Pulsatilla decoction inhibits Candida albicans proliferation and adhesion in a mouse model of vulvovaginal candidiasis via the Dectin-1 signaling pathway

Ethnopharmacological relevance: Pulsatilla decoction (PD) is a classical prescription in Traditional Chinese Medicine (TCM) and has been reported to have inhibitory effects on Candida albicans proliferation. Study aim: To investigate the therapeutic effects of PD in the treatment of Vulvovaginal candidiasis (VVC) and elucidate the potential mechanism. Materials and methods: Female BALB/c mice (N = 90) were randomized to six treatment groups, including the Control group, Model group, three PD groups and Fluconazole group which served as a positive control (20 mg/kg weekly). The three PD groups (low dose group, medium dose group and high dose group) were given a daily intragastric gavage of PD at doses of 5, 10 and 20 g/kg, respectively. Five animals from each group were euthanized on Day 4, Day 7 and Day 14 after treatment. Colony forming unit (CFU) was measured by the serial dilution method. The degree of infection was assessed by Gram staining, Periodic acid schiff (PAS) staining, Hematoxylin and eosin (H&E) staining and Scanning electron microscopy (SEM). The serum inflammation levels were determined by a Luminex assay. Gene and protein expression levels of components of the Dectin-1 signaling pathway were determined by Real-time PCR, Western-blot and immunohistochemistry, respectively. Results: The administration of PD significantly decreased the fungal load from Day 7 post-infection onwards and decreased the number of visible microorganisms based on findings from Gram staining, PAS staining and SEM. H &E staining indicated that the impaired histological profiles were improved in all three PD groups. PD led to a significantly lower level of IL-23 in the serum; the levels of IL-10 and TNF-alpha were also decreased, although the differences were not significant. Furthermore, a substantial downregulation of Dectin-1, CARD9 and NF-eB mRNA levels and Dectin-1, Syk, CARD9 and NF-KB protein levels was observed after the administration of PD. Conclusion: This study suggests that PD exerts inhibitory effects on C. albicans proliferation, adhesion and inflammation and simultaneously downregulates the expression levels of important genes and proteins associated with the Dectin-1 pathway, highlighting the potential application of PD to improve the clinical management of VVC.