Jinping Zhang

Acinetobacter baumannii is a significant opportunistic pathogen causing severe nosocomial infections that poses increasing clinical challenges due to escal

Cryptococcus neoformans is an invasive fungus that causes both acute and chronic infections, especially in immunocompromised patients. Owing to the increase in the prevalence of drug-resistant pathogenic fungi and the limitations of current treatment strategies, drug repositioning has become a feasible strategy to accelerate the development of new drugs. In this study, the minimum inhibitory concentration of vitamin D₃ (VD₃) against C. neoformans was found to be 0.4 mg/mL by broth microdilution assay. The antifungal activities of VD₃ were further verified by solid dilution assays and “time-kill” curves. The results showed that VD₃ reduced fungal cell adhesion and hydrophobicity and inhibited biofilm formation at various developmental stages, as confirmed by crystal violet staining and the 2,3-bis(2-methoxy-4-nitro-5-sulfophenyl)-2H-tetrazolium-5-carboxanilide assay. Fluorescence staining of cellular components and a stress susceptibility assay indicated that VD₃ compromised cell integrity. Reverse transcription quantitative PCR demonstrated that VD₃ treatment upregulated the expression of fungal genes related to cell wall synthesis (i.e., CDA3, CHS3, FKS1, and AGS1). Moreover, VD₃ enhanced cell membrane permeability and caused the accumulation of intracellular reactive oxygen species. Finally, VD₃ significantly reduced the tissue fungal burden and prolonged the survival of Galleria mellonella larvae infected with C. neoformans. These results showed that VD₃ could exert significant antifungal activities both in vitro and in vivo, demonstrating its potential application in the treatment of cryptococcal infections.

Both the increasing environmental temperature in nature and the defensive body temperature response to pathogenic fungi during mammalian infection cause he