Acute kidney injury in patients with chronic liver disease

International audienceAcute kidney injury (AKI) is a frequent clinical event in patients with liver disease, compounding their prognosis. Furthermore, it is likely that the occurrence of AKI has a detrimental impact on the subsequent renal function and the long-term survival of these patients. Recently, some authors advocated the use of new diagnostic criteria for detecting acute kidney injury in patients with cirrhosis. These criteria are based on the rapidity and extent of the creatinine increase comparing to the basal creatinine and also on the kinetics of diuresis decrease. Although their validity in this population requires further studies to be clearly established, these new criteria could have two advantages: (1) to allow earlier diagnosis of AKI and, thus, hepatorenal syndrome for which earlier intervention could improve patients' survival; and (2) to promote more intensive monitoring of renal function in these patients with high risk of AKI. Finally, recent practice guidelines about the prevention and treatment of general AKI have been published which should be useful in optimising the management of AKI in cirrhotic patients

Early mortality in dialysis and adequacy of predialysis renal care: the picture is more complex than we thought

International audienceTwo new studies examine clinical events during early dialysis. Foley et al. underline a probable ascertainment bias affecting the mortality rate during the first 6 weeks and find that age is the major risk factor for very early mortality, which can be amplified by short time of predialysis nephrology care. Singhal et al. show that adequacy of predialysis renal care is determined not only by the timing of the nephrology referral but also by the number and timing of visits

Evaluation of renal function in patients with cirrhosis: where are we now?

International audienceIn the clinical context of the patients with liver cirrhosis, accurate evaluation of the renal function is potentially crucial. Indeed, it can lead to early diagnosis of both acute kidney injury and chronic kidney disease and to reliable characterization of the renal status of the patient before performing a liver transplantation. Despite some limitations, the assay of serum creatinine (SCr) is universally used to estimate glomerular filtration rate (GFR) because of its wide availability, its simplicity and because it is inexpensive. Nevertheless, several reports show that the value of this assay to estimate GFR is strongly challenged in cirrhotic patients, especially in patients with liver failure and/or severely impaired renal function. This has led to seek new alternatives to estimate more reliably the GFR in these patients. Although the reference methods, based on the utilization of exogenous markers, allow measuring GFR and thereby constitute the "gold standard" to evaluate renal function, they are not feasible in routine clinical practice. Several studies have shown that a cystatin C (CysC) based formula perform better than the SCr-based estimates in cirrhotic patients and the estimation of GFR by these formulas could therefore lead to optimize the management of the patients. A new estimate based on CysC has been recently developed using a large number of patients and the first results regarding the evaluation of its performance are promising, making this new formula the best candidate for a reference estimate of the renal function in cirrhotic patients

Postconditioning with cyclosporine a reduces early renal dysfunction by inhibiting mitochondrial permeability transition

International audienceBACKGROUND: Ischemia-reperfusion (IR) injury leads to mitochondrial permeability transition pore opening, which contributes to cell death. The aim of this study is to determine whether ischemic or pharmacological postconditioning with cyclosporine A (CsA) might protect the kidney from lethal reperfusion injury. METHODS: Male mice underwent a unilateral (right) nephrectomy followed by 30 minutes of contralateral (left) clamping of the renal artery. We studied 4 groups at 20 minutes and 24 hours of reperfusion: a sham group (n = 4), an ischemic group (n = 6), CsA-postconditioned group (postcond-CsA, injection of 3 mg/kg of CsA 5 minutes before the end of ischemia, (n = 6), and an ischemic postconditioning (IPC) group (n = 6), consisting of 3 cycles of 30 seconds of renal ischemia with 30 seconds intervening reperfusion. After 24 hours of reperfusion, we measured plasma creatinine, urea, and histological kidney injury. The kidney mitochondria were isolated to assess the mitochondria calcium retention capacity and oxidative phosphorylation. RESULTS: At 24 hours after reperfusion, serum creatinine decreased in postcond-CsA and IPC compared to ischemic group. The histological score was also significantly improved with postcond-CsA and IPC. At 20 minutes and 24 hours of reperfusion, calcium retention capacity was decreased significantly in the ischemic group. The mitochondrial respiration stay decreased in the ischemic group at 24 hours of reperfusion, whereas the respiration was improved significantly in the postcond-CsA and IPC group. Bax and cleaved caspase 3 decreased in PostCsA and IPC group. CONCLUSIONS: Our results suggest that IPC and CsA, administered immediately before reperfusion, protect the kidney from lethal injury

Acute, pro‐contractile effects of prorenin on rat mesenteric arteries

Prorenin and the prorenin receptor ((P)RR) are important, yet controversial, members of the renin–angiotensin–aldosterone system. The ((P)RR) is expressed throughout the body, including the vasculature, however, the direct effect of prorenin on arterial contractility is yet to be determined. Within rat mesenteric arteries, immunostaining and proximity ligation assays were used to determine the interacting partners of (P)RR in freshly isolated vascular smooth muscle cells (VSMCs). Wire myography examined the functional effect of prorenin. Simultaneous changes in [Ca 2+] i and force were recorded in arteries loaded with Fura-2AM. Spontaneously transient outward currents were recorded via perforated whole-cell patch-clamp configuration in freshly isolated VSMCs. We found that the (P)RR is located within a distance of less than 40 nm from the V-ATPase, caveolin-1, ryanodine receptors, and large conductance Ca 2+-activated K + channels (BK Ca) in VSMCs. [Ca 2+] i imaging and isometric tension recordings indicate that 1 nM prorenin enhanced α1-adrenoreceptor-mediated contraction, associated with an increased number of Ca 2+ waves, independent of voltage-gated Ca 2+ channels activation. Incubation of VSMCs with 1 nM prorenin decreased the amplitude and frequency of spontaneously transient outward currents and attenuated BK Ca-mediated relaxation. Inhibition of the V-ATPase with 100 nM bafilomycin prevented prorenin-mediated inhibition of BK Ca-derived relaxation. Renin (1 nM) had no effect on BK Ca-mediated relaxation. In conclusion, prorenin enhances arterial contractility by inhibition of BK Ca and increasing intracellular Ca 2+ release. It is likely that this effect is mediated through a local shift in pH upon activation of the (P)RR and stimulation of the V-ATPase.</p

Creatinine- versus cystatine C-based equations in assessing the renal function of candidates for liver transplantation with cirrhosis

International audienceRenal dysfunction is frequent in liver cirrhosis and is a strong prognostic predictor of orthotopic liver transplantation (OLT) outcome. Therefore, an accurate evaluation of the glomerular filtration rate (GFR) is crucial in pre-OLT patients. However, in these patients plasma creatinine (Pcr) is inaccurate and the place of serum cystatine C (CystC) is still debated. New GFR-predicting equations, based on standardized assays of Pcr and/or CystC, have been recently recommended in the general population but their performance in cirrhosis patients has been rarely studied. We evaluated the performance of the recently published Chronic Kidney Disease Epidemiology Collaboration equations (CKD-EPI-Pcr, CKD-EPI-CystC, and CKD-EPI-Pcr-CystC) and the more classical ones (4- and 6-variable MDRD and Hoek formulas) in cirrhosis patients referred for renal evaluation before OLT. Inulin clearance was performed in 202 consecutive patients together with the determination of Pcr and CystC with assays traceable to primary reference materials. The performance of the GFR-predicting equations was evaluated according to ascites severity (no, moderate, or refractory) and to hepatic and renal dysfunctions (MELD score \textless/= or \textgreater15 and KDOQI stages, respectively). In the whole population, CystC-based equations showed a better performance than Pcr-based ones (lower bias and higher 10% and 30% accuracies). CKD-EPI-CystC equation showed the best performance whatever the ascites severity and in presence of a significant renal dysfunction (GFR \textless60 mL/min/1.73 m(2)). CONCLUSION: Pcr-based GFR predicting equations are not reliable in pre-OLT patients even when an IDMS-traceable enzymatic Pcr assay is used. Whenever a CystC-assay traceable to primary reference materials is performed and when a true measurement of GFR is not possible, CystC-based equations, especially CKD-EPI-CystC, may be recommended to evaluate renal function and for KDOQI staging