GCA and Obesity: Recent studies highlight obesity‐associated immunosenescence, where senescent macrophages drive obesity‐induced inflammation and disorder of lipid metabolism.[20, 21, 22] Our previous work showed that macrophages in obese mice contribute to skeletal deterioration via paracrine signaling.[4] In addition, we reported that senescent macrophages secret grancalcin (GCA), promoting bone loss and impairing fracture healing in aging mice.[23, 24] However, several questions remain unanswered: What is the role of obese gut microbiota in immunosenescence?