Phenotype Of Intraepithelial Lymphocytes Research Articles

Nurturing the phenotype: Environmental signals and transcriptional regulation of intestinal γδ T cells.

The intestinal epithelium harbours a unique lymphocyte population, the intraepithelial lymphocytes (IELs). A large fraction of IELs is represented by γδ T cells. Their role in epithelial homeostasis and immune response is well documented, but a conclusive view of their developmental pathway is still missing. In this review, we discuss the existing literature as well as recent advances regarding the tissue adaptation of γδ IELs, both for the characteristic cytotoxic subset and the newly described noncytotoxic subset. We particularly highlight the environmental cues and the transcriptional regulation that equip γδ T cells with their IEL phenotype.

CD4+CD8αα+ is the dominant phenotype of intraepithelial lymphocytes and regulated by ThPOK and Runx3 in oral lichen planus.

Oral lichen planus (OLP) is a common T cell-mediated oral mucosal immune inflammatory disease. Intraepithelial lymphocytes (IELs) are a unique subset of T cells that play an important role in regulating immune response. This study aims to investigate the phenotype and the differentiation mechanism of IELs in OLP. The expression of CD4, CD8α, CD8β, T-helper-inducing POZ/Krueppel-like factor (ThPOK), and RUNX family transcription factor 3 (Runx3) in the epithelium and peripheral blood mononuclear cells (PBMCs) of OLP was determined by immunofluorescence and immunohistochemistry. Then, the correlations among them were analyzed. Naïve CD4+ T cells were sorted from blood of OLP patients and stimulated with retinoic acid (RA) and transforming growth factor-β1 (TGF-β1). Then the expression of CD4, CD8α, CD8β, ThPOK, and Runx3 was investigated by immunocytochemistry. CD8α expression and CD8αα+ cells were upregulated in the epithelium of OLP, whereas they were downregulated in PBMCs of OLP. CD8β was not expressed in the epithelium of OLP. CD4, CD8α, and Runx3 expression and CD4+CD8α+ cells were increased, whereas ThPOK expression was decreased in the epithelium of OLP. CD8α expression was positively correlated with Runx3 expression, whereas ThPOK expression was negatively correlated with Runx3 expression. After RA and TGF-β1 stimulation, CD8α and Runx3 expression was upregulated, and ThPOK expression was downregulated in naïve CD4+ T cells. CD4+CD8αα+ IELs may be the dominant phenotype of IELs in OLP, and the differentiation of CD4+CD8αα+ IELs in OLP is negatively regulated by ThPOK and positively regulated by Runx3.

Flow cytometry for the assessment and monitoring of aberrant intraepithelial lymphocytes in non-responsive celiac disease and non-celiac enteropathies

BackgroundFew data are available on flow cytometry (FC) for monitoring intraepithelial lymphocytes (IELs) in refractory celiac disease (RCD), non-responsive celiac disease (NRCD), and non-celiac enteropathies (NCEs).AIMS.1) To investigate the significance of monitoring IELs immunophenotype with FC in patients with NRCD, RCD and NCEs; 2) to evaluate FC concordance with immunohistochemistry (IHC) and γ-TCR clonality analysis. MethodsPatients investigated between January-2012 and February-2023 were divided into two groups: 1)confirmed RCD or NRCD being investigated for persistent symptoms and suspected complications of celiac disease (CD); 2)NCEs lacking clinical/histological response. Clinical/molecular features and outcomes were retrospectively collected and analysed according to presence/absence of aberrant IELs on FC (cut-off≥20 % CD103+sCD3-CD8-iCD3+ IELs). Results52 patients (18 RCD,21 NRCD,13 NCEs; 38F, 55±13 years; median follow-up 30 months, IQR 2-58) underwent 100 FC IELs determinations. 22/52 had ≥2 FC determinations and IEL phenotype remained unchanged over time in all them (κ=1.00). Aberrant IEL phenotype in CD was associated with increased mortality (HR 4.2, 95 % CI 1.5–11.9, p < 0.01). No patients with NCEs had an aberrant IEL phenotype at FC, although 3/13 developed lymphoma and 4/13 died. Concordance of FC was fair with both IHC (κ=0.40) and γ-TCR clonality analysis (κ=0.22). ConclusionFC is accurate for assessing and monitoring IEL phenotype and providing important prognostic information in celiac patients. Further study is needed on its role in NCEs.

Expansion of the intraepithelial lymphocyte (IEL) compartment results in an increased bioenergetic profile and reduced IFNγ production in γδ IELs.

Abstract Intestinal γδ intraepithelial lymphocytes (γδ IEL) serve as the first line of defense against pathogen invasion. We recently identified a transmissible hyperproliferative γδ IEL (γδ HYP) phenotype that protects against enteric infection, and these mice have no signs of overt intestinal pathology. Given that IELs are metabolically constrained to prevent aberrant activation, we hypothesized that the bioenergetics of γδ HYPIELs may regulate their effector function. Electron microscopy revealed a 70% increase in mitochondrial number (p=0.005) and 24% increase in mitochondrial area (p=0.04) in γδ HYPIELs relative to WT. Seahorse mitochondrial stress assays on γδ IELs showed a 50% increase in spare respiratory capacity in γδ HYPIELs compared to WT (p=0.014). Mitochondrial metabolism was shown to influence γδ T cell cytokine production, and similarly, we found that stimulation with PMA and ionomycin reduced the frequency of IFNγ +γδ IELs by 59% in γδ HYPrelative to WT (p&amp;lt;0.0001). We also observed that γδ HYPIELs exhibit higher CD39 expression compared to WT (p&amp;lt;0.0001), and a CD39 hisubset produces less IFNγ compared to CD39 negand CD39 intcells (p&amp;lt;0.0001) The addition of the ATP-synthase inhibitor oligomycin during IEL stimulation increased IFNγ production by both WT and γδ HYPIELs by 66% and 44%, respectively (p&amp;lt;0.0001). Together, our data demonstrate that the shift towards high CD39 expression and elevated mitochondrial metabolism contribute to decreased IFNγ production in γδ HYPIELs. Further understanding of the mechanisms regulating γδ IEL homeostasis and effector function may ultimately allow fine tuning of mucosal surveillance to confer protection against intestinal injury or infection while limiting aberrant cytotoxicity. Supported by NJCCR (COCR23PRF024)

P013 A single cell approach reveals immune cell dynamics in Inflammatory Bowel Disease (IBD) and highlights association of CD8 intraepithelial lymphocytes (IELs) with response to vedolizumab treatment

Abstract Background Dysregulated immunity in the gut is central to the pathogenesis of inflammatory bowel disease (IBD) and its contribution to patient responses following biologic treatment is poorly understood. Single cell protein- and sequencing-based analyses have provided unprecedented understanding of cell heterogeneity and function in IBD. In this study, recent cytometry by time of flight (CyTOF) and single cell transcriptomics technology advancements have been leveraged to characterize the intestinal mucosa of IBD patients treated with vedolizumab. Methods Single cell RNA sequencing from IBD mucosa biopsies were analysed to derive cell molecular signatures and deconvolute bulk transcriptomic datasets of UC patients treated with biologics. Cellular abundance differences in response to therapy were in-silico validated in both vedolizumab and anti-TNF treated patients. CyTOF analysis of intestinal biopsies from 24 UC patients and 29 healthy controls (HC) was applied to complement transcriptomic findings and further understand T cell dysregulation in disease activity and treatment response. CyTOF panels were focused on T cell polarization, memory differentiation, effector function and homing. Mucosal microbiota analysis by 16S rRNA gene sequencing was employed and correlated with patient/host cellular dynamics. Results Deconvolution analysis of UC bulk transcriptomic data with single cell molecular signatures from mucosa biopsied samples (Smillie et al.) revealed decreased abundance of CD8 IELs along with increased activated T cells, inflammatory/activated stromal cells in non-responders to both vedolizumab and anti-TNF therapy compared with responders and HC. CyTOF analysis of intestinal biopsies from patients responding or not responding to biologic treatment confirms cellular alterations at the protein level. Specifically, in patients that respond to vedolizumab, we observed greater levels of immune cells with CD8 IEL phenotype (CD8+ CD69+ CD103+) similar to HC. In contrast, in non-responder patients we observed lower levels of these cells but higher abundances of CD8+ Tc17 and CD4+ Th17 cells. In non-responders, Tregs were also elevated compared with responders and HC. Assessment of mucosal biopsies with 16S rRNA gene analysis also revealed microbial metabolic pathways supportive of CD8 IEL development associated with elevated CD8 IELs in vedolizumab treatment responders. Conclusion This multi-modal and deep molecular phenotyping approach revealed CD8 IELs to be associated with healthy intestinal tissue and treatment response to vedolizumab. These findings suggest that CD8 IELs may be beneficial for supporting and restoring tissue homeostasis.

СУБПОПУЛЯЦИОННЫЙ СОСТАВ ИНТРАЭПИТЕЛИАЛЬНЫХ ЛИМФОЦИТОВ У ПАЦИЕНТОВ С БОЛЕЗНЬЮ КРОНА

Crohn’s disease is an autoimmune inflammatory bowel disease characterized with the chronic relapsing-remitting inflammation, mainly in the terminal parts of the small intestine and colon, as a result of a genetic predisposition or environmental factors influence. It is associated with impaired bacterial clearance and changes in immunological parameters what resulted in disruption of the gastrointestinal tract ecosystem, formed by the microbiome and non-living components such as mucus, food metabolites or additives. Intraepithelial lymphocytes of the gastrointestinal tract play an important role in mucosal immunity and their phenotype and functional profile is largely determined by the microbiome composition and environmental factors affecting it (diet, smoking, seasonal changes, air pollution, hygiene, etc.). In this investigation the changes in intraepithelial lymphocytes phenotype of small and large intestine were shown in patient with Crohn’s disease as well as the correlation of intraepithelial lymphocytes phenotype with clinical data was established. Obtained data may be used as a hallmark of immune inflammation in the gut and make intraepithelial lymphocytes as ideal candidate for targeting in further immunoregulation of mucosal adaptive immune response against autoantigens.

Oral immunization induces a novel CXCR6+ β7+ intraepithelial lymphocyte subset predominating in the small intestine.

Intestinal T cells form a central part of the front-line defence against foreign organisms and need to be situated in the mucosa where infection occurs. It is well accepted that immunization by a mucosal route favours localization of antigen-specific effector T cells in the mucosal epithelium, while systemic immunization does not. The aim of the study is to determine how homing receptors are specifically involved in retaining effector T cells in the small intestine after oral immunization. We here demonstrate that the chemokine receptor CXCR6, integrins β7 and CD29 contribute differentially to the epithelial retention phenotype of CD8+ T cells in the small intestine of mice. CD8+ intraepithelial lymphocytes (IELs) of unvaccinated mice are predominantly β7 single positives, and subcutaneous immunization-induced antigen-specific CD8+ effector IELs are mainly composed of CXCR6+ , CD29+ and CXCR6+ CD29+ cells. Strikingly, the majority of oral immunization-induced antigen-specific CD8+ effector IELs exhibit a distinct, tissue-specific CXCR6+ β7+ double-positive phenotype, cytotoxic potential and enhanced intraepithelial localization. Transfer of antigen-specific CD8+ T cells preactivated with certain immuno-stimuli (such as monophosphoryl lipid A) results in increased accumulation of donor IELs with the CXCR6+ β7+ phenotype. As β7 exclusively paired with αE on IELs, our results strongly suggest that CXCR6 may cooperate with the heterodimer αEβ7 to preferentially retain intestinally induced effector IELs in the epithelium. The identification of this novel IEL phenotype has significant implications for the development of vaccines and therapeutic strategies to enhance gut immunity.

Butyrophilin-like proteins display combinatorial diversity in selecting and maintaining signature intraepithelial \u03b3\u03b4 T cell compartments

Butyrophilin-like (Btnl) genes are emerging as major epithelial determinants of tissue-associated γδ T cell compartments. Thus, the development of signature, murine TCRγδ+ intraepithelial lymphocytes (IEL) in gut and skin depends on Btnl family members, Btnl1 and Skint1, respectively. In seeking mechanisms underlying these profound effects, we now show that normal gut and skin γδ IEL development additionally requires Btnl6 and Skint2, respectively, and furthermore that different Btnl heteromers can seemingly shape different intestinal γδ+ IEL repertoires. This formal genetic evidence for the importance of Btnl heteromers also applied to the steady-state, since sustained Btnl expression is required to maintain the signature TCR.Vγ7+ IEL phenotype, including specific responsiveness to Btnl proteins. In sum, Btnl proteins are required to select and to maintain the phenotypes of tissue-protective γδ IEL compartments, with combinatorially diverse heteromers having differential impacts on different IEL subsets.

Type 2 refractory celiac disease on third-generation capsule endoscopy and enteroscopy: typical appearance of ulcerative jejunitis.

We report the case of a 43-year-old woman with a medical history of active smoking who presented with abdominal pain that had appeared 4 months ago. The physical examination revealed periumbilical pain associated with weight loss. Laboratory studies revealed elevated inflammatory markers (C-reactive protein: 54 mg/dL) and hypoalbuminemia (22 g/L). Abdominal computed tomography (CT) and magnetic resonance enterography (MRE) showed a thickening of the small bowel at the junction between the jejunum and ileum, at 30 cm, suggesting Crohn’s disease. Gastroscopy showed an appearance of duodenal villous atrophy, confirmed by Marsh stage 3c biopsy findings. Anti-transglutaminase antibodies were positive at 17 U/ml. 18F-fluorodeoxyglucose (18F-FDG) positron emission tomography (PET) detected a jejunoileal accumulation of 18F-FDG, with a standard uptake value (SUV) at of 8.1. Small-bowel capsule endoscopy confirmed the appearance of villous atrophy with the presence of sporadic ulceration ([Fig. 1]), then a completely ulcerated jejunoileal segment over several tens of centimeters, with necrotic pseudomembranous and hemorrhagic spots ([Fig. 2], [Video 1]). Biopsies of this ulcerated area were performed with double-balloon enteroscopy ([Fig. 3]), histological examination revealing refractory type 2 celiac disease (RCD) characterized by an increased clonal population of abnormal intraepithelial lymphocytes (IEL). Abnormal IEL phenotype was described with disappearance of the classical markers such as CD4 or CD5 and the presence of NKp46 marker, but without any sign of high-grade lymphoma ([Fig. 4]). Systemic corticosteroid therapy was initiated but did not improve the patient’s symptoms. She developed an occlusive syndrome requiring surgical resection of the ulcerated jejunoileal segment (39 cm). The surgical follow-up was simple. The diagnosis of type 2 RCD without high-grade lymphoma was confirmed. Gluten-free diet and open-capsule budesonide treatment were initiated with close surveillance of the patient due to the high risk of progression to T-cell lymphoma.

A Single-Tube, EuroClonality-Inspired, TRG Clonality Multiplex PCR Aids Management of Patients with Enteropathic Diseases, including from Formaldehyde-Fixed, Paraffin-Embedded Tissues

Celiac disease is a chronic inflammation of the small intestine with villous atrophy that can become refractory to a gluten-free diet. Two categories of refractory celiac disease can be distinguished by the phenotype of intraepithelial lymphocytes and the status of TRG genes. Their distinction is important because 30% to 50% of type II but only 0% to 14% of type I evolve to an aggressive enteropathy-associated T-cell lymphoma and therefore require intensive treatment. Currently, differential diagnosis integrates immunohistochemistry, immunophenotyping, and TRG clonality analyses, but each has limitations. A single-tube multiplex TRG PCR (ECN) was prospectively compared to an in-house two-tube TRG PCR (N2T) in 73 samples, including 67 cryopreserved intestine tissues. Thirteen formalin-fixed, paraffin-embedded (FFPE) samples were also analyzed retrospectively. The ECN PCR had comparable efficiency to detect major clonal rearrangements in highly infiltrated tissues from T-cell lymphoproliferative disorders and type II refractory celiac disease and to detect the persistence of minor clones in type II refractory celiac disease follow-up samples. The ECN PCR abolished the risk of amplification of false-positive weak clonal rearrangements in cryopreserved specimens and allowed improved detection of clonal rearrangements in DNA from FFPE samples. The ECN PCR allows robust assessment of cryopreserved and FFPE digestive tissues at diagnosis and follow-up of enteropathies with villous atrophy, thus guiding therapeutic management.

The Innate Immune System in the Gastrointestinal Tract: Role of Intraepithelial Lymphocytes and Lamina Propria Innate Lymphoid Cells in Intestinal Inflammation.

The gastrointestinal tract harbors the largest microbiota load in the human body, hence maintaining a delicate balance between immunity against invading pathogens and tolerance toward commensal. Such immune equilibrium, or intestinal homeostasis, is conducted by a tight regulation and cooperation of the different branches of the immune system, including the innate and the adaptive immune system. However, several factors affect this delicate equilibrium, ultimately leading to gastrointestinal disorders including inflammatory bowel disease. Therefore, here we decided to review the currently available information about innate immunity lymphocyte subsets playing a role in intestinal inflammation. Intestinal innate lymphocytes are composed of intraepithelial lymphocytes (IELs) and lamina propria innate lymphoid cells (ILCs). While IELs can be divided into natural or induced, ILCs can be classified into type 1, 2, or 3, resembling, respectively, the properties of TH1, TH2, or TH17 adaptive lymphocytes. Noteworthy, the phenotype and function of both IELs and ILCs are disrupted under inflammatory conditions, where they help to exacerbate intestinal immune responses. The modulation of both IELs and ILCs to control intestinal inflammatory responses represents a major challenge, as they provide tight regulation among the epithelium, the microbiota, and the adaptive immune system. An improved understanding of the innate immunity mechanisms involved in gastrointestinal inflammation would therefore aid in the diagnosis and further treatment of gastrointestinal inflammatory disorders.

Open-Capsule Budesonide for Refractory Celiac Disease.

Refractory celiac disease (RCD) is a rare condition often associated with poor prognosis. Various immunosuppressive medications (IMs) have been used with modest success. We describe outcomes in patients treated with open-capsule budesonide (OB), including those for whom IM treatment failed. We identified RCD patients treated with OB at Mayo Clinic, Rochester, Minnesota from 2003 to 2015. Demographic, serologic, and clinical variables were analyzed. We identified 57 patients who received OB for suspected RCD. Based on clonal T-cell receptor gamma gene rearrangement or aberrant phenotype of intraepithelial lymphocytes (IELs), 13 patients (23%) were classified as having RCD-2 and 43 (75%) as RCD-1. In one patient (2%) TCR gene rearrangement status was unknown. Most patients were women (69%), mean (s.d.) age was 60.5 (3.5) years and body mass index was 28.4 (4.5) kg/m2. The majority had diarrhea (72%), with median of 6 bowel movements per day (range, 4-25). IM treatment (azathioprine, systemic corticosteroids, or regular budesonide) had failed in nearly half. Twenty-four patients (42%) had anemia and 12 (21%) had hypoalbuminemia. All had Marsh 3 lesions on biopsy: 3a (19%), 3b (46%), and 3c (35%). After OB therapy, the majority had clinical (92%) and histologic (89%) improvement. Follow-up biopsy in 7 out of 13 patients with RCD-2 (53%) showed an absence of clonal TCR gamma gene rearrangement/aberrant IEL phenotype previously seen. On follow-up, 2 patients (4%) died of enteropathy-associated T-cell lymphoma. Most patients with RCD show clinical and histopathologic improvement with OB therapy, including those with failure of IMs. OB is a promising therapeutic option for management of RCD.

Deciphering the Different Types of Refractory Celiac Disease

Universite Paris Descartes-Sorbonne Paris Centre Gastroenterology department, Hopital Europeen Georges Pompidou APHP, Paris Inserm U989, Hopital Europeen Georges Pompidou APHP Paris, France Fifteen years ago has emerged the concept of refractory celiac disease (RCD). [1,2] RCD is defined by persisting malabsorption and villous atrophy after one year of strict GFD ascertained by a dietician. RCD has been subdivided into two subgroups according to the normal (type I RCD (RCDI)) or abnormal phenotype of intraepithelial lymphocytes (IEL) (type II RCD (RCDII). RCDI is indistinguishable from active CD and is characterized by a polyclonal repertoire. Survival of patients with RCDI is slightly inferior to that of those with celiac disease. [3,4] In contrast, RCDII is a severe enteropathy with frequent intractable ulcerative duodeno-jejunitis. RCDII is characterized by a clonal repertoire and is considered as a low-grade intraepithelial lymphoma. [1,2] The five year survival rate of patients with RCDII is around 50%. This poor prognosis is due to severe malnutrition and increased risk of overt lymphoma. One of the current challenges in RCD is to ascertain the type of RCD. Indeed, diagnosis of RCD has become highly specialized. It requires small bowel endoscopic specialized investigations such as capsule endoscopy and double balloon enteroscopy. [5,6] Intestinal biopsy needs to be studied by different complementary techniques such as immunohistochemistry, flow cytometry, and Multiplex PCR, all necessary to ascertain the precise diagnosis. Recent studies have reported case series of chronic intestinal diseases mimicking the both types of RCD. RCDI needs to be distinguished from other causes of non clonal villous atrophy such as enteropathy associated with common variable immunodeficiency (CVID). [7] Demonstration of HLA haplotypes encoding HLA-DQ2 or DQ8 can be useful as their absence excludes CD or RCD as a cause of villous atrophy. [8] Nevertheless, genotypes HLA-DQ2/DQ8 are also found in 77% of CVID patients with enteropathy mimicking CD defined by intestinal intra-epithelial lymphocytosis. [7] So evidence of serum hypogammaglobulinemia and histopathological features such as intestinal plasmocytic rarefaction or nodular lymphoid hyperplasia appear essential to distinct CVID enteropathy from RCDI. [7] RCDII needs to be distinguished from other cases of clonal enteropathy with villous atrophy. Flow cytometry allows to tell the difference between RCDII and other intestinal clonal malignancies with villous atrophy. Indeed, demonstration of excess of CD4+IEL with a specific Vbeta repertoire is essential for diagnosis of intestinal CD4 lymphoproliferations. [9] Diagnosis may be particularly tricky when CD4 lymphoproliferation [9] or large granular lymphocytic leukemia (LGL) [10] complicate an authentic CD. Consequently, spectrum of RCD has been recently substantially extended. Advances in accuracy of diagnostic tools could reduce the number of undiagnosed RCD and increase the frequency of RCD currently estimated to 1 to 2% of CD patients. [11,12] Besides epidemiological interest, improvement of diagnostic tools allowed precise diagnosis of RCD type and appropriate treatment. By example, distinction between RCDII and CD complicated by LGL is crucial as cyclosporin, inefficient in RCDII, is in contrast very useful for treating LGL. Indeed, treatment of RCD remains another challenge particularly in case of RCDII patients who have poor prognosis and for whom referral treatment does not yet exist. Immunosuppressors are poorly efficient and may possibly trigger overt lymphoma. [13] Purine analogues such pentostatine or cladribine (2 CDA) have been largely used in the past with slight therapeutic effect. [4,14,15] Autologous haematopoietic stem cells transplantation represents an interesting alternative but when combined to chemotherapy for hopping sustained reduction of abnormal IEL. [16,17] We are currently evaluating this strategy in a prospective phase II trial. Many advances in the understanding of the pathogenesis of RCDII were made by deciphering the anti-apoptotic signaling pathway of the cytokine IL-15 which prevents the elimination of IEL in CD and RCDII. [18] The IL-15 induced antiapoptotic signaling pathway includes activation of IL15Rβγ, Jak3, STAT5 and Bcl-xL [19] which represent so many therapeutic targets. Blocking the effect of IL-15 appears of a particular interest in RCDII but may probably be useful in other types of RCD with possible involvement of IL-15 such as RCDI or LGL-complicated CD. [20] Continuing the characterization of the different forms of RCD will probably guide next pathogenic studies and permit to increase our therapeutic efficacy in the future.

Clinical and Immunologic Features of Ultra-Short Celiac Disease

The clinical effects of gluten-sensitive enteropathy with villous atrophy limited to the duodenal bulb (D1) have not been delineated in adults with celiac disease. We investigated the sensitivity of D1 biopsy analysis in the detection of celiac disease, the number and sites of biopsies required to detect ultra-short celiac disease (USCD, villous atrophy limited to D1), and the clinical phenotype of USCD. We performed a prospective study of 1378 patients (mean age, 50.3 y; 62% female) who underwent endoscopy at a tertiary medical center in the United Kingdom from 2008 through 2014; routine duodenal biopsy specimens were collected from D1 and the second part of the duodenum (D2). Quadrantic D1 biopsy specimens were collected from 171 consecutive patients with a high suspicion of celiac disease (mean age, 46.5 y; 64% female). Clinical data from patients diagnosed with USCD, based on biopsy analysis, were compared with those from patients with conventional celiac disease (CCD) (villous atrophy beyond D1) and individuals without celiac disease (controls). The number of intraepithelial lymphocytes (IELs) and immune phenotypes were compared between D1 vs D2 in patients with celiac disease. Of the 1378 patients assessed, 268 (19.4%) were diagnosed with celiac disease; 9.7% of these patients had villous atrophy confined to D1 (USCD; P < .0001). Collection of a single additional biopsy specimen from any D1 site increased the sensitivity of celiac disease detection by 9.3%-10.8% (P < .0001). Patients with USCD were younger (P= .03), had lower titers of tissue transglutaminase antibody (P= .001), and less frequently presented with diarrhea (P=.001) than patients with CCD. Higher proportions of patients with CCD had ferritin deficiency (P= .007) or folate deficiency (P= .003) than patients with USCD or controls. Patients with celiac disease had a median of 50 IELs/100 enterocytes in D1 and a median of 48 IELs/100 enterocytes (P= .7) in D2. The phenotype of IELs from patients with D1 celiac disease was indistinguishable from those of patients with D2 celiac disease. Collection of a single additional biopsy specimen from any site in the D1 intestine increases the sensitivity of detection for celiac disease. Patients with USCD may have early stage or limited celiac disease, with a mild clinical phenotype and infrequent nutritional deficiencies.

TLR2-Dependent Signaling for IL-15 Production Is Essential for the Homeostasis of Intestinal Intraepithelial Lymphocytes.

TLR2 signaling is related to colitis and involved in regulation of innate immunity in the intestinal tract, but the mechanisms remain unclear. The aim of this study is to investigate how TLR2 affects differentiation of intraepithelial lymphocytes (IELs) and regulates the susceptibility of colitis. IELs were isolated from the small intestine and colon of mice, respectively. The IEL phenotype, activation, and apoptosis were examined using flow cytometry and RT-PCR. IL-15 expression and IEL location were detected through immunohistochemistry. The experimental colitis was induced by administration of dextran sulfate sodium (DSS). We found that the numbers of CD8αα +, CD8αβ +, and TCRγδ + IELs were significantly decreased in TLR2-deficient mice and the residual IELs displayed reduced activation and proliferation and increased apoptosis, accompanied with impaired IL-15 expression by intestinal epithelial cells (IECs). Further study showed that TLR2 signaling maintained the expression of IL-15 in IEC via NF-κB activation. Moreover, TLR2-deficient mice were found to be more susceptible to DSS-induced colitis as shown by the increased severity of colitis. Our results demonstrate that IECs contribute to the maintenance of IELs at least partly via TLR2-dependent IL-15 production, which provides a clue that may link IECs to innate immune protection of the host via IELs.

Aryl Hydrocarbon Receptor Activation Down-Regulates IL-7 and Reduces Inflammation in a Mouse Model of DSS-Induced Colitis.

The pathogenesis of inflammatory bowel disease (IBD) is associated with dysregulation of intestinal immune system. Aryl hydrocarbon receptor (AHR) is believed to control the chronic inflammation in the gut. Besides, interleukin-7 (IL-7) is proved to be an important cytokine that activates mucosal inflammation in IBD. Moreover, intraepithelial lymphocytes (IELs) are one of the key immunological compartments involved in regulating intestinal inflammation. In this study, we investigated the function of 6-formylindolo (3,2-b) carbazole (Ficz), a ligand of AHR, on IL-7, colitis, and IEL phenotypes. Colitis was induced by administration of dextran sulfate sodium (DSS) to wild-type C57BL/6J mice for 7 days. Mice were weighted, colon tissues were collected and measured, and histology analyses were performed. IELs were isolated from colon, and the phenotype and activation of IELs were examined using flow cytometry detection. The expression of AHR and IL-7 was measured by immunofluorescence, Western blot, and RT-PCR. Ficz down-regulated epithelial-derived IL-7 expression in mice with DSS-induced colitis and ameliorated DSS-induced colitis. Ficz also decreased CD8αβ(+) and CD8(+) IEL subpopulations, enhanced TCRγδ(+) IEL subpopulation, and reduced the percentage of activated CD4(+) and CD8(+) subpopulations. Ficz could down-regulate epithelial-derived IL-7 expression in mice with DSS-induced colitis and inhibit inflammation in the gastrointestinal tract of mice. AHR-related compounds might be the new and promising therapeutic medicaments for the treatment of patients with IBD.

Disturbance of intraepithelial lymphocytes in a murine model of acute intestinal ischemia/reperfusion

Strategically located at the epithelial basolateral surface, intraepithelial lymphocytes (IELs) are intimately associated with epithelial cells and maintain the epithelial barrier integrity. Intestinal ischemia-reperfusion (I/R)-induced acute injury not only damages the epithelium but also affects the mucosal barrier function. Therefore, we hypothesized that I/R-induced mucosal damage would affect IEL phenotype and function. Adult C57BL/6J mice were treated with intestinal I/R or sham. Mice were euthanized at 6 h after I/R, and the small bowel was harvested for histological examination and to calculate the transmembrane resistance. Occludin expression and IEL location were detected through immunohistochemistry. The IEL phenotype, activation, and apoptosis were examined using flow cytometry. Cytokine and anti-apoptosis-associated gene expressions were measured through RT-PCR. Intestinal I/R induced the destruction of epithelial cells and intercellular molecules (occludin), resulting in IEL detachment from the epithelium. I/R also significantly increased the CD8αβ, CD4, and TCRαβ IEL subpopulations and significantly changed IEL-derived cytokine expression. Furthermore, I/R enhanced activation and promoted apoptosis in IELs. I/R-induced acute intestinal mucosal damage significantly affected IEL phenotype and function. These findings provide profound insight into potential IEL-mediated epithelial barrier dysfunction after intestinal I/R.

Refractory coeliac disease

Concept of refractory coeliac disease (RCD) emerged in the past decade and refers to persistence of malnutrition and intestinal villous atrophy for more than 1 year strict gluten-free diet in coeliac patients. Diagnosis of this condition remains difficult and conditions treatment and follow-up. RCD has been subdivided into two subgroups according to the normal [type I RCD (RCDI)] or abnormal phenotype of intraepithelial lymphocytes [type II RCD (RCDII)]. RCDII is considered as a low-grade intraepithelial lymphoma and has a very poor prognosis, leading to intractable ulcerative jejunitis, gastrointestinal and extra-intestinal dissemination of the abnormal intraepithelial lymphocytes, and to their frequent transformation into a high-grade invasive lymphoma. Herein, we review here the distinctive diagnostic features of RCDI and RCDII, the risk of developing overt lymphoma and different therapeutic approaches.

Immunohistochemical and T-Cell Receptor Gene Rearrangement Analyses as Predictors of Morbidity and Mortality in Refractory Celiac Disease

Classification of refractory celiac disease (RCD) is based on the presence or absence of monoclonal expansions of intraepithelial lymphocytes (IELs) with an aberrant immunophenotype. To investigate the contribution of IEL parameters toward mortality and morbidity in RCD. IEL phenotype by immunohistochemistry and T-cell receptor (TCR) gene rearrangement by polymerase chain reaction were assessed in 73 RCD patients (type I=67, type II=6). Detection of a monoclonal TCR gene rearrangement and presence of <50% CD3 CD8 IELs were considered abnormal. Time to worsening of clinical symptoms and predictors of worsening were calculated by Kaplan-Meier and Cox proportional hazard analyses. Fewer than 50% CD3 CD8 IELs were detected in 30 patients and monoclonal TCR rearrangements in 6. Three patients died and 40 suffered clinical worsening despite treatment. Estimated 5-year survival rates decreased from 100% in patients with >50% CD3 CD8 IELs and polyclonal TCR to 88% and 50% in patients with <50% CD3 CD8 IELs and monoclonal TCR, respectively. Clinical worsening was more frequent (100%) among patients harboring a monoclonal TCR gene rearrangement with <50% CD3 CD8 IELs. These patients also showed shorter median time to clinical worsening (11 mo) when compared to patients with <50% CD3 CD8 IELs alone (21 mo), polyclonal TCR (38 mo), or >50% CD3 CD8 IELs alone (66 mo). After adjusting for age and gender, only the presence of <50% CD3 CD8 IELs was associated with increased risk for clinical worsening despite negative celiac serologies (hazard ratio=4.879; 95% confidence interval, 1.785-13.336; P=0.002). Presence of <50% CD3 CD8 IELs is a risk factor for clinical worsening in RCD and combined with a monoclonal TCR gene rearrangement result is associated with increased mortality. IEL phenotype and TCR gene rearrangement analyses provide differential information regarding morbidity and mortality in RCD.

P175 Requirement of Axl for the migration of intestinal gammadelta T cells by upregulating IL-7R alpha and chemokine expression

Introduction Axl receptor tyrosine kinase (Axl) has been known to play a crucial role in cell survival, proliferation, and migration, but little is known about its regulatory role in the migration of gd T cells. Here we investigated the role of Axl in the migration of intraepithelial gd T cells. Methods Primary intraepithelial lymphocytes (IELs) and gdT cells were isolated from 6 to 8 weeks old WT and Axl-deficient mice. Gene expression of IL-7Ra, CCR5, CCR9 and integrin aEb7 was examined by realtime-PCR. IEL phenotype was analyzed by flow cytometry. For adoptive transfer, primary IELs isolated from donors were injected into orbital vein of recipient mice after 6 weeks. Results The gd T cell population and absolute cell number was increased in IELs of Axl-deficient mice compared to them of wild type mice but not in other tissues. In addition, up-regulation of IL-7Ra, CCR5, CCR9 and integrin aEbexpression was observed in both IELs and gd T cells purified from IELs of Axl-deficient mice. The adoptive transfer of IELs of Axl-deficientmice to RAG-deficientmice induced the increased migration of gdT cells. Conclusion Our findings suggest that Axl is required for the migration of intestinal gd T cells by the transcriptional regulation of IL-7Ra, CCR5, CCR9 and integrin aEb7.