# Necroptosis induced by MLKL overexpression in liver triggers cellular senescence and leads to chronic inflammation and fibrosis

## TL;DR

Overexpression of MLKL in liver cells causes necroptosis, which leads to cellular senescence, chronic inflammation, and liver fibrosis.

## Contribution

This study is the first to directly test the interaction between necroptosis and cellular senescence in a novel Mlkl-KI mouse model.

## Key findings

- MLKL overexpression in hepatocytes increases necroptosis and cellular senescence.
- Necroptosis triggers inflammation and fibrosis through DAMPs and SASP-factors.
- Transcriptomic changes reveal altered genes in senescence, inflammation, and drug metabolism.

## Abstract

Cellular senescence and necroptosis are two cell fates, which trigger an inflammatory response and increase with age, that have been proposed to play a role in inflammaging. In this study, we performed the first study to directly test the possible interaction between necroptosis and cellular senescence. Using a novel Mlkl-KI mouse model, we were able to specifically induce (~ 4-fold) the overexpression of MLKL, the necroptotic executioner, in hepatocytes (hMlkl-KI mice). The overexpression of MLKL led to increased necroptosis and cell damage/death in liver, as shown by increased levels of MLKL-oligomers, TUNEL staining, and Ki-67 staining in the livers, as well as increased ALT activity and HMGB1 levels in the plasma. The increase in necroptosis was paralleled by an increase in cellular senescence. We observed increased levels of p16INK4A and p21Clip1/Waf1 as well as SASP-factors. As expected, inflammation, as measured by the levels of proinflammatory factors and mononuclear cell clusters, was increased in the hMlkl-KI mice. Transcriptomic analysis revealed that MLKL overexpression altered the expression of genes involved in cellular senescence, inflammation, and drug metabolism. The increase in inflammation, necroptosis, and cellular senescence in the livers of 6-month-old hMlkl-KI mice was associated with an increase in liver fibrosis. The data from our study suggest that necroptosis has the potential of inducing inflammation through two pathways: (1) the initial inflammatory storm triggered by DAMPs released from necroptotic, dying cells and (2) SASP-factors produced by senescent cells that were induced by necroptosis.

The online version contains supplementary material available at 10.1007/s11357-025-01994-y.