Molecular adaptation and clinical progression of Cryptococcus neoformans infection from the lungs to systemic...

Cryptococcus neoformans is a prime example of accidental virulence, repurposing environmental survival strategies to persist within the hostile milieu of the human host. This review synthesizes recent advances in systems biology and infection modeling to chart the pathogen's dissemination from the lungs to distal organs along the anatomic route of infection. Upon inhalation, mammalian temperature and elevated CO₂ act as host-entry signals that engage the thermotolerance and stress-response circuitry required for survival at 37°C. In the lung, capsule expansion, melanization, and trehalose-supported proteostasis underpin survival within alveolar macrophages and the establishment of latency. Morphotype diversification - including lung-predominant titan cells and the smaller 'seed' cells optimized for hematogenous spread - shapes this host encounter. During hematogenous transit, fungal cells must contend with alkaline pH and phosphate limitation, integrated through Pho4, alongside iron-mediated nutritional immunity that intersects with mitochondrial redox state, before facing Kupffer-cell-mediated hepatic filtration. At the blood-brain barrier, inositol metabolism together with hyaluronic acid, Plb1, Mpr1, and urease drives invasion, after which adaptation to copper limitation and microglial pressure governs central nervous system persistence. Beyond neuroinvasion, we highlight persistence in less frequent infection reservoirs such as the kidney and prostate, where the fungus encounters distinctchallenges, including osmotic stress and fluctuating metal availability. Finally, we outline open questions ranging from cryptococcal cytolytic effectors and vaccine development to next-generation induction therapy, and propose that large-scale gene deletion resources will be central to identifying organ-specific virulence determinants. This overview identifies the pathogen's vulnerabilities to inform the development of new treatments.