Selenium binding protein 1 protects renal tubular epithelial cells from ferroptosis by upregulating glutathione peroxidase 4.

Ferroptosis is a form of programmed cell death involved in various types of acute kidney injury (AKI). It is characterized by inactivation of the selenoprotein, glutathione peroxidase 4 (GPX4), and upregulation of acyl-CoA synthetase long-chain family member 4 (ACSL4). Since urinary selenium binding protein 1 (SBP1/SELENBP1) is a potential biomarker for AKI, this study investigated whether SBP1 plays a role in AKI. First, we showed that SBP1 is expressed in proximal tubular cells in normal human kidney, but is significant downregulated in cases of AKI in association with reduced GPX4 expression and increased ACSL4 expression. In mouse renal ischemia-reperfusion injury (I/R), the rapid downregulation of SBP1 protein levels preceded downregulation of GPX4 and the onset of necrosis. In vitro, hypoxia/reoxygenation (H/R) stimulation in human proximal tubular epithelial (HK-2) cells induced ferroptotic cell death in associated with an acute reduction in SBP1 and GPX4 expression, and increased oxidative stress. Knockdown of SBP1 reduced GPX4 expression and increased the susceptibility of HK-2 cells to H/R-induced cell death, whereas overexpression of SBP1 reduced oxidative stress, maintained GPX4 expression, reduced mitochondrial damage, and reduced H/R-induced cell death. Finally, selenium deficiency reduced GPX4 expression and promoted H/R-induced cell death, whereas addition of selenium was protective against H/R-induced oxidative stress. In conclusion, SBP1 plays a functional role in hypoxia-induced tubular cell death. Enhancing SBP1 expression is a potential therapeutic approach for the treatment of AKI.

Tea polyphenols may attenuate the neurocognitive impairment caused by global cerebral ischemia/reperfusion injury via anti-apoptosis.

BACKGROUND/AIMS: Global cerebral ischemia/reperfusion (GCIR) may incur neurocognitive impairment. Tea polyphenols (TP) have strong anti-oxidant capacity. This study planned to investigate the protective effect of TP against the neurocognitive impairment caused by GCIR and its mechanism. METHODS: One-stage anterior approach for cerebral four-vessel occlusion (4VO) was used to construct the GCIR model. Sprague Dawley rats were randomly classified into Sham group, GCIR group, and TP group (n = 50 per group). Besides receiving the same 4VO, the rats in TP group were treated with TP (6.4%) injection from the tail vein 30 minutes before cerebral ischemia. Morris water-maze test was used to evaluate the changes in space recognition and memory and open field activity test to assess the activity and motor function of rats. The cell apoptotic study in hippocampal CA1 region at specified time points (12, 24, 48, and 72 hours after surgery) was carried out by the flow cytometry, histology (hematoxylin and eosin staining), and immunohistochemical (terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling staining) examinations. One-way analysis of variance and least significant difference t-test were used and statistical significance considered at P < 0.05. RESULTS: Compared with the GCIR group, the TP group was significantly attenuated in the impairment of space recognition and memory caused by GCIR and so was the neuronal apoptosis in the hippocampal CA1 region (P < 0.05). CONCLUSION: TP may attenuate the impairment of space recognition and memory caused by GCIR via anti-apoptosis.

Artemisinin ameliorated proteinuria in rats with adriamycin-induced nephropathy through regulating nephrin and podocin expressions.

OBJECTIVE: To investigate the effects of artemisinin against proteinuria and glomerular filtration barrier damage in rats with adriamycin-induced nephropathy, and the potential mechanism underpinned the action. METHODS: Forty adriamycin rats were randomly divided into two groups with the ratio of 1 : 3; the small-number group served as control group (n = 10), and the rats in the large-number group were treated with adriamycin to induce nephropathy; then they were further randomly assigned into 3 subgroups: benazepril group (n = 10), artemisinin group (n = 10), and adriamycin group (n = 10). The benazepril group and artemisinin group were treated with benazepril suspl (5.0 mg/kg daily) and artemisinin suspl (150 mg/kg daily) respectively after being modeled; those in the control group and adriamycin group were intragastrically administered an equivalent volume of distilled water every day. The treatment after model establishment lasted for a total of 4 weeks. The 24 h uric protein, blood biochemicals, renal pathological changes, renal ultrastrutural changes, Nephrin and Podocin proteins and gene expressions were measured by Coomassie brilliant blue assay, completely automatic biochemical analyzer, light microscope, electron microscopy, Western blot and reverse transcription polymerase chain reaction, respectively. RESULTS: The rats in adriamycin group showed a significant increase in 24 h uric protein excretion, serum total cholesterol (TC), triglyceride (TG), blood urea nitrogen (BUN), serum creatinine (Scr) and decrease in albumin (Alb) (P < 0.05 or P < 0.01). Compared with adriamycin group, artemisinin could reduce uric protein excretion, decrease the serum TC, TG elevation, increase the serum Alb level, up-regulate the expressions of Nephrin and Podocin (P < 0.05 or P < 0.01), but no statistical significance effects on the levels of BUN, Scr in artemisinin group (P > 0.05). The renal pathological and ultrastrutural observation indicate that artemisinin could attenuate the severity of foot process effacement and fusion in the nephropathic rats. CONCLUSION: Artemisinin might have an effect on the nephropathy in rats caused by adriamycin, which may be at least partly correlated with attenu- ation of the severity of foot process effacement and fusion, up-regulation of the expressions of Nephrin and Podocin in the glomeruli in the rats.

[Effect of Qufeng Tongluo Recipe on the expressions of connexin 36 protein and gene in rat mesangial cells].

OBJECTIVE: To determine the effect of Qufeng Tongluo Recipe (QFTLR) on the expressions of connexin 36 (Cx36) protein and gene in rat mesangial cells (MCs) and the proliferation of the MCs. METHODS: Serum samples containing Benazepril (Bena) and QFTLR were prepared in line with serum pharmacology methodology. The MCs cultured in vitro were divided into normal control and Lipopolysaccharide (LPS), Bena and QFTLR treated groups. The expressions of Cx36 protein and gene were detected by laser scanning confocal microscope (LSCM), Western blot, immunohistochemical assay and quantitative real time polymerase chain reaction (QRT-PCR) respectively. RESULTS: Compared with the control, higher level of Cx36 protein expression was found in the MCs than treated with LPS (P < 0.01). Both Bena and QFTLR lowered the level of Cx36 protein expression in the MCs treated with LPS significantly (P < 0.01 or P < 0.05). Similar results were found with the expression of Cx36 mRNA. CONCLUSION: QFTLR inhibits the proliferation of rat MCs, possibly through down-regulating the expressions of Cx36 protein and gene.

Qufeng Tongluo Prescription () inhibits mesangial cell proliferation and promotes apoptosis through regulating cell cycle progression.

OBJECTIVE: To study the effects and possible underlying mechanism of Qufeng Tongluo Prescription (, QFTL) on the regulation of mesangial cells (MCs) proliferation and apoptosis. METHODS: The MCs used in this experiment have undergone five passages induced by lipopolysaccharide (LPS). Changes in the proliferation, apoptosis, cell cycle regulatory proteins and mRNA expression levels of the MCs after administration of Benazepril or QFTL were measured by methyl thiazolyl tetrazolium (MTT) reduction assay, flow cytometry, Western blot and quantitative real-time polymerase chain reaction (qRT-PCR), respectively. RESULTS: The addition of Benazepril or QFTL serum inhibited LPS-induced MC proliferation after treatment for 24, 48 and 72 h, respectively (P<0.05 or P<0.01). Moreover, the inhibitory effect is more significant in the QFTL group at 48 h (P<0.05). Compared with the control group, LPS-induced cell proliferation decreased the number of cells in G1 phase versus cells in S and G2/M phases, while the addition of QFTL and Benazepril serum increased the ratio of cells at G1 phase (P<0.05 or P<0.01) to cells at S phase (P<0.01), implicating the cell cycle inhibition effect exerted by QFTL. LPS decreased the level of MC apoptosis, compared with the control group (P<0.05), while QFTL and Benazepril serum increased the level of MC apoptosis (P<0.01). Moreover, the difference between the QFTL group and the Benazepril group was statistically significant (P<0.01). Compared with the control group, the protein and mRNA expression levels of cylinD1, cyclin dependent kinase 2 (CDK2) and p21 were significantly increased (P<0.05 or P<0.01), p27 was decreased but with no statistical significance (P>0.05); After being treated with QFTL and Benazepril serum, the protein and mRNA expression levels of cylinD1, CDK2, p21 were decreased and p27 increased significantly (P<0.05 or P<0.01); Compared with the Benazepril group, QFTL show better effects on protein and mRNA expression levels of cylinD1, CDK2 (P<0.05 or P<0.01) and p21 protein expression (P<0.05). CONCLUSION: QFTL inhibits MCs proliferation, promotes MCs apoptosis through an underlying mechanism of down-regulating the protein and mRNA expression levels of cylinD1, CDK2, p21 and up-regulation of the expression level of p27.

An optimal dose of tea polyphenols protects against global cerebral ischemia/reperfusion injury.

Previous studies addressing the protection of tea polyphenols against cerebral ischemia/reperfusion injury often use focal cerebral ischemia models, and the optimal dose is not unified. In this experiment, a cerebral ischemia/reperfusion injury rat model was established using a modified four-vessel occlusion method. Rats were treated with different doses of tea polyphenols (25, 50, 100, 150, 200 mg/kg) via intraperitoneal injection. Results showed that after 2, 6, 12, 24, 48 and 72 hours of reperfusion, peroxide dismutase activity and total antioxidant capacity in brain tissue gradually increased, while malondialdehyde content gradually decreased after tea polyphenol intervention. Tea polyphenols at 200 mg/kg resulted in the most apparent changes. Terminal deoxynucleotidyl transferase-mediated nick end labeling and flow cytometry showed that 200 mg/kg tea polyphenols significantly reduced the number and percentage of apoptotic cells in the hippocampal CA1 region of rats after cerebral ischemia/reperfusion injury. The open field test and elevated plus maze experiments showed that tea polyphenols at 200 mg/kg strengthened exploratory behavior and reduced anxiety of cerebral ischemia/reperfusion injured rats. Experimental findings indicate that tea polyphenols protected rats against cerebral ischemia/reperfusion injury and 200 mg/kg is regarded as the optimal dose.

Uremic anorexia and gastrointestinal motility dysfunction correlate with the changes of ghrelin system in hypothalamus.

AIM: Ghrelin can act as a signal for meal initiation and play a role in the regulation of gastrointestinal (GI) motility via hypothalamic circuit. This study investigated the correlation between changes of hypothalamic ghrelin system and GI motility dysfunction and anorexia in rats with chronic renal failure (CRF). METHODS: Sprague-Dawley (SD) rats (male/female 1:1, 180 ± 20 g) were randomly classified into a CRF group and control group (n = 8 per group). 5/6 nephrectomy was used to construct the CRF model. When plasma creatinine concentration (PCr) and blood urea nitrogen (BUN) in the CRF group were twice higher than the normal, food intake (g/24 h) and gastrointestinal interdigestive myoelectric complex (IMC) were detected. Then all rats were killed for assessment of the mRNA expression of ghrelin and growth hormone secretagogue receptor (GHS-R) in hypothalamus using reverse transcription-polymerase chain reaction. Analysis of variance, Student-Newman-Keuls-q-test and Correlation Analysis were used to do statistical analysis. P < 0.05 was considered as statistically significant. RESULTS: Compared to the control group, the CRF group was obviously decreased in the food intake (g/24 h), the phase III duration and amplitude and the ghrelin and GHS-R expression in the hypothalamus (P < 0.05). There was a positive correlation between them (P < 0.05). CONCLUSION: Changes of ghrelin and GHS-R in the hypothalamus correlate with gastrointestinal motility dysfunction and anorexia in rats with CRF.

[Effects of Qufengtongluo Recipe on expressions of cell cycle regulatory proteins in rat mesangial cells].

OBJECTIVE: To observe the effects of Qufengtongluo Recipe (QFTLR) on the expressions of cell cycle regulatory proteins in rat mesangial cells (MCs) in vitro and investigate the mechanism by which QFTLR inhibits MC proliferation. METHODS: Using the methods of serum pharmacology, we studied the expressions of cell cycle regulatory proteins in rat MCs treated with QFTLR by laser scanning confocal microscope and immunohistochemistry. RESULTS: Compared with the normal control cells, the cells challenged with lipopolysaccharide (LPS) showed significantly enhanced expressions of cyclin D1, CDK2, and P21 (P<0.01) and obviously lowered protein expression of P27 (P<0.01). Treatment of the LPS-challenged cells with QFTLR and benazepril both resulted in significantly attenuated expressions of cyclin D1, CDK2, and P21 and obvious increase of P27 expression (P<0.05 or P<0.01), but QFTLR produced stronger effects than benazepril in regulating of cyclinD1, P21 and P27 protein expressions (P<0.05 or P<0.01). CONCLUSION: QFTLR inhibits rat MC proliferation in vitro possibly by down-regulating the cellular expressions of cyclin D1, CDK2, and P21 and up-regulating the expression of P27 protein.

Chronic renal failure impacts the expression of ghrelin and its receptor in hypothalamus and hippocampus.

BACKGROUND/AIMS: Ghrelin plays a central role in the regulation of gastrointestinal (GI) motility. This study aimed to investigate the expression of ghrelin and growth hormone secretagogue receptor (GHSR) in the central nervous system of rats with chronic renal failure (CRF). METHODS: Sprague-Dawley rats (male, 180 ± 20 g, n = 24) were treated by 5/6 nephrectomy to construct CRF model. As their plasma creatinine concentration and blood urea nitrogen were maintained more than double the normal level for 2 weeks, they were killed for assessing the expression of ghrelin and GHSR in hypothalamus and hippocampus using immunohistochemistry and real-time polymerase chain reaction (RT-PCR). The rats (male, 180 ± 20 g, n = 24) treated by Sham operation served as a control. One-way analysis of variance and Student-Newman-Keuls q test were used to analyze group difference and a p-value of <0.05 was considered as statistically significant. RESULTS: Compared with the controls, the ghrelin and GHSR expression was obviously increased in the hippocampus (p < 0.05) but decreased in the hypothalamus of rats with CRF (p < 0.05). CONCLUSIONS: CRF was found to impact the expression of ghrelin and GHSR in hypothalamus and hippocampus. This might be associated with the CRF-induced GI motility dysfunction.

[Expression of ghrelin and its receptor GHS-R in the hypothalamus and gastrointestinal tract in rats with chronic renal failure].

OBJECTIVE: To investigate the expression of ghrelin and its receptor, growth hormone secretagogue receptor (GHS-R), in the hypothalamus and gastrointestinal tract in rats with chronic renal failure (CRF) and explore their relationship with the disorder of gastrointestinal tract motility. METHODS: SD rats were randomly divided into sham-operated group (n=8) and CRF group (n=16), and in the latter group, the rats were subjected to 5/6 nephrectomy to induce CRF. Real-time PCR and immunohistochemical staining were used to detect the distribution of mRNA and protein of ghrelin and GHS-R in the gastric fundus, duodenum, and hypothalamus. RESULTS: The rats in the CRF group showed a significantly higher expression of ghrelin mRNA and protein in the gastric fundus but a lower expression in the hypothalamus than those in the sham-operated group (P<0.01), but the expression in the duodenum was similar between the two groups (P>0.05). The expression of GHS-R mRNA and protein in the gastric fundus was significantly higher in the CRF group than in the sham-operated group (P<0.01), while in the hypothalamus and duodenum, the expression was significantly lower in the CRF group (P<0.01). CONCLUSION: The different distribution patterns of ghrelin and GHS-R in the tissues may be an important pathological basis of gastrointestinal motility disorder in CRF.