Tumour necrosis factor in mouse models of chronic intestinal inflammation

Pentavalent outer membrane vesicles immunized mice sera confers passive protection against five prevalent pathotypes of diarrhoeagenic Escherichia coli in neonatal mice

Diarrhoeagenic Escherichia coli (DEC) pathotypes are one of the major causative agents of diarrhoea induced childhood morbidity and mortality in developing countries. Licensed vaccines providing broad spectrum protection against DEC mediated infections are not available. Outer membrane vesicles (OMVs) are microvesicles released by gram-negative bacteria during the growth phase and contain multiple immunogenic proteins. Based on prevalence of infections, we have formulated a pentavalent outer-membrane vesicles (POMVs) based immunogen targeting five main pathotypes of DEC responsible for diarrhoeal diseases. Following isolation, OMVs from five DEC pathotypes were mixed in equal proportions to formulate POMVs and 10 µg of the immunogen was intraperitoneally administered to adult BALB/c mice. Three doses of POMVs induced significant humoral immune response against whole cell lysates (WCLs), outer membrane proteins (OMPs) and lipopolysaccharides (LPS) isolated from DEC pathotypes along with significant induction of cellular immune response in adult mice. Passive transfer of POMVs immunized adult mice sera protected neonatal mice significantly against DEC infections. Overall, this study finds POMVs to be immunogenic in conferring broad-spectrum passive protection to neonatal mice against five main DEC pathotypes. Altogether, these findings suggest that POMVs can be used as a potent vaccine candidate to ameliorate the DEC-mediated health burden.

Recent advances in development of nano-carriers for immunogene therapy in various complex disorders

Immunotherapy is a novel preference for the treatment of various complex diseases. Considering the application of varying agents for suppression or activation of the immune system, immunogene therapy was confirmed to stand as a proper alternative for other immunotherapeutic strategies due to its capability in targeting cells with more specificity that leads to controlling the expression of therapeutic genes. This method facilitates the local and single-dose application of most gene therapies that result in the usage of high therapeutic doses with a low risk of systemic side effects while being cost-efficient in long-term administrations. However, the existing barriers between the administration site and cell nucleus limited the clinical uses of genetic materials. These challenges can be overcome through the promising method of exerting non-carriers with high stability, low toxicity/immunogenicity, and simple modifications. In this study, we attempted to review the potential of nanoparticle application throughout the immunogene therapy of different diseases including cancer, microbial diseases, allergies, inflammatory bowel disease, rheumatoid arthritis, and respiratory infections. We included the outline of some challenges and opportunities in regards to the delivery of genetic materials that are based on nano-systems through immunotherapy of these disorders. Next to the promising future of these vectors, more detailed analyses are required to overcome the current limitations in clinical approaches.

St. John's Wort alleviates dextran sodium sulfate-induced colitis through pregnane X receptor-dependent NFκB antagonism

St. John's wort (SJW), from traditional herbs, activates the pregnane X receptor (PXR), a potential drug target for treating inflammatory bowel disease (IBD). However, how SJW alleviates dextran sodium sulfate (DSS)-induced experimental IBD by activating PXR is unknown. To test this, PXR-humanized, wild-type (WT) and Pxr-null mice, primary intestinal organoids cultures, and the luciferase reporter gene assays were employed. In vivo, a diet supplemented with SJW was found to activate intestinal PXR both in WT and PXR-humanized mice, but not in Pxr-null mice. SJW prevented DSS-induced IBD in PXR-humanized and WT mice, but not in Pxr-null mice. In vitro, hyperforin, a major component of SJW, activated PXR and suppressed tumor necrosis factor (TNF)α-induced nuclear factor (NF) κB translocation in primary intestinal organoids from PXR-humanized mice, but not Pxr-null mice. Luciferase reporter gene assays showed that hyperforin dose-dependently alleviated TNFα-induced NFκB transactivation by activating human PXR in Caco2 cells. Furthermore, SJW therapeutically attenuated DSS-induced IBD in PXR-humanized mice. These data indicate the therapeutic potential of SJW in alleviating DSS-induced IBD in vivo, and TNFα-induced NFκB activation in vitro, dependent on PXR activation, which may have clinical implications for using SJW as a herbal drug anti-IBD treatment.

The phytonutrient cinnamaldehyde limits intestinal inflammation and enteric parasite infection

Phytonutrients such as cinnamaldehyde (CA) have been studied for their effects on metabolic diseases, but their influence on mucosal inflammation and immunity to enteric infection are not well documented. Here, we show that consumption of CA in mice significantly down-regulates transcriptional pathways connected to inflammation in the small intestine, and alters T-cell populations in mesenteric lymph nodes. During infection with the enteric helminth Heligomosomoides polygyrus, CA treatment attenuated infection-induced changes in biological pathways connected to cell cycle and mitotic activity, and tended to reduce worm burdens. Mechanistically, CA did not appear to exert activity through a prebiotic effect, as CA treatment did not significantly change the composition of the gut microbiota. Instead, in vitro experiments showed that CA directly induced xenobiotic metabolizing pathways in intestinal epithelial cells and suppressed endotoxin-induced inflammatory responses in macrophages. Collectively, our results show that CA down-regulates inflammatory pathways in the intestinal mucosa and can limit the pathological response to enteric infection. These properties appear to be largely independent of the gut microbiota, and instead connected to the ability of CA to induce antioxidant pathways in intestinal cells. Our results encourage further investigation into the use of CA and related phytonutrients as functional food components to promote intestinal health in humans and animals.

Impact of Interleukin 10 Deficiency on Intestinal Epithelium Responses to Inflammatory Signals

Interleukin 10 (IL-10) is a pleiotropic, anti-inflammatory cytokine that has a major protective role in the intestine. Although its production by cells of the innate and adaptive immune system has been extensively studied, its intrinsic role in intestinal epithelial cells is poorly understood. In this study, we utilised both ATAC sequencing and RNA sequencing to define the transcriptional response of murine enteroids to tumour necrosis factor (TNF). We identified that the key early phase drivers of the transcriptional response to TNF within intestinal epithelium were NFκB transcription factor dependent. Using wild-type and Il10-/- enteroid cultures, we showed an intrinsic, intestinal epithelium specific effect of IL-10 deficiency on TNF-induced gene transcription, with significant downregulation of identified NFκB target genes Tnf, Ccl20, and Cxcl10, and delayed overexpression of NFκB inhibitor encoding genes, Nfkbia and Tnfaip3. IL-10 deficiency, or immunoblockade of IL-10 receptor, impacted on TNF-induced endogenous NFκB activity and downstream NFκB target gene transcription. Intestinal epithelium-derived IL-10 appears to play a crucial role as a positive regulator of the canonical NFκB pathway, contributing to maintenance of intestinal homeostasis. This is particularly important in the context of an inflammatory environment and highlights the potential for future tissue-targeted IL-10 therapeutic intervention.

Physical Activity Shapes the Intestinal Microbiome and Immunity of Healthy Mice but Has No Protective Effects against Colitis in MUC2-/- Mice

Perturbation in the gut microbial ecosystem has been associated with various diseases, including inflammatory bowel disease. Habitual physical activity, through its ability to modulate the gut microbiome, has recently been shown to prophylactically protect against chemically induced models of murine colitis. Here, we (i) confirm previous reports that physical activity has limited but significant effects on the gut microbiome of mice and (ii) show that such changes are associated with anti-inflammatory states in the gut, such as increased production of beneficial short-chain fatty acids and lower levels of proinflammatory immune markers implicated in human colitis; however, we also show that (iii) these physical activity-derived benefits are completely lost in the absence of a healthy intestinal mucus layer, a hallmark phenotype of human colitis.

The interactions among humans, their environment, and the trillions of microbes residing within the human intestinal tract form a tripartite relationship that is fundamental to the overall health of the host. Disruptions in the delicate balance between the intestinal microbiota and host immunity are implicated in various chronic diseases, including inflammatory bowel disease (IBD). There is no known cure for IBD; therefore, novel therapeutics targeting prevention and symptom management are of great interest. Recently, physical activity in healthy mice was shown to be protective against chemically induced colitis; however, the benefits of physical activity during or following disease onset are not known. In this study, we examine whether voluntary wheel running is protective against primary disease symptoms in a mucin 2-deficient (Muc2^−/−) lifelong model of murine colitis. We show that 6 weeks of wheel running in healthy C57BL/6 mice leads to distinct changes in fecal bacteriome, increased butyrate production, and modulation in colonic gene expression of various cytokines, suggesting an overall primed anti-inflammatory state. However, these physical activity-derived benefits are not present in Muc2^−/− mice harboring a dysfunctional mucosal layer from birth, ultimately showing no improvements in clinical signs. We extrapolate from our findings that while physical activity in healthy individuals may be an important preventative measure against IBD, for those with a compromised intestinal mucosa, a commonality in IBD patients, these benefits are lost.

IMPORTANCE Perturbation in the gut microbial ecosystem has been associated with various diseases, including inflammatory bowel disease. Habitual physical activity, through its ability to modulate the gut microbiome, has recently been shown to prophylactically protect against chemically induced models of murine colitis. Here, we (i) confirm previous reports that physical activity has limited but significant effects on the gut microbiome of mice and (ii) show that such changes are associated with anti-inflammatory states in the gut, such as increased production of beneficial short-chain fatty acids and lower levels of proinflammatory immune markers implicated in human colitis; however, we also show that (iii) these physical activity-derived benefits are completely lost in the absence of a healthy intestinal mucus layer, a hallmark phenotype of human colitis.

Novel functions of inactive rhomboid proteins in immunity and disease

iRhoms are related to a family of intramembrane serine proteinases called rhomboids but lack proteolytic activity. In mammals, there are two iRhoms, iRhom1 and iRhom2, which have similar domain structures and overlapping specificities as well as distinctive functions. These catalytically inactive rhomboids are essential regulators for the maturation and trafficking of the disintegrin metalloprotease ADAM17 from the endoplasmic reticulum to the cell surface, and are required for the cleavage and release of a variety of membrane-associated proteins, including the IL-6 receptor, l-selectin, TNF, and EGFR ligands. iRhom2-dependent regulation of ADAM17 function has been recently implicated in the development and progression of several autoimmune diseases including rheumatoid arthritis, lupus nephritis, as well as hemophilic arthropathy. In this review, we discuss our current understanding of iRhom biology, their implications in autoimmune pathologies, and their potential as therapeutic targets.

Human TNF-Luc reporter mouse: A new model to quantify inflammatory responses

Tumour necrosis factor (TNF) is a key cytokine during inflammatory responses and its dysregulation is detrimental in many inflammatory diseases, such as rheumatoid arthritis and inflammatory bowel disease. Here, we used a bacterial artificial chromosome (BAC) construct that expresses luciferase under the control of the human TNF locus to generate a novel transgenic mouse, the hTNF.LucBAC strain. In vitro stimulation of hTNF.LucBAC cells of different origin revealed a cell specific response to stimuli demonstrating the integrated construct's ability as a proxy for inflammatory gene response. Lipopolysaccharide was the most potent luciferase inducer in macrophages, while TNF was a strong activator in intestinal organoids. Lipopolysaccharide-induced luciferase activity in macrophages was downregulated by inhibitors of NF-κB pathway, as well as by Interleukin-10, a known anti-inflammatory cytokine. Moreover, the transgene-dependent luciferase activity showed a positive correlation to the endogenous murine soluble TNF secreted to the culture medium. In conclusion, the hTNF.LucBAC strain is a valuable tool for studying and screening molecules that target TNF synthesis and will allow further functional studies of the regulatory elements of the TNF locus.

Local delivery of macromolecules to treat diseases associated with the colon

Current treatments for intestinal diseases including inflammatory bowel diseases, irritable bowel syndrome, and colonic bacterial infections are typically small molecule oral dosage forms designed for systemic delivery. The intestinal permeability hurdle to achieve systemic delivery from oral formulations of macromolecules is challenging, but this drawback can be advantageous if an intestinal region is associated with the disease. There are some promising formulation approaches to release peptides, proteins, antibodies, antisense oligonucleotides, RNA, and probiotics in the colon to enable local delivery and efficacy. We briefly review colonic physiology in relation to the main colon-associated diseases (inflammatory bowel disease, irritable bowel syndrome, infection, and colorectal cancer), along with the impact of colon physiology on dosage form design of macromolecules. We then assess formulation strategies designed to achieve colonic delivery of small molecules and concluded that they can also be applied some extent to macromolecules. We describe examples of formulation strategies in preclinical research aimed at colonic delivery of macromolecules to achieve high local concentration in the lumen, epithelial-, or sub-epithelial tissue, depending on the target, but with the benefit of reduced systemic exposure and toxicity. Finally, the industrial challenges in developing macromolecule formulations for colon-associated diseases are presented, along with a framework for selecting appropriate delivery technologies.

The Indices of Nitric Oxide System in Rats with Carrageenan-Induced Enterocolitis Combined with Diabetes Mellitus

Background and aims: Diabetes mellitus (DM) represents a considerable public health issue, being one of the major causes of morbidity and mortality in the modern societies. Chronic hyperglycemia is accompanied by significant physiological, biochemical, and histological changes, e.g. development of oxidative stress that affects the motor activity of the intestine. This study aimed to evaluate the indices of nitric oxide (NO) system in blood serum and colon tissue supernatant of rats with carrageenan-induced enterocolitis combined with streptozotocin-induced diabetes.

Material and methods: The total NOS activity was determined by monitoring the rate of conversion of L-arginine into citrulline. The total quantity of NO metabolites was assessed by evaluating their amount, which included nitrite ions that were initially present in the sample (NO2 −) and nitrate ions reducted to nitrites (NO3 −).

Results: We found a significant increase in total NOS activity in colon tissue of all experimental groups vs. control animals (54.8, 30.6 and 79.2 % respectively). The total content of NO metabolites in colon tissue of all experimental groups also significantly increased (2.8, 1.9 and 3.4 times respectively) compared to the control animals.

Conclusions: We observed activation of nitroxydergic process in blood serum and colon tissue of rats with carrageenan-induced enterocolitis. Nitroxydergic processes markedly intensified in rats with carrageenan-induced enterocolitis combined with diabetes mellitus.

Infliximab Selectively Modulates the Circulating Blood Monocyte Repertoire in Crohn's Disease

BACKGROUND

Infliximab (IFX), an anti-tumour necrosis factor alpha (TNFα) monoclonal antibody, provides clinical benefits in treating Crohn's disease (CD) but its mechanisms of action are not fully elucidated. This study investigated blood monocyte repertoires and the acute effects of IFX infusion on monocyte subset phenotype and function in IFX-treated patients with CD.

METHODS

Monocytes and monocyte subsets were enumerated and phenotypically characterized by multicolor flow cytometry in freshly isolated blood from healthy controls (n = 21) and patients with CD treated with (IFX, n = 24) and without (non-IFX, n = 20) IFX. For the IFX-CD group, blood was sampled immediately before (tough-IFX) and after (peak-IFX) infusion. Monocyte responses to lipopolysaccharide were analyzed by whole-blood intracellular cytokine staining.

RESULTS

Non-IFX and IFX-CD patients had increased numbers of intermediate (CD14CD16) monocytes compared with healthy controls, whereas classical (CD14CD16) and nonclassical (CD14CD16) monocytes were numerically reduced in the IFX-CD group alone. In all groups, monocyte subsets expressed high surface levels of transmembrane (tm)TNFα. After IFX infusion, a significant reduction in monocyte numbers occurred. Post-IFX monocytopenia was proportionately greatest for classical and intermediate subsets, correlated with postinfusion IFX levels and was not associated with monocyte apoptosis. In contrast, lipopolysaccharide-induced production of TNFα and IL-12 by monocytes was significantly reduced in peak-IFX compared with trough-IFX blood samples.

CONCLUSIONS

Actively managed CD is associated with monocyte repertoire skewing suggestive of chronic inflammatory stimulation. Infused IFX acutely targets monocytes, likely by binding to tmTNFα, resulting in a non-apoptosis-related decline in circulating monocyte numbers and blunting of the inflammatory response of monocytes remaining in the blood.

Regulatory effects of glycyrrhizae radix extract on DSS-induced ulcerative colitis

BACKGROUND

Glycyrrhizae Radix (GR) is a Korean traditional herb medicine that is widely-used in clinical health care. The clinical functions of GR include relief of toxicity, anti-cancer, regulating blood cholesterol and anti-inflammation. This study investigated the role of GR on ulcerative colitis in a dextran sulfate sodium (DSS)-induced mouse model of colitis.

METHOD

Western blot analysis and enzyme-linked immunosorbent assay (ELISA) analyses were done on male BALB/c mice administered 5 % DSS during the experimental period. Ethanol extracts of GR were orally administered at same time daily to control mice. The severity of colitis was measured by body weight change and colon length.

RESULT

DSS-treated mice displayed weight loss and shortened colon length compared with control mice. Mice were administered GR showed less weight loss and longer colon length than the DSS-treated group. Inflammatory cytokines were decreased by GR treatment. Treatment also reduced DSS-induced microscopic damage to colon tissue. GR regulated the phosphorylation of transcription factors such as NF-κB p65 and IκB α.

CONCLUSIONS

GR has beneficial effects in a colitis model. GR might be a useful herb medicine in the treatment of ulcerative colitis.

Early Detection of T cell Transfer-induced Autoimmune Colitis by In Vivo Imaging System

Inflammatory bowel disease is a chronic and progressive inflammatory intestinal disease that includes two major types, namely ulcerative colitis and Crohn’s disease (CD). CD is characterized by intestinal epithelial hyperplasia and inflammatory cell infiltration. Transfer of CD25⁻CD45RB^hiCD4⁺ (naïve) T cells into immunodeficiency mice induces autoimmune colitis with pathological lesions similar to CD and loss of body weight 4 weeks after cell transfer. However, weight loss neither has sufficient sensitivity nor totally matches the pathological findings of CD. To establish an early and sensitive indicator of autoimmune colitis model, the transferred T cell-induced colitis mouse model was modified by transferring luciferase-expressing donor T cells and determining the colitis by in vivo imaging system (IVIS). Colitis was detected with IVIS 7–10 days before the onset of body weight loss and diarrhea. IVIS was also applied in the dexamethasone treatment trial, and was a more sensitive indicator than body weight changes. All IVIS signals were parallel to the pathological abnormalities of the gut and immunological analysis results. In summary, IVIS provides both sensitive and objective means to monitor the disease course of transferred T cell-induced CD and fulfills the 3Rs principle of humane care of laboratory animals.

The Intersection of TNF, IBD and the Microbiome

Inflammatory bowel disease (IBD), comprised of Crohn's disease and ulcerative colitis, is a chronic inflammatory condition of multifactorial etiology and risk factors. Currently, one of the most effective treatments for IBD is the use of Tumor Necrosis Factor (TNF) functional inhibitor drugs, however, this treatment can cause adverse reactions and has a relatively large percentage of incomplete or non-responders. This lack of response may be related to differences in patients' gut microbiomes prior to and after disease initiation or treatment. Recent observations in our lab using a rodent model of IBD support the theory that TNF drives acute colitis, but also that the microbiome differs in association with TNF production and colitis severity. Studies such as this and others provide new insights into host-microbiome interactions associated with colitis that can lead to new therapies to prevent or treat the disease.

Spontaneous and transgenic rodent models of inflammatory bowel disease

Inflammatory Bowel Disease (IBD) is a multifactorial disorder with many different putative influences mediating disease onset, severity, progression and diminution. Spontaneous natural IBD is classically expressed as Crohn's Disease (CD) and Ulcerative Colitis (UC) commonly found in primates; lymphoplasmocytic enteritis, eosinophilic gastritis and colitis, and ulcerative colitis with neuronal hyperplasia in dogs; and colitis in horses. Spontaneous inflammatory bowel disease has been noted in a number of rodent models which differ in genetic strain background, induced mutation, microbiota influences and immunopathogenic pathways. Histological lesions in Crohn's Disease feature noncaseating granulomatous inflammation while UC lesions typically exhibit ulceration, lamina propria inflammatory infiltrates and lack of granuloma development. Intestinal inflammation caused by CD and UC is also associated with increased incidence of intestinal neoplasia. Transgenic murine models have determined underlying etiological influences and appropriate therapeutic targets in IBD. This literature review will discuss current opinion and findings in spontaneous IBD, highlight selected transgenic rodent models of IBD and discuss their respective pathogenic mechanisms. It is very important to provide accommodation of induced putative deficits in activities of daily living and to assess discomfort and pain levels in the face of significant morbidity and/or mortality in these models. Epigenetic, environmental (microbiome, metabolome) and nutritional factors are important in IBD pathogenesis, and evaluating ways in which they influence disease expression represent potential investigative approaches with the greatest potential for new discoveries.

Beneficial effects of the traditional medicine Igongsan and its constituent ergosterol on dextran sulfate sodium-induced colitis in mice

Ulcerative colitis (UC) is a type of inflammatory bowel disease and is considered a chronic gastrointestinal disorder. Igongsan (IGS) is a Korean herbal medicine, which has been used to treat digestive disorders. However, the ameliorative effect and molecular mechanisms of IGS in intestinal inflammation have not yet been studied in detail. The present study aimed to investigate the protective effects of IGS and its constituent, ergosterol, in a mouse model of dextran sulfate sodium (DSS)‑induced colitis. Colitis was induced in mice by supplementing their drinking water with 5% (w/v) DSS for 7 days. The effects of IGS were then determined on DSS‑induced clinical signs of colitis, including weight loss, colon shortening, diarrhea and obscure/gross bleeding. In addition, the effects of IGS were determined on the expression levels of inflammation‑associated genes in the colon tissue of DSS‑treated mice. The results of the present study demonstrated that mice treated with DSS exhibited marked clinical symptoms, including weight loss and reduced colon length. Treatment with IGS attenuated these symptoms and also suppressed the expression levels of tumor necrosis factor‑α and interleukin‑6, as well as the expression of cyclooxygenase‑2 in the colon tissue of DSS‑treated mice. IGS also reduced the activation of the transcription factor nuclear factor‑κB p65 in the colon tissue of DSS‑treated mice. In addition, ergosterol was shown to attenuate the DSS‑induced clinical symptoms of colitis in mice. In conclusion, the present study provided experimental evidence that IGS may be a useful therapeutic drug for patients with UC.

Optimization of multifunctional chitosan-siRNA nanoparticles for oral delivery applications, targeting TNF-α silencing in rats

Secretion of tumor necrosis factor-α (TNF-α) by macrophages plays a predominant role in the development and progression of various inflammatory diseases. In the current contribution, multifunctional nanoparticles (NPs) containing TNF-α siRNA targeting macrophages via oral administration were developed to knockdown TNF-α expression against acute hepatic injury in rats. Mannose-modified trimethyl chitosan-cysteine (MTC) NPs were prepared by self-assembly method (sa-MTC NPs), ionic gelation and siRNA entrapment method (en-MTC NPs), and ionic gelation and siRNA adsorption method (ad-MTC NPs). Among them, en-MTC NPs demonstrated the best stability against ionic challenges with desired siRNA integrity against nucleases. By targeting normal enterocytes and M cells that express mannose receptors, en-MTC NPs notably promoted intestinal absorption of siRNA in rats. They further facilitated siRNA internalization by rat peritoneal exudate cells (PECs) via lipid-raft involved endocytosis and macropinocytosis, thus inducing effective in vitro TNF-α knockdown. Orally delivered en-MTC NPs at a low siRNA dose of 50 μg/kg inhibited systemic TNF-α production and decreased TNF-α mRNA levels in macrophage-enriched liver, spleen, and lung tissues, which consequently protected rats from acute hepatic injury. Therefore, the en-MTC NPs would provide an effective approach to orally deliver TNF-α siRNA for the anti-inflammatory therapy.

TNF blocking therapies and immunomonitoring in patients with inflammatory bowel disease

Since their appearance in the armamentarium for inflammatory bowel disease (IBD) more than a decade ago, antitumor necrosis factor (TNF) inhibitors have demonstrated beneficial activity in induction and maintenance of clinical remission, mucosal healing, improvement in quality of life, and reduction in surgeries and hospitalizations. However, more than one-third of patients present primary resistance, and another one-third become resistant over time. One of the main factors associated with loss of response is the immunogenicity of anti-TNF biologics leading to the production of antidrug antibodies (ADAbs) accelerating their clearance. In this review we present the current state of the literature on the place of TNF and its blockage in the treatment of patients with IBD and discuss the usefulness of serum trough levels and ADAb monitoring in the optimization of anti-TNF therapies.

Ixeris dentata NAKAI Reduces Clinical Score and HIF-1 Expression in Experimental Colitis in Mice

Ixeris dentata (ID) is an herbal medicine used in Asian countries to treat indigestion, pneumonia, hepatitis, contusions, and tumors; however, its effect on intestinal inflammation is unknown. Thus, we investigated the effect of ID in the dextran sulfate sodium (DSS) model of colitis in female BALB/c mice; animals were evaluated after seven days of DSS treatment. DSS-treated mice showed considerable clinical signs, including weight loss, reduced colon length, colonic epithelial injury, infiltration of inflammatory cells in the colon tissue, and upregulation of inflammatory mediators. However, administration of ID attenuated body weight loss, colon shortening, and the increase in disease activity index score. ID also significantly decreased the colonic mucosal injury and the number of infiltrating mast cells. Moreover, ID inhibited the expressions of cyclooxygenase-2 and hypoxia-inducible factor-1α in colon tissue. Taken together, the results provide experimental evidence that ID might be a useful therapy for patients with ulcerative colitis.

Potential prospects of nanomedicine for targeted therapeutics in inflammatory bowel diseases

Inflammatory bowel diseases (IBDs) such as Crohn’s disease are highly debilitating. There are inconsistencies in response to and side effects in the current conventional medications, failures in adequate drug delivery, and the lack of therapeutics to offer complete remission in the presently available treatments of IBD. This suggests the need to explore beyond the horizons of conventional approaches in IBD therapeutics. This review examines the arena of the evolving IBD nanomedicine, studied so far in animal and in vitro models, before comprehensive clinical testing in humans. The investigations carried out so far in IBD models have provided substantial evidence of the nanotherapeutic approach as having the potential to overcome some of the current drawbacks to conventional IBD therapy. We analyze the pros and cons of nanotechnology in IBD therapies studied in different models, aimed at different targets and mechanisms of IBD pathogenesis, in an attempt to predict its possible impact in humans.

Comparative evaluation of different doses of green tea extract alone and in combination with sulfasalazine in experimentally induced inflammatory bowel disease in rats

BACKGROUND

The exact etiopathology of inflammatory bowel disease is still unclear. Most of the therapies present are directed towards symptomatic improvement. Surgical therapy in the form of restorative proctocolectomy is reserved for the terminal stage disease, which is unresponsive to medical therapy. The present study was conducted to evaluate the effect of green tea in experimentally induced inflammatory bowel disease.

METHODS

A total of 36 animals were included in the study. The animals were divided into five groups (n = 6): Group I-Vehicle (ethanol), group II-TNBS + ethanol, group III-green tea-treated group was divided into two sub-groups on the basis of different doses: group IIIA-TNBS + green tea (35 mg/kg), group IIIB-TNBS + green tea (70 mg/kg), group IV-TNBS + sulfasalazine (360 mg/kg), group V-TNBS + sulfasalazine (360 mg/kg) + green tea (least effective dose found in group III). After completion of 2 weeks of treatment, the rats were killed under ether anesthesia by cervical dislocation for assessment of intestinal inflammation, histological analysis, myeloperoxidase assay, malondialdehyde assay, and TNF-α estimation.

RESULTS

The study showed that green tea alone and in combination with sulfasalazine reduced inflammatory changes induced by tri nitro benzene sulfonic acid in rats. This reduction is associated with reduced malondialdehyde, lipid peroxidation, and TNF-α. This correlates well with both gross morphological and histopathological scores.

CONCLUSIONS

The authors concluded that a combination of green tea extract with sulfasalazine showed greater efficacy than single drug treatment.

Dual TNF-α/Cyclin D1 Gene Silencing With an Oral Polymeric Microparticle System as a Novel Strategy for the Treatment of Inflammatory Bowel Disease

OBJECTIVES:

RNA silencing utilizing short interfering RNA (siRNA) offers a new and exciting means to overcome the limitations of current treatment options of many diseases. However, delivery of these molecules still poses a great challenge to date.

METHODS:

In the present study, a multicompartmental biodegradable polymer-based nanoparticles-in-microsphere oral system (NiMOS) using gelatin nanoparticles encapsulating a combination of siRNA duplexes specifically targeted against tumor necrosis factor-α (TNF-α) and cyclin D1 (Ccnd1) was employed to study its effects on a dextran sulfate sodium (DSS)-induced acute colitis mouse model mimicking inflammatory bowel disease (IBD). DSS colitis-bearing animals were divided into several control and treatment groups and received either no treatment, blank NiMOS, NiMOS-encapsulating inactive (scrambled), active TNF-α silencing, CyD1 silencing siRNA, or a combination of both active siRNAs by repeated oral administration of three NiMOS doses.

RESULTS:

Successful gene silencing with the aid of dual siRNA treatment led to decreased colonic levels of TNF-α or CyD1, suppressed expression of certain pro-inflammatory cytokines (interleukin-1α and -β, interferon-γ), an increase in body weight, and reduced tissue myeloperoxidase activity, while the silencing effect of CyD1 siRNA or the dual treatment was more potent than that of TNF-α siRNA alone.

CONCLUSION:

Results of this study demonstrate the therapeutic potential of a NiMOS-based oral combined TNF-α and CyD1 gene silencing system for the treatment of IBD as shown in an acute colitis model.

Oral TNF-α gene silencing using a polymeric microsphere-based delivery system for the treatment of inflammatory bowel disease

The purpose of this study was to evaluate down-regulation of tumor necrosis factor (TNF)-α by oral RNA interference therapy. Control (scrambled sequence) or TNF-α specific small interfering RNA (siRNA) was encapsulated in type B gelatin nanoparticles and further entrapped in poly(epsilon-caprolactone) (PCL) microspheres to form a nanoparticles-in-microsphere oral system (NiMOS). Upon confirmation of the dextran sulfate sodium (DSS)-induced acute colitis model, mice were divided into several treatment groups receiving no treatment, blank NiMOS, NiMOS with scramble siRNA, or NiMOS with TNF-α silencing siRNA by oral administration. Successful gene silencing led to decreased colonic levels of TNF-α, suppressed expression of other pro-inflammatory cytokines (e.g., interleukin (IL)-1β, interferon (IFN)-γ) and chemokines (MCP-1), an increase in body weight, and reduced tissue myeloperoxidase activity. Results of this study established the clinical potential of a NiMOS-based oral TNF-α gene silencing system for the treatment of inflammatory bowel disease as demonstrated in an acute colitis model.

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

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

The microbiota mediates pathogen clearance from the gut lumen after non-typhoidal Salmonella diarrhea

Many enteropathogenic bacteria target the mammalian gut. The mechanisms protecting the host from infection are poorly understood. We have studied the protective functions of secretory antibodies (sIgA) and the microbiota, using a mouse model for S. typhimurium diarrhea. This pathogen is a common cause of diarrhea in humans world-wide. S. typhimurium (S. tm^att, sseD) causes a self-limiting gut infection in streptomycin-treated mice. After 40 days, all animals had overcome the disease, developed a sIgA response, and most had cleared the pathogen from the gut lumen. sIgA limited pathogen access to the mucosal surface and protected from gut inflammation in challenge infections. This protection was O-antigen specific, as demonstrated with pathogens lacking the S. typhimurium O-antigen (wbaP, S. enteritidis) and sIgA-deficient mice (TCRβ^−/−δ^−/−, J_H^−/−, IgA^−/−, pIgR^−/−). Surprisingly, sIgA-deficiency did not affect the kinetics of pathogen clearance from the gut lumen. Instead, this was mediated by the microbiota. This was confirmed using ‘L-mice’ which harbor a low complexity gut flora, lack colonization resistance and develop a normal sIgA response, but fail to clear S. tm^att from the gut lumen. In these mice, pathogen clearance was achieved by transferring a normal complex microbiota. Thus, besides colonization resistance ( = pathogen blockage by an intact microbiota), the microbiota mediates a second, novel protective function, i.e. pathogen clearance. Here, the normal microbiota re-grows from a state of depletion and disturbed composition and gradually clears even very high pathogen loads from the gut lumen, a site inaccessible to most “classical” immune effector mechanisms. In conclusion, sIgA and microbiota serve complementary protective functions. The microbiota confers colonization resistance and mediates pathogen clearance in primary infections, while sIgA protects from disease if the host re-encounters the same pathogen. This has implications for curing S. typhimurium diarrhea and for preventing transmission.

Numerous pathogens infect the gut. Protection against these infections is mediated by mucosal immune defenses including secreted IgA as well as by the competing intestinal microbiota. However, so far the relative importance of these two different defense mechanisms remains unclear. We addressed this question using the example of non-typhoidal Salmonella (NTS) gut infections which can be spread in stool of infected patients over long periods of time. We used a mouse model to reveal that the intestinal microbiota and the adaptive immune system hold different but complementary functions in fighting NTS infections. A primary Salmonella infection disrupts the normal microbiota and elicits Salmonella-specific sIgA. sIgA prevents disease when the animal is infected with NTS for a second time. However, sIgA was dispensable for pathogen clearance from the gut. Instead, this was mediated by the microbiota. By re-establishing its normal density and composition, the microbiota was necessary and sufficient for terminating long-term fecal Salmonella excretion. This establishes a novel paradigm: The microbiota clears the pathogen from the gut lumen, while sIgA protects from disease upon re-infection with the same pathogen. This has implications for the evolutionary role of sIgA responses as well as for developing microbiota-based therapies for curing infected patients.

Adiponectin deficiency modulates adhesion molecules expression and cytokine production but does not affect disease severity in the transfer model of colitis

We investigated the effect of adiponectin (APN) deficiency in the CD4(+)CD45RB(high) transfer model of colitis. Recombination activating gene (Rag)-1 knockout (KO) and Rag-1 APN KO mice receiving CD4(+)CD45RB(high) cells developed colitis of comparable severity. Colonic mRNA expression of IL-6 and IL-17 was lower in Rag-1 APN KO mice compared to Rag-1 KO mice. Rag-1 APN KO and Rag-1 KO mice released comparable amounts of IL-6 from colon cultures, whereas release of IL-17 was higher in Rag-1 APN KO compared to Rag-1 KO mice. Expression of TNFalpha mRNA was comparable in Rag-1 KO and Rag-1 APN KO mice, but protein release was lower in Rag-1 APN KO mice compared to Rag-1 KO mice. Levels of IFNgamma and IL-10 at mRNA and protein were comparable in Rag-1 KO and Rag-1 APN KO mice. Higher mRNA expression of VCAM-1 was observed in the colon of healthy APN KO compared to WT mice, while induction of colitis resulted in a comparable increase in VCAM-1 expression in Rag-1 KO and Rag-1 APN KO mice. In conclusion, although APN regulates expression of cytokines and adhesion molecules in the colon, this does not result in alteration of overall colitis severity in the CD4(+)CD45RB(high) transfer model.

Voluntary exercise training in mice increases the expression of antioxidant enzymes and decreases the expression of TNF-alpha in intestinal lymphocytes

Acute exercise in mice induces intestinal lymphocyte (IL) apoptosis. Freewheel running reduces apoptosis and forced exercise training increases splenocyte antioxidant levels. The purpose of this study was to examine the effect of freewheel running and acute exercise on mouse IL numbers and concentrations of apoptosis and antioxidant proteins and pro-inflammatory cytokines in IL. Female C57BL/6 mice had access to in-cage running wheels (RW) or cages without wheels (NRW) for 16 weeks and were randomized at the end of training to no exercise control (TC) or to treadmill exercise with sacrifice after 90 min of running (TREAD; 30 min, 22 m min(-1); 30 min, 25 m min(-1); 30 min, 28 m min(-1); 2 degrees slope). IL were analyzed for pro-(caspase 3 and 7) and anti-(Bcl-2) apoptotic proteins, endogenous antioxidants (glutathione peroxidase: GPx; catalase: CAT) and the pro-inflammatory cytokine, TNF-alpha. RW mice had higher cytochrome oxidase (p<0.001) and citrate synthase (p<0.01) activities in plantaris and soleus muscles and higher GPx and CAT expression in IL (p<0.05) (indicative of training) compared with NRW mice. TNF-alpha expression was lower (p<0.05) and IL numbers higher (p<0.05) in RW vs. NRW mice. No training effect was observed for apoptotic protein expression, although TREAD resulted in higher caspase and lower Bcl-2. These results suggest that freewheel running in mice for 16 weeks enhances antioxidant and reduces TNF-alpha expression in IL but does not reduce pro-apoptotic protein expression after acute exercise. Results are discussed in terms of implications for inflammatory bowel diseases where apoptotic proteins and TNF-alpha levels are elevated.

Repeated exercise in mice alters expression of IL-10 and TNF-alpha in intestinal lymphocytes

Intestinal inflammation is characterized by mucosal damage that may arise, in part, to imbalances in pro- and anti-inflammatory cytokines. The purpose of this study was to describe the effects of repeated bouts of strenuous exercise on cytokine expression in mouse intestinal lymphocytes (IL). Thirty-four female C57BL/6 mice were randomly assigned to three groups: three repeated bouts of treadmill running separated by 24h followed by sacrifice immediately or after a 24h period or a sedentary (no exercise) control. The pro-inflammatory cytokine, TNF-alpha, and the anti-inflammatory cytokine, IL-10, were measured in IL by Western blotting. IL-10 concentration increased by 48% (p<0.05) in the immediate group compared to the sedentary control. TNF-alpha levels in mouse IL were significantly lower 24h after completion of the exercise protocol compared to the immediate group (p<0.05). The results suggest a possible physiological compensation in which intestinal lymphocytes increase the expression of IL-10 in response to exercise-induced stress.

The correlation between proinflammatory cytokines, MAdCAM-1 and cellular infiltration in the inflamed colon from TNF-alpha gene knockout mice

Tumour necrosis factor (TNF) is important in the development of inflammatory bowel disease. TNF-alpha-deficient mice show more severe colonic inflammation than wild-type (Wt) mice, but the underlying mechanism remains unclear. Using immunohistochemistry, enzyme-linked-immunosorbent assay and histopathology, we found that there was a higher level of macrophage infiltration in TNF-alpha(-/-) compared to Wt mice. This is consistent with higher levels of monocyte chemotactic protein-1, interleukin (IL)-6 and granulocyte monocyte colony-stimulating factor (GM-CSF) in the inflamed colon from the TNF-alpha(-/-) mice, compared to the Wt mice, following dextran sulphate sodium (DSS) challenge. There was close correlation between clinical observations and histopathological findings in both Wt and TNF-alpha(-/-) mice. The expression of mucosal addressin cell adhesion molecule 1 (MAdCAM-1) was upregulated in the colon of Wt and TNF-alpha(-/-) mice following DSS challenge. Interestingly, the induction of MAdCAM-1 was relatively lower in the inflamed colon of TNF-alpha(-/-) mice, despite the higher inflammatory cell infiltrate, compared to their Wt counterparts. On the other hand, TNF-alpha(-/-) mice had significantly lower baseline levels of colonic IL-4, IL-6 and GM-CSF. Furthermore, there was a reduction of both immunoglobulin A (IgA) and IgG in the gut from TNF-alpha(-/-) mice following DSS challenge. These data indicate that TNF-alpha deficiency alters homoeostasis of the colonic chemokine/cytokine environment and humoral immune response, resulting in an exacerbation of acute DSS-induced colitis in TNF-alpha(-/-) mice. These findings support the idea that TNF-alpha plays a role in the acute stage of intestinal inflammation.

Mast cells in allergy: Innate instructors of adaptive responses

The function of mast cells as effector cells in allergy has been extensively studied. However, increasing insight into mast cell physiology has revealed new mast cell functions and has introduced mast cells as key players in the regulation of innate as well as adaptive immunity. For example, mast cells have recently been found to express Toll-like receptors (TLRs), which enable them to participate in the innate immune response against pathogens. Furthermore, mast cells have been reported to interact with B cells, dendritic cells and T cells and thereby modulate the direction of an adaptive immune response. Finally, recent documentation that mast cells express functional MHC class II and costimulatory molecules and release immunologically active exosomes, has raised the possibility that mast cells also engage in (as yet) poorly understood antigen presentation functions. In this review, we explore the hypothesis that mast cells serve as central mediators between innate and adaptive immunity, rather as pure effector cells, during allergic innate responses.

Role of TNF-alpha in muscularis inflammation and motility disorder in a TNBS-induced colitis model: clues from TNF-alpha-deficient mice

Macroscopic and histological analysis revealed that the colonic inflammation induced by 2,4,6-trinitrobenzenesulphonic acid (TNBS) was of lower grade in tumour necrosis factor-alpha (TNF-alpha)(-/-) mice than in wild-type mice. Myeloperoxidase activity, an indicator of neutrophilic infiltration, was also low in both the mucosal and smooth muscle layer of the TNF-alpha(-/-) mouse colon. After the induction of inflammation with TNBS, the levels of proinflammatory cytokines, such as TNF-alpha, interleukin-1beta and interleukin-6, were elevated both in the inflamed mucosa and muscle layers in the wild-type mice; however, the productions of these cytokines were greatly reduced in the TNF-alpha(-/-) mouse colon. The contractions of isolated colonic smooth muscle strips induced by several stimulatory agents were significantly decreased after treatment with TNBS in wild-type mice; however, these contractions were scarcely affected in TNF-alpha(-/-) mice. Finally, using the organ culture method, we found that TNF-alpha directly (independent of mucosal inflammation) disturbs the smooth muscle function. These results suggest that TNF-alpha plays an essential role not only in mucosal inflammation but also in muscularis inflammation in the colon of mice with TNBS-induced colitis, and that TNF-alpha directly induces motor dysfunctions by acting on the smooth muscle.

Proinflammatory CD4+CD45RBhi Lymphocytes Promote Mammary and Intestinal Carcinogenesis in ApcMin/+ Mice

Cancers of breast and bowel are increasingly frequent in humans. Chronic inflammation is known to be a risk factor for these malignancies, yet cellular and molecular mechanisms linking inflammation and carcinogenesis remain poorly understood. Here, we apply a widely used T-cell transfer paradigm, involving adoptive transfer of proinflammatory CD4+ CD45RB(hi) (T(E)) cells to induce inflammatory bowel disease (IBD) in mice, to investigate roles of inflammation on carcinogenesis in the Apc(Min/+) mouse model of intestinal polyposis. We find that transfer of T(E) cells significantly increases adenoma multiplicity and features of malignancy in recipient Apc(Min/+) mice. Surprisingly, we find that female Apc(Min/+) recipients of T(E) cells also rapidly develop mammary tumors. Both intestinal polyposis and mammary adenocarcinoma are abolished by cotransfer of anti-inflammatory CD4+ CD45RB(lo) regulatory lymphocytes or by neutralization of key proinflammatory cytokine tumor necrosis factor-alpha. Lastly, down-regulation of cyclooxygenase-2 and c-Myc expression is observed coincident with tumor regression. These findings define a novel mouse model of inflammation-driven mammary carcinoma and suggest that epithelial carcinogenesis can be mitigated by anti-inflammatory cells and cytokines known to regulate IBD in humans and mice.

Mucosal integrity and barrier function in the pathogenesis of early lesions in Crohn's disease

Crohn's disease aetiology is multifactorial and remains enigmatic. However, animal models show that disease heterogeneity is probable, in that more than one defective mucosal mechanism can produce the same clinical phenotype. For example, Crohn's-like lesions are reported after compromise of mucosal integrity per se in the presence of an intact immune system, through altered expression of mucosal adhesion molecules, such as cadherins and tight junction proteins, highlighting the importance of the mucosal barrier in the disease process. Key to mucosal damage is the trigger of an inflammatory cascade after luminal antigen processing, a role classically ascribed to M cells in the surface follicle associated epithelium. Direct luminal antigen sampling has recently been proposed, however, by extension of dendritic cell (DC) processes through the intact gut epithelium, and it follows that early mucosal damage could result from de novo lymphoid recruitment. Cytokines, such as tumour necrosis factor alpha (TNFalpha), are known to drive inflammation, but emerging data suggest additional important roles for TNFalpha influencing mucosal barrier efficacy by altering adhesion molecule expression, influencing epithelial apoptosis, and affecting tight junction functionality.

Long-Term Exposure of the HT-29 Human Intestinal Epithelial Cell Line to TNF Causes Sustained Up-Regulation of the Polymeric Ig Receptor and Proinflammatory Genes through Transcriptional and Posttranscriptional Mechanisms

Transport of IgA Abs across intestinal epithelial cells into gut secretions is mediated by the polymeric Ig receptor (pIgR). The cytokine TNF plays a central role in initiating and amplifying inflammatory reactions, and is implicated in the pathogenesis of inflammatory bowel diseases. Acute exposure of intestinal epithelial cell lines to TNF has been shown to up-regulate transcription of genes encoding pIgR and a number of proinflammatory factors, but the effects of chronic exposure to TNF have not been studied. We found that exposure of HT-29 human colon carcinoma cells to TNF for up to 20 days reduced the rate of cell proliferation, but did not cause gross morphological changes. Expression of mRNA encoding pIgR and several proinflammatory genes increased acutely, and then diminished but remained elevated above control levels throughout the experiment. Changes in gene expression were paralleled by increased expression of the transcription factors IFN regulatory factor-1 and the RelB subunit of NF-kappaB. HT-29 cells activated the endogenous TNF gene in response to TNF treatment, but the level of TNF production was insufficient to maintain pIgR and proinflammatory gene expression after withdrawal of exogenous TNF. Chronic exposure to TNF caused a marked increase in pIgR mRNA stability and a small but significant decrease in TNF mRNA stability, but no change in the half-lives of IL-8, c-Myc, and GAPDH. In summary, we observed different effects of acute vs chronic exposure to TNF on gene expression, and found evidence for transcriptional and posttranscriptional regulation of expression of the pIgR.

Transmembrane tumor necrosis factor is a potent inducer of colitis even in the absence of its secreted form

BACKGROUND & AIMS

Tumor necrosis factor (TNF) is cleaved proteolytically from a 26-kilodalton transmembrane precursor protein into secreted 17-kilodalton monomers. Transmembrane (tm) and secreted trimeric TNF are biologically active and may mediate distinct activities. We assessed the consequences of a complete inhibition of TNF processing on the course of colitis in recombination activating gene (RAG)2 -/- mice on transfer of CD4 CD45RB hi T cells.

METHODS

TNF -/- mice, transgenic for a noncleavable mutant TNF gene, were used as donors of CD4 T cells, and, on a RAG2 -/- background, also as recipients. Kinetics of disease development were compared in the absence of TNF, in the absence of secreted TNF, and in the presence of secreted and tmTNF. The analysis at the end of the observation period included the histopathologic assessment of the intestine and the localization of TNF and interferon gamma (IFNgamma)-expressing cells.

RESULTS

The complete prevention of TNF secretion in tmTNF transgenic RAG2 -/- mice neither prevented nor delayed disease induction by transferred transgenic for a noncleavable transmembrane mutant of mouse TNF (tmTNF tg) CD4 CD45RB hi T cells. tmTNF expression by transferred CD4 T cells, however, was not required for disease induction because severe colitis and weight loss also were observed in tmTNF RAG2 -/- recipients of TNF -/- CD4 CD45RB hi T cells. In the presence of tmTNF, the absence of secreted TNF did not affect frequency and distribution of TNF and interferon-gamma messenger RNA (mRNA)-expressing cells.

CONCLUSIONS

These results indicate that specific inhibitors of TNF processing are not appropriate for modulating the pro-inflammatory and disease-inducing effects of TNF in chronic inflammatory disorders of the intestine.

Crohn's disease: future anti-tumor necrosis factor therapies beyond infliximab

The dramatic benefit experienced by many Crohn's disease patients treated with the anti-tumor necrosis factor-alpha (TNF-alpha) antibody infliximab underscores the centrality of this cytokine in the pathogenesis of Crohn's disease and the potential use of the therapeutic strategy of blocking TNF-alpha in this disease. In the hopes of emulating and improving on the success of infliximab, numerous strategies are being devised and studied to inhibit the actions of TNF-alpha. This article focuses on those agents, other than infliximab, which target TNF-alpha to treat inflammatory bowel disease as their central mechanism of action.

Tumor necrosis factor (TNF)-mediated neuroprotection against glutamate-induced excitotoxicity is enhanced by N-methyl-D-aspartate receptor activation. Essential role of a TNF receptor 2-mediated phosphatidylinositol 3-kinase-dependent NF-kappa B pathway

We have previously shown that two tumor necrosis factor (TNF) receptors (TNFR) exhibit antagonistic functions during neurodegenerative processes in vivo with TNFR1 aggravating and TNFR2 reducing neuronal cell loss, respectively. To elucidate the neuroprotective signaling pathways of TNFR2, we investigated glutamate-induced excitotoxicity in primary cortical neurons. TNF-expressing neurons from TNF-transgenic mice were found to be strongly protected from glutamate-induced apoptosis. Neurons from wild type and TNFR1(-/-) mice prestimulated with TNF or agonistic TNFR2-specific antibodies were also resistant to excitotoxicity, whereas TNFR2(-/-) neurons died upon glutamate and/or TNF exposures. Both protein kinase B/Akt and nuclear factor-kappa B (NF-kappa B) activation were apparent upon TNF treatment. Both TNFR1 and TNFR2 induced the NF-kappa B pathway, yet with distinguishable kinetics and upstream activating components, TNFR1 only induced transient NF-kappa B activation, whereas TNFR2 facilitated long term phosphatidylinositol 3-kinase-dependent NF-kappa B activation strictly. Glutamate-induced triggering of the ionotropic N-methyl-D-aspartate receptor was required for the enhanced and persistent phosphatidylinositol 3-kinase-dependent NF-kappa B activation by TNFR2, indicating a positive cooperation of TNF and neurotransmitter-induced signal pathways. TNFR2-induced persistent NF-kappa B activity was essential for neuronal survival. Thus, the duration of NF-kappa B activation is a critical determinant for sensitivity toward excitotoxic stress and is dependent on a differential upstream signal pathway usage of the two TNFRs.

Infliximab for refractory ulcerative colitis or indeterminate colitis: an open-label multicentre study

BACKGROUND

The efficacy of infliximab in ulcerative colitis (UC) and indeterminate colitis has been poorly assessed and preliminary results are conflicting.

METHODS

The records of 30 patients treated with infliximab for ulcerative colitis (n=19) or indeterminate colitis (n=11) were reviewed. Infliximab was given because of steroid resistance (n=18), dependence (n=5) or intolerance (n=7); five patients had failed on cyclosporin; 19 patients had a severe flare-up.

RESULTS

Median duration of follow-up was 10 months. In 28 patients with active disease, the response rate was 75% at day 7, with 43% having a complete remission, and 50% at month 1, with 32% having a complete remission. Among the 22 responders, the probability of relapse was 73% at month 6. The probability of complete remission without steroids, taking into account the re-treatment for relapse (n=11), was 57% (95% confidence interval (CI): 45% to 69%) at month 6. The probability of colectomy was 33% (95% CI: 23% to 43%) at month 12. In indeterminate colitis, response rate was only 50% at day 7 and 30% at month 1. Concomitant use of antimetabolite agents was associated with better results.

CONCLUSIONS

Infliximab was able to induce a rapid response in some patients with UC or indeterminate colitis refractory to conventional treatment. Long-term results were less favourable, with frequent relapses, and about one-third of the patients required a colectomy.

The t-SNARE syntaxin 4 is regulated during macrophage activation to function in membrane traffic and cytokine secretion

Activation of macrophages with lipopolysaccharide (LPS) induces the rapid synthesis and secretion of proinflammatory cytokines, such as tumor necrosis factor (TNFalpha), for priming the immune response. TNFalpha plays a key role in inflammatory disease; yet, little is known of the intracellular trafficking events leading to its secretion. In order to identify molecules involved in this secretory pathway, we asked whether any of the known trafficking proteins are regulated by LPS. We found that the levels of SNARE proteins were rapidly and significantly up- or downregulated during macrophage activation. A subset of t-SNAREs (Syntaxin 4/SNAP23/Munc18c) known to control regulated exocytosis in other cell types was substantially increased by LPS in a temporal pattern coinciding with peak TNFalpha secretion. Syntaxin 4 formed a complex with Munc18c at the cell surface of macrophages. Functional studies involving the introduction of Syntaxin 4 cDNA or peptides into macrophages implicate this t-SNARE in a rate-limiting step of TNFalpha secretion and in membrane ruffling during macrophage activation. We conclude that, in macrophages, SNAREs are regulated in order to accommodate the rapid onset of cytokine secretion and for membrane traffic associated with the phenotypic changes of immune activation. This represents a novel regulatory role for SNAREs in regulated secretion and in macrophage-mediated host defense.