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Item does not contain fulltext, BACKGROUND: Cystic fibrosis (CF) is a common genetic disease caused by mutations of the CF transmembrane conductance regulator (CFTR) gene. Persistent lung inflammation, characterized by increasing polymorphonuclear leukocyte recruitment, is a major cause of the decline in respiratory function in CF patients, and is a leading cause of morbidity and mortality. CFTR is expressed in various cell types, including leukocytes, but its involvement in the regulation of leukocyte recruitment is unknown. METHODS: Ex vivo adhesion and chemotaxis, flow cytometry, immunofluorescence, GTPases activity assays. RESULTS: We found that chemoattractant-induced activation of beta1 and beta2 integrins and of chemotaxis is defective in mononuclear cells isolated from CF patients. In contrast, polymorphonuclear leukocyte adhesion and chemotaxis were normal. The functionality of beta1 and beta2 integrins was restored by treatment of CF monocytes with the CFTR correcting drugs VX325 and VX809. Moreover, treatment of healthy monocytes with the CFTR inhibitor CFTR inh-172 blocked integrin activation by chemoattractants. In a murine model of lung inflammation, we found that integrin-independent migration of CF monocytes into the lung parenchyma was normal, whereas, in contrast, integrin-dependent transmigration into the alveolar space was impaired. Finally, signal transduction analysis showed that in CF monocytes chemoattractant-triggered activation of RhoA and CDC42 rho small GTPases, controlling integrin activation and chemotaxis respectively, was strongly deficient. CONCLUSION: Altogether, these data highlight the critical regulatory role of CFTR in integrin activation by chemoattractants in monocytes and identify CF as a new, cell-type selective, leukocyte adhesion deficiency disease providing new insights on CF pathogenesis.

Item does not contain fulltext, BACKGROUND: Cystic fibrosis (CF) is a common genetic disease caused by mutations of the CF transmembrane conductance regulator (CFTR) gene. Persistent lung inflammation, characterized by increasing polymorphonuclear leukocyte recruitment, is a major cause of the decline in respiratory function in CF patients, and is a leading cause of morbidity and mortality. CFTR is expressed in various cell types, including leukocytes, but its involvement in the regulation of leukocyte recruitment is unknown. METHODS: Ex vivo adhesion and chemotaxis, flow cytometry, immunofluorescence, GTPases activity assays. RESULTS: We found that chemoattractant-induced activation of beta1 and beta2 integrins and of chemotaxis is defective in mononuclear cells isolated from CF patients. In contrast, polymorphonuclear leukocyte adhesion and chemotaxis were normal. The functionality of beta1 and beta2 integrins was restored by treatment of CF monocytes with the CFTR correcting drugs VX325 and VX809. Moreover, treatment of healthy monocytes with the CFTR inhibitor CFTR inh-172 blocked integrin activation by chemoattractants. In a murine model of lung inflammation, we found that integrin-independent migration of CF monocytes into the lung parenchyma was normal, whereas, in contrast, integrin-dependent transmigration into the alveolar space was impaired. Finally, signal transduction analysis showed that in CF monocytes chemoattractant-triggered activation of RhoA and CDC42 rho small GTPases, controlling integrin activation and chemotaxis respectively, was strongly deficient. CONCLUSION: Altogether, these data highlight the critical regulatory role of CFTR in integrin activation by chemoattractants in monocytes and identify CF as a new, cell-type selective, leukocyte adhesion deficiency disease providing new insights on CF pathogenesis.

Item does not contain fulltext, Regulatory T cells (Tregs) maintain tolerance toward self-antigens and suppress autoimmune diseases, although the underlying molecular mechanisms are unclear. In this study, we show that mice deficient for P-selectin glycoprotein ligand-1 (PSGL-1) develop a more severe form of experimental autoimmune encephalomyelitis than wild type animals do, suggesting that PSGL-1 has a role in the negative regulation of autoimmunity. We found that Tregs lacking PSGL-1 were unable to suppress experimental autoimmune encephalomyelitis and failed to inhibit T cell proliferation in vivo in the lymph nodes. Using two-photon laser-scanning microscopy in the lymph node, we found that PSGL-1 expression on Tregs had no role in the suppression of early T cell priming after immunization with Ag. Instead, PSGL-1-deficient Tregs lost the ability to modulate T cell movement and failed to inhibit the T cell-dendritic cell contacts and T cell clustering essential for sustained T cell activation during the late phase of the immune response. Notably, PSGL-1 expression on myelin-specific effector T cells had no role in T cell locomotion in the lymph node. Our data show that PSGL-1 represents a previously unknown, phase-specific mechanism for Treg-mediated suppression of the persistence of immune responses and autoimmunity induction.

Item does not contain fulltext, Regulatory T cells (Tregs) maintain tolerance toward self-antigens and suppress autoimmune diseases, although the underlying molecular mechanisms are unclear. In this study, we show that mice deficient for P-selectin glycoprotein ligand-1 (PSGL-1) develop a more severe form of experimental autoimmune encephalomyelitis than wild type animals do, suggesting that PSGL-1 has a role in the negative regulation of autoimmunity. We found that Tregs lacking PSGL-1 were unable to suppress experimental autoimmune encephalomyelitis and failed to inhibit T cell proliferation in vivo in the lymph nodes. Using two-photon laser-scanning microscopy in the lymph node, we found that PSGL-1 expression on Tregs had no role in the suppression of early T cell priming after immunization with Ag. Instead, PSGL-1-deficient Tregs lost the ability to modulate T cell movement and failed to inhibit the T cell-dendritic cell contacts and T cell clustering essential for sustained T cell activation during the late phase of the immune response. Notably, PSGL-1 expression on myelin-specific effector T cells had no role in T cell locomotion in the lymph node. Our data show that PSGL-1 represents a previously unknown, phase-specific mechanism for Treg-mediated suppression of the persistence of immune responses and autoimmunity induction.