Finding the needle in a haystack
Aspergillus fumigatus is a fungus widespread in nature, typically found in soil and decaying organic matter and can release thousands of spores that can become airborne. Opportunistic infections with Aspergillus fumigatus can cause life-threatening lung infections in immunocompromised patients. In a new research article we describe 3D light sheet fluorescence microscopy of lungs to dissect local host immune-Aspergillus fumigatus interactions.
In our new research article, the lead authors Dr. Jorge Amich (former postdoc in the Beilhack lab and now MRC Career Award Research Fellow at Manchester University, UK) and Dr. Zeinab Mokhtari dissected the dynamic and highly complex fungal pathogen interactions with the lung during the development of invasive aspergillosis we employed quantitative light sheet fluorescence microscopy (LSFM).
Generating a plane of light to section through biological specimens, LSFM can acquire multicolor images at speeds 100 to 1000 times faster than e.g. confocal microscopy, which is a point-scanning method. Multicolor LSFM is revolutionizing how we can obtain three-dimensional views deep into tissues without distorting artifacts in subcellular resolution.
To mimic the clinical situation in patients we analyzed three very common murine models of with corticosteroid treatment, chemotherapy-induced leukopenia, or myeloablative irradiation. Scanning of lungs with LSFM revealed distinct 3D architectures of fungal growth and degrees of tissue invasion in each model. LSFM revealed the spatial distribution, interaction, and activation of alveolar macrophages and neutrophilic granulocytes, two key immune cell populations in antifungal defense. Clearly, fungal growth patterns correlated with the detected effects of the immunosuppressive regimens on the local immune cell populations but also revealed that less than 80% of fungal growth occurred outside the alveolar space. LSFM proofed as a a powerful tool to describe important features of fungal growth and of the local immune response. As multiparameter LSFM allows for assaying models of pulmonary aspergillosis using lower, more physiologically appropriate doses of infective conidia, this method could form the basis for refining and maximizing the utility of lung infection models.
Our work was generously supported by the DFG Transregio Research Network TRR124, the DFG Transregio Research Network TRR225. The analytical tools developed in this project are key for monitoring 3D tissue models as they are developed in the DFG consortium Biofabrication (TRR225) and in our DFG graduate college 3D Infect (DFG RTG 2157).
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