Unveiling the role of PD-L1 in vascular endothelial dysfunction: Insights into the mtros/NLRP3/caspase-1 mediated pyroptotic pathway

Tianzhu Tao; Ying Zhu; Yue Shi; Bingke Sun; Yi Gu; Shumin Xu

doi:10.1016/j.yexcr.2024.114047

Unveiling the role of PD-L1 in vascular endothelial dysfunction: Insights into the mtros/NLRP3/caspase-1 mediated pyroptotic pathway

Exp Cell Res. 2024 Apr 16;438(1):114047. doi: 10.1016/j.yexcr.2024.114047. Online ahead of print.

Authors

Tianzhu Tao¹, Ying Zhu², Yue Shi¹, Bingke Sun³, Yi Gu³, Shumin Xu⁴

Affiliations

¹ Department of Anesthesiology, Air Force Medical Center, Beijing, China.
² Department of Pulmonary and Critical Care Medicine, 7th Medical Center of Chinese PLA General Hospital, Beijing, 100700, China; College of Pulmonary and Critical Care Medicine, 8th Medical Center of Chinese PLA General Hospital, Beijing, 100091, China.
³ Department of Emergency Medicine and Critical Care, Shanghai East Hospital, Tongji University School of Medicine, Shanghai, China.
⁴ Department of Emergency Medicine and Critical Care, Shanghai East Hospital, Tongji University School of Medicine, Shanghai, China. Electronic address: xxssmm9511028@163.com.

PMID: 38631546
DOI: 10.1016/j.yexcr.2024.114047

Abstract

Background: Programmed death ligand-1(PD-L1) has been postulated to play a crucial role in the regulation of barrier functions of the vascular endothelium, yet how this novel molecule mediates dysfunction in endothelial cells (ECs) during acute lung injury (ALI) remains largely unknown.

Methods: PD-L1 siRNA and plasmids were synthesized and applied respectively to down- or up-regulate PD-L1 expression in human lung microvascular endothelial cells (HMVECs). RNA sequencing was used to explore the differentially expressed genes following PD-L1 overexpression. The expression levels of tight junction proteins (ZO-1 and occludin) and the signaling pathways of NLRP-3/caspase-1/pyroptosis were analyzed. A mouse model of indirect ALI was established through hemorrhagic shock (HEM) followed by cecal ligation and puncture (CLP), enabling further investigation into the effects of intravenous delivery of PD-L1 siRNA.

Results: A total of 1502 differentially expressed genes were identified, comprising 532 down-regulated and 970 up-regulated genes in ECs exhibiting PD-L1overexpression. Enrichment of PD-L1-correlated genes were observed in the NOD-like receptor signaling pathway and the TNF signaling pathway. Western blot assays confirmed that PD-L1 overexpression elevated the expression of NLRP3, cleaved-caspase-1, ASC and GSDMD, and concurrently diminished the expression of ZO-1 and occludin. This overexpression also enhanced mitochondrial oxidative phosphorylation and mitochondrial reactive oxygen species (mtROS) production. Interestingly, mitigating mitochondrial dysfunction with mitoQ partially countered the adverse effects of PD-L1 on the functionality of ECs. Furthermore, intravenous administration of PD-L1 siRNA effectively inhibited the activation of the NLRP3 inflammasome and pyroptosis in pulmonary ECs, subsequently ameliorating lung injury in HEM/CLP mice.

Conclusion: PD-L1-mediated activation of the inflammasome contributes significantly to the disruption of tight junction and induction of pyroptosis in ECs, where oxidative stress associated with mitochondrial dysfunction serves as a pivotal mechanism underpinning these effects.

Keywords: Endothelial barrier; NLRP3 inflammasome; PD-L1; Pyroptosis; mtROS.