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Updated: Aug 16, 2026
Histological Quantification to Determine Lung Fungal Burden in Experimental Aspergillosis
Published on: March 9, 2018
Involvement of toll-like receptor 2 in experimental invasive pulmonary aspergillosis
Viviane Balloy1, Mustapha Si-Tahar, Osamu Takeuchi
1Unité de Défense Innée et Inflammation, Inserm E336, Institut Pasteur, 25, rue du Dr Roux, 75015 Paris, France.
Abstract:
Aspergillus fumigatus, an opportunistic fungal pathogen, causes severe and usually fatal invasive pulmonary aspergillosis in immunocompromised hosts. Interestingly, Drosophila cells lacking the Toll protein are prone to A. fumigatus infection. In the current study, we looked for the involvement of Toll-like receptor 2 (TLR2) in the recognition of A. fumigatus by analyzing the in vivo and ex vivo responses of immunocompromised TLR2(-/-) and TLR2(+/+) mice to this fungus. Upon intratracheal administration of conidia, survival and tumor necrosis factor alpha (TNF-alpha), interleukin-12, and macrophage inhibitory protein-2 alpha concentrations in the airspaces of TLR2(-/-) mice were significantly lower than those of TLR2(+/+) animals. In vitro analysis of TNF-alpha production by conidia-challenged alveolar macrophages from TLR2(-/-) revealed a significant deficiency in comparison with macrophages from TLR2(+/+) mice. Infected TLR2(-/-) mice also have a higher respiratory distress and a higher pathogen burden than TLR2(+/+) mice. These data demonstrate that TLR2 plays a significant role in the defense of the host against A. fumigatus infection.
Insights
Toll-like receptor 2 (TLR2) is crucial for host defense against Aspergillus fumigatus. Mice lacking TLR2 showed reduced survival and increased fungal burden, highlighting TLR2's role in combating this opportunistic pathogen.
Area of Science:
- Immunology
- Mycology
- Infectious Diseases
Background:
- Aspergillus fumigatus is an opportunistic fungal pathogen causing life-threatening invasive pulmonary aspergillosis in immunocompromised individuals.
- The innate immune system plays a critical role in controlling fungal infections.
- Toll-like receptors (TLRs) are key pattern recognition receptors involved in host defense against pathogens.
Purpose of the Study:
- To investigate the role of Toll-like receptor 2 (TLR2) in the host's immune response to Aspergillus fumigatus infection.
- To compare the susceptibility and immune responses of TLR2 knockout mice versus wild-type mice to A. fumigatus.
Main Methods:
- In vivo studies using intratracheal administration of A. fumigatus conidia to immunocompromised TLR2(-/-) and TLR2(+/+) mice.
- Ex vivo analysis of immune cell responses, including cytokine production (TNF-alpha, IL-12, MIP-2 alpha) from alveolar macrophages.
- Assessment of survival rates, pathogen burden, and respiratory distress.
Main Results:
- TLR2(-/-) mice exhibited significantly lower survival rates and reduced concentrations of TNF-alpha, IL-12, and MIP-2 alpha in the lungs compared to TLR2(+/+) mice.
- Alveolar macrophages from TLR2(-/-) mice showed a significant deficiency in TNF-alpha production upon challenge with A. fumigatus conidia.
- Infected TLR2(-/-) mice displayed increased respiratory distress and a higher fungal pathogen burden.
Conclusions:
- Toll-like receptor 2 (TLR2) is essential for effective host defense against Aspergillus fumigatus.
- TLR2 mediates critical innate immune responses, including pro-inflammatory cytokine production and pathogen clearance.
- Targeting TLR2 may represent a therapeutic strategy to enhance host resistance against invasive aspergillosis.
