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WIP1 Limits Renal Pyroptosis via p38 MAPK in Septic AKI
2026-08-03
WIP1 Phosphatase Regulates Pyroptosis in Sepsis-Related Acute Kidney Injury
Study Background and Research Question
Sepsis-associated acute kidney injury (AKI) is a critical complication in intensive care patients, contributing to high morbidity and mortality worldwide. The etiology of septic AKI is complex, involving metabolic dysregulation, microvascular dysfunction, and pronounced renal inflammation. Recent research points to pyroptosis—a form of programmed necrotic cell death mediated by inflammasome activation—as a pivotal driver of tissue injury in this context. However, the endogenous molecular brakes on pyroptosis within kidney tissue during sepsis remain insufficiently characterized. The present study, WIP1-mediated regulation of p38 MAPK signaling attenuates pyroptosis in sepsis-associated acute kidney injury, addresses whether the phosphatase WIP1 (wild-type p53-induced phosphatase 1, PPM1D) modulates pyroptosis in renal tubular cells following septic insult, and delineates the underlying signaling pathways.Key Innovation from the Reference Study
A major contribution of this research is the identification of WIP1 as a negative regulator of p38 MAPK-mediated pyroptosis in the setting of sepsis-induced AKI. The study demonstrates that WIP1 expression increases in renal tubular cells during acute injury and repair phases, and that pharmacological inhibition of WIP1 exacerbates LPS-induced pyroptotic cell death in both mouse and human kidney cell models. Mechanistically, the findings show that WIP1 restrains p38 MAPK phosphorylation, thereby limiting activation of the NLRP3 inflammasome and downstream cleavage of gasdermin-D (GSDMD), a central effector of pyroptosis. This mechanistic link provides new insight into how the kidney may intrinsically counteract inflammatory cell death during septic injury.Methods and Experimental Design Insights
The study employed a multi-layered experimental approach to dissect the role of WIP1 in renal pyroptosis:- In vivo sepsis model: Acute kidney injury was induced in mice using lipopolysaccharide (LPS) injection. The WIP1 inhibitor CCT007093 was administered to a subset of animals to assess its effect on injury progression.
- In vitro cell model: Human kidney 2 (HK2) cells were exposed to LPS, with or without CCT007093 treatment, to evaluate changes in pyroptosis markers and cell viability.
- Gene and protein expression analysis: Single-cell RNA sequencing (scRNA-seq) tracked Ppm1d (WIP1) mRNA dynamics following unilateral ischemia–reperfusion injury in mice. Western blot and immunohistochemistry were used to quantify WIP1, NLRP3, cleaved-Caspase1, GSDMD-N, and IL-1β protein levels in both tissue and cell samples.
- Functional assays: Cell viability was measured using CCK-8, while pyroptosis was assessed by detecting the cleaved forms of key effectors.
- Phosphorylation status: The activation state of p38 MAPK was determined by immunoblotting for phosphorylated p38 in response to LPS and WIP1 inhibition.
Protocol Parameters
- LPS induction of AKI: Mice received intraperitoneal LPS at doses sufficient to elicit acute kidney injury, typically 10 mg/kg, with evaluation 24–48 hours post-injection.
- WIP1 inhibition: CCT007093 was administered at 5 mg/kg in vivo or at 10 μM in vitro, starting concurrently with LPS exposure.
- scRNA-seq time points: Renal tissue collected at multiple intervals post-ischemia–reperfusion injury, with peak Ppm1d expression observed on day 2 in proximal tubular cells.
- Pyroptosis marker assessment: Cleaved-Caspase1, GSDMD-N, and IL-1β quantified via western blot and immunostaining in both animal and cell models.
- MAPK pathway analysis: Phospho-p38 levels measured following LPS and/or WIP1 inhibitor treatment to map signaling dynamics.
Core Findings and Why They Matter
The principal findings of the study can be summarized as follows:- WIP1 upregulation in injury: Both human patients with acute tubular injury and mouse models of LPS-induced AKI exhibited significant increases in WIP1 expression within the renal tubules.
- WIP1 suppresses pyroptosis: Inhibition of WIP1 activity (via CCT007093) led to higher levels of NLRP3, cleaved-Caspase1, GSDMD-N, and IL-1β in LPS-injured HK2 cells and mouse kidney tissue, indicating enhanced pyroptosis and inflammatory signaling.
- p38 MAPK as a critical node: WIP1 inhibition augmented LPS-induced phosphorylation of p38 MAPK, which acted upstream to promote inflammasome activation and pyroptotic cell death.