Lipid accumulation impairs lysosomal acid lipase activity in hepatocytes: Evidence in NAFLD patients and cell cultures

Monica Gomaraschi, Anna Ludovica Fracanzani, Paola Dongiovanni, Chiara Pavanello, Eleonora Giorgio, Lorenzo Da Dalt, Giuseppe Danilo Norata, Laura Calabresi, Dario Consonni, Rosa Lombardi, Adriana Branchi, Silvia Fargion

Research output: Contribution to journalArticle

Abstract

Aims: It has been hypothesized that the activity of lysosomal acid lipase (LAL), a key enzyme involved in lipid metabolism, is involved in the NAFLD phenotype. To clarify the role of LAL in NAFLD, we studied 164 consecutive patients with biopsy-proven NAFLD and fat-loaded HepG2 cells. Methods: LAL activity was measured (i) on dried blood spots (DBS) from NAFLD patients and dyslipidemic subjects without fatty liver and (ii) on liver biopsies from NAFLD patients. LAL activity and expression were evaluated in HepG2 cells cultured in the presence of free fatty acids (FAs), with or without a PPAR-alpha agonist. Results: LAL activity was significantly reduced in patients with NAFLD compared to dyslipidemic subjects. LAL activity measured in liver biopsies from NAFLD patients was highly correlated to that measured on DBS and was independent of LAL expression in the liver. In a fully adjusted model, LAL activity on DBS was associated only with platelets and, when normalized by platelet count, it did not differ according to fibrosis stage. In vitro, FA loading of HepG2 fully replicated the impairment of LAL activity observed in NALFD patients. In these cells, the activation of PPAR-alpha receptors prevented and corrected FA-induced LAL impairment, by stimulating FA oxidation and LAL expression. Conclusions: LAL activity is reduced in NAFLD patients, independently from disease progression. In vitro, impaired LAL activity induced by FA loading was rescued by PPAR-alpha activation. These data suggest that the pharmacological modulation of LAL should be explored in the management of NAFLD patients.

Original languageEnglish
Article number158523
JournalBiochimica et Biophysica Acta - Molecular and Cell Biology of Lipids
Volume1864
Issue number12
DOIs
Publication statusPublished - Dec 1 2019

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Sterol Esterase
Hepatocytes
Cell Culture Techniques
Lipids
PPAR alpha
Fatty Acids
Hep G2 Cells
Non-alcoholic Fatty Liver Disease
Biopsy
Liver
Fatty Liver
Platelet Count
Lipid Metabolism
Nonesterified Fatty Acids

Keywords

  • Hepatocytes
  • Lysosomal acid lipase
  • Non-alcoholic fatty liver disease
  • Peroxisome proliferator-activated receptors

ASJC Scopus subject areas

  • Molecular Biology
  • Cell Biology

Cite this

Lipid accumulation impairs lysosomal acid lipase activity in hepatocytes : Evidence in NAFLD patients and cell cultures. / Gomaraschi, Monica; Fracanzani, Anna Ludovica; Dongiovanni, Paola; Pavanello, Chiara; Giorgio, Eleonora; Da Dalt, Lorenzo; Norata, Giuseppe Danilo; Calabresi, Laura; Consonni, Dario; Lombardi, Rosa; Branchi, Adriana; Fargion, Silvia.

In: Biochimica et Biophysica Acta - Molecular and Cell Biology of Lipids, Vol. 1864, No. 12, 158523, 01.12.2019.

Research output: Contribution to journalArticle

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abstract = "Aims: It has been hypothesized that the activity of lysosomal acid lipase (LAL), a key enzyme involved in lipid metabolism, is involved in the NAFLD phenotype. To clarify the role of LAL in NAFLD, we studied 164 consecutive patients with biopsy-proven NAFLD and fat-loaded HepG2 cells. Methods: LAL activity was measured (i) on dried blood spots (DBS) from NAFLD patients and dyslipidemic subjects without fatty liver and (ii) on liver biopsies from NAFLD patients. LAL activity and expression were evaluated in HepG2 cells cultured in the presence of free fatty acids (FAs), with or without a PPAR-alpha agonist. Results: LAL activity was significantly reduced in patients with NAFLD compared to dyslipidemic subjects. LAL activity measured in liver biopsies from NAFLD patients was highly correlated to that measured on DBS and was independent of LAL expression in the liver. In a fully adjusted model, LAL activity on DBS was associated only with platelets and, when normalized by platelet count, it did not differ according to fibrosis stage. In vitro, FA loading of HepG2 fully replicated the impairment of LAL activity observed in NALFD patients. In these cells, the activation of PPAR-alpha receptors prevented and corrected FA-induced LAL impairment, by stimulating FA oxidation and LAL expression. Conclusions: LAL activity is reduced in NAFLD patients, independently from disease progression. In vitro, impaired LAL activity induced by FA loading was rescued by PPAR-alpha activation. These data suggest that the pharmacological modulation of LAL should be explored in the management of NAFLD patients.",
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author = "Monica Gomaraschi and Fracanzani, {Anna Ludovica} and Paola Dongiovanni and Chiara Pavanello and Eleonora Giorgio and {Da Dalt}, Lorenzo and Norata, {Giuseppe Danilo} and Laura Calabresi and Dario Consonni and Rosa Lombardi and Adriana Branchi and Silvia Fargion",
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T1 - Lipid accumulation impairs lysosomal acid lipase activity in hepatocytes

T2 - Evidence in NAFLD patients and cell cultures

AU - Gomaraschi, Monica

AU - Fracanzani, Anna Ludovica

AU - Dongiovanni, Paola

AU - Pavanello, Chiara

AU - Giorgio, Eleonora

AU - Da Dalt, Lorenzo

AU - Norata, Giuseppe Danilo

AU - Calabresi, Laura

AU - Consonni, Dario

AU - Lombardi, Rosa

AU - Branchi, Adriana

AU - Fargion, Silvia

PY - 2019/12/1

Y1 - 2019/12/1

N2 - Aims: It has been hypothesized that the activity of lysosomal acid lipase (LAL), a key enzyme involved in lipid metabolism, is involved in the NAFLD phenotype. To clarify the role of LAL in NAFLD, we studied 164 consecutive patients with biopsy-proven NAFLD and fat-loaded HepG2 cells. Methods: LAL activity was measured (i) on dried blood spots (DBS) from NAFLD patients and dyslipidemic subjects without fatty liver and (ii) on liver biopsies from NAFLD patients. LAL activity and expression were evaluated in HepG2 cells cultured in the presence of free fatty acids (FAs), with or without a PPAR-alpha agonist. Results: LAL activity was significantly reduced in patients with NAFLD compared to dyslipidemic subjects. LAL activity measured in liver biopsies from NAFLD patients was highly correlated to that measured on DBS and was independent of LAL expression in the liver. In a fully adjusted model, LAL activity on DBS was associated only with platelets and, when normalized by platelet count, it did not differ according to fibrosis stage. In vitro, FA loading of HepG2 fully replicated the impairment of LAL activity observed in NALFD patients. In these cells, the activation of PPAR-alpha receptors prevented and corrected FA-induced LAL impairment, by stimulating FA oxidation and LAL expression. Conclusions: LAL activity is reduced in NAFLD patients, independently from disease progression. In vitro, impaired LAL activity induced by FA loading was rescued by PPAR-alpha activation. These data suggest that the pharmacological modulation of LAL should be explored in the management of NAFLD patients.

AB - Aims: It has been hypothesized that the activity of lysosomal acid lipase (LAL), a key enzyme involved in lipid metabolism, is involved in the NAFLD phenotype. To clarify the role of LAL in NAFLD, we studied 164 consecutive patients with biopsy-proven NAFLD and fat-loaded HepG2 cells. Methods: LAL activity was measured (i) on dried blood spots (DBS) from NAFLD patients and dyslipidemic subjects without fatty liver and (ii) on liver biopsies from NAFLD patients. LAL activity and expression were evaluated in HepG2 cells cultured in the presence of free fatty acids (FAs), with or without a PPAR-alpha agonist. Results: LAL activity was significantly reduced in patients with NAFLD compared to dyslipidemic subjects. LAL activity measured in liver biopsies from NAFLD patients was highly correlated to that measured on DBS and was independent of LAL expression in the liver. In a fully adjusted model, LAL activity on DBS was associated only with platelets and, when normalized by platelet count, it did not differ according to fibrosis stage. In vitro, FA loading of HepG2 fully replicated the impairment of LAL activity observed in NALFD patients. In these cells, the activation of PPAR-alpha receptors prevented and corrected FA-induced LAL impairment, by stimulating FA oxidation and LAL expression. Conclusions: LAL activity is reduced in NAFLD patients, independently from disease progression. In vitro, impaired LAL activity induced by FA loading was rescued by PPAR-alpha activation. These data suggest that the pharmacological modulation of LAL should be explored in the management of NAFLD patients.

KW - Hepatocytes

KW - Lysosomal acid lipase

KW - Non-alcoholic fatty liver disease

KW - Peroxisome proliferator-activated receptors

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