Impaired macrophage migration inhibitory factor-AMP-activated protein kinase activation and ischemic recovery in the...

Area of Science:

• Cardiovascular Research
• Aging Biology
• Molecular Cardiology

Background:

• Elderly individuals exhibit heightened sensitivity to myocardial ischemia, correlating with increased mortality rates.
• Aging significantly impacts cellular signaling pathways, including those crucial for cardiac protection.

Purpose of the Study:

• To investigate the effect of aging on the AMP-activated protein kinase (AMPK) signaling pathway, a key mediator of cardioprotection.
• To elucidate the role of macrophage migration inhibitory factor (MIF) and hypoxia-inducible factor 1alpha (HIF-1α) in age-related alterations of cardiac AMPK activation.

Main Methods:

• Comparative analysis of ischemic AMPK activation in aged versus young murine hearts.
• Assessment of macrophage migration inhibitory factor (MIF) expression and secretion, and hypoxia-inducible factor 1alpha (HIF-1α) levels in aged and young hearts.
• Evaluation of cardiac function and infarct size in MIF knockout mice and aged mice treated with adenovirus encoding MIF.

Main Results:

• Ischemic AMPK activation was significantly impaired in aged murine hearts compared to young hearts.
• Expression and secretion of MIF, an upstream regulator of AMPK, were reduced in aged hearts, linked to decreased HIF-1α levels.
• MIF deficiency exacerbated ischemia-induced contractile dysfunction, while MIF gene delivery in aged mice improved AMPK activation and reduced infarct size.

Conclusions:

• Aging-associated defects in HIF-1α reduce MIF expression, leading to an impaired MIF-AMPK activation response in senescence.
• This impaired pathway contributes to the increased susceptibility of older adults to myocardial ischemia.
• Therapeutic strategies targeting the MIF-AMPK axis may offer protection against myocardial ischemia in the elderly.