Targeting Immune Cell Wiring in Ulcerative Colitis.

The cytokine TNF is thought to play a major role in the immunopathogenesis of ulcerative colitis, and anti-TNF antibodies are considered as cornerstones of clinical therapy. Two clinical trials published in The New England Journal of Medicine now challenge this paradigm and suggest new avenues for research.

TLR7/8 regulates type I and type III interferon signalling in rhinovirus 1b-induced allergic asthma.

INTRODUCTION: Interferon (IFN) responses have been reported to be defective in rhinovirus (RV)-induced asthma. The heterodimeric receptor of type I IFN (IFN-α/ß) is composed of IFN-αR1 and IFN-αR2. Ligand binding to the IFN-α/ß receptor complex activates signal transducer and activator of transcription (STAT) proteins STAT1 and STAT2 intracellularly. Although type III IFN (IFN-λ) binds to a different receptor containing IFN-λR1 and interleukin-10R2, its triggering leads to activation of the same downstream transcription factors. Here, we analysed the effects of RV on IFN type I and III receptors, and asked about possible Toll-like receptor 7/8 (TLR7/8) agonist R848-mediated IFN-αR1 and IFN-λR1 regulation. METHODS: We measured IFN-α, IFN-ß and IFN-λ and their receptor levels in peripheral blood mononuclear cell (PBMC) supernatants and cell pellets stimulated with RV1b and R848 in two cohorts of children with and without asthma recruited at pre-school age (PreDicta) and at primary school age (AGENDAS) as well as in cell supernatants from total lung cells isolated from mice. RESULTS: We observed that R848 induced IFN-λR mRNA expression in PBMCs of healthy and asthmatic children, but suppressed IFN-αR mRNA levels. In murine lung cells, RV1b alone and together with R848 suppressed IFN-αR protein in T-cells compared with controls and in total lung IFN-λR mRNA compared with RV1b infection alone. CONCLUSIONS: In PBMCs from pre-school age children, IFN-αR mRNA was reduced and IFN-λR1 mRNA was induced upon treatment with the TLR7/8 agonist R848, thus suggesting new avenues for induction of antiviral immune responses in paediatric asthma.

Activation of Epithelial Signal Transducer and Activator of Transcription 1 by Interleukin 28 Controls Mucosal Healing in Mice With Colitis and Is Increased in Mucosa of Patients With Inflammatory Bowel Disease.

BACKGROUND & AIMS: We investigated the roles of interleukin 28A (also called IL28A or interferon λ2) in intestinal epithelial cell (IEC) activation, studying its effects in mouse models of inflammatory bowel diseases (IBD) and intestinal mucosal healing. METHODS: Colitis was induced in C57BL/6JCrl mice (controls), mice with IEC-specific disruption of Stat1 (Stat1IEC-KO), mice with disruption of the interferon λ receptor 1 gene (Il28ra-/-), and mice with disruption of the interferon regulatory factor 3 gene (Irf3-/-), with or without disruption of Irf7 (Irf7-/-). We used high-resolution mini-endoscopy and in vivo imaging methods to assess colitis progression. We used 3-dimensional small intestine and colon organoids, along with RNA-Seq and gene ontology methods, to characterize the effects of IL28 on primary IECs. We studied the effects of IL28 on the human intestinal cancer cell line Caco-2 in a wound-healing assay, and in mice colon wounds. Colonic biopsies and resected tissue from patients with IBD (n = 62) and patients without colon inflammation (controls, n = 23) were analyzed by quantitative polymerase chain rection to measure expression of IL28A, IL28RA, and other related cytokines; biopsy samples were also analyzed by immunofluorescence to identify sources of IL28 production. IECs were isolated from patient tissues and incubated with IL28; signal transducer and activator of transcription 1 (STAT1) phosphorylation was measured by immunoblots and confocal imaging. RESULTS: Lamina propria cells in colon tissues of patients with IBD, and mice with colitis, had increased expression of IL28 compared with controls; levels of IL28R were increased in the colonic epithelium of patients with IBD and mice with colitis. Administration of IL28 induced phosphorylation of STAT1 in primary human and mouse IECs, increasing with dose. Il28ra-/-, Irf3-/-, Irf3-/-Irf7-/-, as well as Stat1IEC-KO mice, developed more severe colitis after administration of dextran sulfate sodium than control mice, with reduced epithelial restitution. Il28ra-/- and Stat1IEC-KO mice also developed more severe colitis in response to oxazolone than control mice. We found IL28 to induce phosphorylation (activation) of STAT1 in epithelial cells, leading to their proliferation in organoid culture. Administration of IL28 to mice with induced colonic wounds promoted mucosal healing. CONCLUSIONS: IL28 controls proliferation of IECs in mice with colitis and accelerates mucosal healing by activating STAT1. IL28 might be developed as a therapeutic agent for patients with IBD.

STAT2 Controls Colorectal Tumorigenesis and Resistance to Anti-Cancer Drugs.

Colorectal cancer (CRC) is a significant socioeconomic burden in modern society and is accountable for millions of premature deaths each year. The role of signal transducer and activator of transcription 2 (STAT2)-dependent signaling in this context is not yet fully understood, and no therapies targeting this pathway are currently being pursued. We investigated the role of STAT2 in CRC using experimental mouse models coupled with RNA-sequencing (RNA-Seq) data and functional assays with anti-cancer agents in three-dimensional tumoroids. Stat2-/- mice showed greater resistance to the development of CRC in both inflammation-driven and inflammation-independent experimental CRC models. In ex vivo studies, tumoroids derived from Stat2-/- mice with the multiple intestinal neoplasia (Min) mutant allele of the adenomatous polyposis coli (Apc) locus exhibited delayed growth, were overall smaller and more differentiated as compared with tumoroids from ApcMin/+ wildtype (WT) mice. Notably, tumoroids from ApcMin/+ Stat2-/- mice were more susceptible to anti-cancer agents inducing cell death by different mechanisms. Our findings clearly indicated that STAT2 promotes CRC and suggested that interventions targeting STAT2-dependent signals might become an attractive therapeutic option for patients with CRC.

T cells are required for the production of blister-inducing autoantibodies in experimental epidermolysis bullosa acquisita.

Epidermolysis bullosa acquisita is a prototypical organ-specific autoimmune disease caused by autoantibodies against type VII collagen of the dermal-epidermal junction. Although mechanisms of autoantibody-induced blister formation were extensively characterized, the initiation of autoantibody production in autoimmune blistering diseases is still poorly defined. In the current study, we addressed the role of T cells for the production of blister-inducing autoantibodies in mice immunized with type VII collagen. To detect autoreactive type VII collagen-specific T cells, lymph node cells from immunized SJL mice were stimulated in vitro with recombinant Ag, and their proliferation was measured by radioactive thymidine incorporation and flow cytometry analysis of CFSE-labeled cells. Interestingly, using synthetic peptides of the immunogen, partly different T and B cell epitopes in mice immunized with type VII collagen were demonstrated. In contrast to wild-type mice, immunization with type VII collagen of SJL athymic nude mice lacking T cells did not induce an autoimmune response and blistering phenotype. Importantly, SJL nude mice repleted with T cells from immunized wild-type mice showed a robust and durable autoantibody production resulting in subepidermal blistering disease in the recipients. Our present results demonstrate that T cells are required for the initiation of autoimmunity against type VII collagen in experimental epidermolysis bullosa acquisita and provide a basis for developing T cell-directed immunomodulatory strategies for this and related autoimmune diseases.

Glucose-Restricted Diet Regulates the Tumor Immune Microenvironment and Prevents Tumor Growth in Lung Adenocarcinoma.

Background: Lung cancer is the second common cancer type in western countries and has a high mortality. During the development and progression of the tumor, the nutrients in its environment play a central role. The tumor cells depend crucially on glucose metabolism and uptake. Tumor cell metabolism is dominated by the Warburg effect, where tumor cells produce large amounts of lactate from pyruvate under aerobic conditions. We thus reasoned that, reducing carbohydrates in the diet might support anti-tumoral effects of current immunotherapy and additionally target tumor immune escape. Objectives: The link between reducing carbohydrates to improve current immunotherapy is not clear. We thus aimed at analyzing the effects of different glucose levels on the tumor development, progression and the anti-tumoral immune response. Methods: We correlated the clinical parameters of our LUAD cohort with different metabolic markers. Additionally, we performed cell culture experiments with A549 tumor cell line under different glucose levels. Lastly, we investigated the effect of low and high carbohydrate diet in an experimental murine model of lung cancer on the tumor progression and different immune subsets. Results: Here we found a positive correlation between the body mass index (BMI), blood glucose levels, reduced overall survival (OS) and the expression of Insulin-like growth factor-1 receptor (IGF1R) in the lung tumoral region of patients with lung adenocarcinoma (LUAD). Furthermore, increasing extracellular glucose induced IGF1R expression in A549 LUAD cells. Functional studies in a murine model of LUAD demonstrated that, glucose restricted diet resulted in decreased tumor load in vivo. This finding was associated with increased presence of lung infiltrating cytotoxic CD8+ T effector memory (TEM), tissue resident memory T (TRM) and natural killer cells as well as reduced IGFR mRNA expression, suggesting that glucose restriction regulates lung immunity in the tumor microenvironment. Conclusions: These results indicate that, glucose restricted diet improves lung immune responses of the host and suppresses tumor growth in experimental lung adenocarcinoma. As glucose levels in LUAD patients were negatively correlated to postoperative survival rates, glucose-restricted diet emerges as therapeutic avenue for patients with LUAD.

STAT1 coordinates intestinal epithelial cell death during gastrointestinal infection upstream of Caspase-8.

Intestinal homeostasis and the maintenance of the intestinal epithelial barrier are essential components of host defense during gastrointestinal Salmonella Typhimurium infection. Both require a strict regulation of cell death. However, the molecular pathways regulating epithelial cell death have not been completely understood. Here, we elucidated the contribution of central mechanisms of regulated cell death and upstream regulatory components during gastrointestinal infection. Mice lacking Caspase-8 in the intestinal epithelium are highly sensitive towards bacterial induced enteritis and intestinal inflammation, resulting in an enhanced lethality of these mice. This phenotype was associated with an increased STAT1 activation during Salmonella infection. Cell death, barrier breakdown and systemic infection were abrogated by an additional deletion of STAT1 in Casp8ΔIEC mice. In the absence of epithelial STAT1, loss of epithelial cells was abolished which was accompanied by a reduced Caspase-8 activation. Mechanistically, we demonstrate that epithelial STAT1 acts upstream of Caspase-8-dependent as well as -independent cell death and thus might play a major role at the crossroad of several central cell death pathways in the intestinal epithelium. In summary, we uncovered that transcriptional control of STAT1 is an essential host response mechanism that is required for the maintenance of intestinal barrier function and host survival.

IL-9 Producing Tumor-Infiltrating Lymphocytes and Treg Subsets Drive Immune Escape of Tumor Cells in Non-Small Cell Lung Cancer.

Although lung cancer is the leading cause of cancer deaths worldwide, the mechanisms how lung cancer cells evade the immune system remain incompletely understood. Here, we discovered IL-9-dependent signaling mechanisms that drive immune evasion in non-small cell lung cancer (NSCLC). We found increased IL-9 and IL-21 production by T cells in the tumoral region of the lung of patients with NSCLC, suggesting the presence of Th9 cells in the lung tumor microenvironment. Moreover, we noted IL-9 producing Tregs in NSCLC. IL-9 target cells in NSCLC consisted of IL-9R+ tumor cells and tumor-infiltrating lymphocytes. In two murine experimental models of NSCLC, and in vitro, IL-9 prevented cell death and controlled growth of lung adenocarcinoma cells. Targeted deletion of IL-9 resulted in successful lung tumor rejection in vivo associated with an induction of IL-21 and reduction of Treg cells. Finally, anti-IL-9 antibody immunotherapy resulted in suppression of tumor development even in established experimental NSCLC and was associated with reduced IL-10 production in the lung. In conclusion, our findings indicate that IL-9 drives immune escape of lung tumor cells via effects on tumor cell survival and tumor infiltrating T cells. Thus, strategies blocking IL-9 emerge as a new approach for clinical therapy of lung cancer.

An IFN-STAT Axis Augments Tissue Damage and Inflammation in a Mouse Model of Crohn's Disease.

Blocking interferon-function by therapeutic intervention of the JAK-STAT-axis is a novel promising treatment option for inflammatory bowel disease (IBD). Although JAK inhibitors have proven efficacy in patients with active ulcerative colitis (UC), they failed to induce clinical remission in patients with Crohn's disease (CD). This finding strongly implicates a differential contribution of JAK signaling in both entities. Here, we dissected the contribution of different STAT members downstream of JAK to inflammation and barrier dysfunction in a mouse model of Crohn's disease like ileitis and colitis (Casp8 ΔIEC mice). Deletion of STAT1 in Casp8 ΔIEC mice was associated with reduced cell death and a partial rescue of Paneth cell function in the small intestine. Likewise, organoids derived from the small intestine of these mice were less sensitive to cell death triggered by IBD-key cytokines such as TNFα or IFNs. Further functional in vitro and in vivo analyses revealed the impairment of MLKL-mediated necrosis as a result of deficient STAT1 function, which was in turn associated with improved cell survival. However, a decrease in inflammatory cell death was still associated with mild inflammation in the small intestine. The impact of STAT1 signaling on gastrointestinal inflammation dependent on the localization of inflammation, as STAT1 is essential for intestinal epithelial cell death regulation in the small intestine, whereas it is not the key factor for intestinal epithelial cell death in the context of colitis. Of note, additional deletion of STAT2 was not sufficient to restore Paneth cell function but strongly ameliorated ileitis. In summary, we provide here compelling molecular evidence that STAT1 and STAT2, both contribute to intestinal homeostasis, but have non-redundant functions. Our results further demonstrate that STATs individually affect the distinct pathophysiology of inflammation in the ileum and colon, respectively, which might explain the diverse outcome of JAK inhibitors on inflammatory bowel diseases.

Regulation and Function of Interferon-Lambda (IFNλ) and Its Receptor in Asthma.

Asthma is a chronic respiratory disease affecting people of all ages, especially children, worldwide. Origins of asthma are suggested to be placed in early life with heterogeneous clinical presentation, severity and pathophysiology. Exacerbations of asthma disease can be triggered by many factors, including viral respiratory tract infections. Rhinovirus (RV) induced respiratory infections are the predominant cause of the common cold and also play a crucial role in asthma development and exacerbations. Rhinovirus mainly replicates in epithelial cells lining the upper and lower respiratory tract. Type III interferons, also known as interferon-lambda (IFNλ), are potent immune mediators of resolution of infectious diseases but they are known to be involved in autoimmune diseases as well. The protective role of type III IFNs in antiviral, antibacterial, antifungal and antiprotozoal functions is of major importance for our innate immune system. The IFNλ receptor (IFNλR) is expressed in selected types of cells like epithelial cells, thus orchestrating a specific immune response at the site of viruses and bacteria entry into the body. In asthma, IFNλ restricts the development of TH2 cells, which are induced in the airways of asthmatic patients. Several studies described type III IFNs as the predominant type of interferon increased after infection caused by respiratory viruses. It efficiently reduces viral replication, viral spread into the lungs and viral transmission from infected to naive individuals. Several reports showed that bronchial epithelial cells from asthmatic subjects have a deficient response of type III interferon after RV infection ex vivo. Toll like Receptors (TLRs) recognize pathogen-associated molecular patterns (PAMPs) expressed on infectious agents, and induce the development of antiviral and antibacterial immunity. We recently discovered that activation of TLR7/8 resulted in enhanced IFNλ receptor mRNA expression in PBMCs of healthy and asthmatic children, opening new therapeutic frontiers for rhinovirus-induced asthma. This article reviews the recent advances of the literature on the regulated expression of type III Interferons and their receptor in association with rhinovirus infection in asthmatic subjects.

Pathogenicity of IgG subclass autoantibodies to type VII collagen: induction of dermal-epidermal separation.

In different autoimmune diseases, tissue damage is mediated by the Fc portion of autoantibodies. These include autoimmunity to type VII collagen, a major hemidesmosomal skin constituent, where autoantibodies activate both complement and leukocytes, leading to separation within the dermal-epidermal junction. Fc-dependent effector functions differ among IgG subclasses. To elucidate the still controversial role of IgG subclasses in the pathogenesis of autoimmunity to type VII collagen, we generated a unique set of V gene-matched recombinant chimeric anti-type VII collagen autoantibodies of the four human IgG subclasses. Binding specificities and avidities of all four autoantibodies were comparable. Using ex vivo models, our results demonstrate that a monoclonal autoantibody is sufficient to activate complement and to induce dermal-epidermal separation. However, only IgG1 and IgG3, but not IgG2 and IgG4 against type VII collagen, were pathogenic in our ex vivo model systems. To our knowledge, this is the first time that a full-length recombinant disease-related human autoantibody has been investigated. Our results demonstrate the usefulness of recombinant antibody technology to dissect the contribution of F(ab')(2) and Fc portions of autoantibodies to their biological effects. These findings may eventually contribute to novel diagnostic tools for monitoring disease and to the development of more specific therapies in autoantibody-mediated diseases, i.e. the generation of subclass-specific adsorbers, used for extracorporal immunoapheresis, or the shifting of the autoimmune response to production of non-pathogenic autoantibodies.

Induction of dermal-epidermal separation in mice by passive transfer of antibodies specific to type VII collagen.

Epidermolysis bullosa acquisita (EBA) is a subepidermal blistering disorder associated with tissue-bound and circulating autoantibodies specific to type VII collagen, a major constituent of the dermal-epidermal junction. Previous attempts to transfer the disease by injection of patient autoantibodies into mice have been unsuccessful. To study the pathogenic relevance of antibodies specific to type VII collagen in vivo, we generated and characterized rabbit antibodies specific to a murine form of this antigen and passively transferred them into adult nude, BALB/c, and C57BL/6 mice. Immune rabbit IgG bound to the lamina densa of murine skin and immunoblotted type VII collagen. Mice injected with purified IgG specific to type VII collagen, in contrast to control mice, developed subepidermal skin blisters, reproducing the human disease at the clinical, histological, electron microscopical, and immunopathological levels. Titers of rabbit IgG in the serum of mice correlated with the extent of the disease. F(ab')(2) fragments of rabbit IgG specific to type VII collagen were not pathogenic. When injected into C5-deficient mice, antibodies specific to type VII collagen failed to induce the disease, whereas C5-sufficient mice were susceptible to blister induction. This animal model for EBA should facilitate further dissection of the pathogenesis of this disease and development of new therapeutic strategies.

STAT1 deficiency supports PD-1/PD-L1 signaling resulting in dysfunctional TNFα mediated immune responses in a model of NSCLC.

In this study we described that Signal Transducer and Activator of Transcription 1 (STAT1) is a key point regulator of PD-1 in tumour infiltrating lymphocytes and PD-L1 in Tumour associated macrophages (TAM) in NSCLC. In our murine model of adenocarcinoma targeted deletion of Stat1 was found associated with enhanced tumour growth, impaired differentiation into M1-like macrophages from the bone marrow, the accumulation of tumor associated macrophages overexpressing PD-L1 and impaired T cell responses in the tumor microenvironment by affecting TNFα responses. In our human NSCLC patient cohort we found that loss of isoforms STAT1 α and STAT1ß mRNA in the tumoural region of the lung correlates with increased tumor size in NSCLC patients. Therefore, STAT1 isoform regulation could be considered for future therapeutical strategies associated to current immune-checkpoint blockade therapy in NSCLC.

The Microbiome in Visceral Medicine: Inflammatory Bowel Disease, Obesity and Beyond.

It has become increasingly evident over the past two decades that the microbiota plays a nurturing role in the development of the immune system. This appears to be important since the amplitude of immune responses has a crucial regulatory function in homeostasis and the prevention of unwanted inflammation. Hence, a malfunctioning gut flora has been shown to play a key role in visceral medicine. Strong evidence demonstrates for example that intestinal inflammation can develop as a result of a dysregulated microbiota, deficient antimicrobial responses, and aberrant bacterial translocation into the bowel wall. In healthy individuals, the bacterial translocation is blocked by a single layer of highly specialized intestinal epithelial cells which forms a strong barrier that lines the gut wall. This structure is responsible for an efficient absorption of nutrients while keeping the luminal flora at bay. In susceptible individuals, for yet incompletely understood reasons, either defective epithelial barrier function or dysregulated microbial composition or microbial pathogens drive intestinal inflammation. Many therapeutic strategies focusing on the modulation of the microbiota have been proposed recently but future research including prospective human studies and gnotobiotic mouse models are still needed to evaluate the contribution and potential therapeutic value of individual bacteria to human health.

Development and Validation of a Confocal Laser Endomicroscopy-Based Score for In Vivo Assessment of Mucosal Healing in Ulcerative Colitis Patients.

Background: Endoscopic monitoring is fundamental for evaluating the therapeutic response in IBD, but a validated endomicroscopic mucosal healing (MH) score is not available to date. However, confocal laser endomicroscopy (CLE) might define MH more precisely than conventional endoscopy. The major aim was to establish and validate an MH score for ulcerative colitis (UC), based on CLE. Methods: In an initial pilot study (n = 10), various CLE changes were analyzed for identification of reproducible criteria for establishing a CLE score. Four reproducible CLE criteria were implemented in a following validation study. Subsequently, active UC patients (n = 23, Mayo score ≥6) were prospectively included and underwent colonoscopy with CLE before and after 3 anti-TNF applications. Patients were clinically followed over a period of 3 years. The endomicroscopic MH score (eMHs; range, 0-4) was compared with histopathology and endoscopy scores from the same colonic location. Results: The eMHs showed high sensitivity, specificity, and accuracy values (100% with 95% confidence interval [CI] of 15.81%-100%; 93.75% with 95% CI of 69.77%-99.84%, and 94.44%, respectively). The eMHs showed a good correlation with the histological Gupta score (rs = 0.82, P < 0.0001) and the endoscopic Mayo subscore (rs = 0.81%, P < 0.0001). Sixty percent of therapy responders presented an eMHs <1, which translated into long-lasting clinical remission and reduced hospitalization, steroid, and surgery need. Conclusions: CLE can accurately assess MH based on the newly developed and statistically validated eMHs in UC, and it is superior in predicting the long-lasting clinical outcome based on both descriptive and functional barrier imaging (NCT01417728).

Chitosan-coated triangular silver nanoparticles as a novel class of biocompatible, highly sensitive plasmonic platforms for intracellular SERS sensing and imaging.

There is a need for new strategies for noninvasive imaging of pathological conditions within the human body. The approach of combining the unique physical properties of noble-metal nanoparticles with their chemical specificity and an easy way of conjugation open up new routes toward building bio-nano-objects for biomedical tracking and imaging. This work reports the design and assessment of a novel class of biocompatible, highly sensitive SERS nanotags based on chitosan-coated silver nanotriangles (Chit-AgNTs) labeled with para-aminothiophenol (p-ATP). The triangular nanoparticles are used as Raman scattering enhancers and have proved to yield a reproducible and strong SERS signal. When tested inside lung cancer cells (A549) this class of SERS nanotags presents low in vitro toxicity, without interfering with cell proliferation. Easily internalized by the cells, as demonstrated by imaging using both reflected bright-light optical microscopy and SERS spectroscopy, the particles are proved to be detectable inside cells under a wide window of excitation wavelengths, ranging from visible to near infrared (NIR). Their high sensitivity and NIR availability make this class of SERS nanotags a promising candidate for noninvasive imaging of cancer cells.

Why human pemphigoid autoantibodies do not trigger disease by the passive transfer into mice?

The recapitulation of disease features in animals by the transfer of patient autoantibodies has been used to demonstrate the autoimmune nature of several diseases. Failure of disease induction by the passive transfer of autoantibodies has been assigned to a limited cross-reactivity of the autoantibodies with the murine tissue. However, the possibility that the passively transferred "inflammatory" patient autoantibodies may not be able to unfold their pathogenic potential due to restricted Fc-dependent effector functions has not yet been systematically explored. In this study we analyze the interaction of patients' autoantibodies with murine complement and granulocytes. Bullous pemphigoid is a blistering disease associated with autoantibodies, which are thought to induce subepidermal blistering by activating complement and granulocytes. The passive transfer of patients autoantibodies failed to induce skin blistering in wild type mice. The cross-reactivity of pemphigoid autoantibodies with murine antigens was analyzed in silico, ex vivo and by the passive transfer of IgG in vivo. Complement-fixing ability of patients' autoantibodies was evaluated by complement-binding test. Granulocyte activation was assessed by reactive oxygen species production assay and the cryosection model. We have found that although pemphigoid autoantibodies bound to murine skin in vitro and in vivo, they showed a lower capacity to fix murine complement and a reduced ability to activate murine granulocytes when compared with human complement and cells, respectively. These results indicate that for disease models using the passive transfer of patient autoantibodies, their interaction with the innate factors of the host should be optimized to match the human situation.

In vivo detection of mucosal healing-involved histiocytes by confocal laser endomicroscopy.

Histiocytes have a pivotal role in wound repair and intestinal epithelial recovery - the most important goal to sustain gut functionality. Yet, an in vivo description of colonic histiocytes by confocal laser endomicroscopy (CLE) is missing. Here, we report the case of a 45-years-old male patient who was referred to our clinic with weight loss and a history of two consecutive Clostridium difficile colitis episodes, the latter cured 3 wk before present admission. Stool microbiology was negative. Conventional colonoscopy showed atrophy and a light mucosal oedema in the distal colon. During on-going endoscopy, we performed a fluorescein-aided CLE which revealed large polygonal (histiocytes-like) cells with copious cytoplasm and large nuclei in the lamina propria of the sigmoid colon as well as regenerative epithelial changes. Histopathological assessment of biopsies from the same areas confirmed the endomicroscopical findings: Periodic acid-Schiff- and CD68-positive foamy histiocytes in the colonic lamina propria and an advanced epithelial recovery. Since stool microbiology was repeatedly negative and polymerase chain reaction-analysis from colonic biopsies could not detect any mRNA for Thropheryma whippleii and common pathogens, we interpreted this particular setting as a mucosal healing process after consecutive Clostridium difficile infections. In conclusion, by describing these colonic histiocytes, we highlight the clinical usefulness of CLE in describing the entity of histiocytes in vivo and in real-time during the process of post-infectious mucosal healing in the colon.

Pemphigus vulgaris is the most common autoimmune bullous disease in Northwestern Romania.

BACKGROUND: Autoimmune bullous diseases are organ-specific diseases characterized by autoreactive T and B cells specific for structural proteins of the skin. The incidence and prevalence of autoimmune blistering diseases vary in different countries and their epidemiology has not yet been addressed in Romania. METHODS: In this study between 2001 and 2007, we prospectively investigated a total of 116 patients with autoimmune blistering diseases from the Northwestern region of Romania. The diagnosis was based on the clinical, histo- and immunohistological as well as serological findings. RESULTS: Pemphigus was the most common disease representing 58.6% of the case (68 cases); 40 cases (34.5%) were diagnosed with bullous pemphigoid (BP) and eight cases (6.9%) with other autoimmune sub-epidermal diseases. The incidence and prevalence of pemphigus diseases were four patients/1,000,000 inhabitants/year and 0.00248%, respectively. BP occurred in 2.5/1,000,000 inhabitants/year and its prevalence was 0.00146%. While the average onset age for pemphigus vulgaris was 53 years, BP patients were first diagnosed at a mean age of 73.6 years. CONCLUSION: The genetic background of the local population may explain why pemphigus occurs more commonly than BP in Northwestern Romania compared with the population of Western Europe. In addition, the shorter life expectancy in Romania (71.3 years) compared with Western Europe (>80 years) may contribute to this phenomenon.