Cytokines in inflammatory bowel disease

A Perspective Of Intestinal Immune-Microbiome Interactions In Alcohol-Associated Liver Disease

Uncovering the intricacies of the gut microbiome and how it interacts with the host immune system has opened up pathways in the search for the treatment of disease conditions. Alcohol-associated liver disease is a major cause of death worldwide. Research has shed light on the breakdown of the protective gut barriers, translocation of gut microbes to the liver and inflammatory immune response to microbes all contributing to alcohol-associated liver disease. This knowledge has opened up avenues for alternative therapies to alleviate alcohol-associated liver disease based on the interaction of the commensal gut microbiome as a key player in the regulation of the immune response. This review describes the relevance of the intestinal immune system, the gut microbiota, and specialized and non-specialized intestinal cells in the regulation of intestinal homeostasis. It also reflects how these components are altered during alcohol-associated liver disease and discusses new approaches for potential future therapies in alcohol-associated liver disease.

Soluble interleukin-2 receptors in ulcerative colitis

T-Cell activation results in the release or shedding of a soluble form (45 kDa) of the cellular (55 kDa) low-affinity interleukin-2 receptor (α-chain) (slL-2R). The present study was performed to investigate if the serum concentration of sIL-2R is a marker of disease activity in patients with ulcerative colitis (UC), a chronic inflammatory bowel disease. Twenty-seven UC patients (about half of them in remission) and 13 healthy volunteers were studied, sIL-2R concentrations were measured by an enzyme-linked immunosorbent assay, and significantly elevated median sIL-2R values were found in clinically active UC (150 pg/ml; range 100–420), compared to inactive UC (145 pg/ml; range 110–255), and healthy controls (110 pg/ml; range 80–165) (p < 0.01). There was no correlation between sIL-2R concentrations and extent of the disease. Due to the overlap of serum sIL-2R concentrations between different disease stages and controls, the general diagnostic value seems to be limited. However, since slL-2R release is an IL-2 dependent phenomenon, we conclude that the demonstration of increased serum sIL-2R concentrations in UC suggests the existence of an enhanced T-cell activation in vivo in this disease. Further longitudinal studies are required to elucidate if repeated measurements of sIL-2R levels provide an additional way of monitoring UC disease activity in individual patients.

Effect of Etiasa on the expression of matrix metalloproteinase-2 and tumor necrosis factor-α in a rat model of ulcerative colitis

The aim of this study was to determine the disease activity index (DAI) and the colonic mucosa damage index (CMDI), and to detect the colonic mucosal expression levels of matrix metalloproteinase-2 (MMP-2) and tumor necrosis factor-α (TNF-α) in rats with ulcerative colitis (UC). We also aimed to investigate the protective role of Etiasa in UC. Sprague Dawley (SD) rats were randomly divided into three groups: the control, an Etiasa-treated group and a UC model group. Rats were sacrificed on days 14, 21, 35 or 56 following the administration of treatment by enema and the DAI, CMDI and colonic expression levels of MMP-2 and TNF-α were assessed. In the UC model group, the DAI and CDMI scores and the colonic expression levels of MMP-2 and TNF-α increased significantly compared with the control at all timepoints, and were also significantly higher than those in the Etiasa-treated group. In conclusion, the expression levels of MMP-2 and TNF-α increased significantly in rats with UC. Etiasa reduces colonic mucosal damage by downregulating the expression of MMP-2 and TNF-α.

Mast cell tryptase in sera of patients with Crohn's disease and mastocytosis

INTRODUCTION

The pathogenesis of Crohn's disease is unclear, but an abnormal immune response seems to play an important role. This study investigated whether serum tryptase could be shown in Crohn's disease as a marker of disease.

MATERIALS AND METHODS

Mast cell tryptase was detected in sera of 48 patients with active Crohn's disease, 31 patients with inactive Crohn's disease, 17 patients with mastocytosis, and 50 controls. Tryptase detection was carried out by UniCap System. Tryptase levels are given as U/l x m2 body surface area to overcome variations of body weight, height, etc. between malnourished and normal persons.

RESULTS

Serum tryptase levels (U/l x m2 body surface area) of controls were 2.4+/-1.0, of patients with Crohn's disease 2.5+/-2.0. In contrast, serum tryptase values were significantly increased in untreated patients with mastocytosis (21.19+/-18.55).

DISCUSSION

Mast cell tryptase is not elevated in sera of Crohn's disease. It might thus be speculated that this highly mast cell associated mediator might only contribute to local symptoms of Crohn's disease such as diarrhea, abdominal pain, etc., but not to its systemic inflammatory effects (Th 1 cytokine pattern). Tryptase may be well used for the screening of patients with mastocytosis.

Dextran sulfate sodium enhances interleukin-1 beta release via activation of p38 MAPK and ERK1/2 pathways in murine peritoneal macrophages

Interleukin (IL)-1 beta is a pro-inflammatory cytokine that has been shown to play a pivotal role in the onset of inflammatory bowel disease (IBD), however, the molecular mechanisms underlying the production of IL-1 beta in IBD are not fully understood. We investigated dextran sulfate sodium (DSS)-induced IL-1 beta production and caspase-1 activities in murine peritoneal macrophages (pM phi). Further, the activation status of p38 mitogen-activated protein kinase (MAPK), extracellular signal-regulated kinase 1/2 (ERK1/2), and c-Jun NH(2)-terminal kinase (JNK1/2), as well as their upstream target kinases, were examined by Western blotting. In addition, mRNA expression was assessed by RT-PCR and CXC chemokine ligand 16 (CXCL16) protein was detected by immunocytochemistry. DSS-treated pM phi released IL-1 beta protein in a time-dependent manner without affecting mRNA levels during 3-24 h, and caspase-1 activity peaked at 5 min (29-fold). IL-1 beta release and caspase-1 activity induced by DSS were significantly inhibited by a MAPK kinase 1/2 inhibitor, a p38 MAPK inhibitor, and NAC, however, not by JNK1/2 or a protein kinase C inhibitor. In addition, DSS strikingly induced the phosphorylation of p38 MAPK and ERK1/2 within 2 and 10 min, respectively. DSS also induced intracellular generation of reactive oxygen species (ROS). Pre-treatment with anti-CXCL16 for 24 h, but not anti-scavenger receptor-A, anti-CD36, or anti-CD68 antibodies, significantly suppressed DSS-induced IL-1 beta production. Our results suggest that DSS triggers the release of IL-1 beta protein from murine pM phi at a post-translational level through binding with CXCL16, ROS generation, and resultant activation of both p38 MAPK and ERK1/2 pathways, and finally caspase-1 activation.

Protein microarray analysis of disease activity in pediatric inflammatory bowel disease demonstrates elevated serum PLGF, IL-7, TGF-beta1, and IL-12p40 levels in Crohn's disease and ulcerative colitis patients in remission versus active disease

OBJECTIVES

Cytokines and growth factors play a major role in the dysregulated immune response in inflammatory bowel disease (IBD). We hypothesized that significant differences exist between the serum cytokine and growth factor profiles of pediatric IBD patients with active disease (AD) and those in remission, and that levels of some of these soluble mediators may be used to define regulators in IBD and determine disease activity.

METHODS

Eighty-eight consecutive patients with confirmed Crohn's disease (CD) and ulcerative colitis (UC) seen at the Duke Children's Hospital were prospectively enrolled and a serum sample was obtained. Data were recorded at the time of serum collection to calculate disease activity indices. The relative expression of 78 cytokines, growth factors, and soluble receptors was determined using proprietary antibody-based protein microarrays amplified by rolling circle amplification. SPSS 8 (SPSS Inc., Chicago, IL) was used to compare protein profiles for CD and UC patients in clinical remission (CR) versus AD.

RESULTS

Sixty-five CD patients and 23 UC patients were enrolled. Forty-one CD patients had available samples and PCDAI results. Twenty-two patients were in remission PCDAI < or = 12.5 (median 5), 19 patients had disease activity >15 (median 30). Univariate analysis revealed that PLGF, IL-7, IL-12p40, and TGF-beta1 cytokine levels were significantly elevated for patients in CR versus AD (p < 0.01). Twelve UC serum samples had Seo/Truelove Witt AI for analysis. Five patients were in remission by TW AI and Seo AI < or =110 and 7 patients had active mild-to-severe disease by TW and Seo AI >110. Only one cytokine, IL12p40, showed significance between CR versus AD (p < 0.02).

CONCLUSIONS

Surprisingly, we found no differences in circulating levels of proinflammatory cytokines but found that pediatric IBD patients in remission compared to those with AD had higher levels of specific circulating cytokines, including the regulatory cytokines IL-12p40 and TGF-beta1. It may be that these cytokines directly regulate intestinal inflammation in IBD or reflect the activity of T regulatory cells in negatively regulating the inflammatory response. Further studies will be needed to validate our results to define the molecular pathways involved in the intestinal immune response in man.

Stimulation of peripheral blood and intestinal mucosa cells by synthetic CpG oligodeoxynucleotides

The breakdown of tolerance to autologous bacterial flora has been implicated as a major factor contributing to the initiation and perpetuation of chronic inflammation in inflammatory bowel diseases (IBD). To test whether bacterial DNA is at the origin of inflammation in IBD, we have examined the response of lamina propria (LPMC) or peripheral mononuclear cells (PBMC) and purified T cells from IBD patients and control patients to stimulations with a set of oligodeoxynucleotides (ODNs) characterized by the presence or absence of cytosine-guanosine dinucleotides (CpG) and/or 3' poly-guanosine (poly-G) extension. Furthermore we have evaluated the costimulatory activities of these ODNs on T cells activated via CD2 or CD3 pathway. We demonstrated that CpG ODNs induce higher proliferation of LPMC from inflammatory intestinal mucosa compared to healthy mucosa. We confirmed that CpG ODNs do not directly costimulate peripheral blood T cells activated by CD3 pathway. Finally, we revealed that CpG or non-CpG ODNs with 3' poly-G extension inhibit completely CD2 activation of purified PB or LP T-cells whereas only CpG ODNs without poly-G extension enhance proliferation and IFN-gamma production of PB T cells stimulated by CD2 pathway only in presence of NK and NK T cells. Our data suggest that NK T cells may be the primary target of ODNs and play a crucial role in indirect T-cell activation by ODN.

T-cell-induced mucosal damage in the intestine

PURPOSE OF REVIEW

T cells are central to most inflammatory disorders of the intestine, particularly Celiac disease, graft vs. host disease, Crohn disease, and ulcerative colitis. The mechanisms by which T cells contribute to mucosal damage in these disorders have been explored using both in vitro and in vivo models. This review will highlight recent studies directed at understanding the mechanisms by which T cells are involved in the induction of mucosal damage.

RECENT FINDINGS

The recent studies of in vivo T-cell activation using monoclonal anti-CD3 antibody have shown that a number of cytotoxic T-cell pathways are required and involved in the induction of mucosal damage and in particular in the induction of epithelial cell apoptosis. These include the Fas/FasL and perforin pathways. Other mediators of T-cell-induced cytotoxicity, such as TNFalpha and IFNgamma may contribute to mucosal damage but are not required for the induction of mucosal damage in vivo. In addition, several studies have tried to identify the role of regulatory mucosal T cells and the physiologically relevant triggers for T-cell-induced mucosal damage.

SUMMARY

It is now clear that there are significant redundancies in the mechanisms that lead to immune-mediated mucosal damage and that the mechanisms that operate in vivo may not be predicted by in vitro experiments. These investigations are improving our understanding of the pathogenesis of immune-mediated enteropathies and will hopefully lead to new approaches to the management of these disorders.

Inflammation, reactive oxygen species and cytochrome P450

Inflammation may ultimately result from damage to membrane lipids by reactive oxygen species (ROS) such as peroxide, superoxide anion, hydroxyl radical and singlet oxygen. This study compares some of the methods used to determine ROS-ethane exhalation, malondialdehyde quantified as thiobarbituric acid-reacting materials, and luminol-activated chemiluminescence (LAC)-and explores possible relationships with oedema formation in the rat foot-pad model. Iron nitrilotriacetate was the most effective of the model compounds tested in producing lipid peroxidation and ethane exhalation in mice. In the mouse and the rat, iron nitrilotriacetate caused increased ethane exhalation and concomitant increases in liver and kidney malondialdehyde. In the rat foot-pad oedema model, the challenge with Freund's complete adjuvant produced maximum malondialdehyde and maximum LAC in the inflamed paw 8 h after dosing, at which time oedema had also reached a high level. These effects were attributed mainly to hydroxyl radical and singlet oxygen. The inhibition of oedema by four anti-inflammatory drugs correlated well with LAC but less well with inhibition of malondialdehyde production. This study shows good agreement between different methods of determining ROS formation, and that inhibition of ROS formation in vivo is paralleled by a decrease in inflammation.

Enteric glial cells. An upstream target for induction of necrotizing enterocolitis and Crohn's disease?

As a direct consequence of the sophisticated arrangement of its intrinsic neurons, the gastrointestinal tract is unique among peripheral organs, in its ability to mediate its own reflexes. Neurons of the enteric nervous system are intimately associated with enteric glial cells. These supporting cells do not resemble Schwann cells, the glial cell found in all other parts of the peripheral nervous system, but share many similarities with astrocytes of the central nervous system. Ablation of enteric glial cells in adult transgenic mice has demonstrated that these cells are essential to maintain the integrity of the small intestine. Acute loss of enteric glial cells induces massive pathological changes with similarities to necrotizing enterocolitis (NEC) and early Crohn's disease. These human conditions share some mechanistic similarities. Identification of enteric glial cell dysfunction/loss as sufficient to induce necrotic/inflammatory bowel disease may be important to understand the pathogenesis of both NEC and Crohn's disease.

The proportion of Th1 cells, which prevail in gut mucosa, is decreased in inflammatory bowel syndrome

T lymphocytes and their cytokines have an important role in the regulation of immune responses in the gut and in the pathogenesis of intestinal inflammation such as in Crohn's disease. The aim of this study was to analyse the Th1/Th2 cytokine profile (IFN-gamma, IL-2, IL-4 and IL-10) in intraepithelial lymphocytes (IEL) and lamina propria lymphocytes (LPL) in Crohn's disease (CD) and ulcerative colitis (UC) in relation to healthy controls (C). Colonic and ileal biopsy specimens were obtained from controls (n = 13) and patients with CD (n = 32). Colonic biopsies were obtained from patients with UC (n = 11). Intracytoplasmic IFN-gamma, IL-2, IL-4 and IL-10 were determined by flow cytometry after PMA-ionomycin stimulation in IEL and LPL. In colonic LPL, a significant proportional decrease of IFN-gamma and IL-2 producing CD3+ cells was observed in patients with CD and UC compared to controls. In ileal LPL, a similar tendency was found although differences were not significant. In IEL no differences in cytokine profiles could be observed. Flow cytometric analysis of intracytoplasmic cytokines at single cell level showed a proportional decrease of IFN-gamma and IL-2 producing T cells in colonic lamina propria in patients with inflammatory bowel disease.

VEGF, basic-FGF, and TGF-beta in Crohn's disease and ulcerative colitis: a novel mechanism of chronic intestinal inflammation

OBJECTIVE

Inflammatory bowel disease (IBD), the precise etiology of which remains unknown, is comprised of two forms of chronic intestinal inflammation; ulcerative colitis (UC) and Crohn's disease (CD). Recent evidence increasingly suggests that IBD is the result of dysfunctional immunoregulation manifested by inappropriate production of mucosal cytokines. An abnormal microcirculatory system has also been implicated in its pathogenesis. To elucidate the mechanism of ischemic change in IBD, we assesse serum concentration levels of vascular endothelial growth factor (VEGF) and basic fibroblast growth factor (b-FGF), and plasma level of endothelin-1 (ET-1). We also investigated the expression of VEGF, b-FGF, and transforming growth factor-beta1,2,3 (TGF-beta1,2,3) in tissue by immunostaining.

METHODS

Blood samples were obtained from 11 patients with UC, 11 patients with CD, and 10 patients as controls. Paraffin-embedded samples were used for an immunohistochemical study.

RESULTS

The concentration levels (in picograms per milliliter) were as follows: for ET-1, UC: 127+/-47.0, CD: 167.3+/-35.1, and controls (asthma: 38.5+/-23.8, p < 0.01; diverticulitis: 40.5+/-25.6, p < 0.01), for b-FGF, UC: 9.2+/-1.9, CD: 9.1+/-1.5, and controls (asthma: 5.0+/-0, p < 0.01; diverticulitis: 5.0+/-0, p < 0.01), for VEGF, UC: 659.8+/-181.0, CD: 740.0+/-182.3, and controls (asthma: 193.7+/-58.7, p < 0.01; diverticulitis: 199.6+/-59.7, p < 0.01). The levels of VEGF and b-FGF were significantly higher in active IBD than those in the controls. There was a significant positive correlation among the serum levels of VEGF and b-FGF and the plasma level of ET-1; that is, elevated VEGF, b-FGF, and ET-1 levels correlated well with each other. Immunohistochemical studies showed increased venula in the submucosa and lamina propria. Overexpression of VEGF and b-FGF in endothelial cells was revealed and TGF-beta2 and TGF-beta3 were found in inflammatory cells of active IBD, but no change was observed around the vessels in the controls.

CONCLUSIONS

It is suggested that the reciprocal reaction of these cytokines may contribute to angiogenesis in IBD b inducing intestinal ischemia through vasoconstriction.

Quantitative assessment of mast cells and expression of IgE protein and mRNA for IgE and interleukin 4 in the gastrointestinal tract of healthy dogs and dogs with inflammatory bowel disease

OBJECTIVE

To characterize the mucosal IgE network in dogs affected with inflammatory bowel disease (IBD) and compare it with that for healthy dogs.

ANIMALS

9 healthy dogs and 20 dogs with IBD.

PROCEDURE

In situ hybridization of mRNA specific for IgE and interleukin 4 (IL-4) and immunohistochemical analysis for IgE protein and 2 markers of mast cells (ie, tryptase and chymase) were performed on tissue sections obtained from the gastrointestinal (GI) tract and lymph nodes of dogs.

RESULTS

Dogs with IBD had significantly more cells positive for IgE protein and more mast cells in the GI mucosa than healthy dogs. Despite this significant increase in number of cells positive for IgE, cells positive for IgE mRNA were rarely detected in the GI mucosa; most cells positive for IgE mRNA were found in mesenteric lymph nodes. Signal pattern of IL-4 mRNA was similar to that of IgE mRNA.

CONCLUSIONS AND CLINICAL RELEVANCE

The increased numbers of cells positive for IgE and mast cells in dogs with IBD suggest hypersensitivity such as hypersensitivity to bacterial or dietary-derived antigens in the intestinal lumen. Future studies need to elucidate whether this represents a cause of inflammation or is a result of the inflammatory process of IBD.

Tumor necrosis factor-alpha and interleukin-1beta inhibit apolipoprotein B secretion in CaCo-2 cells via the epidermal growth factor receptor signaling pathway

In inflammatory conditions of the gut, cytokines are released into the mucosa and submucosa propagating and sustaining the inflammatory response. In CaCo-2 cells, we have shown that various inflammatory cytokines interfere with the secretion of lipids, an effect that is likely caused by the release of a ligand to the epidermal growth factor (EGF) receptor. In the present study, the role of the EGF receptor signaling pathway and the effects of the cytokines tumor necrosis factor-alpha (TNF-alpha) and and interleukin 1beta (IL-1beta) on triacylglycerol-rich lipoprotein secretion were investigated. CaCo-2 cells were incubated with oleic acid to enhance triacylglycerol-rich lipoprotein secretion. TNF-alpha and IL-1beta significantly decreased the basolateral secretion of apolipoprotein B (apoB) mass, with IL-1beta being more potent. Tyrphostin, an inhibitor of the EGF receptor intrinsic tryosine kinase, prevented or markedly attenuated the decrease in apoB secretion by TNF-alpha or IL-1beta. Both cytokines increased the phosphorylation of the EGF receptor by 30 min. Moreover, phosphotyrosine immunoblots of the EGF receptor demonstrated an increase in tyrosine residues phosphorylated by 0.5 and 6.5 h. At both these time points, TNF-alpha and IL-1beta also decreased the binding of EGF to its cell surface receptor. At 6.5 h, activation of the EGF receptor was sustained. In contrast, the early activation of the receptor was only transient as receptor phosphorylation and binding of EGF to its receptor returned to basal levels by 2 h. Preventing ligand binding to the EGF receptor by a receptor-blocking antibody attenuated receptor activation observed after 6.5 h. This did not occur at 0.5 h, suggesting that early activation of the EGF receptor was non-ligand-mediated. Similarly, apoB secretion was inhibited by an early non-ligand-mediated process; whereas at the later time, inhibition of apoB secretion was ligand-mediated. Thus, the inflammatory cytokines TNF-alpha and IL-1beta interfere with the secretion of triacylglycerol-rich lipoproteins by both early and delayed signaling events mediated by the EGF receptor signaling pathway.

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.

The influence of cigarette smoking on cytokine levels in patients with inflammatory bowel disease

Anecdotal reports suggest that smoking may be beneficial for patients with inflammatory bowel disease (IBD) as nicotine may act through inflammatory mediators within the colonic mucosa. Furthermore, there is increasing evidence that cytokines play a pathologic role in IBD. Our aim was to determine the effects of cigarette smoking on cytokine levels in the colonic mucosa of patients with and without IBD. Mucosal biopsies were obtained from 10 patients with Crohn's disease (CD), 10 with ulcerative colitis (UC), and 10 healthy controls. Five of 10 patients in each of the three groups were smokers and five were nonsmokers. Concentrations of interleukin (IL)-1beta, IL-2, IL-6, and IL-8 were determined using enzyme-linked immunosorbent assay (ELISA). Cytokine levels of smokers were compared with nonsmokers in each group and with controls. Results were analyzed using the Mann-Whitney test; significance was set at p<0.05. The concentration of IL-8 was significantly higher in healthy controls who smoke compared with nonsmokers and significantly reduced in smokers with CD compared with nonsmokers with CD. Moreover, concentrations of IL-1beta and IL-8 were significantly reduced in smokers with UC compared with nonsmokers with UC. Smokers had significantly elevated levels of IL-8 in the colonic mucosa. Smokers with IBD had a significant reduction in cytokine levels; specifically, IL-1beta and IL-8 for patients with UC and IL-8 for patients with CD. Further studies are warranted to determine if this reduction in cytokine levels is histologically and clinically significant.

Colonic explant production of IL-1and its receptor antagonist is imbalanced in inflammatory bowel disease (IBD)

IBD is associated with an increased activation of intestinal immune cells, which causes overproduction of proinflammatory cytokines such as IL-1beta. IL-1beta is implicated in mediating the sustained inflammatory response. IL-1 receptor antagonist (IL-1Ra), the naturally occurring inhibitor of IL-1, has been shown to have beneficial effects in experimental models of colitis. In this study we investigated the hypothesis that an imbalance between IL-1 and IL-1Ra exists in IBD by measuring their secretion by explant cultures of colonic biopsies. Freshly homogenized biopsies from involved tissue in IBD patients exhibited significantly lower IL-1Ra/IL-1beta ratios than control and uninvolved IBD mucosal tissue. Using explant cultures, in vitro production of IL-1beta and IL-1Ra increased progressively during the 4-18-h culture periods. IL-1beta secretion was higher in supernatants from involved Crohn's disease (CD) and ulcerative colitis tissue compared with control tissue, and IL-1beta levels increased with severity of inflammation. IL-1Ra secretion was not elevated in involved IBD samples, but significantly higher levels were released when moderate to severely involved tissue samples were compared with noninflammatory controls. Similar to freshly homogenized tissue, explant studies showed that the IL-1Ra/IL-1beta ratios were significantly decreased in involved IBD tissue, but not in uninvolved CD or inflammatory control specimens. These data support the hypothesis of an imbalance between IL-1beta and IL-1Ra in IBD.

Nucleoside-nucleotide-free diet suppresses cytokine production and contact sensitivity responses in rats with trinitrobenzene sulphonic acid-induced colitis

We examined the effects of dietary nucleoside-nucleotide mixture on synthesis of inflammatory cytokines, interleukin-8 and tumor necrosis factor-alpha, in sensitized and nonsensitized colitic rats. Sensitized and nonsensitized colitic rats that were fed a nucleoside-nucleotide mixture had greater colonic weight and macroscopic and microscopic damage scores than nucleoside-nucleotide-free sensitized and nonsensitized colitic rats. Increased colonic tumor necrosis factor-alpha and interleukin-8 concentrations were associated with increased colonic inflammation and ulceration in the nucleoside-nucleotide mixture-fed group. There was also increased ear thickness in the nucleoside-nucleotide mixture-fed sensitized and nonsensitized colitic rats, which correlated highly with increased tumor necrosis factor-alpha and interleukin-8 levels in the ear lobes. Nucleoside-nucleotide-free diets may suppress cytokine secretion, thereby reducing colonic damage and contact sensitivity responses in colitic rats.

The soluble interleukin-2 receptor, peripheral blood, and reticulocyte fractions in acute pancreatitis

CONCLUSION

In acute pancreatitis (AP), the peripheral blood analysis, including reticulocytes (RC) and RC fractions, and its relationship to the changes of the levels of the soluble interleukin 2 receptor (sIL-2R) can provide useful information about the involvement of the immunoinflammatory system in AP and can indicate the severity of the disease.

BACKGROUND

In the disease clinical assessment, we correlated the sIL-2R serum levels to the peripheral blood components (including RC and RC fractions) to serum albumin and C-reactive protein (CRP) during AP.

METHODS

In 21 patients with AP, sIL-2R, the total and differential white blood cell (WBC) counts, red blood cell (RBC) counts, RC, RC fractions, hemoglobin (Hb), hematocrit (Ht), platelets (PLT), albumin, and CRP were evaluated from the onset to the sixth day of illness.

RESULTS

sIL-2R increased in all the patients. The increase was directly related to eosinophils, monocytes, and to middle-aged (MFR) RC, and inversely related to neutrophils and the old (LFR) RC. MFR-RC were directly related to the total WBC count, eosinophils, and basophils, and inversely related to Hb and albumin. LFR-RC behaved in the opposite manner. CRP increased in 16 patients; this rise was directly related to WBC, RC, and MFR-RC, and inversely related to Hb, LFR-RC, and albumin. sIL-2R and CRP values were not statistically interrelated, but when the CRP levels were higher, the increase in sIL-2R was greater and more sustained.

Nucleoside-nucleotide free diet protects rat colonic mucosa from damage induced by trinitrobenzene sulphonic acid

BACKGROUND

Growing evidence suggests that intestinal recovery from injury induced by radiation, endotoxin, and protein deficiency is improved by the ingestion of nucleosides and nucleotides.

AIM

This study examined the effect of dietary nucleosides and nucleotides supplementation on trinitrobenzene sulphonic acid induced colonic damage in experimental colitis.

METHODS

Sprague-Dawley rats were randomised into two groups and fed nucleic acid free 20% casein diet (control) or this diet supplemented with 0.5% nucleoside-nucleotide mixture for four weeks. On the second week, colonic inflammation was induced in rats by intracolonic administration of 0.25 ml of 50% ethanol containing 25 mg of trinitrobenzene sulphonic acid. Additionally, other sets of rats were treated with 0.25 ml of 50% ethanol, 25 mg of trinitrobenzene sulphonic acid in 0.25 ml saline, or 0.25 ml of 0.9% saline.

RESULTS

After two weeks, colon weight, macroscopic and microscopic damage scores, were significantly greater (p < 0.05) in the nucleoside-nucleotide supplemented group compared with the non-supplemented control groups. The same variables seen in the trinitrobenzene sulphonic acid-ethanol group fed nucleoside-nucleotide free diet were greater (p < 0.05) than in the rest of the groups fed nucleoside-nucleotide free diet and treated with ethanol, trinitrobenzene sulphonic acid in saline, or saline. Histologically, segmental ulceration and inflammation associated with significantly increased infiltration of polymorphonuclear leucocytes, macrophages, lymphocytes, fibroblasts were observed in the supplemented group compared with the controls. In the nucleoside-nucleotide supplemented group the epithelial damage, mucosal erosion, oedema, and coagulative necrosis of the muscularis propria was more extensive in comparison to the non-supplemented control groups.

CONCLUSIONS

This study suggests that dietary nucleosides and nucleotides may aggravate colonic damage and inflammation in chemically induced experimental colitis in rats; and that nucleoside-nucleotide free diet combined with other pharmacological agents may offer a better response.

A simple filter-paper technique allows detection of mucosal cytokine levels in vivo in ulcerative colitis. Interleukin-1 and interleukin-1-receptor antagonist

A simple filter-paper method for in vivo assessment of cytokines in intestinal mucosa of patients with ulcerative colitis (UC) was developed and evaluated. Twenty-eight patients were included. Twenty-three patients had ulcerative colitis (UC) and five irritable bowel syndrome (IBS). Inflammation was assessed endoscopically. Through a rectoscope, filter paper was applied to the macroscopically most inflamed area of the rectal mucosa until soaked. The filter paper was transferred to a buffer solution, and IL-1 beta and IL-1ra were assessed using ELISA. Positive correlations between endoscopic grading and In(IL-1 beta) (P < 0.0001) and In(IL-1ra) (P < 0.001) and a negative correlation between endoscopic grading and In(IL-1ra /IL-1 beta) (P < 0.02) were found. In measurements during and after a flare-up no significant change in IL-1ra but a significant decrease in IL-1 beta was detected, which is in agreement with investigations on biopsies. In conclusion, the filter-paper technique is an easily applicable, low-risk method that provides a means of monitoring cytokines in vivo in UC.

Role of cytokines and platelet-activating factor in inflammatory bowel disease. Implications for therapy

BACKGROUND

Platelet-activating factor (PAF) and cytokines, such as interleukins, tumor necrosis factor, and others, are thought to play a role in the inflammatory process involving gastrointestinal disorders such as Crohn's disease, ulcerative colitis, ischemic colitis, or antibiotic-associated colitis.

PURPOSE

This study was undertaken to review the latest literature on the role of PAF and cytokines in the genesis of inflammatory bowel disease and implications for therapy and management.

RESULTS

PAF is an endogenous phospholipid involved in hypersensitivity and inflammatory reactions such as platelet and neutrophil aggregation, vasodilation, increased vascular permeability, and leukocyte adhesion, which have been associated with inflammatory processes. Cytokines are peptides that regulate and coordinate inflammatory and immunologic responses. Increased production of cytokines has been reported during Crohn's disease and ulcerative colitis and is correlated with disease activity.

CONCLUSIONS

Because PAF and cytokines may have an important role in the pathogenesis of inflammatory bowel disease, their inhibition by specific antagonists, mediators, or other agents such as steroids may have a potential therapeutic benefit in treatment and management of these inflammatory diseases in the near future.

Clinical pharmacology in gastroenterology: development of new forms of treatment of inflammatory bowel disease

Kinetic-dynamic aspects of the development of slow-release mesalazine, Pentasa (now an established treatment of inflammatory bowel disease (IBD)), and cyclosporin, a T cell selective immunosuppressant (still in the investigative phase), are reviewed as examples of Danish contributions at an early stage to international, clinical drug research. Apart from increasing the therapeutic options for patients with IBD, current and future studies with these (and other) drugs may add important clues to a more precise understanding of the basic pathogenetic mechanisms (e.g. cytokines, adhesion molecules) involved in these diseases. The future development and clinical implementation of novel drug designs in IBD and other gastrointestinal diseases may be expected to benefit from a continued or even closer collaboration between clinical gastroenterologists and basic research institutions, including the pharmaceutical industry at an early stage.

Altered Th1/Th2 cytokine profiles in the intestinal mucosa of patients with inflammatory bowel disease as assessed by quantitative reversed transcribed polymerase chain reaction (RT-PCR)

Cytokines serve a central function as key factors in the regulation of the intestinal immune response and mediation of tissue damage in inflammatory bowel disease (IBD). Abnormalities in the expression of immunoregulatory cytokines such as IL-2, IL-4, IL-10 and interferon-gamma (IFN-gamma) may indicate a dysregulation of intestinal immunity probably associated with pathogenic events. Therefore, cytokine mRNA concentrations were determined in the mucosa of patients with IBD at sites of active (n = 13) and inactive (n = 12) ulcerative colitis (UC), active (n = 11) and inactive (n = 11) Crohn's disease (CD) and in control patients (n = 14) using quantitative RT-PCR. IL-10 mRNA concentrations were significantly increased in patients with both active UC (P < 0.001) and active CD (P < 0.005) compared with control patients. IFN-gamma mRNA concentrations were also significantly increased both in patients with active UC (P < 0.02) and active CD (P < 0.05) compared with control patients, whereas IL-2 mRNA levels were significantly (P < 0.02) increased only in active CD. IL-4 mRNA expression in the intestinal mucosa was frequently below the detection limit. Our results demonstrate that chronic intestinal inflammation in patients with CD is characterized by an increase of Th1-like cytokines. Furthermore, the increased IL-10 mRNA expression at sites of active IBD suggests that IL-10 is an important regulatory component involved in the control of the inflammatory response in inflammatory bowel disease.

European trial of cyclosporine in chronic active Crohn's disease: a 12-month study. The European Study Group

BACKGROUND & AIMS

The role of cyclosporine in Crohn's disease is controversial. This study aimed to delineate the long-term effect of cyclosporine in chronic active Crohn's disease.

METHODS

One hundred eighty-two patients from 33 European centers were included. The patient cohort was stratified at entry into a stratum with low Crohn's Disease Activity Index (CDAI) ( < 200) and high CDAI ( > 200). The low-activity group continued to receive the pretrial steroid dose for 2 months, and the high-activity group received 1 mg.kg-1.day-1 prednisone initially. During months 3 and 4, the dose of steroids was reduced stepwise to 5 mg/day in all patients. Placebo and cyclosporine (5 mg.kg-1.day-1) were administered throughout the 12-month study period. The main parameter of efficacy was the CDAI, and the main end point was the number of patients in remission at month 12.

RESULTS

During cyclosporine therapy, 35% (95% confidence interval [95% Cl], 25%-46%) of the patients achieved a full remission (CDAI, < 150) after 4 months compared with 27% (95% Cl, 18%-38%) in the placebo group (P > 0.05). At month 12, only 20% (95% Cl, 12%-31%) vs. 20% (95% Cl, 12%-31%) of the patients had maintained a continuous remission. No major differences between treatment groups were found within each of the two strata.

CONCLUSIONS

The long-term treatment of chronic active Crohn's disease with cyclosporine plus low-dose steroids does not offer an advantage compared with low-dose steroids alone.

Severe colitis in mice with aberrant thymic selection

Tg epsilon 26 mice display an arrest very early in T cell development that has a profound effect on the architecture of thymic stromal cells. We have recently demonstrated that transplantation of wild-type bone marrow cells restores the thymic microenvironment of fetal but not adult Tg epsilon 26 mice. Here, we report that T cell-reconstituted adult Tg epsilon 26 mice develop a spontaneous wasting syndrome characterized by extensive inflammation of the colon, resembling human ulcerative colitis. Colitis in these animals was marked by substantial infiltration of the colon by activated thymus-derived CD4+ T cells. Importantly, bone marrow-transplanted Tg epsilon 26 mice previously engrafted with a fetal Tg epsilon 26 thymus did not develop colitis. These results suggest that T cells selected in an aberrant thymic microenvironment contain a population of cells able to induce severe colitis that can be prevented by T cells that have undergone normal thymic development.

Phenotypic and immunoregulatory analysis of intestinal T-cells in patients with inflammatory bowel disease: evaluation of an in vitro model

Although a disturbed immune response to constituents of the gut mucosa has been implicated in the pathogenesis of inflammatory bowel disease, the mechanisms are still unclear. Intestinal T-cells derived from gut biopsies were propagated in vitro as single and co-cultures under different experimental conditions prior to flow cytometry. Intestinal T-cell lines from inflamed mucosa (n = 69) showed a significant (P < 0.001) decrease in CD4+ T-cells compared to T-cells from normal (n = 49) and uninflamed (n = 29) tissue specimens. Co-culturing of inflamed and uninflamed mucosa led to a normalization of CD4+ T-cells in cultures derived from inflamed mucosa. Analysis of supernatants revealed a significantly (P < 0.001) increased secretion of IL-4 under co-culture conditions. Moreover, stimulation of cultures derived from inflamed mucosa with rIL-4 led to a significant (P < 0.001) increase in CD4+ T-cells, whereas anti-IL-4 antibodies or IFN-gamma supplementation of T-cells derived from uninflamed mucosa significantly (P < 0.001) reduced the CD4+ subset. Treatment with IFN-gamma and anti-IL-4 antibodies did not affect the phenotype of T-cells derived from inflamed mucosa. These data suggest that IL-4 might play a key role in the intestinal immune response. Furthermore, this in vitro system allows the investigation of mucosal immune mechanisms in more detail under standardized conditions.

Interleukin-2 receptor alpha and beta chain expression by circulating alpha beta and gamma delta T cells in inflammatory bowel disease

The pathogenetic role of activated alpha beta and gamma delta T cells in inflammatory bowel disease (IBD) is not well defined. To elucidate this, interleukin-2 receptor (IL-2R) alpha and IL-2R beta single chain expression and coexpression by peripheral blood TCR alpha beta + cells and TCR gamma delta + cells was studied in 21 patients with ulcerative colitis (UC), 25 with Crohn's disease (CD), and 15 controls. The percentages of IL-2R alpha + beta-, IL-2R alpha-beta +, and IL-2R alpha + beta + TCR alpha beta + cells were increased in IBD patients with moderate and severe disease activity, as compared to controls (P < 0.01). In contrast, the percentages of IL-2R alpha-beta + and IL-2R alpha + beta + TCR gamma delta + cells were increased in patients with inactive UC (P < 0.01), but not in CD. The results suggest that activated alpha beta T cells are involved in the development of IBD. The differences in gamma delta T cell IL-2R expression between inactive UC and CD may correspond to a yet undefined etiopathogenetic difference between these two diseases.

Tolerability of interferon alpha-2b, a possible new treatment of active Crohn's disease

BACKGROUND AND AIMS

Due to the need for new principles for the treatment of Crohn's disease and due to the documented immunomodulatory effects of interferon alpha, the tolerability and effect(s) of interferon alpha-2b (Introna) in active Crohn's disease were examined in a pilot study.

METHODS

Five patients with active Crohn's disease (activity index (CDAI) scores of 235-517), were treated with interferon alpha-2b for 12 weeks.

RESULTS

All patients tolerated the treatment, but developed influenza-like symptoms, which were fully controlled by paracetamol. Two patients obtained partial remission with a decline in activity index scores of 39% and 50%. The activity of 2',5'-oligoadenylate synthetase, which together with two other interferon-induced proteins, neopterin and beta 2-microglobulin were increased during treatment, indicated clearly an in vivo uptake of interferon. Sedimentation rate, C-reactive protein, orosomucoid, albumin, specific inflammatory markers: soluble interleukin-2 alpha-receptors (sIL-2R) and intercellular adhesion molecule-1 (ICAM-1) did not show any changes before or after treatment.

CONCLUSION

Future multicentre investigations are required to evaluate the clinical effect of interferon alpha-2b treatment in active Crohn's disease.

Neutrophil-macrophage interaction: a paradigm for chronic inflammation

Autoimmune diseases, such as rheumatoid arthritis and inflammatory bowel disease are characterized by chronic inflammatory responses resulting in tissue damage. These diseases have a number of common denominators including: abnormal cytokine expression, aberrant antigen-antibody complexes, T cell anomalies, and increased numbers of neutrophils and macrophages. We propose that the interaction between neutrophils and macrophages induces a state of chronic inflammation which contributes to the disease state. One of the central players in this scenario is myeloperoxidase (MyPo). This enzyme functions in the 'cytotoxic triad' and is involved in cell killing. Studies done by the present investigators have known that MyPo, which is released from neutrophils, induces macrophages to secrete interleukin-1, interferon alpha beta and tumor necrosis factor alpha. Furthermore, our studies have suggested a major immunoregulatory role of this enzyme. We propose that the release of MyPo from neutrophils and subsequent binding to macrophages initiates a cascade of events which enhance the production of reactive oxygen intermediates and cytokine expression resulting in the chronic inflammatory state associated with autoimmune diseases.

Cytokines in Crohn's colitis

BACKGROUND

Increasing evidence points to a pathologic role for cytokines in Crohn's colitis. Levels of cytokines are increased in diseased segments of colon in Crohn's colitis, but no one has studied the concentration of cytokines in clinically and histologically nondiseased segments.

METHODS

Mucosal biopsies were obtained from 7 patients with active segmental Crohn's colitis and from 7 controls without inflammatory bowel disease. The concentration of Interleukin (IL)-1 beta, IL-2, IL-6, and IL-8 in patients and controls were determined using enzyme linked immunosorbent assay and compared. Histologic sections were also performed to confirm diseased and nondiseased segments of colon.

RESULTS

The concentrations of IL-1 beta, IL-6, and IL-8 were significantly higher in the involved segments of colon (10.3 +/- 4.1, 3.7 +/- 1.0, 34.4 +/- 6.9 picograms [pg] per mg) when compared to controls (1.8 +/- 0.5, 1.1 +/- 0.5, 5.3 +/- 1.0 pg/mg). The concentrations of IL-1 beta, IL-2, and IL-8 (8.5 +/- 2.9, 5.3 +/- 1.2, 26.3 +/- 8.8 pg/mg) in normal appearing segments of colon of patients with Crohn's colitis were also significantly higher than in controls, whose IL-2 level was 2.0 +/- 0.5 pg/mg. IL-1 beta and IL-8 were significantly more concentrated in both the involved and uninvolved colonic segments of patients with Crohn's colitis compared to controls. IL-2 and IL-6 were also more concentrated in Crohn's patients than in controls, but not significantly. The differences in interleukin concentrations between involved and uninvolved segments of colon in patients with segmental Crohn's colitis were not significant.

CONCLUSIONS

Although Crohn's colitis is often a segmental disease, concentrations of IL-1 beta and IL-8 are increased throughout the entire colon. These observations reinforce the hypothesis that Crohn's colitis involves the whole colon even when this is not apparent clinically or histologically.

Circulating soluble intercellular adhesion molecule-1 (sICAM-1) in active inflammatory bowel disease

Intercellular adhesion molecule (ICAM)-1 promotes the initial interaction between macrophages and T cells during immune activation. We have measured serum levels of soluble ICAM-1 (sICAM-1) by ELISA in 27 patients with ulcerative colitis (UC), 31 with Crohn's disease (CD), and 29 healthy subjects. The median sICAM-1 serum concentration was significantly increased in inflammatory bowel disease (IBD) patients (355 ng/ml, range 195-855) compared to controls (245 ng/ml, 155-580) (P = 0.001). Variance analysis for trend showed that sICAM-1 levels were significantly higher in patients with active CD and UC, compared to those with inactive disease and controls (P = 0.00002). The concentration of sICAM-1 was higher in CD patients (365 ng/ml 230-470) compared to UC (300 ng/ml 195-855) (P = 0.01). Furthermore, weak but significant correlations were found between serum levels of sICAM-1 and: soluble IL-2 receptors, orosomucoid, and C-reactive protein. It is suggested that increased circulating sICAM-1 levels may reflect increased adhesiveness and signal transmission across cells, probably as a result of shedding of the parent molecule during local cellular immunoresponses in vivo.

Characterization of circulating interleukin-1 receptor antagonist expression in children with inflammatory bowel disease

The cytokines IL-1 beta and IL-6 appear to be important in the pathogenesis of inflammatory bowel disease (IBD). Recently, a naturally occurring interleukin-1 receptor antagonist, designated IL-1ra, which inhibits IL-1 beta activity in vitro and in vivo has been described. The purpose of the present study was to assess the circulating levels and relative relationships of IL-1ra, IL-1 beta, and IL-6 in children with IBD of varying severity. Serum/plasma samples were obtained from 32 children with ulcerative colitis, 45 with Crohn's disease, and 24 control patients. Cytokine assays were performed by enzyme-linked immunoassay. IL-1ra levels were significantly elevated in children with ulcerative colitis or Crohn's disease of moderate/severe activity compared to patients with inactive/mild IBD or control subjects (P < 0.001). IL-1 beta was only detectable in the circulation of two subjects with severe colitis (one ulcerative colitis, one Crohn's disease), and both had extremely elevated IL-1ra levels. IL-1ra levels were significantly related to IL-6 levels for patients with IBD (P < 0.00001). Our results suggest that circulating IL-1ra appears in increasing concentrations in children with mounting degrees of disease severity as determined by clinical scoring methods as well as by the level of IL-6. Future work will need to address the clinical and prognostic value of measuring circulating IL-1ra in individuals with inflammatory bowel disease.