Summary The dietary supplement and prebiotic values of β‐glucan‐rich products have been widely recognized and dietary approaches for modulating autoimmunity have been increasingly explored, we assess the impact of oral administration of high‐purity yeast β‐glucan (YBG) on gut immune function, microbiota and type 1 diabetes (T1D) using mouse models. Oral administration of this non‐digestible complex polysaccharide caused a dectin‐1‐dependent immune response involving increased expression of interleukin‐10 (IL‐10), retinaldehyde dehydrogenase (Raldh) and pro‐inflammatory cytokines in the gut mucosa. YBG‐exposed intestinal dendritic cells induced/expanded primarily Foxp3+, IL‐10+ and IL‐17+ T cells, ex vivo. Importantly, prolonged oral administration of low‐dose YBG at pre‐diabetic stage suppressed insulitis and significantly delayed the appearance of T1D in non‐obese diabetic (NOD) mice. Further, prolonged treatment with YBG showed increased Foxp3+ T‐cell frequencies, and a significant change in the gut microbiota, particularly an increase in the abundance of Bacteroidetes and a decrease in the Firmicute members. Oral administration of YBG, together with Raldh‐substrate and β‐cell antigen, resulted in better protection of NOD mice from T1D. These observations suggest that YBG not only has a prebiotic property, but also an oral tolerogenic‐adjuvant‐like effect, and these features could be exploited for modulating autoimmunity in T1D.

Since the dietary supplement and prebiotic value of β -glucan-rich products have been widely recognized and the dietary approaches for modulating autoimmunity have been increasingly explored, we assessed the impact of oral administration of high-pure yeast β -glucan (YBG) on gut immune function, microbiota and type 1 diabetes (T1D) using mouse models. Oral administration of this non-digestible complex polysaccharide caused a Dectin-1-dependent immune response involving increased expression of IL10, retinaldehyde dehydrogenase (Raldh) and pro-inflammatory cytokines in the gut mucosa. YBG-exposed intestinal DCs induced/expanded primarily Foxp3+, IL10+ and IL17+ T cells, ex vivo. Importantly, prolonged oral administration of low-dose YBG at pre-diabetic stage suppressed insulitis and significantly delayed the T1D incidence in non-obese diabetic (NOD) mice. Further, prolonged treatment with YBG showed increased Foxp3+ T cell frequencies, and a significant change in the gut microbiota, particularly an increase in the abundance of Bacteroidetes and a decrease in the Firmicute members. Oral administration of YBG, together with Raldh-substrate and β -cell antigen, resulted in a better protection of NOD mice from T1D. These observations suggest that YBG not only has a prebiotic property, but also has an oral tolerogenic-adjuvant-like effect, and these features could be exploited for modulating autoimmunity in T1D.

IL-10-competent subset within CD1dhiCD5+ B cells, also known as B10 cells, has been shown to regulate autoimmune diseases. Whether B10 cells can prevent or suppress the development of experimental autoimmune myasthenia gravis (EAMG) has not been studied. In this study, we investigated whether low dose granulocyte macrophage-colony stimulating factor (GM-CSF), which suppresses EAMG, can expand B10 cells in vivo, and whether adoptive transfer of CD1dhiCD5+ B cells would prevent or suppress EAMG. We found that treatment of EAMG mice with low-dose GM-CSF increased the proportion of CD1dhiCD5+ B cells and B10 cells. In vitro co-culture studies revealed that CD1dhiCD5+ B cells altered T cell cytokine profile but did not directly inhibit T cell proliferation. On the other hand, CD1dhiCD5+ B cells inhibited B cell proliferation and its autoantibody production in an IL-10-dependent manner. Adoptive transfer of CD1dhiCD5+ B cells to mice could prevent disease as well as suppress EAMG after disease onset. This was associated with downregulation of mature dendritic cell markers and expansion of regulatory T cells resulting in the suppression of acetylcholine receptor (AChR)-specific T cell and B cell responses. Thus, our data have provided significant insights into the mechanisms underlying the tolerogenic effects of B10 cells in EAMG. These observations suggest that in vivo or in vitro expansion of CD1dhiCD5+ B cells or B10 cells may represent an effective strategy in the treatment of human myasthenia gravis.

Summary B7-2-/-non-obese diabetic (NOD) mice develop a spontaneous autoimmune polyneuropathy (SAP) that mimics the progressive form of chronic inflammatory demyelinating polyradiculoneuropathy (CIDP). In this study, we focused on the role of regulatory T cells (T regs ) and regulatory B cells (B regs ) in SAP. We found that deletion of B7-2 in female NOD mice led to a lower frequency and number of T regs and B regs in spleens and lymph nodes. T regs but not B regs suppressed antigen-stimulated splenocyte proliferation, whereas B regs inhibited the T helper type 1 (Th1) cytokine response. Both T regs and B regs induced an increase in CD4 1 interleukin (IL)210 1 cells, although less effectively in the absence of B7-2. Adoptive transfer studies revealed that T regs , but not B regs , suppressed SAP, while B regs attenuated disease severity when given prior to symptom onset. B cell deficiency in B cell-deficient (muMT)/B7-2 -/-NOD mice prevented the development of SAP, which would indicate that the pathogenic role of B cells predominates over its regulatory role in this model. We conclude that B regs and T regs control the immunopathogenesis and progression of SAP in a non-redundant fashion, and that therapies aimed at expansion of B regs and T regs may be an effective approach in autoimmune neuropathies.

These results suggest ISS-ODN/Der f conjugate induces an antiallergic effect and induces an increase in transforming growth factor beta1 level in the allergic rhinitis model using Der f allergen. Allergic response developed by Der f allergen could be more effectively reduced by injection with ISS-ODN/Der f conjugate than by injection with ISS-ODN only.