New immunobiotics from highly proteolytic Lactobacillus delbrueckii strains: their impact on intestinal antiviral innate immune response

ELEAN, M.D.; ALBARRACIN, L.; CATALDO, P.G.; LONDERO, A. ; KITAZAWA, H.; SAAVEDRA, L.; VILLENA, J.; HEBERT, E. M.

Beneficial Microbes

Wageningen Academic Publishers

Año: 2020

Proteolytic starter cultureswith intrinsic immunomodulatory activities are desirably features for thedevelopment of functional foods, which would significantly reduce the cost oftheir production (one-strain starter) having an additional beneficial effect onthe host. In this work, Lactobacillusdelbrueckii strains were selectedaccording to their ability to efficiently hydrolyze β-casein and to modulatethe immune system. Among 36 strains evaluated, the highest proteolyticactivities were found for L. delbrueckiisubsp. lactis CRL581 and L. delbrueckii subsp. bulgaricus CRL656. The immunomodulatoryeffect of both strains and their β-casein hydrolysates (CRL581 and CRL656hydrolysates, respectively) were studied in a murine model. Balb/c mice werefed lactobacilli or their hydrolysates for three days. One day after the lastlactobacilli or hydrolysate treatments, mice were challenged with the TLR3agonist poly(I:C) by intraperitoneal injection. Before and after poly(I:C)challenge the phagocytic and microbicidal activity of peritoneal macrophages,intestinal IgA, cytokine profile, and histological analysis of intestine wereanalyzed. L. delbrueckii subsp. lactis CRL581 significantly increasedthe activation of peritoneal macrophages as well as the levels of intestinalIgA, IL-10 and IFN-γ when compared to untreated controls. In addition, theCRL581 strain was able to significantly reduce the intestinal inflammatorydamage triggered by TLR3 activation. L.delbrueckii CRL581 increased the levels ofIL-10, IFN-γ and IFN-β,and reduced TNF-αand IL-6 concentrations in the intestine of poly(I:C)-challenged mice. No immunomodulatoryeffects were observed for the CRL656 strain or for the CRL581 or CRL656 hydrolysates.The results of this work show that the technologically relevant and high proteolyticstrain L. delbrueckii CRL581 is ableto beneficially modulate the intestinal innate antiviral immune response.Although further studies with the CRL581 strain are required to corroborate anddeepen its immunological effects, this bacterium is an interesting alternativefor the development of new functional foods with antiviral capabilities.