Related Experiment Video
Updated: Jan 23, 2026
Author Spotlight: Unraveling the Interplay Between Trichoderma stromaticum and the Mammalian Immune System
Published on: October 20, 2023
Early Interaction of Alternaria infectoria Conidia with Macrophages
M C Almeida1, D Antunes2, B M A Silva2
1CNC - Center for Neuroscience and Cell Biology of Coimbra, University of Coimbra, Rua Larga, 3004-504, Coimbra, Portugal. mcalmeida@uc.pt.
Abstract:
Fungi of the genus Alternaria are ubiquitous indoor and outdoor airborne agents, and individuals are daily exposed to their spores. Although its importance in human infections and, particularly in respiratory allergies, there are no studies of how Alternaria spp. spores interact with host cells. Our aim was to study the early interaction of Alternaria infectoria spores with macrophages, the first line of immune defense. RAW 264.7 macrophages were infected with A. infectoria conidia, and the internalization and viability of conidia once inside the macrophages were quantified during the first 6 h of interaction. Live cell imaging was used to study the dynamics of this interaction. TNF-α production was quantified by relative gene expression, and the concentration of other cytokines (IL-1α, IL-1β, IL-6, IL-4, IL-10, IL-17, GM-CSF and INF-γ) and a chemokine, MIP-1α, was quantified by ELISA. Conidia were rapidly internalized by macrophages, with approximately half internalized after 30 min of interaction. During the first 6 h of interaction, macrophages retained the ability to mitotically divide while containing internalized conidia. The classical macrophage-activated morphology was absent in macrophages infected with conidia, and TNF-α and other cytokines and chemokines failed to be produced. Thus, macrophages are able to efficiently phagocyte A. infectoria conidia, but, during the first 6 h, no effective antifungal response is triggered, therefore promoting the residence of these fungal conidia inside the macrophages.
Insights
Alternaria infectoria fungal spores are quickly engulfed by macrophages, the immune system's first responders. However, these immune cells fail to mount an effective antifungal response, allowing the fungus to survive inside them.
Area of Science:
- Mycology
- Immunology
- Cell Biology
Background:
- Fungi of the genus Alternaria are common airborne allergens and potential human pathogens.
- Exposure to Alternaria spores is widespread, yet their interaction with host immune cells remains poorly understood.
- Macrophages are critical immune cells involved in the initial defense against pathogens.
Purpose of the Study:
- To investigate the early cellular interactions between Alternaria infectoria spores and macrophages.
- To quantify the internalization and viability of A. infectoria conidia within macrophages.
- To assess the immune response, including cytokine production, following A. infectoria conidia exposure.
Main Methods:
- RAW 264.7 macrophage cell line infected with A. infectoria conidia.
- Live cell imaging to observe real-time interaction dynamics.
- Quantification of conidia internalization and viability over 6 hours.
- Measurement of TNF-α gene expression and various cytokines/chemokines (IL-1α, IL-1β, IL-6, IL-4, IL-10, IL-17, GM-CSF, INF-γ, MIP-1α) via ELISA.
Main Results:
- Macrophages rapidly internalized A. infectoria conidia, with ~50% phagocytosed within 30 minutes.
- Internalized conidia remained viable within macrophages for up to 6 hours.
- Macrophages containing conidia did not exhibit classical activation morphology.
- No significant production of TNF-α, other pro-inflammatory cytokines, or chemokines was detected.
Conclusions:
- Macrophages efficiently phagocytose Alternaria infectoria conidia.
- The early interaction (first 6 hours) does not trigger a robust innate immune response.
- This lack of an effective early antifungal response facilitates the survival of A. infectoria conidia within macrophages, potentially aiding fungal persistence.
Related Concept Videos
02:39Predator-Prey Interactions
01:24Van der Waals Interactions
02:57piRNA - Piwi-interacting RNAs
01:29Drug-Receptor Interactions
Several parameters, such as the drug's affinity for its receptor and its efficacy, which is its ability to activate the receptor, determine the drug's effect on the tissue....
01:20Gene-Environment Interactions
01:19Interactions Between Signaling Pathways
Convergence and divergence, and cross-talk between signaling pathways
Two distinct signaling pathways can converge on a single functional unit, which may either be a single protein or a complex of proteins. The response is either functionally distinct or synergistic between the two pathways but different from the response...