Early-onset Crohn's disease and autoimmunity associated with a variant in CTLA-4

CTLA4 Alteration and Neurologic Manifestations: A New Family with Large Phenotypic Variability and Literature Review

Cytotoxic-T-lymphocyte-antigen-4 (CTLA-4), a member of the immunoglobulin superfamily, is an essential negative regulator of immune responses that is constitutively expressed on both regulatory (Treg) and activated T cells. To date, heterozygous germline variants in CTLA4, leading to haploinsufficiency, have been associated with several immunological disorders, including hypogammaglobulinemia, multi-organ autoimmunity, lymphoproliferative disorders, and enlarged lymphoid organs. Indeed, CTLA4 carriers display highly heterogeneous clinical manifestations with a phenotypic spectrum ranging from asymptomatic carrier status to fatal autoimmunity. Here, we describe a family with autoimmune phenotypes (Hashimoto thyroiditis, psoriasiform dermatitis, celiac disease/inflammatory bowel disease, and rheumatoid arthritis), segregating across three different generations due to a recurrent missense variant [c.436G>A, p.(Gly146Arg)] in the CTLA4 gene. Interestingly, the proband showed prominent neurological manifestations, including seizures, hydrocephalus, and demyelination, which are less frequently reported in individuals with pathogenic variants in CTLA4. A detailed literature review of neurologic features that have been reported so far in CTLA4 carriers is also provided.

Spleen volume in relation to ulcerative colitis and Crohn's disease: a Mendelian randomization study

Prior research has established the significance of spleen volume (SV) in the pathogenesis and advancement of ulcerative colitis (UC) and Crohn's disease (CD). Nevertheless, these investigations are predominantly observational, thereby leaving their causal associations ambiguous. Moreover, the breadth of existing research is constrained by various uncontrollable variables in clinical settings. This study aims to deduce the causal link between SV and the susceptibility to UC and CD through a genetic perspective. The objective of this study was to investigate the genetic association between SV and inflammatory bowel disease (IBD) risk using Mendelian randomization (MR) analysis. Single nucleotide polymorphisms (SNPs) associated with SV were used as instrumental variables. Genetic associations for UC and CD were extracted from the International Inflammatory Bowel Disease Genetics Consortium (IIBDGC), the FinnGen study, and other publicly available genome-wide association studies (GWAS). Methods such as inverse variance weighted, Bayesian weighted Mendelian randomization (BWMR), contamination mixture (ConMix), along with sensitivity analyses and the Steiger test were used in the study. A meta-analysis was conducted to synthesize the results. The study found that genetically predicted SV was associated with an increased risk of UC in the IIBDGC dataset (OR = 1. 223, 95% CI: 1. 055-1. 417, P = 0. 008), FinnGen (OR = 1. 169, 95% CI: 1. 003-1. 363, P = 0. 045), the GWAS study by Sakaue S (OR = 1. 188, 95% CI: 1. 008-1. 399, P = 0. 040), and in the meta-analysis (OR = 1. 115, 95% CI: 1. 014-1. 227, P = 0. 025). Similarly, genetically predicted SV was associated with an increased risk of CD in the IIBDGC dataset (OR = 1. 235, 95% CI: 1. 026-1. 488, P = 0. 026), FinnGen (OR = 1. 308, 95% CI: 1. 026-1. 667, P = 0. 030), the GWAS study by Zorina-Lichtenwalter K (OR = 1. 316, 95% CI: 1. 037-1. 670, P = 0. 024), and in the meta-analysis (OR = 1. 272, 95% CI: 1. 133-1. 428, P < 0. 001). According to the meta-analysis results, for each standard unit increase in SV, the risk of developing UC increases by 11. 5%, and the risk of developing CD increases by 27. 2%. This study presents findings that suggest a positive causal association between SV and the onset of IBD.

Characteristics of the Kelch domain containing (KLHDC) subfamily and relationships with diseases

The Kelch protein superfamily is an evolutionary conserved family containing 63 alternate protein coding members. The superfamily is split into three subfamilies: Kelch like (KLHL), Kelch-repeat and bric-a-bracs (BTB) domain containing (KBTBD) and Kelch domain containing protein (KLHDC). The KLHDC subfamily is one of the smallest within the Kelch superfamily, containing 10 primary members. There is little known about the structures and functions of the subfamily; however, they are thought to be involved in several cellular and molecular processes. Recently, there have been significant structural and biochemical advances for KLHDC2, which has aided our understanding of other KLHDC family members. Furthermore, small molecules directly targeting KLHDC2 have been identified, which act as tools for targeted protein degradation. This review utilises this information, in conjunction with a thorough exploration of the structural aspects and potential biological functions to summarise the relationship between KLHDCs and human disease.

Developmental drugs for sarcoidosis

Sarcoidosis is a multi-organ granulomatous inflammatory disease of unknown etiology. Over 50% of patients will require treatment at some point in their disease and 10%-30% will develop a chronic progressive disease with pulmonary fibrosis leading to significant morbidity and mortality. Recently published guidelines recommend immunosuppressive therapy for sarcoidosis patients at risk of increased disease-related morbidity and mortality, and in whom disease has negatively impacted quality of life. Prednisone the currently recommended first line therapy is associated with significant toxicity however none of the other guideline recommended steroid sparing therapy is approved by regulatory agencies for use in sarcoidosis, and data in support of their use is weak. For patients with severe refractory disease requiring prolonged therapy, treatment options are limited. The need for expanding treatment options in sarcoidosis has been emphasized. Well conducted large, randomized trials evaluating currently available therapeutic options as well as novel pathways for targeting disease are necessary to better guide treatment decisions. These trials will not be without significant challenges. Sarcoidosis is a rare disease with heterogenous presentation and variable progression and clinical outcome. There are no universally agreed upon biomarkers of disease activity and measurement of outcomes is confounded by the need to balance patient centric measures and objective measures of disease activity. Our paper provides an update on developmental drugs in sarcoidosis and outlines several novel pathways that may be targeted for future drug development. Currently available trials are highlighted and ongoing challenges to drug development and clinical trial design are briefly discussed.

Evaluating the Safety of Immune Checkpoint Inhibitors and Combination Therapies in the Management of Brain Metastases: A Comprehensive Review

Brain metastases (BM) are a frequent and severe complication in patients with lung cancer, breast cancer, and melanoma. Immune checkpoint inhibitors (ICIs) have become a crucial treatment option for BM, whether used alone or in combination with chemotherapy and stereotactic radiosurgery (SRS). However, ICIs are associated with immune-related adverse events (irAEs) that can affect multiple organ systems, complicating their use in BM patients. This review examines the mechanisms of irAEs and their effects on different organs and evaluates the safety of ICIs across various treatment strategies for BM. Our analysis indicates that ICIs significantly improve survival and disease control in BM patients, but their use increases the risk of irAEs, including dermatologic, gastrointestinal, endocrine, pulmonary, and neurologic toxicities. Neurotoxic events, particularly treatment-associated brain necrosis (TABN) and encephalitis, are more common in BM patients. While the overall incidence of irAEs is similar between patients with and without BM, the neurotoxicity risk is higher in the BM population. Combining ICIs with chemotherapy and SRS enhances efficacy but also heightens the risk of adverse events across organ systems. ICIs offer substantial benefits for BM patients but require careful management to mitigate the risks of irAEs. Close patient monitoring, individualized treatment protocols, and prompt intervention are essential for optimizing the outcomes. Future research should focus on refining combination strategies and improving the management of irAEs, particularly neurotoxicity, to maximize therapeutic benefits for BM patients.

CTLA-4 expressing innate lymphoid cells modulate mucosal homeostasis in a microbiota dependent manner

The maintenance of intestinal homeostasis is a fundamental process critical for organismal integrity. Sitting at the interface of the gut microbiome and mucosal immunity, adaptive and innate lymphoid populations regulate the balance between commensal micro-organisms and pathogens. Checkpoint inhibitors, particularly those targeting the CTLA-4 pathway, disrupt this fine balance and can lead to inflammatory bowel disease and immune checkpoint colitis. Here, we show that CTLA-4 is expressed by innate lymphoid cells and that its expression is regulated by ILC subset-specific cytokine cues in a microbiota-dependent manner. Genetic deletion or antibody blockade of CTLA-4 in multiple in vivo models of colitis demonstrates that this pathway plays a key role in intestinal homeostasis. Lastly, we have found that this observation is conserved in human IBD. We propose that this population of CTLA-4-positive ILC may serve as an important target for the treatment of idiopathic and iatrogenic intestinal inflammation.

Modern View on Very Early Onset and Early Onset Inflammatory Bowel Diseases in Children

Nowadays, an urgent problem of pediatric gastroenterology is the study of inflammatory bowel diseases with very early onset (VEO-IBD), which have unique genetic, clinical, immunological, morphological, and laboratory sings. Early VEO-IBD is usually considered as monogenic disease, especially in combination with congenital immune defects, which leads to difficulties in diagnosis and management this pathology. Despite this, systematization of information about this group of nosological forms of IBD is practically not carried out. This article presents a review of the available information on etiological factors, course variants, and therapeutic options for VEO-IBD.

Leukocyte dysfunction and reduced CTLA-4 expression are associated with perianal Crohn's disease

Although perianal Crohn's disease (PCD) is highly associated with the exacerbated inflammation, the molecular basis and immunological signature that distinguish patients who present a history of perianal lesions are still unclear. This paper aims to define immunological characteristics related to PCD. In this cross-sectional observational study, we enrolled 20 healthy controls and 39 CD patients. Blood samples were obtained for the detection of plasma cytokines and lipopolysaccharides (LPS). Peripheral blood mononuclear cells (PBMCs) were phenotyped by flow cytometry. Leukocytes were stimulated with LPS or anti-CD3/anti-CD28 antibodies. Our results show that CD patients had augmented plasma interleukin (IL)-6 and LPS. However, their PBMC was characterized by decreased IL-6 production, while patients with a history of PCD produced higher IL-6, IL-8, and interferon-γ, along with decreased tumor necrosis factor alpha (TNF). CD patients had augmented FoxP3 and cytotoxic T lymphocyte-associated antigen 4 (CTLA-4) regulatory markers, though the PCD subjects presented a significant reduction in CTLA-4 expression. CTLA-4 as well as IL-6 and TNF responses were able to distinguish the PCD patients from those who did not present perianal complications. In conclusion, IL-6, TNF, and CTLA-4 exhibit a distinct expression pattern in CD patients with a history of PCD, regardless of disease activity. These findings clarify some mechanisms involved in the development of the perianal manifestations and may have a great impact on the disease management.

Position statement on the management of the immune checkpoint inhibitor-induced colitis via multidisciplinary modified Delphi consensus

INTRODUCTION

The use of immune checkpoint inhibitors (ICIs) in cancer immunotherapy has shown increased overall survival in a wide range of cancer types with the associated risk of developing severe immune-mediated adverse events, commonly involving the gastrointestinal tract.

AIM

The aim of this position statement is to provide an updated practice advice to the gastroenterologists and oncologists on the diagnosis and management of ICI-induced gastrointestinal toxicity.

METHODOLOGY

The evidence reviewed in this paper includes a comprehensive search strategy of English language publications. Consensus was reached using a three-round modified Delphi methodology and approved by the members of the Belgian Inflammatory Bowel Disease Research and Development Group (BIRD), Belgian Society of Medical Oncology (BSMO), Belgian group of Digestive Oncology (BGDO), and Belgian Respiratory Society (BeRS).

CONCLUSIONS

The management of ICI-induced colitis requires an early multidisciplinary approach. A broad initial assessment is necessary (clinical presentation, laboratory markers, endoscopic and histologic examination) to confirm the diagnosis. Criteria for hospitalisation, management of ICIs, and initial endoscopic assessment are proposed. Even if corticosteroids are still considered the first-line therapy, biologics are recommended as an escalation therapy and as early treatment in patients with high-risk endoscopic findings.

Pharmacologic Management of Monogenic and Very Early Onset Inflammatory Bowel Diseases

Inflammatory bowel disease (IBD) is treated with a variety of immunomodulating and immunosuppressive therapies; however, for the majority of cases, these therapies are not targeted for specific disease phenotypes. Monogenic IBD with causative genetic defect is the exception and represents a disease cohort where precision therapeutics can be applied. With the advent of rapid genetic sequencing platforms, these monogenic immunodeficiencies that cause inflammatory bowel disease are increasingly being identified. This subpopulation of IBD called very early onset inflammatory bowel disease (VEO-IBD) is defined by an age of onset of less than six years of age. Twenty percent of VEO-IBDs have an identifiable monogenic defect. The culprit genes are often involved in pro-inflammatory immune pathways, which represent potential avenues for targeted pharmacologic treatments. This review will provide an overview of the current state of disease-specific targeted therapies, as well as empiric treatment for undifferentiated causes of VEO-IBD.

Germline genetic variation and predicting immune checkpoint inhibitor induced toxicity

Immune checkpoint inhibitor (ICI) therapy has revolutionised the treatment of various cancer types. ICIs reinstate T-cell function to elicit an anti-cancer immune response. The resulting immune response can however have off-target effects which manifest as autoimmune type serious immune-related adverse events (irAE) in ~10-55% of patients treated. It is currently challenging to predict both who will experience irAEs and to what severity. Identification of patients at high risk of serious irAE would revolutionise patient care. While the pathogenesis driving irAE development is still unclear, host genetic factors are proposed to be key determinants of these events. This review presents current evidence supporting the role of the host genome in determining risk of irAE. We summarise the spectrum and timing of irAEs following treatment with ICIs and describe currently reported germline genetic variation associated with expression of immuno-modulatory factors within the cancer immunity cycle, development of autoimmune disease and irAE occurrence. We propose that germline genetic determinants of host immune function and autoimmune diseases could also explain risk of irAE development. We also endorse genome-wide association studies of patients being treated with ICIs to identify genetic variants that can be used in polygenic risk scores to predict risk of irAE.

Localization and movement of Tregs in gastrointestinal tract: a systematic review

BACKGROUND

The intestine is rich in food-derived and microbe-derived antigens. Regulatory T cells (Tregs) are an essential T-cell population that prevents systemic autoimmune diseases and inhibits inflammation by encountering antigens. Previously, it was reported that the functional loss of Tregs induces systemic inflammation, including inflammatory bowel disease and graft-versus-host disease in human and murine models. However, there is a dearth of information about how Tregs localize in different tissues and suppress effector cells.

MAIN BODY

The development of Tregs and their molecular mechanism in the digestive tract have been elucidated earlier using murine genetic models, infectious models, and human samples. Tregs suppress immune and other nonimmune cells through direct effect and cytokine production. The recent development of in vivo imaging technology allows us to visualize how Tregs localize and move in the settings of inflammation and homeostasis. This is important because, according to a recent report, Treg characterization and function are regulated by their location. Tregs located in the proximal intestine and its draining lymph nodes induce tolerance against food antigens, and those located in the distal intestine suppress the inflammation induced by microbial antigens. Taken together, various Tregs are induced in a location-specific manner in the gastrointestinal tract and influence the homeostasis of the gut.

CONCLUSION

In this review, we summarize how Tregs are induced in the digestive tract and the application of in vivo Treg imaging to elucidate immune homeostasis in the digestive tract.

Therapeutic gene editing of T cells to correct CTLA-4 insufficiency

Heterozygous mutations in CTLA-4 result in an inborn error of immunity with an autoimmune and frequently severe clinical phenotype. Autologous T cell gene therapy may offer a cure without the immunological complications of allogeneic hematopoietic stem cell transplantation. Here, we designed a homology-directed repair (HDR) gene editing strategy that inserts the CTLA-4 cDNA into the first intron of the CTLA-4 genomic locus in primary human T cells. This resulted in regulated expression of CTLA-4 in CD4+ T cells, and functional studies demonstrated CD80 and CD86 transendocytosis. Gene editing of T cells isolated from three patients with CTLA-4 insufficiency also restored CTLA-4 protein expression and rescued transendocytosis of CD80 and CD86 in vitro. Last, gene-corrected T cells from CTLA-4-/- mice engrafted and prevented lymphoproliferation in an in vivo murine model of CTLA-4 insufficiency. These results demonstrate the feasibility of a therapeutic approach using T cell gene therapy for CTLA-4 insufficiency.

The ABACHAI clinical trial protocol: Safety and efficacy of abatacept (s.c.) in patients with CTLA-4 insufficiency or LRBA deficiency: A non controlled phase 2 clinical trial

Background

Cytotoxic T-lymphocyte-associated protein 4 (CTLA-4) insufficiency and lipopolysaccharide-responsive and beige-like anchor protein (LRBA) deficiency are both complex immune dysregulation syndromes with an underlying regulatory T cell dysfunction due to the lack of CTLA-4 protein. As anticipated, the clinical phenotypes of CTLA-4 insufficiency and LRBA deficiency are similar. Main manifestations include hypogammaglobulinemia, lymphoproliferation, autoimmune cytopenia, immune-mediated respiratory, gastrointestinal, neurological, and skin involvement, which can be severe and disabling. The rationale of this clinical trial is to improve clinical outcomes of affected patients by substituting the deficient CTLA-4 by administration of CTLA4-Ig (abatacept) as a causative personalized treatment.

Objectives

Our objective is to assess the safety and efficacy of abatacept for patients with CTLA-4 insufficiency or LRBA deficiency. The study will also investigate how treatment with abatacept affects the patients’ quality of life.

Methods

/Design: ABACHAI is a phase IIa prospective, non-randomized, open-label, single arm multi-center trial. Altogether 20 adult patients will be treated with abatacept 125 mg s.c. on a weekly basis for 12 months, including (1) patients already pretreated with abatacept, and (2) patients not pretreated, starting with abatacept therapy at the baseline study visit. For the evaluation of drug safety infection control during the trial, for efficacy, the CHAI-Morbidity Score will be used.

Trial registration

The trial is registered in the German Clinical Trials Register (Deutsches Register Klinischer Studien, DRKS) with the identity number DRKS00017736, registered: 6 July 2020, https://www.drks.de/drks_web/navigate.do?navigationId=trial.HTML&TRIAL_ID=DRKS00017736.

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Clinical trial for safety and efficacy of abatacept in CTLA-4 or LRBA deficiency.

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Substitution of CTLA4-deficiency by abatacept, a causative treatment approach.

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Primary endpoint: no. of episodes of failed infection control under trial treatment.

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Development of disease severity score.

Gene Edited T Cell Therapies for Inborn Errors of Immunity

Inborn errors of immunity (IEIs) are a heterogeneous group of inherited disorders of the immune system. Many IEIs have a severe clinical phenotype that results in progressive morbidity and premature mortality. Over 450 IEIs have been described and the incidence of all IEIs is 1/1,000–10,000 people. Current treatment options are unsatisfactory for many IEIs. Allogeneic haematopoietic stem cell transplantation (alloHSCT) is curative but requires the availability of a suitable donor and carries a risk of graft failure, graft rejection and graft-versus-host disease (GvHD). Autologous gene therapy (GT) offers a cure whilst abrogating the immunological complications of alloHSCT. Gene editing (GE) technologies allow the precise modification of an organisms’ DNA at a base-pair level. In the context of genetic disease, this enables correction of genetic defects whilst preserving the endogenous gene control machinery. Gene editing technologies have the potential to transform the treatment landscape of IEIs. In contrast to gene addition techniques, gene editing using the CRISPR system repairs or replaces the mutation in the DNA. Many IEIs are limited to the lymphoid compartment and may be amenable to T cell correction alone (rather than haematopoietic stem cells). T cell Gene editing has the advantages of higher editing efficiencies, reduced risk of deleterious off-target edits in terminally differentiated cells and less toxic conditioning required for engraftment of lymphocytes. Although most T cells lack the self-renewing property of HSCs, a population of T cells, the T stem cell memory compartment has long-term multipotent and self-renewal capacity. Gene edited T cell therapies for IEIs are currently in development and may offer a less-toxic curative therapy to patients affected by certain IEIs. In this review, we discuss the history of T cell gene therapy, developments in T cell gene editing cellular therapies before detailing exciting pre-clinical studies that demonstrate gene editing T cell therapies as a proof-of-concept for several IEIs.

Co-Inhibitory Molecules – Their Role in Health and Autoimmunity; Highlighted by Immune Related Adverse Events

Immune checkpoint receptors are key players in regulating the immune response. They are responsible for both generating an immune response sufficient to kill invading pathogens, balancing the same response, and protecting against tissue destruction or the development of autoimmune events. The central role of the co-inhibitory receptors also referred to as inhibitory immune checkpoints, including PD-1 and CTLA-4 has become especially evident with the cancer treatments targeting these receptors. Blocking these pathways enhances the immune activity, resulting in both an increased chance of cancer clearance, at the same time induction of immune-related adverse events (irAE). Some of these irAE progress into actual autoimmune diseases with autoantibodies and symptoms, undistinguished from the naturally occurring diseases. This review will take advantage of the lessons learned from immune checkpoint blockade and relate this knowledge to our understanding of the same pathways in naturally occurring autoimmune diseases, mainly focusing on rheumatic diseases.

Autoimmunity in Primary Immunodeficiencies (PID)

Primary immunodeficiency (PID) may impact any component of the immune system. The number of PID and immune dysregulation disorders is growing steadily with advancing genetic detection methods. These expansive recognition methods have changed the way we characterize PID. While PID were once characterized by their susceptibility to infection, the increase in genetic analysis has elucidated the intertwined relationship between PID and non-infectious manifestations including autoimmunity. The defects permitting opportunistic infections to take hold may also lead the way to the development of autoimmune disease. In some cases, it is the non-infectious complications that may be the presenting sign of PID autoimmune diseases, such as autoimmune cytopenia, enteropathy, endocrinopathies, and arthritis among others, have been reported in PID. While autoimmunity may occur with any PID, this review will look at certain immunodeficiencies most often associated with autoimmunity, as well as their diagnosis and management strategies.

Early DNA methylation changes in children developing beta cell autoimmunity at a young age

AIMS/HYPOTHESIS

Type 1 diabetes is a chronic autoimmune disease of complex aetiology, including a potential role for epigenetic regulation. Previous epigenomic studies focused mainly on clinically diagnosed individuals. The aim of the study was to assess early DNA methylation changes associated with type 1 diabetes already before the diagnosis or even before the appearance of autoantibodies.

METHODS

Reduced representation bisulphite sequencing (RRBS) was applied to study DNA methylation in purified CD4+ T cell, CD8+ T cell and CD4-CD8- cell fractions of 226 peripheral blood mononuclear cell samples longitudinally collected from seven type 1 diabetes-specific autoantibody-positive individuals and control individuals matched for age, sex, HLA risk and place of birth. We also explored correlations between DNA methylation and gene expression using RNA sequencing data from the same samples. Technical validation of RRBS results was performed using pyrosequencing.

RESULTS

We identified 79, 56 and 45 differentially methylated regions in CD4+ T cells, CD8+ T cells and CD4-CD8- cell fractions, respectively, between type 1 diabetes-specific autoantibody-positive individuals and control participants. The analysis of pre-seroconversion samples identified DNA methylation signatures at the very early stage of disease, including differential methylation at the promoter of IRF5 in CD4+ T cells. Further, we validated RRBS results using pyrosequencing at the following CpG sites: chr19:18118304 in the promoter of ARRDC2; chr21:47307815 in the intron of PCBP3; and chr14:81128398 in the intergenic region near TRAF3 in CD4+ T cells.

CONCLUSIONS/INTERPRETATION

These preliminary results provide novel insights into cell type-specific differential epigenetic regulation of genes, which may contribute to type 1 diabetes pathogenesis at the very early stage of disease development. Should these findings be validated, they may serve as a potential signature useful for disease prediction and management.

Linking Genetic Diagnosis to Therapeutic Approach in Very Early Onset Inflammatory Bowel Disease: Pharmacologic Considerations

Very early onset inflammatory bowel disease (VEO-IBD) is diagnosed in children < 6 years of age, and in rare cases may be due to an identifiable monogenic cause. Recent advances in genetic testing have allowed for more accurate diagnosis, with as many as 100 genes now known to be associated with monogenic inflammatory bowel disease. These genes are involved in many immune pathways and thus may represent potential avenues for targeted precision medicine with pharmacologic treatments aimed at these. This review describes the broad classifications of monogenic disorders known to cause VEO-IBD, as well as empiric and disease-specific medical therapies. These include immune-modulating or immunosuppressant medications, nutritional therapy, surgery, and hematopoietic stem cell transplantation. We aim to provide an overview of the current state of targeted therapy for VEO-IBD.

A Pattern-based Pathology Approach to Very Early-onset Inflammatory Bowel Disease: Thinking Beyond Crohn Disease and Ulcerative Colitis

Very early-onset inflammatory bowel disease (VEO-IBD), IBD diagnosed in children younger than 6 years old, is phenotypically and genetically distinct from older onset IBD. Monogenic and digenic causative defects, particularly in primary immunodeficiency and intestinal epithelial barrier genes, have been identified in a subset of patients with VEO-IBD allowing for targeted therapies and improved outcomes. However, these findings are the minority, thus strategies to correctly diagnose patients, including identification of specific histopathologic findings with correlating clinical and laboratory features may provide critical and necessary insight into mechanisms of disease pathogenesis and subsequent therapeutic options. In this article, we review the pathologic findings seen in patients with VEO-IBD and outline a pattern-based approach to diagnosis using examples from primary immunodeficiencies with gastrointestinal manifestations.

Gastric cancer, inflammatory bowel disease and polyautoimmunity in a 17-year-old boy: CTLA-4 deficiency successfully treated with Abatacept

Gut involvement is frequent in immunologic disorders, especially with inflammatory manifestations but also with cancer. In the last years, advances in functional and genetic testing have improved the diagnostic and therapeutic approach to immune dysregulation syndromes. CTLA-4 deficiency is a rare disease with variable phenotype, ranging from absence of symptoms to severe multisystem manifestations and complications. We describe a rare case of CTLA-4 deficiency in a boy with gastric cancer, very early onset inflammatory bowel disease and polyautoimmunity, the second-ever reported in the literature with the same characteristics. A 17-year-old boy was referred to Bambino Gesù Children's Hospital of Rome, a tertiary care center, for a gastric mass and a long-term history of very early onset inflammatory bowel disease, diabetes mellitus type 1, polyarthritis and psoriasis. Histology of gastric biopsies revealed the presence of neoplastic signet ring cells. Imaging staging showed localized cancer; therefore, the patient underwent subtotal gastrectomy with termino-lateral gastro-jejunal anastomosis. Immunological work up and genetic testing by next-generation sequencing panels for primary immunodeficiencies led to the diagnosis of CTLA-4 deficiency. Good disease control was obtained with the administration of Abatacept. The patient experienced an asymptomatic SARS-CoV-2 infection without any concern. Eighteen months after treatment initiation, the patient is alive and well. Immunologic and genetic testing, such as next-generation sequencing, should always be part of the diagnostic approach to patients with complex immune dysregulation syndrome, severe clinical course, poor response to treatments or cancer. The early recognition of the monogenic disease is the key for disease management and targeted therapy.

Risk factors for immune-related adverse events: what have we learned and what lies ahead?

Immune checkpoint inhibitors (ICIs) have heralded the advent of a new era in oncology by holding the promise of prolonged survival in severe and otherwise treatment-refractory advanced cancers. However, the remarkable antitumor efficacy of these agents is overshadowed by their potential for inducing autoimmune toxic effects, collectively termed immune-related adverse events (irAEs). These autoimmune adverse effects are often difficult to predict, possibly permanent, and occasionally fatal. Hence, the identification of risk factors for irAEs is urgently needed to allow for prompt therapeutic intervention. This review discusses the potential mechanisms through which irAEs arise and summarizes the existing evidence regarding risk factors associated with the occurrence of irAEs. In particular, we examined available data regarding the effect of a series of clinicopathological and demographic factors on the risk of irAEs.

Expanding Contributions of Monogenic Very Early Onset Inflammatory Bowel Disease

Currently over 70 genes known to be causative in very early onset inflammatory bowel disease (VEOIBD) have been identified. In the current issue of Inflammatory Bowel Diseases, 2 articles describing monogenetic forms of VEOIBD are highlighted. One describes a patient with life-threatening VEOIBD and a mutation in ITGA6, illustrating the importance of the epithelial barrier in maintaining mucosal homeostasis. The other describes the presentation and management of 10 patients with VEOIBD secondary to damaging mutations in MVK, resulting in mevalonate kinase deficiency. Though most monogenic causes of VEOIBD remain "private," understanding the different categories of pathways affected in children with VEOIBD is critical and has already resulted in invaluable insight in the management of patients with VEOIBD and may hold strong implications for the care of IBD overall.

Artificial intelligence enables comprehensive genome interpretation and nomination of candidate diagnoses for rare genetic diseases

BACKGROUND

Clinical interpretation of genetic variants in the context of the patient's phenotype is becoming the largest component of cost and time expenditure for genome-based diagnosis of rare genetic diseases. Artificial intelligence (AI) holds promise to greatly simplify and speed genome interpretation by integrating predictive methods with the growing knowledge of genetic disease. Here we assess the diagnostic performance of Fabric GEM, a new, AI-based, clinical decision support tool for expediting genome interpretation.

METHODS

We benchmarked GEM in a retrospective cohort of 119 probands, mostly NICU infants, diagnosed with rare genetic diseases, who received whole-genome or whole-exome sequencing (WGS, WES). We replicated our analyses in a separate cohort of 60 cases collected from five academic medical centers. For comparison, we also analyzed these cases with current state-of-the-art variant prioritization tools. Included in the comparisons were trio, duo, and singleton cases. Variants underpinning diagnoses spanned diverse modes of inheritance and types, including structural variants (SVs). Patient phenotypes were extracted from clinical notes by two means: manually and using an automated clinical natural language processing (CNLP) tool. Finally, 14 previously unsolved cases were reanalyzed.

RESULTS

GEM ranked over 90% of the causal genes among the top or second candidate and prioritized for review a median of 3 candidate genes per case, using either manually curated or CNLP-derived phenotype descriptions. Ranking of trios and duos was unchanged when analyzed as singletons. In 17 of 20 cases with diagnostic SVs, GEM identified the causal SVs as the top candidate and in 19/20 within the top five, irrespective of whether SV calls were provided or inferred ab initio by GEM using its own internal SV detection algorithm. GEM showed similar performance in absence of parental genotypes. Analysis of 14 previously unsolved cases resulted in a novel finding for one case, candidates ultimately not advanced upon manual review for 3 cases, and no new findings for 10 cases.

CONCLUSIONS

GEM enabled diagnostic interpretation inclusive of all variant types through automated nomination of a very short list of candidate genes and disorders for final review and reporting. In combination with deep phenotyping by CNLP, GEM enables substantial automation of genetic disease diagnosis, potentially decreasing cost and expediting case review.

Intestinal Regulatory T Cells as Specialized Tissue-Restricted Immune Cells in Intestinal Immune Homeostasis and Disease

FOXP3+ regulatory T cells (Treg cells) are a specialized population of CD4+ T cells that restrict immune activation and are essential to prevent systemic autoimmunity. In the intestine, the major function of Treg cells is to regulate inflammation as shown by a wide array of mechanistic studies in mice. While Treg cells originating from the thymus can home to the intestine, the majority of Treg cells residing in the intestine are induced from FOXP3neg conventional CD4+ T cells to elicit tolerogenic responses to microbiota and food antigens. This process largely takes place in the gut draining lymph nodes via interaction with antigen-presenting cells that convert circulating naïve T cells into Treg cells. Notably, dysregulation of Treg cells leads to a number of chronic inflammatory disorders, including inflammatory bowel disease. Thus, understanding intestinal Treg cell biology in settings of inflammation and homeostasis has the potential to improve therapeutic options for patients with inflammatory bowel disease. Here, the induction, maintenance, trafficking, and function of intestinal Treg cells is reviewed in the context of intestinal inflammation and inflammatory bowel disease. In this review we propose intestinal Treg cells do not compose fixed Treg cell subsets, but rather (like T helper cells), are plastic and can adopt different programs depending on microenvironmental cues.

CTLA-4 Haploinsufficiency Presenting as Extensive Enteropathy in a Patient With Very Early Onset Inflammatory Bowel Disease

Patients with very early onset inflammatory bowel disease (VEO-IBD) have a higher incidence of monogenic disease compared to older age groups. Age, alone, is a strong predictor for monogenic disease. We discuss a case of VEO-IBD in which the patient presented with severe and refractory enteropathy, leading to diagnosis of CTLA-4 haploinsufficiency. Genetic workup showed de novo heterozygous deletions of the CTLA-4 and ICOS genes. This case was unique, as the patient did not have the other manifestations commonly present with the disease. We advocate for early and routine genetic workup of VEO-IBD, as patients with monogenic IBD have high morbidity and mortality, if inadequately treated. Our patient did not respond to conventional treatment modalities and required targeted treatment with Abatacept, a CTLA-4 agonist.

Checkpoint Inhibitor Colitis Shows Drug-Specific Differences in Immune Cell Reaction That Overlap With Inflammatory Bowel Disease and Predict Response to Colitis Therapy

OBJECTIVES

Checkpoint inhibitor (CPI)-associated colitis can limit therapy and has resemblance to inflammatory bowel disease (IBD). Studies exploring mechanistic similarities between these colitides are limited, yet therapeutic targets for either disorder could emerge from shared pathophysiology.

METHODS

The morphology and inflammatory content of colonic biopsy specimens from anti-CTLA-4 and anti-PD-1/PD-L1 antibody-treated patients with CPI colitis were compared with initial biopsy specimens from patients with IBD. Predictors of the need for infliximab were sought in CPI patients.

RESULTS

Biopsy specimens from CPI patients showed significantly lower chronicity scores and similar activity scores compared with patients with IBD. Anti-CTLA-4 and IBD groups showed equivalent CD8, CD4, PD-1, and PD-L1 expression, while FoxP3 scores were lower and CD68 scores were higher in anti-CTLA-4 compared with IBD biopsy specimens. Anti-PD-1/PD-L1 group had lower scores for CD8, CD4, and PD-1 and equivalent scores for FoxP3, PD-L1, and CD68 compared with IBD. Anti-CTLA-4 biopsy specimens had higher scores for CD8, PD-1, PD-L1, and CD68 than anti-PD-1/PD-L1 biopsy specimens. CD8/FoxP3 ratios and CD68 scores were higher among CPI patients requiring infliximab therapy for colitis compared with those responding to steroids.

CONCLUSIONS

The proinflammatory immune phenotype of anti-CTLA-4-associated colitis has significant overlap with IBD. CD8/FoxP3 ratios may predict therapeutic response in CPI-associated colitis.

Endocrine Disorders in Autoimmune Rheumatological Diseases: A Focus on Thyroid Autoimmune Diseases and on the Effects of Chronic Glucocorticoid Treatment

Autoimmune rheumatological diseases’ incidence and prevalence have risen over the last decades and they are becoming increasingly important worldwide. Thyroid autoimmune diseases share with them an imbalance in the immune system that lead to a pro-inflammatory environment. Usually this is the result of a multi-factorial process. In fact, it includes not only a possible genetic predisposition, but also environmental causes like microbiota dysbiosis, diet rich in processed foods, exposure to toxicants and infections. However, many aspects are currently under study. This paper aims to examine the factors that participate in the developing of rheumatological and thyroid autoimmune diseases. Moreover, as glucocorticoids still represent a leading treatment for systemic autoimmune rheumatological diseases, our secondary aim is to summarize the main effects of glucocorticoids treatment focusing on iatrogenic Cushing’s syndrome and glucocorticoids’ withdrawal syndrome.

Therapeutic options for CTLA-4 insufficiency

BACKGROUND

Heterozygous germline mutations in cytotoxic T lymphocyte-associated antigen-4 (CTLA4) impair the immunomodulatory function of regulatory T cells. Affected individuals are prone to life-threatening autoimmune and lymphoproliferative complications. A number of therapeutic options are currently being used with variable effectiveness.

OBJECTIVE

Our aim was to characterize the responsiveness of patients with CTLA-4 insufficiency to specific therapies and provide recommendations for the diagnostic workup and therapy at an organ-specific level.

METHODS

Clinical features, laboratory findings, and response to treatment were reviewed retrospectively in an international cohort of 173 carriers of CTLA4 mutation. Patients were followed between 2014 and 2020 for a total of 2624 months from diagnosis. Clinical manifestations were grouped on the basis of organ-specific involvement. Medication use and response were recorded and evaluated.

RESULTS

Among the 173 CTLA4 mutation carriers, 123 (71%) had been treated for immune complications. Abatacept, rituximab, sirolimus, and corticosteroids ameliorated disease severity, especially in cases of cytopenias and lymphocytic organ infiltration of the gut, lungs, and central nervous system. Immunoglobulin replacement was effective in prevention of infection. Only 4 of 16 patients (25%) with cytopenia who underwent splenectomy had a sustained clinical response. Cure was achieved with stem cell transplantation in 13 of 18 patients (72%). As a result of the aforementioned methods, organ-specific treatment pathways were developed.

CONCLUSION

Systemic immunosuppressants and abatacept may provide partial control but require ongoing administration. Allogeneic hematopoietic stem cell transplantation offers a possible cure for patients with CTLA-4 insufficiency.

Curcumin and Its Modified Formulations on Inflammatory Bowel Disease (IBD): The Story So Far and Future Outlook

Inflammatory bowel disease (IBD) is a chronic relapsing and remitting inflammatory disorder of the small intestine and colon. IBD includes ulcerative colitis (UC) and Crohn's disease (CD), and it is a major factor for the development of colon cancer, referred to as colitis-associated cancer (CAC). The current treatment of IBD mainly includes the use of synthetic drugs and monoclonal antibodies. However, these drugs have side effects over long-term use, and the high relapse rate restricts their application. In the recent past, many studies had witnessed a surge in applying plant-derived products to manage various diseases, including IBD. Curcumin is a bioactive component derived from a rhizome of turmeric (Curcuma longa). Numerous in vitro and in vivo studies show that curcumin may interact with many cellular targets (NF-κB, JAKs/STATs, MAPKs, TNF-γ, IL-6, PPARγ, and TRPV1) and effectively reduce the progression of IBD with promising results. Thus, curcumin is a potential therapeutic agent for patients with IBD once it significantly decreases clinical relapse in patients with quiescent IBD. This review aims to summarize recent advances and provide a comprehensive picture of curcumin's effectiveness in IBD and offer our view on future research on curcumin in IBD treatment.

Biologic and advanced immunomodulating therapeutic options for sarcoidosis: a clinical update

Introduction: Sarcoidosis is a multi-organ disease with a wide range of clinical manifestations and outcomes. A quarter of sarcoidosis patients require long-term treatment for chronic disease. In this group, corticosteroids and cytotoxic agents be insufficient to control diseaseAreas covered: Several biologic agents have been studied for treatment of chronic pulmonary and extra-pulmonary disease. A review of the available literature was performed searching PubMed and an expert opinion regarding specific therapy was developed.Expert opinion: These agents have the potential of treating patients who have progressive disease. Many of these agents have different mechanisms of action, response rates, and toxicity profiles.

Intestinal Regulatory T Cells

Mucosal surfaces are distinctive sites exposed to environmental, dietary, and microbial antigens. Particularly in the gut, the host continuously actively adapts via complex interactions between the microbiota and dietary compounds and immune and other tissue cells. Regulatory T cells (Tregs) are critical for tuning the intestinal immune response to self- and non-self-antigens in the intestine. Its importance in intestinal homeostasis is illustrated by the onset of overt inflammation caused by deficiency in Treg generation, function, or stability in the gut. A substantial imbalance in Tregs has been observed in intestinal tissue during pathogenic conditions, when a tightly regulated and equilibrated system becomes dysregulated and leads to unimpeded and chronic immune responses. In this chapter, we compile and critically discuss the current knowledge on the key factors that promote Treg-mediated tolerance in the gut, such as those involved in intestinal Treg differentiation, specificity and suppressive function, and their immunophenotype during health and disease. We also discuss the current state of knowledge on Treg dysregulation in human intestine during pathological states such as inflammatory bowel disease (IBD), necrotizing enterocolitis (NEC), graft-versus-host disease (GVHD), and colorectal cancer (CRC), and how that knowledge is guiding development of Treg-targeted therapies to treat or prevent intestinal disorders.

Safety and efficacy of abatacept in patients with treatment-resistant SARCoidosis (ABASARC) - protocol for a multi-center, single-arm phase IIa trial

INTRODUCTION

Sarcoidosis is a granulomatous systemic disease that becomes chronic in approximately one third of affected patients resulting in quality of life and functional impairment. Immunosuppressive drugs other than steroids represent alternative therapeutic options, but side effects like liver and bone marrow toxicity or increased susceptibility to infections limit their use. Pathophysiological studies in sarcoidosis patients demonstrate altered regulatory T-cell functions with a reduced expression of CTLA-4 (CD152) and prolonged inflammation. Therefore, interfering with CTLA-4 using abatacept might be a therapeutic option in sarcoidosis similar to rheumatoid arthritis therapy.

METHODS/DESIGN

This is a multicenter prospective open-labeled single arm phase II study addressing the safety of abatacept in sarcoidosis patients. 30 patients with chronic sarcoidosis requiring immunosuppressive therapy beyond 5 mg prednisolone equivalent will be treated with abatacept in combination with corticosteroids for one year in two centers.The primary endpoint is the number and characterization of severe infectious complications under treatment with abatacept.Secondary endpoints are the rate of all infections, patient-related outcomes (assessed by questionnaires), lung function and immunological parameters including alveolar inflammation assessed by bronchoaveolar lavage.

DISCUSSION

This is the first trial of abatacept in patients with sarcoidosis. It is hypothesized that administration of abatacept is safe in patients with chronic sarcoidosis and can limit ongoing inflammation. Patients' wellbeing is assessed by established questionnaires. Immunological work-up will highlight the effect of abatacept on inflammatory pathways in sarcoidosis.

TRIAL REGISTRATION

The trial has been registered at the German Clinical Trial Registry (Deutsches Register Klinischer Studien, DRKS) with the identity number DRKS00011660.

Comprehensive Targeted Sequencing Identifies Monogenic Disorders in Patients With Early-onset Refractory Diarrhea

OBJECTIVES

Causes of early-onset refractory diarrhea include exudative diarrhea associated with very early-onset inflammatory bowel diseases, osmotic or secretory diarrhea, and protein-losing enteropathy. Monogenic disorders are included in these diseases, yet a comprehensive genetic analysis has not been fully established.

METHODS

We established targeted gene panels covering all responsible genes for early-onset diarrhea. In total, 108 patients from 15 institutions were enrolled in this study. We collected clinical data from all patients. Seventy-three patients with exudative diarrhea, 4 with osmotic or secretory diarrhea and 8 with protein-losing enteropathy were subjected to genetic analysis.

RESULTS

A total of 15 out of the 108 enrolled patients (13.9%) were identified as monogenic. We identified 1 patient with RELA, 2 with TNFAIP3, 1 with CTLA4, 1 with SLCO2A1, 4 with XIAP, 3 with IL10RA, 1 with HPS1, 1 with FOXP3, and 1 with CYBB gene mutations. We also identified 1 patient with NFKB2 and 1 with TERT mutations from the gene panel for primary immunodeficiency syndromes. The patient with refractory diarrhea caused by heterozygous truncated RelA protein expression is the first case identified worldwide, and functional analysis revealed that the mutation affected nuclear factor kappa B signaling. Genotypes were significantly associated with the clinical and pathological findings in each patient.

CONCLUSIONS

We identified variable monogenic diseases in the patients and found that genes responsible for primary immunodeficiency diseases were frequently involved in molecular pathogenesis. Comprehensive genetic analysis was useful for accurate molecular diagnosis, understanding of underlying pathogenesis, and selecting the optimal treatment for patients with early-onset refractory diarrhea.An infographic for this article is available at: http://links.lww.com/MPG/B853.

Multinational Association of Supportive Care in Cancer (MASCC) 2020 clinical practice recommendations for the management of severe gastrointestinal and hepatic toxicities from checkpoint inhibitors

Immune-related adverse events (IrAEs) affecting the gastrointestinal (GI) tract and liver are among the most frequent and most severe inflammatory toxicities from contemporary immunotherapy. Inflammation of the colon and or small intestines (entero)colitis is the single most common GI IrAE and is an important cause of delay of discontinuation of immunotherapy. The severity of these GI IrAEs can range from manageable with symptomatic treatment alone to life-threatening complications, including perforation and liver failure. The frequency and severity of GI IrAEs is dependent on the specific immunotherapy given, with cytotoxic T lymphocyte antigen (CTLA)-4 blockade more likely to induce severe GI IrAEs than blockade of either programmed cell death protein 1 (PD-1) or PD-1 ligand (PD-L1), and combination therapy showing the highest rate of GI IrAEs, particularly in the liver. To date, we have minimal prospective data on the appropriate diagnosis and management of GI IrAEs, and recommendations are based largely on retrospective data and expert opinion. Although clinical diagnoses of GI IrAEs are common, biopsy is the gold standard for diagnosis of both immunotherapy-induced enterocolitis and hepatitis and can play an important role in excluding competing, though less common, diagnoses and ensuring optimal management. GI IrAEs typically respond to high-dose corticosteroids, though a significant fraction of patients requires secondary immune suppression. For colitis, both TNF-α blockade with infliximab and integrin inhibition with vedolizumab have proved highly effective in corticosteroid-refractory cases. Detailed guidelines have been published for the management of low-grade GI IrAEs. In the setting of more severe toxicities, involvement of a GI specialist is generally recommended. The purpose of this review is to survey the available literature and provide management recommendations focused on the GI specialist.

Molecular Pathways of Colon Inflammation Induced by Cancer Immunotherapy

Checkpoint blockade with antibodies specific for the PD-1 and CTLA-4 inhibitory receptors can induce durable responses in a wide range of human cancers. However, the immunological mechanisms responsible for severe inflammatory side effects remain poorly understood. Here we report a comprehensive single-cell analysis of immune cell populations in colitis, a common and severe side effect of checkpoint blockade. We observed a striking accumulation of CD8 T cells with highly cytotoxic and proliferative states and no evidence of regulatory T cell depletion. T cell receptor (TCR) sequence analysis demonstrated that a substantial fraction of colitis-associated CD8 T cells originated from tissue-resident populations, explaining the frequently early onset of colitis symptoms following treatment initiation. Our analysis also identified cytokines, chemokines, and surface receptors that could serve as therapeutic targets for colitis and potentially other inflammatory side effects of checkpoint blockade.

Very Early Onset Inflammatory Bowel Disease: A Clinical Approach With a Focus on the Role of Genetics and Underlying Immune Deficiencies

Very early onset inflammatory bowel disease (VEO-IBD) is defined as IBD presenting before 6 years of age. When compared with IBD diagnosed in older children, VEO-IBD has some distinct characteristics such as a higher likelihood of an underlying monogenic etiology or primary immune deficiency. In addition, patients with VEO-IBD have a higher incidence of inflammatory bowel disease unclassified (IBD-U) as compared with older-onset IBD. In some populations, VEO-IBD represents the age group with the fastest growing incidence of IBD. There are contradicting reports on whether VEO-IBD is more resistant to conventional medical interventions. There is a strong need for ongoing research in the field of VEO-IBD to provide optimized management of these complex patients. Here, we provide an approach to diagnosis and management of patients with VEO-IBD. These recommendations are based on expert opinion from members of the VEO-IBD Consortium (www.VEOIBD.org). We highlight the importance of monogenic etiologies, underlying immune deficiencies, and provide a comprehensive description of monogenic etiologies identified to date that are responsible for VEO-IBD.

Safety of Immune Checkpoint Inhibitors in Patients With Pre-Existing Inflammatory Bowel Disease and Microscopic Colitis

PURPOSE

Enterocolitis is among the leading adverse events associated with immune checkpoint inhibitors (ICIs). There are limited retrospective data regarding the safety of ICIs in patients with inflammatory bowel disease (IBD; ulcerative colitis, Crohn's disease) because they have been generally excluded from clinical trials testing ICIs. Furthermore, there are no outcome data available in patients with microscopic colitis, a leading cause of chronic diarrhea. We aimed to study the safety of ICIs in patients with cancer with pre-existing IBD or microscopic colitis.

METHODS

We retrospectively reviewed the records of patients with cancer treated at our institution who received at least 1 dose of either a programmed cell death-1 (PD-1)/ PD-1 ligand inhibitor, cytotoxic T-lymphocyte-associated antigen 4 inhibitor, or both between 2011 and 2018. We identified patients with pre-existing IBD or microscopic colitis.

RESULTS

Of 548 patients with solid tumor treated with an ICI, we identified 25 with pre-existing colitis (21 IBD; 4 microscopic colitis). An enterocolitis flare occurred in 7 patients (28%): 3 of 4 patients (75%) with microscopic colitis and 4 of 21 (19%) with IBD. All were treated with systemic corticosteroids, 2 required an anti-tumor necrosis factor agent, and one required an anti-integrin agent and colectomy for treatment of refractory colitis. ICI therapy was discontinued in all patients who experienced an enterocolitis flare.

CONCLUSION

In our cohort, exacerbation of enterocolitis occurred in a notable percentage of patients with IBD and a majority of patients with microscopic colitis, leading to discontinuation of ICIs. Although these data suggest that patients with cancer with pre-existing IBD/microscopic colitis may be treated with ICIs, additional studies are needed to validate our results.

New therapeutic perspectives to manage refractory immune checkpoint-related toxicities

Immune checkpoint inhibitors are reshaping the prognosis of many cancer and are progressively becoming the standard of care in the treatment of many tumour types. Immunotherapy is bringing new hope to patients, but also a whole new spectrum of toxicities for healthcare practitioners to manage. Oncologists and specialists involved in the pluridisciplinary management of patients with cancer are increasingly confronted with the therapeutic challenge of treating patients with severe and refractory immune-related adverse events. In this Personal View, we summarise the therapeutic strategies that have been used to manage such toxicities resulting from immune checkpoint inhibitor treatment. On the basis of current knowledge about their pathogenesis, we discuss the use of new biological and non-biological immunosuppressive drugs to treat severe and steroid refractory immune-related adverse events. Depending on the immune infiltrate type that is predominant, we propose a treatment algorithm for personalised management that goes beyond typical corticosteroid use. We propose a so-called shut-off strategy that aims at inhibiting key inflammatory components involved in the pathophysiological processes of immune-related adverse events, and limits potential adverse effects of drug immunosuppression on tumour response. This approach develops on current guidelines and challenges the step-by-step increase approach to drug immunosuppression.

Gastrointestinal and Hepatic Complications of Immunotherapy: Current Management and Future Perspectives

PURPOSE OF REVIEW

Checkpoint inhibitor (CPI) immunotherapy has transformed the treatment of multiple cancers over the past decade, leading to durable remissions, but also to severe inflammatory toxicities. These toxicities, termed immune-related adverse events (irAEs), can affect any organ system in the body, but commonly induce inflammation in barrier organs. Gastrointestinal (GI) and hepatic irAEs are among the most frequent and most severe from contemporary immunotherapies, with inflammation in the colon and or small intestines (entero)colitis as the single most common GI irAE. The aim of this review is to describe the evidence supporting our current understanding of CPI enterocolitis and hepatitis, as well as the management of these entities.

RECENT FINDINGS

Although most patients who develop enterocolitis recover without long-term GI sequelae, enterocolitis is still an important reason for treatment discontinuation, which, in patients with metastatic cancer, can be a life-threatening outcome. At present, we have almost no prospective, randomized data regarding the management of CPI enterocolitis, and current management algorithms are based on expert opinion and small retrospective studies with a high likelihood of bias. Retrospective studies have defined colonic ulceration as a predictor of colitis responsiveness to corticosteroids, and have defined microscopic colitis as a subtype of CPI enterocolitis with a distinct treatment response. Corticosteroids appear to be effective for 60-70% of patients with CPI enterocolitis, with about a third of patients requiring escalation to a biologic agent such as infliximab or vedolizumab. Yet proper sequencing of these treatments to minimize risk and maximize treatment benefit has not been established, and we do not know how treatment of colitis influences cancer outcomes. CPI enterocolitis and hepatitis are important causes of treatment interruption and discontinue, and significant morbidity in patients undergoing immunotherapy. As guidelines for diagnosis and management rely heavily on expert opinion, we have an urgent need for randomized and prospective trials that use both colitis and cancer outcomes to determine optimal management strategies.

North American Society for Pediatric Gastroenterology, Hepatology, and Nutrition Position Paper on the Evaluation and Management for Patients With Very Early-onset Inflammatory Bowel Disease

The rate of pediatric inflammatory bowel disease (IBD) has been increasing over the last decade and this increase has occurred most rapidly in the youngest children diagnosed <6 years, known as very early-onset inflammatory bowel disease (VEO-IBD). These children can present with more extensive and severe disease than older children and adults. The contribution of host genetics in this population is underscored by the young age of onset and the distinct, aggressive phenotype. In fact, monogenic defects, often involving primary immunodeficiency genes, have been identified in children with VEO-IBD and have led to targeted and life-saving therapy. This position paper will discuss the phenotype of VEO-IBD and outline the approach and evaluation for these children and what factors should trigger concern for an underlying immunodeficiency. We will then review the immunological assays and genetic studies that can facilitate the identification of the underlying diagnosis in patients with VEO-IBD and how this evaluation may lead to directed therapies. The position paper will also aid the pediatric gastroenterologist in recognizing when a patient should be referred to a center specializing in the care of these patients. These guidelines are intended for pediatricians, allied health professionals caring for children, pediatric gastroenterologists, pediatric pathologists, and immunologists.

Immune Checkpoint Inhibitor Therapy in Patients With Preexisting Inflammatory Bowel Disease

PURPOSE

The risk of immune checkpoint inhibitor therapy-related GI adverse events in patients with cancer and inflammatory bowel disease (IBD) has not been well described. We characterized GI adverse events in patients with underlying IBD who received immune checkpoint inhibitors.

PATIENTS AND METHODS

We performed a multicenter, retrospective study of patients with documented IBD who received immune checkpoint inhibitor therapy between January 2010 and February 2019. Backward selection and multivariate logistic regression were conducted to assess risk of GI adverse events.

RESULTS

Of the 102 included patients, 17 received therapy targeting cytotoxic T-lymphocyte antigen-4, and 85 received monotherapy targeting programmed cell death 1 or its ligand. Half of the patients had Crohn's disease, and half had ulcerative colitis. The median time from last active IBD episode to immunotherapy initiation was 5 years (interquartile range, 3-12 years). Forty-three patients were not receiving treatment of IBD. GI adverse events occurred in 42 patients (41%) after a median of 62 days (interquartile range, 33-123 days), a rate higher than that among similar patients without underlying IBD who were treated at centers participating in the study (11%; P < .001). GI events among patients with IBD included grade 3 or 4 diarrhea in 21 patients (21%). Four patients experienced colonic perforation, 2 of whom required surgery. No GI adverse event-related deaths were recorded. Anti-cytotoxic T-lymphocyte antigen-4 therapy was associated with increased risk of GI adverse events on univariable but not multivariable analysis (odds ratio, 3.19; 95% CI, 1.8 to 9.48; P = .037; and odds ratio, 4.72; 95% CI, 0.95 to 23.53; P = .058, respectively).

CONCLUSION

Preexisting IBD increases the risk of severe GI adverse events in patients treated with immune checkpoint inhibitors.

CTLA-4: From mechanism to autoimmune therapy

CD28 and CTLA-4 are both important stimulatory receptors for the regulation of T cell activation. Because receptors share common ligands, B7.1 and B7.2, the expression and biological function of CTLA-4 is important for the negative regulation of T cell responses. Therefore, elimination of CTLA-4 can result in the breakdown of immune tolerance and the development of several diseases such as autoimmunity. Inhibitory signals of CTLA-4 suppress T cell responses and protect against autoimmune diseases in many ways. In this review, we summarize the structure, expression and signaling pathway of CTLA-4. We also highlight how CTLA-4 defends against potentially self-reactive T cells. Finally, we discuss how the CTLA-4 regulates a number of autoimmune diseases that indicate manipulation of this inhibitory molecule is a promise as a strategy for the immunotherapy of autoimmune diseases.

Time to dissect the autoimmune etiology of cancer antibody immunotherapy

Immunotherapy has transformed the treatment landscape for a wide range of human cancers. Immune checkpoint inhibitors (ICIs), monoclonal antibodies that block the immune-regulatory "checkpoint" receptors CTLA-4, PD-1, or its ligand PD-L1, can produce durable responses in some patients. However, coupled with their success, these treatments commonly evoke a wide range of immune-related adverse events (irAEs) that can affect any organ system and can be treatment-limiting and life-threatening, such as diabetic ketoacidosis, which appears to be more frequent than initially described. The majority of irAEs from checkpoint blockade involve either barrier tissues (e.g., gastrointestinal mucosa or skin) or endocrine organs, although any organ system can be affected. Often, irAEs resemble spontaneous autoimmune diseases, such as inflammatory bowel disease, autoimmune thyroid disease, type 1 diabetes mellitus (T1D), and autoimmune pancreatitis. Yet whether similar molecular or pathologic mechanisms underlie these apparent autoimmune adverse events and classical autoimmune diseases is presently unknown. Interestingly, evidence links HLA alleles associated with high risk for autoimmune disease with ICI-induced T1D and colitis. Understanding the genetic risks and immunologic mechanisms driving ICI-mediated inflammatory toxicities may not only identify therapeutic targets useful for managing irAEs, but may also provide new insights into the pathoetiology and treatment of autoimmune diseases.

Vitamin D Increases CTLA-4 Gene Expression in Patients with Mild to Moderate Ulcerative Colitis

BACKGROUND

Ulcerative colitis (UC) is a chronic inflammatory disorder of the large intestine. Cytotoxic T-lymphocyte-associated protein 4 (CTLA-4) is a member of the immunoglobulin superfamily, which binds B7-1 and B7-2 on APCs (antigen-presenting cells), and induces APCs to produce an inhibitory signal to T cells. The aim of this study was to investigate the effect of vitamin D on CTLA-4 gene expression in whole blood samples of patients with UC.

METHODS

90 patients with mild to moderate UC were randomized to receive either a single injection of 7.5 mg vitamin D3 or 1 mL normal saline. 90 days following the intervention fold changes in CTLA-4 mRNA expression were determined and statistical comparisons between the two groups were performed.

RESULTS

Serum vitamin D increased significantly only in the vitamin D group. CTLA-4 fold changes were significantly higher in the vitamin D group compared with the placebo group (median ± IQR: 1.21 ± 2.3 vs. 1.00 ± 1.5, respectively; p = 0.007).

CONCLUSION

The results of this study revealed that vitamin D administration in patients with UC enhances the CTLA-4 gene expression.

What did we learn from CTLA-4 insufficiency on the human immune system?

Cytotoxic-T-lymphocyte-antigen-4 (CTLA-4) is a negative immune regulator constitutively expressed on regulatory T (Treg) cells and upregulated on activated T cells. CTLA-4 inhibits T cell activation by various suppressive functions including competition with CD28, regulation of the inhibitory function of Treg cells, such as transendocytosis, and the control of adhesion and motility. Intrinsic CTLA-4 signaling has been controversially discussed, but so far no distinct signaling pathway has been identified. The CTLA-4-mediated Treg suppression plays an important role in the maintenance of peripheral tolerance and the prevention of autoimmune diseases. Human CTLA-4 insufficiency is caused by heterozygous germline mutations in CTLA4 and characterized by a complex immune dysregulation syndrome. Clinical studies on CTLA4 mutation carriers showed a reduced penetrance and variable expressivity, suggesting modifying factor(s). One hundred and forty-eight CTLA4 mutation carriers have been reported; patients showed hypogammaglobulinemia, recurrent infectious diseases, various autoimmune diseases, and lymphocytic infiltration into multiple organs. The CTLA-4 expression level in Treg cells was reduced, while the frequency of Treg cells was increased in CTLA-4-insufficient patients. The transendocytosis assay is a specific functional test for the assessment of newly identified CTLA4 gene variants. Immunoglobulin substitution, corticosteroids, immunosuppressive therapy, and targeted therapy such as with CTLA-4 fusion proteins and mechanistic target of rapamycin (mTOR) inhibitors were applied; patients with life-threatening, treatment-resistant symptoms underwent hematopoietic stem cell transplantation. The fact that in humans CTLA-4 insufficiency causes severe disease taught us that the amount of CTLA-4 molecules present in/on T cells matters for immune homeostasis. However, whether the pathology-causing activated T lymphocytes in CTLA-4-insufficient patients are antigen-specific is an unsolved question. CTLA-4, in addition, has a role in autoimmune diseases and cancer. Anti-CTLA-4 drugs are employed as checkpoint inhibitors to target various forms of cancer. Thus, clinical research on human CTLA-4 insufficiency might provide us a deeper understanding of the mechanism(s) of the CTLA-4 molecule and immune dysregulation disorders.