Guangyuan Zhang

Antithrombin III/SerpinC1 insufficiency exacerbates renal ischemia/reperfusion injury

Antithrombin III, encoded by SerpinC1, is a major anti-coagulation molecule in vivo and has anti-inflammatory effects. We found that patients with low antithrombin III activities presented a higher risk of developing acute kidney injury after cardiac surgery. To study this further, we generated SerpinC1 heterozygous knockout rats and followed the development of acute kidney injury in a model of modest renal ischemia/reperfusion injury. Renal injury, assessed by serum creatinine and renal tubular injury scores after 24 h of reperfusion, was significantly exacerbated in SerpinC1+/− rats compared to wild-type littermates. Concomitantly, renal oxidative stress, tubular apoptosis, and macrophage infiltration following this injury were significantly aggravated in SerpinC1+/− rats. However, significant thrombosis was not found in the kidneys of any group of rats. Antithrombin III is reported to stimulate the production of prostaglandin I2, a known regulator of renal cortical blood flow, in addition to having anti-inflammatory effects and to protect against renal failure. Prostaglandin F1α, an assayable metabolite of prostaglandin I2, was increased in the kidneys of the wild-type rats at 3 h after reperfusion. The increase of prostaglandin F1α was significantly blunted in SerpinC1+/− rats, which preceded increased tubular injury and oxidative stress. Thus, our study found a novel role of SerpinC1 insufficiency in increasing the severity of renal ischemia/reperfusion injury.

Limb ischemic preconditioning protects against contrast-induced nephropathy via renalase

Clinical trials shows that remote ischemic preconditioning (IPC) can protect against contrast induced nephropathy (CIN) in risky patients, however, the exact mechanism is unclear. In this study, we explored whether renalase, an amine oxidase that has been previously shown to mediate reno-protection by local IPC, would also mediate the same effect elicited by remote IPC in animal model. Limb IPC was performed for 24 h followed by induction of CIN. Our results indicated that limb IPC prevented renal function decline, attenuated tubular damage and reduced oxidative stress and inflammation in the kidney. All those beneficial effects were abolished by silencing of renalase with siRNA. This suggests that similar to local IPC, renalase is also critically involved in limb IPC-elicited reno-protection. Mechanistic studies showed that limb IPC increased TNFα levels in the muscle and blood, and up-regulated renalase and phosphorylated IκBα expression in the kidney. Pretreatment with TNFα antagonist or NF-κB inhibitor, largely blocked renalase expression. Besides, TNFα preconditioning increased expression of renal renalase in vivo and in vitro, and attenuated H2O2 induced apoptosis in renal tubular cells. Collectively, our results suggest that limb IPC-induced reno-protection in CIN is dependent on increased renalase expression via activation of the TNFα/NF-κB pathway.

miR‐29 contributes to normal endothelial function and can restore it in cardiometabolic disorders

We investigated the role of microRNAs (miRNA) in endothelial dysfunction in the setting of cardiometabolic disorders represented by type 2 diabetes mellitus (T2DM). miR‐29 was dysregulated in resistance arterioles obtained by biopsy in T2DM patients. Intraluminal delivery of miR‐29a‐3p or miR‐29b‐3p mimics restored normal endothelium‐dependent vasodilation (EDVD) in T2DM arterioles that otherwise exhibited impaired EDVD. Intraluminal delivery of anti‐miR‐29b‐3p in arterioles from non‐DM human subjects or rats or targeted mutation of Mir29b‐1/a gene in rats led to impaired EDVD and exacerbation of hypertension in the rats. miR‐29b‐3p mimic increased, while anti‐miR‐29b‐3p or Mir29b‐1/a gene mutation decreased, nitric oxide levels in arterioles. The mutation of Mir29b‐1/a gene led to preferential differential expression of genes related to nitric oxide including Lypla1. Lypla1 was a direct target of miR‐29 and could abrogate the effect of miR‐29 in promoting nitric oxide production. Treatment with Lypla1 siRNA improved EDVD in arterioles obtained from T2DM patients or Mir29b‐1/a mutant rats or treated with anti‐miR‐29b‐3p. These findings indicate miR‐29 is required for normal endothelial function in humans and animal models and has therapeutic potential for cardiometabolic disorders.

Sulodexide Protects Contrast-Induced Nephropathy in Sprague-Dawley Rats.

Background: Sulodexide is a powerful antithrombin agent with reno-protective property. However, whether it has beneficial effects on Contrast-Induced Nephropathy (CIN) remained elusive. In the current study, we evaluated the therapeutic effects of Sulodexide on CIN and investigated the potential mechanisms. Methods: CIN model was induced by intravenous injection of indomethacin, followed by Ioversol and L-NAME. Sprague-Dawley rats were divided into 4 groups: control group, CIN group, CIN+vehicle group (CIN rats pretreated with vehicle) and CIN+ Sulodexide (CIN rats pretreated with Sulodexide). Sulodexide or an equivalent volume of vehicle was intravenously delivered 30 min before the induction of CIN. All the animals were sacrificed at 24h after CIN and tissues were harvested to evaluate renal injury, kidney oxidative stress and apoptosis levels. Plasma antithrombin III (ATIII) activities were also measured. Results: Compared to the untreated CIN group, improved renal function, reduced tubular injury, decreased levels of oxidative stress and apoptosis were observed in CIN rats receiving Sulodexide injection. In addition, we also found that ATIII activity was significantly higher in Sulodexide-administered group than that in vehicle-injected CIN rats. For in vitro studies, HK2 cells were exposed to Ioversol and the cyto-protective effects of Sulodexide were also determined. Sulodexide pretreatment protected HK2 cells against the cytotoxicity of Ioversol via inhibiting caspase-3 activity. Preincubation with Sulodexide could also attenuate H2O2-induced increases in ROS, apoptosis and caspase-3 levels. Conclusions: Taken together, Sulodexide could protect against CIN through activating ATIII, and inhibiting oxidative stress, inflammation and apoptosis.

Sulodexide pretreatment attenuates renal ischemia-reperfusion injury in rats

Sulodexide is a potent antithrombin agent, however, whether it has beneficial effects on renal ischemia-reperfusion injury (IRI) remains unknown. In the present study, we assessed the therapeutic effects of sulodexide in renal IRI and tried to investigate the potential mechanism. One dose of sulodexide was injected intravenously in Sprague-Dawley rats 30 min before bilateral kidney ischemia for 45 min. The animals were sacrificed at 3h and 24h respectively. Our results showed that sulodexide pretreatment improved renal dysfunction and alleviated tubular pathological injury at 24h after reperfusion, which was accompanied with inhibition of oxidative stress, inflammation and cell apoptosis. Moreover, we noticed that antithrombin III (ATIII) was activated at 3h after reperfusion, which preceded the alleviation of renal injury. For in vitro study, hypoxia/reoxygenation (H/R) injury model for HK2 cells was carried out and apoptosis and reactive oxygen species (ROS) levels were evaluated after sulodexide pretreatment. Consistently, sulodexide pretreatment could reduce apoptosis and ROS level in HK2 cells under H/R injury. Taken together, sulodexide pretreatment might attenuate renal IRI through inhibition of inflammation, oxidative stress and apoptosis, and activation of ATIII.

Antithrombin III Protects Against Contrast-Induced Nephropathy

We previously reported that insufficiency of antithrombin III (ATIII), the major anti-coagulation molecule in vivo, exacerbated renal ischemia-reperfusion injury in animal models and possibly humans. In the present study, we investigated the relationship between ATIII level and contrast induced nephropathy (CIN) in patients and examined therapeutic effect of ATIII on CIN in Sprague-Dawley rats. Patients with low ATIII activity presented a higher incidence of acute kidney injury (AKI) following coronary angiography. ATIII (500 μg/kg) was intravenously injected before or after the induction of AKI in rats. Our data demonstrated ATIII significantly attenuated the elevation of serum creatinine, blood urea nitrogen, and renal histological injury. The beneficial effects of ATIII were accompanied by diminished renal inflammatory response, oxidative stress, cell apoptosis and improved renal blood flow in rats. In conclusion, ATIII appears to attenuate CIN through inhibiting inflammation, oxidative stress, apoptosis and improving renal blood flow. ATIII administration may represent a promising strategy for the prevention and treatment of contrast-induced AKI.

Underestimated incidence of kidney disease in nonrenal outpatient

Abstract Background and aims: Chronic kidney disease (CKD) has been regarded as a severe threaten to public health, a large percentage of CKD are secondary to other diseases. Serum creatinine is the most common marker of renal function, but it did not always reflect glomerular filtration rate (GFR) accurately. In order to investigate the prevalence of kidney disease in non-renal departments and to provide a basis for the prevention of kidney injury, the present study was conducted in several medical centers. Methods: A total of 17,462 outpatients were selected randomly from the departments of cardiology, endocrinology, and neurology in 16 hospitals and the incidence of kidney disease was screened. Estimated GFR (eGFR) was calculated by using MDRD-formula. Results: There are 5293 (30.1%) patients’ eGFR above 90 mL/min/1.73m2 among all the subjects in non-renal departments, and 4055(23%) patients’ eGFR lower than 60 mL/min/1.73 m2 including 80 patients whose eGFR were below 15 mL/min/1.73 m2. Furthermore, among 16616 subjects who have a normal SCr level, there are 3209 respondents’ eGFR lower than 60 mL/min/1.73 m2. Moreover, individuals with hypertension or diabetes had a high prevalence of decreased renal function. Conclusions: This survey indicated kidney injury wildly existed in non-renal outpatients, and the incidence of CKD is underestimated.

Antithrombin III prevents progression of chronic kidney disease following experimental ischaemic‐reperfusion injury

Acute kidney disease (AKI) leads to increased risk of progression to chronic kidney disease (CKD). Antithrombin III (ATIII) is a potent anticoagulant with anti‐inflammatory properties, and we previously reported that insufficiencies of ATIII exacerbated renal ischaemia‐reperfusion injury (IRI) in rats. In this study, we examined the characteristic of AKI‐CKD transition in rats with two distinct AKI models. Based on our observation, left IRI plus right nephrectomy (NX‐IRI) was used to determine whether ATIII had therapeutic effects in preventing CKD progression after AKI. It was observed that NX‐IRI resulted in significant functional and histological damage at 5 weeks after NX‐IRI compared with sham rats, which was mitigated by ATIII administration. Besides, we noticed that ATIII administration significantly reduced NX‐IRI‐induced interstitial fibrosis. Consistently, renal expression of collagen‐1, α‐smooth muscle actin and fibronectin were substantial diminished in ATIII‐administered rats compared with un‐treated NX‐IRI rats. Furthermore, the beneficial effects of ATIII were accompanied with decreased M1‐like macrophage recruitment and down‐regulation of M1‐like macrophage‐dependent pro‐inflammatory cytokines such as tumour necrosis factor α, inducible nitric oxide synthase and interleukin‐1β, indicating that ATIII prevented AKI‐CKD transition via inhibiting inflammation. Overall, ATIII shows potential as a therapeutic strategy for the prevention of CKD progression after AKI.

Tanshinone IIA Attenuates Contrast-Induced Nephropathy via Nrf2 Activation in Rats

Background/Aims: Tanshinone IIA is a chemical compound extracted from Salvia miltiorrhiza Bunge, a perennial plant also known as red sage used in traditional Chinese medicine. Tanshinone IIA has been shown to protect against various organ injuries. In this study, we hypothesized that Tanshinone IIA could play an anti-oxidative role in contrast-induced nephropathy (CIN) through enhancing Nrf2/ARE activation. Methods: To test whether Tanshinone IIA can attenuate CIN, oxidative stress, and apoptosis, we utilized two models: an in vivo Sprague-Dawley rat model of ioversol-induced CIN and an in vitro cell model of oxidative stress in which HK2 cells, a human renal tubular cell line, are treated with hydrogen peroxide (H2O2). Rats were randomly assigned to 4 groups (n = 6 per group): control group, ioversol group (ioversol-induced CIN), vehicle group (ioversol-induced CIN rats pretreated with vehicle), and Tanshinone IIA group (ioversol-induced CIN rats pretreated with 25mg/kg Tanshinone IIA). Renal functions, renal injuries and apoptosis were evaluated by using serum creatinine, histological scoring, and TUNEL staning respectively. Malondialdehyde, 8-hydroxy-2’ –deoxyguanosine, and intracellular reactive oxygen species were used for oxidative stress assessment. Levels of Nrf2 and heme oxygenase-1 (HO-1) were measured in vivo and in vitro. Results: Tanshinone IIA attenuated renal tubular necrosis, apoptosis and oxidative stress in rats and oxidative stress in HK2 cells. Furthermore, Tanshinone IIA activated Nrf2, and up-regulated HO-1 expression in vivo and in vitro, resulting in a reduction in oxidative stress. Conclusion: Tanshinone IIA may protect against CIN through enhancing Nrf2/ARE activation.

Tissue-specific effects of targeted mutation of Mir29b1 in rats

Background miR-29 is a master regulator of extracellular matrix genes, but conflicting data on its anti-fibrotic effect have been reported. miR-29 improves nitric oxide (NO) production in arterioles by targeting Lypla1. Mir29b1 targeted mutation exacerbates hypertension in a model derived from the Dahl salt-sensitive rat. We examined the effect of Mir29b1 mutation on tissue fibrosis and NO levels with a focus on kidney regions. Methods Mir29b1 targeted mutant rats on the genetic background of SS-Chr13BN rats were studied. Masson trichrome staining, molecular and biochemical assays, metabolic cage studies, and bioinformatic analysis of human genomic data were performed. Findings The abundance of miR-29b and the co-transcribed miR-29a was substantially lower in mutant rats. Tissue fibrosis was significantly increased in the renal outer medulla, but not in the renal cortex, heart or liver in mutant rats on a 0.4% NaCl diet. Lypla1 protein abundance was significantly higher and NO levels lower in the renal outer medulla, but not in the renal cortex. After 14 days of a 4% NaCl diet, 24 h urine volume and urinary sodium excretion was significantly lower in mutant rats, and tissue fibrosis became higher in the heart. NO levels were lower in the renal outer medulla and heart, but not in the renal cortex. Human miR-29 genes are located in proximity with blood pressure-associated single nucleotide polymorphisms. Interpretation The renal outer medulla might be particularly susceptible to the injurious effects of a miR-29 insufficiency, which might contribute to the development of hypertension in Mir29b1 mutant rats.