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 αβ+ 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.

The gut microbiota-induced kynurenic acid recruits GPR35-positive macrophages to promote experimental encephalitis

The intricate interplay between gut microbes and the onset of experimental autoimmune encephalomyelitis (EAE) remains poorly understood. Here, we uncover remarkable similarities between CD4+ T cells in the spinal cord and their counterparts in the small intestine. Furthermore, we unveil a synergistic relationship between the microbiota, particularly enriched with the tryptophan metabolism gene EC:1.13.11.11, and intestinal cells. This symbiotic collaboration results in the biosynthesis of kynurenic acid (KYNA), which modulates the recruitment and aggregation of GPR35-positive macrophages. Subsequently, a robust T helper 17 (Th17) immune response is activated, ultimately triggering the onset of EAE. Conversely, modulating the KYNA-mediated GPR35 signaling in Cx3cr1+ macrophages leads to a remarkable amelioration of EAE. These findings shed light on the crucial role of microbial-derived tryptophan metabolites in regulating immune responses within extraintestinal tissues.

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 TNF-α/IL-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. 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 characterised 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 analysed 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%; B 64.5%; C 18.7%, all p<0.05) and negatively correlated with MELD and CRP (all p<0.05). AXL-expressing hepatic macrophages were CD68^highHLA-DR^highCD16^highCD206^high. 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 HSCs-secreted GAS6, suggests a role for AXL in the regulation of hepatic immune homeostasis.

Stimulatory MAIT cell antigens reach the circulation and are efficiently metabolised and presented by human liver cells

OBJECTIVE

Mucosal-associated invariant T (MAIT) cells are the most abundant T cells in human liver. They respond to bacterial metabolites presented by major histocompatibility complex-like molecule MR1. MAIT cells exert regulatory and antimicrobial functions and are implicated in liver fibrogenesis. It is not well understood which liver cells function as antigen (Ag)-presenting cells for MAIT cells, and under which conditions stimulatory Ags reach the circulation.

DESIGN

We used different types of primary human liver cells in Ag-presentation assays to blood-derived and liver-derived MAIT cells. We assessed MAIT cell stimulatory potential of serum from healthy subjects and patients with portal hypertension undergoing transjugular intrahepatic portosystemic shunt stent, and patients with inflammatory bowel disease (IBD).

RESULTS

MAIT cells were dispersed throughout healthy human liver and all tested liver cell types stimulated MAIT cells, hepatocytes being most efficient. MAIT cell activation by liver cells occurred in response to bacterial lysate and pure Ag, and was prevented by non-activating MR1 ligands. Serum derived from peripheral and portal blood, and from patients with IBD stimulated MAIT cells in MR1-dependent manner.

CONCLUSION

Our findings reveal previously unrecognised roles of liver cells in Ag metabolism and activation of MAIT cells, repression of which creates an opportunity to design antifibrotic therapies. The presence of MAIT cell stimulatory Ags in serum rationalises the observed activated MAIT cell phenotype in liver. Increased serum levels of gut-derived MAIT cell stimulatory ligands in patients with impaired intestinal barrier function indicate that intrahepatic Ag-presentation may represent an important step in the development of liver disease.

Experimental and genetic evidence for the impact of CD5 and CD6 expression and variation in inflammatory bowel disease

Crohn’s disease (CD) and ulcerative colitis (UC) are inflammatory bowel diseases (IBD) resulting from the interaction of multiple environmental, genetic and immunological factors. CD5 and CD6 are paralogs encoding lymphocyte co-receptors involved in fine-tuning intracellular signals delivered upon antigen-specific recognition, microbial pattern recognition and cell adhesion. While CD5 and CD6 expression and variation is known to influence some immune-mediated inflammatory disorders, their role in IBD remains unclear. To this end, Cd5- and Cd6-deficient mice were subjected to dextran sulfate sodium (DSS)-induced colitis, the most widely used experimental animal model of IBD. The two mouse lines showed opposite results regarding body weight loss and disease activity index (DAI) changes following DSS-induced colitis, thus supporting Cd5 and Cd6 expression involvement in the pathophysiology of this experimental IBD model. Furthermore, DNA samples from IBD patients of the ENEIDA registry were used to test association of CD5 (rs2241002 and rs2229177) and CD6 (rs17824933, rs11230563, and rs12360861) single nucleotide polymorphisms with susceptibility and clinical parameters of CD (n=1352) and UC (n=1013). Generalized linear regression analyses showed association of CD5 variation with CD ileal location (rs2241002^CC) and requirement of biological therapies (rs2241002^C-rs2229177^T haplotype), and with poor UC prognosis (rs2241002^T-rs2229177^T haplotype). Regarding CD6, association was observed with CD ileal location (rs17824933^G) and poor prognosis (rs12360861^G), and with left-sided or extensive UC, and absence of ankylosing spondylitis in IBD (rs17824933^G). The present experimental and genetic evidence support a role for CD5 and CD6 expression and variation in IBD’s clinical manifestations and therapeutic requirements, providing insight into its pathophysiology and broadening the relevance of both immunomodulatory receptors in immune-mediated disorders.

IL-20 subfamily cytokines impair the oesophageal epithelial barrier by diminishing filaggrin in eosinophilic oesophagitis

OBJECTIVE

Disruption of the epithelial barrier plays an essential role in developing eosinophilic oesophagitis (EoE), a disease defined by type 2 helper T cell (Th2)-mediated food-associated and aeroallergen-associated chronic inflammation. Although an increased expression of interleukin (IL)-20 subfamily members, IL-19, IL-20 and IL-24, in Th2-mediated diseases has been reported, their function in EoE remains unknown.

DESIGN

Combining transcriptomic, proteomic and functional analyses, we studied the importance of the IL-20 subfamily for EoE using patient-derived oesophageal three-dimensional models and an EoE mouse model.

RESULTS

Patients with active EoE have increased expression of IL-20 subfamily cytokines in the oesophagus and serum. In patient-derived oesophageal organoids stimulated with IL-20 cytokines, RNA sequencing and mass spectrometry revealed a downregulation of genes and proteins forming the cornified envelope, including filaggrins. On the contrary, abrogation of IL-20 subfamily signalling in Il20R2 ^-/- animals resulted in attenuated experimental EoE reflected by reduced eosinophil infiltration, lower Th2 cytokine expression and preserved expression of filaggrins in the oesophagus. Mechanistically, these observations were mediated by the mitogen-activated protein kinase (MAPK); extracellular-signal regulated kinases (ERK)1/2) pathway. Its blockade prevented epithelial barrier impairment in patient-derived air-liquid interface cultures stimulated with IL-20 cytokines and attenuated experimental EoE in mice.

CONCLUSION

Our findings reveal a previously unknown regulatory role of the IL-20 subfamily for oesophageal barrier function in the context of EoE. We propose that aberrant IL-20 subfamily signalling disturbs the oesophageal epithelial barrier integrity and promotes EoE development. Our study suggests that specific targeting of the IL-20 subfamily signalling pathway may present a novel strategy for the treatment of EoE.

The Selective 5-HT1A Agonist SR57746A Protects Intestinal Epithelial Cells and Enteric Glia Cells and Promotes Mucosal Recovery in Experimental Colitis

BACKGROUND

Neurotrophic growth factors can stabilize the intestinal barrier by preventing the apoptosis of enteric glial cells (EGCs) and enterocytes. We reasoned that a selective 5-HT1A receptor agonist may have neuroprotective properties in the gut and that topical application of SR57746A might be an effective treatment strategy in inflammatory bowel disease (IBD).

METHODS

The therapeutic potential of 5-HT1A receptor agonist SR57746A in IBD was evaluated in vitro (nontransformed NCM460 colonic epithelial cells, SW480 colorectal carcinoma cells) and in vivo (murine dextran sulfate sodium [DSS] colitis and CD4-T-cell transfer colitis). In vitro, we analyzed the effect of SR57746A on apoptosis in intestinal epithelial cells (IECs) and EGCs, and upon proliferation, migration, and intracellular signaling in IECs. In vivo, the effect of topical application of SR57746 on disease activity and on histological and endoscopic findings was compared with intraperitoneal infliximab and placebo, respectively.

RESULTS

The SR57746A activates PI3-K/AKT- and ERK-signaling in IECs. Depending on ERK- and AKT activation, SR57746A potently prevents apoptosis of IECs without inducing proliferation or migration in these cells. Moreover, SR57746A prevented apoptosis in EGCs in vitro. Topical SR57746A treatment significantly reduced mucosal injury in 2 experimental murine colitis models and was as effective as intraperitoneal infliximab treatment.

CONCLUSIONS

Treatment with SR57746A prevents inflammatory cell damage and apoptosis in IECs and EGCs, similar to the neurotrophic effects of EGCs on IECs. Topical treatment with SR57746A could be a candidate for clinical evaluation in the treatment of IBD.

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.

GPR35 in Intestinal Diseases: From Risk Gene to Function

Diet and gut microbial metabolites mediate host immune responses and are central to the maintenance of intestinal health. The metabolite-sensing G-protein coupled receptors (GPCRs) bind metabolites and trigger signals that are important for the host cell function, survival, proliferation and expansion. On the contrary, inadequate signaling of these metabolite-sensing GPCRs most likely participate to the development of diseases including inflammatory bowel diseases (IBD). In the intestine, metabolite-sensing GPCRs are highly expressed by epithelial cells and by specific subsets of immune cells. Such receptors provide an important link between immune system, gut microbiota and metabolic system. Member of these receptors, GPR35, a class A rhodopsin-like GPCR, has been shown to be activated by the metabolites tryptophan-derived kynurenic acid (KYNA), the chemokine CXCL17 and phospholipid derivate lysophosphatidic acid (LPA) species. There have been studies on GPR35 in the context of intestinal diseases since its identification as a risk gene for IBD. In this review, we discuss the pharmacology of GPR35 including its proposed endogenous and synthetic ligands as well as its antagonists. We elaborate on the risk variants of GPR35 implicated in gut-related diseases and the mechanisms by which GPR35 contribute to intestinal homeostasis.

Immune system and microbiome in the esophagus: implications for understanding inflammatory diseases

The gastrointestinal tract is the largest compartment of the body's immune system exposed to microorganisms, structural components and metabolites, antigens derived from the diet, and pathogens. Most studies have focused on immune responses in the stomach, the small intestine, and the colon, but the esophagus has remained an understudied anatomic immune segment. Here, we discuss the esophagus' anatomical and physiological distinctions that may account for inflammatory esophageal diseases.

[The IBD-Control questionnaire: German translation and validation of the standardized questionnaire for Patient Reported Outcome Measurement in inflammatory bowel disease]

BACKGROUND

Subjectively perceived results of treatment will be in the center of defining treatment success on the way to value-based and patient-centered health care. Patient-reported outcome measures (PROMs) serve as an instrument to measure treatment success. In inflammatory bowel disease (IBD), measuring treatment success from a patient's point of view is performed with the validated IBD-Control questionnaire. Because the IBD-Control questionnaire has not been published in German yet, the translation and validation of the IBD-Control in the German-speaking part of Switzerland was necessary before use.

METHODS

We have translated the English original version of the IBD-Control questionnaire into German in a state-of-the-art procedure of "forward-backward translation" and validated the translated IBD-Control questionnaire with 154 patients with Crohn's disease or with ulcerative colitis.

RESULTS

Professional health care and translation experts have contributed to the translation of the IBD-Control into German. The IBD-Control-D is an accepted questionnaire. Spearmans Rho showed high consistency between the IBD-Control-8-Subscore and the IBD-Control-VAS-Score (r=0.632). The disease activity in the past 6 months highly correlated with the IBD-8 subscore (r=0.640) as well as with the IBD-Control-VAS-Score (r=0.622). The IBD-Control-8-Subscore highly correlated with the Harvey Bradshaw Index (r=-0.620) and the partial Mayo Score (r=-0.679), as well as the IBD-Control-VAS-Score with the Harvey Bradshaw Index (r=-0.484) and the Mayo Score (r=-0.435), showing sufficient construct validity. The result is the German version of the IBD-Control, the IBD-Control-D, published here.

CONCLUSION

The original English version is a valid instrument, and its use has proven to be a suitable instrument in German-speaking areas to make the subjective feeling of illness and treatment outcome measurable.

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.

Intestinal microbial metabolites in human metabolism and type 2 diabetes

Humans with the metabolic syndrome and type 2 diabetes have an altered gut microbiome. Emerging evidence indicates that it is not only the microorganisms and their structural components, but also their metabolites that influences the host and contributes to the development of the metabolic syndrome and type 2 diabetes. Here, we discuss some of the mechanisms underlying how microbial metabolites are recognised by the host or are further processed endogenously in the context of type 2 diabetes. We discuss the possibility that gut-derived microbial metabolites fuel the development of the metabolic syndrome and type 2 diabetes. Graphical abstract.

The Copper/Zinc Ratio Correlates With Markers of Disease Activity in Patients With Inflammatory Bowel Disease

BACKGROUND

Zinc (Zn) and copper (Cu) are trace elements that serve as cofactors in catalytic processes with impact on immune responses. In patients with inflammatory bowel disease (IBD), decreased levels of serum Zn and Cu have been observed. Here, we investigated the effect of inflammation on serum concentrations of these trace elements in patients with IBD.

METHODS

In this cross-sectional study, 98 patients with Crohn disease (CD) and 56 with ulcerative colitis (UC) were prospectively enrolled. Disease activity parameters, such as C-reactive protein (CRP) and fecal calprotectin (FC) were compared to serum Zn, Cu, and Cu/Zn ratio.

RESULTS

Zinc insufficiency was observed in 11.2% of patients with CD and 14.3% with UC, Cu insufficiency in 20.4% with CD and 7.1% with UC. Anemia, hypoalbuminemia, increased FC, and elevated CRP were more frequently present in Zn-insufficient patients with IBD. In contrast, lower serum CRP values and a trend to lower FC were observed in Cu-insufficient patients. In multiple linear regression models adjusted for age, gender, and serum albumin, CRP positively correlated with serum Cu (P < 0.001) and the Cu/Zn ratio in both CD and UC (P < 0.001) but not with serum Zn concentrations. FC levels correlated only with the Cu/Zn ratio in patients with UC (P < 0.038).

CONCLUSION

Systemic inflammation inversely affected the serum Zn and Cu concentrations and, consequently, resulted in an increased Cu/Zn ratio.

[The Role of the Exposome in the Emergence of Chronic Inflammatory Bowel Diseases]

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.

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.

High Prevalence of Vitamin D Deficiency among Patients with Inflammatory Bowel Disease

Background

Vitamin D is a hormone with immunomodulatory properties. Vitamin D deficiency has been reported for patients with inflammatory bowel disease (IBD). In this cross-sectional study, 25-hydroxyvitamin D3 (25-OH-D3) levels in patients with IBD were compared to those in patients with irritable bowel syndrome (IBS).

Methods

A total of 181 patients, 156 with IBD and 25 with IBS, were included. The influence of disease activity, inflammatory markers, physical activity, and season were assessed.

Results

A total of 58.6$ (n = 58) of the patients with Crohn's disease (CD) and 44.6$ (n = 25) of the patients with ulcerative colitis (UC) had a 25-OH-D3 level < 50 nmol/L. CD patients showed significantly decreased 25-OH-D3 levels compared to the IBS patients (p = 0.018), but no significant difference was found for UC patients. In a linear regression model adjusted for age, gender, and BMI, a significant inverse association of C-reactive protein (CRP) (p = 0.031) and faecal calprotectin (FC) (p = 0.025) with 25-OH-D3 levels was observed for CD patients. Seasonal variation in 25-OH-D3 levels was found in CD patients, with significantly lower values in spring than in summer (p = 0.04).

Conclusion

Vitamin D deficiency was common in all IBD patients, but more pronounced in CD patients, in whom it also showed a significant inverse association with inflammatory markers such as CRP and FC.

The Interleukin-20 Cytokines in Intestinal Diseases

Autoimmune/inflammatory intestinal diseases, such as Crohn’s disease and ulcerative colitis, infectious gastrointestinal diseases, and gastrointestinal cancers, such as colorectal cancer, are worldwide a significant health problem. Intercellular communication and direct contact with the environment as the microbiota colonizes the gastrointestinal surface facilitates these diseases. Cytokines mediate the intercellular communication to maintain the equilibrium between host and environment and to regulate immune responses. One cytokine family that exchange information between immune cells and epithelial cells is the IL-20 cytokine family which includes the cytokines IL-19, IL-20, IL-22, IL-24, and IL-26. These cytokines share common receptor subunits and signaling pathways. IL-22 is the most intensively studied cytokine within this family in contexts of gastrointestinal disease, but the importance of other family members is more and more appreciated. In this review, the potential function of IL-20 cytokines concerning gastrointestinal conditions is discussed.

Injections of Lipopolysaccharide into Mice to Mimic Entrance of Microbial-derived Products After Intestinal Barrier Breach

The intestinal epithelial barrier separates the host from the microbiota that is normally tolerated or ignored. The breach of this barrier results in the entrance of bacteria or bacteria-derived products into the host, accessing the host circulation and inner organs leading to the uncontrolled inflammation as observed in patients with inflammatory bowel disease (IBD), that are characterized by an increased intestinal epithelial permeability. To mimic the entrance of bacterial-derived compounds into the host, an endotoxemia model has been adopted in which lipopolysaccharide (LPS), a component of the outer cell wall of Gram-negative bacteria, were injected into mice. In this study, a sublethal dose of LPS was intraperitoneally injected and the mice were subsequently monitored for 8 h using a disease score. Furthermore, the expression levels of the inflammatory cytokines Il6, Il1b, and Tnfa were analyzed in the spleen, liver and colon by qPCR at different time points post LPS injection. This model could be useful for the studies involving investigation of immune responses after the invasion of microorganisms or bacterial-derived products caused by a barrier breach of body surfaces.

The Stimulation of Macrophages with TLR Ligands Supports Increased IL-19 Expression in Inflammatory Bowel Disease Patients and in Colitis Models

IL-19, a member of the IL-10 cytokine family that signals through the IL-20 receptor type I (IL-20Rα:IL-20Rβ), is a cytokine whose function is not completely known. In this article, we show that the expression of IL19 in biopsies of patients with active ulcerative colitis was increased compared with patients with quiescent ulcerative colitis and that colitis was attenuated in IL-19-deficient mice. The disruption of the epithelial barrier with dextran sodium sulfate leads to increased IL-19 expression. Attenuated colitis in IL-19-deficient animals was associated with reduced numbers of IL-6-producing macrophages in the inflamed colonic lamina propria. Microbial-driven expression of IL-19 by intestinal macrophages may contribute to the pathogenesis of inflammatory bowel disease.

Successful Treatment of Small Intestinal Bleeding in a Crohn's Patient with Noncirrhotic Portal Hypertension by Transjugular Portosystemic Shunt Placement and Infliximab Treatment

Small intestinal bleeding in Crohn's disease patients with noncirrhotic portal hypertension and partial portal and superior mesenteric vein thrombosis is a life-threatening event. Here, a case is reported in which treatment with azathioprine may have resulted in nodular regenerative hyperplasia, portal hypertension and portal vein thrombosis. The 56-year-old patient with Crohn's disease developed nodular regenerative hyperplasia under treatment with azathioprine. He was admitted with severe bleeding. Gastroscopy showed small esophageal varices without bleeding stigmata. Blood was detected in the terminal ileum. CT scan revealed a partial portal vein thrombosis with extension to the superior mesenteric vein, thickening of the jejunal wall and splenomegaly. Because intestinal bleeding could not be controlled by conservative treatment, the thrombus was aspirated and a transjugular intrahepatic portosystemic shunt (TIPS) was placed. Switching the immunosuppressive medication to infliximab controlled Crohn's disease activity. Bleeding was stopped, hemoglobin normalized, and thrombocytopenia and bowel movements improved. In summary, small intestinal bleeding in a Crohn's patient with nodular regenerative hyperplasia, portal hypertension and portal vein thrombosis can be efficiently treated by TIPS. TIPS placement together with infliximab treatment led to the improvement of the blood panel and remission in this patient.

Development of an Antigen-driven Colitis Model to Study Presentation of Antigens by Antigen Presenting Cells to T Cells

Inflammatory bowel disease (IBD) is a chronic inflammation which affects the gastrointestinal tract (GIT). One of the best ways to study the immunological mechanisms involved during the disease is the T cell transfer model of colitis. In this model, immunodeficient mice (RAG(-/-) recipients) are reconstituted with naive CD4(+) T cells from healthy wild type hosts. This model allows examination of the earliest immunological events leading to disease and chronic inflammation, when the gut inflammation perpetuates but does not depend on a defined antigen. To study the potential role of antigen presenting cells (APCs) in the disease process, it is helpful to have an antigen-driven disease model, in which a defined commensal-derived antigen leads to colitis. An antigen driven-colitis model has hence been developed. In this model OT-II CD4(+) T cells, that can recognize only specific epitopes in the OVA protein, are transferred into RAG(-/-) hosts challenged with CFP-OVA-expressing E. coli. This model allows the examination of interactions between APCs and T cells in the lamina propria.

The early activation marker CD69 regulates the expression of chemokines and CD4 T cell accumulation in intestine

Migration of naïve and activated lymphocytes is regulated by the expression of various molecules such as chemokine receptors and ligands. CD69, the early activation marker of C-type lectin domain family, is also shown to regulate the lymphocyte migration by affecting their egress from the thymus and secondary lymphoid organs. Here, we aimed to investigate the role of CD69 in accumulation of CD4 T cells in intestine using murine models of inflammatory bowel disease. We found that genetic deletion of CD69 in mice increases the expression of the chemokines CCL-1, CXCL-10 and CCL-19 in CD4⁺ T cells and/or CD4⁻ cells. Efficient in vitro migration of CD69-deficient CD4 T cells toward the chemokine stimuli was the result of increased expression and/or affinity of chemokine receptors. In vivo CD69^−/− CD4 T cells accumulate in the intestine in higher numbers than B6 CD4 T cells as observed in competitive homing assay, dextran sodium sulphate (DSS)-induced colitis and antigen-specific transfer colitis. In DSS colitis CD69^−/− CD4 T cell accumulation in colonic lamina propria (cLP) was associated with increased expression of CCL-1, CXCL-10 and CCL-19 genes. Furthermore, treatment of DSS-administrated CD69^−/− mice with the mixture of CCL-1, CXCL-10 and CCL-19 neutralizing Abs significantly decreased the histopathological signs of colitis. Transfer of OT-II×CD69^−/− CD45RB^high CD4 T cells into RAG^−/− hosts induced CD4 T cell accumulation in cLP. This study showed CD69 as negative regulator of inflammatory responses in intestine as it decreases the expression of chemotactic receptors and ligands and reduces the accumulation of CD4 T cells in cLP during colitis.

Age-of-onset-dependent influence of NOD2 gene variants on disease behaviour and treatment in Crohn's disease

Background

Influence of genetic variants in the NOD2 gene may play a more important role in disease activity, behaviour and treatment of pediatric- than adult-onset Crohn’s disease (CD).

Methods

85 pediatric- and 117 adult-onset CD patients were tested for the three main NOD2 CD-associated variants (p.R702W, p.G908R and p.10007fs) and clinical data of at least two years of follow-up were compared regarding disease behaviour and activity, response to therapy and bone mineral density (BMD).

Results

Chronic active and moderate to severe course of CD is associated in patients with pediatric-onset (p=0.0001) and NOD2 variant alleles (p=0.0001). In pediatric-onset CD the average PCDAI-Score was significantly higher in patients carrying NOD2 variants (p=0.0008). In addition, underweight during course of the disease (p=0.012) was associated with NOD2 variants. Interestingly, osteoporosis was found more frequently in patients carrying NOD2 variant alleles (p=0.033), especially in pediatric-onset CD patients with homozygous NOD2 variants (p=0.037). Accordingly, low BMD in pediatric-onset CD is associated with a higher PCDAI (p=0.0092), chronic active disease (p=0.0148), underweight at diagnosis (p=0.0271) and during follow-up (p=0.0109). Furthermore, pediatric-onset CD patients with NOD2 variants are more frequently steroid-dependent or refractory (p=0.048) and need long-term immunosuppressive therapy (p=0.0213).

Conclusions

These data suggests that the presence of any of the main NOD2 variants in CD is associated with osteoporosis and an age of onset dependent influence towards underweight, higher disease activity and a more intensive immunosuppressive therapy. This observation supports the idea for an early intensive treatment strategy in children and adolescent CD patients with NOD2 gene variants.

CX(3)CR1(+) macrophages support IL-22 production by innate lymphoid cells during infection with Citrobacter rodentium

Innate immune cells, such as intestinal epithelial cells, dendritic cells (DCs), macrophages, granulocytes, and innate lymphoid cells provide a first line of defence to enteric pathogens. To study the role of CX(3)CR1(+) DCs and macrophages in host defence, we infected CX(3)CR1-GFP animals with Citrobacter rodentium. When transgenic CX(3)CR1-GFP animals are infected with the natural mouse pathogen C. rodentium, CX(3)CR1(-/-) animals showed a delayed clearance of C. rodentium as compared with (age- and sex-matched) wild-type B6 animals. The delayed clearance of C. rodentium is associated with reduced interleukin (IL)-22 expression. In C. rodentium-infected CX(3)CR1-GFP animals, IL-22 producing lymphoid-tissue inducer cells (LTi cells) were selectively reduced in the absence of CX(3)CR1. The reduced IL-22 expression correlates with decreased expression of the antimicrobial peptides RegIIIβ and RegIIIγ. The depletion of CX(3)CR1(+) cells by diphtheria toxin injection in CX(3)CR1-GFP × CD11c.DOG animals confirmed the role of CX(3)CR1(+) phagocytes in establishing IL-22 production, supporting the clearance of a C. rodentium infection.

CD69 regulates type I IFN-induced tolerogenic signals to mucosal CD4 T cells that attenuate their colitogenic potential

CD69 is highly expressed by lymphocytes at mucosal surfaces. We aimed to investigate the role of CD69 in mucosal immune responses. The expression of CD69 by CD4 T cells isolated from the spleen, mesenteric lymph nodes, small intestinal lamina propria, and colonic lamina propria was determined in specific pathogen-free B6 and TCR transgenic animals, as well as in germ-free B6 mice. Transfer colitis was induced by transplanting RAG(-/-) mice with B6 or CD69(-/-)CD45RB(high) CD4 T cells. CD69 expression by CD4 T cells is induced by the intestinal microflora, oral delivery of specific Ag, and type I IFN (IFN-I) signals. CD4 T cells from CD69(-/-) animals produce higher amounts of the proinflammatory cytokines IFN-γ, TNF-α, and IL-21, whereas the production of TGF-β1 is decreased. CD69-deficient CD4 T cells showed reduced potential to differentiate into Foxp3(+) regulatory T cells in vivo and in vitro. The transfer of CD69(-/-)CD45RB(high) CD4 T cells into RAG(-/-) hosts induced an accelerated colitis. Oral tolerance was impaired in CD69(-/-) and IFN-I receptor 1-deficient mice when compared with B6 and OT-II × RAG(-/-) animals. Polyinosinic-polycytidylic acid treatment of RAG(-/-) mice transplanted with B6 but not CD69(-/-) or IFN-I receptor 1-deficient CD45RB(high) CD4 T cells attenuated transfer colitis. CD69 deficiency led to the increased production of proinflammatory cytokines, reduced Foxp3(+) regulatory T cell induction, impaired oral tolerance, and more severe colitis. Hence, the activation Ag CD69 plays an important role in regulating mucosal immune responses.

NOD2 polymorphism predicts response to treatment in Crohn's disease--first steps to a personalized therapy

BACKGROUND AND AIMS

Great efforts have been made to predict disease behavior over time and the response to treatment in Crohn's disease (CD). Such understanding could personalize therapy. Early introduction of more aggressive therapies to patients at high risk and no introduction of predictable refractory treatments could become possible. We hence tested the influence of the NOD2 carrier status on treatment response.

PATIENTS AND METHODS

In 185 CD patients (age 45 ± 9.8 years, female n = 108, minimum disease duration 10 years), the three most common polymorphisms (p.Arg702Trp, p.Gly908Arg, p.Leu1007fsX1008) of NOD2 were tested by polymerase chain reaction and sequencing. Detailed clinical and medical history were obtained with a standardized questionnaire and by reviewing the medical charts. Treatments introduced were chosen by physicians blinded to genotype data.

RESULTS

The frequency of the NOD2 variant allele was about one-third (67, 30.2%) of CD patients. NOD2 carriers were more often treated with systemic and locally active steroids and with an immunosuppressant (Azathioprine/6-MP). NOD2 mutation carrier status was more often associated with systemic steroid [8.9% vs. wild-type (WT) 1.2%, P = 0.0086] and local-steroid refractory (14.9% vs. WT 3.5%; P = 0.001). The WT patients were significantly higher refractory to immunosuppressant (12.8% vs. NOD2 carriers, 0.5%, P = 0.03). Most WT patients were treated with TNF-α antagonists and remission rates were significantly higher in this group after 1 year of treatment (84% vs. NOD2 carriers, 33%, P = 0.07).

CONCLUSIONS

The study presents first hints for the NOD2 carrier status to be predictive for response to therapy. A higher percentage of CD patients with NOD2 mutation carrier status was steroid refractory but could be treated well with immunosuppressants. The WT status showed a higher response to steroids and remission rates within 1 year of anti-TNF-α therapy. On the way to personalized medicine, this approach should be further investigated in larger studies.

Role of gut-resident dendritic cells in inflammatory bowel disease

The gastrointestinal immune system, innate and adaptive, is continuously exposed to challenges provided by the enteric flora. In most cases, the result of mucosal immune responses is the development of tolerance. Mucosal dendritic cells initiate and regulate local immune responses. Uncontrolled local immune responses are thought to be a major factor in the development of inflammatory bowel disease, such as Crohn's disease and ulcerative colitis. This review will discuss the function of dendritic cells in the recognition of the enteric flora and their role in the development of intestinal inflammation.

Enteric flora expands gut lamina propria CX3CR1+ dendritic cells supporting inflammatory immune responses under normal and inflammatory conditions

CD103 or CX(3)CR1 surface expression defines distinct dendritic cells (DCs) and macrophages in the murine lamina propria of the colon (cLP). We investigated the surface marker and functional phenotype of CD103(+) and CX(3)CR1(+) cLP DCs and their role in transfer colitis. cLP CD11c(+) cells were isolated from specific pathogen-free or germ-free mice to elucidate the role of the commensal flora in their development. The cLP CD11c(+) cells are a heterogeneous cell population that includes 16% CX(3)CR1(+), 34% CD103(+), 30% CD103(-)CX(3)CR1(-) DCs, and 17% CD68(+/)F4/80(+)CX(3)CR1(+)CD11c(+) macrophages. All DCs expressed high levels of MHC II but low levels of costimulatory (CD40, CD86, and CD80) and coinhibitory (programmed death ligand-1) molecules. Ex vivo confocal microscopy demonstrated that CX(3)CR1(+)CD11c(+) cells, but not CD103(+) DCs, were reduced in the cLP of germ-free (CX(3)CR1-GFP) mice. The absence of the enteric flora prevents the formation of transepithelial processes by the CX(3)CR1(+) DCs. CX(3)CR1(+) DCs preferentially supported Th1/Th17 CD4 T cell differentiation. CD103(+) DCs preferentially induced the differentiation of Foxp3-expressing regulatory T cells. The stimulation of cLP DCs with fractalkine/CX(3)CL1 increased the release of IL-6 and TNF-alpha. In the absence of CX(3)CR1, the CD45RB(high) CD4 transfer colitis was suppressed and associated with reduced numbers of DCs in the mesenteric lymph nodes and a reduction in serum IFN-gamma and IL-17. The local bacteria-driven accumulation of CX(3)CR1(+) DCs seems to support inflammatory immune responses.

What are CX3CR1+ mononuclear cells in the intestinal mucosa?

Intestinal dendritic cells (DC) and macrophages play a key role for the maintenance of intestinal integrity by initiating innate and adaptive immune responses. Although DC and macrophages have been viewed as distinct lineages, the reliability of surface markers for the definition of DC and macrophages has recently been questioned. Here, I will discuss the ontogeny and function of CX(3)CR1(+) mononuclear cells in the small and large intestine.

Strongyloides stercoralis: a rare cause of obstructive duodenal stenosis

BACKGROUND

Strongyloidiasis is a rare helminthic infection in Europe, and it may cause duodenal obstruction.

METHODS

We report a patient who was admitted to our Medical Department with nausea and repeated vomiting since 10 years until food intake became impossible. Subsequent investigations revealed a duodenal obstruction at the upper third of the duodenum, as well as enterocolitis of the terminal ileum with eosinophils dispersed throughout the mucosa. Since food intake was still not possible after treatment with a course of i.v. PPI and prokinetic applications, we decided to perform a resection of the upper duodenum with Y-Roux reconstruction.

RESULTS

The histopathological examination of the resected specimen revealed strongyloidiasis.

CONCLUSION

Parasite infections such as strongyloidiasis represent a rare differential diagnosis of duodenal obstruction especially if patients originate from endemic regions.

Role of mucosal dendritic cells in inflammatory bowel disease

The gastrointestinal innate and adaptive immune system continuously faces the challenge of potent stimuli from the commensal microflora and food constituents. These local immune responses require a tight control, the outcome of which is in most cases the induction of tolerance. Local T cell immunity is an important compartment of the specific intestinal immune system. T cell reactivity is programmed during the initial stage of its activation by professional presenting cells. Mucosal dendritic cells (DCs) are assumed to play key roles in regulating immune responses in the antigen-rich gastrointestinal environment. Mucosal DCs are a heterogeneous population that can either initiate (innate and adaptive) immune responses, or control intestinal inflammation and maintain tolerance. Defects in this regulation are supposed to lead to the two major forms of inflammatory bowel disease (IBD), Crohn’s disease (CD) and ulcerative colitis (UC). This review will discuss the emerging role of mucosal DCs in regulating intestinal inflammation and immune responses.

Commensal gut flora drives the expansion of proinflammatory CD4 T cells in the colonic lamina propria under normal and inflammatory conditions

We tested in B6 mice whether the local expansion of CD4 T cells producing proinflammatory cytokines including IL-17 (Th17 cells) in the colonic lamina propria (cLP) depends on the commensal microflora. High numbers of CD4 Th17 cells were found in the lamina propria of the ileum and colon but not the duodenum, jejunum, mesenteric lymph nodes, spleen, or liver of specific pathogen-free (SPF) mice. The microflora is required for the accumulation of cytokine (IL-17, IFN-gamma, TNF-alpha, IL-10)-producing CD4 T cells in the cLP because only low numbers of cytokine-producing cLP CD4 T cells were found in syngeneic (age- and sex-matched) germfree mice. The fraction of cLP Th17 cells was higher in (type I and type II) IFN- but not IL-4- or IL-12p40-deficient SPF congenics. cLP CD4 Th17 cells produce IL-17 but not IFN-gamma, TNF-alpha, IL-4, or IL-10. cLP CD4 Th17 cells accumulate locally in colitis induced by adoptive transfer of IFN-gamma+/+ or IFN-gamma-/- CD4 T cells into congenic SPF (but not germfree) RAG-/- hosts. In this colitis model, cLP CD4 T cells that "spontaneously" produce IL-17 progressively increase in number in the inflamed cLP, and increasing serum IL-17 levels appear as the disease progresses. Commensal bacteria-driven, local expansion of cLP CD4 Th17 cells may contribute to the pathogenesis of this inflammatory bowel disease.

Dendritic cells in the recognition of intestinal microbiota

Mucosal dendritic cells (DCs) constantly survey the luminal microenvironment which contains commensal microbiota and potentially harmful organisms regulating pathogen recognition and adaptive as well as innate defense activation. Distinct mechanisms are beginning to emerge by which intestinal antigen sampling and handling is achieved ensuring specificity and contributing to redundancy in pathogen detection. Distinct DC subsets are associated with these mechanisms and regulate specific innate or adaptive immune responses to help distinguish between commensal microbiota, pathogens and self antigens. Understanding DC biology in the mucosal immune system may contribute to the unraveling of infection routes of intestinal pathogens and may aid in developing novel vaccines and therapeutic strategies for the treatment of infectious and inflammatory diseases.

Lamina propria dendritic cells in the physiology and pathology of the gastrointestinal tract

PURPOSE OF REVIEW

The mucosal immune system constantly surveys the intestinal microbiota. The outcome of this interaction is determined by the functional properties of dendritic cells, which play a key role in immune response by facilitating antigen sampling and pathogen recognition, as well as innate host defenses.

RECENT FINDINGS

Recent advances have provided insight into the diverse mechanisms involved in the acquisition of intestinal antigens and led to a new appreciation of organ-specific functional subspecification of dendritic cell subsets. Dendritic cells are not a rare cell type in the intestine but populate the entire lamina propria of the gastrointestinal tract as an extensive network. Distinct dendritic cell subsets may be associated with specific immune functions in the lamina propria and Peyer's patches. Newly discovered routes of antigen acquisition, such as the formation of transepithelial dendrites, allow dendritic cells direct access to the intestinal lumen to obtain information about commensal and pathogenic microorganisms. Dendritic cells emerge as key regulators of the intestinal immune system with their ability to direct intestine-specific migration and control of T cells.

SUMMARY

Dendritic cells play a major role in the complex interactions between the gut microbiota and the innate and adaptive immune system, leading to tolerance and immunity. Recent contributions have yielded important information that may aid in the development of novel therapeutic approaches to the treatment of inflammatory bowl disease and intestinal infections and to new immunization strategies.

CX3CR1-mediated dendritic cell access to the intestinal lumen and bacterial clearance

Dendritic cells (DCs) and macrophages are critical to innate and adaptive immunity to the intestinal bacterial microbiota. Here, we identify a myeloid-derived mucosal DC in mice, which populates the entire lamina propria of the small intestine. Lamina propria DCs were found to depend on the chemokine receptor CX3CR1 to form transepithelial dendrites, which enable the cells to directly sample luminal antigens. CX3CR1 was also found to control the clearance of entero-invasive pathogens by DCs. Thus, CX3CR1-dependent processes, which control host interactions of specialized DCs with commensal and pathogenic bacteria, may regulate immunological tolerance and inflammation.

Elevated nonspecific plasma proteins in allergic patients

Several allergen-specific plasma proteins, such as IgE and IgG subclasses, are commonly used for the evaluation of grade of allergy. In the present investigation, we compared the concentration of various nonspecific plasma proteins, mostly known as inflammation markers, in an allergic and a healthy population. Plasma from 130 children with single inhalation allergies to grass pollen, birch pollen, or house dust mites as well as from 42 healthy children was obtained during the symptom-free period. Patients showed symptoms including allergic rhinitis, dermatitis, and asthma with one single radioallergosorbent test (RAST) class 3 or higher. Plasma concentrations of soluble intercellular adhesion molecule-1(sICAM-1), soluble interleukin-2 receptor(sIL-2R), sE-selectin, and soluble vascular cell adhesion molecule-1 (1sVCAM-1) were analyzed by enzyme linked immunosorbent assay (ELISA) technique. Concentrations of sICAM-1 and sE-selectin were significantly increased in all patients compared to controls. In the single allergen groups, sICAM-1 elevation was significant in the grass and mite groups, but not in the birch group; while sE-selection increase was significant in the birch and mite groups, but not in the grass group. The elevation of sIL-2R in the allergic patients was obvious in each single allergen group, but not significant. No difference was observed in sVCAM-1 expression. In two groups of patients with mean age of 9.5 years versus 17.5 years, the analyzed parameters were not age dependent. The increased proteins may be useful as additional markers for efficacy and follow-up investigations of allergy therapies.

Review on the influence of stress on immune mediators, neuropeptides and hormones with relevance for inflammatory bowel disease

Stress has long been postulated to influence the progression of inflammatory bowel disease (IBD). Our current understanding of the relationship between stress and IBD is still limited, and hence explanation for the occurrence of relapses has remained largely speculative. Stress affects the immune system, the neuroendocrine system and the intestinal epithelia. Stress induces the release of pro-inflammatory Th1 cytokines and neuropeptides, such as tachykinins. Thereby, stress may induce alterations of the intestinal epithelium via the interaction of the neuroendocrine and immune system and may induce relapses of IBD. The present review focuses on this network and highlights the role of distinct mediators and mechanisms, i.e. neurotransmitters, hormones and immune cells, which are involved in the response to stress on the one hand, and contribute to the onset, progression or relapses of IBD on the other.

Elevated CD154 (CD40 ligand) synthesis in T-cells from allergic patients after nonspecific stimulation in vitro

The interaction of the CD154 molecule (CD40 ligand, gp39) on activated T-cells with the CD40 antigen on B-cells seems to play a key role in immunoglobulin class switching. We aimed to compare the capacity of intracellular CD154 expression after nonspecific stimulation with phorbol-12-myristate-13-acetate and ionomycin on separated T-cells from allergic patients and healthy donors. We analyzed blood from 104 patients allergic to grass pollen, house dust mites or birch pollen, and from 44 healthy donors. Lymphocytes were isolated using a density gradient and B-cells were extracted by magnet-activated cell separation (MACS) using anti-CD19 microbeads. Cells were nonspecifically stimulated for 5 h, permeabilized and stained with anti-CD154 for fluorescence-activated cell sorter analysis. It was found that stimulation induced a 1.4% increase of intracellular CD154+ T-cells; a 4.6% increase of mean channel fluorescence of all T-cells from healthy donors; a 6.1% increase in intracellular CD154+ T-cells; and a 28.1% increase of mean channel fluorescence of all T-cells from allergic patients. The data demonstrated an elevated capability of B-cell independent CD154 synthesis in T-cells from allergic patients when compared to healthy individuals. It is possible that the enhanced IgE production of B-cells from allergic patients might be partly due to the phenomena described.