Vol.22 No.1

Original Article

High circulating levels of interleukin-18 binding protein indicate the severity of glomerular involvement in systemic lupus erythematosus

Authors

Chie Shimizu1 , Takayuki Fujita1 , Yoshinobu Fuke1 , Ken Ito1 , Atsushi Satomura2 , Koichi Matsumoto3 , Masayoshi Soma1,4

  • Department of Nephrology, Hypertension and Endocrinology, Nihon University School of Medicine, 30-1 Oyaguchi-kamimachi, Itabashiku, Tokyo, 173-8610, Japan
  • Department of Laboratory Medicine, Nihon University School of Medicine, Tokyo, Japan
  • The University Research Center, Nihon University School of Medicine, Tokyo, Japan
  • Department of General Medicine, Nihon University School of Medicine, Tokyo, Japan
Received:

31 January 2011

Accepted:

6 May 2011

Published online:

9 June 2011

Full Text

PDF　(member's only)

Abstract

In systemic lupus erythematosus (SLE), glomerular involvement often progresses with the activity of the disease. Immune complexes and abnormal secretion of cytokines are thought to be involved in the central mechanism of the development of lupus nephritis. We investigated serum levels of interleukin 18 (IL-18), a proinflammatory cytokine, and its natural antagonist IL-18 binding protein (IL-18 BP) in 45 patients with lupus nephritis. IL-18 levels were significantly increased in patients with Class II, Class III, and Class IV lupus nephritis compared with the level in a healthy control group. However, the levels stayed within the non-significant range in Class V. IL-18 BP levels were significantly increased in patients with Class III and Class IV lupus nephritis, in which histological activity and chronicity are severe. However, IL-18 BP levels stayed within the non-significant range in Class II and Class V, in which histological markers are mild. We also compared the levels of IL-18 and IL-18 BP in patients with and without glomerular infiltration of inflammatory cells. IL-18 was increased regardless of glomerular infiltration. However, IL-18 BP was increased only in patients with glomerular infiltration. These data suggest that IL-18 levels indicate the extent of the offending inflammatory response not only in the bloodstream but also in renal tissue, and that high IL-18 BP levels indicate the severity of existing glomerular injury.

Key words

Glomerular involvement - Interleukin-18 - Interleukin-18 binding protein - Proinflammatory cytokine - Systemic lupus erythematosus