Inhibition of calcineurin as a strategy for biofilm control: <i>Trichosporon</i> spp. as a case study

Among the opportunistic species related to Invasive Fungal Infections (IFIs), <i>Trichosporon</i> spp. are particularly noteworthy, being responsible for infections with high mortality rates in patients with hematological cancers. <i>Trichosporon</i> spp. are intrinsically resistant to echinocandins and their biofilms are tolerant to polyenes and triazoles. This study investigated the effect of calcineurin inhibition on the development and antifungal tolerance of <i>Trichosporon</i> biofilms. Mature biofilms of <i>T. inkin</i> and <i>T. asahii</i> were treated with Ciclosporin A (CsA) and analyzed for biomass reduction and viability, ultrastructure, and tolerance tolerance to antifungals. Molecular docking studies were performed to understand the attachment of CsA to the calcineurin of <i>T. asahii</i>. CsA was able to significantly reduce both the biomass and metabolic activity of biofilms. Mature biofilms formed in the presence of CsA showed greater susceptibility to antifungals, compared to biofilm growth control. CsA caused structural changes in biofilms. Molecular modeling suggested that CsA can block the active site of the calcineurin A subunit of <i>T. asahii</i>. Calcineurin inhibition seems to be a promising strategy for controlling antifungal-resistant fungal biofilms.