Macrocyclic
trichothecene mycotoxins produced by indoor air molds potentially contribute to symptoms associated with damp building illnesses. The purpose of this investigation was to determine (1) the kinetics of nasal
inflammation and neurotoxicity after a single intranasal instillation of
roridin A (RA), a representative macrocyclic
trichothecene; and (2) the capacity of
lipopolysaccharide (LPS) to modulate RA's effects. C57Bl/6 female mice were intranasally instilled once with 50 mul of RA (500 mug/kg
body weight [bw]) in saline or saline only and then nose and brain tissues were collected over 72 h and processed for histopathologic and
messenger RNA (
mRNA) analysis. RA-induced apoptosis specifically in olfactory sensory neurons (OSNs) after 24 h postinstillation (PI) causing marked
atrophy of olfactory epithelium (OE) that was maximal at 72 h PI. Concurrently, there was marked bilateral
atrophy of olfactory nerve layer of the olfactory bulbs (OBs) of the brain. In the ethmoid turbinates, upregulated
messenger RNA (
mRNA) expression of the proapoptotic gene FAS and the proinflammatory
cytokines tumor necrosis factor-alpha,
interleukin (IL)-6,
IL-1, and macrophage inhibitory protein-2 was observed from 6 to 24 h PI, whereas expression of several other proapoptotic genes (PKR, p53, Bax, and
caspase-activated DNAse) was detectable only at 24 h PI. Simultaneous exposure to LPS (500 ng/kg bw) and a lower dose of RA (250 mug/kg bw) magnified RA-induced proinflammatory gene expression, apoptosis, and
inflammation in the nasal tract. Taken together, the results suggest that RA markedly induced FAS and proinflammatory
cytokine expression prior to evoking OSN apoptosis and OE
atrophy and that RA's effects were augmented by LPS.