Long-term changes in nail fold capillary abnormalities and serum fibroblast growth factor 23 levels in dermatomyositis patients with anti-melanoma differentiating antigen 5 antibody.

Nail fold videocapillaroscopy (NVC) abnormalities are a characteristic finding of microangiopathy in dermatomyositis (DM). The aim of the present study was to examine long-term changes in NVC abnormalities and serum fibroblast growth factor 23 (FGF23) and vascular endothelial growth factor (VEGF) levels in DM patients with anti-melanoma differentiation-associated gene 5 (MDA5) antibody (Ab). Serum levels of FGF23 and VEGF were measured by enzyme-linked immunosorbent assay. NVC abnormalities were evaluated by capillaroscopy in 11 DM patients with anti-MDA5 Ab at baseline and after treatment. NVC abnormalities included irregularly enlarged capillaries, reduced capillaries, hemorrhages, capillary ramifications, disorganization of the vascular array, loss of capillaries and giant capillaries. Serum FGF23 levels were significantly decreased in patients with anti-MDA5 Ab (0.3 ± 0.3 pmol/L) compared with healthy controls (1.0 ± 0.6 pmol/L, P < 0.01). Serum FGF23 levels significantly increased after treatment (0.3 ± 0.3 vs 1.0 ± 0.7 pmol/L, P < 0.005), but serum VEGF levels were comparable between at baseline and after treatment. At baseline, irregularly enlarged capillaries were observed in 10 of 11 patients, but after treatment, they were significantly reduced in only two (91% vs 18%, P < 0.001). Hemorrhages were observed in all 11 patients at baseline, but disappeared in all after treatment (100% vs 0%, P < 0.001). These results suggest that NVC abnormalities are reversible by treatment and that serum FGF23 levels reflect the degree of microvascular damage in DM patients with anti-MDA5 Ab.