Co-exposure to ammonia and lipopolysaccharide-induced impaired energy metabolism via the miR-1599/HK2 axis and triggered autophagy, ER stress, and apoptosis in chicken cardiomyocytes

Ammonia (NH₃) and lipopolysaccharide (LPS), common pollutants in poultry farming environments, pose significant health risks by disrupting cellular processes. Although previous studies have demonstrated the individual effect of NH₃ or LPS on human and animal health, the mechanisms underlying their combined impact on chicken heart tissue remain poorly understood. In this study, we established a chicken cardiotoxicity model to investigate the effects of NH₃ and/or LPS exposure on energy metabolism, autophagy, endoplasmic reticulum (ER) stress, and apoptosis in cardiomyocytes. Our findings indicated that exposure to NH₃ or/and LPS reduced ATPase activity and ATP content, led to the downregulation of HK2, PK, PDHX, and SDH, and upregulation of AMPK, resulting in impaired energy metabolism in chicken cardiomyocytes. Additionally, we found the gga-miR-1599/HK2 axis as a key regulator involved in NH₃ or/and LPS-induced energy metabolism impairment. The impairment in energy metabolism activated the AMPK/mTOR pathway, which subsequently triggered autophagy, evidenced by the upregulation of Beclin, LC3-I, and LC3-II. Furthermore, decreased mTOR expression induced ER stress, as indicated by the upregulation of key markers such as ATF6, GRP78, IRE1, and PERK. ER stress, in turn, increased CHOP expression, which downregulated Bcl-2 and upregulated Bim, resulting in elevated levels of Bax, caspase-9, and caspase-3, ultimately triggering apoptosis. This study provides valuable insights into the mechanisms of NH₃ and LPS co-exposure on poultry heart tissue and identifies potential molecular targets for mitigating these adverse effects.