Xiu-Ning Wei

Serum Matrix Metalloproteinase-3 as a Noninvasive Biomarker of Histological Synovitis for Diagnosis of Rheumatoid Arthritis

Objective. To explore the correlation between matrix metalloproteinase- (MMP-) 3 and histological synovitis in rheumatoid arthritis (RA). Methods. Serum MMP-3 of 62 patients with active RA was detected by ELISA. Serial synovial tissue sections from all RA patients, 13 osteoarthritis, and 10 orthopedic arthropathies patients were stained with hematoxylin and eosin and immunohistochemically for MMP-3, CD3, CD20, CD38, CD68, and CD15. Results. The percentage of lining MMP3+ cells was significantly higher in RA patients especially with high grade synovitis and it was significantly correlated with Krenns synovitis score (r = 0.574, P < 0.001) and sublining inflammatory cells. Multivariate stepwise linear regression analysis revealed that the association of the percentage of lining MMP3+ cells with activation of synovial stroma, sublining CD68+ macrophages, and CD15+ neutrophils was stronger than other histological indicators. The percentage of lining MMP3+ cells was significantly correlated with serum MMP-3 in RA (r = 0.656, P < 0.001). Serum MMP-3 was higher in RA patients with high grade synovitis than that of low grade synovitis and significantly correlated with synovitis score and activation of synovial stroma subscore (all P < 0.05). Conclusion. Serum MMP-3 may be an alternative noninvasive biomarker of histological synovitis and RA diagnosis.

Synovial Infiltration with CD79a-positive B Cells, But Not Other B Cell Lineage Markers, Correlates with Joint Destruction in Rheumatoid Arthritis

Objective. The efficacy of B cell depletion in the treatment of patients with rheumatoid arthritis (RA) has revitalized interest in the pathogenic role(s) of B cells in RA. We evaluated the distribution of synovial B lineage cells and their correlation with histologic disease activity and joint destruction in RA. Methods. Synovial tissue samples were obtained by closed-needle biopsy from 69 Chinese patients with active RA, from 14 patients with osteoarthritis (OA), and from 15 with orthopedic arthropathies (OrthA) as disease controls. Serial tissue sections were stained immunohistochemically for CD79a (pro-B cell to plasma cell), CD20 (B cells), CD38 (plasma cells), CD21 (follicular dendritic cells), CD68 (macrophages), CD3 (T cells), and CD34 (endothelial cells). Densities of positive-staining cells were determined and correlated with histologic disease activity (Krenn 3-component synovitis score) and radiographic joint destruction (Sharp score). Results. Mean sublining CD79a-positive cell density was significantly higher in RA than in OA (p <0.001) or OrthA (p = 0.003). Receiver operating characteristic curve analysis showed that CD79a-positive cell density differentiated RA well from OA [area under the curve (AUC) = 0.79] or OrthA (AUC = 0.75). Spearman’s rank order correlation showed significant correlations between sublining CD79a-positive cell density and the synovitis score (r = 0.714, p < 0.001), total Sharp score (r = 0.490, p < 0.001), and the erosion subscore (r = 0.545, p < 0.001), as well as the joint space narrowing subscore (r = 0.468, p = 0.001) in RA. Conclusion. Synovial CD79a-positive B cells may be a helpful biomarker for histologic disease activity in RA and may be involved in the pathogenesis of joint destruction in RA.

Elevated Serum Glucose-6-Phosphate Isomerase Correlates with Histological Disease Activity and Clinical Improvement After Initiation of Therapy in Patients with Rheumatoid Arthritis

Objective. To determine serum glucose-6-phosphate isomerase (GPI) concentrations in patients with rheumatoid arthritis (RA), and to test whether they correlate with objective measures of disease activity. Methods. Sera from 116 patients with RA, 69 patients with non-RA rheumatic diseases, and 101 healthy controls were analyzed. Levels of soluble serum GPI were measured by ELISA. Histological disease activity was determined with the synovitis score in synovial needle biopsies from 58 of the 116 patients with RA. Thirty-one of the 58 synovium samples were stained for CD68, CD3, CD20, CD38, CD79a, and CD34 by immunohistochemistry. Demographic data were collected, as well as serological and clinical variables that indicate RA disease activity, for Spearman correlation analysis. Results. Serum GPI level correlated positively with the synovitis score (r = 0.278, p = 0.034). Significantly higher soluble GPI levels were detected in the RA sera compared with sera from healthy controls and the non-RA disease controls (2.25 ± 2.82 vs 0.03 ± 0.05 and 0.19 ± 0.57 μg/ml, respectively; p < 0.0001). The rate of serum GPI positivity was significantly higher in the RA patients than in the non-RA disease controls (64.7% vs 10.1%; p < 0.0001). Spearman analysis showed no significant correlation between serum GPI level and Disease Activity Score in 28 joints at baseline. After initiation of antirheumatic treatments, GPI levels decreased significantly (2.81 ± 3.12 vs 1.44 ± 2.09 μg/ml; p = 0.016), paralleling improvement of the disease activity indices. Conclusion. Elevated serum GPI may be involved in the synovitis of RA and may prove useful as a serum marker for disease activity of RA.

Joint damage is amplified in rheumatoid arthritis patients with positive thyroid autoantibodies

Background Autoimmune thyroid disease (AITD), which is characterized by an increased presence of thyroid autoantibodies (TAbs), such as antibodies against thyroid peroxidase (TPOAbs) and antibodies against thyroglobulin (TgAbs), has been reported to be associated with rheumatoid arthritis (RA) because AITD and RA both involve autoimmunity. However, few data are available on the incidence of TAbs in Chinese RA patients, and studies on the association between TAbs and joint damage as well as synovitis in RA patients remain sparse. Here, we aimed to evaluate the incidence of TAbs in a consecutive Chinese RA cohort and to investigate whether the elevated presence of TAbs is associated with joint damage and synovitis in RA patients. Methods A total of 125 hospitalized RA patients were consecutively recruited. Clinical data and available synovial tissues were collected at baseline, and TAbs and thyroid function were detected by chemiluminescent immunoassay. Patients who tested positive for TPOAbs or TgAbs were classified as the TAbs-positive group, and patients who tested positive for neither TPOAbs nor TgAbs were recruited as the TAbs-negative group. Disease activity was assessed using DAS28-ESR (the disease activity score in 28 joints and including the erythrocyte sedimentation rate). X-ray assessment of the hand/wrist was performed according to the Sharp/van der Heijde-modified Sharp score (mTSS), and patients with an mTSS score >10 were defined as having radiographic joint damage (RJD). Serial tissue sections were stained immunohistochemically for CD3, CD15, CD20, CD34, CD38, and CD68, and synovitis were assessed according to Krenn’s synovitis score. Results A total of 44 (35%) patients were positive for either TPOAbs or TgAbs. Importantly, there was a significantly greater percentage of patients with RJD in the TAbs-positive group versus the TAbs-negative group (68% vs. 42%, p = 0.005). Compared with the TAbs-negative group, significantly more CD38-positive plasma cells infiltrated the TAbs-positive synovium, and a higher percentage of patients with high-grade synovitis were observed in the TAbs-positive group (5/8, 63% vs. 5/14, 36%). Moreover, RF positivity and disease activity indicators, including TJC28, DAS28-ESR, and CDAI, were significantly higher in the TAbs-positive group (all p < 0.05). Adjusted logistic regression analysis revealed that positive TAbs (OR 2.999, 95% CI [1.301–6.913]; p = 0.010) and disease duration (OR 1.013, 95% CI [1.006–1.019]; p < 0.001) were independently associated with RJD, and an odds ratio of 2.845 (95% CI [1.062–7.622]) was found for RJD in women with positive TAbs (n = 37) compared with those without TAbs (n = 59) (p = 0.038). Conclusion Our data showed that joint destruction was amplified in RA patients with an elevated presence of TAbs, which supports the importance and necessity of TAbs and thyroid function screening and monitoring in RA patient management in clinical practice.

AB0813 High Prevalence of Urolithiasis Due To Excess Urinary Uric Acid Concentration and Calcium Excretion in South Chinese Gout Patients: Table 1.

Background Urolithiasis greatly impact urate lowering therapy in Chinese gout patients. Benzbromarone is contraindicated and Chinese is high risk of allopurinol hypersensitivity syndrome. Febuxostat is too expensive for many patients. Few study about urolithiasis in Chinese gout patients are presented. Objectives To investigate the prevalence and risk factors of urolithiasis in south Chinese gout patients. Methods Patients with primary gout were recruited in the present cross-section study. Urolithiasis was defined as positive stone history and/or ultrasonography. All inpatients with estimated glomerular filtration rate (eGFR) over 30 ml/min/1.73 m2 underwent 24 hours urinary chemistry assay including uric acid (UA), UA concentration, clearance of UA, Cr, calcium, phosphorus, potassium, sodium and chloride. Logistic regression were performed to examine association of urolithiasis with independent variables including age, gender, duration of gout, sUA, previous urate lowering therapy, serum creatinine, eGFR, body mass index, urine pH and 24 hours urinary chemistry assay. Results (1) Two hundred and nighty-four patients were recruited. Mean age of male (N=255) and female (N=39) were 54.4±16.4 and 67.2±15.3, respectively. Average serum UA was 9.0±2.5mg/dl and 25.9% of patients presented tophi. Allopurinol, benzbromarone, or a combination of these two drugs had been prescribed in 97 patients (33.0%), 18 patients (6.1%) and 36 patients (12.2%), respectively. The rest 143 patients (48.6%) had not received urate lowering therapy before. (2) One hundred and eleven gout patients (37.8%) complicated with urolithiasis and urolithiasis was observed in 69 of them (62.1%) on ultrasonography. Compared with non urolithiasis group, urolithiasis group had significant higher serum creatinine (1.6±0.6 VS 1.3±0.3 mg/dl], lower eGFR (56.3±18.0 VS 64.1±18.4 ml/min/1.73m2) and higher alcohol overuse (38.7% VS 26.2%) (P<0.05). (3) Among 102 patients performed 24 hours urinary chemical assay, 45 patients complicated with urolithiasis. Urolithiasis group had significantly higher 24 hours urine UA concentration than non-urolithiasis group (30.4±13.1 VS 23.9±11.9 mg/dl, P=0.01). There were no significant difference of other variables between two groups. Prevalence of urolithiasis increased significantly across increasing quartiles of urinary UA concentration (P=0.012, Table 1). (4) Logistic regression suggested that risk factors of urolithiasis were urinary UA concentration grouped by quartile (P=0.05) and urinary calcium excretion [OR 1.26 (1.01, 1.57), P=0.04]. Urinary UA concentration over 24.4mg/dl was associated with increasing risk of urolithiasis (Table 1).Table 1. Prevalence of urolithiasis among quartiles of urinary UA concentration Quartiles of urinary UA concentration (mg/dl) I (<17.6) II (17.6–24.3) III (24.4–34.9) IV (≥35.0) Median (mg/dl) 12.8 20.8 30.0 42.5 Prevalence* 13.3% (6) 22.2% (10) 33.3% (15) 31.1% (14) Adjusted OR# 1 2.47 (0.66, 9.24) 5.5 (1.50, 20.72) 4.58 (1.24, 16.92) P# – 0.18 0.01 0.02 *Test for a linear trend P=0.012. #By logistic regression. Conclusions Prevalence of urolithiasis in Chinese gout patients were high and predicted by excess urinary UA concentration and urinary calcium excretion. Acknowledgement The present study was supported by Guangdong Natural Science Foundation, China (Grant no. 2014A030310086) to Qian-Hua Li. Disclosure of Interest None declared

AB0499 The Influence on Hepatitis B Virus Infection in Rheumatoid Arthritis Patients Undergoing Treatment with Newer Dmard, Iguratimod

Background The hepatitis B surface antigen (HBsAg) carrying rate of rheumatoid arthritis (RA) was 11.2% in China according to recent studies. HBV infection is a major issue in RA patients undergoing disease-modifying anti-rheumatic drugs (DMARDs) therapy. Iguratimod was a newer effective conventional DMARD, which was small molecular and approved in China in Augest, 2011. However, little was known about the influence of iguratimod to liver injury and HBV reactivation. Objectives To explore the influence of iguratimod on HBV reactivation in HBsAg/HBcAb+ RA patients and the influence on HBsAb titer in HBsAb+ RA patients. Methods Patients with active RA were enrolled from October 2013 to September 2014. All were treated with iguratimod (25mg Bid) alone or in combination with other conventional DMARDs for 24 weeks, such as methotrexate (MTX), leflunomide (LEF), etc. Adding with non-steroidal anti-inflammatory drugs (NSAIDs) or small doses of corticosteroids was permitted if constant pain observed. HBsAg+ RA patients were suggested to be treated with anti-virus therapy preventively. Liver function, HBsAg or HBsAb titer, and HBV-DNA load were evaluated at baseline, 12th and 24th week. HBV reactivation was defined as a 10-fold rise in HBV-DNA compared to baseline or HBsAg/HBeAg switch from undetectable to detectable. Results 1) Thirty-six patients with active RA were enrolled and 74% (29/36) were female, age (median and IQR, similarly hereinafter) was 49 (39–58) years, disease duration was 59 (23–81) months, and DAS28-CRP was 4.44 (3.96–5.75). Twelve patients received iguratimod monotherapy. 2) Patients with active RA were grouped according to serum HBV biomarkers, including chronic or past HBV infection group (HBsAg or HBcAb +, N=20) and free of HBV infection group (HBsAg and HBcAb -, N=16).There was no significance difference of transaminases (AST 18 (14–24) vs 17 (12–25), ALT 14 (12–30) vs 13 (8–22)) and DAS28 (4.82 (4.03–5.85)vs 4.28 (3.81–5.65)) of baseline (all P>0.05). 3) The chronic or past HBV infection group was divided into chronic HBV infection subgroup (HBsAg or HBV-DNA +, n=3) and past HBV exposed subgroup (HBcAb + but HBsAg-,n=17). In the chronic HBV infection subgroup, all refused antiviral prophylaxis, and 2 developed HBV reactivation without aminotransferases elevation in 10th and 24th weeks. In pass HBV exposed subgroup, 2 patients developed transient 3-times elevation of aminotransferases in 24th weeks. 4) In free of HBV infection group, none developed transaminases elevation. The changes of HBsAg and HBsAb has no statistical significance among baseline,12th and 24th weeks according to repeated measures analysis of variance (F=0.795, P=0.472) and Wilcoxon Matched-Pairs Signed-Ranks Test (all P>0.05). Conclusions Active RA patients should be screened for liver function and HBV biomarker before iguratimod therapy. RA patients with HBV infection, especially with positive baseline HBV-DNA,were recommended to be treated with antiviral prophylaxis and monitor liver function and HBV-DNA load regularly. Acknowledgements This work was supported by National Natural Science Foundation of China (grant no. 81471597), Specialized Research Fund for the Doctoral Program of Higher Education (grant no.20130171110075) and Guangdong Natural Science Foundation (grant no.S2013010014396). Disclosure of Interest None declared

SAT0078 Elevated Synovial Matrix Metalloproteinase 3 as a Predictor of Radiographic Progression in Rheumatoid Arthritis

Background Rheumatoid arthritis (RA) is an autoimmune disease which leads to bone destruction. RA synovium secretes large amounts of matrix metalloproteinase (MMP) 3 which plays essential role in degradation of extracellular components and cartilage. Several studies reported that serum MMP-3 correlated with radiographic progression. However, little was known about the relationship of synovial MMP-3 and radiographic progression. Objectives To explore the correlation of synovial MMP-3 and radiographic progression in RA. Methods Patients with active RA were recruited and followed up at 1st, 3rd, 6thand 12th months. Serum MMP-3 was detected by ELISA and clinical data was collected simultaneously at baseline and each visit. X-ray assessment of hand/wrist was repeated and radiographic progression was defined as the increase of total Sharp score more than 0.5 from baseline to one year. Synovial tissues were obtained at baseline and serial tissue sections were stained with H&E and immunohistochemically for MMP-3, CD3, CD20, CD38, CD68and CD15. Krenns synovitis score was assessed semi-quantitatively and the density of positive-staining cells were quantitatively determined. Results (1) Twenty-six patients fulfilled 1 year follow-up, 81% were female, age (median and IQR, similarly hereinafter) was 49 (39–58) years, disease duration was 24 (12–66) months, disease activity SDAI was 36.3 (24.0–48.1), and 54% were treated with csDMARDs while 46% were treated with bDMARD. (2) Eight (31%) patients had radiographic progression at 12th month. Histopathological analysis showed that subscore of lining hyperplasia, percentage of lining MMP3+ cells and sublining CD68+ macrophage count were significantly higher in progressive patients than non-progressive patients (all P<0.05). Univariate logistic regression showed that high level of synovial MMP-3 was a significant predictor of 1-year radiologic progression (P=0.044, OR=1.117, 95%CI: 1.003 to 1.244). ROC curve analysis showed that the tradeoff value of synovial MMP-3 for predicting 1-year radiographic progression was 49% with sensitivity 63% and specificity 83% (AUC=0.785, 95%CI: 0.595–0.975, P=0.023). (3) Patients were divided into high (n=9) or low synovial MMP-3 groups (n=17) according to the tradeoff value. Serum MMP-3 at baseline was significantly higher in high synovial MMP-3 group than that in low synovial MMP-3 group [440 (246–609) ng/ml vs 152 (69–316) ng/ml, P=0.016], and the percentage of synovial MMP3+ cells positively correlated with serum MMP-3 at each visit (r=0.537–0.592, all P<0.05). Serum MMP-3 decreased to normal after 6 months in half patients of low synovial MMP-3 group while it continually elevated throughout 12 months in high synovial MMP-3 group (Fig. 1A). (4)SDAI in both groups decreased during follow-up and showed no significant difference at each visit (all P>0.05, Fig. 1B). However, Fisher exact test showed obvious tendency that the percentage of progressive patients in high synovial MMP-3 group (55.6%) was higher than that in low synovial MMP-3 group (17.6%, P=0.078, Fig. 1C). Conclusions Our results implied that synovial MMP-3 may be a predictor of radiographic progression in RA. Acknowledgements This work was supported by National Natural Science Foundation of China (No.81471597), Specialized Research Fund for the Doctoral Program of Higher Education (No.20130171110075) and Guangdong Natural Science Foundation (No.S2013010014396). Disclosure of Interest None declared

OP0070 Synovial Hypoxia-Inducible Factor 1 Alpha Involved in Joint Destruction in Rheumatoid Arthritis

Background Hypoxia-inducible factor (HIF)-1α is a critical transcription regulator in cellular response to hypoxic condition. Hypoxic microenvironment exists in rheumatoid arthritis (RA) joints and we have reported that elevated HIF-1α promoted angiogenesis and inflammation in RA. Recent studies showed HIF-1α might promote osteoclast-mediated bone resorption in vitro. However, little was known about its role in RA joint destruction. Objectives To explore the correlation of synovial HIF-1α with joint destruction and its progression in RA. Methods Patients with active RA were followed up and X-ray assessment of hand/wrist was repeated at baseline and one year. Erosive disease was defined according to 2013 EULAR definition and radiographic progression was defined as the increase of total Sharp score more than 0.5 from baseline to one year. Synovial tissue was obtained from RA patients as well as OA and orthopedic arthropathies (Orth.A) patients. Serial tissue sections were stained with H&E, immunohistochemically for CD3, CD20, CD38, CD68, CD15, CD34 and HIF-1α. Krenns synovitis score was semi-quantitatively assessed and the density of positive-staining cells was quantitatively determined. Results (1) Twenty five RA patients fulfilled 1 year follow-up, 84% were female, age (median and IQR, similarly hereinafter) was 50 (40–57) years, disease duration was 24 (10–48) months and disease activity SDAI was 35.0 (25.3–46.3). (2) HIF-1α expressed in lining and sublining area with intense nuclear and endochylema staining in RA synovium and the percentage of HIF-1α+ cells [57% (31%–77%)] was significantly higher than that in OA [n=13, 25% (9%–41%), P=0.022]or Orth.A [n=8, 21% (12%–38%), P=0.021, Fig.1]. The percentage of HIF-1α+ cells significantly correlated with subscore of synovial stroma activation, CD34+ microvessel count, CD68+ macrophage count and CD15+ neutrophil count (r=0.420–0.586, all P<0.05). (3) Eleven (44%) RA patients had erosive disease at baseline. The percentage of HIF-1α+ cells was significantly higher in erosive patients than non-erosive patients [78% (49%–82%) vs 47% (23%–62%), P=0.014]. ROC curve analysis showed that the tradeoff value of synovial HIF-1α for diagnosing erosive disease was 69% with sensitivity 73% and specificity 100% (AUC=0.792, 95%CI: 0.574–1.010, P=0.014). Patients were then divided into high (n=8) and low synovial HIF-1α (n=17) groups. Total Sharp score and erosion subscore were higher in patients with high synovial HIF-1α than that in patients with low synovial HIF-1α [33 (14–69) vs 10 (4–24), 18 (11–25) vs 3 (2–12), respectively, all P<0.05] (4) Eight (32%) RA patients showed radiographic progression at one year. The percentage of HIF-1α+ cells was significantly higher in progressive patients than non-progressive patients [80% (58%–85%) vs 49% (18%–63%), P=0.018]. ROC curve analysis showed that the tradeoff value of synovial HIF-1α for predicting 1-year radiographic progression was 66% with sensitivity 75% and specificity 82% (AUC=0.798, 95%CI :0.576–1.019, P=0.018). Univariate logistic regression showed that high level of synovial HIF-1α was a significant predictor of 1-year radiographic progression (P=0.011, OR=14.00, 95%CI: 1.841 to 106.465). Conclusions HIF-1α might play important roles in the pathogenesis of joint destruction in RA. Acknowledgements This work was supported by National Natural Science Foundation of China (81471597). Disclosure of Interest None declared

THU0105 Combination of Baseline Sharp Score and Dynamic Serum Matrix Metalloproteinase 3 for Predicting Radiographic Progression in Rheumatoid Arthritis Patients Achieved Therapeutic Target

Background Current recommendations for rheumatoid arthritis (RA) management emphasize treat-to-target strategies which reduce joint destruction. However, recent studies showed radiographic progression even in remission RA patients and novel predictors were required. Objectives To evaluate clinical, serological and radiographic indicators in predicting radiographic progression in RA patients achieved therapeutic target. Methods Patients with active RA (SDAI >11.0) were treated according to recommendations and followed up at 1st, 3rd, 6th, and 12th months. Serum matrix metalloproteinase (MMP) 3 was detected by ELISA and clinical data was collected simultaneously at baseline and each visit. X-ray assessment of hand/wrist was repeated and radiographic progression was defined as the increase of total Sharp score more than 0.5 from baseline to one year. Patients who achieved therapeutic target at 6th month were included in the analysis. Results (1) Fifty-six patients were recruited and fulfilled 1-year follow-up. Forty-two (75%) of them achieved therapeutic target at 6th month. Among the 42 patients, 71% were female, age (median and IQR, similarly hereinafter) was 49 (38–56) years, disease duration was 18 (12–72) months, SDAI at baseline was 26.5 (14.5–37.4), and 62% were treated with csDMARDs while 38% were treated with bDMARD. Eleven (26%) of them had radiographic progression at 12th month. (2) Among the clinical indicators, serum MMP-3 and Sharp score at baseline, multivariable stepwise logistic regression showed that high level of baseline Sharp score was a significant predictor of 1-year radiologic progression (OR=1.045, 95%CI: 1.001–1.091,P=0.045). ROC curve analysis showed that the tradeoff value of baseline Sharp score for predicting 1-year radiographic progression was 15 with positive predictive value (PPV) 58% and negative predictive value (NPV) 87% (AUC=0.740, 95%CI: 0.562–0.919, P=0.019, Fig 1B). (3) Serum MMP-3 decreased to normal at 6th month in half non-progressive patients but continually elevated throughout 12 months in progressive patients, while SDAI showed similar decreasing between non-progressive and progressive groups (all P>0.05, Fig. 1A). Univariate logistic regression analysis showed that elevated serum MMP-3 at 6th month was a significant predictor for 1-year radiographic progression in RA patients (OR=1.006, 95%CI: 1.001–1.011, P=0.010). ROC curve analysis showed that the tradeoff value of serum MMP-3 at 6th month for predicting 1-year radiographic progression was 161 ng/ml with PPV 67% and NPV 90% at 6th month (AUC=0.789, 95%CI: F0.612–0.965, P=0.005, Fig. 1B) (4) According to the tradeoff value of Sharp score and serum MMP-3 above, ROC curve analysis showed that the PPV and NPV of combination of baseline Sharp score and serum MMP-3 at 6th month for predicting 1-year radiographic progression was 61% and 100% (AUC=0.887, 95%CI: F0.789–0.985, P<0.001, Fig. 1B). Conclusions Our results implied that combination of baseline Sharp score and dynamic serum MMP-3 might be helpful in predicting radiographic progression in RA patients achieved therapeutic target. Acknowledgements This work was supported by National Natural Science Foundation of China (81471597) and Specialized Research Fund for the Doctoral Program of Higher Education (20130171110075). Disclosure of Interest None declared

AB0091 Decreased expression of bcl6 in peripheral blood monocytes from rheumatoid arthritis patients

Background Rheumatoid arthritis (RA) is a common chronic inflammatory disease which could lead to joint destruction and disability. Osteoclasts are essential for bone resorption and play key roles in joint destruction in RA. A recent research on mice suggested that B cell lymphoma 6 (Bcl6) is a negative regulator of osteoclastogenesis, and Bcl6 deficiency facilitates osteoclast formation. B lymphocyte–induced maturation protein-1 (Blimp1) regulates Bcl6 expression and osteoclastogenesis. However, the effect of Bcl6 and Blimp1 on osteoclastogenesis in RA patients is unknown. Objectives To investigate the expression of Bcl6 in peripheral blood monocytes (PBMs, osteoclast precursors) and its correlation with disease activity and radiographic joint destruction in RA. Methods PBMs were isolated from 24 RA patients and 16 healthy controls matched with age and gender, and identified by flow cytometry with CD14 and CD3 markers. The expression of Bcl6 protein was detected by immunofluorescence. Bcl6 and Blimp1 mRNA expression in PBMs was determined by real-time PCR and correlated with clinical parameters which reflect disease activity and radiographic joint destruction (Sharp score). Results (1) Immunofluorescence staining showed significantly decreased expression of Bcl6 in PBMs from RA patients than healthy controls (1.76±0.08 vs 1.88±0.03 AU/mm2, p=0.009). (2) Bcl6 and Blimp1 mRNA expression in PBMs was decreased significantly in RA patients than in healthy controls (χ2 =9.733, p=0.002; χ2 =9.334, p=0.001, respectively). (3) To exclude the influence of medication, 12 treatment-naïve RA patients who had never been treated with disease-modifying antirheumatic drugs or glucocorticoids were analyzed. Bcl6 and Blimp1 mRNA expression in PBMs was decreased significantly in treatment-naïve RA patients, compared with that in healthy controls (χ2 =12.452, p<0.001; χ2 =8.077, p=0.003, respectively). (4) Spearman’s rank order correlation showed that Bcl6 mRNA expression in PBMs from RA patients was positively correlated with joint space narrowing subscore and Blimp1 mRNA expression (r=0.488, p=0.021; r=0.639, p=0.001, respectively), but not significantly correlated with clinical parameters including rheumatoid factor, C-reactive protein, anti-cyclic citrullinated peptide antibody, erythrocyte sedimentation rate, the 28-joint tender and swollen joint count and the disease activity score in 28 joints (DAS28) with three variables including CRP (DAS28(3)-CRP) (all p>0.05). Conclusions Our results showed that Bcl6 expression was decreased in PBMs in RA patients, which implied that Bcl6 may be involved in osteoclastogenesis in RA. Further studies are needed to establish the mechanisms of Bcl6 in osteoclatogenesis and joint destruction in RA. Acknowledgements This work was supported by the Chinese National Natural Science Research Grant (grant no.30972742 and 81001334) and the Natural Science Research Grant of Guangdong Province, China (grant no. 9151008901000130 and 10451008901004542). Disclosure of Interest None Declared