Circulating midkine in children with Henoch-Schönlein purpura: Clinical implications

• This is the first report on midkine (MK) in children with HSP.
• Serum midkine level was elevated at the onset of the disease in children with HSP.
• There is an abnormal production of cytokines in children with HSP.
• MK positively correlated with IL-4, IL-6, IL17A, IgA and IgE.
• MK could be used as an efficient indicator for an early diagnosis of HSPN.

BackgroundMidkine (MK) is a heparin-binding growth factor, which behaves like a cytokine, involved in various cellular processes such as cellular proliferation, differentiation, survival, adhesion, and migration. Studies provided evidence for a role of MK in acute and chronic inflammatory processes. The association between midkine and Henoch-Schönlein purpura (HSP) has not yet been explored. The aim of our study was to investigate the potential role of midkine in children with HSP.MethodsA total of 152 cases consisting of 92 children with HSP and 60 age- and sex-matched healthy control children were enrolled in this prospective study. Circulating midkine, IL-2, IL-4, IL-6, IL-10, TNF, IFN-γ, and IL-17A was measured in all of the 92 patients and 60 healthy controls. Midkine diagnostic value was evaluated by receiver operating characteristic (ROC) analysis.ResultsRenal involvement occurred in 36 of the 92 patients. Circulating midkine level was elevated in children with HSPN than those of patients without renal involvement and of the controls (326.58 (266.58–459.25) pg/ml versus 280.72 (233.67–384.36) pg/ml and 217.3 (198.98–243.65) pg/ml, respectively; P < 0.05). Midkine positively correlated with IL-4, IL-6, IL17A, IgA and IgE. The threshold MK concentration of HSPN was 295.58 pg/ml, with the sensitivity and specificity of 80.6% and 88.3%, respectively. The area under the receiver operating characteristic (ROC) curve (AUCROC) of MK was 0.902.ConclusionsMK seems to be involved in the development of HSP. Measurement of serum levels of MK is helpful in confirming the diagnosis of HSP and predicting HSPN.