SAT0638 INCREASED LEVELS OF CIRCULATING EXTRA CELLULAR LONG NON-CODING RNAS MALAT1, MEG3 AND NEAT1 IN PATIENTS WITH RHEUMATOID ARTHRITIS AND THEIR IMPACT ON DISEASE ACTIVITY MEASURES
Authors: Sudipta Chatterjee, Nitai P. Bhattacharyya, Dipanjan Bhattacharjee, Sanchaita Misra, Alakendu Ghosh
Journal: Annals of the Rheumatic Diseases (2019)

<h3>Background:</h3> Deregulations of long non-coding RNAs (lncRNA) have been lately implicated in autoimmune diseases(1) including Rheumatoid arthritis (RA). However, their specific roles in disease pathogenesis, extra-cellular manifestations and clinical impact in RA remain largely unknown. <h3>Objectives:</h3> To identify the intra- and extra-cellular expressions of lncRNAs, MEG3, MALAT1, NEAT1, in RA and their impact on disease activity. <h3>Methods:</h3> Blood samples were collected from 82 active RA patients (DAS28-CRP: 4.7±0.2) and 15 age-sex matched healthy individuals. Knee synovial fluids (SF) were collected from 24 RA patients (among 82) and 10 osteoarthritis patients (as control). Sera were separated for cytokines measurements. RNA, isolated from peripheral blood mono nuclear cells (PBMCs), plasma and synovial fluid were quantified by spectrophotometry. Levels of MALAT1, MEG3 and NEAT1 were determined using specific primers and real time PCR, 18S rRNA was the endogenous control. Fold changes were calculated using standard 2<sup>-ΔΔCt</sup> method. Multivariate analysis was performed to analyze associations between the dependent variable (DAS28-CRP) and the predictor variables (CRP, MALAT1, MEG3 and NEAT1). Confidence interval of 95% (p&lt;0.05) was considered statistically significant for all analyses. <h3>Results:</h3> All patients recruited were anti-CCP positive (122.5 ±28.3 IU/ml) and RF positive (166.5 ±37.3 IU/ml). Their systemic inflammation were high compared to controls (p&lt;0.05) as reflected in serum CRP (47.4 ±26.2 mg/L), TNFα (140±29 pg/dl) and IL17 (270±33 pg/dl). Levels of MALAT1, MEG3 and NEAT1 were increased in the PBMCs (p&lt;0.05) of RA patients compared to controls. Similar increases of these lncRNAs were seen in plasma and in SF. Spearman's correlation were performed with the fold changes of lncRNAs in PBMC, DAS28-CRP and its components. MEG3 significantly correlated with tender joint count (TJC) (r=0.75, p=0.002) whereas NEAT1 correlated with both TJC (r=0.571, p=0.002) and DAS28-CRP (r=0.943, p=.001). Multivariate analysis was performed with NEAT1 and MEG3 as the predictors and DAS28-CRP (model 2) as outcome and co-efficient of determinant (r<sup>2</sup>) was compared to that of CRP as the predictor and DAS28-CRP as the outcome (model 1). Model 1 was made to set a cut-off mark for model 2. The r<sup>2</sup> for model 1 (0.862) was greater than that of model 2 (0.656) indicating the expressions of NEAT1 and MEG3 accounted more for variability in DAS28-CRP scores (86.2%) than CRP (65.6%). In model 2, β co-efficient of NEAT1 (β=0.868) was greater than that of MEG3 (β=0.397) suggesting a greater impact of NEAT1 on DAS28-CRP scores. The lncRNAs in plasma and in synovial fluids had shown similar trends. <h3>Conclusion:</h3> Increased in lncRNAs in extra cellular fluid suggests their systemic regulation on RA pathogenesis. Increased predictability of DAS28-CRP by NEAT1 and MEG3 compared to CRP indicate their potentiality of being probable markers in monitoring disease activity. However, validation of this finding in larger cohort is necessary. <h3>References</h3> [1] Wu GC, Pan HF, Leng RX, Wang DG, Li XP, Li XM, Ye DQ. Emerging role of long noncoding RNAs in autoimmune diseases. Autoimmun Rev. 2015 Sep;14(9):798-805. <h3>Disclosure of Interests:</h3> None declared