Quantifying Forms and Functions of Enterohepatic Bile Acid Pools in Mice.

Backgrounds & Aims: Bile acids (BAs) are core gastrointestinal metabolites with dual functions in lipid absorption and cell signaling. BAs circulate between the liver and distal small intestine (i.e.

Quantifying forms and functions of intestinal bile acid pools in mice.

Bile acids (BAs) are gastrointestinal metabolites that serve dual functions in lipid absorption and cell signaling. BAs circulate actively between the liver and distal small intestine (i.e.

Clonal from Gut Microfistulous Tracts as Transmissible Cytotoxic Succinate-Commensal Model of Crohn's Disease Complications.

Crohn's disease (CD) has been traditionally viewed as a chronic inflammatory disease that cause gut wall thickening and complications, including fistulas, by mechanisms not understood. By focusing on (presumed modern succinate-producing commensal probiotic), recovered from intestinal microfistulous tracts (cavernous fistulous micropathologies CavFT proposed as intermediate between 'mucosal fissures' and 'fistulas') in two patients that required surgery to remove CD-damaged ilea, we demonstrate that such isolates exert pathogenic/pathobiont roles in mouse models of CD. Our isolates are clonally-related; potentially emerging as transmissible in the community and mice; proinflammatory and adapted to the ileum of germ-free mice prone to CD-like ileitis (SAMP1/YitFc) but not healthy mice (C57BL/6J), and cytotoxic/ATP-depleting to HoxB8-immortalized bone marrow derived myeloid cells from SAMP1/YitFc mice when concurrently exposed to succinate and extracts from CavFT-derived , but not to cells from healthy mice.

ATP-dependent transporters: emerging players at the crossroads of immunity and metabolism.

Nearly 50 ATP-binding cassette (ABC) transporters are encoded by mammalian genomes. These transporters are characterized by conserved nucleotide-binding and hydrolysis (i.e.

Development of a putative Zn-chelating but highly selective MMP-13 inhibitor.

Starting from an already known MMP-13 inhibitor, 1, we pursued an SAR-approach focusing on optimizing interactions close to the Zn binding site of the enzyme. We found the oxetane containing compound 32 (MMP-13 IC = 42 nM), which exhibited complete inhibition of collagenolysis in in vitro studies and an excellent selectivity profile among the MMP family. Interestingly, docking studies propose that the oxetane ring in 32 is oriented towards the Zn ion for chelating the metal ion.

Transcriptional Behavior of Regulatory T Cells Predicts IBD Patient Responses to Vedolizumab Therapy.

Background: Inflammatory bowel disease (IBD) involves chronic T cell-mediated inflammatory responses. Vedolizumab (VDZ), a monoclonal antibody against α4β7 integrin, inhibits lymphocyte extravasation into intestinal mucosae and is effective in ulcerative colitis (UC) and Crohn's disease (CD).

Aim: We sought to identify immune cell phenotypic and gene expression signatures that related to response to VDZ.

CAR directs T cell adaptation to bile acids in the small intestine.

Bile acids are lipid-emulsifying metabolites synthesized in hepatocytes and maintained in vivo through enterohepatic circulation between the liver and small intestine. As detergents, bile acids can cause toxicity and inflammation in enterohepatic tissues. Nuclear receptors maintain bile acid homeostasis in hepatocytes and enterocytes, but it is unclear how mucosal immune cells tolerate high concentrations of bile acids in the small intestine lamina propria (siLP).

Regulation of Intestinal Inflammation by Dietary Fats.

With the epidemic of human obesity, dietary fats have increasingly become a focal point of biomedical research. Epidemiological studies indicate that high-fat diets (HFDs), especially those rich in long-chain saturated fatty acids (e.g.

Genetic and pharmacological inhibition of the nuclear receptor RORα regulates T17 driven inflammatory disorders.

Full development of IL-17 producing CD4 T helper cells (T17 cells) requires the transcriptional activity of both orphan nuclear receptors RORα and RORγt. However, RORα is considered functionally redundant to RORγt; therefore, the function and therapeutic value of RORα in T17 cells is unclear. Here, using mouse models of autoimmune and chronic inflammation, we show that expression of RORα is required for T17 cell pathogenicity.

Physiological expression and function of the MDR1 transporter in cytotoxic T lymphocytes.

Multidrug resistance-1 (MDR1) acts as a chemotherapeutic drug efflux pump in tumor cells, although its physiological functions remain enigmatic. Using a recently developed MDR1-knockin reporter allele (Abcb1aAME), we found that constitutive MDR1 expression among hematopoietic cells was observed in cytolytic lymphocytes-including CD8+ cytotoxic T lymphocytes (CTLs) and natural killer cells-and regulated by Runt-related (Runx) transcription factors. Whereas MDR1 was dispensable for naive CD8+ T cell development, it was required for both the normal accumulation of effector CTLs following acute viral infection and the protective function of memory CTLs following challenge with an intracellular bacterium.

Aminoacyl-tRNA synthetase inhibition activates a pathway that branches from the canonical amino acid response in mammalian cells.

Signaling pathways that sense amino acid abundance are integral to tissue homeostasis and cellular defense. Our laboratory has previously shown that halofuginone (HF) inhibits the prolyl-tRNA synthetase catalytic activity of glutamyl-prolyl-tRNA synthetase (EPRS), thereby activating the amino acid response (AAR). We now show that HF treatment selectively inhibits inflammatory responses in diverse cell types and that these therapeutic benefits occur in cells that lack GCN2, the signature effector of the AAR.

Artificial microbiome heterogeneity spurs six practical action themes and examples to increase study power-driven reproducibility.

With >70,000 yearly publications using mouse data, mouse models represent the best engrained research system to address numerous biological questions across all fields of science. Concerns of poor study and microbiome reproducibility also abound in the literature. Despite the well-known, negative-effects of data clustering on interpretation and study power, it is unclear why scientists often house >4 mice/cage during experiments, instead of ≤2.

Emerging roles of bile acids in mucosal immunity and inflammation.

Bile acids are cholesterol-derived surfactants that circulate actively between the liver and ileum and that are classically recognized for emulsifying dietary lipids to facilitate absorption. More recent studies, however, have revealed new functions of bile acids; as pleotropic signaling metabolites that regulate diverse metabolic and inflammatory pathways in multiple cell types and tissues through dynamic interactions with both germline-encoded host receptors and the microbiota. Accordingly, perturbed bile acid circulation and/or metabolism is now implicated in the pathogenesis of cholestatic liver diseases, metabolic syndrome, colon cancer, and inflammatory bowel diseases (IBDs).

Xenobiotic and endobiotic handling by the mucosal immune system.

Purpose Of Review: Mucosal immune cells in the intestinal tract are continuously exposed to a barrage of both foreign and endogenously generated metabolites, termed xenobiotics, and endobiotics, respectively. This review summarizes recent insights into the mechanisms by which xenobiotics and endobiotics regulate intestinal immunity and inflammation.

Recent Findings: The community of enteric microbes (i.

The Xenobiotic Transporter Mdr1 Enforces T Cell Homeostasis in the Presence of Intestinal Bile Acids.

CD4 T cells are tightly regulated by microbiota in the intestine, but whether intestinal T cells interface with host-derived metabolites is less clear. Here, we show that CD4 T effector (Teff) cells upregulated the xenobiotic transporter, Mdr1, in the ileum to maintain homeostasis in the presence of bile acids. Whereas wild-type Teff cells upregulated Mdr1 in the ileum, those lacking Mdr1 displayed mucosal dysfunction and induced Crohn's disease-like ileitis following transfer into Rag1 hosts.

Role of Dysregulated Cytokine Signaling and Bacterial Triggers in the Pathogenesis of Cutaneous T-Cell Lymphoma.

Cutaneous T-cell lymphoma is a heterogeneous group of lymphomas characterized by the accumulation of malignant T cells in the skin. The molecular and cellular etiology of this malignancy remains enigmatic, and what role antigenic stimulation plays in the initiation and/or progression of the disease remains to be elucidated. Deep sequencing of the tumor genome showed a highly heterogeneous landscape of genetic perturbations, and transcriptome analysis of transformed T cells further highlighted the heterogeneity of this disease.

Informatics-Based Discovery of Disease-Associated Immune Profiles.

Advances in flow and mass cytometry are enabling ultra-high resolution immune profiling in mice and humans on an unprecedented scale. However, the resulting high-content datasets challenge traditional views of cytometry data, which are both limited in scope and biased by pre-existing hypotheses. Computational solutions are now emerging (e.

Cytokine Networks and T-Cell Subsets in Inflammatory Bowel Diseases.

Pathogenesis of the inflammatory bowel diseases (IBDs), such as ulcerative colitis (UC) and Crohn's disease (CD), involve proinflammatory changes within the microbiota, chronic immune-mediated inflammatory responses, and epithelial dysfunction. Converging data from genome-wide association studies, mouse models of IBD, and clinical trials indicate that cytokines are key effectors of both normal homeostasis and chronic inflammation in the gut. Yet many questions remain concerning the role of specific cytokines in different IBDs within distinct regions of the gut, and regarding cellular mechanisms of action.

In vivo regulation of gene expression and T helper type 17 differentiation by RORγt inverse agonists.

The orphan nuclear receptor, retinoic acid receptor-related orphan nuclear receptor γt (RORγt), is required for the development and pathogenic function of interleukin-17A-secreting CD4(+) T helper type 17 (Th17) cells. Whereas small molecule RORγt antagonists impair Th17 cell development and attenuate autoimmune inflammation in vivo, the broader effects of these inhibitors on RORγt-dependent gene expression in vivo has yet to be characterized. We show that the RORγt inverse agonist TMP778 acts potently and selectively to block mouse Th17 cell differentiation in vitro and to impair Th17 cell development in vivo upon immunization with the myelin antigen MOG35-55 plus complete Freund's adjuvant.

Akt inhibition enhances expansion of potent tumor-specific lymphocytes with memory cell characteristics.

Adoptive cell therapy (ACT) using autologous tumor-infiltrating lymphocytes (TIL) results in complete regression of advanced cancer in some patients, but the efficacy of this potentially curative therapy may be limited by poor persistence of TIL after adoptive transfer. Pharmacologic inhibition of the serine/threonine kinase Akt has recently been shown to promote immunologic memory in virus-specific murine models, but whether this approach enhances features of memory (e.g.

Targeting Th17 cells in autoimmune diseases.

T helper 17 (Th17) cells have been implicated in the pathogenesis of most common autoimmune diseases, including psoriasis, rheumatoid arthritis (RA), inflammatory bowel disease (IBD), and multiple sclerosis (MS). Although anti-interleukin-17 (IL-17) antibodies show marked clinical efficacy in psoriasis, targeting IL-17 alone is not sufficient to improve clinical end points in other autoimmune conditions, namely RA and Crohn's disease. Given that Th17 cells express IL-17 together with many other proinflammatory cytokines [IL-17F, IL-22, IL-26, and granulocyte-macrophage colony-stimulating factor (GM-CSF)], targeting the Th17 cell lineage may be superior to blocking a single effector cytokine.

Small-molecule RORγt antagonists inhibit T helper 17 cell transcriptional network by divergent mechanisms.

We identified three retinoid-related orphan receptor gamma t (RORγt)-specific inhibitors that suppress T helper 17 (Th17) cell responses, including Th17-cell-mediated autoimmune disease. We systemically characterized RORγt binding in the presence and absence of drugs with corresponding whole-genome transcriptome sequencing. RORγt acts as a direct activator of Th17 cell signature genes and a direct repressor of signature genes from other T cell lineages; its strongest transcriptional effects are on cis-regulatory sites containing the RORα binding motif.