Intravascular radiocontrast iodixanol increases permeability of proximal tubule epithelium: a possible mechanism of contrast-induced nephropathy

Zinc Preconditioning Provides Cytoprotection following Iodinated Contrast Media Exposure in In Vitro Models

Methods

Normal human proximal renal kidney cells (HK-2) were preconditioned with either increasing doses of ZnCl₂ or control. Following this preconditioning, cells were exposed to increasing concentrations of Iohexol 300 mg I₂/ml for four hours. Key outcome measures included cell survival (MTT colorimetric assay) and ROS generation (H₂DCFDA fluorescence assay).

Results

Contrast media induced a dose-dependent reduction in survival of HK-2 cells. Compared to control, contrast media at 150, 225, and 300 mg I₂/ml resulted in 69.5% (SD 8.8%), 37.3% (SD 4.8%), and 4.8% (SD 6.6%) cell survival, respectively (p < 0.001). Preconditioning with 37.5 μM and 50 μM ZnCl₂ increased cell survival by 173% (SD 27.8%) (p < 0.001) and 219% (SD 32.2%) (p < 0.001), respectively, compared to control preconditioning. Zinc preconditioning resulted in a reduction of ROS generation. Zinc pre-conditioning with 37.5 μM μM ZnCl₂ reduced ROS generation by 46% (p < 0.001) compared to control pre-conditioning.

Conclusions

Zinc preconditioning reduces oxidative stress following exposure to radiographic contrast media which in turn results in increased survival of renal cells. Translation of this in vitro finding in animal models will lay the foundation for future use of zinc preconditioning against contrast induced nephropathy.

Coenzyme Q10 combined with trimetazidine in the prevention of contrast-induced nephropathy in patients with coronary heart disease complicated with renal dysfunction undergoing elective cardiac catheterization: a randomized control study and in vivo study

Background

Contrast-induced nephropathy (CIN) is one of the common hospital-acquired acute renal failures. The purpose of this study was to investigate whether Coenzyme Q10 (CoQ10) and trimetazidine (TMZ) can prevent the occurrence of CIN after elective cardiac catheterization in patients with coronary artery disease complicated with renal dysfunction.

Methods

Consecutive coronary artery disease patients with renal insufficiency scheduled for coronary angiography were enrolled in randomized, paralleled, double-blind, controlled trial. The development of CIN was occurrence at the 48 or 72 h after the procedure. The changes of serum creatinine (SCr), eGFR, and Cys-C within 72 h after the procedure were measured and compared. In vivo contrast medium (CM)-induced acute kidney injury (AKI) animal model was established, and CoQ10 plus TMZ was orally administrated to evaluate its renal protective effect.

Results

150 patients with renal insufficiency were enrolled finally. CIN occurred in 21 (14.00%) of the 150 patients. 72 h after the procedure, the incidence of CIN was significantly lower in CoQ10 plus TMZ group compared with control group (6.67 vs. 21.3%, p = 0.01). No cardiac death occurred in this study. No side effects were observed after administration of CoQ10 and TMZ. In vivo test demonstrated that CoQ10 and TMZ could significantly reduce the concentration of blood urea nitrogen (BUN) and SCR induced by CM i.v. injection, as well as tubular pathological injuries. Meanwhile, CoQ10 and TMZ could significantly reduce the oxidation stress in kidneys from CM-AKI animals.

Conclusion

CoQ10 plus TMZ could decrease the incidence of CIN in patients with renal insufficiency undergoing elective cardiac catheterization, and their effect may be due to its strong anti-oxidation effect.

The molecular mechanism of contrast-induced nephropathy (CIN) and its link to in vitro studies on iodinated contrast media (CM)

Iodinated contrast media (iodinated CM) have increased ability to absorb x-rays and to visualize structures that normally are impossible to observe in a radiological examination. The use of iodinated CM may destory renal function, commonly known as contrast-induced nephropathy (CIN), which can result in acute renal failure (ARF). This review article mainly focuses on the following areas: (1) classifications of iodinated CM: ionic or non-ionic, high-osmolarity contrast media (HOCM), low-osmolarity contrast media (LOCM) and iso-osmolarity contrast media (IOCM); (2) an introduction to the physical and chemical properties of the non-ionic iodinated CM; (3) the management of anaphylactic reaction by iodinated CM; (4) a suggested single injection of adult doses and maximum dose for non-ionic iodinated CM; (5) the molecular mechanism of contrast-induced nephropathy (CIN); (6) In vitro studies on iodinated CM. Based on above information, this review article provide an insight for understanding the drug safety of iodinated CM.

Hydrogen sulfide metabolism regulates endothelial solute barrier function

Hydrogen sulfide (H₂S) is an important gaseous signaling molecule in the cardiovascular system. In addition to free H₂S, H₂S can be oxidized to polysulfide which can be biologically active. Since the impact of H₂S on endothelial solute barrier function is not known, we sought to determine whether H₂S and its various metabolites affect endothelial permeability. In vitro permeability was evaluated using albumin flux and transendothelial electrical resistance. Different H₂S donors were used to examine the effects of exogenous H₂S. To evaluate the role of endogenous H₂S, mouse aortic endothelial cells (MAECs) were isolated from wild type mice and mice lacking cystathionine γ-lyase (CSE), a predominant source of H₂S in endothelial cells. In vivo permeability was evaluated using the Miles assay. We observed that polysulfide donors induced rapid albumin flux across endothelium. Comparatively, free sulfide donors increased permeability only with higher concentrations and at later time points. Increased solute permeability was associated with disruption of endothelial junction proteins claudin 5 and VE-cadherin, along with enhanced actin stress fiber formation. Importantly, sulfide donors that increase permeability elicited a preferential increase in polysulfide levels within endothelium. Similarly, CSE deficient MAECs showed enhanced solute barrier function along with reduced endogenous bound sulfane sulfur. CSE siRNA knockdown also enhanced endothelial junction structures with increased claudin 5 protein expression. In vivo, CSE genetic deficiency significantly blunted VEGF induced hyperpermeability revealing an important role of the enzyme for barrier function. In summary, endothelial solute permeability is critically regulated via exogenous and endogenous sulfide bioavailability with a prominent role of polysulfides.

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Polysulfide from cystathionine γ-lyase (CSE) and exogenous polysulfide donors increases endothelial permeability.

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The ability of polysulfide to increase permeability is associated with junction disruption and stress fiber formation.

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CSE expression in vivo regulates VEGF induced hyper-permeability.