Diabetes aggravates renal ischemia-reperfusion injury by repressing mitochondrial function and PINK1/Parkin-mediated mitophagy.

Diabetes could aggravate ischemia-reperfusion (I/R) injury, but the underlying mechanism is unclear. In the present study, we aimed to investigate whether diabetes exacerbates renal I/R injury and its possible mechanism. In vitro, HK-2 cells under normal or high glucose conditions were subjected to hypoxia (12 h) followed by reoxygenation (3 h) (H/R). Cell viability, intracellular ATP content, mitochondrial membrane potential, reactive oxygen species production, and apoptosis were measured. In vivo, streptozotocin-induced diabetic and nondiabetic rats were subjected to I/R. Renal pathology, function, and apoptosis were evaluated by hematoxylin and eosin staining, transmission electron microscopy, and Western blot analysis. Compared with the normal glucose + H/R group, mitochondrial function (ATP, mitochondrial membrane potential, and reactive oxygen species) and mitophagy were reduced in the high glucose + H/R group, as was expression of phosphatase and tensin homolog-induced putative kinase 1 (PINK1) and Parkin. Also, cells in the high glucose + H/R group exhibited more apoptosis compared with the normal glucose + H/R group, as assessed by flow cytometry, TUNEL staining, and Western blot analysis. Compared with normal rats that underwent I/R, diabetic rats that underwent I/R exhibited more severe tubular damage and renal dysfunction as well as expression of the apoptotic protein caspase-3. Meanwhile, diabetes alleviated mitophagy-associated protein expression in rats subjected to I/R, including expression of PINK1 and Parkin. Transmission electron microscopy indicated that the mitophagosome could be hardly observed and that mitochondrial morphology and structure were obviously damaged in the diabetes + I/R group. In conclusion, our results, for the first time, indicate that diabetes could aggravate I/R injury by repressing mitochondrial function and PINK1/Parkin-mediated mitophagy in vivo and in vitro.

Diabetes aggravates renal ischemia and reperfusion injury in rats by exacerbating oxidative stress, inflammation, and apoptosis.

Diabetic patients are more susceptible to renal ischemia/reperfusion (I/R) injury (RI/RI) and have a poor prognosis, but the underlying mechanism remains unclear. The present study aimed to examine whether diabetes could worsen acute kidney injury induced by I/R in rats and clarify its mechanism. Control and streptozotocin-induced diabetic rats were subjected to 45 min renal pedicle occlusion followed by 24 h reperfusion. Tert-butylhydroquinone (TBHQ, 16.7 mg/kg) was administrated intraperitoneally 3 times at intervals of 8 h before ischemia. Serum and kidneys were harvested after reperfusion to evaluate renal function and histological injury. Enzyme-linked immunosorbent assays were used to test pro-inflammatory cytokines. Terminal deoxynucleotidyl-transferase-mediated dUTP nick-end labeling assays were used to detect apoptotic cells, and western blotting was performed to determine the expression of B-cell lymphoma-2 (Bcl-2), Bcl-2-associated X protein (Bax), and cleaved caspase-3, as well as oxidative stress and inflammation-related proteins, such as nuclear factor-erythroid 2-related factor 2 (Nrf2), heme oxygenase-1 (HO-1), Toll-like receptor 4 (TLR4), and nuclear factor-κB (NF-κB). Compared with control animals, diabetic rats undergoing I/R exhibited more severe tubular damage and renal dysfunction. Diabetes exacerbated oxidative stress, the inflammatory response, and apoptosis after renal I/R by enhancing TLR4/NF-κB signaling and blocking the Nrf2/HO-1 pathway. RI/RI in diabetic rats was attenuated by pretreatment with TBHQ (a Nrf2 agonist), which exerted anti-inflammatory and anti-apoptotic properties by inhibiting NF-κB signaling. These findings indicate that hyperglycemia exacerbates RI/RI by intensifying oxidative stress, inflammation, and apoptosis. Antioxidant pretreatment may alleviate RI/RI in diabetic patients.

Aortic cell apoptosis in rat primary aldosteronism model.

This study aimed to determine whether aldosterone could induce vascular cell apoptosis in vivo. Thirty-two male rats were randomly divided into 4 groups: vehicle (control), aldosterone, aldosterone plus eplerenone or hydralazine. They were then implanted with an osmotic mini-pump that infused either aldosterone or the vehicle. Systolic blood pressure (SBP) was measured weekly by the tail-cuff method. After 8 weeks, plasma aldosterone concentration (PAC) and renin activity (PRA) were determined by radioimmunoassay. Aortic apoptosis was examined by TUNEL assay. The levels of cytochrome c and caspase-3 were determined by Western blotting and the expression of Bax and Bcl-2 was detected by immunohistochemistry and Western blotting. The results showed that as compared with control group, aldosterone-infused rats exhibited: (1) an increase in SBP; (2) significantly elevated PAC with depressed PRA; (3) elevated aortic vascular cell apoptosis accompanied with higher levels of cytochrome c and activated caspase-3; and (4) significantly up-regulated Bax protein with down-regulated Bcl-2. These effects of aldosterone were significantly inhibited after co-administration with eplerenone but not with hydralazine. It was concluded that aldosterone induced vascular cell apoptosis by its direct effect on the aorta via mineralocorticoid receptors and independently of blood pressure, which may contribute to aldosterone-mediated vascular injury.

Inhibition of the SIRT1 signaling pathway exacerbates endoplasmic reticulum stress induced by renal ischemia/reperfusion injury in type 1 diabetic rats.

The aim of the present study was to investigate whether the diabetic kidney is more susceptible to ischemia/reperfusion (I/R) injury, and identify the potential mechanisms involved. An animal model of type 1 diabetes was created by treating rats with streptozotocin (STZ). This model was then used, along with healthy controls, to investigate the effect of diabetes mellitus (DM) on renal I/R injury. After 45 min of ischemia and 24 h of reperfusion, kidney and serum samples were acquired and used to evaluate function and histopathological injury in the kidneys. Western blotting was also used to determine the expression levels of key proteins. Rats experiencing renal I/R exhibited significant characteristics of renal dysfunction, reduced levels of Sirtuin 1 (SIRT1) protein (a key signaling protein in the kidneys), increased endoplasmic reticulum stress (ERS) and pyroptosis. Furthermore, diabetic rats exhibited further reductions in the levels of SIRT1 in response to renal I/R injury and an increase in the levels of ERS. These effects were all alleviated by the administration of a SIRT1 agonist. The present analysis revealed that the SIRT1­mediated activation of ER stress and pyroptosis played a pivotal role in diabetic rats subjected to renal I/R injury. Downregulation of the SIRT1 signaling pathway were exacerbated in response to renal I/R injury­induced acute kidney injury (AKI). The present data indicated that DM enhanced ER stress and increased pyroptosis by downregulating the SIRT1 signaling pathway.

Fibulin-5 is down-regulated in urothelial carcinoma of bladder and inhibits growth and invasion of human bladder cancer cell line 5637.

PURPOSE: The expression of fibulin-5 was investigated in urothelial carcinomas of bladder and in normal bladder samples. The effects of fibulin-5 on cell proliferation, motility, and invasion were further explored in bladder cancer cell line 5637. MATERIALS AND METHODS: The expression of fibulin-5 in 20 bladder carcinoma samples and 7 normal bladder samples were detected by Western blot. Fibuin-5 cDNA was cloned into p-EGFP-N1 vector and transfected into bladder cancer cell line 5637. Growth curves were estimated by the 3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyl-tetrazolium bromide assay and cell number count. The migration and invasion of the transfected cells and the control cells were measured by Boyden chamber assay. RESULTS: Compared with 1.16 ± 0.28 in the normal control, the mean ± SD expression of fibulin-5 in low grade tumors and high grade tumors were 0.57 ± 0.32 and 0.44 ± 0.42 (P = 0.002 and P = 0.018, respectively), while the expression in Ta-T1 tumors and T2+ tumors were 0.55 ± 0.31 and 0.49 ± 0.43 (P = 0.002 and P = 0.015, respectively). The differences between low grade and high grade tumors or Ta-T1 and T2+ tumors were not statistically significant (P = 0.362 and P = 0.589, respectively). The growth rate of the fibulin-5 transfected GFP-F5 cells was remarkably reduced than that of the untransfected cells or the empty vector transfected GFP-t cells. Besides, compared with control cells, the GFP-F5 cells showed significant inhibition of cell invasion with slight inhibition of cell migration. CONCLUSIONS: Fibulin-5 is down-regulated in urothelial carcinoma of bladder and acts as a tumor suppressor gene by inhibiting proliferation and invasion of bladder cancer cells.

A radially expanding sheath for urethral dilation.

Urethral trauma caused by urethral dilation often leads to complications including gross hemorrhage and inflammation. The injury of the urethral mucosa is, in a large part, due to the shearing forces imposed on it during the introduction of dilation devices. In this article, a radially expanding sheath for urethral dilation is hypothesized by the authors. This device aims to reduce the axial forces during the insertion of dilators, thereby protecting the urethral mucosa from friction. When performing the endoscopy, the device could act as a barrier between urethral mucosa and the endoscope. Moreover, in the situation of encountering difficulties in catheterization, the sheath could also be used as a guide-wire to lead the catheter through its lumen course. Thus, it is proposed that this radially expanding sheath could be a potential powerful approach for reducing the risks and complications of urethral dilation.