Development Of Colitis In Mice Research Articles

Osteopontin Deficiency Accelerates Spontaneous Colitis in Mice with Disrupted Gut Microbiota and Macrophage Phagocytic Activity.

BackgroundOsteopontin (OPN) is a multifunctional protein expressed in a variety of tissues and cells. Recent studies revealed increased OPN expression in the inflamed intestinal tissues of patients with inflammatory bowel disease (IBD). The role of OPN in the pathophysiology of IBD, however, remains unclear.AimsTo investigate the role of OPN in the development of intestinal inflammation using a murine model of IBD, interleukin-10 knock out (IL-10 KO) mice.MethodsWe compared the development of colitis between IL-10 KO and OPN/IL-10 double KO (DKO) mice. OPN expression in the colonic tissues of IL-10 KO mice was examined by fluorescence in situ hybridization (FISH) analysis. Enteric microbiota were compared between IL-10 KO and OPN/IL-10 DKO mice by terminal restriction fragment length polymorphism analysis. The effect of OPN on macrophage phagocytic function was evaluated by phagocytosis assay.ResultsOPN/IL-10 DKO mice had an accelerated onset of colitis compared to IL-10 KO mice. FISH analysis revealed enhanced OPN synthesis in the colonic epithelial cells of IL-10 KO mice. OPN/IL-10 DKO mice had a distinctly different enteric bacterial profile with a significantly lower abundance of Clostridium subcluster XIVa and a greater abundance of Clostridium cluster XVIII compared to IL-10 KO mice. Intracellular OPN deletion in macrophages impaired phagocytosis of fluorescence particle-conjugated Escherichia coli in vitro. Exogenous OPN enhanced phagocytosis by OPN-deleted macrophages when administered at doses of 1 to 100 ng/ml, but not 1000 ng/ml.ConclusionsOPN deficiency accelerated the spontaneous development of colitis in mice with disrupted gut microbiota and macrophage phagocytic activity.

Tumor Necrosis Factor Receptor 2 Restricts the Pathogenicity of CD8+ T Cells in Mice With Colitis

Tumor necrosis factor receptor 2 (TNFR2, Tnfrsf1b) regulates multiple aspects of immune function, but little is known about its role in the immunopathogenesis of inflammatory bowel disease (IBD). We investigated whether TNFR2 restricts the activity of specific immune cell subtypes to protect against the development of colitis in mice. Tnfr2(-/-) mice were crossed with interleukin (Il) 10(-/-) mice, which spontaneously develop colitis, to generate Il10(-/-)Tnfr2(-/-) mice. Colonic tissues were collected from Il10(-/-)Tnfr2(-/-) mice along with Il10(-/-) mice (controls) and analyzed by flow cytometry and histology. Bone marrow wastransplanted into Il10(-/-) and Il10(-/-)Tnfr2(-/-) mice from Il10(-/-) or Il10(-/-)Tnfr2(-/-) donors by intravenous injection. CD8(+) T cells were neutralized in Il10(-/-)Tnfr2(-/-) mice by intraperitoneal injection of anti-CD8 or isotype control antibodies. Colitis was induced in Rag2(-/-) mice by intravenous injections of naïve CD8(+) T cells isolated from C57BL/6 or Tnfr2(-/-) mice. Il10(-/-)Tnfr2(-/-) mice spontaneously developed more severe colitis compared with Il10(-/-) controls, characterized by selective expansion of colonic CD8(+) T cells. Transplantation of TNFR2-deficient bone marrow resulted in significantly increased incidence and severity of colitis. Transcriptome analyses showed that the expression of genes regulated by TNFR2 were specific to CD8(+) T cells and included genes associated with risk for IBD. Depletion of CD8(+) T cells from Il10(-/-)Tnfr2(-/-) mice prevented colonic inflammation. Adoptive transfer of TNFR2-null naïve CD8(+) T cells compared with CD8(+) T cells from control mice increased the severity of colitis that developed in Rag2(-/-) mice. TNFR2 protects mice from colitis by inhibiting the expansion of colonic CD8(+) T cells. TNFR2 regulates expression of genes that regulate CD8(+) T cells and have been associated with susceptibility toIBD. Disruption in TNFR2 signaling might therefore be associated with pathogenesis. Strategies to increase levels or activity of TNFR2 and thereby reduce the activity of CD8(+) T cells might be developed to treat IBD patients with CD8(+) T cell dysfunction.

Food antigen-induced immune responses in Crohn's disease patients and experimental colitis mice.

BackgroundIn Crohn’s disease (CD), the involvement of food antigens in immune responses remains unclear. The objective of this study was to detect immune responses against food antigens in CD patients and examine the mechanism in a mouse model of colitis.MethodsWe enrolled 98 CD patients, 50 ulcerative colitis patients, and 52 healthy controls (HCs) to compare the levels of serum immunoglobulin (Ig)Gs against 88 foods. The presence of serum IgGs against foods was also examined in interleukin (IL)-10 knockout (KO) mice in which CD4+ T cell activation by antigenic food protein was assessed. Mice transferred with IL-10 KO cells received diets with or without food antigens, and the development of colitis was evaluated.ResultsThe prevalence of IgGs against various foods, especially vegetables, grains, and nuts, was significantly higher in CD patients than in HCs. Similarly, the prevalence of IgGs against food proteins was higher in IL-10 KO mice than in BALB/c mice. Beta-conglycinin, identified as an antigenic food proteins in IL-10 KO mice, induced CD4+ T cell production of interferon-γ and IL-17 through dendritic cell antigen presentation. Elimination of the food antigens ameliorated the development of colitis in mice without altering the composition of their intestinal microbiota.ConclusionsIn CD colitis mice, intestinal inflammation via CD4+ T cell hyperactivation was induced by food antigens associated with high serum IgG levels and was ameliorated by the elimination of food antigens. This disrupted immunological tolerance to food antigen, which might act as an exacerbating factor, remains to be elucidated in CD patients.Electronic supplementary materialThe online version of this article (doi:10.1007/s00535-014-0981-8) contains supplementary material, which is available to authorized users.

P-229 Muc5ac Expression Protects the Intestinal Mucosa During Acute Colitis

The mucus gel layer lining the intestinal epithelium is essential for maintaining mucosal homeostasis. Goblet cells within the epithelial barrier are responsible for the secretion of intestinal mucins. Goblet cell depletion and decreased mature mucin production is associated with enhanced mucosal inflammation in patients with ulcerative colitis (UC). Genetic loss of the secreted gel-forming mucin, Muc2 results in the spontaneous development of colitis in mice, suggestive of a key role for the mucus gel layer in colitis pathogenesis. Muc5ac is another member of this family of gel-forming mucins. Elevated Muc5ac expression has been detected in the mucosa of UC patients. However, the role of Muc5ac in UC is unknown. Previous studies demonstrate a beneficial role for gastrointestinal Muc5ac expression during nematode infection. We hypothesize that expression of colonic Muc5ac is a protective response during inflammation associated with ulcerative colitis. Muc5ac expression was studied during the course of acute dextran sulphate sodium (DSS) colitis in C57BL/6 mice. Mice with genetic loss of Muc5ac (Muc5ac-/-) and wildtype control mice (Muc5ac+/+) were subjected to DSS colitis followed by analysis of disease activity parameters. Muc5ac expression in colonic tissue was greatly increased throughout the timecourse of DSS colitis. Upon exposure to DSS, Muc5ac-/- mice demonstrated increased weight loss and colonic shortening in comparison to Muc5ac+/+ mice following 7 days of DSS. Blinded histological analysis revealed that Muc5ac-/- mice experienced dramatically elevated tissue inflammation and injury over that observed in Muc5ac+/+ mice during DSS. Finally, Muc5ac-/- mice exhibited significant mortality compared to wildtype controls as a result of DSS administration. Initial studies indicate that expression of the gel-forming mucin Muc5ac mediates a protective response during acute colitis. This is the first study to present evidence of a direct functional role for Muc5ac in a model of IBD.

Endotoxicity of Lipopolysaccharide as a Determinant of T-Cell−Mediated Colitis Induction in Mice

The intestinal microbiota is an important determinant of the mucosal response. In patients with inflammatory bowel diseases, the mucosal immune system has inappropriate interactions with the intestinal microbiota. We investigated how the composition of the intestinal microbiota affects its endotoxicity and development of colitis in mice. Germ-free C57BL/6J-Rag(1tm1Mom) (Rag1(-/-)) mice were colonized with 2 different types of complex intestinal microbiota. Colitis was induced in Rag1(-/-) mice by transfer of CD4(+)CD62L(+) T cells from C57BL/6J mice. Colonic tissues were collected and used for histologic analysis and cell isolation. Activation of lamina propria dendritic cells and T cells was analyzed by flow cytometry. After transfer of CD4(+)CD62L(+) T cells, mice with intestinal Endo(lo) microbiota (a low proportion of Enterobacteriaceae, high proportion of Bacteroidetes, and low endotoxicity) maintained mucosal immune homeostasis, and mice with highly endotoxic Endo(hi) microbiota (a high proportion of Enterobacteriaceae and low proportion of Bacteroidetes) developed colitis. To determine whether the effects of Endo(hi) microbiota were related to the higher endotoxic activity of lipopolysaccharide (LPS), we compared LPS from Enterobacteriaceae with that of Bacteroidetes. Administration of Escherichia coli JM83 (wild-type LPS) to the mice exacerbated colitis, and Escherichia coli JM83+ htrBPG (mutated LPS, with lower endotoxicity, similar to that of Bacteroidetes) prevented development of colitis after transfer of the T cells to mice. The endotoxicity of LPS produced by the intestinal microbiota is a determinant of whether mice develop colitis after transfer of CD4(+)CD62L(+) T cells. This finding might aid the design of novel biologics or probiotics to treat inflammatory bowel disease.

Peritoneal cavity regulatory B cells (B10 cells) modulate IFN-γ+CD4+ T cell numbers during colitis development in mice.

The spleen regulatory B cell subset with the functional capacity to express IL-10 (B10 cells) modulates both immune responses and autoimmune disease severity. However, the peritoneal cavity also contains relatively high frequencies of functionally defined IL-10-competent B10 cells. In this study, peritoneal cavity B10 cells shared similar cell surface phenotypes with their spleen counterparts. However, peritoneal cavity B10 cells were 10-fold more frequent among B cells than occurred within the spleen, intestinal tract, or mesenteric lymph nodes and were present at higher proportions among the phenotypically defined peritoneal B1a > B1b > B2 cell subpopulations. The development or localization of B10 cells within the peritoneal cavity was not dependent on the presence of commensal microbiota, T cells, IL-10 or B10 cell IL-10 production, or differences between their fetal liver or adult bone marrow progenitor cell origins. The BCR repertoire of peritoneal cavity B10 cells was diverse, as occurs in the spleen, and predominantly included germline-encoded VH and VL regions commonly found in either the conventional or B1 B cell compartments. Thereby, the capacity to produce IL-10 appears to be an intrinsic functional property acquired by clonally diverse B cells. Importantly, IL-10 production by peritoneal cavity B cells significantly reduced disease severity in spontaneous and induced models of colitis by regulating neutrophil infiltration, colitogenic CD4(+) T cell activation, and proinflammatory cytokine production during colitis onset. Thus, the numerically small B10 cell subset within the peritoneal cavity has regulatory function and is important for maintaining homeostasis within gastrointestinal tissues and the immune system.

Endothelial PAS Domain Protein 1 Activates the Inflammatory Response in the Intestinal Epithelium to Promote Colitis in Mice

Hypoxic inflammation (decreased oxygen tension at sites of inflammation) is a feature of inflammatory bowel disease (IBD). The hypoxia response is mediated by the transcription factors hypoxia-inducible factor (HIF) 1α and endothelial PAS domain protein 1 (EPAS1 or HIF2α), which are induced in intestinal tissues of patients with IBD. HIF1α limits intestinal barrier dysfunction, but the role of EPAS1 has not been assessed under conditions of hypoxic inflammation or in models of IBD. Acute colitis was induced by administration of Citrobacter rodentium or dextran sulfate sodium (DSS) to transgenic hypoxia reporter mice (oxygen-dependent degradation-luciferase), mice with conditional overexpression of Epas1 (Epas1(LSL/LSL)), mice with intestinal epithelium-specific deletion of Epas1 (Epas1(ΔIE) ), or wild-type littermates (controls). Colon tissues from these mice and from patients with ulcerative colitis or Crohn's disease were assessed by histologic and immunoblot analyses, immunohistochemistry, and quantitative polymerase chain reaction. Levels of hypoxia and EPAS1 were increased in colon tissues of mice after induction of colitis and patients with ulcerative colitis or Crohn's disease compared with controls. Epas1(ΔIE) mice had attenuated colonic inflammation and were protected from DSS-induced colitis. Intestine-specific overexpression of EPAS1, but not HIF-1α, led to spontaneous colitis, increased susceptibility to induction of colitis by C rodentium or DSS, and reduced survival times compared with controls. Disruption of intestinal epithelial EPAS1 attenuated the inflammatory response after administration of DSS or C rodentium, and intestine-specific overexpression of EPAS1 increased this response. We found EPAS1 to be a positive regulator of tumor necrosis factor-α production by the intestinal epithelium. Blocking tumor necrosis factor-α completely reduced hypoxia-induced intestinal inflammation. EPAS1 is a transcription factor that activates mediators of inflammation, such as tumor necrosis factor-α, in the intestinal epithelium and promotes development of colitis in mice.

Peritoneal Cavity Regulatory B Cells (B10 Cells) Modulate IFN- +CD4+ T Cell Numbers during Colitis Development in Mice

Peritoneal Cavity Regulatory B Cells (B10 Cells) Modulate IFN- +CD4+ T Cell Numbers during Colitis Development in Mice

Bacterial Sensor Triggering Receptor Expressed on Myeloid Cells-2 Regulates the Mucosal Inflammatory Response

Triggering receptor expressed on myeloid cells (TREM)-2 is a surface receptor detected on macrophages, dendritic cells, and microglia that binds repeated anionic motifs on yeast and Gram-positive and Gram-negative bacteria. Little is known about TREM-2 expression and function in the intestine or its role in inflammatory bowel disease (IBD). We investigated the expression of TREM-2 in the intestinal lamina propria and its role in the development of colonic inflammation. We measured levels of TREM-2 in lamina propria mononuclear cells from surgical specimens collected from patients with IBD or cancer (controls). We analyzed the development of colitis in TREM-2 knockout and wild-type mice. Colon samples were isolated from mice and analyzed for cytokine expression, phagocytosis of bacteria, proliferation in colonic crypts, lamina propria mononuclear cell function, and T-cell activation by ovalbumin. TREM-2 was virtually absent from colon samples of control patients, but levels were significantly higher in within the inflamed mucosa of patients with IBD; it was mainly expressed by CD11c(+) cells. Levels of TREM-2 increased as acute or chronic colitis was induced in mice. TREM-2 knockout mice developed less severe colitis than wild-type mice; the knockout mice lost less body weight, had a lower disease activity index, and had smaller mucosal lesions in endoscopic analysis. Colon dendritic cells from TREM-2 knockout mice produced lower levels of inflammatory cytokines and had reduced levels of bacterial killing and T-cell activation than cells from wild-type mice. TREM-2 contributes to mucosal inflammation during development of colitis in mice. Levels of TREM-2 are increased within the inflamed mucosa of patients with IBD, indicating its potential as a therapeutic target.

Signaling Lymphocyte Activation Molecule Regulates Development of Colitis in Mice

Signaling lymphocyte activation molecule (Slamf)1 is a co-stimulatory receptor on T cells and regulates cytokine production by macrophages and dendritic cells. Slamf1 regulates microbicidal mechanisms in macrophages, therefore we investigated whether the receptor affects development of colitis in mice. We transferred CD45RB(hi) CD4(+) T cells into Rag(-/-) or Slamf1(-/-)Rag(-/-) mice to induce colitis. We also induced colitis by injecting mice with an antibody that activates CD40. We determined the severity of enterocolitis based on disease activity index, histology scores, and levels of cytokine production, and assessed the effects of antibodies against Slamf1 on colitis induction. We quantified migration of monocytes and macrophage to inflamed tissues upon induction of colitis or thioglycollate-induced peritonitis and in response to tumor necrosis factor-α in an air-pouch model of leukocyte migration. Colitis was reduced in Slamf1(-/-)Rag(-/-) mice, compared with Rag(-/-) mice, after transfer of CD45RB(hi) CD4(+) T cells or administration of the CD40 agonist. The numbers of monocytes and macrophages were reduced in inflamed tissues of Slamf1(-/-)Rag(-/-) mice, compared with Rag(-/-) mice, after induction of colitis and other inflammatory disorders. An antibody that inhibited Slamf1 reduced the level of enterocolitis in Rag(-/-) mice. Slamf1 contributes to the development of colitis in mice. It appears to indirectly regulate the appearance of monocytes and macrophages in inflamed intestinal tissues. Antibodies that inhibit Slamf1 reduce colitis in mice, so human SLAMF1 might be a therapeutic target for inflammatory bowel disease.

Redox mapping using overhauser-enhanced MRI in the on-set and development of DSS-induced colitis in mice

Redox mapping using overhauser-enhanced MRI in the on-set and development of DSS-induced colitis in mice

T-helper 17 and Interleukin-17–Producing Lymphoid Tissue Inducer-Like Cells Make Different Contributions to Colitis in Mice

T helper (Th) 17 cells that express the retinoid-related orphan receptor (ROR) γt contribute to the development of colitis in mice, yet are found in normal and inflamed intestine. We investigated their development and functions in intestines of mice. We analyzed intestinal Th17 cells in healthy and inflamed intestinal tissues of mice. We analyzed expression of lymphotoxin (LT)α by Th17 cells and lymphoid tissue inducer-like cells. LTα(-/-) and RORγt(-/-) mice had significantly lower percentages of naturally occurring Th17 cells in the small intestine than wild-type mice. Numbers of CD3(-)CD4(+/-)interleukin-7Rα(+)c-kit(+)CCR6(+)NKp46(-) lymphoid tissue inducer-like cells that produce interleukin-17A were increased in LTα(-/-) and LTα(-/-) × recombination activating gene (RAG)-2(-/-) mice, compared with wild-type mice, but were absent from RORγt(-/-) mice. Parabiosis of wild-type and LTα(-/-) mice and bone marrow transplant experiments revealed that LTα-dependent gut-associated lymphoid tissue structures are required for generation of naturally occurring Th17 cells. However, when wild-type or LTα(-/-) CD4(+)CD45RB(high) T cells were transferred to RAG-2(-/-) or LTα(-/-)×RAG-2(-/-) mice, all groups, irrespective of the presence or absence of LTα on the donor or recipient cells, developed colitis and generated Th1, Th17, and Th17/Th1 cells. RAG-2(-/-) mice that received a second round of transplantation, with colitogenic but not naturally occurring Th17 cells, developed intestinal inflammation. The presence of naturally occurring Th17 cells in the colons of mice inhibited development of colitis after transfer of CD4(+)CD45RB(high) T cells and increased the numbers of Foxp3(+) cells derived from CD4(+)CD45RB(high) T cells. Gut-associated lymphoid tissue structures are required to generate naturally occurring Th17 cells that have regulatory activities in normal intestines of mice, but not for colitogenic Th17 and Th17/Th1 cells during inflammation.

A Novel, Orally Active Alpha 4 Integrin Antagonist, AJM300 Prevents the Development of Experimental Colitis Induced by Adoptive Transfer of IL-10 Deficient CD4+ T Cells in Mice.

Abstract Inhibition of lymphocyte trafficking by treatment with an antibody to α4 integrin has been clinically validated as a therapeutic approach for inflammatory bowel disease (IBD). The aim of this study was to investigate the pharmacological profile of AJM300, a novel small molecule α4 integrin antagonist. The active metabolite of AJM300 (HCA2969) selectively inhibited the in vitro binding of α4β7 integrin and α4β1 integrin to MAdCAM-1 and VCAM-1, respectively. Oral administration of AJM300 dose-dependently inhibited lymphocyte homing to Peyer's patches in normal mice. In addition, an increase in the peripheral lymphocyte count was observed in the same dose range that inhibited lymphocyte homing and was associated with the pharmacokinetics of HCA2969 in mice. AJM300 in the diet (AJM300M1) dose-dependently prevented the development of colitis in mice induced by adoptive transfer of IL-10 deficient CD4(+) T cells. In mice fed 1% AJM300M1 the concentration of HCA2969 in plasma was maintained over the EC(90) value for lymphocyte homing for 24 h. A significant inhibition of colon weight increase was observed at a 1% dose of AJM300M1 and was accompanied by inhibition (> 95%) of T-cell infiltration into the colon. This was comparable to the efficacy achieved by a full blockade of α4 integrin by antibody treatment. Furthermore, a histological improvement of epithelial cell hyperplasia, a reduction of inflammatory cell infiltration and a maintenance of mucus production were observed with AJM300M1. These results suggest that AJM300 might be a promising oral drug for the treatment of IBD.

Dysregulation of CD1d-Restricted Type II Natural Killer T Cells Leads to Spontaneous Development of Colitis in Mice

CD1d-restricted natural killer (NK) T cells are a subset of immunoregulatory T cells that comprise type I (express the semi-invariant T-cell receptor [TCR] and can be detected using the α-galactosylceramide/CD1d tetramer) and type II (express diverse TCRs and cannot be directly identified). Studies in mouse models of inflammatory bowel disease revealed a complex role for type I NKT cells in the development of colitis. Type II NKT cells have been associated with intestinal inflammation in patients with ulcerative colitis. To investigate whether dysregulation of type II NKT cells, caused by increased expression of CD1d, can contribute to colitis, we generated transgenic mice that express high levels of CD1d and a TCR from an autoreactive, type II NKT cell (CD1dTg/24αβTg mice). CD1dTg/24αβTg mice had reduced numbers of 24αβ T cells compared with 24αβTg mice, indicating that negative selection increases among type II NKT cells engaged by abundant self-antigen. The residual 24αβ T cells in CD1dTg/24αβTg mice had an altered surface phenotype and acquired a cytokine profile distinct from that of equivalent cells in 24αβTg mice. Interestingly, CD1dTg/24αβTg mice spontaneously developed colitis; adoptive transfer experiments confirmed that type II NKT cells that develop in the context of increased CD1d expression are pathogenic. Aberrant type II NKT cell responses directly contribute to intestinal inflammation in mice, indicating the importance of CD1d expression levels in the development and regulation of type II NKT cells.

Interleukin-13 Damages Intestinal Mucosa via TWEAK and Fn14 in Mice—A Pathway Associated With Ulcerative Colitis

TWEAK, a member of the tumor necrosis factor (TNF) superfamily, promotes intestinal epithelial cell injury and signals through the receptor Fn14 following irradiation-induced tissue damage and during development of colitis in mice. Interleukin (IL)-13, an effector of tissue damage in similar models, has been associated with the pathogenesis of ulcerative colitis (UC). We investigated interactions between TWEAK and IL-13 following mucosal damage in mice. We compared patterns of gene expression in intestinal tissues from wild-type and TWEAK knockout mice following γ-irradiation. Intestinal explants from these mice were used to detect cell damage induced by IL-13 and TNF-α. Levels of messenger RNA for IL-13, TWEAK, and Fn14 were measured in mucosal samples from patients with UC. Based on gene expression analysis, TWEAK mediates γ-irradiation-induced epithelial cell cycle arrest and apoptosis. However, TWEAK alone did not induce damage or apoptosis of primary intestinal epithelial cells. On the other hand, exogenous IL-13 activated caspase-3 in naïve intestinal explants; this process required TWEAK, Fn14, and secretion of endogenous TNF-α which was mediated by ADAM17. Conversely, activation of caspase by exogenous TNF-α required IL-13, TWEAK, and Fn14. In mucosa from patients with UC, messenger RNA levels of IL-13, TWEAK, and Fn14 increased with level of disease severity. IL-13-induced damage of intestinal epithelial cells requires TWEAK, its receptor (Fn14), and TNF-α. IL-13, TNF-α, TWEAK, and Fn14 could perpetuate and aggravate intestinal inflammation in patients with UC.

Elafin Antiprotease Prevents the Development of Colitis in Mice by Inhibiting Two Neutrophil Serine Proteases: Elastase and Proteinase 3

Elafin Antiprotease Prevents the Development of Colitis in Mice by Inhibiting Two Neutrophil Serine Proteases: Elastase and Proteinase 3

Generation of colitogenic Th17 CD4 T cells and experimental colitis is enhanced by IL-17+ γδ T cells (166.5)

Abstract Adoptive transfer of naïve CD4 T cells into T cell deficient mice induces severe colitis, a widely used animal model to study inflammatory bowel disease (IBD) including ulcerative colitis and Crohn’s disease. Th17 cells have been implicated in the pathogenesis of T cell-mediated colitis, although cellular mechanism(s) that supports in vivo Th17 differentiation and colitis induction remains unclear. We report here that γδ T cells play critical roles in amplifying Th17 differentiation and subsequent development of colitis in mice. Following naïve CD4 T cell transfer, TCRβ-/- mice developed severe colitis with enhanced Th17 differentiation, while TCRβ/δ-/- mice showed no sign of weight loss with very mild colitis. Th17 differentiation in TCRβ/δ-/- recipients was significantly diminished compared to that in TCRβ-/- recipients. Adoptive transfer of CD4 T cells with γδ T cells fully restored colitis in TCRβ/δ-/- mice and Th17 differentiation was accordingly elevated. Surprisingly, IL-17 production by γδ T cells was found to be very important for colitogenic effect because cotransfer of CCR6+ (IL-17+) γδ T cells was sufficient to promote Th17 differentiation and colitis yet transfer of CCR6- (IL-17-) γδ T cells failed to do so. Collectively, our results demonstrate that IL-17 production by γδ T cells play a critical role in fostering in vivo Th17 differentiation and inducing colitis, implying that targeting these cells might be beneficial to treat the disease.

Dietary oleic acid as a control fatty acid for polyunsaturated fatty acid intervention studies: A transcriptomics and proteomics investigation using interleukin‐10 gene‐deficient mice

Oleic acid (OA) has been used as a control fatty acid in dietary polyunsaturated fatty acid (PUFA) intervention studies due to its lack of effect on eiconasoid biosynthesis. Since the effect of OA as a control fatty acid has not yet been investigated for transcriptomics and proteomics studies, this study aimed to test whether colonic transcriptome and proteome profiles associated with colitis development in mice fed a linoleic acid-rich corn oil-AIN-76A diet (Il10(-/-) compared to C57 mice) where similar to those of OA-fed Il10(-/-) compared to C57 mice (genotype comparison). A close clustering of colonic gene and protein expression profiles between the mice fed the AIN-76A or OA diet was observed. Inflammation-induced regulatory processes associated with cellular and humoral immune responses, cellular stress response and metabolic processes related to energy utilization were identified in Il10(-/-) compared to C57 mice fed either diet. Thus OA was considered as a suitable control unsaturated fatty acid for use in multi-omics PUFA studies. The second aim of this study was to test the effect of an OA-enriched AIN-76A diet compared to a linoleic acid-rich corn oil-AIN-76A diet on colonic transcriptome and proteome changes within Il10(-/-) or C57 mice (diet comparison). Overall, there was a limited concordance observed between measureable transcriptomics and proteomics profiles for genotype and diet comparisons. This underlines the importance and validity of a systems biology approach to understand the effects of diet on gene expression as a function of the genotype.

Naphthalen-1-yl-(4-pentyloxynaphthalen-1-yl)methanone (SAB378), a Peripherally Restricted Cannabinoid CB1/CB2 Receptor Agonist, Inhibits Gastrointestinal Motility but Has No Effect on Experimental Colitis in Mice

The endocannabinoid system is involved in the regulation of gastrointestinal (GI) motility and inflammation. Using the peripherally restricted cannabinoid (CB)(1)/CB(2) receptor agonist naphthalen-1-yl-(4-pentyloxynaphthalen-1-yl)methanone (SAB378), we investigated the role of peripheral cannabinoid receptors in the regulation of GI motility and the development of colitis in mice. The actions of SAB378 on whole gut transit, upper GI transit, colonic propulsion, and locomotor activity were investigated in C57BL/6N, CB(1) receptor knockout, and CB(2) receptor knockout mice. The potential for SAB378 to modify inflammation was studied by using dextran sulfate sodium (DSS) and 2,4,6-trinitrobenzene sulfonic acid (TNBS) models of experimental colitis. SAB378 did not modify locomotor activity. SAB378 slowed all parameters of GI motility, and these effects were significantly reduced by the CB(1) receptor antagonist N-(piperidin-1-yl)-5-(4-iodophenyl)-1-(2,4-dichlorophenyl)-4-methyl-1H-pyrazole-3 carboxamide (AM251), but not by the CB(2) receptor antagonist 6-iodo-2-methyl-1-[2-(4-morpholinyl)ethyl]-1H- indol-3-yl](4-methoxyphenyl)methanone (AM630). SAB378 did not inhibit GI transit or colonic propulsion in CB(1) receptor knockout mice, whereas its effects were observed in CB(2) receptor knockout mice. SAB378 did not reduce the degree of colitis induced by DSS or TNBS. The actions of SAB378 on GI motility are mediated by peripherally located CB(1) receptors. SAB378 was not effective against two models of experimental colitis, which may indicate that peripheral cannabinoid receptor stimulation alone may not be sufficient to mediate the anti-inflammatory effects of cannabinoids.

M1750 Westernized High-Fat Diet Accelerates Development of Dextran Sulfate Sodium-Induced Colitis in Mice and Supplementation of Heme Aggravates the Disease Course

M1750 Westernized High-Fat Diet Accelerates Development of Dextran Sulfate Sodium-Induced Colitis in Mice and Supplementation of Heme Aggravates the Disease Course