Hyperexpression of inducible costimulator and its contribution on lamina propria T cells in inflammatory bowel disease

The chromatin and single-cell transcriptional landscapes of CD4 T cells in inflammatory bowel disease link risk loci with a proinflammatory Th17 cell population

Introduction

The imbalance between Th17 and regulatory T cells in inflammatory bowel diseases (IBD) promotes intestinal epithelial cell damage. In this scenario, T helper cell lineage commitment is accompanied by dynamic changes to the chromatin that facilitate or repress gene expression.

Methods

Here, we characterized the chromatin landscape and heterogeneity of intestinal and peripheral CD4 T cellsfrom IBD patients using in house ATAC-Seq and single cell RNA-Seq libraries.

Results

We show that chromatin accessibility profiles of CD4 T cells from inflamed intestinal biopsies relate to genes associated with a network of inflammatory processes. After integrating the chromatin profiles of tissue-derived CD4 T cells and in-vitro polarized CD4 T cell subpopulations, we found that the chromatin accessibility changes of CD4 T cells were associated with a higher predominance of pathogenic Th17 cells (pTh17 cells) in inflamed biopsies. In addition, IBD risk loci in CD4 T cells were colocalized with accessible chromatin changes near pTh17-related genes, as shown in intronic STAT3 and IL23R regions enriched in areas of active intestinal inflammation. Moreover, single cell RNA-Seq analysis revealed a population of pTh17 cells that co-expresses Th1 and cytotoxic transcriptional programs associated with IBD severity.

Discussion

Altogether, we show that cytotoxic pTh17 cells were specifically associated with IBD genetic variants and linked to intestinal inflammation of IBD patients.

Protective Effects of Aminooxyacetic Acid on Colitis Induced in Mice with Dextran Sulfate Sodium

As a known inhibitor of pyridoxal phosphate-dependent transaminase glutamic-oxaloacetic transaminase 1 (GOT1), aminooxyacetic acid (AOAA) has been pointed out to have potential pharmacological effects in antiepileptic, anticonvulsant, antibacterial, cancer cell proliferation inhibition, and acute myocardial infarction (MI) relief. However, its role in inflammatory bowel disease (IBD) has not been reported. Through the in vivo experiment of dextran sulfate sodium- (DSS-) induced colitis in mice, it was found that AOAA significantly attenuated the symptoms, signs, and pathological changes of colitis. In addition, AOAA treatment prevented gut barrier damages by enhancing the expression of zona occludens- (ZO-) 1, occludin, claudin-1, and E-cadherin and recovering the upregulation of the most abundant intermediate filament protein (vimentin). Moreover, the release of interleukin- (IL-) 1β, IL-6, and tumour necrosis factor- (TNF-) α was suppressed, yet the level of IL-10 was upregulated by AOAA treatment compared to the model group. Furthermore, it was shown that AOAA administration boosted M2-like phenotype and effectively reduced M1 macrophage phenotype in the lamina propria of mouse colonic epithelium. Similarly, the effect of AOAA was verified in vitro. AOAA effectively inhibited the classically activated M1 macrophage phenotype and proinflammatory cytokine (IL-1β, TNF-α, and IL-6) expression induced by lipopolysaccharide (LPS) and promoted M2-like phenotype. Collectively, this study reveals for the first time that short-term treatment of AOAA can significantly alleviate DSS-induced acute colitis by regulating intestinal barrier function and macrophage polarization, which provides a theoretical basis for the potential use of AOAA in the treatment of IBD.

Acazicolcept (ALPN-101), a dual ICOS/CD28 antagonist, demonstrates efficacy in systemic sclerosis preclinical mouse models

Background

Uncontrolled immune response with T cell activation has a key role in the pathogenesis of systemic sclerosis (SSc), a disorder that is characterized by generalized fibrosis affecting particularly the lungs and skin. Costimulatory molecules are key players during immune activation, and recent evidence supports a role of CD28 and ICOS in the development of fibrosis. We herein investigated the efficacy of acazicolcept (ALPN-101), a dual ICOS/CD28 antagonist, in two complementary SSc-related mouse models recapitulating skin fibrosis, interstitial lung disease, and pulmonary hypertension.

Methods

Expression of circulating soluble ICOS and skin-expressed ICOS was investigated in SSc patients. Thereafter, acazicolcept was evaluated in the hypochlorous acid (HOCL)-induced dermal fibrosis mouse model and in the Fra-2 transgenic (Tg) mouse model. In each model, mice received 400 μg of acazicolcept or a molar-matched dose of an Fc control protein twice a week for 6 weeks. After 6 weeks, skin and lung were evaluated.

Results

ICOS was significantly increased in the sera from SSc patients and in SSc skin biopsies as compared to samples from healthy controls. Similar body weight changes were observed between Fc control and acazicolcept groups in both HOCL and Fra-2 Tg mice suggesting a good tolerance of acazicolcept treatment. In mice challenged with HOCL, acazicolcept induced a significant decrease in dermal thickness, collagen content, myofibroblast number, and inflammatory infiltrates characterized by B cells, T cells, neutrophils, and macrophages. In the Fra-2 Tg mouse model, acazicolcept treatment reduced lung collagen content, fibrillar collagen, histological fibrosis score, and right ventricular systolic pressure (RVSP). A reduction in frequency of CD4+ and T effector memory cells and an increase in the percentage of CD4+ T naïve cells in spleen and lung of acazicolcept-treated Fra-2 Tg mice was observed as compared to Fc control-treated Fra-2 Tg mice. Moreover, acazicolcept reduced CD69 and PD-1 expression on CD4+ T cells from the spleen and the lung. Target engagement by acazicolcept was demonstrated by blockade of CD28 and ICOS detection by flow cytometry in treated mice.

Conclusions

Our results confirm the importance of costimulatory molecules in inflammatory-driven fibrosis. Our data highlight a key role of ICOS and CD28 in SSc. Using complementary models, we demonstrated that dual ICOS/CD28 blockade by acazicolcept decreased dermal and pulmonary fibrosis and alleviated pulmonary hypertension. These results pave the way for subsequent research on ICOS/CD28-targeted therapies.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13075-021-02709-2.

The Correlation between Vitamin D Levels and the Risk of Postoperative Recurrence in Crohn's Disease

BACKGROUND AND AIMS

Vitamin D deficiency has been associated with disease activity in Crohn's disease (CD). We assessed whether there is a correlation between vitamin D levels and the risk of postoperative recurrence in CD.

METHODS

CD patients who underwent surgery were identified from a prospectively maintained database at the University of Chicago. The primary endpoint was the correlation of serum 25-hydroxy vitamin D levels measured at 6-12 months after surgery and the proportion of patients in endoscopic remission, defined as a simple endoscopic score for CD of 0. Clinical, biological (C-reactive protein), and histologic recurrences were also studied.

RESULTS

Among a total of 89 patients, 17, 46, and 26 patients had vitamin D levels of <15, 15-30, and >30 ng/mL, respectively. Patients with higher vitamin D levels were significantly more likely to be in endoscopic remission compared to those with lower levels (23, 42, and 67% in ascending tertile order; p = 0.028). On multivariate analysis, vitamin D >30 ng/mL (odds ratio [OR] 0.22, 95% confidence interval [CI] 0.07-0.66, p = 0.006) and anti-tumor necrosis factor agent treatment (OR 0.25, 95% CI 0.08-0.83, p = 0.01) were associated with reduced risk of endoscopic recurrence. Rates of clinical, biological, and histologic remission trended to be higher in patients with higher vitamin D levels (p = 0.17, 0.55, 0.062, respectively).

CONCLUSION

In the present study, higher vitamin D level was associated with lower risk of postoperative endoscopic CD recurrence. Further, studies are warranted to assess the role of vitamin D in postoperative CD recurrence.

First-in-human study of the safety, tolerability, pharmacokinetics, and pharmacodynamics of ALPN-101, a dual CD28/ICOS antagonist, in healthy adult subjects

ALPN-101 (ICOSL vIgD-Fc) is an Fc fusion protein of a human inducible T cell costimulatory ligand (ICOSL) variant immunoglobulin domain (vIgD) designed to inhibit the cluster of differentiation 28 (CD28) and inducible T cell costimulator (ICOS) pathways simultaneously. A first-in-human study evaluated the safety, tolerability, pharmacokinetics (PK), and pharmacodynamics (PD) of ALPN-101 in healthy adult subjects. ALPN-101 was generally well-tolerated with no evidence of cytokine release, clinically significant immunogenicity, or severe adverse events following single subcutaneous (SC) doses up to 3 mg/kg or single intravenous (IV) doses up to 10 mg/kg or up to 4 weekly IV doses of up to 1 mg/kg. ALPN-101 exhibited a dose-dependent increase in exposure with an estimated terminal half-life of 4.3-8.6 days and SC bioavailability of 60.6% at 3 mg/kg. Minimal to modest accumulation in exposure was observed with repeated IV dosing. ALPN-101 resulted in a dose-dependent increase in maximum target saturation and duration of high-level target saturation. Consistent with its mechanism of action, ALPN-101 inhibited cytokine production in whole blood stimulated by Staphylococcus aureus enterotoxin B ex vivo, as well as antibody responses to keyhole limpet hemocyanin immunization, reflecting immunomodulatory effects upon T cell and T-dependent B cell responses, respectively. In conclusion, ALPN-101 was well-tolerated in healthy subjects with dose-dependent PK and PD consistent with the known biology of the CD28 and ICOS costimulatory pathways. Further clinical development of ALPN-101 in inflammatory and/or autoimmune diseases is therefore warranted.

Infliximab therapy intensification based on endoscopic activity is related to suppress treatment discontinuation in patients with Crohn disease: A retrospective cohort study

ABSTRACT

Administering double doses of infliximab or shortening its dosing interval for patients with Crohn disease who experience a loss of response to treatment is an accepted treatment method; however, the effectiveness and appropriate timing of treatment intensification remain unclear. We examined the treatment outcomes of patients with Crohn disease receiving infliximab therapy intensification.Among 430 patients with Crohn disease who were seen at our related facilities from July 2002 to July 2018, 46 patients (30 men and 16 women) who were followed up for diminished infliximab effects for >1 year after therapy intensification were included in this study. The relationship between patient background and continuation of therapy intensification was retrospectively examined through a logistic regression analysis.Among the 46 patients, 67.4% (31 cases) continued therapy intensification for 12 months. The treatment discontinuation rate after 12 months (7.1% vs 43.8%, P = .015) and the C-reactive protein levels at the start of therapy intensification (P = .0050) were significantly lower in the group in which treatment was strengthened due to remaining endoscopic findings (n = 14) than that due to clinical symptoms (n = 32). There was no significant difference in the rates of treatment discontinuation after 12 months of treatment strengthening between patients receiving double doses (n = 34) and those with shortened dosing intervals (n = 12).Infliximab treatment discontinuation seems to be less likely to occur in patients with Crohn disease who are receiving infliximab treatment intensification based on endoscopic findings of exacerbations than in patients whose treatment is based on clinical symptoms.

Role of endocytosis and trans-endocytosis in ICOS costimulator-induced downmodulation of the ICOS Ligand

The interaction between the T-lymphocyte costimulatory molecule ICOS and its ligand (ICOS-L) is needed for efficient immune responses, but expression levels are tightly controlled, as altered expression of ICOS or ICOS-L may lead to immunodeficiency, or favor autoimmune diseases and tumor growth. Using cells of mouse B cell lymphoma (M12.C3) and melanoma (B16), or hamster CHO cells transfected with various forms of mouse ICOS-L, and ICOS⁺ T cell lines, we show that, within minutes, ICOS induces significant downmodulation of surface ICOS-L that is largely mediated by endocytosis and trans-endocytosis. So, after interaction with ICOS⁺ cells, ICOS-L was found inside permeabilized cells, or in cell lysates, with significant transfer of ICOS from ICOS⁺ T cells to ICOS-L-expressing cells, and simultaneous loss of surface ICOS by the T cells. Data from cells expressing ICOS-L mutants show that conserved, functionally important residues in the cytoplasmic domain of mouse ICOS-L (Arg₃₀₀ , Ser₃₀₇ and Tyr₃₀₈ ), or removal of ICOS-L cytoplasmic tail have minor effect on its internalization. Internalization was dependent on temperature, and was partially dependent on actin polymerization, the GTPase dynamin, protein kinase C, or the integrity of lipid rafts. In fact, a fraction of ICOS-L was detected in lipid rafts. On the other hand, proteinase inhibitors had negligible effects on early modulation of ICOS-L from the cell surface. Our data add a new mechanism of control of ICOS-L expression to the regulation of ICOS-dependent responses.

ICOS+ Tregs: A Functional Subset of Tregs in Immune Diseases

Recent studies have reported the pathological effect of ICOS⁺ T cells, but ICOS signals also widely participate in anti-inflammatory responses, particularly ICOS⁺ regulatory T (Treg) cells. The ICOS signaling pathway endows Tregs with increased generation, proliferation, and survival abilities. Furthermore, there is enough evidence to suggest a superior capacity of ICOS⁺ Tregs, which is partly attributable to IL-10 induced by ICOS, yet the associated mechanism needs further investigation. In this review, we discuss the complicated role of ICOS⁺ Tregs in several classical autoimmune diseases, allergic diseases, and cancers and investigate the related therapeutic applications in these diseases. Moreover, we identify ICOS as a potential biomarker for disease treatment and prognostic prediction. In addition, we believe that anti-ICOS/ICOSL monoclonal antibodies exhibit excellent clinical application potential. A thorough understanding of the effect of ICOS⁺ Tregs and the holistic role of ICOS toward the immune system will help to improve the therapeutic schedule of diseases.

Aberrant Expressions of Co-stimulatory and Co-inhibitory Molecules in Autoimmune Diseases

Co-signaling molecules include co-stimulatory and co-inhibitory molecules and play important roles in modulating immune responses. The roles of co-signaling molecules in autoimmune diseases have not been clearly defined. We assessed the expressions of co-stimulatory and co-inhibitory molecules in autoimmune diseases through a bioinformatics-based study. By using datasets of whole-genome transcriptome, the expressions of 54 co-stimulatory or co-inhibitory genes in common autoimmune diseases were analyzed using Robust rank aggregation (RRA) method. Nineteen array datasets and 6 RNA-seq datasets were included in the RRA discovery study and RRA validation study, respectively. Significant genes were further validated in several autoimmune diseases including Graves' disease (GD). RRA discovery study suggested that CD160 was the most significant gene aberrantly expressed in autoimmune diseases (Adjusted P = 5.9E-12), followed by CD58 (Adjusted P = 5.7E-06) and CD244 (Adjusted P = 9.5E-05). RRA validation study also identified CD160 as the most significant gene aberrantly expressed in autoimmune diseases (Adjusted P = 5.9E-09). We further found that the aberrant expression of CD160 was statistically significant in multiple autoimmune diseases including GD (P < 0.05), and CD160 had a moderate role in diagnosing those autoimmune diseases. Flow cytometry confirmed that CD160 was differentially expressed on the surface of CD8⁺ T cells between GD patients and healthy controls (P = 0.002), which proved the aberrant expression of CD160 in GD at the protein level. This study suggests that CD160 is the most significant co-signaling gene aberrantly expressed in autoimmune diseases. Treatment strategy targeting CD160-related pathway may be promising for the therapy of autoimmune diseases.

The Use of Vedolizumab in Preventing Postoperative Recurrence of Crohn's Disease

BACKGROUND

Clinical and endoscopic recurrence are common after surgery in Crohn's disease (CD). Vedolizumab has been increasingly used to treat CD, however, its effectiveness in preventing postoperative recurrence remains unknown. We aimed to investigate the use of vedolizumab in the postoperative setting and compare the risk of recurrence between patients receiving vedolizumab and anti-tumor necrosis factor (TNF)-α agents.

METHODS

Medical records of CD patients who underwent surgery between April 2014 and June 2016 were reviewed. We first analyzed how frequently vedolizumab is used to prevent postoperative recurrence and compared the patient characteristics with those being treated with other therapies. Furthermore, the rates of endoscopic remission, defined as a simple endoscopic score for CD of 0, at 6-12 months after surgery were compared between patients receiving vedolizumab and anti-TNF-α agents. Clinical, biological, and histologic outcomes such as Harvey-Bradshaw index, C-reactive protein, and histologic inflammation also were compared between the 2 groups. Risks of recurrence were assessed by univariate, multivariate, and propensity score-matched analyses.

RESULTS

Among 203 patients that underwent a CD related surgery, 22 patients received vedolizumab as postoperative treatment. There were 58, 38, and 16 patients who received anti-TNF-α agents, immunomodulators, and metronidazole, respectively, whereas 69 patients were monitored without any medication. Patients receiving vedolizumab were young and frequently had perianal disease. Patients postoperatively treated with vedolizumab or anti-TNF-α agents were mostly treated with the same agent pre- and postoperatively. Rate of endoscopic remission at 6-12 months in the vedolizumab group was 25%, which was significantly lower as compared to anti-TNF-α agent group (66%, P = 0.01). Vedolizumab use was the only factor that was associated with an increased risk of endoscopic recurrence on both univariate (odds ratio (OR) 5.58, 95% confidence interval (CI) 1.51-24.3, P = 0.005) and multivariate analysis (OR 5.77, 95%CI 1.71-19.4, P = 0.005). The results were supported by a propensity score-matched analysis demonstrating lower rates of endoscopic remission (25 vs 69%, P = 0.03) in patients treated with vedolizumab as compared to anti-TNF-α agents.

CONCLUSION

In the present retrospective cohort study of real-world experience, vedolizumab was shown to be commonly used as postoperative treatment for CD especially in high risk patients. Multivariate and propensity score-matched analyses showed that postoperative endoscopic recurrence in CD was higher with vedolizumab than with anti-TNF-α agents, but further investigation including controlled trials is required before determining the utility of vedolizumab in preventing postoperative recurrence of CD.

Risk of Postoperative Complications Among Inflammatory Bowel Disease Patients Treated Preoperatively With Vedolizumab

OBJECTIVES

Vedolizumab is increasingly used to treat patients with ulcerative colitis (UC) and Crohn's disease (CD), however, its safety during the perioperative period remains unclear. We compared the 30-day postoperative complications among patients treated preoperatively with vedolizumab, anti-tumor necrosis factor (TNF)-α agents or non-biological therapy.

METHODS

The retrospective study cohort was comprised of patients receiving vedolizumab, anti-TNF-α agents or non-biological therapy within 4 weeks of surgery. The rates of 30-day postoperative complications were compared between groups using univariate and multivariate analysis. Propensity score-matched analysis was performed to compare the outcome between groups.

RESULTS

Among 443 patients (64 vedolizumab, 129 anti-TNF-α agents, and 250 non-biological therapy), a total of 144 patients experienced postoperative complications (32%). In multivariate analysis, age >65 (odds ratio (OR) 3.56, 95% confidence interval (CI) 1.30-9.76) and low-albumin (OR 2.26, 95% CI 1.28-4.00) were associated with increased risk of 30-day postoperative complications. For infectious complications, steroid use (OR 3.67, 95% CI 1.57-8.57, P=0.003) and low hemoglobin (OR 3.03, 95% CI 1.32-6.96, P=0.009) were associated with increased risk in multivariate analysis. Propensity score matched analysis demonstrated that the risks of postoperative complications were not different among patients preoperatively receiving vedolizumab, anti-TNF-α agents or non-biological therapy (UC, P=0.40; CD, P=0.35).

CONCLUSIONS

In the present study, preoperative vedolizumab exposure did not affect the risk of 30-day postoperative complications in UC and CD. Further, larger studies are required to confirm our findings.

Maternal microchimerism in pediatric inflammatory bowel disease

Inflammatory bowel disease (IBD) shares many immunologic and clinical characteristics with graft versus host disease caused by allogeneic T lymphocytes after hematopoietic cell transplantation. Since maternal cells are known to enter the fetal circulation in a high proportion of pregnancies, we hypothesized that maternal engraftment in the fetus results in immune sequelae that can lead to IBD.

METHOD

The presence and extent of maternal microchimerism in tissues and blood samples from patients with Crohn's, Ulcerative colitis (UC), and control groups were determined using kinetic Polymerase Chain Reaction (kPCR) to detect maternal- and patient-specific HLA types. In addition, fluorescent in situ hybridization (FISH) was employed to detect maternal cells in biopsies from patients with IBD.

RESULTS

Using kPCR, maternal microchimerism was observed in 9 of the 16 (56%) patients with IBD and 6 out of 15 of the control group (40%) (P=NS). Five of 10 Crohn's patients had evidence of maternal microchimerism (50%) (P=NS). Four of six UC patients had evidence of maternal microchimerism in gut tissues (67%) (P=NS). There was no correlation between maternal michrochimerism and disease activity, disease location or granulomas in patients with IBD. Using FISH, five male Crohn's and five male UC patient's intestinal biopsies were analyzed for maternal microchimerism. No maternal cells were identified.

CONCLUSION

There is nothing in the data to suggest that patients with IBD differ from disease controls in their frequency of maternal microchimerism in either blood or gut mucosal tissues. These data suggest that maternal microchimerism in blood and biopsies is a relatively common phenomenon that has neither positive nor negative impact on IBD.

The genomic architecture of mastitis resistance in dairy sheep

Background

Mastitis is the most prevalent disease in dairy sheep with major economic, hygienic and welfare implications. The disease persists in all dairy sheep production systems despite the implementation of improved management practises. Selective breeding for enhanced mastitis resistance may provide the means to further control the disease. In the present study, we investigated the genetic architecture of four mastitis traits in dairy sheep. Individual animal records for clinical mastitis occurrence and three mastitis indicator traits (milk somatic cell count, total viable bacterial count in milk and the California mastitis test) were collected monthly throughout lactation for 609 ewes of the Greek Chios breed. All animals were genotyped with a custom-made 960-single nucleotide polymorphism (SNP) DNA array based on markers located in quantitative trait loci (QTL) regions for mastitis resistance previously detected in three other distinct dairy sheep populations.

Results

Heritable variation and strong positive genetic correlations were estimated for clinical mastitis occurrence and the three mastitis indicator traits. SNP markers significantly associated with these mastitis traits were confirmed on chromosomes 2, 3, 5, 16 and 19. We identified pathways, molecular interaction networks and functional gene clusters for mastitis resistance. Candidate genes within the detected regions were identified based upon analysis of an ovine transcriptional atlas and transcriptome data derived from milk somatic cells. Relevant candidate genes implicated in innate immunity included SOCS2, CTLA4, C6, C7, C9, PTGER4, DAB2, CARD6, OSMR, PLXNC1, IDH1, ICOS, FYB, and LYFR.

Conclusions

The results confirmed the presence of animal genetic variability in mastitis resistance and identified genomic regions associated with specific mastitis traits in the Chios sheep. The conserved genetic architecture of mastitis resistance between distinct dairy sheep breeds suggests that across-breed selection programmes would be feasible.

Electronic supplementary material

The online version of this article (doi:10.1186/s12864-017-3982-1) contains supplementary material, which is available to authorized users.

Systematic review with meta-analysis: the efficacy and safety of CT-P13, a biosimilar of anti-tumour necrosis factor-α agent (infliximab), in inflammatory bowel diseases

BACKGROUND

Biosimilars of anti-tumour necrosis factor (TNF)-α agents have now become clinically available for the treatment of inflammatory bowel diseases (IBD).

AIM

To perform a systematic review and meta-analysis to evaluate the efficacy and safety of biosimilars of anti-TNF-α agents in patients with IBD.

METHODS

Electronic databases were searched. The outcomes were the pooled rates of clinical response or remission, sustained clinical response or remission, and adverse events in patients with IBD induced with or switched to biosimilars of anti-TNF-α agents.

RESULTS

Eleven observational studies reporting outcomes in 829 patients treated with biosimilar of infliximab (CT-P13) were identified. The pooled rates of clinical response among Crohn's disease (CD) and ulcerative colitis (UC) at 8-14 weeks were 0.79 (95% confidence interval (CI) = 0.65-0.88) and 0.74 (95% CI = 0.65-0.82), respectively, and at 24-30 weeks were 0.77 (95% CI = 0.63-0.86) and 0.77 (95% CI = 0.67-0.85) respectively. Adverse events were rare (CD, 0.08 (95% CI = 0.02-0.26); UC, 0.08 (95% CI = 0.03-0.17)). The pooled rates of sustained clinical response among CD and UC after switching from infliximab to CT-P13 at 30-32 weeks were 0.85 (95% CI = 0.71-0.93) and 0.96 (95% CI = 0.58-1.00), respectively, and at 48-63 weeks were 0.75 (95% CI = 0.44-0.92) and 0.83 (95% CI = 0.19-0.99) respectively. Adverse events were rare (CD, 0.10, 95% CI = 0.02-0.31; UC, 0.22, 95% CI = 0.04-0.63).

CONCLUSIONS

CT-P13 was associated with excellent clinical efficacy and safety profile, supporting its use in the treatment of IBD.

Efficacy, safety and pharmacokinetics of biosimilars of anti-tumor necrosis factor-α agents in rheumatic diseases; A systematic review and meta-analysis

OBJECTIVE

To evaluate the efficacy and safety of biosimilars of anti-tumor necrosis factor (TNF)-α agents compared to their reference agents in immune mediated diseases.

METHODS

Electronic databases were searched for randomized controlled trials (RCTs) assessing the efficacy and safety of biosimilars of anti-TNF-α agents compared to their reference agents in patients with various immune mediated diseases. The outcomes were the rates of clinical response and adverse events among patients treated with biosimilars compared to their reference agents. Additionally, occurrence of anti-drug antibodies with the use of biosimilars was compared to the reference agents.

RESULTS

Nine studies reporting outcomes in 3291 patients with rheumatoid arthritis (RA) and ankylosing spondylitis (AS) were identified (5 infliximab, 2 adalimumab, and 2 etanercept). No RCTs in other diseases were found. Biosimilars of infliximab showed similar rates of clinical response compared to the reference agent in RA and AS. Frequency of anti-drug antibody and adverse events were similar except for a slightly, but significantly, higher risk of upper respiratory tract infections with biosimilar (RR 1.54, P = 0.047, 95% confidence interval (CI) = 1.01-2.37). Biosimilar of adalimumab showed no differences among any outcomes compared to the reference agent. Biosimilars of etanercept showed no differences for clinical response and frequency of adverse events, but showed a significantly lower rate of anti-drug antibodies at 24-30 weeks (RR 0.05, P <0.0001%, 95% CI = 0.01-0.21).

CONCLUSION

In the present study, biosimilars of anti-TNF-α agents had an overall comparable efficacy and safety profile compared to their reference agents in RA and AS supporting their use for these conditions.

Pulmonary sarcoidosis is associated with high-level inducible co-stimulator (ICOS) expression on lung regulatory T cells--possible implications for the ICOS/ICOS-ligand axis in disease course and resolution

Sarcoidosis is a granulomatous inflammatory disorder of unknown aetiology. The increased frequency of activated lung CD4(+) T cells with a T helper type 1 (Th1) cytokine profile in sarcoidosis patients is accompanied by a reduced proportion and/or impaired function of regulatory T cells (Tregs ). Here we evaluated the expression of the inducible co-stimulator (ICOS) on lung and blood CD4(+) T cell subsets in sarcoidosis patients with different prognosis, by flow cytometry. Samples from the deep airways were obtained by bronchoalveolar lavage (BAL). We show that Tregs from the inflamed lung of sarcoidosis patients were characterized by a unique ICOS(high) phenotype. High-level ICOS expression was restricted to Tregs from the inflamed lung and was absent in blood Tregs of sarcoidosis patients as well as in lung and blood Tregs of healthy volunteers. In addition, lung Tregs exhibited increased ICOS expression compared to sarcoid-specific lung effector T cells. Strikingly, ICOS expression on Tregs was in particularly high in the lungs of Löfgren's syndrome (LS) patients who present with acute disease which often resolves spontaneously. Moreover, blood monocytes from LS patients revealed increased ICOS-L levels compared to healthy donors. Sarcoidosis was associated with a shift towards a non-classical monocyte phenotype and the ICOS-L(high) phenotype was restricted to this particular monocyte subset. We propose a potential implication of the ICOS/ICOS-L immune-regulatory axis in disease activity and resolution and suggest to evaluate further the suitability of ICOS as biomarker for the prognosis of sarcoidosis.

Pattern recognition receptor signaling in human dendritic cells is enhanced by ICOS ligand and modulated by the Crohn's disease ICOSLG risk allele

Inflammatory bowel disease (IBD) is characterized by dysregulated intestinal immune homeostasis and cytokine secretion. Multiple loci are associated with IBD, but a functional explanation is missing for most. Here we found that pattern-recognition receptor (PRR)-induced cytokine secretion was diminished in human monocyte-derived dendritic cells (MDDC) from rs7282490 ICOSLG GG risk carriers. Homotypic interactions between the costimulatory molecule ICOS and the ICOS ligand on MDDCs amplified nucleotide-binding oligomerization domain 2 (NOD2)-initiated cytokine secretion. This amplification required arginine residues in the ICOSL cytoplasmic tail that recruited the adaptor protein RACK1 and the kinases PKC and JNK leading to PKC, MAPK, and NF-κB activation. MDDC from rs7282490 GG risk-carriers had reduced ICOSL expression and PRR-initiated signaling and this loss-of-function ICOSLG risk allele associated with an ileal Crohn's disease phenotype, similar to polymorphisms in NOD2. Taken together, ICOSL amplifies PRR-initiated outcomes, which might contribute to immune homeostasis.

Enhanced inducible costimulator ligand (ICOS-L) expression on dendritic cells in interleukin-10 deficiency and its impact on T-cell subsets in respiratory tract infection

An association between inducible costimulator ligand (ICOS-L) expression and interleukin (IL)-10 production by dendritic cells (DCs) has been commonly found in infectious disease. DCs with higher ICOS-L expression and IL-10 production are reportedly more efficient in inducing regulatory T cells (Tregs). Here we use the Chlamydia muridarum (Cm) lung infection model in IL-10 knockout (KO) mice to test the relationship between IL-10 production and ICOS-L expression by DCs. We examined ICOS-L expression, the development of T-cell subsets, including Treg, Th17 and Th1 cell, in the background of IL-10 deficiency and its relationship with ICOS-L/ICOS signaling after infection. Surprisingly, we found that the IL-10 KO mice exhibited significantly higher ICOS-L expression by DCs. Moreover, IL-10 KO mice showed lower Tregs but higher Th17 and Th1 responses, but only the Th17 response depended on ICOS signaling. Consistently, most of the Th17 cells were ICOS⁺, whereas most of the Th1 cells were ICOS⁻ in the infected mice. Furthermore, neutralization of IL-17 in IL-10 KO mice significantly exacerbated lung infection. The data suggest that ICOS-L expression on DC may be negatively regulated by IL-10 and that ICOS-L expression on DC in the presence or absence of IL-10 costimulation may promote Treg or Th17 response, without significant impact on Th1.

Costimulatory pathways: physiology and potential therapeutic manipulation in systemic lupus erythematosus

System lupus erythematosus (SLE) is an immune-complex-mediated autoimmune condition with protean immunological and clinical manifestation. While SLE has classically been advocated as a B-cell or T-cell disease, it is unlikely that a particular cell type is more pathologically predominant than the others. Indeed, SLE is characterized by an orchestrated interplay amongst different types of immunopathologically important cells participating in both innate and adaptive immunity including the dendritic cells, macrophages, neutrophils and lymphocytes, as well as traditional nonimmune cells such as endothelial, epithelial, and renal tubular cells. Amongst the antigen-presenting cells and lymphocytes, and between lymphocytes, the costimulatory pathways which involve mutual exchange of information and signalling play an essential role in initiating, perpetuating, and, eventually, attenuating the proinflammatory immune response. In this review, advances in the knowledge of established costimulatory pathways such as CD28/CTLA-4-CD80/86, ICOS-B7RP1, CD70-CD27, OX40-OX40L, and CD137-CD137L as well as their potential roles involved in the pathophysiology of SLE will be discussed. Attempts to target these costimulatory pathways therapeutically will pave more potential treatment avenues for patients with SLE. Preliminary laboratory and clinical evidence of the potential therapeutic value of manipulating these costimulatory pathways in SLE will also be discussed in this review.

Histone deacetylase 6 and heat shock protein 90 control the functions of Foxp3(+) T-regulatory cells

Foxp3(+) T-regulatory cells (Tregs) are key to immune homeostasis such that their diminished numbers or function can cause autoimmunity and allograft rejection. Foxp3(+) Tregs express multiple histone/protein deacetylases (HDACs) that regulate chromatin remodeling, gene expression, and protein function. Pan-HDAC inhibitors developed for oncologic applications enhance Treg production and Treg suppression function but have limited nononcologic utility given their broad actions and various side effects. We show, using HDAC6-deficient mice and wild-type (WT) mice treated with HDAC6-specific inhibitors, that HDAC6 inhibition promotes Treg suppressive activity in models of inflammation and autoimmunity, including multiple forms of experimental colitis and fully major histocompatibility complex (MHC)-incompatible cardiac allograft rejection. Many of the beneficial effects of HDAC6 targeting are also achieved by inhibition of the HDAC6-regulated protein heat shock protein 90 (HSP90). Hence, selective targeting of a single HDAC isoform, HDAC6, or its downstream target, HSP90, can promote Treg-dependent suppression of autoimmunity and transplant rejection.

Report of the ECCO workshop on anti-TNF therapy failures in inflammatory bowel diseases: biological roles and effects of TNF and TNF antagonists

This second section of the first ECCO pathogenesis workshop on anti-TNF therapy failures in inflammatory bowel diseases addresses the biological roles of TNFα and the effects and mechanisms of action of TNFα antagonists. Mechanisms underlying their failure, including induction of TNF-independent inflammatory pathways and phenomena of paradoxical inflammation are discussed.

Inhibition of HDAC9 increases T regulatory cell function and prevents colitis in mice

BACKGROUND & AIMS

Foxp3+ T regulatory cells (Tregs) help prevent autoimmunity, and increases in their numbers of functions could decrease the development of inflammatory bowel disease. Like other cells, Foxp3+ Tregs express histone/protein deacetylases (HDACs), which regulate chromatin remodeling and gene expression. We investigated whether disruption of a specific class IIa HDAC, HDAC9, activity in Tregs affects the pathogenesis of colitis in mice.

METHODS

We tested the effects of various HDAC inhibitors (HDACi) in models of colitis using wild-type mice. We also transferred Tregs and non-Treg cells from HDAC9-/- or wild-type mice to immunodeficient mice. HDAC9 contributions to the functions of Tregs were determined during development and progression of colitis.

RESULTS

Pan-HDACi, but not class I-specific HDACi, increased the functions of Foxp3+ Tregs, prevented colitis, and reduced established colitis in mice, indicating the role of class II HDACs in controlling Treg function. The abilities of pan-HDACi to prevent/reduce colitis were associated with increased numbers of Foxp3+ Tregs and their suppressive functions. Colitis was associated with increased local expression of HDAC9; HDAC9-/- mice resistant to development of colitis. HDAC9-/- Tregs expressed increased levels of the heat shock protein (HSP) 70, compared with controls. Immunoprecipitation experiments indicated an interaction between HSP70 and Foxp3. Inhibition of HSP70 reduced the suppressive functions of HDAC9-/- Tregs; Tregs that overexpressed HSP70 had increased suppressive functions.

CONCLUSIONS

Strategies to decrease HDAC9 expression or function in Tregs or to increase expression of HSP70 might be used to treat colitis and other autoimmune disorders.

ICOS promotes IL-17 synthesis in colonic intraepithelial lymphocytes in IL-10-/- mice

In the absence of IL-10, colonic inflammation ensues, which is characterized by high levels of IL-17. Here, we demonstrate a direct correlation between ICOS expression and IL-17 production in cIELs. IL-10(-/-) mice had increased numbers of cIELs and greater colon weight. Although the CD69 early activation antigen was expressed on cIELs from normal and IL-10(-/-) mice, ICOS was expressed only on cIELs from IL-10(-/-) mice. IL-17-producing cells in IL-10(-/-) mice consisted of CD4(+) and CD8(+) cIELs; however, CD4(+) cells were the predominant IL-17-producing cell population. Culture of cIELs from IL-10(-/-) mice with IL-23 resulted in an increase in ICOS and IL-17 expression, whereas IL-10 suppressed expression of ICOS and IL-17. This occurred in primary cultures and recall stimulation experiments. The ICOS ligand B7RP-1 was up-regulated on colonic epithelial cells and on a population of large granular leukocytes during inflammation. Culture of cIELs with B7RP-1(+) DCs enhanced IL-17A production from normal cIELs but failed to do so using cIELs from ICOS(-/-) mice. In vivo treatment of IL-10(-/-) mice with antibody to ICOS resulted in a significant reduction in colonic pathology. These findings implicate ICOS as an activational signal of Th17 cells during chronic intestinal inflammation, and they suggest that under some conditions, control of ICOS expression may help to suppress chronic intestinal inflammation.

Th1/Th17 immune response is induced by mesenteric lymph node dendritic cells in Crohn's disease

BACKGROUND & AIMS

Dendritic cells (DCs) possess the most potent ability to induce acquired immunity. However, their involvement in the pathogenesis of Crohn's disease (CD) has not yet been determined. We aimed to establish the immune status of mesenteric lymph nodes, the major gut-associated lymphoid tissue, and isolated DCs and determine their involvement in the pathogenesis of CD.

METHODS

CD4(+) T cells and DCs were isolated from mesenteric lymph nodes of CD, ulcerative colitis, and normal control. The immune status of CD4(+) T cells was analyzed by cytokine production and transcriptional profile. Surface phenotype of DCs was analyzed by flow cytometry. Cytokine production by myeloid DCs was analyzed by real-time polymerase chain reaction and exogenous bacterial stimulation. Immune stimulating activity of DCs was determined by mixed lymphocyte reaction.

RESULTS

In CD, mesenteric lymph node CD4(+) T cells produced higher amounts of interferon-gamma and interleukin (IL)-17 compared with ulcerative colitis and normal control, and this was dictated by increased T-bet and retinoic acid-related orphan receptor-gamma expression. Three subtypes of DCs, myeloid DC, plasmacytoid DC, and mature DC, were identified in all groups. When stimulated with exogenous bacterial derivative, myeloid DCs from CD produced a higher amount of IL-23 and a lower amount of IL-10. Myeloid DCs from CD induced stronger T helper cell (Th)1 immune response in mixed lymphocyte reaction compared with those from ulcerative colitis and normal control.

CONCLUSIONS

Our findings revealed that mesenteric lymph node is the key pathogenic location of CD elicited by the unique cytokine milieu produced by DCs leading to a dysregulated Th1/Th17 immune response.

Antigen-independent adhesion and cell spreading by inducible costimulator engagement inhibits T cell migration in a PI-3K-dependent manner

Engagement of the costimulatory protein ICOS activates effector/memory T cells in tissue by enhancing TCR-mediated proliferation and cytokine production. We now report that in an antigen-independent manner, ICOS also induces adhesion and spreading in human effector/memory T cells, consequently inhibiting cell migration. T cell spreading and elongation after ICOS ligation are accompanied by the formation of two types of actin-rich membrane protrusions: thin, finger-like structures similar to filopodia and short, discrete microspikes. Although filopodia/microspike formation occurs independently of the PI-3K signaling cascade, ICOS-mediated T cell elongation depends on PI-3K activity, which inhibits the accumulation of GTP-bound RhoA. Further inhibition of RhoA activation exacerbates the ICOS-mediated, elongated phenotype. We propose that in inflamed tissue, ICOS engagement by ICOS ligand on a professional or nonprofessional APC prevents the forward motility of the T cell by inhibiting RhoA-dependent uropod retraction. The resulting ICOS-induced T cell spreading and filopodia/microspike formation may promote antigen recognition by enhancing a T cell's scanning potential of an adherent APC surface.

Down-regulation of ICOS ligand by interaction with ICOS functions as a regulatory mechanism for immune responses

Although it is well-known that the ICOS-ICOS ligand (ICOSL) costimulatory pathway is important for many immune responses, recent accumulated evidence suggests that dysregulation of this pathway may lead to and/or exaggerate autoimmune responses. ICOS is induced on the cell surface after T cell activation. Similarly, ICOSL is up-regulated on APCs by several mitogenic stimuli. However, the mechanism regulating expression of the ICOS-ICOSL pair, and the significance of controlling their expression for an appropriate immune response, is largely unknown. To gain a better understanding of the importance of fine control of the ICOS-ICOSL costimulatory pathway, we generated ICOS-transgenic (Tg) mice that have high constitutive expression of ICOS in all T cells. Using ICOS-Tg mice, we studied whether in vivo immune responses were affected. Unexpectedly, we first found that ICOS-Tg mice exhibited a phenotype resembling ICOS-deficient mice in their Ag-specific Ab response, such as a defect in class switch recombination. Further examination revealed that ICOSL expression of APCs was significantly suppressed in ICOS-Tg mice. Interestingly, suppression of ICOSL was induced by interaction of ICOSL with ICOS, and it seemed to be regulated at the posttranscriptional level. The suppressive effect of the ICOS-ICOSL interaction overcame the positive effect of CD40 or B cell activation factor of the TNF family (BAFF) stimulation on ICOSL expression. Together, our studies demonstrate a novel mechanism for the regulation of ICOSL expression in vivo and suggest that the ICOS costimulatory pathway is subject to negative feedback regulation by ICOSL down-regulation in response to ICOS expression.

Salmonella enterica serovar Choleraesuis derivatives harbouring deletions in rpoS and phoP regulatory genes are attenuated in pigs, and survive and multiply in porcine intestinal macrophages and fibroblasts, respectively

Live attenuated Salmonella enterica strains have been extensively studied as potential vectors for the oral delivery of heterologous antigens. Due to its ability to target immune cells, its specific mechanism for crossing the intestinal barrier, and its swine-restricted tropism, S. enterica subspecies enterica serovar Choleraesuis (S. Choleraesuis) has attracted a great deal of interest for the production of bacterial-based oral carriers specifically adapted to swine. In this study, two mutants of S. Choleraesuis were constructed and their attenuation and intracellular fate analysed with the purpose of engineering new attenuated live strains with improved properties as oral vaccine carriers. Those strains harboured a specific deletion either within the phoP or rpoS genes, which encode virulence-related regulators in S. Typhimurium. In comparison to the wild-type parental S. Choleraesuis, the mutant strains, especially DeltaphoP, were extremely low in virulence in the murine model and in the natural host, the pig. Moreover, when compared with a commercial live vaccine strain, SC-54, the two mutants showed a higher level of attenuation in mice and DeltaphoP also in pigs. In addition, DeltarpoS and DeltaphoP presented a proliferation and survival phenotype within swine intestinal primary fibroblast and macrophage cell cultures, respectively. Collectively, the present results indicate that the DeltarpoS and DeltaphoP strains of S. Choleraesuis gather adequate features to be potential candidates for vaccine vectors for the specific delivery of heterologous antigens adapted to pigs.

Massive but selective cytokine dysregulation in the colon of IL-10-/- mice revealed by multiplex analysis

IL-10-deficient mice develop enterocolitis due to a failure of cytokine regulation; however, the full scope of that response remains poorly defined. Using multiplex analysis to quantify the activity of 23 regulatory and effector cytokines produced by colonic leukocytes, we demonstrate a vast dysregulation process of 18 cytokines in IL-10-/- mice from 7 to 27 weeks of age. Of those, IL-12p40, IL-6, granulocyte macrophage colony-stimulating factor, IFN-gamma, IL-13 and monocyte chemoattractant protein-1 (MCP-1) had the highest single correlations with pathology (r = 0.7766-0.7016). Importantly, there were strong associations (r = 0.7071-0.9074) between those cytokines and as many as 10 additional cytokines, indicating a high degree of cytokine complexity as disease progressed. IL-17 was notable in that it was produced at high levels by colonic leukocytes from IL-10-/- mice with pathology ranging from mild to severe, though it was not produced by healthy IL-10-/- mice lacking pathology. Tumor necrosis factor alpha (TNFalpha) by itself displayed only a modest association with pathology (r = 0.6340), ranking sixth lowest, though it cross-correlated strongly with the synthesis of 12 other cytokines, implying that the destructive effects associated with TNFalpha may be due to interactions of multiple cytokine activities. IL-23 expression did not correlate with pathology, possibly suggesting that IL-23 is involved in the initiation but not the perpetuation of inflammation. Four cytokines (IL-2, IL-3, IL-4 and IL-5) remained negative in IL-10-/- mice, demonstrating that cytokine dysregulation was not universal. These findings emphasize the need to better understand cytokine networks in chronic inflammation and they provide a rationale for combining immunotherapies in the treatment of intestinal inflammation.

T-cell activation in the intestinal mucosa

The vast majority of peripheral T cells exist as resting lymphocytes until a signal for activation has been received. In response to antigen, this activation involves ligation of the T-cell receptor (TCR) and signal transmission through the CD3 complex, which then initiates a cascade of intracellular events that lead to the expression of genes used in T-cell activation. T-cell activation also requires soluble mediators in the form of cytokines and chemokines that regulate the process in both positive and negative ways, and costimulatory signals received in conjunction with TCR/CD3 signaling are important in the activation of T cells. Unlike T cells in other peripheral immune compartments, small and large intestinal intraepithelial lymphocytes (IELs) bear some but not all properties of activated T cells, suggesting that they constitute a large population of 'partially activated' effector cells. Thus, regulation of the IEL activation process must be held in tight check, yet it must be ready to respond to foreign antigen rapidly and effectively. We discuss how costimulatory molecules may hold the key to controlling IEL activation through a multiphase process beginning with cells that have already entered into the early stage of activation.

Association of CTLA-4 gene microsatellite polymorphism with ulcerative colitis in Chinese patients

Ulcerative colitis (UC) is characterized by chronic intestinal inflammation as a result of an exaggerated T cell response. Cytotoxic T lymphocyte associated antigen-4 (CTLA-4), expressed mainly in activated T cells, inhibits T cell activation and proliferation by combining B7 through competing CD28 and maintains immune homeostasis. Polymorphisms of the CTLA-4 gene are known to be associated with several autoimmune diseases. The aim of this study was to investigate the association between the CTLA-4 gene microsatellite polymorphism and UC in Chinese patients. Unrelated 100 Chinese patients with UC and 140 healthy controls were studied. The (AT) repeats in the 3' untranslated region of exon 4 of the CTLA-4 gene were amplified by allele-specific polymerase chain reaction (PCR). The amplified products were electrophoresed on a 12% polyacrylamide gel, followed by silver staining. Twenty alleles were found in Chinese patients and healthy controls. The 122-bp allele was increased in UC compared with healthy controls (9.5% vs 0.7%, P = 0.0001/Pc = 0.002, OR = 14.591, 95%CI 3.357-63.420). The frequency of the longer alleles (>or=118 bp) of UC was higher than that in healthy controls (26% vs 4%, P = 0.0001/Pc = 0.0002, OR = 7.644, 95%CI 3.950-14.792), but was not associated with location and severity of the disease. Furthermore, the longer alleles were not associated with haplotypes of C-318T/A+49G of the CTLA-4 gene in Chinese patients with UC. The longer alleles of the CTLA-4 gene microsatellite polymorphism were strongly associated with UC in Chinese patients.

Upregulation of ICOS on CD43+ CD4+ murine small intestinal intraepithelial lymphocytes during acute reovirus infection

Murine intestinal intraepithelial lymphocytes (IELs) can be classified according to expression of a CD43 glycoform recognized by the S7 monoclonal antibody. In this study, we examined the response of S7+ and S7- IELs in mice during acute reovirus serotype 3 (Dearing strain) infection, which was confirmed by virus-specific real-time PCR. In vivo proliferation increased significantly for both S7- and S7+ IELs on day 4 post-infection as determined by BrdU incorporation; however, expression of the inducible costimulatory (ICOS) molecule, which peaked on day 7 post-infection, was upregulated on S7+ CD4+ T cells, most of which were CD4+8- IELs. In vitro ICOS stimulation by syngeneic peritoneal macrophages induced IFN-gamma secretion from IELs from day 7 infected mice, and was suppressed by treatment with anti-ICOS mAb. Additionally, IFN-gamma mRNA increased in CD4+ IELs on day 6 post-infection. These findings indicate that S7- and S7+ IELs are differentially mobilized during the immune response to reovirus infection; that the regulated expression of ICOS is associated with S7+ IELs; and that stimulation of IELs through ICOS enhances IFN-gamma synthesis during infection.

CTLA4/CT60 polymorphism is not relevant in susceptibility to autoimmune inflammatory intestinal disorders

The aim of this work was to investigate the possible influence of the recently described CT60 A/G dimorphism of the CTLA4 (cytotoxic T-lymphocyte antigen 4) gene in the susceptibility to two different autoimmune inflammatory intestinal disorders, inflammatory bowel disease (IBD) and celiac disease. We analyzed a case-control cohort composed of 528 Spanish patients with IBD (284 with Crohn disease and 244 with ulcerative colitis) and 454 unrelated healthy individuals, and additionally a group of 90 celiac disease families. CT60 genotyping was performed with a TaqMan 5' allelic discrimination assay. After comparing patients with IBD with the control population, we found no significant deviation in the distribution of the alleles or genotypes of CTLA4/CT60 dimorphism. In addition, by means of familial and case-control analysis, no evidence for a statistically significant association was observed between CTLA4/CT60 and celiac disease susceptibility. Therefore, our results suggest that the CTLA4/CT60 polymorphism does not play a major role in inflammatory intestinal disorders.

Functional expression of 4-1BB (CD137) in the inflammatory tissue in Crohn's disease

4-1BB ligand (L) expressed on antigen presenting cells (APC) interacts with 4-1BB, expressed on activated T cells and this interaction costimulates T cells to secrete cytokines and to proliferate. We investigated whether 4-1BB/4-1BBL interactions might be involved in the pathogenesis of Crohn's disease (CD). In immunohistochemistry, we found 4-1BB expression on lamina propria (LP) cells in inflamed and to a lesser extend in non-inflamed gut tissue from CD patients. mRNA levels for 4-1BB were also elevated in intestinal CD tissue. In contrast, only few 4-1BB-expressing cells were found in inflamed tissue from ulcerative colitis (UC) patients and almost no positive cells were found in control intestinal tissue. 4-1BB expression was better sustained on in vitro activated lamina propria T cells from CD patients compared to controls. Finally, agonistic anti-4-1BB antibody enhanced interferon-gamma (IFN-gamma) production and proliferation of lamina propria T cells from CD patients. Taken together, our data suggest that 4-1BB/4-1BBL interactions contribute to the persistence of gut inflammation in CD.