Isolation and characterisation of new putative probiotic bacteria from human colonic flora

The present study describes a novel bacterial isolate exhibiting high ability to synthesise and secrete butyrate. The novel isolated bacterium was obtained from human faeces and grown in selective liquid intestinal microflora medium containing rumen fluid under microaerobic conditions. Its probiotic properties were demonstrated by the ability of the isolate to survive high acidity and medium containing bile acids and the ability to adhere to colon cancer cells (Caco-2) in vitro. Phylogenetic identity to Enterococcus durans was established using specific primers for 16S rRNA (99% probability). PCR analyses with primers to the bacterial gene encoding butyrate kinase, present in the butyrogenic bacteria Clostridium, showed that this gene is present in E. durans. The in vivo immunoprotective and anti-inflammatory effects of E. durans were assessed in dextran sodium sulfate (DSS)-induced colitis in Balb/c mice. Administration of E. durans ameliorated histological, clinical and biochemical scores directly related to intestinal inflammation whereas the lactic acid bacterium Lactobacillus delbrueckii was ineffective in this regard. Colonic cDNA concentrations of IL-1beta and TNF-alpha were significantly down regulated in DSS-treated E. durans-fed mice but not in control or DSS-treated L. delbrueckii- fed mice. Fluorescent in situ hybridisation analyses of colonic tissue from mice fed E. durans, using a butyrate kinase probe, demonstrated that E. durans significantly adheres to the colonic tissue. The novel isolated bacterium described in the present paper, upon further characterisation, can be developed into a useful probiotic aimed at the treatment of patients suffering from ulcerative colitis.

MIP-3alpha neutralizing monoclonal antibody protects against TNBS-induced colonic injury and inflammation in mice

A characteristic feature of human inflammatory bowel disease, particularly Crohn's disease, is the presence of activated CD4(+) T cells. Recently, we have shown that colonic epithelial cell production of macrophage inflammatory protein (MIP)-3alpha, a CD4 T cell-directed chemokine, is elevated in inflammatory bowel disease. However, the functional relevance of MIP-3alpha production during intestinal inflammation is poorly understood. The aim of this study was to determine whether MIP-3alpha production is increased during murine 2,4,6-trinitrobenzene sulfonic acid (TNBS)-induced colitis and to examine the effect of anti-MIP-3alpha neutralizing monoclonal antibody administration in this model. We found that the administration of TNBS significantly increased colonic MIP-3alpha protein levels in Balb/c mice. Consistent with this, a marked increase in the number of CCR6-bearing lamina propria CD4(+) and CD8(+) T cells was also observed in TNBS-treated animals. Treatment of mice with an anti-MIP-3alpha neutralizing monoclonal antibody significantly reduced TNBS-mediated increases in colonic weight-to-length ratio, mucosal ulceration, histological damage, and myeloperoxidase activity. TNBS-mediated increases in the number of CCR6-bearing lamina propria T cells were also substantially reduced by anti-MIP-3alpha neutralizing monoclonal antibody treatment. Taken together, our findings indicate that blockade of MIP-3alpha bioactivity can significantly reduce TNBS-mediated colonic injury and T cell recruitment, suggesting a role for this chemokine in the pathophysiology of intestinal inflammation.

Effects of the probiotic formulation VSL#3 on colitis in weanling rats

BACKGROUND

Only a few studies have used models of inflammatory bowel disease (IBD) with weanling animals. Previously, the effects of probiotics have not been assessed in such IBD models. The objectives of our study were 2-fold: to establish a suitable model of dextran sulfate sodium (DSS)-induced colitis in weanling rats and to determine the effects of the probiotic formulation VSL#3 on DSS-induced colitis in weanling animals.

MATERIALS AND METHODS

Rats were weaned on postnatal day 21 and administered 2%, 2.5%, or 3% (wt/vol) DSS in drinking water. In subsequent experiments, newly weaned animals were administered vehicle or VSL#3 (0.06, 0.6, or 6 mg) by orogastric gavage. These treatments were given to animals maintained on water (postnatal days 21-28) and then on DSS (postnatal days 28-35). Disease activity indices were determined on a routine basis. On day 35, rats were euthanized. The total colon length was determined. Other parameters of colitis were measured from the distal colon. These parameters included myeloperoxidase (MPO), interleukin (IL)-1beta, inhibitory kappaB-alpha (IkappaB-alpha), and histological assessment of crypt damage and inflammation.

RESULTS

DSS 2% was optimal for inducing colitis in weanling rats without significant morbidity. VSL#3 treatments improved various parameters of 2% DSS-induced colitis in weanling rats. The 0.6- and 6-mg doses of VSL#3 were most effective for attenuating this colitis.

CONCLUSIONS

The probiotic formulation VSL#3 improved DSS-induced colitis in weanling rats. This improvement of colitis involved changes in colonic IkappaB-alpha, IL-1beta, and MPO, which are suggestive of immune modulation by VSL#3.

Glutamine inhibits over-expression of pro-inflammatory genes and down-regulates the nuclear factor kappaB pathway in an experimental model of colitis in the rat

We investigated the effects of glutamine on markers of oxidative stress, nuclear factor kappaB (NF-kappaB) activation, and pro-inflammatory mediators in a rat model of experimental colitis induced by intracolonic administration of 7% acetic acid. Glutamine (25 mg/kg) was given by rectal route 48 and 24h before acetic acid instillation. Glutamine significantly reduced gross damage and histopathological scores, and partially prevented the decrease of anal pressure observed in the animals receiving acetic acid. Increases in the cytosolic concentration of TBARS and hydroperoxide-initiated chemiluminescence were significantly prevented in glutamine-treated animals. Acetic acid instillation induced a marked increase of the NF-kappaB p65 subunit expression in the nucleus and resulted in significant changes in the cytosolic protein level of IkappaB kinases (IKKalpha and IKKbeta) and the non-phosphorylated form of the inhibitor IkappaBalpha. Protein levels of inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2) were significantly increased. All these effects were partially prevented by administration of glutamine. It is concluded that the anti-inflammatory activity of glutamine in a rat model of acetic acid-induced colitis may be mediated, at least in part, by inhibition of the expression of certain pro-inflammatory mediators which are regulated by the oxidative stress-sensitive NF-kappaB signalling pathway.

Peroxisome proliferator-activated receptor gamma is required for regulatory CD4+ T cell-mediated protection against colitis

Peroxisome proliferator-activated receptor (PPAR) gamma activation has been implicated in the prevention of immunoinflammatory disorders; however, the mechanisms of regulation of effector and regulatory CD4+ T cell functions by endogenously activated PPAR-gamma remain unclear. We have used PPAR-gamma-deficient CD4+ T cells obtained from tissue-specific PPAR-gamma null mice (i.e., PPAR-gamma fl/fl; MMTV-Cre+) to investigate the role of endogenous PPAR-gamma on regulatory T cell (Treg) and effector CD4+ T cell function. Overall, we show that the loss of PPAR-gamma results in enhanced Ag-specific proliferation and overproduction of IFN-gamma in response to IL-12. These findings correlate in vivo with enhanced susceptibility of tissue-specific PPAR-gamma null mice to trinitrobenzene sulfonic acid-induced colitis. Furthermore, the transfer of purified PPAR-gamma null CD4+ T cells into SCID recipients results in enteric disease. To test the assertion that the deficiency of PPAR-gamma in Treg impairs their ability to prevent effector T cell-induced colitis, we performed cotransfer studies. These studies demonstrate that PPAR-gamma-expressing, but not PPAR-gamma null Treg, prevent colitis induced by transfer of naive CD4+ T cells into SCID recipients. In line with these findings, the production of IFN-gamma by spleen and mesenteric lymph node-derived CD4+ T cells was down-regulated following transfer of PPAR-gamma-expressing, but not PPAR-gamma null, Treg. In conclusion, our data suggest that endogenous PPAR-gamma activation represents a Treg intrinsic mechanism of down-regulation of effector CD4+ T cell function and prevention of colitis.

Therapeutic and prophylactic thalidomide in TNBS-induced colitis: Synergistic effects on TNF-α, IL-12 and VEGF production

AIM: To evaluated the therapeutic and prophylactic effect of thalidomide on 2, 4, 6-trinitrobenzene sulfonic acid (TNBS)-induced colitis. Thalidomide has been reported to downregulate the expression of tumor necrosis factor α (TNF-α), IL-12, and vascular endothelial growth factor (VEGF), hallmarks of intestinal inflammation in Crohn’s disease (CD).

METHODS: Male Wistar rats were divided in five groups of ten animals each. Four groups received a rectal infusion of TNBS in ethanol. The first group was sacrificed 7 d after colitis induction. The second and third groups received either thalidomide or placebo by gavage and were sacrificed at 14 d. The fourth group received thalidomide 6 h before TNBS administration, and was sacrificed 7 d after induction. The fifth group acted as the control group and colitis was not induced. Histological inflammatory scores of the colon were performed and lamina propria CD4+ T cells, macrophages, and VEGF+ cells were detected by immunohistochemistry. TNF-α and IL-12 were quantified in the supernatant of organ cultures by ELISA.

RESULTS: Significant reduction in the inflammatory score and in the percentage of VEGF+ cells was observed in the group treated with thalidomide compared with animals not treated with thalidomide. Both TNF-α and IL-12 levels were significantly reduced among TNBS induced colitis animals treated with thalidomide compared with animals that did not receive thalidomide. TNF-α levels were also significantly reduced among the animals receiving thalidomide prophylaxis compared with untreated animals with TNBS-induced colitis. Intestinal levels of TNF-α and IL-12 were significantly correlated with the inflammatory score and the number of VEGF+ cells.

CONCLUSION: Thalidomide significantly attenuates TNBS-induced colitis by inhibiting the intestinal production of TNF-α, IL-12, and VEGF. This effect may support the use of thalidomide as an alternate approach in selected patients with CD.

Tolerogenic dendritic cells pulsed with enterobacterial extract suppress development of colitis in the severe combined immunodeficiency transfer model

Immunomodulatory dendritic cells (DCs) that induce antigen-specific T-cell tolerance upon in vivo adoptive transfer are promising candidates for immunotherapy of autoimmune diseases. The feasibility of such a strategy has recently proved its efficacy in animal models of allotransplantation and experimental allergic encephalitis, but the effect in inflammatory bowel disease has not yet been demonstrated. In severe combined immunodeficient (SCID) mice, adoptively transferred CD4(+) CD25(-) T cells repopulate the lymphoid tissues and lead to development of chronic colitis characterized by CD4(+) T-cell proliferation against enterobacterial extract in vitro. In this model, we adoptively transferred in-vitro-generated bone-marrow-derived DCs exposed to interleukin-10 (IL-10) and an enterobacterial extract. We show that these cells are CD11c positive with intermediate expression of CD40, CD80 and CD86 and have a diminished secretion of IL-6, IL-12 p40/70, tumour necrosis factor-alpha and keratinocyte-derived chemokine (KC) compared to DCs treated with enterobacterial extract alone. In vivo, these cells prevented weight loss in SCID mice adoptively transferred with CD4(+) CD25(-) T cells, resulted in a lower histopathology colitis score and tended to result in higher serum levels of IL-1alpha, IL-10, IL-12, IL-13, IL-17, KC and monokine induced by interferon-gamma (MIG). These data underscore the potential of using immunomodulatory DCs to control inflammatory bowel disease and demonstrate its potential use in future human therapeutic settings.

Melphalan in ultralow doses decreases the severity of experimental colitis in mice

We studied the effect of melphalan in ultralow doses on mice with experimental colitis induced by substitution of drinking water for 5% dextran sulfate. Daily treatment with melphalan in a dose of 0.025 mg/kg improved the general state of animals. The influence of melphalan was evaluated by quantitative clinical, pathomorphological, and laboratory parameters. Melphalan had a local and systemic antiinflammatory effect.

Protective effect of melatonin in acetic acid induced colitis in rats

Possible protective effects of exogenous melatonin on colonic inflammation were studied in rats. Colitis was induced by intracolonic (i.c.) instillation of 4% acetic acid (AA) and the resulting injury was assessed after 1 and 48 hr. Diffuse hyperemia and bleeding with erosions and ulcerations were observed in the colons of vehicle-treated rats. Melatonin administered in doses of 5 and 10 mg/kg reduced significantly the extent of gross mucosal damage after intraperitoneal as well as i.c. dosing. The inflammation induced increase in colonic wet weight was also reduced by melatonin treatment. In the early phase of colonic inflammation (60 min), melatonin partly prevented the decrease of reduced glutathione (GSH) content and limited lysosomal enzyme, N-acetyl-glucosaminidase and cathepsin D, activities induced by AA, with no changes in proteins or acid phosphatase activity. Increase of myeloperoxidase activity (MPO) caused by colonic inflammation was prevented by melatonin given i.c. As observed 48 hr after AA exposure, there was no difference between the effect of vehicle and melatonin on the content of GSH. Colitis did not influence the melatonin content of the colon. After administration of exogenous melatonin, plasma, pineal and gut melatonin tended to increase. The results indicate that melatonin participates in various defense mechanisms against colonic inflammatory processes by preserving the important endogenous antioxidant reserve of GSH, by preventing lysosomal enzyme disruption, by inhibiting enhanced MPO activity, thus reducing the extent of colonic damage, mainly in the early phase of colitis.

Pregnane X receptor activation ameliorates DSS-induced inflammatory bowel disease via inhibition of NF-kappaB target gene expression

Pregnane X receptor (PXR) expression was shown to be protective in inflammatory bowel disease (IBD). However, the mechanism by which PXR provides protection remains unclear. Wild-type and Pxr-null mice were treated with the PXR agonist pregnenolone-16alpha-carbonitrile or vehicle and administered 2.5% dextran sulfate sodium (DSS) in drinking water to induce IBD. Typical clinical symptoms were evaluated on a daily basis. In vivo intestinal permeability assays and proinflammatory cytokine analysis were performed. PXR agonist-treated mice were protected from DSS-induced colitis compared with vehicle-treated mice, as defined by body weight loss, diarrhea, rectal bleeding, colon length, and histology. Pregnenolone-16alpha-carbonitrile did not decrease the severity of IBD in Pxr-null mice. PXR agonist treatment did not increase epithelial barrier function but did decrease mRNA expression of several NF-kappaB target genes in a PXR-dependent manner. The present study clearly demonstrates a protective role for PXR agonist in DSS-induced IBD. The data suggest that PXR-mediated repression of NF-kappaB target genes in the colon is a critical mechanism by which PXR activation decreases the susceptibility of mice to DSS-induced IBD.

A key role of dendritic cells in probiotic functionality

BACKGROUND

Disruption of the intestinal homeostasis and tolerance towards the resident microbiota is a major mechanism involved in the development of inflammatory bowel disease. While some bacteria are inducers of disease, others, known as probiotics, are able to reduce inflammation. Because dendritic cells (DCs) play a central role in regulating immune responses and in inducing tolerance, we investigated their role in the anti-inflammatory potential of probiotic lactic acid bacteria.

METHODOLOGY/PRINCIPAL FINDINGS

Selected LAB strains, while efficiently taken up by DCs in vitro, induced a partial maturation of the cells. Transfer of probiotic-treated DCs conferred protection against 2, 4, 6-trinitrobenzenesulfonic acid (TNBS)-induced colitis. Protection was associated with a reduction of inflammatory scores and colonic expression of pro-inflammatory genes, while a high local expression of the immunoregulatory enzyme indolamine 2, 3 dioxgenase (IDO) was observed. The preventive effect of probiotic-pulsed DCs required not only MyD88-, TLR2- and NOD2-dependent signaling but also the induction of CD4+ CD25+ regulatory cells in an IL-10-independent pathway.

CONCLUSIONS/SIGNIFICANCE

Altogether, these results suggest that selected probiotics can stimulate DC regulatory functions by targeting specific pattern-recognition receptors and pathways. The results not only emphasize the role of DCs in probiotic immune interactions, but indicate a possible role in immune-intervention therapy for IBD.

The bisphosphonate alendronate improves the damage associated with trinitrobenzenesulfonic acid-induced colitis in rats

BACKGROUND AND PURPOSE

The nitrogen-containing bisphosphonates are drugs used successfully in the treatment of osteoporosis. They act inhibiting farnesyl diphosphate synthase. This mechanism may also produce anti-inflammatory effects. The therapeutic activity of alendronate was tested in vivo using a model of inflammatory bowel disease.

EXPERIMENTAL APPROACH

The trinitrobenzenesulfonic acid model of colitis in the rat was used. Rats were treated orally with alendronate and its efficacy compared with that of oral sulphasalazine or vehicle, starting 2 h after colitis induction. The status of the animals was assessed 5 days later.

KEY RESULTS

Alendronate treatment (25 or 75 mg kg(-1) day(-1)) resulted in a decrease in the colonic damage score and loss of body weight (at 25 mg kg(-1) day(-1) only). This was associated to a dramatic reduction in the mRNA levels of interleukin 1 beta (IL-1 beta), monocyte chemoattractant protein 1 (MCP-1) and interleukin 1 receptor antagonist (IL-1 ra). The magnitude of the beneficial effect was comparable to that of sulphasalazine (at a 6-20 fold higher dose). Thus sulphasalazine post-treatment reduced the mRNA levels of IL-1 beta/IL-1 ra and MCP-1 to the same extent as alendronate and additionally lowered colonic alkaline phosphatase activity, but failed to affect body weight loss or colonic damage score. Alendronate failed to exert beneficial effects when administered intraperitoneally.

CONCLUSIONS AND IMPLICATIONS

Oral but not intraperitoneal alendronate significantly protected the colon in experimental rat colitis. Inflammatory bowel disease patients might benefit from exposure to oral alendronate.

Enhanced activity of a hydrogen sulphide-releasing derivative of mesalamine (ATB-429) in a mouse model of colitis

BACKGROUND AND PURPOSE

Mesalamine is the first-line therapy for colitis, but it lacks potency and is only effective for mild-to-moderate forms of this disease. Hydrogen sulphide has been shown to be a potent, endogenous anti-inflammatory substance, modulating leukocyte-endothelial adhesion and leukocyte migration. The purpose of this study was to determine if an H(2)S-releasing derivative of mesalamine (ATB-429) would exhibit increased potency and effectiveness in a mouse model of colitis.

EXPERIMENTAL APPROACH

Colitis was induced in mice with trinitrobenzene sulphonic acid and the effects of ATB-429 and mesalamine were compared in several treatment regimens. The severity of colitis was determined using several indices, including a disease activity score (comprised of scores for diarrhea, weight loss and fecal blood), colonic myeloperoxidase activity and macroscopic/microscopic scoring of tissue injury.

KEY RESULTS

Irrespective of the treatment regiment, ATB-429 was more effective than mesalamine in reducing the severity of colitis. ATB-429 was particularly effective in reducing granulocyte infiltration into the colonic tissue (by approximately 70%), as well as reducing the expression of mRNA for several key proinflammatory cytokines/chemokines (e.g., TNFalpha, IFNgamma). Treatment with ADT-OH, the H(2)S-releasing moiety of ATB-429, did not affect severity of colitis.

CONCLUSIONS AND IMPLICATIONS

ATB-429 exhibits a marked increase in anti-inflammatory activity and potency in a murine model of colitis, as compared to mesalamine. These results are consistent with recently described anti-inflammatory effects of H(2)S. ATB-429 may represent an attractive alternative to mesalamine for the treatment of inflammatory bowel disease.

Physiological activities of carbon monoxide-releasing molecules: Ca ira

In this issue of British Journal of Pharmacology, Megías and colleagues demonstrate how preincubation of human colonic Caco-2 cells with CORM-2, a carbon monoxide releasing molecule (CO-RM), reduces the expression of inducible nitric oxide synthase, interleukin (IL)-6 and IL-8 caused by proinflammatory cytokines. A role for IL-6 in the regulation of metalloproteinase (MMP)-7 expression by CORM-2 is described. However, it is the demonstration that CORM-2 inhibits MMP-7 or matrilysin expression, which is most intriguing as this small MMP has been implicated in carcinogenesis. Thus, CO-RMs appear to now possess chemoprotective properties and, in this particular case, may influence inflammation-induced colon carcinogenesis via modulation of nuclear factors participating in the transcription of genes implicated in the development of intestinal inflammation and cancer. This report opens yet another door for research involving these exciting molecules and it is now clear that further discoveries of the beneficial properties of CO-RMs will go on.

Characterization of the immuno-regulatory response to the tapeworm Hymenolepis diminuta in the non-permissive mouse host

Hymenolepis diminuta is spontaneously expelled from mice; concomitant with worm expulsion was protection against colitis induced by dinitrobenzene sulphonic acid (DNBS). Here we examined the immune response mobilized by Balb/c and C57Bl/6 male mice in response to H. diminuta and assessed the requirement for CD4+ cells (predominantly T cells) in worm expulsion and the anti-colitic effect. Wild-type (CD4+) or CD4 knock-out (CD4-/-) mice received five H. diminuta cysticercoids and segments of jejunum and mesenteric lymph nodes (MLNs), or spleen, were excised 5, 8 and 1l days later for mRNA analysis and cytokine production, respectively. In separate experiments uninfected and infected mice received DNBS by intra-rectal infusion and indices of inflammation were assessed 3 days later (i.e. 11 days p.i.). Infection of Balb/c mice resulted in a time-dependent increase in intestinal mRNA for Foxp3, a marker of natural regulatory T cells, and markers of alternatively activated macrophages (arginase-1, FIZZ1), while concanavalin-A activation of MLN cells revealed a significant increase in T helper 2 (TH2) type cytokines: IL-4, -5, -9, -10, -13. MLN cells showed a reduced ability to induce Foxp3 expression upon stimulation. CD4-/- mice did not display this response to infection, but surprisingly did expel H. diminuta. Moreover, DNBS-induced colitis in CD4-/- mice (wasting, tissue damage, elevated myeloperoxidase) was not reduced by H. diminuta infection, whereas time-matched infected CD4+ C57Bl/6 mice had significantly less DNBS-induced inflammation.

IN CONCLUSION

(i) in addition to stereotypical TH2 events, H. diminuta-infected Balb/c mice develop a local immuno-regulatory response; and (ii) CD4+ cells are not essential for H. diminuta expulsion from mice but are critical in mediating the anti-colitic effect that accompanies infection in this model.

Prevention of experimental colitis by parenteral administration of a pathogen-derived immunomodulatory molecule

BACKGROUND

Filamentous haemagglutinin (FHA) of Bordetella pertussis subverts host immune responses by inhibiting interleukin (IL)12 and enhancing IL10 production by macrophages and dendritic cells, and promoting the induction of regulatory T cells.

HYPOTHESIS

Injection of FHA would ameliorate disease in a T cell-dependent model of colitis via the induction of anti-inflammatory cytokines and regulatory T cells.

METHODS

Colitis was induced by injection of CD4CD45RB(high) naive T cells into severe combined immunodeficient (SCID) mice. Mice were treated with four subcutaneous injections of FHA or buffer alone.

RESULTS

Parenteral injection of FHA stimulated IL10 and/or transforming growth factor beta production in local and mesenteric lymph nodes and Peyer's patches of mice 2-6 h after administration. Compared with phosphate-buffered saline-treated mice, FHA-treated SCID mice had significantly (p<0.01) less weight loss, lower colon weight, less colon shrinkage and reduced inflammatory lesions. The therapeutic effect of FHA was associated with enhanced IL10 and reduced type 1 and type 2 T helper cytokine production by spleen cells. Finally, FHA also attenuated the symptoms of colitis in SCID mice transferred with CD4CD45RB(high) T cells from IL10-deficient mice.

CONCLUSIONS

Our finding shows that FHA suppresses type 1 T helper and pro-inflammatory cytokines, and ameliorates disease activity in a chronic T cell-dependent model of colitis, an effect that was not dependent on IL10 production by T cells, but was associated with induction of anti-inflammatory cytokines in vivo. Having already been used as a pertussis vaccine component in children, FHA is a promising candidate for clinical testing in patients with Crohn's disease.

Schistosoma japonicum eggs modulate the activity of CD4+ CD25+ Tregs and prevent development of colitis in mice

Crohn's disease (CD) is considered to be caused by a disorder of the immune system and helminth infections may interact with development of the disease. We induced colitis in mice by trinitrobenzenesulfonic acid (TNBS) and observed the effects of intraperitoneally injected eggs of Schistosoma japonicum on the course of the disease. The inflammation in the colon was reduced in egg-treated mice and secretion of IFN-gamma (a Th1 cytokine) by cultured spleen cells in vitro was greatly suppressed, and of IL-4, IL-5 and IL-10 (Th2 cytokines) significantly elevated after egg injection. Also, the percentage of regulatory T-cells (Tregs) was increased in the spleens of egg-exposed mice with TNBS-induced colitis compared to non-egg exposed animals. The data suggest that Tregs may be activated by S. japonicum eggs and play a role in restoring immune disorders in TNBS-induced colitis of mice.

Adiponectin deficiency protects mice from chemically induced colonic inflammation

BACKGROUND & AIMS

Adiponectin (APN) is an adipokine that regulates insulin sensitivity and is anti-inflammatory in atherosclerosis. The goal of this study was to investigate the role of APN in intestinal inflammation.

METHODS

APN knockout (KO) mice and their wild-type (WT) littermates received dextran sulfate sodium (DSS) or trinitrobenzene sulfonic acid (TNBS) to induce intestinal inflammation. Clinical and histologic scores and proliferation of epithelial cells were assessed. Cytokines and APN levels were measured. Expression of APN and heparin binding epidermal growth factor (HB-EGF) was analyzed by immunohistochemistry. Expression of APN and its receptors, HB-EGF, and basic fibroblast growth factor (bFGF) messenger RNA was assessed by reverse-transcription polymerase chain reaction. Association of serum APN with HB-EGF and bFGF was studied by coimmunoprecipitation.

RESULTS

APN KO mice are protected from chemically induced colitis; administration of APN restores inflammation. APN is expressed in the colon, luminal APN associates with colonic epithelial cells. In vitro, APN increases production of proinflammatory cytokines from colonic tissue. Expression of colonic APN overlaps with that of bFGF and HB-EGF, which play a protective role in colitis. Circulating APN binds to bFGF and HB-EGF, likely inhibiting their protective activity. Inhibition of EGF receptor signaling, which is required for biologic activity of HB-EGF, restores inflammation in APN KO mice.

CONCLUSIONS

APN deficiency is associated with protection from chemically induced colitis. APN exerts proinflammatory activities in the colon by inducing production of proinflammatory cytokines and inhibiting bioactivity of protective growth factors. Thus, in colitis, APN exerts an opposite role compared with atherosclerosis.

Correlation between in vitro and in vivo immunomodulatory properties of lactic acid bacteria

AIM: To investigate the correlation between the in vitro immune profile of probiotic strains and their ability to prevent experimental colitis in mice.

METHODS: in vitro immunomodulation was assessed by measuring interleukin (IL)-12p70, IL-10, tumor necrosis factor alpha (TNFα) and interferon γ (IFNγ) release by human peripheral blood mononuclear cells (PBMCs) after 24 h stimulation with 13 live bacterial strains. A murine model of acute TNBS-colitis was next used to evaluate the prophylactic protective capacity of the same set of strains.

RESULTS: A strain-specific in vivo protection was observed. The strains displaying an in vitro capacity to induce higher levels of the anti-inflammatory cytokine IL-10 and lower levels of the inflammatory cytokine IL-12, offered the best protection in the in vivo colitis model. In contrast, strains leading to a low IL-10/IL-12 cytokine ratio could not significantly attenuate colitis symptoms.

CONCLUSION: These results show that we could predict the in vivo protective capacity of the studied lactic acid bacteria (LAB) based on the cytokine profile we established in vitro. The PBMC-based assay we used may thus serve as a useful primary indicator to narrow down the number of candidate strains to be tested in murine models for their anti-inflammatory potential.

Inhibition of Helicobacter hepaticus-induced colitis by IL-10 requires the p50/p105 subunit of NF-kappa B

Defects within the innate immune system sensitize NF-kappaB-deficient (p50(-/-); p65(+/-)) mice to Helicobacter hepaticus (Hh)-induced colitis. Because IL-10 plays a central role in the inhibition of Hh-induced colitis, we hypothesized that the ability of IL-10 to inhibit the innate inflammatory response to Hh may be compromised in NF-kappaB-deficient mice. To test this hypothesis, we evaluated the ability of an IL-10-Ig fusion protein with IL-10-like properties to inhibit Hh-induced colitis in RAG-2(-/-) (RAG) and p50(-/-); p65(+/-); RAG-2(-/-) (3X/RAG) mice. As expected, IL-10-Ig efficiently inhibited the development of colitis in RAG mice. In contrast, the ability of IL-10-Ig to inhibit colitis was compromised in 3X/RAG mice. The defect in response to IL-10-Ig appeared to be primarily the result of the absence of the p50/p105 subunit, because the ability of IL-10-Ig to inhibit colitis was also compromised in p50(-/-); RAG-2(-/-) (p50/RAG) mice. Radiation chimeras demonstrated that the presence of p50/p105 within hemopoietic cells of the innate immune system was necessary for efficient inhibition of colitis by IL-10-Ig. Consistent with a defect in the suppressive effects of IL-10 in the absence of p50/p105, we found that the ability of IL-10 to control LPS-induced expression of IL-12 p40 was significantly compromised in macrophages lacking p50/p105. These results suggest that the absence of the p50/p105 subunit of NF-kappaB within hemopoietic cells of the innate immune system interferes with the ability of IL-10 to suppress inflammatory gene expression and Hh-induced colitis.

Anti-inflammatory potential of the probiotic dietary supplement Lactibiane Tolérance: In vitro and in vivo considerations

BACKGROUND & AIMS

Probiotics are live microorganisms which when administered in adequate amounts confer a health benefit on the host. In inflammatory bowel disease (IBD), where major modifications of the intestinal microflora have been reported, there is an increasing interest in modulating the flora with probiotic products. This work addresses the anti-inflammatory potential of Lactibiane Tolérance, a probiotic dietary supplement (mixture of four strains) using in vitro and in vivo approaches.

METHODS

Comparison of the four individual strains and the commercial product reconstituted from them was conducted by in vitro tests (cytokine release after 24h stimulation of human peripheral blood mononuclear cells (PBMC)). The potential immunomodulatory characteristics of Lactibiane Tolérance were determined in vivo in an acute mice model of 2,4,6-trinitrobenzene sulfonic acid (TNBS)-induced colitis. Assessment of colitis included blinded histological and macroscopic scores.

RESULTS

We showed that Lactibiane Tolérance has anti-inflammatory properties in vitro by stimulating IL-10 production and in vivo by conferring a significant protective effect in the TNBS-induced colitis model (more than 50% decrease of colitis symptoms, P<0.01).

CONCLUSIONS

These results demonstrate that a probiotic dietary supplement, Lactibiane Tolérance, can significantly prevent the initial injury of TNBS and could stimulate the initiation of clinical trials in IBD.

Therapeutic treatment of experimental colitis with regulatory dendritic cells generated with vasoactive intestinal peptide

BACKGROUND & AIMS

Crohn's disease is a chronic debilitating disease characterized by severe T helper cell (Th)1-driven inflammation of the colon partially caused by a loss of immune tolerance against mucosal antigens. The use of regulatory dendritic cells (DCs) with the capacity to induce regulatory T cells has been proposed recently for the treatment of Crohn's disease in a strategy to restore immune tolerance. Vasoactive intestinal peptide is an immunomodulatory neuropeptide that induces regulatory DCs. The aim of this study was to investigate the therapeutic effect of vasoactive intestinal peptide-induced regulatory DCs (DC(VIP)) in a murine model of colitis.

METHODS

We examined the therapeutic action of DC(VIP) in the colitis induced by intracolonic administration of trinitrobenzene sulfonic acid, evaluating diverse clinical signs of the disease including weight loss, diarrhea, colitis, and histopathology. We also investigated the mechanisms involved in the potential therapeutic effect of DC(VIP), such as inflammatory cytokines and chemokines, Th1-type response, and the generation of regulatory T cells.

RESULTS

DC(VIP) injection significantly ameliorated the clinical and histopathologic severity of colitis, abrogating body weight loss, diarrhea, and inflammation, and increasing survival. The therapeutic effect was associated with down-regulation of both inflammatory and Th1-driven autoimmune response, by regulating a wide spectrum of inflammatory mediators directly through activated macrophages, and by generating interleukin-10-secreting regulatory T cells with suppressive capacity on autoreactive T cells.

CONCLUSIONS

The possibility to generate/expand ex vivo regulatory DC(VIP) opens new therapeutic perspectives for the treatment of Crohn's disease in human beings, and may minimize the dependence on nonspecific immunosuppressive drugs used currently for autoimmune disorders.

Inhibition of Smad7 with a specific antisense oligonucleotide facilitates TGF-beta1-mediated suppression of colitis

BACKGROUND & AIMS

Defective transforming growth factor (TGF)-beta1 signaling due to high levels of Smad7 is a feature of inflammatory bowel disease (IBD). In this study, we analyzed the effect of reducing Smad7 levels with antisense oligonucleotide on mouse models of colitis.

METHODS

Mucosal samples taken from colitic tissue of mice with colitis due to either haptenating reagents (trinitrobenzene sulfonic acid [TNBS] or oxazolone) or to transfer of T cells (SCID transfer colitis) were analyzed for Smad3 and/or Smad7 expression by Western blotting and, in some cases, content of TGF-beta1 by enzyme-linked immunosorbent assay. The effect of oral Smad7 antisense oligonucleotide on mucosal inflammation was assessed.

RESULTS

TGF-beta1 levels were increased in the inflamed tissues of mice with colitis induced by either TNBS or oxazolone. Nevertheless, TGF-beta1 did not exert a regulatory effect, probably because TGF-beta1 signaling was blocked, as indicated by the presence of reduced Smad3 phosphorylation and high levels of Smad7. Oral administration of Smad7 antisense oligonucleotide to colitic mice restored TGF-beta1 signaling via Smad3 and ameliorated inflammation in hapten-induced colitis. In addition, Smad7 antisense oligonucleotide had a therapeutic effect on relapsing TNBS-induced colitis but not on cell-transfer colitis.

CONCLUSIONS

These data suggest that colitis models associated with high endogenous TGF-beta1 levels and defective TGF-beta1 signaling due to high levels of Smad7 can be ameliorated by down-regulation of Smad7 and by oral administration of Smad7 antisense oligonucleotide. This may represent a new approach to the control of IBD, particularly during active phases when its Smad7 profile resembles that of hapten-induced colitis.

Lactobacillus fermentum, a probiotic capable to release glutathione, prevents colonic inflammation in the TNBS model of rat colitis

BACKGROUND AND AIMS

Inflammatory bowel disease is associated with intestinal oxidative stress. In the present study we test the preventative effect of Lactobacillus fermentum, a probiotic that produces per se glutathione, in the trinitrobenzenesulphonic acid (TNBS) model of rat colitis.

METHODS

Colitis was induced in rats by intracolonic administration of 10 mg of TNBS dissolved in 0.25 ml of 50% ethanol. L. fermentum was administered orally (5x10(8) CFU suspended in 0.5 ml of skim milk) to a group of rats for 3 weeks, starting 2 weeks before colitis induction. Colonic damage was evaluated both histologically and biochemically, and the colonic luminal contents were used for bacterial studies as well as for short chain fatty acid (SCFA) production.

RESULTS

L. fermentum treatment resulted in an amelioration of the inflammatory response in colitic rats as evidenced histologically and by a significant reduction of colonic MPO activity (P<0.05). The probiotic partially counteracted the colonic glutathione depletion induced by the inflammatory process. In addition, probiotic-treated colitic rats showed significant lower colonic tumour necrosis factor (TNF)alpha levels (P<0.01) and inducible nitric oxide synthase (iNOS) expression when compared to non-treated rats. Finally, the probiotic induced growth of Lactobacilli species and production of SCFA in colonic contents in comparison with control colitic rats.

CONCLUSION

Administration of the probiotic L. fermentum facilitates the recovery of the inflamed tissue in the TNBS model of rat colitis, an effect associated with increased levels of glutathione as well as with amelioration of the production of some of the mediators involved in the inflammatory response of the intestine, such as TNFalpha and NO.

Rapamycin decreases leukocyte migration in vivo and effectively reduces experimentally induced chronic colitis

BACKGROUND

Immunosuppressive calcineurin inhibitors, like cyclosporine (CsA), can be used for the clinical management of severe ulcerative colitis. However, patients treated with CsA are at a risk for developing kidney failure and may be more susceptible to colon cancer. Furthermore, severe neurotoxicity and hypertension are common problems. To avoid the side effects of CsA, new immunosuppressive drugs to treat colitis are needed. The aim of the present study was to test the immunosuppressive mammalian target of rapamycin inhibitor rapamycin in an experimental model of chronic colitis and to compare its effectiveness with CsA.

METHODS

Chronic colitis was established in Balb/c mice after four feeding cycles of dextran sodium sulfate. Because leukocyte recruitment to sites of intestinal inflammation is crucial for the development of chronic colitis, intravital microscopy was used to study the effect of rapamycin and CsA on leukocyte-endothelium interactions and leukocyte extravasation. To assess the degree of colitis, histological sections were evaluated.

RESULTS

Both rapamycin and cyclosporine effectively reduced leukocyte sticking (>60%) in submucosal venules, as compared to controls. Furthermore, rapamycin, but not CsA, reduced (>35%) leukocyte extravasation in the mucosa. Both rapamycin and CsA treatments significantly improved the histologic inflammation score.

CONCLUSION

Our in vivo results demonstrate that rapamycin reduces leukocyte sticking and extravasation during chronic colitis induction and proves to be as effective as CsA at reducing experimental chronic colitis. These results support the use of rapamycin in clinical trials to avoid serious side effects of CsA therapy in chronic colitis patients.