Effect of radiographic contrast media on renal perfusion - First results

Dysregulation of ferroptosis may participate in the mitigating effect of CoCl2 on contrast-induced nephropathy

BACKGROUND

Contrast agents can directly or indirectly induce renal tubular ischemia and hypoxic damage. Given that cobalt chloride (CoCl2) can protect renal tubules, the protective effect and potential mechanism of action of CoCl2 on contrast-induced nephropathy (CIN) warrant investigation.

METHODS

A CIN mouse model was established to determine the protective effect of CoCl2 on renal injury in vivo. Then, TMT-based proteomics was performed to determine the differentially expressed proteins (DEPs), following which, enrichment analyses of gene ontology and the KEGG pathway were performed. In vitro, a CIN model was constructed with renal tubular epithelial cells (HK-2) to determine the effect of CoCl2 on potential targets and the role of the key protein identified from the in vivo experiments.

RESULTS

CoCl2 treatment decreased the levels of BUN and serum creatinine (sCr), while increasing the levels of urea and creatinine (Cr) in the urine of mice after CIN injury. Damage to the renal tubules in the CoCl2 treatment group was significantly less than in the CIN model group. We identified 79 DEPs after treating the in vivo model with CoCl2, and frequently observed ferroptosis-related GO and KEGG pathway terms. Of these, Hp (haptoglobin) was selected and found to have a strong renoprotective effect, even though its expression level in kidney tissue decreased after CoCl2 treatment. In HK-2 cells, overexpression of Hp reduced the ferroptosis caused by erastin, while knocking down Hp negated the attenuation effect of CoCl2 on HK-2 cell ferroptosis.

CONCLUSION

CoCl2 attenuated kidney damage in the CIN model, and this effect was associated with the decrease in ferroptosis mediated by Hp.

Post-mortem distribution of Iodinated Contrast Media (ICM) (iodixanol versus iopromide) in the porcine kidney after multiple bolus injections in vivo into the supra-renal aorta1

 Iodinated contrast media (ICM) are widely used for diagnostic and interventional procedures in radiology and cardiology. Ideally, they should not interact with blood cells or vascular wall cells to avoid deteriorations of the blood circulation. However, it is well known that ICM can affect erythrocytes as well as endothelial cells which consequently might perturb especially the microcirculation. In former studies the influence of two ICM (iodixanol versus iopromide) on the vascular system, the development of blood stasis, on changes in renal resistive index (RRI) and vascular diameters, and on the post-mortem distribution of iodine as marker for ICM in the explanted kidneys was examined. The modus of ICM application into the supra-renal aorta followed the regime in interventional cardiology, so that 10 bolus injections were administered at steady intervals (iopromide 4,32 ml / iodixanol 5 ml) accompanied by infusion of 500 ml isotonic NaCl-solution.In the present study, the post-mortem X-ray analysis revealed that there were no differences in iodine content in the regions of the mid-cortex and the medullo-pelvic transition zone of the kidneys after application of both ICM. Remarkable differences, however, were found in the region of the capsule-near cortex, where the application of iopromide led to a significantly lower iodine content in the microcirculation. This is in good agreement with former studies, in which a maldistribution in this area, presumably due to a decrease in arteriolar inflow as a result of stasis/occlusion was shown.

Sonographic 3-D Power Doppler Imaging Enhances Rapid Assessment of Morphologic and Pathologic Arteriovenous Fistula Variations

Early detection of pathologic variations in an arteriovenous fistula (AVF) is essential for preventing fistula dysfunction in individuals undergoing hemodialysis. This study aimed to evaluate the clinical applicability of 3-D tomographic ultrasound (tUS) for rapid and simple visualization of AVF morphology and pathology. We assessed 53 AVFs in 50 consecutive patients using 3-D tUS including secondary, blinded reading. For all examinations, a high-end ultrasound (US) device was used with linear probe, attached to a tUS system to allow freehand 3-D scanning. Participants were examined by 2-D US and 3-D tUS with different raw data (B-mode, power Doppler, B-flow). Additional angiography was available for 15 participants with scheduled interventions. In all participants, 3-D tUS allowed a 3-D representation of AVFs in angiographic-like images with good image quality. The 2-D US assessment took 7.9 ± 4.0 min. A 3-D power Doppler scan required, on average, 1.4 ± 0.6 min. Diagnostic accuracy of blinded reading for pathologies was high (86.8% for aneurysms and 79.2% for stenoses). Bland-Altman plots showed an excellent correlation of 3-D tUS with 2-D US and angiography. 3-D tUS is an easily and rapidly applicable method for visualizing morphologic and pathologic AVF variations. Color-coded 3-D reconstruction of power Doppler data simplifies detection of perfused aneurysms and stenoses.

Porcine models of acute kidney injury

Pigs represent a potentially attractive model for medical research. Similar body size and physiological patterns of kidney injury that more closely mimic those described in humans make larger animals attractive for experimentation. Using larger animals, including pigs, to investigate the pathogenesis of acute kidney injury (AKI) also serves as an experimental bridge, narrowing the gap between clinical disease and preclinical discoveries. This article compares the advantages and disadvantages of large versus small AKI animal models and provides a comprehensive overview of the development and application of porcine models of AKI induced by clinically relevant insults, including ischemia-reperfusion, sepsis, and nephrotoxin exposure. The primary focus of this review is to evaluate the use of pigs for AKI studies by current investigators, including areas where more information is needed.

Histological and SEM Assessment of Blood Stasis in Kidney Blood Vessels after Repeated Intra-Arterial Application of Radiographic Contrast Media

BACKGROUND

After application of iodinated contrast media (CM), a pronounced deterioration of the microcirculation in skin and myocardium was reported. Clinically, the repeated application of CM, especially, led to an increase of the renal resistance index (RRI). With respect to the transiency of the RRI increase, it is reasonable to assume that the deterioration of blood flow could be due to transient blood stasis caused by reversible morphologic cell alterations due to osmotic discrepancies between CM and human blood. Therefore, the hypothesis was investigated whether CM are able to induce in vivo such blood stasis and cell deformations in the renal vasculature of well-hydrated pigs.

METHODS

The in vivo study was performed as a prospective randomized examination to compare the effects of two different CM in 16 pigs (German Landrace). Pigs were randomized to receive either Iodixanol (n = 8), or Iopromide (n = 8). Each animal received 10 injections separated by 5-min intervals via the suprarenal aorta at a rate of 10 mL/s according to the usual procedure during a cardiac catheter examination. Finally, the kidneys were explanted and processed for histology (H & E staining and fibrin staining according to Weigert) as well as for scanning electron microscopy (SEM) with regards to morphologic correlates explaining the changes in the microcirculation.

RESULTS

In each of the predefined four categories of vascular diameters, blood stasis were found, but clearly more often after application of Iopromide than after application of Iodixanol (p < 0.001). In addition, Iopromide induced more blood stasis in all of the examined kidney regions compared to Iodixanol (p = 0.0001). There were no obstructive events in the middle cortex following the application of Iodixanol. Except for the region around a puncture channel of a placed-in catheter probe, no fibrin was detected in Weigert's fibrin-stained samples, neither around the histologically assessed thrombi nor in vessels with blood stasis. Complementary SEM analyses revealed in a few cases only a slight generation of fibrin and thrombi and deformations, such as echinocyte and "box-like" deformations.

CONCLUSIONS

According to previous in vitro studies, pathological erythrocyte deformations, such as echinocyte and box-like formation of erythrocytes, were observed also in vivo. In addition, blood stasis and/or thrombi could be detected in histological samples from explanted kidneys from young pigs after repeated in vivo administration of CM. In only a few cases, mural platelet aggregates within minimal fibrin meshes occurred only after the application of Iopromide.

A Randomized Trial of Recombinant Human C1-Esterase-Inhibitor in the Prevention of Contrast-Induced Kidney Injury

OBJECTIVES

This study sought to determine the efficacy profile and safety of recombinant human C1 esterase inhibitor (rhC1INH) in the prevention of contrast-associated acute kidney injury after elective coronary angiography.

BACKGROUND

Contrast-associated acute kidney injury is caused by tubular cytotoxicity and ischemia/reperfusion injury. rhC1INH is effective in reducing renal ischemia/reperfusion injury in experimental models.

METHODS

In this placebo-controlled, double-blind, single-center trial 77 patients with chronic kidney disease were randomized to receive 50 IU/kg rhC1INH before and 4 h after elective coronary angiography or placebo. The primary outcome was the peak change of urinary neutrophil gelatinase-associated lipocalin within 48 h, a surrogate marker of kidney injury.

RESULTS

Median peak change of urinary neutrophil gelatinase-associated lipocalin was lower in the rhC1INH group (4.7 ng/ml vs. 22.5 ng/ml; p = 0.038) in the per-protocol population but not in the modified intention-to-treat analysis, and in patients with percutaneous coronary interventions (median, 1.8 ng/ml vs. 26.2 ng/ml; p = 0.039 corresponding to a median proportion peak change of 11% vs. 205%; p = 0.002). The incidence of a cystatin C increase ≥10% within 24 h was lower in the rhC1INH group (16% vs. 33%; p = 0.045), whereas the frequency of contrast-associated acute kidney injury was comparable. Adverse events during a 3-month follow-up were similarly distributed.

CONCLUSIONS

Administration of rhC1INH before coronary angiography may attenuate renal injury as reflected by urinary neutrophil gelatinase-associated lipocalin and cystatin C. The safety profile of rhC1INH was favorable in a patient population with multiple comorbidities. (Recombinant Human C1 Esterase Inhibitor in the Prevention of Contrast-induced Nephropathy in High-risk Subjects [PROTECT]; NCT02869347).