AGPAT2 Inflammatory Metabolic Reprogramming Mediates Immune Checkpoint Inhibitor-associated Myocarditis via LPAR5-pyroptosis Axis
Objectives: Immune checkpoint inhibitors (ICIs), especially programmed cell death protein-1 (PD1) inhibitors, are effective onco-therapeutic agents. However, ICI-associated myocarditis (ICIAM) greatly limits their clinical utility. Imbalance between 1-acylglycerol-3-phosphate O-acyltransferases (AGPAT2) and lysophosphatidic acid (LPA) induced by inflammatory metabolic reprogramming (IMRP) might cause cardiovascular injury. This study aims to explore the link between AGPAT2 pathway and ICIAM as well as identifies diagnosis and treatment targets of ICIAM. Methods: ICIAM model was established by injecting anti-PD1 (PD1) in wild-type (WT) and AGPAT2 heterozygous knockout (AGPAT2+/-) mice. The pathogenic and regulating mechanisms of AGPAT2-LPA and its downstream signaling were examined in vitro and in vivo. A tumor-patient cohort was enrolled to observe the association between serum LPA and risk of ICIAM. Results: In the PD1-induced ICIAM model, myocardial IMRP occurred due to upstream immunity disorder, leading to downstream AGPAT2 degradation via lysosomal pathway and subsequent LPA accumulation. Knockout of AGPAT2 gene also promoted LPA accumulation. The accumulated LPA, by binding to its dominant receptor subtype 5 (LPAR5), triggered pyroptotic myocardial damage and resultant ICIAM. LPAR5 knockdown with siRNA or inhibition with TCLPA5-4 played the most significant rescue effect on myocardial pyroptosis, while stimulating LPAR5 with overdose LPA significantly increased myocardial pyroptosis. In ICI-treated patients, elevated serum LPA was associated with increased risk of ICIAM. Conclusions: IMRP-triggered dysfunction of AGPAT2-LPA-LPAR5-pyroptosis axis is involved in pathogenesis of ICIAM. Several elements in this axis may be the promising targets in diagnosis (LPA as a biomarker) and treatment (LPA or LPAR5 as therapeutics) of ICIAM.