Liping Xia

Elevated serum and synovial fluid levels of interleukin-34 in rheumatoid arthritis: possible association with disease progression via interleukin-17 production.

To measure the levels of interleukin-34 (IL-34) in serum and synovial fluid (SF) of patients with rheumatoid arthritis (RA) and to evaluate the effect of recombination human (rh) IL-34 on IL-17 production by peripheral blood mononuclear cells (PBMC) in RA patients, the serum and SF levels of IL-34, and the production of IL-17 by rhIL-34-treated PBMC of RA patients were measured by enzyme-linked immunosorbent assay. We also tested the change of IL-34 level after tumor necrosis factor (TNF)-α blockade therapy in 30 RA patients. In contrast to almost no detectable IL-34 in osteoarthritis (OA) and healthy serum, IL-34 could be detected in 93 out of the 125 RA cases (74.4%). Sera IL-34 levels were significantly higher in RA patients compared with the controls and correlated with disease activity. IL-34 levels were higher in SF samples than in sera in 11 RA patients. The level of serum IL-34 decreased after anti-TNF treatment. In the presence of rhIL-34, stimulation of PBMC from RA patients resulted in increased production of IL-17. These findings suggest that IL-34 may play a role in the pathogenesis of RA.

Infliximab Reduces the Frequency of Interleukin 17-Producing Cells and the Amounts of Interleukin 17 in Patients With Rheumatoid Arthritis

Background To detect frequency changes in interleukin 17 (IL-17)+ CD4+ T cells and the amounts of IL-17 in supernatants between baseline and 30 weeks after Infliximab combined with methotrexate (MTX) or MTX-alone therapy. Methods Flow cytometry was used to analyze the frequency of IL-17+ CD4+ T cells in rheumatoid arthritis (RA) patients and control subjects at baseline and 30 weeks after therapy. Secretion of IL-17 by peripheral blood mononuclear cells was measured by enzyme-linked immunosorbent assay. Results The percentages of IL-17+ CD4+T cells were increased in the peripheral blood mononuclear cells of patients with RA compared with healthy subjects. The percentages of IL-17+ CD4+T cells were correlated with the number of swelling joints and C-reactive protein of RA patients. Likewise, concentrations of IL-17 in supernatants from patients with RA were significantly higher compared with those from control subjects. After infliximab combined with MTX or MTX-alone therapy, the number of swelling joints, erythrocyte sedimentation rate, C-reactive protein, rheumatoid factor, and Disease Activity Score 28 decreased significantly compared with baseline. Only in the infliximab + MTX group that the frequency of TH17 cells and concentration of IL-17 decreased. Conclusions These data support the hypothesis that infliximab therapy can have an effect on TH17 cells and decrease disease activity.

Interleukin-17 and interleukin-23 in patients with polymyositis and dermatomyositis

Objective: To analyse the concentration of interleukin (IL)-17 and IL-23 in serum and ex vivo culture supernatant of peripheral blood mononuclear cells (PBMCs) from patients with polymyositis (PM) and dermatomyositis (DM) compared with healthy controls (HC). Methods: Enzyme-linked immunosorbent assay (ELISA) was used to analyse the concentration of IL-17 and IL-23 from 25 patients with PM, 21 patients with DM, and 12 HC in serum or ex vivo culture supernatant of PBMCs following stimulation ex vivo with anti-CD3/CD28 for 72 h. Results: The levels of IL-23 increased in the serum and culture supernatant of patients with PM and patients with DM compared with HC. By contrast, concentrations of IL-17 in supernatants from patients with PM and DM were not significantly higher than those from HC. We subdivided the group of DM and PM patients into those with early disease versus those with established disease and found that the levels of IL-17 and IL-23 were much higher in early stage compared to established disease. Conclusion: We have demonstrated that stimulated PBMCs from DM and PM patients produce increased levels of IL-23 as compared to HC. IL-17 and IL-23 levels are increased in early as compared to established disease. This provides further evidence that IL-17/IL-23 may play a crucial role in autoimmune diseases.

Increased levels of interleukin‐27 in patients with rheumatoid arthritis

Rheumatoid arthritis (RA) is a chronic autoimmune disease in which many cytokines play a fundamental pathogenetic role. Interleukin-27 (IL-27) is a dimeric member of the IL-12 family that comprises the Epstein-Barr virus– induced protein 3 and p28 subunits, which signal through a receptor complex composed of IL-27 receptor agonist (IL27Ra) and glycoprotein 130 subunits (1). IL-27 is mainly produced by antigen-presenting cells and plays a key role in regulating T cell differentiation and function (2). Recently, studies have indicated that IL-27 may exert both proand antiinflammatory functions in experimental arthritis, depending on the phase of disease (3,4). Cao and colleagues showed that IL-27Ra / mice displayed reduced severity and delayed onset of proteoglycan-induced arthritis, which was associated with decreased interferonexpression (3). In contrast, exogenous IL-27 has been shown to ameliorate collagen-induced arthritis when injected immediately prior to the onset of disease (4). Despite the overall effects observed in animal models of RA, the role of IL-27 in human RA remains largely unclear. In the present study, we investigated the serum levels of IL-27 in RA patients and analyzed their correlation with measures of disease activity. Sera were obtained from 31 patients who satisfied the 1987 American College of Rheumatology RA criteria (5). Among them, 23 patients had RA that had been recently diagnosed, while the other 8 RA patients had established disease, but had not received either corticosteroids or immunosuppressive treatment for at least 3 months prior to the study. Sera were also obtained from 18 healthy ageand sex-matched controls. Written informed consent was provided by all subjects, and the study was approved by the local institutional ethics committee and was conducted according to the Declaration of Helsinki. Clinical data, including swollen joint count and tender joint count, were obtained from medical records at admission. Tests for erythrocyte sedimentation rate (ESR), C-reactive protein (CRP), and rheumatoid factor (RF) were conducted by standard methods, and the 28-joint Disease Activity Score (DAS28) (6) was calculated. Serum levels of IL-27 were detected by enzyme-linked immunosorbent assay, according to the instructions of the manufacturer (R&D Systems). Since RF may interfere with such assays, we added known quantities of recombinant IL-27 to an RF-positive serum sample in order to determine whether this altered our ability to measure the cytokine. The presence of RF had no significant effect on the measurement. Statistical differences were analyzed by Mann-Whitney test and correlation coefficients were determined by Spearman’s rank correlation test, using SPSS 17.0 and GraphPad 5 software. The RA patients (26 women and 5 men) had a mean SD age of 56 15 years (range 25–82), while control subjects (15 women and 3 men) had a mean SD age of 51 9 years (range 28–75). Serum IL-27 levels were higher in RA patients compared with normal controls (mean SD 1,877 1,597 pg/ml versus 524 793 pg/ml; P 0.0001) (Figure 1A). In 18 of the 31 patients, interstitial lung disease (ILD) was identified on high-resolution computed tomography and IL-27 levels were significantly higher in RA patients with ILD than in RA patients without ILD (mean SD 2,087 1,623 pg/ml versus 1,579 1,530 pg/ml; P 0.029) (Figure 1B). Among the 31 RA patients, 18 were positive for antibodies to cyclic citrullinated peptide (CCP). There were no differences in IL-27 levels between anti-CCP–positive and anti-CCP– negative patients. A significant positive correlation was found between IL-27 levels and ESR (r 0.401, P 0.026) in the RA group as a whole. Additionally, there was a statistically significant positive correlation between the levels of IL-27 and DAS28 (r 0.402, P 0.025). In contrast, there was no correlation between the levels of IL-27 and other clinical parameters, including the CRP, RF titer, and number of swollen or tender joints. In summary, serum IL-27 levels were elevated in patients with RA and were associated particularly with disease activity and with ILD as a complication of RA. This suggested a possible therapeutic significance for IL-27 in RA.

Elevated serum and synovial fluid levels of interleukin-37 in patients with rheumatoid arthritis: Attenuated the production of inflammatory cytokines

OBJECTIVES To measure the serum and synovial fluid (SF) levels of interleukin (IL)-37 in patients with rheumatoid arthritis (RA) and to investigate the effect of recombinant human (rh)IL-37 on inflammatory cytokine production (tumor necrosis factor [TNF]-α, IL-6, IL-17 and IL-10) by peripheral blood mononuclear cells (PBMCs) in RA patients. METHODS An enzyme-linked immunosorbent assay (ELISA) was used to analyse the serum and SF IL-37 levels. RhIL-37 was used to stimulate RA patient PBMCs. The supernatant TNF-α, IL-17, IL-6 and IL-10 levels were detected with ELISAs. RESULTS The serum IL-37 levels in RA patients were significantly increased compared with those of osteoarthritis (OA) and healthy controls (HC), and they were especially elevated in RA patients with positive rheumatoid factor (RF) and anti-citrullinated peptide antibody (CCP) levels. Furthermore, the serum IL-37 levels were positively correlated with RF values. In 20 matched RA SF and serum samples, the SF IL-37 levels were much higher than those in the serum. After anti-TNF-α therapy, the serum IL-37 levels significantly decreased. Additionally, rhIL-37 significantly down-regulated TNF-α, IL-17 and IL-6 production by RA patient PBMCs. CONCLUSIONS IL-37 is an important anti-inflammatory cytokine in the control of RA pathogenesis by suppressing inflammatory cytokine production. Thus, IL-37 administration may be a novel therapy for RA.

Elevated levels of interleukin-27 and effect on production of interferon-γ and interleukin-17 in patients with Behçet’s disease

Objectives: To measure the levels of interleukin (IL)-27, interferon (IFN)-γ, and IL-17 in serum and supernatants of stimulated peripheral blood mononuclear cells (PBMCs) of patients with Behçet’s disease (BD) compared with healthy subjects, and to evaluate the effect of recombinant human IL-27 (rhIL-27) on IFN-γ and IL-17 production by PBMCs. Methods: Forty-three patients with BD and 40 healthy controls were included in this study. The serum levels of IL-27, IFN-γ, and IL-17 and their production by PBMCs were measured by enzyme-linked immunosorbent assay (ELISA), together with the effects of levels of rhIL-27 on IFN-γ and IL-17 production by PBMCs. Results: There were significantly higher levels of IL-27, IFN-γ, and IL-17 in sera of patients with BD compared with the controls. Levels of IL-27, IFN-γ, and IL-17 in BD patients with active uveitis were significantly higher than in those without. Moreover, IL-27, IFN-γ, and IL-17 production by stimulated PBMCs was increased in BD patients compared to controls. In the presence of rhIL-27, stimulation of PBMCs from BD patients resulted in decreased production of IL-17 but increased production of IFN-γ. Conclusions: These findings suggest that IL-27, IFN-γ, and IL-17 play a role in the pathogenesis of BD.

Elevated Serum Level of IL-33 and sST2 in Patients With Ankylosing Spondylitis: Associated With Disease Activity and Vascular Endothelial Growth Factor

Objective Interleukin (IL)-33 is a cytokine belonging to the IL-1 family and was recently identified as a ligand for ST2, which belongs to the IL-1 receptor (IL-1R) family. In this study, we aimed to investigate the possible pathophysiological role of IL-33/sST2 in ankylosing spondylitis (AS). Methods The levels of IL-33/sST2 and vascular endothelial growth factor in serum samples of 140 patients with AS and 90 controls were measured by enzyme-linked immunosorbent assay. Erythrocyte sedimentation rate, C-reactive protein level, and human leukocyte antigen B27 were measured by standard laboratory techniques. Disease activity in AS was measured by the Bath Ankylosing Spondylitis Disease Activity Index. Hip involvement, peripheral arthritis, and eye involvement were also recorded. Results The serum levels of IL-33/sST2 were remarkably higher in the patients with AS than the healthy groups and significantly correlated with vascular endothelial growth factor and the Bath Ankylosing Spondylitis Disease Activity Index. The sST2 levels correlated with erythrocyte sedimentation rate, C-reactive protein, platelet, and human leukocyte antigen B27. Elevated levels of IL-33/sST2 were detected in the patients with peripheral arthritis, and sST2 were detected to be increased in the patients with hip involvement. By contrast, levels of IL-33 but not sST2 increased in the patients with eye involvement. Conclusion IL-33/sST2 may regulate the immunological or inflammatory process of AS.

Blockage of TNF-α by infliximab reduces CCL2 and CCR2 levels in patients with rheumatoid arthritis.

Objectives To investigate the mechanism in vivo for the regulation of inflammation of patients with RA by infliximab, we measured serum levels of chemokine ligand (CCL) 2, CCL3, CXCL8, and expression of CCL2 receptor chemokine receptor (CCR) 2 on CD4+ T cells from patients with rheumatoid arthritis (RA). Methods Forty-four patients with were enrolled in our study. Twenty-four patients received infliximab combined with methotrexate. Twenty patients received methotrexate alone. Serum levels of the chemokines CCL2, CCL3, and CXCL8 were quantified using commercial enzyme-linked immunosorbent assay kits. Flow cytometry was used to analyze the expression of CCR2 on CD4+ T cells. Results The mean CCL2 levels in the infliximab-treated patients decreased significantly from 885.20 ± 323.52 pg/mL at pretreatment to 454.65 ± 185.03 pg/mL (P < 0.05) at 30 weeks after the initial treatment. Fluorescence density of CCR2 expression on CD4+ T cells were significantly reduced after infliximab treatment. Conclusions CCL2/CCR2 system in patients with active RA may be sensitive to anti-tumor necrosis factor-α therapy and suggest that CCL2 plays a crucial role in the pathogenesis of RA. CCR2 may be an important target for therapy in RA.

IL-35 Inhibits Angiogenesis through VEGF/Ang2/Tie2 Pathway in Rheumatoid Arthritis

Background/Aims: The pro-angiogenic factors vascular endothelial growth factor (VEGF) and angiopoietins (Angs) play a prominent role in synovial angiogenesis, an early and critical event in the pathogenesis of rheumatoid arthritis (RA). Interleukin (IL)-35 is an anti-inflammatory cytokine that attenuates collagen-induced arthritis, however, the mechanisms involved are not fully understood. Methods: The effects of IL-35 on endothelial cell migration, adhesion, and tube formation were examined using human umbilical vein endothelial cells (HUVEC) in vitro. The effects of IL-35 on vessel formation in vivo were examined using a murine Matrigel plugs model. MMP2/MMP9 and IL-6/IL-8 secretion were assessed by zymography and ELISA, respectively. The crosstalk between IL-35, VEGF, and Ang2 in HUVECs and RA synovial tissue explants was investigated. Results: IL-35 inhibited basal and VEGF-induced HUVEC migration and adhesion in vitro as well as tube formation in vitro and in vivo. VEGF increased Ang2 secretion by HUVECs and RA synovial tissue explants, and exogenous Ang2 promoted HUVEC migration, adhesion, and tube formation with similar potency to VEGF. Blocking the Ang/Tie2 pathway with a Tie2 kinase antibody inhibited the proangiogenic effects of exogenous Ang2 and VEGF in HUVECs. IL-35 inhibited basal and VEGF-induced Ang2 secretion by HUVECs and RA synovial tissue explants; it also antagonized the proangiogenic effects of exogenous Ang2 in HUVECs. Moreover, IL-35 reduced basal and VEGF/Ang2-induced MMP2/MMP9 and IL-6/IL-8 secretion. Conclusion: These results suggested that IL-35 restrains RA angiogenesis and inflammation by downregulating basal and VEGF-induced Ang2 secretion as well as disrupting Ang2/Tie2 signal transduction. Our findings extend current understanding of mechanisms regulating RA angiogenesis and may support development of novel angiogenesis-targeting therapeutics for RA treatment.

Potential contribution of interleukin-33 to the development of interstitial lung disease in patients with primary Sjogren's Syndrome

OBJECTIVE To determine whether interleukin (IL)-33 and soluble ST2 (sST2) are associated with primary Sjogrens Syndrome (pSS). METHODS Serum levels of IL-33 and sST2 in 110 pSS patients and 78 healthy controls were measured by enzyme-linked immunosorbent assay (ELISA). Immunoglobulins, rheumatoid factors (RF), antinuclear antibody (ANA), anti-SSA/RO-52 antibody, anti-SSB antibody and erythrocyte sedimentation rate (ESR) were measured by standard laboratory techniques. Interstitial lung disease (ILD) was identified on high-resolution computed tomography (HRCT). Disease activity in pSS was scored with the European League Against Rheumatism Sjogrens Syndrome Disease Activity Index (ESSDAI). RESULTS Serum levels of IL-33 and sST2 were significantly elevated in pSS patients, especially in patients with ILD. There was significant positive correlation between IL-33 and RF, anti-SSB antibody. CONCLUSION IL-33/sST2 may be involved in the pathogenesis of pSS and partly contribute to the ILD in pSS patients.