Loss of interleukin-2-producing intestinal CD4+ T cells in inflammatory bowel disease

Analysis of differentially expressed lncRNAs and mRNAs associated with slow‑transit constipation

Slow transit constipation (STC) is a refractory gastrointestinal disease, accounting for approximately 13 ∼ 37 % of chronic constipation. However, the molecular mechanism of STC remains poorly understood. Herein, this study aims to identify the key mRNAs and lncRNAs associated with STC. To this end, we performed high-throughput RNA sequencing to identify differentially expressed (DE) mRNAs and lncRNAs in the whole-layer sigmoid intestinal tissues from 4 STC patients and 4 non-STC patients. The identified DE lncRNAs and mRNAs were validated through quantitative real-time PCR. Weighted gene co-expression network analysis (WGCNA) and Pearson correlation analysis were conducted to determine the significantly correlated DE mRNA-lncRNA pairs. A total of 1420 DE lncRNAs and 1634 DE mRNAs were identified. Kyoto Encyclopedia of Genes and Genomes analysis of DE mRNAs indicated that these DE mRNAs might be associated with systemic lupus erythematosus, alcoholism, intestinal immune network for IgA production, inflammatory bowel disease, NF-kappa B signaling pathway. WGCNA and Pearson correlation analyses jointly identified 16,577 significantly correlated DE mRNA-lncRNA pairs. Furthermore, lncRNAs LINC00641, LINC02268, LINC03013 were identified as hub lncRNAs. The protein-protein interaction (PPI) network of proteins encoded by DE mRNAs was established, and PPI-based analysis revealed that Interleukin 2(IL2), CD80 molecule (CD80), interleukin-17A (IL-17A) might play significant roles in the development of STC. This study analyzes the expression profiles of lncRNAs and mRNAs associated with STC. Our findings will contribute to further understanding of the molecular mechanism of STC and provide potential diagnostic or therapeutic biomarkers for STC.

Clostridium butyricum MIYAIRI 588-Induced Protectin D1 Has an Anti-inflammatory Effect on Antibiotic-Induced Intestinal Disorder

Metabolites are thought as the end products in cellular regulatory processes and their levels show the strongest relationships with the phenotype. Previously, we showed that the administration of Clostridium butyricum MIYAIRI 588 (CBM 588) upregulated protectin D1, an anti-inflammatory lipid metabolite, in colon tissue under antibiotic therapy. However, how CBM 588 induces protectin D1 expression and whether the metabolite has anti-inflammatory effects on antibiotic-induced inflammation are unclear. Therefore, here, we evaluated the effect of CBM 588 on lipid metabolism and protectin D1 in gut protection from antibiotic-induced intestinal disorders. In the CBM 588 treatment group, expression levels of genes encoding lipid receptors related to the conversion of DHA to protectin D1, such as polyunsaturated fatty acid (PUFA) receptors, G-protein coupled receptor 120 (GPR120), and 15-lipoxygenase (LOX), were increased in colon tissue. CD4⁺ cells producing interleukin (IL)-4, the main component of T helper type 2 (Th2) cells that can activate 15-LOX, also increased in CBM 588-treated groups even after clindamycin co-administration. In addition, similar to CBM 588, exogenously administered protectin D1 reduced inflammatory cytokines, while IL-10 and TGF-β1, works as anti-inflammatory cytokines, were increased. Our data revealed that CBM 588 activated 15-LOX to enhance protectin D1 production by increasing IL-4-producing CD4⁺ cell population in the intestinal tract. Additionally, CBM 588-induced protectin D1 clearly upregulated IL-10-producing CD4⁺ cells to control antibiotic-induced gut inflammation. We provide new insights into CBM 588-mediated lipid metabolism induction for the treatment of gut inflammatory diseases.

Molecular Structure and Function of Janus Kinases: Implications for the Development of Inhibitors

Cytokines can trigger multiple signalling pathways, including Janus tyrosine kinases [JAK] and signal transducers and activators of transcription [STATS] pathways. JAKs are cytoplasmic proteins that, following the binding of cytokines to their receptors, transduce the signal by phosphorylating STAT proteins which enter the nuclei and rapidly target gene promoters to regulate gene transcription. Due to the critical involvement of JAK proteins in mediating innate and adaptive immune responses, these family of kinases have become desirable pharmacological targets in inflammatory diseases, including ulcerative colitis and Crohn's disease. In this review we provide an overview of the main cytokines that signal through the JAK/STAT pathway and the available in vivo evidence on mutant or deleted JAK proteins, and discuss the implications of pharmacologically targeting this kinase family in the context of inflammatory diseases.

The role of cytokines in inflammatory bowel disease

Cytokines play an important role in the development and persistence of the inflammatory lesions seen in Crohn's disease and ulcerative colitis. This review discusses the current thinking of the role of cytokines in chronic intestinal inflammation including the involvement of immunoregulatory cytokines within the Th1 and Th2 subsets.

Molecular mechanism of interleukin-2-induced mucosal homeostasis

Sustained damage to the mucosal lining in patients with inflammatory bowel disease (IBD) facilitates translocation of intestinal microbes to submucosal immune cells leading to chronic inflammation. Previously, we demonstrated the role of Jak3 in IL-2-induced intestinal epithelial cell (IEC) migration, one of the early events during intestinal wound repair. In this study, we demonstrate that IL-2 also plays a role in IEC homeostasis through concentration-dependent regulation of IEC proliferation and cell death. At lower concentrations (≤50 U/ml), IL-2 promoted proliferation, while at higher concentrations (100 U/ml), it promoted apoptosis. Activation by IL-2 led to tyrosine phosphorylation-dependent interactions between Jak3 and p52ShcA only at lower concentrations. Phosphatase SHP1 dephosphorylated IL-2-induced phosphorylated p52ShcA. Higher concentrations of IL-2 decreased the phosphorylation of Jak3 and p52ShcA, disrupted their interactions, redistributed Jak3 to the nucleus, and induced apoptosis in IEC. IL-2 also induced dose-dependent upregulation of p52shcA and downregulation of jak3-mRNA. Constitutive overexpression and mir-shRNA-mediated knockdown studies showed that expression of both Jak3 and p52ShcA were necessary for IL-2-induced proliferation of IEC. Doxycycline-regulated sh-RNA expression demonstrated that IL-2-induced downregulation of jak3-mRNA was responsible for higher IL-2-induced apoptosis in IEC. Collectively, these data demonstrate a novel mechanism of IL-2-induced mucosal homeostasis through posttranslational and transcriptional regulation of Jak3 and p52ShcA.

Patients with inflammatory bowel disease may have a transforming growth factor-beta-, interleukin (IL)-2- or IL-10-deficient state induced by intrinsic neutralizing antibodies

Ulcerative colitis (UC) and Crohn's disease (CD) are considered to be immunologically mediated disorders that share certain features with murine models of colitis. Whether any of these models are physiologically relevant to the human condition remains controversial. The hypothesis is that increased amounts of antibodies neutralizing transforming growth factor (TGF)-beta, interleukin (IL)-2 or IL-10 create a relative immunodeficient state in inflammatory bowel disease (IBD) that predisposes to disease. To evaluate this, serum samples from patients with UC or CD and from normal healthy individuals were studied by enzyme-linked immunosorbent assays. Antibodies recognizing TGF-beta were most prevalent in UC (P<0.01); anti-IL-10 antibodies were elevated in CD (P<0.05), while anti-IL-2 antibodies were the same for all three groups. Importantly, the percentage of IBD patients with at least one of the antibody levels greater than any control value was 30% for UC and 33% for CD. To verify the presence of these antibodies, immobilized TGF-beta was exposed to UC sera and the attached proteins identified by Western blot assay. The proteins proved to be exclusively immunoglobulin (Ig) G. To evaluate the neutralizing activity of these antibodies, cytokine-specific IgG from subjects in each group of patients was incubated with TGF-beta, IL-2 or IL-10 before addition to a bioassay with changes in viability determined by a colorimetric analysis. Antibodies from most individuals in all three groups neutralized the action of each cytokine. This study shows that about one-third of IBD patients may have a relative deficiency of TGF-beta, IL-2 or IL-10 due to an increase in neutralizing antibodies in their sera.

Intestinal epithelial cells from inflammatory bowel disease patients preferentially stimulate CD4+ T cells to proliferate and secrete interferon-gamma

Previous studies have suggested that intestinal epithelial cells (IECs) have the capacity to function as nonprofessional antigen presenting cells that in the normal state preferentially activate CD8+ T cells. However, under pathological conditions, such as those found in inflammatory bowel disease (IBD), persistent activation of CD4+ T cells is seen. The aim of this study was to determine whether the IBD IECs contribute to CD4+ T cell activation. Freshly isolated human IECs were obtained from surgical specimens of patients with or without IBD and cocultured with autologous or allogeneic peripheral blood T lymphocytes. Cocultures of normal T cells and IECs derived from IBD patients resulted in the preferential activation of CD4+ T cell proliferation that was associated with significant IFN-gamma, but not IL-2, secretion. Cytokine secretion and CD4+ T cell proliferation was inhibited by pretreatment of the IBD IECs with the anti-DR MAb L243. In contrast, normal IECs stimulated the proliferation and cytokine secretion by CD4+ T cells to a significantly lesser degree than IBD IECs. Furthermore, blockade of human leukocyte antigen-DR had a lesser effect in the normal IEC-CD4+ T cell cocultures. We conclude that IECs can contribute to the ongoing CD4+ T cell activation seen in IBD. We suggest that the apparent differences between the secreted levels of IFN-gamma indicate that it may play a dual role in intestinal homeostasis, in which low levels contribute to physiological inflammation whereas higher levels are associated with an uncontrolled inflammatory state.

Barley and rye prolamins induce an mRNA interferon-gamma response in coeliac mucosa

BACKGROUND

In coeliac disease, wheat, barley and rye are traditionally excluded in the gluten-free diet. However, few studies have examined the small intestinal immune response to barley and rye.

AIM

To investigate the immunogenicity of barley and rye prolamins (hordein and secalin respectively) in comparison with wheat gliadin.

METHODS

Duodenal biopsies from 22 coeliac patients and 23 disease controls were cultured for 4 h with gliadin, hordein or secalin and compared with culture medium alone. Proinflammatory cytokines, interferon-gamma and interleukin-2, were quantified by TaqMan polymerase chain reaction and enzyme-linked immunosorbent assay.

RESULTS

Hordein caused the greatest increase in interferon-gamma mRNA in coeliac patients (median: 3.3-fold) in comparison with control subjects (median: 0.28-fold, P < 0.085). Secalin and gliadin induced similar levels of interferon-gamma mRNA with median fold-changes of 3.4 and 2.8, respectively, in coeliac patients in comparison with 1.6- and 1.1-fold increases in control subjects (P < 0.294 and P < 0.105, respectively). The median fold-changes for interleukin-2 mRNA did not differ between coeliac patients and controls. Cytokine protein was not upregulated.

CONCLUSION

The findings of this study provide evidence that barley and rye cause immune activation in the mucosa of coeliac patients and support the practice that barley and rye should be excluded from the gluten-free diet.

Quantitative measurement of cytokine mRNA in inflammatory bowel disease: relation to clinical and endoscopic activity and outcome

OBJECTIVE

The objective of this study was to quantitatively determine cytokine mRNA expression in inflammatory bowel disease under different clinical conditions including active disease, remission or an impaired response to a glucocorticoid (GC) therapy.

METHODS

Mucosal biopsies were taken from 33 patients with ulcerative colitis (UC), 21 patients with Crohn's disease (CD) and 11 controls. Peripheral blood mononuclear cells (PBMNC) were isolated from 24 CU patients, 18 CD patients and 11 controls. Cytokine-mRNA [interleukin (IL)-1beta, IL-2, IL-4, IL-6, IL-10, interferon gamma (IFN-gamma), tumour necrosis factor alpha (TNF-alpha)] expression was measured by quantitative reverse transcriptase-polymerase chain reaction in biopsies and PBMNC, and correlated to endoscopic findings, clinical activity and outcome after 6 months GC therapy.

RESULTS

IL-1beta, IL-6 and TNF-alpha were the largely dominating cytokines. In contrast to IL-1beta and TNF-alpha-, IL-6 expression was restricted to inflamed mucosa and correlated with the clinical activity and C-reactive protein levels in cases of pancolitis ulcerosa. TNF-alpha was elevated in CD even in endoscopic normal tissue. IL-2 and IFN-gamma were downregulated in PBMNC from CD and UC. No Th1 or Th2 specificity could be detected. Cytokine mRNA levels did not correlate with the response to a GC therapy.

CONCLUSION

IL-6 sharply distinguishes between inflamed and non-inflamed mucosa, and is therefore a suitable marker of intestinal inflammation. Its selective expression in the inflammatory site makes it an interesting target for future therapeutic strategies. TNF-alpha overexpression even in remission suggests a key role of this cytokine in CD pathogenesis and is possibly a feature that allows one to differentiate CD from UC.

Reduced susceptibility to dextran sulphate sodium-induced colitis in the interleukin-2 heterozygous (IL-2) mouse

Summary Mice homozygous for an inactivation of the interleukin-2 (IL-2) gene develop a T-cell dependent colitis. Heterozygous (IL-2+/-) mice are clinically healthy but have been shown to express reduced levels of IL-2 in the colon. Splenocytes from the IL-2+/- mice had a poorer proliferative response to polyclonal T-cell activation and these mice have reduced numbers of intestinal regulatory T cells (CD4+ CD25+ cells) when compared to wild type mice. When exposed to dextran sulphate sodium (DSS) IL-2+/- mice showed a markedly reduced susceptibility to DSS-induced colitis. While DSS treatment caused a marked increase in both CD4+ and CD8+ colonic T cells expressing increased levels of IL-2, IL-4, and IL-10 in wild type mice none of these changes were seen in IL-2+/- mice. On the contrary, cytokine expression in intestinal T cells of IL-2+/- mice was actually reduced after DSS treatment. These results suggest that reduced levels of IL-2 leads to attenuated activation and function of intestinal T cells in IL-2+/- mice and a failure to react adequately to DSS exposure.

Over-expression of interleukin 10 in mucosal T cells of patients with active ulcerative colitis

Ulcerative colitis (UC), a chronic inflammatory bowel disease, exhibits pronounced increase of T lymphocytes in the inflamed mucosa. To understand the role of intestinal T lymphocytes in the pathogenesis of UC their cytokine production in the mucosa was analysed. Intestinal T lymphocytes of UC, Crohn's disease and control patients were analysed for cytokine mRNA levels by real-time quantitative reverse transcription-polymerase chain reaction (RT-PCR) directly after isolation without in vitro stimulation. Frequencies of cytokine positive cells were determined in UC and control colon by immunomorphometry. T lymphocytes in normal colon expressed interleukin (IL)-2, interferon (IFN)-gamma, tumour necrosis factor (TNF)-alpha and transforming growth factor (TGF)-beta1, but not IL-4, IL-5 or IL-10. In UC, a highly significant increase in IL-10 mRNA levels in T lymphocytes and an increased frequency of IL-10 positive cells was seen in colon. IL-10 mRNA levels were also elevated in T lymphocytes of the non-inflamed ileum and correlated with disease activity at both locations. CD4+ T lymphocytes were the major source of IL-10 mRNA. IL-2, IFN-gamma and TNF-alpha mRNA levels were decreased in colonic T lymphocytes, and virtually no IL-2, IFN-gamma, TNF-alpha or TGF-beta positive cells were detected in basal lymphoid aggregates. However, scattered IL-10 positive cells were found here. Lamina propria outside the aggregates contained IL-10-, IFN-gamma, TNF-alpha and TGF-beta but not IL-2 positive cells. T cells of UC patients did not express IL-4 or IL-5. Taken, together the data suggest a generalized activation of IL-10 producing CD4+ T cells along the intestine of UC patients. The local environment seems to determine the biological consequences of elevated IL-10.

DNA variants in cytokine and NOD2 genes, exposures to infections and risk for Crohn's disease

The incidence and prevalence of Crohn's disease (CD) among children in developed countries is increasing. Although extensive progress has been made in the elucidation of the pathogenesis of the disease, its mechanism remains unknown. CD is likely to be the result of a complex interplay of both genetic and environmental factors (G x E). However, the specific elements underlying these interactions have not been defined. We propose that the underlying pathology of CD may be related to interactions between infections acquired either during intrauterine life and/or early childhood and DNA variants in the cytokine and the NOD2 genes. DNA variants in the latter could confer susceptibility by altering immune development and response to infectious agents. We present a molecular and epidemiological perspective on possible mechanisms underlying G x E. Investigating these and other pathways will be paramount for the appropriate identification of susceptible populations, so that preventive and/or therapeutic interventions could be adequately targeted.

Paradoxical coexpression of proinflammatory and down-regulatory cytokines in intestinal T cells in childhood celiac disease

BACKGROUND & AIMS

Specific T-lymphocyte reactions are central in the pathogenesis of celiac disease, an inflammatory small-bowel enteropathy caused by a permanent intolerance to gluten. To delineate local T-lymphocyte responses to gluten, the cytokine expression in jejunal T lymphocytes of pediatric celiac patients with active disease, i.e., untreated and gluten-challenged celiac patients, was determined and compared with that of treated, symptom-free celiac patients and controls.

METHODS

Biopsy samples were collected from celiac patients and controls. Intraepithelial and lamina propria T lymphocytes were isolated separately, and the cytokine messenger RNA levels were determined by using quantitative real-time reverse-transcription polymerase chain reaction. Interferon (IFN)-gamma and interleukin (IL)-10 were determined at the protein level by immunohistochemistry.

RESULTS

Active celiac disease was characterized by distortions in cytokine expression by T lymphocytes, with highly significant increases of IFN-gamma and IL-10 but no concomitant increases in tumor necrosis factor alpha, transforming growth factor beta1, or IL-2 and no induction of IL-4. A marked shift of IFN-gamma and IL-10 production from the lamina propria to the epithelium was characteristic of active celiac disease, and as many as one fourth of the intraepithelial lymphocytes expressed IFN-gamma. Intraepithelial T lymphocytes in treated, symptom-free celiac patients still had increased IFN-gamma levels compared with controls.

CONCLUSIONS

In celiac patients, gluten intake seems to cause an overreaction in intraepithelial T lymphocytes, with uncontrolled production of IFN-gamma and IL-10. This may cause both recruitment of intraepithelial lymphocytes and a leaky epithelium, leading to a vicious circle with amplified immune activity and establishment of intestinal lesions.

Cytokine mRNA expression pattern in horses with large intestinal disease

The aim of this study was to investigate cytokine expression patterns in the large intestinal mucosa of horses, particularly in diseases associated with inflammation. Many cases of equine colitis remain without a definitive diagnosis and survival rates are poor. In humans, colitis is associated with increased expression of pro-inflammatory cytokines. To examine if similar responses occur in horses, we investigated il -2, il -4, il -5, il -10, tnfalpha, ifngamma and tgfbeta messenger rna expression in large intestinal mucosa. Samples were obtained from animals with large intestinal disease (n=15) or from horses which had different levels of cyathostomin infection (n=9) and analysed by reverse transcription-polymerase chain reaction. il -2 was detected at all sites, whilst il -4 was detected at all but one site. The presence of il -10, il -5, ifngamma and tgfbeta varied with no significant differences amongst groups (P>0.4). Detection of tnfalpha was significantly different between the group of horses that had infiltrative inflammatory bowel disease and those with larval cyathostominosis (P=0.028) and those that were helminth negative (P=0.014). These results indicate a possible role for tnfalpha in the pathogenesis of equine infiltrative inflammatory bowel disease.

Suppressive effects of cyclosporine A on neutrophils and T cells may be related to therapeutic benefits in patients with steroid-resistant ulcerative colitis

An intravenous infusion of cyclosporine A (CsA) shows clinical benefits in patients with steroid-resistant ulcerative colitis (UC). To clarify its mechanisms, we investigated the ability of CsA to inhibit the functions of neutrophils and T cells. The cytotoxic activity by mucosal T cells was analyzed by anti-CD3-triggered cytotoxicity after lamina propria mononuclear cells were cultured with recombinant interleukin (IL)-2. The chemotactic response, the generation of superoxide, and the production of chemokines, IL-8, and macrophage inflammatory protein-1alpha by neutrophils were examined using a multiple-well chamber assay, a chemiluminescence method, and an enzyme-linked immunosorbent assay (ELISA), respectively. Mucosal chemokine activity was determined by an ELISA using the organ culture supernatant of mucosal biopsy tissues. Pretreatment with CsA caused consistent inhibitions of cytotoxic activity by mucosal T cells and chemotactic migration, superoxide generation, and chemokine production by neutrophils mostly in a dose-dependent manner. In patients who received an intravenous infusion of CsA, mucosal chemokine activity decreased after therapy in parallel with decreases in the numbers of neutrophils and mononuclear cells in the biopsy tissues. These results suggest that suppressive effects of CsA on neutrophils and T cells may be related to therapeutic benefits in patients with steroid-resistant UC.

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.

B2 microglobulin: is it a reliable marker of activity in inflammatory bowel disease?

OBJECTIVES

The aims of this study were to investigate a possible positive correlation between B2-microglobulin (B2-M) serum levels and the severity and activity of inflammatory bowel disease (IBD); and to examine whether B2-M levels reflect IBD extent.

METHODS

We examined B2-M serum levels in 87 ulcerative colitis (UC) patients, 74 with Crohn's disease (CD) and 68 control subjects, using an enzymatic method. The reliability of the measuring method was assessed by evaluating serum B2-M in 18 patients suffering from chronic renal failure (CRF). The severity and activity of IBD was estimated using the van Hees Activity Index and the True-love-Witts criteria for CD and UC patients respectively. Endoscopic evaluation for UC patients was done according to Baron's et al. classification; Riley's et al. criteria were used for histological evaluation.

RESULTS

B2-M serum levels were significantly increased in all CD patients except those in remission. After 6 months treatment a second blood sample taken from CD patients with initially elevated B2-M levels proved to be compatible with CD severity at that time. Such a positive correlation was not assessed in UC patients; therefore, a second blood sample was considered unnecessary. Furthermore, CD patients with pancolitis, ileal-caecal, or small intestinal disease had higher B2-M levels than those with left-sided, anal, or perianal disease.

CONCLUSIONS

B2-M serum levels could prove to be a useful marker in assessing not only the activity, severity, and extent of CD but the treatment efficacy as well.

Increased serum levels of eotaxin in patients with inflammatory bowel disease

BACKGROUND

The CC-chemokines eotaxin and eotaxin-2, produced by epithelial and phagocytic cells, are potent and selective chemoattractants for eosinophils and basophils. The eosinophil is a potent inflammatory cell thought to play an important role in the pathogenesis of inflammatory bowel disease (IBD). In this study we investigated the serum concentrations of eotaxin and eotaxin-2 in patients with Crohn disease and ulcerative colitis.

METHODS

Thirty-one patients with Crohn disease, 35 patients with ulcerative colitis and 41 control patients were studied. Eotaxin and eotaxin-2 serum levels were measured with solid phase sandwich enzyme-linked immunosorbent assays.

RESULTS

Significantly increased serum eotaxin levels were observed in both patients with Crohn disease (289.4+/-591.5 pg/ml) and ulcerative colitis (207.0+/-243.4 pg/ml) when compared with controls (138.0+/-107.8 pg/ml) (P < 0.01). Moreover, patients with active Crohn disease and ulcerative colitis showed significantly higher serum eotaxin levels than patients with quiescent disease (434.0+/-776.8 pg/ml versus 113.8+/-65.4 pg/ml in Crohn disease and 295.7+/-337.1 versus 121.2+/-91.9 pg/ml in ulcerative colitis, P < 0.05). In contrast, there was no significant difference in eotaxin-2 serum levels among patients with Crohn disease (863.5+/-448.2 pg/ml), ulcerative colitis (1028.3+/-431.4 pg/ml) and controls (981.4+/-539.4 pg/ml).

CONCLUSIONS

Eotaxin is significantly increased in serum of patients with active Crohn disease and ulcerative colitis, suggesting that this cytokine may play a role in the pathogenesis of IBD.

Prostaglandin E2 stimulates motilin release via a cholinergic muscarinic pathway in the dog

Prostaglandins are well known to be widely distributed in mammalian gastrointestinal tissues and to play a role in the regulation of gastrointestinal hormones and contractions. The present study was undertaken to determine whether prostaglandins have an effect on the endogenous release of motilin in the dog. In six conscious dogs, gastrointestinal contractions were monitored by means of chronically implanted force transducers. Prostaglandin E2 (PGE2; 3, 10, 30 microgram kg-1) was given intravenously during the interdigestive phase I period with or without a muscarinic or nicotinic receptor antagonist. Blood samples were collected from 10 min before, to 30 min after, prostaglandin injection. Indomethacin (5 mg kg-1) was given intravenously to investigate the effect of endogenous prostaglandins on motilin release. PGE2 significantly stimulated motilin release but not gastric contractions. Atropine, but not hexamethonium, blocked PGE2-induced motilin release. Motilin release in response to PGE2 was significantly increased by pretreatment with hexamethonium. Indomethacin inhibited the cyclic release of motilin and gastric phase III contractions. We conclude that PGE2 appears to stimulate motilin release via cholinergic muscarinic pathways, and nicotinic receptors modulate this reaction. PGE2 may be involved in part in the regulation of the cyclic release of motilin and the occurrence of gastric phase III.

Selective resistance of mucosal T-cell activation to immunosuppression in Crohn's disease

BACKGROUND & AIMS

The inappropriately high state of T-cell activation found in Crohn's disease could be due to failure to respond to inhibitory signals. We tested the hypothesis that Crohn's disease mucosal T-cells are resistant to the immunosuppressive action of interleukin4.

PATIENTS

Patients with Crohn's disease, ulcerative colitis, and other malignant and non-malignant conditions undergoing bowel resection.

METHODS

The effect of interleukin-4 on lamina propria mononuclear cells from Crohn's disease, ulcerative colitis and control mucosa was assessed on various T-cell functions: interleukin-2-induced cytotoxicity, soluble interleukin-2 receptor and interleukin-2 production, and expression of mRNA for interleukin-2R and interferon-gamma.

RESULTS

Cytotoxicity of control and ulcerative colitis cells was markedly decreased by interleukin-4, whereas Crohn's disease cells failed to be inhibited. Addition of interleukin-4 to interleukin-2-stimulated cultures decreased soluble interleukin-2R production significantly less in Crohn's disease and ulcerative colitis than control cells. In the same cultures, residual levels of interleukin-2 were significantly increased in control and ulcerative colitis, but not Crohn's disease cultures. Finally, Crohn's disease cells were significantly more resistant to interleukin-4-mediated inhibition of spontaneous and interleukin-2-induced expression of interleukin-2Ralpha and interferon-gamma mRNA compared to control cells.

CONCLUSIONS

The effector function, receptor expression and cytokine production of Crohn's disease mucosal T-cells are resistant to interleukin4-mediated inhibition. Failure to respond to down-regulatory signals may contribute to persistent T-cell activation and chronicity of inflammation in Crohn's disease.

Cytokines and inflammatory bowel disease: a review

The etiology and pathogenesis of inflammatory bowel disease (IBD) remains an area under intense investigation. Cytokine secretion, which is important in the regulation of normal gastrointestinal immune responses, appears to be dysregulated in IBD. In Crohn's disease, there appears to be an excessive T(H)1 T-cell response to an antigenic stimulus, leading to increased levels of proinflammatory cytokines, such as interferon-gamma (IFN-gamma), interleukin (IL)-12, IL-1, IL-6, and tumor necrosis factor-alpha (TNF-alpha). In ulcerative colitis, a T(H)2 T-cell response appears to be the pathological process responsible for the inflammatory disease. New and innovative therapeutic strategies targeting cytokines, such as TNF-alpha, are producing some promising results in animal and human studies. As more is learned about the complex cytokine interactions in IBD, more effective treatments will undoubtedly ensue.

Resistance of Crohn’s Disease T Cells to Multiple Apoptotic Signals Is Associated with a Bcl-2/Bax Mucosal Imbalance

Crohn’s disease (CD) is a condition characterized by excessive numbers of activated T cells in the mucosa. We investigated whether a defect in apoptosis could prolong T cell survival and contribute to their accumulation in the mucosa. Apoptotic, Bcl-2+, and Bax+ cells in tissue sections were detected by the TUNEL method and immunohistochemistry. T cell apoptosis was induced by IL-2 deprivation, Fas Ag ligation, and exposure to TNF-α and nitric oxide. TUNEL+ leukocytes were few in control, CD, and ulcerative colitis (UC) mucosa, with occasional CD68+ and myeloperoxidase+, but no CD45RO+, apoptotic cells. Compared with control and UC, CD T cells grew remarkably more in response to IL-2 and were significantly more resistant to IL-2 deprivation-induced apoptosis. CD T cells were also more resistant to Fas- and nitric oxide-mediated apoptosis, whereas TNF-α failed to induce cell death in all groups. Compared with control, CD mucosa contained similar numbers of Bcl-2+, but fewer Bax+, cells, while UC mucosa contained fewer Bcl-2+, but more Bax+, cells. Hence, the Bcl-2/Bax ratio was significantly higher in CD and lower in UC. These results indicate that CD may represent a disorder where the rate of T cell proliferation exceeds that of cell death. Insufficient T cell apoptosis may interfere with clonal deletion and maintenance of tolerance, and result in inappropriate T cell accumulation contributing to chronic inflammation.

Effector and regulatory lymphoid cells and cytokines in mucosal sites

In this review, I hope to have highlighted that cytokines are of crucial importance in the normal homeostasis of the gut immune system, the interactions of the gut immune system with enteric antigens and also in tissue injury associated with IBD. There is evidence from a number of different systems that the response to nominal non-replicating antigens, administered nasally or orally, is skewed towards a non-Th1 type of response. To say that the response is Th2, Th3 or Tr is premature. IL-10 and TGF beta seem to be important in downregulating potentially tissue-damaging Th1 responses to the normal flora and possibly food antigens. However, it need to be seen whether the mouse results also apply to humans. A consistent pattern in disease states, whether it be human or mouse, is an exaggerated Th1 type response with excess local production of IFN-gamma and TNF alpha, and its association with tissue injury. An important question to address is whether this represents a switch from the Th2, Th3, or Tr pathway towards a Th1 pathway, or whether the Th1 pathway is in fact always present in the gut, but is kept in check and non-pathogenic by regulatory cells. Equally important is the need to discover where regulation occurs: is it in the PP or the lamina propria? Intriguing results from Kronenberg and colleagues have shown that SCID mice reconstituted with CD45RBhi or CD45RBlo cells show no difference in the re-population of the gut prior to disease (ARANDA et al. 1997). The reason for colitis developing in those mice reconstituted with CD45RBhi cells is therefore more complex than merely differential re-population kinetics. No matter what the outcome is, these and other related questions dealing with the induction and expression of mucosal T-cell responses are going to produce some surprises in the next few years.

Cytokine production from colonic T cells in patients with ulcerative colitis with and without primary sclerosing cholangitis

PURPOSE

Only five percent of all patients with ulcerative colitis develop primary sclerosing cholangitis. T cells accumulate at the sites of the colonic and bile duct inflammation in both ulcerative colitis and primary sclerosing cholangitis. T helper cell populations comprise functionally distinct subsets characterized by the cytokines they produce. Several alterations in cytokine production have been described in patients with ulcerative colitis. The aim of this study was to investigate possible differences in T helper subsets and cytokine production in peripheral blood and colonic mucosa among ulcerative colitis patients with and without primary sclerosing cholangitis.

METHODS

Eleven patients with primary sclerosing cholangitis and extensive ulcerative colitis, 11 patients with extensive ulcerative colitis and no liver disease, and 5 patients without any history of liver disease who underwent routine colonoscopy because of previous polypectomy were included in the study. Colonoscopy with multiple biopsies was performed on all patients. Lamina propria mononuclear cells and peripheral blood mononuclear cells were isolated. A modified version of solid-phase enzyme-linked immunospot assay was used for the separate counting of cells producing interferon-gamma, interleukin-2 (T helper 1), and interleukin-4 (T helper 2).

RESULTS

No differences in spontaneous production of cytokines from peripheral blood mononuclear cells was found among the three groups. Patients with primary sclerosing cholangitis compared with patients with ulcerative colitis without liver disease showed a significant increase in the number of cells secreting interferon-gamma after purified protein derivative stimulation (P < 0.02). More cells secreting interferon-gamma were found in the two ulcerative colitis groups than in the cell populations from healthy controls (P < 0.03). The number of cells secreting interferon-gamma in the primary sclerosing cholangitis group was significantly lower than in the ulcerative colitis group without liver disease (P < 0.04). The number of cells secreting interleukin-4 was lower in the primary sclerosing cholangitis group than among the patients with ulcerative colitis only (P = 0.05).

CONCLUSION

Isolated lymphocytes from colonic mucosa differ in cytokine production in patients with ulcerative colitis with and without primary sclerosing cholangitis.

Hemophagocytic syndrome associated with fulminant ulcerative colitis and presumed acute pancreatitis

We herein report a case of hemophagocytic syndrome that developed in a 25-yr-old man with fulminant ulcerative colitis and presumed acute pancreatitis. Physical examination on admission showed a chronically ill, delirious patient with an upper abdominal mass. Peripheral blood showed progressive pancytopenia and bone marrow aspirate smears revealed hypocellular bone marrow with an increase of histiocytes showing prominent hemophagocytosis. Plain abdominal radiography revealed toxic megacolon. Both ultrasound and computed tomography showed the enlargement of the pancreas, thus indicating presumed acute pancreatitis. No apparent neoplasms or viral or bacterial infections, which are normally reported to be the cause of hemophagocytic syndrome, were detected. The patient was successfully treated with high doses of prednisolone and gamma-globulin.

Interleukin 15 activity in the rectal mucosa of inflammatory bowel disease

BACKGROUND & AIMS

Interleukin (IL)-15 has been found to share many immunoregulatory activities in lymphocytes with IL-2. The aim of this study was to investigate IL-15 activity in organ cultures, localization of IL-15 messenger RNA (mRNA), and proliferation of lamina propria mononuclear cells (LPMCs) in response to recombinant IL-15 using the mucosal tissues obtained from patients with inflammatory bowel disease (IBD).

METHODS

The contents of IL-15, tumor necrosis factor alpha, and IL-2 in the culture supernatant of the rectal mucosal tissues were determined by an enzyme-linked immunosorbent assay. Expression of IL-15 mRNA was analyzed by in situ hybridization, and proliferative response of LPMCs to recombinant IL-15 was determined by [3H]thymidine incorporation into DNA.

RESULTS

Significantly greater IL-15 activity was detected in active IBD, and this elevation was also observed in inactive ulcerative colitis. In contrast, greater tumor necrosis factor alpha activity was observed only in active IBD, and IL-2 was not detected in organ cultures. In situ hybridization showed IL-15 mRNA in macrophages and epithelial cells in active IBD specimens, and recombinant IL-15 induced a dose-dependent proliferative response in LPMCs.

CONCLUSIONS

Mucosal IL-15 may be involved in the pathogenesis of IBD as one of the important mediators in activation of mucosal immune cells.

Therapeutic effects of interleukin-4 gene transfer in experimental inflammatory bowel disease

Inflammatory bowel disease (IBD) is characterized by altered immunoregulation and augmented intestinal synthesis of nitric oxide. The purpose of this study was to determine the effects of exogenous IL-4, introduced by a recombinant human type 5 adenovirus (Ad5) vector, on the tissue injury associated with an experimental model of colonic immune activation and inflammation. Colitis was induced in rats by the intrarectal administration of trinitrobenzene sulfonic acid (TNB) dissolved in 50% ethanol, and control rats received saline via the same route. 1 h later, all rats were randomized into two groups. The first group was injected intraperitoneally (ip) with 3.0 x 10(6) plaque forming units (PFUs) of Ad5 transfected with murine interleukin-4 (Ad5IL-4) and the second group was injected ip with the same amount of Ad5 expressing the Escherichia coli Lac Z gene (Ad5LacZ). One-half of the colitic and control rats were injected again with 3.0 x 10(6) PFUs of Ad5IL-4 or Ad5LacZ on day 3 of the 6-d study. When introduced once or twice via the peritoneal route into control rats, Ad5LacZ was localized to the serosal lining of the peritoneal cavity, the diaphragm and the liver on day 6. One or two injections of Ad5IL-4 into rats also produced measurable levels of circulating IL-4. TNB-colitis in both Ad5LacZ-treated groups was associated with pronounced elevations in serum IFN-gamma, and mucosal ulceration of the distal colon. Myeloperoxidase and inducible nitric oxide synthase II (NOS II) synthetic activity were also increased by 30- and fivefold, respectively, above control levels in the distal colon. However, two injections of Ad5IL-4 into colitic rats caused the overexpression of IL-4, and significantly inhibited tissue damage, serum and colon IFN-gamma levels and myeloperoxidase activity in the distal colon. In addition, NOS II gene expression and NOS II nitric oxide synthesis was significantly inhibited. No therapeutic effect was observed in rats injected once with Ad5IL-4. Thus, IL-4, introduced by Ad5, is therapeutic during acute inflammation in the rat colon. The therapeutic effect of IL-4 was associated with an inhibition of inducible nitric oxide expression and a reduction in nitric oxide synthesis.

Adequacy of mucosal biopsies for evaluation of intestinal cytokine-specific mRNA. Comparative study of RT-PCR in biopsies and isolated cells from normal and inflamed intestine

Endoscopic biopsies are being increasingly utilized to investigate cytokine profiles in normal and diseased intestine. To evaluate the adequacy of mucosal biopsies as a source of cytokine-specific mRNA, we measured their content of interleukin-1 beta (IL-1 beta) and interleukin-2 (IL-2) mRNA by reverse transcription-polymerase chain reaction and compared it to that of autologous lamina propria mononuclear cells in control and inflammatory bowel disease-involved specimens. High-quality total RNA was recovered more consistently from cell isolates than from biopsies. Interleukin-1 beta mRNA was reliably detected in both cell and biopsy samples, whereas IL-2 mRNA was measurable in all lamina propria cells but not always in biopsies. Compared to controls, levels of IL-1 beta were significantly elevated in Crohn's disease and ulcerative colitis cells and biopsies, and a weak but significant correlation existed between values derived from the two sources. In contrast, only ulcerative colitis cell isolates but not biopsies contained significantly reduced concentrations of IL-2 mRNA compared to those of control and Crohn's disease samples, and no correlation was found between cell and biopsy contents. Widely different levels of cytokine-specific mRNA were present in closely adjacent biopsies, particularly for IL-2. These results suggest that mucosal biopsies are suitable to assess some but not all cytokine-specific mRNA due to variation in RNA recovery, intrinsic level of cytokine gene expression, and substantial variability of cytokine transcripts.

Elevation of interleukin-6 in inflammatory bowel disease is macrophage- and epithelial cell-dependent

Local interleukin-6 (IL-6) activity was studied using colonic mucosal tissues in inflammatory bowel disease (IBD) and inflammatory control patients. Active IBD specimens exhibited significantly higher IL-6 activity than control specimens in both cultures of isolated lamina propria mononuclear cells (LPMC) and mucosal tissues with an increased number of IL-6-producing cells. However, the activity in inactive IBD or inflammatory controls did not differ from controls. Northern blot analysis demonstrated IL-6 messenger RNA in LPMC and colonic epithelial cells isolated from active IBD specimens but not in control cells. Furthermore, immunofluorescent microscopic study of active IBD specimens showed more conspicuous staining of IL-6 in infiltrating LPMC (mostly CD68+ cells) and colonic epithelial cells. These results suggest that elevation of local IL-6 activity may be a characteristic feature of active IBD and both macrophages and colonic epithelial cells are the major cell types responsible for this phenomenon.

Cytokine messenger RNA expression and proliferation status of intestinal mononuclear cells in noninflamed gut and Crohn's disease

T-cell activation and local cytokine production probably contribute to the pathogenesis of Crohn's disease. This study investigates the proliferative status of intestinal mononuclear cells (MNC) and cytokine messenger RNA (mRNA) production in gut tissue sections from patients with Crohn's disease and noninflamed controls. mRNA in situ hybridization was performed using 33P-labelled riboprobes for human interleukin (IL)-1 beta, IL-2, IL-4, IL-5, IL-6, tumour necrosis factor-alpha and interferon-gamma. The expression of the proliferation-associated antigen Ki-67 was analysed by immunohistochemical single and double staining. Compared with controls, where proliferation of MNC and cytokine expression was restricted to mucosal lymphoid follicles, inflamed gut tissue contained increased numbers of cells expressing cytokine mRNA, most prominently IL-1 beta and IL-6, but also interferon-gamma and tumour necrosis factor-alpha. Proliferating T-cells were increased in number, and small amounts of IL-2-expressing cells were detected. IL-4 was expressed by a few cells exclusively in follicular germinal centres. IL-5 was negative. Proinflammatory cytokines are strongly expressed in situ in Crohn's disease and largely predominate over lymphokine mRNA. Our results provide in situ evidence of a local lymphocyte response in Crohn's disease with characteristics of a delayed-type hypersensitivity reaction.

Phenotypic and functional characterization of T-cell lines generated from colonoscopic biopsy specimens in patients with ulcerative colitis

Intestinal T-cell lines were generated from lamina propria mononuclear cells isolated from colonoscopic biopsies in ulcerative colitis patients and controls. In both ulcerative colitis and controls, expanded cells were constituted largely by T-cell receptor alpha beta+, CD4+, CD45RA- (helper), and CD8+, CD11b- (cytotoxic) phenotypes. T-cell receptor V beta gene usage was not significantly changed after cell expansion and no difference was observed between ulcerative colitis and controls. Ulcerative colitis cells, especially those derived from the patients with long-standing disease, showed significantly higher levels of cytotoxicity against the target cells, including those of colonic epithelial origin, and enhanced production of tumor necrosis factor-alpha and interferon-gamma after short incubation with anti-CD3 antibody. Generation of T-cell lines from colonoscopic biopsy specimens may be useful for detailed functional characterization of locally infiltrating T cells in ulcerative colitis patients.

T cell receptor repertoire and mitotic responses of lamina propria T lymphocytes in inflammatory bowel disease

Human intestinal lamina propria T lymphocytes (LPL-T) physiologically exhibit minimal proliferation in response to antigen receptor stimulation in vitro. This is thought to occur as a consequence of regulatory influences which are exerted by the mucosal microenvironment. The present study is aimed at investigating whether proliferative responses of intestinal LPL-T to antigen receptor stimulation are altered in patients with inflammatory bowel disease. Accordingly, proliferative responses of LPL-T in patients with Crohn's disease and ulcerative colitis to stimulation with CD3 MoAb plus IL-2 were examined and compared with controls. In addition, T cell receptor (TCR) repertoires of LPL-T and peripheral blood T lymphocytes were determined by indirect immunofluorescence using a panel of 11 TCR V beta specific antibodies. In most patients with inflammatory bowel disease, LPL-T showed enhanced proliferation to antigen receptor stimulation compared with controls. Moreover, perhaps as a consequence, an enhanced frequency of in vivo preactivated T cells was seen as judged from an increased spontaneous proliferative response to low concentrations of exogenous IL-2. LPL-T and peripheral blood T lymphocytes exhibited similar percentages of TCR V beta gene usage both in controls and in patients. In summary, polyclonal activation of LPL-T due to impairment of local adjustment, i.e. insufficient down-regulation of TCR/CD3-dependent signalling processes, may contribute to the pathogenesis of inflammatory bowel disease.

Treatment of inflammatory bowel disease from now to the millennium

After decades of therapeutic stasis, treatment advances are occurring in inflammatory bowel disease. Recognition that mesalazine was the active moiety of sulphasalazine has led to a number of new methods of delivering mesalazine without sulphapyridine, with improved toxicity ratios. Current attempts to deliver topical steroids directly to the large bowel have yet to be established as therapeutically effective. Immunosuppressive treatment has been used for many years but recent evidence has firmly established its value and cyclosporin has recently been added to the therapeutic armamentarium. Increasing understanding of the basic processes of inflammation has yielded targets for anti-inflammatory treatments aimed both at the processes of immune activation and of attraction by chemotaxis of neutrophils from the circulation to the lamina propria. Some of these novel treatments, which will be assessed in forthcoming years, involve large molecular weight bioengineered peptides and antibodies that are likely to be expensive and difficult to administer. Other treatment, e.g. 5-lipoxygenase or thromboxane synthesis inhibitors or platelet-activating factor antagonists, are conventional lower molecular weight compounds that are easier to produce and are orally active. It is predicted that 5-lipoxygenase inhibitors will be the next therapeutic advance in inflammatory bowel disease. Such a prediction may founder if blanket suppression of multiple inflammatory mechanisms, rather than targeted actions, is required in inflammation.

Aetiology and pathogenesis of chronic inflammatory bowel disease

While Crohn's disease and ulcerative colitis are both conditions characterized by intestinal inflammation, with some overlap in their clinical and histological features, they are essentially different in pathogenesis. Crohn's disease appears to be primarily a condition of chronic T-lymphocyte activation, with tissue damage induced by secondary macrophage activation. What activates the T-cells is unknown. In this chapter we look at the evidence for and against cell-wall deficient mycobacteria species, viral infection of vascular endothelium and luminal contents as potential mechanisms of chronic activation. In ulcerative colitis, by contrast, there is no strong evidence for T-cell activation, and humoral mechanisms predominate. While the finding of atypical anti-neutrophil cytoplasmic antibodies (P-ANCAs) may be useful in screening, the only novel pathogenetic discovery is the co-localization of a 40 kD colonic autoantibody with immunoglobulins and complement on the apical enterocyte surface. Despite the fundamental differences in initiating mechanisms, the two conditions have many 'downstream' inflammatory processes in common. We discuss the evidence for local production of cytokines, arachidonic acid metabolites and reactive oxygen and nitrogen radicals, highlighting the potential adverse consequences for intestinal vascular integrity.

Ulcerative colitis-like disease in mice with a disrupted interleukin-2 gene

Mice deficient for interleukin-2 develop normally during the first 3-4 weeks of age. However, later on they become severely compromised, and about 50% of the animals die between 4 and 9 weeks after birth. Of the remaining mice, 100% develop an inflammatory bowel disease with striking clinical and histological similarity to ulcerative colitis in humans. The alterations of the immune system are characterized by a high number of activated T and B cells, elevated immunoglobulin secretion, anti-colon antibodies, and aberrant expression of class II major histocompatibility complex molecules. The data provide evidence for a primary role of the immune system in the etiology of ulcerative colitis and strongly suggest that the disease results from an abnormal immune response to a normal antigenic stimulus.

Spontaneous development of inflammatory bowel disease in T cell receptor mutant mice

We describe the spontaneous development of inflammatory bowel disease (IBD) in several immunodeficient mouse strains created via gene targeting in embryonic stem cells. Chronic colitis was observed in T cell receptor (TCR) alpha mutant, TCR beta mutant, TCR beta x delta double mutant, or class II major histocompatibility complex (MHC) mutant mice, but not in recombination-activating gene RAG-1 mutant mice or nude mice kept in the same specific pathogen-free animal facility. This clinical pattern suggests that the disease requires the presence of B lymphocytes and the absence of class II MHC-restricted CD4+ alpha beta T cells. IBD in the mutant mice has some of the features of the human disease ulcerative colitis. Based on these results, we suggest that dysfunction of the mucosal immune system may underly the pathogenesis of some types of IBD in humans.

Interleukin-2 activity of colonic lamina propria mononuclear cells in a rat model of experimental colitis

BACKGROUND

Altered interleukin 2 (IL-2) production has been implicated in the pathogenesis of inflammatory bowel diseases.

METHODS

The temporal relationship between IL-2, prostaglandin E2 (PGE2) production, and mucosal injury was evaluated by isolated colonic lamina propria mononuclear cells (LPMC), using the trinitrobenzene sulfonic acid model of rat colitis.

RESULTS

Spontaneous LPMC IL-2 activity was significantly increased in chronic (5 weeks) but not acute (5 days) or resolved colitis groups. IL-2 activity after concanavalin A activation was highest in the groups with resolved and chronic colitis. PGE2 production was significantly increased in LPMC cultures in acute or chronic colitis as well as the ethanol control groups but not the resolved colitis group. The addition of indomethacin to LPMC cultures decreased PGE2 levels in all groups, whereas IL-2 activity increased only for the chronic and resolved colitis groups. No correlation was found between PGE2 and IL-2 production by LPMC.

CONCLUSIONS

In this experimental model, LPMC IL-2 production varied according to the severity and duration of the inflammation. Increased PGE2 production does not appear to be responsible for the IL-2 alterations in colitis.

Immune activation genes in inflammatory bowel disease

BACKGROUND

Inflammatory bowel disease is associated with enhanced activation of T cells, but the genes responsible for this state are not well characterized.

METHODS

T-cell activation genes were studied in peripheral blood and intestinal mucosal mononuclear cells of control, Crohn's disease, and ulcerative colitis patients.

RESULTS

In all groups the expression of interleukin-2 (IL-2), IL-2 receptor alpha (IL-2R alpha), and IL-2R beta messenger RNA (mRNA) was significantly higher in intestinal than circulating cells, and it correlated well with protein levels. Both IL-2R alpha and IL-2R beta mRNA were abundant in mucosal cells, suggesting that a substantial number of them displays high affinity IL-2R. This would explain why intestinal cells proliferate more, express more IL-2 transcripts, and secrete more IL-2 than peripheral cells. Inflammatory bowel disease cells produced similar or higher IL-2R alpha and IL-2R beta mRNA than controls but generated significantly lower IL-2 mRNA. Thus, the reported defect of IL-2 activity in Crohn's disease and ulcerative colitis is probably related to decreased IL-2 transcription. Crohn's disease intestinal cells had the highest expression of IL-2R gene products. This provides a mechanism for their increased response to IL-2 and supports claims that elevated soluble IL-2R alpha serum levels reflect gut T-cell hyperactivity in this disease.

CONCLUSIONS

These findings underscore the importance of T cells in mucosal immunity and indicate that abnormal T-cell activation is intimately associated to the pathogenesis of inflammatory bowel disease.