Post-transplant Inflammatory Bowel Disease Associated with Donor-Derived TIM-3 Deficiency.

Inflammatory bowel disease (IBD) occurring following allogeneic stem cell transplantation (aSCT) is a very rare condition. The underlying pathogenesis needs to be better defined. There is currently no systematic effort to exclude loss- or gain-of-function mutations in immune-related genes in stem cell donors. This is despite the fact that more than 100 inborn errors of immunity may cause or contribute to IBD. We have molecularly characterized a patient who developed fulminant inflammatory bowel disease following aSCT with stable 100% donor-derived hematopoiesis. A pathogenic c.A291G; p.I97M HAVCR2 mutation encoding the immune checkpoint protein TIM-3 was identified in the patient's blood-derived DNA, while being absent in DNA derived from the skin. TIM-3 expression was much decreased in the patient's serum, and in vitro-activated patient-derived T cells expressed reduced TIM-3 levels. In contrast, T cell-intrinsic CD25 expression and production of inflammatory cytokines were preserved. TIM-3 expression was barely detectable in the immune cells of the patient's intestinal mucosa, while being detected unambiguously in the inflamed and non-inflamed colon from unrelated individuals. In conclusion, we report the first case of acquired, "transplanted" insufficiency of the regulatory TIM-3 checkpoint linked to post-aSCT IBD.

Surface protein and functional analyses identify CD4+CD39+ TCR αß+ and activated TCR Vδ1+ cells with distinct pro-inflammatory functions in Crohn's disease lesions.

Crohn's disease (CD) is a chronic immune-mediated disorder of the gastrointestinal tract. Extensive screening studies have revealed the accumulation of immune cell subsets with unique plasticity and immunoregulatory properties in patients with CD. We performed phenotypic and functional studies on inflamed and non-inflamed bioptic tissue to investigate the presence of distinct T cells in the intestinal mucosa of CD patients. We analysed hundreds of surface molecules expressed on cells isolated from the intestinal tissue of CD patients using anti-CD45 mAbs-based barcoding. A gene ontology enrichment analysis showed that proteins that regulate the activation of T cells were the most enriched group. We, therefore, designed T-cell focused multicolour flow-cytometry panels and performed clustering analysis which revealed an accumulation of activated TEM CD4+CD39+ T cells producing IL-17 and IL-21 and increased frequency of terminally differentiated TCR Vδ1+ cells producing TNF-α and IFN-γ in inflamed tissue of CD patients. The different functional capacities of CD4+ and TCR Vδ1+ cells in CD lesions indicate their non-overlapping contribution to inflammation. The abnormally high number of terminally differentiated TCR Vδ1+ cells suggests that they are continuously activated in inflamed tissue, making them a potential target for novel therapies.

[Chronic inflammatory bowel disease in elderly people].

INTRODUCTION: Inflammatory bowel disease is mainly diagnosed in younger patients. However, the number of elderly patients (age > 60 years) affected by Crohn's disease or ulcerative colitis is increasing. In the elderly, symptoms often differ from the younger population. Older patients generally present a milder clinical course and are less often affected by extraintestinal disease activity. Treatment options are similar to the ones in younger patients. Due to the higher risk of drug interactions and side effects, comorbidities and comedication of the older patients play a pivotal role in the selection of the specific treatment agent. In therapy refractory disease, surgical treatment is also a valuable option for patients > 60 years. Furthermore, vaccination, prevention of infections and regular cancer screening is mandatory in this vulnerable population.

Multidisciplinary recommendations for essential baseline functional and laboratory tests to facilitate early diagnosis and management of immune-related adverse events among cancer patients.

Immune checkpoint inhibitors (ICIs) have fundamentally changed the treatment landscape of various cancers. While ICI treatments result in improved survival, quality of life and are cost-effective, the majority of patients experience at least one immune-related adverse event (irAE). Many of these side effects cause little discomfort or are asymptomatic; however, irAEs can affect any organ and are potentially life-threatening. Consequently, early diagnosis and appropriate treatment of irAEs are critical for optimizing long-term outcomes and quality of life in affected patients. Some irAEs are diagnosed according to typical symptoms, others by abnormal findings from diagnostic tests. While there are various guidelines addressing the management of irAEs, recommendations for the early recognition of irAEs as well as the optimal extent and frequency of laboratory tests are mostly lacking. In clinical practice, blood sampling is usually performed before each ICI administration (i.e., every 2-3 weeks), often for several months, representing a burden for patients as well as health care systems. In this report, we propose essential laboratory and functional tests to improve the early detection and management of irAEs and in cancer patients treated with ICIs. These multidisciplinary expert recommendations regarding essential laboratory and functional tests can be used to identify possible irAEs at an early time point, initiate appropriate interventions to improve patient outcomes, and reduce the burden of blood sampling during ICI treatment.

AXL Expression on Homeostatic Resident Liver Macrophages Is Reduced in Cirrhosis Following GAS6 Production by Hepatic Stellate Cells.

BACKGROUND & AIMS: AXL and MERTK expression on circulating monocytes modulated immune responses in patients with cirrhosis (CD14+HLA-DR+AXL+) and acute-on-chronic liver failure (CD14+MERTK+). AXL expression involved enhanced efferocytosis, sustained phagocytosis, but reduced tumor necrosis factor-α/interleukin-6 production and T-cell activation, suggesting a homeostatic function. Axl was expressed on murine airway in tissues contacting the external environment, but not interstitial lung- and tissue-resident synovial lining macrophages. Here, we assessed AXL expression on tissue macrophages in patients with cirrhosis. METHODS: Using multiplexed immunofluorescence we compared AXL expression in liver biopsies in cirrhosis (n = 22), chronic liver disease (n = 8), non-cirrhotic portal hypertension (n = 4), and healthy controls (n = 4). Phenotype and function of isolated primary human liver macrophages were characterized by flow cytometry (cirrhosis, n = 11; control, n = 14) ex vivo. Also, AXL expression was assessed on peritoneal (n = 29) and gut macrophages (n = 16) from cirrhotic patients. Regulation of AXL expression was analyzed in vitro and ex vivo using primary hepatic stellate cells (HSCs), LX-2 cells, and GAS6 in co-culture experiments. RESULTS: AXL was expressed on resident (CD68+) but not tissue-infiltrating (MAC387+) liver macrophages, hepatocytes, HSCs, or sinusoidal endothelial cells. Prevalence of hepatic CD68+AXL+ cells significantly decreased with cirrhosis progression: (healthy, 90.2%; Child-Pugh A, 76.1%; Child-Pugh B, 64.5%; and Child-Pugh C, 18.7%; all P < .05) and negatively correlated with Model for End-Stage Liver Disease and C-reactive protein (all P < .05). AXL-expressing hepatic macrophages were CD68highHLA-DRhighCD16highCD206high. AXL expression also decreased on gut and peritoneal macrophages from cirrhotic patients but increased in regional lymph nodes. GAS6, enriched in the cirrhotic liver, appeared to be secreted by HSCs and down-regulate AXL in vitro. CONCLUSIONS: Decreased AXL expression on resident liver macrophages in advanced cirrhosis, potentially in response to activated HSC-secreted GAS6, suggests a role for AXL in the regulation of hepatic immune homeostasis.

Targeting colonic macrophages improves glycemic control in high-fat diet-induced obesity.

The obesity epidemic continues to worsen worldwide. However, the mechanisms initiating glucose dysregulation in obesity remain poorly understood. We assessed the role that colonic macrophage subpopulations play in glucose homeostasis in mice fed a high-fat diet (HFD). Concurrent with glucose intolerance, pro-inflammatory/monocyte-derived colonic macrophages increased in mice fed a HFD. A link between macrophage numbers and glycemia was established by pharmacological dose-dependent ablation of macrophages. In particular, colon-specific macrophage depletion by intrarectal clodronate liposomes improved glucose tolerance, insulin sensitivity, and insulin secretion capacity. Colonic macrophage activation upon HFD was characterized by an interferon response and a change in mitochondrial metabolism, which converged in mTOR as a common regulator. Colon-specific mTOR inhibition reduced pro-inflammatory macrophages and ameliorated insulin secretion capacity, similar to colon-specific macrophage depletion, but did not affect insulin sensitivity. Thus, pharmacological targeting of colonic macrophages could become a potential therapy in obesity to improve glycemic control.

High Serum Creatine Kinase Levels in Infliximab and Vedolizumab-Treated Inflammatory Bowel Disease Patients.

BACKGROUND: TNF inhibitors are relatively safe drugs, but asymptomatic infliximab-induced high serum creatine kinase (CK) levels have been reported in >30% of patients with inflammatory bowel disease (IBD). Whether high serum CK levels are a specific effect of treatment with TNF inhibitors has not been studied in detail. CK levels were therefore compared between infliximab- and vedolizumab-treated IBD patients. METHODS: In this retrospective, monocentric study, 131 IBD cases (82 with Crohn's disease (CD), 49 with ulcerative colitis) of the Basel University Hospital IBD cohort treated either with infliximab or vedolizumab were included. Serum samples for measuring CK, lactate dehydrogenase (LDH), C-reactive protein (CRP), and fecal calprotectin (FCal) levels were collected longitudinally and analyzed using mixed additive models. RESULTS: No significant differences in CK levels between infliximab and vedolizumab-treated patients were observed over time. Infliximab-treated males, however, showed significantly higher CK levels than females and former smokers treated with infliximab showed significantly lower CK levels than nonsmokers. No such differences were observed in vedolizumab-treated patients. LDH and CRP were not significantly different between infliximab- and vedolizumab-treated patients, while adjusted groups showed substantially higher LDH levels with increasing age and significantly lower LDH levels in patients with longer disease duration. Infliximab patients with CD showed significantly lower CRP. However, significantly higher FCal concentrations were noted in infliximab patients independent of diagnosis, gender, disease duration, smoking behavior, and age. CONCLUSION: In our cohort, high serum CK levels are not an infliximab- or vedolizumab-specific effect.

Obesity in Humans Is Characterized by Gut Inflammation as Shown by Pro-Inflammatory Intestinal Macrophage Accumulation.

Chronic low-grade inflammation is a hallmark of obesity and associated with cardiovascular complications. However, it remains unclear where this inflammation starts. As the gut is constantly exposed to food, gut microbiota, and metabolites, we hypothesized that mucosal immunity triggers an innate inflammatory response in obesity. We characterized five distinct macrophage subpopulations (P1-P5) along the gastrointestinal tract and blood monocyte subpopulations (classical, non-classical, intermediate), which replenish intestinal macrophages, in non-obese (BMI<27kg/m2) and obese individuals (BMI>32kg/m2). To elucidate factors that potentially trigger gut inflammation, we correlated these subpopulations with cardiovascular risk factors and lifestyle behaviors. In obese individuals, we found higher pro-inflammatory macrophages in the stomach, duodenum, and colon. Intermediate blood monocytes were also increased in obesity, suggesting enhanced recruitment to the gut. We identified unhealthy lifestyle habits as potential triggers of gut and systemic inflammation (i.e., low vegetable intake, high processed meat consumption, sedentary lifestyle). Cardiovascular risk factors other than body weight did not affect the innate immune response. Thus, obesity in humans is characterized by gut inflammation as shown by accumulation of pro-inflammatory intestinal macrophages, potentially via recruited blood monocytes. Understanding gut innate immunity in human obesity might open up new targets for immune-modulatory treatments in metabolic disease.

Factors influencing the outcome of vedolizumab treatment: Real-life data with objective outcome measurements.

BACKGROUND: Vedolizumab (VDZ), a humanised monoclonal antibody against a4ß7-integrin, has shown efficacy in inflammatory bowel disease (IBD). It is of importance to assess the mid-to long-term efficacy of VDZ using real-life data. OBJECTIVE: Our study aimed to determine the efficacy of VDZ in patients with IBD with and without prior exposure to anti-tumour necrosis factor (TNF) treatments in a real-life setting. Furthermore, we investigated confounding factors influencing the remission to VDZ. METHODS: Patients participating in the Swiss IBD Cohort Study were included in this study. Remission was defined as calprotectin less than 200 mg/kg stool and/or mucosal healing determined by endoscopy. End points were determined between Months 4 and 8 (T1) and between Months 12 and 16 (T2) after VDZ induction. RESULTS: Remission was reported in 50.5% (110/218) of patients in T1 (48.7% Crohn's disease [CD] and 52.5% ulcerative colitis [UC]) and 46.8% (102/218) in T2 (47% CD and 46.5% UC). In UC patients, a significantly higher remission rate was achieved in T2 among anti-TNF-naive patients (57.7%) compared to anti-TNF-experienced patients (34.7%; p = 0.02; odds ratio = 0.39, 95% confidence interval: 0.17-0.87). In patients with CD, no difference could be seen in either evaluation interval. Multivariable analysis showed that disease duration significantly influenced remission rates among UC patients. A late response to VDZ therapy with an achievement of remission in T2 was seen in a fifth of all patients (CD: 21.7%, UC: 20.8%). VDZ treatment was stopped in a third of all patients (31.8%) due to nonresponse, adverse events or aggravation of extra-intestinal manifestations. CONCLUSION: In a real-life national cohort setting, VDZ induced remission in more than half of IBD patients. Previous treatment with anti-TNF agents was associated with a significant lower efficacy of VDZ in UC but not in CD patients.

Lysophosphatidic Acid-Mediated GPR35 Signaling in CX3CR1+ Macrophages Regulates Intestinal Homeostasis.

Single-nucleotide polymorphisms in the gene encoding G protein-coupled receptor 35 (GPR35) are associated with increased risk of inflammatory bowel disease. However, the mechanisms by which GPR35 modulates intestinal immune homeostasis remain undefined. Here, integrating zebrafish and mouse experimental models, we demonstrate that intestinal Gpr35 expression is microbiota dependent and enhanced upon inflammation. Moreover, murine GPR35+ colonic macrophages are characterized by enhanced production of pro-inflammatory cytokines. We identify lysophosphatidic acid (LPA) as a potential endogenous ligand produced during intestinal inflammation, acting through GPR35 to induce tumor necrosis factor (Tnf) expression in macrophages. Mice lacking Gpr35 in CX3CR1+ macrophages aggravate colitis when exposed to dextran sodium sulfate, which is associated with decreased transcript levels of the corticosterone-generating gene Cyp11b1 and macrophage-derived Tnf. Administration of TNF in these mice restores Cyp11b1 expression and intestinal corticosterone production and ameliorates DSS-induced colitis. Our findings indicate that LPA signals through GPR35 in CX3CR1+ macrophages to maintain TNF-mediated intestinal homeostasis.

Loss of the branched-chain amino acid transporter CD98hc alters the development of colonic macrophages in mice.

Comprehensive development is critical for gut macrophages being essential for the intestinal immune system. However, the underlying mechanisms of macrophage development in the colon remain elusive. To investigate the function of branched-chain amino acids in the development of gut macrophages, an inducible knock-out mouse model for the branched-chain amino acid transporter CD98hc in CX3CR1+ macrophages was generated. The relatively selective deletion of CD98hc in macrophage populations leads to attenuated severity of chemically-induced colitis that we assessed by clinical, endoscopic, and histological scoring. Single-cell RNA sequencing of colonic lamina propria macrophages revealed that conditional deletion of CD98hc alters the "monocyte waterfall"-development to MHC II+ macrophages. The change in the macrophage development after deletion of CD98hc is associated with increased apoptotic gene expression. Our results show that CD98hc deletion changes the development of colonic macrophages.

Management of the Elderly Inflammatory Bowel Disease Patient.

Inflammatory bowel disease (IBD) is increasingly diagnosed among elderly persons (older than 60 years). Epidemiological studies show that late-onset IBD is characterized by predominance of colonic disease, milder disease course, and less frequent occurrence of extraintestinal manifestations. However, due to comorbidities, polypharmacy and reduced resistance to severe disease course elderly patients have an increased risk of mortality. Drug treatment generally follows the same algorithms as in the younger IBD patients. This is challenging for the treating physician as this population is usually underrepresented in clinical trials and treatment outcomes as well as safety data on the elderly population are scarce. Choice of drugs should consider risk of infections, skin cancer, lymphoma, and metabolic as well as cardiovascular side effects. Considering comorbidities, surgical interventions such as colectomy with ileo-anal pouch anastomosis for refractory ulcerative colitis can be performed safely provided that the anal sphincter function is adequately maintained. Special attention should be given in this age group to general health issues, including nutrition, vaccination, bone, muscle, and mental health as well as colorectal and skin cancer screening.

NLRP6 Deficiency in CD4 T Cells Decreases T Cell Survival Associated with Increased Cell Death.

The nucleotide-binding oligomerization domain (NOD)-like receptors belong to the family of pattern recognition receptors (PRRs). NOD-like receptors play a role in regulation of innate immune response by recognition of both pathogen-associated molecular patterns that are engulfed during phagocytic process and danger-associated molecular patterns that are mainly byproducts of cell stress mediated response. NOD-like family pyrin domain containing 6 (NLRP6) is one of the 14 pyrin domain-containing receptors. NLRP6 is highly expressed by epithelial and goblet cells to regulate epithelial renewal and mucus production in mice and humans, but its function in T cells is rather unknown. Increased caspase-1 activation and cell death were observed in mouse Nlrp6-deficient T cells following adoptive transfer into Rag2-deficient mice, indicating that Nlrp6 deficiency in CD4+ T cells led to decreased survival.

Eosinophilic Gastroenteritis: Clinical Manifestation, Natural Course, and Evaluation of Treatment with Corticosteroids and Vedolizumab.

BACKGROUND: Eosinophilic gastroenteritis (EGE) is a rare, chronic inflammatory condition of the gastrointestinal tract. Little is known about its natural history and treatment outcomes. The aims of our analysis were to describe clinical presentation, response to current medical treatments, and to evaluate the response of refractory EGE to anti-integrin therapy. METHODS: Patients with confirmed diagnosis of EGE fulfilling the diagnostic criteria: (1) the presence of gastrointestinal symptoms, (2) dense eosinophilic infiltration of the gastrointestinal mucosa, and (3) exclusion of other conditions leading to gastrointestinal eosinophilia were included in this analysis. In patients non-responding to corticosteroids and/or anti-TNF treatment the integrin blocker vedolizumab was used. RESULTS: EGE patients (n = 22) were predominantly female (63%) with a median age at diagnosis of 41.5 years. The most frequent symptoms were abdominal pain (100%), diarrhea (59%), nausea/vomiting (36%), and bloating (27%). No pathognomonic endoscopic alterations were found. Eosinophilic infiltration was observed in the majority of patients in more than one segment. Patients were treated with systemic steroids, topical, and enteral release steroids in 21/22 (95%) patients, proton pump inhibitors in 7/22 (32%), TNFα inhibitors in 3/22 (14%), and vedolizumab in 4/22 (18%) patients. In 3/4 of steroid-refractory patients vedolizumab induced a clinical and histological improvement. CONCLUSIONS: The combination of highly variable clinical presentation, subtle endoscopic abnormalities, and involvement of several GI segments undermines the difficulty to diagnose EGE and the need for structured biopsy sampling. Corticosteroids were efficient in the majority of patients to induce remission. Response to the integrin blocker vedolizumab suggests further assessment in refractory cases.

[The Role of the Exposome in the Emergence of Chronic Inflammatory Bowel Diseases]. / Die Rolle des Exposoms in der Entstehung von chronisch entzündlichen Darmkrankheiten.

The Role of the Exposome in the Emergence of Chronic Inflammatory Bowel Diseases Abstract. Inflammatory Bowel Disease (IBD) including Crohn's disease (CD) and ulcerative colitis (UC), are chronic inflammatory conditions of the gut related to a combination of genetic and environmental factors that impact on normal host-microbe interactions. The gastrointestinal tract is exposed to an overwhelming load of foreign antigens arising from commensal microorganisms, dietary products and occasional pathogens. But these factors explain only a small fraction of disease risk. During the last two decades advances in genomics, epigenomics and understanding of the intestinal microbiota have improved our knowledge in IBD pathogenesis. Although our ability to predict relapses and response to treatment remains limited, the importance of the external environment to modify the risk of IBD and to precipitate relapses in patients with established disease rises. The term 'exposome' is proposed to reflect a life-course of environmental influences beginning in-utero and proceeding right through childhood to adulthood. While the exposome is still a concept which needs practical perspective to enable better patient care, this review highlights important components of environmental contributors to improve our understanding on pathophysiologic mechanisms in IBD.

ß6 -integrin serves as a novel serum tumor marker for colorectal carcinoma.

Colorectal cancer (CRC) is one of the leading causes of cancer-related deaths worldwide and the need for novel biomarkers and therapeutic strategies to improve diagnosis and surveillance is obvious. This study aims to identify ß6 -integrin (ITGB6) as a novel serum tumor marker for diagnosis, prognosis, and surveillance of CRC. ITGB6 serum levels were validated in retro- and prospective CRC patient cohorts. ITGB6 serum levels were analyzed by ELISA. Using an initial cohort of 60 CRC patients, we found that ITGB6 is present in the serum of CRC, but not in non-CRC control patients. A cut-off of ≥2 ng/mL ITGB6 reveals 100% specificity for the presence of metastatic CRC. In an enlarged study cohort of 269 CRC patients, ITGB6 predicted the onset of metastatic disease and was associated with poor prognosis. Those data were confirmed in an independent, prospective cohort consisting of 40 CRC patients. To investigate whether ITGB6 can also be used for tumor surveillance, serum ITGB6-levels were assessed in 26 CRC patients, pre- and post-surgery, as well as during follow-up visits. After complete tumor resection, ITGB6 serum levels declined completely. During follow-up, a new rise in ITGB6 serum levels indicated tumor recurrence or the onset of new metastasis as confirmed by CT scan. ITGB6 was more accurate for prognosis of advanced CRC and for tumor surveillance as the established marker carcinoembryonic antigen (CEA). Our findings identify ITGB6 as a novel serum marker for diagnosis, prognosis, and surveillance of advanced CRC. This might essentially contribute to an optimized patient care.

High-dimensional single-cell proteomics analysis identifies immune checkpoint signatures and therapeutic targets in ulcerative colitis.

Immune checkpoints are regulators of immune cells and play key roles in the modulation of immune responses. The role of checkpoints in autoimmune disease is poorly understood but likely to be central since checkpoint inhibition during cancer treatment can cause autoimmunity. We generated a high-dimensional single-cell proteomics data set from PBMCs of healthy individuals and patients with ulcerative colitis (UC) by mass cytometry, enabling systems-wide analyses of immune cell frequencies and cell type-specific expression patterns of 12 immune checkpoints. Subtle but significant changes in immune cell frequencies and checkpoint expression were observed between UC patients on different treatment regimens and between patients and healthy controls. Most strikingly, UC patients showed a reduced number of peripheral NK-cells and those cells showed an altered phenotype including increased TIGIT expression. Based on these results, we modulated NK-cell function ex vivo through targeting of TIGIT pathway members. In summary, we describe a pattern of changes in immune cell abundance and checkpoint expression as a basis for UC patient stratification and we show modulation of a corresponding immune cell subset through checkpoint targeting. Our approach can be used for the identification of pathogenic immune cell subsets and guide target selection in autoimmunity and chronic inflammation.