title: Induction of lysosomal biogenesis in atherosclerotic macrophages can rescue lipid-induced lysosomal dysfunction and downstream sequelae.
abstract: OBJECTIVE
  Recent reports of a proatherogenic phenotype in mice with macrophage-specific autophagy deficiency have renewed interest in the role of the autophagy-lysosomal system in atherosclerosis. Lysosomes have the unique ability to process both exogenous material, including lipids and autophagy-derived cargo such as dysfunctional proteins/organelles. We aimed to understand the effects of an atherogenic lipid environment on macrophage lysosomes and to evaluate novel ways to modulate this system.
  
  
  RESULTS
  Using a variety of complementary techniques, we show that oxidized low-density lipoproteins and cholesterol crystals, commonly encountered lipid species in atherosclerosis, lead to profound lysosomal dysfunction in cultured macrophages. Disruptions in lysosomal pH, proteolytic capacity, membrane integrity, and morphology are readily seen. Using flow cytometry, we find that macrophages isolated from atherosclerotic plaques also display features of lysosome dysfunction. We then investigated whether enhancing lysosomal function can be beneficial. Transcription factor EB (TFEB) is the only known transcription factor that is a master regulator of lysosomal biogenesis although its role in macrophages has not been studied. Lysosomal stress induced by chloroquine or atherogenic lipids leads to TFEB nuclear translocation and activation of lysosomal and autophagy genes. TFEB overexpression in macrophages further augments this prodegradative response and rescues several deleterious effects seen with atherogenic lipid loading as evidenced by blunted lysosomal dysfunction, reduced secretion of the proinflammatory cytokine interleukin-1β, enhanced cholesterol efflux, and decreased polyubiquitinated protein aggregation.
  
  
  CONCLUSIONS
  Taken together, these data demonstrate that lysosomal function is markedly impaired in atherosclerosis and suggest that induction of a lysosomal biogenesis program in macrophages has antiatherogenic effects.
authors: Cardiovascular Division, Department of Medicine, Washington University School of Medicine, St. Louis, MO (R.E., I.S., S.B., S.E., A.D., B.R.) and Department of Pathology and Immunology, Washington University School of Medicine, St. Louis, MO (J.T., B.R.); John Cochran VA Medical Center, St. Louis, MO (A.D.); Telethon Institute of Genetics and Medicine (TIGEM), Naples, Italy (C.S., A.B.); and Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX (C.S., A.B.).
authors: Roy
authors: R
authors: Emanuel
authors: Cardiovascular Division, Department of Medicine, Washington University School of Medicine, St. Louis, MO (R.E., I.S., S.B., S.E., A.D., B.R.) and Department of Pathology and Immunology, Washington University School of Medicine, St. Louis, MO (J.T., B.R.); John Cochran VA Medical Center, St. Louis, MO (A.D.); Telethon Institute of Genetics and Medicine (TIGEM), Naples, Italy (C.S., A.B.); and Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX (C.S., A.B.).
authors: Ismail
authors: I
authors: Sergin
authors: Cardiovascular Division, Department of Medicine, Washington University School of Medicine, St. Louis, MO (R.E., I.S., S.B., S.E., A.D., B.R.) and Department of Pathology and Immunology, Washington University School of Medicine, St. Louis, MO (J.T., B.R.); John Cochran VA Medical Center, St. Louis, MO (A.D.); Telethon Institute of Genetics and Medicine (TIGEM), Naples, Italy (C.S., A.B.); and Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX (C.S., A.B.).
authors: Somashubhra
authors: S
authors: Bhattacharya
authors: Cardiovascular Division, Department of Medicine, Washington University School of Medicine, St. Louis, MO (R.E., I.S., S.B., S.E., A.D., B.R.) and Department of Pathology and Immunology, Washington University School of Medicine, St. Louis, MO (J.T., B.R.); John Cochran VA Medical Center, St. Louis, MO (A.D.); Telethon Institute of Genetics and Medicine (TIGEM), Naples, Italy (C.S., A.B.); and Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX (C.S., A.B.).
authors: Jaleisa
authors: J
authors: Turner
authors: Cardiovascular Division, Department of Medicine, Washington University School of Medicine, St. Louis, MO (R.E., I.S., S.B., S.E., A.D., B.R.) and Department of Pathology and Immunology, Washington University School of Medicine, St. Louis, MO (J.T., B.R.); John Cochran VA Medical Center, St. Louis, MO (A.D.); Telethon Institute of Genetics and Medicine (TIGEM), Naples, Italy (C.S., A.B.); and Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX (C.S., A.B.).
authors: Slava
authors: S
authors: Epelman
authors: Cardiovascular Division, Department of Medicine, Washington University School of Medicine, St. Louis, MO (R.E., I.S., S.B., S.E., A.D., B.R.) and Department of Pathology and Immunology, Washington University School of Medicine, St. Louis, MO (J.T., B.R.); John Cochran VA Medical Center, St. Louis, MO (A.D.); Telethon Institute of Genetics and Medicine (TIGEM), Naples, Italy (C.S., A.B.); and Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX (C.S., A.B.).
authors: Carmine
authors: C
authors: Settembre
authors: Cardiovascular Division, Department of Medicine, Washington University School of Medicine, St. Louis, MO (R.E., I.S., S.B., S.E., A.D., B.R.) and Department of Pathology and Immunology, Washington University School of Medicine, St. Louis, MO (J.T., B.R.); John Cochran VA Medical Center, St. Louis, MO (A.D.); Telethon Institute of Genetics and Medicine (TIGEM), Naples, Italy (C.S., A.B.); and Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX (C.S., A.B.).
authors: Abhinav
authors: A
authors: Diwan
authors: Cardiovascular Division, Department of Medicine, Washington University School of Medicine, St. Louis, MO (R.E., I.S., S.B., S.E., A.D., B.R.) and Department of Pathology and Immunology, Washington University School of Medicine, St. Louis, MO (J.T., B.R.); John Cochran VA Medical Center, St. Louis, MO (A.D.); Telethon Institute of Genetics and Medicine (TIGEM), Naples, Italy (C.S., A.B.); and Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX (C.S., A.B.).
authors: Andrea
authors: A
authors: Ballabio
authors: Cardiovascular Division, Department of Medicine, Washington University School of Medicine, St. Louis, MO (R.E., I.S., S.B., S.E., A.D., B.R.) and Department of Pathology and Immunology, Washington University School of Medicine, St. Louis, MO (J.T., B.R.); John Cochran VA Medical Center, St. Louis, MO (A.D.); Telethon Institute of Genetics and Medicine (TIGEM), Naples, Italy (C.S., A.B.); and Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX (C.S., A.B.).
authors: Babak
authors: B
authors: Razani
mesh_terms: D000818:Animals; D001057:Apolipoproteins E / Q000172:deficiency; D050197:Atherosclerosis / Q000378:metabolism* / Q000473:pathology; D001343:Autophagy; D000071187:Autophagy-Related Protein 5; D051778:Basic Helix-Loop-Helix Leucine Zipper Transcription Factors; D002463:Cell Membrane Permeability; D002738:Chloroquine / Q000494:pharmacology; D002784:Cholesterol / Q000378:metabolism; D006863:Hydrogen-Ion Concentration; D002479:Inclusion Bodies / Q000378:metabolism; D058847:Inflammasomes / Q000378:metabolism; D053583:Interleukin-1beta / Q000378:metabolism; D008055:Lipids; D008077:Lipoproteins, LDL / Q000378:metabolism; D008247:Lysosomes / Q000187:drug effects / Q000502:physiology*; D017737:Macrophages, Peritoneal / Q000502:physiology*; D051379:Mice; D008810:Mice, Inbred C57BL; D008822:Mice, Transgenic; D008869:Microtubule-Associated Proteins / Q000172:deficiency / Q000235:genetics; D058226:Plaque, Atherosclerotic / Q000378:metabolism / Q000473:pathology; D025821:Polyubiquitin / Q000378:metabolism; D059748:Proteolysis; D002787:Sterol Esterase / Q000378:metabolism; D014158:Transcription, Genetic
chemical_list: D001057:Apolipoproteins E; C495773:Atg5 protein, mouse; D000071187:Autophagy-Related Protein 5; D051778:Basic Helix-Loop-Helix Leucine Zipper Transcription Factors; D058847:Inflammasomes; D053583:Interleukin-1beta; D008055:Lipids; D008077:Lipoproteins, LDL; D008869:Microtubule-Associated Proteins; C484068:Tcfeb protein, mouse; C099252:oxidized low density lipoprotein; D025821:Polyubiquitin; D002738:Chloroquine; D002784:Cholesterol; D002787:Sterol Esterase
keywords: atherosclerosis; autophagy; inflammasome; lipid metabolism; lysosomes; macrophages