RESUMO
The urinary tract is constantly exposed to microorganisms. Host defense mechanisms in protection from microbial colonization and development of urinary tract infections require better understanding to control kidney infection. Here we report that the lectin collectin 11 (CL-11), particularly kidney produced, has a pivotal role in host defense against uropathogen infection. CL-11 was found in mouse urine under normal and pathological conditions. Mice with global gene ablation of Colec11 had increased susceptibility to and severity of kidney and to an extent, bladder infection. Mice with kidney-specific Colec11 ablation exhibited a similar disease phenotype to that observed in global Colec11 deficient mice, indicating the importance of kidney produced CL-11 for protection against kidney and bladder infection. Conversely, intravesical or systemic administration of recombinant CL-11 reduced susceptibility to and severity of kidney and bladder infection. Mechanism analysis revealed that CL-11 can mediate several key innate defense mechanisms (agglutination, anti- adhesion, opsonophagocytosis), and limit local inflammatory responses to pathogens. Furthermore, CL-11-mediated innate defense mechanisms can act on clinically relevant microorganisms including multiple antibiotic resistant strains. CL-11 was detectable in eight of 24 urine samples from patients with urinary tract infections but not detectable in urine samples from ten healthy individuals. Thus, our findings demonstrate that CL-11 is a key factor of host defense mechanisms in kidney and bladder infection with therapeutic potential for human application.
Assuntos
Cistite , Infecções por Escherichia coli , Infecções Urinárias , Humanos , Camundongos , Animais , Bexiga Urinária , Rim , Colectinas/genéticaRESUMO
Collectin-11 (CL-11) is a recently described soluble C-type lectin that has distinct roles in embryonic development, host defence, autoimmunity, and fibrosis. Here we report that CL-11 also plays an important role in cancer cell proliferation and tumor growth. Melanoma growth was found to be suppressed in Colec11-/- mice in a s.c. B16 melanoma model. Cellular and molecular analyses revealed that CL-11 is essential for melanoma cell proliferation, angiogenesis, establishment of more immunosuppressive tumor microenvironment, and the reprogramming of macrophages to M2 phenotype within melanomas. In vitro analysis revealed that CL-11 can activate tyrosine kinase receptors (EGFR, HER3) and ERK, JNK, and AKT signaling pathways and has a direct stimulatory effect on murine melanoma cell proliferation. Furthermore, blockade of CL-11 (treatment with L-fucose) inhibited melanoma growth in mice. Analysis of open data sets revealed that COLEC11 gene expression is upregulated in human melanomas and that high COLEC11 expression has a trend toward poor survival. CL-11 also had direct stimulatory effects on human tumor cell proliferation in melanoma and several other types of cancer cells in vitro. Overall, our findings provide the first evidence to our knowledge that CL-11 is a key tumor growth-promoting protein and a promising therapeutic target in tumor growth.
Assuntos
Proliferação de Células , Colectinas , Melanoma Experimental , Neoplasias Cutâneas , Animais , Humanos , Camundongos , Autoimunidade , Proliferação de Células/genética , Proliferação de Células/fisiologia , Colectinas/metabolismo , Melanoma Experimental/genética , Melanoma Experimental/metabolismo , Proteínas de Neoplasias , Receptores Proteína Tirosina Quinases , Neoplasias Cutâneas/genética , Neoplasias Cutâneas/metabolismo , Microambiente Tumoral/genética , Microambiente Tumoral/fisiologiaRESUMO
Emerging evidence suggest that C3aR plays important roles in homeostasis, host defense and disease. Although it is known that C3aR is protective in several models of acute bacterial infections, the role for C3aR in chronic infection is largely unknown. Here we show that C3aR is protective in experimental chronic pyelonephritis. Global C3aR deficient (C3ar-/- ) mice had higher renal bacterial load, more pronounced renal histological lesions, increased renal apoptotic cell accumulation, tissue inflammation and extracellular matrix deposition following renal infection with uropathogenic E. coli (UPEC) strain IH11128, compared to WT control mice. Myeloid C3aR deficient (Lyz2-C3ar-/- ) mice exhibited a similar disease phenotype to global C3ar-/- mice. Pharmacological treatment with a C3aR agonist reduced disease severity in experimental chronic pyelonephritis. Furthermore, macrophages of C3ar-/- mice exhibited impaired ability to phagocytose UPEC. Our data clearly demonstrate a protective role for C3aR against experimental chronic pyelonephritis, macrophage C3aR plays a major role in the protection, and C3aR is necessary for phagocytosis of UPEC by macrophages. Our observation that C3aR agonist curtailed the pathology suggests a therapeutic potential for activation of C3aR in chronic infection.
Assuntos
Infecções por Escherichia coli , Pielonefrite , Receptores de Complemento , Animais , Camundongos , Infecções por Escherichia coli/imunologia , Infecções por Escherichia coli/patologia , Inflamação/imunologia , Inflamação/microbiologia , Inflamação/patologia , Rim/microbiologia , Rim/patologia , Macrófagos/imunologia , Macrófagos/metabolismo , Macrófagos/patologia , Pielonefrite/imunologia , Pielonefrite/microbiologia , Pielonefrite/patologia , Pielonefrite/prevenção & controle , Escherichia coli Uropatogênica/patogenicidade , Receptores de Complemento/agonistas , Receptores de Complemento/deficiência , Receptores de Complemento/genética , Receptores de Complemento/imunologia , Matriz Extracelular/metabolismoRESUMO
Our previous work using a murine model of pyelonephritis demonstrated that the C5a/C5aR1 axis plays a pathogenic role in acute kidney infection. In this study, we report that the C5a/C5aR1 axis also plays a pathogenic role in acute bladder infection. C5aR1-deficient mice had reduced bladder bacterial load and attenuated bladder tissue injury, which is associated with reduced expression of terminal α-mannosyl residues (Man) (a potential ligand for type 1 fimbriae of E. coli) at the luminal surface of the bladder epithelium and reduced early bacterial colonization of the bladder. In vitro, C5a stimulation enhanced mannose expression in and facilitated bacterial adhesion/colonization to human bladder epithelial cells. C5a stimulation also upregulated the activation of ERK1/2 and NF-κB signaling and gene expression of proinflammatory cytokines (i.e., Il6, Il1b, Cxcl1, Ccl2) in the epithelial cells, which could drive pro-inflammatory responses leading to tissue injury. Administration of the C5aR1 antagonist effectively reduced bladder bacterial load and tissue injury. Thus, our findings demonstrate a previously unknown pathogenic role for the C5a/C5aR1 axis in bladder infection and suggest that the C5a/C5aR1 axis-mediated upregulation of Man expression, enhancement of bacterial adhesion/colonization, and excessive inflammatory responses contribute to acute bladder infection. These findings improve our understanding of the pathogenesis of bladder infection with therapeutic implications for UTI.
Assuntos
Cistite , Pielonefrite , Escherichia coli Uropatogênica , Doença Aguda , Animais , Complemento C5a , Citocinas/metabolismo , Feminino , Humanos , Camundongos , Receptor da Anafilatoxina C5a/genética , Escherichia coli Uropatogênica/metabolismoRESUMO
OBJECTIVE: Collectin 11 (CL-11) is a soluble C-type lectin, a mediator of innate immunity. Its role in autoimmune disorders is unknown. We undertook this study to determine the role of CL-11 in a mouse model of rheumatoid arthritis (RA). METHODS: A murine collagen-induced arthritis (CIA) model was used and combined two approaches, including gene deletion of Colec11 and treatment with recombinant CL-11 (rCL-11). Joint inflammation and tissue destruction, circulating levels of inflammatory cytokines, and adaptive immune responses were assessed in mice with CIA. Splenic CD11c+ cells were used to examine the influence of CL-11 on antigen-presenting cell (APC) function. Serum CL-11 levels in RA patients were also examined. RESULTS: Colec11-/- mice developed more severe arthritis than wild-type mice, as determined by disease incidence, clinical arthritis scores, and histopathology (P < 0.05). Disease severity was associated with significantly enhanced APC activation, Th1/Th17 responses, pathogenic IgG2a production and joint inflammation, as well as elevated circulating levels of inflammatory cytokines. In vitro analysis of CD11c+ cells revealed that CL-11 is critical for suppression of APC activation and function. Pharmacologic treatment of mice with rCL-11 reduced the severity of CIA in mice. Analysis of human blood samples revealed that serum CL-11 levels were lower in RA patients (n = 51) compared to healthy controls (n = 53). Reduction in serum CL-11 was inversely associated with the Disease Activity Score in 28 joints, erythrocyte sedimentation rate, and C-reactive protein level (P < 0.05). CONCLUSION: Our findings demonstrate a novel role of CL-11 in protection against RA, suggesting that the underlying mechanism involves suppression of APC activation and subsequent T cell responses.
Assuntos
Artrite Experimental/genética , Artrite Reumatoide/genética , Colectinas/sangue , Imunidade Adaptativa/genética , Adulto , Animais , Células Apresentadoras de Antígenos/imunologia , Artrite Experimental/sangue , Artrite Experimental/imunologia , Artrite Reumatoide/sangue , Artrite Reumatoide/imunologia , Sedimentação Sanguínea , Proteína C-Reativa/metabolismo , Citocinas/sangue , Modelos Animais de Doenças , Feminino , Humanos , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Índice de Gravidade de Doença , Linfócitos T/imunologiaRESUMO
OBJECTIVE: Emerging evidence suggests that C3aR (C3a anaphylatoxin receptor) signaling has protective roles in various inflammatory-related diseases. However, its role in atherosclerosis has been unknown. The purpose of the study was to investigate the possible protective role of C3aR in aortic atherosclerosis and explore molecular and cellular mechanisms involved in the protection. Approach and Results: C3ar-/-/Apoe-/- mice were generated by cross-breeding of atherosclerosis-prone Apoe-/- mice and C3ar-/- mice. C3ar-/-/Apoe-/- mice and Apoe-/- mice (as a control) underwent high-fat diet for 16 weeks were assessed for (1) atherosclerotic plaque burden, (2) aortic tissue inflammation, (3) recruitment of CD11b+ leukocytes into atherosclerotic lesions, and (4) systemic inflammatory responses. Compared with Apoe-/- mice, C3ar-/-/Apoe-/- mice developed more severe atherosclerosis. In addition, C3ar-/-/Apoe-/- mice have increased local production of proinflammatory mediators (eg, CCL2 [chemokine (C-C motif) ligand 2], TNF [tumor necrosis factor]-α) and infiltration of monocyte/macrophage in aortic tissue, and their lesional macrophages displayed an M1-like phenotype. Local pathological changes were associated with enhanced systemic inflammatory responses (ie, elevated plasma levels of CCL2 and TNF-α, increased circulating inflammatory cells). In vitro analyses using peritoneal macrophages showed that C3a stimulation resulted in upregulation of M2-associated signaling and molecules, but suppression of M1-associated signaling and molecules, supporting the roles of C3a/C3aR axis in mediating anti-inflammatory response and promoting M2 macrophage polarization. CONCLUSIONS: Our findings demonstrate a protective role for C3aR in the development of atherosclerosis and suggest that C3aR confers the protection through C3a/C3aR axis-mediated negative regulation of proinflammatory responses and modulation of macrophage toward the anti-inflammatory phenotype.
Assuntos
Aorta/metabolismo , Doenças da Aorta/prevenção & controle , Aterosclerose/prevenção & controle , Inflamação/prevenção & controle , Macrófagos Peritoneais/metabolismo , Receptores Acoplados a Proteínas G/metabolismo , Animais , Aorta/imunologia , Aorta/patologia , Doenças da Aorta/imunologia , Doenças da Aorta/metabolismo , Doenças da Aorta/patologia , Aterosclerose/imunologia , Aterosclerose/metabolismo , Aterosclerose/patologia , Células Cultivadas , Quimiocina CCL2/metabolismo , Quimiotaxia , Modelos Animais de Doenças , Inflamação/imunologia , Inflamação/metabolismo , Inflamação/patologia , Mediadores da Inflamação/metabolismo , Macrófagos Peritoneais/imunologia , Macrófagos Peritoneais/patologia , Masculino , Camundongos Endogâmicos C57BL , Camundongos Knockout para ApoE , NF-kappa B/metabolismo , Fenótipo , Placa Aterosclerótica , Proteínas Proto-Oncogênicas c-akt/metabolismo , Receptores Acoplados a Proteínas G/deficiência , Receptores Acoplados a Proteínas G/genética , Transdução de Sinais , Serina-Treonina Quinases TOR/metabolismo , Fator de Necrose Tumoral alfa/metabolismoRESUMO
C5a is a potent inflammatory mediator that binds C5aR1 and C5aR2. Although pathogenic roles of the C5a/C5aR1 axis in inflammatory disorders are well documented, the roles for the C5a/C5aR2 axis in inflammatory disorders and underlying mechanisms remain unclear. Here, we show that the C5a/C5aR2 axis contributes to renal inflammation and tissue damage in a mouse model of acute pyelonephritis. Compared with WT littermates, C5ar2-/- mice had significantly reduced renal inflammation, tubular damage, and renal bacterial load following bladder inoculation with uropathogenic E. coli. The decrease in inflammatory responses in the kidney of C5ar2-/- mice was correlated with reduced intrarenal levels of high mobility group box-1 protein (HMGB1), NLRP3 inflammasome components, cleaved caspase-1, and IL-1ß. In vitro, C5a stimulation of macrophages from C5ar1-/- mice (lacking C5aR1 but expressing C5aR2) led to significant upregulation of HMGB1 release, NLRP3/cleaved caspase-1 inflammasome activation, and IL-1ß secretion. Furthermore, blockade of HMGB1 significantly reduced C5a-mediated upregulation of NLRP3/cleaved caspase-1 inflammasome activation and IL-1ß secretion in the macrophages, implying a HMGB1-dependent upregulation of NLRP3/cleaved caspase-1 inflammasome activation in macrophages. Our findings demonstrate a pathogenic role for the C5a/C5aR2 axis in renal injury following renal infection and suggest that the C5a/C5aR2 axis contributes to renal inflammation and tissue damage through upregulation of HMGB1 and NLRP3/cleaved caspase-1 inflammasome.
Assuntos
Complemento C5a/metabolismo , Nefropatias/metabolismo , Rim/metabolismo , Receptor da Anafilatoxina C5a/metabolismo , Animais , Caspase 1/genética , Caspase 1/metabolismo , Complemento C5a/genética , Proteína HMGB1/genética , Proteína HMGB1/metabolismo , Inflamação/genética , Inflamação/metabolismo , Inflamação/patologia , Rim/patologia , Nefropatias/genética , Nefropatias/patologia , Camundongos , Camundongos Knockout , Proteína 3 que Contém Domínio de Pirina da Família NLR/genética , Proteína 3 que Contém Domínio de Pirina da Família NLR/metabolismo , Receptor da Anafilatoxina C5a/genéticaRESUMO
Both the C3a/C3aR and C5a/C5aR1 axes are regarded as important pathways for inducing and regulating inflammatory responses. It is well documented that the C5a/C5aR1 axis is a potent inflammatory mediator in the pathogenesis of many clinic disorders. However, our understanding of the role of the C3a/C3aR axis in renal disorders remains limited. Contrary to the C5a/C5aR axis, we now show that the C3a/C3aR axis has a protective role in uropathogenic Escherichia coli (UPEC)-induced renal injury. C3aR-/- mice were found to develop severe renal pathology compared to wild type mice, a pathology characterized by intense tissue damage and an increased bacterial load within the kidney. This was associated with an overwhelming production of pro-inflammatory mediators and increased neutrophil infiltration in the kidney. Bone marrow chimera experiments found that tissue damage and bacterial load were significantly reduced in C3aR-/- mice that received bone marrow from wild type mice, compared with that in mice re-populated with bone marrow from C3aR-/- mice. This supports a critical role for C3aR on myeloid cells in the pathological process. Pharmacological treatment of mice with a C3aR agonist reduced both the extent of tissue injury and bacterial load. Mechanistic analyses indicated that the C3a/C3aR axis downregulates the lipopolysaccharide-induced pro-inflammatory responses in macrophages and facilitates the phagocytosis of UPEC by phagocytes. Thus, our findings clearly demonstrate a protective role of the C3a/C3aR axis in UPEC-induced renal injury, conferred by the suppression of pro-inflammatory responses and enhanced phagocytosis by macrophages.
Assuntos
Complemento C3a/metabolismo , Infecções por Escherichia coli/imunologia , Receptores de Complemento/metabolismo , Transdução de Sinais/imunologia , Infecções Urinárias/imunologia , Escherichia coli Uropatogênica/imunologia , Animais , Modelos Animais de Doenças , Resistência à Doença/imunologia , Infecções por Escherichia coli/diagnóstico , Infecções por Escherichia coli/microbiologia , Feminino , Humanos , Camundongos , Camundongos Knockout , Receptores de Complemento/genética , Índice de Gravidade de Doença , Infecções Urinárias/diagnóstico , Infecções Urinárias/microbiologiaRESUMO
C5a is a potent proinflammatory agonist that mediates renal ischemia reperfusion (IR) injury, but the potential for modulating chronic post-ischemic fibrosis and use of therapeutic antagonist are undefined. Here we determine whether C5a receptor 1 (C5aR1) signaling is essential to the development of post-ischemic fibrosis and if it is a valid target for therapeutic blockade with soluble receptor antagonist. C5aR1 is required for the development of renal tubulointerstitial fibrosis in a murine model of renal ischemia/reperfusion injury. Deficiency of C5aR1 protected mice from the development of the fibrosis. This protection was associated with attenuated deposition of extracellular matrix components (fibronectin, collagen I), reduced cellular infiltrates (CD45, F4/80), and gene expression of proinflammatory and profibrogenic mediators in the kidney. In an in vitro model of hypoxia/reoxygenation, C5a stimulation caused renal fibroblast proliferation and activation, and upregulated gene expression of interleukin-1α (IL-1α), IL-6 and transforming growth factor-α (TGF-α) in renal tubular epithelial cells and monocytes/macrophages. Administration of a C5aR1 antagonist (PMX53) significantly reduced renal injury and tubulointerstitial fibrosis. Thus, our results demonstrate a pathogenic role for C5aR1 in the progression of tubulointerstitial fibrosis following renal IR injury and support that C5aR1-mediated local inflammatory responses to hypoxic renal injury contribute to tubulointerstitial fibrosis through several cellular pathways, namely, promoting tubule injury, interstitial fibroblast proliferation and epithelial-to-mesenchymal transition of renal tubular epithelial cells. Our results also suggest the C5a-C5aR1 interaction is a therapeutic target for chronic post-ischemic fibrosis.
Assuntos
Túbulos Renais/patologia , Nefrite Intersticial/imunologia , Receptor da Anafilatoxina C5a/metabolismo , Traumatismo por Reperfusão/complicações , Transdução de Sinais/imunologia , Animais , Proliferação de Células , Complemento C5a/metabolismo , Modelos Animais de Doenças , Progressão da Doença , Transição Epitelial-Mesenquimal/imunologia , Fibroblastos , Fibrose , Humanos , Túbulos Renais/citologia , Túbulos Renais/imunologia , Masculino , Camundongos , Camundongos Knockout , Nefrite Intersticial/patologia , Receptor da Anafilatoxina C5a/genética , Receptor da Anafilatoxina C5a/imunologia , Traumatismo por Reperfusão/imunologia , Regulação para CimaRESUMO
Recent work in a murine model of ascending urinary tract infection has suggested that C5a/C5aR1 interactions play a pathogenic role in the development of renal infection through enhancement of bacterial adhesion/colonization to renal tubular epithelial cells (RTECs). In the present study, we extended these observations to human. We show that renal tubular epithelial C5aR1 signaling is involved in promoting uropathogenic Escherichia coli (UPEC) adhesion/invasion of host cells. Stimulation of primary cultures of RTEC with C5a resulted in significant increases in UPEC adhesion/invasion of the RTEC. This was associated with enhanced expression of terminal α-mannosyl residues (Man) (a ligand for type 1 fimbriae of E. coli) in the RTEC following C5a stimulation. Mechanism studies revealed that C5aR1-mediated activation of ERK1/2/NF-κB and upregulation of proinflammatory cytokine production (i.e., TNF-α) is at least partly responsible for the upregulation of Man expression and bacterial adhesion. Clinical sample studies showed that C5aR1 and Man were clearly detected in the renal tubular epithelium of normal human kidney biopsies, and UPEC bound to the epithelium in a d-mannose-dependent manner. Additionally, C5a levels were significantly increased in urine of urinary tract infection patients compared with healthy controls. Our data therefore demonstrate that, in agreement with observations in mice, human renal tubular epithelial C5aR1 signaling can upregulate Man expression in RTEC, which enhances UPEC adhesion to and invasion of RTEC. It also suggests the in vivo relevance of upregulation of Man expression in renal tubular epithelium by C5a/C5aR1 interactions and its potential impact on renal infection.
Assuntos
Aderência Bacteriana , Células Epiteliais/metabolismo , Células Epiteliais/microbiologia , Túbulos Renais/metabolismo , Receptor da Anafilatoxina C5a/metabolismo , Transdução de Sinais , Escherichia coli Uropatogênica/fisiologia , Biomarcadores , Células Cultivadas , Citocinas/metabolismo , Humanos , Imuno-Histoquímica , Mediadores da Inflamação/metabolismo , Túbulos Renais/citologia , Ligação ProteicaRESUMO
Background: Complement C5 mediates pro-inflammatory responses in many immune-related renal diseases. Given that the C5a level is elevated in diabetes, we investigated whether activation of C5a/C5aR signalling plays a pathogenic role in diabetic nephropathy (DN) and the therapeutic potential of C5a inhibition for renal fibrosis. Methods: Human renal biopsies from patients with DN and control subjects were used for immunohistochemical staining of complement C5 components. Renal function and tubulointerstitial injury were compared between db/m mice, vehicle-treated mice and C5a inhibitor-treated db/db mice. A cell culture model of tubule epithelial cells (HK-2) was used to demonstrate the effect of C5a on the renal fibrotic pathway. Results: Increased levels of C5a, but not of its receptor C5aR, were detected in renal tubules from patients with DN. The intensity of C5a staining was positively correlated with the progression of the disease. In db/db mice, administration of a novel C5a inhibitor, NOX-D21, reduced the serum triglyceride level and attenuated the upregulation of diacylglycerolacyltransferase-1 and sterol-regulatory element binding protein-1 expression and lipid accumulation in diabetic kidney. NOX-D21-treated diabetic mice also had reduced serum blood urea nitrogen and creatinine levels with less glomerular and tubulointerstitial damage. Renal transforming growth factor beta 1 (TGF-ß1), fibronectin and collagen type I expressions were reduced by NOX-D21. In HK-2 cells, C5a stimulated TGF-ß production through the activation of the PI3K/Akt signalling pathway. Conclusions: Blockade of C5a signalling by NOX-D21 moderates altered lipid metabolism in diabetes and improved tubulointerstitial fibrosis by reduction of lipid accumulation and TGF-ß-driven fibrosis in diabetic kidney.
Assuntos
Aptâmeros de Nucleotídeos/farmacologia , Complemento C5a/antagonistas & inibidores , Diabetes Mellitus Experimental/fisiopatologia , Nefropatias Diabéticas/complicações , Fibrose/prevenção & controle , Nefropatias/prevenção & controle , Metabolismo dos Lipídeos/efeitos dos fármacos , Animais , Fibrose/etiologia , Fibrose/metabolismo , Humanos , Nefropatias/etiologia , Nefropatias/metabolismo , Túbulos Renais/efeitos dos fármacos , Túbulos Renais/metabolismo , Túbulos Renais/patologia , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Fosfatidilinositol 3-Quinases/metabolismo , Serina Endopeptidases/farmacologia , Transdução de Sinais/efeitos dos fármacos , Fator de Crescimento Transformador beta/metabolismoRESUMO
Collectin-11 is a recently described soluble C-type lectin, a pattern recognition molecule of the innate immune system that has distinct roles in host defense, embryonic development, and acute inflammation. However, little is known regarding the role of collectin-11 in tissue fibrosis. Here, we investigated collectin-11 in the context of renal ischemia-reperfusion injury. Compared with wild-type littermate controls, Collec11 deficient (CL-11-/- ) mice had significantly reduced renal functional impairment, tubular injury, renal leukocyte infiltration, renal tissue inflammation/fibrogenesis, and collagen deposition in the kidneys after renal ischemia-reperfusion injury. In vitro, recombinant collectin-11 potently promoted leukocyte migration and renal fibroblast proliferation in a carbohydrate-dependent manner. Additionally, compared with wild-type kidney grafts, CL-11-/-mice kidney grafts displayed significantly reduced tubular injury and collagen deposition after syngeneic kidney transplant. Our findings demonstrate a pathogenic role for collectin-11 in the development of tubulointerstitial fibrosis and suggest that local collectin-11 promotes this fibrosis through effects on leukocyte chemotaxis and renal fibroblast proliferation. This insight into the pathogenesis of tubulointerstitial fibrosis may have implications for CKD mediated by other causes as well.
Assuntos
Proliferação de Células/efeitos dos fármacos , Quimiotaxia de Leucócito/genética , Colectinas/genética , Colectinas/farmacologia , Túbulos Renais/patologia , Nefrite/genética , Aloenxertos/patologia , Animais , Quimiotaxia de Leucócito/efeitos dos fármacos , Colágeno/metabolismo , Colectinas/metabolismo , Matriz Extracelular/metabolismo , Fibroblastos/fisiologia , Fibrose , Transplante de Rim , Túbulos Renais/metabolismo , Masculino , Camundongos , Camundongos Knockout , Nefrite/etiologia , Nefrite/patologia , Nefrite/fisiopatologia , Traumatismo por Reperfusão/complicações , Traumatismo por Reperfusão/patologiaRESUMO
C5a receptor 1 (C5aR1) is a G protein-coupled receptor for C5a and also an N-linked glycosylated protein. In addition to myeloid cells, C5aR1 is expressed on epithelial cells. In this study, we examined the role of C5aR1 in bacterial adhesion/colonization of renal tubular epithelium and addressed the underlying mechanisms of this role. We show that acute kidney infection was significantly reduced in mice with genetic deletion or through pharmacologic inhibition of C5aR1 following bladder inoculation with uropathogenic E. coli (UPEC). This was associated with reduced expression of terminal α-mannosyl residues (Man; a ligand for type 1 fimbriae of E. coli) on the luminal surface of renal tubular epithelium and reduction of early UPEC colonization in these mice. Confocal microscopy demonstrated that UPEC bind to Man on the luminal surface of renal tubular epithelium. In vitro analyses showed that C5a stimulation enhances Man expression in renal tubular epithelial cells and subsequent bacterial adhesion, which, at least in part, is dependent on TNF-α driven by C5aR1-mediated intracellular signaling. Our findings demonstrate a previously unknown pathogenic role for C5aR1 in acute pyelonephritis, proposing a potentially novel mechanism by which C5a/C5aR1 signaling mediates upregulation of carbohydrate ligands on renal tubules to facilitate UPEC adhesion.
Assuntos
Infecções por Escherichia coli/metabolismo , Pielonefrite/microbiologia , Receptor da Anafilatoxina C5a/fisiologia , Infecções Urinárias/metabolismo , Escherichia coli Uropatogênica , Doença Aguda , Animais , Aderência Bacteriana/fisiologia , Complemento C5a/imunologia , Citocinas/biossíntese , Mediadores da Inflamação/metabolismo , Rim/metabolismo , Rim/microbiologia , Camundongos Knockout , Microscopia Confocal , Pielonefrite/metabolismo , Pielonefrite/prevenção & controle , Receptor da Anafilatoxina C5a/deficiência , Receptor da Anafilatoxina C5a/metabolismo , Regulação para Cima/imunologiaRESUMO
Complement receptor 3 (CR3) is expressed abundantly on natural killer (NK) cells; however, whether it plays roles in NK cell-dependent tumor surveillance is largely unknown. Here, we show that CR3 is an important negative regulator of NK cell function, which has negative impact on tumor surveillance. Mice deficient in CR3 (CD11b-/- mice) exhibited a more activated NK phenotype and had enhanced NK-dependent tumor killing. In a B16-luc melanoma-induced lung tumor growth and metastasis model, mice deficient in CR3 had reduced tumor growth and metastases, compared with WT mice. In addition, adaptive transfer of NK cells lacking CR3 (into NK-deficient mice) mediated more efficient suppression of tumor growth and metastases, compared with the transfer of CR3 sufficient NK cells, suggesting that CR3 can impair tumor surveillance through suppression of NK cell function. In vitro analyses showed that engagement of CR3 with iC3b (classical CR3 ligand) on NK cells negatively regulated NK cell activity and effector functions (i.e. direct tumor cell killing, antibody-dependent NK-mediated tumor killing). Cell signaling analyses showed that iC3b stimulation caused activation of Src homology 2 domain-containing inositol-5-phosphatase-1 (SHIP-1) and JNK, and suppression of ERK in NK cells, supporting that iC3b mediates negative regulation of NK cell function through its effects on SHIP-1, JNK, and ERK signal transduction pathways. Thus, our findings demonstrate a previously unknown role for CR3 in dysregulation of NK-dependent tumor surveillance and suggest that the iC3b/CR3 signaling is a critical negative regulator of NK cell function and may represent a new target for preserving NK cell function in cancer patients and improving NK cell-based therapy.
RESUMO
In this paper, we report previously unknown roles for collectin-11 (CL-11, a soluble C-type lectin) in modulating the retinal pigment epithelial (RPE) cell functions of phagocytosis and cytokine production. We found that CL-11 and its carbohydrate ligand are expressed in both the murine and human neural retina; these resemble each other in terms of RPE and photoreceptor cells. Functional analysis of murine RPE cells showed that CL-11 facilitates the opsonophagocytosis of photoreceptor outer segments and apoptotic cells, and also upregulates IL-10 production. Mechanistic analysis revealed that calreticulin on the RPE cells is required for CL-11-mediated opsonophagocytosis whereas signal-regulatory protein α and mannosyl residues on the cells are involved in the CL-11-mediated upregulation of IL-10 production. This study is the first to demonstrate the role of CL-11 and the molecular mechanisms involved in modulating RPE cell phagocytosis and cytokine production. It provides a new insight into retinal health and disease and has implications for other phagocytic cells.
Assuntos
Calreticulina/metabolismo , Colectinas/metabolismo , Retina/patologia , Epitélio Pigmentado da Retina/metabolismo , Animais , Células Cultivadas , Colectinas/genética , Citofagocitose , Humanos , Interleucina-10/metabolismo , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Epitélio Pigmentado da Retina/patologia , Pigmentos da Retina/metabolismo , Regulação para CimaRESUMO
Complement plays an important role in the pathogenesis of rheumatoid arthritis. Although the alternative pathway (AP) is known to play a key pathogenic role in models of rheumatoid arthritis, the importance of the lectin pathway (LP) pattern recognition molecules such as ficolin (FCN) A, FCN B, and collectin (CL)-11, as well as the activating enzyme mannose-binding lectin-associated serine protease-2 (MASP-2), are less well understood. We show in this article that FCN A-/- and CL-11-/- mice are fully susceptible to collagen Ab-induced arthritis (CAIA). In contrast, FCN B-/- and MASP-2-/-/sMAp-/- mice are substantially protected, with clinical disease activity decreased significantly (p < 0.05) by 47 and 70%, respectively. Histopathology scores, C3, factor D, FCN B deposition, and infiltration of synovial macrophages and neutrophils were similarly decreased in FCN B-/- and MASP-2-/-/sMAp-/- mice. Our data support that FCN B plays an important role in the development of CAIA, likely through ligand recognition in the joint and MASP activation, and that MASP-2 also contributes to the development of CAIA, likely in a C4-independent manner. Decreased AP activity in the sera from FCN B-/- and MASP-2-/-/sMAp-/- mice with arthritis on adherent anti-collagen Abs also support the hypothesis that pathogenic Abs, as well as additional inflammation-related ligands, are recognized by the LP and operate in vivo to activate complement. Finally, we also speculate that the residual disease seen in our studies is driven by the AP and/or the C2/C4 bypass pathway via the direct cleavage of C3 through an LP-dependent mechanism.
Assuntos
Artrite Experimental/imunologia , Artrite Reumatoide/imunologia , Lectina de Ligação a Manose da Via do Complemento , Inflamação/imunologia , Lectinas/metabolismo , Serina Proteases Associadas a Proteína de Ligação a Manose/metabolismo , Animais , Complexo Antígeno-Anticorpo/metabolismo , Células Cultivadas , Colágeno/imunologia , Colectinas/genética , Colectinas/metabolismo , Proteínas do Sistema Complemento/metabolismo , Humanos , Lectinas/genética , Serina Proteases Associadas a Proteína de Ligação a Manose/genética , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , FicolinasRESUMO
Complement factor 5a (C5a) interaction with its receptor (C5aR1) contributes to the pathogenesis of inflammatory diseases, including acute kidney injury. However, its role in chronic inflammation, particularly in pathogen-associated disorders, is largely unknown. Here we tested whether the development of chronic inflammation and renal fibrosis is dependent on C5aR1 in a murine model of chronic pyelonephritis. C5aR1-deficient (C5aR1-/-) mice showed a significant reduction in bacterial load, tubule injury and tubulointerstitial fibrosis in the kidneys following infection, compared with C5aR1-sufficient mice. This was associated with reduced renal leukocyte infiltration specifically for the population of Ly6Chi proinflammatory monocytes/macrophages and reduced intrarenal gene expression of key proinflammatory and profibrogenic factors in C5aR1-/- mice following infection. Antagonizing C5aR1 decreased renal bacterial load, tissue inflammation and tubulointerstitial fibrosis. Ex vivo and in vitro studies showed that under infection conditions, C5a/C5aR1 interaction upregulated the production of proinflammatory and profibrogenic factors by renal tubular epithelial cells and monocytes/macrophages, whereas the phagocytic function of monocytes/macrophages was down-regulated. Thus, C5aR1-dependent bacterial colonization of the tubular epithelium, C5a/C5aR1-mediated upregulation of local inflammatory responses to uropathogenic E. coli and impairment of phagocytic function of phagocytes contribute to persistent bacterial colonization of the kidney, chronic renal inflammation and subsequent tubulointerstitial fibrosis.
Assuntos
Infecções por Escherichia coli/patologia , Inflamação/patologia , Rim/patologia , Pielonefrite/patologia , Receptor da Anafilatoxina C5a/metabolismo , Escherichia coli Uropatogênica/isolamento & purificação , Animais , Antígenos Ly , Carga Bacteriana , Doença Crônica , Complemento C5a/metabolismo , Modelos Animais de Doenças , Células Epiteliais/metabolismo , Células Epiteliais/microbiologia , Fibrose , Rim/citologia , Leucócitos/metabolismo , Macrófagos/metabolismo , Camundongos , Camundongos Knockout , Monócitos/metabolismo , Peptídeos Cíclicos/farmacologia , Receptor da Anafilatoxina C5a/antagonistas & inibidores , Receptor da Anafilatoxina C5a/genéticaRESUMO
In the last 15 years two major advances in the role of complement in the kidney transplant have come about. The first is that ischaemia reperfusion injury and its profound effect on transplant outcome is dependent on the terminal product of complement activation, C5b-9. The second key observation relates to the function of the small biologically active fragments C3a and C5a released by complement activation in increasing antigen presentation and priming the T cell response that results in transplant rejection. In both cases local synthesis of C3 principally by the renal tubule cells plays an essential role that overshadows the role of the circulating pool of C3 generated largely by hepatocyte synthesis. More recent efforts have investigated the molecules expressed by renal tissue that can trigger complement activation. These have revealed a prominent effect of collectin-11 (CL-11), a soluble C-type lectin that is expressed in renal tissue and aligns with its major ligand L-fucose at sites of complement activation following ischaemic stress. Biochemical studies have shown that interaction between CL-11 and L-fucose results in complement activation by the lectin complement pathway, precisely targeting the innate immune response to the ischaemic tubule surface. Therapeutic approaches to reduce inflammatory and immune stimulation in ischaemic kidney have so far targeted C3 or its activation products and several are in clinical trials. The finding that lectin-fucose interaction is an important trigger of lectin pathway complement activation within the donor organ opens up further therapeutic targets where intervention could protect the donor kidney against complement.
Assuntos
Lectina de Ligação a Manose da Via do Complemento/imunologia , Proteínas do Sistema Complemento/imunologia , Transplante de Rim , Imunologia de Transplantes , Animais , Biomarcadores , Proteínas do Sistema Complemento/metabolismo , Rejeição de Enxerto/imunologia , Humanos , Imunidade Inata , Lectina de Ligação a Manose/imunologia , Lectina de Ligação a Manose/metabolismo , Traumatismo por Reperfusão/etiologia , Traumatismo por Reperfusão/metabolismo , Traumatismo por Reperfusão/patologiaRESUMO
Physiochemical stress induces tissue injury as a result of the detection of abnormal molecular patterns by sensory molecules of the innate immune system. Here, we have described how the recently discovered C-type lectin collectin-11 (CL-11, also known as CL-K1 and encoded by COLEC11) recognizes an abnormal pattern of L-fucose on postischemic renal tubule cells and activates a destructive inflammatory response. We found that intrarenal expression of CL-11 rapidly increases in the postischemic period and colocalizes with complement deposited along the basolateral surface of the proximal renal tubule in association with L-fucose, the potential binding ligand for CL-11. Mice with either generalized or kidney-specific deficiency of CL-11 were strongly protected against loss of renal function and tubule injury due to reduced complement deposition. Ex vivo renal tubule cells showed a marked capacity for CL-11 binding that was induced by cell stress under hypoxic or hypothermic conditions and prevented by specific removal of L-fucose. Further analysis revealed that cell-bound CL-11 required the lectin complement pathway-associated protease MASP-2 to trigger complement deposition. Given these results, we conclude that lectin complement pathway activation triggered by ligand-CL-11 interaction in postischemic tissue is a potent source of acute kidney injury and is amenable to sugar-specific blockade.
Assuntos
Injúria Renal Aguda/metabolismo , Colectinas/metabolismo , Lectina de Ligação a Manose da Via do Complemento/efeitos dos fármacos , Proteínas do Sistema Complemento/metabolismo , Fucose/toxicidade , Túbulos Renais Proximais/lesões , Túbulos Renais Proximais/metabolismo , Injúria Renal Aguda/induzido quimicamente , Injúria Renal Aguda/genética , Injúria Renal Aguda/patologia , Animais , Colectinas/genética , Lectina de Ligação a Manose da Via do Complemento/genética , Proteínas do Sistema Complemento/genética , Túbulos Renais Proximais/patologia , Serina Proteases Associadas a Proteína de Ligação a Manose/genética , Serina Proteases Associadas a Proteína de Ligação a Manose/metabolismo , Camundongos , Camundongos KnockoutRESUMO
The pathogenesis of pyelonephritis caused by uropathogenic Escherichia coli (UPEC) is not well understood. Here, we show that besides UPEC virulence, the severity of the host innate immune response and invasion of renal epithelial cells are important pathogenic factors. Activation of endogenous anti-inflammatory mediator cAMP significantly attenuated acute pyelonephritis in mice induced by UPEC. Administration of forskolin (a potent elevator of intracellular cAMP) reduced kidney infection (ie, bacterial load, tissue destruction); this was associated with attenuated local inflammation, as evidenced by the reduction of renal production of proinflammatory mediators, renal infiltration of inflammatory cells, and renal myeloperoxidase activity. In primary cell culture systems, forskolin not only down-regulated UPEC-stimulated production of proinflammatory mediators by renal tubular epithelial cells and inflammatory cells (eg, monocyte/macrophages) but also reduced bacterial internalization by renal tubular epithelial cells. Our findings clearly indicate that activation of endogenous anti-inflammatory mediator cAMP is beneficial for controlling UPEC-mediated acute pyelonephritis in mice. The beneficial effect can be explained at least in part by limiting excessive inflammatory responses through acting on both renal tubular epithelial cells and inflammatory cells and by inhibiting bacteria invasion of renal tubular epithelial cells.