Response to the letter by Brotherton regarding "insoluble fiber and intestinal microbiota metabolism"

Novel probiotic yeast from Miso promotes regulatory dendritic cell IL-10 production and attenuates DSS-induced colitis in mice

BACKGROUND

Yeasts are a type of fungi thought to have probiotic functions. In this study, we isolated a novel probiotic yeast (Zygosaccharomyces sapae strain I-6) from Miso (a traditional Japanese fermented food). We examined its effects on phenotypic changes in intestinal dendritic cells (DCs), and evaluated its anti-inflammatory effects in dextran sulfate sodium (DSS)-induced colitis.

METHODS

A single colony was selected from homogenized Miso, based on its ability to produce interleukin (IL)-10 in CD11c⁺ bone marrow DCs (BMDCs) in vitro. The anti-inflammatory effects of strain I-6 on CD11c⁺ BMDCs and CD11c⁺ CD103⁺ DCs were analyzed in mouse mesenteric lymph nodes in vitro and in a DSS mouse model.

RESULTS

The IL-10 concentrations in the co-culture BMDC supernatants treated with I-6 were dramatically higher than in those treated with Saccharomyces cerevisiae (Sc). IL-10 production is mediated by both TLR2 and Dectin-1. β-Glucan extracted from I-6 also induced higher levels of IL-10 production in BMDCs than β-glucan from Sc. The number of mesenteric lymph node CD11c⁺ CD103⁺ DCs was significantly increased by I-6 administration, compared with Sc administration. Strain I-6 showed strong anti-inflammatory effects on DSS-induced colitis compared to Sc. Moreover, the adoptive transfer of I-6-treated BMDCs showed anti-inflammatory effects on DSS-induced colitis in mice without oral administration of I-6 cells.

CONCLUSIONS

Strain I-6 induced phenotypic changes in intestinal CD11c⁺ DCs characterized by high IL-10 production and exerted strong anti-inflammatory effects on DSS-induced colitis. Traditional Japanese fermented foods may be a valuable source of probiotic yeasts for effective IBD therapy and treatment.

Novel probiotics isolated from a Japanese traditional fermented food, Funazushi, attenuates DSS-induced colitis by increasing the induction of high integrin αv/β8-expressing dendritic cells

BACKGROUND

We isolated two novel probiotics strains (s193 and s292) from Funazushi, which is a traditional Japanese fermented food, and evaluated its effects on DSS-induced colitis to determine the possible underlying mechanisms.

METHODS

A single colony from homogenized Funazushi was isolated by its ability to suppress TNF-α in RAW 264.7. Effect of probiotics on colonic inflammation induced by DSS was evaluated. Effect of probiotics on Treg induction by CD11c⁺ dendritic cells (DCs) of MLNs were analyzed.

RESULTS

Two novel probiotics strains classified into the genus Lactobacillus were isolated (s193 and s292), and those strains showed stronger anti-inflammatory effects on DSS-induced colitis than those of L. gasseri isolated from the gut. mRNA expression β8 integrin in CD11c⁺DCs of MLNs and the number of Tregs in the large intestine were significantly increased by s193 and s292 administration compared with L. gasseri administration. Bone marrow DCs treated with s193 and s292 highly increased β8 integrin, and those cells strongly induced differentiation of CD4⁺ T cells into Tregs. Differentiation of Tregs was remarkably inhibited by anti-β8 integrin antibody treatment.

CONCLUSIONS

Strains s193 and s292 demonstrate strong anti-inflammatory effects on DSS-induced colitis through induction of β8 integrin expression on DCs. Our results suggested that Japanese traditional fermented foods are valuable sources for probiotics that are effective for IBD therapy and treatment.

Expression of human cathelicidin peptide LL-37 in inflammatory bowel disease

Cathelicidin peptide LL-37 plays an important role in the early host response against invading pathogens via its broad-spectrum anti-microbial activity. In this study, we investigated LL-37 expression in the inflamed mucosa of inflammatory bowel disease (IBD) patients. Furthermore, the regulatory mechanism of LL-37 induction was investigated in human colonic subepithelial myofibroblasts (SEMFs). LL-37 mRNA expression and protein secretion were analysed using real-time polymerase chain reaction and enzyme-linked immunosorbent assay, respectively. Intracellular signalling pathways were analysed using immunoblotting and specific small interference RNA (siRNA). The expression of LL-37 mRNA was increased significantly in the inflamed mucosa of ulcerative colitis and Crohn's disease. The Toll-like receptor (TLR)-3 ligand, polyinosinic-polycytidylic acid (poly(I:C), induced LL-37 mRNA expression and stimulated LL-37 secretion in colonic SEMFs. The transfection of siRNAs specific for intracellular signalling proteins [Toll/IL-1R domain-containing adaptor-inducing interferon (IFN) (TRIF), tumour necrosis factor receptor-associated factor (TRAF)6, transforming growth factor β-activated kinase (TAK)1] suppressed the poly(I:C)-induced LL-37 mRNA expression significantly. Poly(I:C)-induced phosphorylation of mitogen-activated protein kinases (MAPKs) and activated nuclear factor kappa B (NF-κB) and activating factor protein (AP)-1. siRNAs specific for NF-κB and c-Jun inhibited poly(I:C)-induced LL-37 mRNA expression. LL-37 suppressed lipopolysaccharide (LPS)-induced interleukin (IL)-6 and IL-8 expression significantly in colonic SEMFs. The expression of LL-37 was up-regulated in the inflamed mucosa of IBD patients. LL-37 was induced by TLR-3 stimulation and exhibited an anti-microbial effect via interaction with lipopolysaccharide (LPS).