Early-in-life inhalation of ferrocene-derived diesel exhaust-induced metabolic and small intestinal toxicities: Roles of peroxisome proliferator-activated receptor gamma and ferroptosis

Ferrocene-derived diesel exhaust (FDE) had been demonstrated to exhibit enhanced cardiopulmonary toxicities. This study evaluated the potential metabolic and small intestinal toxicities following early-in-life inhalation exposure to FDE using an in ovo air cell inhalation model in chicken embryos. Ferrocene was added to standard diesel fuel at 205, 410 or 820 mg/L (corresponding to 75, 150 or 300 ppm iron) and combusted in a diesel generator. The resulting FDE was exposed to embryonic day 18-19 chicken embryos via air cell inhalation. Serum, small intestine, white adipose tissue, and pancreas tissue from 1- or 3-month-old animals were collected and subjected to histopathological and biochemical/molecular evaluations. For mechanistic investigation, lentivirus-mediated in ovo silencing of PPARγ or the PPARγ agonist rosiglitazone was co-administered with FDE. Identical pathological and biochemical endpoints were evaluated in resulting animals. Following exposure to FDE, shortened small intestinal villi and decreased number of crypts, along with adipocyte hypertrophy and pancreatic islet hypertrophy were observed in 1- and 3-month-old animals. Additionally, elevated serum MDA and insulin levels as well as decreased serum SOD activity were observed. In ovo PPARγ silencing mimicked these effects, while pretreatment with rosiglitazone alleviated such effects. The expression of PPARγ, PGC1α, GPX4 and SLC7A11 was suppressed in small intestine samples from 1-month-old animals exposed to FDE. Again, PPARγ silencing mimicked the observed effects, while rosiglitazone alleviated such effects. In conclusion, early-in-life inhalation exposure to FDE resulted in metabolic and small intestinal toxicities in 1- or 3-month-old chickens, such effects were associated with PPARγ/PGC1α-ferroptosis signaling.