Marked Iron in Liver Explants in the Absence of Major Hereditary Hemochromatosis Gene Defects: A Risk Factor for Cardiac Failure

Type 2 diabetic mellitus related osteoporosis: focusing on ferroptosis

With the aging global population, type 2 diabetes mellitus (T2DM) and osteoporosis(OP) are becoming increasingly prevalent. Diabetic osteoporosis (DOP) is a metabolic bone disorder characterized by abnormal bone tissue structure and reduced bone strength in patients with diabetes. Studies have revealed a close association among diabetes, increased fracture risk, and disturbances in iron metabolism. This review explores the concept of ferroptosis, a non-apoptotic cell death process dependent on intracellular iron, focusing on its role in DOP. Iron-dependent lipid peroxidation, particularly impacting pancreatic β-cells, osteoblasts (OBs) and osteoclasts (OCs), contributes to DOP. The intricate interplay between iron dysregulation, which comprises deficiency and overload, and DOP has been discussed, emphasizing how excessive iron accumulation triggers ferroptosis in DOP. This concise overview highlights the need to understand the complex relationship between T2DM and OP, particularly ferroptosis. This review aimed to elucidate the pathogenesis of ferroptosis in DOP and provide a prospective for future research targeting interventions in the field of ferroptosis.

Sudden Onset Iron Overload Cardiomyopathy After Liver Transplantation

Iron overload cardiomyopathy has been described in patients who develop acute heart failure after liver transplantation but few reports of this are available. We present a case of a patient with end-stage liver disease who underwent a deceased donor liver transplantation and developed acute onset systolic heart failure with reduced left ventricular ejection fraction. A cardiac magnetic resonance image demonstrated late gadolinium enhancement with diffuse enhancement globally and T1 mapping with severely decreased pre-contrast T1 values suggesting iron overload cardiomyopathy. The patient was treated with iron chelating therapy as well as heart failure guideline-directed medical therapy with subsequent improvement in cardiac function on follow-up magnetic resonance images. Despite our patient's diagnosis of iron overload cardiomyopathy, her iron studies showed normal serum iron and ferritin levels and no evidence of hepatic iron deposition in the transplanted liver.

Explant liver evaluation decodes the mystery of cryptogenic cirrhosis!

Background and Aim

To determine the concordance of liver explants with the pretransplant diagnosis.

Methods

This was a retrospective analysis of 251 liver explants. Patient information included demography, comorbidity, and etiological diagnosis. Final diagnosis was based on morphological and histological findings. For non‐alcoholic steatohepatitis (NASH) and cryptogenic cirrhosis, we investigated comorbid states such as obesity, hypertension, and diabetes. Chi square test and Cohen's Kappa value were used. A P value of <0.05 was considered significant.

Results

A total of 192 patients (76.5%) were males. A significant concordance of explant diagnosis with pretransplant diagnosis was present in 225 (89.6%) patients. It was 100% for alcohol‐related disease, hepatitis B, hepatitis C, autoimmune (AI) liver disease, biliary cirrhosis, and Budd–Chiari syndrome. Of 37 patients with a pretransplant diagnosis of cryptogenic cirrhosis, major discordance was observed in 23 (62.1%). On explant, seven patients each had hemochromatosis 5 (13.5%), AI hepatitis, and NASH (18.9%); two had noncirrhotic fibrosis (5.4%); and one each had Wilson's disease and congenital hepatic fibrosis (2.7%). Of the 20 explants, 3 with pretransplant diagnosis of NASH had a diagnosis of cryptogenic cirrhosis on explant specimens. Cohen's Kappa for the concordance of pretransplant diagnosis and explant diagnosis in NASH and cryptogenic cirrhosis patients was 0.75 and 0.47, respectively. An incidental hepatocellular carcinoma was picked up in 16 explants, and 18 had granulomas.

Conclusion

Concordance between pretransplant and explant diagnosis is lower for NASH and cryptogenic cirrhosis. The true prevalence of cryptogenic cirrhosis in our study was 5.6%.

Cardiac iron overload following liver transplantation in patients without hereditary hemochromatosis or severe hepatic iron deposition

BACKGROUND

Cardiac iron overload following liver transplantation in patients without hemochromatosis but with severe hepatic iron deposition has been reported to result in heart failure and/or death in case reports and small case series. However, the frequency and causes of cardiac iron overload following liver transplantation and its relationship to cardiac dysfunction in patients without severe hepatic iron deposition are unclear.

METHODS

The primary inclusion criteria for this study were liver transplantation followed by autopsy or cardiac transplantation within 1 year. Cases of known hemochromatosis were excluded. Iron stains were performed on left ventricular myocardium from either the autopsy or surgically resected heart, as well as the surgically resected liver.

RESULTS

Nineteen cases met the study criteria: 18 autopsies and 1 case of cardiac transplantation. None of the resected livers evaluated showed severe iron deposition. Myocardial iron deposition was identified in 7 (37%) of the cases. The presence of myocardial iron deposition was not significantly associated with the grade of hepatic iron deposition, or the pre-liver transplantation serum iron or ferritin levels. However, in the patients with myocardial iron deposition, there were trends toward higher pretransplant transferrin saturation (TSAT) and more units of red blood cells transfused (uRBC). The product of the TSAT multiplied by the uRBC was significantly greater in the patients with myocardial iron deposition [4700 (3100-9800) vs. 680 (400-2300), median (interquartile range), P=.003]. New reduced left ventricular ejection fraction (<50%) following liver transplantation occurred in four of five patients with myocardial iron deposition, compared with zero of eight patients without myocardial iron deposition (P=.007).

CONCLUSIONS

In this series of patients without severe hepatic iron deposition, cardiac iron overload was associated with cardiac dysfunction following liver transplantation and was related to the product of the pre-liver transplant TSAT multiplied by the number of uRBC transfused during and following the surgery.

Cardiac MRI T2* in Liver Transplant Candidates: Application and Performance of a Novel Imaging Technique to Identify Patients at Risk for Poor Posttransplant Cardiac Outcomes

Background

In end-stage liver disease, alterations in iron metabolism can lead to iron overload and development of iron overload cardiomyopathy. In liver transplant candidates, evaluation for cardiac iron overload and dysfunction can help to identify candidates at increased risk for peritransplant morbidity and mortality, though recommendations for pretransplant evaluation of cardiac iron overload are not standardized. Cardiac Magnetic Resonance Imaging T2* (CMRI-T2*) is a validated method to quantify cardiac iron deposition, with normal T2* value of 20 ms or greater. In this study, we sought to identify the incidence and predictors of iron overload by CMRI-T2* and to evaluate the impact of cardiac and iron overload on morbidity and mortality after liver transplantation.

Methods

In this retrospective single-center cohort study, all liver transplant candidates who underwent a pretransplant CMRI-T2* between January 1, 2008, and June 30, 2016, were included to analyze the association between clinical characteristics and low T2* using logistic regression.

Results

One hundred seventy-nine liver transplant candidates who received CMRI-T2* were included. Median age was 57 years, 73.2% were male, and 47.6% were white. 49.7% had hepatitis C and 2.8% had hemochromatosis. Median Model for End-Stage Liver Disease score was 25. 65.2% were Child-Pugh C. In multivariable logistic regression, T2* less than 20 ms (n = 35) was associated with Model for End-Stage Liver Disease score of 25 or greater (odds ratio [OR], 3.65; P = 0.007), Child-Pugh C (OR, 3.42; P = 0.03), and echocardiographic systolic ejection fraction less than 65% (OR, 2.24; P = 0.01). Posttransplant heart failure occurred exclusively in recipients with T2* less than 15 ms. Survival was worse in T2* 10 to 14.9 versus T2* of 20 ms or greater (hazard ratio, 3.85; P = 0.003), but not for 15 to 19.9 versus T2* of 20 ms or greater.

Conclusions

Severity of liver disease and systolic dysfunction is associated with T2* less than 20 ms, though there was no difference in posttransplant outcomes between T2* 15 to 19.9 and T2* 20 ms or greater, suggesting that individuals with T2* of 15 ms or greater may be suitable transplant candidates. CMRI-T2* is an additional diagnostic tool in evaluating transplant candidates at high risk for posttransplant cardiac complications.

Molecular pathogenesis and clinical consequences of iron overload in liver cirrhosis

BACKGROUND

The liver, as the main iron storage compartment and the place of hepcidin synthesis, is the central organ involved in maintaining iron homeostasis in the body. Excessive accumulation of iron is an important risk factor in liver disease progression to cirrhosis and hepatocellular carcinoma. Here, we review the literature on the molecular pathogenesis of iron overload and its clinical consequences in chronic liver diseases.

DATA SOURCES

PubMed was searched for English-language articles on molecular genesis of primary and secondary iron overload, as well as on their association with liver disease progression. We have also included literature on adjuvant therapeutic interventions aiming to alleviate detrimental effects of excessive body iron load in liver cirrhosis.

RESULTS

Excess of free, unbound iron induces oxidative stress, increases cell sensitivity to other detrimental factors, and can directly affect cellular signaling pathways, resulting in accelerated liver disease progression. Diagnosis of liver cirrhosis is, in turn, often associated with the identification of a pathological accumulation of iron, even in the absence of genetic background of hereditary hemochromatosis. Iron depletion and adjuvant therapy with antioxidants are shown to cause significant improvement of liver functions in patients with iron overload. Phlebotomy can have beneficial effects on liver histology in patients with excessive iron accumulation combined with compensated liver cirrhosis of different etiology.

CONCLUSION

Excessive accumulation of body iron in liver cirrhosis is an important predictor of liver failure and available data suggest that it can be considered as target for adjuvant therapy in this condition.

Iron and the liver

Humans have evolved to retain iron in the body and are exposed to a high risk of iron overload and iron-related toxicity. Excess iron in the blood, in the absence of increased erythropoietic needs, can saturate the buffering capacity of serum transferrin and result in non-transferrin-bound highly reactive forms of iron that can cause damage, as well as promote fibrogenesis and carcinogenesis in the parenchymatous organs. A number of hereditary or acquired diseases are associated with systemic or local iron deposition or iron misdistribution in organs or cells. Two of these, the HFE- and non-HFE hemochromatosis syndromes represent the paradigms of genetic iron overload. They share common clinical features and the same pathogenic basis, in particular, a lack of synthesis or activity of hepcidin, the iron hormone. Before hepcidin was discovered, the liver was simply regarded as the main site of iron storage and, as such, the main target of iron toxicity. Now, as the main source of hepcidin, it appears that the loss of the hepcidin-producing liver mass or genetic and acquired factors that repress hepcidin synthesis in the liver may also lead to iron overload. Usually, there is low-grade excess iron which, through oxidative stress, is sufficient to worsen the course of the underlying liver disease or other chronic diseases that are apparently unrelated to iron, such as chronic metabolic and cardiovascular diseases. In the future, modulation of hepcidin synthesis and activity or hepcidin hormone-replacing strategies may become therapeutic options to cure iron-related disorders.

Genetics, Genetic Testing, and Management of Hemochromatosis: 15 Years Since Hepcidin

The discovery of hepcidin in 2000 and the subsequent unprecedented explosion of research and discoveries in the iron field have dramatically changed our understanding of human disorders of iron metabolism. Today, hereditary hemochromatosis, the paradigmatic iron-loading disorder, is recognized as an endocrine disease due to the genetic loss of hepcidin, the iron hormone produced by the liver. This syndrome is due to unchecked transfer of iron into the bloodstream in the absence of increased erythropoietic needs and its toxic effects in parenchymatous organs. It is caused by mutations that affect any of the proteins that help hepcidin to monitor serum iron, including HFE and, in rarer instances, transferrin-receptor 2 and hemojuvelin, or make its receptor ferroportin, resistant to the hormone. In Caucasians, C282Y HFE homozygotes are numerous, but they are only predisposed to hemochromatosis; complete organ disease develops in a minority, due to alcohol abuse or concurrent genetic modifiers that are now being identified. HFE gene testing can be used to diagnose hemochromatosis in symptomatic patients, but analyses of liver histology and full gene sequencing are required to identify patients with rare, non-HFE forms of the disease. Due to the central pathogenic role of hepcidin, it is anticipated that nongenetic causes of hepcidin loss (eg, end-stage liver disease) can cause acquired forms of hemochromatosis. The mainstay of hemochromatosis management is still removal of iron by phlebotomy, first introduced in 1950s, but identification of hepcidin has not only shed new light on the pathogenesis of the disease and the approach to diagnosis, but etiologic therapeutic applications from these advances are now foreseen.

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.

Iron overload secondary to cirrhosis: a mimic of hereditary haemochromatosis?

AIMS

Hepatic iron deposition unrelated to hereditary haemochromatosis is common in cirrhosis. The aim of this study was to determine whether hepatic haemosiderosis secondary to cirrhosis is associated with iron deposition in extrahepatic organs.

METHODS AND RESULTS

Records of consecutive adult patients with cirrhosis who underwent autopsy were reviewed. Storage iron was assessed by histochemical staining of sections of liver, heart, pancreas and spleen. HFE genotyping was performed on subjects with significant liver, cardiac and/or pancreatic iron. The 104 individuals were predominantly male (63%), with a mean age of 55 years. About half (46%) had stainable hepatocyte iron, 2+ or less in most cases. In six subjects, there was heavy iron deposition (4+) in hepatocytes and biliary epithelium. All six of these cases had pancreatic iron and five also had cardiac iron. None of these subjects had an explanatory HFE genotype.

CONCLUSIONS

In this series, heavy hepatocyte iron deposition secondary to cirrhosis was commonly associated with pancreatic and cardiac iron. Although this phenomenon appears to be relatively uncommon, the resulting pattern of iron deposition is similar to haemochromatosis. Patients with marked hepatic haemosiderosis secondary to cirrhosis may be at risk of developing extrahepatic complications of iron overload.

Monogenic diseases that can be cured by liver transplantation

While the prevalence of most diseases caused by single-gene mutations is low and defines them as rare conditions, all together, monogenic diseases account for approximately 10 in every 1000 births according to the World Health Organisation. Orthotopic liver transplantation (LT) could offer a therapeutic option in monogenic diseases in two ways: by substituting for an injured liver or by supplying a tissue that can replace a mutant protein. In this respect, LT may be regarded as the correction of a disease at the level of the dysfunctional protein. Monogenic diseases that involve the liver represent a heterogeneous group of disorders. In conditions associated with predominant liver parenchymal damage (i.e., genetic cholestatic disorders, Wilson's disease, hereditary hemochromatosis, tyrosinemia, α1 antitrypsin deficiency), hepatic complications are the major source of morbidity and LT not only replaces a dysfunctional liver but also corrects the genetic defect and effectively cures the disease. A second group includes liver-based genetic disorders characterised by an architecturally near-normal liver (urea cycle disorders, Crigler-Najjar syndrome, familial amyloid polyneuropathy, primary hyperoxaluria type 1, atypical haemolytic uremic syndrome-1). In these defects, extrahepatic complications are the main source of morbidity and mortality while liver function is relatively preserved. Combined transplantation of other organs may be required, and other surgical techniques, such as domino and auxiliary liver transplantation, have been attempted. In a third group of monogenic diseases, the underlying genetic defect is expressed at a systemic level and liver involvement is just one of the clinical manifestations. In these conditions, LT might only be partially curative since the abnormal phenotype is maintained by extrahepatic synthesis of the toxic metabolites (i.e., methylmalonic acidemia, propionic acidemia). This review focuses on principles of diagnosis, management and LT results in both paediatric and adult populations of selected liver-based monogenic diseases, which represent examples of different transplantation strategies, driven by the understanding of the expression of the underlying genetic defect.

Iron overload and HFE gene mutations in Polish patients with liver cirrhosis

BACKGROUND

Increased liver iron stores may contribute to the progression of liver injury and fibrosis, and are associated with a higher risk of hepatocellular carcinoma development. Pre-transplant symptoms of iron overload in patients with liver cirrhosis are associated with higher risk of infectious and malignant complications in liver transplant recipients. HFE gene mutations may be involved in the pathogenesis of liver iron overload and influence the progression of chronic liver diseases of different origins. This study was designed to determine the prevalence of iron overload in relation to HFE gene mutations among Polish patients with liver cirrhosis.

METHODS

Sixty-one patients with liver cirrhosis included in the study were compared with a control group of 42 consecutive patients subjected to liver biopsy because of chronic liver diseases. Liver function tests and serum iron markers were assessed in both groups. All patients were screened for HFE mutations (C282Y, H63D, S65C). Thirty-six of 61 patients from the study group and all controls had liver biopsy performed with semiquantitative assessment of iron deposits in hepatocytes.

RESULTS

The biochemical markers of iron overload and iron deposits in the liver were detected with a higher frequency (70% and 47% respectively) in patients with liver cirrhosis. There were no differences in the prevalence of all HFE mutations in both groups. In patients with a diagnosis of hepatocellular carcinoma, no significant associations with iron disorders and HFE gene mutations were found.

CONCLUSIONS

Iron disorders were detected in patients with liver cirrhosis frequently but without significant association with HFE gene mutations. Only the homozygous C282Y mutation seems to occur more frequently in the selected population of patients with liver cirrhosis. As elevated biochemical iron indices accompanied liver iron deposits more frequently in liver cirrhosis compared to controls with chronic liver disease, there is a need for more extensive studies searching for the possible influence of non-HFE iron homeostasis regulators and their modulation on the course of chronic liver disease and liver cirrhosis.

Beyond hereditary hemochromatosis: new insights into the relationship between iron overload and chronic liver diseases

Following the model of hereditary hemochromatosis, the possible role of iron overload as a cofactor for disease progression in acquired liver diseases has been investigated with controversial results. In recent years, progress has been made in understanding the regulation of iron metabolism, thereby allowing the evaluation of the mechanisms linking liver diseases to excessive iron accumulation. Indeed, deregulation of the transcription of hepcidin, emerging as the master regulator of systemic iron metabolism, has been implicated in the pathogenesis of hepatic iron overload in chronic liver diseases. Whatever the cause, hepatocellular iron deposition promotes liver fibrogenesis, while an emerging possible aggravating factor is represented by the strong link between iron stores and insulin resistance, a recently recognized risk factor for the progression of liver diseases. Overall, these pathogenic mechanisms, together with the known proliferative and mutagenic effect of excess iron, converge in determining an increased susceptibility to hepatocellular carcinoma. Finally, an association between serum ferritin levels and mortality in patients with end-stage liver disease has recently been reported. Prospective, randomized studies are required to evaluate whether iron depletion may reduce fibrosis progression, hepatocellular carcinoma development, and eventually mortality in patients with chronic liver diseases.

Liver transplantation for inherited metabolic disorders of the liver

PURPOSE OF REVIEW

Liver transplantation is curative, life saving or both for a range of inherited diseases affecting the liver. Indications, timing and outcome of transplantation for these diseases are the focus of this review.

RECENT FINDINGS

Liver transplant represents a mode of gene replacement therapy for several disorders, including Wilson disease, hemochromatosis, tyrosinemia, urea cycle defects and hypercholesterolemia in which the primary defect residing in the liver results in hepatic complications or severe extrahepatic disease. Liver transplant is also an important therapeutic modality in multisystemic genetic disorders with major hepatic disease such as glycogen storage disease types I, III and IV and porphyria. For familial amyloidosis and primary hyperoxaluria, liver replacement eliminates the source of the injurious products that results in extrahepatic disease. Innovations in medical and surgical management of these patients have led to improved outcomes providing an important benchmark for future gene therapy of these disorders.

SUMMARY

Recent developments have refined the indications for liver transplant in the treatment of inherited metabolic diseases. The full potential of liver transplant in these disorders can be harnessed by careful patient selection, optimizing timing and perioperative metabolic management of these patients.

HFE mutations in alpha-1-antitrypsin deficiency: an examination of cirrhotic explants

Increased iron deposition is often seen in liver explants with alpha-1-antitrypsin deficiency, but it remains unclear if this is a nonspecific effect of end-stage liver disease or if individuals with alpha-1-antitrypsin deficiency and excess iron are at increased risk for HFE mutations. To further examine this question, 45 liver explants with alpha-1-antitrypsin deficiency and 33 control livers with chronic hepatitis C were examined for histological iron accumulation, graded on a scale of 0 to 4+, and HFE mutations. Interestingly, the alpha-1-antitrypsin cirrhotic livers showed a bimodal distribution of iron accumulation, with peaks at grades 1 and 3. In contrast, hepatitis C cirrhotic livers showed a unimodal distribution with a peak at grade 2. HFE mutations in livers with alpha-1-antitrypsin deficiency were as follows: C282Y=2%, H63D=42%. H63D mutations were more frequent in alpha-1-antitrypsin deficiency cases than in controls (42 vs 27%), but was not statistically significant, P=0.17. However, there was a significant association with HFE mutations in alpha-1-antitrypsin deficiency livers with grade 3+ or 4+ iron, P=0.02. In contrast, livers with hepatitis C showed a similar frequency of HFE mutations as the general population: C282Y=15%, H63D=27%. A rare S65C mutation and a novel A271S mutation were also found in this study; the latter patient had 4+ iron in the liver and later developed heart failure with cardiac iron. In conclusion, total H63D mutations were high (42%) in cirrhotics with alpha-1-antitrypsin deficiency and there was a significant association between HFE mutations and high levels of iron accumulation.