Hepcidin in Kawasaki disease: upregulation by acute inflammation in patients having resistance to intravenous immunoglobulin therapy

Hepcidin is an iron metabolism inhibitor that increases with chronic inflammation. However, it is unclear whether hepcidin indicates acute inflammatory response in Kawasaki disease (KD), which is an acute systemic vasculitis. In this study, we examined the serum hepcidin levels before and after intravenous immunoglobulin (IVIG) therapy in responders and non-responders to IVIG. This was a pilot prospective observational study at a university hospital. All KD patients were initially administered 2 g/kg of IVIG as the first IVIG therapy (IVIG₁) on day 4 to day 7 after onset. Non-responders to IVIG₁ were additionally treated with the second IVIG therapy (IVIG₂) using 1 g/kg of IVIG. All KD patients were also treated with aspirin. We measured serum hepcidin levels before IVIG₁, after IVIG₁, and during the recovery period. Among the 31 KD patients, 21 patients and 5 patients improved after IVIG₁ (responders-1) and IVIG₂ (responders-2), respectively, but 5 patients did not improve after IVIG₂ (non-responders). Serum hepcidin levels before IVIG₁ were significantly higher in responders-2 (159.0 ng/mL) and non-responders (240.0 ng/mL), compared to responders-1 (103.0 ng/mL). Serum hepcidin levels after IVIG₁ were significantly higher in non-responders (163.0 ng/mL), compared to responders-1 (43.4 ng/mL) and responders-2 (54.6 ng/mL). Serum hepcidin levels of non-responders to IVIG were higher before IVIG and remained high after IVIG. Erythrocyte-related indexes, including hemoglobin, reticulocytes, iron, and ferritin before IVIG₁, were not significantly different among the three groups. Serum hepcidin might be excessively upregulated by acute inflammation in KD patients having resistance to IVIG.