Fc gamma RIIb on CD11c(+) cells modulates serum cholesterol and triglyceride levels and differentially affects atherosclerosis in male and female Ldlr(-/-) mice
Authors: Marvin, Jennifer; Rhoads, Jillian P.; Major, Amy S.
Background and aims: Circulating levels of oxidized lipoprotein oxLDL) correlate with myocardial infarction risk and atherosclerosis severity. Our previous study demonstrates that oxLDL immune complexes oxLDL-ICs) can signal through Fc gamma Rs on bone marrow-derived dendritic cells BMDCs) and enhance their activation and inflammatory cytokine secretion. While global Fc gamma R-/- studies have shown that activating Fc gamma Rs are proatherogenic, the role of the inhibitory Fc gamma RIIb is unclear. We sought to determine the role of DC-specific Fc gamma RIIb in atherosclerosis. Methods: Bone marrow chimeras were generated by rescuing lethally irradiated Ldlr(-/-) mice with hematopoietic cells from littermate CD11c-Cre(+) or CD11c-Cre-Fcgr2b(fl/fl) donors. Four weeks following transplant, recipients were placed on a Western diet for eight weeks. Various tissues and organs were analyzed for differences in inflammation. Results: Quantitation of atherosclerosis in the proximal aorta demonstrated a 58% increase in female CD11c-Cre(+) Fcgr2b(fl/fl) recipients, but a surprising 44% decrease in male recipients. Hepatic cholesterol and triglycerides were increased in female CD11c-Cre(+) Fcgr2b(fl/fl) recipients. This was associated with an increase in CD36 and MHC Class II expression on hepatic CD11c(+) CD11b(+) DCs in female livers. In contrast, male CD11c-Cre(+) Fcgr2b(fl/fl) recipients had decreased hepatic lipids with a corresponding decrease in CD36 and MHC Class II expression on CD11c(+) cells. Interestingly, both sexes of CD11c-Cre(+) Fcgr2b(fl/fl) recipients had significant decreases in serum cholesterol and TGs with corresponding decreases in liver Fasn transcripts. Conclusions: The absence of Fc gamma RIIb expression on CD11c(+) cells results in sex-dependent alteration in liver inflammation influencing atherogenesis and sex-independent modulation of serum cholesterol and TGs.
Molecular biomarkers of phospholipidosis in rat blood and heart after amiodarone treatment
JOURNAL OF APPLIED TOXICOLOGY
Authors: Bocchini, Nicola; Giantin, Mery; Crivellente, Federica; Ferraresso, Serena; Faustinelli, Ivo; Dacasto, Mauro; Cristofori, Patrizia
Phospholipidosis (PLD) is characterized by an intracellular accumulation of phospholipids in lysosomes and concurrent development of concentric lamellar bodies. It is induced in humans and in animals by drugs with a cationic amphiphilic structure. The purpose of the present study was to identify a set of molecular biomarkers of PLD in rat blood and heart, hypothetically applicable in preclinical screens within the drug development process. A toxicological study was set up in rats orally treated up to 11 days with 300mgkg(-1) per day(-1) amiodarone (AMD). Light and transmission electron microscopy investigations were performed to confirm the presence of lamellar bodies indicative of phospholipid accumulation. The effects of AMD upon the transcriptome of these tissues were estimated using DNA microarray technology. Microarray data analysis showed that a total of 545 and 8218 genes were modulated by AMD treatment in heart and blood, respectively. Some genes implicated in the phospholipid accumulation in cells, such as phospholipase A2, showed similar alterations of gene expression. After transcriptome criteria of analysis and target selection, including also the involvement in the onset of PLD, 7 genes (Pla2g2a, Pla2g7, Gal, Il1b, Cebpb, Fcgr2b, Acer 2) were selected as candidate biomarkers of PLD in heart and blood tissues, and their potential usefulness as a sensitive screening test was screened and confirmed by quantitative Real-Time PCR analysis. Collectively, these data underscore the importance of transcriptional profiling in drug discovery and development, and suggest blood as a surrogate tissue for possible phospholipid accumulation in cardiomyocytes. Copyright (c) 2014 John Wiley & Sons, Ltd. A set of phospholipidosis (PLD) biomarkers was identified in the blood and hearts of rats treated with amiodarone (AMD) using DNA microarrays. Overall, 545 and 8218 genes were modulated by AMD in hearts and blood, respectively; furthermore, some genes implicated in cellular phospholipid accumulation showed similar alterations. The usefulness of seven candidate genes was screened and confirmed by quantitative Real-Time PCR analysis. Presented data underscore the importance of transcriptional profiling in preclinical studies. Blood may be a surrogate tissue of cardiomyocyte PLD.