Role of probiotics in managing various human diseases, from oral pathology to cancer and gastrointestinal diseases

Abstract

The imbalance of microbial composition and diversity in favor of pathogenic microorganisms combined with a loss of beneficial gut microbiota taxa results from factors such as age, diet, antimicrobial administration for different infections, other underlying medical conditions, etc. Probiotics are known for their capacity to improve health by stimulating the indigenous gut microbiota, enhancing host immunity resistance to infection, helping digestion, and carrying out various other functions. Concurrently, the metabolites produced by these microorganisms, termed postbiotics, which include compounds like bacteriocins, lactic acid, and hydrogen peroxide, contribute to inhibiting a wide range of pathogenic bacteria. This review presents an update on using probiotics in managing and treating various human diseases, including complications that may emerge during or after a COVID-19 infection.

Keywords: dysbiosis; gut microbiota; intestinal barrier; microbiome therapeutics; probiotics.

Figure 1

Mechanisms of the antimicrobial action of probiotics.

Figure 2

Mechanism of action of probiotics.

Figure 3

Schematically representation of bacteriocins mode of action. (A) The action of bacteriocins on Gram-negative targets, without the formation of pores. (B) The action of bacteriocins on Gram-positive targets, with the formation of membrane pores.

Figure 4

Effects of probiotics on SARS-CoV-2 infection. (A) The virus enters the body, infecting the respiratory system, including the lungs. (B) Via the gut-lung axis, SARS-CoV-2 virus induces dysbiosis in the lungs and colon. (C) Dietary supplementation with probiotics is effective in restoring eubiosis and relieving symptoms produced by SARS-CoV-2 infection. (D) Example of beneficial effect produced by the probiotic Lactobacillus plantarum, whose plantaricins D, E, F, and W inhibit the binding of viral spicular glycoprotein S (S1 subunit) to the cellular ACE2 receptor, they also and binding and inactivate RNA-dependent RNA polymerase (Nsp12), preventing transcription of the viral genome. (E) Different compounds secreted by probiotics may target some viral proteins, including Nsp3, Nsp5, Nsp12, Nsp13 and S, or some host cell-expressed proteins, ACE2, which serves as a receptor for viral attachment, and TMPRSS2, which facilitates activation of the viral glycoprotein S, with activation of the virus and its cell binding. (F) Probiotics participate in the modulation of barrier function and antiviral activity of epithelia, modulate innate immune response, antigen processing and presentation by antigen-presenting cells via MHC or HLA I and II molecules, and cellular and humoral mediated immunity.