The NLRP3/IL-6/EGR2/CSF-1 Axis Regulates Macrophage Differentiation and Inflammatory Resolution in Infection-Associated Wound Healing

Chronic Pseudomonas aeruginosa (P. aeruginosa) infection impairs wound healing, yet the underlying inflammatory mechanisms remain poorly understood. This study investigates how the NLRP3 inflammasome orchestrates macrophage differentiation and inflammatory resolution during infection-associated wound healing. A murine P. aeruginosa wound infection model was established. Macrophage polarization dynamics were assessed by flow cytometry (CD11b/F4/80/Arg1/iNOS/CD206/CD86) and histology. Wound healing outcomes were compared between wild-type and NLRP3-/- mice via closure kinetics, ECM analysis (Masson's trichrome/picrosirius red), and transcriptomic profiling. Mechanistic studies employed CRISPR-edited and pharmacologically modulated (MCC950/nigericin) THP-1/U937 cells, along with ChIP-qPCR, luciferase assays, and genetic rescue experiments. P. aeruginosa-infected wounds exhibited delayed healing, reduced ECM deposition, increased cellular senescence, and impaired fibroblast activation, with M1-dominant macrophage polarization and elevated NLRP3, ASC, caspase-1, IL-6, and IL-18. NLRP3-/- mice showed further delayed healing, decreased collagen I/III, reduced macrophage recruitment, and suppressed M1-to-M2 transition. Transcriptomics revealed downregulated Tlr4, Cd74, Egr2, and IL-6/JAK/STAT3 pathways. NLRP3 knockout impaired monocyte-to-macrophage differentiation (reduced CD14⁺ cells and adhesion), while NLRP3 overexpression enhanced it. EGR2 expression correlated with NLRP3 levels; EGR2 knockdown suppressed CSF-1/CSF1R and macrophage differentiation, whereas EGR2 overexpression rescued defects caused by NLRP3 knockout. Mechanistically, IL-6 promoted EGR2 nuclear translocation, and EGR2 directly bound the CSF-1 promoter to regulate its expression. The NLRP3 inflammasome drives macrophage differentiation and M1 polarization via the IL-6/EGR2/CSF-1 axis in infection-associated wound healing. Targeting this axis may represent a therapeutic strategy to modulate inflammatory responses and improve healing in infected wounds.