Local Acute Phase Response in Myocardial Tissue

• Project/Area Number: 06670748
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Single-year Grants
• Section: 一般
• Research Field: Circulatory organs internal medicine
• Research Institution: Nippon Medical School
• Principal Investigator: NAGAE Yasuhiro Nippon Medical School, Dept.of Medicine, 医学部, 助手 (10189102)
• Co-Investigator(Kenkyū-buntansha): TOMITA Yoshifumi Nippon Medical School, Dept.of Medicine, 医学部, 助手 (00180175) ; SEINO Yoshihiko Nippon Medical School, Dept.of Medicine, 医学部, 講師 (10163073)
• Project Period (FY): 1994 – 1996
• Project Status: Completed (Fiscal Year 1996)
• Budget Amount: ¥2,200,000 (Direct Cost: ¥2,200,000); Fiscal Year 1996: ¥600,000 (Direct Cost: ¥600,000); Fiscal Year 1995: ¥700,000 (Direct Cost: ¥700,000); Fiscal Year 1994: ¥900,000 (Direct Cost: ¥900,000)
• Keywords: Hemopexin / Interleukin-6 / Cardiac myocyte / 局所急性期反応 / ヘモベキシン / 急性期反応 / サイトカイン / 組織レニン・アンギオテンシン系 / アンチオキシダント

Research Abstract

To elucidate molecular mechanisms of local acute phase response in myocardial tissue, tissue expression of hemopexin (Hx) gene was investigated.
To determine the expression levels of Hx, the 239bp region (exon9 - exon10) of rat Hx mRNA was amplifiedbyquantitativeRT-PCR standardized with aninternal control. As an acute myocardial injury model, rat neonatal cardiac myocytes were cultured in serum free medium for 24 hours supplemented with heme (20uM), ethanol (100mM) or cytokines contained in a conditioned medium (CM,5%) of LPS stimulated rat macrophages. Hx mRNA levels were induced by 5-fold in response to CM (cytokines) but unchanged by the direct cytotoxic stimuli (heme or ehtanol). As a chronic myocardial injury model, total RNAs were extracted from adriamycin cardiomyopathy rat hearts. Significant changes of Hx expression could not be detected. By histopathological examination, severe myocardial damage caused by adriamycin cardiotoxicity was prominent (histologic index ; 3.3+0.7 vs 0.6+0.6 in controls, mean+SD), whereas immunocytes response was poor. Thus, induction of myocardial Hx is considered to be mediated by indirect mechanism involving cytokines.
To investigate transcriptional regulation of Hx, CAT assays were performed. 5' flanking region of Hx gene exhibited promoter activity in cardiac myocytes as well as hepatocytes. These results suggest that locally synthesized Hx constitutes acute phase response in the myocardium to function as a physiological antioxidant to myocardialinjury.