[The expression of Semaphorin 5A in patients with rheumatoid arthritis and its effect on osteoclastogenesis]

Objective: To investigate the clinical significance of soluble Semaphorin 5A(Sema 5A) in patients of rheumatoid arthritis(RA) and the effect of Sema 5A on osteoclastogenesis in RAW264.7 cells. Methods: (1)Soluble Sema 5A was detected in the serum of 62 RA patients, 30 osteoarthritis(OA) patients and 48 healthy controls(HC) by enzyme-linked immunosorbent assay(ELISA).The relationships between serum Sema 5A and disease activity, radiographic severity and laboratory parameters were investigated in RA patients.(2)RAW264.7 cells were treated with different concentrations of Sema 5A(0,0.5,1,2.5,5 μg/ml).After 7 days, tartrate-resistant acid phosphate(TRAP) staining was performed. The mRNA levels of TRAP, cathepsin-K and matrix metallopeptidase 9(MMP-9) were tested using real-time polymerase chain reaction (RT-PCR).(3)Bone resorption area of dentine slides cultured with RAW264.7 cells was calculated after Sema 5A(5μg/ml) treatment. Results: (1)The serum Sema 5A in RA patients[(5.24±0.59)μg/L] was significantly higher than those in healthy controls[(2.93±0.34)μg/L,P<0.01] and OA patients[(2.68±0.47)μg/L,P<0.05]. The Sema 5A level in RA patients was positively correlated with disease activity score with 28 joint using C-reactive protein(DAS28-CRP), clinical disease activity index (CDAI),C-reactive protein(CRP) and sharp scores(P<0.05 or P<0.01).In addition,the serum Sema 5A in RA patients with positive anti-cyclic citrullinated peptide(CCP) antibody was significantly greater than that of anti-CCP antibody-negative patients(P<0.05).(2)After RAW264.7 cells were treated with Sema 5A, the number of TRAP positive osteoclasts increased according to the increase of Sema 5A concentration with maximal effect at 5 μg/ml. Meanwhile, Sema 5A promoted mRNA expression of TRAP,Cathepsin-K and MMP-9.(3)Bone resorption area increased when RAW264.7 cells were treated with Sema 5A(5 μg/ml). Conclusions: Serum Sema 5A is elevated in RA patients and correlated with disease activity and radiographic severity. Sema 5A promotes osteoclastogenesis of RAW264.7 cells.