RelB and C/EBPα critically regulate the development of Peyer's patch mononuclear phagocytes.

To establish protection against harmful foreign antigens, the small intestine harbors guardian sites called Peyer's patches (PPs). PPs take up antigens through microfold (M) cells and transfer them to the sub-epithelial dome (SED), which contains a high density of mononuclear phagocytes (MPs), for T cell-priming. Accumulating evidence indicates that SED-MPs have unique functions other than T cell-priming to facilitate mucosal immune responses; however, the crucial factors regulating the functions of SED-MPs have not been determined.

Food antigens suppress small intestinal tumorigenesis.

Food components suppressing small intestinal tumorigenesis are not well-defined partly because of the rarity of this tumor type compared to colorectal tumors. Using mice, a mouse model for intestinal tumorigenesis, and antigen-free diet, we report here that food antigens serve this function in the small intestine. By depleting Peyer's patches (PPs), immune inductive sites in the small intestine, we found that PPs have a role in the suppression of small intestinal tumors and are important for the induction of small intestinal T cells by food antigens.

Galectin-2 Agglutinates via Lipopolysaccharide Containing H Type I Under Weakly Acidic Conditions.

Galectins are β-galactoside-binding animal lectins involved in various biological functions, such as host defense. Galectin-2 and -3 are members of the galectin family that are expressed in the stomach, including the gastric mucosa and surface mucous cells. Galectin-3 exhibits aggregation and bactericidal activity against in a β-galactoside-dependent manner.

RIPK1 blocks T cell senescence mediated by RIPK3 and caspase-8.

Receptor-interacting protein kinase 1 (RIPK1) regulates cell death and inflammation. Here, we show that T cell-specific RIPK1 deficiency in mice leads to the premature senescence of T cells and induces various age-related diseases, resulting in premature death. RIPK1 deficiency causes higher basal activation of mTORC1 (mechanistic target of rapamycin complex 1) that drives enhanced cytokine production, induction of senescence-related genes, and increased activation of caspase-3/7, which are restored by inhibition of mTORC1.

Fatty acid overproduction by gut commensal microbiota exacerbates obesity.

Although recent studies have highlighted the impact of gut microbes on the progression of obesity and its comorbidities, it is not fully understood how these microbes promote these disorders, especially in terms of the role of microbial metabolites. Here, we report that Fusimonas intestini, a commensal species of the family Lachnospiraceae, is highly colonized in both humans and mice with obesity and hyperglycemia, produces long-chain fatty acids such as elaidate, and consequently facilitates diet-induced obesity. High fat intake altered the expression of microbial genes involved in lipid production, such as the fatty acid metabolism regulator fadR.

Role of leukotriene B4 (LTB4)-LTB4 receptor 1 signaling in post-incisional nociceptive sensitization and local inflammation in mice.

Leukotriene B4 (LTB4) is a potent lipid mediator involved in the recruitment and activation of neutrophils, which is an important feature of tissue injury and inflammation. The biological effects of LTB4 are primarily mediated through the high-affinity LTB4 receptor, BLT1. Postoperative incisional pain is characterized by persistent acute pain at the site of tissue injury and is associated with local inflammation.

Acetate differentially regulates IgA reactivity to commensal bacteria.

The balance between bacterial colonization and its containment in the intestine is indispensable for the symbiotic relationship between humans and their bacteria. One component to maintain homeostasis at the mucosal surfaces is immunoglobulin A (IgA), the most abundant immunoglobulin in mammals. Several studies have revealed important characteristics of poly-reactive IgA, which is produced naturally without commensal bacteria.

Galectin-2 Has Bactericidal Effects against in a β-galactoside-Dependent Manner.

is associated with the onset of gastritis, peptic ulcers, and gastric cancer. Galectins are a family of β-galactoside-binding proteins involved in diverse biological phenomena. Galectin-2 (Gal-2), a member of the galectin family, is predominantly expressed in the gastrointestinal tract.

Human gain-of-function STAT1 mutation disturbs IL-17 immunity in mice.

Gain-of-function (GOF) mutations in the gene for signal transducer and activator of transcription 1 (STAT1) account for approximately one-half of patients with chronic mucocutaneous candidiasis (CMC) disease. Patients with GOF-STAT1 mutations display a broad variety of infectious and autoimmune manifestations in addition to CMC, and those with severe infections and/or autoimmunity have a poor prognosis. The establishment of safe and effective treatments based on a precise understanding of the molecular mechanisms of this disorder is required to improve patient care.

Dietary Antigens Induce Germinal Center Responses in Peyer's Patches and Antigen-Specific IgA Production.

The primary induction sites for intestinal IgA are the gut-associated lymphoid tissues (GALT), such as Peyer's patches (PPs) and isolated lymphoid follicles (ILFs). The commensal microbiota is known to contribute to IgA production in the gut; however, the role of dietary antigens in IgA production is poorly understood. To understand the effect of dietary antigens on IgA production, post-weaning mice were maintained on an elemental diet without any large immunogenic molecules.

Innate Lymphoid Cells in the Induction of Obesity.

Complex interactions between immune cells are an important component in the induction of obesity. Here, we show that Il2rgRag2 mice lacking all lymphocytes are resistant to diet-induced obesity. Transplantation of bone marrow cells from Rag2 mice, which lack only acquired immune cells, into Il2rgRag2 mice abolishes this resistance, indicating a role for innate lymphoid cells (ILCs) in this process.

Identification of Galectin-2-Mucin Interaction and Possible Formation of a High Molecular Weight Lattice.

Galectins comprise a group of animal lectins characterized by their specificity for β-galactosides. Galectin-2 (Gal-2) is predominantly expressed in the gastrointestinal tract and has been identified as one of the main gastric mucosal proteins that are proposed to have a protective role in the stomach. As Gal-2 is known to form homodimers in solution, this may result in crosslinking of macromolecules with the sugar structures recognized by Gal-2.

IL-22BP dictates characteristics of Peyer's patch follicle-associated epithelium for antigen uptake.

Interleukin-22 (IL-22) acts protectively and harmfully on intestinal tissue depending on the situation; therefore, IL-22 signaling needs to be tightly regulated. IL-22 binding protein (IL-22BP) binds IL-22 to inhibit IL-22 signaling. It is expressed in intestinal and lymphoid tissues, although its precise distribution and roles have remained unclear.

Resolvins as regulators of the immune system.

Inflammation is the first response of the immune system to infection or injury, but excessive or inappropriate inflammatory responses contribute to a range of acute and chronic human diseases. Clinical assessment of dietary supplementation of ù-3 polyunsaturated fatty acids (i.e.