Vascular smooth muscle-specific NLRP3 hyperactivation exacerbates arterial intimal hyperplasia in mice

Intimal hyperplasia is a major contributor to restenosis after vascular interventions and to atherosclerotic lesion progression, involving vascular smooth muscle cell (VSMC) inflammatory activation, phenotypic switching, and maladaptive remodeling. Although NOD-like receptor pyrin domain 3 (NLRP3)-associated inflammatory signaling has been linked to vascular diseases, in vivo evidence defining how VSMC-intrinsic NLRP3 hyperactivation contributes to VSMC dysfunction and intimal hyperplasia remains limited. Here, we generated a VSMC-specific Nlrp3 gain-of-function (GOF) knock-in (KI) mouse model (Nlrp3 ^{L351P/+/Myh11-Cre}, "Nlrp3^SMKI") and subjected it to carotid partial ligation under hypercholesterolemic conditions. VSMC Nlrp3 GOF was associated with increased caspase1 activation-associated signaling in vivo, including in unligated arteries, and further enhanced ligation-triggered caspase1 activation. Nlrp3^SMKI arteries exhibited heightened vascular inflammation, including VCAM1 upregulation and increased macrophage-associated accumulation, together with enhanced Gasdermin D (GSDMD)/GSDMD N-terminal-associated signaling and increased TUNEL-positive cell death. These changes were accompanied by significantly exacerbated neointimal lesion growth, as reflected by increased intimal area and intima-to-media ratio. VSMC Nlrp3 GOF was also associated with enhanced vascular injury-induced lipid accumulation and foam cell-like remodeling in the injured arterial wall, including α-SMA-positive VSMC-containing regions. These pathological responses were accompanied by reduced expression of the transcription factor EB (TFEB) and altered expression of lysosome-autophagy-related markers, suggesting an association between VSMC NLRP3 hyperactivation and disrupted cellular stress-adaptive pathways during vascular remodeling. Collectively, these data provide in vivo evidence that VSMC-specific Nlrp3 GOF exacerbates vascular injury-induced intimal hyperplasia and is accompanied by heightened vascular inflammation, GSDMD-associated cell injury signaling, lipid accumulation, foam cell-like remodeling, reduced TFEB expression, and altered lysosome-autophagy-related marker expression. These findings suggest that targeting VSMC NLRP3-associated inflammatory signaling may represent a potential therapeutic strategy for limiting restenosis and plaque progression.