Leptin signaling in adipose tissue: role in lipid accumulation and weight gain

Rationale: The link between obesity, hyperleptinemia, and development of cardiovascular disease is not completely understood. Increases in leptin have been shown to impair leptin signaling via caveolin-1-dependent mechanisms. However, the role of hyperleptinemia versus impaired leptin signaling in adipose tissue is not known. Objective: To determine the presence and significance of leptin-dependent increases in adipose tissue caveolin-1 expression in humans. Methods and Results: We designed a longitudinal study to investigate the effects of increases in leptin on adipose tissue caveolin-1 expression during weight gain in humans. Ten volunteers underwent 8 weeks of overfeeding, during which they gained an average weight of 4.1±1.4 kg, with leptin increases from 7±3.8 to 12±5.7 ng/mL. Weight gain also resulted in changes in adipose tissue caveolin-1 expression, which correlated with increases in leptin (rho=0.79, P=0.01). In cultured human white preadipocytes, leptin increased caveolin-1 expression, which in turn impaired leptin cellular signaling. Functionally, leptin decreased lipid accumulation in differentiating human white preadipocytes, which was prevented by caveolin-1 overexpression. Further, leptin decreased perilipin and fatty acid synthase expression, which play an important role in lipid storage and biogenesis. Conclusions: In healthy humans, increases in leptin, as seen with modest weight gain, may increase caveolin-1 expression in adipose tissue. Increased caveolin-1 expression in turn impairs leptin signaling and attenuates leptin-dependent lowering of intracellular lipid accumulation. Our study suggests a leptin-dependent feedback mechanism that may be essential to facilitate adipocyte lipid storage during weight gain.     

The Personal Patient Profile-Prostate decision support for men with localized prostate cancer: A multi-center randomized trial

ObjectiveThe purpose of this trial was to compare usual patient education plus the Internet-based Personal Patient Profile-Prostate, vs. usual education alone, on conflict associated with decision making, plus explore time-to-treatment, and treatment choice.MethodsA randomized, multi-center clinical trial was conducted with measures at baseline, 1-, and 6 months. Men with newly diagnosed localized prostate cancer (CaP) who sought consultation at urology, radiation oncology, or multi-disciplinary clinics in 4 geographically-distinct American cities were recruited. Intervention group participants used the Personal Patient Profile-Prostate, a decision support system comprised of customized text and video coaching regarding potential outcomes, influential factors, and communication with care providers. The primary outcome, patient-reported decisional conflict, was evaluated over time using generalized estimating equations to fit generalized linear models. Additional outcomes, time-to-treatment, treatment choice, and program acceptability/usefulness, were explored.ResultsA total of 494 eligible men were randomized (266 intervention; 228 control). The intervention reduced adjusted decisional conflict over time compared with the control group, for the uncertainty score (estimate ?3.61; (confidence interval, ?7.01, 0.22), and values clarity (estimate ?3.57; confidence interval (?5.85,?1.30). Borderline effect was seen for the total decisional conflict score (estimate ?1.75; confidence interval (?3.61,0.11). Time-to-treatment was comparable between groups, while undecided men in the intervention group chose brachytherapy more often than in the control group. Acceptability and usefulness were highly rated.ConclusionThe Personal Patient Profile-Prostate is the first intervention to significantly reduce decisional conflict in a multi-center trial of American men with newly diagnosed localized CaP. Our findings support efficacy of P3P for addressing decision uncertainty and facilitating patient selection of a CaP treatment that is consistent with the patient values and preferences.