Aryl Hydrocarbon Receptor Signalling in the Control of Gut Inflammation.

Aryl hydrocarbon receptor (AHR), a transcription factor activated by many natural and synthetic ligands, represents an important mediator of the interplay between the environment and the host's immune responses. In a healthy gut, AHR activation promotes tolerogenic signals, which help maintain mucosal homeostasis. AHR expression is defective in the inflamed gut of patients with inflammatory bowel diseases (IBD), where decreased AHR signaling is supposed to contribute to amplifying the gut tissue's destructive immune-inflammatory responses. We here review the evidence supporting the role of AHR in controlling the "physiological" intestinal inflammation and summarize the data about the therapeutic effects of AHR activators, both in preclinical mouse models of colitis and in patients with IBD.

Diagnostic value of anti-integrin αvß6 antibodies in ulcerative colitis.

Ulcerative colitis (UC)-related mucosal inflammation is characterized by the production of various autoantibodies with limited clinical relevance. Recent studies have shown that circulating levels of IgG against integrin αvß6 are increased in UC patients as compared to Crohn's disease (CD) patients and healthy controls (HC). The present study assessed the diagnostic value of circulating IgG anti-αvß6 in UC. Sera were prospectively collected from 108 outpatients with UC, 103 patients with CD, and 62 HC, and the levels of IgG anti-αvß6 were measured using a commercially available ELISA kit. The cut-off for positive results was defined as the 95th percentile of the values of the autoantibodies in HC serum samples. Levels of IgG anti-αvß6 were significantly higher in UC than in CD patients, including those with colonic localization, and HC. Fifty-six of the 108 (51.8%) UC patients had a positive test whereas only 17/103 (16.5%) patients with CD, and among these, 4/16 (25%) patients with colonic CD, were positive. In UC, there was no statistical difference between patients with IgG anti-αvß6 positivity and those negative in terms of clinical disease activity, fecal calprotectin values, and disease extent. The sensitivity, specificity, predictive positive value, and predictive negative value of the test to differentiate between UC and CD were 51.9% (C.I.42.4-61.3), 83.5% (C.I. 76.3-90.7), 76.7% (C.I. 67.0-86.4), and 62.3% (C.I. 54.2-70.4) respectively. Our study confirms that anti-αvß6 antibodies are demonstrable in the serum of the majority of UC patients and suggests the necessity of further research to understand if the anti-αvß6 antibody determination could have a place in the clinical decision-making of IBD.

Emerging oral drug options for ulcerative colitis.

INTRODUCTION: Despite the availability of a variety of therapeutic compounds and improved management strategies, one-third of UC patients with moderate-to-severe disease do not benefit from the existing treatments or experience drug-related side effects. This has boosted intensive research focusing on the development of new drugs for UC therapy. This article aims to summarize the available evidence on oral drugs, which are now being explored in clinical trials or are ready to enter the clinics. AREAS COVERED: From May 15 to June 11, we searched on PubMed using the keywords 'oral drugs ulcerative colitis,' 'ulcerative colitis clinical trials,' 'UC phase 2 and 3 trials' excluding case reports, case series, phase 1 and 4 studies, and studies about approved therapies. EXPERT OPINION: The findings discussed in this article suggest that the future treatment of UC patients will be probably characterized by the possibility of using various small-molecule drugs. All these new compounds, even those belonging to the same class, differ in terms of efficacy and safety. Identification of predictors of response could help optimize the efficacy and safety of these treatments, thus improving resource allocation through a pretreatment stratification of patients.

Immune-mediated inflammatory diseases: Common and different pathogenic and clinical features.

The term "immune-mediated inflammatory diseases (IMIDs)" refers to several inflammatory pathologies of multifactorial etiology and involving either simultaneously or sequentially more organs. IMIDs share some common pathogenic mechanisms, which account for some similarities in the clinical course and the impact that these diseases may have on other organs and systems of the body. However, there are some differences in the IMID-associated pathological process, including the synthesis and function of multiple inflammatory cytokines, which are supposed to perpetuate the tissue-damaging inflammation. This justifies the different indications and responsiveness to corticosteroids, immunosuppressors, small molecules, and biologics. Many individuals with IMIDs are, however, intolerant, or unresponsive to the current drugs, thus suggesting the necessity of novel therapeutic approaches, such as the combination of compounds that either inhibit more immuno-inflammatory networks selectively or simultaneously suppress inflammatory signals and activate counter-regulatory pathways. In this article, we highlight the most relevant features of IMIDs and discuss how clinicians can combat the detrimental immune response in such disorders.

Severe acute respiratory syndrome coronavirus 2 infection does not worsen the course of inflammatory bowel disease in the long term.

BACKGROUND: The long-term outcome of inflammatory bowel disease (IBD) patients after severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection is under investigation. AIM: To assess, in a prospective study, whether a recent SARS-CoV-2 infection increases the risk of IBD relapse within 12 months. METHODS: From March to April 2021, all IBD patients with recent (<2 months) SARS-CoV-2 infection (Cases) were enrolled. For each enrolled Case, four IBD Controls with no history of infection were considered. Clinical course of IBD was recorded for 12 months. Inclusion criteria: well defined diagnosis of IBD; age ≥18 and ≤85 years; 12-month follow-up; consent. Exclusion criteria: incomplete data; SARS-CoV-2 infection after enrollment. Additional inclusion criteria: recent SARS-CoV-2 infection for Cases; no history of SARS-CoV-2 infection for Controls. Data expressed as median [range]. Statistical analysis: Student-t-Test, Mann-Whitney U-test, χ2 test, multivariate logistic regression model [odds ratio (95% confidence interval)], Kaplan-Meier curves. RESULTS: One hundred forty-three IBD patients were enrolled. The analysis included 118 patients (22 met the exclusion criteria, three lost at follow-up): 29 (24.6%) Cases and 89 (75.4%) Controls. Demographic and clinical characteristics were comparable between groups. During the 12-month study, the frequency of IBD relapse was comparable between Cases and Controls [8 (27%) vs 19 (21%); P = 0.65]. At univariate analysis, SARS-CoV-2 infection was not a risk factor for IBD relapse within 12 months [1.5 (0.6-3.9); P = 0.34]. At multivariate analysis, IBD activity at baseline was the only risk factor for relapse [3.2 (1.1-9.1); P = 0.03]. Kaplan-Meier curves showed that survival from IBD relapse was comparable between Cases and Controls (P = 0.33). CONCLUSION: In a prospective 12-month study, a recent SARS-CoV-2 infection did not increase the risk of clinical relapse of IBD in the long term.

Frequency and Predictors of Dysplasia in Pseudopolyp-like Colorectal Lesions in Patients with Long-Standing Inflammatory Bowel Disease.

Current endoscopic surveillance programs do not consider inflammatory bowel disease (IBD)-associated post-inflammatory polyps (pseudopolyps) per se clinically relevant, even though their presence seems to increase the risk of colorectal cancer (CRC). However, it remains unclear whether the link between pseudopolyps and CRC is indirect or whether some subsets of pseudopolyp-like lesions might eventually undergo neoplastic transformation. This study aimed to assess the frequency and predictors of dysplasia in pseudopolyp-like lesions in a population with long-standing colonic IBD. This was a retrospective, single-center study including patients with a colonic IBD (median disease duration of 192 months) and at least a pseudopolyp-like lesion biopsied or resected in the period from April 2021 to November 2022. One hundred and five pseudopolyps were identified in 105 patients (80 with ulcerative colitis and 25 with Crohn's disease). Twenty-three out of 105 pseudopolyp samples (22%) had dysplastic foci, and half of the dysplastic lesions were hyperplastic. Multivariate analysis showed that the age of the patients (odds ratio (OR) 1.1; p = 0.0012), size (OR 1.39; p = 0.0005), and right colonic location (OR 5.32; p = 0.04) were independent predictors of dysplasia, while previous exposure to immunosuppressors/biologics and left colonic location of the lesions were inversely correlated to dysplasia (OR 0.11; p = 0.005, and OR 0.09; p = 0.0008, respectively). No differences were seen between ulcerative colitis and Crohn's disease patients. Lesions with a size greater than 5 mm had a sensitivity of 87% and a specificity of 63% to be dysplastic. These data show that one-fourth of pseudopolyp-like lesions evident during surveillance colonoscopy in patients with longstanding IBD bear dysplastic foci and suggest treating such lesions properly.

Niclosamide Enema for Active Distal Ulcerative Colitis: A Phase 1, Open-Label Study.

BACKGROUND: Oral and rectal formulations of 5-aminosalicylic acid are the first-line therapy for mild-to-moderate, distal ulcerative colitis (UC), but such a treatment is not effective in one-third of patients. Niclosamide is a small molecule, developed and approved as an orally administered drug to treat helminthic infections, with an excellent safety profile. Preclinical work showed that niclosamide is an anti-inflammatory agent, thereby providing the rationale to explore its safety and efficacy in patients with UC. This phase 1, open-label trial was aimed at assessing the safety of niclosamide formulated as an enema in patients with mild-to-moderate, distal UC, who relapsed on maintenance therapy with oral and/or rectal 5-aminosalicylic acid. METHODS: Seventeen patients with active UC received niclosamide enema (150 mg/60 mL) twice a day for 6 weeks. The primary endpoint was the safety of niclosamide treatment. Secondary endpoints included clinical remission and improvements in endoscopic Mayo/histologic scores. Endoscopic remission percentages exclude participants meeting criteria at baseline for endoscopic remission. RESULTS: Niclosamide was well tolerated by all 17 patients that were enrolled and treated. No serious adverse event was registered. Fifteen mild adverse events were registered in 6 patients and considered to be unrelated to the treatment. Clinical remission was achieved in 10 (59%) of 17 patients. Improvements of endoscopic Mayo score and histologic Geboes score were seen in 7 (58%) of 12 and 7 (41.2%) of 17 patients, respectively. CONCLUSIONS: Niclosamide enema treatment is safe and well tolerated. Niclosamide improves clinical symptoms and endoscopic/histologic signs of UC; however, appropriately designed placebo-controlled clinical trials are required to confirm efficacy.

Corrigendum: An essential role of adenosine deaminase acting on RNA 1 in coeliac disease mucosa.

[This corrects the article DOI: 10.3389/fimmu.2023.1175348.].

An essential role of adenosine deaminase acting on RNA 1 in coeliac disease mucosa.

Background and aim: Type I interferons (IFNs) are highly expressed in the gut mucosa of celiac disease (CD) gut mucosa and stimulates immune response prompted by gluten ingestion, but the processes that maintain the production of these inflammatory molecules are not well understood. Adenosine deaminase acting on RNA 1 (ADAR1), an RNA-editing enzyme, plays a crucial role in inhibiting self or viral RNAs from activating auto-immune mediated responses, most notably within the type-I IFN production pathway. The aim of this study was to assess whether ADAR1 could contribute to the induction and/or progression of gut inflammation in patients with celiac disease. Material and methods: ADAR1 expression was assessed by Real time PCR and Western blotting in duodenal biopsy taken from inactive and active celiac disease (CD) patients and normal controls (CTR). To analyze the role of ADAR1 in inflamed CD mucosa, lamina propria mononuclear cells (LPMC) were isolated from inactive CD and ADAR1 was silenced in with a specific antisense oligonucleotide (AS) and then incubated with a synthetic analogue of viral dsRNA (poly I:C). IFN-inducing pathways (IRF3, IRF7) in these cells were evaluated with Western blotting and inflammatory cytokines were evaluated with flow cytometry. Lastly, the role of ADAR1 was investigated in a mouse model of poly I:C-driven small intestine atrophy. Results: Reduced ADAR1 expression was seen in duodenal biopsies compared to inactive CD and normal controls. Ex vivo organ cultures of duodenal mucosal biopsies, taken from inactive CD patients, stimulated with a peptic-tryptic digest of gliadin displayed a decreased expression of ADAR1. ADAR1 silencing in LPMC stimulated with a synthetic analogue of viral dsRNA strongly boosted the activation of IRF3 and IRF7 and the production of type-I IFN, TNF-α and IFN-γ. Administration of ADAR1 antisense but not sense oligonucleotide to mice with poly I:C-induced intestinal atrophy, significantly increased gut damage and inflammatory cytokines production. Conclusions: These data show that ADAR1 is an important regulator of intestinal immune homeostasis and demonstrate that defective ADAR1 expression could provide to amplifying pathogenic responses in CD intestinal mucosa.

Reversibility of Frail Phenotype in Patients with Inflammatory Bowel Diseases.

It was recently reported that frailty status can negatively influence the clinical course of patients with inflammatory bowel diseases (IBDs). Our recent study demonstrated that 20% of patients with an IBD are frail, and disease activity increases the risk of frailty. In the present study, we prospectively monitored this subgroup of frail patients, assessed whether the frailty status was reversible, and analyzed factors associated with frailty reversibility. Of the sixty-four frail patients with IBD enrolled, five (8%) were lost during the follow-up period and one (2%) underwent a colectomy. Eleven out of the fifty-eight (19%) patients maintained a frail phenotype during a median follow-up of 8 months (range 6-19 months), and thirty-five (60%) and twelve (21%) became pre-frail or fit, respectively. A comparison of the 58 patients at baseline and at the end of the study showed that frail phenotype reversibility occurred more frequently in patients who achieved clinical remission. A multivariate analysis showed that the improvement of the frail phenotype was inversely correlated with the persistence of clinically active disease (OR:0.1; 95% CI: 0.02-0.8) and a history of extra-intestinal manifestations (OR:0.1; 95% CI: 0.01-0.6) and positively correlated with the use of biologics (OR: 21.7; 95% CI: 3.4-263). Data indicate that the frail phenotype is a reversible condition in most IBD patients, and such a change relies on the improvement in disease activity.

Helicobacter pylori and Gastric Cancer: Pathogenetic Mechanisms.

Gastric cancer is the sixth most commonly diagnosed cancer and the fourth leading cause of cancer death worldwide. Helicobacter pylori (H. pylori) is one of the main risk factors for this type of neoplasia. Carcinogenetic mechanisms associated with H. pylori are based, on the one hand, on the onset of chronic inflammation and, on the other hand, on bacterial-specific virulence factors that can damage the DNA of gastric epithelial cells and promote genomic instability. Here, we review and discuss the major pathogenetic mechanisms by which H. pylori infection contributes to the onset and development of gastric cancer.

Frail Phenotype in Patients With Inflammatory Bowel Disease.

BACKGROUND: Recent retrospective studies have shown that frailty is common in hospitalized patients with inflammatory bowel disease (IBD) and enhances the risk of drug-related infections, postsurgery complications, hospital readmissions, and mortality, independently of age and comorbidities. We carried out a descriptive cohort study to evaluate the frequency of frail phenotype in IBD and analyzed the risk factors associated with this condition. METHODS: Frail phenotype was assessed in IBD patients by using the Fried frailty phenotype. Univariate and multivariate analyses were conducted to assess the risk factors for frail phenotype. Serum levels of interleukin (IL)-6 were quantified in patients with a frail or a fit phenotype by ELISA. RESULTS: Three hundred eighty-six IBD outpatients (198 Crohn's disease and 188 ulcerative colitis) were prospectively enrolled from December 2021 to April 2022. Frail phenotype was diagnosed in 64 of 386 (17%) IBD patients and was significantly associated with female gender, active disease, and current use of steroids. Multivariate analysis showed that active disease was a risk factor for frail phenotype (odds ratio, 11.5; 95% confidence interval, 3.9-33.9). No difference in IL-6 serum levels was seen between patients with a frail phenotype and those who were fit. CONCLUSIONS: This is the first prospective study showing that frail phenotype occurs in nearly one-fifth of IBD patients. Data indicate that active IBD is an independent risk factor for frail phenotype in IBD.

In IBD, frailty has been associated with enhanced risk of adverse outcomes. In this prospective study, nearly one-fifth of IBD patients were frail, and active disease was an independent risk factor for the frail phenotype.

Endoscopic Predictors of Neoplastic Lesions in Inflammatory Bowel Diseases Patients Undergoing Chromoendoscopy.

Dye-based chromoendoscopy (DCE) with targeted biopsies is recommended for surveillance of patients with long-standing inflammatory bowel diseases (IBD), but endoscopic features that predict dysplasia are not fully clarified. We here aimed at identifying predictive factors of dysplastic/neoplastic lesions in IBD patients undergoing DCE. Two-hundred-and-nineteen patients were consecutively and prospectively enrolled from October 2019 to March 2022. One-hundred-and-forty-five out of 219 patients underwent DCE, and 148 lesions were detected in 79/145 (54%) patients. Thirty-nine lesions (26%) were dysplastic and one of them contained a CRC. Among these lesions, 7 (17.9%) had Kudo pit pattern I-II and 32 (82.1%) had a neoplastic pit pattern (Kudo III-IV). Multivariate analysis showed that neoplastic lesions Kudo III-IV (OR: 5.8, 95% CI: 2.3−14.6; p = 0.0002), lesion's size (OR 1.16, 95% CI: 1.06−1.26; p = 0.0009), and polypoid lesions according to Paris Classification (OR 7.4, 95% CI: 2.7−20.2; p = 0.0001) were independent predictors of dysplasia. A cut-off of lesion's size > 7 mm was identified as the best predictor of dysplasia. Among such features, Kudo pit pattern III-IV had the highest sensitivity and specificity to predict dysplasia (79% and 80%, respectively). Lesions with all three endoscopic features had a sensitivity of 90% and specificity of 100% to predict dysplasia. In contrast, non-polypoid lesions were inversely associated with dysplasia (OR 0.13, 95% CI: 0.05−0.36; p = 0.0001). These findings indicate that, in IBD patients, DCE-evidenced polypoid lesions with Kudo pit pattern III-IV and size > 7 mm are frequently dysplastic.

MicroRNAs as Innovative Biomarkers for Inflammatory Bowel Disease and Prediction of Colorectal Cancer.

Inflammatory bowel disease (IBD) includes ulcerative colitis (UC) and Crohn's disease (CD). These are autoimmune diseases of the gastrointestinal tract with a chronic relapsing and remitting course. Due to complex interactions between multiple factors in the etiology of IBD, the discovery of new predictors of disease course and response to therapy, and the development of effective therapies is a significant challenge. The dysregulation of microRNAs (miRNAs), a class of conserved endogenous, small non-coding RNA molecules with a length of 18-25 nucleotides, that regulate gene expression by an RNA interference process, is implicated in the complex pathogenetic context of IBD. Both tissue-derived, circulating, and fecal microRNAs have been explored as promising biomarkers in the diagnosis and the prognosis of disease severity of IBD. In this review, we summarize the expressed miRNA profile in blood, mucosal tissue, and stool and highlight the role of miRNAs as biomarkers with potential diagnostic and therapeutic applications in ulcerative colitis and Crohn's disease. Moreover, we discuss the new perspectives in developing a new screening model for the detection of colorectal cancer (CRC) based on fecal miRNAs.

Targeting IL-34/MCSF-1R Axis in Colon Cancer.

Colorectal carcinoma (CRC) is one of the most common neoplasias in the Western world and it is still one of the most deadly cancers worldwide mainly due to the fact that metastatic CRC is not responsive to current pharmacologic treatment. Identification of pathways that sustain CRC cell behaviour could help develop effective therapeutic compounds. A large body of evidence indicates that colon carcinogenesis is a dynamic process in which multiple cell types present in the tumor microenvironment either stimulate or suppress CRC cell growth, survival, and diffusion mainly via the production of cytokines. Interleukin-34 (IL-34), a cytokine initially known for its ability to regulate monocyte/macrophage survival and function, is highly produced in human CRC by both cancer cells and non-tumoral cells. IL-34 function is mainly mediated by interaction with the macrophage colony-stimulating factor-1 receptor (MCSF-1R), which is also over-expressed by CRC cells as well as by tumour-associated macrophages (TAMs) and cancer-associated fibroblasts. IL-34-driven MCSF-1R activation triggers several pro-tumoral functions in the colon. In this article, we review the current understanding of the involvement of IL-34 and its receptor in CRC, with particular attention to the available evidence about the IL-34/MCSF-1R axis-mediated regulation of TAMs and the role of IL-34 and MCSF-1R in promoting cancer resistance to chemotherapy and immunotherapy. Manuscript Contribution to the Field: In this review, we highlight the multiple effects of IL-34 and its receptor, macrophage colony-stimulating factor-1 receptor, on the activity of colorectal cancer (CRC) cells and non-tumoral cells, with particular attention to the available data supporting the role of IL-34/MCSF-1R axis in the control of tumor-associated macrophages. The findings summarized in this manuscript could help understand whether targeting IL-34/MCSF-1R can be exploited for therapeutic intervention in CRC.

Smad7 Antisense Oligonucleotide-Based Therapy in Crohn's Disease: Is it Time to Re-Evaluate?

Abundant preclinical work showed that in Crohn's disease (CD), the defective activity of the immunosuppressive cytokine tumor necrosis factor (TGF)-ß1 due to high levels of the intracellular inhibitor Smad7 contributes to amplify the tissue-damaging inflammatory response. Consistently, phase I and II studies documented clinical and endoscopic benefit in active CD patients treated with mongersen, an oral antisense oligonucleotide targeting Smad7. However, a multicenter, randomized, double-blind, placebo-controlled, phase III study was prematurely discontinued as a futility analysis showed that mongersen was not effective in CD patients. The reasons why the phase III study failed despite the fact that previous clinical trials documented the efficacy of the drug remain unknown. The primary objective of this Viewpoint was to provide clues about the factors explaining discrepancies among the clinical trials. We illustrate the recent data indicating that the various batches of mongersen, used during the phase III program, are chemically different, with some of them being unable to downregulate Smad7 expression. Overall, these findings suggest the necessity of new clinical studies to further evaluate the efficacy of chemically homogenous batches of mongersen in patients with inflammatory bowel diseases (IBDs), and, at the same time, they can help understand the failure of other clinical trials with antisense oligonucleotides in IBD (i.e. alicaforsen).

Interleukin-34 Mediates Cross-Talk Between Stromal Cells and Immune Cells in the Gut.

Initially known as a cytokine produced by and regulating the function of monocytes and macrophages, interleukin-34 (IL-34) can be synthesized by many cell types and interacts with receptors expressed by multiple immune and non-immune cells. IL-34 is constitutively expressed in the healthy human small intestine and colon and its production is markedly increased in damaged gut of patients with Crohn's disease and patients with ulcerative colitis, the main forms of chronic inflammatory bowel diseases (IBD) in human beings. Circumstantial evidence suggests that, in these pathologies, IL-34 plays a crucial role in mediating cross-talk between immune cells and stromal cells, thereby promoting activation of signalling pathways, which amplify the ongoing mucosal inflammation as well as production of fibrogenic molecules. In this article, we summarize the available data supporting the multiple effects of IL-34 in human IBD with particular attention to the role of the cytokine in immune and stromal cell interactions.