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The Shimanami Leaf®, produced at Innoshima Island in Onomichi City, Hiroshima Prefecture, Japan, is a leafy vegetable that does not require pesticide use and has a high nutritional value. Although the leaf has abundant dietary fiber and other nutrients, reports on its biological regulatory functions are lacking. Therefore, this study aimed to elucidate the effects of Shimanami leaf intake on bowel movement and gut microbiota in mice. We examined the effects of Shimanami leaves on fecal weight, fecal water content, and intestinal microbiota composition. On day 10 of administration, the Shimanami leaf-treated group exhibited significantly higher fecal weight and water content than the control group. Next-generation sequencing analysis revealed that the ingestion of Shimanami leaf increased the abundances and diversity of intestinal bacteria, including members from Lactococcus, Streptococcus, and Muribaculaceae. Our findings suggest that Shimanami leaf supplementation improves bowel movement and promotes defecation.
Assuntos
Microbioma Gastrointestinal , Camundongos , Animais , Defecação , Fezes/microbiologia , Fibras na Dieta/farmacologia , Folhas de PlantaRESUMO
Blood levels of the extracellular matrix protein nephronectin (Npnt), a protein critical for kidney development, are elevated in autoimmune experimental autoimmune encephalitis (EAE) mice, which are a model for multiple sclerosis. We found here that treatment with anti-Npnt antibody directed against the α8ß1 integrin-binding site (Npnt-blocking antibody) inhibits EAE development. The selenium transporter selenoprotein P (SeP) was identified as a novel Npnt-binding partner. In EAE, Npnt induced SeP and glutathione peroxidase 1 (GPx1) expression, followed by reactive oxygen species (ROS) inhibition in CD4+ T cells; these changes were disturbed by Npnt-blocking antibody treatment, which also caused suppressed differentiation of interleukin (IL)-17-producing CD4+ T-helper cells (Th17s) and elevated differentiation of regulatory T cells (Tregs). Treatment of EAE mice with the ROS scavenger N-acetyl cysteine (NAC) blocked the Npnt-blocking antibody-induced decrease in Th17 differentiation and increase in Treg differentiation. In conclusion, the interaction between Npnt and SeP contributes to EAE development by regulating the Th17/Treg balance via the ROS level.
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Encefalomielite Autoimune Experimental , Linfócitos T Reguladores , Células Th17 , Animais , Encefalomielite Autoimune Experimental/imunologia , Proteínas da Matriz Extracelular/metabolismo , Camundongos , Camundongos Endogâmicos C57BL , Espécies Reativas de Oxigênio/metabolismo , Células Th17/metabolismoRESUMO
Roles of interstitial tissue in morphogenesis of testicular structures remain less well understood. To analyze the roles of CD34+ cells in the reconstruction of interstitial tissue containing Leydig cells (LCs), and testicular structures, we used 3D-reaggregate culture of dissociated testicular cells from prepubertal mouse. After a week of culture, adult Leydig cells (ALCs) were preferentially incorporated within CD34+ cell-aggregates, but fetal LCs (FLCs) were not. Immunofluorescence studies showed that integrins α4, α9 and ß1, and VCAM1, one of the ligands for integrins α4ß1 and α9ß1, are expressed mainly in CD34+ cells and ALCs, but not in FLCs. Addition of function-blocking antibodies against each integrin and VCAM1 to the culture disturbed the reconstruction of testicular structures. Antibodies against α4 and ß1 integrins and VCAM1 robustly inhibited cell-to-cell adhesion between testicular cells and between CD34+ cells. Cell-adhesion assays indicated that CD34+ cells adhere to VCAM1 through the interaction with α4ß1 integrin. Live cell imaging showed that CD34+ cells adhered around ALC-aggregates. CD34+ cells on the dish moved toward the aggregates, extending filopodia, and entered into them, which was disturbed by VCAM1 antibody. These results indicate that VCAM1-α4ß1 integrin interaction plays pivotal roles in formation of testicular interstitial tissues in vitro and also in vivo.
Assuntos
Integrina alfa4beta1/metabolismo , Testículo/citologia , Testículo/metabolismo , Molécula 1 de Adesão de Célula Vascular/metabolismo , Animais , Antígenos CD34/metabolismo , Biomarcadores , Adesão Celular/efeitos dos fármacos , Adesão Celular/genética , Células Cultivadas , Expressão Gênica , Integrina alfa4beta1/genética , Células Intersticiais do Testículo/metabolismo , Masculino , Camundongos , Organogênese/genética , Ligação Proteica , Isoformas de Proteínas , Maturidade Sexual , Esferoides Celulares , Molécula 1 de Adesão de Célula Vascular/genética , Molécula 1 de Adesão de Célula Vascular/farmacologiaRESUMO
Excessive proliferation of vascular smooth muscle cells (SMCs) remains a significant cause of in-stent restenosis. Integrins, which are heterodimeric transmembrane receptors, play a crucial role in SMC biology by binding to the extracellular matrix protein with the actin cytoskeleton within the SMC. Integrin α9 plays an important role in cell motility and autoimmune diseases; however, its role in SMC biology and remodeling remains unclear. Herein, we demonstrate that stimulated human coronary SMCs upregulate α9 expression. Targeting α9 in stimulated human coronary SMCs, using anti-integrin α9 antibody, suppresses synthetic phenotype and inhibits SMC proliferation and migration. To provide definitive evidence, we generated an SMC-specific α9-deficient mouse strain. Genetic ablation of α9 in SMCs suppressed synthetic phenotype and reduced proliferation and migration in vitro. Mechanistically, suppressed synthetic phenotype and reduced proliferation were associated with decreased focal adhesion kinase/steroid receptor coactivator signaling and downstream targets, including phosphorylated ERK, p38 MAPK, glycogen synthase kinase 3ß, and nuclear ß-catenin, with reduced transcriptional activation of ß-catenin target genes. Following vascular injury, SMC-specific α9-deficient mice or wild-type mice treated with murine anti-integrin α9 antibody exhibited reduced injury-induced neointimal hyperplasia at day 28 by limiting SMC migration and proliferation. Our findings suggest that integrin α9 regulates SMC biology, suggesting its potential therapeutic application in vascular remodeling.
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Cadeias alfa de Integrinas/metabolismo , Miócitos de Músculo Liso , Remodelação Vascular/fisiologia , Animais , Feminino , Masculino , Camundongos , Camundongos Transgênicos , Miócitos de Músculo Liso/citologia , Miócitos de Músculo Liso/metabolismo , Miócitos de Músculo Liso/fisiologia , FenótipoRESUMO
Inherent immune suppression represents a major challenge in the treatment of human cancer. The extracellular matrix molecule tenascin-C promotes cancer by multiple mechanisms, yet the roles of tenascin-C in tumor immunity are incompletely understood. Using a 4NQO-induced oral squamous cell carcinoma (OSCC) model with abundant and absent tenascin-C, we demonstrated that tenascin-C enforced an immune-suppressive lymphoid stroma via CCL21/CCR7 signaling, leading to increased metastatic tumors. Through TLR4, tenascin-C increased expression of CCR7 in CD11c+ myeloid cells. By inducing CCL21 in lymphatic endothelial cells via integrin α9ß1 and binding to CCL21, tenascin-C immobilized CD11c+ cells in the stroma. Inversion of the lymph node-to-tumor CCL21 gradient, recruitment of T regulatory cells, high expression of anti-inflammatory cytokines, and matrisomal components were hallmarks of the tenascin-C-instructed lymphoid stroma. Ablation of tenascin-C or CCR7 blockade inhibited the lymphoid immune-suppressive stromal properties, reducing tumor growth, progression, and metastasis. Thus, targeting CCR7 could be relevant in human head and neck tumors, as high tenascin-C expression and an immune-suppressive stroma correlate to poor patient survival.
Assuntos
Neoplasias Bucais/imunologia , Carcinoma de Células Escamosas de Cabeça e Pescoço/imunologia , Tenascina/imunologia , Animais , Quimiocina CCL21/imunologia , Humanos , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Neoplasias Bucais/patologia , Receptores CCR7/imunologia , Proteínas Recombinantes/farmacologia , Linfócitos T Reguladores/imunologia , Tenascina/farmacologia , Microambiente Tumoral/imunologiaRESUMO
RATIONALE: Currently, there is no effective intervention available that can reduce brain damage following reperfusion. Clinical studies suggest a positive correlation between the increased influx of neutrophils and severity of brain injury following reperfusion. Integrin α9ß1 is highly expressed on activated neutrophils and contributes to stable adhesion, but its role in stroke outcome has not been demonstrated to date. OBJECTIVE: We sought to determine the mechanistic role of myeloid-specific α9ß1 in the progression of ischemic stroke in murine models with preexisting comorbidities. METHODS AND RESULTS: We generated novel myeloid-specific α9-deficient (α9-/-) wild type (α9fl/flLysMCre+/-), hyperlipidemic (α9fl/flLysMCre+/-Apoe-/-), and aged (bone marrow chimeric) mice to evaluate stroke outcome. Susceptibility to ischemia/reperfusion injury was evaluated at 1, 7, and 28 days following reperfusion in 2 models of experimental stroke: filament and embolic. We found that peripheral neutrophils displayed elevated α9 expression following stroke. Irrespective of sex, genetic deletion of α9 in myeloid cells improved short- and long-term stroke outcomes in the wild type, hyperlipidemic, and aged mice. Improved stroke outcome and enhanced survival in myeloid-specific α9-/- mice was because of marked decrease in cerebral thromboinflammatory response as evidenced by reduced fibrin, platelet thrombi, neutrophil, NETosis, and decreased phospho-NF-κB (nuclear factor-κB), TNF (tumor necrosis factor)-α, and IL (interleukin)-1ß levels. α9-/- mice were less susceptible to FeCl3 injury-induced carotid artery thrombosis that was concomitant with improved regional cerebral blood flow following stroke as revealed by laser speckle imaging. Mechanistically, fibronectin containing extra domain A, a ligand for integrin α9, partially contributed to α9-mediated stroke exacerbation. Infusion of a specific anti-integrin α9 inhibitor into hyperlipidemic mice following reperfusion significantly reduced infarct volume and improved short- and long-term functional outcomes up to 28 days. CONCLUSIONS: We provide genetic and pharmacological evidence for the first time that targeting myeloid-specific integrin α9ß1 improves short- and long-term functional outcomes in stroke models with preexisting comorbidities by limiting cerebral thrombosis and inflammation.
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Infarto da Artéria Cerebral Média/metabolismo , Integrinas/metabolismo , Células Mieloides/metabolismo , Trombose/metabolismo , Envelhecimento/patologia , Animais , Armadilhas Extracelulares/metabolismo , Fibrina/metabolismo , Fibronectinas/metabolismo , Deleção de Genes , Hiperlipidemias/complicações , Infarto da Artéria Cerebral Média/complicações , Infarto da Artéria Cerebral Média/patologia , Inflamação , Integrinas/genética , Interleucina-1beta/metabolismo , Camundongos , NF-kappa B/metabolismo , Neutrófilos/metabolismo , Trombose/complicações , Trombose/patologia , Fator de Necrose Tumoral alfa/metabolismoRESUMO
Previously, we reported that an extracellular matrix protein, osteopontin (OPN), is involved in various autoimmune diseases using a neutralizing polyclonal antibody against OPN generated in rabbits. However, the antibody cannot be used for long-term mouse models of chronic inflammatory disease because of the induction of antibodies against anti-OPN rabbit IgG. In this study, we generated a new antibody, anti-mouse OPN mouse IgG (35B6). 35B6 inhibited the cell adhesion of mouse and human OPN to Chinese Hamster Ovary (CHO) cells or CHO cells expressing α4 or α9 integrin. It was reported that OPN is highly expressed and has an important role in a chronic liver disease, non-alcoholic steatohepatitis (NASH). 35B6 injection twice a week for 8 weeks attenuated liver inflammation and fibrosis in a NASH mouse model, suggesting 35B6 is beneficial for the treatment of NASH. 35B6 was preferable to the rabbit anti-OPN antibody for investigating the in vivo function of OPN in mouse models of long-term disease.
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Evidence suggests that neutrophils contribute to thrombosis via several mechanisms, including neutrophil extracellular traps (NETs) formation. Integrin α9ß1 is highly expressed on neutrophils when compared with monocytes. It undergoes affinity upregulation on neutrophil activation, and stabilizes adhesion to the activated endothelium. The role of integrin α9 in arterial thrombosis remains unexplored. We generated novel myeloid cell-specific integrin α9-/- mice (α9fl/flLysMCre+) to study the role of integrin α9 in arterial thrombosis. α9fl/fl littermates were used as controls. We report that α9fl/flLysMCre+ mice were less susceptible to arterial thrombosis in ferric chloride (FeCl3) and laser injury-induced thrombosis models with unaltered hemostasis. Neutrophil elastase-positive cells were significantly reduced in α9fl/flLysMCre+ mice concomitant with reduction in neutrophil count, myeloperoxidase levels, and red blood cells in the FeCl3 injury-induced carotid thrombus. The percentage of cells releasing NETs was significantly reduced in α9fl/flLysMCre+ mouse neutrophils stimulated with thrombin-activated platelets. Furthermore, we found a significant decrease in neutrophil-mediated platelet aggregation and cathepsin-G secretion in α9fl/flLysMCre+ mice. Transfusion of α9fl/fl neutrophils in α9fl/flLysMCre+ mice restored thrombosis similar to α9fl/fl mice. Treatment of wild-type mice with anti-integrin α9 antibody inhibited arterial thrombosis. This study identifies the potential role of integrin α9 in modulating arterial thrombosis.
Assuntos
Integrinas/antagonistas & inibidores , Integrinas/metabolismo , Células Mieloides/metabolismo , Trombose/metabolismo , Animais , Gerenciamento Clínico , Suscetibilidade a Doenças , Armadilhas Extracelulares/imunologia , Armadilhas Extracelulares/metabolismo , Camundongos , Camundongos Knockout , Células Mieloides/imunologia , Ativação de Neutrófilo/imunologia , Neutrófilos/imunologia , Neutrófilos/metabolismo , Agregação Plaquetária , Trombose/etiologia , Trombose/prevenção & controleRESUMO
The extracellular matrix protein nephronectin (Npnt) is known to be critical for kidney development, but its function in inflammatory diseases is unknown. Here, we developed a new enzyme-linked immunosorbent assay system to detect Npnt in various autoimmune diseases, which revealed that plasma Npnt levels are increased in various mouse autoimmune models. We also report that antibodies against the α8ß1 integrin-binding region of Npnt protect mice from anti-type II collagen-induced arthritis, suggesting that Npnt may be a potential therapeutic target molecule for the prevention of autoimmune arthritis.
Assuntos
Anticorpos/imunologia , Anticorpos/uso terapêutico , Artrite Experimental/tratamento farmacológico , Artrite Experimental/imunologia , Colágeno Tipo II/imunologia , Proteínas da Matriz Extracelular/antagonistas & inibidores , Proteínas da Matriz Extracelular/imunologia , Animais , Artrite Experimental/metabolismo , Células Cultivadas , Ensaio de Imunoadsorção Enzimática , Proteínas da Matriz Extracelular/metabolismo , Humanos , Camundongos , Camundongos Endogâmicos BALB C , Camundongos Endogâmicos C57BL , Células NIH 3T3 , Ratos , Ratos Sprague-DawleyRESUMO
Silicosis is a typical form of pneumoconiosis and is characterized as a type of lung fibrosis. Silica particles are captured and recognized upon by alveolar macrophages via the macrophage receptor with collagenous structure (MARCO) scavenger receptor, and thereafter the inflammasome is activated. Thereafter, various chemokines/cytokines play their roles to eventually form fibrosis. Additionally, silica particles chronically activate T helper cells which sets the background for the formation of silicosis-associated autoimmune disturbances. The occurrence and progression of lung fibrosis, the extracellular matrix-related molecules such as integrins and their ligands including fibronectin, vitronectin, laminin, and collagens, all play important roles. Here, the roles of these molecules in silicosis-related lung fibrosis are reviewed from the literature. Additionally, the measurement of serum nephronectin (Npnt), a new member of the integrin family of ligands, is discussed, together with investigations attempting to delineate the role of Npnt in silica-induced lung fibrosis. Serum Npnt was found to be higher in silicosis patients compared to healthy volunteers and seems to play a role in the progression of fibrosis with other cytokines. Therefore, serum Npnt levels may be employed as a suitable marker to monitor the progression of fibrosis in silicosis patients.
Assuntos
Proteínas da Matriz Extracelular/sangue , Doenças Profissionais/sangue , Fibrose Pulmonar/sangue , Silicose/sangue , Animais , Humanos , Inflamação/sangue , Inflamação/etiologia , Inflamação/fisiopatologia , Pulmão/fisiopatologia , Doenças Profissionais/etiologia , Doenças Profissionais/fisiopatologia , Fibrose Pulmonar/etiologia , Dióxido de Silício/efeitos adversos , Silicose/etiologia , Silicose/fisiopatologiaRESUMO
Adhesion of cells to extracellular matrix proteins through integrins expressed on the cell surface is important for cell adhesion/motility, survival, and differentiation. Recently, α9ß1 integrin was reported to be important for the development of autoimmune diseases including rheumatoid arthritis, multiple sclerosis, and their murine models. In addition, ligands for α9ß1 integrin, such as osteopontin and tenascin-C, are well established as key regulators of autoimmune diseases. Therefore, this review focused on the role of interactions between α9ß1 integrin and its ligands in the development of autoimmune diseases.
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The integrin α9ß1 is a key receptor involved in the development of autoimmune diseases. However, the detailed mechanism for the association of α9ß1 integrin with its ligands remains unclear. In this study, we introduce XCL1/lymphotactin, a member of the chemokine family, as a novel ligand for α9 integrin. Using α9 integrin-overexpressing NIH3T3 cells and endogenously α9 integrin-expressing human rhabdomyosarcoma cells, the interaction between XCL1 and α9 integrin was confirmed by pull-down assays. XCL1 enhanced α9 integrin-dependent cell migration of these cells, thus acting on α9 integrin as a chemoattractant. We also analyzed the in vivo function of XCL1 in the development of anti-type II collagen Ab-induced inflammatory arthritis (CAIA) in BALB/c mice and experimental autoimmune encephalomyelitis in C57BL/6 mice, because α9 integrin is involved in these autoimmune disease models. In CAIA, recombinant XCL1 aggravated the disease and this exacerbation was inhibited by an anti-α9 integrin Ab. An XCL1-neutralizing Ab produced in this study also ameliorated CAIA. Furthermore, the XCL1-neutralizing Ab abrogated the disease progression in experimental autoimmune encephalomyelitis. Therefore, to our knowledge this study provides the first in vitro and in vivo evidence that the interaction between XCL1 and α9 integrin has an important role for autoimmune diseases.
Assuntos
Quimiocinas C/imunologia , Quimiocinas C/metabolismo , Encefalomielite Autoimune Experimental/imunologia , Cadeias alfa de Integrinas/metabolismo , Animais , Anticorpos Neutralizantes/imunologia , Artrite Experimental/imunologia , Adesão Celular , Movimento Celular , Modelos Animais de Doenças , Encefalomielite Autoimune Experimental/fisiopatologia , Encefalomielite Autoimune Experimental/terapia , Cadeias alfa de Integrinas/imunologia , Ligantes , Camundongos , Camundongos Endogâmicos C57BL , Células NIH 3T3 , Rabdomiossarcoma/imunologiaRESUMO
We recently reported that Lactobacillus helveticus SBT2171 (LH2171) inhibited the proliferation and inflammatory cytokine production of primary immune cells in vitro, and alleviated collagen-induced arthritis (CIA) in mice, a model of human rheumatoid arthritis (RA). In this study, we newly investigated whether LH2171 could relieve the severity of experimental autoimmune encephalomyelitis (EAE), a murine model of multiple sclerosis (MS), which is an autoimmune disease, but develop the symptoms by different mechanisms from RA. In MS and EAE, main cause of the disease is the abnormality in CD4+ T cell immunity, whereas in RA and CIA, is that in antibody-mediated immunity. The intraperitoneal administration of LH2171 significantly decreased the incidence and clinical score of EAE in mice. LH2171 also reduced the numbers of pathogenic immune cells, especially Th17 cells, in the spinal cord at the peak stage of disease severity. Interestingly, before the onset of EAE, LH2171 administration remarkably decreased the ratio of Th17 cells to CD4+ T cells in the inguinal lymph nodes (LNs), where pathogenic immune cells are activated to infiltrate the central nervous system, including the spinal cord. Furthermore, the expression of interleukin (IL)-6, an inflammatory cytokine essential for Th17 differentiation, decreased in the LNs of LH2171-administered mice. Moreover, LH2171 significantly inhibited IL-6 production in vitro from both DC2.4 and RAW264.7 cells, model cell lines of antigen-presenting cells. These findings suggest that LH2171 might down-regulate IL-6 production and the subsequent Th17 differentiation and spinal cord infiltration, consequently alleviating EAE symptoms.
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Signal transducer and activator of transcription 3 (STAT3) is involved in cell proliferation, differentiation, and cell survival during immune responses, hematopoiesis, neurogenesis, and other biological processes. STAT3 activity is regulated by a variety of mechanisms, including phosphorylation and nuclear translocation. To clarify the molecular mechanisms underlying the regulation of STAT3 activity, we performed yeast two-hybrid screening. We identified ARL3 (ADP-ribosylation factor-like 3) as a novel STAT3-binding partner. ARL3 recognizes the DNA-binding domain as well as the C-terminal region of STAT3 in vivo, and their binding was the strongest when both proteins were activated. Importantly, small interfering RNA-mediated reduction of endogenous ARL3 expression decreased IL-6-induced tyrosine phosphorylation, nuclear accumulation, and transcriptional activity of STAT3. These results indicate that ARL3 interacts with STAT3 and regulates the transcriptional activation of STAT3 by influencing its nuclear accumulation of STAT3.
Assuntos
Fatores de Ribosilação do ADP/metabolismo , Núcleo Celular/metabolismo , Fator de Transcrição STAT3/metabolismo , Fatores de Ribosilação do ADP/genética , Transporte Ativo do Núcleo Celular/efeitos dos fármacos , Transporte Ativo do Núcleo Celular/genética , Núcleo Celular/genética , Regulação da Expressão Gênica/efeitos dos fármacos , Células HeLa , Humanos , Interleucina-6/farmacologia , Fosforilação/efeitos dos fármacos , Fosforilação/genética , Ligação Proteica/efeitos dos fármacos , Ligação Proteica/genética , Fator de Transcrição STAT3/genéticaRESUMO
In psoriasis lesions, a diverse mixture of cytokines is up-regulated that influence each other generating a complex inflammatory situation. Although this is the case, the inhibition of IL-17A alone showed unprecedented clinical results in patients, indicating that IL-17A is a critical inducer of psoriasis pathogenesis. To elucidate IL-17A-driven keratinocyte-intrinsic signaling pathways, we treated monolayers of normal human epidermal keratinocytes in vitro with a mixture of six cytokines (IL-17A, TNF-α, IL-17C, IL-22, IL-36γ and IFN-γ) involved in psoriasis to mimic the inflammatory milieu in psoriasis lesions. Microarray and gene set enrichment analysis revealed that this cytokine mixture induced similar gene expression changes with the previous transcriptome studies using psoriasis lesions. Importantly, we identified a set of IL-17A-regulated genes in keratinocytes, which recapitulate typical psoriasis genes exemplified by DEFB4A, S100A7, IL19 and CSF3, based on the differences in the expression profiles of cells stimulated with six cytokines versus cells stimulated with only five cytokines lacking IL-17A. Furthermore, a specific IL-17A-induced gene, NFKBIZ, which encodes IκB-ζ, a transcriptional regulator for NF-κB, was demonstrated to have a significant role for IL-17A-induced gene expression. Thus, we present novel in vitro data from normal human keratinocytes that would help elucidating the IL-17A-driven keratinocyte activation in psoriasis.
Assuntos
Regulação da Expressão Gênica/imunologia , Proteínas I-kappa B/imunologia , Interleucina-17/imunologia , Queratinócitos/imunologia , Proteínas Nucleares/imunologia , Psoríase/imunologia , Proteínas Adaptadoras de Transdução de Sinal , Linhagem Celular , Humanos , Queratinócitos/patologia , Psoríase/patologiaRESUMO
Epstein-Barr virus (EBV)-encoded latent membrane protein-1 (LMP1) plays pathogenic roles in EBV-related diseases. Thus, host cells employ several mechanisms to regulate LMP1 functions, and we previously reported possible regulation by signal transducing adaptor protein-2 as well as BS69. Here, we found that caspase-3 mainly degraded LMP1 proteins in HeLa cells, leading to decreased NF-κB and STAT3 activation. Caspase-3 cleaved the consensus DNTD sequences in the CTAR3 region of LMP1. Of importance, LMP1 expression strongly enhanced caspase-3 activity. Taken together, the reduction of LMP1 protein levels by caspases is likely to be a newly identified host defense against EBV infection.
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Caspase 3/metabolismo , Proteínas da Matriz Viral/metabolismo , Caspase 3/genética , Inibidores de Caspase/farmacologia , Ativação Enzimática , Expressão Gênica , Genes Virais , Células HeLa , Herpesvirus Humano 4/genética , Herpesvirus Humano 4/patogenicidade , Herpesvirus Humano 4/fisiologia , Interações Hospedeiro-Patógeno , Humanos , NF-kappa B/metabolismo , Oligopeptídeos/farmacologia , Estrutura Terciária de Proteína , Proteólise , RNA Interferente Pequeno/genética , Proteínas Recombinantes/química , Proteínas Recombinantes/genética , Proteínas Recombinantes/metabolismo , Fator de Transcrição STAT3/metabolismo , Proteínas da Matriz Viral/química , Proteínas da Matriz Viral/genéticaRESUMO
HLA-G is involved in maternal-fetal immune tolerance and is reported to be a natural tolerogenic molecule. Seven-spliced isoforms including dimeric and ß2m-free forms have been identified. The major isoform, HLA-G1 (and its soluble type HLA-G5), binds to the inhibitory immune receptors, leukocyte immunoglobulin (Ig)-like receptor (LILR) B1 and LILRB2. We previously reported that HLA-G1 also binds to paired Ig-like receptor (PIR)-B, a mouse homolog of LILRBs, and had a significant immunosuppressive effect in collagen-induced arthritis (CIA) mice. Although HLA-G2 and its soluble form HLA-G6 bind specifically to LILRB2, its functional characteristics are largely unknown. In this study, we report the significant immunosuppressive effect of HLA-G2 dimer in CIA mice. Surface plasmon resonance analysis revealed a specific interaction of HLA-G2 with PIR-B. CIA mice were administered HLA-G2 protein subcutaneously once in the left footpad and clinical severity was evaluated in a double-blind study. A single administration of HLA-G2 maintained a suppressive effect for over 1month. These results suggested that the HLA-G2 protein might be a useful biopharmaceutical for the treatment of rheumatoid arthritis by binding to inhibitory PIR-B.
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Artrite Experimental/tratamento farmacológico , Artrite Reumatoide/tratamento farmacológico , Antígenos HLA-G/uso terapêutico , Animais , Dimerização , Progressão da Doença , Antígenos HLA-G/genética , Antígenos HLA-G/metabolismo , Humanos , Terapia de Imunossupressão , Masculino , Camundongos , Camundongos Endogâmicos DBA , Domínios Proteicos/genética , Engenharia de Proteínas , Receptores Imunológicos/metabolismo , Deleção de Sequência/genéticaRESUMO
Cyclosporin A (CsA) is effective at reducing pathogenic immune responses, but upon withdrawal of CsA the immune response often "rebounds" resulting in a relapse or exacerbation of disease. The mechanisms, cells and cytokines involved in the relapse or exacerbation after CsA withdrawal are unknown. We hypothesized that CsA withdrawal induces IL-17 production that could be responsible for relapse, and examined the effect of anti-IL-17A antibody on relapse induced after CsA withdrawal in mouse experimental autoimmune encephalomyelitis (EAE). CsA treatment markedly decreased the EAE disease score during the first episode, but augmented disease severity after CsA withdrawal, compared to untreated mice. After discontinuation of CsA the production of IL-17A was increased and the severity of relapse in EAE was reduced by treatment with anti-IL-17A antibody. These results suggest that the resumption of T cell immune responses after CsA withdrawal leads to a burst of IL-17A production that is at least partially responsible for relapse in EAE mice.
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Signal transducers and activators of transcription (STATs) mediate essential signals for various biological processes, including immune responses, hematopoiesis, and neurogenesis. STAT3, for example, is involved in the pathogenesis of various human diseases, including cancers, autoimmune and inflammatory disorders. STAT3 activation is therefore tightly regulated at multiple levels to prevent these pathological conditions. A number of proteins have been reported to associate with STAT3 and regulate its activity. These STAT3-interacting proteins function to modulate STAT3-mediated signaling at various steps and mediate the crosstalk of STAT3 with other cellular signaling pathways. This article reviews the roles of novel STAT3 binding partners such as DAXX, zipper-interacting protein kinase, Krüppel-associated box-associated protein 1, Y14, PDZ and LIM domain 2 and signal transducing adaptor protein-2, in the regulation of STAT3-mediated signaling.
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Kaposi's sarcoma-associated herpesvirus (KSHV)-encoded latency-associated nuclear antigen (LANA), which interacts with cellular proteins, plays a central role in modification of viral and/or cellular gene expression. Here, we show that LANA associates with glucocorticoid receptor (GR), and that LANA enhances the transcriptional activity of GR. Co-immunoprecipitation revealed a physical interaction between LANA and GR in transiently transfected 293T and HeLa cells. In human B-lymphoma cells, LANA overexpression enhanced GR activity and cell growth suppression following glucocorticoid stimulation. Furthermore, confocal microscopy showed that activated GR was bound to LANA and accumulated in the nucleus, leading to an increase in binding of activated GR to the glucocorticoid response element of target genes. Taken together, KSHV-derived LANA acts as a transcriptional co-activator of GR. Our results might suggest a careful use of glucocorticoids in the treatment of patients with KSHV-related malignancies such as Kaposi's sarcoma, primary effusion lymphoma, and multicentric Castleman disease.