Wogonin Alleviates Kidney Tubular Epithelial Injury in Diabetic Nephropathy by Inhibiting PI3K/Akt/NF-κB Signaling Pathways

Abstract

Introduction

Kidney tubular epithelial injury is one of the key factors in the progression of diabetic nephropathy (DN). Wogonin is a kind of flavonoid, which has many pharmacological effects, such as anti-inflammation, anti-oxidation and anti-fibrosis. However, the effect of wogonin in renal tubular epithelial cells during DN is still unknown.

Materials and Methods

STZ-induced diabetic mice were given doses of wogonin (10, 20, and 40 mg/kg) by intragastric administration for 16 weeks. The metabolic indexes from blood and urine and pathological damage of renal tubules in mice were evaluated. Human tubular epithelial cells (HK-2) were cultured in high glucose (HG) condition containing wogonin (2μM, 4μM, 8μM) for 24 h. Tubular epithelial cell inflammation and autophagic dysfunction both in vivo and in vitro were assessed by Western blot, qRT-PCR, IHC, and IF analyses.

Results

The treatment of wogonin attenuated urinary albumin and histopathological damage in tubulointerstitium of diabetic mice. We also found that wogonin down-regulated the expression of pro-inflammatory cytokines and autophagic dysfunction in vivo and in vitro. Molecular docking and Cellular Thermal Shift Assay (CETSA) results revealed that mechanistically phosphoinositide 3-kinase (PI3K) was the target of wogonin. We then found that inhibiting PI3K eliminated the protective effect of wogonin. Wogonin regulated autophagy and inflammation via targeting PI3K, the important connection point of PI3K/Akt/NF-κB signaling pathway.

Conclusion

Our study is the first to demonstrate the novel role of wogonin in mitigating tubulointerstitial fibrosis and renal tubular cell injury via regulating PI3K/Akt/NF-κB signaling pathway-mediated autophagy and inflammation. Wogonin might be a latent remedial drug against tubular epithelial injury in DN by targeting PI3K.

Keywords:

• diabetic nephropathy
• tubular epithelial cell
• wogonin
• inflammation
• autophagy
• PI3K/Akt/NF-κB pathway

Abbreviations

Akt, protein kinase B; BUN, blood urea nitrogen; CETSA, Cellular Thermal Shift Assay; CRE, creatinine; DN, diabetic nephropathy; DM, diabetic mellitus; ESRD, end-stage renal nephropathy; ECM, extracellular matrix; EMT, epithelial-to-mesenchymal transition; HK-2, human tubular epithelial cells; HG, high glucose; IF, immunofluorescence; IHC, immunohistochemistry; LG, low glucose; MG, mannitol glucose; mTOR, mammalian target of rapamycin; NC, normal control; PAS, Periodic acid–Schiff; PI3K, phosphoinositide 3-kinase; PI3Ki, PI3K inhibitor; STZ, streptozotocin; Wog, wogonin.

Data Sharing Statement

All the data in the manuscript are available upon reasonable request from the corresponding author.

Author Contributions

All authors made substantial contributions to conception and design, acquisition of data, or analysis and interpretation of data; took part in drafting the article or revising it critically for important intellectual content; agreed to submit to the current journal; gave final approval of the version to be published; and agreed to be accountable for all aspects of the work.

Disclosure

All authors declare that there are no competing interests.

Additional information

Funding

This study was supported by the Scientific Research Foundation of the Institute for Translational Medicine of Anhui Province (number: 2017zhyx01) and Natural Science Foundation of Anhui Province (No: 1808085MH236).