Inflammatory and Cytotoxic Responses in Mouse Lungs Exposed to Purified Toxins from Building Isolated Penicillium brevicompactum Dierckx and P. chrysogenum Thom.

Abstract

In vitro and in vivo studies have shown that building-associated Penicillium spores and spore extracts can induce significant inflammatory responses in lung cells and animal models of lung disease. However, because spores and spore extracts comprise mixtures of bioactive constituents often including toxins, it is impossible to resolve which constituent mediates inflammatory responses. This study examined dose-response (0.5 nM, 2.5 nM, 5.0 nM, 12.5 nM/g body weight (BW) animal) and time-course (3, 6, 24 and 48 h post instillation (PI)) relationships associated with inflammatory and cytotoxic responses in mouse lungs intratracheally instilled with pure brevianamide A, mycophenolic acid, and roquefortine C. High doses (5.0 nM and/or 12.5 nM/g BW animal) of brevianamide A and mycophenolic acid, the dominant metabolites of P. brevicompactum, and roquefortine C, the dominant metabolite of P. chrysogenum, induced significant inflammatory responses within 6 h PI, expressed as differentially elevated macrophage, neutrophil, MIP-2, TNF, and IL-6 concentrations in the bronchioalveolar lavage fluid (BALF) of intratracheally exposed mice. Macrophage and neutrophil numbers were maximal at 24 h PI; responses of the other inflammatory markers were maximal at 6 h PI. Except for macrophage numbers in mycophenolic acid–treatment animals, cells exhibited significant dose-dependent-like responses; for the chemo-/cytokine markers, dose dependency was lacking except for MIP-2 concentration in brevianamide A–treatment animals. It was also found that brevianamide A induced cytotoxicity expressed as significantly increased LDH concentration in mouse BALF, at concentrations of 12.5 nM/g BW animal and at 6 and 24 h PI. Albumin concentrations, measured as a nonspecific marker of vascular leakage, were significantly elevated in the BALF of mice treated with 12.5 nM/g nM brevianamide A/animal from 6 to 24 h PI and in ≥5.0 nM/g mycophenolic acid–treated animals at 6 to 24 h PI. These results suggest that these three toxins from Penicillium species common on damp materials in residential housing provoke compound-specific toxic responses with different toxicokinetics. Moreover, that these toxins can stimulate significant inflammatory responses in vivo might help explain some of the indoor effects associated with Penicillium spore exposures in indoor environments.