第50回日本理学療法学術大会

講演情報

口述

英語 口述3

Animal Experiments

2015年6月5日(金) 12:30 〜 13:30 第6会場 (ホールD7)

座長:Jiro Nakano(長崎大学 大学院医歯薬学総合研究科保健学専攻)

[O-0103] IL-1β/TGF-β1 up-regulation and hypoxia induced in immobilization are related to the molecular mechanisms governing muscle contracture

Yuichiro Honda1,2, Junya Sakamoto3, Jiro Nakano3, Hideki Kataoka4, Ryo Sasabe1,2, Kyo Goto2,4, Miho Tanaka3, Minoru Okita2 (1.Department of Rehabilitation, Nagasaki University Hospital, 2.Department of Locomotive Rehabilitation Science, Unit of Rehabilitation Sciences, Nagasaki University Graduate School of Biomedical Sciences, 3.Department of Physical Therapy Science, Unit of Physical and Occupational Therapy Sciences, Nagasaki University Graduate School of Biomedical Sciences, 4.Department of Rehabilitation, Nagasaki Memorial Hospital)

キーワード:muscle contracture, IL-1β/TGF-β1, hypoxia

【Purpose】
This investigation was conducted to determine the molecular mechanism underlying muscle contracture in immobilized rat soleus muscle.
【Methods】
Wistar rats were divided randomly into immobilization groups(n=25)and control groups(n=25). In the immobilization group, both ankle joints were fixed in full plantar flexion with plaster casts for 1, 2, 4, 8, and 12 weeks. The right soleus muscle was immunostained for CD-11b, which is a macrophage marker, α-SMA, which is a myofibroblast marker, and type I and III collagen. Additionally, the left soleus muscle was used to detect the mRNA expression of HIF-1α, which is a hypoxic marker, IL-1β, TGF-β1, α-SMA, and type I and III collagen by RT-PCR.
【Results】
The levels of CD-11b and α-SMA protein, IL-1β and TGF-β1 mRNA, and type I and III collagen protein and mRNA were significantly higher in the immobilization group than in the controls at each time point. HIF-1α mRNA levels were significantly higher in the immobilization group than in the controls at 4 weeks. Moreover, HIF-1α, α-SMA, and type I collagen levels were significantly higher at 4, 8, and 12 weeks than at 1 and 2 weeks in the immobilization group.
【Discussion】
In the early stages of immobilization(1 to 2 weeks after immobilization), the up-regulation of IL-1β/TGF-β1 via macrophages may activate fibroblasts and promote their differentiation into myofibroblasts, and that may be associated with the over-expression of type I and III collagen. Additionally, the soleus muscle became hypoxic after 4 weeks of immobilization. Thus, hypoxia accelerates fibrosis and these alterations may influence the progression of muscle contracture in the later stages of immobilization(4, 8, and 12 weeks after immobilization).