RIP kinase-dependent necrosis drives lethal systemic inflammatory response syndrome

Area of Science:

• Immunology
• Cell Biology
• Pathology

Background:

• Tumor necrosis factor receptor 1 (TNFR1) signaling initiates survival-inflammation or cell death pathways.
• Cell death can proceed via apoptosis or receptor-interacting protein kinase (RIPK)-mediated necrosis (necroptosis).

Purpose of the Study:

• To investigate the roles of apoptosis and necroptosis in TNF-induced systemic inflammatory response syndrome (SIRS).
• To identify potential therapeutic targets for SIRS and sepsis by examining the necroptotic pathway.

Main Methods:

• Utilized genetic deletion of caspases (caspase-3, -7, -1) and RIPK3 in mouse models of SIRS.
• Administered necrostatin-1, a RIPK1 kinase inhibitor, to assess its protective effects.
• Evaluated SIRS mortality and levels of circulating damage-associated molecular patterns (DAMPs).
• Tested RIPK3 deficiency in a cecal ligation and puncture (CLP) sepsis model.

Main Results:

• Deletion of apoptotic caspases or inflammatory caspase-1 did not affect lethal SIRS.
• Complete protection against lethal SIRS was observed in RIPK3-deficient mice.
• RIPK3 deficiency significantly reduced circulating DAMPs and mortality in both TNF-induced SIRS and CLP sepsis models.
• Necrostatin-1 pretreatment mimicked the protective effects of RIPK3 deficiency.

Conclusions:

• RIPK1-RIPK3-mediated necroptosis, not apoptosis, is the primary driver of mortality in TNF-induced SIRS.
• RIPK kinase inhibition represents a promising therapeutic strategy for SIRS and sepsis.
• Components of the necroptotic pathway are viable therapeutic targets for inflammatory conditions.