Exopolysaccharides From Streptococcus thermophilus ST538 Modulate the Antiviral Innate Immune Response in Porcine Intestinal Epitheliocytes

Hiroya Mizuno; Kae Tomotsune; Md Aminul Islam; Ryutaro Funabashi; Leonardo Albarracin; Wakako Ikeda-Ohtsubo; Hisashi Aso; Hideki Takahashi; Katsunori Kimura; Julio Villena; Yasuko Sasaki; Haruki Kitazawa

doi:10.3389/fmicb.2020.00894

Exopolysaccharides From Streptococcus thermophilus ST538 Modulate the Antiviral Innate Immune Response in Porcine Intestinal Epitheliocytes

Front Microbiol. 2020 May 19:11:894. doi: 10.3389/fmicb.2020.00894. eCollection 2020.

Authors

Hiroya Mizuno^{1

2}, Kae Tomotsune^{1

2}, Md Aminul Islam^{1

2}, Ryutaro Funabashi^{1

2}, Leonardo Albarracin^{1

3

4}, Wakako Ikeda-Ohtsubo^{1

2}, Hisashi Aso^{2

5}, Hideki Takahashi^{6

7}, Katsunori Kimura⁸, Julio Villena^{1

3}, Yasuko Sasaki⁹, Haruki Kitazawa^{1

2}

Affiliations

¹ Food and Feed Immunology Group, Laboratory of Animal Products Chemistry, Graduate School of Agricultural Science, Tohoku University, Sendai, Japan.
² Livestock Immunology Unit, International Education and Research Center for Food and Agricultural Immunology (CFAI), Graduate School of Agricultural Science, Tohoku University, Sendai, Japan.
³ Laboratory of Immunobiotechnology, Reference Centre for Lactobacilli (CERELA-CONICET), San Miguel de Tucumán, Argentina.
⁴ Scientific Computing Laboratory, Computer Science Department, Faculty of Exact Sciences and Technology, National University of Tucuman, San Miguel de Tucumán, Argentina.
⁵ Laboratory of Animal Health Science, Graduate School of Agricultural Science, Tohoku University, Sendai, Japan.
⁶ Laboratory of Plant Pathology, Graduate School of Agricultural Science, Tohoku University, Sendai, Japan.
⁷ Plant Immunology Unit, International Education and Research Center for Food and Agricultural Immunology (CFAI), Graduate School of Agricultural Science, Tohoku University, Sendai, Japan.
⁸ Food Microbiology and Function Research Laboratories, Meiji Co., Ltd., Kanagawa, Japan.
⁹ Laboratory of Fermented Foods, Graduate School of Agriculture, Meiji University, Kanagawa, Japan.

Abstract

It was reported that exopolysaccharides (EPSs) from lactobacilli are able to differentially modulate mucosal antiviral immunity. Although research has described the ability of EPSs derived from Streptococcus thermophilus to modulate the mucosal immune system, their impact on antiviral immunity was less explored. In this work, we investigated the capacity of the EPS-producing S. thermophilus ST538 to modulate the innate antiviral immune response triggered by the activation of the Toll-like receptor 3 (TLR3) in porcine intestinal epitheliocytes (PIE cells). Moreover, in order to study the immunomodulatory potential of S. thermophilus ST538 EPS, we successfully developed two mutant strains through the knockout of the epsB or epsC genes. High-performance liquid chromatography and scanning electron microscopy studies demonstrated that the wild type (WT) strain produced as high as 595 μg/ml of EPS in the skim milk medium, while none of the mutant strains (S. thermophilus ΔepsB and ΔepsC) were able to produce EPS. Studies in PIE cells demonstrated that the EPS of S. thermophilus ST538 is able to significantly improve the expression of interferon β (IFN-β), interleukin 6 (IL-6), and C-X-C motif chemokine 10 (CXCL10) in response to TLR3 stimulation. The role of EPS in the modulation of antiviral immune response in PIE cells was confirmed by comparative studies of cell free culture supernatants and fermented skim milks obtained from S. thermophilus ΔepsB and ΔepsC. These results suggest that S. thermophilus ST538 could be used as an immunobiotic strain for the development of new immunologically functional foods, which might contribute to improve resistance against viral infections.

Keywords: PIE cells; Streptococcus thermophilus ST538; antiviral immunity; epsB; epsC; exopolysaccharides; gene-knockout.