BATF2 inhibits immunopathological Th17 responses by suppressing Il23a expression during Trypanosoma cruzi infection

Shoko Kitada, Hisako Kayama, Daisuke Okuzaki, Ritsuko Koga, Masao Kobayashi, Yasunobu Arima, Atsushi Kumanogoh, Masaaki Murakami, Masahito Ikawa, Kiyoshi Takeda; BATF2 inhibits immunopathological Th17 responses by suppressing Il23a expression during Trypanosoma cruzi infection. J Exp Med 1 May 2017; 214 (5): 1313–1331. doi: https://doi.org/10.1084/jem.2016107

Interleukin-10-Producing Plasmablasts Exert Regulatory Function in Autoimmune Inflammation

SummaryB cells can suppress autoimmunity by secreting interleukin-10 (IL-10). Although subpopulations of splenic B lineage cells are reported to express IL-10 in vitro, the identity of IL-10-producing B cells with regulatory function in vivo remains unknown. By using IL-10 reporter mice, we found that plasmablasts in the draining lymph nodes (dLNs), but not splenic B lineage cells, predominantly expressed IL-10 during experimental autoimmune encephalomyelitis (EAE). These plasmablasts were generated only during EAE inflammation. Mice lacking plasmablasts by genetic ablation of the transcription factors Blimp1 or IRF4 in B lineage cells developed an exacerbated EAE. Furthermore, IRF4 positively regulated IL-10 production that can inhibit dendritic cell functions to generate pathogenic T cells. Our data demonstrate that plasmablasts in the dLNs serve as IL-10 producers to limit autoimmune inflammation and emphasize the importance of plasmablasts as IL-10-producing regulatory B cells

The Lactic Acid Bacterium Pediococcus acidilactici Suppresses Autoimmune Encephalomyelitis by Inducing IL-10-Producing Regulatory T Cells

BACKGROUND: Certain intestinal microflora are thought to regulate the systemic immune response. Lactic acid bacteria are one of the most studied bacteria in terms of their beneficial effects on health and autoimmune diseases; one of which is Multiple sclerosis (MS) which affects the central nervous system. We investigated whether the lactic acid bacterium Pediococcus acidilactici, which comprises human commensal bacteria, has beneficial effects on experimental autoimmune encephalomyelitis (EAE), an animal model of MS. METHODOLOGY/PRINCIPAL FINDINGS: P. acidilactici R037 was orally administered to EAE mice to investigate the effects of R037. R037 treatment suppressed clinical EAE severity as prophylaxis and therapy. The antigen-specific production of inflammatory cytokines was inhibited in R037-treated mice. A significant increase in the number of CD4(+) Interleukin (IL)-10-producing cells was observed in the mesenteric lymph nodes (MLNs) and spleens isolated from R037-treated naive mice, while no increase was observed in the number of these cells in the lamina propria. Because only a slight increase in the CD4(+)Foxp3(+) cells was observed in MLNs, R037 may primarily induce Foxp3(-) IL10-producing T regulatory type 1 (Tr1) cells in MLNs, which contribute to the beneficial effect of R037 on EAE. CONCLUSIONS/SIGNIFICANCE: An orally administered single strain of P. acidilactici R037 ameliorates EAE by inducing IL10-producing Tr1 cells. Our findings indicate the therapeutic potential of the oral administration of R037 for treating multiple sclerosis

Slc3a2 Mediates Branched-Chain Amino-Acid-Dependent Maintenance of Regulatory T Cells

Foxp3+ regulatory T (Treg) cells, which suppress immune responses, are highly proliferative in vivo. However, it remains unclear how the active replication of Treg cells is maintained in vivo. Here, we show that branched-chain amino acids (BCAAs), including isoleucine, are required for maintenance of the proliferative state of Treg cells via the amino acid transporter Slc3a2-dependent metabolic reprogramming. Mice fed BCAA-reduced diets showed decreased numbers of Foxp3+ Treg cells with defective in vivo proliferative capacity. Mice lacking Slc3a2 specifically in Foxp3+ Treg cells showed impaired in vivo replication and decreased numbers of Treg cells. Slc3a2-deficient Treg cells showed impaired isoleucine-induced activation of the mTORC1 pathway and an altered metabolic state. Slc3a2 mutant mice did not show an isoleucine-induced increase of Treg cells in vivo and exhibited multi-organ inflammation. Taken together, these findings demonstrate that BCAA controls Treg cell maintenance via Slc3a2-dependent metabolic regulation

ATF6β is a host cellular target of the Toxoplasma gondii virulence factor ROP18

Toxoplasma virulence factor ROP18 targets endoplasmic reticulum–bound transcription factor ATF6β in the host cell, leading to the detrimental loss of ATF6β through proteasome-dependent degradation

Probiotic Bifidobacterium breve Induces IL-10-Producing Tr1 Cells in the Colon

Specific intestinal microbiota has been shown to induce Foxp3+ regulatory T cell development. However, it remains unclear how development of another regulatory T cell subset, Tr1 cells, is regulated in the intestine. Here, we analyzed the role of two probiotic strains of intestinal bacteria, Lactobacillus casei and Bifidobacterium breve in T cell development in the intestine. B. breve, but not L. casei, induced development of IL-10-producing Tr1 cells that express cMaf, IL-21, and Ahr in the large intestine. Intestinal CD103+ dendritic cells (DCs) mediated B. breve-induced development of IL-10-producing T cells. CD103+ DCs from Il10−/−, Tlr2−/−, and Myd88−/− mice showed defective B. breve-induced Tr1 cell development. B. breve-treated CD103+ DCs failed to induce IL-10 production from co-cultured Il27ra−/− T cells. B. breve treatment of Tlr2−/− mice did not increase IL-10-producing T cells in the colonic lamina propria. Thus, B. breve activates intestinal CD103+ DCs to produce IL-10 and IL-27 via the TLR2/MyD88 pathway thereby inducing IL-10-producing Tr1 cells in the large intestine. Oral B. breve administration ameliorated colitis in immunocompromised mice given naïve CD4+ T cells from wild-type mice, but not Il10−/− mice. These findings demonstrate that B. breve prevents intestinal inflammation through the induction of intestinal IL-10-producing Tr1 cells