Impaired erythropoietin production in liver transplant recipients: the role of calcineurin inhibitors

Prevalence of Iron Deficiency and Iron Administration in Left Ventricular Assist Device and Heart Transplantation Patients

Iron deficiency (ID) is a common comorbidity in heart failure (HF). In these patients, intravenous iron administration can improve clinical outcomes and quality of life (QoL). However, data on ID are lacking in patients who have transitioned toward left ventricular assist device (LVAD) or heart transplantation (HTx). All patients who underwent LVAD (n = 84) surgery or HTx (n = 67) at our center between 2012 and 2019, aged ≥18 years with a follow-up of ≥3 months, were included. Retrospectively, the prevalence of ID up to 1 year preoperatively, and up to February 2020 postoperatively, as well as all iron administrations were assessed during this period. Iron status was assessed in 61% and 51% of the LVAD and HTx patients preoperatively, and 81% and 84%, respectively, postoperatively. Of these patients, 53% and 71% of the LVAD and HTx patients preoperatively were diagnosed with ID preoperatively, and 71% and 77%, respectively, postoperatively. ID was more frequently diagnosed >3 months postoperatively. Sixty-three percent of the LVAD (mostly intravenous) and 63% of the HTx patients (mostly oral) received iron administration. ID is highly prevalent pre- and post-LVAD and HTx. It is plausible that substitution can have similar QoL gains as in regular HF patients.

Chronic Use of Proton-Pump Inhibitors and Iron Status in Renal Transplant Recipients

Proton-pump inhibitor (PPI) use may influence intestinal iron absorption. Low iron status and iron deficiency (ID) are frequent medical problems in renal transplant recipients (RTR). We hypothesized that chronic PPI use is associated with lower iron status and ID in RTR. Serum iron, ferritin, transferrin saturation (TSAT), and hemoglobin were measured in 646 stable outpatient RTR with a functioning allograft for ≥ 1 year from the "TransplantLines Food and Nutrition Biobank and Cohort Study" (NCT02811835). Median time since transplantation was 5.3 (1.8-12.0) years, mean age was 53 ± 13 years, and 56.2% used PPI. In multivariable linear regression analyses, PPI use was inversely associated with serum iron (β = -1.61, p = 0.001), natural log transformed serum ferritin (β = -0.31, p < 0.001), TSAT (β = -2.85, p = 0.001), and hemoglobin levels (β = -0.35, p = 0.007), independent of potential confounders. Moreover, PPI use was independently associated with increased risk of ID (Odds Ratio (OR): 1.57; 95% Confidence Interval (CI )1.07-2.31, p = 0.02). Additionally, the odds ratio in RTR taking a high PPI dose as compared to RTR taking no PPIs (OR 2.30; 95% CI 1.46-3.62, p < 0.001) was higher than in RTR taking a low PPI dose (OR:1.78; 95% CI 1.21-2.62, p= 0.004). We demonstrated that PPI use is associated with lower iron status and ID, suggesting impaired intestinal absorption of iron. Moreover, we found a stronger association with ID in RTR taking high PPI dosages. Use of PPIs should, therefore, be considered as a modifiable cause of ID in RTR.

Risk factors for chronic anemia in pediatric orthotopic liver transplantation: analysis of data from the SPLIT registry

Risk factors for chronic anemia in the post-transplant period have not been clearly delineated in pediatric liver transplant recipients. We analyzed data from children transplanted from 2000 to 2008 with at least two consecutive hemoglobin values from follow-up between six months and five yr post-transplant. A multivariate model was derived to determine independent risk factors associated with chronic anemia. Of 1026 children in this analysis, 242 (23.6%) were found to have chronic anemia. On multivariate analysis, GI bleeding (OR 11.83 [2.08-67.49], p = 0.0054), presence of leukopenia (OR 9.55 [95% CI 3.71-24.62], p < 0.0001), use of cyclosporine (OR 3.69, [95% CI 1.56-8.76], p = 0.0039) and corticosteroids (OR 2.90 [95% CI 1.94-4.33], p < 0.0001), and cGFR <90 mL/min/1.73 m(2) (OR 4.62 [95% CI 2.47-8.67], p < 0.0001) represented the most significant risk factors for chronic anemia. Use of antihypertensive medications (OR 1.89 [95% CI 1.23-2.91], p = 0.0039) was also significantly associated with a higher risk. In summary, chronic anemia is common in children following liver transplant. Our findings underscore the need to define the mechanisms by which these risk factors, some of which are modifiable, result in chronic anemia in pediatric liver transplant recipients.

Anemia is not predictive of sustained virological response in liver transplant recipients with hepatitis C virus who are treated with pegylated interferon and ribavirin

In the immunocompetent setting, antiviral therapy-related anemia has recently been shown to be associated with a sustained virological response (SVR). Our goal was to assess whether this is also true for liver transplantation (LT). We included 160 LT patients with recurrent hepatitis C virus (HCV) who were treated with pegylated interferon and ribavirin (RBV) between 2002 and 2010; 76% of the patients were men, the median age of the patients was 56 years (range = 33-75 years), 63% had advanced fibrosis, and 86% were infected with HCV genotype 1a or 1b. The baseline immunosuppression was tacrolimus in 56% of the patients. Mycophenolate mofetil (MMF) was used in 15%. Anemia was defined as a hemoglobin (Hb) level < 10 g/dL. Significant anemia was present when the Hb decline was >5 g/dL. Anemia and significant anemia developed in 67% and 41% of the patients, respectively. Erythropoietin was used in 60%. Factors independently associated with significant anemia included low estimated creatinine clearance [relative risk (RR) = 0.951, 95% confidence interval (CI) = 0.925-0.978, P = 0.0001], a longer time from LT to therapy (RR = 1.001, 95% CI = 1.000-1.001, P = 0.002), high baseline viremia (RR = 3.2, 95% CI = 1.3-8.1, P = 0.01), cyclosporine A (CSA)-based immunosuppression (RR: 3.472, 95% CI: 1.386-8.695; P = 0.008), and the use of MMF (RR: 5.346, 95% CI: 1.398-20.447; P = 0.014). An SVR occurred in 43% of the patients; the factors associated with an SVR included baseline variables (younger recipient age, younger donor age, infections with non-1 HCV genotypes, body mass index, and mild fibrosis) and on-treatment factors related to adherence or viral kinetics. Anemia resulted in RBV dose reductions but was not associated with the virological response at any time. In conclusion, anemia is a very frequent complication in LT patients during antiviral therapy and is associated with increased RBV dose reduction but not with an SVR. Predictors of anemia include MMF or CSA immunosuppression, high viremia, and renal insufficiency.

Comparative study of the cellular pharmacodynamics of calcineurin inhibitors between patients with chronic renal failure awaiting renal transplantation and cirrhosis patients awaiting liver transplantation

The in vitro response of peripheral blood mononuclear cells (PBMCs) to the suppressive effects of calcineurin inhibitors is known to correlate with the clinical efficacy of drugs used in renal transplantations. The present study was conducted to examine the differences of PBMC responses to calcineurin inhibitors between chronic renal failure (CRF) patients awaiting renal transplantation and cirrhosis patients awaiting liver transplantation. The study included 99 CRF patients awaiting renal transplantation and 27 cirrhosis patients awaiting liver transplantation. Twenty milliliters of venous blood was taken 1-7 days before transplantation. The in vitro drug concentrations giving 50% inhibition of PBMC blastogenesis stimulated with concanavalin A (IC(50)s) were calculated. The suppressive effects of tacrolimus against PBMC blastogenesis were more than 10-100 times stronger than those of cyclosporine. The median IC(50) value for cyclosporine against the CRF PBMCs was not significantly different from the median IC(50) value against the cirrhosis PBMCs. In contrast, tacrolimus sensitivity in cirrhosis PBMCs is approximately seven times higher than that in CRF PBMCs. The median IC(50) value for tacrolimus against cirrhosis PBMCs was significantly lower and therefore the effect was stronger in comparison to the CRF PBMCs (p < 0.001). These data suggest that the PBMCs of cirrhosis patients, in comparison to those of CRF patients, are highly sensitive to the suppressive effect of tacrolimus. However, PBMC sensitivity to cyclosporine was not significantly different between the CRF and cirrhosis patients. These observations raise the possibility that treatment with tacrolimus, rather than cyclosporine, may therefore be a better choice to reduce the risks of allograft rejection in liver transplantation.

Multiple doses of erythropoietin impair liver regeneration by increasing TNF-alpha, the Bax to Bcl-xL ratio and apoptotic cell death

Background

Liver resection and the use of small-for-size grafts are restricted by the necessity to provide a sufficient amount of functional liver mass. Only few promising strategies to maximize liver regeneration are available. Apart from its erythropoiesis-stimulating effect, erythropoietin (EPO) has meanwhile been recognized as mitogenic, tissue-protective, and anti-apoptotic pleiotropic cytokine. Thus, EPO may support regeneration of hepatic tissue.

Methodology

Rats undergoing 68% hepatectomy received daily either high dose (5000 IU/kg bw iv) or low dose (500 IU/kg bw iv) recombinant human EPO or equal amounts of physiologic saline. Parameters of liver regeneration and hepatocellular apoptosis were assessed at 24 h, 48 h and 5 d after resection. In addition, red blood cell count, hematocrit and serum EPO levels as well as plasma concentrations of TNF-α and IL-6 were evaluated. Further, hepatic Bcl-x_L and Bax protein expression were analyzed by Western blot.

Principal Findings

Administration of EPO significantly reduced the expression of PCNA at 24 h followed by a significant decrease in restitution of liver mass at day 5 after partial hepatectomy. EPO increased TNF-α levels and shifted the Bcl-x_L to Bax ratio towards the pro-apoptotic Bax resulting in significantly increased hepatocellular apoptosis.

Conclusions

Multiple doses of EPO after partial hepatectomy increase hepatocellular apoptosis and impair liver regeneration in rats. Thus, careful consideration should be made in pre- and post-operative recombinant human EPO administration in the setting of liver resection and transplantation.