Gut-Selective Integrin-Targeted Therapies for Inflammatory Bowel Disease

Gut-associated lymphoid tissue attrition associates with response to anti-α4β7 therapy in ulcerative colitis

Vedolizumab (VDZ) is a first-line treatment in ulcerative colitis (UC) that targets the α4β7- mucosal vascular addressin cell adhesion molecule 1 (MAdCAM-1) axis. To determine the mechanisms of action of VDZ, we examined five distinct cohorts of patients with UC. A decrease in naïve B and T cells in the intestines and gut-homing (β7+) plasmablasts in circulation of VDZ-treated patients suggested that VDZ targets gut-associated lymphoid tissue (GALT). Anti-α4β7 blockade in wild-type and photoconvertible (KikGR) mice confirmed a loss of GALT size and cellularity because of impaired cellular entry. In VDZ-treated patients with UC, treatment responders demonstrated reduced intestinal lymphoid aggregate size and follicle organization and a reduction of β7+IgG+ plasmablasts in circulation, as well as IgG+ plasma cells and FcγR-dependent signaling in the intestine. GALT targeting represents a previously unappreciated mechanism of action of α4β7-targeted therapies, with major implications for this therapeutic paradigm in UC.

Prospective trial of natalizumab personalised extended interval dosing by therapeutic drug monitoring in relapsing-remitting multiple sclerosis (NEXT-MS)

BACKGROUND

Extended interval dosing (EID) of natalizumab is a promising strategy to optimise treatment in multiple sclerosis (MS). Personalised EID by therapeutic drug monitoring can enable further extension of treatment intervals.

METHODS

The NEXT-MS trial is an investigator-initiated prospective phase IV non-randomised study. Adults with a diagnosis of relapsing-remitting MS who received ≥6 natalizumab infusions were included in three groups: personalised EID with a target drug trough concentration of 10 µg/mL (EID10), an exploratory group of personalised EID with a target of 5 µg/mL (EID5) and standard interval dosing (SID) of 4 weeks. The primary outcome is radiological disease activity (new/newly enlarged T2 lesions) comparing the EID10 group to a historical cohort of SID (HSID).

RESULTS

Results of the first phase of the NEXT-MS trial are reported here (n=376) as the study will continue with an amended protocol. In the EID10 group (n=251), incidence rate of radiological activity was 10.0 per 1000 person-years, which was non-inferior to the HSID cohort (24.7 per 1000 person-years (n=87), incidence rate difference 14.7, 90% CI -4.5 to 34.0). Incidence rate of radiological activity was 10.0 per 1000 person-years in the EID5 group (n=65), and 47.0 per 1000 person-years in the SID group (n=60). Serum neurofilament light levels did not increase over time within the EID groups. There were no cases of progressive multifocal leukoencephalopathy.

CONCLUSIONS

MS disease activity is adequately controlled with personalised natalizumab EID. Interval extension to a drug trough concentration of 5 µg/mL is likely a safe target to extend natalizumab treatment intervals >6 weeks.

TRIAL REGISTRATION NUMBER

NCT04225312.

Gut-tropic T cells and extra-intestinal autoimmune diseases

Gut-tropic T cells primarily originate from gut-associated lymphoid tissue (GALT), and gut-tropic integrins mediate the trafficking of the T cells to the gastrointestinal tract, where their interplay with local hormones dictates the residence of the immune cells in both normal and compromised gastrointestinal tissues. Targeting gut-tropic integrins is an effective therapy for inflammatory bowel disease (IBD). Gut-tropic T cells are further capable of entering the peripheral circulatory system and relocating to multiple organs. There is mounting evidence indicating a correlation between gut-tropic T cells and extra-intestinal autoimmune disorders. This review aims to systematically discuss the origin, migration, and residence of gut-tropic T cells and their association with extra-intestinal autoimmune-related diseases. These discoveries are expected to offer new understandings into the development of a range of autoimmune disorders, as well as innovative approaches for preventing and treating the diseases.

Mesenchymal stromal cells with chimaeric antigen receptors for enhanced immunosuppression

Allogeneic mesenchymal stromal cells (MSCs) are a safe treatment option for many disorders of the immune system. However, clinical trials using MSCs have shown inconsistent therapeutic efficacy, mostly owing to MSCs providing insufficient immunosuppression in target tissues. Here we show that antigen-specific immunosuppression can be enhanced by genetically modifying MSCs with chimaeric antigen receptors (CARs), as we show for E-cadherin-targeted CAR-MSCs for the treatment of graft-versus-host disease in mice. CAR-MSCs led to superior T-cell suppression and localization to E-cadherin+ colonic cells, ameliorating the animals' symptoms and survival rates. On antigen-specific stimulation, CAR-MSCs upregulated the expression of immunosuppressive genes and receptors for T-cell inhibition as well as the production of immunosuppressive cytokines while maintaining their stem cell phenotype and safety profile in the animal models. CAR-MSCs may represent a widely applicable therapeutic technology for enhancing immunosuppression.

MAdCAM-1 targeting strategy can prevent colitic cancer carcinogenesis and progression via suppression of immune cell infiltration and inflammatory signals

Chronic inflammation caused by infiltrating immune cells can promote colitis-associated dysplasia/colitic cancer in ulcerative colitis (UC) by activating inflammatory cytokine signalling through the IL-6/p-STAT3 and TNFα/NF-κB pathways. Mucosal addressin cell adhesion molecule-1 (MAdCAM-1) expressed on high endothelial venules promotes the migration of immune cells from the bloodstream to the gut via interaction with α4β7 integrin expressed on the immune cells. MAdCAM-1, has therefore drawn interest as a novel therapeutic target for treating active UC. However, the role of MAdCAM-1-positive endothelial cells in immune cell infiltration in dysplasia/colitic cancers remains unclear. We evaluated the expression of MAdCAM-1, CD31 and immune cell markers (CD8, CD68, CD163 and FOXP3) in samples surgically resected from 11 UC patients with dysplasia/colitic cancer and 17 patients with sporadic colorectal cancer (SCRC), using immunohistochemical staining. We used an azoxymethane/dextran sodium sulphate mouse model (AOM/DSS mouse) to evaluate whether dysplasia/colitic cancer could be suppressed with an anti-MAdCAM-1 blocking antibody by preventing immune cell infiltration. The number of MAdCAM-1-positive vessels and infiltrating CD8+ , CD68+ and CD163+ immune cells was significantly higher in dysplasia/colitic cancer than in normal, SCRC and UC mucosa. In AOM/DSS mice, the anti-MAdCAM-1 antibody reduced the number, mean diameter, depth of tumours, Ki67 positivity, number of CD8+ , CD68+ and CD163+ immune cells and the IL-6/p-STAT3 and TNF-α/NF-κB signalling. Our results indicate that targeting MAdCAM-1 is a promising strategy for controlling not only UC severity but also carcinogenesis and tumour progression by regulating inflammation/immune cell infiltration in patients with UC.

Further characterization of Shigella-specific (memory) B cells induced in healthy volunteer recipients of SF2a-TT15, a Shigella flexneri 2a synthetic glycan-based vaccine candidate

Shigellosis is common worldwide, and it causes significant morbidity and mortality mainly in young children in low- and middle- income countries. To date, there are not broadly available licensed Shigella vaccines. A novel type of conjugate vaccine candidate, SF2a-TT15, was developed against S. flexneri serotype 2a (SF2a). SF2a-TT15 is composed of a synthetic 15mer oligosaccharide, designed to act as a functional mimic of the SF2a O-antigen and covalently linked to tetanus toxoid (TT). SF2a-TT15 was recently shown to be safe and immunogenic in a Phase 1 clinical trial, inducing specific memory B cells and sustained antibody response up to three years after the last injection. In this manuscript, we advance the study of B cell responses to parenteral administration of SF2a-TT15 to identify SF2a LPS-specific B cells (SF2a+ B cells) using fluorescently labeled bacteria. SF2a+ B cells were identified mainly within class-switched B cells (SwB cells) in volunteers vaccinated with SF2a-TT15 adjuvanted or not with aluminium hydroxide (alum), but not in placebo recipients. These cells expressed high levels of CXCR3 and low levels of CD21 suggesting an activated phenotype likely to represent the recently described effector memory B cells. IgG SF2a+ SwB cells were more abundant than IgA SF2a + SwB cells. SF2a+ B cells were also identified in polyclonally stimulated B cells (antibody secreting cells (ASC)-transformed). SF2a+ ASC-SwB cells largely maintained the activated phenotype (CXCR3 high, CD21 low). They expressed high levels of CD71 and integrin α4β7, suggesting a high proliferation rate and ability to migrate to gut associated lymphoid tissues. Finally, ELISpot analysis showed that ASC produced anti-SF2a LPS IgG and IgA antibodies. In summary, this methodology confirms the ability of SF2a-TT15 to induce long-lived memory B cells, initially identified by ELISpots, which remain identifiable in blood up to 140 days following vaccination. Our findings expand and complement the memory B cell data previously reported in the Phase 1 trial and provide detailed information on the immunophenotypic characteristics of these cells. Moreover, this methodology opens the door to future studies at the single-cell level to better characterize the development of B cell immunity to Shigella.

Emerging Therapies for Ulcerative Colitis: Updates from Recent Clinical Trials

Ulcerative colitis (UC) is a chronic and progressive inflammatory disorder that affects the colon. The advent of advanced therapies such as biologic agents and small molecules has revolutionized the management of UC. Despite the expanding therapeutic armamentarium of advanced therapies to treat UC, the overall net remission rates and durability of currently available agents are relatively low. This highlights the need for further drug development and more innovative clinical trial design. There are currently multiple emerging agents in the pipeline for the management of UC. This includes agents with alternative routes of administration such as oral or subcutaneous tumor necrosis factor inhibitors or novel mechanisms of action such as toll-like receptor 9 (TLR9) agonist cobitolimod and phosphodiesterase 4 inhibitor apremilast. In this review, we will highlight novel and emerging advanced therapies currently in the pipeline for the management of UC.

Concurrent immune checkpoint inhibition and selective immunosuppressive therapy in patients with immune-related enterocolitis

PURPOSE

Immune checkpoint inhibitor (ICI) therapy is often suspended because of immune-related enterocolitis (irEC). We examined the effect of resumption of ICIs with or without concurrent selective immunosuppressive therapy (SIT) on rates of symptom recurrence and survival outcomes.

METHODS

This retrospective, multicenter study examined patients who were treated with ICI and developed irEC requiring SIT (infliximab or vedolizumab) for initial symptom control or to facilitate steroid tapering between May 2015 and June 2020. After symptom resolution, patients were restarted either on ICI alone or on concurrent ICI and SIT at the discretion of the treating physicians. The associations between irEC recurrence and treatment group were assessed via univariate analyses and multivariate logistic regression. Cox proportional hazards model was used for survival analysis.

RESULTS

Of the 138 included patients who required SIT for initial irEC symptom control, 61 (44.2%) patients resumed ICI without concurrent SIT (control group) and 77 (55.8%) patients resumed ICI therapy with concurrent SIT: 33 with infliximab and 44 with vedolizumab. After symptom resolution, patients in the control group were more commonly restarted on a different ICI regimen (65.6%) compared with those receiving SIT (31.2%) (p<0.001). The total number of ICI doses administered after irEC resolution and ICI resumption was similar in both groups (four to five doses). Recurrence of severe colitis or diarrhea after ICI resumption was seen in 34.4% of controls compared with 20.8% of patients receiving concurrent SIT. Concurrent SIT was associated with reduced risk of severe irEC recurrence after ICI resumption in a multivariate logistic regression model (OR 0.34; 95% CI 0.13 to 0.92; p=0.034). There was no difference in survival outcomes between patients in the control group and patients concurrently treated with SIT.

CONCLUSION

After resolution of irEC symptoms, reinitiation of ICI with concurrent SIT is safe, reduces severe irEC recurrence, and has no negative impact on survival outcomes.

Safety and Effectiveness of Vedolizumab in Patients with Moderate-to-Severe Ulcerative Colitis: An Interim Analysis of a Japanese Post-Marketing Surveillance Study

INTRODUCTION

This ongoing post-marketing surveillance monitors the long-term safety and effectiveness of vedolizumab in routine clinical practice in patients with moderate-to-severe ulcerative colitis (UC) in Japan. This interim analysis assessed induction-phase data, covering the initial three doses of vedolizumab.

METHODS

Patients were enrolled via a web-based electronic data capture system from approximately 250 institutions. Incidence of adverse events and treatment responses were assessed by the physicians after the patient had received three doses of vedolizumab or when the drug was discontinued, whichever occurred first. Therapeutic response was defined as any treatment response, including remission or improvement of complete or partial Mayo score, and was assessed in the total and stratified patient populations according to prior tumor necrosis factor alpha (TNFα) inhibitor treatments and/or baseline partial Mayo score.

RESULTS

The total incidence of adverse drug reactions (ADRs) was 4.10% (11/268). Common ADRs were dizziness, nausea, and arthralgia, each reported in 0.75% of patients (2/268). Serious ADRs were herpes zoster oticus and UC, each reported in 0.37% of patients (1/268). Therapeutic response was reported in 84.5% (218/258) of all patients, 85.8% (127/148) of TNFα inhibitor-naïve patients, and 82.7% (91/110) of TNFα inhibitor-experienced patients. Among patients with partial Mayo score of ≥ 4 at baseline, partial Mayo score remission in patients without or with prior TNFα inhibitor treatment was 62.5% (60/96) and 45.6% (36/79), respectively.

CONCLUSION

The results confirm a safety and effectiveness profile of vedolizumab consistent with that observed in previous trials.

CLINICAL TRIAL REGISTRATION

JapicCTI-194603, NCT03824561.

Force-Regulated Calcium Signaling of Lymphoid Cell RPMI 8226 Mediated by Integrin α4β7/MAdCAM-1 in Flow

MAdCAM-1 binds to integrin α₄β₇, which mediates the rolling and arrest of circulating lymphocytes upon the vascular endothelia during lymphocytic homing. The calcium response by adhered lymphocytes is a critical event for lymphocyte activation and subsequent arrest and migration under flow. However, whether the interaction of integrin α₄β₇ /MAdCAM-1 can effectively trigger the calcium response of lymphocytes remains unclear, as well as whether the fluid force affects the calcium response. In this study, we explore the mechanical regulation of integrin α₄β₇-induced calcium signaling under flow. Flou-4 AM was used to examine the calcium response under real-time fluorescence microscopy when cells were firmly adhered to a parallel plate flow chamber. The interaction between integrin α₄β₇ and MAdCAM-1 was found to effectively trigger calcium signaling in firmly adhered RPMI 8226 cells. Meanwhile, increasing fluid shear stress accelerated the cytosolic calcium response and enhanced signaling intensity. Additionally, the calcium signaling of RPMI 8226 activated by integrin α₄β₇ originated from extracellular calcium influx instead of cytoplasmic calcium release, and the signaling transduction of integrin α₄β₇ was involved in Kindlin-3. These findings shed new light on the mechano-chemical mechanism of calcium signaling in RPMI 8226 cells induced by integrin α₄β_7.

Gut-associated lymphoid tissue attrition associates with response to anti-α4β7 therapy in ulcerative colitis

Targeting the α4β7-MAdCAM-1 axis with vedolizumab (VDZ) is a front-line therapeutic paradigm in ulcerative colitis (UC). However, mechanism(s) of action (MOA) of VDZ remain relatively undefined. Here, we examined three distinct cohorts of patients with UC (n=83, n=60, and n=21), to determine the effect of VDZ on the mucosal and peripheral immune system. Transcriptomic studies with protein level validation were used to study drug MOA using conventional and transgenic murine models. We found a significant decrease in colonic and ileal naïve B and T cells and circulating gut-homing plasmablasts (β7+) in VDZ-treated patients, pointing to gut-associated lymphoid tissue (GALT) targeting by VDZ. Murine Peyer's patches (PP) demonstrated a significant loss cellularity associated with reduction in follicular B cells, including a unique population of epithelium-associated B cells, following anti-α4β7 antibody (mAb) administration. Photoconvertible (KikGR) mice unequivocally demonstrated impaired cellular entry into PPs in anti-α4β7 mAb treated mice. In VDZ-treated, but not anti-tumor necrosis factor-treated UC patients, lymphoid aggregate size was significantly reduced in treatment responders compared to non-responders, with an independent validation cohort further confirming these data. GALT targeting represents a novel MOA of α4β7-targeted therapies, with major implications for this therapeutic paradigm in UC, and for the development of new therapeutic strategies.

The treatment of inflammatory bowel disease with monoclonal antibodies in Asia

Crohn's disease (CD) and ulcerative colitis (UC), the two main forms of inflammatory bowel disease (IBD), are chronic, systemic autoimmune diseases. As the incidence of IBD rapidly increases in Asia, increasing attention has been paid to developing additional treatment strategies. Presently, the end point of therapy is achieving clinical and endoscopic remission through the blockade of inflammatory cascades. Recent studies have shown that monoclonal antibodies (mAbs) use for precise molecular targeting of inflammatory pathways has a promising effect on IBD, especially moderate-to-severe CD and UC. Since the 1997 report on the use of infliximab (a monoclonal antibody against tumor necrosis factor alpha [TNF-α]) in patients with CD, mAbs have expanded therapeutic options and have also complicated initial management options and subsequent treatment. This review comprehensively summarizes the clinical reports and studies related to the use of mAbs for the treatment of IBD in Asian countries and regions in recent years thus demonstrating the current status of mAbs use in Asia. In addition, the differences in the use of mAbs for the treatment of IBD between the Asia and the West are expounded. Ultimately, it is hoped that this review will provide new insights and a scientific basis for the clinical application of mAbs.

An NKX-COUP-TFII morphogenetic code directs mucosal endothelial addressin expression

Immunoglobulin family and carbohydrate vascular addressins encoded by Madcam1 and St6gal1 control lymphocyte homing into intestinal tissues, regulating immunity and inflammation. The addressins are developmentally programmed to decorate endothelial cells lining gut post-capillary and high endothelial venules (HEV), providing a prototypical example of organ- and segment-specific endothelial specialization. We identify conserved NKX-COUP-TFII composite elements (NCCE) in regulatory regions of Madcam1 and St6gal1 that bind intestinal homeodomain protein NKX2-3 cooperatively with venous nuclear receptor COUP-TFII to activate transcription. The Madcam1 element also integrates repressive signals from arterial/capillary Notch effectors. Pan-endothelial COUP-TFII overexpression induces ectopic addressin expression in NKX2-3⁺ capillaries, while NKX2-3 deficiency abrogates expression by HEV. Phylogenetically conserved NCCE are enriched in genes involved in neuron migration and morphogenesis of the heart, kidney, pancreas and other organs. Our results define an NKX-COUP-TFII morphogenetic code that targets expression of mucosal vascular addressins.

Tackling Inflammatory Bowel Diseases: Targeting Proinflammatory Cytokines and Lymphocyte Homing

Inflammatory bowel diseases (IBDs) are characterized by chronic inflammatory disorders that are a result of an abnormal immune response mediated by a cytokine storm and immune cell infiltration. Proinflammatory cytokine therapeutic agents, represented by TNF inhibitors, have developed rapidly over recent years and are promising options for treating IBD. Antagonizing interleukins, interferons, and Janus kinases have demonstrated their respective advantages in clinical trials and are candidates for anti-TNF therapeutic failure. Furthermore, the blockade of lymphocyte homing contributes to the excessive immune response in colitis and ameliorates inflammation and tissue damage. Factors such as integrins, selectins, and chemokines jointly coordinate the accumulation of immune cells in inflammatory regions. This review assembles the major targets and agents currently targeting proinflammatory cytokines and lymphatic trafficking to facilitate subsequent drug development.

Efficacy and safety of vedolizumab for pediatrics with inflammatory bowel disease: a systematic review

BACKGROUND

Vedolizumab use in pediatrics is still off-label and the data are limited. We conducted a systematic review evaluating the efficacy and safety of vedolizumab in children and adolescents with inflammatory bowel disease (IBD).

METHODS

PubMed, EMBASE and Cochrane databases were systematically searched for studies of vedolizumab in children and adolescents with IBD reporting clinical remission, response, corticosteroid-free (CS-free) remission, mucosal healing, or safety up to December 3^rd 2021.

RESULTS

Ten studies, comprising 455 patients were included. For CD, the pooled clinical remission rates were 25% (19/75) at 6 weeks, 28% (25/85) at 14 weeks, 32% (17/53) at 22 weeks, and 46% (43/92) at 1 year. For UC/IBD-U, the pooled clinical remission rates were 36% (25/70) at 6 weeks, 48% (52/101) at 14 weeks, 53% (24/45) at 22 weeks, and 45% (50/112) at 1 year. Mucosal healing was found in 17%-39% of CD and 15%-34% of UC/IBD-U respectively. Six percent of patients reported serious adverse events.

CONCLUSIONS

According to low-quality evidence based on case series, approximately one-third and one-half of patients for CD and UC/IBD-U respectively achieved remission within 22 weeks, and about half of patients achieved remission at 1 year with reasonable safety profile. Long-term benefit profile data and high quality evidence are still needed.

Absence of Oral Opportunistic Infections in Patients with Inflammatory Bowel Disease Receiving Anti-TNF-α and Anti-Integrin-α4β7 Therapy

Biological therapy of inflammatory bowel disease (IBD) carries an increased risk for the development of opportunistic infections due to immunomodulation. The aim of this study was to determine the prevalence and types of oral infections in IBD patients treated with biological (anti-TNF-α and anti-integrin-α4β7) and conventional medication protocols. The study included 20 IBD patients receiving anti-TNF-α therapy, 20 IBD patients receiving anti-integrin-α4β7 therapy and 20 IBD patients without immunomodulatory therapy. Participants completed questionnaires on medical information, oral lesions and symptoms. For each patient, clinical examination and a salivary flow rate test were performed, followed by a swab of the oral mucosa. The swab samples were cultured to identify Candida spp. and oral bacteria. No bacterial opportunistic infections were detected. Candidiasis was detected in four participants, with no significant difference between groups (p = 0.765). Hyposalivation was most common in the anti-TNF-α group, with a significant difference between groups (p = 0.036). There were no significant differences between groups in self-reported oral mucosal lesions and symptoms (p > 0.05), or in the distribution of oral mucosal lesions (p > 0.05). This study suggests that IBD patients receiving biological therapy are at no greater risk of developing oral opportunistic infections than IBD patients not receiving immunomodulatory therapy.

A review of the therapeutic management of Crohn's disease

Crohn's disease is a chronic inflammatory, relapsing-remitting, and progressive gastrointestinal disorder with an often-negative impact on the physical, emotional, and psychological well-being. Over the past two decades, the medical compendium for the treatment of Crohn's disease has increased significantly, enabling treatment beyond symptoms. Indeed, early and timely use of effective medical therapy has been reflected by improved outcomes with reduction in surgery and ability to achieve clinical and endoscopic remission, reduce corticosteroid dependance, and prevent long-term complications in more patients. In this review, we discuss the key milestones in the medical management of Crohn's disease.

Susceptibility to disease (tropical theileriosis) is associated with differential expression of host genes that possess motifs recognised by a pathogen DNA binding protein

Background

Knowledge of factors that influence the outcome of infection are crucial for determining the risk of severe disease and requires the characterisation of pathogen-host interactions that have evolved to confer variable susceptibility to infection. Cattle infected by Theileria annulata show a wide range in disease severity. Native (Bos indicus) Sahiwal cattle are tolerant to infection, whereas exotic (Bos taurus) Holstein cattle are susceptible to acute disease.

Methodology/Principal findings

We used RNA-seq to assess whether Theileria infected cell lines from Sahiwal cattle display a different transcriptome profile compared to Holstein and screened for altered expression of parasite factors that could generate differences in host cell gene expression.

Significant differences (<0.1 FDR) in the expression level of a large number (2211) of bovine genes were identified, with enrichment of genes associated with Type I IFN, cholesterol biosynthesis, oncogenesis and parasite infection. A screen for parasite factors found limited evidence for differential expression. However, the number and location of DNA motifs bound by the TashAT2 factor (TA20095) were found to differ between the genomes of B. indicus vs. B. taurus, and divergent motif patterns were identified in infection-associated genes differentially expressed between Sahiwal and Holstein infected cells.

Conclusions/Significance

We conclude that divergent pathogen-host molecular interactions that influence chromatin architecture of the infected cell are a major determinant in the generation of gene expression differences linked to disease susceptibility.

Integrin αEβ7 is involved in the intestinal barrier injury of sepsis

Background: IL-9-producing CD4(+) T (Th9) cell was related to acute intestinal barrier injury in sepsis. Integrin αEβ7 was an important lymphocyte homing receptor on the surface of intestinal Th9 cells. However, the roles of αEβ7 in the intestinal injury caused by Th9 cells were not clear in sepsis.

Methods: To investigate the roles of αEβ7 in the intestinal injury caused by Th9 cells in sepsis model, the Th9 cells percentages, αEβ7, E-cadherin, IL-9, and D-lactate levels in both serum and intestinal tissue were measured. The intestinal histopathology, epithelium apoptosis, and mucosal permeability measurement were also performed. The survival rate of septic rats was recorded daily for 14 days.

Results: Rats were assigned to four cohorts: control cohort, sepsis cohort, sepsis+αEβ7i (αEβ7 inhibition) cohort, and sepsis+αEβ7e (αEβ7 overexpression) cohort. The Th9 cells percentages, αEβ7, IL-9, and D-lactate levels of the sepsis cohort were significantly higher than those of the control cohort. The levels of these variables were also elevated progressively in the sepsis+αEβ7i cohort, sepsis cohort, and sepsis+αEβ7e cohort. The E-cadherin levels were decreased progressively in the control cohort, sepsis+αEβ7i cohort, sepsis cohort, and sepsis+αEβ7e cohort. Moreover, αEβ7 overexpression could decrease the 14-day survival rate. The findings of histopathology staining, apoptosis detection, and intestinal permeability test also confirmed that the barrier injury was deteriorated or relieved by elevating or decreasing the αEβ7 expression levels, respectively.

Conclusions: Integrin αEβ7 was closely associated with the intestinal barrier injury caused by Th9 lymphocytes in sepsis.

Targeting PDE4 as a promising therapeutic strategy in chronic ulcerative colitis through modulating mucosal homeostasis

Phosphodiesterase-4 (PDE4) functions as a catalyzing enzyme targeting hydrolyzation of intracellular cyclic adenosine monophosphate (cAMP) and inhibition of PDE4 has been proven to be a competitive strategy for dermatological and pulmonary inflammation. However, the pathological role of PDE4 and the therapeutic feasibility of PDE4 inhibitors in chronic ulcerative colitis (UC) are less clearly understood. This study introduced apremilast, a breakthrough in discovery of PDE4 inhibitors, to explore the therapeutic capacity in dextran sulfate sodium (DSS)-induced experimental murine chronic UC. In the inflamed tissues, overexpression of PDE4 isoforms and defective cAMP-mediating pathway were firstly identified in chronic UC patients. Therapeutically, inhibition of PDE4 by apremilast modulated cAMP-predominant protein kinase A (PKA)–cAMP-response element binding protein (CREB) signaling and ameliorated the clinical symptoms of chronic UC, as evidenced by improvements on mucosal ulcerations, tissue fibrosis, and inflammatory infiltrations. Consequently, apremilast maintained a normal intestinal physical and chemical barrier function and rebuilt the mucosal homeostasis by interfering with the cross-talk between human epithelial cells and immune cells. Furthermore, we found that apremilast could remap the landscape of gut microbiota and exert regulatory effects on antimicrobial responses and the function of mucus in the gut microenvironment. Taken together, the present study revealed that intervene of PDE4 provided an infusive therapeutic strategy for patients with chronic and relapsing UC.

Role of mesenteric component in Crohn’s disease: A friend or foe?

Crohn’s disease (CD) is a complex and relapsing gastrointestinal disease with mesenteric alterations. The mesenteric neural, vascular, and endocrine systems actively take part in the gut dysbiosis-adaptive immunity-mesentery-body axis, and this axis has been proven to be bidirectional. The abnormalities of morphology and function of the mesenteric component are associated with intestinal inflammation and disease progress of CD via responses to afferent signals, neuropeptides, lymphatic drainage, adipokines, and functional cytokines. The hypertrophy of mesenteric adipose tissue plays important roles in the pathogenesis of CD by secreting large amounts of adipokines and representing a rich source of proinflammatory or profibrotic cytokines. The vascular alteration, including angiogenesis and lymphangiogenesis, is concomitant in the disease course of CD. Of note, the enlarged and obstructed lymphatic vessels, which have been described in CD patients, are likely related to the early onset submucosa edema and being a cause of CD. The function of mesenteric lymphatics is influenced by endocrine of mesenteric nerves and adipocytes. Meanwhile, the structure of the mesenteric lymphatic vessels in hypertrophic mesenteric adipose tissue is mispatterned and ruptured, which can lead to lymph leakage. Leaky lymph factors can in turn stimulate adipose tissue to proliferate and effectively elicit an immune response. The identification of the role of mesentery and the crosstalk between mesenteric tissues in intestinal inflammation may shed light on understanding the underlying mechanism of CD and help explore new therapeutic targets.

Target-Based Small Molecule Drug Discovery Towards Novel Therapeutics for Inflammatory Bowel Diseases

Inflammatory bowel disease (IBD), including ulcerative colitis (UC) and Crohn's disease (CD), is a class of severe and chronic diseases of the gastrointestinal (GI) tract with recurrent symptoms and significant morbidity. Long-term persistence of chronic inflammation in IBD is a major contributing factor to neoplastic transformation and the development of colitis-associated colorectal cancer. Conversely, persistence of transmural inflammation in CD is associated with formation of fibrosing strictures, resulting in substantial morbidity. The recent introduction of biological response modifiers as IBD therapies, such as antibodies neutralizing tumor necrosis factor (TNF)-α, have replaced nonselective anti-inflammatory corticosteroids in disease management. However, a large proportion (~40%) of patients with the treatment of anti-TNF-α antibodies are discontinued or withdrawn from therapy because of (1) primary nonresponse, (2) secondary loss of response, (3) opportunistic infection, or (4) onset of cancer. Therefore, the development of novel and effective therapeutics targeting specific signaling pathways in the pathogenesis of IBD is urgently needed. In this comprehensive review, we summarize the recent advances in drug discovery of new small molecules in preclinical or clinical development for treating IBD that target biologically relevant pathways in mucosal inflammation. These include intracellular enzymes (Janus kinases, receptor interacting protein, phosphodiesterase 4, IκB kinase), integrins, G protein-coupled receptors (S1P, CCR9, CXCR4, CB2) and inflammasome mediators (NLRP3), etc. We will also discuss emerging evidence of a distinct mechanism of action, bromodomain-containing protein 4, an epigenetic regulator of pathways involved in the activation, communication, and trafficking of immune cells. We highlight their chemotypes, mode of actions, structure-activity relationships, characterizations, and their in vitro/in vivo activities and therapeutic potential. The perspectives on the relevant challenges, new opportunities, and future directions in this field are also discussed.

Regulation and Role of αE Integrin and Gut Homing Integrins in Migration and Retention of Intestinal Lymphocytes during Inflammatory Bowel Disease

Adhesion molecules are upregulated in inflamed intestinal mucosa in IBD patients.

Baseline β7 expression does not impact αE induction or gene expression in T cells.

Phospho-SMAD3 is increased in inflamed mucosa in IBD.

Targeting interactions between α4β7 integrin and endothelial adhesion molecule MAdCAM-1 to inhibit lymphocyte migration to the gastrointestinal tract is an effective therapy in inflammatory bowel disease (IBD). Following lymphocyte entry into the mucosa, a subset of these cells expresses αEβ7 integrin, which is expressed on proinflammatory lymphocytes, to increase cell retention. The factors governing lymphocyte migration into the intestinal mucosa and αE integrin expression in healthy subjects and IBD patients remain incompletely understood. We evaluated changes in factors involved in lymphocyte migration and differentiation within tissues. Both ileal and colonic tissue from active IBD patients showed upregulation of ICAM-1, VCAM-1, and MAdCAM-1 at the gene and protein levels compared with healthy subjects and/or inactive IBD patients. β1 and β7 integrin expression on circulating lymphocytes was similar across groups. TGF-β1 treatment induced expression of αE on both β7⁺ and β7⁻ T cells, suggesting that cells entering the mucosa independently of MAdCAM-1/α4β7 can become αEβ7⁺. ITGAE gene polymorphisms did not alter protein induction following TGF-β1 stimulation. Increased phospho-SMAD3, which is directly downstream of TGF-β, and increased TGF-β–responsive gene expression were observed in the colonic mucosa of IBD patients. Finally, in vitro stimulation experiments showed that baseline β7 expression had little effect on cytokine, chemokine, transcription factor, and effector molecule gene expression in αE⁺ and αE⁻ T cells. These findings suggest cell migration to the gut mucosa may be altered in IBD and α4β7⁻, and α4β7⁺ T cells may upregulate αEβ7 in response to TGF-β once within the gut mucosa.

Lower incidence of COVID-19 in patients with inflammatory bowel disease treated with non-gut selective biologic therapy

BACKGROUND AND AIM

Since the outbreak of COVID-19, concerns have been raised as to whether inflammatory bowel disease (IBD) patients under biologic therapy may be more susceptible to the disease. This study aimed to determine the incidence and outcomes of COVID-19 in a large cohort of IBD patients on biologic therapy.

METHODS

This observational retrospective multicenter study collected data about COVID-19 in IBD patients on biologic therapy in Italy, between February and May 2020. The main end-points were (i) to assess both the cumulative incidence and clinical outcome of COVID-19, according to different biologic agents and (ii) to compare them with the general population and a cohort IBD patients undergoing non-biologic therapies.

RESULTS

Among 1816 IBD patients, the cumulative incidence of COVID-19 was 3.9 per 1000 (7/1816) with a 57% hospitalization rate and a 29% case-fatality rate. The class of biologic agents was the only risk factor of developing COVID-19 (P = 0.01). Non-gut selective agents were associated with a lower incidence of COVID-19 cases, related symptoms, and hospitalization (P < 0.05). Compared with the general population of Lombardy, an overall lower incidence of COVID-19 was observed (3.9 vs 8.5 per 1000, P = 0.03). Compared with 565 IBD patients on non-biologic therapies, a lower rate of COVID-19 symptoms was observed in our cohort (7.5% vs 18%, P < 0.001).

CONCLUSIONS

Compared with the general population, IBD patients on biologic therapy are not exposed to a higher risk of COVID-19. Non-gut selective agents are associated with a lower incidence of symptomatic disease, supporting the decision of maintaining the ongoing treatment.

Targeting Leukocyte Trafficking in Inflammatory Bowel Disease

In the last two decades, understanding of inflammatory bowel disease (IBD) immunopathogenesis has expanded considerably. Histopathological examination of the intestinal mucosa in IBD demonstrates the presence of a chronic inflammatory cell infiltrate. Research has focused on identifying mechanisms of immune cell trafficking to the gastrointestinal tract that may represent effective gut-selective targets for IBD therapy whilst avoiding systemic immunosuppression that may be associated with off-target adverse effects such as infection and malignancy. Integrins are cell surface receptors that can bind to cellular adhesion molecules to mediate both leukocyte homing and retention. In 2014, Vedolizumab (Entyvio^®) was the first anti-integrin (anti-α4ß7 monoclonal antibody) treatment to be approved for use in IBD. Several other anti-integrin therapies are currently in advanced stages of development, including novel orally administered small-molecule drugs. Drugs targeting alternative trafficking mechanisms such as mucosal addressin cellular adhesion molecule-1 and sphingosine-1-phosphate receptors are also being evaluated. Here, we summarise key established and emerging therapies targeting leukocyte trafficking that may play an important role in realising the goal of stratified precision medicine in IBD care.

E-cadherin activating antibodies limit barrier dysfunction and inflammation in mouse inflammatory bowel disease

Deficits in gastrointestinal (GI) paracellular permeability has been implicated in etiology of Inflammatory Bowel Disease (IBD), and E-cadherin, a key component of the epithelial junctional complex, has been implicated in both barrier function and IBD. We have previously described antibodies against E-cadherin that activate cell adhesion, and in this study, we show that they increase transepithelial electrical resistance in epithelial cell monolayers in vitro. We therefore tested the hypothesis that adhesion activating E-cadherin mAbs will enhance epithelial barrier function in vivo and limit progression of inflammation in IBD. Activating mAbs to mouse E-cadherin were tested in different mouse models of IBD including the IL10-/- and adoptive T cell transfer models of colitis. Previously established histological and biomarker measures of inflammation were evaluated to monitor disease progression. Mouse E-cadherin activating mAb treatment reduced total colitis score, individual histological measures of inflammation, and other hallmarks of inflammation compared to control treatment. Activating mAbs also reduced the fecal accumulation lipocalin2 and albumin content, consistent with enhanced barrier function. Therefore, E-cadherin activation could be a potential strategy for limiting inflammation in UC.

Development of Anti-fibrotic Therapy in Stricturing Crohn's Disease: Lessons from Randomized Trials in Other Fibrotic Diseases

Intestinal fibrosis is considered an inevitable complication of Crohn's disease (CD) that results in symptoms of obstruction and stricture formation. Endoscopic or surgical treatment is required to treat the majority of patients. Progress in the management of stricturing CD is hampered by the lack of effective anti-fibrotic therapy; however, this situation is likely to change because of recent advances in other fibrotic diseases of the lung, liver and skin. In this review, we summarized data from randomized controlled trials (RCT) of anti-fibrotic therapies in these conditions. Multiple compounds have been tested for the anti-fibrotic effects in other organs. According to their mechanisms, they were categorized into growth factor modulators, inflammation modulators, 5-hydroxy-3-methylgultaryl-coenzyme A (HMG-CoA) reductase inhibitors, intracellular enzymes and kinases, renin-angiotensin system (RAS) modulators and others. From our review of the results from the clinical trials and discussion of their implications in the gastrointestinal tract, we have identified several molecular candidates that could serve as potential therapies for intestinal fibrosis in CD.

Anti-Integrins for the Treatment of Inflammatory Bowel Disease: Current Evidence and Perspectives

Leukocyte trafficking to the gastrointestinal tract is recognized to play a role in the pathogenesis of inflammatory bowel disease (IBD). Integrins are expressed on immune cells and interact with cell adhesion molecules (CAM) to mediate leukocyte trafficking. Blockade of the gut-tropic integrin α4β7 and its subunits has been exploited as a therapeutic target in IBD. Natalizumab (anti-α4) is approved for moderate to severe Crohn's disease (CD), but its use is limited due to potential risk of progressive multifocal leukoencephalopathy. Vedolizumab (anti-α4β7) is approved for the treatment of ulcerative colitis (UC) and CD. It is the most widely used anti-integrin therapy in IBD and has been shown to be effective in both induction and maintenance therapy, with a favorable safety profile. Several models incorporating clinical, genetic, immune, gut microbial, and vitamin D markers to predict response to vedolizumab in IBD have been developed. Etrolizumab (anti-β7) blocks leukocyte trafficking via α4β7 and cell adhesion via αEβ7 integrins. Large phase 3 clinical trials evaluating efficacy of etrolizumab in the induction and maintenance of patients with IBD are underway. Other investigational anti-integrin therapies include abrilumab (anti-α4β7 IgG2), PN-943 (orally administered and gut-restricted α4β7 antagonist peptide), AJM300 (orally active small molecule inhibitor of α4), and ontamalimab (anti-MAdCAM-1 IgG).

The Gut-Brain Axis in Inflammatory Bowel Disease-Current and Future Perspectives

The gut–brain axis is a bidirectional communication system driven by neural, hormonal, metabolic, immunological, and microbial signals. Signaling events from the gut can modulate brain function and recent evidence suggests that the gut–brain axis may play a pivotal role in linking gastrointestinal and neurological diseases. Accordingly, accumulating evidence has suggested a link between inflammatory bowel diseases (IBDs) and neurodegenerative, as well as neuroinflammatory diseases. In this context, clinical, epidemiological and experimental data have demonstrated that IBD predisposes a person to pathologies of the central nervous system (CNS). Likewise, a number of neurological disorders are associated with changes in the intestinal environment, which are indicative for disease-mediated gut–brain inter-organ communication. Although this axis was identified more than 20 years ago, the sequence of events and underlying molecular mechanisms are poorly defined. The emergence of precision medicine has uncovered the need to take into account non-intestinal symptoms in the context of IBD that could offer the opportunity to tailor therapies to individual patients. The aim of this review is to highlight recent findings supporting the clinical and biological link between the gut and brain, as well as its clinical significance for IBD as well as neurodegeneration and neuroinflammation. Finally, we focus on novel human-specific preclinical models that will help uncover disease mechanisms to better understand and modulate the function of this complex system.

Dual targeting of lymphocyte homing and retention through α4β7 and αEβ7 inhibition in inflammatory bowel disease

Anti-integrins are therapeutically effective for inflammatory bowel disease, yet the relative contribution of α4β7 and αEβ7 to gut lymphocyte trafficking is not fully elucidated. Here, we evaluate the effect of α4β7 and αEβ7 blockade using a combination of murine models of gut trafficking and longitudinal gene expression analysis in etrolizumab-treated patients with Crohn's disease (CD). Dual blockade of α4β7 and αEβ7 reduces CD8+ T cell accumulation in the gut to a greater extent than blockade of either integrin alone. Anti-αEβ7 reduces epithelial:T cell interactions and promotes egress of activated T cells from the mucosa into lymphatics. Inflammatory gene expression is greater in human intestinal αEβ7+ T cells. Etrolizumab-treated patients with CD display a treatment-specific reduction in inflammatory and cytotoxic intraepithelial lymphocytes (IEL) genes. Concurrent blockade of α4β7 and αEβ7 promotes reduction of cytotoxic IELs and inflammatory T cells in the gut mucosa through a stepwise inhibition of intestinal tissue entry and retention.

Global Gene Expression of T Cells Is Differentially Regulated by Peritoneal Dendritic Cell Subsets in an IL-2 Dependent Manner

Dendritic cells (DCs) in peripheral tissues may have a unique role to regulate innate and adaptive immune responses to antigens that enter the tissues. Peritoneal cavity is the body compartment surrounding various tissues and organs and housing diverse immune cells. Here, we investigated the specialized features of classical DC (cDC) subsets following the intraperitoneal injection of a model antigen ovalbumin (OVA). Peritoneal cDC1s were superior to cDC2s in activating OVA-specific CD8 T cells, while both cDCs were similar in stimulating OVA-specific CD4 T cells. Each peritoneal cDC subset differentially regulated the homing properties of CD8 T cells. CD8 T cells stimulated by cDC1s displayed a higher level of lung-homing receptor CCR4, whereas those stimulated by cDC2s prominently expressed various homing receptors including gut-homing molecules CCR9 and α4β7. Also, we found that cDC1s played a dominating role over cDC2s in controlling the overall gene expression of CD8 T cells. Soluble factor(s) emanating from CD8 T cells stimulated by peritoneal cDC1s were responsible for mediating this dominance of cDC1s, and we identified IL-2 as a soluble factor regulating the global gene expression of T cells. Collectively, our study indicates that different peritoneal cDC subsets effectively diversify T cell responses by altering the level of cytokines, such as IL-2, in the milieu.

Transgenic overexpression of ITGB6 in intestinal epithelial cells exacerbates dextran sulfate sodium-induced colitis in mice

Integrins, as a large family of cell adhesion molecules, play a crucial role in maintaining intestinal homeostasis. In inflammatory bowel disease (IBD), homeostasis is disrupted. Integrin αvβ6, which is mainly regulated by the integrin β6 subunit gene (ITGB6), is a cell adhesion molecule that mediates cell-cell and cell-matrix interactions. However, the role of ITGB6 in the pathogenesis of IBD remains elusive. In this study, we found that ITGB6 was markedly upregulated in inflamed intestinal tissues from patients with IBD. Then, we generated an intestinal epithelial cell-specific ITGB6 transgenic mouse model. Conditional ITGB6 transgene expression exacerbated experimental colitis in mouse models of acute and chronic dextran sulphate sodium (DSS)-induced colitis. Survival analyses revealed that ITGB6 transgene expression correlated with poor prognosis in DSS-induced colitis. Furthermore, our data indicated that ITGB6 transgene expression increased macrophages infiltration, pro-inflammatory cytokines secretion, integrin ligands expression and Stat1 signalling pathway activation. Collectively, our findings revealed a previously unknown role of ITGB6 in IBD and highlighted the possibility of ITGB6 as a diagnostic marker and therapeutic target for IBD.

Clinical Characterization of Ulcerative Colitis in Patients with Primary Sclerosing Cholangitis

Objectives

The clinical/colonoscopic features of ulcerative colitis (UC) associated with primary sclerosing cholangitis (PSC), the prognostic impact of UC, and the utility of UC screening in PSC patients are unknown. We characterized UC associated with PSC and assessed UC's impact on the prognosis of PSC and the importance of colonoscopic UC screening in PSC patients.

Methods

We retrospectively analyzed the cases of 77 patients treated for PSC at a single center (April 2000–July 2019). We reviewed the clinical/colonoscopic profiles of the concurrent UC patients and compared the clinical profiles, survival, and primary causes of death between the patients with/without UC (n = 35/n = 42). The details of all patients' colonoscopies were reviewed.

Results

The concurrent UC group: 17 men, 18 women, diagnosed with PSC at the mean (SD) age of 36 (17) years; 21 patients (60%) had no UC symptoms. Colonoscopy revealed pancolitis in all patients, predominantly affecting the right-sided colon in 30 patients (86%). Lesions were scattered. Backwash ileitis (n = 13, 37%) and rectal sparing (n = 18, 51%) were observed. Most patients had mild UC; some had moderate or more severe UC (median Ulcerative Colitis Endoscopic Index of Severity (UCEIS) score 2; range, 1–5). Ludwig's stage determined by liver biopsy did not correlate with the Mayo endoscopic score for UC. The patients with UC were diagnosed with PSC at a significantly younger age than those without UC (mean (SD), 36 [17] years vs. 55 [19] years, p < 0.0001) and had a significantly higher 5-year survival rate (97.1% vs. 70.5%, p = 0.0028). UC was detected in 19 of 34 asymptomatic patients (56%) who underwent colonoscopy screening.

Conclusions

Our cohort's clinical/colonoscopic features of UC associated with PSC are more moderate or severe UC than previous cases. The coexistence of UC might affect the prognosis of PSC. In this regard, colonoscopy in PSC patients is an important examination for determining prognosis. There is also asymptomatic UC in patients with PSC. In this regard, screening for colonoscopy in PSC patients is essential. When a diagnosis of PSC is made, immediate colonoscopy is a priority with UC complications in mind.

Proteomics-Informed Identification of Luminal Targets For In Situ Diagnosis of Inflammatory Bowel Disease

Inflammatory bowel disease (IBD) is a chronic condition resulting in impaired intestinal homeostasis. Current practices for diagnosis of IBD are challenged by invasive, demanding procedures. We hypothesized that proteomics analysis could provide a powerful tool for identifying clinical biomarkers for non-invasive IBD diagnosis. Here, the global intestinal proteomes from commonly used in vitro and in vivo models of IBD were analyzed to identify apical and luminal proteins that can be targeted by orally delivered diagnostic agents. Global proteomics analysis revealed upregulated plasma membrane proteins in intestinal segments of proximal- and distal colon from dextran sulfate sodium-treated mice and also in inflamed human intestinal Caco-2 cells pretreated with pro-inflammatory agents. The upregulated colon proteins in mice were compared to the proteome of the healthy ileum, to ensure targeting of diagnostic agents to the inflamed colon. Promising target proteins for future investigations of non-invasive diagnosis of IBD were found in both systems and included Tgm2/TGM2, Icam1/ICAM1, Ceacam1/CEACAM1, and Anxa1/ANXA1. Ultimately, these findings will guide the selection of appropriate antibodies for surface functionalization of imaging agents aimed to target inflammatory biomarkers in situ.

Circulating α4β7+ Memory T Cells in Pediatric IBD Patients Express a Polyclonal T Cell Receptor Repertoire

Background

The integrin α4β7 is highly expressed on activated T cells and is thought to direct homing of lymphocytes to the intestine. Since ulcerative colitis (UC) and Crohn's disease (CD) are characterized by mucosal oligoclonal T cells' expansion, we aimed to assess whether similar repertoire features are identified in circulating gut-specific memory T cells.

Methods

Memory CD3⁺ T cells were isolated from blood samples of control subjects and patients with active UC or CD and then FACS-sorted into α4β7⁺ and α4β7^- populations. DNA was extracted from each subset and subjected to next-generation sequencing of the TCRβ. Different repertoire characteristics were compared between α4β7⁺ and α4β7^- subsets for each subject, and between groups.

Results

The percentages of memory T cells and α4β7⁺ cells were comparable between groups. α4β7⁺ memory T cells displayed a polyclonal distribution, in control subjects and in UC or CD patients, with similar indices of diversity. Strikingly, the clonal overlap between α4β7⁺ and α4β7^- T cells for each subject in all three groups was high, ranging between 20%-50%. We were unable to identify shared T cell clones that were specific to one of the groups.

Conclusion

α4β7⁺ memory T cells exhibited a polyclonal repertoire in both control subjects and patients with active inflammatory bowel disease, with high rates of overlap with α4β7^- memory T cells. Our study, along with additional recent reports, may suggest that the suppression of intestinal inflammation by vedolizumab is independent of the drug's effect on T cell migration to the gut.

Etrolizumab for the Treatment of Ulcerative Colitis and Crohn's Disease: An Overview of the Phase 3 Clinical Program

Introduction

Etrolizumab is a next-generation anti-integrin with dual action that targets two pathways of inflammation in the gut. A robust phase 3 clinical program in ulcerative colitis (UC) and Crohn’s disease is ongoing and will evaluate the efficacy and safety of etrolizumab in well-defined patient populations in rigorous trials that include direct head-to-head comparisons against approved anti-tumor necrosis factor alpha agents (anti-TNF). The etrolizumab phase 3 clinical program consists of six randomized controlled trials (RCTs; UC: HIBISCUS I and II, GARDENIA, LAUREL, HICKORY; Crohn’s disease: BERGAMOT) and two open-label extension trials (OLEs; UC: COTTONWOOD; Crohn’s disease: JUNIPER) evaluating patients with moderately to severely active UC or Crohn’s disease.

Methods

In the UC RCTs, patients are randomly assigned according to each protocol to receive etrolizumab, adalimumab, infliximab, or placebo. In BERGAMOT, patients are randomly assigned to receive etrolizumab 105 mg, etrolizumab 210 mg, or placebo. The primary outcomes for the UC RCTs are Mayo Clinic score-based clinical response, remission, and clinical remission; for BERGAMOT, the co-primary outcomes are clinical remission (based on abdominal pain and stool frequency) and endoscopic improvement (based on the Simple Endoscopic Score for Crohn’s disease). The OLEs will primarily assess long-term efficacy and safety. Secondary and exploratory endpoints include endoscopy, histology, quality of life, and biomarkers at various timepoints.

Discussion

The etrolizumab phase 3 clinical program is the largest and most comprehensive in inflammatory bowel disease, enrolling more than 3000 patients. The program explores both induction and maintenance regimens. HIBISCUS I and II and GARDENIA are among the first head-to-head trials in UC against an anti-TNF and are the first registrational trials making that comparison. This program will also help address unanswered clinical questions on evaluation of treatment effects and treatment selection across a range of patients with varying treatment histories using an extensive repository of patient samples and data.

Trial Registration

ClinicalTrials.gov: HIBISCUS I (NCT02163759), HIBISCUS II (NCT02171429), GARDENIA (NCT02136069), LAUREL (NCT02165215), HICKORY (NCT02100696), COTTONWOOD (NCT02118584), BERGAMOT (NCT02394028), JUNIPER (NCT02403323).

Novel candidate drugs in anti-tumor necrosis factor refractory Crohn's diseases: in silico study for drug repositioning

Biologicals like anti-tumor necrosis factor (TNF) therapy for Crohn's disease (CD) are safe and effective but there is a significant rate of primary and secondary nonresponse in the patients. In this study, we applied a computational approach to discover novel drug therapies for anti-TNF refractory CD in silico. We use a transcriptome dataset (GSE100833) for the anti-TNF refractory CD patients from NCBI GEO. After co-expression analysis, we specifically investigated the extent of protein-protein interactions among genes in clusters based on a protein-protein interaction database, STRING. Pathway analysis was performed using the clEnrich function based on KEGG gene sets. Co-expressed genes in cluster 1, 2, 3, 4, up or down-regulated genes and all differentially expressed genes are highly connected. Among them, cluster 1, which is highly enriched for chemokine signaling, also showed enrichment for cytokine-cytokine receptor interaction and identifies several drugs including cyclosporin with known efficacy in CD. Vorinostat, histone deacetylase inhibitors, and piperlongumine, which is known to have inhibitory effect on activity of NF-κB, were also identified. Some alkaloids were also selected as potential therapeutic drugs. These finding suggest that they might serve as a novel therapeutic option for anti-TNF refractory CD and support the use of public molecular data and computational approaches to discover novel therapeutic options for CD.

Factors Influencing Drug Disposition of Monoclonal Antibodies in Inflammatory Bowel Disease: Implications for Personalized Medicine

Monoclonal antibody (mAb) therapies have revolutionized the treatment of several chronic inflammatory diseases, including the inflammatory bowel diseases (IBD), Crohn's disease, and ulcerative colitis. While efficacious, responses to these therapies vary considerably from patient to patient, due in part to inter- and intra-individual variability in pharmacokinetics (PK) and drug exposure. The concept of personalized medicine to monitor drug exposure and to adjust dosing in individual patients is consequently gaining acceptance as a powerful tool to optimize mAb therapy for improved outcomes in IBD. This review provides a brief overview of the different mAbs currently approved or in development for the treatment of IBD, including their presumed mechanisms of action and PK properties. Specifically described are (1) the factors known to affect mAb PK and drug exposure in patients with IBD, (2) the value of population PK/pharmacodynamic (PD) modeling to identify and understand the influence of these factors on drug exposure and effect, and (3) the clinical evidence for the potential of therapeutic drug monitoring (TDM) to improve IBD outcomes in response to mAb-based therapy. Incorporation of PK/PD parameters into clinical decision support tools has the potential to guide therapeutic decision making and aid implementation of personalized medicine strategies in patients with IBD.

Vedolizumab and etrolizumab for ulcerative colitis: twins or simple cousins?

Introduction: Vedolizumab is a monoclonal antibody that selectively blocks α4β7 integrin and has already been approved for use in patients with moderate-to-severe ulcerative colitis both as first and second line. Etrolizumab is a monoclonal antibody still being tested, which acts with a dual mechanism by selectively inhibiting both α4β7 and αEβ7 integrins.Areas covered: This review provides an overview of the literature data of vedolizumab and etrolizumab, in order to define their role in the treatment of patients with moderate-to-severe ulcerative colitis.Expert opinion: Etrolizumab and vedolizumab block the α4β7 integrin with a similar action mechanism. However, the inhibition of αEβ7 integrin by etrolizumab distinguishes the two anti-integrins making them 'cousin' drugs. Phase 3 clinical trials are needed to confirm the promising etrolizumab's efficacy data and to resolve any doubts about its safety, allowing a clearer comparison with vedolizumab.

Analysis of Flagellin-Specific Adaptive Immunity Reveals Links to Dysbiosis in Patients With Inflammatory Bowel Disease

BACKGROUND & AIMS

Bacterial flagellin is an important antigen in inflammatory bowel disease, but the role of flagellin-specific CD4⁺ T cells in disease pathogenesis remains unclear. Also unknown is how changes in intestinal microbiome intersect with those in microbiota-specific CD4⁺ T cells. We aimed to quantify and characterize flagellin-specific CD4⁺ T cells in Crohn's disease (CD) and ulcerative colitis (UC) patients and study their relationship with intestinal microbiome diversity.

METHODS

Blood was collected from 3 cohorts that included CD patients, UC patients, and healthy controls. Flow cytometry analyzed CD4⁺ T cells specific for Lachnospiraceae-derived A4-Fla2 and Escherichia coli H18 FliC flagellins, or control vaccine antigens. Serum antiflagellin IgG and IgA antibodies were detected by enzyme-linked immunosorbent assay and stool samples were collected and subjected to 16S ribosomal DNA sequencing.

RESULTS

Compared with healthy controls, CD and UC patients had lower frequencies of vaccine-antigen-specific CD4⁺ T cells and, as a proportion of vaccine-specific cells, higher frequencies of flagellin-specific CD4⁺ T cells. The proportion of flagellin-specific CD4⁺ T cells that were CXCR3^negCCR4⁺CCR6⁺ Th17 cells was reduced in CD and UC patients, with increased proportions of CD39⁺, PD-1⁺, and integrin β7⁺ cells. Microbiome analysis showed differentially abundant bacterial species in patient groups that correlated with immune responses to flagellin.

CONCLUSIONS

Both CD and UC patients have relative increases in the proportion of circulating Fla2-specific CD4⁺ T cells, which may be associated with changes in the intestinal microbiome. Evidence that the phenotype of these cells strongly correlate with disease severity provides insight into the potential roles of flagellin-specific CD4⁺ T cells in inflammatory bowel disease.

Keep calm: the intestinal barrier at the interface of peace and war

Epithelial barriers have to constantly cope with both harmless and harmful stimuli. The epithelial barrier therefore serves as a dynamic and not static wall to safeguard its proper physiological function while ensuring protection. This is achieved through multiple defence mechanisms involving various cell types - epithelial and non-epithelial - that work in an integrated manner to build protective barriers at mucosal sites. Damage may nevertheless occur, due to pathogens, physical insults or dysregulated immune responses, which trigger a physiologic acute or a pathologic chronic inflammatory cascade. Inflammation is often viewed as a pathological condition, particularly due to the increasing prevalence of chronic inflammatory (intestinal) diseases. However, inflammation is also necessary for wound healing. The aetiology of chronic inflammatory diseases is incompletely understood and identification of the underlying mechanisms would reveal additional therapeutic approaches. Resolution is an active host response to end ongoing inflammation but its relevance is under-appreciated. Currently, most therapies aim at dampening inflammation at damaged mucosal sites, yet these approaches do not efficiently shut down the inflammation process nor repair the epithelial barrier. Therefore, future treatment strategies should also promote the resolution phase. Yet, the task of repairing the barrier can be an arduous endeavour considering its multiple integrated layers of defence - which is advantageous for damage prevention but becomes challenging to repair at multiple levels. In this review, using the intestines as a model epithelial organ and barrier paradigm, we describe the consequences of chronic inflammation and highlight the importance of the mucosae to engage resolving processes to restore epithelial barrier integrity and function. We further discuss the contribution of pre-mRNA alternative splicing to barrier integrity and intestinal homeostasis. Following discussions on current open questions and challenges, we propose a model in which resolution of inflammation represents a key mechanism for the restoration of epithelial integrity and function.

The Compromised Mucosal Immune System of β7 Integrin-Deficient Mice Has Only Minor Effects on the Fecal Microbiota in Homeostasis

The gastrointestinal tract is an ideal habitat for diverse bacterial species that reside in a homeostatic balance with local tissue and significantly contribute to host health. Negative shifts in gut microbiota profiles, also known as dysbiosis, may be implicated in the development of chronic disorders such as inflammatory bowel diseases (IBD). Adhesion molecule-dependent recruitment of immune cells to the gut is an important step in IBD pathogenesis. The adhesion molecule β7 integrin contributes to the development of the gut-associated lymphoid tissue (GALT), intestinal immune cell homing, and immune responses and is known to promote intestinal inflammation. Although many studies underlined the role of the gut microbiota in shaping the mucosal immune system, studies on the influence of the host immune system on the microbiota are rare, especially in homeostasis. We addressed this question via comparative 16S rRNA gene amplicon analysis of fecal microbial communities from wild-type and β7 integrin-deficient mice, the latter being characterized by a compromised GALT. Besides subtle changes in relative abundances of Muribaculaceae spp. and unknown members of the families Ruminococcaceae and Lachnospiraceae, there was altogether no major difference in microbiota profiles in β7 integrin-deficient mice vs. wild-type littermates. This indicates that, in conditions of homeostasis, there is only a minor influence of the host immune system on the fecal microbiota in our mouse model, stressing the potential importance of pathological factors for dysbiosis development.

Vedolizumab versus Adalimumab for Moderate-to-Severe Ulcerative Colitis

BACKGROUND

Biologic therapies are widely used in patients with ulcerative colitis. Head-to-head trials of these therapies in patients with inflammatory bowel disease are lacking.

METHODS

In a phase 3b, double-blind, double-dummy, randomized trial conducted at 245 centers in 34 countries, we compared vedolizumab with adalimumab in adults with moderately to severely active ulcerative colitis to determine whether vedolizumab was superior. Previous exposure to a tumor necrosis factor inhibitor other than adalimumab was allowed in up to 25% of patients. The patients were assigned to receive infusions of 300 mg of vedolizumab on day 1 and at weeks 2, 6, 14, 22, 30, 38, and 46 (plus injections of placebo) or subcutaneous injections of 40 mg of adalimumab, with a total dose of 160 mg at week 1, 80 mg at week 2, and 40 mg every 2 weeks thereafter until week 50 (plus infusions of placebo). Dose escalation was not permitted in either group. The primary outcome was clinical remission at week 52 (defined as a total score of ≤2 on the Mayo scale [range, 0 to 12, with higher scores indicating more severe disease] and no subscore >1 [range, 0 to 3] on any of the four Mayo scale components). To control for type I error, efficacy outcomes were analyzed with a hierarchical testing procedure, with the variables in the following order: clinical remission, endoscopic improvement (subscore of 0 to 1 on the Mayo endoscopic component), and corticosteroid-free remission at week 52.

RESULTS

A total of 769 patients underwent randomization and received at least one dose of vedolizumab (383 patients) or adalimumab (386 patients). At week 52, clinical remission was observed in a higher percentage of patients in the vedolizumab group than in the adalimumab group (31.3% vs. 22.5%; difference, 8.8 percentage points; 95% confidence interval [CI], 2.5 to 15.0; P = 0.006), as was endoscopic improvement (39.7% vs. 27.7%; difference, 11.9 percentage points; 95% CI, 5.3 to 18.5; P<0.001). Corticosteroid-free clinical remission occurred in 12.6% of the patients in the vedolizumab group and in 21.8% in the adalimumab group (difference, -9.3 percentage points; 95% CI, -18.9 to 0.4). Exposure-adjusted incidence rates of infection were 23.4 and 34.6 events per 100 patient-years with vedolizumab and adalimumab, respectively, and the corresponding rates for serious infection were 1.6 and 2.2 events per 100 patient-years.

CONCLUSIONS

In this trial involving patients with moderately to severely active ulcerative colitis, vedolizumab was superior to adalimumab with respect to achievement of clinical remission and endoscopic improvement, but not corticosteroid-free clinical remission. (Funded by Takeda; VARSITY ClinicalTrials.gov number, NCT02497469; EudraCT number, 2015-000939-33.).

Myxozoan Adhesion and Virulence: Ceratonova shasta on the Move

Motility factors are fundamental for parasite invasion, migration, proliferation and immune evasion and thus can influence parasitic disease pathogenesis and virulence. Salmonid enteronecrosis is caused by a myxozoan (Phylum Cnidarian) parasite, Ceratonova shasta. Three parasite genotypes (0, I, II) occur, with varying degrees of virulence in its host, making it a good model for examining the role of motility in virulence. We compare C. shasta cell motility between genotypes and describe how the cellular protrusions interact with the host. We support these observations with motility gene expression analyses. C. shasta stages can move by single or combined used of filopodia, lamellipodia and blebs, with different behaviors such as static adhesion, crawling or blebbing, some previously unobserved in myxozoans. C. shasta stages showed high flexibility of switching between different morphotypes, suggesting a high capacity to adapt to their microenvironment. Exposure to fibronectin showed that C. shasta stages have extraordinary adhesive affinities to glycoprotein components of the extracellular matrix (ECM). When comparing C. shasta genotypes 0 (low virulence, no mortality) and IIR (high virulence, high mortality) infections in rainbow trout, major differences were observed with regard to their migration to the target organ, gene expression patterns and proliferation rate in the host. IIR is characterized by rapid multiplication and fast amoeboid bleb-based migration to the gut, where adhesion (mediated by integrin-β and talin), ECM disruption and virulent systemic dispersion of the parasite causes massive pathology. Genotype 0 is characterized by low proliferation rates, slow directional and early adhesive migration and localized, non-destructive development in the gut. We conclude that parasite adhesion drives virulence in C. shasta and that effectors, such as integrins, reveal themselves as attractive therapeutic targets in a group of parasites for which no effective treatments are known.

Transcriptome analysis of the effects of Hericium erinaceus polysaccharide on the lymphocyte homing in Muscovy duck reovirus-infected ducklings

Hericium erinaceus polysaccharide (HEP) is a bioactive substance present in the fruiting bodies of H. erinaceus. Previously we have shown that HEP can repair the intestinal injury caused by Muscovy duck reovirus (MDRV) infection in Muscovy ducklings. To examine the effect of HEP on intestine mucosal MDRV immunity and explore its possible mechanisms, an MDRV contact-infection model in the Muscovy ducklings was established. Transcriptome sequencing analysis was then performed to investigate the mechanism of action of HEP on intestine mucosal MDRV immunity. During the infection, the expression levels of genes involved in cellular activities (protein translation and binding, cytokine interaction, and adhesion molecules activities) in the infected ducklings were increased. The expression levels of adhesion molecules (α4β7, LFA-1) and chemotaxis cytokine receptors (CCR7, CCR9, and CCR10) were also significantly upregulated. Following HEP treatment, cellular activities and cytokines upregulated to various degrees play crucial roles in the immune defenses and antiviral activities of Muscovy ducklings. ELISA analysis results were consistent with the results of the transcriptome analysis. Overall, our results provide a basis for further studying the underlying mechanisms of HEP in regulating mucosal immunity and for the clinical application of HEP in controlling MDRV infection in the Muscovy duck industry.