Increased expression of vascular cell adhesion molecule 1 in muscle biopsy samples from juvenile dermatomyositis patients with short duration of untreated disease is regulated by miR-126

Kim, E.; Cook-Mills, J.; Morgan, G.; Sredni, S. T.; Pachman, L. M.

Arthritis Rheum. 2012 Jun 29; 64(11):3809-17

Abstract

OBJECTIVE: To evaluate the effect of duration of untreated disease on vascular cell adhesion molecule 1 (VCAM-1) and microRNA (miRNA) expression in muscle biopsy samples from children with juvenile dermatomyositis (DM) as well as its effect on soluble VCAM-1 (sVCAM-1) and tumor necrosis factor alpha (TNFalpha) concentrations in sera from these children. METHODS: We enrolled 28 untreated children with juvenile DM and 8 pediatric controls. Eleven children with juvenile DM had short duration of untreated disease (symptoms for 2 months before muscle biopsy). Vascular structures, characterized by immunofluorescence using antibodies against von Willebrand factor, VCAM-1, and alpha-smooth muscle actin, were measured for total area and intensity. Circulating sVCAM-1 and TNFalpha levels were determined in patients with short duration of untreated disease, patients with long duration of untreated disease, and controls. Differential expression of microRNA-126 (miR-126) in muscle biopsy samples from the 2 patient groups and the control group was detected by miRNA expression profiling and confirmed by quantitative reverse transcription-polymerase chain reaction in muscle biopsy samples from the 3 groups. RESULTS: Juvenile DM patients with short duration of untreated disease had significantly higher total positive area and intensity/high power field of VCAM-1 expression than did juvenile DM patients with long duration of untreated disease (P = 0.043 and P = 0.015, respectively) or controls (P = 0.004 and P = 0.001, respectively). Von Willebrand factor antigen-positive vasculature displayed greater VCAM-1 intensity in patients with short duration of untreated disease than in patients with long duration of untreated disease (P = 0.001). Circulating levels of sVCAM-1 and TNFalpha were significantly higher in patients with short duration of untreated disease than in controls (P = 0.013 and P = 0.048, respectively). The miRNA miR-126, a negative regulator of VCAM-1 expression, was significantly decreased (3.39-fold; P < 0.006) in patients with short duration of untreated disease compared to controls, while miR-126 expression in patients with long duration of untreated disease did not differ significantly compared to controls. CONCLUSION: In patients with short duration of untreated disease, miR-126 down-regulation is associated with increased VCAM-1 in both muscle and blood, suggesting that VCAM-1 plays a critical role early in juvenile DM disease pathophysiology, augmented by TNFalpha.

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