Conjugated Linoleic Acid Isomers Exert Differential Effects on an Adipocyte Model of HIV-associated Lipodystrophy.

BACKGROUND: HIV-associated lipodystrophy is associated with decreased expression of PPAR-γ in adipose tissue. Conjugated linoleic acid (CLA) isomers (cis9, trans11 and trans10, cis12) are putative PPAR-γ agonists, but have not previously been investigated in the context of HIVassociated lipodystrophy. METHOD: 3T3-L1 pre-adipocytes were differentiated in the presence of ritonavir (20 µM as per previous experimental models) and 100 µM cis9,trans11, trans10,cis12 or vehicle control, DMSO. Microarray analysis, RT-PCR, DNA binding ELISA and Oil Red O staining were used to investigate adipocyte gene expression and binding, protein secretion and triglyceride storage. RESULTS: trans10, cis12 + ritonavir altered the expression of 2160 gene transcripts greater than 1.5-fold compared with control, while 257 gene transcripts were altered by cis9,trans11 + ritonavir (P<0.001). trans10,cis12 + ritonavir down-regulated Pparg (-1.55) and Adipoq (-2.95), as well as differentiation (Fcor (-4.78-fold), Arl4a (-4.84), Itga6 (-2.45), Id4 (-2.01)) and triglyceride storage genes (Mrap (- 8.25), Scd1 (-4.34), Lipin1 (-2.52)). Changes in Adipoq were confirmed by RT-PCR (P=0.038) and adiponectin secretion by ELISA (P= 0.003). cis9,trans11 + ritonavir increased PPAR-γ nuclear binding to its gene response element (P=0.038). Both isomers increased triglyceride storage in the presence of ritonavir (P<0.001). CONCLUSION: In the presence of ritonavir, trans10, cis12 appears to be detrimental, while cis9, trans11 was beneficial and may mediate its effects via PPAR-γ. Further research is required to determine the potential role of CLA isomers as therapeutic agents in the management of HIV-associated lipodystrophy.

Energy Drinks and Their Impact on the Cardiovascular System: Potential Mechanisms.

Globally, the popularity of energy drinks is steadily increasing. Scientific interest in their effects on cardiovascular and cerebrovascular systems in humans is also expanding and with it comes a growing number of case reports of adverse events associated with energy drinks. The vast majority of studies carried out in the general population report effects on blood pressure and heart rate. However, inconsistencies in the current literature render it difficult to draw firm conclusions with regard to the effects of energy drinks on cardiovascular and cerebrovascular variables. These inconsistencies are due, in part, to differences in methodologies, volume of drink ingested, and duration of postconsumption measurements, as well as subject variables during the test. Recent well-controlled, randomized crossover studies that used continuous beat-to-beat measurements provide evidence that cardiovascular responses to the ingestion of energy drinks are best explained by the actions of caffeine and sugar, with little influence from other ingredients. However, a role for other active constituents, such as taurine and glucuronolactone, cannot be ruled out. This article reviews the potentially adverse hemodynamic effects of energy drinks, particularly on blood pressure and heart rate, and discusses the mechanisms by which their active ingredients may interact to adversely affect the cardiovascular system. Research areas and gaps in the literature are discussed with particular reference to the use of energy drinks among high-risk individuals.

Microarray Analysis Reveals Altered Lipid and Glucose Metabolism Genes in Differentiated, Ritonavir-Treated 3T3-L1 Adipocytes.

OBJECTIVE: HIV lipodystrophy is characterised by abnormal adipose tissue distribution and metabolism, as a result of altered adipocyte function and gene expression. The protease inhibitor ritonavir is associated with the development of lipodystrophy. Quantifying changes in adipogenic gene expression in the presence of ritonavir may help to identify therapeutic targets for HIV lipodystrophy. METHODS: Affymetrix Mouse Genome 430 2.0 oligonucleotide microarray was used to investigate gene expression in 3T3-L1 adipocytes treated with 20 µmol/l ritonavir or vehicle control (ethanol). Pparg, Adipoq, Retn and Il6 expression were validated by real time RT-PCR. Transcriptional signalling through PPAR-γ was investigated using a DNA-binding ELISA. Changes in adipocyte function were investigated through secreted adiponectin quantification using ELISA and Oil Red O staining for triglyceride storage. RESULTS: Expression of 389 genes was altered by more than 5-fold in the presence of ritonavir (all P < 0.001). Gene ontology analysis revealed down-regulation of genes responsible for adipocyte triglyceride accumulation including complement factor D (Cfd; 238.42-fold), Cidec (73.75-fold) and Pparg (5.63-fold). Glucose transport genes were also down-regulated including Adipoq (24.42-fold) and Glut4 (13.36-fold), while Il6 was up-regulated (10.39-fold). PPAR-γ regulatory genes Cebpa (11.33-fold) and liver-X-receptor α (Nr1h3) were down-regulated. Changes in Pparg, Adipoq and Il6 were confirmed by RT-PCR. PPAR-γ binding to its nuclear consensus site, adiponectin secretion and triglyceride accumulation were all reduced by ritonavir. CONCLUSION: Ritonavir had a significant effect on expression of genes involved in adipocyte differentiation, lipid accumulation and glucose metabolism. Down-regulation of Pparg may be mediated by changes in Cebpa, Lcn2 and Nr1h3.