Recent data suggest that proinflammatory cytokines secreted from adipose tissue contribute to the morbidity associated with obesity. However, characterization of the cell types involved in inflammation and how these cells promote insulin resistance in human adipocytes are unclear. We simulated acute inflammation using the endotoxin lipopolysaccharide (LPS) to define the roles of nonadipocytes in primary cultures of human adipocytes. LPS induction of the mRNA levels of proinflammatory cytokines (e.g. IL-6, TNF-alpha, and IL-1beta) and chemokines (e.g. IL-8, monocyte chemoattractant protein-1) occurred primarily in the nonadipocyte fraction of newly differentiated human adipocytes. Nonadipocytes were characterized as preadipocytes based on their abundant mRNA levels of preadipocyte markers preadipocyte factor-1 and adipocyte enhancer protein-1 and only trace levels of markers for macrophages and myocytes. The essential role of preadipocytes in inflammation was confirmed by modulating the degree of differentiation in the cultures from approximately 0-90%. LPS-induced proinflammatory cytokine/chemokine expression and nuclear factor-kappaB and MAPK signaling decreased as differentiation increased. LPS-induced cytokine/chemokine expression in preadipocytes was associated with: 1) decreased adipogenic gene expression, 2) decreased ligand-induced activation of a peroxisome proliferator activated receptor (PPAR)-gamma reporter construct and increased phosphorylation of PPARgamma, and 3) decreased insulin-stimulated glucose uptake. Collectively, these data demonstrate that LPS induces nuclear factor-kappaB- and MAPK-dependent proinflammatory cytokine/chemokine expression primarily in preadipocytes, which triggers the suppression of PPARgamma activity and insulin responsiveness in human adipocytes.

The new ARCHITECT STAT hs-TnI assay with improved analytical features meets the criteria of high sensitive Tn test and will be a valuable diagnostic tool.

Lipid droplet-associated proteins play an important role in adipocyte triglyceride (TG) metabolism. Here, we show that trans -10, cis -12 conjugated linoleic acid (CLA), but not cis -9, trans -11 CLA, increased lipolysis and altered human adipocyte lipid droplet morphology. Before this change in morphology, there was a rapid trans -10, cis -12 CLA-induced increase in the accumulation of perilipin A in the cytosol, followed by the disappearance of perilipin A protein. In contrast, protein levels of adipose differentiation-related protein (ADRP) were increased in cultures treated with trans -10, cis -12 CLA. Immunostaining revealed that ADRP localized to the surface of small lipid droplets, displacing perilipin. Intriguingly, trans -10, cis -12 CLA increased ADRP protein expression to a much greater extent than ADRP mRNA without affecting stability, suggesting translational control of ADRP. To this end, we found that trans -10, cis -12 CLA increased activation of the mammalian target of rapamycin/p70 S6 ribosomal protein kinase/S6 ribosomal protein (mTOR/p70S6K/ S6) pathway. Collectively, these data demonstrate that the trans -10, cis -12 CLA-mediated reduction of human adipocyte TG content is associated with the differential localization and expression of lipid droplet-associated proteins. This process involves both the translational control of ADRP through the activation of mTOR/p70S6K/S6 signaling and transcriptional control of perilipin A. Conjugated linoleic acid (CLA) refers to a group of dienoic derivatives of linoleic acid. The two primary isomers of CLA found in ruminant meats and milk products and commercial preparations are cis -9, trans -11 CLA and trans -10, cis -12 CLA. CLA isomers have potential anticancer (1, 2) and antiobesity properties (reviewed in 3, 4). Concerning the isomer specificity of CLA and obesity, numerous animal studies have demonstrated that trans -10, cis -12 CLA prevents the development of adiposity (5-9). Similarly, we have shown that trans -10, cis -12 CLA, but not cis-9, trans -11 CLA, inhibits the differentiation of human preadipocytes into adipocytes and reduces the triglyceride (TG) content of mature or newly differentiated human adipocytes (10-12). However, the molecular mechanism(s) and physiological consequences of CLA supplementation are unclear, especially in humans.Recently, we reported that trans -10, cis -12 CLA treatment of cultures of human stromal vascular (SV) cells containing newly differentiated adipocytes caused delipidation by activating mitogen-activated protein kinase kinase/extracellular signal-related kinase (MEK/ERK) signaling (12). This relatively rapid activation of MEK/ERK signaling by trans -10, cis -12 CLA was followed by a decrease in the mRNA levels of peroxisome proliferator-activated receptor ␥ and many of its downstream adipogenic target genes, including perilipin, glucose transporter 4, adipocyte-specific fatty acid binding protein, lipoprotein lipase, and adiponectin. These CLA-mediated alterations were accompanied by decreased gluco...

The lining of the adult heart contains epicardial mesothelial cells (EMCs) that have the potential to undergo fibrogenic Epithelial-to-Mesenchymal Transition (EMT) during cardiac injury. EMT of EMCs has therefore been suggested to contribute to the heterogeneous fibroblast pool that mediates cardiac fibrosis. However, the molecular basis of this process is poorly understood. Recently, microRNAs (miRNAs) have been shown to regulate a number of sub-cellular events in cardiac disease. Hence, we hypothesized that miRNAs regulate fibrogenic EMT in the adult heart. Indeed pro-fibrogenic stimuli, especially TGF-β, promoted EMT progression in EMC cultures, which resulted in differential expression of numerous miRNAs, especially the pleiotropic miR-21. Accordingly, ectopic expression of miR-21 substantially promoted the fibroblast-like phenotype arising from fibrogenic EMT, whereas an antagonist that targeted miR-21 blocked this effect, as assessed on the E-cadherin/α-smooth muscle actin balance, cell viability, matrix activity, and cell motility, thus making miR-21 a relevant target of EMC-derived fibrosis. Several mRNA targets of miR-21 was differentially regulated during fibrogenic EMT of EMCs and miR-21-dependent targeting of Programmed Cell Death 4 (PDCD4) and Sprouty Homolog 1 (SPRY1) significantly contributed to the development of a fibroblastoid phenotype. However, PDCD4- and SPRY1-targeting was not entirely ascribable to all phenotypic effects from miR-21, underscoring the pleiotropic biological role of miR-21 and the increasing number of recognized miR-21 targets.