Endothelial biomarkers may be frequently altered in the peripheral blood of patients with juvenile dermatomyositis (JDM), according to study results published in the Journal of Rheumatology. Researchers indicated that markers of endothelial dysfunction were significantly increased in patients with JDM vs control participants, and these levels correlated with extramuscular activity.
Investigators obtained serum samples from 20 patients with JDM enrolled in the study from the United States National Institute of Environmental Health Sciences myositis natural history study. Using standard detection methods, myositis-specific autoantibodies were identified in the sera of 20 healthy control participants. Researchers used flow cytometry to detect circulating endothelial cells (CECs) and circulating endothelial progenitor cells (CEPCs) in blood samples. They performed plate-based assays to measure von Willebrand factor (vWF) antigen and activity, factor VIII, P-selectin, and thrombomodulin; Myositis Disease Activity Assessment tool (MDAAT) was used to evaluate disease activity and damage. Patients also underwent magnetic resonance imaging (MRI) of the thigh and pelvis to capture T1 muscle atrophy. In addition, investigators assessed nailfold capillary density and brachial artery flow dilation in all participants.
Of 20 patients with JDM, 13 (65%) were girls. Median age at evaluation was 12.1 years (interquartile range, 9.3-15.7 years). Compared with control participants, patients with JDM had significantly elevated levels of CECs, thrombomodulin, vWF antigen, and factor VIII. Researchers did not detect any significant between-group differences in vWF activity, P-selectin levels, or number of CEPCs. Among patients with JDM, CEC count was found to be significantly correlated with the MDAAT pulmonary visual analog scale (VAS) activity (rs=.056), which assessed dyspnea, dysphonia, and interstitial lung disease (P =.001). The CEPC count was inversely correlated with MDAAT muscle VAS activity and physical function in patients (rs=-0.52 to -0.53; P =.054 to .055); CEPCs also inversely correlated with MRI T1 muscle damage scores (rs=-0.53; P =.051) and with endocrine damage severity according to the Myositis Damage Index (rs=-0.56; P =.039). The vWF antigen levels were correlated with patient global activity, extramuscular VAS activity, and cutaneous VAS activity (rs=0.47 to 0.54; P =.014 to .046). The vWF antigen and activity also correlated with interleukin-10 and interferon gamma-inducible protein-10 (rs=0.82 and 0.64, respectively), each of which were associated with MDAAT extramuscular activity.
According to the researchers, these data indicate elevated levels of endothelial damage biomarkers in patients with JDM compared with control participants.
“The inverse relationship of CEPC with muscle function suggests… there may be a functional disturbance in repair mechanisms,” the investigators wrote.
Further study in a larger cohort is necessary to expand on these findings and elucidate the mechanisms that underlie endothelial marker elevation in JDM.
Kishi T, Chipman J, Evereklian M, et al. Endothelial activation markers as disease activity and damage measures in juvenile dermatomyositis [published online August 1, 2019]. J Rheumatol. doi:10.3899/jrheum.181275