Integrating anti-tumor necrosis factor therapy in inflammatory bowel disease: current and future perspectives

Matrix Metalloproteinase-9 (MMP-9) induced disruption of intestinal epithelial tight junction barrier is mediated by NF-κB activation

BACKGROUND

Matrix Metalloproteinase-9 (MMP-9) has been shown to play a key role in mediating inflammation and tissue damage in inflammatory bowel disease (IBD). In patients with IBD, the intestinal tight junction (TJ) barrier is compromised as characterized by an increase in intestinal permeability. MMP-9 is elevated in intestinal tissue, serum and stool of patients with IBD. Previous studies from our laboratory showed that MMP-9 causes an increase in intestinal epithelial TJ permeability and that the MMP-9 induced increase in intestinal permeability is an important pathogenic factor contributing to the development of intestinal inflammation in IBD. However, the intracellular mechanisms that mediate the MMP-9 modulation of intestinal barrier function remain unclear.

AIMS

The main aim of this study was to further elucidate the molecular mechanisms involved in MMP-9 induced increase in intestinal epithelial TJ permeability using Caco-2 monolayers as an in-vitro model system.

RESULTS

MMP-9 induced increase in Caco-2 TJ permeability was associated with activation and cytoplasmic-to-nuclear translocation of NF-κB p65. Knocking-down NF-κB p65 by siRNA transfection prevented the MMP-9 induced expression of the NF-κB target gene IL-8, myosin light chain kinase (MLCK) protein expression, and subsequently prevented the increase in Caco-2 TJ permeability. In addition, the effect of MMP-9 on Caco-2 intestinal epithelial TJ barrier function was not mediated by apoptosis or necrosis.

CONCLUSION

Our data show that the MMP-9 induced disruption of Caco-2 intestinal epithelial TJ barrier function is regulated by NF-κB pathway activation of MLCK.

Immunomodulation in Heart Failure with Preserved Ejection Fraction: Current State and Future Perspectives

The heart failure (HF) epidemic is growing and approximately half of the HF patients have heart failure with preserved ejection fraction (HFpEF). HFpEF is a heterogeneous syndrome, characterized by a preserved left ventricular ejection fraction (LVEF ≥ 50%) with diastolic dysfunction, and is associated with high morbidity and mortality. Underlying comorbidities of HFpEF, i.e., hypertension, type 2 diabetes mellitus, obesity, and renal failure, lead to a systemic pro-inflammatory state, thereby affecting normal cardiac function. Increased inflammatory biomarkers predict incident HFpEF and are higher in patients with HFpEF as compared with heart failure with reduced ejection fraction (HFrEF). Randomized trials in HFpEF patients using traditional HF medication failed to demonstrate a clear benefit on hard endpoints (mortality and/or HF hospitalization). Therefore, therapies targeting underlying comorbidities and systemic inflammation in early HFpEF may provide better opportunities. Here, we provide an overview of the current state and future perspectives of immunomodulatory therapies for HFpEF.

The Immunological Basis of Inflammatory Bowel Disease

Inflammatory bowel diseases (IBDs) are chronic ailments, Crohn's disease and ulcerative colitis being the most important. These diseases present an inflammatory profile and they differ according to pathophysiology, the affected area in the gastrointestinal tract, and the depth of the inflammation in the intestinal wall. The immune characteristics of IBD arise from abnormal responses of the innate and adaptive immune system. The number of Th17 cells increases in the peripheral blood of IBD patients, while Treg cells decrease, suggesting that the Th17/Treg proportion plays an important role in the development and maintenance of inflammation. The purpose of this review was to determine the current state of knowledge on the immunological basis of IBD. Many studies have shown the need for further explanation of the development and maintenance of the inflammatory process.

Assessing patient preferences for treatment options and process of care in inflammatory bowel disease: a critical review of quantitative data

Inflammatory bowel disease (IBD), consisting of both Crohn's disease (CD) and ulcerative colitis (UC), are chronic inflammatory conditions of the intestinal tract. As there is no cure for either CD or UC, patients with these conditions face numerous treatment decisions regarding their disease. The aim of this review is to evaluate literature regarding quantitative studies of patient preferences in therapy for IBD with a focus on the emerging technique of stated preference and its application in IBD. Numerous simple survey-based studies have been performed evaluating IBD patients' preferences for medication frequency, mode of delivery, potential adverse events, etc., as well as variations in these preferences. These studies are limited, however, as they are purely descriptive in nature with limited quantitative information on the relative value of treatment alternatives. Time trade-off and standard-gamble studies have also been utilized to quantify patient utility for various treatment options or outcomes. However, these types of studies suffer from inaccurate assumptions regarding patient choice behavior. Stated preference is an emerging robust methodology increasingly utilized in health care that can determine the relative utility for a therapy option as well as its specific attributes (such as efficacy or adverse side effects). Stated preference techniques have begun to be applied in IBD and offer an innovative way of examining the numerous therapy options these patients and their providers face.

Adverse events of tumor necrosis factor inhibitors

BACKGROUND/AIMS

Adverse events in anti-TNF treatment can be divided into allergic reactions with an acute and delayed onset, infectious complications in relation to the underlying disease, and without. Last but not least, there is the unresolved question of tumor induction and propagation. All of these may account for morbidity and eventually mortality.

METHODS

Literature-based review to update current knowledge about safety and adverse events of TNF blockers.

RESULTS

Major drawbacks are infectious complications with the use of anti-TNF-α antibodies. The risk is increased in inflammatory bowel disease in general and in the perioperative setting of Crohn's disease patients. The number of tuberculosis cases has decreased since meticulous testing prior to treatment start is mandatory. An excess mortality that has been reported from referral centers is neither documented in randomized controlled trials nor in real-life settings. Regarding malignancies, lymphoma and skin cancer are a concern. The incidence of lymphoma may be raised, but this has also been debated with the use of thiopurines. Skin cancer, especially melanoma, is more common in inflammatory bowel disease and may be associated with the use of biologics. Overall, most studies do not address the influence of active inflammation or co-administration of other drugs. Hence, the risk attributable to TNF blockers alone is currently ill-defined.

CONCLUSION

Treatment with anti-TNF-α antibodies is an option with substantial risks. Most problems can be prevented by thorough workup of the patient.

Impact of probiotics on toll-like receptor 4 expression in an experimental model of ulcerative colitis

Toll-like receptors (TLRs) are key components of the innate immune system which trigger antimicrobial host defense responses. This study aimed to investigate the impact of probiotics (Lactobacillus, Bifidobacterium) on the expression of TLR4 and tumor necrosis factor-alpha (TNF-α) in the colon mucosa of rat experimental ulcerative colitis model induced by trinitrobenzene sulfonic acid (TNBS)/ethanol and immune complexes. The gross and histological changes of the colonic mucosa were observed and assessed by the means-standard deviation and independent samples t-test. The protein expression levels of TLR4 and TNF-α were detected by using immunohistochemistry and Western blotting, respectively. It was revealed that there was visible infiltration of inflammatory cells, formation of crypt abscess, and the reduction of goblet cells in the colon tissue of experimental models. As compared with the control group, the levels of TLR4 and TNF-α protein were significantly increased in the model group (P<0.01 for both). No significant difference was found in the expression of TLR4 and TNF-α between the two-week probiotics treatment group and the model group (P>0.05), whereas significant reductions were shown in rats which were treated with probiotics for four weeks as compared with the model group (P<0.01). There was no significant difference between two probiotics-treated groups. Our results implied that probiotics were likely to play a key role in protecting ulcerative colitis by reducing the inflammatory factor TNF-α expression through inhibiting the TLR4 expression in the colon tissue of experimental models.

Opposite role of tumor necrosis factor receptors in dextran sulfate sodium-induced colitis in mice

Tumor necrosis factor-α (TNF-α) is a key factor for the pathogenesis of inflammatory bowel diseases (IBD), whose function is known to be mediated by TNF receptor 1 (TNFR1) or 2. However, the precise role of the two receptors in IBD remains poorly understood. Herein, acute colitis was induced by dextran sulfate sodium (DSS) instillation in TNFR1 or 2−/− mice. TNFR1 ablation led to exacerbation of signs of colitis, including more weight loss, increased mortality, colon shortening and oedema, severe intestinal damage, and higher levels of myeloperoxidase compared to wild-type counterparts. While, TNFR2 deficiency had opposite effects. This discrepancy was reflected by alteration of proinflammatory cytokine and chemokine production in the colons. Importantly, TNFR1 ablation rendered enhanced apoptosis of colonic epithelial cells and TNFR2 deficiency conferred pro-apoptotic effects of lamina propria (LP)-immune cells, as shown by the decreased ratio of Bcl-2/Bax and enhanced nuclear factor (NF)-κB activity.

Amelioration of dextran sodium sulfate-induced colitis in mice by Rhodobacter sphaeroides extract

Bacteria can produce some compounds in response to their environment. These compounds are widely used in cosmetic and pharmaceutical applications. Some probiotics have immunomodulatory activities and modulate the symptoms of several diseases. Autoimmune diseases represent a complex group of conditions that are thought to be mediated through the development of autoreactive immunoresponses. Inflammatory bowel disease (IBD) is common autoimmune disease that affects many individuals worldwide. Previously, we found that the extracts of Rhodobacter sphaeroides (Lycogen) inhibited nitric oxide production and inducible nitric-oxide synthase expression in activated macrophages. In this study, the effect of Lycogen™, a potent anti-inflammatory agent, was evaluated in mice with dextran sodium sulfate (DSS)-induced colitis. Oral administration of Lycogen™ reduced the expressions of proinflammatory cytokines (tumor necrosis factor-α and interleukin-1β) in female BABL/c mice. In addition, the increased number of bacterial flora in the colon induced by DSS was amelirated by Lycogen™. The histological score of intestinal inflammation in 5% DSS-treated mice after oral administration of Lycogen™ was lower than that of control mice. Meanwhile, Lycogen™ dramatically prolonged the survival of mice with severe colitis. These findings identified that Lycogen™ is an anti-inflammatory agent with the capacity to ameliorate DSS-induced colitis.

Ultrasound-based molecular imaging and specific gene delivery to mesenteric vasculature by endothelial adhesion molecule targeted microbubbles in a mouse model of Crohn's disease

Crohn's disease (CD) is a chronic inflammatory disorder of the gastrointestinal tract (GI) for which treatments with immunosuppressive drugs have significant side-effects. Consequently, there is a clinical need for site-specific and non-toxic delivery of therapeutic genes or drugs for CD and related disorders such as inflammatory bowel disease. The aim of this study was to validate a gene delivery platform based on ultrasound-activated lipid-shelled microbubbles (MBs) targeted to inflamed mesenteric endothelium in the CD-like TNFΔARE mouse model. MBs bearing luciferase plasmid were functionalized with antibodies to MAdCAM-1 (MB-M) or VCAM-1 (MB-V), biomarkers of gut endothelial cell inflammation and evaluated in an in vitro flow chamber assay with appropriate ligands to confirm targeting specificity. Following MB retro-orbital injection in TNFΔARE mice, the mean contrast intensity in the ileocecal region from accumulated MB-M and MB-V was 8.5-fold and 3.6-fold greater, respectively, compared to MB-C. Delivery of luciferase plasmid to the GI tract in TNFΔARE mice was achieved by insonating the endothelial cell-bound agents using a commercial sonoporator. Luciferase expression in the midgut was detected 48 h later by bioluminescence imaging and further confirmed by immunohistochemical staining. The liver, spleen, heart, and kidney had no detectable bioluminescence following insonation. Transfection of the microcirculation guided by a targeted, acoustically-activated platform such as an ultrasound contrast agent microbubble has the potential to be a minimally-invasive treatment strategy to ameliorate CD and other inflammatory conditions.

Insights into the role of progranulin in immunity, infection, and inflammation

PGRN, a pleiotrophic growth factor, is known to play an important role in the maintenance and regulation of the homeostatic dynamics of normal tissue development, proliferation, regeneration, and the host-defense response and therefore, has been widely studied in the fields of infectious diseases, wound healing, tumorigenesis, and neuroproliferative and degenerative diseases. PGRN has also emerged as a multifaceted immune-regulatory molecule through regulating the signaling pathways known to be critical for immunology, especially TNF/TNFR signaling. In this review, we start with updates about the interplays of PGRN with ECM proteins, proteolytic enzymes, inflammatory cytokines, and cell-surface receptors, as well as various pathophysiological processes involved. We then review the data supporting an emerging role of PGRN in the fields of the "Cubic of I", namely, immunity, infection, and inflammation, with special focus on its regulation of autoimmune syndromes. We conclude with insights into the immunomodulating, anti-inflammatory, therapeutic potential of PGRN in treating diseases with an inflammatory etiology in a vast range of medical specialties.

Antioxidative potential of a combined therapy of anti TNFα and Zn acetate in experimental colitis

AIM: To evaluate whether combination therapy with anti-tumour necrosis factor α (TNFα) antibody and Zn acetate is beneficial in dextran sodium sulphate (DSS) colitis.

METHODS: Colitis was induced in CD1-Swiss mice with 5% DSS for 7 d. The experimental mice were then randomised into the following subgroups: standard diet + DSS treated (induced colitis group); standard diet + DSS + subcutaneous 25 μg anti-TNFα treated group; Zn acetate treated group + DSS + subcutaneous 25 μg anti-TNFα; standard diet + DSS + subcutaneous 6.25 μg anti-TNFα treated group and Zn acetate treated group + DSS + subcutaneous 6.25 μg anti-TNFα. Each group of mice was matched with a similar group of sham control animals. Macroscopic and histological features were scored blindly. Homogenates of the colonic mucosa were assessed for myeloperoxidase activity as a biochemical marker of inflammation and DNA adducts (8OH-dG) as a measure of oxidative damage.

RESULTS: DSS produced submucosal erosions, ulcers, inflammatory cell infiltration and cryptic abscesses which were reduced in both groups of mice receiving either anti-TNFα alone or combined with zinc. The effect was more pronounced in the latter group (vs Zn diet, P < 0.02). Myeloperoxidase activity (vs controls, P < 0.02) and DNA adducts, greatly elevated in the DSS fed colitis group (vs controls, P < 0.05), were significantly reduced in the treated groups, with a more remarkable effect in the group receiving combined therapy (vs standard diet, P < 0.04).

CONCLUSION: DSS induces colonic inflammation which is modulated by the administration of anti-TNFα. Combining anti-TNFα with Zn acetate offers marginal benefit in colitis severity.

Colitogenic role of tumour necrosis factor (TNF) receptors in trinitrobenzene sulphonic acid colitis: TNF-R1 ablation does not affect systemic inflammatory response

Tumour necrosis factor (TNF)-α plays a critical role in the pathogenesis of T helper type 1-mediated colitis such as Crohn's disease. However, the roles of its two receptors in mediating pathology remain largely unknown. In this study, trinitrobenzene sulphonic acid (TNBS) was used to induce colitis in TNF-receptor single or double knock-out (DKO) BALB/c mice and in wild-type counterparts. TNF-R1(-/-) mice had significantly less weight loss, reduced mortality, colon shortening and oedema, colon histological damage and lower levels of colon myeloperoxidase compared with wild-type (WT) BALB/c mice. A similar manifestation was also observed in TNF-R2(-/-) and TNF-R1(-/-) TNF-R2(-/-) (TNF-R DKO) mice. Strikingly, systemic inflammatory response (including splenomegaly and monocyte expansion) was found in WT and TNF-R1(-/-) mice after TNBS, instead of TNF-R2(-/-) and TNF-R DKO mice. Attenuated pathology of colitis in TNF-R1(-/-) or TNF-R2(-/-) mice correlated with lower amounts of interleukin (IL)-6, IL-1β, monocyte chemotactic protein (MCP)-1, IL-12p70 and interferon (IFN)-γ production in the colons. Importantly, ablation of TNF-R1 or TNF-R2 reduced the number of terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate nick end-labelling (TUNEL)-positive apoptotic epithelial cells in the affected colons compared with WT TNBS-instilled controls, which might be due to the heightened ratio of Bcl-2/Bax and reduced activity of nuclear factor (NF)-κB. These findings suggest that either TNF-R1 or TNF-R2 plays a pathogenic role in the pathology of colitis and TNF signalling via TNF-R1 or TNF-R2 alone is not sufficient for inducing mucosal damage.

Inflammatory bowel disease: review from the aspect of genetics

Regardless of how inflammatory bowel disease (IBD) is defined, the term "genetic susceptibility" is always included. Due to substantial progress in the characterization of susceptible genes that interact with environmental influences, a number of review articles offering the latest insights continue to be presented. To date, more than 30 novel IBD susceptible loci have been found, while several promising associations between IBD and gene variants have also been identified and replicated effectively. The present review highlights recent insights regarding linkage analysis and genome-wide association presented in studies of IBD susceptible genes, which provide additional evidence supporting their involvement in disease pathogenesis, based on linking to innate immune systems as a result of interactions with intestinal microbial flora. An improved understanding of IBD genetics will promote the identification of novel therapeutic agents, making it possible to identify environmental factors related to intestinal inflammation.

Adalimumab in ulcerative colitis: Two cases of mucosal healing and clinical response at two years

Infliximab (IFX) is currently the only biologic therapy used in the treatment of moderate-to-severe ulcerative colitis (UC). In the years to come, more biologic therapies will have a role in the management of moderate-to-severe UC. We report on two patients with steroid-dependent UC who, due to adverse reactions to IFX, have been under therapy with adalimumab for two years. Both patients received concomitant immunosuppressive treatment. Long term clinical remission and mucosal healing are described.

Human tumour necrosis factor: physiological and pathological roles in placenta and endometrium

The cytokine tumour necrosis factor alpha (TNF) is a well known member of the TNF superfamily consisting of at least 18 ligands and 29 different receptors involved in numerous cellular processes. TNF signals through two distinct receptors TNFR1 and TNFR2 thereby controlling expression of cytokines, immune receptors, proteases, growth factors and cell cycle genes which in turn regulate inflammation, survival, apoptosis, cell migration, proliferation and differentiation. Since expression of TNF was discovered in amnion and placenta many studies demonstrated the presence of the cytokine and its receptors in the diverse human reproductive tissues. Whereas TNF has been implicated in ovulation, corpus luteum formation and luteolysis, this review focuses on the functions of TNF in human placental, endometrial and decidual cell types of normal tissues and also discusses its role in endometrial and gestational diseases. Physiological levels of the cytokine could be important for balancing cell fusion and apoptotic shedding of villous trophoblasts and to limit trophoblast invasion into maternal decidua. Regulation of the TNF/TNFR system by steroid hormones also suggests a role in uterine function including menstrual cycle-dependent destruction and regeneration of endometrial tissue. Aberrant levels of TNF, however, are associated with diverse reproductive diseases such as amniotic infections, recurrent spontaneous abortions, preeclampsia, preterm labour or endometriosis. Hence, concentrations, receptor distribution and length of stimulation determine whether TNF has beneficial or adverse effects on female reproduction and pregnancy.

Melatonin reduces bacterial translocation and apoptosis in trinitrobenzene sulphonic acid-induced colitis of rats

AIM: To investigate the effects of exogenous melatonin on bacterial translocation and apoptosis in a rat ulcerative colitis model.

METHODS: Rats were randomly assigned to three groups: groupI: control, group II: experimental colitis, group III: colitis plus melatonin treatment. On d 11 after colitis, plasma tumor necrosis factor-α, portal blood endotoxin levels, colon tissue myeloperoxidase and caspase-3 activity were measured. Bacterial translocation was quantified by blood, lymph node, liver and spleen culture.

RESULTS: We observed a significantly reduced incidence of bacterial translocation to the liver, spleen, mesenteric lymph nodes, portal and systemic blood in animals treated with melatonin. Treatment with melatonin significantly decreased the caspase-3 activity in colonic tissues compared to that in trinitrobenzene sulphonic acid- treated rats (16.11 ± 2.46 vs 32.97 ± 3.91, P < 0.01).

CONCLUSION: Melatonin has a protective effect on bacterial translocation and apoptosis.

Metabolic Inactivation of Resolvin E1 and Stabilization of Its Anti-inflammatory Actions

The resolvins (Rv) are lipid mediators derived from omega-3 polyunsaturated fatty acids that act within a local inflammatory milieu to stop leukocyte recruitment and promote resolution. Resolvin E1 (RvE1; (5S,12R,18R)-trihydroxy-6Z,8E,10E,14Z,16E-eicosapentaenoic acid) is an oxygenase product derived from omega-3 eicosapentaenoic acid that displays potent anti-inflammation/pro-resolution actions in vivo. Here, we determined whether oxidoreductase enzymes catalyze the conversion of RvE1 and assessed the biological activity of the RvE1 metabolite. With NAD+ as a cofactor, recombinant 15-hydroxyprostaglandin dehydrogenase acted as an 18-hydroxyl dehydrogenase to form 18-oxo-RvE1. In the murine lung, dehydrogenation of the hydroxyl group at carbon 18 position to form 18-oxo-RvE1 represented the major initial metabolic route for RvE1. At a concentration where RvE1 potently reduced polymorphonuclear leukocyte (PMN) recruitment in zymosan-induced peritonitis, 18-oxo-RvE1 was devoid of activity. In human neutrophils, carbon 20 hydroxylation of RvE1 was the main route of conversion. An RvE1 analog, i.e. 19-(p-fluorophenoxy)-RvE1, was synthesized that resisted rapid metabolic inactivation and proved to retain biological activity reducing PMN infiltration and pro-inflammatory cytokine/chemokine production in vivo. These results established the structure of a novel RvE1 initial metabolite, indicating that conversion of RvE1 to the oxo product represents a mode of RvE1 inactivation. Moreover, the designed RvE1 analog, which resisted further metabolism/inactivation, could be a useful tool to evaluate the actions of RvE1 in complex disease models.

Autoantibody profile during short-term infliximab treatment for Crohn's disease: a prospective cohort study

BACKGROUND

The potential clinical implications of autoimmunity during treatment with infliximab are unclear.

AIM

To determine the frequency and correlation of autoantibody formation in patients with Crohn's disease treated with infliximab in a routine clinical setting.

METHODS

Sixty-three patients with refractory/inflammatory (31) and/or fistulising Crohn's disease (32), received an infliximab infusion at a dose 5 mg/kg in weeks 0, 2 and 6, and were evaluated for the development of antinuclear, anti-double-stranded DNA, anti-Sm, anti-RNP, anti-SSA, anti-SSB and antihistone antibodies. The correlates with pharmacological treatments, the response to infliximab and adverse events were evaluated.

RESULTS

Antinuclear antibodies were found in five of the 63 patients (8%) at baseline and in 26 (42%) after 10 weeks (P < 0.001). Of the 26 antinuclear antibody-positive patients who were further subtyped, nine of 63 (17%) had anti-double-stranded DNA (P = 0.003), and 1.5% were extractable nuclear antigen (ENA) and antihistone-positive. Five patients were initially positive for anticardiolipin antibodies and two more patients became positive during infliximab treatment. New autoantibody formation was more frequent in the patients with inflammatory/refractory disease than in those with fistulising disease (17 vs. 7; P = 0.02). One patient developed drug-induced lupus without major organ damage.

CONCLUSIONS

Autoantibody formation occurs in 42% of patients (8% of these patients were positive before infliximab treatment) with Crohn's disease receiving induction treatment with infliximab, but the clinical significance of this remains to be determined.

Resolvin E1, an endogenous lipid mediator derived from omega-3 eicosapentaenoic acid, protects against 2,4,6-trinitrobenzene sulfonic acid-induced colitis

Resolvin E1 (RvE1; 5S,12R,18R-trihydroxyeicosapentaenoic acid) is an antiinflammatory lipid mediator derived from omega-3 fatty acid eicosapentaenoic acid (EPA). At the local site of inflammation, aspirin treatment enhances EPA conversion to 18R-oxygenated products, including RvE1, which carry potent antiinflammatory signals. Here, we obtained evidence for reduced leukocyte infiltration in a mouse peritonitis model, where the administration of EPA and aspirin initiated the generation of RvE1 in the exudates. Similar results were obtained with the administration of synthetic RvE1, which blocked leukocyte infiltration. RvE1 also protected against the development of 2,4,6-trinitrobenzene sulfonic acid-induced colitis. The beneficial effect was reflected by increased survival rates, sustained body weight, improvement of histologic scores, reduced serum anti-2,4,6-trinitrobenzene sulfonic acid IgG, decreased leukocyte infiltration, and proinflammatory gene expression, including IL-12 p40, TNF-alpha, and inducible nitric oxide synthase. Thus, the endogenous lipid mediator RvE1 counter-regulates leukocyte-mediated tissue injury and proinflammatory gene expression. These findings show an endogenous mechanism that may underlie the beneficial actions of omega-3 EPA and provide targeted approaches for the treatment of intestinal inflammation.

Biologic Therapy for Inflammatory Bowel Disease

Despite all of the advances in our understanding of the pathophysiology of inflammatory bowel disease (IBD), we still do not know its cause. Some of the most recently available data are discussed in this review; however, this field is changing rapidly and it is increasingly becoming accepted that immunogenetics play an important role in the predisposition, modulation and perpetuation of IBD. The role of intestinal milieu, and enteric flora in particular, appears to be of greater significance than previously thought. This complex interplay of genetic, microbial and environmental factors culminates in a sustained activation of the mucosal immune and non-immune response, probably facilitated by defects in the intestinal epithelial barrier and mucosal immune system, resulting in active inflammation and tissue destruction. Under normal situations, the intestinal mucosa is in a state of 'controlled' inflammation regulated by a delicate balance of proinflammatory (tumour necrosis factor [TNF]-alpha, interferon [IFN]-gamma, interleukin [IL]-1, IL-6, IL-12) and anti-inflammatory cytokines (IL-4, IL-10, IL-11). The mucosal immune system is the central effector of intestinal inflammation and injury, with cytokines playing a central role in modulating inflammation. Cytokines may, therefore, be a logical target for IBD therapy using specific cytokine inhibitors. Biotechnology agents targeted against TNF, leukocyte adhesion, T-helper cell (T(h))-1 polarisation, T-cell activation or nuclear factor (NF)-kappaB, and other miscellaneous therapies are being evaluated as potential therapies for IBD. In this context, infliximab is currently the only biologic agent approved for the treatment of inflammatory and fistulising Crohn's disease. Other anti-TNF biologic agents have emerged, including CDP 571, certolizumab pegol (CDP 870), etanercept, onercept and adalimumab. However, ongoing research continues to generate new biologic agents targeted at specific pathogenic mechanisms involved in the inflammatory process. Lymphocyte-endothelial interactions mediated by adhesion molecules are important in leukocyte migration and recruitment to sites of inflammation, and selective blockade of these adhesion molecules is a novel and promising strategy to treat Crohn's disease. Therapeutic agents that inhibit leukocyte trafficking include natalizumab, MLN-02 and alicaforsen (ISIS 2302). Other agents being investigated for the treatment of Crohn's disease include inhibitors of T-cell activation, peroxisome proliferator-activated receptors, proinflammatory cytokine receptors and T(h)1 polarisation, and growth hormone and growth factors. Agents being investigated for treatment of ulcerative colitis include many of those mentioned for Crohn's disease. More controlled clinical trials are currently being conducted, exploring the safety and efficacy of old and new biologic agents, and the search certainly will open new and exciting perspectives on the development of therapies for IBD.

Discovery and structure-activity relationship of coumarin derivatives as TNF-alpha inhibitors

The discovery and structure-activity relationship of a novel series of coumarin-based TNF-alpha inhibitors is described. Starting from the initial lead 1a, various derivatives were prepared surrounding the coumarin core structure to optimize the in vitro inhibitory activity of TNF-alpha production by human peripheral blood mononuclear cells (hPBMC), stimulated by bacterial lipopolysaccharide (LPS). Selected compounds also demonstrated in vivo inhibition of TNF-alpha production in rats.

PDE4 inhibition: a novel approach for the treatment of inflammatory bowel disease

Inflammation is a hallmark of inflammatory bowel disease (IBD), and elevation of cAMP levels can inhibit the pro-inflammatory and tissue-destructive properties of leukocytes. Phosphodiesterase 4 (PDE4) is the predominant enzyme that metabolizes cAMP in inflammatory cells, and the anti-inflammatory and immunomodulatory potential of PDE4 inhibitors in human leukocytes, endothelium and epithelium is well documented. Although PDE4 inhibitors have been investigated as treatments for several inflammatory diseases, this has focused mainly on asthma and chronic obstructive disease (COPD). Historically, their clinical utility has been limited by nausea and emesis. However, the PDE4 inhibitors cilomilast and roflumilast have recently shown efficacy in asthma and COPD, with a reduced propensity to cause nausea and emesis. In this review, we summarize for the first time the evidence that PDE4 inhibitors might have therapeutic benefit in IBD, and discuss mechanisms of action beyond the inhibition of inflammatory cells.

Selective inhibition of tumor necrosis factor-alpha prevents nucleus pulposus-induced histologic changes in the dorsal root ganglion

STUDY DESIGN

The possibility to prevent nucleus pulposus-induced structural changes of the dorsal root ganglion (DRG) by selective tumor necrosis factor-alpha (TNF-alpha) inhibition was assessed in an experimental model in the rat spine.

OBJECTIVES

To evaluate the role of TNF-alpha in the mediation of nucleus pulposus-induced structural changes by using selective inhibition and to confirm the effect of TNF-alpha inhibitor at the point of histologic findings.

SUMMARY OF BACKGROUND DATA

TNF-alpha is known to be released from the nucleus pulposus, and has been suggested to play a key role in chemical damage of the adjacent nerve tissue. The TNF-alpha inhibitor prevents the reduction of nerve conduction velocity and may limit the nerve fiber injury, intracapillary thrombus formation, and intraneural edema formation caused by nucleus pulposus. However, there is no report on the effect of the inhibitor regarding histologic findings and the appearance of the TNF-alpha in the DRG exposed to nucleus pulposus.

METHODS

1) Rats were treated with an intraperitoneal injection of infliximab. Nucleus pulposus from the disc was obtained 1, 3, 7, 14, and 21 days after the injection. The TNF-alpha-positive cells were observed using immunohistochemistry. 2) Disc herniation of the nucleus pulposus was made on the L4-L5 disc in rats. Two groups were treated with selective TNF-alpha inhibitor 1 day before or 3 hours after surgery. The other group received no TNF-alpha inhibitor. The L4 DRG was resected 1, 3, 7, 14, and 21 days after surgery. The specimens were processed for hematoxylin and eosin staining and immunohistochemistry using rabbit antisera to TNF-alpha. The histologic findings and TNF-alpha-positive cells were observed by light microscopy.

RESULTS

1) While positively stained immunoreactive TNF-alpha appeared between 7 and 21 days, no immunoreactive TNF-alpha was observed 1 and 3 days after injection in the nucleus pulposus. 2) The histologic changes of the DRG caused by nucleus pulposus were smaller in the infliximab treatment group than those in the nontreatment group. The number of immunoreactive TNF-alpha cells was high 1 and 3 days after surgery in the DRGs of disc herniation rats that were treated without an injection of the inhibitor, low on day 7 and 14, and very low on day 21 after surgery. No immunoreactive TNF-alpha was observed in the DRGs of the TNF-alpha inhibitor treatment groups on day 1, 3, and 21 after surgery. Weakly stained cells were sometimes observed in rats at day 7 and 14 after surgery.

CONCLUSIONS

Infliximab may prevent the histologic damage induced by nucleus pulposus. When rats were given a single intraperitoneal injection of infliximab at the beginning of disc herniation, the histologic damage seemed to be reduced in comparison with the nontreated rats.

Astroglial-derived lymphotoxin-? exacerbates inflammation and demyelination, but not remyelination

Tumor necrosis factoralpha (TNFalpha) and lymphotoxin-alpha (Ltalpha) are upregulated in and around multiple sclerosis plaques and are proposed to play a role during chronic inflammation in demyelinating disease. Despite the perceived detrimental role of these cytokines, human clinical trials inhibiting TNFalpha signaling has led to worsening of symptoms in multiple sclerosis (MS) patients. Our laboratory has verified a role for TNFalpha in the exacerbation of demyelination but, more importantly, has demonstrated a novel role for TNFalpha in reparative remyelination in a cuprizone-induced demyelination model. This may explain the worsening of symptoms experienced by MS patients. In view of the cross-talk in TNF family signaling, the aim of this study is to understand the role of Ltalpha in demyelination and remyelination in hopes of improving therapeutic strategies for MS. Using the same model, we show that mice lacking Ltalpha exhibit a delay in demyelination that is greater than that exhibited by TNFalpha null mice. In this model, Ltalpha is expressed primarily by astroglia. The delay in demyelination is accompanied by a delay in the loss of mature GSTpi-positive oligodendrocytes in Ltalpha-/- mice compared with wild-type mice. Ltalpha-/- mice have decreased numbers of microglia at the site of insult during demyelination, although the number of astrocytes present is similar between strains. In contrast to TNFalpha the lack of Ltalpha did not alter the time course of remyelination, or the number of mature oligodendrocytes during the remyelination phase. Since Ltalpha is detrimental in inflammation and demyelination, but not necessary for remyelination and repair, inhibiting Ltalpha signaling may represent a promising strategy to treat MS.

Protective effect of angelica sinensis polysaccharide on experimental immunological colon injury in rats

AIM: To study the effect of angelica sinensis polysaccharide (ASP) on immunological colon injury and its mechanisms in rats.

METHODS: Immunological colitis model of rats was induced by intracolon enema with 2, 4, 6-trinitrobenzene sulfonic acid (TNBS) and ethanol. The experimental animals were randomly divided into normal control, model control, 5-aminosalicylic acid therapy groups and three doses of ASP therapy groups. The 6 groups were treated intracolonically with normal saline, normal saline, 5-aminosalicylic acid (100 mg·kg^-1), and ASP daily (8: 00 am) at the doses of 200, 400 and 800 mg·kg^-1 respectively for 21 days 7 d following induction of colitis. The rat colon mucosa damage index (CMDI), the histopathological score (HS), the score of occult blood test (OBT), and the colonic MPO activity were evaluated. The levels of SOD, MDA, NO, TNF-α, IL-2 and IL-10 in colonic tissues were detected biochemically and immunoradiometrically. The expressions of TGF-β and EGF in colonic tissues were also determined immunochemically.

RESULTS: Enhanced colonic mucosal injury, inflammatory response and oxidative stress were observed in colitis rats, which manifested as significant increases of CMDI, HS, OBT, MPO activity, MDA and NO contents, as well as the levels of TNF-α and IL-2 in colonic tissues, although colonic TGF-β protein expression, SOD activity and IL-10 content were significantly decreased compared with the normal control (P < 0.01). However, these parameters were found to be significantly ameliorated in colitis rats treated intracolicly with ASP at the doses of 400 and 800 mg·kg^-1 (P < 0.05-0.01). Meantime, colonic EGF protein expression in colitis rats was remarkably up-regulated.

CONCLUSION: ASP has a protective effect on immunological colon injury induced by TNBS and ethanol enema in rats, which was propably due to the mechanism of antioxidation, immunomodulation and promotion of wound repair.

Basiliximab (anti-CD25) in combination with steroids may be an effective new treatment for steroid-resistant ulcerative colitis

BACKGROUND

Steroid resistance represents a major clinical problem in the treatment of ulcerative colitis. In vitro, interleukin-2 renders lymphocytes steroid resistant.

AIM

To explore the therapeutic potential of interleukin-2 receptor blockade in steroid-resistant ulcerative colitis with both in vitro measures and a pilot in vivo study.

METHODS

Ten patients with steroid-resistant ulcerative colitis received a single bolus of 40 mg of intravenous basiliximab plus steroid treatment in an open-label, uncontrolled, 24-week study. The outcome was assessed using the Ulcerative Colitis Symptom Score, rectal biopsy and Inflammatory Bowel Disease Questionnaire. Lymphocyte steroid sensitivity was measured in vitro in 39 subjects in the presence or absence of basiliximab.

RESULTS

Nine of the 10 patients achieved clinical remission within 8 weeks. At 24 weeks, seven patients were in clinical remission. Marked improvement in the Ulcerative Colitis Symptom Score was seen by 1 week (P = 0.004) and on rectal biopsy and Inflammatory Bowel Disease Questionnaire by 2 weeks (both P < 0.05). Improvements persisted to 24 weeks (Ulcerative Colitis Symptom Score, Inflammatory Bowel Disease Questionnaire, both P < 0.005). Eight of the nine responders relapsed (median, 9 weeks), but remission was re-achieved with further corticosteroids and the addition of azathioprine. At 24 weeks, seven patients were in full clinical remission, five off all steroid therapy. In vitro measurement of lymphocyte steroid sensitivity demonstrated steroid resistance in 22% of subjects. All were rendered steroid sensitive in the presence of basiliximab.

CONCLUSIONS

Basiliximab appears to be effective at inducing remission in steroid-resistant ulcerative colitis. In vitro, basiliximab also produced a dramatic increase in lymphocyte steroid sensitivity in healthy subjects. Confirmation in randomized controlled studies is required.

Therapeutic inhibition of tumour necrosis factor alpha in patients with heart failure: cooling an inflamed heart

Heart failure is a systemic disorder characterised by tissue hypoxia and secondary organ dysfunction which occurs in response to various myocardial insults that include ischaemia, viral infections, and toxins. In addition to maladaptive neurohumoral activation, heart failure is associated with an inflammatory state that appears to have a detrimental effect on cardiac function and prognosis. This has led to the suggestion that anti-inflammatory interventions may have therapeutic potential in the symptomatic and prognostic treatment of patients with heart failure. This review considers the role of inhibition of the cytokine tumour necrosis factor alpha in the treatment of heart failure.

Inflammation and infection in clinical stroke

Stroke has enormous clinical, social, and economic implications, and demands a significant effort from both basic and clinical science in the search for successful therapies. Atherosclerosis, the pathologic process underlying most coronary artery disease and the majority of ischemic stroke in humans, is an inflammatory process. Complex interactions occur between the classic risk factors for atherosclerosis and its clinical consequences. These interactions appear to involve inflammatory mechanisms both in the periphery and in the CNS. Central nervous system inflammation is important in the pathophysiologic processes occurring after the onset of cerebral ischemia in ischemic stroke, subarachnoid hemorrhage, and head injury. In addition, inflammation in the CNS or in the periphery may be a risk factor for the initial development of cerebral ischemia. Peripheral infection and inflammatory processes are likely to be important in this respect. Thus, it appears that inflammation may be important both before, in predisposing to a stroke, and afterwards, where it is important in the mechanisms of cerebral injury and repair. Inflammation is mediated by both molecular components, including cytokines, and cellular components, such as leukocytes and microglia, many of which possess pro- and/or antiinflammatory properties, with harmful or beneficial effects. Classic acute-phase reactants and body temperature are also modified in stroke, and may be useful in the prediction of events, outcome, and as therapeutic targets. New imaging techniques are important clinically because they facilitate dynamic evaluation of tissue damage in relation to outcome. Inflammatory conditions such as giant cell arteritis and systemic lupus erythematosus predispose to stroke, as do a range of acute and chronic infections, principally respiratory. Diverse mechanisms have been proposed to account for inflammation and infection-associated stroke, ranging from classic risk factors to disturbances of the immune and coagulation systems. Considerable opportunities therefore exist for the development of novel therapies. It seems likely that drugs currently used in the treatment of stroke, such as aspirin, statins, and modulators of the renin-angiotensin-aldosterone system, act at least partly via antiinflammatory mechanisms. Newer approaches have included antimicrobial and antileukocyte strategies. One of the most promising avenues may be the use of cytokine antagonism, for example, interleukin-1 receptor antagonist.

Inflammatory bowel disease: new insights into pathogenesis and treatment

Despite all the advances in our understanding of the pathophysiology of inflammatory bowel disease (IBD), we do not know the cause. Some of the most recently available data have been discussed here and yet it is now becoming increasingly accepted that immunogenetics play an important role in the predisposition, modulation, and perpetuation of IBD. The mucosal immune system is the central effector of intestinal inflammation and injury, with cytokines playing a central role in modulating inflammation. The role of intestinal milium, and enteric flora in particular, appears to be of greater significance than previously held. A review is made of the main areas of research exploring the mechanisms more intimately associated with the development of IBD, providing advances in the agents currently used, and identifying a host of new therapeutic agents potentially interacting with or interrupting specific targets in the genesis of IBD.

The efficacy of methotrexate for maintaining remission in inflammatory bowel disease

BACKGROUND

The management of patients with inflammatory bowel disease who are resistant to or intolerant of azathioprine remains a challenge. Low-dose methotrexate has been shown to be effective in inducing remission in Crohn's disease.

AIM

This review was conducted because there are limited long-term follow-up data during and after stopping treatment. There are also limited data on the use of methotrexate in ulcerative colitis.

METHODS

The study was a retrospective review of clinical notes. Remission was defined as minimal bowel symptoms without the need for oral steroids for 3 months. Relapse was defined as bowel symptoms that required steroid treatment or surgery.

RESULTS

Seventy patients were reviewed; 48 had Crohn's disease and 22 had ulcerative colitis. The mean duration of treatment was 17.1 months; the mean maintenance dose was 20 mg weekly. Remission was achieved in 34 of 55 patients who completed more than 3 months of treatment (62%). Life-table analysis showed that the chances of remaining in remission at 12, 24 and 36 months (if treatment was continued) were 90%, 73% and 51%, respectively. The chances of remaining in remission after stopping treatment at 6, 12 and 18 months were 42%, 21% and 16%, respectively. The dose of methotrexate (mg/kg) was associated with the induction of remission (P=0.02). Treatment was equally effective for Crohn's disease and ulcerative colitis.

CONCLUSIONS

Maintenance methotrexate treatment gives acceptable remission rates for treatment periods up to 3 years. After stopping treatment, relapse is frequent and occurs early (usually within 1 year).