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1.
Mol Ther ; 32(4): 1061-1079, 2024 Apr 03.
Artigo em Inglês | MEDLINE | ID: mdl-38382529

RESUMO

Complement-mediated diseases can be treated using systemic inhibitors. However, complement components are abundant in circulation, affecting systemic inhibitors' exposure and efficacy. Furthermore, because of complement's essential role in immunity, systemic treatments raise infection risk in patients. To address these challenges, we developed antibody fusion proteins combining the alternative-pathway complement inhibitor factor H (fH1-5) with an anti-C3d monoclonal antibody (C3d-mAb-2fH). Because C3d is deposited at sites of complement activity, this molecule localizes to tissue complement while minimizing circulating complement engagement. These fusion proteins bind to deposited complement in diseased human skin sections and localize to activated complement in a primate skin injury model. We further explored the pharmacology of C3d-mAb-2fH proteins in rodent models with robust tissue complement activation. Doses of C3d-mAb-2fH >1 mg/kg achieved >75% tissue complement inhibition in mouse and rat injury models while avoiding circulating complement blockade. Glomerular-specific complement inhibition reduced proteinuria and preserved podocyte foot-process architecture in rat membranous nephropathy, indicating disease-modifying efficacy. These data indicate that targeting local tissue complement results in durable and efficacious complement blockade in skin and kidney while avoiding systemic inhibition, suggesting broad applicability of this approach in treating a range of complement-mediated diseases.


Assuntos
Fator H do Complemento , Nefropatias , Humanos , Camundongos , Ratos , Animais , Fator H do Complemento/genética , Complemento C3d/metabolismo , Nefropatias/etiologia , Anticorpos , Ativação do Complemento
2.
Front Immunol ; 13: 869725, 2022.
Artigo em Inglês | MEDLINE | ID: mdl-35784298

RESUMO

Sustained complement activation is an underlying pathologic driver in many inflammatory and autoimmune diseases. Currently approved anti-complement therapies are directed at the systemic blockade of complement. Consequently, these therapies provide widespread inhibition of complement pathway activity, beyond the site of ongoing activation and the intended pharmacodynamic (PD) effects. Given the essential role for complement in both innate and adaptive immunity, there is a need for therapies that inhibit complement in diseased tissue while limiting systemic blockade. One potential approach focuses on the development of novel fusion proteins that enable tissue-targeted delivery of complement negative regulatory proteins. These therapies are expected to provide increased potency and prolonged tissue PD, decreased dosing frequency, and the potential for improved safety profiles. We created a library of bifunctional fusion proteins that direct a fragment of the complement negative regulator, complement receptor type 1 (CR1) to sites of tissue injury. Tissue targeting is accomplished through the binding of the fusion protein to complement C3 fragments that contain a surface-exposed C3d domain and which are covalently deposited on tissues where complement is being activated. To that end, we generated a fusion protein that contains an anti-C3d monoclonal antibody recombinantly linked to the first 10 consensus repeats of CR1 (CR11-10) with the intention of delivering high local concentrations of this complement negative regulatory domain to tissue-bound complement C3 fragments iC3b, C3dg and C3d. Biochemical and in vitro characterization identified several fusion proteins that inhibit complement while maintaining the C3d domain binding properties of the parent monoclonal antibody. Preclinical in vivo studies further demonstrate that anti-C3d fusion proteins effectively distribute to injured tissue and reduce C3 fragment deposition for periods beyond 14 days. The in vitro and in vivo profiles support the further evaluation of C3d mAb-CR11-10 as a novel approach to restore proper complement activation in diseased tissue in the absence of continuous systemic complement blockade.


Assuntos
Doenças Autoimunes , Complemento C3 , Anticorpos Monoclonais , Ativação do Complemento , Humanos , Receptores de Complemento/metabolismo
3.
Am J Physiol Renal Physiol ; 321(4): F505-F516, 2021 10 01.
Artigo em Inglês | MEDLINE | ID: mdl-34459222

RESUMO

Focal segmental glomerulosclerosis (FSGS) and minimal change disease (MCD) are common forms of idiopathic nephrotic syndrome. The causes of these diseases are incompletely understood, but the response of patients to immunosuppressive therapies suggests that their pathogenesis is at least in part immune mediated. Preclinical and clinical research indicates that activation of the classical pathway of complement contributes to glomerular injury in FSGS. Glomerular IgM deposits are also prominent in some patients, raising the possibility that IgM is a trigger of classical pathway activation. In the present study, we examined the pattern of complement activation in the glomeruli and plasma of patients with nephrotic syndrome. We also tested whether patients with FSGS and MCD have elevated levels of natural IgM reactive with epitopes on glomerular endothelial cells and cardiolipin. We found evidence of classical pathway activation in patients with idiopathic nephrotic syndrome compared with healthy control subjects. We also detected higher levels of self-reactive IgM to both targets. Based on these results, IgM and classical pathway activation may contribute to disease pathogenesis in some patients with FSGS and MCD.NEW & NOTEWORTHY IgM is detected in biopsies from some patients with nephrotic syndrome, although this has been attributed to passive trapping of the protein. We found, however, that IgM colocalizes with complement activation fragments in some glomeruli. We also found that affected patients had higher levels of IgM reactive to glomerular endothelial cell epitopes. Thus, IgM activates the complement system in the glomeruli of some patients with nephrotic syndrome and may contribute to injury.


Assuntos
Cardiolipinas/imunologia , Via Clássica do Complemento , Proteínas do Sistema Complemento/análise , Células Endoteliais/imunologia , Epitopos , Glomerulosclerose Segmentar e Focal/imunologia , Imunoglobulina M/análise , Glomérulos Renais/imunologia , Nefrose Lipoide/imunologia , Síndrome Nefrótica/imunologia , Adulto , Idoso , Especificidade de Anticorpos , Estudos de Casos e Controles , Via Clássica do Complemento/efeitos dos fármacos , Células Endoteliais/efeitos dos fármacos , Feminino , Glomerulosclerose Segmentar e Focal/sangue , Glomerulosclerose Segmentar e Focal/tratamento farmacológico , Glomerulosclerose Segmentar e Focal/patologia , Humanos , Imunoglobulina M/sangue , Imunossupressores/uso terapêutico , Glomérulos Renais/efeitos dos fármacos , Glomérulos Renais/patologia , Masculino , Pessoa de Meia-Idade , Nefrose Lipoide/tratamento farmacológico , Nefrose Lipoide/patologia , Síndrome Nefrótica/tratamento farmacológico , Síndrome Nefrótica/patologia , Resultado do Tratamento , Adulto Jovem
4.
Mol Ther Methods Clin Dev ; 15: 333-342, 2019 Dec 13.
Artigo em Inglês | MEDLINE | ID: mdl-31788497

RESUMO

Mucopolysaccharidosis type IIIA (MPS-IIIA) is a lysosomal storage disorder (LSD) caused by inherited defect of sulfamidase, a lysosomal sulfatase. MPS-IIIA is one of the most common and severe forms of LSDs with CNS involvement. Presently there is no cure. Here we have developed a new gene delivery approach for the treatment of MPS-IIIA based on the use of a modified version of sulfamidase expression cassette. This cassette encodes both a chimeric sulfamidase containing an alternative signal peptide (sp) to improve enzyme secretion and sulfatase-modifying factor 1 (SUMF1) to increase sulfamidase post-translational activation rate. We demonstrate that improved secretion and increased activation of sulfamidase act synergistically to enhance enzyme biodistribution in wild-type (WT) pigs upon intrathecal adeno-associated virus serotype 9 (AAV9)-mediated gene delivery. Translating such gene delivery strategy to a mouse model of MPS-IIIA results in a rescue of brain pathology, including memory deficit, as well as improvement in somatic tissues. These data may pave the way for developing effective gene delivery replacement protocols for the treatment of MPS-IIIA patients.

5.
Mol Ther ; 24(2): 276-286, 2016 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-26639405

RESUMO

Cerebrospinal fluid administration of recombinant adeno-associated viral (rAAV) vectors has been demonstrated to be effective in delivering therapeutic genes to the central nervous system (CNS) in different disease animal models. However, a quantitative and qualitative analysis of transduction patterns of the most promising rAAV serotypes for brain targeting in large animal models is missing. Here, we characterize distribution, transduction efficiency, and cellular targeting of rAAV serotypes 1, 2, 5, 7, 9, rh.10, rh.39, and rh.43 delivered into the cisterna magna of wild-type pigs. rAAV9 showed the highest transduction efficiency and the widest distribution capability among the vectors tested. Moreover, rAAV9 robustly transduced both glia and neurons, including the motor neurons of the spinal cord. Relevant cell transduction specificity of the glia was observed after rAAV1 and rAAV7 delivery. rAAV7 also displayed a specific tropism to Purkinje cells. Evaluation of biochemical and hematological markers suggested that all rAAV serotypes tested were well tolerated. This study provides a comprehensive CNS transduction map in a useful preclinical large animal model enabling the selection of potentially clinically transferable rAAV serotypes based on disease specificity. Therefore, our data are instrumental for the clinical evaluation of these rAAV vectors in human neurodegenerative diseases.


Assuntos
Sistema Nervoso Central/metabolismo , Dependovirus/genética , Vetores Genéticos/administração & dosagem , Vetores Genéticos/líquido cefalorraquidiano , Proteínas de Fluorescência Verde/metabolismo , Animais , Dependovirus/imunologia , Técnicas de Transferência de Genes , Proteínas de Fluorescência Verde/genética , Humanos , Especificidade de Órgãos , Sorogrupo , Suínos , Transdução Genética , Transgenes
6.
Curr Opin Rheumatol ; 23(1): 119-24, 2011 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-21124094

RESUMO

PURPOSE OF REVIEW: Recent descriptions of the group of clinical disorders collectively defined as IgG4-related systemic disease (IgG4-RSD) have prompted this review of the unique biology of the IgG4 antibody. This article will discuss IgG4 structure and function, the unique phenomenon of half-antibody exchange, and the implications of IgG4 biology for its proposed role in immunologic diseases. RECENT FINDINGS: IgG4 antibodies have unique structural and functional properties and undergo 'half-antibody exchange' in vivo, resulting in recombined antibodies composed of two different binding specificities. The production of IgG4 antibodies appears to be driven in part by T helper 2 (Th2) cytokines that mediate allergic responses and IgE production. Although serum IgG4 levels in healthy individuals vary significantly, data from multiple sclerosis (MS) patients suggest tight regulation of individual IgG4 levels over time. IgG4-RSD represents a diverse group of clinical disorders unified by elevated IgG4 levels and specific histopathologic findings. A key unanswered question is whether IgG4, a relatively weak activator of effector cells, is pathogenic in these disorders. SUMMARY: IgG4 is a unique antibody biologically and structurally. Increased understanding of its precise role in the clinical syndromes that comprise IgG4-RSD may ultimately elucidate the underlying pathogenesis.


Assuntos
Imunoglobulina G/química , Imunoglobulina G/imunologia , Anticorpos Biespecíficos/biossíntese , Anticorpos Biespecíficos/química , Anticorpos Biespecíficos/imunologia , Especificidade de Anticorpos , Autoanticorpos/biossíntese , Autoanticorpos/química , Autoanticorpos/imunologia , Doenças Autoimunes/imunologia , Humanos , Imunoglobulina G/biossíntese , Imunoglobulina G/uso terapêutico , Estrutura Molecular , Estrutura Terciária de Proteína , Células Th2/imunologia
7.
Int Immunol ; 18(10): 1473-85, 2006 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-16914508

RESUMO

BAFF [B cell-activating factor of the tumour necrosis factor (TNF) family] and APRIL (a proliferation-inducing ligand) are two TNF family members with shared receptors. While, physiological roles for APRIL are not fully understood, BAFF is critical for B cell homeostasis and also acts as a co-stimulator of T cells. Using a B and T cell-mediated mouse model of multiple sclerosis (MS), myelin oligodendrocyte glycoprotein (MOG)-induced experimental autoimmune encephalomyelitis (EAE), we observed that a BAFF/APRIL antagonist (soluble BCMA-Fc) inhibited central nervous system inflammation and demyelination such that it suppressed the onset and progression of clinical symptoms of EAE. In addition to dramatically reducing the titre of MOG-specific auto-antibodies, this treatment also induced a switch in the subtype of the T(h) cell population characterized by marked alterations in cytokine production following re-stimulation with MOG in vitro. Indeed, hBCMA-Fc therapy led to significant increases in the level of transforming growth factor beta, while the levels of T(h)1 cytokines were markedly diminished. These results not only identify BAFF as a critical factor in maintaining humoral immunity in EAE but also support its role in T lymphocyte responses. Our findings demonstrate that hBCMA-Fc acts on both effector arms of the immune response in EAE, a characteristic that may be of significant therapeutic value in the treatment of MS.


Assuntos
Formação de Anticorpos/efeitos dos fármacos , Fator Ativador de Células B/antagonistas & inibidores , Antígeno de Maturação de Linfócitos B/administração & dosagem , Encefalomielite Autoimune Experimental/tratamento farmacológico , Fragmentos Fc das Imunoglobulinas/administração & dosagem , Esclerose Múltipla/tratamento farmacológico , Animais , Formação de Anticorpos/imunologia , Fator Ativador de Células B/imunologia , Linfócitos B/imunologia , Encefalomielite Autoimune Experimental/induzido quimicamente , Encefalomielite Autoimune Experimental/imunologia , Feminino , Imunidade Celular/efeitos dos fármacos , Imunidade Celular/imunologia , Camundongos , Camundongos Endogâmicos NOD , Esclerose Múltipla/induzido quimicamente , Esclerose Múltipla/imunologia , Proteínas da Mielina , Glicoproteína Associada a Mielina/administração & dosagem , Glicoproteína Associada a Mielina/toxicidade , Glicoproteína Mielina-Oligodendrócito , Proteínas Recombinantes de Fusão/administração & dosagem , Linfócitos T/imunologia , Membro 13 da Superfamília de Ligantes de Fatores de Necrose Tumoral/antagonistas & inibidores , Membro 13 da Superfamília de Ligantes de Fatores de Necrose Tumoral/imunologia
8.
Semin Immunol ; 18(5): 290-6, 2006 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-16931038

RESUMO

The development of the B cell lineage has been extensively studied along with the soluble and cellular components involved in the maturation and selection process. It was not always clear, however, what factors were involved in supporting mature B cell survival. Identification of the B cell survival factor, BAFF, was a key discovery in understanding the survival mechanism for mature B cells in the periphery. More recent investigations have illuminated roles for BAFF in B cell biology outside of a survival mechanism. These include germinal center maintenance, isotype switching, and regulation of specific B cell surface markers. More importantly, a role for BAFF in B cell biology has been validated in vivo in humans.


Assuntos
Fator Ativador de Células B/imunologia , Receptor do Fator Ativador de Células B/imunologia , Subpopulações de Linfócitos B/imunologia , Animais , Formação de Anticorpos/imunologia , Doenças Autoimunes/imunologia , Autoimunidade/imunologia , Fator Ativador de Células B/deficiência , Fator Ativador de Células B/genética , Receptor do Fator Ativador de Células B/deficiência , Receptor do Fator Ativador de Células B/genética , Subpopulações de Linfócitos B/citologia , Diferenciação Celular , Sobrevivência Celular , Centro Germinativo/imunologia , Humanos , Leucemia de Células B/imunologia , Cooperação Linfocítica , Linfoma de Células B/imunologia , Camundongos , Primatas/imunologia , Especificidade da Espécie
9.
Endocrinology ; 147(10): 4561-8, 2006 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-16794009

RESUMO

Hyperthyroid Graves' disease is a common autoimmune disorder mediated by agonistic antibodies to the TSH receptor, termed thyroid stimulating antibodies (TSAbs). Recently members of the TNF superfamily, B cell activating factor (BAFF) and a proliferation-inducing ligand (APRIL), have been identified along with their receptors, B cell maturation antigen and transmembrane activator and calcium-modulator and cyclophilin ligand interactor, and the BAFF-specific receptor. BAFF is a fundamental B cell survival/maturation factor, and both BAFF and APRIL have been implicated in antibody production. We investigated the effect of interfering with BAFF- and APRIL-mediated signals in an induced model of Graves' disease by blockade of these factors using soluble decoy receptors. In a therapeutic setting in mice with established hyperthyroidism, we show that blockade of BAFF or BAFF+APRIL with BAFF-specific receptor-Fc and B cell maturation antigen-Fc, respectively, leads to significant reductions in the induced hyperthyroidism. This was supported by a parallel pattern of declining TSAbs in the responding animals. Histopathological analysis of splenic sections from treated animals revealed marked reductions in the B cell follicle regions, but staining with anti-CD138 revealed the persistence of plasma cells. Thus, the reductions in TSAbs in the treated animals were not related to overall plasma cell numbers in the secondary lymphoid organs. Our results are the first to demonstrate attenuation of established hyperthyroidism by therapeutic intervention aimed at autoreactive B cells and indicate that both BAFF and APRIL appear to play important roles in the development and survival of the autoantibody producing cells in this model.


Assuntos
Doença de Graves/tratamento farmacológico , Proteínas de Membrana/fisiologia , Tireoidite Autoimune/tratamento farmacológico , Fator de Necrose Tumoral alfa/antagonistas & inibidores , Adenoviridae/genética , Animais , Fator Ativador de Células B , Linfócitos B/fisiologia , Difenilamina/análogos & derivados , Difenilamina/farmacologia , Feminino , Citometria de Fluxo , Vetores Genéticos , Doença de Graves/patologia , Imunoglobulinas Estimuladoras da Glândula Tireoide/metabolismo , Imuno-Histoquímica , Ligantes , Proteínas de Membrana/antagonistas & inibidores , Camundongos , Camundongos Endogâmicos BALB C , Receptores da Tireotropina/genética , Tireoidite Autoimune/patologia , Membro 13 da Superfamília de Ligantes de Fatores de Necrose Tumoral , Fator de Necrose Tumoral alfa/fisiologia
10.
J Autoimmun ; 25(4): 298-302, 2005 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-16242914

RESUMO

BAFF (B-cell activating factor of the TNF family) plays a crucial role in B-cell survival. Elevated BAFF serum levels have been linked to several autoimmune diseases in humans, and therapies targeting BAFF were successful in animal models of rheumatoid arthritis and systemic lupus erythematosus. Wagener's granulomatosis (WG), a chronic systemic vasculitis, is characterized by circulating autoantibodies (cANCA) targeting neutrophils, which can produce BAFF. To investigate whether BAFF is involved in WG pathology, BAFF serum levels were measured by ELISA in 46 WG patients and 62 healthy donors. We report the novel finding that in WG patients serum levels of BAFF were significantly increased (median 3.95 ng/ml, p=0.009) compared to healthy controls (median 2.38 ng/ml). The difference was even more pronounced when comparing controls with untreated WG patients (median 4.61 ng/ml, p=0.001). Treatment of WG patients with glucocorticoids was associated with lower BAFF levels. The serum BAFF level in treated WG patients was about the same as in the control group. We propose that BAFF might be a pathogenic factor in WG and that targeting BAFF may represent a new therapeutic strategy in a subset of chronically relapsing WG patients with elevated BAFF levels.


Assuntos
Fator Ativador de Células B/sangue , Granulomatose com Poliangiite/sangue , Regulação para Cima/imunologia , Idoso , Idoso de 80 Anos ou mais , Fator Ativador de Células B/biossíntese , Feminino , Humanos , Masculino , Pessoa de Meia-Idade
11.
J Immunol ; 175(9): 6143-54, 2005 Nov 01.
Artigo em Inglês | MEDLINE | ID: mdl-16237111

RESUMO

Foci of autoantigen-specific B lymphocytes in nonlymphoid tissues have been associated with development of autoimmune disease. To better understand the genesis of such ectopic lymphoid tissue, this study investigated whether several B cell-tropic innate immune system molecules, known to be elevated in response to inflammatory stimuli, can cooperate in fostering the T cell-independent clonal expansion of mature human B2 cells under conditions of limiting BCR engagement. Notable synergy was observed between BCR coligation with the C3dg-binding CD21/CD19 costimulatory complex, B cell-activating factor belonging to the TNF family (BAFF), and IL-4 in generating B cell progeny with sustained CD86 and DR expression. The synergy was observed over a wide range of BCR:ligand affinities and involved: 1) cooperative effects at promoting early cell cycle progression and viability; 2) BCR:CD21 coligation-promoted increases in BAFF receptors that were highly regulated by IL-4; 3) reciprocal effects of IL-4 and BAFF at dampening daughter cell apoptosis typical of stimulation by BCR:CD21 and either cytokine alone; and 4) BAFF-sustained expression of antiapoptotic Mcl-1 within replicating lymphoblasts. The results suggest that significant clonal proliferation of recirculating B2 cells occurs upon limited binding to C3dg-coated Ag in an inflammatory in vivo milieu containing both BAFF and IL-4. When rare autoantigen-presenting B cells undergo such expansions, both B cell and T cell autoimmunity may be promoted.


Assuntos
Subpopulações de Linfócitos B/fisiologia , Imunidade Inata , Adolescente , Anticorpos Anti-Idiotípicos/farmacologia , Antígenos CD19/fisiologia , Fator Ativador de Células B , Subpopulações de Linfócitos B/imunologia , Sobrevivência Celular , Criança , Pré-Escolar , Antígenos de Histocompatibilidade Classe II/análise , Humanos , Interleucina-4/farmacologia , Ativação Linfocitária , Proteínas de Membrana/farmacologia , Proteínas de Membrana/fisiologia , Proteína de Sequência 1 de Leucemia de Células Mieloides , Proteínas de Neoplasias/análise , Proteínas Proto-Oncogênicas c-bcl-2/análise , Receptores de Antígenos de Linfócitos B/fisiologia , Receptores de Complemento 3d/fisiologia , Receptores do Fator de Necrose Tumoral/fisiologia , Fase S , Proteína Transmembrana Ativadora e Interagente do CAML , Fator de Necrose Tumoral alfa/farmacologia
12.
Arthritis Rheum ; 52(7): 2080-91, 2005 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-15986357

RESUMO

OBJECTIVE: To determine whether overexpression of BAFF can accelerate the development of systemic lupus erythematosus-associated end-organ disease in hosts with an underlying autoimmune diathesis. METHODS: We introduced a BAFF transgene (Tg) into autoimmune-prone B6.Sle1 and B6.Nba2 mice and evaluated these mice for serologic autoimmunity and renal pathology. RESULTS: B6.Sle1.BAFF and B6.Nba2.BAFF mice, but not non-Tg littermates, frequently developed severe glomerular pathology by 3 months of age. Age-matched B6.BAFF mice, despite renal Ig deposits and increases in B cells and Ig production similar to those in B6.Sle1.BAFF and B6.Nba2.BAFF mice, did not develop glomerular pathology. In B6.Sle1.BAFF and B6.Nba2.BAFF mice, severity of glomerular disease did not obligately correlate with circulating levels of IgG anti-chromatin and/or anti-double-stranded DNA antibodies or with amounts of these autoantibodies deposited in the kidneys. Even in mice with severe glomerular disease, renal tubulointerstitial infiltrates were very limited, and increased proteinuria was not detected. CONCLUSION: BAFF-driven effects on glomerular pathology may be mediated, at least in part, by autoantibodies with specificities other than chromatin and/or by autoantibody-independent means. There is an uncoupling of BAFF-driven precocious glomerular pathology from concomitant development of clinically apparent renal disease, strongly suggesting that BAFF overexpression works in concert with other factors to promote overt renal disease.


Assuntos
Expressão Gênica , Predisposição Genética para Doença , Nefrite Lúpica/genética , Proteínas de Membrana/genética , Fator de Necrose Tumoral alfa/genética , Animais , Anticorpos Antinucleares/imunologia , Fator Ativador de Células B , Linfócitos B/patologia , Cromatina/imunologia , DNA/imunologia , Modelos Animais de Doenças , Feminino , Imunoglobulina G/imunologia , Glomérulos Renais/patologia , Nefrite Lúpica/imunologia , Nefrite Lúpica/patologia , Masculino , Proteínas de Membrana/metabolismo , Camundongos , Camundongos Transgênicos , Baço/patologia , Linfócitos T/patologia , Fatores de Tempo , Fator de Necrose Tumoral alfa/metabolismo
13.
J Exp Med ; 201(9): 1375-83, 2005 May 02.
Artigo em Inglês | MEDLINE | ID: mdl-15851487

RESUMO

B cell activating factor of the tumor necrosis factor (TNF) family (BAFF) and a proliferation-inducing ligand (APRIL) are closely related ligands within the TNF superfamily that play important roles in B lymphocyte biology. Both ligands share two receptors--transmembrane activator and calcium signal--modulating cyclophilin ligand interactor (TACI) and B cell maturation antigen (BCMA)--that are predominantly expressed on B cells. In addition, BAFF specifically binds BAFF receptor, whereas the nature of a postulated APRIL-specific receptor remains elusive. We show that the TNF homology domain of APRIL binds BCMA and TACI, whereas a basic amino acid sequence (QKQKKQ) close to the NH2 terminus of the mature protein is required for binding to the APRIL-specific "receptor." This interactor was identified as negatively charged sulfated glycosaminoglycan side chains of proteoglycans. Although T cell lines bound little APRIL, the ectopic expression of glycosaminoglycan-rich syndecans or glypicans conferred on these cells a high binding capacity that was completely dependent on APRIL's basic sequence. Moreover, syndecan-1-positive plasma cells and proteoglycan-rich nonhematopoietic cells displayed high specific, heparin-sensitive binding to APRIL. Inhibition of BAFF and APRIL, but not BAFF alone, prevented the survival and/or the migration of newly formed plasma cells to the bone marrow. In addition, costimulation of B cell proliferation by APRIL was only effective upon APRIL oligomerization. Therefore, we propose a model whereby APRIL binding to the extracellular matrix or to proteoglycan-positive cells induces APRIL oligomerization, which is the prerequisite for the triggering of TACI- and/or BCMA-mediated activation, migration, or survival signals.


Assuntos
Linfócitos B/metabolismo , Proteínas de Membrana/metabolismo , Modelos Biológicos , Proteínas Nucleares/metabolismo , Proteoglicanas/metabolismo , Receptores do Fator de Necrose Tumoral/metabolismo , Animais , Fator Ativador de Células B , Receptor do Fator Ativador de Células B , Antígeno de Maturação de Linfócitos B , Linhagem Celular , Movimento Celular/genética , Proliferação de Células , Citometria de Fluxo , Heparina/metabolismo , Humanos , Imunoprecipitação , Camundongos , Plasmócitos/metabolismo , Ligação Proteica , Estrutura Terciária de Proteína , Transfecção , Proteína Transmembrana Ativadora e Interagente do CAML , Fator de Necrose Tumoral alfa/metabolismo
14.
Immunol Rev ; 204: 43-54, 2005 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-15790349

RESUMO

BAFF [B-cell activating factor belonging to the tumor necrosis factor (TNF) family] is a ligand that is required for peripheral B-cell survival and homeostasis. In addition to mediating B-cell survival, BAFF also regulates expression of certain B-cell-surface proteins, such as CD21/35. BAFF deficiency results in a reduced number of peripheral B cells and a diminished ability to mount robust humoral immune responses. Overexpression of BAFF has been linked to murine and human autoimmunity, and recent data provide clues as to how excess BAFF may allow the emergence of autoreactive B cells. In vivo animal testing with BAFF inhibitors has generated exciting data that support the pathway as a target for modulating B cells. The role of BAFF in B-cell biology, T-cell biology, and autoimmunity is discussed, as well as current efforts to develop BAFF inhibitors for clinical testing in autoimmune disorders.


Assuntos
Autoimunidade/imunologia , Proteínas de Membrana/imunologia , Fator de Necrose Tumoral alfa/imunologia , Animais , Fator Ativador de Células B , Linfócitos B/citologia , Linfócitos B/imunologia , Sobrevivência Celular , Humanos , Proteínas de Membrana/antagonistas & inibidores , Receptores do Fator de Necrose Tumoral/imunologia , Fator de Necrose Tumoral alfa/antagonistas & inibidores
15.
J Immunol ; 174(2): 864-70, 2005 Jan 15.
Artigo em Inglês | MEDLINE | ID: mdl-15634908

RESUMO

Immunohistochemical analysis revealed that the intimal lining cells of synovial tissue of inflamed joints of patients with rheumatoid arthritis differed from that of normal joints or of diseased joints in osteoarthritis in that they stained with mAb specific for the B cell-activating factor of the TNF family (BAFF; also called BLyS). We generated fibroblast-like synoviocytes (FLS) cell lines that were bereft of myelomonocytic cells to examine whether mesenchymal-derived FLS could express this critical B cell survival factor. We found that FLS expressed low amounts of BAFF mRNA relative to that of myelomonocytic cells. However, when various cytokines/factors were added to such FLS cell lines, we found that IFN-gamma or TNF-alpha were unique in that they could induce significant increases in BAFF mRNA and protein. Even minute amounts of IFN-gamma primed FLS for TNF-alpha, allowing the latter to stimulate significantly higher levels of BAFF mRNA and protein than could TNF-alpha alone. Consistent with this, B cells cocultured with IFN-gamma and/or TNF-alpha-treated FLS had a significantly greater viability than B cells cocultured with nontreated FLS. The enhanced protection of B cells afforded by IFN-gamma/TNF-alpha-treated FLS was inhibited by the addition of BAFF-R:Fc fusion protein. We conclude that the proinflammatory cytokines IFN-gamma and TNF-alpha can induce mesenchymal-derived FLS to express functional BAFF in vitro. The induced expression of BAFF on FLS by proinflammatory cytokines may enhance the capacity of such cells to protect B cells from apoptosis in inflammatory microenvironments in vivo.


Assuntos
Citocinas/fisiologia , Fibroblastos/imunologia , Mediadores da Inflamação/fisiologia , Proteínas de Membrana/biossíntese , Mesoderma/citologia , Membrana Sinovial/imunologia , Fator de Necrose Tumoral alfa/biossíntese , Adjuvantes Imunológicos/fisiologia , Apoptose/imunologia , Artrite Reumatoide/imunologia , Artrite Reumatoide/metabolismo , Fator Ativador de Células B , Subpopulações de Linfócitos B/citologia , Subpopulações de Linfócitos B/imunologia , Linhagem Celular , Sobrevivência Celular/imunologia , Células Cultivadas , Técnicas de Cocultura , Sinergismo Farmacológico , Fibroblastos/metabolismo , Humanos , Interferon gama/fisiologia , Proteínas de Membrana/genética , Proteínas de Membrana/fisiologia , Mesoderma/imunologia , Mesoderma/metabolismo , RNA Mensageiro/biossíntese , Membrana Sinovial/citologia , Membrana Sinovial/metabolismo , Fator de Necrose Tumoral alfa/genética , Fator de Necrose Tumoral alfa/fisiologia
16.
J Exp Med ; 201(2): 195-200, 2005 Jan 17.
Artigo em Inglês | MEDLINE | ID: mdl-15642740

RESUMO

We report that B cell-activating factor of the tumor necrosis factor (TNF) family (BAFF) is expressed in the normal human brain at approximately 10% of that in lymphatic tissues (tonsils and adenoids) and is produced by astrocytes. BAFF was regularly detected by enzyme-linked immunosorbent assay in brain tissue lysates and in normal spinal fluid, and in astrocytes by double fluorescence microscopy. Cultured human astrocytes secreted functionally active BAFF after stimulation with interferon-gamma and TNF-alpha via a furin-like protease-dependent pathway. BAFF secretion per cell was manifold higher in activated astrocytes than in monocytes and macrophages. We studied brain lesions with B cell components, and found that in multiple sclerosis plaques, BAFF expression was strongly up-regulated to levels observed in lymphatic tissues. BAFF was localized in astrocytes close to BAFF-R-expressing immune cells. BAFF receptors were strongly expressed in situ in primary central nervous system (CNS) lymphomas. This paper identifies astrocytes as a nonimmune source of BAFF. CNS-produced BAFF may support B cell survival in inflammatory diseases and primary B cell lymphoma.


Assuntos
Astrócitos/metabolismo , Neoplasias do Sistema Nervoso Central/metabolismo , Linfoma/metabolismo , Proteínas de Membrana/metabolismo , Esclerose Múltipla/metabolismo , Fator de Necrose Tumoral alfa/metabolismo , Fator Ativador de Células B , Receptor do Fator Ativador de Células B , Linfócitos B , Encéfalo/metabolismo , Humanos , Proteínas de Membrana/genética , Especificidade de Órgãos , RNA Mensageiro/metabolismo , Receptores do Fator de Necrose Tumoral/metabolismo , Fator de Necrose Tumoral alfa/genética , Regulação para Cima
17.
Curr Dir Autoimmun ; 8: 206-42, 2005.
Artigo em Inglês | MEDLINE | ID: mdl-15564723

RESUMO

The tumor necrosis factor (TNF) family of related receptors and ligands contains a rich collection of molecules that are important players in a broad spectrum of biological systems. While several family members are critical for development and function of the immune system, providing both activation and death signals, other members are involved in nonimmunological functions as diverse as hair follicle formation. TNF homology searches during the past several years have led to the discovery of numerous novel ligands, two of which will be the focus of this review. BAFF, a cytokine responsible for B cell survival, has recently been the subject of intense investigation that has expanded our understanding of mature B cell genesis, and mechanisms involved in developing B cell pathologies. APRIL is a close relative of BAFF and while its biological roles are less well understood, it may have both immune and non-immune functions. Herein we will discuss the discovery, structure, cognate receptors and functions of these two proteins.


Assuntos
Proteínas de Membrana/química , Proteínas de Membrana/imunologia , Fator de Necrose Tumoral alfa/química , Fator de Necrose Tumoral alfa/imunologia , Animais , Fator Ativador de Células B , Receptor do Fator Ativador de Células B , Linfócitos B/citologia , Linfócitos B/imunologia , Diferenciação Celular , Sobrevivência Celular , Doença Enxerto-Hospedeiro/terapia , Humanos , Ligantes , Proteínas de Membrana/genética , Camundongos , Receptores do Fator de Necrose Tumoral/química , Receptores do Fator de Necrose Tumoral/genética , Receptores do Fator de Necrose Tumoral/imunologia , Transdução de Sinais , Linfócitos T/imunologia , Membro 13 da Superfamília de Ligantes de Fatores de Necrose Tumoral , Fator de Necrose Tumoral alfa/genética
18.
Int Immunol ; 16(11): 1583-94, 2004 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-15466914

RESUMO

Blockade of the CD154-CD40 co-stimulatory pathway with anti-CD154 mAbs has shown impressive efficacy in models of autoimmunity and allotransplantation. Clinical benefit was also demonstrated in systemic lupus erythematosus (SLE) and idiopathic thrombocytopenia patients with the humanized anti-CD154 mAb, 5C8 (hu5C8). However, thromboembolic complications that occurred during the course of the hu5C8 clinical trials have proven to be a major setback to the field and safe alternative therapeutics targeting the CD154-CD40 pathway are of great interest. Recently, effector mechanisms have been shown to play a part in anti-CD154 mAb-induced transplant acceptance in murine models, while this issue remains unresolved for humoral-mediated models. Herein, aglycosyl anti-CD154 mAbs with reduced binding to FcgammaR and complement were used as a novel means to test the role of effector mechanisms in non-human primate and murine models not amenable to gene knockout technology. While aglycosyl hu5C8 mAb was relatively ineffective in rhesus renal and islet allotransplantation, it inhibited primary and secondary humoral responses to a protein immunogen in cynomolgus monkeys. Moreover, an aglycosyl, chimeric MR1 mAb (muMR1) prolonged survival and inhibited pathogenic auto-antibody production in a murine model of SLE. Thus, the mechanisms required for efficacy of anti-CD154 mAbs depend on the nature of the immune challenge.


Assuntos
Anticorpos Monoclonais/imunologia , Ligante de CD40/imunologia , Imunização Passiva , Transplante das Ilhotas Pancreáticas/imunologia , Transplante de Rim/imunologia , Lúpus Eritematoso Sistêmico/imunologia , Receptores de IgG/imunologia , Animais , Anticorpos Monoclonais/administração & dosagem , Anticorpos Monoclonais Humanizados , Antígenos CD40/imunologia , Modelos Animais de Doenças , Glicosilação , Humanos , Fragmentos Fc das Imunoglobulinas/imunologia , Lúpus Eritematoso Sistêmico/patologia , Lúpus Eritematoso Sistêmico/terapia , Macaca fascicularis , Camundongos , Trombocitemia Essencial/imunologia , Trombocitemia Essencial/patologia , Trombocitemia Essencial/terapia , Transplante Homólogo
19.
Nature ; 431(7007): 456-61, 2004 Sep 23.
Artigo em Inglês | MEDLINE | ID: mdl-15361883

RESUMO

Approximately 65% of B cells generated in human bone marrow are potentially harmful autoreactive B cells. Most of these cells are clonally deleted in the bone marrow, while those autoreactive B cells that escape to the periphery are anergized or perish before becoming mature B cells. Escape of self-reactive B cells from tolerance permits production of pathogenic auto-antibodies; recent studies suggest that extended B lymphocyte survival is a cause of autoimmune disease in mice and humans. Here we report a mechanism for the regulation of peripheral B-cell survival by serine/threonine protein kinase Cdelta (PKCdelta): spontaneous death of resting B cells is regulated by nuclear localization of PKCdelta that contributes to phosphorylation of histone H2B at serine 14 (S14-H2B). We show that treatment of B cells with the potent B-cell survival factor BAFF ('B-cell-activating factor belonging to the TNF family') prevents nuclear accumulation of PKCdelta. Our data suggest the existence of a previously unknown BAFF-induced and PKCdelta-mediated nuclear signalling pathway which regulates B-cell survival.


Assuntos
Linfócitos B/citologia , Linfócitos B/metabolismo , Núcleo Celular/metabolismo , Proteínas de Membrana/metabolismo , Proteína Quinase C/metabolismo , Transdução de Sinais , Fator de Necrose Tumoral alfa/metabolismo , Animais , Fator Ativador de Células B , Linfócitos B/enzimologia , Morte Celular , Núcleo Celular/enzimologia , Sobrevivência Celular , Células Cultivadas , Fibroblastos , Camundongos , Fosforilação , Proteína Quinase C/deficiência , Proteína Quinase C/genética , Proteína Quinase C-delta
20.
J Immunol ; 173(4): 2331-41, 2004 Aug 15.
Artigo em Inglês | MEDLINE | ID: mdl-15294946

RESUMO

The TNF-related ligand, B cell-activating factor belonging to the TNF family (BAFF), is necessary for normal B cell development and survival, and specifically binds the receptors transmembrane activator and calcium-modulator and cyclophilin ligand interactor (TACI), B cell maturation Ag (BCMA), and BAFF-R. Similarities between mice completely lacking BAFF and A/WySnJ strain mice that express a naturally occurring mutant form of BAFF-R suggest that BAFF acts primarily through BAFF-R. However, the nearly full-length BAFF-R protein expressed by A/WySnJ mice makes unambiguous interpretation of receptor function in these animals impossible. Using homologous recombination we created mice completely lacking BAFF-R and compared them directly to A/WySnJ mice and to mice lacking BAFF. BAFF-R-null mice exhibit loss of mature B cells similar to that observed in BAFF(-/-) and A/WySnJ mice. Also, mice lacking both TACI and BCMA simultaneously exhibit no B cell loss, thus confirming that BAFF-R is the primary receptor for transmitting the BAFF-dependent B cell survival signal. However, while BAFF-R-null mice cannot carry out T cell-dependent Ab formation, they differ from BAFF-deficient mice in generating normal levels of Ab to at least some T cell-independent Ags. These studies clearly demonstrate that BAFF regulates Ab responses in vivo through receptors in addition to BAFF-R.


Assuntos
Formação de Anticorpos/imunologia , Linfócitos B/imunologia , Proteínas de Membrana/imunologia , Linfócitos T/imunologia , Fator de Necrose Tumoral alfa/imunologia , Animais , Fator Ativador de Células B , Receptor do Fator Ativador de Células B , Antígeno de Maturação de Linfócitos B , Ensaio de Imunoadsorção Enzimática , Citometria de Fluxo , Imuno-Histoquímica , Proteínas de Membrana/genética , Camundongos , Camundongos Mutantes , Receptores do Fator de Necrose Tumoral/genética , Receptores do Fator de Necrose Tumoral/imunologia , Reação em Cadeia da Polimerase Via Transcriptase Reversa , Proteína Transmembrana Ativadora e Interagente do CAML
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