Cinnabarinic acid regulates the barrier function and inflammatory reactions in primary chicken intestinal epithelial cells with hyperthermia treatment via the aryl hydrocarbon receptor

This study aimed to evaluate the efficacy of cinnabarinic acid (CA) in regulating the barrier function and inflammatory responses of primary intestinal epithelial cells (IECs) derived from chicken embryos subjected to hyperthermia, so as to provide a theoretical basis for alleviating heat stress in broilers. The IECs were randomly divided into 4 groups, a thermoneutral group (37 °C), a hyperthermia group (43 °C), a hyperthermia + CA group and a hyperthermia + CA + aryl hydrocarbon receptor (AhR) inhibitor group. A hyperthermia cell model was established by exposing IECs to 43 °C for 6 h, and the experimental treatments consisted of 1 µmol/L CA and 1 µmol/L AhR inhibitor. According to the results, the supplementation of 1 µmol/L CA into the basal culture medium markedly improved the relative cell viability of hyperthermia-treated IECs, decreased the levels of lactate dehydrogenase (LDH), tumor necrosis factor alpha (TNF-α), and interleukin (IL)-1β in cell culture supernatants, downregulated the mRNA expression of heat shock protein (HSP)70, HSP90, claudin2, toll-like receptor (TLR)4, TLR5 and TLR21, increased AhR protein expression and the mRNA expression of occludin, increased the secretion of IL-22 of IECs treated with hyperthermia. Notably, the protective and regulatory effects of CA were markedly abolished by the AhR inhibitor under hyperthermic conditions. In conclusion, CA activated AhR in IECs, promoted IL-22 secretion, inhibited inflammatory responses, increased tight junction proteins genes expression, enhanced epithelial barrier integrity.