Synergistic effect of immunoregulatory cytokines on peripheral blood monocytes from patients with inflammatory bowel disease

Down-regulation of the expression of cyclooxygenase-2 and prostaglandin E2 by interleukin-4 is mediated via a reduction in the expression of prostanoid EP4 receptors in HCA-7 human colon cancer cells

Chronic inflammatory bowel disease (IBD), which is characterized by prolonged inflammation of the gastrointestinal tract is associated with an increased risk of colorectal cancer. Recent studies revealed that the pathology of IBD is caused by hyperactivated immune responses mediated by differentiated CD4⁺ naïve helper T cells, such as Th1 and Th17 cells, but not Th2 cells. The human E-type prostanoid 4 (EP4) receptor and its pathways have also been implicated in and/or associated with the early developmental stages of colorectal cancer along with increases in the levels of prostaglandin E₂ (PGE₂) and cyclooxygenase-2 (COX-2), the hallmarks of colorectal carcinogenesis. In the present study, using an in silico analysis and pharmacological experiments, we demonstrated that interleukin (IL)-4, a signature cytokine of Th2 cells, down-regulated the expression of COX-2 and PGE₂ in the human colon cancer cell line, HCA-7. This result may be attributed to a reduction in the expression of prostanoid EP4 receptors through the induction of hypoxia inducible factor-1α via the interleukin-4 receptor-stimulated activation of signal transducer and activator of transcription 6. However, another major Th2 cytokine IL-13 had no effect on the expression of COX-2 or prostanoid EP4 receptors in HCA-7 cells. Therefore, instead of the hyperactivation of Th1/Th17 cells, the deactivation/down-regulation of Th2 cells followed by a decrease in the production of IL-4 in IBD may play a role in the cancerous transformation of cells, at least in prostanoid EP4 receptor-overactivated tumorigenesis.

Hippocampal TNF-α Signaling Mediates Heroin Withdrawal-Enhanced Fear Learning and Withdrawal-Induced Weight Loss

There is significant comorbidity of opioid use disorder (OUD) and post-traumatic stress disorder (PTSD) in clinical populations. However, the neurobiological mechanisms underlying the relationship between chronic opioid use and withdrawal and development of PTSD are poorly understood. Our previous work identified that chronic escalating heroin administration and withdrawal can produce enhanced fear learning, an animal model of hyperarousal, and is associated with an increase in dorsal hippocampal (DH) interleukin-1β (IL-1β). However, other cytokines, such as TNF-α, work synergistically with IL-1β and may have a role in the development of enhanced fear learning. Based on both translational rodent and clinical studies, TNF-α has been implicated in hyperarousal states of PTSD, and has an established role in hippocampal-dependent learning and memory. The first set of experiments tested the hypothesis that chronic heroin administration followed by withdrawal is capable of inducing alterations in DH TNF-α expression. The second set of experiments examined whether DH TNF-α expression is functionally relevant to the development of enhanced fear learning. We identified an increase of TNF-α immunoreactivity and positive cells at 0, 24, and 48 h into withdrawal in the dentate gyrus DH subregion. Interestingly, intra-DH infusions of etanercept (TNF-α inhibitor) 0, 24, and 48 h into heroin withdrawal prevented the development of enhanced fear learning and mitigated withdrawal-induced weight loss. Overall, these findings provide insight into the role of TNF-α in opioid withdrawal and the development of anxiety disorders such as PTSD.

Macrophage-polarizing stimuli differentially modulate the inflammatory profile induced by the secreted phospholipase A2 group IA in human lung macrophages

In this study we investigated the effects of snake venom Group IA secreted phospholipase A₂ (svGIA) on the release of inflammatory and angiogenic mediators from human lung macrophages (HLMs). HLMs were incubated with lipopolysaccharide (LPS) or svGIA with or without macrophage-polarizing stimuli (IL-4, IL-10, IFN-γ or the adenosine analogue NECA). M2-polarizing cytokines (IL-4 and IL-10) inhibited TNF-α, IL-6, IL-12, IL-1β, CXCL8 and CCL1 release induced by both LPS and svGIA. IL-4 inhibited also the release of IL-10. IFN-γ reduced IL-10 and IL-12 and increased CCL1 release by both the LPS and svGIA-stimulated HLMs, conversely IFN-γ reduced IL-1β only by svGIA-stimulated HLMs. In addition, IFNγ promoted TNF-α and IL-6 release from svGIA-stimulated HLMs to a greater extent than LPS. NECA inhibited TNF-α and IL-12 but promoted IL-10 release from LPS-stimulated HLMs according to the well-known effect of adenosine in down-regulating M1 activation. By contrast NECA reduced TNF-α, IL-10, CCL1 and IL-1β release from svGIA-activated HLM. IL-10 and NECA increased both LPS- and svGIA-induced vascular endothelial growth factor A (VEGF-A) release. By contrast, IL-10 reduced angiopoietin-1 (ANGPT1) production from activated HLMs. IFN-γ and IL-4 reduced VEGF-A and ANGPT1 release from both LPS- and svGIA-activated HLMs. Moreover, IL-10 inhibited LPS-induced ANGPT2 production. In conclusion, we demonstrated a fine-tuning modulation of svGIA-activated HLMs differentially exerted by the classical macrophage-polarizing cytokines.

Sialic Acid-Engineered IL4-10 Fusion Protein is Bioactive and Rapidly Cleared from the Circulation

PURPOSE

Modulating sialylation of therapeutic glycoproteins may be used to influence their clearance and systemic exposure. We studied the effect of low and high sialylated IL4-10 fusion protein (IL4-10 FP) on in vitro and in vivo bioactivity and evaluated the effect of differential sialylation on pharmacokinetic parameters.

METHODS

CHO cell lines producing low (IL4-10 FP lowSA) and high sialylated (IL4-10 FP highSA) fusion protein were generated. Bioactivity of the proteins was evaluated in an LPS-stimulated whole blood assay. Pharmacokinetics were studied in rats, analyzing plasma levels of IL4-10 FP upon intravenous injection. In vivo activity was assessed in an inflammatory pain mice model upon intrathecal injection.

RESULTS

IL4-10 FP lowSA and IL4-10 FP highSA had similar potency in vitro. The pharmacokinetics study showed a 4-fold higher initial systemic clearance of IL4-10 FP lowSA, whereas the calculated half-life of both IL4-10 FP lowSA and IL4-10 FP highSA was 20.7 min. Finally, both IL4-10 FP glycoforms inhibited persistent inflammatory pain in mice to the same extent.

CONCLUSIONS

Differential sialylation of IL4-10 fusion protein does not affect the in vitro and in vivo activity, but clearly results in a difference in systemic exposure. The rapid systemic clearance of low sialylated IL4-10 FP could be a favorable characteristic to minimize systemic exposure after administration in a local compartment.

Effector T Helper Cell Subsets in Inflammatory Bowel Diseases

The gastrointestinal tract is a site of high immune challenge, as it must maintain a delicate balance between tolerating luminal contents and generating an immune response toward pathogens. CD4⁺ T cells are key in mediating the host protective and homeostatic responses. Yet, CD4⁺ T cells are also known to be the main drivers of inflammatory bowel disease (IBD) when this balance is perturbed. Many subsets of CD4⁺ T cells have been identified as players in perpetuating chronic intestinal inflammation. Over the last few decades, understanding of how each subset of Th cells plays a role has dramatically increased. Simultaneously, this has allowed development of therapeutic innovation targeting specific molecules rather than broad immunosuppressive agents. Here, we review the emerging evidence of how each subset functions in promoting and sustaining the chronic inflammation that characterizes IBD.

Cytokine Networks and T-Cell Subsets in Inflammatory Bowel Diseases

Pathogenesis of the inflammatory bowel diseases (IBDs), such as ulcerative colitis (UC) and Crohn's disease (CD), involve proinflammatory changes within the microbiota, chronic immune-mediated inflammatory responses, and epithelial dysfunction. Converging data from genome-wide association studies, mouse models of IBD, and clinical trials indicate that cytokines are key effectors of both normal homeostasis and chronic inflammation in the gut. Yet many questions remain concerning the role of specific cytokines in different IBDs within distinct regions of the gut, and regarding cellular mechanisms of action. In this article, we review current and emerging concepts concerning the role of cytokines in IBD with a focus on immune regulation, T cell subsets, and potential clinical applications.

Cytokine Networks and T-Cell Subsets in Inflammatory Bowel Diseases

Pathogenesis of the inflammatory bowel diseases (IBDs), such as ulcerative colitis (UC) and Crohn's disease (CD), involve proinflammatory changes within the microbiota, chronic immune-mediated inflammatory responses, and epithelial dysfunction. Converging data from genome-wide association studies, mouse models of IBD, and clinical trials indicate that cytokines are key effectors of both normal homeostasis and chronic inflammation in the gut. Yet many questions remain concerning the role of specific cytokines in different IBDs within distinct regions of the gut, and regarding cellular mechanisms of action. In this article, we review current and emerging concepts concerning the role of cytokines in IBD with a focus on immune regulation, T cell subsets, and potential clinical applications.

Characterisation and expression analysis of B-cell activating factor (BAFF) in spiny dogfish (Squalus acanthias): cartilaginous fish BAFF has a unique extra exon that may impact receptor binding

B-cell activating factor (BAFF), also known as tumour necrosis factor (TNF) ligand superfamily member 13B, is an important immune regulator with critical roles in B-cell survival, proliferation, differentiation and immunoglobulin secretion. A BAFF gene has been cloned from spiny dogfish (Squalus acanthias) and its expression studied. The dogfish BAFF encodes for an anchored type-II transmembrane protein of 288 aa with a putative furin protease cleavage site and TNF family signature as seen in BAFFs from other species. The identity of dogfish BAFF has also been confirmed by conserved cysteine residues, and phylogenetic tree analysis. The dogfish BAFF gene has an extra exon not seen in teleost fish, birds and mammals that encodes for 29 aa and may impact on receptor binding. The dogfish BAFF is highly expressed in immune tissues, such as spleen, and is up-regulated by PWM in peripheral blood leucocytes, suggesting a potentially important role in the immune system.

All-trans retinoic acid down-regulates inflammatory responses by shifting the Treg/Th17 profile in human ulcerative and murine colitis

IBD is characterized by uncontrolled immune responses in inflamed mucosa, with dominance of IL-17-producing cells and deficiency of Treg cells. The aim of this study was to explore the effect and mechanisms of RA, the ligand of RARalpha, on immune responses in human and murine colitis. Colonic biopsies from patients with UC were cultured and treated with RA as the agonist of RARalpha or LE135 as the antagonist of RARalpha. Expressions of IL-17 and FOXP3 were detected by immunohistochemistry. Murine colitis was induced by intrarectal administration with TNBS at Day 1. Mice were then i.p.-treated with RA or LE135 daily for 7 days. Cytokine levels in the cultures of mouse LPMCs were measured. Expressions of FOXP3 and IL-17 in colon tissues or MLN were detected by immunohistological analysis. Body weight and colon inflammation were evaluated. RA treatment up-regulated FOXP3 expression and down-regulated IL-17 expression in colon biopsies of patients and in colon tissues and MLN of mice with colitis compared with controls. LPMCs from RA-treated mice produced lower levels of proinflammatory cytokines (TNF-alpha, IL-1beta, IL-17) but more regulatory cytokines (IL-10, TGF-beta) compared with that of untreated mice. LE135 showed the opposite effect of RA. Furthermore, RA ameliorated TNBS-induced colitis in a dose-dependent manner, as seen by improved body weight and colon inflammation. RA down-regulates colon inflammatory responses in patients with IBD in vitro and in murine colitis in vivo, representing a potential therapeutic approach in IBD treatment.

Modulation of inflammatory response via alpha2-adrenoceptor blockade in acute murine colitis

Inflammatory bowel disease (IBD) is characterized by heavy production of proinflammatory cytokines such as tumour necrosis factor (TNF)-alpha and interleukin (IL)-1beta. Interactions of the autonomic nervous system with local immune cells play an important role in the development of IBD, and the balance of autonomic nerve function is broken in IBD patients with sympathetic overactivity. However, the function of catecholamines in the progress of colitis is unclear. In this study, we examined the role of catecholamines via alpha2-adrenoreceptor in acute murine colitis. The expression of tyrosine hydroxylase (TH) and dopamine b-hydroxylase (DBH), two rate-limiting enzymes in catecholamine synthesis, was detected by immunohistochemistry in murine colitis. Murine colitis was induced by dextran sodium sulphate or trinitrobenzene sulphonic acid (TNBS), and the mice were administered RX821002 or UK14304, alpha2-adrenoceptor antagonists or agonists. Colitis was evaluated by clinical symptoms, myeloperoxidase assay, TNF-alpha and IL-1beta production and histology. Lamina propria mononuclear cells (LPMCs) from mice with TNBS colitis were cultured in the absence or presence of RX821002 or UK14304, and stimulated further by lipopolysaccharide. TH and DBH are induced in LPMCs of inflamed colon, the evidence of catecholamine synthesis during the process of colitis. RX821002 down-regulates the production of proinflammatory cytokines from LPMCs, while UK14304 leads to exacerbation of colitis. Together, our data show a critical role of catecholamines via alpha2-adrenoreceptors in the progress of acute colitis, and suggest that use of the alpha2-adrenoceptor antagonist represents a novel therapeutic approach for the management of colitis.

IL-6 and CCL2 levels in CSF are associated with the clinical course of MS: implications for their possible immunopathogenic roles

Biological markers would provide valuable tools for tracking disease activity, immunopathological processes or therapeutic efficacy in MS. In this study we analysed a panel of Th(1)/Th(2) cytokines and the chemokine CCL2 in serum and CSF from MS patients and healthy controls. Increased levels of IL-6 (p<0.05) and decreased levels of CCL2 (p<0.001), with the lowest levels during acute relapses, was found in CSF from patients with relapsing-remitting MS. CSF levels of CCL2 correlated with indices for intrathecal IgG production and the CSF level of the neurofilament light protein, a marker for axonal damage, indicating a immunopathogenic role for CCL2.

Intestinal interleukin-13 in pediatric inflammatory bowel disease patients

BACKGROUND

Interleukin-13 (IL-13) is a multifunctional cytokine whose net principle action is to diminish inflammatory responses. Dysregulation of IL-13 production has been proposed to contribute to intestinal inflammation in inflammatory bowel disease (IBD) patients. Previous studies implicate IL-13 in IBD pathogenesis; however, they fail to accurately reflect in vivo intestinal IL-13 production. We evaluate IL-13, IL-6, and IL-1beta elaborations from colonic organ cultures of pediatric IBD patients

METHODS

Endoscopic lamina propria biopsies or surgical specimens from pediatric patients with IBD were organ cultured and supernatants evaluated by enzyme-linked immunosorbent assay for IL-1beta, IL-6, and IL-13.

RESULTS

IL-13 concentrations were significantly reduced in ulcerative colitis (UC) patients when compared with normal controls (P = 0.002) and Crohn disease (CD) patients (P = 0.001). End-stage UC patients at colectomy had lower intestinal IL-13 production than all other UC patients (P = 0.002). No significant correlation was found between IL-13 concentration and histologic disease severity (P = 0.134).

CONCLUSIONS

Diminished intestinal IL-13 production is present in UC patients and wanes further with clinical disease progression. These findings suggest that UC patients may be differentiated from CD patients by intestinal IL-13 quantitation, and UC patients may benefit from IL-13 enhancing therapies.

Inhibitory effects of the new anti-inflammatory agent, IS-741, on spontaneous colitis in HLA-B27/beta2-microglobulin transgenic rats

BACKGROUND

A novel anti-inflammatory drug, IS-741, blocked the adhesion of inflammatory cells to microvascular endothelial cells both in vivo and in vitro. Transgenic rats expressing human leukocyte antigen (HLA)-B27 and human beta2-microglobulin (HLA-B27 rats) spontaneously develop chronic colitis, which resembles human inflammatory bowel disease. In the present study, the authors examined the efficacy of IS-741 against spontaneous colitis in HLA-B27 rats.

METHODS

The HLA-B 27 rats were divided in two groups after the development of colitis. IS-741 was dissolved in water and administered orally (10 mg/kg) once per day for 14 days.

RESULTS

The HLA-B27 rats treated with IS-741 remained healthy; the wet weight of the colon was significantly lower in the IS-741-treated group. Histological examinations revealed a marked infiltration of inflammatory cells into both the mucosa and the submucosa in the control HLA-B27 rats, but these changes were attenuated in the IS-741-treated group. The mucosal damage score was also significantly reduced by treatment with IS-741. IS-741 significantly reduced the mucosal myeloperoxidase activity and mucosal cytokine-induced neutrophil chemoattractant-1 levels. IS-741 also reduced CD3-positive T-cell infiltration.

CONCLUSION

IS-741 suppressed the spontaneous colitis that developed in HLA-B27 rats. Some of the actions of IS-741 may be associated with its inhibitory effects on the adhesion of neutrophils to endothelial cells. The findings from the present study suggest that IS-741 may be a useful new therapeutic agent for inflammatory bowel disease.

Evidence of Epstein-Barr virus infection in ulcerative colitis

BACKGROUND AND AIM

The aetiology of ulcerative colitis is still controversial, however, recent studies have emphasised the possible role of infectious agents or ingested substances and their breakdown products, which might activate immune-mediated mechanisms eventually leading to tissue damage. Aim of this investigation was to ascertain the occurrence and the potential role of Epstein-Barr virus infection in large bowel mucosa of ulcerative colitis patients.

PATIENTS AND METHODS

Twenty-three biopsies and six total colectomies from 17 patients were analysed for the expression of Epstein-Barr virus proteins and RNAs. Polymerase chain reaction experiments were also carried out to detect Epstein-Barr virus DNA. For comparison, ten biopsies from patients with Crohn's disease, ten biopsies from patients with different types of colitis, seven biopsies and five surgical margins of normal colonic mucosa from the small and large bowels were studied (controls).

RESULTS

Six biopsies and four colectomies from seven ulcerative colitis patients showed scattered lymphocytes expressing nuclear EBER 1-2 and harbouring polymerase chain reaction-amplifiable Epstein-Barr virus-DNA. In some cases, linear viral DNA (typical of lytic Epstein-Barr virus infection) was also found. Epithelial cells were invariably negative in all cases. All control tissues from non-ulcerative colitis patients were also invariably non-reactive.

CONCLUSION

Evidence of Epstein-Barr virus infection in the mucosal inflammatory cells of ulcerative colitis patients suggests a possible role of this virus in the chronicity of ulcerative colitis.

Activated self-MHC-reactive T cells have the cytokine phenotype of Th3/T regulatory cell 1 T cells

In the present study, we show that human self-MHC-reactive (autoreactive) T cell clones are functionally distinct from Ag-specific T cell clones. Self-MHC-reactive T cells exhibited helper function for B cell Ig production when cultured with non-T cells alone, and they exhibit suppressor function when cultured with PWM- or rCD40 ligand (rCD40L)-activated non-T cells, whereas tetanus toxoid (TT)-specific clones exhibited only helper function in the presence of TT with or without PWM or rCD40L. Addition of neutralizing Abs to the cultures showed that the suppression was mediated by TGF-beta but not by IL-10 or IFN-gamma. The self-MHC-reactive clones also inhibited proliferation of primary CD4+ T cells and TT-specific T cell clones, but in this case the inhibition was mediated by both IL-10 and TGF-beta. In further studies, the interactions between self-MHC-reactive T cell clones and non-T cells that led to suppressor cytokine production have been explored. We found that prestimulation of non-T cells for 8 h with PWM or for 48 h for rCD40L results in non-T cells capable of inducing self-MHC-reactive T cell to produce high levels of TGF-beta and IL-10. In addition, these prestimulation times coincided with peak induction of HLA-DR and costimulatory B7 molecule (especially CD86) expression on B cells. Finally, addition of CTLA-4/Fc or blocking F(ab')2 anti-CTLA-4 mAb, plus optimally stimulated non-T cells, to cultures of self-MHC-reactive clones inhibited the induction of TGF-beta but not IL-10 or IFN-gamma production. In summary, these studies show that activated self-MHC-reactive T cells have the cytokine phenotype of Th3 or T regulatory cell 1 and thus may be important regulatory cells that mediate oral and peripheral tolerance and prevent the development of autoimmunity.

Cultured human monocytes secrete fibronectin in response to activation by proinflammatory cytokines

We studied the effects of the cytokines IL-1alpha, IL-6, tumour necrosis factor-alpha (TNF-alpha), IL-4, IL-10, IL-13 and transforming growth factor-beta (TGF-beta) on fibronectin (FN) production by cultured-human monocytes. IL-1alpha, IL-6 and TNF-alpha all increased FN production, an indicator of monocyte activation. These cytokines increased FN production in a dose-dependent fashion, with a 4-h treatment being sufficient to measure FN production by radioimmunoassay. Conversely, IL-4, IL-10 and IL-13 strongly inhibited cytokine-induced FN production, while TGF-beta only partially inhibited FN production. The combination of suboptimal doses of cytokines (IL-1alpha + IL-6, IL-1alpha + TNF-alpha, IL-6 + TNF-alpha), which could not singly induce substantial amounts of FN, were able to induce FN production by cultured monocytes. Northern blot analysis with a cDNA specific for FN confirmed the expression of FN mRNA in cultured monocytes stimulated with a single cytokine or a combination of cytokines. Our data demonstrate that monocytes may not always require high concentrations of cytokines for activation in vitro, and that the synergistic or additive action of low levels of cytokines on monocyte activation may be sufficient to promote immune or inflammatory reactions. Our data also suggest that certain T cell cytokines may regulate monocyte activation.

Inflammatory Bowel Disease: Current Pharmacotherapy Issues

Inflammatory bowel disease (IBD) includes two idiopathic syndromes, ulcerative colitis and Crohn's disease. In ulcerative colitis, inflammation is limited to the colonic mucosa and submucosa. Crohn's disease may, however, involve the small intestine, all bowel wall layers, and the upper gastrointestinal tract. Because health-related quality of life is significantly impaired during active disease, pharmaceutical care. is important in patient management. Traditional therapy includes 5-aminosalicylates, corticosteroids, and antimicrobial therapy. In steroid-resistant active disease, immunosuppressants (cyclosporine, azathioprine, 6-mercaptopurine, methotrexate) have a role but possess significant toxicity profiles. Current research focuses on the role of inflammatory mediators in IBD. Investigational therapies include monoclonal antibodies to proinflammatory cytokines, inhibitory cytokines, and anti-CD4 monoclonal antibodies.

Interleukin-13 prevents diaphragm muscle deterioration in a septic animal model

The effects of an intravenous injection of Interleukin-13 (IL-13) after endotoxin administration on diaphragm muscle were studied using Wistar rats. Two treatment groups, a control (saline+endotoxin) group and an IL-13 (IL-13+endotoxin) group were studied. E. coli endotoxin (10 mg/kg) was injected intraperitoneally 5 minutes after saline or IL-13 (0.25 microg) injection. The force-frequency curves, twitch kinetics and fatigability were measured at 0 and 4 hours after endotoxin injection. The force-frequency curves and twitch tension in the control group were significantly lower at 4 hours than those at 0 hour due to endotoxin. On the other hand, IL-13 prevented the decrement of the force-frequency curves and twitch tension induced by endotoxin. Nicotinamide adenine dinucleotide phosphate (NADPH) diaphorase histochemistry showed positive staining at 4 hours due to endotoxin in the control group; however, IL-13 also blocked NADPH diaphorase staining at 4 hours. Furthermore, the positive muscle fibers detected by the NADPH diaphorase staining were classified as type I (slow twitch) muscle fibers by ATPase staining. We conclude that IL-13 prevents the deterioration of contraction induced by endotoxin by inhibiting nitric oxide production in the diaphragm muscle, mainly the type I muscle fibers.

Characterization of cytokine expression in the rectal mucosa of ulcerative colitis: correlation with disease activity

OBJECTIVE

Mucosal inflammation in ulcerative colitis (UC) is presumed to be regulated by Th2-like cytokines. The aim of this study was to characterize local expression of various cytokines mRNA.

METHODS

Total RNA was extracted from rectal biopsy specimens in 61 patients with UC, 18 inflammatory controls, and 16 noninflammatory controls. Reverse-transcription polymerase chain reaction (RT-PCR) was used to determine mRNA expression of interleukin (IL)-2, interferon (IFN)-gamma, IL-4, IL-10, IL-13, and IL-15.

RESULTS

Expression of IL-10 was more frequent in UC (75.4%) than in noninflammatory controls (37.5%, p < 0.01). IL-4 was more frequently positive in UC (41%) than in inflammatory controls (5.6%, p < 0.01) and in noninflammatory controls (6.3%, p < 0.01). Positive expressions of IL-4 (66.7% vs 20.6%, p < 0.01) and IL-13 (63.0% vs 29.4%, p < 0.01) were higher in active UC than in inactive UC. The positive rate of IL-2, interferon (IFN)-gamma, and IL-15 expression showed no difference among the groups divided by clinical, endoscopic, and histological grade of inflammation.

CONCLUSIONS

These findings suggest that in active UC, IL-4 is pivotal, in combination with other Th2-like cytokines. In contrast, Th1-like cytokines and IL-15 bear no definite relation to local inflammation of UC.

Cytokine-based therapies in inflammatory bowel disease

Cytokine-based therapy for inflammatory bowel disease (IBD) has significantly advanced in the last year. This review highlights some of the exciting progress that has occurred. The efficacy of anti-tumor necrosis factor (TNF) monoclonal antibody therapy in Crohn's disease has promoted further research and the development of other anti-TNF therapies, such as thalidomide, phosphodiesterase type IV inhibitors, and new-generation anti-TNF monoclonal antibodies. Current research is also focused on more proximal events in the inflammatory cascade to modify T-cell regulation and to decrease the production and activity of proinflammatory proteins, cytokines, and nuclear regulatory factors. Concurrently, the emerging role of interleukin (IL)-11, IL-12, and IL-18 in the perpetuation of chronic inflammation continues to stimulate much interest. All of these new advancements reveal an exciting future for IBD therapy.

Modulating insulin-release profile from pH/thermosensitive polymeric beads through polymer molecular weight

Stimuli-sensitive statistical terpolymers of N-isopropylacrylamide (NIPAAm) (temperature-sensitive), butyl methacrylate (BMA) and acrylic acid (AA) (pH-sensitive) of various molecular weight (MW) with NIPAAm/BMA/AA feed mol ratio of 85/5/10 were used to modulate release of insulin, a model protein drug, from pH/thermosensitive polymeric beads. Protein drug loading from an aqueous medium into the beads was achieved by preparing a 7 or 10% (w/v) polymer solution with 0.2% (w/v) insulin at low pH and below the lower critical solution temperature (LCST) of the polymer (pH 2.0 and 4 degrees C), and then dropping the solution into an oil bath above the LCST of the solution (35 degrees C). This loading procedure maintained protein stability while achieving high loading efficiency, between 90 and 95% in the beads. Insulin-release studies from beads prepared from terpolymers of the same composition but increasing MW were performed at pH 2.0 and 7.4, at 37 degrees C. It was observed that there was negligible loss of insulin at pH 2.0 from the beads, indicating no burst effect. At pH 7.4, insulin release was seen from all the beads and the release rate was a function of the MW of the polymer. The low MW polymeric beads eroded, dissolved and released most of the insulin within 2 h at pH 7.4 and 37 degrees C, the intermediate MW polymeric beads swelled slightly, dissolved and released most of the insulin within 4 h, whereas the high MW polymeric beads swelled slowly and gradually released the loaded insulin over a period of 8 h. Thus, the release of protein from the low MW polymeric beads is controlled by the rate of dissolution of the polymer, whereas the release from the high MW polymeric beads is controlled by swelling of the beads and drug diffusion. Studies using fluorescein-labeled insulin revealed that insulin was uniformly distributed in the beads regardless of polymer MW. The loaded and released insulin were fully bioactive. Based on the described results, the low MW polymeric beads may be used for immediate delivery of protein drugs in the duodenum, the intermediate MW polymeric beads may be used for lower small intestine targeting, while the high MW polymeric beads may be used to target protein drugs predominantly to the colon.

C-X-C and C-C chemokine expression and secretion by the human colonic epithelial cell line, HT-29: differential effect of T lymphocyte-derived cytokines

Differential chemokine production by colonic epithelial cells is thought to contribute to the characteristic increased infiltration of selected population of leukocytes cells in inflammatory bowel disease. We have previously demonstrated that IL-13 enhances IL-1alpha-induced IL-8 secretion by the colonic epithelial cell line HT-29. We have now explored the C-C chemokine expression and modulation in this system. The combination of TNF-alpha and IFN-gamma was the minimal stimulation required for regulated on activation, normal T cell expressed and secreted (RANTES) and monocyte chemoattractant protein (MCP-1) mRNA expression and secretion by HT-29 cells. The same stimulation induced a stronger IL-8 mRNA expression and secretion. Pretreatment with IL-13 or IL-4, reduced significantly the RANTES, and MCP-1, but not IL-8 mRNA expression and secretion. In contrast, IL-10 had no effect on either MCP-1, or RANTES, or IL-8 generation. Pretreatment of HT-29 cells with wortmannin suggested that the IL-13-induced inhibition of C-C chemokine expression is via activation of a wortmannin-sensitive phosphatidylinositol 3-kinase. These data demonstrate that colonic epithelial cell chemokine production can be differentially regulated by T cell-derived cytokines and suggest an interplay between epithelial cells and T lymphocytes potentially important in the intestinal inflammation.

The role of IL-10 in inflammatory bowel disease: "of mice and men"

Inflammatory bowel disease (IBD) is a generic term typically used to describe a group of idiopathic inflammatory intestinal conditions in humans that are generally divided into Crohn's disease and ulcerative colitis. Although the etiology of these diseases remains unknown, a number of rodent models of IBD have recently been identified, all sharing the concept that the development of chronic intestinal inflammation occurs as a consequence of alterations in the immune system that lead to a failure of normal immunoregulation in the intestine. On the basis of these models, it has been hypothesized that the development of IBD in humans may be related to a dysregulated immune response to normal flora in the gut. Immunodeficient scid mice injected with CD4+ CD45RB(high) T cells and mice deficient in interleukin (IL)-10 (IL-10-/-) are among the rodent models of IBD. In both models, there is inflammation and evidence of a Th1-like response in the large intestine, characterized by CD4+ T-cell and macrophage infiltrates, and elevated levels of interferon-gamma. Because IL-10 is an immunomodulatory cytokine that is capable of controlling Th1-like responses, the role of IL-10 was investigated in these models. IL-10 was shown to be important in regulating the development of intestinal inflammation in both models. These results provided key data that supported initiation of clinical trials evaluating the efficacy of IL-10 in patients with IBD.

Food allergy, coeliac disease and chronic inflammatory bowel disease in man

It is often stated that the gastrointestinal tract has a limited number of responses to pathogens. Entirely different agents can produce a similar histopathological reaction. However, the expression of the disease in man is very heterogeneous, it varies with the age of the subject and is to a certain extent genetically determined. For example, food allergy is frequent in childhood and not common in adulthood. The intestinal mucosa in the child with cows milk allergy shows a 'flat' mucosa, which may be indistinguishable of that observed in gluten sensitive enteropathy or coeliac disease. Subjects with other forms of food allergy may have a morphologically normal small intestinal mucosa, occasionally with increased IgE plasma cells and often only characterised by an increased intestinal permeability. An abnormal intestinal permeability is one of the hallmarks of an inflamed gut, however, subjects with a latent form of coeliac disease have an abnormal permeability only without overt signs of inflammation. Recently, it has become clear that what determines the characteristics of the intestinal inflammatory response is dependent on the cytokines involved during the response and this seems to be the same in the stomach, the small intestine and the colon. A so-called Th1 response, with an increased production of IFN-gamma, TNF-alpha and other pro-inflammatory cytokines, occurs in the stomach when infected by Helicobacter pylori, in the small intestine when the subject with coeliac disease consumes normal bread and during the active phases of Crohn's disease. A Th2 response is characteristic of the allergic subject and there is some evidence that it is the predominant response in subjects with ulcerative colitis. We still do not know the fine-tuning of the cytokine response but IL-12 appears to be a key cytokine in polarising the response to a Th1 type. More recently it has become clear that the intestinal mucosa has a unique subset of CD4+ T cells that secrete TGF-beta (Th3 cells) that provide help for IgA. These cells have downregulatory properties for Th1 cells and therefore play an important role in the active suppression of oral tolerance and IgE response. What determines that an individual develops one of these diseases? It is now clear that these different pathological entities are multifactorial. Different environmental factors and a complex genetic predisposition where more that one gene and more than one chromosome are involved. The extent and severity of the inflammatory response depends on the genetic diversity of the bacteria or the amount of the antigen on the one hand and on the genetic constitution of the host on the other. The abnormal immune response in the human gut is predominantly a Th1-like inflammatory response. This can be elicited by bacteria, peptides, possibly the bacterial flora and some viruses. The recent findings in the pathogenesis of the intestinal inflammatory response will probably alter the therapy of the future.

IL-4, IL-10 and IL-13 down-regulate monocyte-chemoattracting protein-1 (MCP-1) production in activated intestinal epithelial cells

Several studies have demonstrated that intestinal epithelial cells play a major role in the initiation and perpetuation of intestinal inflammation by secreting proinflammatory cytokines and chemokines. MCP-1 is suggested to be a chemokine that plays a major part during intestinal inflammation in inflammatory bowel disease (IBD). Immunoregulatory cytokines such as IL-4, IL-10 and IL-13 have been described to exert anti-inflammatory properties on various cell types. The aim of our study was to determine the effect of Th2 cytokines on the production of MCP-1 by activated intestinal epithelial cells. We examined Caco-2 cells as well as intestinal epithelial cells which were isolated from surgical specimens. Production of the chemokine MCP-1 was determined under stimulated and non-stimulated conditions. IL-4, IL-10 and IL-13 were added to stimulated epithelial cells under various culture conditions. Supernatants were analysed for cytokine concentrations using ELISAs. Under stimulation with physiological agents like IL-1beta or tumour necrosis factor-alpha (TNF-alpha), we observed markedly increased concentrations of MCP-1 in supernatants of Caco-2 cells and intestinal epithelial cells. IL-4, IL-10 and IL-13 all had the capacity to down-regulate the production of MCP-1 in Caco-2 cells as well as in freshly isolated epithelial cells. Caco-2 cells which were primed with Th2 cytokines 24 h before stimulation were subsequently decreased in their ability to be stimulated by IL-1beta or TNF-alpha for MCP-1 production. As MCP-1 has been shown to play a major role during intestinal inflammation, the in vitro suppression of MCP-1 in enterocytes suggests the in vivo use of regulatory cytokines in patients with active IBD.