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The lectin but not classical pathway of activation is important for complement to regulate the development of experimental autoimmune uveitis
Abstracts / Immunobiology 221 (2016) 1131–1225
phagocytosis of SEC/hDAF (11.2 ± 1.7%) was significantly suppressed compared to naïve SEC (30.1 ± 11.8%), hDAF delta-SCR4 failed to suppress the phagocytosis by macrophage (29.5 ± 8.6%). These findings indicate that DAF suppresses macrophage-mediated rejection via binding of SCR4 to an inhibitory receptor on macrophages. http://dx.doi.org/10.1016/j.imbio.2016.06.019 5 Painting factor H onto mesenchymal stem cells protects the cells from complement- and neutrophil-mediated damage Yan Li 1,∗ , Wen Qiu 1 , Lingjun Zhang 1 , John Fung 2 , Feng Lin 1 1 Department of Immunology, Cleveland Clinic, Cleveland, OH, USA 2 Digestive Disease Institute, Cleveland Clinic, Cleveland, OH, USA
Mesenchymal stem cells (MSCs) are undergoing intensive testing in clinical trials as a promising new therapy for many inflammatory diseases and for regenerative medicine, but further optimization of current MSC-based therapies is required. In this study, we found that in addition to direct complement–mediated attack through the assembly of membrane attack complexes (MACs) that we and others have recently reported, of the released complement activation products, C5a, but not C3a, activates neutrophils in the blood to further damage MSCs through oxidative burst. In addition, we have developed a simple method for painting factor H, a native complement inhibitor, onto MSCs to locally inhibit complement activation on MSCs. MSCs painted with factor H are protected from both MAC- and neutrophil-mediated attack and are significantly more effective in inhibiting antigen-specific T cell responses than the mock-painted MSCs both in vitro and in vivo. http://dx.doi.org/10.1016/j.imbio.2016.06.020 6 The lectin but not classical pathway of activation is important for complement to regulate the development of experimental autoimmune uveitis Lingjun Zhang 1,5,∗ , Brent A. Bell 2 , Yan Li 3 , Xiaomin Zhang 1 , John J. Fung 4 , Rachel R. Caspi 3 , Feng Lin 5 1
Tianjin Medical University Eye Hospital, Eye Institute, Tianjin, China 2 Cole Eye Institute, Cleveland Clinic, Cleveland, OH, USA 3 Laboratory of Immunology, National Eye Institute, National Institutes of Health, Bethesda, MD, USA 4 Digestive Diseases Institute, Cleveland Clinic, Cleveland, OH, USA 5 Department of Immunology, Cleveland Clinic, Cleveland, OH, USA Purpose: Complement needs to be activated to function. Although the alternative pathway has been found important in regulating T cell responses, the potential roles of the other two complement activation pathways, the classical and the lectin pathways in this process remain unclear. To address this issue, we studied
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mice deficient of C4 (both classical and lectin pathways deficient) or C1q (classical pathway deficient) in the development of experimental autoimmune uveitis (EAU). Methods: WT, C4 and C1q knockout (KO) mice (all C57BL/6J background) were immunized with interphotoreceptor retinoid binding protein (IRBP) peptide to induce EAU following an established protocol. After immunization, the development of EAU was monitored by indirect ophthalmoscopy, and clinical scores were assigned according to previously published criteria. Two weeks after immunization, mice were also examined by scanning laser ophthalmoscopy (SLO) and spectral-domain optical coherence tomography (OCT). Three weeks after immunization, mice were euthanized for retinal histopathological analysis, for numbers of antigen-specific CD4+ T cells comparison by tetramer staining, and for antigen-specific Th1/Th17 responses assessment by recall assays. Results: After immunization, C4 KO mice developed significantly milder EAU than WT controls while C1q KO mice developed comparable EAU to WT mice as judged by clinical scores, retinal histopathological scores, SLO and OCT analyses. Consistent with the imaging results, C4 KO mice in EAU also showed reduced numbers of IRBP-specific CD4+ T cells and had decreased IRBP-specific Th1 and Th17 responses compared with WT mice while C1q mice in EAU did not show any significant difference from WT mice in these immunological assays. Conclusions: Complement classical pathway of activation is not important for the development of EAU, while the lectin pathway of complement activation is required. These data suggest that the lectin pathway of complement activation should be a novel target to suppress pathogenic T cell responses for treating EAU, and potentially, for treating autoimmune uveitis. http://dx.doi.org/10.1016/j.imbio.2016.06.021 7 Absence of complement protects against bone loss in a model of postmenopausal osteoporosis Danielle L. MacKay 1,∗ , Thomas J. Kean 1 , Kristina G. Bernardi 2 , G. Adam Whitney 1 , James E. Dennis 1 , Feng Lin 3 1
Department of Orthopedic Surgery, Baylor College of Medicine, Houston, TX, USA 2 Seattle Children’s Hospital, Seattle, WA, USA 3 Department of Immunology, Cleveland Clinic Lerner Research Institute, Cleveland, OH, USA The growing field of osteoimmunology seeks to unravel the complex interdependence of the skeletal and immune systems. Notably, we and others have demonstrated that complement signaling influences the differentiation of osteoblasts and osteoclasts, the two primary cell types responsible for maintaining bone homeostasis. However, the net effect of complement on bone homeostasis in vivo was unknown. To address this, bone loss in a model of postmenopausal osteoporosis was studied using complement component 3 (C3) deficient mice. WT and C3−/− mice (both on a C57BL/6 background) were either ovariectomized or shamoperated at 6 weeks of age and euthanized at 12 weeks. Harvested bones were analyzed by microCT, 3-point bending, femoral neck testing, and histomorphometry. MicroCT revealed that the trabecular bone volume fraction in the metaphyses of both the proximal tibiae and distal femora of ovariectomized C3−/− mice is significantly greater than that of their WT counterparts. Mechanical testing demonstrated significantly greater stiffness in the femoral necks of ovariectomized C3−/− mice. Lumbar vertebrae showed
phagocytosis of SEC/hDAF (11.2 ± 1.7%) was significantly suppressed compared to naïve SEC (30.1 ± 11.8%), hDAF delta-SCR4 failed to suppress the phagocytosis by macrophage (29.5 ± 8.6%). These findings indicate that DAF suppresses macrophage-mediated rejection via binding of SCR4 to an inhibitory receptor on macrophages. http://dx.doi.org/10.1016/j.imbio.2016.06.019 5 Painting factor H onto mesenchymal stem cells protects the cells from complement- and neutrophil-mediated damage Yan Li 1,∗ , Wen Qiu 1 , Lingjun Zhang 1 , John Fung 2 , Feng Lin 1 1 Department of Immunology, Cleveland Clinic, Cleveland, OH, USA 2 Digestive Disease Institute, Cleveland Clinic, Cleveland, OH, USA
Mesenchymal stem cells (MSCs) are undergoing intensive testing in clinical trials as a promising new therapy for many inflammatory diseases and for regenerative medicine, but further optimization of current MSC-based therapies is required. In this study, we found that in addition to direct complement–mediated attack through the assembly of membrane attack complexes (MACs) that we and others have recently reported, of the released complement activation products, C5a, but not C3a, activates neutrophils in the blood to further damage MSCs through oxidative burst. In addition, we have developed a simple method for painting factor H, a native complement inhibitor, onto MSCs to locally inhibit complement activation on MSCs. MSCs painted with factor H are protected from both MAC- and neutrophil-mediated attack and are significantly more effective in inhibiting antigen-specific T cell responses than the mock-painted MSCs both in vitro and in vivo. http://dx.doi.org/10.1016/j.imbio.2016.06.020 6 The lectin but not classical pathway of activation is important for complement to regulate the development of experimental autoimmune uveitis Lingjun Zhang 1,5,∗ , Brent A. Bell 2 , Yan Li 3 , Xiaomin Zhang 1 , John J. Fung 4 , Rachel R. Caspi 3 , Feng Lin 5 1
Tianjin Medical University Eye Hospital, Eye Institute, Tianjin, China 2 Cole Eye Institute, Cleveland Clinic, Cleveland, OH, USA 3 Laboratory of Immunology, National Eye Institute, National Institutes of Health, Bethesda, MD, USA 4 Digestive Diseases Institute, Cleveland Clinic, Cleveland, OH, USA 5 Department of Immunology, Cleveland Clinic, Cleveland, OH, USA Purpose: Complement needs to be activated to function. Although the alternative pathway has been found important in regulating T cell responses, the potential roles of the other two complement activation pathways, the classical and the lectin pathways in this process remain unclear. To address this issue, we studied
1133
mice deficient of C4 (both classical and lectin pathways deficient) or C1q (classical pathway deficient) in the development of experimental autoimmune uveitis (EAU). Methods: WT, C4 and C1q knockout (KO) mice (all C57BL/6J background) were immunized with interphotoreceptor retinoid binding protein (IRBP) peptide to induce EAU following an established protocol. After immunization, the development of EAU was monitored by indirect ophthalmoscopy, and clinical scores were assigned according to previously published criteria. Two weeks after immunization, mice were also examined by scanning laser ophthalmoscopy (SLO) and spectral-domain optical coherence tomography (OCT). Three weeks after immunization, mice were euthanized for retinal histopathological analysis, for numbers of antigen-specific CD4+ T cells comparison by tetramer staining, and for antigen-specific Th1/Th17 responses assessment by recall assays. Results: After immunization, C4 KO mice developed significantly milder EAU than WT controls while C1q KO mice developed comparable EAU to WT mice as judged by clinical scores, retinal histopathological scores, SLO and OCT analyses. Consistent with the imaging results, C4 KO mice in EAU also showed reduced numbers of IRBP-specific CD4+ T cells and had decreased IRBP-specific Th1 and Th17 responses compared with WT mice while C1q mice in EAU did not show any significant difference from WT mice in these immunological assays. Conclusions: Complement classical pathway of activation is not important for the development of EAU, while the lectin pathway of complement activation is required. These data suggest that the lectin pathway of complement activation should be a novel target to suppress pathogenic T cell responses for treating EAU, and potentially, for treating autoimmune uveitis. http://dx.doi.org/10.1016/j.imbio.2016.06.021 7 Absence of complement protects against bone loss in a model of postmenopausal osteoporosis Danielle L. MacKay 1,∗ , Thomas J. Kean 1 , Kristina G. Bernardi 2 , G. Adam Whitney 1 , James E. Dennis 1 , Feng Lin 3 1
Department of Orthopedic Surgery, Baylor College of Medicine, Houston, TX, USA 2 Seattle Children’s Hospital, Seattle, WA, USA 3 Department of Immunology, Cleveland Clinic Lerner Research Institute, Cleveland, OH, USA The growing field of osteoimmunology seeks to unravel the complex interdependence of the skeletal and immune systems. Notably, we and others have demonstrated that complement signaling influences the differentiation of osteoblasts and osteoclasts, the two primary cell types responsible for maintaining bone homeostasis. However, the net effect of complement on bone homeostasis in vivo was unknown. To address this, bone loss in a model of postmenopausal osteoporosis was studied using complement component 3 (C3) deficient mice. WT and C3−/− mice (both on a C57BL/6 background) were either ovariectomized or shamoperated at 6 weeks of age and euthanized at 12 weeks. Harvested bones were analyzed by microCT, 3-point bending, femoral neck testing, and histomorphometry. MicroCT revealed that the trabecular bone volume fraction in the metaphyses of both the proximal tibiae and distal femora of ovariectomized C3−/− mice is significantly greater than that of their WT counterparts. Mechanical testing demonstrated significantly greater stiffness in the femoral necks of ovariectomized C3−/− mice. Lumbar vertebrae showed