Reciprocal changes of Foxp3 expression in blood and intestinal mucosa in IBD patients responding to infliximab

Restoration of Foxp3+ Regulatory T-cell Subsets and Foxp3- Type 1 Regulatory-like T Cells in Inflammatory Bowel Diseases During Anti-tumor Necrosis Factor Therapy

BACKGROUND

A defect in regulatory T cells (Tregs) may be involved in the pathogenesis of inflammatory bowel diseases (IBD). Several subsets of human Foxp3+ Tregs (activated and resting Tregs) have now been identified, as well as an IL-10 and IFN-γ double producing Foxp3 type 1 regulatory-like T cell (Tr1L). We have quantified these Tregs in patients with active IBD and during therapy with infliximab (IFX).

METHODS

Blood samples were obtained from healthy controls (n = 54) and patients with active IBD, either before (n = 62) or during IFX therapy (n = 75). Tregs were identified by immunofluorescent staining and flow cytometry analysis. Resting and activated Foxp3+ Tregs can be differentiated from Foxp3+ effector T cells (Foxp3+ Teff) by the expression of CD45RA. Tr1L are identified as CD4+CD45RA-CD25-CD127-Foxp3- T cells.

RESULTS

A numerical deficiency of circulating resting Tregs, activated Treg cells, and Tr1L was documented in patients with active IBD. Baseline levels of these Treg subsets predicted clinical responses to IFX. We documented an upregulation of all 3 subsets during IFX therapy. Moreover, after therapy, significant differences in Treg subsets were seen between responders and nonresponders to IFX. Restoration of Tregs correlated with the clinical and biological response to IFX therapy. Trough serum levels of IFX positively correlated with the proportion of activated Treg cells and Tr1L during therapy.

CONCLUSIONS

IFX therapy, when successful, results in upmodulation of the different types of Treg cells in the blood of patients with IBD. This effect might be relevant for understanding the mechanism of action of anti-TNF agents.

Anti-TNF-alpha loss of response is associated with a decreased percentage of FoxP3+ T cells and a variant NOD2 genotype in patients with Crohn's disease

BACKGROUND

Anti-TNF-α therapies interact with the tolerogenic response in patients with Crohn's disease, modulating inflammation. However, drug levels and the genetic background may affect this interaction.

METHODS

Patients with Crohn's disease in remission on biologic monotherapy were enrolled in this study. FoxP3+ lymphocytes, NOD2 genotype, serum cytokine, anti-TNF-α levels, and anti-drug antibodies were evaluated. Regulatory T cell response to infliximab was evaluated in vitro.

RESULTS

Fifty-seven patients were included. Thirty-nine patients (68.4%) were receiving non-intensified biologic therapy whereas 18 patients (31.6%) were under an intensified biologic schedule due to loss of response. Eleven intensified patients (61.1%) showed a variant NOD2 genotype vs 9 on non-intensified biologics (23%, p < 0.01). Percentage of FoxP3+ T cells and serum free anti-TNF-α levels were significantly higher in patients with a wild-type vs variant NOD2 genotype, either under non-intensified or intensified schedule. Increasing amounts of infliximab significantly increased the expression of FoxP3+ T cells and anti-TNF-α levels in the supernatant from wild-type NOD2 patients cultured cells whereas the induction of FoxP3+ T cells and anti-TNF-α levels in the supernatant from variant NOD2 patients cultured cells were significantly lower. TNF-α and IL-10 showed a correlation with the FoxP3+ T cell population percentage and serum levels of anti-TNF-α, irrespective of NOD2 genotype. Eight variant NOD2 patients (66.6%) vs 4 wild-type NOD2 patients (8.8%) showed a perianal phenotype (p = 0.01). A significant reduction of the percentage of FoxP3+ T cells and serum levels of anti-TNF-α was observed in patients with the associated perianal disease.

CONCLUSION

Anti-TNF-α loss of response is associated with a decreased percentage of FoxP3+ T cells and a variant NOD2 genotype in patients with CD.

Spontaneous and transgenic rodent models of inflammatory bowel disease

Inflammatory Bowel Disease (IBD) is a multifactorial disorder with many different putative influences mediating disease onset, severity, progression and diminution. Spontaneous natural IBD is classically expressed as Crohn's Disease (CD) and Ulcerative Colitis (UC) commonly found in primates; lymphoplasmocytic enteritis, eosinophilic gastritis and colitis, and ulcerative colitis with neuronal hyperplasia in dogs; and colitis in horses. Spontaneous inflammatory bowel disease has been noted in a number of rodent models which differ in genetic strain background, induced mutation, microbiota influences and immunopathogenic pathways. Histological lesions in Crohn's Disease feature noncaseating granulomatous inflammation while UC lesions typically exhibit ulceration, lamina propria inflammatory infiltrates and lack of granuloma development. Intestinal inflammation caused by CD and UC is also associated with increased incidence of intestinal neoplasia. Transgenic murine models have determined underlying etiological influences and appropriate therapeutic targets in IBD. This literature review will discuss current opinion and findings in spontaneous IBD, highlight selected transgenic rodent models of IBD and discuss their respective pathogenic mechanisms. It is very important to provide accommodation of induced putative deficits in activities of daily living and to assess discomfort and pain levels in the face of significant morbidity and/or mortality in these models. Epigenetic, environmental (microbiome, metabolome) and nutritional factors are important in IBD pathogenesis, and evaluating ways in which they influence disease expression represent potential investigative approaches with the greatest potential for new discoveries.

Expression of TIM-3, Human β-defensin-2, and FOXP3 and Correlation with Disease Activity in Pediatric Crohn's Disease with Infliximab Therapy

BACKGROUND/AIMS

This study investigated the expression of T cell immunoglobulin- and mucin-domain-containing molecule 3 (TIM-3), human β-defensin (HBD)-2, forkhead box protein 3 (FOXP3), and the frequency of CD4(+) CD25(+) FOXP3(+) regulatory T cells (Tregs) in children with Crohn's disease (CD) during infliximab therapy.

METHODS

We enrolled 20 CD patients who received infliximab treatment for 1 year. Peripheral blood and colonic mucosal specimens were collected from all CD patients and from healthy control individuals.

RESULTS

A significant difference in TIM-3 mRNA expression was evident in peripheral blood mononuclear cells and colonic mucosa between CD patients before infliximab therapy and the healthy controls (p<0.001 and p=0.005, respectively). A significant difference in HBD-2 mRNA expression was found in colonic mucosa between CD patients before infliximab therapy and the healthy controls (p=0.013). In the active phase of CD, at baseline, the median percentage of T cells that were CD25(+) FOXP3(+) was 1.5% (range, 0.32% to 3.49%), which increased after inflixmab treatment for 1 year to 2.2% (range, 0.54% to 5.02%) (p=0.008).

CONCLUSIONS

Our study suggests that both the adaptive and innate immune systems are closely linked to each other in CD pathogenesis. And the results of our study indicate that it could be a useful therapeutic tool, where restoration of TIM-3, HBD-2 and the function of Tregs may repair the dysfunctional immunoregulation in CD.

β-Arrestin2 encourages inflammation-induced epithelial apoptosis through ER stress/PUMA in colitis

β-Arrestins (β-arrs) are regulators and mediators of G protein-coupled receptor signaling, and accumulating evidence suggests that they are functionally involved in inflammation and autoimmune diseases. However, the effect of β-arrs is unclear in inflammatory bowel disease (IBD), and the role of β-arr2 is unknown in ulcerative colitis (UC) and Crohn's disease (CD). The aim of this study is to investigate whether β-arr2 encourages inflammation-induced epithelial apoptosis through endoplasmic reticulum (ER) stress/p53-upregulated modulator of apoptosis (PUMA) in colitis. In the present study, the results showed that β-arr2 was increased in specimens from patients with UC or CD. Furthermore, a β-arr2 deficiency significantly repressed intestinal inflammation, ameliorated colitis, and alleviated mucosal apoptosis in mice. In addition, the targeted deletion of β-arr2 depressed ER stress, inhibited PUMA, and downregulated PUMA-mediated mitochondrial apoptotic signaling in colitis. β-Arr2, an important modulator of G protein-coupled receptor function, binds eIF2α to activate ER stress signaling. Furthermore, the knockdown of PUMA dramatically prevented β-arr2-induced apoptosis via alleviating ER stress in vitro. The results suggest that β-arr2 encourages inflammation-induced epithelial apoptosis through ER stress/PUMA in colitis and that β-arr2 is a potential therapeutic target for colitis.

Regulatory T-cells in autoimmune diseases: challenges, controversies and--yet--unanswered questions

Regulatory T cells (Tregs) are central to the maintenance of self-tolerance and tissue homeostasis. Markers commonly used to define human Tregs in the research setting include high expression of CD25, FOXP3 positivity and low expression/negativity for CD127. Many other markers have been proposed, but none unequivocally identifies bona fide Tregs. Tregs are equipped with an array of mechanisms of suppression, including the modulation of antigen presenting cell maturation and function, the killing of target cells, the disruption of metabolic pathways and the production of anti-inflammatory cytokines. Treg impairment has been reported in a number of human autoimmune conditions and includes Treg numerical and functional defects and conversion into effector cells in response to inflammation. In addition to intrinsic Treg impairment, resistance of effector T cells to Treg control has been described. Discrepancies in the literature are common, reflecting differences in the choice of study participants and the technical challenges associated with investigating this cell population. Studies differ in terms of the methodology used to define and isolate putative regulatory cells and to assess their suppressive function. In this review we outline studies describing Treg frequency and suppressive function in systemic and organ specific autoimmune diseases, with a specific focus on the challenges faced when investigating Tregs in these conditions.

Distinct kinetics in the frequency of peripheral CD4+ T cells in patients with ulcerative colitis experiencing a flare during treatment with mesalazine or with a herbal preparation of myrrh, chamomile, and coffee charcoal

BACKGROUND

We found the first evidence of the efficacy of a herbal treatment with myrrh, dry extract of chamomile flowers, and coffee charcoal for ulcerative colitis (UC). However, the impact of the herbal treatment on the CD4+ T-cell compartment, which is essential for both the induction of UC and the maintenance of tolerance in the gut, is not well understood.

AIM

To analyze the frequency and functional phenotype of CD4+ T cells and of immune-suppressive CD4+CD25high regulatory T cells (Tregs) in healthy control subjects, patients with UC in remission, and patients with clinical flare of UC.

METHODS

Patients in clinical remission were treated with either mesalazine or the herbal preparation for 12 months. The frequencies of whole CD4+ T cells, CD4+CD25med effector T cells, and Tregs and the expression of Foxp3 within the CD4+CD25hig Tregs were determined by flow cytometry at 6 time points. We determined the suppressive capability of Tregs from healthy control subjects and from patients in remission or clinical flare.

RESULTS

A total of 79 patients (42 women, 37 men; mean age, 48.5 years; 38 with clinical flare) and 5 healthy control subjects were included in the study. At baseline the frequencies of whole CD4+ T cells, CD4+CD25med effector cells, and Tregs did not differ between the two treatment groups and the healthy control subjects. In addition, patients with UC in sustained clinical remission showed no alteration from baseline after 1, 3, 6, 9, or 12 months of either treatment. In contrast, CD4+ T cells, CD4+CD25med effector T cells, and Tregs demonstrated distinctly different patterns at time points pre-flare and flare. The mesalazine group showed a continuous but not statistically significant increase from baseline to pre-flare and flare (p = ns). In the herbal treatment group, however, the percentage of the CD4+ T cells was lower at pre-flare than at baseline. This decrease was completely reversed after flare, when a significant increase was seen (CD4+CD25med pre-flare/flare p = 0.0461; CD4+CD25high baseline/flare p = 0.0269 and pre-flare/flare p = 0.0032). In contrast, no changes in the expression of Foxp3 cells were detected within the subsets of CD4+CD25high regulatory T cells. Of note, no alterations were detected in the suppressive capability of CD4+CD25high regulatory T cells isolated from the peripheral blood of healthy donors, from patients in remission, or from patients with clinical flare.

CONCLUSIONS

In patients with UC experiencing acute flare, the CD4+ T compartment demonstrates a distinctly different pattern during treatment with myrrh, chamomile extract, and coffee charcoal than during treatment with mesalazine. These findings suggest an active repopulation of regulatory T cells during active disease.

TRIAL REGISTRATION

EU Clinical Trials Register 2007-007928-18/DE.

Predictors of response to anti-tumor necrosis factor therapy in ulcerative colitis

Ulcerative colitis (UC) is an immune-mediated, chronic inflammatory disease of the large intestine. Its course is characterized by flares of acute inflammation and periods of low-grade chronic inflammatory activity or remission. Monoclonal antibodies against tumor necrosis factor (anti-TNF) are part of the therapeutic armamentarium and are used in cases of moderate to severe UC that is refractory to conventional treatment with corticosteroids and/or immunosuppressants. Therapeutic response to these agents is not uniform and a large percentage of patients either fail to improve (primary non-response) or lose response after a period of improvement (secondary non-response/loss of response). In addition, the use of anti-TNF agents has been related to uncommon but potentially serious adverse effects that preclude their administration or lead to their discontinuation. Finally, use of these medications is associated with a considerable cost for the health system. The identification of parameters that may predict response to anti-TNF drugs in UC would help to better select for patients with a high probability to respond and minimize risk and costs for those who will not respond. Analysis of the major clinical trials and the accumulated experience with the use of anti-TNF drugs in UC has resulted to the report of such prognostic factors. Included are clinical and epidemiological characteristics, laboratory markers, endoscopic indicators and molecular (immunological/genetic) signatures. Such predictive parameters of long-term outcomes may either be present at the commencement of treatment or determined during the early period of therapy. Validation of these prognostic markers in large cohorts of patients with variable characteristics will facilitate their introduction into clinical practice and the best selection of UC patients who will benefit from anti-TNF therapy.

Heme oxygenase-1 ameliorates dextran sulfate sodium-induced acute murine colitis by regulating Th17/Treg cell balance

Inflammatory bowel disease (IBD), including ulcerative colitis and Crohn's disease, is a group of autoimmune diseases characterized by nonspecific inflammation in the gastrointestinal tract. Recent investigations suggest that activation of Th17 cells and/or deficiency of regulatory T cells (Treg) is involved in the pathogenesis of IBD. Heme oxygenase (HO)-1 is a protein with a wide range of anti-inflammatory and immune regulatory function, which exerts significantly protective roles in various T cell-mediated diseases. In this study, we aim to explore the immunological regulation of HO-1 in the dextran sulfate sodium-induced model of experimental murine colitis. BALB/c mice were administered 4% dextran sulfate sodium orally; some mice were intraperitoneally pretreated with HO-1 inducer hemin or HO-1 inhibitor stannum protoporphyrin IX. The results show that hemin enhances the colonic expression of HO-1 and significantly ameliorates the symptoms of colitis with improved histological changes, accompanied by a decreased proportion of Th17 cells and increased number of Tregs in mesenteric lymph node and spleen. Moreover, induction of HO-1 down-regulates retinoic acid-related orphan receptor γt expression and IL-17A levels, while promoting Treg-related forkhead box p3 (Foxp3) expression and IL-10 levels in colon. Further study in vitro revealed that up-regulated HO-1 switched the naive T cells to Tregs when cultured under a Th17-inducing environment, which involved in IL-6R blockade. Therefore, HO-1 may exhibit anti-inflammatory activity in the murine model of acute experimental colitis via regulating the balance between Th17 and Treg cells, thus providing a possible novel therapeutic target in IBD.

TLR4 regulates IFN-γ and IL-17 production by both thymic and induced Foxp3+ Tregs during intestinal inflammation

Tregs play a crucial role in the maintenance of intestinal immune homeostasis. However, significant numbers of Foxp3(+) Tregs accumulate in the inflamed lesions in experimental colitis and in IBD patients. Treg production of the proinflammatory cytokines IFN-γ and/or IL-17 may arguably explain their ineffectiveness in suppressing intestinal inflammation. However, it remains unknown whether iTreg and tTreg produce proinflammatory cytokines and how TLR signaling regulates this process. Here, we found that Foxp3(+)Tregs were increased in the intestines of B6.TLR4(-/-) and B6.IL-10(-/-) mice when compared with WT B6 mice. TLR4(-/-) and IL-10(-/-) resulted in more Tregs within inflamed intestines. The majority of Foxp3(+) Tregs in the spleen was Helios(+)Nrp1(+), whereas most Foxp3(+) Tregs in the intestinal LP were Helios(-)Nrp1(-). More Helios(+)Nrp1(+) Tregs expressed IFN-γ and/or IL-17 than did Helios(-)Nrp1(-) Tregs in the spleen and intestine, which was increased with TLR4(-/-). TLR4 signaling in T cells and APCs inhibited Foxp3(+) induction via MyD88-dependent, TRIF-independent pathways, which was negatively regulated by SOCS3. Collectively, these data demonstrate Helios(+)Nrp1(+) tTregs and Helios(-)Nrp1(-) iTregs produce proinflammatory cytokines in the intestines during inflammation, which was regulated by TLR4 signaling.

CD25 and TNF receptor II reflect early primary response to infliximab therapy in patients with ulcerative colitis

BACKGROUND

Although infliximab treatment is an option for patients with ulcerative colitis (UC), not all patients do respond to therapy, and cellular mechanisms leading to therapy response are incompletely known.

OBJECTIVE

The objective of this article is to determine early effects of infliximab therapy on T cells in the blood of UC patients and if effects differed in therapy responders and nonresponders.

METHODS

Blood samples were obtained before and two weeks post-treatment start from 34 anti-tumor necrosis factor (TNF) therapy-naïve UC patients undergoing infliximab therapy. Response to therapy was evaluated prior to the fourth treatment dose. Expression of T cell surface markers and levels of soluble receptors and cytokines in serum were determined.

RESULTS

At baseline, there were no differences in cellular, biochemical or clinical parameters between therapy responders and nonresponders. Infliximab therapy reduced frequencies of CD25(+) T cells and increased frequencies of annexin V(+) T cells in patients responding to infliximab, but not in nonresponding patients, two weeks after therapy start. Only therapy responders had decreased serum levels of sCD25 and sTNFRII two weeks after treatment start. In contrast, clinical parameters did not reflect therapy outcome already two weeks after therapy start.

CONCLUSION

Soluble and membrane-bound T cell receptors may be early indicators of infliximab therapy response in UC, which can be of clinical importance for the decision when to continue or to stop the treatment.

Review article: the role of oxidative stress in pathogenesis and treatment of inflammatory bowel diseases

In this review, we focus on the role of oxidative stress in the aetiology of inflammatory bowel diseases (IBD) and colitis-associated colorectal cancer and discuss free radicals and free radical-stimulated pathways as pharmacological targets for anti-IBD drugs. We also suggest novel anti-oxidative agents, which may become effective and less-toxic alternatives in IBD and colitis-associated colorectal cancer treatment. A Medline search was performed to identify relevant bibliography using search terms including: ‘free radicals,’ ‘antioxidants,’ ‘oxidative stress,’ ‘colon cancer,’ ‘ulcerative colitis,’ ‘Crohn’s disease,’ ‘inflammatory bowel disease.’ Several therapeutics commonly used in IBD treatment, among which are immunosuppressants, corticosteroids and anti-TNF-α antibodies, could also affect the IBD progression by interfering with cellular oxidative stress and cytokine production. Experimental data shows that these drugs may effectively scavenge free radicals, increase anti-oxidative capacity of cells, influence multiple signalling pathways, e.g. MAPK and NF-kB, and inhibit pro-oxidative enzyme and cytokine concentration. However, their anti-oxidative and anti-inflammatory effectiveness still needs further investigation. A highly specific antioxidative activity may be important for the clinical treatment and relapse of IBD. In the future, a combination of currently used pharmaceutics, together with natural and synthetic anti-oxidative compounds, like lipoic acid or curcumine, could be taken into account in the design of novel anti-IBD therapies.

Therapeutic effects of curcumin combined with MSCs against ulcerative colitis in rats

AIM: To assess the therapeutic effects of curcumin combined with mesenchymal stem cells (MSCs) in the treatment of ulcerative colitis in rats and to explore the underlying mechanisms.

METHODS: Ulcerative colitis was induced in rats with 2,4,6-trinitrobenzene sulfonic acid (TNBS). 40 male Sprague-Dawley rats were randomly divided into 5 groups: a normal group, a model group, an MSCs group, a curcumin group, and a curcumin plus MSCs group. The signs and symptoms of rats in each group were observed, including vitality, diet, property of stool and bloody stool. The severity of colitis was assessed using gross morphological score (GMS) and histopathologic damage score (HDS). The percentages of Th17 and Treg lymphocytes in peripheral blood were determined by flow cytometry. Expression of IL-17 and Foxp3 in the colonic mucosa was detected by immunohistochemistry.

RESULTS: Compared with the normal group, the GMS and HDS were significantly higher in the model group (0.00 ± 0.00 vs 4.63 ± 0.74; 0.25 ± 0.46 vs 4.00 ± 0.53, P < 0.01); the levels of Treg in the peripheral blood and Foxp3 in the colon tissue were significant decreased, and the levels of Th17 in the peripheral blood and IL-17 in the colon tissue were significantly increased in the model group (8.01 ± 0.29 vs 1.16 ± 0.18; 9.50 ± 1.60 vs 0.88 ± 0.64; 0.63 ± 0.13 vs 4.56 ± 0.21; 0.88 ± 0.64 vs 7.75 ± 1.16, P < 0.01 for all). The GMS and HDS were significantly lower in the treatment groups than in the model group (4.63 ± 0.74 vs 2.12 ± 0.64, 2.00 ± 0.53, 1.00 ± 0.53; 4.00 ± 0.53 vs 2.00 ± 0.53, 1.88 ± 0.83, 1.25 ± 0.46, P < 0.01 for all). The levels of Treg and Foxp3 were significantly increased, and the levels of Th17 and IL-17 were significantly decreased in the treatment groups compared with the model group (1.16 ± 0.18 vs 3.29 ± 0.18, 3.19 ± 0.20, 5.00 ± 0.19; 0.88 ± 0.64 vs 3.75 ± 0.46, 4.00 ± 0.92, 6.88 ± 1.25; 4.56 ± 0.21 vs 2.60 ± 0.15, 2.59 ± 0.23, 1.52 ± 0.21; 0.88 ± 0.64 vs 3.75 ± 0.46, 4.00 ± 0.92, 6.88 ± 1.25, P < 0.01 for all). Compared with the MSCs group and curcumin group, the GMS and HDS were significantly decreased in the curcumin plus MSCs group (1.00 ± 0.53 vs 2.12 ± 0.64, 2.00 ± 0.53; 1.25 ± 0.46 vs 2.00 ± 0.53, 1.88 ± 0.83, P < 0.05 for all). The levels of Treg and Foxp3 in the combination treatment group were significantly increased, and the levels of Th17 and IL-17 were significantly decreased compared with monotherapy groups (5.00 ± 0.19 vs 3.29 ± 0.18, 3.19 ± 0.20; 6.88 ± 1.25 vs 3.75 ± 0.46, 4.00 ± 0.92; 1.52 ± 0.21 vs 2.60 ± 0.15, 2.59 ± 0.23; 2.38 ± 0.92 vs 5.00 ± 1.07, 4.62 ± 1.19, P < 0.01 for all).

CONCLUSION: Curcumin together with MSCs can decrease colonic mucosal damage and promote the repair of impaired mucosa in UC rats possibly via mechanisms associated with regulating the balance of Treg and Th17 1ymphocytes and the relevant cytokines in colonic tissue．

Intestinal and peripheral fibrinogen-like protein 2 expression in inflammatory bowel disease

BACKGROUND

Fibrinogen-like protein 2 (FGL2), a new member of the fibrinogen-like family, has recently been identified as a novel immunosuppressive molecule.

AIM

The purpose of this work was to investigate intestinal and peripheral expression of FGL2 in patients with inflammatory bowel disease (IBD), mainly ulcerative colitis (UC) and Crohn's disease (CD).

METHODS

FGL2 expression in mucosal biopsies from three groups (UC group (n = 61), CD group (n = 54), and controls group (n = 35)) was detected by immunohistochemistry. Concentrations of FGL2 in plasma from 50 UC patients, 45 CD patients, and 30 controls were analyzed by enzyme-linked immunosorbent assay. Western blot of FGL2 protein and real-time fluorescent quantitative PCR of FGL2 mRNA expression by peripheral mononuclear cells was performed. Correlations of FGL2 expression with disease type, activity, and location, and with measured laboratory data, including C-reactive protein (CRP) and erythrocyte sedimentation rate (ESR), were examined.

RESULTS

Intestinal and peripheral FGL2 protein data showed that FGL2 expression was significantly up-regulated in both UC and CD patients compared with controls (P < 0.001). Expression of FGL2 was higher in UC and CD patients with active disease than in those with inactive disease (P < 0.001). Moreover, FGL2 mRNA expression was significantly higher in patients with active disease than in those with inactive disease (P < 0.050). Expression of FGL2 protein was correlated with disease activity indices, CRP levels, and ESR levels.

CONCLUSION

Expression of FGL2 was up-regulated in IBD patients with active disease. Measurement of FGL2 may be used as a helpful biomarker for understanding immunopathogenesis and for assessment of IBD.

Infliximab inhibits activation and effector functions of peripheral blood T cells in vitro from patients with clinically active ulcerative colitis

Many patients with inflammatory bowel disease (IBD) are undergoing therapy with infliximab, an antibody specific for TNF. However, the exact mechanisms of action of infliximab are not completely understood. The aim of this study was to determine the in vitro effects of infliximab on blood T cells derived from anti-TNF therapy-naïve ulcerative colitis (UC) patients with clinically active disease. Peripheral blood mononuclear cells were stimulated polyclonally or by antigen in the presence or absence of infliximab. The T cell phenotype was investigated by flow cytometry, cytokine secretion was determined by ELISA, and cell proliferation was determined by thymidine assay or CFSE dye. Presence of infliximab resulted in reduced expression of CD25 in CD4(+) and CD8(+) T cell populations and inhibited secretion of IFN-γ, IL-13, IL-17A, TNF as well as granzyme A. Infliximab also suppressed CD4(+) and CD8(+) T cell proliferation. These effects of infliximab were recorded both in T cells activated by polyclonal and antigen-specific stimulation. The effects of infliximab on T cell apoptosis and induction of FOXP3(+) CD4(+) T regulatory cells were ambiguous and depended on the originating cellular source and/or the stimulation mode and strength. In conclusion, infliximab is able to reduce T cell activation as measured by CD25, proliferation and cytokine secretion in vitro from UC patients with clinically active disease. These data suggest that suppression of T cell activity may be important for infliximab-mediated disease remission in patients with UC.

Keeping the bowel regular: the emerging role of Treg as a therapeutic target in inflammatory bowel disease

The understanding of the intricate mechanisms by which gut immune cells interact with each other and the intestinal flora is constantly developing. The mucosal immune system must retain the ability to mount a prompt response to intestinal pathogens while maintaining tolerance for commensal organisms. Effector T lymphocytes drive inflammation, whereas their actions are counteracted by populations of regulatory T cells (Treg), which act as an endogenous suppressor of mucosal inflammation. There is growing evidence that a loss of this delicate counterbalance is important in the etiology of inflammatory bowel disease (IBD). Here, we review studies highlighting alterations in Treg in the pathogenesis of IBD. Observations of dynamic changes in Treg activity with successful IBD treatment have highlighted their functional importance and potential to also serve as a biomarker of disease activity and to predict response to therapy. Furthermore, we explore the potential for adoptive transfer of Treg as part of IBD treatment.

Increased prevalence of circulating novel IL-17 secreting Foxp3 expressing CD4+ T cells and defective suppressive function of circulating Foxp3+ regulatory cells support plasticity between Th17 and regulatory T cells in inflammatory bowel disease patients

BACKGROUND

IL-17 and Foxp3 double-expressing (DE) CD4(+) T lymphocytes are novel crossover immune cell population, but the presence and role of these cells in human intestinal inflammation is unclear. The aim of this study was to investigate the circulating IL-17 and Foxp3 DE CD4(+) T lymphocytes in patients with inflammatory bowel disease (IBD).

METHODS

The entire cohort consisted of 79 subjects: 31 patients with Crohn's disease, 28 patients with ulcerative colitis, and 20 healthy control subjects (HC). IBD patients with evidence of active disease at endoscopy were entered into the study. Peripheral blood mononuclear cells were used for ex vivo and in vitro studies to assess the characteristics and generation of these novel cells and the function of circulating Foxp3 CD4(+) regulatory T lymphocytes (Treg) in patients with IBD compared with HC.

RESULTS

Patients with IBD had significantly higher prevalence of IL-17 and Foxp3 DE CD4(+) T lymphocytes compared with age- and gender-matched HC. These cells expressed RORγt. The ability of Treg cells to suppress autologous T-cell proliferation was reduced by approximately 60% in patients with IBD compared with HC. Increased generation of these DE cells was demonstrated by the modulation of cytokine environment of CD4(+) lymphocytes in vitro in patients with Crohn's disease.

CONCLUSIONS

Prevalence of circulating IL-17 and Foxp3 DE CD4(+) T cells is increased in patients with IBD. Coexpression of RORγt and Foxp3 in these cells implies conversion from Treg cells to Th17 cells. This is associated with a decreased suppressive function of Foxp3 CD4(+) T lymphocytes in patients with IBD.

Study on the interactions between transplanted bone marrow-derived mesenchymal stem cells and regulatory T cells for the treatment of experimental colitis

Accumulating evidence has established the use of mesenchymal stem cells (MSCs) as candidate cells for immunosuppressive therapy. Experimental studies have suggested that MSCs exert their immunomodulatory effects through the induction of regulatory T cells (Tregs) in vitro and in vivo. However, the interactions between MSCs and Tregs in inflammatory bowel disease (IBD) and whether MSCs can be used for the treatment of IBD remains to be elucidated. In this study, we aimed to investigate whether MSCs can be used for the treatment of IBD through the induction of Tregs. MSCs were isolated and identified by flow cytometry. The MSCs were transduced with a replication-defective recombinant lentiviral vector carrying GFP in order to be able to trace the injected cells in vivo. Prepared MSCs (1x106) were injected into rats with 2,4,6-trinitrobenzene sulfonic acid (TNBS)‑induced colitis via the tail vein; the control rats received phosphate-buffered saline (PBS) alone. Two weeks after the intravenous infusion, the frequency of CD4+CD25+Foxp3 cells in the peripheral blood was examined by flow cytometry. The colon was sectioned and analyzed for histopathological changes. Foxp3 mRNA expression was determined by real-time reverse-transcription polymerase chain reaction (qRT-PCR). In our study, the systemic infusion of MSCs significantly ameliorated the clinical and histopathologic severity of TNBS-induced colitis in contrast to the controls. There was an inverse regulation of mucosal and peripheral Foxp3 expression, suggesting that the MSCs redistributed the Tregs from the mucosa to the blood. Thus, MSCs exhibit immunomodulatory functions and may be used to ameliorate or treat IBD by redistributing regulatory T cells. Therefore, the interactions between transplanted bone marrow-derived MSCs and Tregs should be further investigated; MSCs have tremendous potential for use in the treatment of IBD.

Importance of regulatory T cells in the pathogenesis of psoriasis: review of the literature

Psoriasis is a common chronic relapsing inflammatory cutaneous disease; the main role in the inflammation of this condition is played by lymphocyte Th1, Th17 and their cytokines. The activity of these cells is modulated by a particular kind of T cells recently described: the T regulatory cells (Treg). These are able to inhibit the immunological response and to maintain the cutaneous immunological homeostasis, thus preventing autoimmunity against self antigens. Few data are available in the literature as to Treg in psoriasis; several studies demonstrate that the function of these cells is impaired in this condition and treatments for psoriasis may increase the number and activity of Treg. The role of these cells in the pathogenesis of psoriasis is very important to understand how they may contribute to the development of this cutaneous disorder. In the near future it would be possible to target therapies at these defects, improving the activity of these cells and maintaining cutaneous homeostasis, preventing psoriasis or other inflammatory cutaneous conditions.

FOXP3⁺ T regulatory cell modifications in inflammatory bowel disease patients treated with anti-TNFα agents

Treg modulation has been hypothesized as one of the mechanisms by which antitumor necrosis factor α (TNFα) agents exert their action in rheumatoid arthritis (RA) and inflammatory bowel disease (IBD). However, data in IBD are still conflicting. We evaluated CD4⁺CD25⁺FOXP3⁺ (Tregs) by flow cytometry in peripheral blood from 32 adult IBD patient before (T0) and after the induction of anti-TNFα therapy (T1). Eight healthy controls (HCs) were included. We also evaluated the number of FOXP3⁺ cells in the lamina propria (LP) in biopsies taken in a subset of patients and controls. Treg frequencies were significantly increased in peripheral blood from our patients after anti-TNFα therapy compared to T0. T1 but not T0 levels were higher than HC. The increase was detectable only in clinical responders to the treatment. A negative correlation was found among delta Treg levels and the age of patients or disease duration and with the activity score of Crohn's disease (CD). No significant differences were found in LP FOXP3⁺ cells. Our data suggest the possibility that in IBD patients the treatment with anti-TNFα may affect Treg percentages and that Treg modifications may correlate with clinical response, but differently in early versus late disease.

Influence of pharmacological immunomodulatory agents on CD4(+)CD25(high)FoxP3(+) T regulatory cells in humans

T regulatory cells (Tregs) play a critical role in the immunologic tolerance to the graft in transplantation. Thus, due to their immunosuppressive capability, ex vivo expanded Tregs may be used as a cellular therapy and an attractive novel strategy to control chronic rejection and eliminate need for lifelong pharmacological immunosuppression. Since Treg therapy is still in its infancy, initially Tregs still need to be applied in combination with pharmacological agents to prevent rejection. Fortunately, some of the medications have been shown to enhance the function and number of Tregs. In the clinic, different immunosuppressive regimens are used for individual patients for different types of organ transplantation. In this review, we present the most commonly used pharmacological agents for immunosuppression and discuss how they affect the Treg population. It is extremely difficult to dissect the effect of single agent on Tregs population in clinical settings since usually the combination of several medications is applied at the same time for graft protection. Nevertheless, experimental and clinical data indicate that thymoglobulin as immunosuppressive induction and mTOR inhibitors as immunosuppressive maintenance agents have the most beneficial effect on Treg population in the blood. Among supplemental agents promoting Tregs, anti-TNFα preparations have been in clinical use (in autoimmune diseases) for many years, so they are optimal candidates for testing in transplant settings in combination with Treg based cellular therapy.

Normalization of mucosal cytokine gene expression levels predicts long-term remission after discontinuation of anti-TNF therapy in Crohn's disease

OBJECTIVE

To investigate mucosal cytokine gene expression levels in healed mucosa after anti-tumor necrosis factor (TNF) therapy in patients with Crohn's disease (CD) as possible risk factors for relapse after discontinuation of therapy.

DESIGN

Thirty-seven CD patients treated with anti-TNF agents until complete mucosal healing, documented by endoscopy, discontinued anti-TNF treatment and entered a follow-up study. Levels of mRNA expression of interleukin (IL)17A (IL17A), IL23, interferon-gamma (IFNG), TNF-alpha (TNF), IL10 and Forkhead Box P3 (FOXP3) were measured in biopsies from healed mucosa and analyzed as possible risk factors of relapse. Mucosal cytokine transcript levels from patients without CD served as controls.

RESULTS

Patients were followed after therapy withdrawal until relapse. Median time to relapse was 20 and 68 weeks for patients with elevated and normalized IL17A and TNF expression levels, respectively (p = 0.02 for IL17A and p = 0.003 for TNF, log-rank). Expression levels of TNF, IL17A and FOXP3 were significantly higher in patients who relapsed before 26 weeks than in those who did not relapse, and also higher in patients with relapse before week 52 versus non-relapsers. Elevated expression levels of TNF and IL17A in healed mucosa significantly increased the risk of relapse (HR = 3.4, p = 0.03, sensitivity 80%, specificity 38% and HR = 4.1, p = 0.008, sensitivity 81%, specificity 61%, respectively).

CONCLUSIONS

Normalization of mucosal gene expression of cytokines after anti-TNF therapy does not occur in all patients with healed mucosa as judged by endoscopy. Normalization of TNF and/or IL17A expression predicts long-term remission.

IL-25 downregulates Th1/Th17 immune response in an IL-10-dependent manner in inflammatory bowel disease

BACKGROUND

Interleukin 25 (IL-25) is involved in the initiation of T helper cell (Th)2-mediated immunopathologies. In this study, we investigated the expression of IL-25 in inflammatory bowel disease (IBD) and its role in the induction of CD4 T-cell differentiation.

METHODS

Expression of IL-25 in inflamed mucosa of patients with IBD was determined by quantitative real-time polymerase chain reaction, immunohistochemistry, and enzyme-linked immunosorbent assay. The correlation of IL-25 expression with endoscopic disease activities and C-reactive protein was evaluated. Peripheral blood and lamina propria CD4 T cells were stimulated with anti-CD3 and anti-CD28 monoclonal antibodies in the presence of IL-25. Transcription factors and cytokines were determined with real-time polymerase chain reaction, flow cytometry, and enzyme-linked immunosorbent assay.

RESULTS

IL-25 was significantly decreased in the sera and inflamed mucosa of patients with active IBD compared with controls. It was upregulated in the sera of patients with Crohn's disease after treatment with infliximab. The levels of IL-25 in inflamed mucosa and sera were inversely correlated with endoscopic disease activities and C-reactive protein, respectively, in IBD. IL-25 could markedly inhibit IBD CD4 T cells to produce tumor necrosis factor, interferon γ, and IL-17A but promote IL-10 secretion. It suppressed the differentiation of IBD CD4 T cells into Th1 and Th17 cells but did not interfere with Th2 cell differentiation. Importantly, blockade of IL-10 secretion by IBD CD4 T cells markedly attenuated the inhibitory role of IL-25 in modulating both Th1 and Th17 immune responses.

CONCLUSIONS

IL-25 is markedly decreased in IBD and inhibits IBD CD4 T-cell activation and differentiation into Th1/Th17 cells in an IL-10-dependent manner, suggesting that it may be a potential therapeutic agent for IBD.

Safety and efficacy of antigen-specific regulatory T-cell therapy for patients with refractory Crohn's disease

BACKGROUND & AIMS

New therapeutic strategies are needed for patients with refractory Crohn's disease (CD). We evaluated data from the Crohn's And Treg Cells Study (CATS1) to determine the safety and efficacy of antigen-specific T-regulatory (Treg) cells for treatment of patients with refractory CD.

METHODS

We performed a 12-week, open-label, multicenter, single-injection, escalating-dose, phase 1/2a clinical study in 20 patients with refractory CD. Ovalbumin-specific Treg cells (ova-Tregs) were isolated from patients' peripheral blood mononuclear cells (PBMCs), exposed to ovalbumin, and administrated intravenously. Safety and efficacy were assessed using clinical and laboratory parameters. We evaluated proliferation of PBMCs in response to ovalbumin.

RESULTS

Injections of ova-Tregs were well tolerated, with 54 adverse events (2 related to the test reagent) and 11 serious adverse events (3 related to the test reagent, all recovered). Overall, a response, based on a reduction in Crohn's Disease Activity Index (CDAI) of 100 points, was observed in 40% of patients at weeks 5 and 8. Six of the 8 patients (75%) who received doses of 10(6) cells had a response at weeks 5 and 8, with a statistically significant reduction in CDAI. In this group, remission (based on CDAI ≤150) was observed in 3 of 8 patients (38%) at week 5 and 2 of 8 patients (25%) at week 8.

CONCLUSIONS

Administration of antigen-specific Tregs to patients with refractory CD (CATS1) was well tolerated and had dose-related efficacy. The ovalbumin-specific immune response correlated with clinical response, supporting immune-suppressive mechanisms of ova-Tregs. The consistency of results among different assessment methods supports the efficacy of ova-Tregs; this immune therapy approach warrants further clinical and mechanistic studies in refractory CD. Eudract, Number: 2006-004712-44.

The effect of adalimumab for induction of endoscopic healing and normalization of mucosal cytokine gene expression in Crohn's disease

OBJECTIVE

To investigate the effects of adalimumab on the induction of complete endoscopic healing and normalization of mucosal cytokine gene expression in patients with active Crohn's disease.

MATERIAL AND METHODS

A prospective, single-center study including 77 patients. All were examined by endoscopy before initiation of adalimumab induction therapy with a minimum of six adalimumab injections. Patients were treated until documentation of complete endoscopic healing. Biopsies for measurements of mRNA expression levels of interleukin(IL)-17A (IL17A), IL23, interferon-gamma (IFNG), tumor necrosis factor-alpha (TNF), IL10 and Forkhead Box P3 (FOXP3), as well as for immunohistochemistry (IHC) were sampled at pre- and post-treatment endoscopy, and from 17 control patients.

RESULTS

Complete endoscopic healing was achieved in 27.3% after 10 weeks of treatment, documented by endoscopy at week 12. Cumulative endoscopic healing after 52 weeks was 44.2%. Complete endoscopic healing led to a significant reduction in mRNA expression levels for all cytokines except IL10. Elevated expression of TNF and IL-17A persisted in 52% and 76%, respectively, of patients with complete endoscopic remission. Pre-treatment cytokine gene expression levels did not predict response to adalimumab therapy.

CONCLUSIONS

Adalimumab induces accumulated complete endoscopic healing in 44% of patients after 52 weeks of therapy. Normalization of mucosal gene expression of cytokines does not occur in all patients with endoscopy-verified healed mucosa. Inclusion of normalized mucosal cytokine expression into the concept of mucosal healing could have an impact on long-term clinical outcome.

Altered immunoregulatory profile during anti-tumour necrosis factor treatment of patients with inflammatory bowel disease

Inflammatory bowel disease (IBD) can be treated effectively by anti-tumour necrosis factor (TNF) therapy. We set out to investigate the unclear immunoregulatory mechanisms of the treatment. Thirty-four patients with IBD treated with anti-TNF were included. Lymphocytes from peripheral blood and intestinal biopsies were analysed by flow cytometry. Regulation of antigen-stimulated proliferation was analysed by blocking of interleukin (IL)-10, transforming growth factor (TGF)-β or depletion of CD25(+) cells in peripheral blood mononuclear cell cultures. No changes in CD4(+)CD25(+), CD25(+)TNF-RII(+) or CD4(+)CD25(+) forkhead box protein 3 (FoxP3(+)) T cells could be observed in peripheral blood after, in comparison to before, 6 weeks of treatment. The suppressive ability of CD4(+)CD25(+) cells did not change. There was an initial decrease of CD4(+)CD25(+) cells in intestinal mucosa after 2 weeks of treatment, followed by an increase of these cells from weeks 2 to 6 of treatment (P < 0·05). This was accompanied by an increased percentage of CD69(+) cells among these cells after 6 weeks of treatment compared to before treatment (P < 0·01). There was also an increase of mucosal T helper type1 cells from weeks 2 to 6 (P < 0·05). In addition, CD25(+)TNF-RII(+) cells in the mucosa were decreased after 6 weeks of treatment compared to before treatment (P < 0·05). Before treatment, peripheral blood mononuclear cell baseline proliferation was increased when IL-10 was blocked (P < 0·01), but not after. In CD25(+) cell-depleted cultures proliferation increased after treatment (P < 0·05). Our data indicate that anti-TNF treatment leads to an induction of effector T cells. Anti-TNF therapy has no significant impact on regulatory T cells in IBD, although the composition of regulatory T cell subsets may change during treatment.

Adeno-associated virus mediated delivery of Tregitope 167 ameliorates experimental colitis

AIM

To explore the anti-inflammatory potential of adeno-associated virus-mediated delivery of Tregitope 167 in an experimental colitis model.

METHODS

The trinitrobenzene sulfonate (TNBS) model of induced colitis was used in Balb/c mice. Subsequently after intravenous adeno-associated virus-mediated regulatory T-cell epitopes (Tregitope) delivery, acute colitis was initiated by intra-rectal administration of 1.5 mg TNBS in 40% ethanol followed by a second treatment with TNBS (0.75 mg in 20% ethanol) 8 d later. Control groups included mice not treated with TNBS (healthy control group) and mice treated by TNBS only (diseased group). At the time of sacrifice colon weight, the disease activity index and histology damage score were determined. Immunohistochemical staining of the colonic tissues was performed to asses the cellular infiltrate and the presence of transcription factor forkhead Box-P3 (Foxp3). Thymus, mesenteric lymph nodes, liver and spleen tissue were collected and the corresponding lymphocyte populations were further assessed by flow cytometry analysis for the expression of CD4+ T cell and regulatory T cell associated markers.

RESULTS

The Tregitope 167 treated mice gained an average of 4% over their initial body weight at the time of sacrifice. In contrast, the mice treated with TNBS alone (no Tregitope) developed colitis, and lost 4% of their initial body weight at the time of sacrifice (P < 0.01). The body weight increase that had been observed in the mice pre-treated with Tregitope 167 was substantiated by a lower disease activity index and a decreased colon weight as compared to the diseased control group (P < 0.01 and P < 0.001, respectively). Immunohistochemical staining of the colonic tissues for CD4+ showed that inflammatory cell infiltrates were present in TNBS treated mice with or without administration with tregitope 167 and that these cellular infiltrates consisted mainly of CD4+ cells. For both TNBS treated groups CD4+ T cell infiltrates were observed in the sub-epithelial layer and the lamina propria. CD4+ T cell infiltrates were also present in the muscularis mucosa layer of the diseased control mice, but were absent in the Tregitope 167 treated group. Numerous Foxp3 positive cells were detected in the lamina propria and sub-epithelium of the colon sections from mice treated with Tregitope 167. Furthermore, the Foxp3 and glycoprotein A repetitions predominant markers were significantly increased in the CD4+ T lymphocyte population in the thymus of the mice pre-treated with adeno-associated virus serotype 5 (cytomegalovirus promoter-Tregitope 167), as cytomegalovirus promoter compared to lymphocyte populations in the thymus of diseased and the healthy control mice (P < 0.05 and P < 0.001, respectively).

CONCLUSION

This study identifies adeno-associated virus-mediated delivery of regulatory T-cell epitope 167 as a novel anti-inflammatory approach with the capacity to decrease intestinal inflammation and induce long-term remission in inflammatory bowel disease.

Host-microbiota interactions in inflammatory bowel disease

The interaction of the host with its abundant intestinal microbiota is complex and engages most of the cells in the intestinal mucosa. The inflammatory bowel diseases appear to be disorders of the host immune response to the microbiota. This is supported by data from induced gene mutations in mice and more recently by the identification of gene variants in humans that result in IBD or IBD susceptibility. These genetic studies have provided insights into the cells and molecular pathways involved in the host-microbiota dialog. This review discusses the innate, adaptive, and regulatory immune response to the microbiota in the context of the mouse and human genes that are involved in maintaining intestinal homeostasis and preventing inflammation. These data continue to support the hypothesis that inflammatory bowel disease results from a dysregulated adaptive immune response, particularly a CD4 T-cell response, to the microbiota. The microbiota itself is an active participant in these homeostatic processes. The microbiota composition is perturbed during inflammation, resulting in a dysbiosis that may induce or perpetuate inflammation. However, host genotype and the environment have a major impact on the shape of such dysbiosis, as well as upon which members of the microbiota stimulate pathogenic immune responses.

Optimizing immunomodulators and anti-TNF agents in the therapy of Crohn disease

Randomized trials support the use of the thiopurines and anti-TNF monoclonal antibodies in treating Crohn disease. New therapeutic approaches and laboratory assays have helped optimize the use of these agents. Thiopurine methyltransferase activity should always be determined to avoid thiopurines in individuals with absent enzyme activity. The role of metabolite-adjusted dosing when initiating thiopurines is not settled. Measuring metabolites helps guide management in patients failing therapy. Loss of response to anti-TNF therapy is mitigated by maintenance therapy and concomitant immunomodulators. When loss of response to infliximab occurs, management is guided by the serum concentrations of infliximab and antibodies to infliximab.

Mucosal cytokine gene expression profiles as biomarkers of response to infliximab in ulcerative colitis

OBJECTIVE

Mucosal cytokine profile determines T cell differentiation and may play an important role in the clinical course of inflammatory bowel disease (IBD). Cytokines from different T helper (Th) cell subsets are elevated in inflamed mucosa of patients with ulcerative colitis (UC), contributing to the inflammation. The aim of this study was to determine the predictive value of pre-treatment mucosal cytokine profile in response to therapy with the anti-TNF agent infliximab (IFX).

MATERIAL AND METHODS

The expression of Th1, Th17, Th2 and T-regulatory (Treg)-related cytokines was quantified by real-time PCR in mucosal biopsies from 74 UC patients before initiation of IFX induction therapy. Clinical and endoscopic effects were assessed after three infusions. Remission was defined as ulcerative colitis disease activity index (UCDAI) below 3.

RESULTS

Higher gene expression levels of IL-17A and IFN-γ were significantly associated with remission after three IFX infusions (OR = 5.4, p = 0.013 and OR = 5.5, p = 0.011, respectively). IL-17A and IFN-γ mRNA expression showed positive correlation. Th2 and Treg-related mediators were not significantly associated with clinical outcome, but were expressed at higher levels in UC patients compared with the controls. Immunohistochemistry (IHC) confirmed the presence of cells expressing both IL-17A and IFN-γ.

CONCLUSIONS

High expression of Th1- and Th17-related cytokines in the mucosa of UC patients can potentially predict a favorable outcome of IFX induction therapy. Th2 and Treg-related mediators do not appear useful as predictive markers.

Results of the 2nd scientific workshop of the ECCO (III): basic mechanisms of intestinal healing

The second scientific workshop of the European Crohn's and Colitis Organization (ECCO) focused on the relevance of intestinal healing for the disease course of inflammatory bowel disease (IBD). The objective was to better understand basic mechanisms, markers for disease prediction, detection and monitoring of intestinal healing, impact of intestinal healing on the disease course of IBD as well as therapeutic strategies. The results of this workshop are presented in four separate manuscripts. This section describes basic mechanisms of intestinal healing, identifies open questions in the field and provides a framework for future studies.

Gene and cell therapy based treatment strategies for inflammatory bowel diseases

Inflammatory bowel diseases (IBD) are a group of chronic inflammatory disorders most commonly affecting young adults. Currently available therapies can result in induction and maintenance of remission, but are not curative and have sometimes important side effects. Advances in basic research in IBD have provided new therapeutic opportunities to target the inflammatory process involved. Gene and cell therapy approaches are suitable to prevent inflammation in the gastrointestinal tract and show therefore potential in the treatment of IBD. In this review, we present the current progress in the field of both gene and cell therapy and future prospects in the context of IBD. Regarding gene therapy, we focus on viral vectors and their applications in preclinical models. The focus for cell therapy is on regulatory T lymphocytes and mesenchymal stromal cells, their potential for the treatment of IBD and the progress made in both preclinical models and clinical trials.

Equine CD4(+) CD25(high) T cells exhibit regulatory activity by close contact and cytokine-dependent mechanisms in vitro

Horses are particularly prone to allergic and autoimmune diseases, but little information about equine regulatory T cells (Treg) is currently available. The aim of this study therefore was to investigate the existence of CD4(+) Treg cells in horses, determine their suppressive function as well as their mechanism of action. Freshly isolated peripheral blood mononuclear cells (PBMC) from healthy horses were examined for CD4, CD25 and forkhead box P3 (FoxP3) expression. We show that equine FoxP3 is expressed constitutively by a population of CD4(+) CD25(+) T cells, mainly in the CD4(+) CD25(high) subpopulation. Proliferation of CD4(+) CD25(-) sorted cells stimulated with irradiated allogenic PBMC was significantly suppressed in co-culture with CD4(+) CD25(high) sorted cells in a dose-dependent manner. The mechanism of suppression by the CD4(+) CD25(high) cell population is mediated by close contact as well as interleukin (IL)-10 and transforming growth factor-β1 (TGF-β1) and probably other factors. In addition, we studied the in vitro induction of CD4(+) Treg and their characteristics compared to those of freshly isolated CD4(+) Treg cells. Upon stimulation with a combination of concanavalin A, TGF-β1 and IL-2, CD4(+) CD25(+) T cells which express FoxP3 and have suppressive capability were induced from CD4(+) CD25(-) cells. The induced CD4(+) CD25(high) express higher levels of IL-10 and TGF-β1 mRNA compared to the freshly isolated ones. Thus, in horses as in man, the circulating CD4(+) CD25(high) subpopulation contains natural Treg cells and functional Treg can be induced in vitro upon appropriate stimulation. Our study provides the first evidence of the regulatory function of CD4(+) CD25(+) cells in horses and offers insights into ex vivo manipulation of Treg cells.

MRI in Crohn's disease--current and future clinical applications

Crohn's disease is a chronic, disabling disease that, over time, can lead to irreversible bowel damage. MRI can be used to diagnose and assess the activity, severity and complications of Crohn's disease; however, the role of MRI in therapeutic monitoring of changes in disease-related intestinal damage is still to be defined. Objective, validated MRI-based scores have been developed to assess the activity of Crohn's disease; these indices are based on the extent and severity of intestinal inflammation, postoperative recurrence and perianal disease. MRI is accurate, safe, reproducible and can allow repeated evaluations of patients without radiation exposure. Evidence that MRI might be valuable in the therapeutic monitoring of patients with Crohn's disease is increasing and, in combination with endoscopy and surgical history, this imaging technique could enable clinicians to assess Crohn's-disease-related intestinal damage. MRI could, therefore, have a crucial role in a future 'damage-driven' treatment paradigm--in which imaging is used to monitor intestinal damage and medication use is targeted to prevent the accumulation of further damage. This damage-driven therapeutic approach could potentially change the course of Crohn's disease.

MRI in Crohn's disease--current and future clinical applications

Crohn's disease is a chronic, disabling disease that, over time, can lead to irreversible bowel damage. MRI can be used to diagnose and assess the activity, severity and complications of Crohn's disease; however, the role of MRI in therapeutic monitoring of changes in disease-related intestinal damage is still to be defined. Objective, validated MRI-based scores have been developed to assess the activity of Crohn's disease; these indices are based on the extent and severity of intestinal inflammation, postoperative recurrence and perianal disease. MRI is accurate, safe, reproducible and can allow repeated evaluations of patients without radiation exposure. Evidence that MRI might be valuable in the therapeutic monitoring of patients with Crohn's disease is increasing and, in combination with endoscopy and surgical history, this imaging technique could enable clinicians to assess Crohn's-disease-related intestinal damage. MRI could, therefore, have a crucial role in a future 'damage-driven' treatment paradigm--in which imaging is used to monitor intestinal damage and medication use is targeted to prevent the accumulation of further damage. This damage-driven therapeutic approach could potentially change the course of Crohn's disease.

Adalimumab treatment in Crohn's disease does not induce early changes in regulatory T cells

OBJECTIVE

Anti-TNF-α antibodies has been suggested to modulate regulatory T cell (Treg) percentages in rheumatoid arthritis, but results from studies of Crohn's disease (CD) are conflicting. We investigated dynamic changes of circulating Tregs in CD during treatment with the anti-TNF-α-antibody adalimumab (Humira®, Abbott Laboratories A/S, Emdrupvej 28C, DK-2100 Copenhagen).

MATERIAL AND METHODS

Blood samples from 26 CD patients were analysed using flow cytometry before and 1 and 26 weeks after initiation of adalimumab treatment to determine the percentage of Tregs among CD4+ T cells.

RESULTS

In spite of a significant decline in disease activity scores and biochemical markers of inflammation, during the first week of treatment, we did not observe early modulating effects of adalimumab on Treg percentages. However, we found a long-term increase in Treg percentages in responders who had low Treg percentages (<5%) at baseline (p = 0.04). Treg percentage was inversely associated with disease activity (CD activity index or CDAI) (Spearman's rank correlation, ρ = -0.47, p = 0.02). High Treg percentages among CD4+ T cells at baseline predicted clinical response to adalimumab.

CONCLUSIONS

Adalimumab treatment did not induce early modulatory effects on Treg percentage, even in responders. This finding suggests that adalimumab does not have a direct or selective effect on Tregs. However, Treg percentage was associated with disease activity and high Treg percentage predicted response to adalimumab.

Mechanisms of impaired regulation by CD4(+)CD25(+)FOXP3(+) regulatory T cells in human autoimmune diseases

A lack of regulatory T (T(Reg)) cells that express CD4, CD25 and forkhead box P3 (FOXP3) results in severe autoimmunity in both mice and humans. Since the discovery of T(Reg) cells, there has been intense investigation aimed at determining how they protect an organism from autoimmunity and whether defects in their number or function contribute to the development of autoimmunity in model systems. The next phase of investigation - that is, to define the role that defects in T(Reg) cells have in human autoimmunity - is now underway. This Review summarizes our progress so far towards understanding the role of CD4(+)CD25(+)FOXP3(+) T(Reg) cells in human autoimmune diseases and the impact that this knowledge might have on the diagnosis and treatment of these diseases.

Tumor necrosis factor-α monoclonal antibodies in the treatment of inflammatory bowel disease: clinical practice pharmacology

In the last 10 years, anti-tumor necrosis factor (TNF)-α therapy has become a cornerstone in the management of autoimmune diseases. Clinical trial data have consistently found that infliximab, adalimumab, and recently certolizumab pegol offer therapeutic benefits to patients with inflammatory bowel diseases (Crohn's disease and ulcerative colitis). Recent understanding on how these monoclonal antibodies evoke changes at the physiological and molecular levels have provided insights into disease pathogenesis and helped to identify new targets for future drug therapy. With increased experience in the use of these anti-TNF-α antibodies the long-term safety data, use in pregnancy have become available. This article provides an overview of the current knowledge regarding anti-TNF-α therapies for clinicians caring for patients with Crohn's disease and ulcerative colitis.