1
|
Okuhara Y, Yokoe S, Iwasaku T, Eguchi A, Nishimura K, Li W, Oboshi M, Naito Y, Mano T, Asahi M, Okamura H, Masuyama T, Hirotani S. Interleukin-18 gene deletion protects against sepsis-induced cardiac dysfunction by inhibiting PP2A activity. Int J Cardiol 2017; 243:396-403. [PMID: 28526544 DOI: 10.1016/j.ijcard.2017.04.082] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/07/2016] [Revised: 02/20/2017] [Accepted: 04/24/2017] [Indexed: 11/30/2022]
Abstract
BACKGROUND Interleukin-18 (IL-18) neutralization protects against lipopolysaccharide (LPS)-induced injuries, including myocardial dysfunction. However, the mechanism is yet to be fully elucidated. The aim of the present study was to determine whether IL-18 gene deletion prevents sepsis-induced cardiac dysfunction and to elucidate the potential mechanisms underlying IL-18-mediated cardiotoxicity by LPS. METHODS AND RESULTS Ten-week-old male wild-type (WT) and IL-18 knockout (IL-18 KO) mice were intraperitoneally administered LPS. Serial echocardiography showed better systolic pump function and less left ventricular (LV) dilatation in LPS-treated IL-18 KO mice compared with those in LPS-treated WT mice. LPS treatment significantly decreased the levels of phospholamban (PLN) and Akt phosphorylation in WT mice compared with those in saline-treated WT mice, while the LPS-induced decrease in the phosphorylation levels was attenuated in IL-18 KO mice compared with that in WT mice. IL-18 gene deletion also attenuated an LPS-induced increase of type 2 protein phosphatase 2A (PP2A) activity, a molecule that dephosphorylates PLN and Akt. There was no difference in type 1 protein phosphatase (PP1) activity. To address whether IL-18 affects PLN and Akt phosphorylation via PP2A activation in cardiomyocytes, rat neonatal cardiac myocytes were cultured and stimulated using 100ng/ml of recombinant rat IL-18. Exogenous IL-18 decreased the level of PLN and Akt phosphorylation in cardiomyocytes. PP2A activity but not PP1 activity was increased by IL-18 stimulation in cardiomyocytes. CONCLUSIONS IL-18 plays a pivotal role in advancing sepsis-induced cardiac dysfunction, and the mechanisms underlying IL-18-mediated cardiotoxicity potentially involve the regulation of PLN and Akt phosphorylation through PP2A activity.
Collapse
Affiliation(s)
- Yoshitaka Okuhara
- Cardiovascular Division, Department of Internal Medicine, Hyogo College of Medicine, Nishinomiya, Japan
| | - Shunichi Yokoe
- Department of Pharmacology, Faculty of Medicine, Osaka Medical College, Osaka, Japan
| | - Toshihiro Iwasaku
- Cardiovascular Division, Department of Internal Medicine, Hyogo College of Medicine, Nishinomiya, Japan
| | - Akiyo Eguchi
- Cardiovascular Division, Department of Internal Medicine, Hyogo College of Medicine, Nishinomiya, Japan
| | - Koichi Nishimura
- Cardiovascular Division, Department of Internal Medicine, Hyogo College of Medicine, Nishinomiya, Japan
| | - Wen Li
- Laboratory of Tumor Immunology and Cell Therapy, Hyogo College of Medicine, Nishinomiya, Japan
| | - Makiko Oboshi
- Cardiovascular Division, Department of Internal Medicine, Hyogo College of Medicine, Nishinomiya, Japan
| | - Yoshiro Naito
- Cardiovascular Division, Department of Internal Medicine, Hyogo College of Medicine, Nishinomiya, Japan
| | - Toshiaki Mano
- Cardiovascular Division, Department of Internal Medicine, Hyogo College of Medicine, Nishinomiya, Japan
| | - Michio Asahi
- Department of Pharmacology, Faculty of Medicine, Osaka Medical College, Osaka, Japan
| | - Haruki Okamura
- Laboratory of Tumor Immunology and Cell Therapy, Hyogo College of Medicine, Nishinomiya, Japan
| | - Tohru Masuyama
- Cardiovascular Division, Department of Internal Medicine, Hyogo College of Medicine, Nishinomiya, Japan
| | - Shinichi Hirotani
- Cardiovascular Division, Department of Internal Medicine, Hyogo College of Medicine, Nishinomiya, Japan.
| |
Collapse
|