C57bl 6

C57BL/6 and OPG-KO^{29 (link)} mice were purchased from Sankyo Labo Service Corporation (Tokyo, Japan) and CLEA Japan (Tokyo, Japan), respectively. Col1(2.3)-GFP mice were provided by K. Matsuo (Keio University, Tokyo, Japan)^{32 (link)}. To generate Col1(2.3)-GFP+/−; OPG+/−mice, we crossed Col1(2.3)-GFP+/−with OPG-KO. Further, the Col1(2.3)-GFP+/−; OPG+/−and OPG+/−mice were crossed to generate Col1(2.3)-GFP+/−; wild-type mice and Col1(2.3)-GFP+/−; OPG-KO mice. Euthanasia was performed by cervical spine fracture dislocation under anesthesia with isoflurane (Pfizer Inc., New York City, NY, USA), when the mice were used for experiments. All animals were maintained under specific pathogen-free conditions at 24 ± 2 °C and 50–60% humidity with a 12 h light/dark cycle, and were provided with sterilized water and ad libitum diets in the animal facilities certified by the Animal Care and Use Committees of Tokyo Dental College or Matsumoto Dental University. Animal studies were approved and performed in accordance with the guidelines of Tokyo Dental College and Matsumoto Dental University Animal Care Committee.

Thirty-one male db/db mice (a mouse model of type 2 diabetes) and seven male C57/BL6 (wild type) mice were purchased from Sankyo Labo Service at the age of 6 weeks and kept on standard rodent chow. All db/db mice developed diabetes at the age of 8 weeks with FBG levels above 200 mg/dL. Starting from the age of 9 weeks, the diabetic db/db mice were given standard rodent chow with or without diet containing the SGLT2i (ipragliflozin) at the dose of 1.0 mg/kg/day for 4 weeks. The wild-type mice were kept on standard rodent chow; they were used as the control model during the same period. At the end of the treatment period, we collected peritoneal macrophages.