Lethal hydrogen peroxide toxicity involves lysosomal iron-catalyzed reactions with membrane damage

Area of Science:

• Cell Biology
• Biochemistry
• Oxidative Stress Research

Background:

• Secondary lysosomes accumulate iron complexes from protein degradation.
• Iron-catalyzed reactions with hydrogen peroxide can damage lysosomal membranes and release cellular contents.
• Cellular resistance to oxidative stress is influenced by lysosomal reactive iron and hydrogen peroxide degradation capacity.

Purpose of the Study:

• To investigate the effects of hydrogen peroxide on cell viability and lysosomal membrane integrity.
• To evaluate the protective role of the iron-chelator desferal against hydrogen peroxide-induced cellular damage.
• To understand the mechanism of desferal's protection, considering endocytosis.

Main Methods:

• Cultured J-774 cells were exposed to hydrogen peroxide.
• Lysosomal membrane integrity was assessed using acridine orange, lucifer yellow, neutral red, and cathepsin D relocalization.
• Cell viability and plasma membrane blebbing were monitored.
• The effect of desferal (an iron-chelator) was tested, with and without inhibition of endocytosis.

Main Results:

• Hydrogen peroxide exposure led to a time-dependent decrease in cell viability and lysosomal proton gradient reduction.
• Early signs of damage included plasma membrane blebbing and lysosomal destabilization, indicated by marker redistribution.
• Pre-treatment with desferal effectively prevented hydrogen peroxide-induced cell damage and lysosomal destabilization.
• Desferal's protective effect was dependent on its cellular uptake via endocytosis.

Conclusions:

• Lysosomal reactive iron plays a critical role in hydrogen peroxide-induced cellular damage.
• Desferal confers significant protection against oxidative stress by chelating iron and stabilizing lysosomal membranes.
• The cellular uptake of desferal is essential for its protective mechanism against oxidative damage.