Porcine coronavirus promotes NLRP3 inflammasome activation during virus-induced neuroinflammation
Qianyu Zhou, Junchao Shi, Ruizhao Qiu, Rui Dai, Yungang Lan, Jiyong Zhou, Xuming Deng, Wenqi He, Zi LiABSTRACT
Neurotropic coronaviruses can invade the central nervous system (CNS) and cause severe neurological disease, but the mechanisms underlying virus-induced neuroinflammation remain incompletely understood. Here, we report that infection with porcine hemagglutinating encephalomyelitis virus (PHEV), a neurotropic betacoronavirus, is associated with mitochondrial dysfunction, including increased reactive oxygen species (ROS) production and loss of the mitochondrial membrane potential (ΔΨm). Our data identify the NOD-like receptor family pyrin domain-containing 3 (NLRP3) inflammasome as an important component connecting PHEV infection, mitochondrial stress, and PANoptosis. The viral nucleocapsid (N) protein interacted with the pyrin domain (PYD) of NLRP3 through its C-terminal region and facilitated inflammasome assembly without detectably disrupting the NLRP3-NIMA-related kinase 7 (NEK7) interaction. Pharmacological inhibition of NLRP3 or caspase-1, as well as genetic knockout of NLRP3, significantly reduced viral load, attenuated neuroinflammation, and delayed disease progression in PHEV-infected mice. Moreover, NLRP3 deficiency shifted the cell-death modality from PANoptosis to necroptosis, thereby mitigating CNS immunopathology. Together, these findings demonstrate that PHEV hijacks the NLRP3-mitochondrial axis to exacerbate neuroinflammatory injury and support further evaluation of inflammasome- and PANoptosis-related pathways as therapeutic targets for neurotropic coronavirus infections.
IMPORTANCE
Porcine hemagglutinating encephalomyelitis virus (PHEV) is a neurotropic betacoronavirus that primarily invades the central nervous system (CNS) and induces fatal encephalomyelitis in young piglets. However, the host and viral determinants that contribute to PHEV-induced brain injury remain incompletely defined. In this paper, we show that PHEV infection activates the host NOD-like receptor family pyrin domain-containing 3 (NLRP3) inflammatory pathway and that this response contributes to CNS immunopathology. Loss of NLRP3 shifts the infection-associated cell death program from PANoptosis to necroptosis. Blocking this pathway reduces viral load, attenuates neuroinflammation, and improves survival in infected mice. These findings expand our understanding of host responses to neuroinvasive coronaviruses and highlight inflammasome signaling as a candidate therapeutic target for controlling coronavirus-associated encephalitis in swine.