Role of paracoccin on Paracoccidioides brasiliensis virulence and susceptibility to antifungal drugs in the Galleria mellonella larvae model

Abstract

Paracoccin (PCN), a Paracoccidioides brasiliensis glycoprotein, has been reported to play roles in fungal biology and paracoccidioidomycosis pathogenesis. Lectin and chitinase domains account for the PCN’s dual roles as an immunomodulatory agent and virulence factor. Soluble PCN injected in P. brasiliensis infected mice, by interacting with TLRs’ N-glycans, drives the host immune response toward a protective Th1 axis. Otherwise, mice infection with yeasts overexpressing PCN (ov-PCN) revealed that PCN acts as a fungal virulence factor, thanks to its chitinase activity on the cell wall, resulting in resistance to phagocytes’ fungicidal activity and development of severe paracoccidioidomycosis. Because antifungal drug administration follows the disease diagnosis, we studied the PCN effect on yeast resistance or susceptibility to antifungal agents. Using a paracoccidioidomycosis model developed in Galleria mellonella larvae, we confirmed the observation, in the murine host, that ov-PCN yeasts display maximum virulence compared to wild-type (wt-PCN) or PCN-silenced (kd-PCN) yeasts. PCN overexpression accounted for the highest susceptibility of P. brasiliensis to antifungal and reduced relative mRNA expression of genes encoding proteins related to cell wall remodeling. The lowest virulence, detected in infection with kd-PCN yeasts, correlated with the lowest susceptibility to antifungals and impact on genes for cell wall remodeling. So, we defined that the grade of endogenous PCN production influences the P. brasiliensis virulence and susceptibility to antifungal drugs, as well as the expression of genes related to cell wall remodeling. We postulate that this variable gene expression is mechanistically associated with P. brasiliensis virulence changes.

Própolis Vermelha E Ação Antifúngica: Potencialidades E Desafios

“…À vista disso, os únicos autores que não investigaram sobre tal microrganismo foram Santos et al (2021), que preferiram testar a atividade fungicida da própolis vermelha contra Paracoccidioides brasiliensis. Sobre este segundo fungo, sabe-se que possui elevada resistência (PITANGUI et al, 2023) e, em especial, é encontrado no Brasil, onde tem emergido como uma ameaça (PEÇANHA et al, 2022), o que indica a importância de se estabelecer novos métodos terapêuticos que sejam mais eficientes contra esse microrganismo, a exemplo do uso da própolis vermelha, que poderia ser testada isolada ou em sinergia com outros antifúngicos conhecidos contra esse fungo (HAHN et al, 2023).…”

Galleria mellonella as a Model for the Study of Fungal Pathogens: Advantages and Disadvantages

“…G. mellonella has been used to study many fungi, including Aspergillus spp., Candida spp., Cryptococcus spp., Conidiobolus coronatus , Histoplasma capsulatum , Madurella mycetomatis , Malassezia spp. and Paraccocidioides brasiliensis [ 59 , 60 , 61 , 62 , 63 , 64 , 65 , 66 , 67 , 68 , 69 , 70 , 71 , 72 , 73 , 74 , 75 , 76 , 77 , 78 , 79 , 80 , 81 , 82 , 83 , 84 , 85 , 86 , 87 , 88 , 89 , 90 , 91 , 92 , 93 , 94 , 95 , 96 , 97 , 98 , 99 , 100 , 101 , 102 , 103 , 104 , 105 , 106 , 107 ].…”

“…Categorising studies using G. mellonella larvae to assess virulence or drug efficacy is a challenging task. It is more appropriate to evaluate the work based on different fungal genera since some species have undergone extensive research in recent years [ 59 , 60 , 61 , 62 , 63 , 64 , 65 , 66 , 67 , 68 , 69 , 70 , 71 , 72 , 73 , 74 , 75 , 76 , 77 , 78 , 79 , 80 , 81 , 82 , 83 , 84 , 85 , 86 , 87 , 88 , 89 , 90 , 91 , 92 , 93 , 94 , 95 , 96 , 97 , 98 , 99 , 100 , 101 , 102 , 103 , 104 , 105 , 106 , 107 ].…”

“…G. mellonella is a suitable model for studying the virulence mechanisms of Paracoccidioides brasiliensis due to its advantage of faster isolation of fungi (4 days) as compared to mice (30 days) [ 97 ]. G. mellonella larvae were also used to study the role of a lectin from P. brasiliensies and its role in virulence, showing that the fungus is less virulent in the absence of this lectin [ 98 ]. It has been tested on G. mellonella , a peptide with an affinity for the PbDrk1 protein of P. brasiliensis , which probably plays a crucial role in morphology and virulence.…”