Palmitoylated COX-2Cys555 reprogrammed mitochondrial metabolism in pyroptotic inflammatory injury in patients with post-acute COVID-19 syndrome.

INTRODUCTION

The complex interplay between protein palmitoylation, mitochondrial dynamics, and inflammatory responses plays a pivotal role in respiratory diseases. One significant feature of post-acute coronavirus disease 2019 (COVID-19) syndrome (PACS) is the occurrence of a storm of inflammatory cytokines related to the NOD-like receptor protein 3 (NLRP3). However, the specific mechanisms via which palmitoylation affects mitochondrial function and its impact on the NLRP3 inflammasome under pathological respiratory conditions remain to be elucidated.

OBJECTIVE

This study aimed to investigate how protein palmitoylation influences inflammatory responses and mitochondrial dynamics in respiratory diseases, such as those induced by the SARS-CoV-2 spike S protein in PACS, thereby providing a therapeutic target for inflammatory lung injury.

METHODS

In vivo experiments were conducted using AdV5-pADM-CMV-COVID-19-S (AdV5-S) nasal drip-treated C57BL/6 mice to assess NLRP3 inflammasome activation and inflammatory response. In vitro experiments were performed using pCMV-S-transfected human lung epithelial BEAS-2B cells to analyze the effects of DHHC5-mediated palmitoylation of cyclooxygenase-2 (COX-2) at cysteine 555 (COX-2Cys555) on mitochondrial metabolism and NLRP3 inflammasome activation.

RESULTS

Palmitoylation of COX-2Cys555 enhanced its interaction with hexokinase 2 (HK2) to regulate mitochondrial metabolic reprogramming, leading to NLRP3 inflammasome activation and pyroptosis. Pharmacological and genetic suppression of palmitoylation diminished the mitochondrial localization of palmitoylated COX-2 and its interaction with HK2, thereby reducing mitochondrial metabolic reprogramming. Furthermore, genetic intervention targeting DHHC5 (shDhhc5) alleviated NLRP3 activation and pyroptosis, mitigating the chronic inflammatory damage associated with PACS.

CONCLUSION

This study highlights the regulatory role of COX-2Cys555 palmitoylation in mitochondrial metabolism and lung inflammatory injury, and suggests potential therapeutic targets to combat respiratory pathogenesis linked to palmitoylated COX-2.