[Core targets and immune regulatory mechanisms of Huoluo Xiaoling Pellet for promoting zebrafish fin regeneration].

Objectives: To investigate the core targets and immunomodulatory mechanisms of Huoluo Xiaoling Pellet (HLXLP) for promoting tissue repair.

Methods: Network pharmacology and protein-protein interaction network were used to screen active components in HLXLP, the disease-related targets and the core targets, followed by GO and KEGG enrichment analyses and molecular docking to predict the pharmacological mechanisms. The toxicity of HLXLP was evaluated in zebrafish, and in a tissue regeneration model established in 3 dpf zebrafish larvae by amputating 95% of the tail fin, the effects of a formulated zebrafish embryo culture medium and 10, 20, and 40 μg/mL of aqueous extract of HLXLP on tissue regeneration was evaluated; RT-qPCR was performed to detect mRNA expressions of tissue regeneration marker genes and the core target genes. Transgenic zebrafish with fluorescently labeled macrophages and neutrophils were used to observe immune cell migration during tissue regeneration, and macrophage polarization at different stages was assessed with RT-qPCR.

Results: We identified a total of 149 intersected targets between HLXLP active components and tissue repair and 5 core targets (AKT1, IL-6, TNF-α, EGFR and STAT3). GO and KEGG analyses suggested that the effects of HLXLP were mediated primarily through the JAK-STAT pathway, adhesion junctions and positive regulation of cell migration. HLXLP was minimally toxic below 40 μg/mL and lethal at 320 μg/mL in zebrafish, and caused renal and pericardial edema and vascular defects above 80 μg/mL. In zebrafish with tail fin amputation, HLXLP significantly promoted tissue regeneration, reduced IL-6 and TNF-α and enhanced AKT1, EGFR and STAT3 mRNA expressions, modulated neutrophil and macrophage recruitment to the injury sites, and regulated M1/M2 macrophage polarization during tissue regeneration.

Conclusions: HLXLP promotes zebrafish tail fin regeneration through multiple active components, targets and pathways for immunomodulation of immune cell migration and macrophage polarization to suppress inflammation and accelerate healing.