Phenytoin inhibits necroptosis

Area of Science:

• Biochemistry
• Immunology
• Pathology

Background:

• Receptor-interacting protein kinases 1 and 3 (RIPK1/3) are key mediators of necroptosis, a regulated form of necrosis.
• While RIPK3-deficient mice show protection in disease models, direct in vivo evidence of necroptosis activation is limited.
• This study investigates necroptosis activation in kidney ischemia-reperfusion injury (IRI) and TNFα-induced severe inflammatory response syndrome (SIRS).

Purpose of the Study:

• To examine necroptosis activation in kidney IRI and SIRS models.
• To investigate the role of mixed lineage kinase domain-like (MLKL) in these injuries.
• To identify potential therapeutic inhibitors of necroptosis.

Main Methods:

• Utilized MLKL-knockout (MLKL-ko) and RIPK3-deficient mice models.
• Analyzed pMLKL accumulation in human acute kidney injury patient samples.
• Screened clinical plasma membrane channel blockers, including phenytoin, for necroptosis inhibition.
• Assessed phenytoin's effect on RIPK1 kinase activity and necrosome formation in vitro.
• Evaluated phenytoin's protective effects in vivo against kidney IRI and SIRS.

Main Results:

• MLKL-ko mice exhibited significant protection in both kidney IRI and SIRS models, exceeding that of RIPK3-deficient mice.
• Accumulation of phosphorylated MLKL (pMLKL) was observed in necrotic tubules of human acute kidney injury patients.
• Phenytoin inhibited necroptosis in vitro by attenuating RIPK1 kinase activity and blocking necrosome formation.
• Phenytoin demonstrated protective effects against kidney IRI and TNFα-induced SIRS in vivo.

Conclusions:

• RIPK3-pMLKL pathway is crucial in acute kidney injury.
• Phenytoin, an anti-convulsant drug, effectively inhibits necroptosis and protects against kidney IRI and SIRS.
• Phenytoin warrants clinical evaluation for treating diseases involving RIPK1/RIPK3-mediated cell death.