Granzyme B is a novel interleukin-18 converting enzyme

Omoto, Youichi; Yamanaka, Keiichi; Tokime, Kazuya; Kitano, Shigehisa; Kakeda, Masato; Akeda, Tomoko; Kurokawa, Ichiro; Gabazza, Esteban C.; Tsutsui, Hiroko; Katayama, Naoyuki; Yamanishi, Kiyofumi; Nakanishi, Kenji; Mizutani, Hitoshi

doi:10.1016/j.jdermsci.2010.05.004

« Previous Next »Journal of Dermatological Science
Volume 59, Issue 2 , Pages 129-135, August 2010

Granzyme B is a novel interleukin-18 converting enzyme

Youichi Omoto
- Department of Dermatology, Mie University, Graduate School of Medicine, Tsu, Mie 514-8507, Japan
Keiichi Yamanaka
- Department of Dermatology, Mie University, Graduate School of Medicine, Tsu, Mie 514-8507, Japan
Kazuya Tokime
- Department of Dermatology, Mie University, Graduate School of Medicine, Tsu, Mie 514-8507, Japan
Shigehisa Kitano
- Department of Hematology and Oncology, Mie University, Graduate School of Medicine, Tsu, Mie 514-8507, Japan
Masato Kakeda
- Department of Dermatology, Mie University, Graduate School of Medicine, Tsu, Mie 514-8507, Japan
Tomoko Akeda
- Department of Dermatology, Mie University, Graduate School of Medicine, Tsu, Mie 514-8507, Japan
Ichiro Kurokawa
- Department of Dermatology, Mie University, Graduate School of Medicine, Tsu, Mie 514-8507, Japan
Esteban C. Gabazza
- Immunology, Mie University, Graduate School of Medicine, Tsu, Mie 514-8507, Japan
Hiroko Tsutsui
- Department of Microbiology, Hyogo College of Medicine, Nishinomiya 663-8501, Japan
Naoyuki Katayama
- Department of Hematology and Oncology, Mie University, Graduate School of Medicine, Tsu, Mie 514-8507, Japan
Kiyofumi Yamanishi
- Dermatology, Hyogo College of Medicine, Nishinomiya 663-8501, Japan
Kenji Nakanishi
- Department of Immunology & Medical Zoology, Hyogo College of Medicine, Nishinomiya 663-8501, Japan
Hitoshi Mizutani
- Department of Dermatology, Mie University, Graduate School of Medicine, Tsu, Mie 514-8507, Japan
- Corresponding author. Tel.: +81 59 231 5422; fax: +81 59 231 5423.

Received 9 December 2009; received in revised form 28 April 2010; accepted 14 May 2010. published online 12 July 2010.

Abstract

Background

Granzyme B (GrB) is recognized to induce apoptosis; however, little is known about its possible role in other biological events. IL-18, a potent inflammatory cytokine, is produced as an inactive precursor (proIL-18). Several cells, including monocytes/macrophage lineage and non-hematopoietic cells such as keratinocytes, produce proIL-18. ProIL-18 requires appropriate processing to become active. Caspase-1 is the authentic IL-18 processing enzyme and is essential for IL-18 release from monocyte/macrophage lineage cells. However, caspase-1 is absent in non-hematopoietic cells, suggesting that there is another candidate to cleave proIL-18 except for caspase-1.

Objective

GrB can invade and be active in cytoplasm of non-hematopoietic cells via perforin, therefore we investigated whether GrB converts proIL-18 into the biologically active form.

Methods

Recombinant proIL-18 (rproIL-18) was produced and purified for protease reaction with GrB; this incubate was evaluated by immunoblotting. Biological activity of the proteolytic fragment cleaved by GrB was determined by IFN-γ assay using KG-1 cells. IFN-γ induction was also analyzed between extracts from GrB(+)/caspase-1(−) human CD8+ T cells and proIL-18 from normal human keratinocytes (NHK).

Results

The proteolytic fragment that GrB cleaved proIL-18 had the same sequence and biological activity compared with mature IL-18 cleaved by caspase-1. Culture extracts from CD8+ T cells was able to cleave proIL-18 into authentic mature IL-18. IFN-γ induction was also detected in NHK treated with CD8+ T cells.

Conclusion

GrB is a potent IL-18 converting enzyme and suggest that GrB secreted by CTLs and/or NK cells may initiate IL-18 release from target cells, leading to the development of inflammation.

Abbreviations: matIL-18, mature IL-18, AD, atopic dermatitis, proIL-18, precursor interleukin-18, rproIL-18, recombinant precursor interleukin-18, CBB, Coomassie Brilliant Blue, GrB, granzyme B, GVHD, graft-versus-host disease, benzyloxycarbonyl-Ala-Ala-Asp-chloromethylketone, Z-AAD-CMK, NHK, normal human keratinocyte, aGrB-pAb, rabbit anti-human Granzyme B polyclonal Antibody