# Polygonati Rhizoma Polysaccharides Ameliorated Diabetic Kidney Disease in db/db Mice via Inhibiting TGFβ /Smad2 Signaling Pathway

## TL;DR

A plant-based treatment improved kidney disease in diabetic mice by reducing inflammation and oxidative stress.

## Contribution

This study is the first to show that Polygonati Rhizoma polysaccharides reduce diabetic kidney disease via the TGFβ/Smad2 pathway.

## Key findings

- PP reduced kidney dysfunction and damage in diabetic db/db mice.
- PP improved lipid metabolism and reduced oxidative stress in diabetic mice.
- PP inhibited TGFβ/Smad2 signaling and increased Smad7 expression in mouse kidneys.

## Abstract

Polygonati Rhizoma polysaccharides (PP) are the active components isolated from medicine food homology (MFH) Chinese herb Polygonati Rhizoma. Diabetic kidney disease (DKD) is a serious diabetic complication occurring in the later stage of diabetes. We have previously reported the hypoglycemic effect of PP on early‐stage type 2 diabetes (T2D). This study evaluated the effect of PP on DKD and investigated the underlying mechanisms. PP was mainly composed of L‐fucose, L‐rhamnose, D‐glucose, and D‐mannose. Ten‐week‐old Leprdb/Leprdb (db/db) compared with control Leprdb/Lepr+ (db/+) mice were given vehicle or PP for 16 weeks. Our results showed that PP alleviated renal dysfunction (BUN, Cr, microalbumin) and pathological damage in db/db mice. PP improved lipid homeostasis (TG, NEFA, and HDL) and reversed oxidative stress (CAT, MDA, SOD, and GSH) in the serum of db/db mice. Besides, PP reduced the Masson‐positive area and expression of TGFβ in the kidneys from db/db mice. Furthermore, PP upregulated the expression of Smad7 and abrogated the phosphorylation of Smad2 in the kidneys from db/db mice. In conclusion, PP ameliorated kidney dysfunction and fibrosis through attenuating dyslipidemia, anti‐oxidative stress, and inhibiting the activation of TGFβ/Smad2 signaling pathway in db/db mice. The study provides a theoretical basis for further elucidation of the effect and mechanism of PP in attenuating DKD.

PP ameliorated diabetic kidney disease in T2D db/db mice. PP improved the lipid metabolism and attenuated the oxidative stress in T2D db/db mice. PP increased the expression of Smad7 and inhibited the activation of TGFβ/Smad2 signaling pathway in kidneys from T2D db/db mice.