Local production of chemokines and prostaglandin E2 in the acute, chronic and recovery phase of murine experimental colitis

Dimethyl fumarate modulates the regulatory T cell response in the mesenteric lymph nodes of mice with experimental autoimmune encephalomyelitis

Dimethyl fumarate (DMF, Tecfidera) is an oral drug utilized to treat relapsing-remitting multiple sclerosis (MS). DMF treatment reduces disease activity in MS. Gastrointestinal discomfort is a common adverse effect of the treatment with DMF. This study aimed to investigate the effect of DMF administration in the gut draining lymph nodes cells of C57BL6/J female mice with experimental autoimmune encephalomyelitis (EAE), an animal model of MS. We have demonstrated that the treatment with DMF (7.5 mg/kg) significantly reduces the severity of EAE. This reduction of the severity is accompanied by the increase of both proinflammatory and anti-inflammatory mechanisms at the beginning of the treatment. As the treatment progressed, we observed an increasing number of regulatory Foxp3 negative CD4 T cells (Tr1), and anti-inflammatory cytokines such as IL-27, as well as the reduction of PGE2 level in the mesenteric lymph nodes of mice with EAE. We provide evidence that DMF induces a gradual anti-inflammatory response in the gut draining lymph nodes, which might contribute to the reduction of both intestinal discomfort and the inflammatory response of EAE. These findings indicate that the gut is the first microenvironment of action of DMF, which may contribute to its effects of reducing disease severity in MS patients.

Set up and validation of a sensitive method to quantify prostaglandins, prostaglandin-glycerol esters and prostaglandin-ethanolamides, as well as their respective precursors

Arachidonic acid-derived prostaglandins are widely studied for their role in inflammation. However, besides arachidonic acid, other arachidonic moiety-containing lipids can be metabolized by COX-2. Indeed, the endocannabinoids 2-arachidonoylglycerol (2-AG) and N-arachidonoylethanolamine (anandamide, AEA) can follow the same biochemical pathways than arachidonic acid leading to the formation of prostaglandin-glycerol esters (PG-G) and prostaglandin-ethanolamides (or prostamides, PG-EA), respectively. The data reported so far support the interest of these bioactive lipids in inflammatory conditions. However, there is only a handful of methods described for their quantification in biological matrices. Moreover, given the shared biochemical pathways for arachidonic acid, 2-AG and AEA, a method allowing for the quantification of these precursors and the corresponding prostaglandin derivatives appears as largely needed. Thus, we report here the development and validation of a single run UPLC-MS/MS quantification method allowing the quantification of these endocannabinoids-derived mediators together with the classical prostaglandin. Moreover, we applied the method to the quantification of these lipids in vitro (using lipopolysaccharides-activated J774 macrophage cells) and in vivo in several tissues from DSS-induced colitis mice. This femtomole-range method should improve the understanding of the interaction between these lipid mediators and inflammation.

Lactiplantibacillus plantarum L47 and inulin alleviate enterotoxigenic Escherichia coli induced ileal inflammation in piglets by upregulating the levels of α-linolenic acid and 12,13-epoxyoctadecenoic acid

Alternatives to antibiotics for preventing bacteria-induced inflammation in early-weaned farm animals are sorely needed. Our previous study showed that Lactiplantibacillus plantarum L47 and inulin could alleviate dextran sulfate sodium (DSS)-induced colitis in mice. To explore the protective effects of L. plantarum L47 and inulin on the ileal inflammatory response in weaned piglets challenged with enterotoxigenic Escherichia coli (ETEC), 28 weaned piglets were assigned into four groups, namely, CON group-orally given 10 mL/d phosphate buffer saline (PBS), LI47 group-orally given a mixture of 10 mL/d L. plantarum L47 and inulin, ECON group-orally given 10 mL/d PBS and challenged by ETEC, and ELI47 group-orally given 10 mL/d L. plantarum L47 and inulin mixture and challenged by ETEC. The results demonstrated that the combination of L. plantarum L47 and inulin reduced inflammatory responses and relieved the inflammatory damage caused by ETEC, including ileal morphological damage, reduced protein expression of ileal tight junction, decreased antioxidant capacity, and decreased anti-inflammatory factors. Transcriptome analysis revealed that L. plantarum L47 and inulin up-regulated the gene expression of phospholipase A2 group IIA (PLA2G2A) (P < 0.05) as well as affected alpha-linolenic acid (ALA) metabolism and linoleic acid metabolism. Moreover, L. plantarum L47 and inulin increased the levels of ALA (P < 0.05), lipoteichoic acid (LTA) (P < 0.05), and 12,13-epoxyoctadecenoic acid (12,13-EpOME) (P < 0.05) and the protein expression of Toll-like receptor 2 (TLR2) (P = 0.05) in the ileal mucosa. In conclusion, L. plantarum L47 and inulin together alleviated ETEC-induced ileal inflammation in piglets by up-regulating the levels of ALA and 12,13-EpOME via the LTA/TLR2/PLA2G2A pathway.

Neuropeptide W Exhibits Preventive and Therapeutic Effects on Acetic Acid-Induced Colitis via Modulation of the Cyclooxygenase Enzyme System

BACKGROUND

The novel peptide neuropeptide W (NPW) was originally shown to function in the control of feeding behavior and energy homeostasis. The aim of this study was to elucidate the putative preventive and therapeutic effects of NPW on colitis-associated oxidative injury and the underlying mechanisms for its action.

METHODS

Sprague-Dawley rats in the acute colitis groups received NPW (0.5, 1 or 5 µg/kg/day) injections prior to induction of colitis with acetic acid, while the chronic colitis groups were treated after the induction of colitis. In both acute and chronic colitis (CC) groups, treatments were continued for 5 days and the rats were decapitated at the 24th hour of the last injections and colon tissues were collected for assessments.

RESULTS

NPW pretreatment given for 5 days before colitis induction, as well as treating rats with NPW during the 5-day course of CC, abolished colonic lipid peroxidation. NPW treatment prevented colitis-induced reduction in blood flow, diminished neutrophil infiltration, and pro-inflammatory cytokine responses. NPW pretreatment only at the higher dose reduced colonic edema and microscopic score and preserved colonic glutathione stores. Elevations in cyclooxygenase (COX) enzyme activity and COX-1 protein level during the acute phase of colitis as well as reduction in COX-2 were all reversed with NPW pretreatment. In contrast, NPW treatment was effective in reducing the elevated COX-2 concentration during the chronic phase.

CONCLUSIONS

NPW alleviates acetic acid-induced oxidative colonic injury in rats through the upregulation of colonic blood flow as well as the inhibition of COX-2 protein expression and pro-inflammatory cytokine production.

Differential Outcome between BALB/c and C57BL/6 Mice after Escherichia coli O157:H7 Infection Is Associated with a Dissimilar Tolerance Mechanism

Enterohemorrhagic Escherichia coli (EHEC) infections can result in a wide range of clinical presentations despite that EHEC strains belong to the O157:H7 serotype, one of the most pathogenic forms. Although pathogen virulence influences disease outcome, we emphasize the concept of host-pathogen interactions, which involve resistance or tolerance mechanisms in the host that determine total host fitness and bacterial virulence. Taking advantage of the genetic differences between mouse strains, we analyzed the clinical progression in C57BL/6 and BALB/c weaned mice infected with an E. coli O157:H7 strain. We carefully analyzed colonization with several bacterial doses, clinical parameters, intestinal histology, and the integrity of the intestinal barrier, as well as local and systemic levels of antibodies to pathogenic factors. We demonstrated that although both strains had comparable susceptibility to Shiga toxin (Stx) and the intestinal bacterial burden was similar, C57BL/6 showed increased intestinal damage, alteration of the integrity of the intestinal barrier, and impaired renal function that resulted in increased mortality. The increased survival rate in the BALB/c strain was associated with an early specific antibody response as part of a tolerance mechanism.

Emerging role of mTOR in tumor immune contexture: Impact on chemokine-related immune cells migration

During the last few decades, cell-based anti-tumor immunotherapy emerged and it has provided us with a large amount of knowledge. Upon chemokines recognition, immune cells undergo rapid trafficking and activation in disease milieu, with immune cells chemotaxis being accompanied by activation of diverse intercellular signal transduction pathways. The outcome of chemokines-mediated immune cells chemotaxis interacts with the cue of mammalian target of rapamycin (mTOR) in the tumor microenvironment (TME). Indeed, the mTOR cascade in immune cells involves migration and infiltration. In this review, we summarize the available mTOR-related chemokines, as well as the characterized upstream regulators and downstream targets in immune cells chemotaxis and assign potential underlying mechanisms in each evaluated chemokine. Specifically, we focus on the involvement of mTOR in chemokine-mediated immune related cells in the balance between tumor immunity and malignancy.

Flavonoids from Engineered Tomatoes Inhibit Gut Barrier Pro-inflammatory Cytokines and Chemokines, via SAPK/JNK and p38 MAPK Pathways

Flavonoids are a diverse group of plant secondary metabolites, known to reduce inflammatory bowel disease symptoms. How they achieve this is largely unknown. Our study focuses on the gut epithelium as it receives high topological doses of dietary constituents, maintains gut homeostasis, and orchestrates gut immunity. Dysregulation leads to chronic gut inflammation, via dendritic cell (DC)-driven immune responses. Tomatoes engineered for enriched sets of flavonoids (anthocyanins or flavonols) provided a unique and complex naturally consumed food matrix to study the effect of diet on chronic inflammation. Primary murine colonic epithelial cell-based inflammation assays consist of chemokine induction, apoptosis and proliferation, and effects on kinase pathways. Primary murine leukocytes and DCs were used to assay effects on transmigration. A murine intestinal cell line was used to assay wound healing. Engineered tomato extracts (enriched in anthocyanins or flavonols) showed strong and specific inhibitory effects on a set of key epithelial pro-inflammatory cytokines and chemokines. Chemotaxis assays showed a resulting reduction in the migration of primary leukocytes and DCs. Activation of epithelial cell SAPK/JNK and p38 MAPK signaling pathways were specifically inhibited. The epithelial wound healing-associated STAT3 pathway was unaffected. Cellular migration, proliferation, and apoptosis assays confirmed that wound healing processes were not affected by flavonoids. We show flavonoids target epithelial pro-inflammatory kinase pathways, inhibiting chemotactic signals resulting in reduced leukocyte and DC chemotaxis. Thus, both anthocyanins and flavonols modulate epithelial cells to become hyporesponsive to bacterial stimulation. Our results identify a viable mechanism to explain the in vivo anti-inflammatory effects of flavonoids.

COX-1/PGE2/EP4 alleviates mucosal injury by upregulating β-arr1-mediated Akt signaling in colitis

COX-1/PGE₂ is an important protective mediator in ulcerative colitis (UC). β-arrestin1 (β-arr1), which acts as a scaffold protein, is involved in PGE₂-mediated signaling pathways. However, the interaction between PGE₂ and β-arr1 in maintaining mucosal barrier integrity remains unexplored. In this study, we demonstrated that COX-1 and PGE₂ were significantly decreased, and EP4 mRNA was downregulated in both UC patients and mice during the injury phase. PGE₂ treatment was found to alleviate mucosal injury and induce EP4 expression during dextran sulfate sodium (DSS)-induced colitis in wild-type (WT) mice. Following DSS-induced injury, β-arr1 deficient mice showed increased signs of colitis compared to β-arr1 WT mice, and the expression of PI3K and p-Akt were remarkably downregulated in β-arr1 deficient mice. In parallel, HCT116 cells transfected with β-arr1 siRNA were examined in the presence or absence of PGE₂in vitro. PGE₂ treatment in the β-arr1 WT/KO DSS model and β-arr1 siRNA transfection of HCT116 cells confirmed that PGE₂ upregulated β-arr1 in vivo and in vitro. Collectively, our results indicate that COX-1/PGE₂/EP4 upregulates the β-arr1 mediated Akt signaling pathway to provide mucosal protection in colitis. Thus, these findings provide support for the future development and clinical application of COX-1/PGE₂ in UC.

Enhancement of macrophage inflammatory responses by CCL2 is correlated with increased miR-9 expression and downregulation of the ERK1/2 phosphatase Dusp6

Macrophage polarization plays a central role in both protective immunity and immunopathology. While the role of cytokines in driving macrophage polarization is well characterized, less is understood about the role of chemokines. The purpose of this study was to determine if CC chemokine 2 (CCL2/MCP1) could influence macrophage polarization in response to subsequent activation with cytokines and microbial products. Treatment of bone marrow-derived macrophages with CCL2 alone did not result in increased expression of either classical or alternatively-activated macrophage genes as compared to standard skewing cytokines or Toll-like receptor agonists. However, subsequent stimulation of CCL2 pre-treated macrophages with classical activation stimuli resulted in enhanced expression of genes associated with classical activation. This enhancement correlated with increased phosphorylation of ERK1/2 kinases, a decrease in expression of the ERK phosphatase Dusp6 and enhanced expression of miR-9. These results indicate that CCL2 supports the classical activation of macrophages, with miR-9 mediated down-regulation of Dusp6 and enhanced ERK-mediated signal transduction possibly mediating this enhanced pro-inflammatory gene expression.

L13a-dependent translational control in macrophages limits the pathogenesis of colitis

Sustained inflammation from infiltrated immune cells plays a pivotal role in the pathogenesis of ulcerative colitis (UC). Previously, we established the role of ribosomal protein L13a in the regulation of an inflammation-responsive post-transcriptional operon in myeloid cells. However, the role of this protein as a molecular cue to control the severity of colitis is not known. Here, we examined whether L13a-dependent translational control in macrophages could serve as an endogenous defense against colitis. The administration of dextran sodium sulfate induced experimental colitis in myeloid-specific L13a-knockout (KO) and control mice. Pathological scoring and injury to the colon mucosa evaluated the severity of colitis. The steady-state levels of several pro-inflammatory cytokines and chemokines were determined through ELISA and polyribosome profile analysis. Rapid weight loss, severe rectal bleeding, shortening of the colon, and significantly reduced survival rate were observed in the KO mice. Histopathological analysis of the colons of KO mice showed a severe disruption of epithelial crypts with immune cell infiltrates. Elevated levels of several inflammatory cytokines and chemokines and abrogation of their naturally imposed translational silencing were observed in the colons of the KO mice. Higher serum levels of several pro-inflammatory cytokines and the release of gut bacteria and endotoxins into the blood streams of KO mice were detected, suggesting the amplification of the inflammatory response to septicemia. Taken together, these results reveal an essential role for L13a in the endogenous protection against UC and demonstrate the potential for new therapeutic opportunities through the deliberate promotion of this mechanism.

Innate Mucosal Immune System Response of BALB/c vs C57BL/6 Mice to Injury in the Setting of Enteral and Parenteral Feeding

BACKGROUND

Outbred mice exhibit increased airway and intestinal immunoglobulin A (IgA) following injury when fed normal chow, consistent with humans. Parenteral nutrition (PN) eliminates IgA increases at both sites. Inbred mice are needed for detailed immunological studies; however, specific strains have not been evaluated for this purpose. BALB/c and C57BL/6 are common inbred mouse strains but demonstrate divergent immune responses to analogous stress. This study addressed which inbred mouse strain best replicates the outbred mouse and human immune response to injury.

METHODS

Intravenously cannulated mice received chow or PN for 5 days and then underwent sacrifice at 0 or 8 hours following controlled surgical injury (BALB/c: n = 16-21/group; C57BL/6: n = 12-15/group). Bronchoalveolar lavage (BAL) was analyzed by enzyme-linked immunosorbent assay for IgA, tumor necrosis factor-α (TNF-α), interleukin (IL)-1β, and IL-6, while small intestinal wash fluid (SIWF) was analyzed for IgA.

RESULTS

No significant increase in BAL IgA occurred following injury in chow- or PN-fed BALB/c mice (chow: P = .1; PN: P = .7) despite significant increases in BAL TNF-α and SIWF IgA (chow: 264 ± 28 vs 548 ± 37, P < .0001; PN: 150 ± 12 vs 301 ± 17, P < .0001). Injury significantly increased mucosal IgA in chow-fed C57BL/6 mice (BAL: 149 ± 33 vs 342 ± 87, P = .01; SIWF: 236 ± 28 vs 335 ± 32, P = .006) and BAL cytokines. After injury, PN-fed C57BL/6 mice exhibited no difference in BAL IgA (P = .9), BAL cytokines, or SIWF IgA (P = .1).

CONCLUSIONS

C57BL/6 mice exhibit similar airway responses to injury as outbred mice and humans, providing an appropriate model for studying mucosal responses to injury. The BALB/c mucosal immune system responds differently to injury and does not replicate the human injury response.

The role of PGE2 in intestinal inflammation and tumorigenesis

Release of the free fatty acid arachidonic acid (AA) by cytoplasmic phospholipase A2 (cPLA2) and its subsequent metabolism by the cyclooxygenase and lipoxygenase enzymes produces a broad panel of eicosanoids including prostaglandins (PGs). This study sought to investigate the roles of these mediators in experimental models of inflammation and inflammation-associated intestinal tumorigenesis. Using the dextran sodium sulfate (DSS) model of experimental colitis, we first investigated how a global reduction in eicosanoid production would impact intestinal injury by utilizing cPLA2 knockout mice. cPLA2 deletion enhanced colonic injury, reflected by increased mucosal ulceration and pro-inflammatory cytokine expression. Increased disease severity was associated with a significant reduction in the levels of several eicosanoid metabolites, including PGE2. We further assessed the precise role of PGE2 synthesis on mucosal injury and repair by utilizing mice with a genetic deletion of microsomal PGE synthase-1 (mPGES-1), the terminal synthase in the formation of inducible PGE2. DSS exposure caused more extensive acute injury as well as impaired recovery in knockout mice compared to wild-type littermates. Increased intestinal damage was associated with both reduced PGE2 levels as well as altered levels of other eicosanoids including PGD2. To determine whether this metabolic redirection impacted inflammation-associated intestinal tumorigenesis, Apc(Min/+) and Apc(Min/+):mPGES-1(-/-) mice were exposed to DSS. DSS administration caused a reduction in the number of intestinal polyps only in Apc(Min/+):mPGES-1(-/-) mice. These results demonstrate the importance of the balance of prostaglandins produced in the intestinal tract for maintaining intestinal homeostasis and impacting tumor development.

Anti-inflammatory effect of Phellinus linteus grown on germinated brown rice on dextran sodium sulfate-induced acute colitis in mice and LPS-activated macrophages

ETHNOPHARMACOLOGICAL RELEVANCE AND AIM OF THE STUDY

Phellinus linteus is a herb used in traditional Asian medicine to treat stomachache, inflammation, and tumors. Recent studies show that the extract of Phellinus linteus has anti-inflammatory and antitumor activities. However, Phellinus linteus extract has limitation of high cost and limited availability because of supply shortage. Here, we grew Phellinus linteus on germinated brown rice to address the issue of supply shortage and investigated anti-inflammatory effect in vivo as well as in vitro.

MATERIALS AND METHODS

Phellinus linteus grown on germinated brown rice (PBR) were extracted using filtration steps, which included γ-aminobutyric acid (GABA). The PBR (200, 500mg/kg/day) was applied into the mouse model of dextran sodium sulfate (DSS)-induced colitis and lipopolysaccharide (LPS)-stimulated mouse macrophage RAW264.7 cells. We used sulfasalazine as a reference drug. In addition, mechanism related to anti-inflammatory was investigated by Western blotting.

RESULTS

In the mouse model of DSS-induced colitis, PBR ameliorated the pathological characteristics of colitis such as shortening of colon length and improved the disease activity index score. In addition, we showed that PBR reduced the expression of nuclear factor-kappa B (NF-κB) in colitis. Western blotting showed that PBR decreased the expression of inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (Cox-2) proteins. Further, PBR treatment reduced the expression of mitogen-activated protein kinases (MAPKs) (e.g., extracellular signal-regulated protein kinase (ERK) and p38) in the mouse model of DSS-induced colitis.

CONCLUSIONS

Treatment of RAW 264.7 macrophages with a combination of PBR and LPS showed a significant concentration-dependent inhibition of nitric oxide (NO) and prostaglandin E2 (PGE2) production. In addition, we determined the ability of PBR to reduce the iNOS and tumor necrosis factor (TNF)-α expression. PBR inhibited the expression of iNOS, NF-κB, and Cox-2 proteins in LPS-stimulated RAW264.7 macrophages. This study presents the potential use of PBR as a drug candidate against colitis.

Effects of different ratios of ω-3/ω-6 polyunsaturated fatty acids on experimental acute colitis in rats

AIM: To investigate the effect of different ratios of ω-3/ω-6 of polyunsaturated fatty acids (PUFAs) on acute colitis induced with dextran sulfate sodium (DSS) in rats and explore the possible mechanisms.

METHODS: Thirty-two male SD rats were randomly divided into four groups (n = 8 for each): A (control), B (ω-3/ω-6, 1:1), C (ω-3/ω-6, 1:3) and D (ω-3/ω-6, 1:30). After six weeks of feeding with different diets, acute colitis in rats in groups B, C and D were induced by giving 3% DSS in drinking water for seven days. Then all the rats were sacrificed. Overall inflammatory severity score and histological damage score were calculated. The levels of prostaglandin E2 (PGE2), tumor necrosis factor-α (TNF-a), nuclear transcription factor kappa B (NF-kB) in the colon, and the level of interleukin-6 (IL-6) in serum were measured by ELISA.

RESULTS: The overall inflammatory severity score in group B was significantly lower than those in groups C and D (2.8 ± 1.2 vs 4.3 ± 1.1, 5.6 ± 1.3, P < 0.05, P < 0.01). The histological damage score in group B was also significantly lower than those in groups C and D (3.2 ± 2.0 vs 35.0 ± 28.8, 27.0 ± 25.8, P < 0.01 for both). The levels of PGE2 and TNF-a in the colon were significantly lower in groups B and C than in group D [443.4 ± 67.3 (ng/100 g tissue), 419.5 ± 52.6 (ng/100 g tissue) vs 541.2 ± 68.5 (ng/100 g tissue), P < 0.05, P < 0.01; 189.2 ± 27.0 (ng/100 g tissue), 173.2 ± 50.2 (ng/100 g tissue) vs 270.3 ± 49.1 (ng/100 g tissue), P < 0.01 for both). The level of IL-6 in serum was significantly lower in group B than in groups C and D (97.1 ng/L ± 8.2 ng/L vs 129.1 ng/L ± 5.5 ng/L, 125.4 ng/L ± 19.6 ng/L, P < 0.01, P < 0.05). There were no statistical differences in the level of nuclear NF-kB between groups B, C and D [497.9 ± 50.7 (ng/100 g tissue), 569.1 ± 121.2 (ng/100 g tissue), 582.5 ± 123.1 (ng/100 g tissue)].

CONCLUSION: Higher ratios of ω-3/ω-6 PUFAs have a more significant protective effect against acute colitis, especially when the ratio is 1:1. The overall inflammatory severity score, histological damage score, the levels of PGE2 and TNF-a in colon and the level of IL-6 in serum are significantly lower in the 1:1 (ω-3/ω-6) group than in the 1:30 group. Adding moderate amount of ω-3 PUFA may be a new way to treat IBD.

Intestinal CCL11 and eosinophilic inflammation is regulated by myeloid cell-specific RelA/p65 in mice

In inflammatory bowel diseases (IBDs), particularly ulcerative colitis, intestinal macrophages (MΦs), eosinophils, and the eosinophil-selective chemokine CCL11, have been associated with disease pathogenesis. MΦs, a source of CCL11, have been reported to be of a mixed classical (NF-κB-mediated) and alternatively activated (STAT-6-mediated) phenotype. The importance of NF-κB and STAT-6 pathways to the intestinal MΦ/CCL11 response and eosinophilic inflammation in the histopathology of experimental colitis is not yet understood. Our gene array analyses demonstrated elevated STAT-6- and NF-κB-dependent genes in pediatric ulcerative colitis colonic biopsies. Dextran sodium sulfate (DSS) exposure induced STAT-6 and NF-κB activation in mouse intestinal F4/80(+)CD11b(+)Ly6C(hi) (inflammatory) MΦs. DSS-induced CCL11 expression, eosinophilic inflammation, and histopathology were attenuated in RelA/p65(Δmye) mice, but not in the absence of STAT-6. Deletion of p65 in myeloid cells did not affect inflammatory MΦ recruitment or alter apoptosis, but did attenuate LPS-induced cytokine production (IL-6) and Ccl11 expression in purified F4/80(+)CD11b(+)Ly6C(hi) inflammatory MΦs. Molecular and cellular analyses revealed a link between expression of calprotectin (S100a8/S100a9), Ccl11 expression, and eosinophil numbers in the DSS-treated colon. In vitro studies of bone marrow-derived MΦs showed calprotectin-induced CCL11 production via a p65-dependent mechanism. Our results indicate that myeloid cell-specific NF-κB-dependent pathways play an unexpected role in CCL11 expression and maintenance of eosinophilic inflammation in experimental colitis. These data indicate that targeting myeloid cells and NF-κB-dependent pathways may be of therapeutic benefit for the treatment of eosinophilic inflammation and histopathology in IBD.

Deletion of intestinal epithelial cell STAT3 promotes T-lymphocyte STAT3 activation and chronic colitis following acute dextran sodium sulfate injury in mice

BACKGROUND

Intestinal epithelial cell (IEC) STAT3 is required for wound healing following acute dextran sodium sulfate (DSS) injury. We hypothesized that loss of IEC STAT3 would promote the development of chronic colitis following acute DSS injury.

METHODS

Colitis was induced in IEC-specific STAT3-deficient mice (STAT3)[INCREMENT]IEC and littermate controls (STAT3 Flx/Flx) with 4% DSS for 7 days, followed by water consumption for 21 days. Epithelial and immune mediators and severity of colitis were determined.

RESULTS

Survival, colon length, and histologic injury were significantly worse at day 28 in STAT3[INCREMENT]IEC mice. IEC proliferation and apoptosis did not vary by genotype at day 14 or day 28. The colonic lamina propria frequency of pSTAT3* cells was increased at day 28 and correlated with histologic injury in STAT3 [INCREMENT]IEC mice. The frequency of colonic F480* pSTAT3* macrophages and CD3* pSTAT3* T lymphocytes were increased in STAT3[INCREMENT]IEC mice as compared with STAT3 Flx/Flx controls. In STAT3[INCREMENT]IEC mice, colonic expression of STAT3 target genes Reg3β and Reg3γ, which mediate epithelial restitution, were significantly decreased, whereas expression of interleukin (IL)-17a, IFNγ, CXCL2, CXCL10, and CCL2 were significantly increased and correlated with the increase in histologic severity at day 28(P < 0.05). IL-17a expression also correlated with the increased lamina propria frequency of CD3* pSTAT3* T lymphocytes.

CONCLUSIONS

Loss of intestinal epithelial STAT3 leads to more severe chronic inflammation following acute injury, which is not accounted for by a sustained defect in epithelial proliferation or apoptosis 7 or 21 days after 1 cycle of DSS but rather defective REG3 expression and expansion of pSTAT3* lymphocytes and IL-17A expression.

Systemic macrophage depletion inhibits Helicobacter bilis-induced proinflammatory cytokine-mediated typhlocolitis and impairs bacterial colonization dynamics in a BALB/c Rag2-/- mouse model of inflammatory bowel disease

Helicobacter bilis, an enterohepatic helicobacter, is associated with chronic hepatitis in aged immunocompetent inbred mice and inflammatory bowel disease (IBD) in immunodeficient mice. To evaluate the role of macrophages in H. bilis-induced IBD, Rag2(-/-) BALB/c or wild-type (WT) BALB/c mice were either sham dosed or infected with H. bilis Missouri strain under specific-pathogen-free conditions, followed by an intravenous injection of a 0.2-ml suspension of liposomes coated with either phosphate-buffered saline (control) or clodronate (a macrophage depleting drug) at 15 weeks postinfection (wpi). At 16 wpi, the ceca of H. bilis-infected Rag2(-/-) mice treated with control liposomes had significantly higher histopathological lesional scores (for cumulative typhlitis index, inflammation, edema, epithelial defects, and hyperplasia) and higher counts of F4/80(+) macrophages and MPO(+) neutrophils compared to H. bilis-infected Rag2(-/-) mice treated with clodronate liposomes. In addition, cecal quantitative PCR analyses revealed a significant suppression in the expression of macrophage-related cytokine genes, namely, Tnfa, Il-1β, Il-10, Cxcl1, and iNos, in the clodronate-treated H. bilis-infected Rag2(-/-) mice compared to the H. bilis-infected Rag2(-/-) control mice. Finally, cecal quantitative PCR analyses also revealed a significant reduction in bacterial colonization in the clodronate-treated Rag2(-/-) mice. Taken together, our results suggest that macrophages are critical inflammatory cellular mediators for promoting H. bilis-induced typhlocolitis in mice.

Expression of IL-17 in inflammatory bowel disease and synergistic action of IL-17 and LPS on IL-8 expression in intestinal epithelial cells

AIM: To investigate the expression of interleukin-17 (IL-17) in inflammatory bowel disease (IBD) in a mouse model and to examine the synergistic reaction of IL-17 and lipopolysaccharide (LPS) on interleukin-8 (IL-8) expression in intestinal epithelial cells (HT-29 cells).

METHODS: A mouse model of inflammatory bowel disease was induced with TNBS to detect the expression of IL-17 and its receptor IL-17Ra in IBD. HT-29 cells were treated with IL-17 and/or different concentrations of LPS to examine their synergistic action on the expression of IL-8 mRNA and protein by FACS, real-time PCR, ELISA, and Western blot.

RESULTS: The expression of IL-17 and IL-17Ra in IBD was significantly increased (both P < 0.05). IL-17 and low doses of LPS showed a synergistic action on IL-8 expression in HT-29 cells (2187.61 ± 132.42 vs 2634.27 ± 134.63, P = 0.01) by activating NF-κB and promoting inflammation. However, high doses of LPS reduced the levels of IL-8, and their synergistic action with IL-17 disappeared (1841.43 ± 50.38 vs 1685.67 ± 71.47, P = 0.03).

CONCLUSION: IL-17 has a synergistic action with low, but not high doses of LPS on the expression of inflammatory mediators in HT-29 cells.

CCL17 promotes intestinal inflammation in mice and counteracts regulatory T cell-mediated protection from colitis

BACKGROUND & AIMS

Priming of T cells by dendritic cells (DCs) in the intestinal mucosa and associated lymphoid tissues helps maintain mucosal tolerance but also contributes to the development of chronic intestinal inflammation. Chemokines regulate the intestinal immune response and can contribute to pathogenesis of inflammatory bowel diseases. We investigated the role of the chemokine CCL17, which is expressed by conventional DCs in the intestine and is up-regulated during colitis.

METHODS

Colitis was induced by administration of dextran sodium sulfate (DSS) to mice or transfer of T cells to lymphopenic mice. Colitis activity was monitored by body weight assessment, histologic scoring, and cytokine profile analysis. The direct effects of CCL17 on DCs and the indirect effects on differentiation of T helper (Th) cells were determined in vitro and ex vivo.

RESULTS

Mice that lacked CCL17 (Ccl17(E/E) mice) were protected from induction of severe colitis by DSS or T-cell transfer. Colonic mucosa and mesenteric lymph nodes from Ccl17-deficient mice produced lower levels of proinflammatory cytokines. The population of Foxp3(+) regulatory T cells (Tregs) was expanded in Ccl17(E/E) mice and required for long-term protection from colitis. CCR4 expression by transferred T cells was not required for induction of colitis, but CCR4 expression by the recipients was required. CCL17 promoted Toll-like receptor-induced secretion of interleukin-12 and interleukin-23 by DCs in an autocrine manner, promoted differentiation of Th1 and Th17 cells, and reduced induction of Foxp3(+) Treg cells.

CONCLUSIONS

The chemokine CCL17 is required for induction of intestinal inflammation in mice. CCL17 has an autocrine effect on DCs that promotes production of inflammatory cytokines and activation of Th1 and Th17 cells and reduces expansion of Treg cells.

Shining a light on intestinal traffic

Inflammatory bowel disease (IBD), encompassing Crohn's disease and ulcerative colitis, is associated with enhanced leukocyte infiltration to the gut, which is directly linked to the clinical aspects of these disorders. Thus, leukocyte trafficking is a major target for IBD therapy. Past and emerging techniques to study leukocyte trafficking both in vitro and in vivo have expanded our knowledge of the leukocyte migration process and the role of inhibitors. Various strategies have been employed to target chemokine- and integrin-ligand interactions within the multistep adhesion cascade and the S1P/S1PR1 axis in leukocyte migration. Though there is an abundance of preclinical data demonstrating efficacy of leukocyte trafficking inhibitors, many have yet to be confirmed in clinical studies. Vigilance for toxicity and further research is required into this complex and emerging area of IBD therapy.

Physiological stress exacerbates murine colitis by enhancing proinflammatory cytokine expression that is dependent on IL-18

Psychological stress is an environmental factor considered to be a precipitating factor of inflammatory bowel disease. Interleukin (IL)-18 plays a role in stress-induced aggravation in some diseases. The aim of this study was to establish a model of murine colitis exacerbated by psychological stress and to clarify the role of IL-18 in this model. Male C57Bl/6 mice and IL-18(-/-) mice were used for this study. The mice received dextran sulfate sodium (DSS) for induction of colitis. Some mice were exposed to psychological stress using a communication box. Body weight, colonic length, and histological inflammation were measured for assessment of colitis. Tumor necrosis factor (TNF)-α and IL-18 expression in the colon and IL-18 expression in the adrenal gland were analyzed using real-time PCR. The effect of anti-IL-18 antibody was also investigated. Effects of TNF-α and IL-18 on cytokine expressions were studied using the colonic epithelial cell line LS174T. Induction of psychological stress in DSS-treated wild-type mice significantly exacerbated colitis with enhanced expression of proinflammatory cytokines and IL-18. However, induction of psychological stress in DSS-treated IL-18(-/-) mice did not aggravate colitis compared with that in the IL-18(-/-) group given only DSS treatment. Stress-induced aggravation of colitis was ameliorated significantly by anti-IL-18 antibody treatment. IL-18 did not enhance TNF-α-induced expression of intercellular adhesion molecule-1 or IL-8 in LS174T. We established a model of colitis exacerbated by psychological stress. Psychological stress enhanced IL-18 expression and plays a proinflammatory role in stress-induced aggravation of colitis.

Anti-inflammatory effects of freeze-dried black raspberry powder in ulcerative colitis

Ulcerative colitis (UC) is a chronic inflammatory disease of the colonic mucosa that can dramatically increase the risk of colon cancers. In the present study, we evaluated the effects of a dietary intervention of freeze-dried black raspberries (BRB), a natural food product with antioxidant and anti-inflammatory bioactivities, on disease severity in an experimental mouse model of UC using 3% dextran sodium sulfate (DSS). C57BL/6J mice were fed either a control diet or a diet containing BRB (5 or 10%) for 7-14 days and then the extent of colonic injury was assessed. Dietary BRB markedly reduced DSS-induced acute injury to the colonic epithelium. This protection included better maintenance of body mass and reductions in colonic shortening and ulceration. BRB treatment, however, did not affect the levels of either plasma nitric oxide or colon malondialdehyde, biomarkers of oxidative stress that are otherwise increased by DSS-induced colonic injury. BRB treatment for up to 7 days suppressed tissue levels of several key pro-inflammatory cytokines, including tumor necrosis factor α and interleukin 1β. Further examination of the inflammatory response by western blot analysis revealed that 7 day BRB treatment reduced the levels of phospho-IκBα within the colonic tissue. Colonic cyclooxygenase 2 levels were also dramatically suppressed by BRB treatment, with a concomitant decrease in the plasma prostaglandin E₂ (276 versus 34 ng/ml). These findings demonstrate a potent anti-inflammatory effect of BRB during DSS-induced colonic injury, supporting its possible therapeutic or preventive role in the pathogenesis of UC and related neoplastic events.

Western-style diets induce macrophage infiltration and contribute to colitis-associated carcinogenesis

BACKGROUND AND AIM

A Western-style diet (WD) is known to play an important role in inflammatory bowel disease and colon carcinogenesis. The purpose of this study was to understand the role of macrophages in WD-induced colitis associated with carcinogenesis.

METHODS

Male BALB/c mice were fed a WD or a control diet (CD) for 4 weeks and exposed to azoxymethane (AOM) followed by 2% dextran sulfate sodium (DSS) for 7 days.

RESULTS

The WD increased susceptibility to DSS-induced inflammation and accelerated the infiltration of macrophages. The incidence and multiplicity of colon tumors were higher in mice fed the WD than in those fed the CD (P < 0.05). Levels of prostaglandin-endoperoxide synthase (PTGS) 2 and prostaglandin (PG) E(2) in the colon were higher after treatment with AOM and DSS in mice fed the WD than in those fed the CD. In addition, WD consumption increased the DNA binding activity of nuclear factor-kappaB and the serum concentration of tumor necrosis factor (TNF)-α. Mice fed the WD had higher numbers of F4/80-positive cells surrounding cancer cells compared with mice fed the CD. These cells expressed PTGS2, TNF-α and β-catenin, which are up-regulated by the WD. We also found that the WD increased unphosphorylated β-catenin accumulation in the cytoplasm and nucleus of colon cancer cells.

CONCLUSIONS

A WD increases the susceptibility to DSS-induced inflammation and accelerates the infiltration of macrophages. In turn, this resulted in the development and progression of colon cancer.

Technical Advance: Function and efficacy of an {alpha}4-integrin antagonist using bioluminescence imaging to detect leukocyte trafficking in murine experimental colitis

Leukocyte trafficking is a therapeutic target in IBD. The integrins α₄β and α₄β₁ regulate leukocyte migration into tissues and lymphoid organs. Current strategies rely on biologics, such as mAb, to inhibit leukocyte recruitment. Here we show the in vivo therapeutic effects of a small molecule α4-integrin antagonist (GSK223618A) in a leukocyte-trafficking model and a murine model of colitis. Leukocytes isolated from MLNs of transgenic β-actin-luc+ mice were injected i.v. into recipients with DSS-induced colitis. Recipient mice were orally gavaged with vehicle or an α₄-integrin antagonist 1 h pre-adoptive transfer, followed by bioluminescence whole body and ex vivo organ imaging 4 h post-transfer. To confirm its therapeutic effect, the α₄-integrin antagonist was given orally twice daily for 6 days to mice with DSS-induced colitis, starting on Day 3. Clinical, macroscopic, and histological signs of inflammation were assessed and gene-expression profiles analyzed. Using bioluminescence imaging, we tracked and quantified leukocyte migration to the inflamed gut and demonstrated its inhibition by a small molecule α₄-integrin antagonist. Additionally, the therapeutic effect of the antagonist was confirmed in DSS-induced colitis in terms of clinical, macroscopic, and histological signs of inflammation. Gene expression analysis suggested enhancement of tissue healing in compound-treated animals. Inhibition of leukocyte trafficking using small molecule integrin antagonists is a promising alternative to large molecule biologics. Furthermore, in vivo bioluminescence imaging is a valuable strategy for preclinical evaluation of potential therapeutics that target leukocyte trafficking in inflammatory diseases.

Use of bioluminescence imaging to track neutrophil migration and its inhibition in experimental colitis

Inflammatory bowel disease (IBD) is associated with neutrophil infiltration into the mucosa and crypt abscesses. The chemokine interleukin (IL)-8 [murine homologues (KC) and macrophage inflammatory protein (MIP)-2] and its receptor CXCR2 are required for neutrophil recruitment; thus, blocking this engagement is a potential therapeutic strategy. In the present study, we developed a preclinical model of neutrophil migration suitable for investigating the biology of and testing new drugs that target neutrophil trafficking. Peritoneal exudate neutrophils from transgenic β-actin-luciferase mice were isolated 12h after intraperitoneal injection with thioglycollate, and were assessed phenotypically and functionally. Exudate cells were injected intravenously into recipients with dextran sodium sulphate (DSS)-induced colitis followed by bioluminescence imaging of whole-body and ex vivo organs at 2, 4 and 16-22h post-transfer. Anti-KC antibody or an isotype control were administered at 20 µg/mouse 1h before transfer, followed by whole-body and organ imaging 4h post-transfer. The peritoneal exudate consisted of 80% neutrophils, 39% of which were CXCR2(+) . In vitro migration towards KC was inhibited by anti-KC. Ex vivo bioluminescent imaging showed that neutrophil trafficking into the colon of DSS recipients was inhibited by anti-KC 4h post-cell transfer. In conclusion, this study describes a new approach for investigating neutrophil trafficking that can be used in preclinical studies to evaluate potential inhibitors of neutrophil recruitment.

Enoxaparin improves the course of dextran sodium sulfate-induced colitis in syndecan-1-deficient mice

Syndecan-1 (Sdc1) plays a major role in wound healing and modulates inflammatory responses. Sdc1 expression is reduced in lesions of patients with ulcerative colitis. The aim of this study was to investigate the role of Sdc1 in murine dextran sodium sulfate (DSS)-induced colitis. DSS colitis was induced in Sdc1-deficient (knockout (KO)) and wild-type mice by oral administration of 3% DSS. KO mice exhibited a significantly increased lethality as compared with wild-type controls (61 versus 5%, P < 0.05). Impaired mucosal healing and prolonged recruitment of inflammatory cells in KO mice were accompanied by significant up-regulation of tumor necrosis factor-alpha, CC chemokine ligand 3/macrophage inflammatory protein-1alpha, and vascular cell adhesion molecule-1, as determined by histological correlation between 0 and 15 days after colitis induction, TaqMan low-density array analysis, and quantitative real-time PCR. Treatment from days 7 through 14 with enoxaparin, a functional analogue of the Sdc1 heparan sulfate chains, significantly reduced lethality of KO mice due to DSS-induced colitis, which was correlated with improved mucosal healing. In vitro, Sdc1-deficient polymorphonuclear cells displayed increased adhesion to endothelial cells and intercellular adhesion molecule-1, and enoxaparin reverted adhesion to wild-type levels. Small interfering RNA-mediated knockdown of Sdc1 expression resulted in reduced basic fibroblast growth factor-mediated mitogen-activated protein kinase signaling and reduced Caco-2 cell proliferation. We conclude that Sdc1 has a protective effect during experimental colitis. The modification of missing Sdc1 function by heparin analogues may emerge as a promising anti-inflammatory approach.

Effects of N-acetylcysteine plus mesalamine on prostaglandin synthesis and nitric oxide generation in TNBS-induced colitis in rats

The aim of the present studies was to examine mechanisms by which the rectally administered combination of N-acetylcysteine (NAC) plus mesalamine (5-ASA) affects inducers of inflammation to promote mucosal healing and reduce tissue inflammation in chemically (trinitrobenzene sulfonic acid, TNBS) induced colitis in rats. Experimental findings demonstrate that dual therapy with NAC plus 5-ASA was superior to individual agents in reducing histological measures of colitis. NAC alone and in combination with 5-ASA suppressed COX2 gene expression and prostaglandin E(2) (PGE(2)) levels to control values. Furthermore, NAC plus 5-ASA reduced nitrate generation, an expression of inducible nitric oxide synthase (iNOS) activity, to basal levels and these results were significantly lower than those observed with either NAC or 5-ASA alone. In conclusion, these results indicate that NAC plus 5-ASA exerts therapeutic benefit, in part by countering the actions of PGE(2) and the deleterious effects of oxidative and nitrosative stress induced by TNBS colitis.

Genetically engineered Lactococcus lactis secreting murine IL-10 modulates the functions of bone marrow-derived dendritic cells in the presence of LPS

Oral delivery of IL-10 by genetically modified Lactococcus lactis (LL-pTmIL10) has been shown to efficiently reduce intestinal inflammation in mice with chronic colitis, but the mechanisms involved have not been elucidated. It has been suggested that IL-10 controls intestinal inflammation by inhibiting microbe-induced activation of dendritic cells. We therefore investigated whether LL-pTmIL10 can modulate the functions of bone marrow-derived dendritic cells (BM-DC) responding to LPS. Incubation of these cells with LL-pTmIL10 or with the control strain LL-pTREX reduced their ability to activate allogeneic T-cell proliferation. However, in contrast to LL-pTREX, LL-pTmIL10 inhibited the LPS-stimulated secretion of MCP-1 by BM-DC and reduced the synergistic up-regulation of IL-12/IL-23p40. In addition, LL-pTmIL10 treatment of LPS-stimulated BM-DC significantly inhibited their capacity to induce strong secretion of IL-17 by CD4+ T cells. Our data suggest that the beneficial effects of LL-pTmIL10 treatment during chronic colitis might involve inhibition of CD4+ Th17 cells and a reduced accumulation of these cells as well as other immune cells at the site of inflammation.

Expression of Pla2g2a prevents carcinogenesis in Muc2-deficient mice

Goblet cell depletion and down-regulation of MUC2 expression are observed in a significant percentage of human non-mucinous colorectal adenocarcinomas. Direct evidence for the role of MUC2 in gastrointestinal tumor formation was demonstrated by a knockout of Muc2 in mice that resulted in the development of adenocarcinomas in the small and large intestine. The secretory phospholipase Pla2g2a is a protein that confers resistance to Apc(Min/+)-induced intestinal tumorigenesis. Like Muc2, in the large intestine Pla2g2a is exclusively expressed by the goblet cells and Pla2g2a's tumor resistance is also strongest in the large intestine. Possible genetic interactions between Muc2 and Pla2g2a were examined by creating C57BL/6-Muc2(-/-)Pla2g2a transgenic mice. Expression of a Pla2g2a transgene reduced tumorigenesis in the large intestine by 90% in male Muc2(-/-) mice and by nearly 100% in female Muc2(-/-) mice. Expression of Pla2g2a also inhibited tumor progression. Microarray gene expression studies revealed Pla2g2a target genes that modulate intestinal energy metabolism, differentiation, inflammation, immune responses and proliferation. Overall, results of the present study demonstrate an Apc-independent role for Pla2g2a in tumor resistance and indicate that Pla2g2a plays an important role, along with Muc2, in protection of the intestinal mucosa.

Dietary Lactoferrin Does Not Prevent Dextran Sulfate Sodium Induced Murine Intestinal Lymphocyte Death

Dextran sulfate sodium (DSS) induced intestinal inflammation is characterized by pronounced mucosal and epithelial cell damage. Bovine lactoferrin (bLf), a common dietary protein, influences inflammatory cytokines and intestinal lymphocyte (IL) apoptosis. The objectives of this study were to determine if 1) DSS induces IL necrotic or apoptotic death, 2) dietary bLf affects DSS induced IL death and 3) bLf alters cytokine profiles during DSS induced inflammation. Female C57BL/6 mice were randomized to 2% or 0% bLf diets for 12 d and within diets to 5% or 0% DSS in the drinking water for 4 d after which intestinal histology, IL number, IL apoptosis/necrosis, IL phenotypes, protein levels of pro-inflammatory cytokine (TNF-α) and transcription factor (NFκB), apoptotic (caspase 3, Bax) proteins, anti-inflammatory cytokine (IL-10) and anti-apoptotic (Bcl-2) protein in IL were evaluated. DSS treatment resulted in shortened intestinal length, decreased body weight and widespread mucosal damage as well as increased IL death as determined by a decreased percentage of viable (PI−/ANN−, P < 0.005) and increased percentage of necrotic/late apoptotic (PI+/ ANN+, P < 0.05) and necrotic (PI+/ANN−, P < 0.05) IL. DSS exposure increased caspase 3 ( P < 0.05) and decreased Bcl-2 ( P < 0.01) protein levels in mouse IL. Dietary bLf did not influence these cell death outcome measures. However, bLf reduced protein levels of the pro-inflammatory transcription factor, NFκB, in IL ( P < 0.05) and was associated with a 34%, albeit non-significant, reduction in TNF-α relative to non-bLf fed mice. DSS treatment increased apoptosis and necrosis of mouse IL and elevated pro-apoptotic and reduced anti-apoptotic protein levels in these cells. Dietary bLf did not influence necrosis or apoptosis of IL but may provide limited protection in the intestine by affecting the pro-inflammatory transcription factor NFκB, and potentially, cytokine expression.

Psychological stress reactivates dextran sulfate sodium-induced chronic colitis in mice

Inflammatory bowel disease (IBD) is a chronic condition with alternating active and quiescent phases of inflammation. Stress has been suggested as a factor triggering a relapse of IBD. We investigated the role of repetitive psychological stress [water avoidance stress (WAS)] in reactivating colonic inflammation in a murine model of dextran sulfate sodium (DSS)-induced chronic colitis. Colitis was induced in C57BL/6 female mice by exposure to 3% DSS (5 days). During chronic inflammation(day 34), mice underwent repetitive WAS (1 h/day/7 days) and were given a sub-threshold concentration of DSS (1%, 5 days)or normal water to drink. At euthanasia (day 40), inflammatory parameters were assessed (colon inflammatory score, levels of inflammatory markers and histology). Mice with chronic colitis exposed to WAS had higher macroscopic and microscopic colonic inflammatory scores and levels of inflammatory markers (mainly IL-1beta, IL12p40 and CCL5) than non-stressed mice. Inflammatory responses were further enhanced by the presence of a sub-threshold concentration of DSS (1%). In mice without chronic inflammation, neither WAS nor 1% DSS, individually or in combination, elicited any inflammation. Hence stress, per se, reactivates a quiescent chronic inflammation, but does not initiate inflammation in healthy mice. Stress should be regarded as an environmental factor triggering IBD relapses in humans.

Blockade of CXCL12/CXCR4 axis ameliorates murine experimental colitis

Recent studies indicate that the CXCL12/CXCR4 interaction is involved in several inflammatory conditions. However, it is unclear whether this interaction has a role in the pathophysiology of inflammatory bowel disease (IBD). We investigated the significance of this interaction in patients with IBD and in mice with dextran sulfate sodium (DSS)-induced colitis and the effect of a CXCR4 antagonist on experimental colitis. First, we measured CXCR4 expression on peripheral T cells in patients with IBD. Furthermore, we investigated CXCR4 expression on leukocytes and CXCL12 expression in the colonic tissue of mice with DSS-induced colitis, and we evaluated the effects of a CXCR4 antagonist on DSS-induced colitis and colonic inflammation of interleukin (IL)-10 knockout (KO) mice. Colonic inflammation was assessed both clinically and histologically. Cytokine production from mesenteric lymph node cells was also examined. CXCR4 expression on peripheral T cells was significantly higher in patients with active ulcerative colitis (UC) compared with normal controls, and CXCR4 expression levels of UC patients correlated with disease activity. Both CXCR4 expression on leukocytes and CXCL12 expression in colonic tissue were significantly increased in mice with DSS-induced colitis. Administration of a CXCR4 antagonist ameliorated colonic inflammation in DSS-induced colitis and IL-10 KO mice. CXCR4 antagonist reduced tumor necrosis factor-alpha and interferon-gamma production from mesenteric lymph node cells, whereas it did not affect IL-10 production. The percentage of mesenteric Foxp3+CD25+ T cells in DSS-induced colitis was not affected by CXCR4 antagonist. These results suggest that blockade of this chemokine axis might have potential as a therapeutic target for the treatment of IBD.

Anti-inflammatory effects and changes in prostaglandin patterns induced by 7beta-hydroxy-epiandrosterone in rats with colitis

High dose levels of dehydroepiandrosterone and its 7-hydroxylated derivatives have been shown to reduce oxidative stress and inflammatory responses in dextran sodium sulfate (DSS)-induced colitis in rats. Another endogenous steroid, 7beta-hydroxy-epiandrosterone (7beta-hydroxy-EpiA) has been shown to exert neuroprotective effects at much smaller doses. Our aims were to evaluate whether 7beta-hydroxy-EpiA pre-treatment prevents DSS-induced colitis and to determine whether the effects involve changes in anti-inflammatory prostaglandin (PG) D(2) and 15-deoxy-Delta(12,14)-PGJ(2) (15d-PGJ(2)) levels. Rats were administered 0.01, 0.1 and 1mg/kg 7beta-hydroxy-EpiA i.p. once a day for 7 days. Thereafter, colitis was induced by administration of 5% DSS in drinking water for 7 days. Levels of the PGs and the expression of cyclooxygenase (COX-2) and PG synthases were assessed during the course of the experiment. Administration of 7beta-hydroxy-EpiA caused a transient increase in COX-2 and PGE synthase expression within 6-15h and augmented colonic tissue levels of 15d-PGJ(2) levels starting at day 2. Treatment with DSS resulted in shortened colon length, depleted mucus in goblet cells and induced oxidative stress. COX-2 and mPGES-1 synthase expression were enhanced and accompanied by increased PGE(2), D(2) and 15d-PGJ(2) production. Although all dose levels of 7beta-hydroxy-EpiA reduced PGE(2) production, only the lowest dose (0.01mg/kg) of the steroid completely prevented colitis damage and tissue inflammation. 7beta-Hydroxy-EpiA pre-treatment prevents the occurrence of DSS-induced colitis through a shift from PGE(2) to PGD(2) production, associated with an early but transient increase in COX-2 expression and a sustained increase in the production of the anti-inflammatory prostaglandin 15d-PGJ(2).

Validation of murine dextran sulfate sodium-induced colitis using four therapeutic agents for human inflammatory bowel disease

Dextran sulfate sodium (DSS)-induced colitis is one of the most frequently used rodent models for inflammatory bowel disease (IBD). The aim of this study was to validate the murine DSS-induced colitis model using four therapeutic agents for IBD. C57BL/6 mice were exposed to 3% DSS for 5days followed by 7-9 days of water (acute inflammation) or 20-31 days of water (chronic phase). Clinical symptoms, plasma and colonic inflammatory markers and histology were assessed for the efficacy of cyclosporine A (CsA), methotrexate or anti-IL-12p40 in acute colitis and of anti-IL-12p40 or an agonistic anti-CD3 antibody in chronic colitis. Cyclosporine A and anti-IL-12p40 (in the acute phase) and anti-CD3 (in the chronic phase) treatment attenuated local cytokine levels, improved clinical symptoms (CsA and anti-IL-12p40) and histology (CsA and anti-CD3). Further, anti-IL-12p40 treatment was partly efficacious in the chronic phase, whereas methotrexate showed no efficacy in the acute colitis. Thus, three of the current tested agents showed efficacy in the disease model, arguing that DSS-induced colitis can be used as a relevant model for the translation of mice data to human disease.

Dextran sulfate sodium-induced colitis generates a transient thymic involution--impact on thymocyte subsets

One of the most widely used animal models for inflammatory bowel disease (IBD) is the dextran sulfate sodium (DSS)-induced colitis. We have previously reported that 5 days administration of DSS in C57Bl/6J mice induces a colonic inflammation that progresses into chronicity after DSS removal, whereas in BALB/cJ mice the inflammation resolves within 4 weeks post-DSS. Here we show that both thymic size and thymocyte numbers dramatically decreased in the acute phase of inflammation in C57Bl/6 mice, 7 days after DSS withdrawal. Mature, CD4(+) and CD8(+) single positive (SP) CD69(lo) CD62L(hi) thymocytes were enriched in these mice, accompanied by a major decrease in the number of immature double positive (DP) thymocytes. However, the different maturation stages within the DP thymocyte subset were unchanged between healthy and inflamed C57Bl/6J mice. Interestingly, as the inflammation progressed into the chronic phase, the thymus recovered and 2 weeks after the acute inflammatory phase all the thymic parameters investigated in this study were restored to normal. In contrast, BALB/cJ mice only develop mild thymic alterations. Nevertheless, we found that within the double negative (DN) thymocytes an increased frequency and also total numbers of CD44(+) CD25(-) (DN1) cells correlated with the severity of colitis, and that the frequency of CD44(-) CD25(-) (DN4) thymocytes decreased proportionally in the acute phase in BALB/cJ mice. Our observations suggest that the thymic effects are intimately connected to the intestinal inflammatory response in colitis regardless of the inflammatory stimuli.