Corrigendum to "Irbesartan Ameliorates Diabetic Nephropathy by Suppressing the RANKL-RANK-NF-κB Pathway in Type 2 Diabetic db/db Mice".

[This corrects the article DOI: 10.1155/2016/1405924.].

Irbesartan Ameliorates Diabetic Nephropathy by Suppressing the RANKL-RANK-NF-κB Pathway in Type 2 Diabetic db/db Mice.

The receptor activator of NF-κB ligand (RANKL) and its receptor RANK are overexpressed in focal segmental glomerular sclerosis (FSGS), IgA nephropathy (IgAN), and membranous nephropathy (MN). However, the expression and the potential roles of RANKL and RANK in diabetic nephropathy (DN) remain unclear. Irbesartan (Irb) has beneficial effects against diabetes-induced renal damage, but its mechanisms are poorly understood. Our present study investigated the effects of Irb in DN and whether the renal protective effects of Irb are mediated by RANKL/RANK and the downstream NF-κB pathway in db/db mice. Our results showed that db/db mice revealed severe metabolic abnormalities, renal dysfunction, podocyte injury, and increased MCP-1; these symptoms were reversed by Irb. At the molecular level, RANKL and RANK were overexpressed in the kidneys of db/db mice and Irb downregulated RANKL and RANK and inhibited the downstream NF-κB pathway. Our study suggests that Irb can ameliorate DN by suppressing the RANKL-RANK-NF-κB pathway.

Cyclopropanyldehydrocostunolide LJ attenuates high glucose-induced podocyte injury by suppressing RANKL/RANK-mediated NF-κB and MAPK signaling pathways.

AIMS: The aim of this research was to investigate the effects of cyclopropanyldehydrocostunolide (also named LJ), a derivative of sesquiterpene lactones (SLs), on high glucose (HG)-induced podocyte injury and the associated molecular mechanisms. METHODS: Differentiated mouse podocytes were incubated in different treatments. The migration and albumin filtration of podocytes were examined by Transwell filters. The protein and mRNA levels of MCP-1 were measured using enzyme-linked immunosorbent assay (ELISA) and quantitative real-time PCR (q-PCR). Protein expression and phosphorylation were detected by western blot, and the nuclear translocation of NF-κB was performed with a confocal microscope. The gene expression of the receptor activator for NF-κB (RANK) was silenced by small interfering RNA (siRNA). RESULTS: Our results showed that HG enhanced migration, albumin filtration and MCP-1 expression in podocytes. At the molecular level, HG promoted the phosphorylation of NF-κB/p65, IKKß, IκBα, mitogen-activated protein kinase (MAPK) and the nuclear translocation of p65. LJ reversed the effects of HG in a dose-dependent manner. Furthermore, our data provided the first demonstration that the receptor activator for NF-κB ligand (RANKL) and its cognate receptor RANK were overexpressed in HG-induced podocytes and were downregulated by LJ. RANK siRNA also attenuated HG-induced podocyte injury and markedly inhibited the activation of NF-κB and MAPK signaling pathways. CONCLUSIONS: LJ attenuates HG-induced podocyte injury by suppressing RANKL/RANK-mediated NF-κB and MAPK signaling pathways.

Metadherin facilitates podocyte apoptosis in diabetic nephropathy.

Apoptosis, one of the major causes of podocyte loss, has been reported to have a vital role in diabetic nephropathy (DN) pathogenesis, and understanding the mechanisms underlying the regulation of podocyte apoptosis is crucial. Metadherin (MTDH) is an important oncogene, which is overexpressed in most cancers and responsible for apoptosis, metastasis, and poor patient survival. Here we show that the expression levels of Mtdh and phosphorylated p38 mitogen-activated protein kinase (MAPK) are significantly increased, whereas those of the microRNA-30 family members (miR-30s) are considerably reduced in the glomeruli of DN rat model and in high glucose (HG)-induced conditionally immortalized mouse podocytes (MPC5). These levels are positively correlated with podocyte apoptosis rate. The inhibition of Mtdh expression, using small interfering RNA, but not Mtdh overexpression, was shown to inhibit HG-induced MPC5 apoptosis and p38 MAPK pathway, and Bax and cleaved caspase 3 expression. This was shown to be similar to the effects of p38 MAPK inhibitor (SB203580). Furthermore, luciferase assay results demonstrated that Mtdh represents the target of miR-30s. Transient transfection experiments, using miR-30 microRNA (miRNA) inhibitors, led to the increase in Mtdh expression and induced the apoptosis of MPC5, whereas the treatment with miR-30 miRNA mimics led to the reduction in Mtdh expression and apoptosis of HG-induced MPC5 cells in comparison with their respective controls. Our results demonstrate that Mtdh is a potent modulator of podocyte apoptosis, and that it represents the target of miR-30 miRNAs, facilitating podocyte apoptosis through the activation of HG-induced p38 MAPK-dependent pathway.

[Effect of nitrotyrosine on renal expressions of NF-κB, MCP-1 and TGF-ß1 in rats with diabetic nephropathy].

OBJECTIVE: To observe the effect of nitrotyrosine on renal expressions of nuclear factor-κB (NF-κB), monocyte chemoattractant protein-1 (MCP-1), and transforming growth factor-ß1 (TGF-ß1) in rats with diabetic nephropathy (DN). METHODS: Rat DN models established by a single intraperitoneal injection of streptozotocin (STZ) were randomly allocated into model group, nitrotyrosine group and ebselen group, with untreated rats as the normal control group. The rats were given the corresponding drugs for 8 weeks, and after the last administration, the 24-h urinary protein level was measured and the kidneys of the rats were harvested for detecting the protein and mRNA expressions of NF-κB, MCP-1 and TGF-ß1 with immunohistochemistry and RT-PCR, respectively. The pathological changes of the kidneys were assessed microscopically. RESULTS: Compared with those in the model group, the 24-h urinary protein level and expressions of NF-κB, MCP-1 and TGF-ß1 mRNA and protein in the renal tissues were significantly increased by nitrotyrosine treatment, which also caused worsened renal pathology, while treatment with ebselen significantly ameliorated these changes. CONCLUSION: Nitrotyrosine can up-regulate the mRNA and protein expressions of NF-κB, MCP-1 and TGF-ß1 and aggravate the inflammatory reaction in the renal tissue of DN rats to promote the progression of DN.

[Effects of Shenkangwan on renal expressions of angiotensin II and its type I receptor in rats with early diabetic nephropathy].

OBJECTIVE: To investigate the effects of Shenkangwan on the expressions of angiotensin II (AngII) and its type I receptor (AT(1)R) and the renalprotection mechanism of Shenkangwan in rats with early diabetic nephropathy (DN). METHODS: The rat models of DN established by a single injection of streptozotocin were randomly divided into 4 groups, namely the model group, Shenkangwan treatment group, irbesartan treatment group, and Shenkangwan and irbesartan treatment group, with normal rats as the control. All the rats received daily gavage for 8 weeks. The urinary protein quality in 24 h and plasma and renal contents of AngII were measured. The expressions of AT1R at the protein and mRNA levels in the kidney tissues were measured by immunohistochemistry and reverse transcription-polymerase chain reaction, respectively. The pathological changes of the kidney were observed microscopically. RESULTS: In DN rats, Shenkangwan reduced the urinary protein quantity in 24 h and the contents of AngII in the plasma and kidney tissues, decreased the renal expressions of AT(1)R protein and mRNA, and alleviated the morphological damage of the kidney. CONCLUSIONS: Shenkangwan offers renalprotection against DN probably by reducing the contents of AngII in the plasma and kidney tissues and inhibiting renal AT(1)R expressions.

[Effects of angiotensin II receptor antagonist on rat podocyte injury in early diabetic nephropathy].

OBJECTIVE: To investigate nephrin and desmin expression in rat podocytes in early diabetic nephropathy (DN) and the rale of angiotensin II receptor antagonist in renal protection. METHODS: Rat models of DN established by a injection of a single dose of streptozotocin (STZ) were randomized into model group and irbesartan group, with rats without STZ injection as the normal control group. The rats in irbesartan group were subjected to daily intragastric irbesartan administration for 8 consecutive weeks, while those in the model group received only saline in the same manner. Upon completion of the treatment, the rats were sacrificed and pathological changes of the kidney were examined with optical and transmission electron microscope. Nephrin and desmin expressions in the podocytes were detected by immunohistochemistry. RESULTS: In rats with DN, irbesartan administration alleviated podocyte injury and significantly lowered the expression of nephrin and desmin (P<0.05). CONCLUSION: Angiotensin II receptor antagonist may offer renal protection against DN by alleviating structural and functional podocyte damage through decreasing nephrin expression in the podocytes.