Auto-aggressive CXCR6+ CD8 T cells cause liver immune pathology in NASH.

Nonalcoholic steatohepatitis (NASH) is a manifestation of systemic metabolic disease related to obesity, and causes liver disease and cancer1,2. The accumulation of metabolites leads to cell stress and inflammation in the liver3, but mechanistic understandings of liver damage in NASH are incomplete. Here, using a preclinical mouse model that displays key features of human NASH (hereafter, NASH mice), we found an indispensable role for T cells in liver immunopathology. We detected the hepatic accumulation of CD8 T cells with phenotypes that combined tissue residency (CXCR6) with effector (granzyme) and exhaustion (PD1) characteristics. Liver CXCR6+ CD8 T cells were characterized by low activity of the FOXO1 transcription factor, and were abundant in NASH mice and in patients with NASH. Mechanistically, IL-15 induced FOXO1 downregulation and CXCR6 upregulation, which together rendered liver-resident CXCR6+ CD8 T cells susceptible to metabolic stimuli (including acetate and extracellular ATP) and collectively triggered auto-aggression. CXCR6+ CD8 T cells from the livers of NASH mice or of patients with NASH had similar transcriptional signatures, and showed auto-aggressive killing of cells in an MHC-class-I-independent fashion after signalling through P2X7 purinergic receptors. This killing by auto-aggressive CD8 T cells fundamentally differed from that by antigen-specific cells, which mechanistically distinguishes auto-aggressive and protective T cell immunity.

Interleukin-11 drives human and mouse alcohol-related liver disease.

OBJECTIVE: Alcoholic hepatitis (AH) reflects acute exacerbation of alcoholic liver disease (ALD) and is a growing healthcare burden worldwide. Interleukin-11 (IL-11) is a profibrotic, proinflammatory cytokine with increasingly recognised toxicities in parenchymal and epithelial cells. We explored IL-11 serum levels and their prognostic value in patients suffering from AH and cirrhosis of various aetiology and experimental ALD. DESIGN: IL-11 serum concentration and tissue expression was determined in a cohort comprising 50 patients with AH, 110 patients with cirrhosis and 19 healthy volunteers. Findings were replicated in an independent patient cohort (n=186). Primary human hepatocytes exposed to ethanol were studied in vitro. Ethanol-fed wildtype mice were treated with a neutralising murine IL-11 receptor-antibody (anti-IL11RA) and examined for severity signs and markers of ALD. RESULTS: IL-11 serum concentration and hepatic expression increased with severity of liver disease, mostly pronounced in AH. In a multivariate Cox-regression, a serum level above 6.4 pg/mL was a model of end-stage liver disease independent risk factor for transplant-free survival in patients with compensated and decompensated cirrhosis. In mice, severity of alcohol-induced liver inflammation correlated with enhanced hepatic IL-11 and IL11RA expression. In vitro and in vivo, anti-IL11RA reduced pathogenic signalling pathways (extracellular signal-regulated kinases, c-Jun N-terminal kinase, NADPH oxidase 4) and protected hepatocytes and murine livers from ethanol-induced inflammation and injury. CONCLUSION: Pathogenic IL-11 signalling in hepatocytes plays a crucial role in the pathogenesis of ALD and could serve as an independent prognostic factor for transplant-free survival. Blocking IL-11 signalling might be a therapeutic option in human ALD, particularly AH.

PUFA-Induced Metabolic Enteritis as a Fuel for Crohn's Disease.

BACKGROUND & AIMS: Crohn's disease (CD) globally emerges with Westernization of lifestyle and nutritional habits. However, a specific dietary constituent that comprehensively evokes gut inflammation in human inflammatory bowel diseases remains elusive. We aimed to delineate how increased intake of polyunsaturated fatty acids (PUFAs) in a Western diet, known to impart risk for developing CD, affects gut inflammation and disease course. We hypothesized that the unfolded protein response and antioxidative activity of glutathione peroxidase 4 (GPX4), which are compromised in human CD epithelium, compensates for metabolic perturbation evoked by dietary PUFAs. METHODS: We phenotyped and mechanistically dissected enteritis evoked by a PUFA-enriched Western diet in 2 mouse models exhibiting endoplasmic reticulum (ER) stress consequent to intestinal epithelial cell (IEC)-specific deletion of X-box binding protein 1 (Xbp1) or Gpx4. We translated the findings to human CD epithelial organoids and correlated PUFA intake, as estimated by a dietary questionnaire or stool metabolomics, with clinical disease course in 2 independent CD cohorts. RESULTS: PUFA excess in a Western diet potently induced ER stress, driving enteritis in Xbp1-/-IEC and Gpx4+/-IEC mice. ω-3 and ω-6 PUFAs activated the epithelial endoplasmic reticulum sensor inositol-requiring enzyme 1α (IRE1α) by toll-like receptor 2 (TLR2) sensing of oxidation-specific epitopes. TLR2-controlled IRE1α activity governed PUFA-induced chemokine production and enteritis. In active human CD, ω-3 and ω-6 PUFAs instigated epithelial chemokine expression, and patients displayed a compatible inflammatory stress signature in the serum. Estimated PUFA intake correlated with clinical and biochemical disease activity in a cohort of 160 CD patients, which was similarly demonstrable in an independent metabolomic stool analysis from 199 CD patients. CONCLUSIONS: We provide evidence for the concept of PUFA-induced metabolic gut inflammation which may worsen the course of human CD. Our findings provide a basis for targeted nutritional therapy.

Transmission of oral microbiota to the biliary tract during endoscopic retrograde cholangiography.

BACKGROUND: Endoscopic retrograde cholangiography (ERC) possesses a translocation risk of microbes to the biliary system. We studied bile contamination during ERC and its impact on patients' outcome in a real-life-situation. METHODS: Ninety-nine ERCs were analyzed and microbial samples were taken from the throat before and from bile during ERC and from irrigation fluid of the duodenoscope before and after ERC. RESULTS: 91.2% of cholangitis patients had detectable microbes in the bile (sensitivity 91%), but the same was true for 86.2% in the non-cholangitis group. Bacteroides fragilis (p=0.015) was significantly associated with cholangitis. In 41.7% of ERCs with contaminated endoscopes these microbes were found in the bile after the procedure. Analysis of duodenoscopes' irrigation liquid after ERC matched the microbial bile analysis of these patients in 78.8%. Identical microbial species were in throat and in bile samples of the same ERC in 33% of all cases and in 45% in the non-cholangitis group. Transmission of microbes to the biliary tract did not result in more frequent cholangitis, longer hospital stays, or worse outcome. CONCLUSIONS: During ERC bile samples are regularly contaminated with microbes of the oral cavity but it did not affect clinical outcome.

Liver Transplantation after Successful Downstaging of a Locally Advanced Hepatocellular Carcinoma with Systemic Therapy.

INTRODUCTION: Liver transplantation (LT) is potentially curative for patients with cirrhosis and hepatocellular carcinoma (HCC). However, this procedure is usually reserved for patients with early tumor stages or after successful downstaging with local regional therapies. In patients with locally advanced HCC, current guidelines recommend locoregional and palliative systemic therapies for tumor stages Barcelona Clinic Liver Cancer (BCLC) B and C, respectively. CASE REPORT: In this article, we describe a 63-year-old male patient with locally advanced HCC (BCLC C) and hepatitis C-associated cirrhosis. Following systemic treatment with the immune checkpoint inhibitor atezolizumab and the anti-VEGF antibody bevacizumab, significant downstaging to a tumor stage within the Milan criteria was achieved after which LT was successfully performed. CONCLUSION: As more effective systemic therapies become available, LT and potential curative treatment could become feasible for selected patients with locally advanced HCC.

The global case fatality rate of coronavirus disease 2019 by continents and national income: A meta-analysis.

The aim of this study is to provide a more accurate representation of COVID-19's case fatality rate (CFR) by performing meta-analyses by continents and income, and by comparing the result with pooled estimates. We used multiple worldwide data sources on COVID-19 for every country reporting COVID-19 cases. On the basis of data, we performed random and fixed meta-analyses for CFR of COVID-19 by continents and income according to each individual calendar date. CFR was estimated based on the different geographical regions and levels of income using three models: pooled estimates, fixed- and random-model. In Asia, all three types of CFR initially remained approximately between 2.0% and 3.0%. In the case of pooled estimates and the fixed model results, CFR increased to 4.0%, by then gradually decreasing, while in the case of random-model, CFR remained under 2.0%. Similarly, in Europe, initially, the two types of CFR peaked at 9.0% and 10.0%, respectively. The random-model results showed an increase near 5.0%. In high-income countries, pooled estimates and fixed-model showed gradually increasing trends with a final pooled estimates and random-model reached about 8.0% and 4.0%, respectively. In middle-income, the pooled estimates and fixed-model have gradually increased reaching up to 4.5%. in low-income countries, CFRs remained similar between 1.5% and 3.0%. Our study emphasizes that COVID-19 CFR is not a fixed or static value. Rather, it is a dynamic estimate that changes with time, population, socioeconomic factors, and the mitigatory efforts of individual countries.

A novel score predicts mortality after transjugular intrahepatic portosystemic shunt: MOTS - Modified TIPS Score.

BACKGROUND AND AIMS: The high risk for severe shunting-related post-interventional complications demands a stringent selection of candidates for transjugular intrahepatic portosystemic shunt (TIPS). We aimed to develop a simple and reliable tool to accurately predict early post-TIPS mortality. METHODS: 144 cases of TIPS implantation were retrospectively analysed. Using univariate and multivariate Cox regression analysis of factors predicting mortality within 90 days after TIPS, a score integrating urea, international normalized ratio (INR) and bilirubin was developed. The Modified TIPS-Score (MOTS) ranges from 0 to 3 points: INR >1.6, urea >71 mg/dl and bilirubin >2.2 mg/dl account for one point each. Additionally, MOTS was tested in an external validation cohort (n = 187) and its performance was compared to existing models. RESULTS: Modified TIPS-Score achieved a significant prognostic discrimination reflected by 90-day mortality of 8% in patients with MOTS 0-1 and 60% in patients with MOTS 2-3 (p < .001). Predictive performance (area under the curve) of MOTS was accurate (c = 0.845 [0.73-0.96], p < .001), also in patients with renal insufficiency (c = 0.830 [0.64-1.00], p = .02) and in patients with refractory ascites (c = 0.949 [0.88-1.00], p < .001), which are subgroups with particular room for improvement of post-TIPS mortality prediction. The results were reproducible in the validation cohort. CONCLUSIONS: Modified TIPS-Score is a novel, practicable tool to predict post-TIPS mortality, that can significantly simplify clinical decision making. Its practical applicability should be further investigated.

Alpha-1 antitrypsin governs alcohol-related liver disease in mice and humans.

OBJECTIVE: Alcohol-related liver disease (ALD) is a global healthcare problem with limited treatment options. Alpha-1 antitrypsin (AAT, encoded by SERPINA1) shows potent anti-inflammatory activities in many preclinical and clinical trials. In our study, we aimed to explore the role of AAT in ALD. DESIGN: An unselected cohort of 512 patients with cirrhosis was clinically characterised. Survival, clinical and biochemical parameters including AAT serum concentration were compared between patients with ALD and other aetiologies of liver disease. The role of AAT was evaluated in experimental ALD models. RESULTS: Cirrhotic ALD patients with AAT serum concentrations less than 120 mg/dL had a significantly higher risk for death/liver transplantation as compared with patients with AAT serum concentrations higher than 120 mg/dL. Multivariate Cox regression analysis showed that low AAT serum concentration was a NaMELD-independent predictor of survival/transplantation. Ethanol-fed wild-type (wt) mice displayed a significant decline in hepatic AAT compared with pair-fed mice. Therefore, hAAT-Tg mice were ethanol-fed, and these mice displayed protection from liver injury associated with decreased steatosis, hepatic neutrophil infiltration and abated expression of proinflammatory cytokines. To test the therapeutic capability of AAT, ethanol-fed wt mice were treated with human AAT. Administration of AAT ameliorated hepatic injury, neutrophil infiltration and steatosis. CONCLUSION: Cirrhotic ALD patients with AAT concentrations less than 120 mg/dL displayed an increased risk for death/liver transplantation. Both hAAT-Tg mice and AAT-treated wt animals showed protection from ethanol-induced liver injury. AAT could reflect a treatment option for human ALD, especially for alcoholic hepatitis.

Frequency and risk factors for major complications after stereotactic radiofrequency ablation of liver tumors in 1235 ablation sessions: a 15-year experience.

OBJECTIVES: To assess the frequency of major complications after multi-probe stereotactic radiofrequency ablation (SRFA) in a large cohort of patients over 15 years and to elucidate risk factors for adverse events. MATERIALS AND METHODS: A retrospective study was carried out between July 2003 and December 2018. Seven hundred ninety-three consecutive patients (median 65.0 years (0.3-88), 241 women and 552 men, were treated in 1235 SRFA sessions for 2475 primary and metastatic liver tumors with a median tumor size of 3.0 cm (0.5-18 cm). The frequency of major complications was evaluated according to SIR guidelines and putative predictors of adverse events analyzed using simple and multivariable logistic regression. RESULTS: Thirty-day mortality after SRFA was 0.5% (6/1235) with an overall major complication rate of 7.4% (91/1235). The major complication rate decreased from 11.5% (36/314) (before January 2011) to 6.0% (55/921) (p = 0.001). 50.5% (46/91) of major complications were successfully treated in the same anesthetic session by angiographic coiling for hemorrhage and chest tube insertion for pneumothorax. History of bile duct surgery/intervention, number of coaxial needles, and location of tumors in segment IVa or VIII were independent prognostic factors for major complications following multivariable logistic regression analysis. Simple logistic regression revealed the number of tumors, tumor size, location close to the diaphragm, tumor conglomerate, and segment VII as other significant predictors. CONCLUSION: SRFA of liver tumors is safe and can extend the treatment spectrum of conventional RFA. Adaptations over time combined with increasing experience resulted in a significant decrease in complications. KEY POINTS: • In 1235 ablation sessions in 793 patients over 15 years, we found a mortality rate of 0.5% (6/1235) and an overall major complication rate of 7.4%, which fell from 11.5 (36/314) to 6.0% (55/921, p = 0.001) after January 2011, likely due to procedural adaptations. • History of bile duct surgery/intervention (p = 0.013, OR = 3.290), number of coaxial needles (p = 0.026, OR = 1.052), and location of tumors in segment IVa (p = 0.016, OR = 1.989) or VIII (p = 0.038, OR = 1.635) were found to be independent prognostic factors. • Simple logistic regression revealed that number of tumors, tumor size, location close to the diaphragm, tumor conglomerates, and segment VII were other significant predictors of major complications.

Using Infodemiology Metrics to Assess Public Interest in Liver Transplantation: Google Trends Analysis.

BACKGROUND: Liver transplantation (LT) is the only curative treatment for end-stage liver disease. Less than 10% of global transplantation needs are met worldwide, and the need for LT is still increasing. The death rates on the waiting list remain too high. OBJECTIVE: It is, therefore, critical to raise awareness among the public and health care providers and in turn increasingly acquire donors. METHODS: We performed a Google Trends search using the search terms liver transplantation and liver transplant on October 15, 2020. On the basis of the resulting monthly data, the annual average Google Trends indices were calculated for the years 2004 to 2018. We not only investigated the trend worldwide but also used data from the United Network for Organ Sharing (UNOS), Spain, and Eurotransplant. Using pairwise Spearman correlations, Google Trends indices were examined over time and compared with the total number of liver transplants retrieved from the respective official websites of UNOS, the Organización Nacional de Trasplantes, and Eurotransplant. RESULTS: From 2004 to 2018, there was a significant decrease in the worldwide Google Trends index from 78.2 in 2004 to 20.5 in 2018 (-71.2%). This trend was more evident in UNOS than in the Eurotransplant group. In the same period, the number of transplanted livers increased worldwide. The waiting list mortality rate was 31% for Eurotransplant and 29% for UNOS. However, in Spain, where there are excellent awareness programs, the Google Trends index remained stable over the years with comparable, increasing LT numbers but a significantly lower waiting list mortality (15%). CONCLUSIONS: Public awareness in LT has decreased significantly over the past two decades. Therefore, novel awareness programs should be initialized.

Non-alcoholic Fatty Liver Disease and COVID-19 Susceptibility and Outcomes: a Korean Nationwide Cohort.

BACKGROUND: Evidence for the association between underlying non-alcoholic fatty liver disease (NAFLD), the risk of testing severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) positive, and the clinical consequences of coronavirus disease 2019 (COVID-19) is controversial and scarce. We aimed to investigate the association between the presence of NAFLD and the risk of SARS-CoV-2 infectivity and COVID-19-related outcomes. METHODS: We used the population-based, nationwide cohort in South Korea linked with the general health examination records between January 1, 2018 and July 30, 2020. Data for 212,768 adults older than 20 years who underwent SARS-CoV-2 testing from January 1 to May 30, 2020, were obtained. The presence of NAFLDs was defined using three definitions, namely hepatic steatosis index (HSI), fatty liver index (FLI), and claims-based definition. The outcomes were SARS-CoV-2 test positive, COVID-19 severe illness, and related death. RESULTS: Among 74,244 adults who completed the general health examination, there were 2,251 (3.0%) who were SARS-CoV-2 positive, 438 (0.6%) with severe COVID-19 illness, and 45 (0.06%) COVID-19-related deaths. After exposure-driven propensity score matching, patients with pre-existing HSI-NAFLD, FLI-NAFLD, or claims-based NAFLD had an 11-23% increased risk of SARS-CoV-2 infection (HSI-NAFLD 95% confidence interval [CI], 1-28%; FLI-NAFLD 95% CI, 2-27%; and claims-based NAFLD 95% CI, 2-31%) and a 35-41% increased risk of severe COVID-19 illness (HSI-NAFLD 95% CI, 8-83%; FLI-NAFLD 95% CI, 5-71%; and claims-based NAFLD 95% CI, 1-92%). These associations are more evident as liver fibrosis advanced (based on the BARD scoring system). Similar patterns were observed in several sensitivity analyses including the full-unmatched cohort. CONCLUSION: Patients with pre-existing NAFLDs have a higher likelihood of testing SARS-CoV-2 positive and severe COVID-19 illness; this association was more evident in patients with NAFLD with advanced fibrosis. Our results suggest that extra attention should be given to the management of patients with NAFLD during the COVID-19 pandemic.

Gastric banding-associated weight loss diminishes hepatic Tsukushi expression.

Obesity has emerged as a substantial global healthcare issue that is frequently associated with insulin resistance and non-alcoholic fatty liver disease (NAFLD). Tsukushi (TSK), a liver-derived molecule, was recently identified as a major driver of NAFLD. Laparoscopic adjustable gastric banding (LAGB) has proven effective in reducing body weight and improving NAFLD. We therefore aimed to investigate the relation between LAGB-induced weight loss and TSK expression. Twenty-six obese patients undergoing LAGB were included in the study and metabolic parameters were assessed before (t0) and six months after LAGB (t6). The expression of TSK in liver and subcutaneous adipose tissue (AT) specimens was determined at both time points. To unravel regulatory mechanisms of TSK expression, human peripheral blood mononuclear cells (PBMCs) were stimulated with pro-inflammatory cytokines and TSK mRNA levels were analyzed by quantitative polymerase chain reaction. LAGB induced pronounced weight loss which was paralleled by amelioration of metabolic disturbances and histologically defined NAFLD. While hepatic TSK expression was markedly decreased after LAGB, adipose tissue TSK expression remained comparable to baseline. The decline in hepatic TSK expression after LAGB positively correlated with weight loss and the reduction in BMI, and negatively correlated with NAFLD activity score (NAS). In human PBMCs, pro-inflammatory cytokines such as IL-1ß and TNFα induced the expression of TSK. In conclusion, LAGB-induced weight loss reduces hepatic TSK expression. Inhibiting TSK might represent a promising target for treating NAFLD in the future.

Effective Control of COVID-19 in South Korea: Cross-Sectional Study of Epidemiological Data.

BACKGROUND: South Korea is one of the few countries that has succeeded in flattening the curve of new COVID-19 cases and avoiding a second outbreak by implementing multiple strategies, ranging from an individual level to the population level. OBJECTIVE: We aim to discuss the unique strategies and epidemiological characteristics of COVID-19 in South Korea and present a summary of policies implemented by the Korean government during the COVID-19 pandemic. METHODS: We designed a cross-sectional study of epidemiological data published by the Korea Centers for Disease Control and Prevention on October 1, 2020. We analyzed detailed epidemiological information of COVID-19 cases, including the number of confirmed cases and resulting deaths. RESULTS: As of October 1, 2020, a total of 23,889 confirmed COVID-19 cases and 415 deaths were reported in South Korea. In this paper, we present data on the epidemiological characteristics and transmission of the disease and discuss how the South Korean government, health care providers, and society responded to the COVID-19 outbreak. CONCLUSIONS: Understanding the epidemiological characteristics of COVID-19 in South Korea and the government's successful efforts in managing the spread of the disease can provide important insights to other countries dealing with the ongoing pandemic.

Pathogenesis of Eosinophilic Esophagitis: A Comprehensive Review of the Genetic and Molecular Aspects.

Eosinophilic esophagitis (EoE) is a relatively new condition described as an allergic-mediated disease of the esophagus. Clinically, it is characterized by dysphagia, food impaction, and reflux-like symptoms. Multiple genome-wide association studies (GWAS) have been conducted to identify genetic loci associated with EoE. The integration of numerous studies investigating the genetic polymorphisms in EoE and the Mendelian diseases associated with EoE are discussed to provide insights into the genetic risk of EoE, notably focusing on CCL26 and CAPN14. We focus on the genetic loci investigated thus far, and their classification according to whether the function near the loci is known. The pathophysiology of EoE is described by separately presenting the known function of each cell and molecule, with the major contributors being eosinophils, Th2 cells, thymic stromal lymphopoietin (TSLP), transforming growth factor (TGF)-ß1, and interleukin (IL)-13. This review aims to provide detailed descriptions of the genetics and the comprehensive pathophysiology of EoE.

Stereotactic radiofrequency ablation of primary liver tumors in the caudate lobe.

BACKGROUND: The encasement of the caudate lobe by a vascular ring of large vessels may apart from the technical difficulties in needle placement increase the probability of local recurrence after thermal ablation due to cooling effects. This single-center retrospective study evaluates the results after multiprobe stereotactic radiofrequency ablation (SRFA) of hepatocellular carcinoma (HCC) in the caudate lobe. METHODS: Twenty patients underwent 24 multiple-probe SRFA sessions for the treatment of 24 HCCs in the caudate lobe. Eight of twenty patients had initially solitary tumors, the remaining 12 patients suffered from multifocal disease. RESULTS: The median tumor size was 1.5 cm (range: 1-8 cm). After a mean follow-up of 21 months one local recurrence in the caudate lobe was observed resulting in a local recurrence rate of 4.2% (1/24). The overall survival rates at 1, 3, and 5 years from the date of the first SRFA were 95%, 59%, and 44%, respectively, with a median overall survival of 51.3 months. The disease-free survival after SRFA was 48%, 24% and 24%, at 1, 3 and 5 years, respectively. One patient suffering from Child C liver cirrhosis died due to septic shock 26 days after SRFA and one postinterventional complication required minimal invasive interventional treatment. CONCLUSION: Multiprobe SRFA for HCC in the caudate lobe appears to be safe and feasible. The overall outcome is at least comparable to that of surgical resection, with low perioperative mortality and only minimal morbidity.

Prognostic significance of hepatic arterial collaterals in liver transplant recipients with biliary strictures.

BACKGROUND: The aim of this study was to determine the prevalence of hepatic artery stenosis (HAS) and the prognostic implications of hepatic arterial collaterals in liver transplant (LT) recipients with biliary strictures. METHODS: The 105 LT recipients transplanted between 2004 and 2015 at our center had documented biliary strictures. HAS and collaterals were assessed in high-quality imaging of the hepatic artery available from 66 recipients. Clinical, demographic, and biochemical recipient and donor data were retrospectively analyzed and tested for their association with biliary or arterial complications after LT. RESULTS: The prevalence of HAS was 68% (45 of 66) in LT recipients with biliary strictures. Seventy-six percent (37 of 49) of patients with nonanastomotic biliary strictures had HAS. This was significantly higher than in patients with anastomotic stricture, where 47% (8 of 17) of patients had a pathological hepatic arteriogram (P=.039). The location of bile duct strictures was not predictive for outcome. In contrast, arterial collaterals were associated with significantly better patient and graft survival. CONCLUSION: Impaired hepatic arterial perfusion is frequently associated with nonanastomotic strictures, but less closely correlated with anastomotic strictures. On survival analysis, hepatic arterial collaterals have a protective effect.

Iron metabolism in transplantation.

Recipient's iron status is an important determinant of clinical outcome in transplantation medicine. This review addresses iron metabolism in solid organ transplantation, where the role of iron as a mediator of ischemia-reperfusion injury, as an immune-modulatory element, and as a determinant of organ and graft function is discussed. Although iron chelators reduce ischemia-reperfusion injury in cell and animal models, these benefits have not yet been implemented into clinical practice. Iron deficiency and iron overload are associated with reduced immune activation, whose molecular mechanisms are reviewed in detail. Furthermore, iron overload and hyperferritinemia are associated with poor prognosis in end-stage organ failure in patients awaiting kidney, or liver transplantation. This negative prognostic impact of iron overload appears to persist after transplantation, which highlights the need for optimizing iron management before and after solid organ transplantation. In contrast, iron deficiency and anemia are also associated with poor prognosis in patients with end-stage heart failure. Intravenous iron supplementation should be managed carefully because parenterally induced iron overload could persist after successful transplantation. In conclusion, current evidence shows that iron overload and iron deficiency are important risk factors before and after solid organ transplantation. Iron status should therefore be actively managed in patients on the waiting list and after transplantation.