Skip to main page content
U.S. flag
See More

An official website of the United States government

Dot gov

The .gov means it’s official.
Federal government websites often end in .gov or .mil. Before sharing sensitive information, make sure you’re on a federal government site.

Https

The site is secure.
The https:// ensures that you are connecting to the official website and that any information you provide is encrypted and transmitted securely.

Access keys NCBI Homepage MyNCBI Homepage Main Content Main Navigation
Comparative Study
. 2006 Jul;4(1):13-24.
doi: 10.1016/j.cmet.2006.05.011.

Oxidative metabolism and PGC-1beta attenuate macrophage-mediated inflammation

Divya Vats  1 , Lata Mukundan, Justin I Odegaard, Lina Zhang, Kristi L Smith, Christine R Morel, Roger A Wagner, David R Greaves, Peter J Murray, Ajay Chawla
Affiliations
Comparative Study

Oxidative metabolism and PGC-1beta attenuate macrophage-mediated inflammation

Divya Vats et al. Cell Metab. 2006 Jul.

Erratum in

  • Cell Metab. 2006 Sep;4(3):255. Wagner, Roger A [added]

Abstract

Complex interplay between T helper (Th) cells and macrophages contributes to the formation and progression of atherosclerotic plaques. While Th1 cytokines promote inflammatory activation of lesion macrophages, Th2 cytokines attenuate macrophage-mediated inflammation and enhance their repair functions. In spite of its biologic importance, the biochemical and molecular basis of how Th2 cytokines promote maturation of anti-inflammatory macrophages is not understood. We show here that in response to interleukin-4 (IL-4), signal transducer and activator of transcription 6 (STAT6) and PPARgamma-coactivator-1beta (PGC-1beta) induce macrophage programs for fatty acid oxidation and mitochondrial biogenesis. Transgenic expression of PGC-1beta primes macrophages for alternative activation and strongly inhibits proinflammatory cytokine production, whereas inhibition of oxidative metabolism or RNAi-mediated knockdown of PGC-1beta attenuates this immune response. These data elucidate a molecular pathway that directly links mitochondrial oxidative metabolism to the anti-inflammatory program of macrophage activation, suggesting a potential role for metabolic therapies in treating atherogenic inflammation.

PubMed Disclaimer

Figures

Figure 1
Figure 1. Induction of oxidative metabolism and PGC-1β during alternative macrophage activation
A) Cluster analysis of macrophage gene expression during alternative and classical activation. Note the reciprocal pattern of expression for inflammatory genes with those involved in fatty acid metabolism. B) IL-4 induces genes required for fatty acid metabolism in a STAT6-dependent manner. Average fold induction relative to untreated wild-type sample is indicated. C) Induction of endogenous PGC-1β protein by IL-4 in a STAT6-dependent manner. 75 μg of total cellular lysates from wild-type or STAT6 null macrophages were subjected to immunoblot analysis with a PGC-1β antibody. Top panel: bone marrow-derived macrophages (BMDM); bottom panel: thioglycolate (TG)-elicited macrophages. D–F) Alternative activation increases reliance on fatty acid metabolism, as measured by uptake of glucose (C), uptake of fatty acids (D), and β-oxidation of fatty acids (E). *p < 0.05, **p < 0.005.
Figure 2
Figure 2. Requirement for oxidative metabolism in maturation of anti-inflammatory alternatively activated macrophages
A) Inhibition or uncoupling of mitochondrial respiration prevents induction of arginase activity by IL-4. B) Mitochondrial respiration is required for expression of the alternative phenotype, as quantified by induction of various mRNAs. C–E) Mitochondrial inhibitors diminish the anti-inflammatory effects of IL-4. Control and treated macrophages were costimulated with IFNγ (1 u/ml) / LPS (2.5 ng/ml) in the presence or absence of IL-4 (5 ng/ml). ELISAs were used to quantify the secreted (C) IL-6, (D) IL-12p40 and (E) TNF-α by macrophages. Eto, etomoxir; Oligo, oligomycin. **p < 0.005. F) IL-4 signaling is intact in macrophages treated with metabolic inhibitors, as measured by induction of PGC-1β and phosphorylation of STAT6.
Figure 3
Figure 3. STAT6 regulates oxidative metabolism in alternatively activated macrophages
A) Identification of STAT6 binding sites in MCAD promoter. NRRE, nuclear receptor response element. Gel mobility shift assays were performed with nuclear extracts from wild-type and STAT6 null macrophages; SS-supershift of STAT6. B) STAT6 homodimers transactivate the MCAD promoter. Note that mutation of STATRE in the MCAD promoter abolishes IL-4 induction, but raises basal promoter activity. C–E) Loss of STAT6 affects both basal and IL-4 induced metabolic fluxes in macrophages; (C) fatty acid uptake, (D) fatty acid oxidation, and (E) glucose uptake. *p < 0.05, **p < 0.005. F and G) Stimulation with IL-4 fails to increase cellular mitochondrial content in STAT6−/− macrophages, as measured by (F) MitoFluor Green and (G) VDAC1, α-ATPase, and CytC protein levels. Equivalent loading was confirmed by immunoblotting for β-actin.
Figure 4
Figure 4. PGC-1β enhances maturation of anti-inflammatory alternatively activated macrophages
A) Coactivation of STAT6 by PGC-1β on arginase I promoter. RAW264.7 cells were transiently transfected with wild-type arginase I promoter (Arg I-luc) or STAT6RE mutant (Arg-ΔSTAT6-luc) reporter constructs, in the presence or absence of PGC-1β. B) Coimmunoprecipitation of PGC-1β and STAT6. C) Real-time ChIP analysis for the arginase promoter. Both STAT6 and PGC-1β are recruited to the arginase promoter after stimulation of macrophages with IL-4. D) PGC-1β enhances arginase activity during alternative macrophage activation. E and F) Expression of PGC-1β attenuates inflammatory activation of macrophages. ELISA measurements for secreted IL-6 (E) and IL-12 p40 subunit (F). *p < 0.02, **p < 0.005.
Figure 5
Figure 5. Requirement for PGC-1β in alternative macrophage activation
A) Knockdown of endogenous PGC-1β protein by retroviral expression of RNAi. Wild-type macrophages were stably infected with retroviral vectors expressing shRNAs against GFP or PGC-1β. Whole-cell lysates were analyzed by immunoblotting for endogenous PGC-1β. B) Requirement for PGC-1β in IL-4-stimulated increase in β-oxidation of fatty acids. C) Arginase activity in control and PGC-1β knockdown macrophages. Macrophages were stimulated IL-4 (5 ng/ml) for 24 hr prior to assaying for urea production. D and E) Role of PGC-1β in inhibition of macrophage inflammatory activation. Macrophages were stimulated by LPS (1 ng/ml) in the presence of IL-4 (2 ng/ml), and secreted cytokine culture supernatants were quantified by ELISAs. Representative data are shown above (n = 3). *p < 0.05; **p < 0.004.
Figure 6
Figure 6. Transgenic expression of PGC-1β potentiates alternative activation and attenuates macrophage-mediated inflammation in vivo
A) hCD68 promoter directs PGC-1β transgene expression to macrophages. Lysates from wild-type or Mac-PGC-1β macrophages were analyzed by immunoblotting for PGC-1β (middle panel). PGC-1β is expressed at a level equivalent to that found in IL-4-stimulated wild-type macrophages (right panel). B) PGC-1β potentiates expression of arginase I mRNA, as assessed by Northern blots. C) Fold increase in arginase activity in macrophages from wild-type and Mac-PGC-1β mice after stimulation with IL-4 (2 ng/ml) for 24 hr. D and E) Transgenic expression of PGC-1β attenuates macrophage inflammatory burst. BMDM from wild-type and PGC-1β transgenic mice were stimulated with IFNγ (1 u/ml) for 20 hr prior to challenge with LPS (0.5 ng/ml). Cytokine secretion was assayed 6 hr later by ELISAs. *p < 0.04.
Figure 7
Figure 7
Model for regulation of macrophage activation by metabolic regulators HIF-1α and Th1-type stimuli increase glycolytic metabolism to support proinflammatory classical activation of macrophages. In contrast, in response to Th2 cytokine IL-4, STAT6, and PGC-1β enhance oxidative metabolism and promote expression of the less-inflammatory alternative phenotype.
See this image and copyright information in PMC

Comment in

References

    1. Arnaud C, Braunersreuther V, Mach F. Toward immunomodulatory and anti-inflammatory properties of statins. Trends Cardiovasc Med. 2005;15:202–206. - PubMed
    1. Binder CJ, Chang MK, Shaw PX, Miller YI, Hartvigsen K, Dewan A, Witztum JL. Innate and acquired immunity in atherogenesis. Nat Med. 2002;8:1218–1226. - PubMed
    1. Chawla A, Barak Y, Nagy L, Liao D, Tontonoz P, Evans RM. PPAR-gamma dependent and independent effects on macrophage-gene expression in lipid metabolism and inflammation. Nat Med. 2001;7:48–52. - PubMed
    1. Cramer T, Yamanishi Y, Clausen BE, Forster I, Pawlinski R, Mackman N, Haase VH, Jaenisch R, Corr M, Nizet V, et al. HIF-1alpha is essential for myeloid cell-mediated inflammation. Cell. 2003;112:645–657. - PMC - PubMed
    1. Djouadi F, Brandt JM, Weinheimer CJ, Leone TC, Gonzalez FJ, Kelly DP. The role of the peroxisome proliferator-activated receptor alpha (PPAR alpha) in the control of cardiac lipid metabolism. Prostaglandins Leukot Essent Fatty Acids. 1999;60:339–343. - PubMed

Publication types

MeSH terms

Associated data