Sialidase 1 fúngica: Um novo alvo terapêutico para infeções por Sporothrix brasiliensis

Sporotrichosis caused by S. brasiliensis has a global impact and it is no longer specifically a Brazilian problem being spread over 3 continents, including Europe [3,17,18]. One important step to S. brasiliensis sporotrichosis control is its correct treatment, and being a zoonotic infection, a One Health approach should be developed [19,20]. Current therapeutic strategies based on antifungal therapy against S. brasiliensis have shown limited effectiveness, prompting the development of novel treatment options [3]. Our lab has been studying the cellular and molecular events that regulate fungal pathogenesis [5–8]. Through dual RNA sequencing analysis, we identified sialidase-1 (SbSia1) as a crucial virulence factor specifically upregulated in S. brasiliensis during infection (Fig 1). Sialidases play a role in nutritional purposes, biofilm formation, and modulation of immune function [21], demonstrating their importance in virulence. Therefore, S. brasiliensis UP-REGULATES SIALIDASE-1 DURING INFECTION, WHICH BY REMOVING SIALIC ACID FROM EXTRACELLULAR GLYCANS (FUNGI AND HOST CELLS) triggers a hyperinflammatory response (Fig 1) [22,23]. The current project aims to build upon this knowledge by identifying a novel drug specifically targeting SbSia1. Our findings boosted support for a DUAL THERAPY REGIMENS combining ITRACONAZOLE AND SIALIDASE INHIBITORS to reduce inflammation and INCREASE TREATMENT EFFICACY OF SPOROTRICHOSIS BY S. brasiliensis. The significance of our project lies in identifying potent SbSia1 inhibitors through innovative drug discovery methods (Fig 3). Therefore, the main objectives of this proposal are: 1 - TO UNCOVER THE 3D STRUCTURE OF SIALIDASE-1 FROM S. brasiliensis. We will obtain the predicted 3D structure of SbSia1 using advanced tools like AlphaFold and I-TASSER, followed by refinement on the GalaxyRefine server and experimental high throughput screening. This data will allow us to perform molecular docking simulations to identify potential inhibitors of SbSia1 on virtual screening approaches that have reduced inhibitory potential in the host sialidase (Neu1), where an X-ray crystallography structure is available. 2 – TO IDENTIFY COMPOUNDS THAT HAVE HIGH POTENCY AND SELECTIVE INDEX AGAINST SbSia1. Potentially SbSia1 inhibitory compounds will be synthesized (based on structural modifications of oseltamivir) or purchased (when commercially available) and their specific effect on SbSia1 will be determined. A specific approach was designed to exclude compounds that also have inhibitor effect on host sialidase (Neu1) as well as those compounds with toxic targets in human cells. Ten compounds will be selected for dual therapy in experimental model of sporotrichosis by S. brasiliensis. 3 – TO UNCOVER THE BEST SbSia1 INHIBITOR FOR DUAL THERAPY WITH ITRACONAZOLE FOR IN VIVO TREATMENT OF S. brasiliensis SPOROTRICHOSIS. Through molecular synthesis and experimental validation, the proposed task flow can pave the way for the development of more effective SbSia1 inhibitors, offering improved therapeutic options for the treatment of fungal infections caused by S. brasiliensis. Specifically, by testing the best target compounds in S. brasiliensis infection models, in vitro (macrophage studies) and in vivo (mouse model of infection), will allow to identify those that have best results in the treatment of the diseases upon a dual therapy with itraconazole.