Immune-Mediated Inflammatory Diseases Awareness and Management among Physicians Treating Patients with Inflammatory Bowel Disease: An IG-IBD Survey

(1) Background: Inflammatory bowel disease (IBD) is frequently associated to other immune-mediated inflammatory diseases (IMIDs). This study aims at assessing physicians' awareness of the issue and the current status of IMID management. (2) Methods: A web-based survey was distributed to all 567 physicians affiliated to IG-IBD. (3) Results: A total of 249 (43.9%) physicians completed the survey. Over 90% of the responding physicians were gastroenterology specialists, primarily working in public hospitals. About 51.0% of the physicians had access to an integrated outpatient clinic, where gastroenterologists collaborated with rheumatologists and 28.5% with dermatologists. However, for 36.5% of physicians, integrated ambulatory care was not feasible. Designated appointment slots for rheumatologists and dermatologists were accessible to 72.2% and 58.2% of physicians, respectively, while 20.1% had no access to designated slots. About 5.2% of physicians report investigating signs or symptoms of IMIDs only during the initial patient assessment. However, 87.9% inquired about the presence of concomitant IMIDs at the initial assessment and actively investigated any signs or symptoms during subsequent clinical examination. (4) Conclusions: While Italian physicians recognize the importance of IMIDs associated with IBD, organizational challenges impede the attainment of optimal multidisciplinary collaboration. Efforts should be directed toward enhancing practical frameworks to improve the overall management of these complex conditions.

Immune system and gut microbiota senescence in elderly IBD patients

In inflammatory bowel disease (IBD), the loss of immune tolerance against gut microbiota causes chronic inflammation and the progressive accumulation of organ damage in genetically susceptible individuals. In the elderly, IBD is often characterized by a different disease behavior when compared with pediatric and young adult disease. Besides disease behavior, another aspect of the multifaceted impact of age on elderly IBD course is increased susceptibility to infections. In this context, age-of-onset-dependent IBD behavior and clinical course are two major contributors to immune system senescence and change of gut microbiota in older subjects. Here, we review the available literature linking immunosenescence and age-dependent changes in the gut microbiota composition to IBD pathogenesis speculating on their possible implications in disease expression in this age class.

Defining Comprehensive Disease Control for Use as a Treatment Target for Ulcerative Colitis in Clinical Practice: International Delphi Consensus Recommendations

BACKGROUND AND AIMS

Treatment of ulcerative colitis [UC] requires a patient-centric definition of comprehensive disease control that considers improvements in aspects not typically captured by classical landmark trial endpoints. In an international initiative, we reviewed aspects of UC that affect patients and/or indicate mucosal inflammation, to achieve consensus on which aspects to combine in a definition of comprehensive disease control, using a modified Delphi process.

METHODS

The Delphi panel comprised 12 gastroenterologists and one patient advocate. Two gastroenterologists were elected as chairs and did not vote. To inform statements, we asked 18 patients and the panel members about their experiences of remission and reviewed published literature. Panel members voted on statements anonymously in three rounds, with a live discussion before Round 3. Consensus was met if ≥67% of the panel agreed. Statements without consensus in Rounds 1 and 2 were revised or discarded after Round 3.

RESULTS

The panel agreed to measure individual patient benefit using a definition of comprehensive disease control that combines aspects currently measured in trials [rectal bleeding, stool frequency, disease-related quality of life, endoscopy, histological inflammatory activity, inflammatory biomarkers, and corticosteroid use] with additional patient-reported symptoms [bowel urgency, abdominal pain, extraintestinal manifestations, fatigue, and sleep disturbance]. The panel agreed on scoring systems and thresholds for many aspects.

CONCLUSIONS

Using a robust methodology, we defined comprehensive disease control in UC. Next, we will combine the measurement and scoring of these aspects into a multicomponent tool and will adopt comprehensive disease control as a treatment target in clinical practice and trials.

IL10 Secretion Endows Intestinal Human iNKT Cells with Regulatory Functions Towards Pathogenic T Lymphocytes

BACKGROUND AND AIMS

Invariant natural killer T [iNKT] cells perform pleiotropic functions in different tissues by secreting a vast array of pro-inflammatory and cytotoxic molecules. However, the presence and function of human intestinal iNKT cells capable of secreting immunomodulatory molecules such as IL-10 has never been reported so far. Here we describe for the first time the presence of IL10-producing iNKT cells [NKT10 cells] in the intestinal lamina propria of healthy individuals and of Crohn's disease [CD] patients.

METHODS

Frequency and phenotype of NKT10 cells were analysed ex vivo from intestinal specimens of Crohn's disease [n = 17] and controls [n = 7]. Stable CD-derived intestinal NKT10 cell lines were used to perform in vitro suppression assays and co-cultures with patient-derived mucosa-associated microbiota. Experimental colitis models were performed by adoptive cell transfer of splenic naïve CD4+ T cells in the presence or absence of IL10-sufficient or -deficient iNKT cells. In vivo induction of NKT10 cells was performed by administration of short chain fatty acids [SCFA] by oral gavage.

RESULTS

Patient-derived intestinal NKT10 cells demonstrated suppressive capabilities towards pathogenic CD4+ T cells. The presence of increased proportions of mucosal NKT10 cells associated with better clinical outcomes in CD patients. Moreover, an intestinal microbial community enriched in SCFA-producing bacteria sustained the production of IL10 by iNKT cells. Finally, IL10-deficient iNKT cells failed to control the pathogenic activity of adoptively transferred CD4+ T cells in an experimental colitis model.

CONCLUSIONS

These results describe an unprecedentd IL10-mediated immunoregulatory role of intestinal iNKT cells in controlling the pathogenic functions of mucosal T helper subsets and in maintaining the intestinal immune homeostasis.

Quercetin and its derivates as antiviral potentials: A comprehensive review

Quercetin, widely distributed in fruits and vegetables, is a flavonoid known for its antioxidant, antiviral, antimicrobial, and antiinflammatory properties. Several studies highlight the potential use of quercetin as an antiviral, due to its ability to inhibit the initial stages of virus infection, to be able to interact with proteases important for viral replication, and to reduce inflammation caused by infection. Quercetin could also be useful in combination with other drugs to potentially enhance the effects or synergistically interact with them, in order to reduce their side effects and related toxicity. Since there is no comprehensive compilation about antiviral activities of quercetin and derivates, the aim of this review is providing a summary of their antiviral activities on a set of human viral infections along with mechanisms of action. Thus, the following family of viruses are examined: Flaviviridae, Herpesviridae, Orthomyxoviridae, Coronaviridae, Hepadnaviridae, Retroviridae, Picornaviridae, Pneumoviridae, and Filoviridae.

Activities related to inflammatory bowel disease management during and after the coronavirus disease 2019 lockdown in Italy: How to maintain standards of care

BACKGROUND AND AIMS

Restructuring activities have been necessary during the lockdown phase of the coronavirus disease 2019 (COVID-19) pandemic. Few data are available on the post-lockdown phase in terms of health-care procedures in inflammatory bowel disease (IBD) care, and no data are available specifically from IBD units. We aimed to investigate how IBD management was restructured during the lockdown phase, the impact of the restructuring on standards of care and how Italian IBD units have managed post-lockdown activities.

METHODS

A web-based online survey was conducted in two phases (April and June 2020) among the Italian Group for IBD affiliated units within the entire country. We investigated preventive measures, the possibility of continuing scheduled visits/procedures/therapies because of COVID-19 and how units resumed activities in the post-lockdown phase.

RESULTS

Forty-two referral centres participated from all over Italy. During the COVID-19 lockdown, 36% of first visits and 7% of follow-up visits were regularly done, while >70% of follow-up scheduled visits and 5% of first visits were done virtually. About 25% of scheduled endoscopies and bowel ultrasound scans were done. More than 80% of biological therapies were done as scheduled. Compared to the pre-lockdown situation, 95% of centres modified management of outpatient activity, 93% of endoscopies, 59% of gastrointestinal ultrasounds and 33% of biological therapies. Resumption of activities after the lockdown phase may take three to six months to normalize. Virtual clinics, implementation of IBD pathways and facilities seem to be the main factors to improve care in the future.

CONCLUSION

Italian IBD unit restructuring allowed quality standards of care during the COVID-19 pandemic to be maintained. A return to normal appears to be feasible and achievable relatively quickly. Some approaches, such as virtual clinics and identified IBD pathways, represent a valid starting point to improve IBD care in the post-COVID-19 era.

Response Assessed by Ultrasonography as Target of Biological Treatment for Crohn's Disease

BACKGROUND & AIMS

Mucosal healing, determined by ileocolonoscopy, is a goal for treatment of Crohn's disease (CD), but this is an invasive assessment procedure. We investigated whether response to tumor necrosis factor (TNF) antagonists, determined by small-intestine contrast ultrasonography, associates with long-term outcomes.

METHODS

We performed observational study of 80 patients with CD treated with anti-TNF agents for at least 1 year who underwent serial small intestine contrast ultrasonography (SICUS) at the University of Rome, in Italy. SICUS was used to evaluate disease site (based on bowel wall thickness), extent of lesions, and presence of complications. Inclusion criteria required pre-therapy SICUS with follow-up SICUS after 18 months. At second SICUS, patients were assigned to categories of complete or partial responder or non-responder. CD-related outcomes (corticosteroid need, hospitalization, and surgery) were assessed at 1 year from the second SICUS, using multivariate models, and were analyzed after long term follow up (5 years) using Kaplan-Meier survival analysis.

RESULTS

Based on SICUS, after a median of 18 months, 36 patients (51%) were complete responders, 30 were partial responders (34%), and 13 were non-responders (15%). At 1 year from the second SICUS, no patients with a complete response, based on ultrasonography, underwent surgery, in comparison to partial responders (P = .0003) or non-responders (P = .001). Complete responders used smaller amounts of corticosteroids than partial responders (P = .0001) or non-responders (P < .0001). Complete responders required fewer hospitalizations than non-responders (P = .001). Kaplan-Meier survival analysis of long-term follow up data demonstrated a lower cumulative probability of need for surgery, hospitalization, and need for steroids among SICUS-categorized complete responders (P < .0001, P = .003 and P = .0001 respectively) than SICUS-categorized non-responders.

CONCLUSIONS

In patients with CD, response to anti-TNF agents, determined by SICUS, is associated with better long-term outcomes than partial or no response. Ultrasonographic assessment therefore provides a relatively non-invasive method for monitoring response to treatment in patients with CD.

Smad7 in intestinal CD4+ T cells determines autoimmunity in a spontaneous model of multiple sclerosis

Environmental triggers acting at the intestinal barrier are thought to contribute to the initiation of autoimmune disorders. The transforming growth factor beta inhibitor Smad7 determines the phenotype of CD4+ T cells. We hypothesized that Smad7 in intestinal CD4+ T cells controls initiation of opticospinal encephalomyelitis (OSE), a murine model of multiple sclerosis (MS), depending on the presence of gut microbiota. Smad7 was overexpressed or deleted in OSE CD4+ T cells to determine the effect on clinical progression, T cell differentiation, and T cell migration from the intestine to the central nervous system (CNS). Smad7 overexpression worsened the clinical course of OSE and increased CNS inflammation and demyelination. It favored expansion of intestinal CD4+ T cells toward an inflammatory phenotype and migration of intestinal CD4+ T cells to the CNS. Intestinal biopsies from MS patients revealed decreased transforming growth factor beta signaling with a shift toward inflammatory T cell subtypes. Smad7 in intestinal T cells might represent a valuable therapeutic target for MS to achieve immunologic tolerance in the intestine and suppress CNS inflammation.

Nonalcoholic fatty liver disease in patients with inflammatory bowel disease: Beyond the natural history

BACKGROUND

Nonalcoholic fatty liver disease (NAFLD) is a frequently reported condition in patients with inflammatory bowel disease (IBD). Both intestinal inflammation and metabolic factors are believed to contribute to the pathogenesis of IBD-associated NAFLD.

AIM

To evaluate the prevalence of steatosis and liver fibrosis (LF) in a cohort of IBD patients and the identification of metabolic- and IBD-related risk factors for NAFLD and LF.

METHODS

IBD patients were consecutively enrolled from December 2016 to January 2018. Demographic, anthropometric and biochemical data were collected so as eating habits. Abdominal ultrasound and transient elastography were performed to evaluate the presence of NAFLD and LF respectively.

RESULTS

A total of 178 consecutive patients were enrolled and included in the analysis (95 Ulcerative colitis, 83 Crohn’s disease). NAFLD was detected by imaging in 72 (40.4%) patients. Comparison between patients with and without NAFLD showed no significant differences in terms of IBD severity, disease duration, location/extension, use of IBD-related medications (i.e., steroids, anti-TNFs, and immunomodulators) and surgery. NAFLD was significantly associated with the presence of metabolic syndrome [MetS; odds ratio (OR): 4.13, P = 0.001] and obesity defined by body mass index (OR: 9.21, P = 0.0002). IBD patients with NAFLD showed higher caloric intake and lipid consumption than those without NAFLD, regardless disease activity. At the multivariate analysis, male sex, advanced age and high lipid consumption were independent risk factors for the development of NAFLD. An increased liver stiffness was detected in 21 patients (16%) and the presence of MetS was the only relevant factor associated to LF (OR: 3.40, P = 0.01).

CONCLUSION

In this study, we demonstrate that risk factors for NAFLD and LF in the IBD population do not differ from those in the general population.

Tbet Expression in Regulatory T Cells Is Required to Initiate Th1-Mediated Colitis

In normal conditions gut homeostasis is maintained by the suppressive activity of regulatory T cells (Tregs), characterized by the expression of the transcription factor FoxP3. In human inflammatory bowel disease, which is believed to be the consequence of the loss of tolerance toward antigens normally contained in the gut lumen, Tregs have been found to be increased and functionally active, thus pointing against their possible role in the pathogenesis of this immune-mediated disease. Though, in inflammatory conditions, Tregs have been shown to upregulate the T helper (Th) type 1-related transcription factor Tbet and to express the pro-inflammatory cytokine IFNγ, thus suggesting that at a certain point of the inflammatory process, Tregs might contribute to inflammation rather than suppress it. Starting from the observation that Tregs isolated from the lamina propria of active but not inactive IBD patients or uninflamed controls express Tbet and IFNγ, we investigated the functional role of Th1-like Tregs in the dextran sulfate model of colitis. As observed in human IBD, Th1-like Tregs were upregulated in the inflamed lamina propria of treated mice and the expression of Tbet and IFNγ in Tregs preceded the accumulation of conventional Th1 cells. By using a Treg-specific Tbet conditional knockout, we demonstrated that Tbet expression in Tregs is required for the development of colitis. Indeed, Tbet knockout mice developed milder colitis and showed an impaired Th1 immune response. In these mice not only the Tbet deficient Tregs but also the Tbet proficient conventional T cells showed reduced IFNγ expression. However, Tbet deficiency did not affect the Tregs suppressive capacity in vitro and in vivo in the adoptive transfer model of colitis. In conclusion here we show that Tbet expression by Tregs sustains the early phase of the Th1-mediated inflammatory response in the gut.

The Resolution of Intestinal Inflammation: The Peace-Keeper's Perspective

The uncontrolled activation of the immune system toward antigens contained in the gut lumen in genetically predisposed subjects is believed to be the leading cause of inflammatory bowel disease (IBD). Two not mutually exclusive hypotheses can explain the pathogenic process leading to IBD. The first and mostly explored hypothesis states that the loss of tolerance toward gut microbiota antigens generates an aberrant inflammatory response that is perpetuated by continuous and unavoidable exposure to the triggering antigens. However, the discovery that the resolution of inflammation is not the mere consequence of clearing inflammatory triggers and diluting pro-inflammatory factors, but rather an active process in which molecular and cellular elements are involved, implies that a defect in the pro-resolving mechanisms might cause chronic inflammation in different immune-mediated diseases, including IBD. Here we review data on pro-resolving and counter-regulatory mechanisms involved in the resolution of inflammation, aiming to identify their possible involvement in the pathogenesis of IBD.

Heligmosomoides polygyrus bakeri Infection Decreases Smad7 Expression in Intestinal CD4+ T Cells, Which Allows TGF-β to Induce IL-10-Producing Regulatory T Cells That Block Colitis

Helminthic infections modulate host immunity and may protect their hosts from developing immunological diseases like inflammatory bowel disease. Induction of regulatory T cells (Tregs) may be an important part of this protective process. Heligmosomoides polygyrus bakeri infection also promotes the production of the regulatory cytokines TGF-β and IL-10 in the gut. In the intestines, TGF-β helps induce regulatory T cells. This study used Foxp3/IL-10 double reporter mice to investigate the effect of TGF-β on the differentiation of colon and mesenteric lymph node-derived murine Foxp3^- IL-10^- CD4⁺ T cells into their regulatory phenotypes. Foxp3^- IL-10^- CD4⁺ T cells from H. polygyrus bakeri-infected mice, as opposed to T cells from uninfected animals, cultured in vitro with TGF-β and anti-CD3/CD28 mAb differentiated into Foxp3⁺ and/or IL-10⁺ T cells. The IL-10-producing T cells nearly all displayed CD25. Smad7 is a natural inhibitor of TGF-β signaling. In contrast to gut T cells from uninfected mice, Foxp3^- IL10^- CD4⁺ T cells from H. polygyrus bakeri-infected mice displayed reduced Smad7 expression and responded to TGF-β with Smad2/3 phosphorylation. The TGF-β-induced Tregs that express IL-10 blocked colitis when transferred into the Rag/CD25^- CD4⁺ T cell transfer model of inflammatory bowel disease. TGF-β had a greatly diminished capacity to induce Tregs in H. polygyrus bakeri-infected transgenic mice with constitutively high T cell-specific Smad7 expression. Thus, infection with H. polygyrus bakeri causes down-modulation in Smad7 expression in intestinal CD4⁺ T cells, which allows the TGF-β produced in response to the infection to induce the Tregs that prevent colitis.

Alternative Splice Forms of CYLD Mediate Ubiquitination of SMAD7 to Prevent TGFB Signaling and Promote Colitis

BACKGROUND & AIMS

The CYLD lysine 63 deubiquitinase gene (CYLD) encodes tumor suppressor protein that is mutated in familial cylindromatosus, and variants have been associated with Crohn disease (CD). Splice forms of CYLD that lack exons 7 and 8 regulate transcription factors and functions of immune cells. We examined the expression of splice forms of CYLD in colon tissues from patients with CD and their effects in mice.

METHODS

We performed immunohistochemical analyses of colon tissues from patients with untreated CD and patients without inflammatory bowel diseases (controls). We obtained mice that expressed splice forms of CYLD (sCYLD mice) without or with SMAD7 (sCYLD/SMAD7 mice) from transgenes and CYLD-knockout mice (with or without transgenic expression of SMAD7) and performed endoscopic analyses. Colitis was induced in Rag1^-/- mice by transfer of CD4⁺ CD62L⁺ T cells from C57/Bl6 or transgenic mice. T cells were isolated from mice and analyzed by flow cytometry and quantitative real-time polymerase chain reaction and intestinal tissues were analyzed by histology and immunohistochemistry. CYLD forms were expressed in mouse embryonic fibroblasts, primary T cells, and HEK293T cells, which were analyzed by immunoblot, mobility shift, and immunoprecipitation assays.

RESULTS

The colonic lamina propria from patients with CD was infiltrated by T cells and had higher levels of sCYLD (but not full-length CYLD) and SMAD7 than tissues from controls. Incubation of mouse embryonic fibroblasts and T cells with transforming growth factor β increased their production of sCYLD and decreased full-length CYLD. Transgenic expression of sCYLD and SMAD7 in T cells prevented the differentiation of regulatory T cells and T-helper type 17 cells and increased the differentiation of T-helper type 1 cells. The same effects were observed in colon tissues from sCYLD/SMAD7 mice but not in those from CYLD-knockout SMAD7 mice. The sCYLD mice had significant increases in the numbers of T-helper type 1 cells and CD44^high CD62L^low memory-effector CD4⁺ T cells in the spleen and mesenteric lymph nodes compared with wild-type mice; sCYLD/SMAD7 mice had even larger increases. The sCYLD/SMAD7 mice spontaneously developed severe colitis, with infiltration of the colon by dendritic cells, neutrophils, macrophages, and CD4⁺ T cells and increased levels of Ifng, Il6, Il12a, Il23a, and Tnf mRNAs. Co-transfer of regulatory T cells from wild-type, but not from sCYLD/SMAD7, mice prevented the induction of colitis in Rag1^-/- mice by CD4⁺ T cells. We found increased levels of poly-ubiquitinated SMAD7 in sCYLD CD4⁺ T cells. CYLD formed a nuclear complex with SMAD3, whereas sCYLD recruited SMAD7 to the nucleus, which inhibited the expression of genes regulated by SMAD3 and SMAD4. We found that sCYLD mediated lysine 63-linked ubiquitination of SMAD7. The sCYLD-SMAD7 complex inhibited transforming growth factor β signaling in CD4⁺ T cells.

CONCLUSIONS

Levels of the spliced form of CYLD are increased in colon tissues from patients with CD. sCYLD mediates ubiquitination and nuclear translocation of SMAD7 and thereby decreases transforming growth factor β signaling in T cells. This prevents immune regulatory mechanisms and leads to colitis in mice.

RORγt-Expressing Tregs Drive the Growth of Colitis-Associated Colorectal Cancer by Controlling IL6 in Dendritic Cells

Chronic inflammation drives colitis-associated colorectal cancer (CAC) in inflammatory bowel disease (IBD). FoxP3⁺ regulatory T cells (Treg) coexpressing the Th17-related transcription factor RORγt accumulate in the lamina propria of IBD patients, where they are thought to represent an intermediate stage of development toward a Th17 proinflammatory phenotype. However, the role of these cells in CAC is unknown. RORγt⁺FoxP3⁺ cells were investigated in human samples of CAC, and their phenotypic stability and function were investigated in an azoxymethane/dextran sulfate sodium model of CAC using Treg fate-mapping reporter and Treg-specific RORγt conditional knockout mice. Tumor development and the intratumoral inflammatory milieu were characterized in these mice. The functional role of CTLA-4 expressed by Tregs and FoxO3 in dendritic cells (DC) was studied in vitro and in vivo by siRNA-silencing experiments. RORγt expression identified a phenotypically stable population of tumor-infiltrating Tregs in humans and mice. Conditional RORγt knockout mice showed reduced tumor incidence, and dysplastic cells exhibited low Ki67 expression and STAT3 activation. Tumor-infiltrating DCs produced less IL6, a cytokine that triggers STAT3-dependent proliferative signals in neoplastic cells. RORγt-deficient Tregs isolated from tumors overexpressed CTLA-4 and induced DCs to have elevated expression of the transcription factor FoxO3, thus reducing IL6 expression. Finally, in vivo silencing of FoxO3 obtained by siRNA microinjection in the tumors of RORγt-deficient mice restored IL6 expression and tumor growth. These data demonstrate that RORγt expressed by tumor-infiltrating Tregs sustains tumor growth by leaving IL6 expression in DCs unchecked. Cancer Immunol Res; 6(9); 1082-92. ©2018 AACR.

Interleukin-21 sustains inflammatory signals that contribute to sporadic colon tumorigenesis

Interleukin (IL)-21 triggers inflammatory signals that contribute to the growth of neoplastic cells in mouse models of colitis-associated colorectal cancer (CRC). Because most CRCs are sporadic and arise in the absence of overt inflammation we have investigated the role of IL-21 in these tumors in mouse and man. IL-21 was highly expressed in human sporadic CRC and produced mostly by IFN-γ-expressing T-bet/RORγt double-positive CD3+CD8− cells. Stimulation of human CRC cell lines with IL-21 did not directly activate the oncogenic transcription factors STAT3 and NF-kB and did not affect CRC cell proliferation and survival. In contrast, IL-21 modulated the production of protumorigenic factors by human tumor infiltrating T cells. IL-21 was upregulated in the neoplastic areas, as compared with non-tumor mucosa, of Apc^min/+ mice, and genetic ablation of IL-21 in such mice resulted in a marked decrease of both tumor incidence and size. IL-21 deficiency was associated with reduced STAT3/NF-kB activation in both immune cells and neoplastic cells, diminished synthesis of protumorigenic cytokines (that is, IL-17A, IL-22, TNF-α and IL-6), downregulation of COX-2/PGE2 pathway and decreased angiogenesis in the lesions of Apc^min/+ mice. Altogether, data suggest that IL-21 promotes a protumorigenic inflammatory circuit that ultimately sustains the development of sporadic CRC.

Th17-type cytokines, IL-6 and TNF-α synergistically activate STAT3 and NF-kB to promote colorectal cancer cell growth

Colorectal cancers (CRCs) often show a dense infiltrate of cytokine-producing immune/inflammatory cells. The exact contribution of each immune cell subset and cytokine in the activation of the intracellular pathways sustaining CRC cell growth is not understood. Herein, we isolate tumor-infiltrating leukocytes (TILs) and lamina propria mononuclear cells (LPMCs) from the tumor area and the macroscopically unaffected, adjacent, colonic mucosa of patients who underwent resection for sporadic CRC and show that the culture supernatants of TILs, but not of LPMCs, potently enhance the growth of human CRC cell lines through the activation of the oncogenic transcription factors signal transducer and activator of transcription 3 (STAT3) and nuclear factor-kappa B (NF-kB). Characterization of immune cell complexity of TILs and LPMCs reveals no differences in the percentages of T cells, natural killer T cells, natural killer (NK) cells, macrophages and B cells. However, T cells from TILs show a functional switch compared with those from LPMCs to produce large amounts of T helper type 17 (Th17)-related cytokines (that is, interleukin-17A (IL-17A), IL-17F, IL-21 and IL-22), tumor necrosis factor-α (TNF-α) and IL-6. Individual neutralization of IL-17A, IL-17F, IL-21, IL-22, TNF-α or IL-6 does not change TIL-derived supernatant-driven STAT3 and NF-kB activation, as well as their proproliferative effect in CRC cells. In contrast, simultaneous neutralization of both IL-17A and TNF-α, which abrogates NF-kB signaling, and IL-22 and IL-6, which abrogates STAT3 signaling, reduces the mitogenic effect of supernatants in CRC cells. IL-17A, IL-21, IL-22, TNF-α and IL-6 are also produced in excess in the early colonic lesions in a mouse model of sporadic CRC, associated with enhanced STAT3/NF-kB activation. Mice therapeutically given BP-1-102, an orally bioavailable compound targeting STAT3/NF-kB activation and cross-talk, exhibit reduced colon tumorigenesis and diminished expression of STAT3/NF-kB-activating cytokines in the neoplastic areas. These data suggest that strategies aimed at the cotargeting of STAT3/NF-kB activation and interaction between them might represent an attractive and novel approach to combat CRC.

Mongersen, an oral SMAD7 antisense oligonucleotide, and Crohn's disease

BACKGROUND

Crohn's disease-related inflammation is characterized by reduced activity of the immunosuppressive cytokine transforming growth factor β1 (TGF-β1) due to high levels of SMAD7, an inhibitor of TGF-β1 signaling. Preclinical studies and a phase 1 study have shown that an oral SMAD7 antisense oligonucleotide, mongersen, targets ileal and colonic SMAD7.

METHODS

In a double-blind, placebo-controlled, phase 2 trial, we evaluated the efficacy of mongersen for the treatment of persons with active Crohn's disease. Patients were randomly assigned to receive 10, 40, or 160 mg of mongersen or placebo per day for 2 weeks. The primary outcomes were clinical remission at day 15, defined as a Crohn's Disease Activity Index (CDAI) score of less than 150, with maintenance of remission for at least 2 weeks, and the safety of mongersen treatment. A secondary outcome was clinical response (defined as a reduction of 100 points or more in the CDAI score) at day 28.

RESULTS

The proportions of patients who reached the primary end point were 55% and 65% for the 40-mg and 160-mg mongersen groups, respectively, as compared with 10% for the placebo group (P<0.001). There was no significant difference in the percentage of participants reaching clinical remission between the 10-mg group (12%) and the placebo group. The rate of clinical response was significantly greater among patients receiving 10 mg (37%), 40 mg (58%), or 160 mg (72%) of mongersen than among those receiving placebo (17%) (P=0.04, P<0.001, and P<0.001, respectively). Most adverse events were related to complications and symptoms of Crohn's disease.

CONCLUSIONS

We found that study participants with Crohn's disease who received mongersen had significantly higher rates of remission and clinical response than those who received placebo. (Funded by Giuliani; EudraCT number, 2011-002640-27.).

A functional role for Smad7 in sustaining colon cancer cell growth and survival

Initially identified as an inhibitor of transforming growth factor (TGF)-β mainly owing to its ability to bind TGF-β receptor type I and abrogate TGF-β-driven signaling, Smad7 can interact with additional intracellular proteins and regulate TGF-β-independent pathways, thus having a key role in the control of neoplastic processes in various organs. Genome-wide association studies have shown that common alleles of Smad7 influence the risk of colorectal cancer (CRC), even though the contribution of Smad7 in colon carcinogenesis is not fully understood. In this study, we assessed the expression and role of Smad7 in human and mouse models of sporadic CRC. We document a significant increase of Smad7 in human CRC relative to the surrounding nontumor tissues and show that silencing of Smad7 inhibits the growth of CRC cell lines both in vitro and in vivo after transplantation into immunodeficient mice. Knockdown of Smad7 results in enhanced phosphorylation of the cyclin-dependent kinase (CDK)2, accumulation of CRC cells in S phase and enhanced cell death. Smad7-deficient CRC cells have lower levels of CDC25A, a phosphatase that dephosphorylates CDK2, and hyperphosphorylated eukaryotic initiation factor 2 (eIF2)α, a negative regulator of CDC25 protein translation. Consistently, knockdown of Smad7 associates with inactivation of eIF2α, lower CDC25A expression and diminished fraction of proliferating cells in human CRC explants, and reduces the number of intestinal tumors in Apc^min/+ mice. Altogether, these data support a role for Smad7 in sustaining colon tumorigenesis.

Smad7 induces plasticity in tumor-infiltrating Th17 cells and enables TNF-alpha-mediated killing of colorectal cancer cells

Transforming growth factor-beta (TGF-β) is deeply involved in colorectal cancer development and the disruption of the TGF-β signaling in dysplastic cells is required for tumor to grow. Nevertheless, tumor cells express TGF-β to escape the immune surveillance mediated by T cells. T-cell expression of Smad7, an intracellular inhibitor of the TGF-β signaling, protects against colitis-associated colorectal cancer. However, whether Smad7 in T cells might influence colorectal cancer growth independently of chronic inflammation and which T-cell subset is involved in this process is unknown. To address this issue, T-cell-specific Smad7 transgenic mice and wild-type (WT) littermates were subcutaneously transplanted with syngenic MC38 colon carcinoma cells. Smad7Tg mice were resistant to tumor development compared with WT mice and protection was dependent on CD4(+) T cells. Smad7 expression in T cells increased the number of tumor-infiltrating Tbet/ROR-γ-t double-positive CD4 T cells characterized by the expression of tumor necrosis factor-alpha (TNF-α) and interferon-gamma but lower IL17A. The low expression of IL17A caused by the Smad7 expression in tumor-infiltrating CD4(+) T cells enabled the TNF-α-mediated killing of cancer cells both in vitro and in vivo, thus indicating that the Smad7-mediated plastic effect on T-cell phenotype induces protection against colorectal cancer.

Angiogenesis, immune system and growth factors: new targets in colorectal cancer therapy

Colorectal cancer is the second most common malignant human neoplasia. Over recent years, many efforts have been performed in order to develop and improve therapeutic protocols, and many advances have been accomplished in both the field of adjuvant and palliative therapy. Most of the chemotherapic agents currently used in the clinical setting are the products of decades of research aimed at inhibiting the uncontrolled growth of dysplastic cells. However, new frontiers in this field have recently been opened, with the identification of key molecules involved in physiologic mechanisms that are of fundamental importance for cancer development and progression. Tumor-induced angiogenesis, the cancer-immune system crosstalk and the effect of growth factors on dysplastic cells represent new fields of investigation for anticancer therapy.

Phase I clinical trial of Smad7 knockdown using antisense oligonucleotide in patients with active Crohn's disease

In the gut of patients with Crohn's disease (CD), high Smad7 blocks the immune-suppressive activity of transforming growth factor (TGF)-β1, thereby contributing to amplify inflammatory signals. In vivo in mice, knockdown of Smad7 with a Smad7 antisense oligonucleotide (GED0301) attenuates experimental colitis. Here, we provide results of a phase 1 clinical, open-label, dose-escalation study of GED0301 in patients with active, steroid-dependent/resistant CD, aimed at assessing the safety and tolerability of the drug. Patients were allocated to three treatment groups receiving oral GED0301 once daily for 7 days at doses of 40, 80, or 160 mg. A total of 15 patients were enrolled. No serious adverse event was registered. GED0301 was well tolerated and no patient dropped out during the study. Twenty-five adverse events were documented in 11 patients, the majority of whom were judged to be of mild intensity and unrelated to treatment. GED0301 treatment reduced the percentage of inflammatory cytokine-expressing CCR9-positive T cells in the blood. The study shows for the first time that GED0301 is safe and well tolerated in patients with active CD.

Smad7 expression in T cells prevents colitis-associated cancer

Patients with inflammatory bowel disease (IBD) have an increased risk of developing colorectal cancer due to chronic inflammation. In IBD, chronic inflammation relies upon a TGFβ signaling blockade, but its precise mechanistic relationship to colitis-associated colorectal cancer (CAC) remains unclear. In this study, we investigated the role of the TGFβ signaling inhibitor Smad7 in CAC pathogenesis. In human colonic specimens, Smad7 was downregulated in CD4(+) T cells located in the lamina propria of patients with complicated IBD compared with uncomplicated IBD. Therefore, we assessed CAC susceptibility in a transgenic mouse model where Smad7 was overexpressed specifically in T cells. In this model, Smad7 overexpression increased colitis severity, but the mice nevertheless developed fewer tumors than nontransgenic mice. Protection was associated with increased expression of IFNγ and increased accumulation of cytotoxic CD8(+) and natural killer T cells in the tumors and peritumoral areas. Moreover, genetic deficiency in IFNγ abolished the Smad7-dependent protection against CAC. Taken together, our findings defined a novel and unexpected role for Smad7 in promoting a heightened inflammatory response that protects against CAC.

Common immunologic mechanisms in inflammatory bowel disease and spondylarthropathies

Spondyloarthropathies (SpA) are commonly observed extra-intestinal manifestations of both Crohn’s disease (CD) and ulcerative colitis (UC), the two major forms of inflammatory bowel diseases (IBD). However, the immunological link between these two clinical entities is still poorly understood. Several lines of evidence indicate that SpA may originate from the relocation to the joints of the immune process primarily induced in the gut. The transfer of the intestinal inflammatory process into the joints implicates that immune cells activated in the gut-draining lymph nodes can localize, at a certain point of the intestinal disease, either into the gut or into the joints. This is indicated by the overlapping expression of adhesion molecules observed on the surface of intestinal and synovial endothelial cells during inflammation. Moreover bacterial antigens and HLA-B27 expression may be implicated in the reactivation of T cells at the articular level. Finally, accumulating evidence indicates that a T helper 17 cell-mediated immune response may contribute to IBD and IBD-related SpA with a crucial role played by tumor necrosis factor-α in CD and to a lesser extent in UC.

Smad7 controls resistance of colitogenic T cells to regulatory T cell-mediated suppression

BACKGROUND & AIMS

Foxp3-expressing regulatory T cells (Tregs) play a key role in the maintenance of the gut immune homeostasis, and an intact transforming growth factor (TGF)-beta signaling is required for their function. In inflammatory bowel disease (IBD), the TGF-beta signaling is impaired because of high expression of the inhibitory molecule Smad7. Although no intrinsic defects in Tregs function have been shown in IBD, it is still unknown whether colitogenic T cells are susceptible to Treg-mediated suppression. In this study, we have investigated whether IBD mucosal CD4+ T cells are resistant to Tregs and whether Smad7 is involved in this process.

METHODS

IBD lamina propria mononuclear cells (LPMC) were cultured with or without Tregs, and proliferation was assessed by flow cytometry. Proliferation of IBD LPMC was also evaluated after Smad7 antisense oligonuclotide treatment. Treg-mediated suppression of T-cell proliferation and proinflammatory cytokine expression was investigated in murine Smad7 transgenic cells. In vivo, the Smad7-dependent resistance of colitogenic naïve T cells to Tregs was studied in the adoptive transfer model of colitis.

RESULTS

IBD LPMC were resistant to Treg-mediated suppression, and this phenomenon was reverted by Smad7 antisense treatment. Consistently, CD4+ T cells isolated from Smad7 transgenic mice showed high proliferation, produced considerable amount of inflammatory cytokines following activation, and induced a severe colitis when transferred in immunodeficient RAG1 knockout mice even in the presence of wild-type Tregs.

CONCLUSIONS

Smad7 makes CD4+ T cells resistant to Tregs-mediated suppression thus fine-tuning their proinflammatory potential.

Cytokines: from gut inflammation to colorectal cancer

Colorectal cancer represents a life-threatening complication of inflammatory bowel diseases. Statistics indicate that the risk to develop colorectal cancer is higher in patients affected by ulcerative colitis and to a lesser extent by Crohn's disease and that such a risk is directly proportional to the number of years of active disease. These observations suggest that chronic inflammation may substantially contribute to cancer development. However the molecular mechanisms underlying this process have been only recently started to be clarified. Indeed from the initial concept that the release of free radicals during inflammation might induce the accumulation of genetic mutations thus leading to the onset of dysplastic cells, it is now becoming clear that the large amount of cytokines and growth factors released during inflammation by immune and non immune cells may influence the carcinogenesis process. IL-6 and IL-23, cytokines which play key roles in the induction and maintenance of gut inflammation during IBDs, have been recently shown to influence the development and growth of colitis associated colorectal cancer. Moreover, the activation of the nuclear factor kappa B (NF kappa B), a transcription factor activated by several cytokines released during inflammation and responsible for many of their proinflammatory effects, have been shown to promote the growth of the colon tumors in experimental models.

Regulation of gut inflammation and th17 cell response by interleukin-21

BACKGROUND & AIMS

Interleukin (IL)-21, a T-cell-derived cytokine, is overproduced in inflammatory bowel diseases (IBD), but its role in the pathogenesis of gut inflammation remains unknown. We here examined whether IL-21 is necessary for the initiation and progress of experimental colitis and whether it regulates specific pathways of inflammation.

METHODS

Both dextran sulfate sodium colitis and trinitrobenzene sulfonic acid-relapsing colitis were induced in wild-type and IL-21-deficient mice. CD4(+)CD25(-) T cells from wild-type and IL-21-deficient mice were differentiated in T helper cell (Th)17-polarizing conditions, with or without IL-21 or an antagonistic IL-21R/Fc. We also examined whether blockade of IL-21 by anti-IL-21 antibody reduced IL-17 in cultures of IBD lamina propria CD3(+) T lymphocytes. Cytokines were evaluated by real-time polymerase chain reaction and/or enzyme-linked immunosorbent assay.

RESULTS

High IL-21 was seen in wild-type mice with dextran sulfate sodium- and trinitrobenzene sulfonic acid-relapsing colitis. IL-21-deficient mice were largely protected against both colitides and were unable to up-regulate Th17-associated molecules during gut inflammation, thus suggesting a role for IL-21 in controlling Th17 cell responses. Indeed, naïve T cells from IL-21-deficient mice failed to differentiate into Th17 cells. Treatment of developing Th17 cells from wild-type mice with IL-21R/Fc reduced IL-17 production. Moreover, in the presence of transforming growth factor-beta1, exogenous IL-21 substituted for IL-6 in driving IL-17 induction. Neutralization of IL-21 reduced IL-17 secretion by IBD lamina propria lymphocytes.

CONCLUSIONS

These results indicate that IL-21 is a critical regulator of inflammation and Th17 cell responses in the gut.

IL-21 regulates experimental colitis by modulating the balance between Treg and Th17 cells

Regulatory T (T(reg)) cells play a key role in the maintenance of the immune system homeostasis. T(reg) cells can be generated in the periphery under control of TGF-beta, a cytokine involved in the negative control of the immune system. However, TGF-beta cooperates with IL-6 in the generation of Th17 cells, a novel class of effector cells involved in numerous inflammatory diseases, including colitis. Therefore, TGF-beta emerges as a mediator of both anti-inflammatory and pro-inflammatory processes, depending on the local cytokine milieu. Here we demonstrate that IL-21, a type-1 cytokine produced by T cells and involved in the pathogenesis of immune-mediated diseases, prevents the TGF-beta-dependent expression of FoxP3, the master regulator of T(reg) cell commitment, and the induction of suppressive capacity in naive CD4(+) T cells, while promoting the differentiation of Th17 cells. In vivo, CD4(+) naive T cells activated in the presence of TGF-beta and IL-21 failed to suppress colitis while inducing an inflammatory response characterized by high levels of IL-17 and RORgammat, the transcription factor expressed by Th17 cells. Therefore, IL-21 emerges as a key modulator of TGF-beta signaling, leading to the reciprocal differentiation of T(reg) and Th17 cells.

New players in the cytokine orchestra of inflammatory bowel disease

In both Crohn's disease (CD) and ulcerative colitis, the pathologic process is almost certainly driven by an aberrant local immune response directed against normal components of the bacterial microflora. Mucosal immune cells interact with nonimmune cells such as epithelial cells and fibroblasts to promote tissue damage; cytokines are essential mediators of this cross talk. Accumulating evidence now suggests that interleukin-21 (IL-21), the newest member of the common gamma-chain-dependent cytokine family, is a key component of the inflammatory cascade. IL-21 is highly produced by activated CD4+ lymphocytes in the inflamed gut of patients with CD, where it contributes to sustaining the ongoing Th1 inflammation. IL-21 also increases the secretion of extracellular matrix-degrading enzymes by fibroblasts and of MIP-3alpha by epithelial cells. Two other cytokines, IL-27 and IL-32, may also be important in the inflammatory pathways that operate in IBD.

Cutting edge: trans-signaling via the soluble IL-6R abrogates the induction of FoxP3 in naive CD4+CD25 T cells

Chronic inflammatory diseases may develop when regulatory T cells (Tregs) fail to control the balance between tolerance and immunity. Alternatively, activated immune cells might prevent the induction or activation of Tregs in such diseases. In this study, we demonstrate that trans-signaling into T cells via the soluble IL-6 receptor completely abrogates the de novo induction of adaptive Tregs. Mechanistically, IL-6 trans-signaling augmented the expression of the TGF-beta signaling inhibitor SMAD7. Consequently, SMAD7 overexpression in T cells using newly created transgenic mice rendered CD4(+)CD25(-) T cells resistant to the induction of FoxP3. Finally, IL-6 trans-signaling inhibited Treg-mediated suppression in a murine model of colitis. In summary, IL-6 trans-signaling into T cells emerges as a key pathway for blockade of the development of adaptive Tregs and thus may play a pivotal role in shifting the balance between effector and regulatory T cell numbers in chronic inflammatory and autoimmune diseases.

IL-27 controls the development of inducible regulatory T cells and Th17 cells via differential effects on STAT1

IL-27 is an IL-12-related cytokine frequently present at sites of inflammation that can promote both anti- and pro-inflammatory immune responses. Here, we have analyzed the mechanisms how IL-27 may drive such divergent immune responses. While IL-27 suppressed the development of proinflammatory Th17 cells, a novel role for this cytokine in inhibiting the development of anti-inflammatory, inducible regulatory T cells (iTreg) was identified. In fact, IL-27 suppressed the development of adaptive, TGF-beta-induced Forkhead box transcription factor p3-positive (Foxp3(+)) Treg. Whereas the blockade of Th17 development was dependent on the transcription factor STAT1, the suppression of iTreg development was STAT1 independent, suggesting that IL-27 utilizes different signaling pathways to shape T cell-driven immune responses. Our data thus demonstrate that IL-27 controls the development of Th17 and iTreg cells via differential effects on STAT1.

In vitro generation of CD4+CD25+ regulatory cells from murine naive T cells

CD4+ CD25+ regulatory T cells (Tregs) are crucial for the maintenance of immunological tolerance. Recent data indicate that Tregs not only develop in the thymus during ontogeny but can also differentiate from naive T cells in the periphery. The following protocol describes a method by which Tregs are generated in vitro by stimulation of naive T cells in the presence of transforming growth factor beta (Ti-Tregs). In vitro-induced regulatory T cells express markers of conventional Treg such as CD25 and the genetic program committing transcription factor FoxP3. Functionally the in vitro-generated Ti-Tregs suppress T-cell activation and proliferation while in vivo these cells have been proven to control inflammation in different animal models, suggesting a potential use of these cells for immunotherapy. The protocol can be completed within 5 days.

High resolution colonoscopy in live mice

Endoscopy in humans is a powerful method for physicians to examine the gut for inflammatory or neoplastic changes. In medical and immunological research, animal models of intestinal diseases are established key tools to investigate the mucosal immune system, colitis and cancer development in the gut. Moreover, such models represent valid systems for testing of novel drugs. In the past, mice had to be killed in order to analyze colitis activity and tumor development. The following protocol describes a method to perform high resolution endoscopic monitoring of live mice. Mice developing colitis or colonic tumors are anesthetized and examined with a miniendoscope. The endoscope is introduced via the anus and the colon is carefully insufflated with an air pump. Endoscopic pictures obtained are of high quality and allow the monitoring and grading of tumors and inflammation. In addition, colonic biopsies can be taken. This protocol can be completed within 1 h.

Control of matrix metalloproteinase production in human intestinal fibroblasts by interleukin 21

BACKGROUND

T cell-mediated immunity plays a central part in the pathogenesis of tissue damage in inflammatory bowel disease (IBD). The mechanism by which T cells mediate tissue damage during IBD remains unclear, but evidence indicates that T cell-derived cytokines stimulate fibroblasts to synthesise matrix metalloproteinases (MMPs), which then mediate mucosal degradation. We have previously shown that, in IBD, there is high production of interleukin (IL) 21, a T cell-derived cytokine, which enhances Th1 activity.

AIM

To investigate whether IL21 controls MMP production by intestinal fibroblasts.

METHODS

IL21 receptor (IL21R) was evaluated in intestinal fibroblasts by reverse transcriptase-polymerase chain reaction (RT-PCR) and western blotting. Fibroblasts were stimulated with IL21 and MMPs were evaluated by RT-PCR and western blotting. The effect of a neutralising IL21R fusion protein (IL21R/Fc) on the induction of MMPs in fibroblasts stimulated with IBD lamina propria mononuclear cell (LPMC) supernatants was also evaluated.

RESULTS

Intestinal fibroblasts constitutively express both IL21R and the common gamma chain receptor, which are necessary for IL21-driven signalling. IL21 enhances fibroblast production of MMP-1, MMP-2, MMP-3 and MMP-9, but not tissue inhibitors of MMP-1 and MMP-2. Moreover, IL21 synergises with tumour necrosis factor alpha to increase synthesis of MMP synthesis. IL21 enhances MMP secretion without affecting gene transcription and protein synthesis. IBD LPMC supernatants stimulate MMP secretion by intestinal fibroblasts, and this effect is partly inhibited by IL21R/Fc.

CONCLUSIONS

These results suggest that fibroblasts are a potential target of IL21 in the gut and that IL21 controls MMP secretion by fibroblasts.

Drug insight: novel small molecules and drugs for immunosuppression

Gastrointestinal diseases can result from the inadequate or excessive response of the immune system to self or innocuous antigens. Moreover, the physiologic activation of the immune system against non-self antigens is a major clinical problem in liver organ transplantation. At present, many drugs are available that suppress the activation of the immune system, although most of the currently used immunosuppressive drugs lack specificity in terms of their molecular targets and, therefore, have the potential to generate numerous side effects. The advances that have been made in understanding the molecular events that underlie the activation of the immune system have led to the development of a new generation of 'small molecules' that are endowed with immunosuppressive properties and can serve as immunomodulatory agents. Among these new small molecules, inhibitors of Janus kinase 3, p21-Rac1 and p38 mitogen-activated protein kinase represent the most innovative approach to immunosuppression, and could be a promising alternative to current immunosuppressive therapies. Here, we report on the progress that has been made in the development of small molecules in the field of gastroenterology.

Cutting edge: IL-23 cross-regulates IL-12 production in T cell-dependent experimental colitis

Although IL-12 and IL-23 share the common p40 subunit, IL-23, rather than IL-12, seems to drive the pathogenesis of experimental autoimmune encephalomyelitis and arthritis, because IL-23/p19 knockout mice are protected from disease. In contrast, we describe in this study that newly created LacZ knockin mice deficient for IL-23 p19 were highly susceptible for the development of experimental T cell-mediated TNBS colitis and showed even more severe colitis than wild-type mice by endoscopic and histologic criteria. Subsequent studies revealed that dendritic cells from p19-deficient mice produce elevated levels of IL-12, and that IL-23 down-regulates IL-12 expression upon TLR ligation. Finally, in vivo blockade of IL-12 p40 in IL-23-deficient mice rescued mice from lethal colitis. Taken together, our data identify cross-regulation of IL-12 expression by IL-23 as novel key regulatory pathway during initiation of T cell dependent colitis.

Transforming growth factor beta induced FoxP3+ regulatory T cells suppress Th1 mediated experimental colitis

BACKGROUND AND AIMS

The imbalance between effector and regulatory T cells plays a central role in the pathogenesis of inflammatory bowel diseases. In addition to the thymus, CD4+CD25+ regulatory T cells can be induced in the periphery from a population of CD25- T cells by treatment with transforming growth factor beta (TGF-beta). Here, we analysed the in vivo function of TGF-beta induced regulatory T (Ti-Treg) cells in experimental colitis.

METHODS

Ti-Treg cells were generated in cell culture in the presence or absence of TGF-beta and tested for their regulatory potential in experimental colitis using the CD4+CD62L+ T cell transfer model.

RESULTS

Ti-Treg cells significantly suppressed Th1 mediated colitis on CD4+CD62L+ T cell transfer in vivo, as shown by high resolution endoscopy, histology, immunohistochemistry, and cytokine analysis. Further analysis of in vivo and in vitro expanded Ti-Treg cells showed that exogenous interleukin 2 (IL-2) was crucial for survival and expansion of these cells.

CONCLUSION

Our data suggest that regulatory Ti-Treg cells expand by TGF-beta and exogenous IL-2 derived from effector T cells at the site of inflammation. In addition to Tr1 and thymic CD4+CD25+ T cells, peripheral Ti-Treg cells emerge as a class of regulatory T cells with therapeutic potential in T cell mediated chronic intestinal inflammation.

TGF-beta as a T cell regulator in colitis and colon cancer

TGF-beta is a pleiotropic cytokine with powerful immunosuppressive functions. Mice deficient for TGF-beta1 show a dramatic phenotype with severe multiorgan inflammation and die shortly after birth. Recent investigations have highlighted the role of TGF-beta in suppression of T cell mediated autoimmune inflammation and anti-tumor immunity. In addition to its direct anti-inflammatory effects on T cells, TGF-beta has been implicated as central regulator of regulatory T cells. TGF-beta not only mediates the suppression of effector T cells by Tregs, recent evidence also reveals a role for TGF-beta along with TCR stimulation in the peripheral induction of regulatory T cells from naïve CD4+CD25- cells.

In vivo imaging of colitis and colon cancer development in mice using high resolution chromoendoscopy

BACKGROUND

Mouse models of colitis and cancer are indispensable for our understanding of the pathogenesis of these diseases. In the past, mice had to be sacrificed in order to analyse colitis activity and tumour development. We have developed a safe method for high resolution endoscopic monitoring of living mice.

METHODS

Mice developing colitis or colonic tumours were anaesthetised using avertine and repeatedly examined by endoscopy. A novel miniendoscope (1.9 mm outer diameter), denoted Coloview, was introduced via the anus and the colon was carefully insufflated with an air pump before analysis of the colonic mucosa. An extra working channel allowed the introduction of biopsy forceps or injection needles as well as surface staining with methylene blue in order to visualise the surface of the crypts and the pit pattern architecture.

RESULTS

Endoscopic pictures obtained were of high quality and allowed monitoring and grading of disease. Scoring of colitis activity as well as tumour size and growth was possible. In addition, pit pattern analysis using chromoendoscopy permitted discrimination between inflammatory and neoplastic changes. Biopsies yielded enough tissue for molecular and histopathological analyses.

CONCLUSIONS

In summary, chromoendoscopy in mice allows monitoring of the development of colitis and colon cancer with high resolution. Manipulations such as local injection of reagents or taking biopsies can be performed easily.

EBV-induced gene 3 transcription is induced by TLR signaling in primary dendritic cells via NF-kappa B activation

The EBV-induced gene 3 (EBI3) is expressed in dendritic cells (DCs) and part of the cytokine IL-27 that controls Th cell development. However, its regulated expression in DCs is poorly understood. In the present study we demonstrate that EBI3 is expressed in splenic CD8(-), CD8(+), and plasmacytoid DC subsets and is induced upon TLR signaling. Cloning and functional analysis of the EBI3 promoter using in vivo footprinting and mutagenesis showed that stimulation via TLR2, TLR4, and TLR9 transactivated the promoter in primary DCs via NF-kappaB and Ets binding sites at -90 and -73 bp upstream of the transcriptional start site, respectively. Furthermore, we observed that NF-kappaB p50/p65 and PU.1 were sufficient to transactivate the EBI3 promoter in EBI3-deficient 293 cells. Finally, induced EBI3 gene expression in DCs was reduced or abrogated in TLR-2/TLR4, TLR9, and MyD88 knockout mice, whereas both basal and inducible EBI3 mRNA levels in DCs were strongly suppressed in NF-kappaB p50-deficient mice. In summary, these data suggest that EBI3 expression in DCs is transcriptionally regulated by TLR signaling via MyD88 and NF-kappaB. Thus, EBI3 gene transcription in DCs is induced rapidly by TLR signaling during innate immune responses preceding cytokine driven Th cell development.

IL-6 signaling promotes tumor growth in colorectal cancer

Recent investigations support an important role for TGF-beta in the development of colorectal cancer. However, the molecular consequences of TGF-beta signaling in the colon remains incompletely understood. In a recent study in Immunity, we analyzed the role of TGF-beta in a murine model of colon cancer. Using transgenic mice overexpressing TGF-beta or a dominant negative TGF-beta receptor II under control of the CD2 minigene, we show that TGF-beta signaling in tumor infiltrating T lymphocytes regulates the growth of dysplastic colon epithelial cells, as determined by histology and a novel system for high resolution chromoendoscopy in vivo. At the molecular level, TGF-beta signaling in T cells regulated STAT-3 activation in tumor cells via IL-6. IL-6 signaling required tumor cell derived soluble IL-6R rather than membrane bound IL-6R and suppression of such TGF-beta-dependent IL-6 trans-signaling prevented tumor progression in vivo. Similar to these observations in mice, here we show that human colon cancer tissue expressed only low amounts of membrane bound IL-6R. In contrast, expression and activity of the matrix metalloproteinase TACE were increased. In summary, our data provide novel insights into the role of TGF-beta signaling in colorectal cancer and suggest novel therapeutic approaches for colorectal cancer based on an inhibition of TGF-beta-dependent IL-6 trans-signaling.

IL-6 signaling promotes tumor growth in colorectal cancer

Recent investigations support an important role for TGF-beta in the development of colorectal cancer. However, the molecular consequences of TGF-beta signaling in the colon remains incompletely understood. In a recent study in Immunity, we analyzed the role of TGF-beta in a murine model of colon cancer. Using transgenic mice overexpressing TGF-beta or a dominant negative TGF-beta receptor II under control of the CD2 minigene, we show that TGF-beta signaling in tumor infiltrating T lymphocytes regulates the growth of dysplastic colon epithelial cells, as determined by histology and a novel system for high resolution chromoendoscopy in vivo. At the molecular level, TGF-beta signaling in T cells regulated STAT-3 activation in tumor cells via IL-6. IL-6 signaling required tumor cell derived soluble IL-6R rather than membrane bound IL-6R and suppression of such TGF-beta-dependent IL-6 trans-signaling prevented tumor progression in vivo. Similar to these observations in mice, here we show that human colon cancer tissue expressed only low amounts of membrane bound IL-6R. In contrast, expression and activity of the matrix metalloproteinase TACE were increased. In summary, our data provide novel insights into the role of TGF-beta signaling in colorectal cancer and suggest novel therapeutic approaches for colorectal cancer based on an inhibition of TGF-beta-dependent IL-6 trans-signaling.

TGF-beta suppresses tumor progression in colon cancer by inhibition of IL-6 trans-signaling

Alterations of TGF-beta signaling have been described in colorectal cancer, although the molecular consequences are largely unknown. By using transgenic mice overexpressing TGF-beta or a dominant-negative TGF-betaRII, we demonstrate that TGF-beta signaling in tumor infiltrating T lymphocytes controls the growth of dysplastic epithelial cells in experimental colorectal cancer, as determined by histology and a novel system for high-resolution chromoendoscopy. At the molecular level, TGF-beta signaling in T cells regulated STAT-3 activation in tumor cells via IL-6. IL-6 signaling required tumor cell-derived soluble IL-6R rather than membrane bound IL-6R and suppression of such TGF-beta-dependent IL-6 trans-signaling prevented tumor progression in vivo. Taken together, our data provide novel insights into TGF-beta signaling in colorectal cancer and suggest novel therapeutic approaches for colorectal cancer based on inhibition of TGF-beta-dependent IL-6 trans-signaling.

Cutting edge: TGF-beta induces a regulatory phenotype in CD4+CD25- T cells through Foxp3 induction and down-regulation of Smad7

CD4(+)CD25(+) regulatory cells are a subpopulation of T lymphocytes of thymic origin. However, recent data suggest an alternative commitment of regulatory T cells in the periphery, although the precise mechanism is unknown. In the present work, we demonstrate that TGF-beta is able to induce Foxp3 expression and subsequently a regulatory phenotype in CD4(+)CD25(-) peripheral murine T cells. Similarly, TGF-beta induced Foxp3 in human CD4(+)CD25(-) T cells. Moreover, we show that the inhibitory Smad7 protein that is normally induced by TGF-beta and limits TGF-beta signaling, is strongly down-regulated by Foxp3 at the transcriptional level. Foxp3-mediated down-regulation of Smad7 subsequently rendered CD4(+)CD25(-) T cells highly susceptible to the morphogenic and regulatory effects of TGF-beta signaling via Smad3/4. In summary, we demonstrate that TGF-beta induces a regulatory phenotype in CD4(+)CD25(-) T cells through the induction of Foxp3 and a positive autoregulatory loop of TGF-beta signaling due to the absence of Smad7.

Spatiotemporal patterns of expression of neurotrophins and neurotrophin receptors in mice suggest functional roles in testicular and epididymal morphogenesis

Several reports have established that the action of neurotrophins is not restricted to the nervous system but can affect a broad range of non-neuronal cells. Nerve growth factor (NGF) is present in adult testis and has been suggested as a potential regulator of meiosis in rat seminiferous epithelium. Here we present an extensive immunohistochemical study on neurotrophins and their receptors (p75 and trk) in the developing mouse testis and epididymis, and in fetal human testis. During the early steps of testicular and epididymal organization in the mouse, strong p75 immunoreactivity is detectable in the gonadal ridge in the mesenchyme that is excluded from the evolving testicular cords, and in the mesenchymal cells of the mesonephros. Later in organogenesis, most of the p75-positive interstitial cells of the testis coexpress neurotrophin-3 (NT-3) and the truncated trk B receptor in a developmentally regulated pattern. Our Western blot data confirm the expression of these molecules. These findings suggest that neurotrophin receptors play a role in early inductive events during critical periods of testicular and epididymal development. During fetal and postnatal histogenesis, an increasing number of NT-3- and p75-positive mesenchymal cells start to express alpha-smooth muscle isoactin, suggesting a role for the so-called neurotrophic system in the differentiation of testicular myoid cells and epididymal smooth muscle cells. In the testis of an 18-wk gestational-age human fetus, immunohistochemical analysis has shown intense immunoreactivity of mesenchymal cells to antibodies for neurotrophin receptors p75, trk A, and trk C, and their ligands NGF and NT-3. In addition, we found that in the human fetal testis, the interstitial cells that are differentiating into peritubular myoid cells are associated with a dense network of nerve fibers. Our data suggest that neurotrophins and their receptors are involved in a multifunctional system that regulates cell differentiation and innervation in the developing testis and epididymis.