Basic Study
Copyright ©The Author(s) 2021. Published by Baishideng Publishing Group Inc. All rights reserved.
World J Diabetes. Jan 15, 2021; 12(1): 19-46
Published online Jan 15, 2021. doi: 10.4239/wjd.v12.i1.19
Metformin regulates inflammation and fibrosis in diabetic kidney disease through TNC/TLR4/NF-κB/miR-155-5p inflammatory loop
Yang Zhou, Xiao-Yu Ma, Jin-Yu Han, Min Yang, Chuan Lv, Ying Shao, Yi-Li Wang, Jia-Yi Kang, Qiu-Yue Wang
Yang Zhou, Yi-Li Wang, Jia-Yi Kang, Qiu-Yue Wang, Department of Endocrinology, The First Affiliated Hospital of China Medical University, Shenyang 110000, Liaoning Province, China
Xiao-Yu Ma, Jin-Yu Han, Department of Gerontology, The First Affiliated Hospital of China Medical University, Shenyang 110000, Liaoning Province, China
Min Yang, Department of Clinical Laboratory, The First Affiliated Hospital of China Medical University, Shenyang 110000, Liaoning Province, China
Chuan Lv, Department of Endocrinology, The People’s Hospital of China Medical University, Shenyang 110000, Liaoning Province, China
Ying Shao, Department of Endocrinology, Shengjing Hospital of China Medical University, Shenyang 110000, Liaoning Province, China
Author contributions: Zhou Y performed the experiments and data analysis and contributed to paper writing; Ma XY performed the experiments and data analysis; Han JY, Yang M, and Lv C performed the experiments; Shao Y supervised the project and contributed to paper writing; Wang YL contributed to paper writing; Kang JY performed the data analysis and contributed to paper writing; Wang QY supervised the project, finalized the manuscript, and managed the submission process.
Supported by National Key Research and Development Program of China, No. 2018YFC1313900 and No. 2018YFC1313901; and The Higher School High-end Talent Team Construction of Liaoning Province, No. [2014]187.
Institutional review board statement: This study was approved by The Ethics Committee of The First Affiliated Hospital of China Medical University. All procedures were performed in accordance with the ethical standards mentioned in the 1964 Declaration of Helsinki and its subsequent amendments or comparable ethical standards.
Institutional animal care and use committee statement: All animal experiments conformed to the internationally accepted principles for the care and use of laboratory animals. All experiments were approved by The Institutional Animal Care and Use Committee (IACUC) of The China Medical University Animal Experiment Department, Approval No. 2017112.
Conflict-of-interest statement: The author(s) have no potential conflicts of interest with respect to the research, authorship, and/or publication of this article to declare.
Data sharing statement: No additional data are available.
ARRIVE guidelines statement: The authors have read the ARRIVE guidelines, and the manuscript was prepared and revised according to the ARRIVE guidelines.
Open-Access: This article is an open-access article that was selected by an in-house editor and fully peer-reviewed by external reviewers. It is distributed in accordance with the Creative Commons Attribution NonCommercial (CC BY-NC 4.0) license, which permits others to distribute, remix, adapt, build upon this work non-commercially, and license their derivative works on different terms, provided the original work is properly cited and the use is non-commercial. See:
Corresponding author: Qiu-Yue Wang, PhD, Professor, Department of Endocrinology, The First Affiliated Hospital of China Medical University, No. 155 Nanjing North Street, Heping District, Shenyang 110000, Liaoning Province, China.
Received: August 21, 2020
Peer-review started: August 21, 2020
First decision: September 21, 2020
Revised: October 5, 2020
Accepted: October 26, 2020
Article in press: October 26, 2020
Published online: January 15, 2021

Type 2 diabetes mellitus (T2DM) is significantly increasing worldwide, and the incidence of its complications is also on the rise. One of the main complications of T2DM is diabetic kidney disease (DKD). The glomerular filtration rate (GFR) and urinary albumin creatinine ratio (UACR) increase in the early stage. As the disease progresses, UACR continue to rise and GFR begins to decline until end-stage renal disease appears. At the same time, DKD will also increase the incidence and mortality of cardiovascular and cerebrovascular diseases. At present, the pathogenesis of DKD is not very clear. Therefore, exploration of the pathogenesis of DKD to find a treatment approach, so as to delay the development of DKD, is essential to improve the prognosis of DKD.


To detect the expression of tenascin-C (TNC) in the serum of T2DM patients, observe the content of TNC in the glomerulus of DKD rats, and detect the expression of TNC on inflammatory and fibrotic factors in rat mesangial cells (RMCs) cultured under high glucose condition, in order to explore the specific molecular mechanism of TNC in DKD and bring a new direction for the treatment of DKD.


The expression level of TNC in the serum of diabetic patients was detected by enzyme-linked immunosorbent assay (ELISA), the protein expression level of TNC in the glomerular area of DKD rats was detected by immunohistochemistry, and the expression level of TNC in the rat serum was detected by ELISA. Rat glomerular mesangial cells were cultured. Following high glucose stimulation, the expression levels of related proteins and mRNA were detected by Western blot and polymerase chain reaction, respectively.


ELISA results revealed an increase in the serum TNC level in patients with T2DM. Increasing UACR and hypertension significantly increased the expression of TNC (P < 0.05). TNC expression was positively correlated with glycosylated haemoglobin (HbA1c) level, body mass index, systolic blood pressure, and UACR (P < 0.05). Immunohistochemical staining showed that TNC expression in the glomeruli of rats with streptozotocin-induced diabetes was significantly increased compared with normal controls (P < 0.05). Compared with normal rats, serum level of TNC in diabetic rats was significantly increased (P < 0.05), which was positively correlated with urea nitrogen and urinary creatinine (P < 0.05). The levels of TNC, Toll-like receptor-4 (TLR4), phosphorylated nuclear factor-κB p65 protein (Ser536) (p-NF-κB p65), and miR-155-5p were increased in RMCs treated with high glucose (P < 0.05). The level of TNC protein peaked 24 h after high glucose stimulation (P < 0.05). After TNC knockdown, the levels of TLR4, p-NF-κB p65, miR-155-5p, connective tissue growth factor (CTGF), and fibronectin (FN) were decreased, revealing that TNC regulated miR-155-5p expression through the TLR4/NF-κB p65 pathway, thereby regulating inflammation (NF-κB p65) and fibrosis (CTGF and FN) in individuals with DKD. In addition, metformin treatment may relive the processes of inflammation and fibrosis in individuals with DKD by reducing the levels of the TNC, p-NF-κB p65, CTGF, and FN proteins.


TNC can promote the occurrence and development of DKD. Interfering with the TNC/TLR4/NF-κB p65/miR-155-5p pathway may become a new target for DKD treatment.

Keywords: Tenascin-C, miR-155-5p, Metformin, Type 2 diabetes mellitus, Diabetic kidney disease, Toll-like receptor 4

Core Tip: We investigated the correlation between serum tenascin-C (TNC) levels and urine albumin clearance ratios in a total of 380 patients with type 2 diabetes mellitus, TNC can regulate miR-155-5p through Toll-like receptor 4/nuclear factor κB signaling in rat mesangial cells under hyperglycaemia condition, and metformin can inhibit inflammation and fibrosis in diabetic kidney disease through TNC.