Nuclear factor-kappa B activity and intestinal inflammation in dextran sulphate sodium (DSS)-induced colitis in mice is suppressed by gliotoxin

Polysaccharides from soybean residue fermented by Neurospora crassa alleviate DSS-induced gut barrier damage and microbiota disturbance in mice

Soluble polysaccharides derived from microbial fermentation of agricultural by-products were considered as potential functional ingredients, primarily having probiotic properties. Herein, soluble polysaccharides (FSRP) were isolated from soybean residue fermented by Neurospora crassa, and FSRP mainly contained rhamnose, arabinose, fucose, mannose, glucose, and galactose, according to GC-MS analysis. To further investigate the protective effect of FSRP against colitis, dextran sulfate sodium induction (DSS)-treated mice were orally gavaged with FSRP (200 mg kg-1 d-1) or inulin (400 mg kg-1 d-1, a positive control) for 7 d. The results showed that DSS-treated mice displayed symptoms of body weight loss, atrophy, and histopathological changes of colon, as well as gut barrier damage, which were recovered after FSRP supplementation (similar to inulin). Furthermore, the beneficial effects of FSRP were linked to a decreased inflammatory response and increased protein expression of E-cadherin, claudin-1 and ZO-1. Illumina-MiSeq sequencing analysis revealed that FSRP increased microbial diversity and altered community structure. Specifically, FSRP could modulate the abundance of inflammation-related bacteria (such as Tenericutes, Clostridia, and Bacilli) to ameliorate colitis symptoms. Therefore, FSRP can relieve DSS-induced colitis, which is closely associated with reduced levels of inflammatory factors, improved gut barrier function and gut microbiota homeostasis.

PRKAR2A-derived circular RNAs promote the malignant transformation of colitis and distinguish patients with colitis-associated colorectal cancer

BACKGROUND

Emerging studies have proved that colonic inflammation caused by refractory inflammatory bowel disease (IBD) can initiate the colitis-associated cancer (CAC), but the transition from inflammation to carcinoma is still largely unknown.

METHODS

In this study, mouse colitis and CAC models were established, and the RNA-seq by circRNA microarray was employed to identify the differentially expressed circRNAs and mRNAs in different comparisons (DSS vs. NC and AOM/DSS vs. DSS). The bioinformatics analyses were used to search the common characteristics in mouse colitis and CAC.

RESULTS

The K-means clustering algorithm packaged these differential expressed circRNAs into subgroup analysis, and the data strongly implied that mmu_circ_0001109 closely correlated to the pro-inflammatory signals, while mmu_circ_0001845 was significantly associated with the Wnt signalling pathway. Our subsequent data in vivo and in vitro confirmed that mmu_circ_0001109 could exacerbate the colitis by up-regulating the Jak-STAT3 and NF-kappa B signalling pathways, and mmu_circ_0001845 promoted the CAC transformation through the Wnt signalling pathway. By RNA blasting between mice and humans, the human RTEL1- and PRKAR2A-derived circRNAs, which might be considered as homeotic circRNAs of mmu_circ_0001109 and mmu_circ_0001845, respectively, were identified. The clinical data revealed that RTEL1-derived circRNAs had no clinical significance in human IBD and CAC. However, three PRKAR2A-derived circRNAs, which had the high RNA similarities to mmu_circ_0001845, were remarkably up-regulated in CAC tissue samples and promoted the transition from colitis to CAC.

CONCLUSIONS

Our results suggested that these human PRKAR2A-derived circRNAs could be novel candidates for distinguishing CAC patients and predicted the prognosis of CAC.

Anti-inflammatory actions of acetate, propionate, and butyrate in fetal mouse jejunum cultures ex vivo and immature small intestinal cells in vitro

Necrotizing enterocolitis (NEC) is an intestinal disease that frequently occurs in premature infants. Presently, there is no effective therapy for NEC. Therefore, the key to reduce the incidence rate of NEC is to take effective intervention measures as early as possible. Short-chain fatty acids (SCFAs) (acetate, propionate, and butyrate), the principal terminal products of enterobacteria fermentation, play anti-inflammatory actions in mature intestinal cells. However, few studies focus on their roles in immature intestine. Here, we evaluated the anti-inflammatory actions of SCFAs ex vivo with ICR fetal mouse jejunum cultures and explored the potential anti-inflammatory regulators through RNA-seq and then verified them in vitro with human fetal small intestinal epithelial FHs 74 Int cells. In this study, we found that acetate, propionate, and butyrate decreased IL-1β-induced production of CXCL2 ex vivo and IL-8 and IL-6 in vitro significantly (p < .05). Furthermore, the inhibitors of NF-κB p65, JNK1/2, and ERK1/2 pathways, which were selected from RNA-seq and depressed by SCFAs, also significantly decreased IL-8 and IL-6 productions induced by IL-1β (p < .05). Therefore, our results showed that acetate, propionate, and butyrate ameliorated the fetal small intestine inflammatory response induced by IL-1β through inhibiting ERK1/2 pathway; NF-κB p65, JNK1/2, and ERK1/2 pathways; or NF-κB p65 and ERK1/2 pathways, respectively. These findings suggested that SCFAs may be a new therapy agent for NEC.

The Toxic Mechanism of Gliotoxins and Biosynthetic Strategies for Toxicity Prevention

Gliotoxin is a kind of epipolythiodioxopiperazine derived from different fungi that is characterized by a disulfide bridge. Gliotoxins can be biosynthesized by a gli gene cluster and regulated by a positive GliZ regulator. Gliotoxins show cytotoxic effects via the suppression the function of macrophage immune function, inflammation, antiangiogenesis, DNA damage by ROS production, peroxide damage by the inhibition of various enzymes, and apoptosis through different signal pathways. In the other hand, gliotoxins can also be beneficial with different doses. Low doses of gliotoxin can be used as an antioxidant, in the diagnosis and treatment of HIV, and as an anti-tumor agent in the future. Gliotoxins have also been used in the control of plant pathogens, including Pythium ultimum and Sclerotinia sclerotiorum. Thus, it is important to elucidate the toxic mechanism of gliotoxins. The toxic mechanism of gliotoxins and biosynthetic strategies to reduce the toxicity of gliotoxins and their producing strains are summarized in this review.

Sulfated polysaccharides from pacific abalone attenuated DSS-induced acute and chronic ulcerative colitis in mice via regulating intestinal micro-ecology and the NF-κB pathway

Due to potential side effects of current drugs in colitis treatment, polysaccharides with anti-inflammatory activities can be considered as alternative molecules for colitis treatment. Sulfated polysaccharide from pacific abalone (AGSP) reduced the level of lipopolysaccharides (LPS) and increased the production of short chain fatty acids in the colon of mice, and it reduced the levels of interleukin (IL)-6, IL-1β and tumor necrosis factor (TNF)-α and increased the IL-10 level in in vitro cell models, suggesting that it can be used as a probiotic agent to inhibit intestinal inflammation. Furthermore, AGSP reduced the disease activity index and intestinal damage, improved the mucosal immune response, and inhibited oxidative damage in mice with DSS-induced acute and chronic colitis, which can be associated with modulation of the NF-κB signaling pathway and gut microbiota. AGSP regulated the structure of the gut microbiota and reduced the level of Bacteroides that had positive correlation with the colitis symptoms. The in vitro result showed that AGSP may inhibit mucin degradation by Bacteroides via the change of the polysaccharide utilization strategy, which can protect intestinal barrier integrity. This study is useful to understand the mechanism by which AGSP ameliorates colitis and related diseases and promotes further development of AGSP.

Anti-Inflammatory Effects of Heritiera littoralis Fruits on Dextran Sulfate Sodium- (DSS-) Induced Ulcerative Colitis in Mice by Regulating Gut Microbiota and Suppressing NF-κB Pathway

Materials and Methods

The chemical compositions of EFH were identified using LC-ESI-MS. The mice with 3% DSS-induced UC were administered EFH (200, 400, and 800 mg/kg), sulfasalazine (SASP, 200 mg/kg), and azathioprine (AZA, 13 mg/kg) for 10 days via daily gavage. The colonic inflammation was evaluated by the disease activity index (DAI), colonic length, histological scores, and levels of inflammatory mediators. The gut microbiota was characterized by 16S rRNA gene sequencing and analysis.

Results

LC-ESI-MS analysis showed that EFH was rich in alkaloids and flavones. The results indicated that EFH significantly improved the DAI score, relieved colon shortening, and repaired pathological colonic variations in colitis. In addition, proteins in the NF-κB pathway were significantly inhibited by EFH. Furthermore, EFH recovered the diversity and balance of the gut microbiota.

Conclusions

EFH has protective effects against DSS-induced colitis by keeping the balance of the gut microbiota and suppressing the NF-κB pathway.

Therapeutic potential of sulfur-containing natural products in inflammatory diseases

Owing to the prevalence of chronic inflammation and its related disorders, there is a demand for novel therapeutic agents capable of preventing or suppressing inflammation. Natural products (NPs) are well established as an important resource for drug development and provide an almost infinite array of molecular entities. Sulfur-containing NPs (i.e., NPs containing one or more sulfur atoms) are abundant throughout nature, from bacteria to animals. The aim of this review was to survey the emerging evidence on role of sulfur-containing NPs, such as glutathione, garlic-derived sulfur compounds, Epipolythiodioxopiperazines (EPTs), Isothiocyanates (ITCs), and Ergothioneine (EGT), in the control of inflammation and to determine the possible underlying mechanisms. A discussion of how hydrogen sulfide (H₂S), an endogenous gaseous signaling molecule, links sulfur-containing NPs and their anti-inflammatory action is also performed. This review may help to further the development of sulfur-based compounds by providing a guide for structure-activity relationship-based modification for use in modern medicinal chemistry. However, as this field is still in its infancy, the review is concluded by an overview of the progression of these promising entities as therapeutic agents.

Albumin Nano-Encapsulation of Piceatannol Enhances Its Anticancer Potential in Colon Cancer Via Downregulation of Nuclear p65 and HIF-1α

Piceatannol (PIC) is known to have anticancer activity, which has been attributed to its ability to block the proliferation of cancer cells via suppression of the NF-kB signaling pathway. However, its effect on hypoxia-inducible factor (HIF) is not well known in cancer. In this study, PIC was loaded into bovine serum albumin (BSA) by desolvation method as PIC–BSA nanoparticles (NPs). These PIC–BSA nanoparticles were assessed for in vitro cytotoxicity, migration, invasion, and colony formation studies and levels of p65 and HIF-1α. Our results indicate that PIC–BSA NPs were more effective in downregulating the expression of nuclear p65 and HIF-1α in colon cancer cells as compared to free PIC. We also observed a significant reduction in inflammation induced by chemical colitis in mice by PIC–BSA NPs. Furthermore, a significant reduction in tumor size and number of colon tumors was also observed in the murine model of colitis-associated colorectal cancer, when treated with PIC–BSA NPs as compared to free PIC. The overall results indicate that PIC, when formulated as PIC–BSA NPs, enhances its therapeutic potential. Our work could prompt further research in using natural anticancer agents as nanoparticels with possible human clinical trails. This could lead to the development of a new line of safe and effective therapeutics for cancer patients.

Intracellular Delivery of Biologically-Active Fungal Metabolite Gliotoxin Using Magnetic Nanoparticles

Gliotoxin (GT), a secondary metabolite produced by Aspergillus molds, has been proposed as a potential anti-tumor agent. Here we have developed a nanoparticle approach to enhance delivery of GT in tumor cells and establish a basis for its potential use as therapeutical drug. GT bound to magnetic nanoparticles (MNPs) retained a high anti-tumor activity, correlating with efficient intracellular delivery, which was increased in the presence of glucose. Our results show that the attachment of GT to MNPs by covalent bonding enhances intracellular GT delivery without affecting its biological activity. This finding represents the first step to use this potent anti-tumor agent in the treatment of cancer.

A20 ameliorates inflammatory bowel disease in mice via inhibiting NF-κB and STAT3 activation

A20 is a zinc finger protein that effectively inhibits the activation of nuclear factor (NF)-κB to downregulate the expression of tumor necrosis factor-α, interleukin (IL)-1β, and IL-17. A20 also plays a crucial role as a feedback inhibitor of the inflammatory response. Due to its inhibitory role, A20 may be useful in regulating diseases resulting from chronic inflammation and excessive pro-inflammatory cytokine production, such as colitis. Patients with colitis produce high levels of pro-inflammatory cytokines in the intestine. Therefore, this study aimed to investigate whether A20 improves experimental colitis by reducing high levels of inflammation in the intestine. An A20 overexpression vector was administered to mice by intrarectal injection after colitis induction. Histological analysis by immunohistochemistry was used to score sections of the intestine. Confocal laser scanning microscopy was used to identify the expression of IL-17 and forkhead box p (FOXP) 3 protein in spleen tissues. Protein expression induced by STAT3 and NF-κB signaling was analyzed by western blot. We found that A20 reduced the colitis activity index score and the histological score of the intestine. A20 also decreased inflammatory cytokine levels in the intestine and increased colon length. Additionally, A20 overexpression downregulated the activation of NF-kB and STAT3. A20 also reduced IL-17 expression in CD4⁺ T cells from spleen sections. In contrast, A20 overexpression enhanced the expression of FOXP3 in CD4⁺ T cells. These results suggest that A20 may inhibit the progression of colitis by decreasing inflammation via inhibition of NF-κB, phosphorylated STAT3, and IL-17.

α-Mangostin ameliorates dextran sulfate sodium-induced colitis through inhibition of NF-κB and MAPK pathways

Ulcerative colitis (UC) is a chronic inflammatory bowel disease (IBD) of the colon as a target site. Previous reports regarding the efficacy of α-mangostin (αMG) to inhibit nuclear factor-kappa B (NF-κB) and mitogen-activated protein kinases (MAPKs) as well as relatively high distribution to the colon suggested the therapeutic potential of this compound in UC model. In dextran sodium sulfate (DSS)-induced colitis mice (DSS mice), the disease activity index scores involving diarrhea, bloody stool, body weight reduction, and myeloperoxidase (MPO) activities of the esophagus and colon increased with the reduced colon length. Also histologic disturbances and changes of NF-κB and MAPK pathways including phosphorylation of IκB kinase, ERK1/2, SAPK/JNK and p38 were observed in the colon of the DSS mice. However, all of these impaired conditions in the DSS mice were restored by αMG treatment, and the intestinal metabolism of αMG decreased, increasing its distribution to the colons in the DSS mice compared with the control mice. All of these results suggest that high distribution of αMG in the colon might attenuate DSS-induced colitis by inhibiting NF-κB and MAPK pathways in the colon.

Molecular pathways driving disease-specific alterations of intestinal epithelial cells

Due to the fact that chronic inflammation as well as tumorigenesis in the gut is crucially impacted by the fate of intestinal epithelial cells, our article provides a comprehensive overview of the composition, function, regulation and homeostasis of the gut epithelium. In particular, we focus on those aspects which were found to be altered in the context of inflammatory bowel diseases or colorectal cancer and also discuss potential molecular targets for a disease-specific therapeutic intervention.

Astragalus polysaccharides protect against dextran sulfate sodium-induced colitis by inhibiting NF-κВ activation

Astragalus polysaccharide (APS) is a bioactive extract of Astragalus membranaceus (AM), which possess a wide range of medicinal benefits, including anti-inflammatory, anti-oxidative, anti-tumor and anti-diabetic effects. The present work evaluated the therapeutic effect of APS and its potential mechanisms in a mouse model of dextran sulfate sodium (DSS)-induced colitis. The APS treatment led to significant improvements in colitis disease activity index (DAI) and histological scores, as well as significantly increased weight and colon length in mice as compared to the control group. Mechanically, reduced NF-κВ DNA phosphorylation activity and downregulated TNF-α, IL-1β, IL-6, IL-17 expressions and myeloperoxidase (MPO) activity were associated with improvement in colitis observed in APS-treated mice. These findings suggest that APS may represent a natural therapeutic approach for treating inflammatory bowel disease, such as ulcerative colitis.

Resistance is not futile: gliotoxin biosynthesis, functionality and utility

Gliotoxin biosynthesis is encoded by the gli gene cluster in Aspergillus fumigatus. The biosynthesis of gliotoxin is influenced by a suite of transcriptionally-active regulatory proteins and a bis-thiomethyltransferase. A self-protection system against gliotoxin is present in A. fumigatus. Several additional metabolites are also produced via the gliotoxin biosynthetic pathway. Moreover, the biosynthesis of unrelated natural products appears to be influenced either by gliotoxin or by the activity of specific reactions within the biosynthetic pathway. The activity of gliotoxin against animal cells and fungi, often mediated by interference with redox homeostasis or protein modification, is revealing new metabolic interactions within eukaryotic systems. Nature has provided a most useful natural product with which to reveal some of its many molecular secrets.

Hydrolysate from eggshell membrane ameliorates intestinal inflammation in mice

Inflammatory bowel diseases (IBD) comprises of ulcerative colitis (UC) and Cohn’s disease (CD) as two main idiopathic pathologies resulting in immunologically mediated chronic inflammatory conditions. Several bioactive peptides and hydro lysates from natural sources have now been tested in animal models of human diseases for potential anti-inflammatory effects. Eggshell membrane (ESM) is a well-known natural bioactive material. In this study, we aim to study the anti-inflammatory activity of ESM hydro lysate (AL-PS) in vitro and in vivo. In vitro, AL-PS was shown to inhibit pro-inflammatory cytokine IL-8 secretion. In vivo treatment with AL-PS was shown to reduce dextran sodium sulphate (DSS)-induced weight loss, clinical signs of colitis and secretion of interleukin (IL)-6 (p < 0.05). In addition, treatment with AL-PS also attenuated the severity of intestinal inflammation via down-regulation of IL-10 an anti-inflammatory cytokine. This validates potential benefits of AL-PS as a novel preventative target molecule for treatment of IBD.

MC-12, an annexin A1-based peptide, is effective in the treatment of experimental colitis

Annexin A1 (ANXA1) inhibits NF-κB, a key regulator of inflammation, the common pathophysiological mechanism of inflammatory bowel diseases (IBD). MC-12, an ANXA1-based tripeptide, suppresses NF-κB activation. Here, we determined the efficacy of MC-12 in the control of IBD. Mice with colitis induced by dextran sodium sulfate (DSS) or 2,4,6-trinitro benzene sulfonic acid (TNBS) were treated with various doses of MC-12 administered intraperitoneally, orally or intrarectally. We determined colon length and the histological score of colitis, and assayed: in colon tissue the levels of TNF-α, IFN-γ, IL-1β, IL-6 and IL-10 by RT-PCR; prostaglandin E₂ (PGE₂), cytoplasmic phospholipase A₂ (cPLA₂) and myeloperoxidase by immunoassay; and COX-2 and NF- κB by immunohistochemistry; and in serum the levels of various cytokines by immunoassay. In both models MC-12: reversed dose-dependently colonic inflammation; inhibited by up to 47% myeloperoxidase activity; had a minimal effect on cytoplasmic phospholipase A₂; reduced significantly the induced levels of TNF-α, IFN-γ, IL-1β, IL-6 and IL-10, returning them to baseline. DSS and TNBS markedly activated NF-κB in colonic epithelial cells and MC-12 decreased this effect by 85.8% and 72.5%, respectively. MC-12 had a similar effect in cultured NCM460 normal colon epithelial cells. Finally, MC-12 suppressed the induction of COX-2 expression, the level of PGE₂ in the colon and PGE₂ metabolite in serum. In conclusion, MC-12, representing a novel class of short peptide inhibitors of NF-κB, has a strong effect against colitis in two preclinical models recapitulating features of human IBD. Its mechanism of action is complex and includes pronounced inhibition of NF-κB. MC-12 merits further development as an agent for the control of IBD.

Immune modulatory effects of the foodborne contaminant citrinin in mice

The mycotoxin citrinin can cause mycotoxic nephropathy, cytotoxicity and genotoxicity. To investigate the immune modulatory effects, CTN was orally administered to female BALB/c mice at the dose of 1, 5, or 10 mg/kg body weight for 14 days, and several immunotoxicity tests were performed. The populations of F4/80+ cells and CD19+ cells were significantly decreased in spleen and MLN. In MLN, CD4+, CD8+, and CD4+CD25+Foxp3+ cell populations were increased. CD8+ cells were increased but CD19+ cells were decreased in intra-epithelial, lamina propria and Peyer's patches lymphocytes. In a cell proliferation assay, along with the increased proliferative capacities of ConA-induced splenocytes and MLN cells, IFN-γ production was increased. The expression of TLR 2 was increased in spleen, but TLR 3 expression in MLN was decreased. The level of serum IgM was reduced. Furthermore, apoptosis was induced in spleen, MLN and Peyer's patches and promoted by the change in the ratio of Bax/Bcl-2 activities. Autophagy gene Atg5 and Beclin-1 were up-regulated in spleen. The expressions of IL-1β, IL-10, and TNF-α were inhibited in murine macrophage cells pre-exposed with TLR ligands. These results indicate that CTN has multiple immune modulatory effects in mice that may alter normal functions of immune system.

Augmented activity of the pelvic nerve afferent mediated by TRP channels in dextran sulfate sodium (DSS)-induced colitis of rats

Enteritis has been recognized as a major symptom in domestic animals and human patients suffering from feed and food poisonings. The aim of the present study was to clarify the excitatory mechanism of the pelvic nerve afferent which may influence the occurrence of enteritis in response to nociceptive chemical stimuli of the colon in normal and abnormal rats with colitis induced by dextran sulfate sodium (DSS). The pelvic nerve afferent activity was markedly increased by colonic instillation of solution (0.5 ml) of acetic acid (5-25%) and capsaicin (100 μg/ml). The nerve activity was augmented by colonic instillation of capsaicin to a greater extent in rats with DSS-induced colitis than in normal control rats. This augmented activity by capsaicin was more prominent at one day (DSS-1) than at 8 day (DSS-8) after the administration of DSS. The increased nerve activity caused by capsaicin in DSS-1 and DSS-8 was significantly inhibited by pretreatment with ruthenium red, which is a nonselective inhibitor of TRP channels of unmyelinated C-fibers (nociceptors). In conclusion, it was elucidated that the nociceptive function of the pelvic nerve was largely elevated at one day after DSS-induced colitis and such increased function was mostly mediated by TRP channels.

Differential patterns of histone acetylation in inflammatory bowel diseases

Post-translational modifications of histones, particularly acetylation, are associated with the regulation of inflammatory gene expression. We used two animal models of inflammation of the bowel and biopsy samples from patients with Crohn's disease (CD) to study the expression of acetylated histones (H) 3 and 4 in inflamed mucosa. Acetylation of histone H4 was significantly elevated in the inflamed mucosa in the trinitrobenzene sulfonic acid model of colitis particularly on lysine residues (K) 8 and 12 in contrast to non-inflamed tissue. In addition, acetylated H4 was localised to inflamed tissue and to Peyer's patches (PP) in dextran sulfate sodium (DSS)-treated rat models. Within the PP, H3 acetylation was detected in the mantle zone whereas H4 acetylation was seen in both the periphery and the germinal centre. Finally, acetylation of H4 was significantly upregulated in inflamed biopsies and PP from patients with CD. Enhanced acetylation of H4K5 and K16 was seen in the PP. These results demonstrate that histone acetylation is associated with inflammation and may provide a novel therapeutic target for mucosal inflammation.

Neuro-endocrine-immune network and inflammatory bowel disease

Inflammatory bowel disease (IBD) is a group of chronic inflammatory gastrointestinal diseases of unknown etiology, including mainly ulcerative colitis (UC) and Crohn's disease (CD). Numerous studies have indicated that there is considerable relationship between the pathogenesis of IBD and the neuro-endocrine-immune network. This article will describe the essential role of the neuro-immune-endocrine network in the development of IBD in terms of the hypothalamus-autonomic nervous system (HANS) axis, hypothalamic-pituitary-adrenal (HPA) axis and immunity.

Exposure to mycotoxins increases the allergic immune response in a murine asthma model

RATIONALE

Epidemiological studies have shown that indoor molds are associated with increased prevalence and exacerbation of respiratory symptoms and asthma. Mycotoxins, secondary metabolites of molds, may contribute to these effects.

OBJECTIVES

To investigate the adjuvant activity of mycotoxins on allergic airway inflammation.

METHODS

Balb/c mice were exposed via the airways to gliotoxin and via the intestine to patulin, sensitized with ovalbumin (OVA), and then analyzed in acute and chronic murine asthma models. In addition, the effect of mycotoxin exposure on dendritic cell (DC) function was investigated using murine bone marrow-derived DCs.

MEASUREMENTS AND MAIN RESULTS

Exposure of mice to both mycotoxins enhanced dose-dependently airway hyperreactivity, eosinophilic lung inflammation, and OVA-specific IgE serum levels compared with mice that received only the antigen. These findings correlated with increased Th2 cytokine levels and decreased IFN-gamma production. Long-term mycotoxin exposure exacerbated chronic airway inflammation and airway remodeling. In vitro or in vivo mycotoxin exposure inhibited IL-12 production in maturing DCs and enhanced airway inflammation after adoptive DC transfer into Balb/c mice. Mycotoxin exposure enhanced OVA-induced lung lipid peroxidation and moderately increased isoprostane levels in naive mice. Treatment of mycotoxin-exposed DCs with the antioxidants N-acetylcysteine or glutathione ethyl ester restored IL-12 secretion and pretreatment of exposed mice with N-acetylcysteine prevented the mycotoxin-induced increase of airway inflammation and AHR.

CONCLUSIONS

Our results demonstrate that gliotoxin and patulin increase the allergic immune response in mice by modulating the Th1/Th2 balance via direct effects on IL-12 secretion in DCs and by inducing oxidative stress.

Attenuation of experimental murine colitis by acanthoic acid from Acanthopanax koreanum

Acanthoic acid (AA) is a pimaradiene diterpene isolated from Acanthopanax koreanum. We examined the effect of AA in dextran sulfate sodium (DSS)-induced colitis. AA (100 mg/kg or 300 mg/kg) was administered p.o. daily for 7 days. AA significantly inhibited Disease Activity Index, histological score, and myeloperoxidase activity. Furthermore, AA markedly suppressed the protein expression of TNF-alpha, COX-2, NF-kappaB and chymase as well as the mRNA expression of TNF-alpha and COX-2. These results suggest that AA exerts beneficial effects in experimental colitis, and therefore we propose that this compound may have therapeutic implications for ulcerative colitis.

Tumor suppressor FOXO3 participates in the regulation of intestinal inflammation

Inflammatory bowel disease (IBD), including Crohn's disease and ulcerative colitis, is characterized by chronic mucosal injury and the infiltration of inflammatory cells. Tumor suppressor FOXO3 regulates gene expression and its translocation to the cytosol leads to the abrogation of its transcriptional function. We have previously shown that bacterial infection regulates FOXO3 in intestinal epithelial cells and increases cytokine levels. As TNFalpha is a major contributor in intestinal inflammation, the aim of this study was to assess its effect on FOXO3 and FOXO3's contribution to intestinal inflammation in vitro and in vivo. TNFalpha induces the translocation of nuclear FOXO3 into the cytosol where it undergoes proteasomal degradation in human intestinal HT-29 cells. Proximally, the PI3K and IKK pathways mediate TNFalpha-induced FOXO3 phosphorylation. In FOXO3-silenced HT-29 cells, TNFalpha-induced IL-8 expression is increased approximately 83%. In vivo, Foxo3 is present in the nuclei and cytosol of colonic crypt epithelia. In DSS-induced colonic inflammation, Foxo3's nuclear localization is lost and it is only found in the cytosol. Consistent with a role for Foxo3 in colitis, Foxo3-deficient mice treated with DSS developed more severe colonic inflammation with an increased number of intraepithelial lymphocytes and PMNs infiltrated in the epithelia, than wild-type mice. In summary, TNFalpha inactivates FOXO3 in intestinal epithelia through the PI3K and IKK pathways and FOXO3 inactivation leads to the upregulation of IL-8 in vitro; in vivo Foxo3 is in the cytosol of inflamed colonic epithelia and Foxo3 deficiency leads to severe intestinal inflammation.

ROS, Hsp27, and IKKbeta mediate dextran sodium sulfate (DSS) activation of IkappaBa, NFkappaB, and IL-8

BACKGROUND

Dextran sodium sulfate (DSS) is a sulfated polysaccharide that has been very widely used to induce inflammation in experimental models of inflammatory bowel disease in which the effects of pharmacologic and biologic therapies are tested. However, the precise mechanisms by which DSS induces inflammation have not been elucidated.

METHODS

DSS-induced increases in phospho-IkappaBalpha, nuclear NFkappaB (p65), and IL-8 secretion in human colonic epithelial cells in tissue culture are attributable to a reactive oxygen species (ROS)-induced pathway of inflammation, and do not require TLR4, MyD88, or Bcl10, which are associated with the innate immune pathway of NFkappaB-IL-8 activation.

RESULTS

DSS-induced increases were inhibited by the ROS scavengers Tempol and Tiron, were associated with decreased phosphorylation of MAPK12 (p38gamma), MAPK 13 (p38delta), and Hsp27, and required the IkappaB kinase (IKK) signalosome component IKKbeta. In ex vivo colonic tissue from TLR4-deficient mice, or following knockdown of MyD88 or Bcl10 or exposure to an IRAK 1/4 inhibitor, DSS effects were not suppressed. Data demonstrated that DSS activates IkappaBalpha, NFkappaB, and IL-8 through an ROS-Hsp27-IKKbeta-mediated pathway, and not through an innate immune cascade.

CONCLUSIONS

These results suggest that DSS models of inflammation may not be optimal for evaluation of interventions that involve mechanisms of innate immunity.

Therapeutic effect of lecithinized superoxide dismutase against colitis

Ulcerative colitis (UC) involves intestinal mucosal damage induced by reactive oxygen species (ROS), in particular, superoxide anion. Superoxide dismutase (SOD) catalyzes dismutation of superoxide anion to hydrogen peroxide, which is subsequently detoxified by catalase. Lecithinized SOD (PC-SOD) is a new modified form of SOD that has overcome previous clinical limitations of SOD. In this study, we examined the action of PC-SOD using an animal model of UC, dextran sulfate sodium (DSS)-induced colitis. DSS-induced colitis was ameliorated by daily intravenous administration of PC-SOD. Unmodified SOD produced a similar effect but only at more than 30 times the concentration of PC-SOD. In vivo electron spin resonance analysis confirmed that the increase in the colonic level of ROS associated with development of colitis was suppressed by PC-SOD administration. The dose-response profile of PC-SOD was bell-shaped, but simultaneous administration of catalase restored the ameliorative effect at high doses of PC-SOD. Accumulation of hydrogen peroxide was observed with the administration of high doses of PC-SOD, an effect that was suppressed by the simultaneous administration of catalase. We also found that either a weekly intravenous administration or daily oral administration of PC-SOD conferred protection. These results suggest that PC-SOD achieves its ameliorative effect against colitis through decreasing the colonic level of ROS and that its ineffectiveness at higher doses is because of the accumulation of hydrogen peroxide. Furthermore, we consider that intermittent or oral administration of PC-SOD can be applied clinically to improve the quality of life of UC patients.

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.

Lactobacillus casei prevents the development of dextran sulphate sodium-induced colitis in Toll-like receptor 4 mutant mice

Probiotics, defined as live or attenuated bacteria or bacterial products, confer a significant health benefit to the host. Recently, they have been shown to be useful in the treatment of chronic inflammatory bowel disease and infectious colitis. In this study, we investigated the effect of probiotics on the development of experimental colitis using Toll-like receptor 4 (TLR-4) mutant (lps-/lps-) mice. TLR-4(lps-/lps-) and wild-type (WT) mice were given 2.5% dextran sulphate sodium (DSS) in drinking water to induce colitis with or without Lactobacillus casei pretreatment. Clinical and histological activity of DSS-colitis was attenuated markedly both in TLR-4(lps-/lps-) and WT mice pretreated with L. casei. Interestingly, histological activity was less severe in TLR-4(lps-/lps-) mice than in WT mice. The levels of myeloperoxidase activity and interleukin (IL)-12p40 were attenuated in pretreated TLR-4(lps-/lps-) mice after DSS administration. By contrast, transforming growth factor (TGF)-beta and IL-10 mRNA and protein expressions were increased markedly in pretreated TLR-4(lps-/lps-) mice. The current results suggest that L. casei has a preventive effect in the development of acute DSS-induced colitis and its action depends largely upon TLR-4 status. L. casei modulates the expression of inflammatory cytokines and down-regulates neutrophilic infiltration in the case of incomplete TLR-4 complex signalling.

Anti-inflammatory effects of Lactobacillus casei BL23 producing or not a manganese-dependant catalase on DSS-induced colitis in mice

Background

Human immune cells generate large amounts of reactive oxygen species (ROS) throughout the respiratory burst that occurs during inflammation. In inflammatory bowel diseases, a sustained and abnormal activation of the immune system results in oxidative stress in the digestive tract and in a loss of intestinal homeostasis. We previously showed that the heterologous production of the Lactobacillus plantarum ATCC14431 manganese-dependant catalase (MnKat) in Lb. casei BL23 successfully enhances its survival when exposed to oxidative stress. In this study, we evaluated the preventive effects of this antioxidative Lb. casei strain in a murine model of dextran sodium sulfate (DSS)-induced moderate colitis.

Results

Either Lb. casei BL23 MnKat^- or MnKat⁺ was administered daily to mice treated with DSS for 10 days. In contrast to control mice treated with PBS for which DSS induced bleeding diarrhea and mucosal lesions, mice treated with both Lb. casei strains presented a significant (p < 0.05) reduction of caecal and colonic inflammatory scores.

Conclusion

No contribution of MnKat to the protective effect from epithelial damage has been observed in the tested conditions. In contrast, these results confirm the high interest of Lb. casei as an anti-inflammatory probiotic strain.

The angiogenic switch molecule, secreted FGF-binding protein, an indicator of early stages of pancreatic and colorectal adenocarcinoma

Tumor angiogenesis has been related to the initiation as well as progression toward more aggressive behavior of human tumors. We will discuss genetic events underlying the initiation and progression of colorectal and pancreatic adenocarcinoma with a particular focus on the modulation of angiogenesis. A secreted fibroblast growth factor (FGF) binding protein (FGF-BP), which is an extracellular chaperone molecule for FGFs, has been shown to enhance FGF-mediated biochemical and biologic events and to be a crucial rate-limiting factor for tumor-dependent angiogenesis. Histochemical and in situ hybridization studies with archival samples show that FGF-BP is induced early during the initiation of colorectal and pancreatic adenocarcinoma. We will discuss the potential of this secreted protein as a serum marker to identify at-risk subjects.

Inhibition of lipopolysaccharide-induced release of interleukin-8 from intestinal epithelial cells by SMA, a novel inhibitor of sphingomyelinase and its therapeutic effect on dextran sulphate sodium-induced colitis in mice

Lipopolysaccharide (LPS) and inflammatory cytokines cause activation of sphingomyelinases (SMases) and subsequent hydrolysis of sphingomyelin (SM) to produce a lipid messenger ceramide. The use of SMase inhibitors may offer new therapies for the treatment of the LPS- and cytokines-related inflammatory bowel disease (IBD). We synthesized a series of difluoromethylene analogues of SM (SMAs). Here, we show that LPS efficiently increases the release of IL-8 from HT-29 intestinal epithelial cells by activating both neutral SMase and nuclear factor (NF)-kappaB in the cells. The addition of SMA-7 suppressed neutral SMase-catalyzed ceramide production, NF-kappaB activation, and IL-8 release from HT-29 cells caused by LPS. The results suggest that activation of neutral SMase is an underlying mechanism of LPS-induced release of IL-8 from the intestinal epithelial cells. Ceramide production following LPS-induced SM hydrolysis may trigger the activation of NF-kappaB in nuclei. Oral administration of SMA-7 (60 mg/kg) to mice with 2% dextran sulfate sodium (DSS) in their drinking water, for 21 consecutive days, reduced significantly the severity of colonic injury. This finding suggests a central role for SMase/ceramide signaling in the pathology of DSS-induced colitis in mice. The therapeutic effect of SMA-7 observed in mice may involve the suppression of IL-8 production from intestinal epithelial cells by LPS or other inflammatory cytokines.

Acid sphingomyelinase inhibition suppresses lipopolysaccharide-mediated release of inflammatory cytokines from macrophages and protects against disease pathology in dextran sulphate sodium-induced colitis in mice

Lipopolysaccharide (LPS) and inflammatory cytokines cause activation of sphingomyelinases (SMases) and subsequent hydrolysis of sphingomyelin (SM) to produce a lipid messenger ceramide. The design of SMase inhibitors may offer new therapies for the treatment of LPS- and cytokine-related inflammatory bowel disease. We synthesized a series of difluoromethylene analogues of SM (SMAs). We report here the effects of the most potent SMase inhibitor, SMA-7, on the LPS-mediated release of tumour necrosis factor-alpha, interleukin-1beta and interleukin-6 from THP-1 macrophages and the pathology of dextran sulphate sodium (DSS)-induced colitis in mice. SMA-7 suppressed the LPS-induced cytokine release and nuclear factor-kappaB activation. LPS stimulation caused a four-fold increase in acid SMase activation, but little increase in neutral SMase activity. The presence of 10 microm SMA-7 caused acid SMase to remain at the control levels and reduced the formation of ceramide. HT-29 cells had significantly decreased cell viability when incubated with media from LPS-stimulated THP-1 macrophages. However, incubating the colon cells in media from both SMA-7 and LPS-treated macrophages caused little decrease in viability, suggesting that ceramide has a role in the LPS-stimulated signalling that releases cytotoxic factors against colon cells. Oral administration of SMA-7 to mice with 2% DSS in the drinking water, for 10 or 21 consecutive days, reduced significantly the cytokine levels in the colon and the severity of colonic injury. These findings suggest a central role for acid SMase/ceramide signalling in the pathology of DSS-induced colitis in mice, indicating a possible preventive or therapeutic role for SMase inhibitor in inflammatory bowel disease.

Reduced severity of a mouse colitis model with angiotensin converting enzyme inhibition

Ulcerative colitis is characterized by elevated rates of epithelial cell apoptosis, and an up-regulation of pro-apoptotic cytokines including tumor necrosis factor alpha (TNF-alpha). Recently, angiotensin converting enzyme (ACE) has been shown to promote apoptosis. In addition, pharmacologic ACE inhibition (ACE-I) both prevents apoptosis and reduces TNF-alpha expression in vitro. We hypothesized that ACE-I, using enalaprilat, would decrease colonic epithelial cell apoptosis and reduce colitis severity in the dextran sulfate sodium (DSS)-induced colitis model in mice. We assessed the severity of colitis, and colonic epithelial cell apoptosis, after administration of DSS. Mice were given either daily ACE-I treatment or daily placebo. ACE-I treatment markedly improved clinical outcomes. In addition, ACE-I treatment significantly reduced the maximum histopathologic colitis grade. ACE-I also dramatically reduced the epithelial apoptotic rate. To investigate the mechanism by which ACE-I reduced apoptosis; we measured TNF-alpha, Bcl-2, and Bax expression. TNF-alpha mRNA was significantly lower with ACE-I treatment compared to placebo at every time point, as was the ratio of Bax to Bcl-2. We conclude that ACE-I reduces the severity of DSS-induced colitis and reduces epithelial cell apoptosis.

Tumor angiogenesis: initiation and targeting - therapeutic targeting of an FGF-binding protein, an angiogenic switch molecule, and indicator of early stages of gastrointestinal adenocarcinomas -

Tumor angiogenesis has been related to the initiation as well as progression toward more aggressive behavior of human tumors. In particular, the activity of angiogenic factors is crucial for tumor progression. We previously characterized a secreted fibroblast growth factor-binding protein (FGF-BP) as a chaperone molecule, which binds to various FGFs, enhances FGF-mediated biochemical and biologic events and importantly is a crucial rate-limiting factor for tumor-dependent angiogenesis. We generated monoclonal antibodies that target FGF-BP protein and used them as a tool to evaluate frequency and pattern of FGF-BP expression during the malignant progression of pancreas and colorectal carcinoma in archival tissue samples. We found that FGF-BP is dramatically upregulated during the initiation of colorectal and pancreatic adenocarcinoma. Crucial genetic events underlying the initiation and progression of colorectal and pancreatic adenocarcinoma with a particular focus on the modulation of angiogenesis and antiangiogenic therapies are discussed. We propose that the upregulation of the secreted FGF-BP protein during early phases of pancreas and colon cancer could make this protein a possible serum marker indicating the presence of high-risk premalignant lesions. Furthermore, the biological activity of FGF-BP is neutralized by monoclonal antibodies suggesting the potential for antibody-based therapeutic targeting.

Human thioredoxin-1 ameliorates experimental murine colitis in association with suppressed macrophage inhibitory factor production

BACKGROUND & AIMS

Thioredoxin-1 (TRX) is a small multifunctional protein with antioxidative and redox-regulating functions. In this study, we investigated the significance of TRX in patients with inflammatory bowel disease (IBD) and the ability and mechanism to ameliorate experimental colitis.

METHODS

Serum TRX and macrophage migration inhibitory factor (MIF) levels were measured in patients with IBD. The effects of TRX were evaluated in a dextran sulfate sodium (DSS)-induced colitis model by comparing TRX-overexpressing transgenic (TRX-TG) and control mice. We further evaluated the effect of recombinant human TRX (rhTRX) administration on DSS-induced colitis and colonic inflammation of interleukin (IL)-10 knockout (IL-10 KO) mice. Colonic inflammation was examined clinically and histologically. Proinflammatory cytokine levels were examined in colonic tissues, and MIF levels were measured in colonic tissues and sera in mice. The effect of TRX on MIF production was also analyzed in vitro.

RESULTS

Serum TRX and MIF levels were significantly higher in patients with IBD than normal controls, and TRX levels correlated with disease activity. TRX significantly ameliorated DSS-induced colitis and colonic inflammation of IL-10 KO mice. Increase of tumor necrosis factor-alpha and interferon-gamma in colonic tissues was significantly suppressed in TRX-TG mice compared with wild-type mice. MIF levels in colonic tissues and sera were significantly lower in TRX-TG mice than in wild-type mice, irrespective of DSS administration. Anti-TRX treatment exacerbated DSS-induced colitis. In vitro studies demonstrated that rhTRX suppressed MIF production in human monocyte cells.

CONCLUSIONS

TRX might have a potential as a novel therapeutic agent for the treatment of IBD.

Gliotoxin reduces the severity of trinitrobenzene sulfonic acid-induced colitis in mice: evidence of the connection between heme oxygenase-1 and the nuclear factor-kappaB pathway in vitro and in vivo

BACKGROUND

Gliotoxin, a fungal metabolite, has been known to show strong immunosuppressive properties, although its mechanisms are not completely understood. In this report, the authors investigated the mechanism whereby gliotoxin has anti-inflammatory properties in vitro and in trinitrobenzene sulfonic acid-induced colitis.

MATERIALS AND METHODS

Body weight, histological scores, and myeloperoxidase activity were evaluated in trinitrobenzene sulfonic acid colitis. Nuclear factor-kappaB (NF-kappaB) p65, tumor necrosis factor-alpha, interleukin (IL)-1beta, IL-12, and intercellular adhesion molecule-1 were detected by immunohistochemical staining. IL-8 secretion was measured by an enzyme-linked immunosorbent assay. Heme oxygenase-1 (HO-1) expression and I-kappaB degradation were analyzed by Western blot.

RESULTS

Pretreatment of human epithelial HT-29 cells with gliotoxin significantly blocked the I-kappaB degradation and NF-kappaB p65 nuclear translocation induced by tumor necrosis factor-alpha or IL-1beta; these were parallel with the inhibition of IL-8 secretion and intercellular adhesion molecule-1 expression in the same cells. Interestingly, gliotoxin induced HO-1 in HT-29 cells and, in turn, inhibition of HO-1 activity by a zinc protoporphyrin IX reversed the effects of gliotoxin in terms of I-kappaB degradation, intercellular adhesion molecule-1 expression, and IL-8 production. In trinitrobenzene sulfonic acid colitis, gliotoxin administration significantly improved the clinical and histopathological symptoms. Notably, gliotoxin also induced HO-1 in the colonic mucosa and zinc protoporphyrin IX reversed the protective effects of gliotoxin in trinitrobenzene sulfonic acid colitis.

CONCLUSIONS

These results demonstrate for the first time that the anti-inflammatory actions mediated by gliotoxin include HO-1 induction and the subsequent blockade of NF-kappaB-dependent signaling pathways in vitro and in vivo. The current results also demonstrate that gliotoxin may be an effective agent for the treatment of diseases characterized by mucosal inflammation.

Exacerbation of dextran sulfate sodium-induced colitis by dietary iron supplementation: role of NF-kappaB

BACKGROUND

In colitis, iron therapy may be given to treat anemia, but it may also be detrimental based on our previous studies using a rat model with colitis where iron supplementation increased disease activity and oxidative stress. This effect was partially reduced by an antioxidant.

AIMS

The aim of this study was to further evaluate, in rats with dextran sulfate sodium (DSS)-induced colitis, the effect of iron on neutrophilic infiltration, cytokines and nuclear factor kappa-B (NF-kappaB)-associated inflammation and to determine whether the addition of vitamin E would be beneficial.

METHODS

Colitis was induced with DSS at 50 g/l in drinking water for 7 days. DSS rats were randomized to the following: DSS, receiving a control, non-purified diet (iron, 270 mg and DL-alpha-tocopherol acetate, 49 mg/kg); DSS+iron (diet+iron, 3,000 mg/kg); DSS+vitamin E (diet+DL-alpha-tocopherol acetate, 2,000 mg/kg); or the DSS+iron+vitamin E. Colonic inflammation, myeloperoxidase activity (MPO), lipid peroxides (LPO), proinflammatory cytokines [tumor necrosis factor (TNF)-alpha, interleukin (IL)-1, IL-6] and NF-kappaB binding activity were measured.

RESULTS

The DSS+iron group showed a significant increase in inflammatory scores, MPO, TNF-alpha, IL-1, LPO and NF-kappaB activity compared to DSS or DSS+vitamin E. The addition of vitamin E to iron (DSS+iron+vitamin E group) significantly reduced the inflammatory scores, TNF-alpha and IL-6. None of the other parameters were affected.

CONCLUSION

Iron increases disease activity in colitis, and this is associated with oxidative stress, neutrophilic infiltration, increased cytokines and activation of NF-kappaB. This detrimental effect was partially reduced by vitamin E.

Gliotoxin-mediated suppression of innate and adaptive immune functions directed againstListeria monocytogenes

Gliotoxin is an immunosuppressive apoptogenic mycotoxin produced by a number of fungi including important human pathogens as Aspergillus fumigatus. In order to elucidate the potential role of gliotoxin as immunoevasive fungal virulence factor we studied the effects of gliotoxin on the innate and adaptive T cell-mediated immune response against the facultatively intracellular bacterium Listeria monocytogenes. Gliotoxin induced apoptosis of bone marrow-derived macrophages, dendritic cells and CD8 T cells in a dose- and cell type-dependent manner. In vitro the apoptogenic effect of gliotoxin correlated with a strong reduction of TNF-alpha and interleukin (IL)-12 production by dendritic cells and bone marrow-derived macrophages infected with L. monocytogenes and in the case of infected macrophages also in reduced NO-production and recognition by L. monocytogenes-specific CD8 T cells. Further gliotoxin pre-treatment of CD8 T cells reduced target cell lysis. In vivo, treatment of mice with gliotoxin increased the bacterial burden during the innate and the adaptive phase of primary L. monocytogenes infection. Taken together, these results demonstrate the suppressive effects of gliotoxin on the innate and also on the adaptive T cell-mediated antilisterial immunity.

Short-term treatment with anti-CD44v7 antibody, but not CD44v4, restores the gut mucosa in established chronic dextran sulphate sodium (DSS)-induced colitis in mice

Increased expression of CD44 variant isoforms have been shown on the inflammatory infiltrates in human and mouse colitis and blockade or deletion of CD44 isoforms inhibit experimental colitis. The objective of this study was to find out if short-term treatment of CD44 antibodies specific to CD44v7, but not to other variant isoforms, suppresses leucocyte-endothelial interaction in chronic dextran sodium sulphate (DSS)-induced colitis in mice. Chronic colitis was induced by oral administration of four cycles of 5% DSS in BALB/c mice. Expression of CD44 was investigated on isolated mononuclear cells of the gut immune system. In established colitis, mice were treated with antibodies against CD44v7 or CD44v4 three times in 7 days. Intravital microscopy was used to study leucocyte-endothelial interactions and leucocyte extravasation. As a marker of inflammatory infiltrates myeloperoxidase was quantified in gut tissue. CD44-induced apoptosis was determined by fluorescence staining of hypodiploidic cell nuclei. In chronic DSS-induced colitis both CD44 variant isoforms, v4 and v7 were significantly up-regulated on mononuclear cells. However, whereas anti-CD44v7 antibody treatment induced a marked restoration of the gut mucosa and significantly reduced endothelial sticking and extravasation of circulating leucocyte in vivo (P < 0.01), application of anti-CD44v4 or an isotype control antibody had no anti-inflammatory effect. A significant reduction of myeloperoxidase activity was detected after blockade of CD44v7, but not v4. Short-term treatment with anti-CD44v7 antibody blocks T cell extravasation and recruitment to the intestinal mucosa and cures established experimental colitis.

Treatment of murine Th1- and Th2-mediated inflammatory bowel disease with NF-kappa B decoy oligonucleotides

The Th1 and Th2 T cell responses that underlie inflammatory bowel diseases (IBDs) are likely to depend on NF-kappaB transcriptional activity. We explored this possibility in studies in which we determined the capacity of NF-kappaB decoy oligodeoxynucleotides (decoy ODNs) to treat various murine models of IBD. In initial studies, we showed that i.r. (intrarectal) or i.p. administration of decoy ODNs encapsulated in a viral envelope prevented and treated a model of acute trinitrobenzene sulfonic acid-induced (TNBS-induced) colitis, as assessed by clinical course and effect on Th1 cytokine production. In further studies, we showed that NF-kappaB decoy ODNs were also an effective treatment of a model of chronic TNBS-colitis, inhibiting both the production of IL-23/IL-17 and the development of fibrosis that characterizes this model. Treatment of TNBS-induced inflammation by i.r. administration of NF-kappaB decoy ODNs did not inhibit NF-kappaB in extraintestinal organs and resulted in CD4+ T cell apoptosis, suggesting that such treatment is highly focused and durable. Finally, we showed that NF-kappaB decoy ODNs also prevented and treated oxazolone-colitis and thus affect a Th2-mediated inflammatory process. In each case, decoy administration led to inflammation-clearing effects, suggesting a therapeutic potency applicable to human IBD.

Anti-inflammatory mechanism of oxymatrine in dextran sulfate sodium-induced colitis of rats

AIM: To investigate the anti-inflammatory mechanism of oxymatrine in dextran sulfate sodium (DSS)-induced colitis of rats.

METHODS: Acute colitis was induced by giving 2% DSS orally in drinking water for 8 d. Twenty-six male rats were randomized into oxymatrine-treated group (group A, 10 rats), DSS control (group B, 10 rats) and normal control (group C, 6 rats). The rats in group A were injected muscularly with oxymatrine at the dosage of 63 mg/(kg穌) from d 1 to 11 and drank 2% DSS solution from d 4 to 11. The rats in group B were treated with 0.9% saline in an equal volume as group A and drank 2% DSS solution from d 4 to 11. The rats in group C were treated with 0.9% saline as group B from d 1 to 11 and drank water normally. Diarrhea and bloody stool as well as colonic histology were observed. The levels of serum tumor necrosis factor-α (TNF-α) and interleukin-6 (IL-6) were determined by ELISA, and nuclear factor-κB (NF-κB) activity and the expression of inter-cellular adhesion molecule-1 (ICAM-1) in colonic mucosa were detected by immunohistochemistry method.

RESULTS: Compared with DSS control group, the inflammatory symptoms and histological damages of colonic mucosa in oxymatrine-treated group were significantly improved, the serum levels of TNF-α, IL-6, and the expression of NF-κB, ICAM-1 in colonic mucosa were significantly reduced.

CONCLUSION: The fact that oxymatrine can reduce the serum levels of TNF-α, IL-6, and the expression of NF-κB and ICAM-1 in colonic mucosa in DSS-induced colitis of rats indicates that oxymatrine may ameliorate the colonic inflammation and thus alleviate diarrhea and bloody stool.

Enhanced human beta-defensin-2 (hBD-2) expression by corticosteroids is independent of NF-kappaB in colonic epithelial cells (CaCo2)

Beta-defensins are small cationic peptides with antimicrobial properties that contribute to innate host defense. Unlike human beta-defensin-1 (hBD-1), which is produced constitutively, human beta-defensin-2 (hBD-2) is expressed after adequate stimulation by cytokines and/or bacterial endotoxins in epithelial tissue and mononuclear phagocytes but may be deficient in patients with Crohn's disease. To further elucidate the role of the intestinal epithelium in antimicrobial host defense, gene regulation of hBD-2 and the interaction with NF-kappaB were analyzed in a cell culture model. Human colonic epithelial cells (CaCo2) were stimulated by pro-inflammatory cytokines (IL-1beta, TNF-alpha, IF-gamma) to induce hBD-2 mRNA transcription. Interactions with NF-kappaB were analyzed using specific inhibitors (sulfasalazine, gliotoxine, dexamethasone) at different concentrations. Defensin mRNA expression was quantified by competitive RT-PCR and antibacterial capacity of supernatants was determined by an antimicrobial assay. HBD-2 mRNA transcription and antimicrobial activity of CaCo2 cells were induced by stimulation with pro-inflammatory cytokines. Induction was not inhibited by sulfasalazine or gliotoxine, whereas dexamethasone further enhanced both gene transcription and antimicrobial capacity. The lack of inhibition of induced hBD-2 expression by specific NF-kappaB antagonists suggests an additional pathway of activation, independent of NF-kappaB. The induction of hBD-2 expression in cytokine-stimulated CaCo2 cells by corticosteroids indicates further immunomodulatory ability of steroid hormones not yet understood.

Analysis of intestinal haem-oxygenase-1 (HO-1) in clinical and experimental colitis

Haem-oxygenase-1 (HO-1) has been shown to exert anti-inflammatory, anti-apoptotic and anti-proliferative effects. We investigated HO-1 expression in patients with inflammatory bowel disease (IBD) and could demonstrate a scattered expression of HO-1 in the intestinal epithelium of severely inflamed colonic mucosa of patients with IBD compared to control specimens such as diverticulitis, suggesting dysregulated expression in IBD. To further analyse potential mechanisms of HO-1 induction in the intestine we employed an in vitro epithelial cell apoptosis model and an experimental colitis model. In vitro induction of HO-1 by the HO-1 inducer cobalt protoporphyrin (CoPP) resulted in a dose-dependent down-regulation of caspase-3 activation in HT-29 cells, indicating an anti-apoptotic function of HO-1 in the intestine. In vivo, preventive HO-1 induction by CoPP in acute dextran sodium sulphate (DSS)-induced colitis led to a significant down-regulation of colonic inflammation (P < 0.01) with a concomitant reduction in interferon (IFN)-gamma - but unaffected interleukin (IL)-10-secretion by isolated mesenteric lymph nodes (P < 0.01). Additionally, TUNEL staining of colonic sections demonstrated fewer apoptotic epithelial cells in the colon of CoPP treated animals. No beneficial effects were observed if HO-1 was induced by CoPP after the onset of acute colitis or in chronic DSS-induced colitis. In conclusion, the data suggest a protective role of HO-1 if it is induced before the onset of inflammation. However, as shown by the lack of effects in established acute or in chronic colitis, the induction of HO-1 may not be a promising approach for the treatment of IBD.

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Blocking lymphotoxin-beta receptor activation diminishes inflammation via reduced mucosal addressin cell adhesion molecule-1 (MAdCAM-1) expression and leucocyte margination in chronic DSS-induced colitis

The lymphotoxin-beta receptor (LTbetaR) pathway is critical for maintenance of organized lymphoid structures and is involved in the development of colitis. To investigate the mechanisms by which LTbetaR activation contributes to the pathology of chronic inflammation we used a soluble LTbetaR-Ig fusion protein as a competitive inhibitor of LTbetaR activation in the mouse model of chronic colitis induced by oral administration of dextran sulphate sodium. Strong expression of LTbeta which constitutes part of the LTalpha(1)beta(2) ligand complex was detected in colonic tissue of mice with chronic colitis. Treatment with LTbetaR-Ig significantly attenuated the development and histological manifestations of the chronic inflammation and reduced the production of inflammatory cytokines such as TNF, IL-1beta, and IL-6. Moreover, LTbetaR-Ig treatment significantly down-regulated mucosal addressin cell adhesion molecule-1 (MAdCAM-1) expression, leading to reduced leucocyte rolling and sticking in postcapillary and collecting venules and reduced extravasation into the intestinal mucosa as quantified by in vivo fluorescence microscopy. Thus, LTbetaR pathway inhibition ameliorates DSS-induced experimental chronic colitis in mice by MAdCAM-1 down-regulation entailing reduced lymphocyte margination and extravasation into the inflamed mucosa. Therefore, a combined treatment with reagents blocking T cell-mediated perpetuation of chronic inflammation such as LTbetaR-Ig together with direct anti-inflammatory reagents such as TNF inhibitors could constitute a promising treatment strategy for chronic colitis.

Pioglitazone, a PPAR-gamma ligand, provides protection from dextran sulfate sodium-induced colitis in mice in association with inhibition of the NF-kappaB-cytokine cascade

Nuclear factor-kappaB-dependent up-regulation of inflammatory cytokines occurs in inflammatory bowel disease. We investigated the effect of pioglitazone, a peroxisome proliferator-activated receptor-gamma ligand, on dextran sulfate sodium-induced colonic mucosal injury and inflammation in mice. Acute colitis was induced in female mice receiving 0, 1, 3, and 10 mg/kg i.p. of pioglitazone daily. Colonic mucosal inflammation was evaluated chemically and histologically. Thiobarbituric acid-reactive substances and tissue-associated myeloperoxidase activity were measured in intestinal mucosa as indices of lipid peroxidation and neutrophil infiltration, respectively. Colonic mRNA expression of pro-inflammatory cytokines and inducible nitric oxide synthase was measured by reverse transcription-PCR and nuclear factor-kappaB activation was evaluated by electrophoretic mobility shift assay. Dextran sulfate sodium administration resulted in decreases in body weight and colon length and increases in lipid peroxide and neutrophil accumulation of the intestine. In contrast, co-administration with pioglitazone prevented these changes. Transcripts coding for pro-inflammatory cytokines and inducible nitric oxide were expressed in high levels after the development of colitis, and pioglitazone markedly reduced mRNA expression of these genes. DNA binding activity of nuclear factor-kappaB was markedly increased, whereas in pioglitazone co-treated intestines the effect was significantly reduced. These data suggest that peroxisome proliferator-activated receptor-gamma may be a novel therapeutic target for the therapy of inflammatory bowel disease.

Garlic (Allium sativum L.) modulates cytokine expression in lipopolysaccharide-activated human blood thereby inhibiting NF-kappaB activity

Garlic is proposed to have immunomodulatory and anti-inflammatory properties. This paper shows that garlic powder extracts (GPE) and single garlic metabolites modulate lipopolysaccharide (LPS)-induced cytokine levels in human whole blood. GPE-altered cytokine levels in human blood sample supernatants reduced nuclear factor (NF)-kappaB activity in human cells exposed to these samples. Pretreatment with GPE (100 mg/L) reduced LPS-induced production of proinflammatory cytokines interleukin (IL)-1beta from 15.7 +/- 5.1 to 6.2 +/- 1.2 micro g/L and tumor necrosis factor (TNF)-alpha from 8.8 +/- 2.4 to 3.9 +/- 0.8 micro g/L, respectively, whereas the expression of the anti-inflammatory cytokine IL-10 was unchanged. The garlic metabolite diallydisulfide (1-100 micro mol/L) also significantly reduced IL-1beta and TNF-alpha. Interestingly, exposure of human embryonic kidney cell line (HEK293) cells to GPE-treated blood sample supernatants (10 or 100 mg/L) reduced NF-kappaB activity compared with cells exposed to untreated blood supernatants as measured by a NF-kappaB-driven luciferase reporter gene assay. Blood samples treated with extract obtained from unfertilized garlic (100 mg/L) reduced NF-kappaB activity by 25%, whereas blood samples treated with sulfur-fertilized garlic extracts (100 mg/L) lowered NF-kappaB activity by 41%. In summary, garlic may indeed promote an anti-inflammatory environment by cytokine modulation in human blood that leads to an overall inhibition of NF-kappaB activity in the surrounding tissue.

Enhanced intestinal inflammation induced by dextran sulfate sodium in tumor necrosis factor-alpha deficient mice

BACKGROUND AND AIMS

Tumor necrosis factor-alpha (TNF-alpha) is a potent pro-inflammatory cytokine thought to be involved in the pathogenesis of inflammatory bowel disease. To further define the role of TNF-alpha in intestinal inflammation, we studied the effects of dextran sulfate sodium (DSS) administration in mice with targeted deletions of TNF-alpha gene.

METHODS

Acute colitis was induced in female TNF-alpha-/- and TNF-alpha+/+ mice by administering 4.5% DSS orally in drinking water for seven days. The colonic mucosal injury and inflammation was evaluated based on body weight changes, total colon length, luminal hemoglobin, and histological findings. Colonic mRNA expression for inducible nitric oxide synthase (iNOS), TNF-alpha, interferon-gamma (IFN-gamma) and interleukin-4 (IL-4) were measured by reverse transcription polymerase chain reaction (RT-PCR), and nuclear factor kappaB (NF-kappaB) activation was evaluated by electrophoretic mobility shift assay.

RESULTS

In each assessment, colonic injury was significantly aggravated in DSS-treated TNF-alpha-/- mice compared with DSS-treated TNF-alpha+/+ mice. The survival rate of TNF-alpha-/- mice on day seven was 40%; in contrast, all TNF-alpha+/+ mice were alive. Histological study also showed an enhanced infiltration of inflammatory cells, especially neutrophils, and mucosal cell disruption in DSS-treated TNF-alpha-/- mice compared with DSS-treated TNF-alpha+/+ mice. On day seven, mRNA levels of IFN-gamma and IL-4 in the colons of TNF-alpha-/- mice were faint or not detected; in contrast, those of TNF-alpha+/+ mice were detected. Although the expression of iNOS mRNA and luminal nitrite levels were similarly increased in both mice on day seven, this induction was delayed in TNF-alpha-/- mice during the early phase. The degree of NF-kappaB binding activity seemed to be similar between the two types of mice on day seven.

CONCLUSION

DSS-induced inflammation is significantly enhanced in TNF-alpha-/- mice compared to TNF-alpha+/+ mice. These data suggest that persistent and marked blockage of TNF-alpha bioactivity may provide a detrimental effect on acute intestinal inflammation.