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Molecular and histological traits of reduced lysosomal acid lipase activity in the fatty liver.

ABSTRACT: Recent studies demonstrated reduced blood lysosomal acid lipase (LAL) activity in patients with nonalcoholic fatty liver disease (NAFLD). We aimed to verify hepatic LAL protein content and activity in in vitro and in vivo models of fat overload and in NAFLD patients. LAL protein content and activity were firstly evaluated in Huh7 cells exposed to high-glucose/high-lipid (HGHL) medium and in the liver of C57BL/6 mice fed with high-fat diet (HFD) for 4 and 8 months. LAL protein was also evaluated by immunohistochemistry in liver biopsies from 87 NAFLD patients and 10 controls, and correlated with hepatic histology. Huh7 cells treated with HGHL medium showed a significant reduction of LAL activity, which was consistent with reduced LAL protein levels by western blotting using an antibody towards the N-term of the enzyme. Conversely, antibodies towards the C-term of the enzyme evidenced LAL accumulation, suggesting a post-translational modification that masks the LAL N-term epitope and affects enzymatic activity. Indeed, we found a high rate of ubiquitination and extra-lysosomal localization of LAL protein in cells treated with HGHL medium. Consistent with these findings, inhibition of proteasome triggered dysfunctional LAL accumulation and affected LAL activity. Accumulation of ubiquitinated/dysfunctional LAL was also found in the liver of HFD fed mice. In NAFLD patients, hepatic levels of non-ubiquitinated/functional LAL were lower than in controls and inversely correlated with disease activity and some of the hallmarks of reduced LAL. Fat overload leads to LAL ubiquitination and impairs its function, possibly reducing hepatic fat disposal and promoting NAFLD activity.

SUBMITTER: Carotti S

PROVIDER: S-EPMC8602623 | biostudies-literature |

REPOSITORIES: biostudies-literature

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Reduced Lysosomal Acid Lipase Activity in Blood and Platelets Is Associated With Nonalcoholic Fatty Liver Disease.

Project description:ObjectivesTo investigate whether blood total lysosomal acid lipase activity (BT-LAL) levels are uniquely associated with the noncirrhotic and cirrhotic stages of nonalcoholic fatty liver disease (NAFLD) and with protection from NAFLD in metabolically/genetically predisposed subjects and a normal liver. To clarify which enzyme-carrying circulating cells are involved in reduced BT-LAL of NAFLD.MethodsIn a cross-sectional study, BT-LAL was measured by a fluorigenic method in patients with NAFLD (n = 118), alcoholic (n = 116), and hepatitis C virus-related disease (n = 49), in 103 controls with normal liver and in 58 liver transplant recipients. Intracellular platelet and leukocyte LAL was measured in 14 controls and 28 patients with NAFLD.ResultsCompared with controls, (i) BT-LAL and LAL in platelets, but not in leukocytes, were progressively reduced in noncirrhotic NAFLD and in nonalcoholic steatohepatitis-related cirrhosis; (ii) platelet and leukocyte counts did not differ in patients with noncirrhotic NAFLD; and (iii) BT-LAL did not differ in alcoholic and hepatitis C virus noncirrhotic patients. BT-LAL progressively increased in controls with metabolic syndrome features according to their PNPLA3 rs738409 steatosis-associated variant status (II vs IM vs MM), and their BT-LAL was higher than that of noncirrhotic NAFLD, only when carriers of the PNPLA3 unfavorable alleles were considered. Liver transplant recipients with de novo NAFLD compared with those without de novo NAFLD had lower BT-LAL.DiscussionLAL in blood and platelets is progressively and uniquely reduced in NAFLD according to disease severity. High BT-LAL is associated with protection from NAFLD occurrence in subjects with metabolic and genetic predisposition. Low LAL in platelets and blood could play a pathogenetic role in NAFLD.

| S-EPMC7145031 | biostudies-literature

Lysosomal Acid Lipase Activity Is Reduced Both in Cryptogenic Cirrhosis and in Cirrhosis of Known Etiology.

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| S-EPMC4878774 | biostudies-literature

Lysosomal acid lipase regulates fatty acid channeling in brown adipose tissue to maintain thermogenesis.

Project description:Lysosomal acid lipase (LAL) is the only known enzyme, which hydrolyzes cholesteryl esters and triacylglycerols in lysosomes of multiple cells and tissues. Here, we explored the role of LAL in brown adipose tissue (BAT). LAL-deficient (Lal-/-) mice exhibit markedly reduced UCP1 expression in BAT, modified BAT morphology with accumulation of lysosomes, and mitochondrial dysfunction, consequently leading to regular hypothermic events in mice kept at room temperature. Cold exposure resulted in reduced lipid uptake into BAT, thereby aggravating dyslipidemia and causing life threatening hypothermia in Lal-/- mice. Linking LAL as a potential regulator of lipoprotein lipase activity, we found Angptl4 mRNA expression upregulated in BAT. Our data demonstrate that LAL is critical for shuttling fatty acids derived from circulating lipoproteins to BAT during cold exposure. We conclude that inhibited lysosomal lipid hydrolysis in BAT leads to impaired thermogenesis in Lal-/- mice.

| S-EPMC5839464 | biostudies-literature

Lysosomal acid lipase deficiency: A rare inherited dyslipidemia but potential ubiquitous factor in the development of atherosclerosis and fatty liver disease.

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| S-EPMC9530988 | biostudies-literature

Lysosomal Acid Lipase Deficiency: Therapeutic Options.

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| S-EPMC7023879 | biostudies-literature

Rescue of lysosomal acid lipase deficiency in mice by AAV liver gene transfer

Project description:Lysosomal acid lipase deficiency (LAL-D) is an autosomal recessive disorder caused by mutation in LIPA gene, which results in fat accumulation in liver and spleen leading to multi-organ failure. The severe form of LAL-D (infantile-onset; ≤5% residual LAL activity), if left untreated, results in premature death within the first year of life due to failure to thrive and hepatic insufficiency. Enzyme replacement therapy is the only available supportive treatment consisting in weekly systemic injection of recombinant LAL. Here, we characterize a novel LAL-D mouse model and develop a curative gene therapy treatment based on the in vivo administration of recombinant AAV8 (rAAV8) vector encoding for human LIPA transgene under the control of hepatocyte-specific promoter. We define the minimal AAV dose required to rescue disease lethality and to produce and secrete sufficient LAL to correct cholesterol and triglycerides accumulation in liver, spleen, blood cells and plasma. Finally, using liver transcriptomic and biochemical analysis, we also show the impairment of mitochondria associated with LAL-D and its recovery by gene therapy. Overall, our in vivo gene therapy strategy achieves stable long-term LAL expression to correct disease phenotype in LAL-D mouse model and opens a new therapeutic option for LAL-D patients.

2024-06-01 | GSE252742 | GEO

Molecular mechanism of recombinant liver fatty acid binding protein's antioxidant activity.

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| S-EPMC2781316 | biostudies-literature

Clinical Features of Lysosomal Acid Lipase Deficiency.

Project description: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.

| S-EPMC4645959 | biostudies-literature

Recent insights into lysosomal acid lipase deficiency.

Project description:Lysosomal acid lipase (LAL) is the sole enzyme known to degrade neutral lipids in the lysosome. Mutations in the LAL-encoding LIPA gene lead to rare lysosomal lipid storage disorders with complete or partial absence of LAL activity. This review discusses the consequences of defective LAL-mediated lipid hydrolysis on cellular lipid homeostasis, epidemiology, and clinical presentation. Early detection of LAL deficiency (LAL-D) is essential for disease management and survival. LAL-D must be considered in patients with dyslipidemia and elevated aminotransferase concentrations of unknown etiology. Enzyme replacement therapy, sometimes in combination with hematopoietic stem cell transplantation (HSCT), is currently the only therapy for LAL-D. New technologies based on mRNA and viral vector gene transfer are recent efforts to provide other effective therapeutic strategies.

| S-EPMC7614602 | biostudies-literature

Opening a window on lysosomal acid lipase deficiency: Biochemical, molecular, and epidemiological insights.

Project description:Lysosomal acid lipase deficiency (LAL-D) is a multi-organ autosomal recessive disease caused by mutations in LIPA. We reviewed data from 681 samples (white blood cells [WBC] n = 625, fibroblasts = 30, liver = 4, amniocytes = 13, chorionic villus = 9) received for analysis of lysosomal acid lipase (LAL) activity over a 15-year period. LIPA sequencing was performed in 49 patients with reduced (n = 26) or deficient (n = 23) LAL activity. The Exome Aggregation Consortium and Genome Aggregation Database dataset were used for LAL-D prevalence calculations. LAL WBC activity was reduced in 67 patients (10.72%) and deficient in 37 (5.92%). The average of LAL activity ± margin of error (CI 95%) was 19.32 ± 0.86 pmol/min/mg for reduced activity patients and 5.90 ± 1.42 pmol/min/mg for deficient patients. The average age at diagnosis for LAL-D was 23.6 years with several patients older than age 30. The correlation between the age at diagnosis and LAL activity showed a significant moderate direct correlation (Pearson's r = 0.46, P < 0.005). Homozygous or compound heterozygous mutations were identified in 9 out of 23 patients with deficient results (detection rate 39.1%). The average LAL activity in molecularly confirmed patients was 4.02 ± 2.02 pmol/min/mg protein, while in molecularly negative patients was 13.886 ± 1.49 pmol/min/mg (P < 0.0001). Twenty-two different mutations were identified including two novel variants (c.309C>A and c.856G>C). A carrier frequency of approximately 1 in 350 was inferred. LAL activity in WBC is a validated tool for LAL-D diagnosis. Higher residual enzymatic activity might result in a milder phenotype leading to diagnosis delay. A cut-off below 12 pmol/min/mg protein might be useful to discriminate patients with LIPA mutations.

| S-EPMC8564860 | biostudies-literature

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