Adiponectin primes human monocytes into alternative anti-inflammatory M2 macrophages

Abstract

primes human monocytes into alternative anti-inflammatory M2 macrophages. Am J Physiol Heart Circ Physiol 299: H656 -H663, 2010. First published July 9, 2010; doi:10.1152/ajpheart.00115.2010.-Altered macrophage kinetics is a pivotal mechanism of visceral obesityinduced inflammation and cardiometabolic risk. Because monocytes can differentiate into either proatherogenic M1 macrophages or antiinflammatory M2 macrophages, approaches that limit M1 while promoting M2 differentiation represent a unique therapeutic strategy. We hypothesized that adiponectin may prime human monocytes toward the M2 phenotype. Adiponectin promoted the alternative activation of human monocytes into anti-inflammatory M2 macrophages as opposed to the classically activated M1 phenotype. Adiponectin-treated cells displayed increased M2 markers, including the mannose receptor (MR) and alternative macrophage activation-associated CC chemokine-1. Incubation of M1 macrophages with adiponectin-treated M2-derived culture supernatant resulted in a pronounced inhibition of tumor necrosis factor-␣ and monocyte chemotactic protein-1 secretion. Activation of human monocytes into M2 macrophages by adiponectin was mediated, in addition to AMP-activated protein kinase and peroxisome proliferator-activated receptor (PPAR)-␥, via PPAR-␣. Furthermore, macrophages isolated from adiponectin knockout mice demonstrated diminished levels of M2 markers such as MR, which were restored with adiponectin treatment. We report a novel immunoregulatory mechanism through which adiponectin primes human monocyte differentiation into anti-inflammatory M2 macrophages. Conditions associated with low adiponectin levels, such as visceral obesity and insulin resistance, may promote atherosclerosis, in part through aberrant macrophage kinetics. adiponectin; obesity; macrophage activation ATHEROSCLEROSIS IS REGARDED as a dynamic and progressive disease arising from the combination of abnormal lipid metabolism, endothelial dysfunction, and inflammation (35). A crucial step in this inflammatory process is the infiltration of monocytes into the subendothelial space of large arteries and their differentiation into tissue macrophages, whose activation and function are influenced by the cytokines within the inflammatory milieu of the atherosclerotic lesion.

Molecular Mechanism for Adiponectin-dependent M2 Macrophage Polarization

“…Adiponectin can either act directly on macrophages to shift polarization (23) or indirectly by priming macrophages to IL-4-mediated M2 polarization (24). Here, we have interrogated the mechanisms for adiponectin-mediated polarization of macrophages, and we report that flAcrp is a very potent inducer of M2 macrophage polarization, both in RAW264.7 macrophages and in primary cultures of rat Kupffer cells.…”

Adiponectin regulates psoriasiform skin inflammation by suppressing IL-17 production from γδ-T cells

“…Interestingly, recent reports regarding adiponectin have been focusing on a new feature of adiponectin, an aspect as a regulator of immune responses 22,23 . A number of experimental studies suggest that adiponectin attenuates excessive inflammatory responses in a variety of tissues, especially in obesity-associated states [24][25][26] . Roles of adiponectin in the development of psoriasis, one of the obesitylinked diseases as mentioned above, have been also discussed in the vast past epidemiologic reports [27][28][29] .…”

Downregulation of the tumour suppressor p16INK4A contributes to the polarisation of human macrophages toward an adipose tissue macrophage (ATM)-like phenotype

“…However, under basal conditions, overproduction of p16 INK4A also exerted effects on the NFκB pathway, as shown by lower IκBα protein levels. IκBα is known to be anti-inflammatory [17] and inhibition of IκBα phosphorylation and subsequent degradation by adiponectin promotes M2 polarisation [29], suggesting that the anti-inflammatory effects of IκBα can enhance alternative polarisation. The lower IκBα levels in basal conditions after p16…”