The accumulation of macrophages with a proinflammatory phenotype in adipose tissue is a driver of obesity-associated metabolic disease. While adipose tissue macrophages are found in the lean state, these cells have an alternatively activated (M2) phenotype. In this episode, Tamás Röszer and colleagues demonstrate that adipose tissue macrophages express a receptor for the appetite-reducing neuropeptide FF and that and that neuropeptide FF promotes M2 activation and proliferation. Additionally, obesity was associated with reduced levels of circulating neuropeptide FF. Together, the results of this study reveal an important role for neuropeptide FF in maintaining metabolically beneficial macrophages in adipose tissue.
The quantity and activation state of adipose tissue macrophages (ATMs) impact the development of obesity-induced metabolic diseases. Appetite-controlling hormones play key roles in obesity; however, our understanding of their effects on ATMs is limited. Here, we have shown that human and mouse ATMs express NPFFR2, a receptor for the appetite-reducing neuropeptide FF (NPFF), and that NPFFR2 expression is upregulated by IL-4, an M2-polarizing cytokine. Plasma levels of NPFF decreased in obese patients and high-fat diet–fed mice and increased following caloric restriction. NPFF promoted M2 activation and increased the proliferation of murine and human ATMs. Both M2 activation and increased ATM proliferation were abolished in NPFFR2-deficient ATMs. Mechanistically, the effects of NPFF involved the suppression of E3 ubiquitin ligase RNF128 expression, resulting in enhanced stability of phosphorylated STAT6 and increased transcription of the M2 macrophage–associated genes IL-4 receptor α (Il4ra), arginase 1 (Arg1), IL-10 (Il10), and alkylglycerol monooxygenase (Agmo). NPFF induced ATM proliferation concomitantly with the increase in N-Myc downstream-regulated gene 2 (Ndrg2) expression and suppressed the transcription of Ifi200 cell-cycle inhibitor family members and MAF bZIP transcription factor B (Mafb), a negative regulator of macrophage proliferation. NPFF thus plays an important role in supporting healthy adipose tissue via the maintenance of metabolically beneficial ATMs.
Syed F. Hassnain Waqas, Anh Cuong Hoang, Ya-Tin Lin, Grace Ampem, Hind Azegrouz, Lajos Balogh, Julianna Thuróczy, Jin-Chung Chen, Ivan C. Gerling, Sorim Nam, Jong-Seok Lim, Juncal Martinez-Ibañez, José T. Real, Stephan Paschke, Raphaëlle Quillet, Safia Ayachi, Frédéric Simonin, E. Marion Schneider, Jacqueline A. Brinkman, Dudley W. Lamming, Christine M. Seroogy, Tamás Röszer