Long-term outcome after living donor liver transplantation for two cases of homozygous familial hypercholesterolemia from a heterozygous donor

Long-term outcomes of liver transplantation for homozygous familial hypercholesterolaemia in Australia and New Zealand

BACKGROUND AND AIMS

Homozygous familial hypercholesterolaemia (FH) causes severe cardiovascular disease from childhood. Conventional drug therapy is usually ineffective; lipoprotein apheresis (LA) is often required. Liver transplantation (LT) can correct the metabolic defect but is considered a treatment of last resort. Newer drugs including lomitapide and evinacumab might reduce the need for apheresis and LT. We sought to determine the long-term outcomes following LT in Australia and New Zealand.

METHODS

We analysed demographic, biochemical and clinical data from all patients in Australia and New Zealand who have received LT for homozygous FH, identified from the Australia and New Zealand Liver and Intestinal Transplant Registry.

RESULTS

Nine patients (five female; one deceased; seven aged between 3 and 6 years at the time of LT and two aged 22 and 26 years) were identified. Mean follow-up was 14.1 years (range 4-27). Baseline LDL-cholesterol off all treatment was 23 ± 4.1 mmol/L. Mean LDL-cholesterol on medical therapy (including maximal statin therapy in all patients, ezetimibe in three and LA in five) was 11 ± 5.7 mmol/L (p < 0.001). After LT, mean LDL-cholesterol was 2.6 ± 0.9 mmol/L (p = 0.004) with three patients remaining on statin therapy and none on LA. One patient died from acute myocardial infarction (AMI) three years after LT. Two patients required aortic valve replacement, more than 10 years after LT. The remaining six patients were asymptomatic after eight to 21 years of follow-up. No significant adverse events associated with immunosuppression were reported.

CONCLUSIONS

LT for homozygous FH was highly effective in achieving substantial long-term reduction in LDL-cholesterol concentrations in all nine patients. LT remains an option for severe cases of homozygous FH where drug therapy combined with apheresis is ineffective or unfeasible.

Guidelines for the Diagnosis and Treatment of Pediatric Familial Hypercholesterolemia 2022

As atherosclerosis begins in childhood, early diagnosis and treatment of familial hypercholesterolemia (FH) is considered necessary. The basic diagnosis of pediatric FH (under 15 years of age) is based on hyper-low-density lipoprotein (LDL) cholesterolemia and a family history of FH; however, in this guideline, to reduce overlooked cases, "probable FH" was established. Once diagnosed with FH or probable FH, efforts should be made to promptly provide lifestyle guidance, including diet. It is also important to conduct an intrafamilial survey, to identify family members with the same condition. If the level of LDL-C remains above 180 mg/dL, drug therapy should be considered at the age of 10. The first-line drug should be statin. Evaluation of atherosclerosis should be started using non-invasive techniques, such as ultrasound. The management target level is an LDL-C level of less than 140 mg/dL. If a homozygous FH is suspected, consult a specialist and determine the response to pharmacotherapy with evaluating atherosclerosis. If the response is inadequate, initiate lipoprotein apheresis as soon as possible.

Familial Hypercholesterolemia: A Narrative Review on Diagnosis and Management Strategies for Children and Adolescents

Familial hypercholesterolemia (FH) is a relatively common inherited disorder caused by deleterious mutation(s) in the low-density lipoprotein (LDL) receptor or its associated genes. Given its nature as a heritable disease, any useful screening scheme, including universal, and cascade screening, allows for the early identification of patients with FH. Another important aspect to note is that early diagnosis associated with appropriate treatment can promote better prognosis. However, most clinical diagnostic criteria for adults have adopted clinical elements, such as physical xanthomas and family history, both of which are usually obscure and/or difficult to obtain in children and adolescents. Moreover, LDL cholesterol levels fluctuating considerably during adolescence, hindering the timely diagnosis of FH. In addition, recent advancements in human genetics have revealed several types of FH, including conventional monogenic FH, polygenic FH caused by common single nucleotide variations (SNV) accumulation associated with elevated LDL cholesterol, and oligogenic FH with multiple deleterious genetic variations leading to substantially elevated LDL cholesterol. The aforementioned findings collectively suggest the need for amassing information related to genetics and imaging, in addition to classical clinical elements, for the accurate diagnosis of FH in this era of personalized medicine. The current narrative review summarizes the current status of the clinical and genetic diagnosis of FH in children and adolescents, as well as provide useful management strategies for FH in children and adolescents based on currently available clinical evidence.

Living Related Liver Transplantation for Metabolic Liver Diseases in Children

ABSTRACT

Metabolic liver diseases (MLDs) are a heterogeneous group of inherited conditions for which liver transplantation can provide definitive treatment. The limited availability of deceased donor organs means some who could benefit from transplant do not have this option. Living related liver transplant (LrLT) using relatives as donors has emerged as one solution to this problem. This technique is established worldwide, especially in Asian countries, with shorter waiting times and patient and graft survival rates equivalent to deceased donor liver transplantation. However, living donors are underutilized for MLDs in many western countries, possibly due to the fear of limited efficacy using heterozygous donors. We have reviewed the published literature and shown that the use of heterozygous donors for liver transplantation is safe for the majority of MLDs with excellent metabolic correction. The use of LrLT should be encouraged to complement deceased donor liver transplantation (DDLT) for treatment of MLDs.

Case Report: Liver Transplantation in Homozygous Familial Hypercholesterolemia (HoFH)-Long-Term Follow-Up of a Patient and Literature Review

Homozygous familial hypercholesterolemia (HoFH) is a rare inherited metabolic disorder, frequently leading to an early cardiovascular death if not adequately treated. Since standard medications usually fail to reduce LDL-cholesterol (LDL-C) levels satisfactorily, LDL-apheresis is a mainstay of managing HoFH patients but, at the same time, very burdensome and suboptimally effective. Liver transplantation (LT) has been previously shown to be a promising alternative. We report on a 14 year-long follow-up after LT in a HoFH patient. At the age of 4, the patient was referred to our institution because of the gradually increasing number of xanthomas on the knees, elbows, buttocks, and later the homozygous mutation c.1754T>C (p.Ile585Thr) on the LDL-receptor gene was confirmed. Despite subsequent intensive treatment with the combination of diet, statins, bile acid sequestrant, probucol, and LDL-apheresis, the patient developed valvular aortic stenosis and aortic regurgitation by 12 years. At 16 years, the patient successfully underwent deceased-donor orthotopic LT. Nine years post-LT, we found total regression of the cutaneous xanthomas and atherosclerotic plaques and with normal endothelial function. Fourteen years post-LT, his clinical condition remained stable, but LDL-C levels have progressively risen. In addition, a systematic review of the literature and guidelines on the LT for HoFH patients was performed. Six of the 17 identified guidelines did not take LT as a treatment option in consideration at all. But still the majority of guidelines suggest LT as an exceptional therapeutic option or as the last resort option when all the other treatment options are inadequate or not tolerated. Most of the observed patients had some kind of cardiovascular disease before the LT. In 76% of LT, the cardiovascular burden did not progress after LT. According to our experience and in several other reported cases, the LDL-C levels are slowly increasing over time post LT. Most of the follow-up data were short termed; only a few case reports have followed patients for 10 or more years after LT. LT is a feasible therapeutic option for HoFH patients, reversing atherosclerotic changes uncontrollable by conservative therapy, thus importantly improving the HoFH patient's prognosis and quality of life.

Function and Immunogenicity of Gene-corrected iPSC-derived Hepatocyte-Like Cells in Restoring Low Density Lipoprotein Uptake in Homozygous Familial Hypercholesterolemia

Gene correction of induced pluripotent stem cells (iPSCs) has therapeutic potential for treating homozygous familial hypercholesterolemia (HoFH) associated with low-density lipoprotein (LDL) receptor (LDLR) dysfunction. However, few data exist regarding the functional recovery and immunogenicity of LDLR gene-corrected iPSC-derived hepatocyte-like cells (HLCs) obtained from an HoFH patient. Therefore, we generated iPSC-derived HLCs from an HoFH patient harbouring a point mutation (NM_000527.4:c.901 G > T) in exon 6 of LDLR, and examined their function and immunogenicity. From the patient’s iPSCs, one homozygous gene-corrected HoFH-iPSC clone and two heterozygous clones were generated using the CRISPR/Cas9 method. Both types of iPSC-derived HLCs showed recovery of the function of LDL uptake in immunofluorescence staining analysis. Furthermore, these gene-corrected iPSC-derived HLCs showed little immunogenicity against the patient’s peripheral blood mononuclear cells in a cell-mediated cytotoxicity assay. These results demonstrate that LDL uptake of iPSC-derived HLCs from HoFH can be restored by gene correction without the appearance of further immunogenicity, suggesting that gene-corrected iPSC-derived HLCs are applicable to the treatment of HoFH.

Liver Transplantation for Homozygous Familial Hypercholesterolemia

Pharmacological treatments to decrease low-density lipoprotein (LDL) cholesterol (LDL-C) have limited effects on patients with homozygous familial hypercholesterolemia (HoFH). Since LDL receptors are located mainly in the liver, liver transplantation is considered to be the only way to correct the hepatic cholesterol metabolism abnormalities in HoFH. Liver transplantations, including those combined with heart transplantation, for HoFH have been increasing since 1984, making this a globally established therapeutic option for HoFH. Plasma LDL-C is reported to be dramatically lowered, by 80%, after transplantation, with the rapid regression of cutaneous and tendinous xanthomas. However, long-term cardiovascular benefits remain unclear. The major concerns about liver transplantation include surgical complications, the need for lifelong immunosuppressive therapy, and rejection. In addition, organ transplantations from deceased donors are extremely rare in Japan. We experienced two pediatric siblings with HoFH who received living-donor liver transplantations from their heterozygous parents. Their plasma LDL-C levels decreased immediately and stabilized at approximately 200 mg/dL. Both developed normally with the administration of lipid-lowering medications and have been free of severe problems for more than 10 years, to date, since transplantation. In Japan, where the shortage of deceased donors is critical, the combination of living-donor liver transplant from a heterozygous donor, that is, usually a parent, and medication is regarded as a valid therapeutic option for HoFH. Further studies and clinical experience are required to establish liver transplantation as a safe and effective treatment for HoFH.

Targeting microsomal triglyceride transfer protein and lipoprotein assembly to treat homozygous familial hypercholesterolemia

Homozygous familial hypercholesterolemia (HoFH) is a polygenic disease arising from defects in the clearance of plasma low-density lipoprotein (LDL), which results in extremely elevated plasma LDL cholesterol (LDL-C) and increased risk of atherosclerosis, coronary heart disease, and premature death. Conventional lipid-lowering therapies, such as statins and ezetimibe, are ineffective at lowering plasma cholesterol to safe levels in these patients. Other therapeutic options, such as LDL apheresis and liver transplantation, are inconvenient, costly, and not readily available. Recently, lomitapide was approved by the Federal Drug Administration as an adjunct therapy for the treatment of HoFH. Lomitapide inhibits microsomal triglyceride transfer protein (MTP), reduces lipoprotein assembly and secretion, and lowers plasma cholesterol levels by over 50%. Here, we explain the steps involved in lipoprotein assembly, summarize the role of MTP in lipoprotein assembly, explore the clinical and molecular basis of HoFH, and review pre-clinical studies and clinical trials with lomitapide and other MTP inhibitors for the treatment of HoFH. In addition, ongoing research and new approaches underway for better treatment modalities are discussed.

Liver transplantation for pediatric inherited metabolic disorders: Considerations for indications, complications, and perioperative management

LT is an effective therapeutic option for a variety of IEM. This approach can significantly improve the quality of life of patients who suffer from severe disease manifestations and/or life-threatening metabolic decompensations despite medical/dietary management. Due to the significant risks for systemic complications from surgical stressors, careful perioperative management is vital. Even after LT, some disorders require long-term dietary restriction, medical management, and monitoring of metabolites. Successful liver transplant for these complex disorders can be achieved with disease- and patient-specific strategies using a multidisciplinary approach. In this article, we review indications, complications, perioperative management, and long-term follow-up recommendations for IEM that are treatable with LT.

Living donor domino liver transplantation using a maple syrup urine disease donor: A case series of three children - The first report from Japan

As the priority of LD-Domino LT is the safety of the first recipient, limitations and technical difficulties in the second recipient often occur. The most technically challenging part of LD-Domino LT is the reconstruction of the vessels. For the reconstruction of HVs, the native HVs were exteriorized as far as possible using a CUSA because longer extensive HVs are essential for facilitating the reconstruction. At the back table, the HVs of the domino graft were sutured together, and the single cuff of the HVs was anastomosed to the IVC by joining the orifices. The HAs, the presence of insufficient length, and multiple vessels in the whole liver rendered the reconstruction more difficult. We determined the dividing sites of the vessels according to the preoperative 3D-CT findings obtained in two institutions. This is the first case series using grafts in DLT obtained from LDLT for patients with MSUD between two institutions. In conclusion, LD-Domino LT is a safe and feasible therapeutic option to expand the donor pool by technical refinement in the reconstruction of the second recipient. Further studies with a greater accumulation of patients and a longer follow-up will be necessary to establish LD-Domino LT using an MSUD donor.

Liver transplantation using grafts with rare metabolic disorders

Metabolic diseases that involve the liver represent a heterogeneous group of disorders. Apart from the metabolic defect, the subject's liver functions may be normal. With the increasing need for organs, livers from donors with metabolic diseases other than familial amyloid polyneuropathy might be possibly used for transplantation. However, whether such livers qualify as grafts and how they might impact recipient outcome are still unanswered questions. This review of the literature summarizes current experience in the use of such grafts in the context of cadaveric, domino, and living-related liver transplantation.

Liver transplantation for the treatment of homozygous familial hypercholesterolaemia in an era of emerging lipid-lowering therapies

Homozygous familial hypercholesterolaemia (FH) causes severe premature coronary artery disease because of very high levels of low density lipoprotein (LDL)-cholesterol. Standard lipid-lowering drugs and LDL-apheresis may not be sufficiently effective. Liver transplantation replaces defective LDL receptors and vastly improves the lipid profile, and we present the first report of an Australian adult to receive this treatment. Emerging drug treatments for FH may be alternatives to LDL-apheresis and transplantation, but long-term safety and efficacy data are lacking for all of these options.

Transplantation for inherited metabolic disorders of the liver

Inherited metabolic diseases that affect the liver are a frequent cause of liver failure in children, but other disorders more commonly cause liver failure in adulthood where they may present with chronic liver disease and, less frequently, with acute liver failure. The identification of the underlying genetic defect for many of these inherited disorders has improved our understanding of their pathophysiology and impacted on the indications for and timing of liver transplant, yielding better outcomes. Screening for disease and genetic counseling of family members may help prevent adverse outcomes in relatives of affected individuals. Timely liver transplantation offers correction of the inherited metabolic defect and restores liver function when medical therapy is not possible or when complications of liver disease arise. Some inherited metabolic diseases have their defect based in the liver and lead not to liver disease, but to other end organ damage. Earlier detection of these disorders may prevent pathological injury by treatment of the underlying disease or by pre-emptive liver transplant. In some instances where damage of other organs has already occurred, dual organ transplant with liver and another organ may be needed. Improvement in the technical aspects of performing liver transplantation and posttransplant care has led to better outcomes for those with inherited metabolic disorders of the liver.

Thyroid hormone reduces cholesterol via a non-LDL receptor-mediated pathway

Although studies in vitro and in hypothyroid animals show that thyroid hormone can, under some circumstances, modulate the actions of low-density lipoprotein (LDL) receptors, the mechanisms responsible for thyroid hormone's lipid-lowering effects are not completely understood. We tested whether LDL receptor (LDLR) expression was required for cholesterol reduction by treating control and LDLR-knockout mice with two forms of thyroid hormone T(3) and 3,5-diiodo-l-thyronine. High doses of both 3,5-diiodo-l-thyronine and T(3) dramatically reduced circulating total and very low-density lipoprotein/LDL cholesterol (∼70%) and were associated with reduced plasma T(4) level. The cholesterol reduction was especially evident in the LDLR-knockout mice. Circulating levels of both apolipoprotein B (apo)B48 and apoB100 were decreased. Surprisingly, this reduction was not associated with increased protein or mRNA expression of the hepatic lipoprotein receptors LDLR-related protein 1 or scavenger receptor-B1. Liver production of apoB was markedly reduced, whereas triglyceride production was increased. Thus, thyroid hormones reduce apoB lipoproteins via a non-LDLR pathway that leads to decreased liver apoB production. This suggests that drugs that operate in a similar manner could be a new therapy for patients with genetic defects in the LDLR.

Fatal cardiac atherosclerosis in a child 10 years after liver transplantation: a case report and a review

We hereby review liver transplantation for homozygous familial hypercholesterolemia and report the case of a 14-year-old girl presenting with severe bilateral coronary ostial stenosis and tight supra-valvular aortic narrowing 10 years after liver transplantation. Despite normalization of the lipids after liver transplantation, the patient showed evidence of severe cardiac atherosclerosis 10 years later and died of apparent sepsis.

Liver transplantation as a treatment option for three siblings with homozygous familial hypercholesterolemia

FH is a hereditary inherited disorder of cholesterol metabolism. Homozygous form of the disease associates severe form of atherosclerotic disease. Clinicians have been tried to inhibit the progression of the homozygous FH with medical and surgical treatment. We here present three siblings with homozygous FH who were successfully treated with liver transplantation.

Paediatric liver transplantation for metabolic disorders. Part 1: Liver-based metabolic disorders without liver lesions

Liver-based metabolic disorders account for 10 to 15% of the indications for paediatric liver transplantation. In the last three decades, important progress has been made in the understanding of these diseases, and new therapies have emerged. Concomitantly, medical and surgical innovations have lead to improved results of paediatric liver transplantation, patient survival nowadays exceeding 80% 10-year after surgery with close to normal quality of life in most survivors. This review is a practical update on medical therapy, indications and results of liver transplantation, and potential future therapies, for the main liver-based metabolic disorders in which paediatric liver transplantation may be considered. Part 1 focuses on metabolic based liver disorders without liver lesions, and part 2 on metabolic liver diseases with liver lesions.

Preemptive liver transplantation in a child with familial hypercholesterolemia

Familial hypercholesterolemia is an autosomal codominant disorder associated with markedly elevated plasma concentration of LDL-cholesterol and increased cardiovascular risk. Homozygous patients have rapid development of atherosclerosis with death from cardiovascular disease even in childhood. Life-long recurrent apheresis to reduce plasma LDL-cholesterol is considered the gold standard for treatment. Liver transplantation can be curative for this condition, but is usually only considered after the development of cardiovascular disease. We report a 5.5-yr-old child initially misdiagnosed with heterozygous familial hypercholesterolemia and treated by low-fat diet only. In view of persistent hypercholesterolemia and development of xanthomatosis, new molecular studies indicated the presence of two different mutations in the LDL receptor gene, with one being a deletion of two exons not identifiable with standard sequencing analysis. Recurrent plasma apheresis in combination with statins lowered, but did not normalize plasma LDL-cholesterol levels. It caused progressive reduction of the size of xanthomas and prevented the development of vascular complications. After two yr, liver transplantation normalized LDL-cholesterol levels and completely resolved the skin lesions. Preemptive liver transplantation is a definitive cure of familial homozygous hypercholesterolemia and might be more effective if performed before development of vascular complications.

Protein kinase C activation stabilizes LDL receptor mRNA via the JNK pathway in HepG2 cells

LDL is the most abundant cholesterol transport vehicle in plasma and a major prognostic indicator of atherosclerosis. Hepatic LDL receptors limit circulating LDL levels, since cholesterol internalized by the liver can be excreted. As such, mechanisms regulating LDL receptor expression in liver cells are appealing targets for cholesterol-lowering therapeutic strategies. Activation of HepG2 cells with phorbol esters enhances LDL receptor mRNA levels through transcriptional and posttranscriptional mechanisms. Here, we show that 12-O-tetradecanoyl-phorbol-13-acetate (TPA)-induced stabilization of receptor mRNA requires the activity of protein kinase C and is accompanied by activation of the major mitogen activated protein kinase pathways. Inhibitor studies demonstrated that receptor mRNA stabilization is independent of the extracellular signal-regulated kinase or p38(MAPK), but requires activation of the c-Jun N-terminal kinase (JNK). An essential role for JNK in stabilizing receptor mRNA was further confirmed through small interfering RNA (siRNA) experiments and by activating JNK through two protein kinase C-independent mechanisms. Finally, prolonged JNK activation increased steady-state levels of receptor mRNA and protein, and significantly enhanced cellular LDL-binding activity. These data suggest that JNK may play an important role in posttranscriptional control of LDL receptor expression, thus constituting a novel mechanism to enhance plasma LDL clearance by liver cells.

Monogenic pediatric dyslipidemias: classification, genetics and clinical spectrum

Monogenic disorders that cause abnormal levels of plasma cholesterol and triglycerides have received much attention due to their role in metabolic dysfunction and cardiovascular disease. While these disorders often present clinically during adulthood, some present most commonly in the pediatric population and can have serious consequences if misdiagnosed or untreated. This review provides an overview of monogenic lipid disorders that present with unusually high or low levels of plasma cholesterol and/or triglycerides during infancy, childhood and adolescence. Biochemical and genetic findings, clinical presentation and treatment options are discussed with an emphasis upon recent advances in our understanding and management of these monogenic disorders.