Th17 cells play a critical role in the pathogenesis of rheumatoid arthritis (RA), but the mechanisms by which these cells regulate the development of RA are not fully understood. We have recently ...shown that α2β1 integrin, the receptor of type I collagen, is the major collagen-binding integrin expressed by human Th17 cells. In this study, we examined the role of α2β1 integrin in Th17-mediated destructive arthritis in the murine model of collagen-induced arthritis (CIA). We found that α2β1 integrin is expressed on synovial Th17 cells from CIA mice and its neutralization with a specific mAb significantly reduced inflammation and cartilage degradation, and protected the mice from bone erosion. Blockade of α2β1 integrin led to a decrease in the number of Th17 cells in the joints and to a reduction of IL-17 levels in CIA mice. This was associated with an inhibition of receptor activator of NF-κB ligand levels and osteoclast numbers, and reduction of bone loss. We further show that α2β1 integrin is expressed on synovial Th17 cells from RA patients, and that its ligation with collagen costimulated the production of IL-17 by polarized human Th17 cells by enhancing the expression of retinoic acid receptor-related orphan receptor C through ERK and PI3K/AKT. Our findings provide the first evidence, to our knowledge, that α2β1 integrin is an important pathway in Th17 cell activation in the pathogenesis of CIA, suggesting that its blockade can be beneficial for the treatment of RA and other Th17-associated autoimmune diseases.
Background: The use of fiberoptic bronchial biopsies has improved our understanding of the immunopathology of asthma. However, this approach offers a limited ability to perform mechanistic studies ...observing cell-cell and cell-matrix interactions, which are a key issue in the study of airway remodeling. Tissue engineering is a technique that combines the use of biology and engineering expertise to generate a limitless amount of tissue from small samples. This technology allows for the study of cell interactions under conditions as close as possible to the natural environment. Objective: The aim of this study was to evaluate the feasibility of an engineered human bronchial mucosa as a model to study cellular interactions in asthma. Methods: Human bronchial fibroblasts from normal and asthmatic donors were incorporated into collagen gel. Bronchial epithelial cells were seeded over this gel and then cultured in an air-liquid interface in the presence or the absence of T lymphocytes. Biopsy specimens from these engineered mucosa were taken for structural and ultrastructural analysis, and T lymphocytes were harvested and used to localize IL-5. Results: Histologic analysis showed that engineered mucosa with normal bronchial cells presented a pseudostratified ciliated epithelium with the presence of mucus secretory cells. The electron microscopy analysis confirmed these histologic results. These features were comparable with those observed in normal bronchial tissues. However, in engineered mucosa from asthmatic subjects, the tissue structure was disorganized, particularly the epithelial cell arrangement. The percentage of IL-5+ lymphocytes was significantly (P = .03) higher in engineered bronchial mucosa from asthmatic subjects (87% ± 2%) compared with mucosa from normal volunteers (2% ± 0.3%). Conclusion: Using tissue engineering, we produced an in vitro model of bronchial mucosa from normal and asthmatic subjects. These models could be a valuable tool to better understand key mechanisms involved in inflammation and airway repair. (J Allergy Clin Immunol 2001;107:36-40.)
Background Up to 30% of asthmatic subjects are smokers, and smoking might be an important contributor to asthma pathology. Inducible nitric oxide synthase (iNOS), ornithine decarboxylase (ODC), and ...arginase I are involved in the arginine pathway. We have shown that arginase I and iNOS are upregulated in asthma. Smoking asthmatic subjects are reported to have low exhaled nitric oxide levels. The effect of cigarette smoking on the expression of arginase I in asthma is unknown. Objectives The aims of this study were to investigate the expression of arginase I, ODC, and iNOS in asthmatic airways of smokers and nonsmokers and in vitro after nicotine stimulation. Methods Endobronchial biopsies were performed on 24 steroid-naive subjects with mild asthma: 12 smokers and 12 nonsmokers. Arginase I, ODC, and iNOS levels were assessed by means of immunohistochemistry and in situ hybridization (arginase I). In vitro stimulation of airway cells with nicotine was performed, followed by real-time PCR. Results Arginase I, ODC, and iNOS were expressed in the epithelium and smooth muscle bundles of both subgroups of asthmatic subjects. There was an increase of arginase I and ODC immunoreactivities in smoking compared with nonsmoking asthmatic subjects. There was no significant difference in immunoreactivity for iNOS between groups. Nicotine induced a 2-fold increase in arginase I and ODC expression in airway epithelial cells and fibroblasts. Conclusion This study demonstrates that the expression of arginase I and ODC is increased in airways of smoking compared with nonsmoking asthmatic subjects and in vitro by nicotine. Clinical implications Increased expression of arginase I might lead to low exhaled nitric oxide and chronic obstructive pulmonary disease–like airway remodeling in smoking asthmatic subjects.
Following tissue injury after trauma, the activation of innate immune pathways results in systemic inflammation, organ failure and an increased risk of infections. The objective of this study was to ...characterize the kinetics of the S100A8/S100A9 complex, a new-recognized alarmin, as well as its soluble receptor sRAGE, over time after trauma as potential early biomarkers of the risk of organ damage.
We collected comprehensive data from consenting patients admitted to an ICU following severe trauma. The blood samples were taken at Day 0 (admission), Day1, 3 and 5 S100A8/A9 and sRAGE were measured by ELISA. Biomarkers levels were reported as median (IQR).
Thirty-eight patients sustaining in majority a blunt trauma (89%) with a median ISS of 39 were included. In this cohort, the S100A8/A9 complex increased significantly over time (p = 0.001), but its levels increment over time (D0 to D5) was significantly smaller in patients developing infection (7.6 vs 40.1 mcg/mL, p = 0.011). The circulating level of sRAGE circulating levels decreased over time (p < 0.0001) and was higher in patients who remained in shock on day 3 (550 vs 918 pg/mL; p = 0.02) or 5 (498 vs 644 pg/mL; p = 0.045). Admission sRAGE levels were significantly higher in non-survivors (1694 vs 745 pg/mL; p = 0.015) and was higher in patients developing renal failure (1143 vs 696 pg/mL, p = 0.011).
Our findings reveal an interesting association between the biomarker S100A8/9 least increase over time and the presence of infectious complication after trauma. We describe that the sRAGE decline over time is in relation with shock and markers of ischemic injury. We also confirm the association of sRAGE levels measured at admission with mortality and the development of renal failure.
This work illustrates the importance of following the circulating level of biomarker overtime. The utilization of S1008/9 as a tool to stratify infection risk and trigger early interventions need to be validated prospectively.
Th17 cells are critical effectors in inflammation and tissue damage such as bone erosion, but the mechanisms regulating their activation in this process are not fully understood. In this study, we ...considered the cooperation between cytokine receptors and integrin pathways in Th17-osteoclast function. We found that human Th17 cells coexpress IL-7R and the collagen-binding integrin α2β1 (CD49b), and IL-7 increases their adhesion to collagen via α2β1 integrin. In addition, coengagement of the two receptors in human Th17 cells cooperatively enhanced their IL-17 production and their osteoclastogenic function. The functional cooperation between IL-7R and α2β1 integrin involves activation of the JAK/PI3K/AKT (protein kinase B) and MAPK/ERK pathways. We also showed that IL-7-induced bone loss in vivo is associated with Th17 cell expansion. Moreover, blockade of α2β1 integrin with a neutralizing mAb inhibited IL-7-induced bone loss and osteoclast numbers by reducing Th17 cell numbers in the bone marrow and reducing the production of IL-17 and the receptor activator of NF-κB ligand. Thus, the cooperation between IL-7R and α2β1 integrin can represent an important pathogenic pathway in Th17-osteoclast function associated with inflammatory diseases.
Rationale: To initiate eosinophil migration in vitro, 5‐oxo‐6,8,11,14‐eicosatetraenoic acid (5‐oxo‐ETE), a potent eosinophil chemotactic factor, activates proteolysis, notably by promoting matrix ...metalloproteinase (MMP)‐9 secretion.
Hypothesis: We postulated that protein kinase C (PKC) and mitogen‐activated protein kinase/extracellular signal‐regulated kinase (MAPK/ERK) are involved in 5‐oxo‐ETE‐induced eosinophil migration through extracellular matrix by increasing MMP‐9 secretion.
Methods: Purified peripheral blood eosinophils were pre‐incubated with or without different selective PKC inhibitors (isoforms α β: Ro‐31‐8425, isoform δ: Rottelin or PKC ζ blocking peptide), ERK inhibitor (PD98054) or p38 MAPK inhibitor (SB203580) for 30 min at 37°C, followed by addition of 5‐oxo‐ETE. Migration assays using Matrigel, a reconstituted basement membrane, was assessed, and rapid MMP‐9 release (within an hour) was evaluated by zymography.
Results and Conclusion: All of these inhibitors decreased by 30 to 90% 5‐oxo‐ETE‐induced eosinophil migration through Matrigel. However, only PKC δ and ERK signalling pathway inhibitors reduced rapid release of MMP‐9, suggesting that the other kinases studied could act on MMP‐9 synthesis, generation of other proteases, adherence or cell motility. More experiments are needed to clarify the mechanisms that regulate eosinophil migration.
Asthma is characterized by leukocyte infiltration, notably eosinophils, in the bronchial mucosa. When stimulated by Th2 cytokines such as interleukin (IL)‐4 and IL‐13, bronchial epithelial cells ...release eotaxins, potent chemotactic factors for eosinophils. Cysteinyl leukotrienes (CysLT), such as LTD4, are also involved in cell recruitment by acting through their receptor (CysLT1R). Interestingly, CysLT and IL‐13 act synergistically to increase eotaxin production from fibroblasts. We investigated the effect of IL‐4, IL‐13 and LTD4 on CysLT1R expression and eotaxin production from epithelial cells. A549 cells were incubated with or without IL‐4 (10 ng/ml), IL‐13 (10 ng/ml) and LTD4 (10−7M). Expression of CysLT1R was evaluated by RT‐PCR and flow cytometry analyses. Production of eotaxin‐1, ‐2 and ‐3 was assessed on cell‐free supernatants by ELISA. At baseline, A549 cells express CysLT1R mRNA and protein and release eotaxin‐2. IL‐13, but not IL‐4 or LTD4, increases CysLT1R expression. LTD4 primes eotaxin‐1 and ‐3 release induced by IL‐4 and IL‐13 stimulation. Release of eotaxin‐2 was augmented by IL‐4 and IL‐13. These results suggest that combination of IL‐4, IL‐13 and LTD4 increase eotaxin‐1 and ‐3 productions via up‐regulation of CysLT1R expression. Eotaxin release from epithelial cells could, at least partially, explain eosinophil recruitment in asthmatic bronchial mucosa.
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