Quantitative Immunohistochemistry of Joint Proteins

Immunohistochemistry was performed with specific antibodies for target proteins following a protocol described previously with some modifications [6 (link)]. Knee joint sections on slides were incubated with anti-VDR, anti-PPAR-γ, anti-LC-3, or anti-P62 (Boster, Wuhan, China) antibodies. Subsequently, the sections were stained with a polymer horseradish peroxidase (HRP) detection system (PV9001, ZSGB-BIO, Beijing, China) and visualized with a diaminobenzidine (DAB) peroxidase substrate kit (ZLI-9017, ZSGB-BIO, Beijing, China). Each section was evaluated under a microscope (DMi8, LEICA, Wetzlar, Germany) in three randomly selected areas at a magnification of 20×. Image-Pro Plus 6 (Media Cybernetics, Inc.) was used to analyze the average integrated optical density (IOD) according to a previously described protocol [35 (link)].