Endothelin activation and postoperative renal failure after human liver transplantation

Literature review of the mechanisms of acute kidney injury secondary to acute liver injury

People exposed to liver ischaemia reperfusion (IR) injury often develop acute kidney injury and the combination is associated with significant morbidity and mortality. Molecular mediators released by the liver in response to IR injury are the likely cause of acute kidney injury (AKI) in this setting, but the mediators have not yet been identified. Identifying the mechanism of injury will allow the identification of therapeutic targets which may modulate both liver IR injury and AKI following liver IR injury.

Molecular profiling of postreperfusion milieu determines acute kidney injury after liver transplantation: A prospective study

Acute kidney injury (AKI) after liver transplantation (LT) is a common event, but its pathogenesis remains unclear. The aim of this prospective study is to investigate the potential relationship between postreperfusion gene expression, serum mediators, and the onset of AKI after LT. Sixty-five consecutive patients undergoing LT were included in the study. Reverse transcription polymerase chain reaction (PCR) was performed on liver biopsies. Gene expression of 23 genes involved in ischemia/reperfusion injury (IRI) was evaluated. The serum concentrations of endothelin (ET)-1 and inflammatory cytokines were analyzed. AKI after LT developed in 21 (32%) recipients (AKI group). Reverse transcription PCR of reperfusion biopsy in the AKI group showed higher expression of several genes involved in IRI compared with the non-AKI group. Fold changes in the gene expression of ET-1, interleukin (IL) 18, and tumor necrosis factor α (TNF-α) were associated with creatinine peak value. AKI patients also had significantly higher ET-1, IL18, and TNF-α postoperative serum levels. Multivariate analysis showed that ET-1 (odds ratio [OR], 16.7; 95% confidence interval [CI], 3.34-83.42; P = 0.001) and IL18 (OR, 5.27; 95% CI, 0.99-27.82, P = 0.048) serum levels on postoperative day 1 were independently predictive of AKI. Receiver operating characteristic analysis demonstrated that the combination of biomarkers ET-1+IL18 was highly predictive of AKI (area under the receiver operating characteristic curve, 0.91; 95% CI, 0.83-0.99). Early allograft dysfunction and chronic kidney disease stage ≥ 2 occurred more frequently in AKI patients. These results suggest that the graft itself, rather than intraoperative hemodynamic instability, plays a main role in AKI after LT. These data may have mechanistic and diagnostic implications for AKI after LT. Liver Transplantation 24 922-931 2018 AASLD.

Intrarenal resistance index for the assessment of acute renal injury in a rat liver transplantation model

Background

Acute kidney injury (AKI) is a common complication after liver transplantation (LT) and associated with a high mortality. The renal resistive index (RI) is used to assess early renal function impairment in critical care patients. However, limited data are available concerning changes of renal RI and the development of AKI early after reperfusion. We approached to investigate the changes of renal RI and AKI after reperfusion in a rat liver transplantation model.

Methods

Rats were randomly divided into sham group or LT group. Ten rats in each group were used for the hemodynamic study and twenty for Doppler measurements during the procedure. Ten rats were sacrificed 30 min or 2 h after the reperfusion. We harvested kidneys, serum and urine for further analysis of the renal function.

Results

The intrarenal RI increased significantly in the anhepatic stage and decreased significantly after the reperfusion in the LT group compared with sham group (P < 0.05). AKI was seen after the reperfusion in the LT group. No correlation was noted between the RI and renal function parameters 30 min after reperfusion.

Conclusions

The intrarenal RI increased significantly during the anhepatic stage, and decreased significantly early after the reperfusion. Intrarenal RI was unable to assess renal function in a rat liver transplantation model.

Factors influencing renal function after liver transplantation. Results from the MOST, an international observational study

INTRODUCTION

Renal failure, both acute and chronic, is a common complication after liver transplantation and can seriously jeopardise long-term outcome. Given organ shortage it should be essential to determine which patients will experience progressive and severe renal dysfunction after liver transplantation (LT).

AIM

To correlate pre-transplant renal function and risk factors for renal failure after liver transplantation with occurrence of renal failure at 1 and 5 years after LT, with particular attention to hepatitis C virus (HCV) infection.

METHODS

Data from patients enrolled in the liver section of Neoral MOST (Multinational Observational Study in Transplantation) study were used for the analysis. HCV status, pre-transplant serum creatinine level, recipient gender, recipient age, pre-transplant arterial hypertension, pre-transplant diabetes mellitus, pre-transplant antiviral therapy, the time of the transplant (before or after 2000) and immunosuppressive regimen were collected for each patient. Post-transplant occurrence of renal failure at 1 and 5 years was defined as a GFR<60 mL/min/1.73 m(2) (Stage III of the National Kidney Foundation).

RESULTS

Data from 1948 patients enrolled in the study were considered. Glomerular filtration rate (GFR) was evaluated in 406 patients at 1 year and in 233 patients at 5 years after LT. The prevalence of HCV infection was 35% in the former and 37% in the latter. The median GFR was 70 mL/min/1.73 m(2) after 1 year and 69 mL/min after 5 years, significantly lower in HCV-positive (HCV+) than in HCV-negative (HCV-) patients both 1 and 5 years after LT (p<0.001). GFR before transplant correlated with GFR at 1 month, 1 and 3 years (p<0.0001 for all correlations). Multivariate analysis confirmed HCV status, pre-LT serum creatinine levels and recipient gender as significant predictors of 1-year GFR (p<0.001 for all three). Further analysis of the effect of recipient gender indicated that the only significant risk factor observed in both male and female patients was HCV positivity. Only 1-year GFR was an independent predictor of 5-year GFR (p<0.001). HCV+ status, cyclosporine (CsA) exposure, antiviral therapy and diabetes mellitus had no significant influence on 5-year GFR.

CONCLUSIONS

HCV status and pre-LT serum creatinine levels were independent predictors of renal function a year after LT, together with GFR before transplant. The negative impact of HCV positivity on renal function was not confirmed in the long term, whereas the prognostic influence of an abnormal renal function in the early post-transplant period was more persistent.

Increased severity of renal ischemia-reperfusion injury with venous clamping compared to arterial clamping in a rat model

BACKGROUND

Arterial inflow occlusion is a well-known mechanism of renal injury during major vascular surgery. In contrast, renal injury from venous outflow obstruction is poorly understood. The goal of this study was to examine the injury pattern of renal venous outflow obstruction, compare this with the traditional model of arterial occlusion, and examine possible mechanisms.

METHODS

Male Fisher rats were used for the renal warm ischemia model. Twenty-five minutes of renal ischemia was induced by selectively occluding either the renal artery or vein. After 24 h of reperfusion, whole blood and kidney tissue were collected for further analysis.

RESULTS

Serum creatinine (SCr) concentrations taken 24 h after reperfusion were significantly greater in the venous occlusion group (V) when compared to the arterial group (A). While histology did not demonstrate significant differences in extent of necrosis between both groups, a stronger inflammatory response resulted from venous occlusion. Specifically, significantly greater MCP-1 mRNA and significantly greater MCP-1, TNF-alpha, and HO-1 protein levels were found in the venous group, while no differences in MIP-2, ICAM-1, and VCAM-1 mRNA expression existed between A and V. Further analysis demonstrated presence of increased cleaved caspase-3 protein in the artery group than in the venous group.

CONCLUSIONS

Venous renal outflow obstruction results in more severe functional renal injury when compared to arterial inflow occlusion. Macrophage activation and neutrophilic infiltration appear to be exaggerated during venous occlusion.