Iron Overload in Renal Transplant Patients: The Role of Hepcidin and Erythropoietin

Increased ferritin levels are associated with incident diabetes after kidney transplantation: A prospective cohort study

AIM

Iron is known to play a role in glucose homeostasis, and diabetes is highly prevalent in patients with iron overload. Here, we investigated whether ferritin and hepcidin (as parameters of iron status) are associated with the development of post-transplant diabetes in kidney transplant recipients, a population in which around 10 % is known to have high iron status.

METHODS

Prospective data from the TransplantLines Insulin Resistance and Inflammation Biobank and Cohort Study from the University Medical Center Groningen, the Netherlands were evaluated, involving stable adult kidney transplant recipients > 1 year after transplantation. Associations between ferritin and hepcidin levels, as markers of iron status, and incident post-transplant diabetes were analyzed by multivariable Cox regression models, followed by the exploration of potential clinical cut-offs of ferritin levels related to the risk of post-transplant diabetes.

RESULTS

Of the included 443 kidney transplant recipients (age 50 ± 12 years, 44 % women, median 6.1 [3.0 - 12.1] years after transplantation), 65 kidney transplant recipients (15 %) developed post-transplant diabetes during a median follow-up of 9.6 [6.3 - 10.2] years. In contrast to hepcidin levels, ferritin levels were significantly associated with incident post-transplant diabetes, independent of adjustment for potential confounders (HR per 50 µg/l, 1.08; 95 % CI 1.02 - 1.14). When analyzing specific clinical cut-offs of ferritin levels, kidney transplant recipients with a ferritin > 500 µg/l (n=40) had more than twice the risk of developing post-transplant diabetes, compared to kidney transplant recipients with ferritin < 100 µg/l (HR, 2.81; 95 % CI 1.04 - 7.55).

CONCLUSIONS

Increased levels of ferritin are independently associated with a higher risk of post-transplant diabetes in kidney transplant recipients. Especially, kidney transplant recipients with ferritin levels > 500 µg/l, seem susceptible to the development of post-transplant diabetes over time.

Mitochondrial iron regulation as an emerging target in ischemia/reperfusion injury during kidney transplantation

The injury caused by ischemia and subsequent reperfusion (I/R) is inevitable during kidney transplantation and its current management remains unsatisfactory. Iron is considered to play a remarkable pathologic role in the initiation or progression of tissue damage induced by I/R, whereas the effects of iron-related therapy remain controversial owing to the complicated nature of iron's involvement in multiple biological processes. A significant portion of the cellular iron is located in the mitochondria, which exerts a central role in the development and progression of I/R injury. Recent studies of iron regulation associated with mitochondrial function represents a unique opportunity to improve our knowledge on the pathophysiology of I/R injury. However, the molecular mechanisms linking mitochondria to the iron homeostasis remain unclear. In this review, we provide a comprehensive analysis of the alterations to iron metabolism in I/R injury during kidney transplantation, analyze the current understanding of mitochondrial regulation of iron homeostasis and discussed its potential application in I/R injury. The elucidation of regulatory mechanisms regulating mitochondrial iron homeostasis will offer valuable insights into potential therapeutic targets for alleviating I/R injury with the ultimate aim of improving kidney graft outcomes, with potential implications that could also extend to acute kidney injury or other I/R injuries.

Impact of iron status on kidney outcomes in kidney transplant recipients

Iron plays an important role in hemodynamics and the immunity, independent of anemia. Since dynamic changes occur in iron storage after kidney transplantation (KT), we investigated the association between iron status and kidney outcomes in KT patients. We analyzed data from the KoreaN cohort study for Outcome in patients With KT (KNOW-KT). The iron status was classified into three groups based on ferritin or transferrin saturation (TSAT) levels one year after KT, with reference ranges of 20‒35% and 100‒300 ng/mL for TSAT and ferritin, respectively. The primary outcome was the composite outcome, which consisted of death, graft failure, and an estimated glomerular filtration rate decline ≥ 50%. In total, 895 patients were included in the final analysis. During a median follow-up of 5.8 years, the primary outcome occurred in 94 patients (19.8/1000 person-years). TSAT levels decreased one year after KT and thereafter gradually increased, whereas ferritin levels were maintained at decreased levels. The adjusted hazard ratios (95% confidence intervals) for the composite outcome were 1.67 (1.00-2.77) and 1.20 (0.60-2.40) in the TSAT > 35% and ferritin > 300 ng/mL groups, respectively. High iron status with high TSAT levels increases the risk of graft failure or kidney functional deterioration after KT.

HEPATIC ALTERATIONS IN KIDNEY TRANSPLANT RECIPIENTS FROM THE LARGEST KIDNEY TRANSPLANT CENTER IN BRAZIL

ABSTRACT Background Kidney transplant is the treatment of choice for patients with end-stage renal disease and is associated with lower mortality when compared to dialysis methods. Brazil is the country with the second largest number of kidney transplants in the world and among these patients it has been observed that liver abnormalities are common. The frequency of liver abnormalities ranges from 20-50% post-transplantation, and have an important impact on the survival and quality of life of these patients. There are scarce data about the frequency, causes and characteristics of these alterations. Objective To determine the prevalence of the different causes of hepatic abnormalities in kidney transplant recipients, to associate the characteristics of these abnormalities with demographic, epidemiological and clinical variables, to compare the characteristics of hepatic alterations between different etiologies, and to evaluate possible changes in diagnosis over two different periods of time. Methods Descriptive, cross-sectional observational, epidemiological study was conducted at the outpatient “Hepato-Rim”clinic of Hospital São Paulo (EPM/UNIFESP), a center providing specialized care for patients with hepatic abnormalities and underlying kidney diseases. Results Five-hundred eighty-one transplant patients were evaluated. The most prevalent etiologies of liver abnormalities were hepatitis C and B, iron overload, nonalcoholic fatty liver disease (NAFLD), and drug-induced liver injury (DILI). The most common cause — hepatitis C — was analyzed in greater detail. Compared to the other causes, this infection was more frequent in older patients, female patients, and patients with a longer time since transplantation and hemodialysis. Analysis of the two periods showed that patients of period 1 (P1 — 1993 to 2005) were older and were more frequently referred because of positive serology; referral due to aminotransferases abnormalities predominated during period 2 (P2 — 2006 to 2018). The predominant diagnoses were hepatitis C and B during P1 and NAFLD and DILI during P2. Conclusion Assessment of the main hepatic alterations in kidney transplant recipients is important because it permits better management of these patients in terms of diagnostic investigation and treatment and contributes to the prevention of complications in this special population.

Anemia in Pediatric Kidney Transplant Recipients-Etiologies and Management

Posttransplant anemia (PTA) is a common complication of pediatric kidney transplantation, with a prevalence ranging from 22 to 85%. PTA is categorized as early (within 6 months posttransplant) and late (>6 months posttransplant). Early PTA is typically associated with surgical blood losses and iron deficiency. Late PTA primarily results from graft dysfunction; however, iron deficiency, drug toxicity, and posttransplant inflammation also play a role. PTA is more severe compared with the anemia in glomerular-filtration-rate matched patients with native chronic kidney disease. Treatment of PTA is directed toward the underlying cause. Erythropoiesis stimulating agents (ESA) are effective; however, their use is limited in the transplant setting. Timely diagnosis and treatment of PTA are vital to prevent long-term adverse outcomes in pediatric transplant recipients.

Effects of resistance training on hepcidin levels and iron bioavailability in older individuals with end-stage renal disease: A randomized controlled trial

Anemia is an inherent complication of older individuals with end-stage renal disease (ESRD) that is associated with inflammation which in turn is an important factor in the activation of hepcidin that contributes to the decrease in serum iron. Athough resistance training (RT) seems to reduce inflammation in ESRD, its influence on hepcidin and iron availability in hemodialysis patients is unclear. Therefore, the aim of this study was to exemine the effects of RT in on inflammatory profile, hepcidin, and iron status in older individuals with ESRD. End-stage renal disease patients (N: 157, age: 66.8 ± 3.6; body mass: 73 ± 15 body mass index:27 ± 3), were assigned to control (CTL n: 76) and exercise groups (RT n: 81). RT consisted of 24 weeks/3 days per week of a moderate intensity. There was an increase in the bioavailability of iron (ΔRT: 22.2; ΔCTL: -1 μg/dL, p < 0.0001), a decrease in hepcidin levels (ΔRT: -7.9; ΔCTL: 0.2 ng/mL, p < 0.0001),and an improvement of the inflammatory profile. These novel findings show that RT is a potential coadjuvant to reduce iron deficiency by decreasing the levels of hepcidin and pro-inflammatory markers in older patients undergoing hemodialysis.