Metabolic changes and propensity for inflammation, fibrosis, and cancer in livers of mice lacking lysosomal acid lipase

Lysosomal acid lipase (LAL) is the sole lysosomal enzyme responsible for the degradation of cholesteryl esters and triacylglycerols at acidic pH. Impaired LAL activity leads to LAL deficiency (LAL-D), a severe and fatal disease characterized by ectopic lysosomal lipid accumulation. Reduced LAL activity also contributes to the development and progression of non-alcoholic fatty liver disease (NAFLD). To advance our understanding of LAL-related liver pathologies, we performed comprehensive proteomic profiling of livers from mice with systemic genetic loss of LAL (Lal-/-) and from mice with hepatocyte-specific LAL-D (hepLal-/-). Lal-/- mice exhibited drastic proteome alterations, including dysregulation of multiple proteins related to metabolism, inflammation, liver fibrosis, and cancer. Global loss of LAL activity impaired both acidic and neutral lipase activities and resulted in hepatic lipid accumulation, indicating a complete metabolic shift in Lal-/- livers. Hepatic inflammation and immune cell infiltration were evident, with numerous upregulated inflammation-related gene ontology biological process terms. In contrast, both young and mature hepLal-/- mice displayed only minor changes in the liver proteome, suggesting that loss of LAL solely in hepatocytes does not phenocopy metabolic alterations observed in mice globally lacking LAL. These findings provide valuable insights into the mechanisms underlying liver dysfunction in LAL-D and may help in understanding why decreased LAL activity contributes to NAFLD. Our study highlights the importance of LAL in maintaining liver homeostasis and demonstrates the drastic consequences of its global deficiency on the liver proteome and liver function.

A Form of Metabolic-Associated Fatty Liver Disease Associated with a Novel LIPA Variant

BACKGROUND

The LIPA gene on chromosome 10q23.31 contains 10 exons and encodes lipase A, the lysosomal acid lipase (LAL) containing 399 amino acids. Pathogenic variants in the LIPA result in autosomal recessive Wolman disease and cholesteryl ester storage disease (CESD). Here, we report a novel missense variant (NM_001127605.3:c.928T>A, p.Trp310Arg) of LIPA in an Iranian family with fatty liver disease identified by whole-exome sequencing and confirmed by Sanger sequencing.

METHODS

A 28-year-old woman referred with lean NASH cirrhosis and extremely high cholesterol levels. Fatty liver disease was found in six of her family members using vibration-controlled transient elastography (VCTE). Baseline routine laboratory tests were performed and whole-exome sequencing and confirmation by Sanger sequencing were done.

RESULTS

The index case had severe dyslipidemia and cirrhosis despite a body mass index of 21.09 kg/m2 . Six other family members had dyslipidemia and fatty liver or cirrhosis. A homozygous missense variant (NM_001127605.3:c.928T>A, p.Trp310Arg) of LIPA which caused LAL-D was found to be associated with fatty liver disease and/or cirrhosis.

CONCLUSION

A homozygous missense variant (NM_001127605.3:c.928T>A, p.Trp310Arg) of the LIPA gene which caused LAL-D was found to be associated with dyslipidemia, fatty liver disease and/or cirrhosis in six members of an Iranian family. These results should be confirmed by functional studies and extending the study to at least three families.

Hormone-sensitive lipase deficiency affects the expression of SR-BI, LDLr, and ABCA1 receptors/transporters involved in cellular cholesterol uptake and efflux and disturbs fertility in mouse testis

Hormone-sensitive lipase (HSL) hydrolyse acylglycerols, cholesteryl and retinyl esters. HSL is a key lipase in mice testis, as HSL deficiency results in male sterility. The present work study the effects of the deficiency and lack of HSL on the localization and expression of SR-BI, LDLr, and ABCA1 receptors/transporters involved in uptake and efflux of cholesterol in mice testis, to determine the impact of HSL gene dosage on testis morphology, lipid homeostasis and fertility. The results of this work show that the lack of HSL in mice alters testis morphology and spermatogenesis, decreasing sperm counts, sperm motility and increasing the amount of Leydig cells and lipid droplets. They also show that there are differences in the localization of HSL, SR-BI, LDLr and ABCA1 in HSL+/+, HSL+/- and HSL-/- mice. The deficiency or lack of HSL has effects on protein and mRNA expression of genes involved in lipid metabolisms in mouse testis. HSL-/- testis have augmented expression of SR-BI, LDLr, ABCA1 and LXRβ, a critical sterol sensor that regulate multiple genes involved in lipid metabolism; whereas LDLr expression decreased in HSL+/- mice. Plin2, Abca1 and Ldlr mRNA levels increased; and LXRα (Nr1h3) and LXRβ (Nr1h2) decreased in testis from HSL-/- compared with HSL+/+; with no differences in Scarb1. Together these data suggest that HSL deficiency or lack in mice testis induces lipid homeostasis alterations that affect the cellular localization and expression of key receptors/transporter involved in cellular cholesterol uptake and efflux (SR-BI, LDRr, ABCA1); alters normal cellular function and impact fertility.

Defective Lysosomal Lipolysis Causes Prenatal Lipid Accumulation and Exacerbates Immediately after Birth

Cholesterol and fatty acids are essential lipids that are critical for membrane biosynthesis and fetal organ development. Cholesteryl esters (CE) are degraded by hormone-sensitive lipase (HSL) in the cytosol and by lysosomal acid lipase (LAL) in the lysosome. Impaired LAL or HSL activity causes rare pathologies in humans, with HSL deficiency presenting less severe clinical manifestations. The infantile form of LAL deficiency, a lysosomal lipid storage disorder, leads to premature death. However, the importance of defective lysosomal CE degradation and its consequences during early life are incompletely understood. We therefore investigated how defective CE catabolism affects fetus and infant maturation using Lal and Hsl knockout (-/-) mouse models. This study demonstrates that defective lysosomal but not neutral lipolysis alters placental and fetal cholesterol homeostasis and exhibits an initial disease pathology already in utero as Lal-/- fetuses accumulate hepatic lysosomal lipids. Immediately after birth, LAL deficiency exacerbates with massive hepatic lysosomal lipid accumulation, which continues to worsen into young adulthood. Our data highlight the crucial role of LAL during early development, with the first weeks after birth being critical for aggravating LAL deficiency.

Lysosomal acid lipase deficiency in Brazilian children: a case series

OBJECTIVE

To describe the demographic, clinical, laboratory and molecular characteristics of patients with lysosomal acid lipase deficiency.

METHODS

A retrospective review of the medical records of children with the disease.

RESULTS

Seven children with lysosomal acid lipase deficiency (5 male; 2 female); 6 were mixed race, and 1 was black. The mean ages at the first onset of symptoms and at diagnosis were 5.0 years (4 months to 9 years) and 6.9 years (3-10 years), respectively. Symptom manifestations at onset were: 3 patients had abdominal pain, one had bone/joint pain due to rickets, and 1 had chronic diarrhea and respiratory insufficiency due to interstitial pneumonitis. One was asymptomatic, and clinical suspicion arose due to hepatomegaly. Six patients had hepatomegaly, and none had splenomegaly. Two patients were siblings. Enzymatic assay and molecular analysis confirmed the diagnoses. Genetic analysis revealed a rare pathogenic variant (p.L89P) in three patients, described only once in medical literature and never described in Brazil. None of those patients were related to each other. Lysosomal acid lipase deficiency was previously described as an autosomal recessive disease, but three patients were heterozygous and undoubtedly had the disease (low enzyme activity, suggestive lab findings and clinical symptoms).

CONCLUSION

This case series supports that lysosomal acid lipase deficiency can present with highly heterogeneous signs and symptoms among patients, but it should be considered in children presenting with gastrointestinal symptoms associated with dyslipidemia. We describe a rare variant in three non-related patients that may suggest a Brazilian genotype for lysosomal acid lipase deficiency.

Reduced lysosomal acid lipase activity: A new marker of liver disease severity across the clinical continuum of non-alcoholic fatty liver disease?

Lysosomal acid lipase (LAL) plays a key role in intracellular lipid metabolism. Reduced LAL activity promotes increased multi-organ lysosomal cholesterol ester storage, as observed in two recessive autosomal genetic diseases, Wolman disease and Cholesterol ester storage disease. Severe liver steatosis and accelerated liver fibrosis are common features in patients with genetic LAL deficiency. By contrast, few reliable data are available on the modulation of LAL activity in vivo and on the epigenetic and metabolic factors capable of regulating its activity in subjects without homozygous mutations of the Lipase A gene. In the last few years, a less severe and non-genetic reduction of LAL activity was reported in children and adults with non-alcoholic fatty liver disease (NAFLD), suggesting a possible role of LAL reduction in the pathogenesis and progression of the disease. Patients with NAFLD show a significant, progressive reduction of LAL activity from simple steatosis to non-alcoholic steatohepatitis and cryptogenic cirrhosis. Among cirrhosis of different etiologies, those with cryptogenic cirrhosis show the most significant reductions of LAL activity. These findings suggest that the modulation of LAL activity may become a possible new therapeutic target for patients with more advanced forms of NAFLD. Moreover, the measurement of LAL activity may represent a possible new marker of disease severity in this clinical setting.

Identification of rare diseases by screening a population selected on the basis of routine pathology results-the PATHFINDER project: lysosomal acid lipase/cholesteryl ester storage disease substudy

AIMS

Lysosomal acid lipase deficiency (LALD) is an autosomal recessive disorder of cholesterol ester storage associated with hepatic disease, cirrhosis and accelerated atherosclerosis. Its prevalence in the general population, patients with dyslipidaemia and raised transaminases is unclear. This study attempted to identify the prevalence of LALD from patients with abnormal results in laboratory databases.

METHODS

Electronic laboratory databases were interrogated to identify from clinical biochemistry records patients with a phenotype of low high-density lipoprotein-cholesterol (≤0.85 mmol/L; 33 mg/dL) and with elevated alanine or aspartate transaminases (≥60 IU/L) on one occasion or more over a 3-year time interval. Patients were recalled, and a dried blood spot sample was collected for lysosomal acid lipase determination by a fluorimetric enzyme assay. Histopathology databases of liver biopsies were interrogated for patients with features of 'microvesicular cirrhosis' or 'cryptogenic cirrhosis' in the report. Histological blocks were sampled, and samples were analysed by next-generation sequencing for the presence of mutations in the LAL gene.

RESULTS

Samples were obtained from 1825 patients with dyslipidaemia and elevated transaminases. No cases of LALD were identified. Liver biopsies were obtained from six patients. DNA extraction was successful from four patients. Two patients were homozygous for the LAL c.46A>C;p.Thr16Pro unclassified variant in exon 2.

CONCLUSIONS

Pathology databases hold routine information that can be used to identify patients with specific patterns of results or those who had biopsies to allow targeted testing for possible causes of disease. Biochemical screening suggests that the gene frequency of LAL deficiency in adults is less than 1 in 100.

Lysosomal acid lipase and lipid metabolism: new mechanisms, new questions, and new therapies

PURPOSE OF REVIEW

Lysosomal acid lipase (LAL), encoded by the LIPA gene, is an essential lysosomal enzyme that hydrolyzes cholesteryl ester and triglyceride delivered to the lysosome. This review highlights the novel pathophysiological role of LAL, the functional genomic discoveries of LIPA as a risk locus for coronary heart diseases (CHD), and the clinical advance in therapies for LAL deficiency.

RECENT FINDINGS

The essential role of LAL in lipid metabolism has been confirmed in human and mice with LAL deficiency. In humans, loss-of-function mutations of LIPA cause rare lysosomal disorders, Wolman disease, and cholesteryl ester storage disease, in which LAL enzyme replacement therapy has shown significant benefits in a phase 3 clinical trial. Recent studies have revealed the role of LAL-mediated lysosomal lipolysis in regulating macrophage M2 polarization, lipid mediator production, VLDL secretion, lysosomal function and autophagy, extracellular degradation of aggregated-LDL, and adipose tissue lipolysis. Genome-wide association studies and functional genomic studies have identified LIPA as a risk locus for CHD, but the causal variants and mechanisms remain to be determined.

SUMMARY

Despite years of research, our understanding of LAL is incomplete. Future studies will continue to focus on the key pathophysiological functions of LAL in health and diseases including CHD.

Mexican consensus on lysosomal acid lipase deficiency diagnosis

INTRODUCTION

Lysosomal acid lipase deficiency (LAL-D) causes progressive cholesteryl ester and triglyceride accumulation in the lysosomes of hepatocytes and monocyte-macrophage system cells, resulting in a systemic disease with various manifestations that may go unnoticed. It is indispensable to recognize the deficiency, which can present in patients at any age, so that specific treatment can be given. The aim of the present review was to offer a guide for physicians in understanding the fundamental diagnostic aspects of LAL-D, to successfully aid in its identification.

METHODS

The review was designed by a group of Mexican experts and is presented as an orienting algorithm for the pediatrician, internist, gastroenterologist, endocrinologist, geneticist, pathologist, radiologist, and other specialists that could come across this disease in their patients. An up-to-date review of the literature in relation to the clinical manifestations of LAL-D and its diagnosis was performed. The statements were formulated based on said review and were then voted upon. The structured quantitative method employed for reaching consensus was the nominal group technique.

RESULTS

A practical algorithm of the diagnostic process in LAL-D patients was proposed, based on clinical and laboratory data indicative of the disease and in accordance with the consensus established for each recommendation.

CONCLUSION

The algorithm provides a sequence of clinical actions from different studies for optimizing the diagnostic process of patients suspected of having LAL-D.

IMPORTANCE OF LIVER BIOPSY IN THE DIAGNOSIS OF LYSOSOMAL ACID LIPASE DEFICIENCY: A CASE REPORT

OBJECTIVE

To describe a case of cholesteryl ester storage disease (CESD) and discuss the importance of liver biopsy for diagnosis.

CASE DESCRIPTION

A female patient, aged two years and ten months, presented with an increased abdominal volume following hepatomegaly for four months. Abdominal ultrasound demonstrated hepatomegaly and hepatic steatosis. Laboratory tests showed elevated liver serum enzymes and dyslipidemia. Liver biopsy was consistent with CESD.

COMMENTS

Although measuring enzyme activity is the gold standard for CESD diagnosis, liver biopsy is very helpful when investigating suspected cases of CESD, particularly upon other differential diagnoses to be considered.

Lysosomal acid lipase deficiency in all siblings of the same parents

We present 4 normal-weight sibling children with lysosomal acid lipase deficiency (LAL-D). LAL-D was considered in the differential diagnosis based on the absence of secondary causes and primary inherited traits for their marked hyperlipidemia, together with unexplained hepatic transaminase elevation. Residual lysosomal acid lipase activity confirmed the diagnosis. DNA sequencing of LIPA indicated that the siblings were compound heterozygotes (c.894G>A and c.428+1G>A). This case describes the unusual occurrence of all offspring from the same nonconsanguineous mother and father inheriting compound heterozygosity of a recessive trait and the identification of an apparently unique LIPA mutation (c.428+1G>A). It highlights the collaborative effort between a lipidologist and gastroenterologist in developing a differential diagnosis leading to the confirmatory diagnosis of this rare, life-threatening disease. With the availability of an effective enzyme replacement therapy (sebelipase alfa), LAL-D should be entertained in the differential diagnosis of children, adolescents, and young adults with idiopathic hyperlipidemia and unexplained hepatic transaminase elevation.

Rapid progression and mortality of lysosomal acid lipase deficiency presenting in infants

PURPOSE

The purpose of this study was to enhance understanding of lysosomal acid lipase deficiency (LALD) in infancy.

METHODS

Investigators reviewed medical records of infants with LALD and summarized data for the overall population and for patients with and without early growth failure (GF). Kaplan-Meier survival analyses were conducted for the overall population and for treated and untreated patients.

RESULTS

Records for 35 patients, 26 with early GF, were analyzed. Prominent symptom manifestations included vomiting, diarrhea, and steatorrhea. Median age at death was 3.7 months; estimated probability of survival past age 12 months was 0.114 (95% confidence interval (CI): 0.009-0.220). Among patients with early GF, median age at death was 3.5 months; estimated probability of survival past age 12 months was 0.038 (95% CI: 0.000-0.112). Treated patients (hematopoietic stem cell transplant (HSCT), n = 9; HSCT and liver transplant, n = 1) in the overall population and the early GF subset survived longer than untreated patients, but survival was still poor (median age at death, 8.6 months).

CONCLUSIONS

These data confirm and expand earlier insights on the progression and course of LALD presenting in infancy. Despite variations in the nature, onset, and severity of clinical manifestations, and treatment attempts, clinical outcome was poor.Genet Med 18 5, 452-458.

Clinical Features of Lysosomal Acid Lipase Deficiency

OBJECTIVE

The aim of this study was to characterize key clinical manifestations of lysosomal acid lipase deficiency (LAL D) in children and adults.

METHODS

Investigators reviewed medical records of LAL D patients ages ≥5 years, extracted historical data, and obtained prospective laboratory and imaging data on living patients to develop a longitudinal dataset.

RESULTS

A total of 49 patients were enrolled; 48 had confirmed LAL D. Mean age at first disease-related abnormality was 9.0 years (range 0-42); mean age at diagnosis was 15.2 years (range 1-46). Twenty-nine (60%) were male patients, and 27 (56%) were <20 years of age at the time of consent/assent. Serum transaminases were elevated in most patients with 458 of 499 (92%) of alanine aminotransferase values and 265 of 448 (59%) of aspartate aminotransferase values above the upper limit of normal. Most patients had elevated low-density lipoprotein (64% patients) and total cholesterol (63%) at baseline despite most being on lipid-lowering therapies, and 44% had high-density lipoprotein levels below the lower limit of normal. More than half of the patients with liver biopsies (n = 31, mean age 13 years) had documented evidence of steatosis (87%) and/or fibrosis (52%). Imaging assessments revealed that the median liver volume was ∼1.15 multiples of normal (MN) and median spleen volume was ∼2.2 MN. Six (13%) patients had undergone a liver transplant (ages 9-43.5 years).

CONCLUSION

This study provides the largest longitudinal case review of patients with LAL D and confirms that LAL D is predominantly a pediatric disease causing early and progressive hepatic dysfunction associated with dyslipidemia that often leads to liver failure and transplantation.

Reversal of advanced disease in lysosomal acid lipase deficient mice: a model for lysosomal acid lipase deficiency disease

Lysosomal acid lipase (LAL) is an essential enzyme that hydrolyzes triglycerides (TG) and cholesteryl esters (CE) in lysosomes. Mutations of the LIPA gene lead to Wolman disease (WD) and cholesterol ester storage disease (CESD). The disease hallmarks include hepatosplenomegaly and extensive storage of CE and/or TG. The effects of intravenous investigational enzyme therapy (ET) on survival and efficacy were evaluated in Lipa knock out, lal-/- mice with advanced disease using recombinant human LAL (rhLAL). Comparative ET was conducted with lower doses (weekly, 0.8 and 3.2mg/kg) beginning at 16 weeks (study 1), and with higher dose (10mg/kg) in early (8-weeks), middle (16-weeks) and late (24-weeks) disease stages (study 2). In study 1, rhLAL extended the life span of lal-/- mice in a dose dependent manner by 52 (0.8 mg/kg) or 94 (3.2mg/kg) days. This was accompanied by partial correction of cholesterol and TG levels in spleen and liver. In study 2, the high dose resulted in a significant improvement in organ size (liver, spleen and small intestine) and tissue histology as well as significant decreases in cholesterol and TG in all three groups. In the treated livers and spleens the cholesterol and TG levels were reduced to below treatment initiation levels indicating a reversal of disease manifestations, even in advanced disease. ET diminished liver fibrosis and macrophage proliferation. These results show that LAL deficiency can be improved biochemically and histopathologically by various dosages of ET, even in advanced disease.

[Wolman disease with novel mutation of LIPA gene in a Chinese infant]

OBJECTIVE

To explore the clinical characteristics of Wolman disease and diagnostic methods using enzymatic and molecular analysis.

METHOD

Lysosomal acid lipase activity was measured using 4-methylumbelliferyl oleate in the leukocytes of an infant suspected of Wolman disease and LIPA gene mutational analysis was performed by PCR and direct sequencing in the proband and his parents. After the diagnosis was confirmed, the clinical, biochemical, radiological and histopathological findings in this case of Wolman disease were retrospectively reviewed.

RESULT

The sixteen-day-old boy was failing to thrive with progressive vomiting, abdominal distention and hepatosplenomegaly. Abdominal X-ray revealed adrenal calcifications which were confirmed on abdominal CT scan. Xanthomatosis were observed on enlarged liver, spleen and lymph nodes during abdominal surgery. Liver and lymph node biopsy showed foamy histiocytes. The lysosomal acid lipase activity in leukocytes was 3.5 nmol/(mg·h) [control 35.5 - 105.8 nmol/(mg·h)]. Serum chitotriosidase activity was 315.8 nmol/(ml·h) [control 0 - 53 nmol/(ml·h)]. The patient was homozygote for a novel insert mutation allele c.318 ins T, p. Phe106fsX4 in exon 4 on LIPA gene. His both parents were carriers of the mutation.

CONCLUSION

The clinical features of Wolman disease include early onset of vomiting, abdominal distention, growth failure, hepatosplenomegaly and bilateral adrenal calcification after birth. A plain abdominal X-ray film should be taken to check for the typical pattern of adrenal calcification in suspected cases of Wolman disease. The enzymatic and molecular analyses of lysosomal acid lipase can confirm the diagnosis of Wolman disease.

Distinctive histopathological features that support a diagnosis of cholesterol ester storage disease in liver biopsy specimens

AIMS

  To identify reliable criteria with which to improve the diagnosis of lysosomal acid lipase (LAL) deficiency of the cholesterol ester storage disease (CESD) type in liver biopsies.

METHODS AND RESULTS

  We analysed a series of 16 liver biopsies of LAL deficiency of the CESD type confirmed by enzyme testing and DNA sequencing. The biopsy appearances were compared with those of biopsies of other causes of fatty liver. A predominantly microvesicular steatosis in CESD patients could not be reliably distinguished from other causes of fatty liver with cytosolic lipid accumulation in fixed paraffin-embedded tissues routinely stained with haematoxylin and eosin. The presence of luminal (cathepsin D) and membrane lysosomal markers [lysosomal-associated membrane protein (LAMP)1, LAMP2, and lysosomal integral membrane protein 2] around the lipid vacuoles facilitated the diagnosis of CESD in fixed paraffin-embedded material. Additional diagnostic clues included autofluorescent detection of ceroid induction in storage macrophages and the absence of lipopigment in hepatocytes. Stored liquid crystals of cholesteryl esters, which are associated with Maltese cross-type birefringence, were best appreciated in unfixed biopsy samples.

CONCLUSIONS

  The pathological diagnosis of CESD requires a high index of suspicion, and can be rapidly and effectively appreciated at the light microscopy level, even in routine fixed paraffin-embedded liver samples with immuohistochemical staining for lysosomal markers.

Wolman disease/cholesteryl ester storage disease: efficacy of plant-produced human lysosomal acid lipase in mice

Lysosomal acid lipase (LAL) is an essential enzyme that hydrolyzes triglycerides (TGs) and cholesteryl esters (CEs) in lysosomes. Genetic LAL mutations lead to Wolman disease (WD) and cholesteryl ester storage disease (CESD). An LAL-null (lal(-/-)) mouse model resembles human WD/CESD with storage of CEs and TGs in multiple organs. Human LAL (hLAL) was expressed in Nicotiana benthamiana using the GENEWARE expression system (G-hLAL). Purified G-hLAL showed mannose receptor-dependent uptake into macrophage cell lines (J774E). Intraperitoneal injection of G-hLAL produced peak activities in plasma at 60 min and in the liver and spleen at 240 min. The t(1/2) values were: approximately 90 min (plasma), approximately 14 h (liver), and approximately 32 h (spleen), with return to baseline by approximately 150 h in liver and approximately 200 h in spleen. Ten injections of G-hLAL (every 3 days) into lal(-/-) mice produced normalization of hepatic color, decreases in hepatic cholesterol and TG contents, and diminished foamy macrophages in liver, spleen, and intestinal villi. All injected lal(-/-) mice developed anti-hLAL protein antibodies, but suffered no adverse events. These studies demonstrate the feasibility of using plant-expressed, recombinant hLAL for the enzyme therapy of human WD/CESD with general implications for other lysosomal storage diseases.

The role of mannosylated enzyme and the mannose receptor in enzyme replacement therapy

Lysosomal acid lipase (LAL) is the critical enzyme for the hydrolysis of triglycerides (TGs) and cholesteryl esters (CEs) in lysosomes. LAL defects cause Wolman disease (WD) and CE storage disease (CESD). An LAL null (lal-/-) mouse model closely mimics human WD/CESD, with hepatocellular, Kupffer cell and other macrophage, and adrenal cortical storage of CEs and TGs. The effect on the cellular targeting of high-mannose and complex oligosaccharide-type oligosaccharide chains was tested with human LAL expressed in Pichia pastoris (phLAL) and CHO cells (chLAL), respectively. Only chLAL was internalized by cultured fibroblasts, whereas both chLAL and phLAL were taken up by macrophage mannose receptor (MMR)-positive J774E cells. After intraperitoneal injection into lal-/- mice, phLAL and chLAL distributed to macrophages and macrophage-derived cells of various organs. chLAL was also detected in hepatocytes. Ten injections of either enzyme over 30 d into 2- and 2.5-mo-old lal-/- mice produced normalization of hepatic color, decreased liver weight (50%-58%), and diminished hepatic cholesterol and TG storage. Lipid accumulations in macrophages were diminished with either enzyme. Only chLAL cleared lipids in hepatocytes. Mice double homozygous for the LAL and MMR deficiences (lal-/-;MMR-/-) showed phLAL uptake into Kupffer cells and hepatocytes, reversal of macrophage histopathology and lipid storage in all tissues, and clearance of hepatocytes. These results implicate MMR-independent and mannose 6-phosphate receptor-independent pathways in phLAL uptake and delivery to lysosomes in vivo. In addition, these studies show specific cellular targeting and physiologic effects of differentially oligosaccharide-modified human LALs mediated by MMR and that lysosomal targeting of mannose-terminated glycoproteins occurs and storage can be eliminated effectively without MMR.

Familial massive tendon xanthomatosis with decreased high-density lipoprotein-mediated cholesterol efflux

We experienced a family with novel massive tendon xanthomatosis which can be excluded from known disease causing xanthomatosis. The proband was a 58-year-old man who had necrosis in his massive Achilles tendon xanthoma. Three of 5 brothers including him and his nephew had the same clinical phenotype. The systemic tendon xanthomatosis became apparent around 30 years of their age. The proband and his elder brother had mild elevations of serum total cholesterol level (251 and 228 mg/dL, respectively). The low-density lipoprotein receptor activity of the proband's lymphocytes was normal. Neither plant sterol nor cholestanol level was increased in the proband's plasma. Magnetic resonance image of the proband's Achilles tendon demonstrated a massive expansion of the soft tissue with salami sausage-like appearance in his heels (50 mm in thickness). The physiological function of macrophages (MPhi) from the patients was investigated to clarify the mechanism for the formation of xanthomatosis. There was no significant difference in the uptake of oxidized low-density lipoprotein between the proband's MPhi and the control. High-density lipoprotein 3-mediated cholesterol efflux from the patients' MPhi (n = 2) was significantly reduced compared with the controls (n = 3), whereas there was no difference in apolipoprotein (apo) A-I-mediated cholesterol efflux between the patients' MPhi and the controls. Furthermore, there was no reduction of the messenger RNA levels of ATP-binding cassette transporter 1 (ABCA1), which is involved in apo A-I-mediated cholesterol efflux, in the proband's MPhi compared with the control. The present study demonstrates that the mechanism for the formation of novel familial massive tendon xanthomatosis may be, at least in part, associated with decreased high-density lipoprotein 3, but not free apo A-I-mediated cholesterol efflux from MPhi in vivo.

Severe chronic diarrhea and weight loss in cholesteryl ester storage disease: A case report

AIM: An inherited deficiency of human lysosomal acid lipase (LAL) results in the rare conditions of Wolman disease and cholesteryl ester storage disease (CESD). We want to present the rare case of CESD in an adult.

METHODS: We report about an adult female patient with severe chronic diarrhea and weight loss as a consequence of CESD. Clinical examination revealed signs of malabsorption and slightly elevated liver enzymes.

RESULTS: Histopathologic changes in the liver tissue and DNA sequence analysis confirmed the diagnosis of CESD due to homozygosity for the most common CESD mutation, a G934A splice site defect encoded by exon 8 of the lysosomal acid lipase (LIPA) gene.

CONCLUSION: It is the first case in the literature with diarrhea as a putative symptom of CESD in adult patients.

MRI of Fat Distribution in a Mouse Model of Lysosomal Acid Lipase Deficiency

OBJECTIVE

We assessed the use of MRI in the evaluation of abdominal fat distribution in a lysosomal acid lipase (LAL)-deficient mouse model.

MATERIALS AND METHODS

LAL-deficient mice are born with a normal fat distribution but over time deplete the fat stores in the subcutaneous and retroperitoneal tissues and accumulate fat in the liver, spleen, and bowel. Four MRI studies of LAL-deficient mice and control mice were obtained with 3-T T1-weighted spin-echo images and volume segmentation processing to create parameters for the study of fat distribution: intraabdominal adipose tissue-subcutaneous adipose tissue (IAT/SAT) ratio, liver volume, reproductive fat, and retroperitoneal fat. MRI adiposity parameters in LAL-deficient mice were compared with those in control mice. Adiposity volumes calculated on MRI were compared with those calculated at autopsy.

RESULTS

Statistically significant differences were found between LAL-deficient and control mice for IAT/SAT ratio (p=0.0336), liver volume (p=0.0336), and reproductive fat (p=0.0336), and a statistically significant trend was found for retroperitoneal fat (p=0.0514). No statistically significant difference was found between adiposity volumes calculated on MRI and adiposity volumes found at autopsy (all p >0.2).

CONCLUSION

Use of an in vivo model showed MRI techniques to be accurate in predicting visceral adiposity. LAL-deficient mice provided a unique model showing a pattern of adipose distribution that is markedly different from that in control mice, and MRI may provide a means of evaluating therapeutic interventions sequentially.

Wolman disease and cholesteryl ester storage disease diagnosed by histological and ultrastructural examination of intestinal and liver biopsy

Deficient activity of lysosomal acid lipase (LAL) results in massive accumulation of cholesteryl esters and triglycerides in most tissues of the body. The deficiency state is expressed in two major phenotypes: Wolman disease (WD) and cholesteryl ester storage disease (CESD). WD occurs in infancy and is nearly always fatal before the age of 1 year, whereas CESD can be more benign and may not be detected until adulthood. Since there are no specific routine laboratory observations that suggest these metabolic diseases, diagnosis is based on the clinical picture combined with LAL deficiency in cultured skin fibroblasts or peripheral lymphocytes. Both disorders are rather rare, considering that about a hundred of cases have been described up to now. This study describes the histological and ultrastructural aspects disclosed by intestinal or liver biopsy in three cases of WD and in two cases of CESD. Furthermore, it emphasizes the role of morphological findings in pointing the diagnosis towards a metabolic storage disease.

Lysosomal acid lipase deficiency: correction of lipid storage by adenovirus-mediated gene transfer in mice

Lysosomal acid lipase (LAL) is the essential enzyme for hydrolysis of triglycerides (TGs) and cholesteryl esters (CEs) in lysosomes. Its deficiency produces two human phenotypes: Wolman disease (WD) and cholesteryl ester storage disease (CESD). The LAL null (lal(-/-)) mouse mimicks aspects of human WD and CESD. The potential for gene therapy of LAL deficiency was tested with first-generation adenoviral vectors containing human LAL cDNA (Ad-hLAL) by intravenous injection into lal(-/-) mice. Compared with phosphate-buffered saline-injected controls, the mice receiving Ad-hLAL had increased hepatic LAL activity, decreased hepatomegaly, and normalization of histopathology. hLAL protein and mRNA were detected by immunohistochemical staining and in situ hybridization in hepatic parenchymal and sinusoid lining cells, splenic sinusoidal cells, lung macrophages, and adrenal cortical cells. Mice showed TG reductions in liver, spleen, and small intestine of 68, 54, and 50%, respectively, and cholesterol reductions of 55, 52, and 34%, respectively, at 20 days postinjection. These studies provide the basis for the use of gene therapy, in the form of gene transfer via intravenously administered adenovirus, to correct deficiency states, such as WD and CESD, and histopathology of a variety of tissues.

Enzyme therapy for lysosomal acid lipase deficiency in the mouse

Lysosomal acid lipase (LAL) is the critical enzyme for the hydrolysis of the triglycerides (TG) and cholesteryl esters (CE) delivered to lysosomes. Its deficiency produces two human phenotypes, Wolman disease (WD) and cholesteryl ester storage disease (CESD). A targeted disruption of the LAL locus produced a null (lal( -/-)) mouse model that mimics human WD/CESD. The potential for enzyme therapy was tested using mannose terminated human LAL expressed in Pichia pastoris (phLAL), purified, and administered by tail vein injections to lal( -/-) mice. Mannose receptor (MR)-dependent uptake and lysosomal targeting of phLAL were evidenced ex vivo using competitive assays with MR-positive J774E cells, a murine monocyte/macrophage line, immunofluorescence and western blots. Following (bolus) IV injection, phLAL was detected in Kupffer cells, lung macrophages and intestinal macrophages in lal( -/-) mice. Two-month-old lal( -/-) mice received phLAL (1.5 U/dose) or saline injections once every 3 days for 30 days (10 doses). The treated lal( -/-) mice showed nearly complete resolution of hepatic yellow coloration; hepatic weight decreased by approximately 36% compared to PBS-treated lal( -/-) mice. Histologic analyses of numerous tissues from phLAL-treated mice showed reductions in macrophage lipid storage. TG and cholesterol levels decreased by approximately 50% in liver, 69% in spleen and 50% in small intestine. These studies provide feasibility for LAL enzyme therapy in human WD and CESD.

Lysosomal acid lipase-deficient mice: depletion of white and brown fat, severe hepatosplenomegaly, and shortened life span

Lysosomal acid lipase (LAL) is essential for the hydrolysis of triglycerides (TG) and cholesteryl esters (CE) in lysosomes. A mouse model created by gene targeting produces no LAL mRNA, protein, or enzyme activity. The lal-/- mice appear normal at birth, survive into adulthood, and are fertile. Massive storage of TG and CE is observed in adult liver, adrenal glands, and small intestine. The age-dependent tissue and gross progression in this mouse model are detailed here. Although lal-/- mice can be bred to give homozygous litters, they die at ages of 7 to 8 months. The lal-/- mice develop enlargement of a single mesenteric lymph node that is full of stored lipids. At 6;-8 months of age, the lal-/- mice have completely absent inguinal, interscapular, and retroperitoneal white adipose tissue. In addition, brown adipose tissue is progressively lost. The plasma free fatty acid levels are significantly higher in lal-/- mice than age-matched lal+/+ mice, and plasma insulin levels were more elevated upon glucose challenge. Energy intake was also higher in lal-/- male mice, although age-matched body weights were not significantly altered from age-matched lal+/+ mice. Early in the disease course, hepatocytes are the main storage cell in the liver; by 3;-8 months, the lipid-stored Kupffer cells progressively fill the liver. The involvement of macrophages throughout the body of lal-/- mice provide evidence for a critical nonappreciated role of LAL in cellular cholesterol and fatty acid metabolism, adipocyte differentiation, and fat mobilization.

Wolman's disease--a case report

Wolman's disease is a rare autosomal recessive lysosomal storage disorder. We report a case, which we identified with foamy histiocytes in bone marrow and adrenal calcification in radiological imaging. The diagnosis can be made on minimal investigation when clinically suspected. But cytogenetic study is required to substantiate the diagnosis further.

Compound heterozygosity for a Wolman mutation is frequent among patients with cholesteryl ester storage disease

Cholesteryl ester storage disease and Wolman disease are rare autosomal recessive lipoprotein-processing disorders caused by mutations in the gene encoding human lysosomal acid lipase. Thus far we have elucidated the genetic defects in 15 unrelated CESD patients. Seven were homozygotes for the prevalent hLAL exon 8 splice junction mutation which results in incomplete exon skipping, while eight probands were compound heterozygotes for E8SJM and a rare mutation on the second chromosome. In this report, we describe the molecular basis of CESD in three compound heterozygous subjects of Czech and Irish origin. RFLP and DNA sequence analysis revealed that they were heteroallelic for the common G(934)-->A substitution in exon 8 of the hLAL gene and a mutation which, if inherited on both alleles, would be expected to result in complete loss of enzyme activity and to cause Wolman disease. In patients A. M. and J. J., two nucleotide deletions in exons 7 and 10 were detected, involving a T at position 722, 723, or 724 and a G in a stretch of five guanosines at positions 1064;-1068 of the hLAL cDNA. Both mutations result in premature termination of protein translation at residues 219 and 336, respectively, and in the production of truncated, inactive enzymes. Subject D. H., in contrast, is a compound heterozygote for the Arg(44)-->Stop mutation previously described in a French CESD proband. Combined with data in the literature, our results demonstrate that compound heterozygosity for a mutation causing Wolman disease is common among cholesteryl ester storage disease patients.

Wolman's disease diagnosed by intestinal biopsy

We describe a fatal case of Wolman's disease in a 5-month-old Italian infant with severe gastrointestinal symptoms in whom the diagnosis was made from intestinal biopsy findings at the age of 3 1/2 months. Abdominal CT scan, elevated blood acid phosphatase levels and histologic findings confirmed the diagnosis.

Morphological characteristics of lipid accumulation in liver-constituting cells of acid lipase deficiency rats (Wolman's disease model rats)

Lysosomal acid lipase is a hydrolase essential for the intracellular degradation of cholesteryl esters and triglycerides. In the laboratory, rats with congenital deficiency of lysosomal acid lipase and marked accumulation of cholesteryl ester, cholesterol free and triglyceride in livers (Wolman's disease rat or Yoshida rat) that corresponded to human Wolman's disease were found and maintained. The morphological characteristics of accumulated lipids in the livers of affected rats were examined also. Many small lipid droplets and lipid crystals were found in the cytoplasms of hepatocytes and ED1-positive and ED2-positive foamy Kupffer's cells, respectively. Electron microscopically, many electron-lucent lipid droplets with limiting membrane were found in hepatocytes. Foamy Kupffer's cells had many multivesicular bodies with limiting membrane, which contained crivilinear bodies, lipid droplets and crystal clefts. At areas of aggregation of foamy Kupffer's cells forming islets, there were many desmin-positive Ito cells. Small lipid droplets with limiting membrane were also found in the cytoplasm of Ito cells and endothelial cells. These findings, which were obtained by morphological methods, indicated that triglyceride and both cholesteryl ester and free cholesterol accumulated in lipolysosomes mainly in hepatocytes and Kupffer's cells, respectively, and suggest that lysosomal acid lipase could participate in dissolution of the membrane.

Targeted disruption of the mouse lysosomal acid lipase gene: long-term survival with massive cholesteryl ester and triglyceride storage

Lysosomal acid lipase (LAL) is essential for the hydrolysis of the triglycerides and cholesteryl esters in lysosomes. Its deficiency produces two phenotypes, a severe infantile-onset variant, Wolman disease (WD), and a later onset variant, cholesteryl ester storage disease (CESD). A mouse model with a LAL null mutation was produced by targeting disruption of the mouse gene. Homozygote knockout mice (lal -/lal-) produce no LAL mRNA, protein or enzyme activity. The lal-/lal- mice are born in Mendelian ratios, are normal appearing at birth, and follow normal development into adulthood. However, massive accumulation of triglycerides and cholesteryl esters occurs in several organs. By 21 days, the liver develops a yellow-orange color and is approximately 1.5-2.0x larger than normal. The accumulated cholesteryl esters and triglycerides are approximately 30-fold greater than normal. The lal+/lal- mice have approximately 50% of normal LAL activity and do not show lipid accumulation. Male and female lal-/lal- mice are fertile and can be bred to produce progeny. This mouse model is a phenotypic model of human CESD, and a biochemical and histopathologic mimic of human WD. The lal-/lal- mice provide a model to determine the role of LAL in lipid metabolism and the pathogenesis of its deficiency states.

[Wolman disease]

BACKGROUND

Wolman disease is a severe disease associated with hepatosplenomegaly and adrenal calcifications; it is nearly always fatal in the first year of life.

CASE REPORT

A boy was born to consanguineous parents. His weight was 3,500 g, height 53 cm. Hepatomegaly was observed at the age of 26 days; he also had vomiting and watery stools with failure to thrive. Diagnosis of Wolman disease was suspected due to family history. Two sisters had died at the age of 3 months without precise diagnosis; both had abdominal distension, hepatosplenomegaly, anemia and inanition; CT scan showed calcifications of adrenal glands in one of them that had been attributed to adrenal hemorrhage. Investigations in our patient showed no adrenal calcification, hepatomegaly without splenomegaly, anemia (Hb: 8 g/100 ml). Liver biopsy showed enlarged and vacuolated parenchymal and Kupffer cells but the marrow did not contain foam cells. Acid lipase deficiency was demonstrated in cultured skin fibroblasts, permitting prenatal diagnosis in a further sib.

CONCLUSION

This case of Wolman disease was the first seen in Tunisia; it was inherited as an autosomal recessive disorder; this patient, as two of his sisters, died during the first 6 months of life.

A large intracranial xanthoma in familial hypercholesterolemia

Intracranial xanthomata occurring in patients with familial hypercholesterolemia are very rare. We present a young woman with a large intracranial xanthoma. The patient was treated for a familial hyperlipoproteinemia type IIa. MRI and morphological features are shown and discussed on reviewing the literature.

Cellular uptake and catabolism of high-density-lipoprotein triacylglycerols in human cultured fibroblasts: degradation block in neutral lipid storage disease

High-density lipoprotein (HDL)-[3H]triolein (i.e. [3H]triolein incorporated into reconstituted HDL) was taken up by cultured fibroblasts through an apparently saturable process, competitively inhibited by non-labelled HDL and independent of the LDL receptor. Using 125I-HDL and HDL-[3H]triolein, binding experiments (at 0 degrees C) followed by a short-time 'chase' at 37 degrees C showed that 125I radioactivity was rapidly released in the culture medium (as trichloroacetic acid-precipitable material), whereas 3H radioactivity remained associated with the cell. The cell-associated HDL-[3H]triolein was rapidly degraded in normal fibroblasts, and the liberated [3H]oleic acid was incorporated into newly biosynthesized phospholipids. In Wolman-disease fibroblasts HDL-[3H]triolein was degraded at a normal rate, and thus independently of the lysosomal compartment. In contrast, the degradation of HDL-[3H]triolein was blocked in fibroblasts from Neutral Lipid Storage Disease (NLSD), similarly to that of endogenously biosynthesized triacylglycerols [Radom, Salvayre, Nègre, Maret and Douste-Blazy (1987) Eur. J. Biochem. 164, 703-708]. Trypsin-treated HDL-[3H]triolein was also taken up by cells and degraded quite similarly to HDL-[3H]triolein. In conclusion, all these data taken together suggest that HDL-[3H]triolein is: (i) associated with the cell through a process independent of intact apolipoprotein (apo) As, thus probably independent of an apoA-receptor-mediated uptake; (ii) internalized by cells, whereas 125I-apoAs are released in the culture medium; (iii) directed to the same non-lysosomal catabolic pool (blocked in NLSD) as for endogenously biosynthesized triacylglycerols.

Wolman disease: morphological, clinical and genetic studies on the first Scandinavian cases

On the Aland Islands, a 1-month-old girl was diagnosed as having Wolman disease. The diagnosis was confirmed neurochemically; a decreased activity of acid lipase was noted in the proband and her parents had typical carrier values. This is the first Scandinavian case reported. The skin biopsy revealed cytoplasmic accumulations identical to those noted in two sibs who highly probably had Wolman disease during the 1950s. Both these sibs died at the age of about 3 months and presented a heavy accumulation of lipid material in lymph nodes, spleen, adrenal glands, liver, gut, and also some pathological alterations in other organs. Electron microscopic findings from deparaffinized samples showed cytoplasmic accumulation of lipid material similar to that noted in Wolman disease. Genealogical analyses revealed that the index families had ancestors from the same restricted area and also common ancestors during the 17th century. The parents of the two affected sibs were born on a small island and were related in many different ways. On the basis of genealogical studies and other genetic investigations performed, the importance of founder and drift effect for manifestations of rare hereditary disorder in isolates is stressed.

Genetic lipid storage disease with lysosomal acid lipase deficiency in rats

We describe a new animal model of a genetic lipid storage disease analogous to human Wolman's disease. Affected Donryu rats, who inherited the disease in an autosomal recessive mode, manifested marked hepatosplenomegaly, lymph node enlargement, and thickened, dilated intestine. Morphologically, many characteristic foam cells were observed in livers and spleens. No adrenal calcification could be found in affected rats. Biochemical studies on spleen and liver tissues showed massive accumulation of esterified cholesterol and triglycerides, and deficiency of acid lipase for [14C]-cholesteryl oleate. This animal model could contribute greatly to the clarification of the physiological and pathological roles of lysosomal acid lipase in the metabolism of lipoproteins and cholesterol, and of the pathogenesis of atherosclerosis.

Cerebrotendinous xanthomatosis

Cerebrotendinous xanthomatosis is a rare familial lipid storage that is caused by a defect in bile acid synthesis. As a result, large amounts of cholestanol, the 5 alpha-dihydro derivative of cholesterol, accumulate in virtually every tissue, with extra large deposits in the nervous system, xanthomas, and bile. Clinically, progressive neurologic dysfunction, tendon xanthomas, cataracts, and atherosclerosis are commonly found. Because chenodeoxycholic acid, a primary bile acid, is almost devoid from the bile, replacement therapy (750 mg per day) suppresses abnormal bile acid synthesis, reduces elevated cholestanol synthesis and plasma concentrations, and improves neurologic function in this disease.