RESUMEN
OBJECTIVE: Inflammation and innate immune responses may contribute to development and progression of Osteoarthritis (OA). Chondrocytes are the sole cell type of the articular cartilage and produce extracellular-matrix molecules. How inflammatory mediators reach chondrocytes is incompletely understood. Previous studies have shown that chondrocytes express mRNA encoding complement proteins such as C1q, suggesting local protein production, which has not been demonstrated conclusively. The aim of this study is to explore C1q production at the protein level by chondrocytes. DESIGN: We analysed protein expression of C1q in freshly isolated and cultured human articular chondrocytes using Western blot, ELISA and flow cytometry. We examined changes in mRNA expression of collagen, MMP-1 and various complement genes upon stimulation with pro-inflammatory cytokines or C1q. mRNA expression of C1 genes was determined in articular mouse chondrocytes. RESULTS: Primary human articular chondrocytes express genes encoding C1q, C1QA, C1QB, C1QC, and secrete C1q to the extracellular medium. Stimulation of chondrocytes with pro-inflammatory cytokines upregulated C1QA, C1QB, C1QC mRNA expression, although this was not confirmed at the protein level. Extracellular C1q bound to the chondrocyte surface dose dependently. In a pilot study, binding of C1q to chondrocytes resulted in changes in the expression of collagens with a decrease in collagen type 2 and an increase in type 10. Mouse articular chondrocytes also expressed C1QA, C1QB, C1QC, C1R and C1S at the mRNA level. CONCLUSIONS: C1q protein can be expressed and secreted by human articular chondrocytes and is able to bind to chondrocytes influencing the relative collagen expression.
Asunto(s)
Condrocitos/metabolismo , Complemento C1q/genética , Complemento C1r/genética , Complemento C1s/genética , Osteoartritis de la Rodilla/genética , ARN Mensajero/metabolismo , Animales , Cartílago Articular/citología , Colágeno Tipo II/genética , Colágeno Tipo X/genética , Regulación de la Expresión Génica , Humanos , Ratones , Osteoartritis de la Rodilla/metabolismo , Proyectos PilotoAsunto(s)
Artritis Reumatoide/inmunología , Autoanticuerpos/inmunología , Biomarcadores/sangre , Carbamatos/inmunología , Adulto , Anciano , Animales , Artritis Reumatoide/fisiopatología , Autoantígenos/inmunología , Estudios de Casos y Controles , Progresión de la Enfermedad , Ensayo de Inmunoadsorción Enzimática , Femenino , Humanos , Masculino , Persona de Mediana Edad , Valores de Referencia , Insuficiencia Renal/sangre , Insuficiencia Renal/fisiopatología , Sensibilidad y Especificidad , Fumar/sangre , Fumar/fisiopatologíaRESUMEN
Rodent models for arthritis implicate a role for complement in disease development and progression. In humans, complement deposition has been observed in inflamed synovia of rheumatoid arthritis (RA) patients. In this study we analysed whether genetic variants of complement component C1q predispose to RA. We genotyped single nucleotide polymorphisms (SNPs) in and around the C1q genes, C1qA, C1qB and C1qC, in a Dutch set of 845 RA cases and 1046 controls. Replication was sought in a sample set from North America (868 cases/1193 controls), and a meta-analysis was performed in a combined samples set of 8000 cases and 23 262 controls of European descent. We determined C1q serum levels in relation to C1q genotypes. In the discovery phase, five of the 13 SNPs tested in the C1q genes showed a significant association with RA. Additional analysis of the genomic area around the C1q genes revealed that the strongest associating SNPs were confined to the C1q locus. Within the C1q locus we observed no additional signal independent of the strongest associating SNP, rs292001 [odds ratio (OR) = 0·72 (0·58-0·88), P = 0·0006]. The variants of this SNP were associated with different C1q serum levels in healthy controls (P = 0·006). Interestingly, this SNP was also associated significantly in genome-wide association studies (GWAS) from the North American Rheumatoid Arthritis Consortium study, confirming the association with RA [OR = 0·83 (0·69-1·00), P = 0·043]. Combined analysis, including integrated data from six GWAS studies, provides support for the genetic association. Genetic variants in C1q are correlated with C1q levels and may be a risk for the development of RA.
Asunto(s)
Artritis Reumatoide/genética , Complemento C1q/genética , Polimorfismo de Nucleótido Simple , Artritis Reumatoide/epidemiología , Canadá/epidemiología , Estudios de Cohortes , Predisposición Genética a la Enfermedad , Estudio de Asociación del Genoma Completo , Genotipo , Grecia/epidemiología , Humanos , Países Bajos/epidemiología , ARN Mensajero/genética , Receptor EphA8/genética , Receptor EphB2/genética , Estados Unidos/epidemiologíaRESUMEN
OBJECTIVE: It has been suggested that anti-citrullinated protein antibodies (ACPAs) play an important role in the pathogenesis of rheumatoid arthritis (RA). To exert their pathologic effects, ACPAs must recruit immune effector mechanisms such as activation of the complement system. Mouse models of RA have shown that, surprisingly, arthritogenic antibodies activate the alternative pathway of complement rather than the expected classical pathway. This study was undertaken to investigate whether human anti-cyclic citrullinated peptide (anti-CCP) antibodies activate the complement system in vitro and, if so, which pathways of complement activation are used. METHODS: We set up novel assays to analyze complement activation by anti-CCP antibodies, using cyclic citrullinated peptide-coated plates, specific buffers, and normal and complement-deficient sera as a source of complement. RESULTS: Anti-CCP antibodies activated complement in a dose-dependent manner via the classical pathway of complement, and, surprisingly, via the alternative pathway of complement. The lectin pathway was not activated by anti-CCP antibodies. Complement activation proceeded in vitro up to the formation of the membrane attack complex, indicating that all activation steps, including the release of C5a, took place. CONCLUSION: Our findings indicate that anti-CCP antibodies activate the complement system in vitro via the classical and alternative pathways but not via the lectin pathway. These findings are relevant for the design of interventions aimed at inhibition of complement-mediated damage in RA.
Asunto(s)
Anticuerpos Antiidiotipos/metabolismo , Artritis Reumatoide/metabolismo , Proteínas del Sistema Complemento/metabolismo , Péptidos Cíclicos/inmunología , Transducción de Señal/fisiología , Adolescente , Adulto , Anciano , Anciano de 80 o más Años , Artritis Reumatoide/inmunología , Estudios de Casos y Controles , Estudios de Cohortes , Complemento C1q/metabolismo , Complemento C5a/metabolismo , Complejo de Ataque a Membrana del Sistema Complemento/metabolismo , Femenino , Humanos , Lectinas/metabolismo , Masculino , Lectina de Unión a Manosa/metabolismo , Persona de Mediana Edad , Adulto JovenRESUMEN
OBJECTIVE: To investigate the clinical effects of rituximab treatment in relation to immunological effects of rituximab on tissue-derived B lineage cells and repopulation of circulating B cells. METHODS: A total of 24 patients with rheumatoid arthritis (RA) were treated with 2x1000 mg rituximab and assessed clinically at 4, 12, 18 and 24 weeks using a 44-joint Disease Activity Score (DAS(44)). Synovial biopsies were analysed with immunohistochemistry at baseline and 12 weeks after treatment. Peripheral blood mononuclear cells were analysed by high sensitivity flow cytometry at all timepoints. RESULTS: In this study, a cohort of patients was dichotomised according to those who achieved a low disease activity score (DAS(44)<2.4: LoA group) and those with persistent disease activity (DAS(44)>2.4: HiA group) at any time after rituximab treatment. At baseline, the low activity (LoA) group had significantly lower DAS(44) scores (median 3.33, range 2.84 to 4.23) than the high activity (HiA) group (median 3.73, range 3.03 to 5.23; p = 0.022) and significantly less histological inflammation in synovium (median 6.7, range 1 to 15 vs 16.6, range 4 to 22; p = 0.036). DAS(44) scores before and after rituximab treatment were associated with synovial infiltration of CD79a+ CD20- B cells, morphologically resembling plasma cells. Following treatment with rituximab, the LoA group had significantly reduced repopulation of circulating pre-switched IgD+ B cells (median 0.044%, range 0.002 to 0.66 vs 0.45%, range 0.07 to 9.47; p = 0.006) and post-switched CD27+ B cells (median 0.17%, range 0.04 to 0.39 vs 0.67, range 0.08 to 2.05; p = 0.005) compared to the HiA group. CONCLUSION: The present study demonstrated that a low disease activity state following rituximab was associated with reduced infiltration of CD79a+ CD20- plasma cells in synovium and reduced B cell repopulation.
Asunto(s)
Anticuerpos Monoclonales/uso terapéutico , Antirreumáticos/uso terapéutico , Artritis Reumatoide/tratamiento farmacológico , Artritis Reumatoide/inmunología , Linfocitos B/inmunología , Membrana Sinovial/inmunología , Adulto , Anciano , Anciano de 80 o más Años , Anticuerpos Monoclonales de Origen Murino , Antígenos CD20/análisis , Artritis Reumatoide/patología , Linfocitos B/patología , Antígenos CD79/análisis , Proliferación Celular , Femenino , Citometría de Flujo , Estudios de Seguimiento , Humanos , Inmunohistoquímica , Recuento de Linfocitos , Masculino , Persona de Mediana Edad , Células Plasmáticas/inmunología , Células Plasmáticas/patología , Rituximab , Índice de Severidad de la Enfermedad , Membrana Sinovial/patología , Insuficiencia del TratamientoRESUMEN
OBJECTIVE: To compare synovial tissue infiltrates from patients with anti-cyclic citrullinated peptide (anti-CCP)-positive rheumatoid arthritis (RA) with those from patients with anti-CCP-negative RA. METHODS: Synovial tissue samples were obtained arthroscopically from the inflamed knee joints of 57 patients with RA (34 of whom were anti-CCP positive) and examined for several histologic features along with immunohistologic expression of cell markers. Joint damage was assessed using the Kellgren/Lawrence (K/L) scale (range 0-4) on standard anteroposterior radiographs. In 31 patients (18 of whom were anti-CCP positive), synovial tissue was available from an earlier time point, allowing analysis of temporal changes. RESULTS: Synovial tissue from anti-CCP-positive patients was characterized by a higher mean number of infiltrating lymphocytes (61.6 versus 31.4/high-power field [hpf] [400x]; P=0.01), less extensive fibrosis (mean score of 1.2 versus 2.0; P=0.04), and a thinner synovial lining layer (mean score of 2.1 versus 3.3; P=0.002) compared with synovial tissue from anti-CCP-negative patients. Anti-CCP-positive patients expressed more CD3, CD8, CD45RO, and CXCL12. More anti-CCP-positive patients had a K/L score >1 compared with anti-CCP-negative patients. The difference in the mean lymphocyte counts was already present a mean of 3.8 years before the index biopsy (76.7 lymphocytes/hpf and 26.7 lymphocytes/hpf in anti-CCP-positive patients and anti-CCP-negative patients, respectively; P=0.008) and was independent of disease duration and K/L score. CONCLUSION: Synovitis in patients with anti-CCP-positive RA differs from that in patients with anti-CCP- negative RA, notably with respect to infiltrating lymphocytes, and is associated with a higher rate of local joint destruction.
Asunto(s)
Artritis Reumatoide/metabolismo , Artritis Reumatoide/patología , Péptidos Cíclicos/metabolismo , Sinovitis/metabolismo , Sinovitis/patología , Adulto , Anciano , Artritis Reumatoide/inmunología , Femenino , Fibrosis , Humanos , Inmunohistoquímica , Linfocitos/patología , Masculino , Persona de Mediana Edad , Osteoartritis/inmunología , Osteoartritis/metabolismo , Osteoartritis/patología , Péptidos Cíclicos/inmunología , Membrana Sinovial/inmunología , Membrana Sinovial/metabolismo , Membrana Sinovial/patología , Sinovitis/inmunologíaRESUMEN
BACKGROUND: Immunoablative therapy combined with haematopoietic stem cell transplantation (SCT) is a possible treatment for patients with severe rheumatoid arthritis (RA). CASE REPORT: A patient with rheumatoid factor positive, progressively erosive RA, refractive to treatment, was treated with high dose cyclophosphamide, followed by reinfusion of an unmanipulated peripheral blood graft derived from her identical twin sister. The clinical response was unsatisfactory, necessitating reinstitution of treatment with disease modifying antirheumatic drugs, which was associated with persistence of host serum autoantibodies and a cellular infiltrate in synovium, notably of plasma cells. DISCUSSION: The effectiveness of syngeneic SCT may be critically dependent on the degree of immunoablation achieved or on the composition of the graft.
Asunto(s)
Antirreumáticos/uso terapéutico , Artritis Reumatoide/terapia , Autoanticuerpos/sangre , Trasplante de Células Madre Hematopoyéticas , Membrana Sinovial/patología , Adulto , Artritis Reumatoide/inmunología , Artritis Reumatoide/patología , Ciclofosfamida/uso terapéutico , Femenino , Humanos , Inmunosupresores/uso terapéutico , Insuficiencia del TratamientoRESUMEN
BACKGROUND: Tumour necrosis alpha (TNF alpha) blocking agents lead to pronounced clinical effects and reduced synovial infiltrate in rheumatoid arthritis. Laboratory and clinical studies suggest that TNF alpha independent pathways play a role in the disease. OBJECTIVES: To evaluate the immunopathological effects of combination therapy on rheumatoid synovial tissue in order to identify TNF alpha independent mechanisms. METHODS: 12 rheumatoid patients, including four DMARD (disease modifying antirheumatic drug) naive patients with early disease, were studied for the effect of combination therapy with infliximab and methotrexate on the synovial infiltrate. Biopsies and clinical assessments (DAS28) were carried out before the first and after the third infusion of infliximab. Synovial inflammation was scored semiquantitatively. Co-expression of CD38(+) cells was studied by an immunofluorescent double labelling technique. RESULTS: Marked clinical responses were associated with a global reduction in the synovial infiltrate and expression of cytokines, notably interleukin 18 and TNF alpha, but low grade disease activity persisted. There was no effect on the expression of CXC chemokine ligand (CXCL12), and germinal centre-like structures were still detectable in synovial tissue in two patients after treatment. CD38(+) activated T cells were more resistant to treatment than CD38(+) plasma cells. No differences in clinical response or effects on synovial infiltrate were observed between DMARD refractory and DMARD naive patients. CONCLUSIONS: Persistent expression of CXCL12 and incomplete resolution of lymphocytic infiltrates after infliximab plus methotrexate indicates that TNF alpha independent mechanisms are operative in rheumatoid arthritis. This may contribute to low grade disease activity, even in DMARD naive patients with early disease.