NLRP3: a key regulator of skin wound healing and macrophage-fibroblast interactions in mice

Wound healing is a highly coordinated process driven by intricate molecular signaling and dynamic interactions between diverse cell types. Nod-like receptor pyrin domain-containing protein 3 (NLRP3) has been implicated in the regulation of inflammation and tissue repair; however, its specific role in skin wound healing remains unclear. This study highlights the pivotal role of NLRP3 in effective skin wound healing, as demonstrated by delayed wound closure and altered cellular and molecular responses in NLRP3-deficient (NLRP3^-/-) mice. Histological analysis revealed impaired healing processes, accompanied by reduced expression of key inflammatory mediators, including interleukin-6 (IL-6), tumor necrosis factor-α (TNF-α), and prostaglandin E₂ (PGE₂). Deficiencies in apoptosis were evident through altered expression of cysteine-aspartic acid protease 3 (Caspase-3), P53, and B-cell lymphoma-2 (Bcl-2). Furthermore, critical growth factors such as vascular endothelial growth factor (VEGF), epidermal growth factor (EGF), and matrix metalloproteinase-9 (MMP-9) were significantly decreased at the excisional skin wound sites. Furthermore, using co-culture systems, we found that NLRP3 mediated the interaction between macrophages and myofibroblasts. Wild-type fibroblast-conditioned media (MFbCM) enhanced nitric oxide (NO), IL-6, and tumor necrosis factor-α (TNF-α) production in M1 macrophages and arginase activity, chitinase 3-like protein 1 (Ym1), and IL-10 expression in M2 macrophages, effects significantly diminished with NLRP3^-/- MFbCM. Similarly, conditioned media from wild-type M1 or M2 macrophages promoted the expression of FGF-2, VEGF, and MMP-2 expression in myofibroblasts, which was attenuated when using NLRP3^-/- macrophage-conditioned media. PGE₂ levels were reduced in both NLRP3^-/- macrophages and myofibroblasts. Supplementing NLRP3^-/- conditioned media with PGE₂ partially restored the impaired functions, suggesting that PGE₂ acts as a downstream mediator of NLRP3-regulated macrophage-myofibroblast interactions. These findings indicate that NLRP3 is a key regulator of skin wound healing, facilitating macrophage-myofibroblast communication.