Recurrence of lecithin cholesterol acyltransferase deficiency after kidney transplantation

A systematic review of the natural history and biomarkers of primary Lecithin:Cholesterol Acyltransferase (LCAT) deficiency

Syndromes associated with LCAT deficiency, a rare autosomal recessive condition, include fish-eye disease (FED) and familial LCAT deficiency (FLD). FLD is more severe and characterized by early and progressive chronic kidney disease (CKD). No treatment is currently available for FLD, but novel therapeutics are under development. Furthermore, although biomarkers of LCAT deficiency have been identified, their suitability to monitor disease progression and therapeutic efficacy is unclear, as little data exist on the rate of progression of renal disease. Here, we systematically review observational studies of FLD, FED, and heterozygous subjects, which summarize available evidence on the natural history and biomarkers of LCAT deficiency, in order to guide the development of novel therapeutics. We identified 146 FLD and 53 FED patients from 219 publications, showing that both syndromes are characterized by early corneal opacity and markedly reduced HDL-C levels. Proteinuria/hematuria were the first signs of renal impairment in FLD, followed by rapid decline of renal function. Furthermore, LCAT activity toward endogenous substrates and the percentage of circulating esterified cholesterol (EC%) were the best discriminators between these two syndromes. In FLD, higher levels of total, non-HDL, and unesterified cholesterol were associated with severe CKD. We reveal a nonlinear association between LCAT activity and EC% levels, in which subnormal levels of LCAT activity were associated with normal EC%. This review provides the first step toward the identification of disease biomarkers to be used in clinical trials and suggests that restoring LCAT activity to subnormal levels may be sufficient to prevent renal disease progression.

LCAT deficiency: a systematic review with the clinical and genetic description of Mexican kindred

BACKGROUND

LCAT (lecithin-cholesterol acyltransferase) deficiency is characterized by two distinct phenotypes, familial LCAT deficiency (FLD) and Fish Eye disease (FED). This is the first systematic review evaluating the ethnic distribution of LCAT deficiency, with particular emphasis on Latin America and the discussion of three Mexican-Mestizo probands.

METHODS

A systematic review was conducted following the PRISMA (Preferred Reporting Items for Systematic review and Meta-Analysis) Statement in Pubmed and SciELO. Articles which described subjects with LCAT deficiency syndromes and an assessment of the ethnic group to which the subject pertained, were included.

RESULTS

The systematic review revealed 215 cases (154 FLD, 41 FED and 20 unclassified) pertaining to 33 ethnic/racial groups. There was no association between genetic alteration and ethnicity. The mean age of diagnosis was 42 ± 16.5 years, with fish eye disease identified later than familial LCAT deficiency (55 ± 13.8 vs. 41 ± 14.7 years respectively). The prevalence of premature coronary heart disease was significantly greater in FED vs. FLD. In Latin America, 48 cases of LCAT deficiency have been published from six countries (Argentina (1 unclassified), Brazil (38 FLD), Chile (1 FLD), Columbia (1 FLD), Ecuador (1 FLD) and Mexico (4 FLD, 1 FED and 1 unclassified). Of the Mexican probands, one showed a novel LCAT mutation.

CONCLUSIONS

The systematic review shows that LCAT deficiency syndromes are clinically and genetically heterogeneous. No association was confirmed between ethnicity and LCAT mutation. There was a significantly greater risk of premature coronary artery disease in fish eye disease compared to familial LCAT deficiency. In FLD, the emphasis should be in preventing both cardiovascular disease and the progression of renal disease, while in FED, cardiovascular risk management should be the priority. The LCAT mutations discussed in this article are the only ones reported in the Mexican- Amerindian population.

Combined liver-kidney transplantation for rare diseases

Combined liver and kidney transplantation (CLKT) is indicated in patients with failure of both organs, or for the treatment of end-stage chronic kidney disease (ESKD) caused by a genetic defect in the liver. The aim of the present review is to provide the most up-to-date overview of the rare conditions as indications for CLKT. They are major indications for CLKT in children. However, in some of them (e.g., atypical hemolytic uremic syndrome or primary hyperoxaluria), CLKT may be required in adults as well. Primary hyperoxaluria is divided into three types, of which type 1 and 2 lead to ESKD. CLKT has been proven effective in renal function replacement, at the same time preventing recurrence of the disease. Nephronophthisis is associated with liver fibrosis in 5% of cases and these patients are candidates for CLKT. In alpha 1-antitrypsin deficiency, hereditary C3 deficiency, lecithin cholesterol acyltransferase deficiency and glycogen storage diseases, glomerular or tubulointerstitial disease can lead to chronic kidney disease. Liver transplantation as a part of CLKT corrects underlying genetic and consequent metabolic abnormality. In atypical hemolytic uremic syndrome caused by mutations in the genes for factor H, successful CLKT has been reported in a small number of patients. However, for this indication, CLKT has been largely replaced by eculizumab, an anti-C5 antibody. CLKT has been well established to provide immune protection of the transplanted kidney against donor-specific antibodies against class I HLA, facilitating transplantation in a highly sensitized recipient.

Novel Missense LCAT Gene Mutation Associated with an Atypical Phenotype of Familial LCAT Deficiency in Two Portuguese Brothers

Familial lecithin-cholesterol acyltransferase deficiency (FLD) is a rare recessive disorder of cholesterol metabolism, caused by loss-of-function mutations in the human LCAT gene, leading to alterations in the lipid/lipoprotein profile, with extremely low HDL levels.The classical FLD phenotype is characterized by diffuse corneal opacification, haemolytic anaemia and proteinuric chronic kidney disease (CKD); an incomplete form, only affecting the corneas, has been reported in a few families worldwide.We describe an intermediate phenotype of LCAT deficiency, with CKD preceding the development of corneal clouding, in two Portuguese brothers apparently homozygous for a novel missense LCAT gene mutation. The atypical phenotype, the diagnosis of membranous nephropathy in the proband's native kidney biopsy, the late-onset and delayed recognition of the corneal opacification, the co-segregation with Gilbert syndrome and the late recurrence of the primary disease in kidney allograft all contributed to obscure the diagnosis of an LCAT deficiency syndrome for many years.A major teaching point is that on standard light microscopy examination the kidney biopsies of patients with LCAT deficiency with residual enzyme activity may not show significant vacuolization and may be misdiagnosed as membranous nephropathy. The cases of these two patients also illustrate the importance of performing detailed physical examination in young adults presenting with proteinuric CKD, as the most important clue to the diagnosis of FLD is in the eyes.

A novel homozygous mutation causing lecithin-cholesterol acyltransferase deficiency in a proband of Romanian origin with a record of extreme gestational hyperlipidemia

A patient from Romania with extraordinarily high total cholesterol levels and clinical and biochemical features consistent with familial lecithin-cholesterol acyltransferase deficiency is reported. The genetic analysis performed on our proband showed a novel homozygous mutation on codon 119 of lecithin-cholesterol acyltransferase gene that causes the substitution of glycine by aspartate. The same mutation, also in homozygosis, was observed in her older sister, whereas his brother presented it in heterozygosis.

Sequential kidney-liver transplantation from the same living donor for lecithin cholesterol acyl transferase deficiency

BACKGROUND

Lecithin cholesterol acyl transferase (LCAT) deficiency is a rare autosomal recessive disorder of lipoprotein metabolism that results in end-stage renal disease (ESRD) necessitating transplantation. As LCAT is produced in the liver, combined kidney and liver transplantation was proposed to cure the clinical syndrome of LCAT deficiency.

METHODS

A 29-year-old male with ESRD secondary to LCAT deficiency underwent a sequential kidney-liver transplantation from the same living donor (LD). One year following the kidney transplant, auxiliary partial orthotopic liver transplant (APOLT) of a left lateral segment from the same donor was performed.

RESULTS

At 5 years follow-up, there have been no major complications, readmissions, or rejection episodes. Serum lipid abnormalities recurred within the first year, but liver and kidney allograft function remains intact.

CONCLUSION

Few cases of sequential transplantation from the same LD have been performed in adults. This is the first APOLT and multi-organ transplant performed for LCAT deficiency. Sequential organ transplant from the same LD for ESRD secondary to a metabolic disorder of the liver is feasible in adults and should be further investigated.

Familial lecithin:cholesterol acyltransferase deficiency: First-in-human treatment with enzyme replacement

BACKGROUND

Humans with familial lecithin:cholesterol acyltransferase (LCAT) deficiency (FLD) have extremely low or undetectable high-density lipoprotein cholesterol (HDL-C) levels and by early adulthood develop many manifestations of the disorder, including corneal opacities, anemia, and renal disease.

OBJECTIVE

To determine if infusions of recombinant human LCAT (rhLCAT) could reverse the anemia, halt progression of renal disease, and normalize HDL in FLD.

METHODS

rhLCAT (ACP-501) was infused intravenously over 1 hour on 3 occasions in a dose optimization phase (0.3, 3.0, and 9.0 mg/kg), then 3.0 or 9.0 mg/kg every 1 to 2 weeks for 7 months in a maintenance phase. Plasma lipoproteins, lipids, LCAT levels, and several measures of renal function and other clinical labs were monitored.

RESULTS

LCAT concentration peaked at the end of each infusion and decreased to near baseline over 7 days. Renal function generally stabilized or improved and the anemia improved. After infusion, HDL-C rapidly increased, peaking near normal in 8 to 12 hours; analysis of HDL particles by various methods all revealed rapid sequential disappearance of preβ-HDL and small α-4 HDL and appearance of normal α-HDL. Low-density lipoprotein cholesterol increased more slowly than HDL-C. Of note, triglyceride routinely decreased after meals after infusion, in contrast to the usual postprandial increase in the absence of rhLCAT infusion.

CONCLUSIONS

rhLCAT infusions were well tolerated in this first-in-human study in FLD; the anemia improved, as did most parameters related to renal function in spite of advanced disease. Plasma lipids transiently normalized, and there was rapid sequential conversion of small preβ-HDL particles to mature spherical α-HDL particles.

Familial lecithin-cholesterol acyltransferase (LCAT) deficiency; a differential of proteinuria

Background: Lecithin cholesterol acyltransferase (LCAT) is an important enzyme in cholesterol metabolism that is involved in the esterification of cholesterol. A lack of this enzyme results in deranged metabolic pathways that are not completely understood, resulting in abnormal deposition of lipids in several organs. Clinically, it manifests with proteinuria, dyslipidemia and corneal opacity with progressive chronic kidney disease resulting in end-stage renal disease.

Case Presentation: We herein present a case of a 30-year-old male with proteinuria that was not responsive to empiric management with angiotensin-converting enzyme (ACE) inhibitors and oral steroids. Physical examination revealed corneal ring opacity involving both eyes. Urinalysis revealed an active sediment. The 24-h proteinuria was 3.55 grams. Family history was positive for renal disease and dyslipidemia. Viral serology for human immunodeficiency virus (HIV), hepatitis C virus (HCV) and hepatitis B virus (HBV) were negative. Serum complements were normal and anti-nuclear antibody (ANA) was negative. We elected for a renal biopsy that revealed characteristic features of LCAT deficiency. The diagnosis of LCAT deficiency was established with a combination of clinical and pathological findings.

Conclusions: Currently renal prognosis is poor but conservative management with ACE inhibitors and lipid lowering therapy in addition to steroids has been shown to retard progression to end-stage renal disease. However newer therapies such as gene replacement and recombinant LCAT replacement are being studied with promising preliminary results.

Nephrotic syndrome caused by immune-mediated acquired LCAT deficiency

Lecithin-cholesterol acyltransferase (LCAT) is an enzyme involved in maintaining cholesterol homeostasis. In familial LCAT deficiency (FLD), abnormal lipid deposition causes renal injury and nephrotic syndrome, frequently progressing to ESRD. Here, we describe a 63-year-old Japanese woman with no family history of renal disease who presented with nephrotic syndrome. The laboratory data revealed an extremely low level of serum HDL and undetectable serum LCAT activity. Renal biopsy showed glomerular lipid deposition with prominent accumulation of foam cells, similar to the histologic findings of FLD. In addition, she had subepithelial electron-dense deposits compatible with membranous nephropathy, which are not typical of FLD. A mixing test and coimmunoprecipitation study demonstrated the presence of an inhibitory anti-LCAT antibody in the patient's serum. Immunohistochemistry and immunofluorescence detected LCAT along parts of the glomerular capillary walls, suggesting that LCAT was an antigen responsible for the membranous nephropathy. Treatment with steroids resulted in complete remission of the nephrotic syndrome, normalization of serum LCAT activity and HDL level, and disappearance of foam cell accumulation in renal tissue. In summary, inhibitory anti-LCAT antibody can lead to glomerular lesions similar to those observed in FLD.

Approach to the patient with extremely low HDL-cholesterol

Patients with extremely low high-density lipoprotein-cholesterol (HDL-C) pose distinct challenges to clinical diagnosis and management. Confirmation of HDL-C levels below 20 mg/dl in the absence of severe hypertriglyceridemia should be followed by evaluation for secondary causes, such as androgen use, malignancy, and primary monogenic disorders, namely, apolipoprotein A-I mutations, Tangier disease, and lecithin-cholesterol acyltransferase deficiency. Global cardiovascular risk assessment is a critical component of comprehensive evaluation, although the association between extremely low HDL-C levels and atherosclerosis remains unclear. Therapeutic interventions address reversible causes of low HDL-C, multiorgan abnormalities that may accompany primary disorders and cardiovascular risk modification when appropriate. Uncommon encounters with patients exhibiting extremely low HDL-C provide an opportunity to directly observe the role of HDL metabolism in atherosclerosis and beyond the vascular system.

Lecithin: Cholesterol Acyltransferase (LCAT) Deficiency: renal lesions with early graft recurrence

Familial lecithin:cholesterol acyltransferase (LCAT) deficiency is a rare metabolic disease with lipid deposition in several organs. The authors report a man with hypertension and proteinuria. Renal biopsy revealed glomerular changes, including peculiar thrombus-like deposits, consistent with LCAT deficiency. He was found to be compound heterozygous for two mutations of the LCAT gene. He received a kidney graft from his father. The authors also describe LCAT deficiency-related lesions in the explanted native kidneys and in biopsies at 2 days, 6 weeks, and 1 year after transplantation. The morphology of this disease is characteristic, and the diagnosis should be suspected from the ultrastructural findings.

Effect of recombinant human lecithin cholesterol acyltransferase infusion on lipoprotein metabolism in mice

Lecithin cholesterol acyl transferase (LCAT) deficiency is associated with low high-density lipoprotein (HDL) and the presence of an abnormal lipoprotein called lipoprotein X (Lp-X) that contributes to end-stage renal disease. We examined the possibility of using LCAT an as enzyme replacement therapy agent by testing the infusion of human recombinant (r)LCAT into several mouse models of LCAT deficiency. Infusion of plasma from human LCAT transgenic mice into LCAT-knockout (KO) mice rapidly increased HDL-cholesterol (C) and lowered cholesterol in fractions containing very-low-density lipoprotein (VLDL) and Lp-X. rLCAT was produced in a stably transfected human embryonic kidney 293f cell line and purified to homogeneity, with a specific activity of 1850 nmol/mg/h. Infusion of rLCAT intravenously, subcutaneously, or intramuscularly into human apoA-I transgenic mice showed a nearly identical effect in increasing HDL-C approximately 2-fold. When rLCAT was intravenously injected into LCAT-KO mice, it showed a similar effect as plasma from human LCAT transgenic mice in correcting the abnormal lipoprotein profile, but it had a considerably shorter half-life of approximately 1.23 ± 0.63 versus 8.29 ± 1.82 h for the plasma infusion. rLCAT intravenously injected in LCAT-KO mice crossed with human apolipoprotein (apo)A-I transgenic mice had a half-life of 7.39 ± 2.1 h and increased HDL-C more than 8-fold. rLCAT treatment of LCAT-KO mice was found to increase cholesterol efflux to HDL isolated from mice when added to cells transfected with either ATP-binding cassette (ABC) transporter A1 or ABCG1. In summary, rLCAT treatment rapidly restored the normal lipoprotein phenotype in LCAT-KO mice and increased cholesterol efflux, suggesting the possibility of using rLCAT as an enzyme replacement therapy agent for LCAT deficiency.

Lecithin: cholesterol acyltransferase--from biochemistry to role in cardiovascular disease

PURPOSE OF REVIEW

We discuss the latest findings on the biochemistry of lecithin : cholesterol acyltransferase (LCAT), the effect of LCAT on atherosclerosis, clinical features of LCAT deficiency, and the impact of LCAT on cardiovascular disease from human studies.

RECENT FINDINGS

Although there has been much recent progress in the biochemistry of LCAT and its effect on high-density lipoprotein metabolism, its role in the pathogenesis of atherosclerosis is still not fully understood. Studies from various animal models have revealed a complex interaction between LCAT and atherosclerosis that may be modified by diet and by other proteins that modify lipoproteins. Furthermore, the ability of LCAT to lower apoB appears to be the best way to predict its effect on atherosclerosis in animal models. Recent studies on patients with LCAT deficiency have shown a modest but significant increase in incidence of cardiovascular disease consistent with a beneficial effect of LCAT on atherosclerosis. The role of LCAT in the general population, however, has not revealed a consistent association with cardiovascular disease.

SUMMARY

Recent research findings from animal and human studies have revealed a potential beneficial role of LCAT in reducing atherosclerosis but additional studies are necessary to better establish the linkage between LCAT and cardiovascular disease.