Inflammatory bowel disease following anti-interleukin-1-treatment in systemic juvenile idiopathic arthritis

Clinical Characteristics of Cryopyrin-Associated Periodic Syndrome and Long-Term Real-World Efficacy and Tolerability of Canakinumab in Japan: Results of a Nationwide Survey

OBJECTIVE

We assess the clinical characteristics of patients with cryopyrin-associated periodic syndrome (CAPS) in Japan and evaluate the real-world efficacy and safety of interleukin-1 (IL-1) inhibitors, primarily canakinumab.

METHODS

Clinical information was collected retrospectively, and serum concentrations of canakinumab and cytokines were analyzed.

RESULTS

A total of 101 patients were included, with 86 and 15 carrying heterozygous germline and somatic mosaic mutations, respectively. We identified 39 mutation types, and the common CAPS-associated symptoms corresponded with those in previous reports. Six patients (5.9% of all patients) died, with four of the deaths caused by CAPS-associated symptoms. Notably, 73.7% of patients (100%, 79.6%, and 44.4% of familial cold autoinflammatory syndrome, Muckle-Wells syndrome, and chronic infantile neurological cutaneous articular syndrome/neonatal onset multisystem inflammatory disease, respectively) achieved complete remission with canakinumab, and early therapeutic intervention was associated with better auditory outcomes. In some patients, canakinumab treatment stabilized the progression of epiphysial overgrowth and improved height gain, visual acuity, and renal function. However, 23.7% of patients did not achieve inflammatory remission with crucial deterioration of organ damage, with two dying while receiving high-dose canakinumab treatment. Serological analysis of canakinumab and cytokine concentrations revealed that the poor response was not related to canakinumab shortage. Four inflammatory nonremitters developed inflammatory bowel disease (IBD)-unclassified during canakinumab treatment. Dual biologic therapy with canakinumab and anti-tumor necrosis factor-α agents was effective for IBD- and CAPS-associated symptoms not resolved by canakinumab monotherapy.

CONCLUSION

This study provides one of the largest epidemiologic data sets for CAPS. Although early initiation of anti-IL-1 treatment with canakinumab is beneficial for improving disease prognosis, some patients do not achieve remission despite a high serum concentration of canakinumab. Moreover, IBD may develop in CAPS after canakinumab treatment.

Selected Cytokines and Metalloproteinases in Inflammatory Bowel Disease

Inflammatory bowel disease (IBD) is a collective term for two diseases: ulcerative colitis (UC) and Crohn's disease (CD). There are many factors, e.g., genetic, environmental and immunological, that increase the likelihood of these diseases. Indicators of IBDs include extracellular matrix metalloproteinases (MMPs). The aim of this review is to present data on the role of selected cytokines and metalloproteinases in IBD. In recent years, more and more transcriptomic studies are emerging. These studies are improving the characterization of the cytokine microenvironment inside inflamed tissue. It is observed that the levels of several cytokines are consistently increased in inflamed tissue in IBD, both in UC and CD. This review shows that MMPs play a major role in the pathology of inflammatory processes, cancer, and IBD. IBD-associated inflammation is associated with increased expression of MMPs and reduced ability of tissue inhibitors of metalloproteinases (TIMPs) to inhibit their action. In IBD patients in tissues that are inflamed, MMPs are produced in excess and TIMP activity is not sufficient to block MMPs. This review is based on our personal selection of the literature that was retrieved by a selective search in PubMed using the terms "Inflammatory bowel disease" and "pathogenesis of Inflammatory bowel diseases" that includes systematic reviews, meta-analyses, and clinical trials. The involvement of the immune system in the pathophysiology of IBD is reviewed in terms of the role of the cytokines and metalloproteinases involved.

Successful treatment of ulcerative colitis with anakinra: a case report

Currently the effect of IL-1 blockade on ulcerative colitis (UC) is still ambiguous. This case report describes a patient with UC who developed severe complications after an episode of azathioprineinduced pancytopenia including cytomegalovirus pneumonitis, hemophagocytic lymphohistiocytosis, and probable pulmonary aspergillosis. Imaging after the hospitalization revealed a severe disseminated chronic candidiasis and persisting inflammation was seen. Genetic testing revealed heterozygous variants in NOD2 and NLRP12, and cytokine testing showed an increase in IL-1Ra, IL-18, CXCL9, and CXCL10. Consequently an IL-1 mediated autoinflammatory syndrome was suspected. Simultaneously, the patient developed a corticosteroid dependent UC flare-up. Treatment with anakinra was initiated for the IL-1 mediated disease which quickly induced remission of both the inflammatory syndrome and the UC.

The safety of canakinumab in systemic juvenile idiopathic arthritis and autoinflammatory diseases in pediatric patients: a multicenter study

OBJECTIVE

To evaluate the safety of canakinumab using real-world data in patients with systemic juvenile idiopathic arthritis (sJIA) and autoinflammatory diseases (AID).

RESEARCH DESIGN AND METHODS

This was a cross-sectional observational, multicenter study. Patients diagnosed with AID and sJIA treated with canakinumab were included in the study. The participating 13 centers retrospectively collected their patients' data.

RESULTS

A total of 335 patients were involved in the study. Among these patients, 280 were in the AID group and 55 were in the sJIA group. Canakinumab was administered at a median dose of 3 (2.5-4) mg/kg. The median total exposure time to canakinumab was 1.9 (0.8-3.2) years, corresponding to 759.5 patient-years. Seven hundred and seventy-nine total adverse events (AE) were identified. The total incidence of AE, and serious adverse events (SAE) throughout the study period was 1.02 per patient-years. The upper respiratory tract infection rate was 0.7 per patient-years, while the other infection rate was 0.13 per patient-years. While no death was observed in any patient, SAE were observed in 8 patients. Interstitial lung disease, anaphylaxis, or anaphylactoid reactions were not observed in any patient.

CONCLUSIONS

Real-life data from a large cohort of patients suggests that canakinumab is as safe as claimed in clinical trials.

IEC-intrinsic IL-1R signaling holds dual roles in regulating intestinal homeostasis and inflammation

Intestinal epithelial cells (IECs) constitute a critical first line of defense against microbes. While IECs are known to respond to various microbial signals, the precise upstream cues regulating diverse IEC responses are not clear. Here, we discover a dual role for IEC-intrinsic interleukin-1 receptor (IL-1R) signaling in regulating intestinal homeostasis and inflammation. Absence of IL-1R in epithelial cells abrogates a homeostatic antimicrobial program including production of antimicrobial peptides (AMPs). Mice deficient for IEC-intrinsic IL-1R are unable to clear Citrobacter rodentium (C. rodentium) but are protected from DSS-induced colitis. Mechanistically, IL-1R signaling enhances IL-22R-induced signal transducer and activator of transcription 3 (STAT3) phosphorylation in IECs leading to elevated production of AMPs. IL-1R signaling in IECs also directly induces expression of chemokines as well as genes involved in the production of reactive oxygen species. Our findings establish a protective role for IEC-intrinsic IL-1R signaling in combating infections but a detrimental role during colitis induced by epithelial damage.

Macrophages-microenvironment crosstalk in fibrostenotic inflammatory bowel disease: from basic mechanisms to clinical applications

INTRODUCTION

Intestinal fibrosis is a common complication of Inflammatory Bowel Disease (IBD) with no available drugs. The current therapeutic principle is surgical intervention as the core. Intestinal macrophages contribute to both the progression of inflammation and fibrosis. Understanding the role of macrophages in the intestinal microenvironment could bring new hope for fibrosis prevention or even reversal.

AREAS COVERED

This article reviewed the most relevant reports on macrophage in the field of intestinal fibrosis. The authors discussed current opinions about how intestinal macrophages function and interact with surrounding mediators during inflammation resolution and fibrostenotic IBD. Based on biological mechanisms findings, authors summarized related clinical trial outcomes.

EXPERT OPINION

The plasticity of intestinal macrophages allows them to undergo dramatic alterations in their phenotypes or functions when exposed to gastrointestinal environmental stimuli. They exhibit distinct metabolic characteristics, secrete various cytokines, express unique surface markers, and transmit different signals. Nevertheless, the specific mechanism through which the intestinal macrophages contribute to intestinal fibrosis remains unclear. It should further elucidate a novel therapeutic approach by targeting macrophages, especially distinct mechanisms in specific subgroups of macrophages involved in the progression of fibrogenesis in IBD.

Crohn's disease in a patient with systemic onset juvenile idiopathic arthritis. Association or associated side effect of treatment?

The progression of systemic-onset juvenile idiopathic arthritis (JIAs) to the different forms of presentation of inflammatory bowel disease is extremely rare. We present the first report of a patient with SJIA that progressed to Crohn's disease in which mutations have been detected in genes responsible for the adequate regulation of the innate immune system.

Gut inflammation induced by drugs: Can pathology help to differentiate from inflammatory bowel disease?

Drug‐induced mucosal injury (DIMI) in the gastrointestinal tract is important to recognise, partly because cessation of the culprit agent alone may result in resolution of symptoms. An ever‐growing list of medications, including newer immunotherapeutic agents and targeted therapies, can cause gastrointestinal inflammation of varying severity. However, the diagnosis of DIMI is challenging, as a single drug can induce a variety of histopathological patterns of injury including acute colitis, chronic colitis, microscopic colitis, apoptotic colopathy, and ischaemic‐type colitis. An additional consideration is the potential clinical, endoscopic and histological overlap of DIMI with gastrointestinal mucosal injury secondary to other entities such as inflammatory bowel disease (IBD). We discuss DIMI of the gastrointestinal tract with an emphasis on histological patterns that mimic IBD, histological features which may distinguish the two entities, and the diagnostic role and limitations of the pathologist.

Bowel Perforation During Haemophagocytic Lymphohistiocytosis Treatment with Corticosteroids and Anakinra

We report the use of anakinra to treat a case of a 64-year-old man diagnosed with haemophagocytic lymphohistiocytosis (HLH) with neurological involvement. After the administration of intravenous pulse corticosteroid therapy, immunoglobulin and anakinra the patient showed neurological recovery. However, the recovery was complicated by the perforation of a pre-existing bowel diverticulum. The effect of anakinra on bowel inflammation has not yet been clearly established. It can potentially augment bowel inflammation and contribute to the risk of bowel perforation associated with the concomitant use of corticosteroids.

LEARNING POINTS

Anakinra can potentially augment bowel inflammation.The concomitant use of anakinra and corticosteroids may increase the risk of bowel perforation.Use of anakinra and corticosteroids in patients with pre-existing gastrointestinal diseases requires vigilant observation for abdominal symptoms.

IL-1β and the Intestinal Epithelial Tight Junction Barrier

The intestinal epithelial tight junction (TJ) barrier controls the paracellular permeation of contents from the intestinal lumen into the intestinal tissue and systemic circulation. A defective intestinal TJ barrier has been implicated as an important pathogenic factor in inflammatory diseases of the gut including Crohn's disease, ulcerative colitis, necrotizing enterocolitis, and celiac disease. Previous studies have shown that pro-inflammatory cytokines, which are produced during intestinal inflammation, including interleukin-1β (IL-1β), tumor necrosis factor-α, and interferon-γ, have important intestinal TJ barrier-modulating actions. Recent studies have shown that the IL-1β-induced increase in intestinal TJ permeability is an important contributing factor of intestinal inflammation. The IL-1β-induced increase in intestinal TJ permeability is mediated by regulatory signaling pathways and activation of nuclear transcription factor nuclear factor-κB, myosin light chain kinase gene activation, and post-transcriptional occludin gene modulation by microRNA and contributes to the intestinal inflammatory process. In this review, the regulatory role of IL-1β on intestinal TJ barrier, the intracellular mechanisms that mediate the IL-1β modulation of intestinal TJ permeability, and the potential therapeutic targeting of the TJ barrier are discussed.

Biotechnological Agents for Patients With Tumor Necrosis Factor Receptor Associated Periodic Syndrome-Therapeutic Outcome and Predictors of Response: Real-Life Data From the AIDA Network

Objective: To describe the role of biotechnological therapies in patients with tumor necrosis factor receptor associated periodic syndrome (TRAPS) and to identify any predictor of complete response. Methods: Clinical, laboratory, and therapeutic data from 44 Caucasian TRAPS patients treated with biologic agents were retrospectively collected in 16 Italian tertiary Centers. Results: A total of 55 biological courses with anakinra (n = 26), canakinumab (n = 16), anti-TNF-α agents (n = 10), and tocilizumab (n = 3) were analyzed. A complete response was observed in 41 (74.5%) cases, a partial response in 9 (16.4%) cases and a treatment failure in 5 (9.1%) cases. The frequency of TRAPS exacerbations was 458.2 flare/100 patients-year during the 12 months prior to the start of biologic treatment and 65.7 flare/100 patients-years during the first 12 months of therapy (p < 0.0001). The median duration of attacks was 5.00 (IQR = 10.50) days at the start of biologics and 1.00 (IQR = 0.00) days at the 12-month assessment (p < 0.0001). Likewise, a significant reduction was observed in the Autoinflammatory Disease Activity Index during the study period (p < 0.0001). A significant corticosteroid sparing effect was observed as early as the first 12 months of treatment both in the number of patients requiring corticosteroids (p = 0.025) and in the dosages employed (p < 0.0001). A significant reduction was identified in the erythrocyte sedimentation rate (p < 0.0001), C reactive protein (p < 0.0001), serum amyloid A (p < 0.0001), and in the 24-h proteinuria dosage during follow-up (p = 0.001). A relapsing-remitting disease course (OR = 0.027, C.I. 0.001-0.841, p = 0.040) and the frequency of relapses at the start of biologics (OR = 0.363, C.I. 0.301-0.953, p = 0.034) were significantly associated with a complete response. No serious adverse events were observed. Conclusions: Treatment with biologic agents is highly effective in controlling clinical and laboratory TRAPS manifestations. Patients with a relapsing-remitting course and a lower frequency of flares at the start of treatment show more likely a complete response to biologic agents.

Immunologic Adverse Effects of Biologics for the Treatment of Atopy

The use of biologic agents as therapies for atopic diseases such as asthma and atopic dermatitis has increased greatly in recent years. The biological agents used to treat atopic diseases are for the most part monoclonal antibodies that suppress the immune response and reduce inflammation by targeting particular cytokines or other molecules involved in Th1, Th2, or Th17 immune reactions. Various side effects and rare complications have been reported from these agents. In this review, we discuss mechanisms of various adverse effects for the biologic agents currently in use or in development for atopic and inflammatory diseases. Monoclonal antibodies targeting the Th1 and Th17 pathways have been associated with significant side effects, partially due to their ability to cause significant impairment in immune responses to pathogens because of the immunologic alterations that they produce. Biologicals targeting Th2-mediated inflammation have had fewer reported side effects, though many are new and emerging drugs whose adverse effects may remain to be fully elucidated with more use. Therefore, continued long-term safety monitoring is required. As with all therapies, the risks associated with side effects of biologics must be balanced against the benefits these drugs offer for treating atopic diseases. One of the most apparent benefits is the steroid-sparing effect of well-chosen biologic therapy used to treat severe atopic disease. In contrast with the quite favorable safety profile of currently available biologics that target the Th2-mediated immune response, chronic systemic corticosteroid use is associated with significant side effects, many of which impact the majority of patients who are placed on long-term steroid therapy.

Integration of Immunome With Disease-Gene Network Reveals Common Cellular Mechanisms Between IMIDs and Drug Repurposing Strategies

Objective

Development and progression of immune-mediated inflammatory diseases (IMIDs) involve intricate dysregulation of the disease-associated genes (DAGs) and their expressing immune cells. Identifying the crucial disease-associated cells (DACs) in IMIDs has been challenging due to the underlying complex molecular mechanism.

Methods

Using transcriptome profiles of 40 different immune cells, unsupervised machine learning, and disease-gene networks, we constructed the Disease-gene IMmune cell Expression (DIME) network and identified top DACs and DAGs of 12 phenotypically different IMIDs. We compared the DIME networks of IMIDs to identify common pathways between them. We used the common pathways and publicly available drug-gene network to identify promising drug repurposing targets.

Results

We found CD4+Treg, CD4+Th1, and NK cells as top DACs in inflammatory arthritis such as ankylosing spondylitis (AS), psoriatic arthritis, and rheumatoid arthritis (RA); neutrophils, granulocytes, and BDCA1+CD14+ cells in systemic lupus erythematosus and systemic scleroderma; ILC2, CD4+Th1, CD4+Treg, and NK cells in the inflammatory bowel diseases (IBDs). We identified lymphoid cells (CD4+Th1, CD4+Treg, and NK) and their associated pathways to be important in HLA-B27 type diseases (psoriasis, AS, and IBDs) and in primary-joint-inflammation-based inflammatory arthritis (AS and RA). Based on the common cellular mechanisms, we identified lifitegrast as a potential drug repurposing candidate for Crohn's disease and other IMIDs.

Conclusions

Existing methods are inadequate in capturing the intricate involvement of the crucial genes and cell types essential to IMIDs. Our approach identified the key DACs, DAGs, common mechanisms between IMIDs, and proposed potential drug repurposing targets using the DIME network. To extend our method to other diseases, we built the DIME tool (https://bitbucket.org/systemsimmunology/dime/) to help scientists uncover the etiology of complex and rare diseases to further drug development by better-determining drug targets, thereby mitigating the risk of failure in late clinical development.

Gastrointestinal and renal complications in SARS-CoV-2-infected patients: Role of immune system

The recent severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) disease has been accompanied by various gastrointestinal (GI) and renal manifestations in significant portion of infected patients. Beside studies on the respiratory complications of coronavirus infection, understanding the essential immunological processes underlying the different clinical manifestations of virus infection is crucial for the identification and development of effective therapies. In addition to the respiratory tract, the digestive and urinary systems are the major sources of virus transmission. Thus, knowledge about the invasion mechanisms of SARS-CoV-2 in these systems and the immune system responses is important for implementing the infection prevention strategies. This article presents an overview of the gut and renal complications in SARS-CoV-2 infection. We focus on how SARS-CoV-2 interacts with the immune system and the consequent contribution of immune system, gut, and renal dysfunctions in the development of disease.

Cell death in the gut epithelium and implications for chronic inflammation

The intestinal epithelium has one of the highest rates of cellular turnover in a process that is tightly regulated. As the transit-amplifying progenitors of the intestinal epithelium generate ~300 cells per crypt every day, regulated cell death and sloughing at the apical surface keeps the overall cell number in check. An aberrant increase in the rate of intestinal epithelial cell (IEC) death underlies instances of extensive epithelial erosion, which is characteristic of several intestinal diseases such as inflammatory bowel disease and infectious colitis. Emerging evidence points to a crucial role of necroptosis, autophagy and pyroptosis as important modes of programmed cell death in the intestine in addition to apoptosis. The mode of cell death affects tissue restitution responses and ultimately the long-term risks of intestinal fibrosis and colorectal cancer. A vicious cycle of intestinal barrier breach, misregulated cell death and subsequent inflammation is at the heart of chronic inflammatory and infectious gastrointestinal diseases. This Review discusses the underlying molecular and cellular underpinnings that control programmed cell death in IECs, which emerge during intestinal diseases. Translational aspects of cell death modulation for the development of novel therapeutic alternatives for inflammatory bowel diseases and colorectal cancer are also discussed.

Inflammatory Bowel Disease in Children With Systemic Juvenile Idiopathic Arthritis

OBJECTIVE

The incidence of inflammatory bowel disease (IBD) in juvenile idiopathic arthritis (JIA) is higher than in the general pediatric population. However, reports of IBD in the systemic JIA (sJIA) subtype are limited. We sought to characterize sJIA patients diagnosed with IBD and to identify potential contributing risk factors.

METHODS

Using an internationally distributed survey, we identified 16 patients with sJIA who were subsequently diagnosed with IBD (sJIA-IBD cohort). Five hundred twenty-two sJIA patients without IBD were identified from the CARRA Legacy Registry and served as the sJIA-only cohort for comparison. Differences in demographic, clinical characteristics, and therapy were assessed using chi-square test, Fisher exact test, t-test, and univariate and multivariate logistic regression, as appropriate.

RESULTS

Of the patients with sJIA-IBD, 75% had a persistent sJIA course and 25% had a history of macrophage activation syndrome. sJIA-IBD subjects were older at sJIA diagnosis, more often non-White, had a higher rate of IBD family history, and were more frequently treated with etanercept or canakinumab compared to sJIA-only subjects. Sixty-nine percent of sJIA-IBD patients successfully discontinued sJIA medications following IBD diagnosis, and sJIA symptoms resolved in 9 of 12 patients treated with tumor necrosis factor-α (TNF-α) inhibitors.

CONCLUSION

IBD in the setting of sJIA is a rare occurrence. The favorable response of sJIA symptoms to therapeutic TNF-α inhibition suggests that the sJIA-IBD cohort may represent a mechanistically distinct sJIA subgroup. Our study highlights the importance of maintaining a high level of suspicion for IBD when gastrointestinal involvement occurs in patients with sJIA and the likely broad benefit of TNF-α inhibition in those cases.

Cytokines in inflammatory bowel diseases - Update 2020

Inflammatory Bowel Diseases (IBD), namely Crohn's Disease and Ulcerative Colitis, cause a significant disease burden in modern civilization. Ever since the introduction of anti-TNF-directed therapies 20 years ago, cytokines have attracted a lot of research attention and several cytokine-directed therapies have been implemented in the clinical treatment of these diseases. The research progress in these past years has underlined the importance of both myeloid and lymphoid elements of the immune system in the pathogenesis of IBD and their cytokine-mediated interplay. The conceptual framework of the mucosal cytokine network has shifted during these years from a T helper (Th) dichotomy (Th1/Th2) to the effector/regulatory T cell balance, while nowadays, the importance of myeloid cell instruction of lymphocytes, namely by IL-12 and IL-23, is increasingly recognized. Anti-IL-12p40 agents, like ustekinumab, groundbreakingly changed patient care, and anti-IL23p19-directed approaches are on the verge of grand success. In this review we present a modular approach to understand the cytokine network and put it into the context of the pathogenesis of IBD with a special focus on publications since 2014.

Mechanisms Underlying Bone Loss Associated with Gut Inflammation

Patients with gastrointestinal diseases frequently suffer from skeletal abnormality, characterized by reduced bone mineral density, increased fracture risk, and/or joint inflammation. This pathological process is characterized by altered immune cell activity and elevated inflammatory cytokines in the bone marrow microenvironment due to disrupted gut immune response. Gastrointestinal disease is recognized as an immune malfunction driven by multiple factors, including cytokines and signaling molecules. However, the mechanism by which intestinal inflammation magnified by gut-residing actors stimulates bone loss remains to be elucidated. In this article, we discuss the main risk factors potentially contributing to intestinal disease-associated bone loss, and summarize current animal models, illustrating gut-bone axis to bridge the gap between intestinal inflammation and skeletal disease.

Ulcerative Colitis and Familial Mediterranean Fever: Can Anakinra Treat Both?

Anakinra is a biological drug used in rheumatoid arthritis and several autoinflammatory diseases. Its main side effects are injection site reactions and increased infection rate. We present a 28-year-old man with familial Mediterranean fever, whose disease went into remission on anakinra, with concomitant flare of his ulcerative colitis.

Using genes to triangulate the pathophysiology of granulomatous autoinflammatory disease: NOD2, PLCG2 and LACC1

The intersection of granulomatosis and autoinflammatory disease is a rare occurrence that can be generally subdivided into purely granulomatous phenotypes and disease spectra that are inclusive of granulomatous features. NOD2 (nucleotide-binding oligomerization domain-containing protein 2)-related disease, which includes Blau syndrome and early-onset sarcoidosis, is the prototypic example of granulomatous inflammation in the context of monogenic autoinflammation. Granulomatous inflammation has also been observed in two related autoinflammatory diseases caused by mutations in PLCG2 (phospholipase Cγ2). More recently, mutations in LACC1 (laccase domain-containing protein 1) have been identified as the cause of a monogenic form of systemic juvenile idiopathic arthritis, which does not itself manifest granulomatous inflammation, but the same LACC1 mutations have also been shown to cause an early-onset, familial form of a well-known granulomatous condition, Crohn's disease (CD). Rare genetic variants of PLCG2 have also been shown to cause a monogenic form of CD, and moreover common variants of all three of these genes have been implicated in polygenic forms of CD. Additionally, common variants of NOD2 and LACC1 have been implicated in susceptibility to leprosy, a granulomatous infection. Although no specific mechanistic link exists between these three genes, they form an intriguing web of susceptibility to both monogenic and polygenic autoinflammatory and granulomatous phenotypes.

Divergent Roles for the IL-1 Family in Gastrointestinal Homeostasis and Inflammation

Inflammatory disorders of the gastro-intestinal tract are a major cause of morbidity and significant burden from a health and economic perspective in industrialized countries. While the incidence of such conditions has a strong environmental component, in particular dietary composition, epidemiological studies have identified specific hereditary mutations which result in disequilibrium between pro- and anti-inflammatory factors. The IL-1 super-family of cytokines and receptors is highly pleiotropic and plays a fundamental role in the pathogenesis of several auto-inflammatory conditions including rheumatoid arthritis, multiple sclerosis and psoriasis. However, the role of this super-family in the etiology of inflammatory bowel diseases remains incompletely resolved despite extensive research. Herein, we highlight the currently accepted paradigms as they pertain to specific IL-1 family members and focus on some recently described non-classical roles for these pathways in the gastrointestinal tract. Finally, we address some of the shortcomings and sources of variance in the field which to date have yielded several conflicting results from similar studies and discuss the potential effect of these factors on data interpretation.

Autoinflammatory disease with focus on NOD2-associated disease in the era of genomic medicine

Systemic autoinflammatory diseases (SAIDs) represent a spectrum of genetically heterogeneous inflammatory disorders. Some SAID-associated genes are located in chromosome 16, including familial Mediterranean fever gene (MEFV) and nucleotide-binding oligomerization domain 2 [NOD2] gene that are linked to Crohn's disease, Blau syndrome, and Yao syndrome. These disorders share overlapping clinical phenotypes, and genotyping is diagnostically helpful and distinctive. Using next generation sequencing in SAIDs, digenic variants or combinations of more genetic variants in different genes can be detected, and they may be related to the MEFV and NOD2 genes. These variants may contribute to heterogeneous phenotypes in an individual, complicating the diagnosis and therapy. An awareness of the clinical significance of the digenic or combined gene variants is important in the era of genomic medicine.

Two distinct colonic CD14+ subsets characterized by single-cell RNA profiling in Crohn's disease

Inflammatory bowel diseases are associated with dysregulated immune responses in the intestinal tissue. Four molecularly identified macrophage subsets control immune homeostasis in healthy gut. However, the specific roles and transcriptomic profiles of the phenotypically heterogeneous CD14⁺ macrophage-like population in inflamed gut remain to be investigated in Crohn's disease (CD). Here we identified two phenotypically, morphologically and functionally distinct colonic HLADR⁺SIRPα⁺CD14⁺ subpopulations that were further characterized using single-cell RNA-sequencing (scRNAseq) in CD. Frequencies of CD64^hiCD163^-/dim cells selectively augmented in inflamed colon and correlated with endoscopic score of disease severity. IL-1β and IL-23-producing CD64^hiCD163^-/dim cells predominated over TNF-α-producing CD64^hiCD163^hi cells in lesions. Purified "inflammatory monocyte-like" CD163^-, but not "macrophage-like" CD163^hi cells, through IL-1β, promoted Th17/Th1 but not Th1 responses in tissue memory CD4⁺T cells. Unsupervised scRNAseq analysis that captures the entire HLADR⁺SIRPα⁺ population revealed six clusters, two of which were enriched in either CD163^- or CD163^hi cells, and best defined by TREM1/FCAR/FCN1/IL1RN or CD209/MERTK/MRCI/CD163L1 genes, respectively. Selected newly identified discriminating markers were used beyond CD163 to isolate cells that shared pro-Th17/Th1 function with CD163^- cells. In conclusion, a molecularly distinct pro-inflammatory CD14⁺ subpopulation accumulates in inflamed colon, drives intestinal inflammatory T-cell responses, and thus, might contribute to CD disease severity.

A Comparative Study on the Efficacy of NLRP3 Inflammasome Signaling Inhibitors in a Pre-clinical Model of Bowel Inflammation

Nucleotide-binding oligomerization domain leucine rich repeat and pyrin domain-containing protein 3 (NLRP3) inflammasome is pivotal in maintaining intestinal homeostasis and sustaining enteric immune responses in the setting of inflammatory bowel diseases. Drugs acting as NLRP3 blockers could represent innovative strategies for treatment of bowel inflammation. This study was performed in rats with dinitrobenzenesulfonic acid (DNBS)-induced colitis, to investigate how the direct blockade of NLRP3 inflammasome with an irreversible inhibitor (INF39) compares with Ac-YVAD-cmk (YVAD, caspase-1 inhibitor) and anakinra (IL-1β receptor antagonist), acting downstream on NLRP3 signaling. Animals with DNBS-colitis received YVAD (3 mg/kg) or anakinra (100 mg/Kg) intraperitoneally, and INF39 (25 mg/kg) or dexamethasone (DEX, 1 mg/kg) orally for 6 days, starting on the same day of colitis induction. Under colitis, there was a body weight decrease, which was attenuated by YVAD, anakinra or INF39, but not DEX. All test drugs counteracted the increase in spleen weight. The colonic shortening and morphological colonic alterations associated with colitis were counteracted by INF39, anakinra and DEX, while YVAD was without effects. Tissue increments of myeloperoxidase, tumor necrosis factor and interleukin-1β were more effectively counteracted by INF39 and DEX, than YVAD and anakinra. These findings indicate that: (1) direct inhibition of NLRP3 inflammasome with INF39 is more effective than caspase-1 inhibition or IL-1β receptor blockade in reducing systemic and bowel inflammatory alterations; (2) direct NLRP3 inhibition can be a suitable strategy for treatment of bowel inflammation.

Anti-Inflammatory Biologics and Anti-Tumoral Immune Therapies-Associated Colitis: A Focused Review of Literature

An increasing number of drugs including monoclonal antibodies and small molecules, either anti-inflammatory or immunity-enhancing, have been developed to treat human diseases and the number of medications in these classes is likely to expand in the future. The two most commonly used categories of such therapies are the anti-inflammatory group (anti- tumor necrosis factor (TNF) α, anti-interleukins/interleukin receptors, and anti-integrin bodies) and the anti-tumoral agents (immune checkpoint inhibitors, anti-CD20, and anti-endothelial growth factor). Although the anti-inflammatory biologics have brought about a revolutionary effect in the management of a variety of autoimmune disorders including rheumatologic diseases, inflammatory bowel disease, and inflammatory dermatological diseases, their ability to induce colitis in patients without a prior history of colitis or exacerbate quiescent colitis has been increasingly and unexpectedly recognized. While the use of immune-augmenting monoclonal antibody therapies results in a significant survival benefit in a subset of patients with malignancies, these monoclonal antibodies also have the ability to cause colitis through an apparent autoimmune mechanism. Colitis associated with these medications may demonstrate multiple histologic patterns including increased apoptosis (graft versus host disease (GVHD)-like), autoimmune enteropathy pattern, acute colitis pattern, ischemic colitis, inflammatory bowel disease pattern, either ulcerative colitis-like, Crohn’s disease-like, or fulminant colitis-like. In addition, anti-inflammatory biologics are known to cause or reactivate latent infections such as tuberculosis and increase the risk for malignancies including high-grade lymphomas as well as indolent lymphoproliferative disorders. Thus, the differential diagnosis for colitis in patients receiving therapeutic anti-inflammatory biologics or anti-tumoral agents can be broad. Optimal diagnosis and treatment requires a multidisciplinary approach. This review aims to provide an overview of the literature on the clinical features, histology, and treatment of these newly recognized anti-inflammatory biologic and anti-tumoral immune therapy-induced colitises and hopes this outlines will raise the vigilance of all clinicians of these entities.