Jun-feng Jia

Contribution of Cyclophilin A to the Regulation of Inflammatory Processes in Rheumatoid Arthritis

IntroductionPrevious studies show that cyclophilin A (CypA) acts as a strong chemotactic cytokine to neutrophils, eosinophils, and monocytes in rheumatoid arthritis (RA).MethodsIn this study, monocytes were stimulated by purified CypA and the production of matrix metalloproteinase (MMPs), the cell invasion and the release of inflammatory cytokines were detected respectively by gelatin zymography, invasion assay, and cytometric bead array FCM.ResultsThe elevated level of inflammatory cytokine IL-8 was also detected. Results showed that CypA significantly promoted the invasion of THP-1 cells and increased the production of MMP-2 and MMP-9, which displayed a biphasic concentration dependency. In vivo experiments found that the cartilage erosion scores in CypA injection group were significantly higher than those in control group (P < 0.05).ConclusionOur findings suggest that CypA significantly enhances the secretion of MMP-2 and MMP-9, the cell invasion, and the inflammatory cytokines production of monocytes. Our findings may shed some new light on the inflammatory process and the degradation of cartilage and bone in RA.

Expression of CD147 (EMMPRIN) on neutrophils in rheumatoid arthritis enhances chemotaxis, matrix metalloproteinase production and invasiveness of synoviocytes

The occurrence of neutrophils at the pannus‐cartilage border is an important phenomenon for understanding the pathogenesis of rheumatoid arthritis (RA). Matrix metalloproteinases (MMPs) are predominant enzymes responsible for the cartilage degradation. The present article studied the expression of CD147 on neutrophils and its potential role in neutrophil chemotaxis, MMPs production and the invasiveness of fibroblast‐like synoviocytes (FLS). The results of flow cytometry revealed that the mean fluorescence intensity of CD147 expression on neutrophils of peripheral blood from RA patients was higher than that in healthy individual. The potential role of CD147 in cyclophilin A (CyPA)‐mediated cell migration was studied using chemotaxis assay and it was found that the addition of anti‐CD147 antibody significantly decreased the chemotactic index of the neutrophils. Significantly elevated release and activation of MMPs were seen in the co‐culture of neutrophil and FLS compared with cultures of the cells alone. An increased number of cells invading through the filters in the invasion assays were also observed in the co‐cultured cells. The addition of anti‐CD147 antibody had some inhibitory effect, not only on MMP production but also on cell invasion in the co‐culture model. Our study demonstrates that the increased expression of CD147 on neutrophils in RA may be responsible for CyPA‐mediated neutrophil migration into the joints, elevated MMPs secretion and cell invasion of synoviocytes, all of which may contribute to the cartilage invasion and bone destruction of RA. Better knowledge of these findings will hopefully provide a new insight into the pathogenesis of RA.

CD147 induces angiogenesis through a vascular endothelial growth factor and hypoxia-inducible transcription factor 1α–mediated pathway in rheumatoid arthritis

OBJECTIVE Rheumatoid arthritis (RA) is an inflammatory and angiogenic disease. However, the molecular mechanisms that promote angiogenesis in RA have not been clearly identified. Our objective was to study the role of CD147 in angiogenesis and determine whether the strategy in which CD147 is suppressed might be useful in reducing angiogenesis in RA. METHODS Correlations among expression levels of CD147, vascular endothelial growth factor (VEGF), and hypoxia-inducible factor 1α (HIF-1α) were determined by immunohistochemistry staining. RA fibroblast-like synoviocytes (FLS) cells were cultured under various conditions, and the production of VEGF and HIF-1α was examined by real-time polymerase chain reaction and enzyme-linked immunosorbent assay. The SCID mouse coimplantation model of RA (SCID-HuRAg) was established, mice were treated with CD147 monoclonal antibody, infliximab, or both CD147 and infliximab, and the volume of the grafts and the average vascular density were measured and analyzed. Western blot analyses were performed to examine the potential signaling pathways. RESULTS The expression levels of CD147 showed significantly positive correlations with VEGF and HIF-1α levels, as well as with vascular density, in RA synovium. After small interfering RNA transfection or after addition of specific antibodies for CD147, the production of VEGF and HIF-1α were significantly reduced. The expression of VEGF and HIF-1α decreased more after CD147 inhibition than after infliximab treatment in the engrafted tissues in SCID-HuRAg mice. The phosphatidylinositol 3-kinase/Akt pathway may be involved in this process. CONCLUSION CD147 induces up-regulation of VEGF and HIF-1α in RA FLS, further promotes angiogenesis, and leads to the persistence of synovitis. Inhibition of CD147 may be a promising target for novel therapeutic strategies.

Inhibitory effect of CD147/HAb18 monoclonal antibody on cartilage erosion and synovitis in the SCID mouse model for rheumatoid arthritis

OBJECTIVE To explore the therapeutic potential of CD147/HAb18 mAb in the treatment of RA in severe combined immunodeficiency (SCID) mice engrafted with human cartilage and rheumatoid synovium tissue (SCID-HuRAg). METHODS SCID-HuRAg mice were treated separately with CD147/HAb18 mAb, anti-TNF-alpha mAb or a combination of both. The mice in control group were treated with anti-Japanese encephalitis virus mAb. The volume of engrafts was measured and the number of inflammatory cells and cartilage erosion score were examined. Expression of MMP-2, -3 and -9 was determined by immunohistochemistry. Human inflammatory cytokine levels in mouse sera were assessed using cytometric bead array kit. RESULTS The volume of engrafts decreased significantly in SCID-HuRAg mice treated separately with anti-CD147 mAb or anti-TNF-alpha mAb, and in the mice treated with anti-CD147 mAb plus anti-TNF-alpha mAb (P < 0.05). Significant reduction was observed in cartilage erosion score in anti-CD147 treatment group and combined treatment group (P < 0.05). Immunohistochemical analysis showed that expression of MMP-2, -3 and -9 was lower in the anti-CD147 treatment group and combined treatment group than in the control mAb group (P < 0.05). Moreover, the level of TNF-alpha, IL-6 and -8 in CD147 mAb group showed a significant decrease compared with that of the control mAb group (P < 0.05). CONCLUSIONS CD147/HAb18 mAb can reduce cartilage erosion and synovitis by inhibition of the MMPs and reduction of inflammatory cytokines in SCID-HuRAg mice, which suggests that CD147/HAb18 mAb is a promising treatment option for RA patients.

CD147 up-regulates calcium-induced chemotaxis, adhesion ability and invasiveness of human neutrophils via a TRPM-7-mediated mechanism

OBJECTIVES We aimed to investigate whether CD147 can up-regulate the chemotactic, adhesive and invasive properties of human neutrophils and to determine the mechanism underlying this process. METHODS Human promyelocytic leukaemia cells (HL-60) cells and peripheral blood or synovial fluid neutrophils were isolated from RA patients. Under cyclophilin A (CypA) stimulation, chemotaxis, adhesion potential and invasion ability were assessed using chemotaxis, adhesion and invasiveness assays. Lipid raft isolation and western blot were used to determine the mechanism underlying the effects of CypA stimulation. RESULTS CD147 up-regulates the calcium-induced chemotaxis, adhesion ability and invasiveness of human neutrophils in RA patients. Transient receptor potential melastatin 7 may be responsible for this phenomenon. CONCLUSION These findings suggest that in RA patients, abundant CypA up-regulates the calcium-induced chemotactic, adhesive and invasive properties of neutrophils via direct binding to CD147. Cyclophilin-CD147 interactions might contribute to the destruction of cartilage and bone in RA.

Platelets induce a proinflammatory phenotype in monocytes via the CD147 pathway in rheumatoid arthritis

IntroductionActivated platelets exert a proinflammatory action that can be largely ascribed to their ability to interact with monocytes. However, the mechanisms that promote dynamic changes in monocyte subsets in rheumatoid arthritis (RA) have not been clearly identified. The aim of this study was to determine whether platelet activation and the consequent formation of monocyte-platelet aggregates (MPA) might induce a proinflammatory phenotype in circulating monocytes in RA.MethodsThe surface phenotype of platelets and the frequencies of monocyte subpopulations in the peripheral blood of RA patients were determined using flow cytometry. Platelets were sorted and co-cultured with monocytes. In addition, monocyte activation was assessed by measuring the nuclear factor kappa B (NF-κB) pathway. The disease activity was evaluated using the 28-joint disease activity score.ResultsPlatelet activation, circulating intermediate monocytes (Mon2) and MPA formation were significantly elevated in RA, especially in those with active disease status. Furthermore, Mon2 monocytes showed higher CD147 expression and responded to direct cell contact with activated platelets with higher cytokine production and matrix metallopeptidase 9 (MMP-9) secretion, which increased the expression of CD147. After the addition of specific antibodies for CD147, those effects were abolished. Furthermore, the NF-κB-driven inflammatory pathway may be involved in this process.ConclusionsThese findings indicate an important role of platelet activation and the consequent formation of MPA in the generation of the proinflammatory cytokine milieu and for the promotion and maintenance of the pathogenically relevant Mon2 monocyte compartment in RA, which is likely to play an important role in the pathogenesis of autoimmunity.