The cardioprotection induced by lipopolysaccharide involves phosphoinositide 3-kinase/Akt and high mobility group box...

Area of Science:

• Cardiovascular Research
• Molecular Cardiology
• Cellular Signaling

Background:

• Ischemia/reperfusion (I/R) injury remains a significant challenge in cardiovascular medicine.
• The precise molecular mechanisms underlying lipopolysaccharide (LPS)-induced cardioprotection are not fully understood.
• Investigating signaling pathways involved in I/R injury can reveal novel therapeutic targets.

Purpose of the Study:

• To elucidate the mechanisms of lipopolysaccharide (LPS) pretreatment-induced cardioprotection against ischemia/reperfusion (I/R) injury.
• To investigate the roles of phosphoinositide 3-kinase (PI3K)/Akt and high mobility group box 1 (HMGBx1) signaling pathways in LPS-induced cardioprotection.
• To determine if LPS pretreatment influences cardiac myocyte apoptosis and specific molecular pathways in vitro and in vivo.

Main Methods:

• In vivo studies utilized C57BL/10Sc wild type mice pretreated with LPS before inducing myocardial I/R, assessing infarct size and apoptosis.
• Key proteins Akt, phospho-Akt, and HMGBx1 were quantified using immunoblotting.
• In vitro studies used rat cardiac myoblasts (H9c2) exposed to hypoxia after LPS pretreatment, with HMGBx1 levels assessed via immunoblot.

Main Results:

• LPS pretreatment significantly reduced infarct size (by up to 70.6%) and cardiac myocyte apoptosis (by 39.1%) in a mouse model of I/R.
• Mechanistically, LPS pretreatment increased PI3K/Akt activity and decreased HMGBx1 expression in the myocardium.
• In vitro, LPS pretreatment reduced cytoplasmic HMGBx1 levels in hypoxic cardiac myoblasts.

Conclusions:

• LPS pretreatment confers significant cardioprotection against I/R injury.
• The protective effects involve the activation of the PI3K/Akt signaling pathway.
• Modulation of high mobility group box 1 (HMGBx1) expression is a key component of LPS-induced cardioprotection.