Platycodin D Inhibits HFD/STZ-Induced Diabetic Nephropathy Via Inflammatory and Apoptotic Signaling Pathways in C57BL/6 Mice

Abstract

Ethnopharmacological relevance: Platycodon grandiflorum A. DC（PG）is a traditional herb used in Asian countries and is widely used in formulas for the treatment of respiratory diseases and diabetes, where platycodin D (PD) is one of the most important components of PG.

Aim of the study: This study aimed to investigate the protective effects and regulatory mechanisms of PD on kidney injury in high-fat diet (HFD) combined with streptozotocin (STZ)-induced diabetic nephropathy (DN).

Materials and methods: DN mice were treated with oral gavage of the PD (2.5, 5 mg/kg) for 8 weeks. Molecular docking and molecular dynamics (MD) were utilized to study the binding ability of PD to target NF-κB and apoptosis signaling pathway-related proteins. Moreover, a western blot was used to test the expressions of NF-κB and apoptosis-related proteins. Vitro experiments were performed to validate the related mechanisms using the high glucose culture of RAW264.7 cells and HK2 cells.

Results: In in vivo experiments, the administration of PD (2.5 and 5.0 mg/kg) reduced FBG and HOMA-IR levels in DN mice, while lipid levels and renal function significantly improved. Moreover, PD significantly inhibited the development of DN by regulating NF-κB and apoptotic signaling pathways, reducing the abnormal elevation of serum inflammatory factors TNF-α and IL-1β in DN mice, and repairing renal apoptosis. Vitro experiments using NF-κB inhibitor ammonium pyrrolidine dithiocarbamate (PDTC) confirmed that PD could alleviate high glucose-induced inflammation in RAW264.7 cells and inhibit the release of inflammatory factors. And in HK2 cell experiments, it was verified that PD could inhibit ROS generation, reduce the loss of JC-1 and suppress HK2 cell injury by regulating NF-κB and apoptotic pathways.

Conclusions: The data suggested that PD has the potential to prevent and treat DN and is a promising natural nephroprotective agent.

Note:
Funding Declaration: This work was supported by the grant of the National Natural Science Foundation of China (No. 82204612) and the grant Jilin Science & Technology Development Plan (No.20200404007YY).

Conflicts of Interest: None

Ethical Approval: Animal experiments were conducted by Jilin Agricultural University's "Regulations on the Management of Experimental Animals". The experiment was approved by Jilin Agricultural University's Experimental Animal Ethics Committee (No.: 2019 07 05 002).

Keywords: Platycodin D, Diabetic nephropathy, Molecular docking, Molecular dynamics, NF-κB pathway, Apoptotic pathways.