Clinical research of interleukin-34 in psoriatic arthritis patients

Abstract

Objective To investigate the relationship between interleukin (IL)-34 and bone erosions in psoriatic arthritis (PsA) patients. Methods Forty PsA patients, 20 psoriasis (Ps) patients and 20 healthy volunteers were recruited into this study. The levels of IL-34 and osteoclast related cytokines [including tumor necrosis factor(TNF)-α, receptor activator of nuclear factor-κB ligand (RANKL), osteoclast precursors (OPG)] were detected in the serum samples of all subjects. The correlations among IL-34, the number of osteoclast precursors (OCP), disease activity and imaging scores were analyzed. All data were analyzed by graphpad prism 6. Differences between groups was analyzed with One-way analysis of variance, q tests, and Spearman's correlation was used to explore the relation between disease activity /radiographic scores and laboratory results and followed by linear regressions. Results The serum level of IL-34 in patients with PsA [(328±476) pg/ml] was higher than that in Ps [(33 ± 52) pg/ml, q=3.92, P<0.01] and healthy controls [(32 ± 32) pg/ml, q=3.93, P<0.01], the erosive PsA group were higher than the non-erosive PsA group [(449 ± 527) pg/ml and (47 ± 24) pg/ml, q=4.04, P<0.01]. The levels of TNF-α, RANKL and OCP in patients with PsA [(125±79) pg/ml, (488± 475) pg/ml and (17.7±4.8) 5 sigh views] were higher than those in PS [(40±22) pg/ml, (26±3) pg/ml and (5.2± 0.8), q=7.32, 6.14 and 2.94, P<0.01] and healthy controls [(41±19) pg/ml, (65±8) pg/ml and (6.2±1.8), q=6.67, 5.62 and 2.71, P<0.01], whereas the OPG/RANKL ratio in PsA patients (0.5±0.4) was significantly lower than Ps patients (4.3 ± 2.7, q=-3.30, P<0.01) and healthy controls (1.8 ± 0.6, q=-1.72, P<0.01). IL-34, TNF-α and RANKL levels were all positively correlated with OCP (r=0.10, P<0.05; r=0.12, P<0.05; r=0.13, P<0.05, respectively). Conclusion The level of IL-34 is not only high in patients with PsA but also positively correlates with the number of OCP. In PsA, IL-34 is probably related to the OCP and osteoclast differentiation, and further participates in the process of bone destruction. Therefore, IL-34 is promising to become a new target or alternative choice for the treatment of PsA. Key words: Psoriatic arthritis; Iinterleukin-34; Tumor necrosis factor-α; Receptor activator of nuclear factor-κB ligand; Osteoclast precursors; Psoriatic arthritis joint activity index; Sharp score; Bath ankylosing spondylitis radiology index.