pathogenic microbes, influences the host microbiota composition, benefits the host immune system to reduce proinflammatory cytokine production, and strengthens the intestinal barrier, decreasing microbial translocation from the gut lumen to the tissues. 3 In periodontics, after the use of L reuteri in patients with periodontitis or peri-implantitis, a decrease in probing depth, bleeding on probing, and decreased gingival and plaque index, or an increase in the clinical attachment level was found. [4][5][6][7][8][9][10][11][12][13] In both in vitro and in vivo studies, L reuteri inhibits the growth of Porphyromonas gingivalis.…”