RESUMO
Duchenne muscular dystrophy (DMD) is an X-linked recessive disease characterized by skeletal muscle instability, progressive muscle wasting, and fibrosis. A major driver of DMD pathology stems from aberrant upregulation of transforming growth factor ß (TGFß) signaling. In this report, we investigated the major transducers of TGFß signaling, i.e., receptor Smads (R-Smads), in DMD patient skeletal muscle and observed a 48-fold increase in Smad8 mRNA. Smad1, Smad2, Smad3, and Smad5 mRNA were only minimally increased. A similar pattern was observed in the muscle from the mdx5cv mouse. Western blot analysis showed upregulation of phosphorylated Smad1, Smad5, and Smad8 compared to total Smad indicating activation of this pathway. In parallel, we observed a profound diminishment of muscle-enriched microRNAs (myomiRs): miR-1, miR-133a, and miR-133b. The pattern of Smad8 induction and myomiR suppression was recapitulated in C2C12 muscle cells after stimulation with bone morphogenetic protein 4 (BMP4), a signaling factor that we found upregulated in DMD muscle. Silencing Smad8 in C2C12 myoblasts derepressed myomiRs and promoted myoblast differentiation; there was also a concomitant upregulation of myogenic regulatory factors (myogenin and myocyte enhancer factor 2D) and suppression of a pro-inflammatory cytokine (interleukin-6). Our data suggest that Smad8 is a negative regulator of miR-1, miR-133a, and miR-133b in muscle cells and that the BMP4-Smad8 axis is a driver of dystrophic pathology in DMD.
Assuntos
MicroRNAs , Distrofia Muscular de Duchenne , Proteína Smad8 , Animais , Camundongos , Camundongos Endogâmicos mdx , MicroRNAs/genética , MicroRNAs/metabolismo , Músculo Esquelético/metabolismo , Distrofia Muscular de Duchenne/metabolismo , RNA Mensageiro/metabolismo , Proteína Smad8/genética , Proteína Smad8/metabolismo , Fator de Crescimento Transformador beta/metabolismoRESUMO
BACKGROUND: Follicular regulatory T (TFR) cells are essential for the regulation of germinal center (GC) response and humoral self-tolerance. Dysregulated follicular helper T (TFH) cell-GC-antibody (Ab) response secondary to dysfunctional TFR cells is the root of an array of autoimmune disorders. The contribution of TFR cells to the pathogenesis of multiple sclerosis (MS) and murine experimental autoimmune encephalomyelitis (EAE) remains largely unclear. METHODS: To determine the impact of dysregulated regulatory T cells (Tregs), TFR cells, and Ab responses on EAE, we compared the MOG-induced EAE in mice with a FoxP3-specific ablation of the transcription factor Blimp1 to control mice. In vitro co-culture assays were used to understand how Tregs and Ab regulate the activity of microglia and central nervous system (CNS)-infiltrating myeloid cells. RESULTS: Mice with a FoxP3-specific deletion of Blimp1 developed severe EAE and failed to recover compared to control mice, reflecting conversion of Tregs into interleukin (IL)-17A/granulocyte-macrophage colony-stimulating factor (GM-CSF)-producing effector T cells associated with increased TFH-Ab responses, more IgE deposition in the CNS, and inability to regulate CNS CD11b+ myeloid cells. Notably, serum IgE titers were positively correlated with EAE scores, and culture of CNS CD11b+ cells with sera from these EAE mice enhanced their activation, while transfer of Blimp1-deficient TFR cells promoted Ab production, activation of CNS CD11b+ cells, and EAE. CONCLUSIONS: Blimp1 is essential for the maintenance of TFR cells and Ab responses in EAE. Dysregulated TFR cells and Ab responses promote CNS autoimmunity.
Assuntos
Formação de Anticorpos/imunologia , Encefalomielite Autoimune Experimental/imunologia , Fator 1 de Ligação ao Domínio I Regulador Positivo/imunologia , Linfócitos T Reguladores/imunologia , Animais , Autoimunidade/imunologia , Diferenciação Celular/imunologia , Centro Germinativo , Camundongos , Camundongos Endogâmicos C57BLRESUMO
Proteinaceous inclusions in neurons, composed primarily of α-synuclein, define the pathology in several neurodegenerative disorders. Neurons can internalize α-synuclein fibrils that can seed new inclusions from endogenously expressed α-synuclein. The factors contributing to the spread of pathology and subsequent neurodegeneration are not fully understood, and different compositions and concentrations of fibrils have been used in different hosts. Here, we systematically vary the concentration and length of well-characterized α-synuclein fibrils and determine their relative ability to induce inclusions and neurodegeneration in different hosts (primary neurons, C57BL/6J and C3H/HeJ mice, and Sprague Dawley rats). Using dynamic-light scattering profiles and other measurements to determine fibril length and concentration, we find that femptomolar concentrations of fibrils are sufficient to induce robust inclusions in primary neurons. However, a narrow and non-linear dynamic range characterizes fibril-mediated inclusion induction in axons and the soma. In mice, the C3H/HeJ strain is more sensitive to fibril exposures than C57BL/6J counterparts, with more inclusions and dopaminergic neurodegeneration. In rats, injection of fibrils into the substantia nigra pars compacta (SNpc) results in similar inclusion spread and dopaminergic neurodegeneration as injection of the fibrils into the dorsal striatum, with prominent inclusion spread to the amygdala and several other brain areas. Inclusion spread, particularly from the SNpc to the striatum, positively correlates with dopaminergic neurodegeneration. These results define biophysical characteristics of α-synuclein fibrils that induce inclusions and neurodegeneration both in vitro and in vivo, and suggest that inclusion spread in the brain may be promoted by a loss of neurons.
Assuntos
Dopamina/metabolismo , Corpos de Inclusão/patologia , Doenças Neurodegenerativas/metabolismo , alfa-Sinucleína/metabolismo , alfa-Sinucleína/toxicidade , Acetilcolinesterase/metabolismo , Animais , Corpo Estriado/efeitos dos fármacos , Corpo Estriado/patologia , Modelos Animais de Doenças , Relação Dose-Resposta a Droga , Humanos , Corpos de Inclusão/efeitos dos fármacos , Corpos de Inclusão/ultraestrutura , Camundongos , Camundongos Endogâmicos C3H , Camundongos Endogâmicos C57BL , Microscopia Eletrônica de Transmissão , Doenças Neurodegenerativas/induzido quimicamente , Doenças Neurodegenerativas/patologia , Neurônios/efeitos dos fármacos , Neurônios/metabolismo , Neurônios/patologia , Neurônios/ultraestrutura , Fosfopiruvato Hidratase/metabolismo , Ratos , Ratos Sprague-Dawley , Substância Negra/efeitos dos fármacos , Substância Negra/metabolismo , Substância Negra/patologia , Tirosina 3-Mono-Oxigenase/metabolismo , alfa-Sinucleína/ultraestrutura , Proteínas tau/metabolismoRESUMO
Mutations in the leucine-rich repeat kinase 2 (LRRK2) gene are the most common known genetic cause of Parkinson's disease, and LRRK2 is also linked to Crohn's and Hansen's disease. LRRK2 is expressed in many organs in mammals but is particularly abundant in the kidney. We find that LRRK2 protein is predominantly localized to collecting duct cells in the rat kidney, with much lower expression in other kidney cells. While genetic knockout (KO) of LRRK2 expression is well-tolerated in mice and rats, a unique age-dependent pathology develops in the kidney. The cortex and medulla of LRRK2 KO rat kidneys become darkly pigmented in early adulthood, yet aged animals display no overt signs of kidney failure. Accompanying the dark pigment we find substantial macrophage infiltration in LRRK2 KO kidneys, suggesting the presence of chronic inflammation that may predispose to kidney disease. Unexpectedly, the dark kidneys of the LRRK2 KO rats are highly resistant to rhabdomyolysis-induced acute kidney injury compared with wild-type rats. Biochemical profiling of the LRRK2 KO kidneys using immunohistochemistry, proteomic and lipidomic analyses show a massive accumulation of hemoglobin and lipofuscin in renal tubules that account for the pigmentation. The proximal tubules demonstrate a corresponding up-regulation of the cytoprotective protein heme oxygenase-1 (HO-1) which is capable of mitigating acute kidney injury. The unusual kidney pathology of LRRK2 KO rats highlights several novel physiological roles for LRRK2 and provides indirect evidence for HO-1 expression as a protective mechanism in acute kidney injury in LRRK2 deficiency.
Assuntos
Nefropatias/genética , Proteínas Serina-Treonina Quinases/genética , Rabdomiólise/genética , Animais , Citoproteção , Células Epiteliais/metabolismo , Predisposição Genética para Doença , Heme Oxigenase (Desciclizante)/genética , Heme Oxigenase (Desciclizante)/metabolismo , Nefropatias/etiologia , Túbulos Renais Proximais/metabolismo , Túbulos Renais Proximais/patologia , Serina-Treonina Proteína Quinase-2 com Repetições Ricas em Leucina , Masculino , Proteínas Serina-Treonina Quinases/deficiência , Proteínas Serina-Treonina Quinases/metabolismo , Proteômica , Ratos , Rabdomiólise/complicações , Regulação para CimaRESUMO
Therapeutic approaches to slow or block the progression of Parkinson disease (PD) do not exist. Genetic and biochemical studies implicate α-synuclein and leucine-rich repeat kinase 2 (LRRK2) in late-onset PD. LRRK2 kinase activity has been linked to neurodegenerative pathways. However, the therapeutic potential of LRRK2 kinase inhibitors is not clear because significant toxicities have been associated with one class of LRRK2 kinase inhibitors. Furthermore, LRRK2 kinase inhibitors have not been tested previously for efficacy in models of α-synuclein-induced neurodegeneration. To better understand the therapeutic potential of LRRK2 kinase inhibition in PD, we evaluated the tolerability and efficacy of a LRRK2 kinase inhibitor, PF-06447475, in preventing α-synuclein-induced neurodegeneration in rats. Both wild-type rats as well as transgenic G2019S-LRRK2 rats were injected intracranially with adeno-associated viral vectors expressing human α-synuclein in the substantia nigra. Rats were treated with PF-06447475 or a control compound for 4 weeks post-viral transduction. We found that rats expressing G2019S-LRRK2 have exacerbated dopaminergic neurodegeneration and inflammation in response to the overexpression of α-synuclein. Both neurodegeneration and neuroinflammation associated with G2019S-LRRK2 expression were mitigated by LRRK2 kinase inhibition. Furthermore, PF-06447475 provided neuroprotection in wild-type rats. We could not detect adverse pathological indications in the lung, kidney, or liver of rats treated with PF-06447475. These results demonstrate that pharmacological inhibition of LRRK2 is well tolerated for a 4-week period of time in rats and can counteract dopaminergic neurodegeneration caused by acute α-synuclein overexpression.
Assuntos
Antiparkinsonianos/farmacologia , Doença de Parkinson/tratamento farmacológico , Inibidores de Proteínas Quinases/farmacologia , Proteínas Serina-Treonina Quinases/antagonistas & inibidores , Pirimidinas/farmacologia , Pirróis/farmacologia , alfa-Sinucleína/genética , Animais , Dependovirus/genética , Modelos Animais de Doenças , Feminino , Regulação da Expressão Gênica/efeitos dos fármacos , Vetores Genéticos , Humanos , Injeções Intraventriculares , Serina-Treonina Proteína Quinase-2 com Repetições Ricas em Leucina , Masculino , Doença de Parkinson/genética , Doença de Parkinson/metabolismo , Doença de Parkinson/patologia , Proteínas Serina-Treonina Quinases/genética , Proteínas Serina-Treonina Quinases/metabolismo , Ratos , Ratos Sprague-Dawley , Transdução de Sinais , Substância Negra/efeitos dos fármacos , Substância Negra/metabolismo , Substância Negra/patologia , alfa-Sinucleína/metabolismoRESUMO
Intercellular adhesion molecule-1 (ICAM-1) plays an important role in leukocyte trafficking, induction of cellular immune responses, and immunological synapse formation. As a member of the immunoglobulin superfamily of adhesion proteins, ICAM-1 is composed of repeating Ig-like domains, a transmembrane domain, and short cytoplasmic tail that participates in intracellular signaling events. At least seven ICAM-1 protein isoforms are generated by alternative splicing, however little is known regarding their immunobiology. We have previously shown using different lines of ICAM-1 mutant mice (Icam1(tm1Jcgr) and Icam1(tm1Bay) ) that expression of alternatively spliced ICAM-1 isoforms can significantly influence the disease course during the development of EAE. In this study, we show using a newly developed transgenic mouse (CD2-Icam1(D4del) /Icam1(null) ) that T-cell-specific expression of a single ICAM-1 isoform composed of Ig domains 1, 2, 3, and 5 can mediate the initiation and progression of EAE. Our results indicate that the ICAM-1 isoform lacking Ig domain 4 can drive pathogenesis in demyelinating disease and may be a novel therapeutic target for treating multiple sclerosis.
Assuntos
Encefalomielite Autoimune Experimental/imunologia , Molécula 1 de Adesão Intercelular/imunologia , Linfócitos T/imunologia , Transferência Adotiva , Processamento Alternativo , Animais , Sítios de Ligação/genética , Sítios de Ligação/imunologia , Western Blotting , Encefalomielite Autoimune Experimental/genética , Encefalomielite Autoimune Experimental/metabolismo , Citometria de Fluxo , Células HEK293 , Humanos , Molécula 1 de Adesão Intercelular/genética , Molécula 1 de Adesão Intercelular/metabolismo , Camundongos , Camundongos Knockout , Camundongos Transgênicos , Isoformas de Proteínas/genética , Isoformas de Proteínas/imunologia , Isoformas de Proteínas/metabolismo , Linfócitos T/metabolismo , Linfócitos T/transplanteRESUMO
Duchenne muscular dystrophy (DMD) is a fatal X-linked recessive disease due to loss-of-function mutations in the DYSTROPHIN gene. DMD-related skeletal muscle wasting is typified by an aberrant immune response involving upregulation of TGFß family of cytokines. We previously demonstrated that bone morphogenetic protein 4 (BMP4) is increased in DMD and BMP4 stimulation induces a 20-fold upregulation of Smad8 transcription. However, the role of BMP4 in severely affected DMD skeletal muscle is unknown. We hypothesized that transcriptomic signatures in severely affected human DMD skeletal muscle are driven by BMP4 signaling. Transcriptomes from skeletal muscle biopsies of late-stage DMD vs. non-DMD controls and C2C12 muscle cells with or without BMP4 stimulation were generated by RNA-Seq and analyzed for single transcript differential expression as well as by Ingenuity Pathway Analysis and weighted gene co-expression network analyses. A total of 2,328 and 5,291 transcripts in the human muscle and C2C12 muscle cells, respectively, were differentially expressed. We identified an overlapping molecular signature of 1,027 genes dysregulated in DMD muscle that were induced in BMP4-stimulated C2C12 muscle cells. Highly upregulated DMD transcripts that overlapped with BMP4-stimulated C2C12 muscle cells included ADAMTS3, HCAR2, SERPING1, SMAD8 , and UNC13C. The DMD transcriptome was characterized by dysregulation of pathways involving immune function, extracellular matrix remodeling, and metabolic/mitochondrial function. In summary, we define a late-stage DMD skeletal muscle transcriptome that substantially overlaps with the BMP4-induced molecular signature in C2C12 muscle cells. This supports BMP4 as a disease-driving regulator of transcriptomic changes in late-stage DMD skeletal muscle and expands our understanding of the evolution of dystrophic signaling pathways and their associated gene networks that could be explored for therapeutic development.
RESUMO
Cerebral malaria is the most severe complication of Plasmodium falciparum infection and accounts for a large number of malaria fatalities worldwide. Recent studies demonstrated that C5(-/-) mice are resistant to experimental cerebral malaria (ECM) and suggested that protection was due to loss of C5a-induced inflammation. Surprisingly, we observed that C5aR(-/-) mice were fully susceptible to disease, indicating that C5a is not required for ECM. C3aR(-/-) and C3aR(-/-) × C5aR(-/-) mice were equally susceptible to ECM as were wild-type mice, indicating that neither complement anaphylatoxin receptor is critical for ECM development. In contrast, C9 deposition in the brains of mice with ECM suggested an important role for the terminal complement pathway. Treatment with anti-C9 Ab significantly increased survival time and reduced mortality in ECM. Our data indicate that protection from ECM in C5(-/-) mice is mediated through inhibition of membrane attack complex formation and not through C5a-induced inflammation.
Assuntos
Complexo de Ataque à Membrana do Sistema Complemento/fisiologia , Malária Cerebral/etiologia , Animais , Encéfalo/imunologia , Complemento C5a/fisiologia , Complemento C9/antagonistas & inibidores , Complexo de Ataque à Membrana do Sistema Complemento/antagonistas & inibidores , Suscetibilidade a Doenças , Inflamação , Malária Cerebral/imunologia , Camundongos , Camundongos Knockout , Receptor da Anafilatoxina C5a , Receptores de Complemento , Taxa de SobrevidaRESUMO
OBJECTIVE: Colon cancer (CC) shows a gradual increasing incidence in recent years, and chemotherapy is a frequently adopted treatment for patients with middle or advanced colon cancer (ACC), but it lacks prognostic markers after CC. METHODS: The changes of lncRNA CASC9 in 58 patients with CC were determined using a real-time quantitative PCR (qRT-PCR) assay before and after chemotherapy, and the correlation of serum lncRNA CASC9 with efficacy of FOLFOX4 regimen (oxaliplatin + calcium folinate + fluorouracil) was analyzed. The patients were followed up to understand the association of lncRNA CASC9 with overall survival (OS) and progression-free survival (PFS). RESULTS: Patients with CC showed notably higher lncRNA CASC9 expression than controls, and lncRNA CASC9 presented an association with the clinical stage of the patients. In addition, lncRNA CASC9 demonstrated a clinical value in predicting efficacy on patients and acted as one independent prognostic factor for PFS in patients with ACC. CONCLUSIONS: With increased expression of serum lncRNA CASC9, patients with ACC suffered an unfavorable chemotherapy effect. In addition, serum lncRNA CASC9 is a promising sensitive indicator for prediction of ACC and is related to the clinical efficacy and prognosis of patients.
RESUMO
Complement per se has been shown to play an important role in demyelinating disease but controversy remains regarding the role of C3 in the development and progression of experimental autoimmune encephalomyelitis (EAE), the animal model for multiple sclerosis. In this study, we used C3(-/-) mice to confirm previous findings that C3 is required for full development of EAE. Furthermore, C3(+/-) mice (with serum C3 levels 50% that of wild-type mice) developed EAE with a severity intermediate between wild-type and C3(-/-) mice. Importantly transfer of wild-type encephalitogenic T cells to C3(-/-) mice resulted in attenuated EAE. C3(-/-) mice with EAE had fewer CD4(+) and CD8(+) T cells in the CNS and 50% fewer of these cells produced IFN-gamma compared to wild-type mice. When treated with anti-CD3 antibody, CD4(+) T cells from wild-type and C3(-/-) mice had similar activation profiles as judged by IFN-gamma production and CD25 and CD69 expression, indicating there is no gross or intrinsic defect in T cells from C3(-/-) mice. T cells from primed C3(-/-) mice proliferated comparably to that of control T cells on re-stimulation with MOG peptide. Our results confirm a requirement for C3 for maximal development of EAE and suggest that receptors for C3-derived activation fragments might be a viable therapeutic target for prevention and treatment demyelinating disease.
Assuntos
Complemento C3/fisiologia , Encefalomielite Autoimune Experimental/etiologia , Animais , Proliferação de Células , Complemento C3/deficiência , Progressão da Doença , Ativação Linfocitária , Camundongos , Camundongos Knockout , Linfócitos T/citologia , Linfócitos T/imunologia , Linfócitos T/transplanteRESUMO
Carboxypeptidase N (CPN) is a member of the carboxypeptidase family of enzymes that cleave carboxy-terminal lysine and arginine residues from a large number of biologically active peptides and proteins. These enzymes are best known for their roles in modulating the activity of kinins, complement anaphylatoxins and coagulation proteins. Although CPN makes important contributions to acute inflammatory events, little is known about its role in autoimmune disease. In this study we used CPN(-/-) mice in experimental autoimmune encephalomyelitis (EAE), the animal model for multiple sclerosis. Unexpectedly, we observed several EAE disease phenotypes in CPN(-/-) mice compared to wild type mice. The majority of CPN(-/-) mice died within five to seven days after disease induction, before displaying clinical signs of disease. The remaining mice presented with either mild EAE or did not develop EAE. In addition, CPN(-/-) mice injected with complete or incomplete Freund's adjuvant died within the same time frame and in similar numbers as those induced for EAE. Overall, the course of EAE in CPN(-/-) mice was significantly delayed and attenuated compared to wild type mice. Spinal cord histopathology in CPN(-/-) mice revealed meningeal, but not parenchymal leukocyte infiltration, and minimal demyelination. Our results indicate that CPN plays an important role in EAE development and progression and suggests that multiple CPN ligands contribute to the disease phenotypes we observed.
Assuntos
Encefalomielite Autoimune Experimental/metabolismo , Leucócitos/imunologia , Lisina Carboxipeptidase/metabolismo , Meninges/patologia , Esclerose Múltipla/metabolismo , Animais , Movimento Celular/genética , Doenças Desmielinizantes/genética , Modelos Animais de Doenças , Progressão da Doença , Encefalomielite Autoimune Experimental/genética , Humanos , Inflamação/genética , Lisina Carboxipeptidase/genética , Camundongos Endogâmicos C57BL , Esclerose Múltipla/genética , Fenótipo , Medula Espinal/patologiaRESUMO
Previous studies from our laboratory using complement-mutant mice demonstrated that the alternative pathway is the dominant activation pathway responsible for complement-mediated pathology in demyelinating disease. Using a well-characterized inhibitory monoclonal antibody (mAb 1379) directed against mouse factor B, we assessed the therapeutic value of inhibiting the alternative complement pathway in experimental autoimmune encephalomyelitis (EAE), the animal model for multiple sclerosis. Administration of anti-factor B antibody to mice prior to the onset of clinical signs of active EAE had no affect on the onset or acute phase of disease, but significantly attenuated the chronic phase of disease resulting in reduced cellular infiltration, inflammation and demyelination in antibody-treated mice. Attenuation of the chronic phase of disease was long lasting even though antibody administration was terminated shortly after disease onset. Chronic disease was also attenuated in transferred EAE when anti-factor B antibody was administered before or after disease onset. Similar levels of disease attenuation were observed in transferred EAE using MOG-specific encephalitogenic T cells. These studies demonstrate the therapeutic potential for inhibition of factor B in the chronic phase of demyelinating disease, where treatment options are limited.
Assuntos
Anticorpos Monoclonais/imunologia , Anticorpos Monoclonais/farmacologia , Via Alternativa do Complemento/efeitos dos fármacos , Via Alternativa do Complemento/imunologia , Proteínas do Sistema Complemento/imunologia , Encefalomielite Autoimune Experimental/tratamento farmacológico , Encefalomielite Autoimune Experimental/imunologia , Animais , Fator B do Complemento/classificação , Doenças Desmielinizantes/imunologia , Modelos Animais de Doenças , Inflamação/imunologia , Camundongos , Camundongos Endogâmicos C57BL , Linfócitos T/efeitos dos fármacos , Linfócitos T/imunologiaRESUMO
Multiple sclerosis (MS) is the most common autoimmune demyelinating disease, affecting millions of individuals worldwide. In the last two decades, many therapeutic options for the treatment of MS have become available, however they are limited in terms of effectiveness and some remain plagued by safety issues. The currently available treatment options target relapsing remitting forms of MS and are not effective against the more progressive forms of the disease. These limitations highlight a significant unmet treatment need for MS. In experimental autoimmune encephalomyelitis (EAE) studies from our laboratory, we have previously shown, using a number of complement mutant and transgenic mice, that inhibition of the alternative complement pathway and the C3 convertase confers significant protection from disease. We report here that targeted inhibition of complement activation using complement receptor 2 (CR2)-conjugated inhibitors significantly attenuates EAE. Administration of CR2-Crry (blocks all complement pathways at C3 activation) and CR2-fH (specifically blocks the alternative pathway) just prior to and during the onset of EAE blocks progression of both acute and chronic disease. These data indicate that inhibition of complement may offer an effective therapeutic approach to treating both acute and chronic forms of demyelinating disease through blocking the alternative pathway or complement convertases.
Assuntos
Inativadores do Complemento/uso terapêutico , Encefalomielite Autoimune Experimental/tratamento farmacológico , Receptores de Complemento 3d/antagonistas & inibidores , Proteínas Recombinantes de Fusão/uso terapêutico , Animais , Via Alternativa do Complemento/efeitos dos fármacos , Modelos Animais de Doenças , Camundongos , Camundongos Endogâmicos C57BL , Terapia de Alvo Molecular/métodosRESUMO
In experimental autoimmune encephalomyelitis (EAE) and other neurodegenerative diseases, astrocytes play an important role in promoting or attenuating the inflammatory response through induction of different cytokines and growth factors. HuR plays a major role in regulating many of these factors by modulating RNA stability and translational efficiency. Here, we engineered transgenic mice to express HuR in astrocytes using the human glial fibrillary acidic protein promoter and found that female transgenic mice had significantly less clinical disability and histopathological changes in the spinal cord. Ovariectomy prior to EAE induction abrogated the protective effect. Our findings support a role for the astrocyte and posttranscriptional regulation in hormonally-mediated attenuation of EAE.
Assuntos
Astrócitos/metabolismo , Proteínas ELAV/biossíntese , Proteínas ELAV/genética , Encefalomielite Autoimune Experimental/genética , Encefalomielite Autoimune Experimental/patologia , Congêneres do Estradiol/fisiologia , Regulação da Expressão Gênica/imunologia , Animais , Astrócitos/imunologia , Astrócitos/patologia , Proteínas ELAV/fisiologia , Encefalomielite Autoimune Experimental/metabolismo , Feminino , Humanos , Camundongos , Camundongos Transgênicos , Medula Espinal/imunologia , Medula Espinal/metabolismo , Medula Espinal/patologiaRESUMO
The beta(2)-integrins are a subfamily of integrins expressed on leukocytes that play an essential role in leukocyte trafficking, activation, and many other functions. Studies in EAE, the animal model for multiple sclerosis, show differential requirements for beta(2)-integrins in this disease model, ranging from critical in the case of LFA-1 (CD11a/CD18) to unimportant in the case of CD11d/CD18. Importantly, expression of beta(2)-integrins on T cell subsets provides some clues as to the function(s) these adhesion molecules play in disease development. For example, transferred EAE studies have shown that Mac-1 (CD11b/CD18) expression on alphabeta T cells is critical for disease development, and the absence of LFA-1 on Tregs in recipient mice results in exacerbated disease. In this review, we summarize recent findings regarding the role of beta(2)-integrins in demyelinating disease and new information about the role of beta(2)-integrins with respect to alterations in Treg numbers and function. In addition, we discuss the potential for targeting beta(2)-integrins in human demyelinating disease in light of the recent animal model studies.
Assuntos
Antígenos CD18/metabolismo , Doenças Desmielinizantes/metabolismo , Animais , Antígenos CD18/química , Encefalomielite Autoimune Experimental/metabolismo , Humanos , Ligantes , Subpopulações de Linfócitos/metabolismo , Esclerose Múltipla/metabolismo , Esclerose Múltipla/terapiaRESUMO
Intercellular adhesion molecule-1 (ICAM-1) functions in leukocyte trafficking, activation, and the formation of the immunological synapse. ICAM-1 is a member of the immunoglobulin superfamily of adhesion proteins, which share a similar structure of repeating Ig-like domains. Many genes in this family, including ICAM-1, show alternative splicing leading to the production of different protein isoforms, although little functional information is available regarding the expression patterns, ligand interactions, and functions of these isoforms, especially those arising from the ICAM-1 gene. In this study, we show using different lines of mutant mice (Icam1(tm1Jcgr) and Icam1(tm1Bay)) that alterations in the expression of the alternatively spliced ICAM-1 isoforms can significantly influence the disease course during the development of EAE. Icam1(tm1Jcgr) mutant mice, unlike Icam1(tm1Bay) mutants, do not express isoforms containing the Mac-1 binding domain and had significantly attenuated of EAE. In contrast, Icam1(tm1Bay) mice developed severe EAE in both active and adoptive transfer models compared to both Icam1(tm1Jcgr) and wild type mice. We also observed that T cells from Icam1(tm1Bay) mice displayed increased proliferation kinetics and produced higher levels of IFN-gamma compared to Icam1(tm1Jcgr) and wild type mice. Thus, our investigations show that the alternatively spliced ICAM-1 isoforms are functional, and play key roles during the progression of CNS inflammation and demyelination in EAE. Furthermore, our findings suggest that these isoforms may also play key roles in controlling the development of inflammatory diseases such as multiple sclerosis, possibly through differential engagement with ICAM-1 ligands such as Mac-1.
Assuntos
Doenças Autoimunes Desmielinizantes do Sistema Nervoso Central/imunologia , Encefalomielite Autoimune Experimental/imunologia , Inflamação/imunologia , Molécula 1 de Adesão Intercelular/imunologia , Processamento Alternativo , Animais , Proliferação de Células , Doenças Autoimunes Desmielinizantes do Sistema Nervoso Central/genética , Doenças Autoimunes Desmielinizantes do Sistema Nervoso Central/patologia , Progressão da Doença , Encefalomielite Autoimune Experimental/genética , Encefalomielite Autoimune Experimental/patologia , Inflamação/genética , Inflamação/patologia , Molécula 1 de Adesão Intercelular/genética , Interferon gama/metabolismo , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Isoformas de Proteínas/genética , Isoformas de Proteínas/imunologia , Linfócitos T Reguladores/imunologia , Linfócitos T Reguladores/metabolismoRESUMO
We showed earlier that experimental autoimmune encephalomyelitis (EAE) in human C-reactive protein (CRP) transgenic mice (CRPtg) has delayed onset and reduced severity compared to wild-type mice. Since human CRP is known to engage Fc receptors and Fc receptors are known to play a role in EAE in the mouse, we sought to determine if FcγRI, FcγRIIb, or FcγRIII was needed to manifest human CRP-mediated protection of CRPtg. We report here that in CRPtg lacking either of the two activating receptors, FcγRI and FcγRIII, the beneficial effects of human CRP are still observed. In contrast, if CRPtg lack expression of the inhibitory receptor FcγRIIB, then the beneficial effect of human CRP is abrogated. Also, subcutaneous administration of purified human CRP stalled progression of ongoing EAE in wild-type mice, but similar treatment failed to impede EAE progression in mice lacking FcγRIIB. The results reveal that a CRP â FcγRIIB axis is responsible for protection against EAE in the CRPtg model.
RESUMO
Many members of the Ig superfamily of adhesion molecules, such as ICAM-1 and VCAM-1, have been implicated in the pathogenesis of multiple sclerosis. Although it is well-established that VCAM-1/VLA-4 interactions can play important roles in mediating CNS inflammatory events in multiple sclerosis patients and during the development of experimental allergic encephalomyelitis (EAE), the contributions of ICAM-1 are poorly understood. This is due in large part to conflicting results from Ab inhibition studies and the observation of exacerbated EAE in ICAM-1 mutant mice that express a restricted set of ICAM-1 isoforms. To determine ICAM-1-mediated mechanisms in EAE, we analyzed ICAM-1 null mutant mice (ICAM-1(null)), which express no ICAM-1 isoforms. ICAM-1(null) mice had significantly attenuated EAE characterized by markedly reduced spinal cord T cell infiltration and IFN-gamma production by these cells. Adoptive transfer of Ag-restimulated T cells from wild-type to ICAM-1(null) mice or transfer of ICAM-1(null) Ag-restimulated T cells to control mice failed to induce EAE. ICAM-1(null) T cells also showed reduced proliferative capacity and substantially reduced levels of IFN-gamma, TNF-alpha, IL-4, IL-10, and IL-12 compared with that of control T cells following myelin oligodendrocyte glycoprotein 35-55 restimulation in vitro. Our results indicate that ICAM-1 expression is critical on T cells and other cell types for the development of demyelinating disease and suggest that expression of VCAM-1 and other adhesion molecules cannot fully compensate for the loss of ICAM-1 during EAE development.