Trehalose-6-phosphate synthase-deletion in Cryptococcus neoformans elicits rapid innate fungal clearance from the lungs with early neutrophil accumulation

Abstract

Abstract Clearance of the invasive fungus Cryptococcus neoformans (Cn) infection requires T-cell immune responses and individuals with impaired adaptive immunity are highly vulnerable to Cn infection. The innate immune response thus may be the only functional arm against the expansion of pathogens in patients with severe T cell deficiencies. Accordingly, targeting pathways responsible for Cn-evasion of early innate defenses could rapidly resolve Cn-disease in immunocompromised patients. Trehalose-6-phosphate synthase (TPS1), a fungal enzyme for trehalose sugar synthesis absent in mammal, was recently identified as a key virulence gene. Using a mouse model of pulmonary Cn infection, we found that TPS1-deficient Cn (tps1Δ) elicits rapid clearance by the host. Within 72 hours, tps1Δ was either completely cleared or reduced by 5 orders of magnitude, while WT-Cn expanded in the lungs of infected mice. Mechanistically, we found that rapid tps1Δ clearance was associated with early neutrophils recruitment and induction of neutrophils - recruiting CXCL1 and CXCL2. Notably, this occurred without improved Cn-killing by macrophages. Tps1Δ stains were rapidly cleared from CD4+ T cell depleted mice that receive anti-CD4 antibody treatment, suggesting that Tps1Δ clearance is independent of host adaptive immunity. Furthermore, our in vitro killing assay showed that tps1Δ was more vulnerable to neutrophils killing compared to WT strain. Together, our data revealed that cnTPS1 contributes to early innate immune evasion by inhibiting neutrophil recruitment and killing. We identify TPS1-interception as an important therapeutic strategy to both compromise the microbe fitness and to enhance efficiency of the innate defenses in C.n elimination.