Krüppel-like factor 4 regulates macrophage polarization
Xudong Liao, … , Karine Clément, Mukesh K. Jain
Xudong Liao, … , Karine Clément, Mukesh K. Jain
Published June 13, 2011
Citation Information: J Clin Invest. 2011;121(7):2736-2749. https://doi.org/10.1172/JCI45444.
View: Text | PDF
Research Article Inflammation Article has an altmetric score of 10

Krüppel-like factor 4 regulates macrophage polarization

Abstract

Current paradigms suggest that two macrophage subsets, termed M1 and M2, are involved in inflammation and host defense. While the distinct functions of M1 and M2 macrophages have been intensively studied — the former are considered proinflammatory and the latter antiinflammatory — the determinants of their speciation are incompletely understood. Here we report our studies that identify Krüppel-like factor 4 (KLF4) as a critical regulator of macrophage polarization. Macrophage KLF4 expression was robustly induced in M2 macrophages and strongly reduced in M1 macrophages, observations that were recapitulated in human inflammatory paradigms in vivo. Mechanistically, KLF4 was found to cooperate with Stat6 to induce an M2 genetic program and inhibit M1 targets via sequestration of coactivators required for NF-κB activation. KLF4-deficient macrophages demonstrated increased proinflammatory gene expression, enhanced bactericidal activity, and altered metabolism. Furthermore, mice bearing myeloid-specific deletion of KLF4 exhibited delayed wound healing and were predisposed to developing diet-induced obesity, glucose intolerance, and insulin resistance. Collectively, these data identify KLF4 as what we believe to be a novel regulator of macrophage polarization.

Authors

Xudong Liao, Nikunj Sharma, Fehmida Kapadia, Guangjin Zhou, Yuan Lu, Hong Hong, Kaavya Paruchuri, Ganapati H. Mahabeleshwar, Elise Dalmas, Nicolas Venteclef, Chris A. Flask, Julian Kim, Bryan W. Doreian, Kurt Q. Lu, Klaus H. Kaestner, Anne Hamik, Karine Clément, Mukesh K. Jain

×

Figure 2

KLF4 is essential for IL-4–mediated macrophage M2 polarization.

Options: View larger image (or click on image) Download as PowerPoint
KLF4 is essential for IL-4–mediated macrophage M2 polarization. (A) Impa...
(A) Impairment of M2 marker gene expression in KLF4-deficient macrophages. PMs isolated from Mye-WT and Mye-KO mice were treated with IL-4 for 16 hours. n = 3 in each group. (B) KLF4 overexpression enhances M2 gene expression. RAW264.7 cells were infected with either Ad-GFP (Ad-EV) or Ad-KLF4 for 24 hours prior to treatment with IL-4 for 16 hours. n = 3 in each group. (C) Representative Western blot showing IL-4–mediated protein induction of Arg-1, Retnla, Chi3l3, and PPARγ in Mye-WT and Mye-KO macrophages. (D) Quantification of Western blot data by densitometry. For Arg-1, protein levels were normalized to Mye-WT control group. For Retnla, Chi3l3 and PPARγ, only IL-4–induced protein levels were calculated and normalized to the IL-4–treated Mye-WT group, due to extremely low levels of expression at baseline. Data were calculated from 3–5 independent blots. (E) Synergistic activation of the mouse Arg1 promoter by KLF4 and Stat6 as assayed by transient transfection. WT, ~4 kb WT mouse Arg1 promoter; ΔKLF, Arg1 promoter with both KLF-binding sites mutated; ΔStat6: Arg1 promoter with Stat6-binding site mutated. Transient transfection experiments were performed in RAW264.7 cells. n = 3. (F) KLF4 binding to Arg1 promoter detected by ChIP assay in WT and Stat6-null BMDMs with or without IL-4 treatment (4 hours). *P < 0.05, **P < 0.01, Student’s t test with Bonferroni correction.