Role of Raf Kinase Inhibitor Protein in Modulating Echinococcal Cyst Fluid-induced Degranulation in Bone Marrow-Derived Mast Cells.

Objective: This study aimed to investigate the role of Raf kinase inhibitor protein (RKIP) in degranulation induced by echinococcal cyst fluid (EgCF) in bone marrow-derived mast cells (BMMCs).

Methods: Primary BMMCs were isolated and cultured from the femurs and tibias of RKIP gene knockout (KO) and wild-type (WT) C57BL/6 mice. EgCF-induced degranulation models were established for both groups. Samples of cells and supernatant were collected for analysis. Surface expression levels of CD117 and Fc-epsilon Receptor Ⅰ α (FcεRIα) were assessed. Supernatant concentrations of β-hexosaminidase, IL-4, IL-6, and tumor necrosis factor (TNF-α) were measured. Cellular mRNA levels of IL-4, IL-6, and TNF-α were quantified, and changes in RKIP protein expression during degranulation in WT BMMCs were monitored.

Results: After 4 weeks of induction culture, the double-positive rates for CD117 and FcεRIα exceeded 98% in both KO and WT BMMCs. Following sensitization, BMMCs from the KO group demonstrated significantly higher degranulation rates compared to the WT group (p < 0.05). In WT BMMCs, surface RKIP protein expression progressively decreased at 1 hour, 2 hours, and 3 hours post-sensitization, corresponding with degranulation progression (p < 0.05). The KO group exhibited elevated release of BMMC-related cytokines, including IL-4, IL-6, and TNF-α, compared to the WT group after sensitization (p < 0.05). Similarly, transcription levels of cytokines IL-4, IL-6, and TNF-α were higher in the KO group than in the WT group following sensitization (p < 0.05).

Conclusion: RKIP gene knockout resulted in an increased EgCF-induced release of cytokines and bioactive substances by BMMCs, indicating that RKIP may suppress EgCF-induced BMMC degranulation. These findings suggest that RKIP could serve as a potential therapeutic target for managing allergic reactions associated with cystic echinococcosis.