The Serum Level Changes Of IL-34 And RANKL And Their Relationship With Osteoporosis In Rheumatoid Arthritis Patients

Objective: To investigate the serum levels of interleukin 34(IL-34) and receptor activator of nuclear factor kappa-B ligand(RANKL) and the incidence of osteoporosis in patients with rheumatoid arthritis,and to investigate the relationship between IL-34 and RANKL, and explore the relationship between them and other clinical indicators such as bone mineral density, C-reactive protein, rheumatoid factor(RF) and DAS28 score.Methods: From July 2013 to November 2014 in The first hospital of Shanxi Medical University, 55 patients with rheumatoid arthritis(n=70) were selected, and the outpatients for health examination in the same period was as the healthy control group(n = 30). The heel bone density was tested using ultrasonic in all patients. According to the results of bone mineral density, RA patients were divided into three subgroups: normal bone mass group, osteopenia group and osteoporosis group. The serum levels of IL-34 and RANKL were detected using ELISA. And we test the levels of others clinical indicators,including C-reactive protein(CRP),erythrocyte sedimentation rate(ESR), anti-cyclic citrullinated peptide(CCP) antibody and rheumatoid factor(RF) titers, and record swollen joint count and tender joint count, and calculate DAS28 score.Results:(1) The serum levels of IL-34 and RANKL in patients with rheumatoid arthritis were significantly higher than those in control group(492.61±161.35 pg/ml vs. 384.48±78.48 pg/ml;509.36±164.02 pmol/L vs. 403.36±40.70 pmol/L, P<0.01);(2) the incidence of osteoporosis in patients with rheumatoid arthritis was significantly higher than its in control group(46.7% vs. 20.0%, P<0.05);(3) the serum levels of IL-34 in osteoporosis group was significantly higher than its in normal bone mass group(541.41±163.55 pg/ml vs. 358.66±126.72 pg/ml, P<0.05), however there was no significant difference of IL-34 levels between osteopenia group and osteoporosis group;(4) the serum levels of RANKL inosteoporosis group was significantly higher than its in normal bone mass group(565.32±165.87 pmol/l vs. 438.09±171.86 pmol/l, P<0.05), and in osteopenia group(565.32±165.87pmol/l vs 464.62±135.5 pmol/l P<0.01).(5) in the correlation analysis of two variables in RA patients, there was a positive correlation between IL-34 and RANKL(r=0.339,P=0.004),and there was a negative correlation between IL-34 and bone mineral density(r=-0.381,P=0.001); RANKL levels were negative correlated with bone mineral density(r=-0.370,P=0.002);(6) in the correlation analysis of two variables in RA patients, the serum IL-34 level was positively correlated with anti-CCP antibody(r=0.291,P=0.015)、 CRP(r=0.284,P=0.017)、ESR(r=0.314,P=0.008)、RF titer(r=0.303,P=0.011) and DAS28 score(r=0.388,P=0.001) And RANKL level was not correlated with anti-CCP antibody(r=0.059,P=0.629), CRP(r=0.170, P=0.160) 、 ESR(r=0.155, P=0.199) 、 RF titer(r=-0.091, P=0.453) and DAS28 score(r=0.126,P=0.297).Conclusions:(1) Studies show that the serum IL-34 level was increased in patients with RA,and it was positively correlated with anti-CCP antibody,CRP,ESR,RF titer and DAS28 score,indicating that IL-34 might be involved in the pathological process of RA;(2)The IL-34 level was positively correlated with RANKL level in RA patients,and in RA patients with osteoporosis both IL-34 and RANKL levels were increased,and both factors were negatively correlated with bone density,suggesting IL-34 and RANKL might together promote the development of osteoporosis in RA and IL-34 might be a new biomarker for the osteoporosis of RA.