Preparation of a polyclonal antibody against Lysosome-Associated Membrane Protein-1 for chicken and its application in the liver of broilers under chronic heat stress.

Lysosome-Associated Membrane Protein 1 (LAMP1) is a critical lysosomal structural marker implicated in cellular stress responses. Heat stress (HS) is a major challenge in poultry production, causing liver injury, yet LAMP1's role in chronic HS remains unexplored due to the absence of chicken-specific antibodies. Here, we developed a polyclonal antibody against chicken LAMP1 and applied it to investigate hepatic responses under chronic HS. Bioinformatic analysis identified multiple antigenic epitopes, a signal peptide, and a transmembrane domain in chicken LAMP1 (GenBank ID: 396220). Recombinant LAMP1 expressed in E. coli elicited high-titer antibodies (≥1:409600) in rabbits. Antibody specificity was validated by western blotting, immunohistochemistry, immunofluorescence, and Si-LAMP1 knockdown in DF-1 cells, confirming robust detection of LAMP1 in liver and kidney. Thirty-six Ningdu Sanhuang broilers were subjected to control (24 ± 2 °C) or chronic HS (37 ± 2 °C, 12 h/d, 35 d). Chronic HS induced hepatic damage, evidenced by elevated AST and ALT, and reduced antioxidant capacity (T-AOC). Importantly, LAMP1 expression was markedly downregulated in HS livers, highlighting its potential involvement in heat-induced lysosomal dysfunction. This study establishes a highly specific tool for chicken LAMP1 research and reveals a novel link between chronic HS and lysosomal protein regulation in broiler liver, offering mechanistic insights that may inform strategies to mitigate heat-induced hepatic injury in poultry.