IL-23-mediated mononuclear phagocyte crosstalk protects mice from Citrobacter rodentium-induced colon immunopathology.

Gut homeostasis and mucosal immune defense rely on the differential contributions of dendritic cells (DC) and macrophages. Here we show that colonic CX3CR1(+) mononuclear phagocytes are critical inducers of the innate response to Citrobacter rodentium infection. Specifically, the absence of IL-23 expression in macrophages or CD11b(+) DC results in the impairment of IL-22 production and in acute lethality. Highlighting immunopathology as a death cause, infected animals are rescued by the neutralization of IL-12 or IFNγ. Moreover, mice are also protected when the CD103(+) CD11b(-) DC compartment is rendered deficient for IL-12 production. We show that IL-12 production by colonic CD103(+) CD11b(-) DC is repressed by IL-23. Collectively, in addition to its role in inducing IL-22 production, macrophage-derived or CD103(-) CD11b(+) DC-derived IL-23 is required to negatively control the otherwise deleterious production of IL-12 by CD103(+) CD11b(-) DC. Impairment of this critical mononuclear phagocyte crosstalk results in the generation of IFNγ-producing former TH17 cells and fatal immunopathology

In vivo histologically equivalent evaluation of gastric mucosal topologic morphology in dogs by using confocal endomicroscopy

Background: Confocal endomicroscopy (CEM) is an endoscopic technology permitting in vivo cellular and subcellular imaging. CEM aids real-time clinical assessment and diagnosis of various gastrointestinal diseases in people. CEM allows in vivo characterization of small intestinal mucosal morphology in dogs. Objective: To determine the feasibility of CEM to evaluate gastric mucosal morphology in dogs and to characterize the appearance in healthy dogs. Animals: Fourteen clinically healthy research colony dogs. Methods: Experimental study. Under general anesthesia, dogs underwent standard endoscopic evaluation and CEM of the gastric mucosa. In the initial 6 dogs, fluorescent contrast was provided with the fluorophore acriflavine (0.05% solution), applied topically. Subsequently, 8 dogs were assessed using a combination of fluorescein (10% solution, 15\ua0mg/kg IV), followed by acriflavine administered topically. For each fluorophore, a minimum of 5 sites were assessed. Results: Confocal endomicroscopy provided high quality in vivo histologically equivalent images of the gastric mucosa, but reduced flexibility of the endoscope tip limited imaging of the cranial stomach in some dogs. Intravenous administration of fluorescein allowed assessment of cellular cytoplasmic and microvasculature features. Topical application of acriflavine preferentially stained cellular nucleic acids, allowing additional evaluation of nuclear morphology. Identification of Helicobacter-like organisms was possible in 13 dogs. Conclusion and Clinical Importance: Confocal endomicroscopy provides in vivo images allowing assessment of gastric mucosal morphology during endoscopy, potentially permitting real-time diagnosis of gastrointestinal disease. \ua9 2014 by the American College of Veterinary Internal Medicine

The engagement of selectins and their ligands in colorectal cancer liver metastases

The colonization of the liver by colorectal cancer (CRC) cells is a complicated process which includes many stages, until macrometastases occur. The entrapment of malignant cells within the hepatic sinusoids and their interactions with resident non-parenchymal cells are considered very important for the whole metastatic sequence. In the sinusoids, cell connection and signalling is mediated by multiple cell adhesion molecules, such as the selectins. The three members of the selectin family, E-, P- and L-selectin, in conjunction with sialylated Lewis ligands and CD44 variants, regulate colorectal cell communication and adhesion with platelets, leucocytes, sinusoidal endothelial cells and stellate cells. Their role in CRC liver metastases has been investigated in animal models and human tissue, in vivo and in vitro, in static and shear flow conditions, and their key-function in several molecular pathways has been displayed. Therefore, trials have already commenced aiming to exploit selectins and their ligands in the treatment of benign and malignant diseases. Multiple pharmacological agents have been developed that are being tested for potential therapeutic applications

Co-expression of nuclear and cytoplasmic HMGB1 is inversely associated with infiltration of CD45RO+ T cells and prognosis in patients with stage IIIB colon cancer

<p>Abstract</p> <p>Background</p> <p>The intratumoral infiltration of T cells, especially memory T cells, is associated with a favorable prognosis in early colorectal cancers. However, the mechanism underlying this process remains elusive. This study examined whether high-mobility group box 1 (HMGB1), a damage-associated molecular pattern (DAMP) molecule, is involved in the infiltration of T cells and disease progression in locally advanced colon cancer.</p> <p>Methods</p> <p>Seventy-two cases of pathologically-confirmed specimens were obtained from patients with stage IIIB (T3N1M0) colon cancer who underwent radical resection between January 1999 and May 2002 at the Cancer Center of Sun Yat-Sen University. The density of tumor-infiltrating lymphocytes (TILs) within the tumor tissue and the expression of HMGB1 in the cancer cells were examined via immunohistochemical analysis. The phenotype of CD45RO+ cells was confirmed using a flow cytometric assay. The association between HMGB1 expression, the density of TILs, and the 5-year survival rate were analyzed.</p> <p>Results</p> <p>The density of CD45RO+ T cells within the tumor was independently prognostic, although a higher density of CD3+ T cells was also associated with a favorable prognosis. More importantly, the expression of HMGB1 was observed in both the nucleus and the cytoplasm (co-expression pattern) in a subset of colon cancer tissues, whereas nuclear-only expression of HMGB1 (nuclear expression pattern) existed in most of the cancer tissues and normal mucosa. The co-expression pattern of HMGB1 in colon cancer cells was inversely associated with the infiltration of both CD3+ and CD45RO+ T cells and 5-year survival rates.</p> <p>Conclusions</p> <p>This study revealed that the co-expression of HMGB1 is inversely associated with the infiltration of CD45RO+ T cells and prognosis in patients with stage IIIB colon cancer, indicating that the distribution patterns of HMGB1 might contribute to the progression of colon cancer via modulation of the local immune response.</p

Control of pathogens and microbiota by innate lymphoid cells

International audienceInnate lymphoid cells (ILCs) are the innate counterpart of T cells. Upon infection or injury, ILCs react promptly to direct the developing immune response to the one most adapted to the threat facing the organism. Therefore, ILCs play an important role early in resistance to infection, but also to maintain homeostasis with the symbiotic microbiota following perturbations induced by diet and pathogens. Such roles of ILCs have been best characterized in the intestine and lung, mucosal sites that are exposed to the environment and are therefore colonized with diverse but specific types of microbes. Understanding the dialogue between pathogens, microbiota and ILCs may lead to new strategies to re-inforce immunity for prevention, vaccination and therapy

Metabolic regulation by PPARγ is required for IL-33-mediated activation of ILC2s in lung and adipose tissue

International audienceType 2 innate lymphoid cells (ILC2s) play a critical role early in the response to infection by helminths and in the development of allergic reactions. ILC2s are also involved in the physiologic regulation of adipose tissue and its metabolic response to cold shock. We find that the metabolic sensor peroxisome proliferator-activated receptor gamma (PPARγ) is highly expressed in ILC2s of the lung and adipose tissue and increases responsiveness to IL-33. In turn, activation of ILC2 by IL-33 leads to increased expression of PPARγ, a prerequisite for proliferation and expression of the effector cytokines IL-5 and IL-13. In contrast, pharmacological inhibition of PPARγ leads to decreased expression of CD36 and fatty acid uptake, a necessary source of energy for ILC2s and of potential ligands for PPARγ. As a consequence, treatment of mice with a PPARγ antagonist reduces the severity of an ILC2-dependent acute airway inflammation. Together, our results demonstrate the critical role of the metabolic sensor PPARγ for the functions of ILC2s

Non-redundant properties of IL-1alpha and IL-1beta during acute colon inflammation in mice

Item does not contain fulltextOBJECTIVE: The differential role of the IL-1 agonists, IL-1alpha, which is mainly cell-associated versus IL-1beta, which is mostly secreted, was studied in colon inflammation. DESIGN: Dextran sodium sulfate (DSS) colitis was induced in mice globally deficient in either IL-1alpha or IL-1beta, and in wild-type mice, or in mice with conditional deletion of IL-1alpha in intestinal epithelial cells (IECs). Bone marrow transplantation experiments were performed to assess the role of IL-1alpha or IL-1beta of myeloid versus colon non-hematopoietic cells in inflammation and repair in acute colitis. RESULTS: IL-1alpha released from damaged IECs acts as an alarmin by initiating and propagating colon inflammation, as IL-1alpha deficient mice exhibited mild disease symptoms with improved recovery. IL-1beta is involved in repair of IECs and reconstitution of the epithelial barrier during the resolution of colitis; its deficiency correlates with disease exacerbation. Neutralisation of IL-1alpha in control mice during acute colitis led to alleviation of clinical and histological manifestations, whereas treatment with rIL-1Ra or anti-IL-1beta antibodies was not effective. Repair after colitis correlated with accumulation of CD8 and regulatory T cells in damaged crypts. CONCLUSIONS: The role of IL-1alpha and IL-1beta differs in DSS-induced colitis in that IL-1alpha, mainly of colon epithelial cells is inflammatory, whereas IL-1beta, mainly of myeloid cell origin, promotes healing and repair. Given the dissimilar functions of each IL-1 agonistic molecule, an IL-1 receptor blockade would not be as therapeutically effective as specific neutralising of IL-1alpha, which leaves IL-1beta function intact

In Vivo Confocal Endomicroscopy of Small Intestinal Mucosal Morphology in Dogs

Background: Confocal endomicroscopy (CEM) is an endoscopic technology that permits in vivo cellular and subcellular imaging of the gastrointestinal mucosa. Objective: To determine the feasibility of CEM to evaluate small intestinal mucosal topologic morphology in dogs and to characterize the appearance in healthy dogs. Animals: Fourteen clinically healthy research colony dogs. Methods: Experimental study. Dogs were anesthetized for standard endoscopic evaluation of the small intestine followed by CEM. Two fluorophores were used to provide contrast: fluorescein (10% solution, 15 mg/kg IV) before administration of topical acriflavine (0.05% solution) via an endoscopy spray catheter. A minimum of 5 sites within the small intestine were assessed and at each location, sequential adjustment of imaging depth allowed collection of a three-dimensional volume equivalent to an 'optical biopsy'. CEM-guided pinch biopsies were obtained for histologic examination. Results: CEM provided high-quality in vivo cellular and subcellular images. Intravenous administration of fluorescein provided sufficient contrast to allow assessment of the vasculature, cellular cytoplasmic features and goblet cell numbers, and distribution. Topical application of acriflavine preferentially stained cellular nucleic acids, allowing evaluation of nuclear morphology. Quality of captured images was occasionally affected by motion artifact, but improved with operator experience. Conclusion and Clinical Importance: CEM provides in vivo images that allow for cellular and subcellular assessment of intestinal mucosal morphology during endoscopy. This has implications for aiding in vivo diagnosis of gastrointestinal disease. © 2013 by the American College of Veterinary Internal Medicine