New Insights into the Exosome-Induced Migration of Uveal Melanoma Cells and the Pre-Metastatic Niche Formation in the Liver.

UM is an aggressive intraocular tumor characterized by high plasticity and a propensity to metastasize in the liver. However, the underlying mechanisms governing liver tropism remain poorly understood. Given the emerging significance of exosomes, we sought to investigate the contribution of UM-derived exosomes to specific steps of the metastatic process. Firstly, we isolated exosomes from UM cells sharing a common genetic background and different metastatic properties. A comparison of protein cargo reveals an overrepresentation of proteins related to cytoskeleton remodeling and actin filament-based movement in exosomes derived from the parental cells that may favor the detachment of cells from the primary site. Secondly, we assessed the role of macrophages in reprogramming the HHSCs by exosomes. The activation of HHSCs triggered a pro-inflammatory and pro-fibrotic environment through cytokine production, upregulation of extracellular matrix molecules, and the activation of signaling pathways. Finally, we found that activated HHSCs promote increased adhesion and migration of UM cells. Our findings shed light on the pivotal role of exosomes in pre-metastatic niche construction in the liver.

Orthotopic murine xenograft model of uveal melanoma with spontaneous liver metastasis.

Uveal melanoma is the most common intraocular malignancy in adults. Despite the effective primary treatment, up to 50% of patients with uveal melanoma will develop metastatic lesions mainly in the liver, which are resistant to conventional chemotherapy and lead to patient's death. To date, no orthotopic murine models of uveal melanoma which can develop spontaneous metastasis are available for preclinical studies. Here, we describe a spontaneous metastatic model of uveal melanoma based on the orthotopic injection of human uveal melanoma cells into the suprachoroidal space of immunodeficient NSG mice. All mice injected with bioluminescent OMM2.5 ( n = 23) or MP41 ( n = 19) cells developed a primary tumor. After eye enucleation, additional bioluminescence signals were detected in the lungs and in the liver. At necropsy, histopathological studies confirmed the presence of lung metastases in 100% of the mice. Liver metastases were assessed in 87 and in 100% of the mice that received OMM2.5 or MP41 cells, respectively. All tumors and metastatic lesions expressed melanoma markers and the signaling molecules insulin-like growth factor type I receptor and myristoylated alanine-rich C-kinase substrate, commonly activated in uveal melanoma. The novelty of this orthotopic mouse xenograft model is the development of spontaneous metastases in the liver from the primary site, reproducing the organoespecificity of metastasis observed in uveal melanoma patients. The faster growth and the high metastatic incidence may be attributed at least in part, to the severe immunodeficiency of NSG mice. This model may be useful for preclinical testing of targeted therapies with potential uveal melanoma antimetastatic activity and to study the mechanisms involved in liver metastasis.

The Genetic Diversity and Dysfunctionality of Catalase Associated with a Worse Outcome in Crohn's Disease.

Chronic gut inflammation in Crohn's disease (CD) is associated with an increase in oxidative stress and an imbalance of antioxidant enzymes. We have previously shown that catalase (CAT) activity is permanently inhibited by CD. The purpose of the study was to determine whether there is any relationship between the single nucleotide polymorphisms (SNPs) in the CAT enzyme and the potential risk of CD associated with high levels of oxidative stress. Additionally, we used protein and regulation analyses to determine what causes long-term CAT inhibition in peripheral white mononuclear cells (PWMCs) in both active and inactive CD. We first used a retrospective cohort of 598 patients with CD and 625 age-matched healthy controls (ENEIDA registry) for the genotype analysis. A second human cohort was used to study the functional and regulatory mechanisms of CAT in CD. We isolated PWMCs from CD patients at the onset of the disease (naïve CD patients). In the genotype-association SNP analysis, the CAT SNPs rs1001179, rs475043, and rs525938 showed a significant association with CD (p < 0.001). Smoking CD patients with the CAT SNP rs475043 A/G genotype had significantly more often penetrating disease (p = 0.009). The gene expression and protein levels of CAT were permanently reduced in the active and inactive CD patients. The inhibition of CAT activity in the PWMCs of the CD patients was related to a low concentration of CAT protein caused by the downregulation of CAT-gene transcription. Our study suggests an association between CAT SNPs and the risk of CD that may explain permanent CAT inhibition in CD patients together with low CAT gene and protein expression.

Transcriptomic identification of TMIGD1 and its relationship with the ileal epithelial cell differentiation in Crohn's disease.

Crohn's disease (CD) is a complex and multifactorial illness. There are still considerable gaps in our knowledge regarding its pathophysiology. A transcriptomic approach could shed some light on little-known biological alterations of the disease. We therefore aimed to explore the ileal transcriptome to gain knowledge about CD. We performed whole transcriptome gene expression analysis on ileocecal resections from CD patients and inflammatory bowel disease-free controls, as well as on a CD-independent cohort to replicate selected results. Normalized data were hierarchically clustered, and gene ontology and the molecular network were studied. Cell cultures and molecular methods were used for further evaluations. Genome-wide expression data analysis identified a robust transmembrane immunoglobulin domain-containing 1 (TMIGD1) gene underexpression in CD tissue, which was even more marked in inflamed ileum, and which was replicated in the validation cohort. Immunofluorescence showed TMIGD1 to be located in the apical microvilli of well-differentiated enterocytes but not in intestinal crypt. This apical TMIGD1 was lower in the noninflamed tissue and almost disappeared in the inflamed mucosa of surgical resections. In vitro studies showed hypoxic-dependent TMIGD1 decreased its expression in enterocyte-like cells. The gene enrichment analysis linked TMIGD1 with cell recovery and tissue remodeling in CD settings, involving guanylate cyclase activities. Transcriptomics may be useful for finding new targets that facilitate studies of the CD pathology. This is how TMIGD1 was identified in CD patients, which was related to multiciliate ileal epithelial cell differentiation.NEW & NOTEWORTHY This is a single-center translational research study that aimed to look for key targets involved in Crohn's disease and define molecular pathways through different functional analysis strategies. With this approach, we have identified and described a novel target, the almost unknown TMIGD1 gene, which may be key in the recovery of injured mucosa involving intestinal epithelial cell differentiation.

Adalimumab or Infliximab for the Prevention of Early Postoperative Recurrence of Crohn Disease: Results From the ENEIDA Registry.

BACKGROUND: Anti-tumor necrosis factor agents (anti-TNFs) are efficacious at preventing the postoperative recurrence (POR) of Crohn disease, as demonstrated in 2 randomized controlled trials. However, real-life data for infliximab or adalimumab in this setting are scarce. Our aim was to assess both the efficiency of anti-TNFs at preventing early POR of Crohn disease in clinical practice and the associated risk factors for POR. METHODS: Patients in whom anti-TNFs were prescribed for the prevention of POR within 3 months after ileocolonic resection and who had an endoscopic assessment within 18 months were identified from the ENEIDA registry. Clinical and endoscopic features were collected within 18 months after surgery. RESULTS: In total, 152 patients were included (55 treated with infliximab, 97 with adalimumab, and 39% with concomitant immunosuppressants). Anti-TNF treatment was started after a median time of 29 days (IQR 13-44) after surgery. Eighty-two percent of patients had at least one risk factor for POR, and 82% had been exposed to anti-TNFs before the index surgery. Overall, 34% had endoscopic POR (as defined using a Rutgeerts endoscopic score > i1); 14% had advanced endoscopic POR (>i2); and 20% had clinical POR, with no differences between infliximab and adalimumab. In the multivariate analysis, only perianal disease (odds ratio 2.73, 95% confidence interval [CI] 1.26-5.91) and rectal involvement (odds ratio 2.79, 95% CI 1.09-7.14) were independent predictors of endoscopic POR. CONCLUSIONS: In clinical practice, anti-TNFs for the prevention of POR of Crohn disease are frequently used in patients experienced with anti-TNFs and with concomitant immunosuppressants. The efficacy of infliximab and adalimumab for POR prevention is similar and in accordance with the results obtained in randomized controlled trials.

Nivolumab-induced immune-mediated colitis: an ulcerative colitis look-alike-report of new cases and review of the literature.

PURPOSE: Nivolumab, a monoclonal antibody-targeting programmed cell death protein-1, is being increasingly used for the treatment of some advanced neoplasms. Several of its adverse effects are a result of the upregulation of T cells, with colitis as one of the most severe, and a challenging differential diagnosis with ulcerative colitis. However, few real-life clinical practice cases have been reported beyond trials. Our aim was to report a series of new cases, reviewing previously communicated endoscopic-proven nivolumab-induced colitis. METHOD: All patients treated with nivolumab in three university centers were identified and those who developed immune-mediated colitis (defined as the presence of diarrhea and evidence of colitis demonstrated by colonoscopy) were described. Additionally, a review of case reports of nivolumab-induced colitis reported in the literature up to March 2018 was performed. RESULTS: Six new cases of nivolumab-induced colitis and 13 previously reported cases out of randomized clinical trials are described. Colonoscopy showed a mucosal pattern mimicking ulcerative colitis in a large proportion of patients. Clostridium difficile superinfection was observed in two out of 19 cases. All but three patients definitively discontinued nivolumab therapy. Most patients were initially managed with oral or intravenous corticosteroids, but five of them required rescue therapy with infliximab. CONCLUSIONS: Nivolumab-induced colitis may mimic ulcerative colitis. Steroid therapy (oral or intravenously) is often efficient, but one-fourth of patients need rescue therapy with anti-TNF. Intestinal superinfection with Clostridium difficile or cytomegalovirus should be ruled out before starting immunosuppressive therapy.

Characteristics of inflammatory bowel disease in patients of Roma/Gypsy ethnicity. A case-control study.

BACKGROUND: Peculiarities of inflammatory bowel disease (IBD) have been explored in ethnic groups, such as Asians, Hispanics, and Afro-Americans, but not in other ethnic minorities, such as Roma/Gypsies. METHODS: In a retrospective, hospital-based study, all adult Roma/Gypsy patients included in the IBD databases of seven Spanish centres were identified as cases. For each Roma/Gypsy patient, a Caucasian patient, matched for several demographic features, was searched as a control. Data on phenotypic features, therapeutic requirements, and familial aggregation were recorded. RESULTS: Sixty-eight Roma/Gypsy patients were identified, 29 of them being women. The mean age at diagnosis of IBD was 24.9±9.5years, and the mean time elapsed since diagnosis was 96.6±72.2months. Roma/Gypsy IBD patients showed a significantly higher rate of familial aggregation (43%) than their Caucasian controls (9%) (p=0.00001). CD in Roma/Gypsies had more often a complicated pattern (mainly penetrating) while UC patients showed a marked trend to more often developing extraintestinal manifestations. In addition, Roma/Gypsy IBD patients had a somewhat greater need for immunosuppressants, biological agents or surgery. CONCLUSIONS: These are the first data on IBD in Roma/Gypsy patients. Familial aggregation is the most prominent feature in these patients, suggesting a predominant role of genetics in its pathogenesis.

Prognostic Value of the Burden of Cytomegalovirus Colonic Reactivation Evaluated by Immunohistochemical Staining in Patients with Active Ulcerative Colitis.

BACKGROUND: Colonic cytomegalovirus [CMV] reactivation has been involved in steroid refractoriness in patients with active ulcerative colitis [UC]. The benefits of antiviral therapy in this clinical setting are still under debate, but the burden of viral reactivation has been associated with a poorer outcome in some studies. Our aim was to assess whether the burden of CMV reactivation measured by the number of viral inclusions by immunohistochemistry [IHC-CMV] is associated with a risk of colectomy. METHODS: Biopsy sets of UC patients with positive IHC-CMV were identified from the Pathology departments of three university hospitals. All biopsies were reviewed by expert pathologists, and the maximum number of IHC-CMV-positive cells in each biopsy set was re-assessed. Epidemiological and clinical features and clinical outcomes were recorded. RESULTS: Forty-six positive IHC-CMV cases with UC were included. At the time of CMV reactivation, 70% were receiving corticosteroids, 33% azathioprine, and 24% anti-tumour necrosis factor [TNF] agents. Thirty-two patients [70%] were treated with antiviral therapy. The median number of IHC-CMV-positive cells was 2 cells/biopsy [IQR 1-4]. Fourteen patients [30%] underwent colectomy, and 4 of them [29%] showed persistence of CMV in the surgical specimen. In the multivariate analysis, colectomy was only associated with >2 positive cells/biopsy [p = 0.048] and younger age [p = 0.023]. CONCLUSIONS: The burden of CMV colonic reactivation in patients with active UC, as measured by IHC, seems to be related to the risk of colectomy, and more data is needed to understand whether antiviral therapy guided by CMV burden will alter the clinical outcome.

Review article: the relationship between obesity, bariatric surgery, and inflammatory bowel disease.

BACKGROUND: The convoluted relationship between obesity, bariatric surgery and inflammatory bowel disease (IBD) is of increasing interest. AIM: To analyse evidence regarding the role of bariatric surgery in the development of de novo IBD and its impact on clinical outcomes and safety in patients with established IBD. METHODS: A PubMed/Medline search was performed to identify studies reporting the development of IBD after bariatric surgery and the outcomes of IBD patients after bariatric surgery. RESULTS: Eighty patients were reported to have developed de novo IBD after bariatric surgery (21% ulcerative colitis [UC], 75% Crohn's disease [CD]), mostly females. Roux-en-Y gastric bypass was the most frequent bariatric technique (80%). Symptoms related to IBD occurred within 1 month and 16 years after surgery. Regarding patients with known IBD undergoing bariatric surgery, 60 patients (35 CD, 24 UC, and 1 unclassified colitis) have been reported. Sleeve gastrectomy was the most frequent bariatric procedure, particularly in CD patients. Acute flares after surgery were observed in only four UC patients. In addition, two retrospective population-based studies described perioperative outcomes of bariatric surgery on IBD patients, demonstrating only a significant increase in small bowel obstruction in these patients. CONCLUSIONS: Bariatric surgery in carefully selected patients with established IBD is technically feasible and probably safe. Development of de novo IBD should be taken into account in individuals with previous bariatric surgery who develop diarrhoea, anaemia or excessive weight loss.

Prevalence and risk factors for colorectal adenomas in patients with ulcerative colitis.

BACKGROUND: Patients with ulcerative colitis (UC) have an increased risk of colorectal cancer. Scarce data regarding the development of adenomas in these patients are available both for normal and colitic mucosa. OBJECTIVE: The objective of this article is to evaluate the prevalence of adenomatous polyps and associated risk factors in patients with UC. METHODS: Patients with UC were identified from the databases of two tertiary referral centers. Medical, endoscopic and histologic reports were reviewed. RESULTS: A total of 403 patients were included (53% male; 33% extensive colitis) and 1065 colonoscopies (median per patient, 2) were recorded and analyzed. Seventy-four adenomas in 47 patients (11.7%) and three cases of colorectal cancer were found during a median follow-up of 6.3 years. The cumulative risk of colorectal adenoma was 4.7%, 16.7%, 23.6% and 34.4% at 10, 20, 30 and 40 years from UC diagnosis, respectively. The cumulative risk of developing metachronous colorectal adenoma was 66.7%, 87.9%, and 90.9% at 5, 10, and 15 years from first adenoma detection. Older age at UC diagnosis and longer disease duration were independent risk factors for colorectal adenoma development. CONCLUSIONS: The prevalence of colorectal adenomas among UC patients seems to be higher than previously reported, although lower than in the background population.