Correlation between sarcopenia and nailfold microcirculation, serum 25-hydroxycholecalciferol (vitamin D3) and IL-17 levels in female patients with rheumatoid arthritis.

AIMS To investigate the correlation between sarcopenia and nailfold microcirculation and serum 25-hydroxycholecalciferol [25 (OH) D3] (instead of 25-hydroxyvitamin D) and IL-17 levels in female rheumatoid arthritis (RA) patients. METHODS 130 female rheumatoid arthritis (RA) patients and 80 healthy controls were tested. Nailfold capillaroscopic scores (NFCS) were measured. Bioimpedance analysis (BIA) was used to measure skeletal muscle mass. Enzyme-linked immunosorbant assay (ELISA) was used to detect the levels of IL-17, IL-6 and TNF-α. Serum 25 (OH) D3 concentration was determined by photochemical immunoassay. The correlation was analyzed by Pearson's correlation, and the influencing factors were analyzed by binary logistic regression. RESULTS (1) Compared with the control group, NFCS and serum IL-17 levels were higher in the RA group, while the serum 25 (OH) D3 and skeletal mass index (SMI) were lower. (2) Pearson correlation analysis found: SMI was positively correlated with 25 (OH) D3 (r=0.515, P<0.001), SMI was negatively correlated with IL-17 (r=-0.468, P<0.001), SMI was negatively correlated with NFS (r = -0.229, P=0.009); (3) Logistic regression analysis: serum 25 (OH) D3 was a protective factor for sarcopenia (OR=0.392, P=0.016); IL-17, C-reactive protein, and NFS were risk factors for sarcopenia (OR=1.516, P=0.049; OR=1.469, P=0.045; OR=3.497, P=0.002). CONCLUSION Secondary sarcopenia in RA is common and is closely related to microcirculation abnormalities. Increased NFCS is a risk factor for sarcopenia. Decreased serum 25 (OH) D3 levels and increased IL-17 are also risk factors for sarcopenia, but the mechanisms involved in sarcopenia and microcirculation abnormalities need further investigation.