Polystyrene nanoparticles reduce the Cryptococcus neoformans virulence via induction of mitochondrial dysfunction

Dongnan Zheng¹Yifan Zhou¹Bin Xu²Wenxia Bu¹Fengxu Wang¹Xinyuan Zhao^1*Peng Xue^1*Yuanyuan Ma^1*

• ¹Nantong University, Nantong, China
• ²The Second Affiliated Hospital of Nanchang Medical College, Nanchang, China

Introduction: Cryptococcus neoformans is a fungus that poses a significant threat to human health, with its polysaccharide capsule being a key virulence factor that can upregulate the expression of host gene ARG1, encoding arginase-1, which suppresses T-cell-mediated antifungal immune responses. Nanoplastics may cause oxidative and mitochondrial stress in mammalian cells, potentially impacting fungal physiology and pathogenic mechanisms as well. Methods: We utilized mouse models and fungal burden assays to investigate the effects of polystyrene nanoparticles (PS-NPs) on C. neoformans infection. Mice were subjected to oropharyngeal aspiration of 50 μl of 80 nm PS-NPs at a concentration of 5 μg/μl, administered three times a week over a specified duration. To assess the impact of PS-NPs on C. neoformans mitochondria, we measured intracellular reactive oxygen species (ROS) levels, mitochondrial superoxide, mitochondrial membrane potential, and intracellular ATP levels in whole fungal cells. Additionally, we performed RNA-Seq analysis and metabolomics studies to evaluate the effects of PS-NPs at a concentration of 0.3 μg/μL on the RNA and metabolic profiles of C. neoformans mitochondria. Results: Our study demonstrated that PS-NPs significantly prolonged the survival of mice infected with C. neoformans (P = 0.0058). PS-NPs exposure resulted in a 30% reduction in ARG1 mRNA expression and enhanced T-cell-mediated antifungal immunity. Additionally, PS-NPs inhibited fungal capsule formation by approximately 40% in infected mice and 70% in capsule induction medium. Given the close link between the mitochondria of C. neoformans and capsule formation, we further investigated the effects of PS-NPs on mitochondrial function. Exposure to PS-NPs led to mitochondrial dysfunction in C. neoformans, as evidenced by a threefold increase in ROS, a 1.7-fold increase in mitochondrial membrane potential, and disruptions in mitochondrial transcription and metabolism. Conclusion: These results suggest that PS-NPs inhibit the formation of the C. neoformans capsule, potentially by inducing mitochondrial dysfunction. Furthermore, the findings highlight the broader implications of PS-NPs on fungal virulence and the dynamics of host-pathogen interactions, underscoring their significance in advancing our understanding of these complex relationships.