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Objective: Treatment with 5-aminosalicylic acid (5-ASA) derivatives is one of the main principles in the therapy of uncomplicated mild to moderate inflammatory bowel diseases (IBD). The beneficial effect of 5-ASA in the treatment of IBD is attributed to its anti-inflammatory and anti-oxidant properties within the inflamed gut. The aim of this study was to investigate whether 5-ASA also modulates intestinal epithelial wound repair in vitro., Material and Methods: The effects of 5-ASA on cell migration and proliferation, two key processes in mucosal healing, were studied in the non-transformed small-intestinal epithelial cell line IEC-6 using an in vitro wounding model and colorimetric MTT assays. Furthermore, the effects of 5-ASA on epithelial cell viability were determined by Trypan blue exclusion and flow cytometry-based cell cycle analysis., Results: Clinically relevant concentrations of 5-ASA caused a significant dose-dependent enhancement of epithelial cell migration and proliferation in vitro. An about 2-fold enhancement of intestinal epithelial cell proliferation and migration was observed for pharmacological doses of 100 microg/ml 5-ASA. Neutralizing antibodies against TGFbeta did not modulate 5-ASA effects on IEC-6 cell proliferation and migration, indicating that the effects of 5-ASA were TGFbeta independent. Trypan blue viability tests and cell cycle analysis did not reveal any toxic or apoptotic effects of pharmacological 5-ASA concentrations on IEC-6 cells., Conclusions: 5-ASA promotes the rapid re-establishment of mucosal integrity in vitro by enhancing epithelial restitution and proliferation, suggesting that 5-ASA in addition to the well-characterized effects on the intestinal inflammatory cascade may also directly stimulate epithelial wound healing.

Although the probiotic Escherichia coli strain Nissle 1917 has been proven to be efficacious for the treatment of inflammatory bowel diseases, the underlying mechanisms of action still remain elusive. The aim of the present study was to analyze the effects of E. coli Nissle 1917 on cell cycling and apoptosis of peripheral blood and lamina propria T cells (PBT and LPT, respectively). Anti-CD3-stimulated PBT and LPT were treated with E. coli Nissle 1917-conditioned medium (E. coli Nissle 1917-CM) or heat-inactivated E. coli Nissle 1917. Cyclin B1, DNA content, and caspase 3 expression were measured by flow cytometry to assess cell cycle kinetics and apoptosis. Protein levels of several cell cycle and apoptosis modulators were determined by immunoblotting, and cytokine profiles were determined by cytometric bead array. E. coli Nissle 1917-CM inhibits cell cycling and expansion of peripheral blood but not mucosal T cells. Bacterial lipoproteins mimicked the effect of E. coli Nissle 1917-CM; in contrast, heat-inactivated E. coli Nissle 1917, lipopolysaccharide, or CpG DNA did not alter PBT cell cycling. E. coli Nissle 1917-CM decreased cyclin D2, B1, and retinoblastoma protein expression, contributing to the reduction of T-cell proliferation. E. coli Nissle 1917 significantly inhibited the expression of interleukin-2 (IL-2), tumor necrosis factor alpha, and gamma interferon but increased IL-10 production in PBT. Using Toll-like receptor 2 (TLR-2) knockout mice, we further demonstrate that the inhibition of PBT proliferation by E. coli Nissle 1917-CM is TLR-2 dependent. The differential reaction of circulating and tissue-bound T cells towards E. coli Nissle 1917 may explain the beneficial effect of E. coli Nissle 1917 in intestinal inflammation. E. coli Nissle 1917 may downregulate the expansion of newly recruited T cells into the mucosa and limit intestinal inflammation, while already activated tissue-bound T cells may eliminate deleterious antigens in order to maintain immunological homeostasis.

Background: Breakdown of tolerance against the commensal microflora is believed to be a major factor in the pathogenesis of inflammatory bowel disease (IBD). Dendritic cells (DC) have been implicated in this process in various animal models, but data on human DC in IBD are very limited., Aim: To characterise plasmacytoid DC (PDC) and myeloid DC (MDC) in patients with active versus inactive IBD and healthy controls., Patients and Methods: Peripheral blood was obtained from 106 patients (Crohn's disease (CD) n=49, ulcerative colitis (UC) n=57) and healthy controls (n=19). Disease activity was scored using the modified Truelove Witts (MTWSI) for UC and the Harvey Bradshaw severity indices (HBSI) for CD. Four colour flow cytometric analysis was used to identify, enumerate, and phenotype DC. DC from patients with acute flare ups and healthy controls were cultured and stimulated with CpG ODN 2006 or lipopolysaccharide (LPS)., Results: IBD patients in remission (PDC UC, 0.39%; CD, 0.35%; MDC-1 UC, 0.23%; CD, 0.22% of PBMC) have slightly lower numbers of circulating DC compared with healthy controls (PDC 0.41%, MDC-1 0.25% of PBMC). In acute flare ups IBD patients experience a significant drop of DC (PDC UC, 0.04%; CD, 0.11%; MDC-1 UC, 0.11%; CD, 0.14% of PBMC) that correlates with disease activity (correlation coefficients: PDC MTWSI, 0.93; HBSI, 0.79; MDC-1 MTWSI, 0.75; HBSI, 0.81). Moreover, both express alpha4beta7 integrin and display an immature phenotype. Freshly isolated PDC and MDC-1 from untreated flaring IBD patients express higher baseline levels of CD86 which increases further in culture and upon stimulation compared with healthy controls., Conclusion: IBD patients lack immature blood DC during flare ups which possibly migrate to the gut. An aberrant response to microbial surrogate stimuli suggests a disturbed interaction with commensals.

Background: CXCL8 (previously known as Interleukin-8), a member of the alpha-chemokine family of chemotactic cytokines, stimulates intestinal neutrophil activation and chemotaxis. As intestinal epithelial cells have been recently shown to produce CXCL8, the aim of this study was to identify functional activities of CXCL8 on intestinal epithelial cells., Methods: The expression of CXCL8 receptors CXCR1 and CXCR2 was assessed by RT-PCR and FACS analysis in human Caco-2 and HT-29 cells. The effects of CXCL8 on intestinal epithelial proliferation were assessed with colorimetric MTT assays and the effects on epithelial restitution with an in vitro migration model using Caco-2 and HT-29 cells., Results: While the expression of both CXCR1 mRNA and protein could be demonstrated by RT-PCR and FACS analysis in human Caco-2 and HT-29 cells, no expression of CXCR2 was observed in these cell lines. Colorimetric MTT assays revealed that CXCL8 does not modulate cell proliferation in HT-29 and Caco-2 cells. In contrast, CXCL8 significantly enhanced intestinal epithelial migration in an in vitro migration model of HT-29 and Caco-2 cells. Enhancement of intestinal epithelial cell migration by CXCL8 was partially CXCR1-dependent and TGFbeta-independent., Conclusion: CXCL8 exerts functional effects on intestinal epithelial cells that may be relevant for intestinal inflammation and mucosal healing.

Although the aetiopathogenesis of Crohn's disease and ulcerative colitis, remains unsolved, current evidence indicates that defective T-cell apoptosis and impairment of intestinal epithelial barrier function play important roles in the pathogenesis of both conditions. Without appropriate control of T-cell proliferation and death during an immune response, an inappropriate accumulation of T cells and subsequent intestinal inflammation may occur. Differences in T-cell responses between Crohn's disease and ulcerative colitis have been identified, with mucosal T-cell apoptosis being defective in Crohn's disease, but not in ulcerative colitis. Furthermore, cell cycling is considerably faster, with a vigorous clonal expansion, in Crohn's disease, whereas, in ulcerative colitis, T cells cycle normally, but have a remarkably reduced capacity to divide and expand. The elimination of excessive T cells therefore seems to be a reasonable approach to restore the gut to a physiological state or, at least, a controlled state of inflammation. The tumour necrosis factor-alpha blocker, infliximab, exerts its beneficial effects, at least in part, by the induction of apoptosis in lamina propria T cells and monocytes. In addition, repeated damage and injury of the intestinal surface is a hallmark of inflammatory bowel disease and may facilitate the entry of luminal antigens into the mammalian organism and the initiation and perpetuation of both nonspecific and specific immune responses. A better understanding of and enhancement of intestinal repair mechanisms may thus provide future approaches for the treatment of inflammatory bowel disease.

We describe two male patients with ulcerative colitis and refractory pyoderma gangrenosum including periorbital phlegmona in one case. Both patients were successfully managed with low dose oral tacrolimus (0.1 mg/kg bodyweight per day). Serum trough levels were closely monitored and maintained between 4 and 6 ng/mL. A rapid response was noted in both cases. Complete non-scarring skin restitution without side effects was accomplished in both cases. Low dose oral tacrolimus provides a valuable alternative treatment option for IBD patients with refractory pyoderma gangrenosum.

Background and Aims: As the first point of contact with enteric antigens, intestinal epithelial cells (IEC) may be key in regulating mucosal immune responses. We determined therefore if murine colonic epithelial cells (CEC) have tolerogenic or activating effects on CD4 T cells., Methods: Using a novel CEC, macrophages, and CD4 T cell coculture system, mitogen and antigen specific responses of naïve and antigen primed CD4 T cells were assessed., Results: Although a proportion of CEC express the costimulatory molecules B7.1, B7.2, CD40, and CD54, they were unable to promote mitogen or antigen driven activation of CD4 T cells, even in the presence of exogenous costimulatory signals. CD4 T cells cocultured with CEC were CD25lo and CD45RBlo and remained in the G1 phase of the cell cycle. CEC were also able to prevent CD4 T cell activation by professional antigen presenting cells. CEC mediated suppression of T cell activation was cell contact dependent and transforming growth factor beta independent., Conclusions: These observations suggest that CEC contribute to the maintenance of T cell tolerance in the gut by preventing inappropriate activation of CD4 T cells.

Current biological therapies for inflammatory bowel disease reflect the exponential advancement in understanding the human intestinal immune system and particularly the biology of intestinal inflammation over the past decade. The better understanding of the mechanisms of inflammatory bowel disease has evolved from descriptive clinical data and genetically engineered animal models. It led to great interest in a variety of new therapeutic agents and procedures with novel actions. This review will discuss the mechanisms of biologics (antibodies against pro-inflammatory cytokines, T-cell antibodies, anti-inflammatory cytokines, adhesion molecule blockers, growth factors, colony stimulating factors, fusion proteins, anti-sense oligonucleotides, hormones, immunostimulatory DNA (ISS-DNA, CpG Oligodeoxynucleotides) and parasites (Trichuris suis eggs), used in inflammatory bowel disease and summarize the available data on investigational and approved agents, and briefly touch on probiotics and extracorporeal immunomodulation (leukocyte apheresis and photoapheresis). Based on the data discussed, it appears that biologics may play an increasing role in managing inflammatory bowel disease in the near future.

Biological therapies in inflammatory bowel disease reflect the exponential advancement in understanding the human intestinal immune system and particularly the biology of intestinal inflammation during the past decade. The better understanding of the mechanisms of inflammatory bowel disease has evolved from desriptive clinical data and genetically engineered animal models. It led to great interest in the evaluation of a variety of new therapeutic agents with novel actions. This review will discuss the mechanisms of biologicals (antibodies against pro-inflammatory cytokines, T cell antibodies, anti-inflammtory cytokines, adhesion molecule blockers, growth factors, hormones, colony stimulating factors, fusion proteins, anti-sense oligonucleotides, trefoil peptides, immunostimulatory [ISS] DNA) used in the treatment of inflammatory bowel disease and summarizes the available data on established biologic therapies as well as investigational agents and briefly touch on probiotics. Based on the data discussed, it seems that biologicals will play an important role in managing inflammatory bowel disease in the near future.

Background: Oral tacrolimus, approved for the prophylaxis of organ rejection in liver or kidney transplants, has been reported to be effective in anecdotal cases of refractory inflammatory bowel disease., Aim: To evaluate the usefulness of low-dose oral tacrolimus in refractory inflammatory bowel disease., Methods: Thirty-one adult Caucasian patients with steroid-dependent (n = 15) or steroid-refractory (n = 16) inflammatory bowel disease (Crohn's disease, n = 6; ulcerative colitis, n = 23; pouchitis, n = 2) were enrolled. Tacrolimus (0.1 mg/kg body weight per day) was administered orally in 30 patients and initially intravenously in one patient (0.01 mg/kg body weight per day), aiming for serum trough levels of 4-6 ng/mL. The median treatment duration was 12 months (range, 1-137 months)., Results: Twenty-eight patients (90.3%) experienced a clinical and laboratory response and 20 (64.5%) went into remission. One ulcerative colitis patient and two Crohn's disease patients did not improve. Three ulcerative colitis patients (9.7%) were colectomized at 1, 12 and 24 months after tacrolimus initiation. In 19 of 23 patients (82.6%) taking steroids, steroids were reduced or discontinued. Side-effects included a temporary rise of creatinine (n = 3, 9.7%), tremor or paraesthesias (n = 3, 9.7%), hyperkalaemia (n = 1, 3.2%), hypertension (n = 1, 3.2%) and an opportunistic infection (n = 1, 3.2%)., Conclusion: Oral tacrolimus is safe and effective in refractory inflammatory bowel disease.

Intestinal barrier function regulates transport and host defense mechanisms at the mucosal interface with the outside world. Transcellular and paracellular fluxes are tightly controlled by membrane pumps, ion channels and tight junctions, adapting permeability to physiological needs. Food and microbial antigens are under constant surveillance of the mucosal immune system. Tolerance against commensals and immunity against pathogens require intact antigen uptake, recognition, processing and response mechanisms. Disturbance at any level, but particularly bacterial translocation due to increased permeability and breakdown of oral tolerance due to compromised epithelial and T cell interaction, can result in inflammation and tissue damage. New therapeutic approaches including probiotics and peptides to restore disrupted barrier function are evolving.

Background & Aims: The immunoregulatory properties of primary colonic epithelial cells (CECs) have not been defined. The ability of CECs from wild-type and interleukin 2-deficient (IL-2(-/-)) mice to take up a complex protein antigen and present peptides via MHC molecules to T cells was assessed and contrasted with that of primary small intestinal epithelial cells (SIECs)., Methods: Uptake of fluorescein isothiocyanate (FITC)-labeled ovalbumin (FITC-OVA) by CECs and SIECs from wild-type and IL-2(-/-) mice was measured by flow cytometry. The effect of disrupting cytoskeleton organization and metabolic activity of CEC on antigen uptake was assessed. An OVA/I-A(b)-specific CD4(+) T-cell line transfected with an NFAT-lacZ reporter gene construct was used to evaluate the ability of CECs and SIECs as well as CECs from healthy and colitic IL-2(-/-) mice to present antigen to T cells., Results: Uptake of FITC-OVA by CECs is concentration dependent, is not saturated at physiologic concentrations, and requires metabolically active cells. CECs from IL-2(-/-) mice take up significantly more antigen than those from wild-type mice. CECs are more efficient APCs than SIECs, and antigen-pulsed CECs from IL-2(-/-) mice induce the highest levels of T-cell activation., Conclusions: Primary CECs are efficient APCs for CD4 MHC class II-restricted T cells. Antigen uptake and presentation is up-regulated in animals prone to develop intestinal inflammation.

We describe a method for long-term culture of primary small intestinal epithelial cells (IEC) from suckling mice. IEC were digested from intestinal fragments as small intact units of epithelium (organoids) by using collagenase and dispase. IEC proliferated from organoids on a basement-membrane-coated culture surface and remained viable for 3 weeks. Cultured IEC had the morphologic and functional characteristics of immature enterocytes, notably sustained expression of cytokeratin and alkaline phosphatase. Few mesenchymal cells were present in the IEC cultures. IEC were also cultured from adult BALB/c mice and expressed major histocompatibility complex (MHC) class II antigens for at least 48 h in vitro. Primary IEC supported the growth of rhesus rotavirus (RRV) to a greater extent than a murine small intestinal cell line, m-IC(cl2). Cell-culture-adapted murine rotavirus strain EDIM infected primary IEC and m-IC(cl2) cells to a lesser extent than RRV. Wild-type EDIM did not infect either cell type. Long-term culture of primary murine small intestinal epithelial cells provides a method to study (i) virus-cell interactions, (ii) the capacity of IEC to act as antigen-presenting cells using a wide variety of MHC haplotypes, and (iii) IEC biology.

Epithelial cell (EC) injury is a feature of all inflammatory bowel disorders (IBD). Although the mechanisms of EC injury are incompletely understood, it has been proposed that T-cell-mediated cytotoxicity and production of inflammatory cytokines are involved. This hypothesis was tested using the interleukin 2-deficient (IL2-/-) mouse model of IBD and cultures of primary colonic EC to determine if abnormal cytokine production or cytotoxicity by colonic T cells cause EC injury. Although capable of cell-mediated killing of allogeneic target cells, IL2-/- colonic T cells were unable to lyse syngeneic colonic EC. During disease progression, large numbers of IL4, TNF-alpha, and IFN-gamma-producing CD4+ and CD8+ cells accumulated within the intraepithelial spaces and lamina propria of the colon of IL2-/- mice. Although colonic EC expressed receptors for IFN-gamma and TNF-alpha, these cytokines did not adversely affect EC viability or growth in vitro consistent with these cytokines not being the primary mediators of EC injury in IBD. Our novel colonic EC culture system provides an in vitro accessible system in which to investigate further the nature of EC-lymphocyte interactions.

We report an 18-year old woman with surgically proven primary hyperparathyroidism (pHPT) and normal intact parathyroid hormone (iPTH) serum levels. The reason for this rare biochemical presentation are possible biologically active amino-terminal parathyroid hormone polypeptide fragments not detected by the widely used two-site immunoradiometric parathyroid hormone assay (PTH IRMA). Diagnosis and therapy of primary hyperparathyroidism therefore should not exclusively rest on the finding of hypercalcemia coupled with an elevated iPTH level.

This review discusses the mechanisms and pathways of immune cell-mediated intestinal inflammation and tissue injury in inflammatory bowel disease (IBD). Our lack of understanding of how the mucosal immune system normally functions to maintain the balance between tolerance and immunity to innumerable dietary and bacterial constituents of the gut is perhaps the biggest obstacle to understanding the cause(s) of IBD, and to developing more effective treatments for these debilitating disorders. Evidence that abnormalities or disruptions in the interaction of immune cells and gut bacteria can trigger or contribute to changes in the composition, regulation and activity of the mucosal immune system that result in inflammatory immune responses and tissue injury are discussed. Based upon these studies, we propose a model to explain how a breakdown in regulation and failure to resolve immune responses in the gut mucosa results in persistent activation of T lymphocytes and other immune cells and the uncontrolled production of soluble inflammatory mediators that directly or indirectly produce the pathophysiological changes and tissue injury characteristic of IBD.

IL-2-deficient (IL-2(-/-)) mice develop disorders of the hemopoietic and immune systems characterized by anemia, lymphocytic hyperplasia, and colitis. The mechanisms responsible for these abnormalities remain unclear. To investigate the underlying basis of autoimmunity, the particular role of commensal gut flora in the initiation of colitis, and the role of IL-2 in the development of intestinal intraepithelial lymphocytes (iIEL), we evaluated IL-2(-/-) mice reared and maintained under gnotobiotic (germfree) conditions. By 8 wk of age, 80% (20 of 25) of germfree IL-2(-/-) mice show signs of disease, including anemia, disturbances in bone marrow hemopoietic cells, lymphocytic hyperplasia, and generalized autoimmunity, similar to those seen in specific pathogen-free (SPF) IL-2(-/-) mice. In striking contrast to SPF IL-2(-/-) mice, germfree IL-2(-/-) mice do not develop colitis. However, the numbers of gammadelta+ and TCR alphabeta+ CD8 alphaalpha+ iIELs are reduced, and in lethally irradiated SPF IL-2(+/+) mice, reconstituted with IL-2(-/-) bone marrow TCR gammadelta+ iIELs fail to develop, consistent with an important role of IL-2/IL-2R signaling in the development of gammadelta iIELs. Consequently, our findings demonstrate that the colitis seen in SPF IL-2(-/-) mice depends upon the presence of intestinal bacterial flora and that environmental Ags are not responsible for the anemia and extraintestinal lymphoid hyperplasia that occur in IL-2(-/-) mice. Thus, germfree IL-2(-/-) mice represent a unique system in which the role of IL-2 deficiency in hemopoietic and immune system disorders can be investigated in dissociation from complications that may arise due to colitis.