Christian Mottet

Cutting Edge: Cure of Colitis by CD4+CD25+ Regulatory T Cells

CD4+CD25+ regulatory T cells have been shown to prevent T cell-mediated immune pathology; however, their ability to ameliorate established inflammation has not been tested. Using the CD4+CD45RBhigh T cell transfer model of inflammatory bowel disease, we show that CD4+CD25+ but not CD4+CD25−CD45RBlow T cells are able to cure intestinal inflammation. Transfer of CD4+CD25+ T cells into mice with colitis led to resolution of the lamina propria infiltrate in the intestine and reappearance of normal intestinal architecture. CD4+CD25+ T cells were found to proliferate in the mesenteric lymph nodes and inflamed colon. They were located between clusters of CD11c+ cells and pathogenic T cells and found to be in contact with both cell types. These studies suggest that manipulation of CD4+CD25+ T cells may be beneficial in the treatment of chronic inflammatory diseases.

The second European evidence-based Consensus on the diagnosis and management of Crohn's disease: Special situations.

Principal changes with respect to the 2004 ECCO guidelines Ileocolonoscopy is recommended within the first year after surgery where treatment decisions may be affected (Statement 8C). Thiopurines are more effective than mesalazine or imidazole antibiotics alone in post-operative prophylaxis (Statement 8F). ### 8.1 Epidemiology of post-operative Crohns disease In the natural history of CD, intestinal resection is almost unavoidable since about 80% of patients require surgery at some stage. Surgery is unfortunately not curative as the disease inexorably recurs in many patients. The post-operative recurrence rate varies according to the definition used: clinical, endoscopic, radiological, or surgical. It is lowest when the repeat resection rate is considered, intermediate when clinical indices are used and highest when endoscopy is employed as the diagnostic tool.1–10 Data from endoscopic follow-up of patients after resection of ileo-caecal disease have shown that in the absence of treatment, the post-operative recurrence rate is around 65–90% within 12 months and 80–100% within 3 years of the operation. The clinical recurrence without therapy is about 20–25%/year.1,10 It has been demonstrated that the post-operative clinical course of CD is best predicted by the severity of endoscopic lesions. Symptoms, in fact, appear only when severe lesions are present and it is not uncommon to observe patients with fairly advanced recurrent lesions at endoscopy who remain asymptomatic.1 For these reasons, clinical indices such as the CDAI have low sensitivity at discriminating between patients with or without post-operative recurrence.11 These data mandate strategies aimed at interrupting or delaying the natural course of post-operative recurrence. Several medications have been tried in an attempt to prevent post-operative recurrence, mostly with disappointing results. The aim of this Consensus was therefore critically to evaluate the optimal strategies for the management of post-operative recurrence in CD. Most, if not all, of the evidence available deals with …

Human CD4(+)CD25(+) thymocytes and peripheral T cells have immune suppressive activity in vitro.

CD4+CD25+ T cells in mice and rats are capable of transferring protection against organ‐specific autoimmune disease and colitis and suppressing the proliferation of other T cells after polyclonal stimulation in vitro. Here we describe the existence in humans of CD4+CD25+ T cells with the same in vitro characteristics. CD4+CD8–CD25+ T cells are present in both the thymus and peripheral blood of humans (∼ 10 % of CD4+CD8– T cells), proliferate poorly in response to mitogenic stimulation and suppress the proliferation of CD4+CD25– cells in co‐culture. This suppression requires cell contact and can be overcome by the addition of exogenous IL‐2. CD4+CD25+ cells from thymus and blood were poor producers of IL‐2 and IFN‐γ, and suppressed the levels of these cytokines produced by CD4+CD25– cells. However, CD4+CD25+ PBL produced higher levels of IL‐4 and similar amounts of IL‐10 as CD4+CD25– cells. Regulatory CD4+CD25+ T cells have an activated phenotype in the thymus with expression of CTLA‐4 and CD122 (IL‐2Rβ). The fact that CD4+CD25+ regulatory T cells are present with a similar frequency in the thymus of humans, ratsand mice, suggests that the role of these cells in the maintenance of immunological tolerance is an evolutionarily conserved mechanism.

Control of intestinal inflammation by regulatory T cells.

Summary: Transfer of CD4+ T cells to immune‐deficient mice in the absence of the CD25+ subset leads to the development of colitis, indicating that regulatory cells capable of controlling a bacteria‐driven inflammatory response are present in normal mice. Cells with this function are present in the thymus as well as in the periphery of germ‐free mice, suggesting they may be reactive with self‐antigen. These cells resemble CD4+CD25+ cells that inhibit organ‐specific autoimmunity, suggesting that a similar subset of regulatory T cells may control responses to self and foreign antigens. Development of colitis is dependent on accumulation of activated CD134L+ dendritic cells (DC) in the mesenteric lymph nodes, which is inhibited by CD4+CD25+ cells, indicating that regulatory T cells may control DC activation in vivo. Whilst inhibition of T‐cell activation in vitro by CD4+CD25+ cells does not involve interleukin‐10 and transforming growth factor‐β, these cytokines are required for the suppression of colitis. It may be that control of responses that activate the innate immune system requires multiple mechanisms of immune suppression. Recently, we identified CD4+CD25+ cells with immune suppressive activity in the thymus and peripheral blood of humans, raising the possibility that dysfunction in this mechanism of immune regulation may be involved in the development of autoimmune and inflammatory diseases.

Characterization of Foxp3+CD4+CD25+ and IL-10-Secreting CD4+CD25+ T Cells during Cure of Colitis

CD4+CD25+ regulatory T cells can prevent and resolve intestinal inflammation in the murine T cell transfer model of colitis. Using Foxp3 as a marker of regulatory T cell activity, we now provide a comprehensive analysis of the in vivo distribution of Foxp3+CD4+CD25+ cells in wild-type mice, and during cure of experimental colitis. In both cases, Foxp3+CD4+CD25+ cells were found to accumulate in the colon and secondary lymphoid organs. Importantly, Foxp3+ cells were present at increased density in colon samples from patients with ulcerative colitis or Crohn’s disease, suggesting similarities in the behavior of murine and human regulatory cells under inflammatory conditions. Cure of murine colitis was dependent on the presence of IL-10, and IL-10-producing CD4+CD25+ T cells were enriched within the colon during cure of colitis and also under steady state conditions. Our data indicate that although CD4+CD25+ T cells expressing Foxp3 are present within both lymphoid organs and the colon, subsets of IL-10-producing CD4+CD25+ T cells are present mainly within the intestinal lamina propria suggesting compartmentalization of the regulatory T cell response at effector sites.

Systematic evaluation of risk factors for diagnostic delay in inflammatory bowel disease

Background: The diagnosis of inflammatory bowel disease (IBD), comprising Crohns disease (CD) and ulcerative colitis (UC), continues to present difficulties due to unspecific symptoms and limited test accuracies. We aimed to determine the diagnostic delay (time from first symptoms to IBD diagnosis) and to identify associated risk factors. Methods: A total of 1591 IBD patients (932 CD, 625 UC, 34 indeterminate colitis) from the Swiss IBD cohort study (SIBDCS) were evaluated. The SIBDCS collects data on a large sample of IBD patients from hospitals and private practice across Switzerland through physician and patient questionnaires. The primary outcome measure was diagnostic delay. Results: Diagnostic delay in CD patients was significantly longer compared to UC patients (median 9 versus 4 months, P < 0.001). Seventy‐five percent of CD patients were diagnosed within 24 months compared to 12 months for UC and 6 months for IC patients. Multivariate logistic regression identified age <40 years at diagnosis (odds ratio [OR] 2.15, P = 0.010) and ileal disease (OR 1.69, P = 0.025) as independent risk factors for long diagnostic delay in CD (>24 months). In UC patients, nonsteroidal antiinflammatory drug (NSAID intake (OR 1.75, P = 0.093) and male gender (OR 0.59, P = 0.079) were associated with long diagnostic delay (>12 months). Conclusions: Whereas the median delay for diagnosing CD, UC, and IC seems to be acceptable, there exists a long delay in a considerable proportion of CD patients. More public awareness work needs to be done in order to reduce patient and doctor delays in this target population. (Inflamm Bowel Dis 2012;)

Cohort Profile: The Swiss Inflammatory Bowel Disease Cohort Study (SIBDCS)

Background Crohn’s disease, ulcerative colitis and indeterminate colitis are the three subtypes of disease collectively known as inflammatory bowel diseases: relapsing and remitting conditions characterized by chronic inflammation which is limited to the colon in ulcerative colitis, whereas it can involve various sites in the gastrointestinal tract in Crohn’s disease. The pathogenesis of inflammatory bowel disease is currently still unclear, although humoral and cell-mediated immune system, as well as environmental [hygiene, smoking, nonsteroidal anti-inflammatory drugs (NSAIDs) use, geographic location] and genetic factors are known to be involved in the occurrence of these diseases. Patients often require continuous medication as well as one or more intestinal resections. The care of these patients is evolving rapidly with the introduction of novel therapies and treatment plans. Some of these new treatments are expensive and their efficacy is usually limited to 30–50% of patients. In the absence of markers able to predict response to specific therapies, all eligible patients currently receive several of these drugs. They are thus exposed to side-effects which contribute to the high overall cost of these therapies—half the average medical costs associated with the disease,—while only a fraction of those treated will benefit at each stage. Impact on patient quality of life is often considerable, especially because disease onset can occur already in the first or second decade of life, while patients are either in full-time education or just entering the workforce. The negative impact on social life or ability to achieve, either scholastically or professionally, can severely affect professional as well as family life. Indeed, 450% of patients with Crohn’s disease indicate that their disease has an influence on their professional and personal life. The course of the disease is often characterized by progressive worsening of the patient’s condition, with increasing frequency of hospitalization and considerable indirect costs through absenteeism and disability allowances. Disease activity is known to be influenced by psychological factors.

Extraintestinal Manifestations of Crohn’s Disease

In each case of extraintestinal manifestations of Crohn’s disease, active disease, if present, should be treated to induce remission, which may positively influence the course of most concomitant extraintestinal manifestations. For some extraintestinal manifestations, however, a specific treatment should be introduced. This latter part of disease management will be discussed in this chapter, in particular for pyoderma gangrenosum, uveitis, spondylarthropathy – axial arthropathy – and primary sclerosing cholangitis, which have also been described in quiescent Crohn’s disease. Few new drugs for the treatment of extraintestinal manifestations of Crohn’s disease have been developed in the past and only the role of infliximab has increased in Crohn’s disease-related extraintestinal manifestations. Drugs specifically aimed at this treatment, stemming from a few randomized controlled studies or case series, are sulfasalazine, 5-ASA, corticosteroids, azathioprine or 6-mercaptopurine, methotrexate, infliximab, adalimumab, etanercept and cyclosporine or tacrolimus. Unfortunately, because of the paucity of data in this field, the best evidence presented and discussed in this article for the treatment of these extraintestinal manifestations is extrapolated from patients that for the most part did not suffer from Crohn’s disease.

Locally inducible CD66a (CEACAM1) as an amplifier of the human intestinal T cell response

CD66a is an adhesion molecule member of the carcinoembryonic antigen immunoglobulin‐like family present on the surface of epithelial cells, granulocytes and IL‐2 activated T cells. We studied whether CD66a is expressed in vivo by T lymphocytes and whether it affects TCR‐mediated activation. CD66a was detected by histochemistry, flow cytometry analysis, reverse transcription PCR and Western blot on fresh colon biopsies and T cell clones. A fraction of T cells in the lamina propria express CD66a, which is induced by IL‐7 and IL‐15 cytokines. T cells express four different CD66a splice variants and at least two forms of the protein are glycosylated in a cell type‐specific manner. Triggering of CD66a on T cells with physiological ligands or with specific mAb increases TCR‐mediated lymphokine release, in an antigen dose‐independent manner. This effect requires the presence of the CD66a intracytoplasmic domain, which contains two immunoglobulin receptor family tyrosine‐based inhibitory motif‐like domains, as shown by stimulation of Jurkat cells transfected with different CD66a isoforms and is associated with increased induction of AP1 and NFκB transcription factors. These data indicate that CD66a amplifies T cell activation and thus could facilitate crosstalk between epithelial cells and T lymphocytes in intestinal immune response.

Fistulizing Crohn’s Disease

Fistulas are common in Crohn’s disease. A population-based study has shown a cumulative risk of 33% after 10 years and 50% after 20 years. Perianal fistulas were the most common (54%). Medical therapy is the main option for perianal fistula once abscesses, if present, have been drained, and should include antibiotics (both ciprofloxacin and metronidazole) and immunomodulators. Infliximab should be reserved for refractory patients. Surgery is often necessary for internal fistulas.