title: The natural compound berberine positively affects macrophage functions involved in atherogenesis.
abstract: OBJECTIVE
  We investigated the effect of berberine (BBR), an alkaloid showing antiatherogenic properties beyond the cholesterol lowering capacity, on macrophage cholesterol handling upon exposure to human serum and on macrophage responses to excess free cholesterol (FC) loading.
  
  
  RESULTS
  Mouse and human macrophages were utilized as cellular models. Cholesterol content was measured by a fluorimetric assay; cholesterol efflux, cytotoxicity and membrane FC distribution were evaluated by radioisotopic assays. Monocyte chemotactic protein-1 (MCP-1) secretion was measured by ELISA; membrane ruffling and macropinocytosis were visualized by confocal microscopy. Exposure of cholesterol-enriched MPM to serum in the presence of 1 μM BBR resulted in a reduction of intracellular cholesterol content twice greater than exposure to serum alone (-52%; p < 0.01 and -21%; p < 0.05), an effect not mediated by an increase of cholesterol efflux, but rather by the inhibition of cholesterol uptake from serum. Consistently, BBR inhibited in a dose-dependent manner cholesterol accumulation in human macrophages exposed to hypercholesterolemic serum. Confocal microscope analysis revealed that BBR inhibited macropinocytosis, an independent-receptor process involved in LDL internalization. Macrophage FC-enrichment increased MCP-1 release by 1.5 folds, increased cytotoxicity by 2 fold, and induced membrane ruffling; all these responses were markedly inhibited by BBR. FC-enrichment led to an increase in plasma membrane cholesterol by 4.5 folds, an effect counteracted by BBR.
  
  
  CONCLUSIONS
  We showed novel potentially atheroprotective activities of BBR in macrophages, consisting in the inhibition of serum-induced cholesterol accumulation, occurring at least in part through an impairment of macropinocytosis, and of FC-induced deleterious effects.
authors.affiliation: Department of Pharmacy, University of Parma, Parma, Italy.
authors.forename: F
authors.initials: F
authors.lastname: Zimetti
authors.affiliation: Department of Pharmacy, University of Parma, Parma, Italy.
authors.forename: M P
authors.initials: MP
authors.lastname: Adorni
authors.affiliation: Department of Pharmacy, University of Parma, Parma, Italy.
authors.forename: N
authors.initials: N
authors.lastname: Ronda
authors.affiliation: Department of Biomedical, Biotechnology and Translational Sciences, University of Parma, Parma, Italy.
authors.forename: R
authors.initials: R
authors.lastname: Gatti
authors.affiliation: Department of Pharmacy, University of Parma, Parma, Italy. Electronic address: fbernini@unipr.it.
authors.forename: F
authors.initials: F
authors.lastname: Bernini
authors.affiliation: Department of Pharmacy, University of Parma, Parma, Italy.
authors.forename: E
authors.initials: E
authors.lastname: Favari
mesh_terms: D000818:Animals; D000924:Anticholesteremic Agents / Q000494:pharmacology; D050197:Atherosclerosis / Q000188:drug therapy*; D001599:Berberine / Q000494:pharmacology*; D002462:Cell Membrane / Q000737:chemistry / Q000187:drug effects; D002478:Cells, Cultured; D018932:Chemokine CCL2 / Q000097:blood / Q000378:metabolism; D002784:Cholesterol / Q000737:chemistry; D006801:Humans; D006937:Hypercholesterolemia / Q000097:blood; D008264:Macrophages / Q000187:drug effects* / Q000378:metabolism; D051379:Mice; D008810:Mice, Inbred C57BL
chemical_list: D000924:Anticholesteremic Agents; D018932:Chemokine CCL2; D001599:Berberine; D002784:Cholesterol
keywords: Atherosclerosis; Berberine; Cholesterol; Inflammation; Macrophages