Background: Interleukin-18 (IL-18) is a proinflammatory cytokine which induces interferon-γ production and plays a crucial role in immune systems. IL-18 binding protein (IL-18BP) is a naturally occurring inhibitor of IL18. The aim was to investigate the involvement of IL-18 and IL-18BP in IgA nephropathy (IgAN).
Methods: Serum samples from 21 IgAN patients and 16 idiopathic membranous nephropathy (MN) patients and 32 healthy controls were assayed by an enzyme-linked immunosorbent method.
Results: Compared to the controls, IgAN patients showed significantly higher levels of IL-18 and the increased IL18/IL-18BP ratio. Despite IL-18 elevation, the levels of IL-18BP did not parallel the increase of IL-18, which resulted in an increased IL-18/IL-18BP ratio. Furthermore, the ratio in patients with renal vasculopathy was significantly increased compared to those without arteriolar lesions.
Conclusions: These findings provide the first evidence that there is an imbalance of IL-18/IL-18BP ratio in IgAN patients, which may be associated with the pathophysiology of renal vasculopathy.