Abstract
Conidia are the primary infection structures in Aspergillus fumigatus, the etiologic agent of aspergillosis. Here, we characterized CrpA (a cysteine-rich protein), a conidial surface-associated protein important for fungal evasion and host immunity modulation. ΔcrpA conidia elicited decreased production of proinflammatory cytokines and increased production of anti-inflammatory cytokine IL-10 from murine macrophages and in the lungs of infected mice. Murine macrophages exposed to ΔcrpA conidia produce significantly higher levels of prostaglandins PGE2 and PGD2, suggesting that deletion of CrpA modulates cytokine production through effects on eicosanoid signaling. While ΔcrpA spores have lower virulence in larval zebrafish, this difference is abrogated in larvae that cannot produce prostaglandins. The CrpA protein can directly modulate PGE2 and cytokine production by macrophages, and solid-state NMR shows that ΔcrpA swollen conidia present lower β-1,3-glucan and chitin than the wild-type strain, suggesting that the effects of the ΔcrpA mutant on macrophages are due to the combinatorial effects of direct CrpA action and altered cell wall PAMP recognition. ΔcrpA mutants are avirulent in an immunocompetent murine model of aspergillosis, and high CrpA-specific IgG responses were found in antisera from individual patients with invasive pulmonary aspergillosis, suggesting a role for CrpA in A. fumigatus pathogenesis.IMPORTANCEConidia serve as the primary infectious units of Aspergillus fumigatus, the causative agent of aspergillosis. This study identifies CrpA, a cysteine-rich protein found on the conidial surface, as a crucial regulator of immune modulation and fungal virulence. Loss of CrpA (ΔcrpA) alters host immune responses, resulting in reduced production of proinflammatory cytokines and increased IL-10 levels in both murine macrophages and infected lungs. ΔcrpA conidia also stimulate elevated levels of prostaglandins PGE2 and PGD2. This immunomodulatory effect is dependent on eicosanoid signaling as the virulence of ΔcrpA is restored in prostaglandin-deficient zebrafish larvae. CrpA directly modulates macrophage production of PGE2 and cytokines. Solid-state NMR analysis shows that ΔcrpA conidia expose lower levels of β-1,3-glucan and chitin, suggesting that CrpA influences both cell wall composition and host pattern recognition receptor engagement. ΔcrpA strains are avirulent in immunocompetent mice, and patients with invasive pulmonary aspergillosis exhibit elevated CrpA-specific IgG. These results highlight CrpA as a key virulence factor in A. fumigatus and a promising target for antifungal therapy.