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A decade of progress in adipose tissue macrophage biology
Author(s) -
Hill Andrea A.,
Reid Bolus W.,
Hasty Alyssa H.
Publication year - 2014
Publication title -
immunological reviews
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 6.839
H-Index - 223
eISSN - 1600-065X
pISSN - 0105-2896
DOI - 10.1111/imr.12216
Subject(s) - adipose tissue , biology , insulin resistance , inflammation , macrophage , adipokine , adipose tissue macrophages , immune system , homeostasis , chemokine , adipocyte , microbiology and biotechnology , immunology , glucose homeostasis , lipolysis , white adipose tissue , endocrinology , insulin , biochemistry , in vitro
Summary One decade has passed since seminal publications described macrophage infiltration into adipose tissue ( AT ) as a key contributor to inflammation and obesity‐related insulin resistance. Currently, a PubMed search for ‘adipose tissue inflammation’ reveals over 3500 entries since these original reports. We now know that resident macrophages in lean AT are alternatively activated, M2‐like, and play a role in AT homeostasis. In contrast, the macrophages in obese AT are dramatically increased in number and are predominantly classically activated, M1‐like, and promote inflammation and insulin resistance. Mediators of AT macrophage ( ATM ) phenotype include adipokines and fatty acids secreted from adipocytes as well as cytokines secreted from other immune cells in AT . There are several mechanisms that could explain the large increase in ATM s in obesity. These include recruitment‐dependent mechanisms such as adipocyte death, chemokine release, and lipolysis of fatty acids. Newer evidence also points to recruitment‐independent mechanisms such as impaired apoptosis, increased proliferation, and decreased egress. Although less is known about the homeostatic function of M2‐like resident ATM s, recent evidence suggests roles in AT expansion, thermoregulation, antigen presentation, and iron homeostasis. The field of immunometabolism has come a long way in the past decade, and many exciting new discoveries are bound to be made in the coming years that will expand our understanding of how AT stands at the junction of immune and metabolic co‐regulation.