Mold was nominated to the NTP for toxicological characterization and based on their inhalation, mycological, and immunological expertise, NIOSH was identified as a partner in 2013 to conduct multiple sub-chronic (13-week) exposure studies to individual organisms or mixtures of molds mimicking a real-world exposure. NIOSH has developed a unique delivery system termed the NIOSH Acoustical Generator System (AGS) that allows for precisely controlled murine exposures to particulates via nose-only inhalation. This approach overcomes a number of limitations associated with previous mold exposure studies in experimental rodent models that have used less relevant means of exposure to assess fungal toxicity. The AGS developed as part of this partnership delivers fungal test articles to mice in a manner that simulates natural indoor fungal exposure within contaminated built environments. NIOSH continued to use the AGS and state-of-the-art methodologies to characterize toxicological endpoints following subchronic dry fungal spore and particle exposures to Aspergillus versicolor in FY19. In FY18 and 19, 1, 2, 3, 4, 8, and 13 week studies were conducted to assess pulmonary and systemic toxicity following repeated exposure to A. versicolor. Preliminary data revealed an increase of cells associated with innate immunity after 1 week of repeated exposure and followed by the infiltration of innate cells, B- cells, T-cells, and type 2 innate lymphoid cells (ILC2s) by 2 weeks. Repeated exposure to A. versicolor led to the increased production of local and circulating Th2 cytokines, including IL4 and IL13, as well as an increase in ILC2s by 4 weeks. By 13 weeks, cellular infiltration was decreased for all cell types except ILC2s. Analysis of miRNA, mRNA, and proteomic datasets derived from the lung homogenates of viable, nonviable, and air-only control samples from these toxicology studies are ongoing. Similar to A. fumigatus and S. chartarum, preliminary data revealed remodeling of pulmonary arterial tissue following repeated subchronic exposure to A. versicolor. A particularly interesting result for all of the fungal species studies to date has been the remodeling of pulmonary arterial tissue, highlighting the potential for cardiovascular involvement in human fungal exposures. In FY19, NIOSH also repeatedly exposed mice to A. versicolor for 4 and 13 weeks and then allowed recovery intervals varying from 1 week to 4 week to study whether the mice recovered from the pulmonary arterial tissue remodeling. Brain hemispheres derived from A. versicolor study mice have also been analyzed by Dr. Michelle Block at the Indiana University School of Medicine. Preliminary results demonstrate that 1 week of repeated A. versicolor exposure resulted in neuroinflammation and significant changes in the broad neuroinflammation transcriptome.The final report from the evaluation of the effects of 13-week inhalation exposure to Aspergillus fumigatus (NTP Toxicology Study #C08022) will be completed and published by the NTP/NIEHS by the end of 2019. NIOSH will also complete the NTP Toxicology Study #C04052 draft report by the end of 2019 and submit the report to the NTP for review and consideration. NTP Toxicology Study #C15017 that will evaluate A. versicolor will be scheduled mid FY20.
