Limits...
Autocrine IL-10 functions as a rheostat for M1 macrophage glycolytic commitment by tuning nitric oxide production ☆ ☆ ☆

View Article: PubMed Central - PubMed

ABSTRACT

Inflammatory maturation of M1 macrophages by proinflammatory stimuli such as toll like receptor ligands results in profound metabolic reprogramming resulting in commitment to aerobic glycolysis as evidenced by repression of mitochondrial oxidative phosphorylation (OXPHOS) and enhanced glucose utilization. In contrast, “alternatively activated” macrophages adopt a metabolic program dominated by fatty acid-fueled OXPHOS. Despite the known importance of these developmental stages on the qualitative aspects of an inflammatory response, relatively little is know regarding the regulation of these metabolic adjustments. Here we provide evidence that the immunosuppressive cytokine IL-10 defines a metabolic regulatory loop. Our data show for the first time that lipopolysaccharide (LPS)-induced glycolytic flux controls IL-10-production via regulation of mammalian target of rapamycin (mTOR) and that autocrine IL-10 in turn regulates macrophage nitric oxide (NO) production. Genetic and pharmacological manipulation of IL-10 and nitric oxide (NO) establish that metabolically regulated autocrine IL-10 controls glycolytic commitment by limiting NO-mediated suppression of OXPHOS. Together these data support a model where autocine IL-10 production is controlled by glycolytic flux in turn regulating glycolytic commitment by preserving OXPHOS via suppression of NO. We propose that this IL-10-driven metabolic rheostat maintains metabolic equilibrium during M1 macrophage differentiation and that perturbation of this regulatory loop, either directly by exogenous cellular sources of IL-10 or indirectly via limitations in glucose availability, skews the cellular metabolic program altering the balance between inflammatory and immunosuppressive phenotypes.

No MeSH data available.


Primary metabolomic analyses reveal broad scale alterations to glycolytic and TCA cycle metabolites inIl10−/−M1 macrophages. WT and Il10−/− BMDM were incubated for 24 h in 100 ng/mL LPS prior to GC-TOF analyses. Schematics shown summarize the fold change differences when comparing LPS stimulated Il10−/− vs LPS stimulated WT macrophages (a). Colors indicate upregulation (red), downregulation (blue), unchanged (black), or undefined (grey) metabolites. All red or blue colors are statistically significant (p-value<0.05 and fold change >10%) except for glucose 6-phosphate (p-value<0.055, a). (For interpretation of the references to color in this figure legend, the reader is referred to the web version of this article.)
© Copyright Policy - CC BY-NC-ND
Related In: Results  -  Collection

License
getmorefigures.php?uid=PMC5037266&req=5

f0030: Primary metabolomic analyses reveal broad scale alterations to glycolytic and TCA cycle metabolites inIl10−/−M1 macrophages. WT and Il10−/− BMDM were incubated for 24 h in 100 ng/mL LPS prior to GC-TOF analyses. Schematics shown summarize the fold change differences when comparing LPS stimulated Il10−/− vs LPS stimulated WT macrophages (a). Colors indicate upregulation (red), downregulation (blue), unchanged (black), or undefined (grey) metabolites. All red or blue colors are statistically significant (p-value<0.05 and fold change >10%) except for glucose 6-phosphate (p-value<0.055, a). (For interpretation of the references to color in this figure legend, the reader is referred to the web version of this article.)

Mentions: Recently, broad scale metabolomic studies on LPS-treated BMDM have shed light on metabolite fluxuations that underlies the phenotypic manifestations associated with glycolytic commitment [4]. Indeed, we also show global metabolic shifts in LPS-treated BMDM including upregulation of glycolytic metabolites (6/7 assayed) (Fig S2). In addition, LPS-treated BMDM have higher citrate, cis-aconitate and itaconic acid levels; known markers of M1 macrophage polarization [17]. Because our data suggest that both IL-10 and NO play major roles in glycolytic commitment of M1 macrophages, we performed unbiased metabolomic studies on WT, and Il10−/− BMDM cultured with or without LPS for 24 h (Fig. 6). In agreement with our metabolic flux data, LPS stimulated Il10−/− BMDM had elevated levels of glycolytic metabolites (4/7 assayed) and more pronounced suppression of TCA metabolites (5/6 assayed) when compared to LPS treated WT BMDM (Fig. 6). Notably, the LPS-induced increase in succinate in WT cells was abolished in macrophages lacking IL-10 yet the reductions of alpha-ketogluterate, indicative of the LPS-induced “TCA break”, is completely intact. This suggests the effects of IL-10 on metabolism are downstream of the break and that they may impact Hif-1α activation by restraining succinate levels. LPS treated Il10−/− BMDM also had decreased pyruvate and lactate levels consistent with their enhanced Ldha expression (Fig. 2D), and elevated ECAR (Fig. 6).


Autocrine IL-10 functions as a rheostat for M1 macrophage glycolytic commitment by tuning nitric oxide production ☆ ☆ ☆
Primary metabolomic analyses reveal broad scale alterations to glycolytic and TCA cycle metabolites inIl10−/−M1 macrophages. WT and Il10−/− BMDM were incubated for 24 h in 100 ng/mL LPS prior to GC-TOF analyses. Schematics shown summarize the fold change differences when comparing LPS stimulated Il10−/− vs LPS stimulated WT macrophages (a). Colors indicate upregulation (red), downregulation (blue), unchanged (black), or undefined (grey) metabolites. All red or blue colors are statistically significant (p-value<0.05 and fold change >10%) except for glucose 6-phosphate (p-value<0.055, a). (For interpretation of the references to color in this figure legend, the reader is referred to the web version of this article.)
© Copyright Policy - CC BY-NC-ND
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC5037266&req=5

f0030: Primary metabolomic analyses reveal broad scale alterations to glycolytic and TCA cycle metabolites inIl10−/−M1 macrophages. WT and Il10−/− BMDM were incubated for 24 h in 100 ng/mL LPS prior to GC-TOF analyses. Schematics shown summarize the fold change differences when comparing LPS stimulated Il10−/− vs LPS stimulated WT macrophages (a). Colors indicate upregulation (red), downregulation (blue), unchanged (black), or undefined (grey) metabolites. All red or blue colors are statistically significant (p-value<0.05 and fold change >10%) except for glucose 6-phosphate (p-value<0.055, a). (For interpretation of the references to color in this figure legend, the reader is referred to the web version of this article.)
Mentions: Recently, broad scale metabolomic studies on LPS-treated BMDM have shed light on metabolite fluxuations that underlies the phenotypic manifestations associated with glycolytic commitment [4]. Indeed, we also show global metabolic shifts in LPS-treated BMDM including upregulation of glycolytic metabolites (6/7 assayed) (Fig S2). In addition, LPS-treated BMDM have higher citrate, cis-aconitate and itaconic acid levels; known markers of M1 macrophage polarization [17]. Because our data suggest that both IL-10 and NO play major roles in glycolytic commitment of M1 macrophages, we performed unbiased metabolomic studies on WT, and Il10−/− BMDM cultured with or without LPS for 24 h (Fig. 6). In agreement with our metabolic flux data, LPS stimulated Il10−/− BMDM had elevated levels of glycolytic metabolites (4/7 assayed) and more pronounced suppression of TCA metabolites (5/6 assayed) when compared to LPS treated WT BMDM (Fig. 6). Notably, the LPS-induced increase in succinate in WT cells was abolished in macrophages lacking IL-10 yet the reductions of alpha-ketogluterate, indicative of the LPS-induced “TCA break”, is completely intact. This suggests the effects of IL-10 on metabolism are downstream of the break and that they may impact Hif-1α activation by restraining succinate levels. LPS treated Il10−/− BMDM also had decreased pyruvate and lactate levels consistent with their enhanced Ldha expression (Fig. 2D), and elevated ECAR (Fig. 6).

View Article: PubMed Central - PubMed

ABSTRACT

Inflammatory maturation of M1 macrophages by proinflammatory stimuli such as toll like receptor ligands results in profound metabolic reprogramming resulting in commitment to aerobic glycolysis as evidenced by repression of mitochondrial oxidative phosphorylation (OXPHOS) and enhanced glucose utilization. In contrast, &ldquo;alternatively activated&rdquo; macrophages adopt a metabolic program dominated by fatty acid-fueled OXPHOS. Despite the known importance of these developmental stages on the qualitative aspects of an inflammatory response, relatively little is know regarding the regulation of these metabolic adjustments. Here we provide evidence that the immunosuppressive cytokine IL-10 defines a metabolic regulatory loop. Our data show for the first time that lipopolysaccharide (LPS)-induced glycolytic flux controls IL-10-production via regulation of mammalian target of rapamycin (mTOR) and that autocrine IL-10 in turn regulates macrophage nitric oxide (NO) production. Genetic and pharmacological manipulation of IL-10 and nitric oxide (NO) establish that metabolically regulated autocrine IL-10 controls glycolytic commitment by limiting NO-mediated suppression of OXPHOS. Together these data support a model where autocine IL-10 production is controlled by glycolytic flux in turn regulating glycolytic commitment by preserving OXPHOS via suppression of NO. We propose that this IL-10-driven metabolic rheostat maintains metabolic equilibrium during M1 macrophage differentiation and that perturbation of this regulatory loop, either directly by exogenous cellular sources of IL-10 or indirectly via limitations in glucose availability, skews the cellular metabolic program altering the balance between inflammatory and immunosuppressive phenotypes.

No MeSH data available.