RESUMO
We previously reported that synovial mast cells (MCs) from patients with rheumatoid arthritis (RA) produced TNF-α in response to immune complexes via FcγRI and FcγRIIA. However, the specific functions of synovial MCs in RA remain unclear. This study aimed to elucidate those functions. Synovial tissues and fluid were obtained from RA and osteoarthritis (OA) patients undergoing joint replacement surgery. Synovium-derived, cultured MCs were generated by culturing dispersed synovial cells with stem cell factor. We performed microarray-based screening of mRNA and microRNA (miRNA), followed by quantitative RT-PCR-based verification. Synovial MCs from RA patients showed significantly higher prostaglandin systhetase (PTGS)1 and PTGS2 expression compared with OA patients' MCs, and they produced significantly more prostaglandin D2 (PGD2) following aggregation of FcγRI. PGD2 induced IL-8 production by human group 2 innate lymphoid cells, suggesting that PGD2-producing MCs induce neutrophil recruitment into the synovium of RA patients. PTGS2 mRNA expression in RA patients' MCs correlated inversely with miRNA-199a-3p expression, which down-regulated PTGS2. RA patients' synovial fluid contained significantly more PGD2 compared with OA patients' fluid. Synovial MCs might regulate inflammation in RA through hyper-production of PGD2 following FcRγ aggregation. Our findings indicate functional heterogeneity of human MCs among diseases.
Assuntos
Artrite Reumatoide/patologia , Ciclo-Oxigenase 2/metabolismo , Mastócitos/metabolismo , MicroRNAs/metabolismo , Osteoartrite/patologia , Prostaglandina D2/biossíntese , Transdução de Sinais , Membrana Sinovial/patologia , Idoso , Idoso de 80 Anos ou mais , Artrite Reumatoide/genética , Células Cultivadas , Ciclo-Oxigenase 1/genética , Ciclo-Oxigenase 1/metabolismo , Ciclo-Oxigenase 2/genética , Dinoprostona/metabolismo , Feminino , Fibroblastos/metabolismo , Perfilação da Expressão Gênica , Regulação da Expressão Gênica , Liberação de Histamina , Humanos , Imunidade Inata , Interleucina-8/biossíntese , Linfócitos/metabolismo , Masculino , Pessoa de Meia-Idade , Osteoartrite/genética , RNA Mensageiro/genética , RNA Mensageiro/metabolismo , Receptores de IgG/metabolismo , Líquido Sinovial/metabolismoRESUMO
BACKGROUND: Neural pathways are thought to be directly involved in the pathogenesis of rheumatoid arthritis (RA). Although synovial mast cells (MCs) are activated by substance P (SP), the role of MCs in neural pathways in RA remains unknown. The aims of this study were to investigate 1) whether tachykinins are produced by synovial MCs and whether production differs in RA and osteoarthritis (OA) patients, and 2) what is the responsible receptor for SP in synovial MCs. METHODS: Synovial tissues were obtained from patients with RA or OA undergoing joint replacement surgery. Cultured synovium-derived MCs were generated by culturing dispersed synovial cells with stem cell factor. SP expression was investigated using immunofluorescence and enzyme immunoassays. Mas-related gene X2 (MrgX2) expression was reduced in human MCs using a lentiviral shRNA silencing technique. RESULTS: SP expression was localized around the cell membrane in 41% (median) of the MCs in synovium from RA but in only 7% of that from OA, suggesting the activation of MCs. Synovial MCs expressed tachykinin (TAC) 1 mRNA, the expression of which was upregulated by the aggregation of FcÉRI or the addition of aggregated IgG. However, the released SP appeared to be rapidly degraded by MC chymase. Synovial MCs were activated with SP through MrgX2 to release histamine without producing proinflammatory cytokines. CONCLUSIONS: Activated synovial MCs may rapidly degrade SP, which may downregulate the SP-mediated activation of synoviocytes in RA. On the other hand, SP activates MCs to induce inflammatory mediators, suggesting the dual regulation of SP-mediated inflammation by MCs in RA.
Assuntos
Artrite Reumatoide/imunologia , Artrite Reumatoide/metabolismo , Mastócitos/imunologia , Mastócitos/metabolismo , Substância P/metabolismo , Sinoviócitos/imunologia , Sinoviócitos/metabolismo , Adulto , Idoso , Idoso de 80 Anos ou mais , Artrite Reumatoide/genética , Artrite Reumatoide/patologia , Biomarcadores , Células Cultivadas , Citocinas/metabolismo , Feminino , Imunofluorescência , Expressão Gênica , Humanos , Mediadores da Inflamação/metabolismo , Masculino , Pessoa de Meia-Idade , Osteoartrite/imunologia , Osteoartrite/metabolismo , Osteoartrite/patologia , RNA Mensageiro/genética , RNA Mensageiro/metabolismoRESUMO
BACKGROUND: Interleukin (IL)-17A plays a pivotal role in the pathogenesis of rheumatoid arthritis (RA). The expression of IL-17A in synovial mast cells (MCs) in RA and osteoarthritis (OA) has been reported, but the frequencies of IL-17A expression in synovial MCs have varied. The aim of this study was to investigate whether IL-17A expression is upregulated in human synovial MCs in RA and to elucidate the mechanism of IL-17A expression in synovial MCs. METHODS: Synovial tissues were obtained from patients with RA or OA undergoing joint replacement surgery, and synovial MCs were enzymatically dispersed. Synovium-derived cultured MCs were generated by culturing synovial cells with stem cell factor. IL-17A expression was investigated using immunofluorescence in synovial tissues. IL-17A mRNA expression and its production from MCs were examined using RT-PCR and ELISA, respectively. RESULTS: The number of IL-17A-positive ((+)) synovial MCs and the percentage of IL-17A(+) MCs among all the IL-17A(+) cells from RA patients were not significantly increased compared with those from OA subjects. The synovium-derived cultured MCs spontaneously released small amounts of IL-17A. Neither IgE- nor IgG-dependent stimulation increased IL-17A production from the MCs. IL-33, tumor necrosis factor-α, C5a, lipopolysaccharide or IL-23 plus IL-1ß did not affect IL-17A production in MCs. CONCLUSIONS: The synovial MCs are not a main source of IL-17A in RA.
