Synovial cell production of IL-26 induces bone mineralization in spondyloarthritis.

Spondyloarthritis (SpA) is characterized by inflammation and new bone formation and can be treated by inhibition of the proinflammatory cytokines TNF-α and IL-17A. IL-26 is considered a proinflammatory cytokine, predominantly related to Th17 cells. In the present study, we investigate IL-26 expression in SpA patients, and examine the in vitro production of IL-26 by synovial cells and the effects of IL-26 on human osteoblasts. IL-26 was measured by ELISA in plasma and synovial fluid (SF) of 15 SpA patients and in plasma samples from 12 healthy controls. Facet joints from axial SpA patients were stained for IL-26 and analyzed by fluorescence microscopy. Synovial fluid mononuclear cells, C-C motif chemokine receptor 6 memory Th17 cells, and fibroblast-like synoviocytes (FLSs) were isolated, and supernatants were analyzed for IL-26 content by ELISA. FLSs were further stained for IL-26 production and the myofibroblast marker α-smooth-muscle-actin (αSMA) and analyzed by flow cytometry. Human osteoblasts were cultured in the presence of IL-26, and the degree of mineralization was quantified. We found that IL-26 levels in SF were increased compared with plasma (P < 0.0001). Moreover, IL-26 expression was found in facet joints of axial SpA patients within the bone marrow. IL-26 secretion was primarily found in αSMA+ myofibroblasts. In contrast, Th17 cells did not produce detectable amounts of IL-26. Human osteoblasts treated with IL-26 showed increased mineralization compared with untreated osteoblasts (P = 0.02). In conclusion, IL-26 seems to be produced by myofibroblasts in the inflamed synovium and could be a possible facilitator of bone mineralization in SpA. KEY MESSAGES: IL-26 levels are higher in synovial fluid compared to plasma in spondyloarthritis. IL-26 was identified in axial facet joints of spondyloarthritis patients. Myofibroblasts from the spondyloarthritis synovium produce large amounts of IL-26. IL-26 induces bone mineralization in human osteoblasts.

Facilitated Peptide Transport via the Mucosal Epithelium: Impact on Tolerance Induction.

A hallmark of autoimmunity is the breakdown of tolerance and generation of effector responses against self-antigens. Re-establishment of tolerance in autoimmune disorders was always the most desired treatment option; however, despite many efforts, clinical trials have been largely unsuccessful. This also applies to the generation of oral tolerance, which seems to be a default response type of the mucosa-associated lymphoid tissues to harmless antigens. In this study, we report improved efficacy of oral tolerance induction by coupling antigen with the newly identified mucosal carrier peptide 13C. Antigen coupled to 13C is efficiently taken up in the gastrointestinal tract and could be visualized in cells of the lamina propria. Oral, rectal, or nasal treatment effectively induced the proliferation of antigen-specific T cells with some increase in the frequency of regulatory T cells. In a model of delayed-type hypersensitivity, especially intrarectal tolerization treatment resulted in reduced footpad swelling, demonstrating a moderate tolerogenic effect of mucosal treatment with 13C coupled antigen. Coupling of antigens to a transmucosal carrier, therefore, is a promising tool to improve the efficacy of vaccination via mucosal surfaces.

Surface-modified yeast cells: A novel eukaryotic carrier for oral application.

The effective targeting and subsequent binding of particulate carriers to M cells in Peyer's patches of the gut is a prerequisite for the development of oral delivery systems. We have established a novel carrier system based on cell surface expression of the ß1-integrin binding domain of invasins derived from Yersinia enterocolitica and Yersinia pseudotuberculosis on the yeast Saccharomyces cerevisiae. All invasin derivatives were shown to be effectively expressed on the cell surface and recombinant yeast cells showed improved binding to both human HEp-2 cells and M-like cells in vitro. Among the different derivatives tested, the integrin-binding domain of Y. enterocolitica invasin proved to be the most effective and was able to target Peyer's patches in vivo. In conclusion, cell surface-modified yeasts might provide a novel bioadhesive, eukaryotic carrier system for efficient and targeted delivery of either antigens or drugs via the oral route.

Identification of Targeting Peptides for Mucosal Delivery in Sheep and Mice.

In this study we identified and characterized a novel cyclic peptide that facilitates the rapid transportation of conjugated molecules across the epithelial layer of the small intestine. The peptide was initially selected from phage display libraries using a large animal experimental model, which employed consecutive in vitro and in vivo panning. The procedure was designed to enrich for peptides that facilitated transcytosis across the intestinal epithelium into the intestinal afferent lymphatic system. A small set of peptides was repeatedly isolated using this selection method; however, the cyclic nonamer CTANSSAQC, 13C, dominated. The activity of the putative targeting peptide 13C was then verified using a mouse model. These experiments showed that the 13C peptide as well as macromolecules conjugated to it were rapidly transported across the intestinal mucosa into distinct subsets of epithelial cells and CD11c+ cells located in the lamina propria and Peyer's Patches. Significant amounts of intact protein could be delivered into the systemic circulation after rectal and nasal application. Thus, peptide 13C is regarded as an attractive carrier candidate for mucosal delivery of large molecules. The preferential targeting to distinct intestinal cells may be utilized to deliver active biological drugs for the effective control of diseases of the gut.

Anti-Inflammatory Effects of IL-27 in Zymosan-Induced Peritonitis: Inhibition of Neutrophil Recruitment Partially Explained by Impaired Mobilization from Bone Marrow and Reduced Chemokine Levels.

Rapid activation of the innate immune system is critical for an efficient host response to invading pathogens. However, the inflammatory reaction has to be strictly controlled to minimize harmful immunopathology. A number of mediators including the cytokine interleukin-27 (IL-27) appear to be responsible for limitation and resolution of inflammation. Despite increasing knowledge of its suppressive effects on T cells, the influence on neutrophils and macrophages is poorly understood. To determine the role of IL-27 in innate immune responses we analysed the effect of IL-27 in a T cell independent model of zymosan-induced peritonitis. Early administration of recombinant IL-27 strongly reduced the number of neutrophils recruited to the peritoneal cavity after zymosan application as well as the neutrophil frequency in the blood. Simultaneously, IL-27 reduced the release of neutrophils from the bone marrow upon inflammation. Although cytokine levels were not affected by IL-27 treatment, the levels of the chemokines KC, MCP-1 and MIP-1α in the peritoneal fluid were strongly decreased. These findings demonstrate that IL-27 is able to control mobilisation and recruitment of neutrophils into the peritoneal cavity and identify a novel mechanism to limit inflammation caused by innate immune cells.

Timed action of IL-27 protects from immunopathology while preserving defense in influenza.

Infection with influenza virus can result in massive pulmonary infiltration and potentially fatal immunopathology. Understanding the endogenous mechanisms that control immunopathology could provide a key to novel adjunct therapies for this disease. Here we show that the cytokine IL-27 plays a crucial role in protection from exaggerated inflammation during influenza virus infection. Using Il-27ra-/- mice, IL-27 was found to limit immunopathology, neutrophil accumulation, and dampened TH1 or TH17 responses via IL-10-dependent and -independent pathways. Accordingly, the absence of IL-27 signals resulted in a more severe disease course and in diminished survival without impacting viral loads. Consistent with the delayed expression of endogenous Il-27p28 during influenza, systemic treatment with recombinant IL-27 starting at the peak of virus load resulted in a major amelioration of lung pathology, strongly reduced leukocyte infiltration and improved survival without affecting viral clearance. In contrast, early application of IL-27 impaired virus clearance and worsened disease. These findings demonstrate the importance of IL-27 for the physiological control of immunopathology and the potential value of well-timed IL-27 application to treat life-threatening inflammation during lung infection.