Innate Immune Response to Aspergillus Fumigatus Infections

Aspergillus fumigatus is an airborne fungal pathogen that challenges the host’s first line of defence, the innate immune system. Inhaled spores, or conidia, are encountered by airway epithelial cells which act as both a physical barrier and an active sentinel population. These cells secrete cytokines and chemokines that recruit neutrophils and monocyte-derived macrophages to the site of infection. Recognition of fungal cell-wall components such as β-glucans and melanins via pattern recognition receptors on innate leukocytes triggers phagocytosis, reactive oxygen species generation, degranulation and release of inflammatory mediators. Neutrophils deploy a combination of oxidative and non-oxidative killing mechanisms, including the formation of neutrophil extracellular traps. Monocyte-derived macrophages and dendritic cells process and clear fungal elements, while shaping downstream adaptive immunity through antigen presentation and cytokine production. Fungal virulence factors such as gliotoxin can suppress phagocyte function by interfering with lipid mediator biosynthesis or blocking v-ATPase assembly, thus impairing phagolysosomal acidification. Epithelial factors, including CFTR-dependent chloride transport, support mucociliary clearance and maintain barrier integrity during early fungal germination. The dynamic interplay between fungal evasion strategies and coordinated innate effector mechanisms determines whether inhaled conidia are eliminated or progress to allergic inflammation, chronic colonisation or invasive disease.

Research from Nature Portfolio

Recent studies have demonstrated that conidial melanin exerts a potent modulatory effect on airway epithelial responses. Using a primary human airway epithelial model, researchers found that fungal melanins block post-translational secretion of chemokines such as CXCL1 and CXCL8 by interfering with intracellular calcium flux, thereby reducing neutrophil recruitment both in vitro and in vivo. This mechanism is independent of melanin uptake and extends to responses against bacterial and exogenous cytokine stimuli, revealing a broad role for fungal melanin in dampening epithelial-derived chemotactic signals during early host defence.

Innate Immune Response to Aspergillus Fumigatus Infections publication trend

The graph below shows the total number of articles in innate immune response to aspergillus fumigatus infections across all publications each year (not limited to Nature Index journals).

Technical terms

Conidia: Asexual fungal spores that serve as the primary infectious particles of Aspergillus fumigatus.

Neutrophils: Innate immune granulocytes that migrate to infection sites and deploy oxidative and non-oxidative killing mechanisms against pathogens.

Dendritic cells: Antigen-presenting cells that detect pathogens, process antigens and activate adaptive immune responses.

Chemokines: Small secreted proteins that orchestrate the migration of immune cells to sites of infection or inflammation.

Gliotoxin: A secondary metabolite produced by Aspergillus fumigatus that impairs phagocyte function by altering lipid mediator pathways and phagolysosomal activity.

CFTR: A chloride channel expressed in epithelial cells that maintains barrier integrity and mucociliary clearance during airway defence.

References

1. Fungal melanin suppresses airway epithelial chemokine secretion through blockade of calcium fluxing. Nature Communications (2024).
2. Aspergillus-mediated allergic airway inflammation is triggered by dendritic cell recognition of a defined spore morphotype. Journal of Allergy and Clinical Immunology (2024).
3. Aspergillus fumigatus‐derived gliotoxin impacts innate immune cell activation through modulating lipid mediator production in macrophages. Immunology (2024).
4. Protective role of CFTR during fungal infection of cystic fibrosis bronchial epithelial cells with Aspergillus fumigatus. Frontiers in Cellular and Infection Microbiology (2023).
5. Preparations for Invasion: Modulation of Host Lung Immunity During Pulmonary Aspergillosis by Gliotoxin and Other Fungal Secondary Metabolites. Frontiers in Immunology (2018).