RESUMO
The common gamma chain cytokines interleukin (IL)-2 and IL-7 are important regulators of T cell homeostasis. Although IL-2 is implicated in the acute phase of the T cell response, IL-7 is important for memory T cell survival. We asked whether regulated responsiveness to these growth factors is determined by temporal expression of the cytokine-specific IL-2 receptor (R) alpha and IL-7Ralpha chains. We demonstrate that IL-2Ralpha is expressed early after priming in T cell receptor-transgenic CD4(+) T cells, whereas IL-7Ralpha expression is lost. In the later stage of the response, IL-7Ralpha is reexpressed while IL-2Ralpha expression is silenced. This reciprocal pattern of IL-2Ralpha/IL-7Ralpha expression is disturbed when CD4(+) T cells are primed in the absence of IL-2 signals. Primed IL-2(-/-) or CD25(-/-) (IL-2Ralpha(-/-)) CD4(+) T cells, despite showing normal induction of activation markers and cell division, fail to reexpress IL-7Ralpha late in the response. Because the generation of CD4(+) memory T cells is dependent on IL-7-IL-7Ralpha interactions, primed IL-2(-/-) or CD25(-/-) CD4(+) T cells develop poorly into long-lived memory cells. Retrovirus-mediated expression of IL-7Ralpha in IL-2(-/-) T cells restores their capacity for long-term survival. These results identify IL-2 as a factor regulating IL-7Ralpha expression and, consequently, memory T cell homeostasis in vivo.
Assuntos
Adjuvantes Imunológicos/fisiologia , Linfócitos T CD4-Positivos/imunologia , Diferenciação Celular/imunologia , Memória Imunológica , Interleucina-2/fisiologia , Receptores de Interleucina-7/biossíntese , Animais , Linfócitos T CD4-Positivos/citologia , Linfócitos T CD4-Positivos/metabolismo , Diferenciação Celular/genética , Células Cultivadas , Regulação da Expressão Gênica/imunologia , Homeostase/genética , Homeostase/imunologia , Memória Imunológica/genética , Subunidade alfa de Receptor de Interleucina-2/biossíntese , Subunidade alfa de Receptor de Interleucina-2/genética , Camundongos , Camundongos Endogâmicos BALB C , Camundongos Knockout , Camundongos Transgênicos , Receptores de Interleucina-7/genéticaRESUMO
OBJECTIVE: Numerous observations implicate interferon-α (IFNα) in the pathophysiology of systemic lupus erythematosus (SLE); however, the potential impact of endogenous anti-IFNα autoantibodies (AIAAs) on IFN-pathway and disease activity is unclear. The aim of this study was to characterize IFN-pathway activity and the serologic and clinical profiles of AIAA-positive patients with SLE. METHODS: Sera obtained from patients with SLE (n = 49), patients with rheumatoid arthritis (n = 25), and healthy control subjects (n = 25) were examined for the presence of AIAAs, using a biosensor immunoassay. Serum type I IFN bioactivity and the ability of AIAA-positive sera to neutralize IFNα activity were determined using U937 cells. Levels of IFN-regulated gene expression in peripheral blood were determined by microarray, and serum levels of BAFF, IFN-inducible chemokines, and other autoantibodies were measured using immunoassays. RESULTS: AIAAs were detected in 27% of the serum samples from patients with SLE, using a biosensor immunoassay. Unsupervised hierarchical clustering analysis identified 2 subgroups of patients, IFN(low) and IFN(high) , that differed in the levels of serum type I IFN bioactivity, IFN-regulated gene expression, BAFF, anti-ribosomal P, and anti-chromatin autoantibodies, and in AIAA status. The majority of AIAA-positive patients had significantly lower levels of serum type I IFN bioactivity, reduced downstream IFN-pathway activity, and lower disease activity compared with the IFN(high) patients. AIAA-positive sera were able to effectively neutralize type I IFN activity in vitro. CONCLUSION: Patients with SLE commonly harbor AIAAs. AIAA-positive patients have lower levels of serum type I IFN bioactivity and evidence for reduced downstream IFN-pathway and disease activity. AIAAs may influence the clinical course in SLE by blunting the effects produced by IFNα.
Assuntos
Autoanticorpos/imunologia , Interferon-alfa/imunologia , Lúpus Eritematoso Sistêmico/imunologia , Adulto , Artrite Reumatoide/genética , Artrite Reumatoide/imunologia , Artrite Reumatoide/metabolismo , Autoanticorpos/sangue , Regulação da Expressão Gênica , Humanos , Interferon-alfa/genética , Interferon-alfa/metabolismo , Lúpus Eritematoso Sistêmico/genética , Lúpus Eritematoso Sistêmico/metabolismo , Índice de Gravidade de Doença , Transdução de SinaisRESUMO
Tumor necrosis factor-superfamily (TNF-SF) members, lymphotoxin (LT)-alpha and LTbeta, are proinflammatory cytokines associated with pathology in rheumatoid arthritis. LTalpha3 homotrimers are secreted, whereas LTalpha(1)beta(2) heterotrimers are expressed on the surface of activated lymphocytes. As many TNF-SF members are actively cleaved from cell membranes, we determined whether LTalphabeta heterotrimers are also cleaved, and are biologically active in rheumatoid arthritis (RA) patients. LTalphabeta heterotrimers were detected in culture supernatants from activated human T-helper (Th) 0, Th1, and Th17 cells, together with LTalpha3 and TNFalpha. The heterotimers were actively cleaved from the cell surface by ADAM17 metalloproteinase (MMP) and MMP-8, and cleavage was inhibited by TAPI-1, a TNF-alpha converting enzyme (TACE) inhibitor. Soluble LTalphabeta was detected in serum from both normal donors and RA patients, and was elevated in synovial fluid from RA patients compared to osteoarthritis (OA) patients. Levels of LTalphabeta in RA patient synovial fluid correlated with increased TNFalpha, IL-8, IL-12, IL-1beta, IFN-gamma, and IL-6 cytokines. Moreover, recombinant LTalpha1beta2-induced CXCL1, CXCL2, IL-6, IL-8, VCAM-1, and ICAM-1 from primary synovial fibroblasts isolated from RA patients. Therefore, soluble LTalphabeta in synovial fluid is associated with a proinflammatory cytokine milieu that contributes to synovitis in RA.
Assuntos
Artrite Reumatoide/complicações , Artrite Reumatoide/enzimologia , Heterotrímero de Linfotoxina alfa1 e beta2/metabolismo , Metaloproteases/metabolismo , Sinovite/complicações , Sinovite/enzimologia , Idoso , Idoso de 80 Anos ou mais , Artrite Reumatoide/sangue , Moléculas de Adesão Celular/metabolismo , Quimiocinas/metabolismo , Demografia , Feminino , Fibroblastos/metabolismo , Fibroblastos/patologia , Humanos , Ativação Linfocitária/imunologia , Heterotrímero de Linfotoxina alfa1 e beta2/sangue , Masculino , Pessoa de Meia-Idade , Solubilidade , Líquido Sinovial/metabolismo , Sinovite/patologia , Linfócitos T/enzimologia , Linfócitos T/imunologiaRESUMO
OBJECTIVES: The interferon (IFN) signature (IS) in patients with systemic lupus erythematosus (SLE) includes over 100 genes induced by type I IFN pathway activation. We developed a method to quantify the IS using three genes-the IS metric (ISM)-and characterised the clinical characteristics of patients with SLE with different ISM status from multiple clinical trials. METHODS: Blood microarray expression data from a training cohort of patients with SLE confirmed the presence of the IS and identified surrogate genes. We assayed these genes in a quantitative PCR (qPCR) assay, yielding an ISM from the IS. The association of ISM status with clinical disease characteristics was assessed in patients with extrarenal lupus and lupus nephritis from four clinical trials. RESULTS: Three genes, HERC5, EPSTI and CMPK2, correlated well with the IS (p>0.96), and composed the ISM qPCR assay. Using the 95th centile for healthy control data, patients with SLE from different studies were classified into two ISM subsets-ISM-Low and ISM-High-that are longitudinally stable over 36â weeks. Significant associations were identified between ISM-High status and higher titres of anti-dsDNA antibodies, presence of anti extractable nuclear antigen autoantibodies, elevated serum B cell activating factor of the tumour necrosis factor family (BAFF) levels, and hypocomplementaemia. However, measures of overall clinical disease activity were similar for ISM-High and ISM-Low groups. CONCLUSIONS: The ISM is an IS biomarker that divides patients with SLE into two subpopulations-ISM-High and ISM-Low-with differing serological manifestations. The ISM does not distinguish between high and low disease activity, but may have utility in identifying patients more likely to respond to treatment(s) targeting IFN-α. CLINICALTRIALSGOV REGISTRATION NUMBER: NCT00962832.
RESUMO
An important goal for personalized health care is the identification of biomarkers that predict the likelihood of treatment responses. Here, we tested the hypothesis that quantitative mRNA assays for B lineage cells in blood could serve as baseline predictors of therapeutic response to B cell depletion therapy in subjects with rheumatoid arthritis (RA). In samples from the REFLEX trial of rituximab in inadequate responders to antibodies to tumor necrosis factor-α, a 25% subgroup of treated subjects with elevated baseline mRNA levels of IgJ, a marker for antibody-secreting plasmablasts, showed reduced clinical response rates. There were no significant efficacy differences in the placebo arm subjects stratified by this marker. Prospective testing of the IgJ biomarker in the DANCER and SERENE rituximab clinical trial cohorts and the SCRIPT ocrelizumab cohort confirmed the utility of this marker to predict nonresponse to anti-CD20 therapy. A combination mRNA biomarker, IgJhiFCRL5lo, showed improved test performance over IgJhi alone. This study demonstrates that baseline blood levels of molecular markers for late-stage B lineage plasmablasts identify a ~20% subgroup of active RA subjects who are unlikely to gain substantial clinical benefit from anti-CD20 B cell depletion therapy.
Assuntos
Anticorpos Monoclonais Murinos/uso terapêutico , Antígenos CD20/imunologia , Artrite Reumatoide/tratamento farmacológico , Artrite Reumatoide/imunologia , Plasmócitos/imunologia , Biomarcadores/sangue , Linhagem da Célula/genética , Estudos de Coortes , Demografia , Feminino , Humanos , Cadeias J de Imunoglobulina/genética , Cadeias J de Imunoglobulina/metabolismo , Masculino , Pessoa de Meia-Idade , RNA Mensageiro/sangue , RNA Mensageiro/genética , Receptores de Superfície Celular/imunologia , Receptores Fc , Reação em Cadeia da Polimerase Via Transcriptase Reversa , Rituximab , Resultado do TratamentoRESUMO
Systemic Lupus Erythematosus (SLE) is a systemic autoimmune disease with a complex spectrum of cellular and molecular characteristics including several dramatic changes in the populations of peripheral leukocytes. These changes include general leukopenia, activation of B and T cells, and maturation of granulocytes. The manifestation of SLE in peripheral blood is central to the disease but is incompletely understood. A technique for rigorously characterizing changes in mixed populations of cells, microarray expression deconvolution, has been applied to several areas of biology but not to SLE or to blood. Here we demonstrate that microarray expression deconvolution accurately quantifies the constituents of real blood samples and mixtures of immune-derived cell lines. We characterize a broad spectrum of peripheral leukocyte cell types and states in SLE to uncover novel patterns including: specific activation of NK and T helper lymphocytes, relationships of these patterns to each other, and correlations to clinical variables and measures. The expansion and activation of monocytes, NK cells, and T helper cells in SLE at least partly underlie this disease's prominent interferon signature. These and other patterns of leukocyte dynamics uncovered here correlate with disease severity and treatment, suggest potential new treatments, and extend our understanding of lupus pathology as a complex autoimmune disease involving many arms of the immune system.
Assuntos
Lúpus Eritematoso Sistêmico/sangue , Ativação Linfocitária , Linfócitos B/imunologia , Estudos de Casos e Controles , Humanos , Lúpus Eritematoso Sistêmico/imunologia , Linfócitos T/imunologiaRESUMO
Although it is established that failure of regulatory mechanisms underlies many autoimmune diseases, the stimuli that activate autoreactive lymphocytes remain poorly understood. Defining these stimuli will lead to therapeutic strategies for autoimmune diseases. IL-2-deficient mice develop spontaneous autoimmunity, because of a deficiency of regulatory T cells, and on the BALB/c background, they rapidly die from autoimmune hemolytic anemia. To define the importance of costimulatory pathways in various components of this autoimmune disorder, we first intercrossed IL-2-deficient mice with mice lacking CD28 or CD40L. Elimination of CD28 reduced the activation of autoreactive T cells and lymphoproliferation as well as production of autoantibodies, whereas elimination of CD40L reduced autoantibody production without affecting T cell expansion and accumulation. To examine the role of IL-7, we blocked IL-7R signaling with neutralizing Abs. This treatment inhibited the production of autoantibodies and the development of autoimmune hemolytic anemia. Together, these data indicate that specific costimulatory and cytokine signals are critical for the spontaneous autoantibody-mediated disease that develops in IL-2-deficient mice.