Ulcerative colitis (UC) is a major form of inflammatory bowel disease (IBD) characterised by chronic immune-mediated inflammation. While serological biomarkers for IBD diagnosis and differentiation have been explored, autoantibody-based profiling remains underdeveloped. This study aimed to elucidate antibody signatures in manifested and pre-diagnostic UC patients compared to controls using a high-content protein microarray. Serum and plasma samples from manifested and pre-diagnostic UC cohorts were analysed using AIT’s 16k protein microarray, presenting 6369 human proteins. The pre-diagnostic cohort, consisting of 33 UC cases and 33 controls, included longitudinal samples collected before diagnosis, while the severe UC cohort, comprising 49 severe UC patients and 23 controls, included individuals undergoing treatment. Immunoglobulin G (IgG) autoantibody reactivity was assessed to identify differentially reactive antigens (DIRAGs) linked to UC onset, disease progression, and activity. In manifested UC, 691 DIRAGs showed higher reactivity in cases. In the pre-diagnostic cohort, 966 DIRAGs were identified, with 803 antigens exhibiting increased reactivity in cases. Longitudinal analysis revealed 1371 DIRAGs, with 1185 showing increased reactivity closer to diagnosis when comparing samples collected 4–11 months before UC diagnosis to earlier time points 9–24 months prior, highlighting potential early biomarkers. A significant overlap of 286 antigens, corresponding to 41 percent of identified DIRAGs, was observed between severe and pre-diagnostic UC datasets, with an odds ratio of 3.8 and a p-value below 2.2 × 10−16, confirming reliability and biological relevance. Additionally, 21 antigens correlated with simple clinical colitis activity index (SCCAI) scores. Reactome pathway analysis identified 49 pathways associated with DIRAGs in pre-diagnostic UC, distinct from 24 pathways in manifested UC, with an overlap of five key pathways related to protein folding, immune regulation, and viral infection, reflecting differences in disease onset and manifestation. Autoantibody profiling reveals early immune signatures in UC, offering novel biomarkers for preclinical diagnosis and disease monitoring. The overlap between pre-diagnostic and manifested UC antigenic profiles reinforces their biological relevance, linking them to molecular pathology. These findings highlight antibody profiling as an additional omics layer, paving the way for new diagnostic and therapeutic strategies in UC management.

Intestinal epithelial overexpression of the Th17 cell chemoattractant CCL20 is implicated in inflammatory bowel disease and influenced by NOD2 mutations in Crohn’s disease. Vitamin D metabolites have been shown to ameliorate inflammatory bowel disease. Considering NOD2 mutations in Crohn’s disease, we investigated whether Vitamin D deficiency (serum 25-hydroxyvitamin D concentration < 20 ng/mL) increases circulating CCL20 levels in inflammatory bowel disease patients and healthy controls and whether active 1,25-dihydroxyvitamin D (calcitriol) downregulates systemic and intestinal CCL20 expression. In a cross-sectional study, serum concentrations of CCL20, 25-hydroxyvitamin D, and calcitriol were measured in 170 NOD2 -genotyped Crohn’s disease patients, 80 ulcerative colitis patients, and 60 healthy controls. Additionally, the effect of calcitriol on experimentally induced CCL20 expression was examined using human intestinal epithelial HT-29 cells. Multivariable linear regression analyses revealed that both the diagnosis of inflammatory bowel disease and vitamin D deficiency were independently associated with elevated CCL20 levels. Compared to healthy controls, Crohn’s disease patients and ulcerative colitis patients exhibited significantly higher circulating CCL20 levels. Unlike in Crohn’s disease patients, vitamin D deficiency was associated with higher CCL20 levels in healthy controls and ulcerative colitis patients, whereas the calcitriol/25-hydroxyvitamin D activation ratios were negatively correlated with serum CCL20 levels in healthy controls and ulcerative colitis patients with sufficient serum 25-hydroxyvitamin D status. Furthermore, calcitriol markedly inhibited intestinal epithelial induction of CCL20. In Crohn’s disease patients, cholecalciferol supplementation was associated with lower serum CCL20 levels, which were unaffected by NOD2 mutations. These findings suggest that although vitamin D metabolites may downregulate CCL20 expression in healthy controls and ulcerative colitis patients, this regulatory effect appears to be impaired in Crohn’s disease patients.

We developed a two-tiered strategy aiming to identify gut bacteria functionally linked to the development of multiple sclerosis (MS). First, we compared gut microbial profiles in a cohort of 81 monozygotic twins discordant for MS. This approach allowed to minimize confounding effects by genetic and early environmental factors and identified over 50 differently abundant taxa with the majority of increased taxa within the Firmicutes. These included taxa previously described to be associated with MS (Anaerotruncus colihominis and Eisenbergiella tayi), along with newly identified taxa, such as Copromonas and Acutalibacter. Second, we interrogated the intestinal habitat and functional impact of individual taxa on the development of MS-like disease. In an exploratory approach, we enteroscopically sampled microbiota from different gut segments of selected twin pairs and compared their compositional profiles. To assess their functional potential, samples were orally transferred into germfree transgenic mice prone to develop spontaneous MS-like experimental autoimmune encephalomyelitis (EAE) upon bacterial colonization. We found that MS-derived ileal microbiota induced EAE at substantially higher rates than analogous material from healthy twin donors. Furthermore, female mice were more susceptible to disease development than males. The likely active organisms were identified as Eisenbergiella tayi and Lachnoclostridium, members of the Lachnospiraceae family. Our results identify potentially disease-facilitating bacteria sampled from the ileum of MS affected twins. The experimental strategy may pave the way to functionally understand the role of gut microbiota in initiation of MS.

Interleukin (IL)-23 and IL-17 are well-validated therapeutic targets in autoinflammatory diseases. Antibodies targeting IL-23 and IL-17 have shown clinical efficacy but are limited by high costs, safety risks, lack of sustained efficacy, and poor patient convenience as they require parenteral administration. Here, we present designed miniproteins inhibiting IL-23R and IL-17 with antibody-like, low picomolar affinities at a fraction of the molecular size. The minibinders potently block cell signaling in vitro and are extremely stable, enabling oral administration and low-cost manufacturing. The orally administered IL-23R minibinder shows efficacy better than a clinical anti-IL-23 antibody in mouse colitis and has a favorable pharmacokinetics (PK) and biodistribution profile in rats. This work demonstrates that orally administered de novo-designed minibinders can reach a therapeutic target past the gut epithelial barrier. With high potency, gut stability, and straightforward manufacturability, de novo-designed minibinders are a promising modality for oral biologics.

The development of animal models reflecting the pathologies of ulcerative colitis (UC) and Crohn's disease (CD) remains a major challenge. The NOD/SCID/IL2rγnull (NSG) mouse strain, which is immune-compromised, tolerates the engraftment of human peripheral blood mononuclear cells (PBMC) derived from patients with UC (NSG-UC) or CD (NSG-CD). This offers the opportunity to examine the impact of individual immunological background on the development of pathophysiological manifestations. When challenged with ethanol, NSG-UC mice exhibited a strong pro-inflammatory response, including the development of edemas, influx of human T cells, B cells and monocytes into the mucosa and submucosa, and elevated expression of the inflammatory markers CRP and CCL-7. Fibrotic alterations were characterized by an influx of fibroblasts and a thickening of the muscularis mucosae. In contrast, the development of pathological manifestations in NSG-CD mice developed without challenge and was signified by extensive collagen deposition between the muscularis propria and muscularis mucosae, as observed in the areas of strictures in CD patients. Vimentin-expressing fibroblasts supplanting colonic crypts and elevated expression of HGF and TGFß corroborated the remodeling phenotype. In summary, the NSG-UC and NSG-CD models partially reflect these human diseases and are powerful tools to examine the mechanism underlying the inflammatory processes in UC and CD.

INTRODUCTION: Iron deficiency and vitamin D deficiency are common comorbidities in inflammatory bowel disease (IBD). Accumulating evidence indicates that active 1,25-dihydroxyvitamin D (1,25(OH)D) may enhance iron absorption by suppressing hepcidin. We investigated the influence of vitamin D on iron metabolism in patients with IBD and on the expression of genes facilitating intestinal epithelial iron absorption. METHODS: Iron parameters and serum levels of 25-hydroxyvitamin D (25(OH)D), 1,25(OH)D, and hepcidin were measured in 104 adult patients with IBD (67 with Crohn's disease and 37 with ulcerative colitis). Genes involved in iron absorption were tested for induction by 1,25(OH)D in Caco-2 cells, which resemble the small intestinal epithelium. RESULTS: In multiple regression models controlling for age, sex, body mass index, smoking status, disease activity, and C-reactive protein levels, low 25(OH)D levels were associated with iron deficiency in patients with IBD (β [SE] = −0.064 [0.030], P = 0.029). Vitamin D sufficiency was associated with increased levels of ferritin (β [SE] = 0.25 [0.11], P = 0.024) and transferrin saturation (β [SE] = 8.41 [4.07], P = 0.044). Higher 1,25(OH)D:25(OH)D ratios were associated with lower hepcidin levels (β [SE] = −4.31 [1.67], P = 0.012). Especially in Crohn's disease, increased 1,25(OH)D correlated with higher transferrin saturation (β [SE] = 0.43 [0.18], P = 0.027). Furthermore, 1,25(OH)D strongly induced the expression of the ferroxidase ceruloplasmin in Caco-2 cells. DISCUSSION: Low vitamin D levels in IBD correlate with iron deficiency. Vitamin D may ameliorate iron deficiency, potentially by downregulating hepcidin and upregulating ceruloplasmin, enhancing intestinal iron absorption.

Purpose To evaluate the role of the nucleotide oligomerization domain 2 (NOD2) mutation status and other risk factors for the incidence of postoperative complications after ileocolic resection for Crohn's disease (CD). Methods Data of 138 patients consecutively undergoing ileocolic resection for CD at a tertiary academic referral center were retrospectively analyzed including single nucleotide polymorphism (SNP) data of the NOD2 gene. Uni- and multivariate regression analysis was performed to identify factors associated with increased risk of severe postoperative complications. Results From 114 patients (83%), the NOD2 mutation status was available. Of these, 60 (53%) had a NOD2 wildtype, whereas eleven (10%) were homozygous for the high risk p.Leu1007fsX1008 (rs2066847) variant. Major postoperative complications occurred in 28 patients (20%). Twenty-seven of these (96%) were intraabdominal septic complications such as anastomotic leakage or abscess. Male gender (P = 0.029; OR 3.052, the duration of CD (time [months] from initial diagnosis of CD to surgery; P = 0.001; OR 1.009), previous abdominal surgery for CD (P = 0.017; OR 3.49), and the presence of enteric fistulas (P = 0.023; OR 3.21) were identified as independent risk factors for major postoperative complications. Homozygosity for the NOD2 high-risk variant p.Leu1007fsX1008 did not show increased postoperative morbidity in the short and long-term outcome. Conclusions We could detect independent risk factors for major postoperative complications after ileocolic resection for Crohn's disease. However, patients with the high-risk variant p.Leu1007fsX1008 of the NOD2 gene did not show increased postoperative morbidity.

Background and Aims: The potassium channel Kv1.3 is a potentially attractive therapeutic target in T cell-mediated inflammatory diseases, as the activity of antigen-activated T cells is selectively impeded by Kv1.3 inhibition. In this study, we examined Kv1.3 as a potential therapeutic intervention point for ulcerative colitis [UC], and studied the efficacy of DES1, a small-molecule inhibitor of Kv1.3, in vitro and in vivo. Methods: Kv1.3 expression on T cells in peripheral blood mononuclear cells [PBMCs] isolated from donors with and without UC was examined by flow cytometry. In biopsies from UC patients, Kv1.3-expressing CD4+ T cells were detected by flow cytometry and immunohistochemistry. In vitro, we determined the ability of DES1 to inhibit anti-CD3-driven activation of T cells. In vivo, the efficacy of DES1 was determined in a humanised mouse model of UC and compared with infliximab and tofacitinib in head-to-head studies. Results: Kv1.3 expression was elevated in PBMCs from UC patients and correlated with the prevalence of TH1 and TH2 T cells. Kv1.3 expression was also detected on T cells from biopsies of UC patients. In vitro, DES1 suppressed anti-CD3-driven activation of T cells in a concentration-dependent manner. In vivo, DES1 significantly ameliorated inflammation in the UC model and most effectively so when PBMCs from donors with higher levels of activated T cells were selected for reconstitution. The efficacy of DES1 was comparable to that of either infliximab or tofacitinib. Conclusion: Inhibition of Kv1.3 [by DES1, for instance] appears to be a potential therapeutic intervention strategy for UC patients.

Abstract With glucose being the preferred source of energy in activated T cells, targeting glycolysis has become an attractive therapeutic intervention point for chronic inflammatory bowel diseases (IBD). The switch to glycolysis is mediated by phosphoinositide‐3‐kinases (PI3K) which relay signals from surface receptors to the AKT pathway. We first confirmed by analysis of the oxygen consumption rate (OCR) and extracellular acidification rate (ECAR) that metabolism is shifted towards glycolysis in IBD patients as compared to non‐IBD donors. In contrast to non‐IBD donors, OCR correlated with ECAR (IBD: cor = 0.79, p = 2E‐10; non‐IBD: cor = 0.37, p = n.s.), in IBD patients. Second, we tested the PI3K inhibitor copanlisib as a potential therapeutic. Ex vivo, copanlisib suppressed the ECAR significantly in T cells activated by anti‐CD3 antibodies and significantly decreased ECAR rates in the presence of copanlisib (anti‐CD3: 58.24 ± 29.06; copanlisib: 43.16 ± 20.23, p < .000. In addition, copanlisib impaired the activation of CD4+ CD25+ T cells (anti‐CD3: 42.15 ± 21.46; anti‐CD3 + copanlisib: 26.06 ± 21.82 p = .013) and the secretion of cytokines (IFNγ: anti‐CD3: 6332.0 ± 5707.61 pmol/ml; anti‐CD3 + copanlisib: 6332.0 ± 5707.61, p = .018). In vivo, copanlisib significantly improved the histological scores (ethanol: 8.5 ± 3.81; copanlisib: 4.57 ± 2.82, p = .006) in the NSG‐UC mouse model. Orthogonal partial least square analysis confirmed the efficacy of copanlisib. These data suggest that the PI3K pathway provides an attractive therapeutic intervention point in IBD for patients in relapse. Targeting metabolic pathways have the potential to develop phase dependent therapies.

AbstractIntroductionCrohn's disease (CD) is characterized by pronounced intestinal fibrosis and severe mucosal damage and conventional animal models are limited to reflect these pathological manifestations. The aim of this study was to examine whether the combination of patient immune‐profiling and preclinical studies in a mouse model based on NOD/scid IL‐2Rγnull (NSG) reconstituted with peripheral blood mononuclear cells (PBMC) from CD patients has the capacity to harmonize ex vivo human and in vivo animal studies.MethodsImmunological profiles of CD (n = 24) and ulcerative colitis (UC) patients (n = 47) were established by flow cytometry of subgroups of immune cells and subjected to hierarchical cluster and estimation graphics analyses. Pathological phenotypes of NSG mice, which were reconstituted with PBMC from CD, UC, and non‐IBD donors (NSG‐CD, NSG‐UC, and NSG‐non‐IBD) were compared. Readouts were the clinical, colon, and histological scores; subtypes of immune cells from spleen and colon; and levels of inflammatory markers, such as c‐reactive protein (CRP), monocyte chemotactic protein (MCP)‐3, transforming growth factor‐beta (TGFß), and hepatocyte growth factor (HGF). Fibrocytes were identified by immunohistochemistry in colonic sections.ResultsCD patients were significantly clustered in a group characterized by increased levels of TH1, TH2 cells, and decreased levels of CD14+ CD163+ monocytes (p = .003). In contrast to NSG‐UC mice, NSG‐CD mice exhibited an immune‐remodeling phenotype characterized by enhanced collagen deposition, elevated levels of CD14+ CD163+ monocytes, HGF, and TGFß. This phenotype was further corroborated by the presence of human fibrocytes as components of fibrotic areas.ConclusionThe NSG‐CD model partially reflects the human disease and allows for studying the development of fibrosis.

This study's aim was to demonstrate that the combination of patient immune profiling and testing in a humanized mouse model of ulcerative colitis (UC) might lead to patient stratification for treatment with oxelumab. First, immunological profiles of UC patients and non-UC donors were analyzed for CD4+ T cells expressing OX40 (CD134; also known as TNFRSF4) and CD14+ monocytes expressing OX40L (CD252; also known as TNFSF4) by flow cytometric analysis. A significant difference was observed between the groups for CD14+ OX40L+ (UC: n=11, 85.44±21.17, mean±s.d.; non-UC: n=5, 30.7±34.92; P=0.02), whereas no significant difference was detected for CD4+ OX40+. CD14+ OX40L+ monocytes were correlated significantly with T helper 1 and 2 cells. Second, NOD/Scid IL2Rγ null mice were reconstituted with peripheral blood mononuclear cells from UC donors exhibiting elevated levels of OX40L, and the efficacy of oxelumab was compared with that of adalimumab. The clinical, colon and histological scores and the serum concentrations of IL-6, IL-1β and glutamic acid were assessed. Treatment with oxelumab or adalimumab resulted in significantly reduced clinical, colon and histological scores, reduced serum concentrations of IL-6 and reduced frequencies of splenic human effector memory T cells and switched B cells. Comparison of the efficacy of adalimumab and oxelumab by orthogonal partial least squares discrimination analysis revealed that oxelumab was slightly superior to adalimumab; however, elevated serum concentrations of glutamic acid suggested ongoing inflammation. These results suggest that oxelumab addresses the pro-inflammatory arm of inflammation while promoting the remodeling arm and that patients exhibiting elevated levels of OX40L might benefit from treatment with oxelumab.

Abstract Background The Holy Grail in chronic inflammatory diseases is the identification of biological markers which might explain the heterogeneity of disease manifestations and predict responses to treatment. The aim of this study was to identify immunological subgroups of patients with UC and to test responsiveness to adalimumab in these subgroups in the mouse model of ulcerative colitis (UC), which is based on NOD/scid IL-2Rγ null (NSG) mice reconstituted with peripheral blood mononuclear cells (PBMCs; NSG-UC). Methods The immunological profiles of 40 UC patients and 16 non-UC donors were determined by flow cytometric analysis of PBMCs in a snapshot and longitudinal study and analysed by principal component (PCA), orthogonal partial least square discrimination (oPLS-DA)- and hierarchical clustering analysis. NSG mice were reconstituted five times at consecutive time points with PBMCs from a single donor and were analysed for frequencies of human leukocytes, histological phenotype and levels of calprotectin (CRP) and transforming growth factor (TGF)-β. The response to adalimumab was tested in the NSG-UC model reconstituted with PBMC from patients clustering in group I (n = 2) or II (n = 2). Readout were the clinical, colon and histological scores, serum levels of glutamic and aspartic acid and interleukin (IL)-6 and IL-1β. The response was analysed by PCA. Results Hierarchical clustering identified two major subgroups in UC patients. Group I was characterised by TH17 and M1 monocytes, group II by TH2/TH1 and switched B cells. O-PLS-DA revealed significant discrimination between the two groups. Patients analysed in longitudinal studies switched from one group to the other. Thus, these subgroups reflected the dynamics of inflammation in patients. Mice reconstituted five times at consecutive time points with PBMC from one donor achieved an immunological phenotype reflecting the one of the Patient at that time point. Like the patient, mice switched from a pro-inflammatory phenotype (group II) to an M1 monocyte driven inflammation (group I). In mice, group II was characterised by a severe influx of inflammatory cells and oedema whereas group I was signified by extensive fibrosis. This observation was corroborated by colonic CRP and TGFß levels. CRP levels were significantly higher in group II, whereas TGFβ levels were increased in group I. PCA analysis revealed that mice reconstituted with PBMC from group II responded better to treatment with adalimumab than mice from group I. Conclusion The combination of profiling and testing of therapeutics in the NSG-UC model may ultimately lead to individualised and phase-dependent therapies.

Abstract Background Recently, we have developed a mouse model that relies on NOD-scid IL-2Rγnull (NSG) mice reconstituted with peripheral blood mononuclear cells (PBMC) derived from patients with ulcerative colitis (UC, NSG-UC). In this model, symptoms of UC are induced by rectal challenge with ethanol. The objective of the study was to adapt this model to Crohn’s disease and to compare the phenotypes of the NSG-UC and NSG-CD mouse models. Methods NSG mice were reconstituted with PBMC from UC (n = 4) or CD (n = 3) patients. Mice were separated into two groups: unchallenged control and ethanol challenged mice. Readout were clinical-, colon and histological scores, analysis of frequencies of subgroups of human T cells, monocytes and B cells isolated from spleen and colon by flow cytometry, and the expression levels of the inflammatory markers TGFß, CRP, MCP-3, and IL-6 in the colon or serum by Luminex analysis. Results The pathological phenotype was markedly different in NSG-UC mice as compared with NSG-CD mice. Firstly, histological analysis revealed that NSG-UC mice exhibited more of a pro-inflammatory phenotype as indicated by a severe influx of inflammatory cells, oedema, crypt loss, crypt abscesses and epithelial hyperplasia. In contrast, NSG-CD mice displayed crypt loss and goblet cell atrophy and pronounced fibrosis indicating ongoing wound healing processes. These observations were corroborated by frequencies of splenic and colonic leucocytes. Antigen experienced CD4+ T (CD45RO+) cells and switched B cells (CD19+ CD27+ IgD-) were significantly increased in NSG-UC mice, whereas significantly higher levels of experienced CD8+ T cells and M1 (CD64+), M2 (CD163+) CD14+ monocytes and unswitched B cells (CD19+ CD27+ IgD+) indicated a monocyte driven inflammation in NSG-CD mice. This observation was also reflected in the colon of mice. Inflammation in UC was characterised by increased frequencies of neutrophils, activated CD4+ T cells (CD69+) and increased levels of CRP and MCP-3, whereas NSG-CD mice were signified by increased frequencies of M2 and M1 monocytes and of TGFß levels. In contrast to NSG-CD mice, NSG-UC mice also displayed higher serum levels of IL-6. Secondly, the impact of ethanol was more pronounced in the NSG-UC mice. In NSG-CD mice, the challenge did not evoke significant differences as compared with unchallenged control mice. Conclusion The comparison of pathological phenotypes of the NSG-UC and NSG-CD mouse models revealed differences, some of which reflect the respective human disease. The NSG-UC and NSG-CD mouse models may constitute powerful tools to get a better understanding of the different inflammatory processes in UC and CD.

To date, no comprehensive analysis of autoantibodies in sera of patients with ulcerative colitis has been conducted. To analyze the spectrum of autoantibodies and to elucidate their role serum-IgG from UC patients (n = 49) and non-UC donors (n = 23) were screened by using a human protein microarray. Screening yielded a remarkable number of 697 differentially-reactive at the nominal 0·01 significance level (FDR<0·1) of the univariate test between the UC and the non-UC group. CD99 emerged as a biomarker to discriminate between both groups (p = 1e-04, AUC = 0·8). In addition, cytokines, chemokines and growth factors were analyzed by Olink's Proseek® Multiplex Inflammation-I 96×96 immuno-qPCR assay and 31 genes were significant at the nominal 0.05 level of the univariate test to discriminate between UC and non-UC donors. MCP-3, HGF and CXCL-9 were identified as the most significant markers to discriminate between UC patients with clinically active and inactive disease. Levels of CXCL10 (cor = 0.3; p = 0.02), CCL25 (cor = 0.25; p = 0.04) and CCL28 (cor = 0.3; p = 0.02) correlated positively with levels of anti CD99. To assess whether autoantibodies are detectable prior to diagnosis with UC, sera from nine donors at two different time points (T-early, median 21 months and T-late, median 6 months) were analyzed. 1201 features were identified with higher reactivity in samples at time points closer to clinical UC presentation. In vitro, additional challenge of peripheral mononuclear cells with CD99 did not activate CD4+ T cells but induced the secretion of IL-10 (-CD99: 20.21±20.25; +CD99: 130.20±89.55; mean ±sd; p = 0.015). To examine the effect of CD99 in vivo, inflammation and autoantibody levels were examined in NOD/ScidIL2Rγnull mice reconstituted with PBMC from UC donors (NSG-UC). Additional challenge with CD99 aggravated disease symptoms and pathological phenotype as indicated by the elevated clinical score (-CD99: 1·85 ± 1·94; +CD99: 4·25 ± 1·48) and histological score (-CD99: 2·16 ± 0·83; +CD99: 3·15 ± 1·16, p = 0·01). Furthermore, levels of anti-CD99 antibodies increased (Control: 398 ± 323; mean MFI ± sd; Ethanol + PBS: 358 ±316; Ethanol + CD99: 1363 ± 1336; Control versus Ethanol + CD99: p = 0.03). In a highly inflammatory environment, frequencies of pro-inflammatory M1 monocytes (CD14+ CD64+: unchallenged 8.09±4.72; challenged 14.2±8.62; p = 0.07; CD14+ CD1a+: unchallenged 16.29 ±6.97; challenged 43.81±14.4, p = 0.0003) increased and levels of autoantibodies in serum decreased in the NSG-UC mouse model. These results suggest that autoantibodies are potent biomarkers to discriminate between UC and non-UC and indicate risk to develop UC. In an inflammatory environment, auto-antibodies may promote the pathological phenotype by activating M1 monocytes in the NSG-UC animal model and also in patients with UC.

Background NOD2variants are the strongest genetic predictors for susceptibility to Crohn's disease (CD). However, the clinical value ofNOD2on an individual patient level remains controversial. We aimed to define the predictive power of the majorNOD2mutations regarding complicated CD in a large single center cohort. Methods 1076 CD patients were prospectively genotyped for the three common CD-associatedNOD2mutations rs2066844, rs2066845, and rs2066847, followed by detailed genotype-phenotype analyses. Results Overall, 434 CD patients (40.3%) carried at least one of the three mainNOD2mutations. A significantly higher minor allele frequency (15.6%) of theNOD2frameshift mutation p.Leu1007fsX1008 (rs2066847) was seen in patients with aggressive disease compared to 8.2% in patients with mild disease (p = 2.6 x 10(-5)). Moreover, a total of 54 CD patients (5.0%) were homozygous for thisNOD2frameshift mutation. 100% of these patients had ileal disease compared to 82% ofNOD2wild-type carriers (p<0.0001). In homozygous carriers of theNOD2frameshift mutation, 87% presented with ileal stenosis, 68.5% had fistulas, and 72.2% required CD-related surgery despite immunosuppressive therapy in 87% of these patients. All homozygous carriers of the 1007fs mutation who were active smokers had ileal stenosis and required CD-related surgery. Conclusion Homozygosity for Leu1007fsX1008 is an excellent biomarker for predicting complicated CD on an individual patient level. Active smoking and homozygosity for this mutation is associated with a 100% risk for developing ileal stenosis requiring CD-related surgery. In these patients, smoking cessation and early initiation of immunosuppressive strategies may be beneficial.

The energy supply of inflammatory cells relies on three sources: Glycolysis, oxidation of lipids, and amino acid (AS) metabolism. In homeostasis, when the major task of inflammatory cells is the maintenance of tolerance, lipids are the preferred source as lipid oxidation is the most efficient albeit slowest pathway to generate ATP: The response to an assault, however, requires the immediate activation, proliferation, differentiation of inflammatory cells, their migration to sites of inflammation and expression of cytokines, growth factors and chemokines. These processes demand prompt energy supply which is met by a metabolic switch from lipid oxidation to glycolysis to ensure swift ATP generation and the synthesis of biosynthetic intermediates albeit at the expense of efficiency. Therefore, the dependence on glycolysis might offer an Achilles’ heel of inflammatory cells. Glucose uptake into the cell is regulated by the PI3K/AKT/mTOR pathway and glucose uptake transporters (GLUT). Therefore, we tested the PI3K inhibitor copanlisib and the glucose uptake inhibitor ritonavir in vitro and in vivo. Peripheral blood mononuclear cells (PBMC) were activated with anti CD3/CD28 in the presence of ritonavir. Cells were analysed by flow cytometric analysis. A seahorse analysis was performed. To examine the effect of ritonavir in vivo, the NSG-UC mouse model was used which is based on immunocompromised NOD-scid IL-2R null mice reconstituted with (PBMC) from patients with ulcerative colitis (UC). Dependent variables were clinical and histological score, frequencies of human leucocytes isolated from spleen and colon and levels of amino acids (AS) in sera of mice. Frequencies of activated CD4+ cells (CD4+ CD69+, CD4+ CD134+) were significantly affected by ritonavir and copanlisib. Ritonavir affects frequencies of CD4+ T-cell subtypes. Copanlisib predominantly inhibited glycolysis induced by activation of CD4+ cells with anti CD3+ / CD28 antibodies and activation of monocytes induced by LPS. Mice benefited from treatment with ritonavir as indicated by decreased clinical (p = 0.05) and histological (p = 7e−0.5) scores and Glu levels (p = 0.02). PCA analysis revealed a clustering of ritonavir treated mice with control mice. Principal component analysis discriminates between the control group, ethanol-challenged group and ritonavir-treated group. Targeting metabolic pathways might open up new avenues for therapeutic interventions. Patients might benefit from FDA-approved drugs as copanlisib or ritonavir.