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Obesity and adipose tissue contribute to local and systemic inflammation. However the role of the inflammatory mediator bradykinin (BK) in this context is not known. We therefore evaluated the effect of BK on adipokines secretion in human preadipocytes during the course of differentiation and characterized the receptors involved. Results obtained from antibody array and ELISA experiments showed that several adipokines are released by human preadipocytes under basal conditions while BK specifically stimulated the production of interleukin(IL)-6 and IL-8. The effect of BK diminished with the progression of differentiation, being almost inactive on adipocytes. In preadipocytes, BK also induced a rapid and transient [Ca²⁺](i) mobilization, a rapid and sustained increase in ERK1/2 activation and enhanced forskolin-stimulated cAMP accumulation. BK was without effect on cell proliferation and viability as assessed by bromodeoxyuridine incorporation, WST-1 conversion, or lactate dehydrogenase leakage and was without effect on adipogenesis as measured by triglyceride accumulation, GPDH activity and leptin release. The B₁ receptor agonist, Lys-[des-Arg⁹]-BK, displayed poor activity or was without effect while overall BK effects were prevented by the selective B₂ receptor antagonist, fasitibant chloride, but not by the B₁ selective antagonist, Lys-[Leu⁸][des-Arg⁹]-BK. Immunoblot analysis and immunofluorescence studies showed that the kinin B₂ receptor was essentially expressed at the beginning of the differentiation program. In conclusion, human preadipocytes expressed kinin B₂ receptors linked to multiple signaling pathways, IL-6 and IL-8 production, and BK proinflammatory response in adipose tissue could be prevented by fasitibant chloride., (Copyright © 2013 Elsevier Inc. All rights reserved.)

The present study investigated the effect of HDAC inhibitors on the differentiation of human subcutaneous white adipocytes. Results showed that trichostatin A, suberoylanilide hydroxamic acid, valproic acid and MS-275 inhibited triglyceride accumulation, GPDH activity and FABP4 protein expression in adipocytes, as well as leptin and VEGF release, while cells retained a fibroblast-like morphology. HDAC inhibitors exerted their antiadipogenic effect without inducing apoptosis or affecting cell viability and number, while 1-2 log unit higher concentrations were mostly required to exert an antiproliferative effect or to reduce LDH activity. A brief exposure to HDAC inhibitors at the beginning of the differentiation program was sufficient to observe the antiadipogenic effect while differentiation restarted after compound withdrawal and further exposure to inducers of differentiation demonstrating reversibility of the events. HDAC inhibitors hyperacetylated histone H4, but only hydroxamate-based compounds produced a massive acetylation of alpha-tubulin, indicating that this latter event is not required to prevent adipose conversion. HDAC inhibitors induced a significant reduction of the expression of the transcription factor C/EBPalpha, an early marker of differentiation, and a diminution of fibronectin immunoreactivity was also observed. In conclusion, HDAC inhibitors from different chemical classes potently inhibited human adipose conversion at an early stage of the differentiation program.