Suppression of Hsp90 expression in Aspergillus fumigatus enhances sensitivity to oxidative stress and activates host cell NF-κB p65 and ERK signaling pathways

ABSTRACT This study investigates the pivotal role of the molecular chaperone Hsp90 in the growth, development, and immune modulation of the opportunistic pathogen Aspergillus fumigatus . Using a Tet-on system-based conditional expression strain, Tet-hsp90 , we demonstrate that Hsp90 is essential for the growth and viability of A. fumigatus . In strains with suppressed Hsp90 expression, we observe a significant reduction in antioxidant capacity, an increase in intracellular reactive oxygen species levels, and a marked decrease in the activity of key antioxidant enzymes, such as superoxide dismutase and catalase, highlighting Hsp90’s critical role in regulating oxidative stress tolerance. Furthermore, the absence of Hsp90 leads to disruptions in metal ion metabolism, including copper, iron, and manganese, which further compromises the fungal cell’s ability to manage oxidative stress. Immune response analysis revealed that after Hsp90 inhibition, spores significantly increased the expression of pro-inflammatory cytokines, such as interleukin-1β (IL-1β), IL-6, and tumor necrosis factor alpha, in host cells. Further research showed that, upon Hsp90 inhibition, spores enhanced the phosphorylation of NF-κB p65 and ERK proteins, thereby activating these key signaling pathways to upregulate immune responses. In conclusion, this study underscores the multifaceted regulatory roles of Hsp90 in oxidative stress resistance, metal ion homeostasis, and immune system activation, providing valuable insights for the development of novel antifungal therapeutic strategies targeting Hsp90. IMPORTANCE The significance of this study lies in its focused and in-depth analysis of the critical roles of the molecular chaperone Hsp90 in oxidative stress tolerance, metal ion homeostasis, and immune response regulation in Aspergillus fumigatus . Utilizing the Tet-on system to precisely modulate Hsp90 expression, this research demonstrates that Hsp90 is essential for the growth, development, and pathogenicity of this major opportunistic pathogen. Specifically, the study highlights Hsp90's crucial role in sustaining antioxidant enzyme activity, maintaining metal ion balance, and regulating immune responses—key factors that enable the fungus to survive and infect the host. These findings provide novel insights into the molecular mechanisms that underlie A. fumigatus 's resistance to oxidative stress and its evasion of host immunity, positioning Hsp90 as a promising therapeutic target for treating fungal infections. Furthermore, the results open new avenues for future investigations into the role of Hsp90 in fungal pathogenesis and immune modulation, potentially guiding the development of targeted antifungal therapies.