PMID- 21116821 OWN - NLM STAT- MEDLINE DCOM- 20110602 LR - 20110203 IS - 1435-1803 (Electronic) IS - 0300-8428 (Linking) VI - 106 IP - 2 DP - 2011 Mar TI - Adipocyte-derived lipids increase angiotensin-converting enzyme (ACE) expression and modulate macrophage phenotype. PG - 205-15 LID - 10.1007/s00395-010-0137-9 [doi] AB - Human monocytes/macrophages express the angiotensin-converting enzyme (ACE) but nothing is known about its role under physiological conditions. As adipose tissue contains resident macrophages that have been implicated in the generation of insulin resistance in expanding fat mass, we determined whether adipocytes release factors that affect ACE expression and function in monocytes. Incubation of human monocyte-derived macrophages with conditioned medium from freshly isolated human adipocytes (BMI = 25.4 +/- 0.96) resulted in a 4-fold increase in ACE expression. The effect was insensitive to denaturation and different proteases but abolished after lipid extraction. mRNA levels of the major histocompatibility complex class II protein increased in parallel with ACE, whereas the expression of tumor necrosis factor-alpha (TNF-alpha), monocyte chemoattractant protein-1 (MCP-1), interleukin (IL)-6, and cyclooxygenase-2 decreased. As a consequence of the reduction in MCP-1, monocyte recruitment was also attenuated. Moreover, adipocyte-conditioned medium prevented the interferon (IFN)-gamma induced formation of TNF-alpha, IL-6, and MCP-1, all markers of classically-activated (M1 type) macrophages. The decrease in cytokine expression in adipocyte-conditioned medium-treated macrophages was sensitive to ACE silencing by small interfering RNA (siRNA). Accordingly, ACE overexpression in THP-1 cells mimicked the effect of adipocyte-conditioned medium. In both cell types, ACE inhibition failed to affect the changes induced by adipocyte conditioned-medium treatment and ACE overexpression. Thus, the modulation of macrophage polarization by ACE appears to be mediated independently of enzyme activity, probably via intracellular signaling. Interestingly, human macrophage ACE expression was also upregulated by IL-4 and IL-13, which promote the "alternative" activation of macrophages and decreased by LPS and IFN-gamma. Mechanistically, adipocyte-conditioned medium stimulated the phosphorylation of the AMP-activated protein kinase and AMPK inhibition prevented the increase in ACE expression. Moreover, ACE expression was reduced in spleen derived-monocytes from AMPKalpha1(-/-) mice versus their wild-type littermates. These data indicate that mature adipocytes modulate the expression profile of macrophages by releasing lipid mediators that increase ACE expression via AMPK. This prevents the pro-inflammatory cytokine production by macrophages. FAU - Kohlstedt, Karin AU - Kohlstedt K AD - Institute for Vascular Signalling, Goethe-University, Theodor-Stern-Kai 7, 60590 Frankfurt am Main, Germany. kohlstedt@vrc.uni-frankfurt.de FAU - Trouvain, Caroline AU - Trouvain C FAU - Namgaladze, Dmitry AU - Namgaladze D FAU - Fleming, Ingrid AU - Fleming I LA - eng PT - Journal Article PT - Research Support, Non-U.S. Gov't DEP - 20101201 PL - Germany TA - Basic Res Cardiol JT - Basic research in cardiology JID - 0360342 RN - 0 (Culture Media, Conditioned) RN - EC 3.4.15.1 (Peptidyl-Dipeptidase A) SB - IM MH - Adipose Tissue/*metabolism MH - Animals MH - Cell Line MH - Cells, Cultured MH - Culture Media, Conditioned MH - Humans MH - *Lipid Metabolism MH - Macrophages/cytology/*metabolism MH - Mice MH - Mice, Transgenic MH - Monocytes/metabolism MH - Peptidyl-Dipeptidase A/*metabolism MH - Phenotype MH - Signal Transduction EDAT- 2010/12/01 06:00 MHDA- 2011/06/03 06:00 CRDT- 2010/12/01 06:00 PHST- 2010/08/09 00:00 [received] PHST- 2010/11/08 00:00 [accepted] PHST- 2010/10/20 00:00 [revised] PHST- 2010/12/01 06:00 [entrez] PHST- 2010/12/01 06:00 [pubmed] PHST- 2011/06/03 06:00 [medline] AID - 10.1007/s00395-010-0137-9 [doi] PST - ppublish SO - Basic Res Cardiol. 2011 Mar;106(2):205-15. doi: 10.1007/s00395-010-0137-9. Epub 2010 Dec 1.