p53 protects against LPS-induced lung endothelial barrier dysfunction

Area of Science:

• Molecular Biology
• Cardiovascular Research
• Inflammation Studies

Background:

• Heat shock protein 90 (Hsp90) inhibitors are being explored for cardiovascular therapies.
• Their anti-inflammatory effects in human tissues are noted, but mechanisms in vasculature are unclear.
• The transcription factor p53, an Hsp90 client, plays a role in cellular stress responses.

Purpose of the Study:

• To investigate the role of the transcription factor p53 in vascular integrity and the anti-inflammatory effects of Hsp90 inhibitors.
• To elucidate the molecular mechanisms linking Hsp90 inhibition, p53, and vascular inflammation.

Main Methods:

• Utilized siRNA to silence p53, p53 inhibitors (pifithrin), and inducers (nutlin) in human lung microvascular endothelial cells (HLMVEC).
• Administered Hsp90 inhibitors in vivo and in vitro to assess effects on p53 expression and its regulators (MDMX, MDM2) following LPS challenge.
• Measured transendothelial electrical resistance, RhoA activation, and MLC2 phosphorylation to assess endothelial barrier function and inflammatory signaling.

Main Results:

• p53 silencing or inhibition worsened endothelial barrier dysfunction and potentiated LPS-induced hyperpermeability.
• p53 induction suppressed LPS-induced vascular barrier dysfunction.
• Hsp90 inhibitors blocked LPS-induced decrease in p53 expression and modulated p53 regulators (MDMX, MDM2).
• p53 activation suppressed LPS-induced RhoA activation and MLC2 phosphorylation, indicating improved vascular stability.

Conclusions:

• The transcription factor p53 is vital for maintaining vascular integrity and mediates the anti-inflammatory actions of Hsp90 inhibitors.
• Hsp90 inhibitors protect the vasculature by inducing p53, which counteracts inflammatory responses.
• These findings reveal a novel therapeutic pathway for vascular disorders involving Hsp90-p53 interactions.