Metallothionein 3 Controls the Phenotype and Metabolic Programming of Alternatively Activated Macrophages.
ABSTRACT: Alternatively activated (M2) macrophages promote wound healing but weaken antimicrobial defenses. The mechanisms that enforce macrophage divergence and dictate the phenotypic and metabolic characteristics of M2 macrophages remain elusive. We show that alternative activation with interleukin (IL)-4 induces expression of metallothionein 3 (MT3) that regulates macrophage polarization and function. MT3 was requisite for metabolic reprograming in IL-4-stimulated macrophages or M(IL-4) macrophages to promote mitochondrial respiration and suppress glycolysis. MT3 fostered an M(IL-4) phenotype, suppressed hypoxia inducible factor (HIF)1? activation, and thwarted the emergence of a proinflammatory M1 program in macrophages. MT3 deficiency augmented macrophage plasticity, resulting in enhanced interferon ? (IFN?) responsiveness and a dampened M(IL-4) phenotype. Thus, MT3 programs the phenotype and metabolic fate of M(IL-4) macrophages.
Project description:Alternative activation of macrophages promotes wound healing but weakens antimicrobial defenses against intracellular pathogens. The mechanisms that suppress macrophage function to create a favorable environment for pathogen growth remain elusive. We show that interleukin (IL)-4 triggers a metallothionein 3 (MT3)- and Zn exporter SLC30A4-dependent increase in the labile Zn(2+) stores in macrophages and that intracellular pathogens can exploit this increase in Zn to survive. IL-4 regulates this pathway by shuttling extracellular Zn into macrophages and by activating cathepsins that act on MT3 to release bound Zn. We show that IL-4 can modulate Zn homeostasis in both human monocytes and mice. In vivo, MT3 can repress macrophage function in an M2-polarizing environment to promote pathogen persistence. Thus, MT3 and SLC30A4 dictate the size of the labile Zn(2+) pool and promote the survival of a prototypical intracellular pathogen in M2 macrophages.
Project description:Macrophages are tissue resident immune cells important for host defence and homeostasis. During diabetes, macrophages and other innate immune cells are known to have a pro-inflammatory phenotype, which is believed to contribute to the pathogenesis of various diabetic complications. However, diabetic patients are highly susceptible to bacterial infections, and often have impaired wound healing. The molecular mechanism underlying the paradox of macrophage function in diabetes is not fully understood. Recent evidence suggests that macrophage functions are governed by metabolic reprograming. Diabetes is a disorder that affects glucose metabolism; dysregulated macrophage function in diabetes may be related to alterations in their metabolic pathways. In this study, we seek to understand the effect of high glucose exposure on macrophage phenotype and functions.Bone marrow cells were cultured in short or long term high glucose and normal glucose medium; the number and phenotype of bone marrow derived macrophages were not affected by long-term high glucose treatment. Short-term high glucose increased the expression of IL-1?. Long-term high glucose increased the expression of IL-1? and TNF? but reduced the expression of IL-12p40 and nitric oxide production in M1 macrophage. The treatment also increased Arg-1 and IL-10 expression in M2 macrophages. Phagocytosis and bactericidal activity was reduced in long-term high glucose treated macrophages and peritoneal macrophages from diabetic mice. Long-term high glucose treatment reduced macrophage glycolytic capacity and glycolytic reserve without affecting mitochondrial ATP production and oxidative respiration.Long-term high glucose sensitizes macrophages to cytokine stimulation and reduces phagocytosis and nitric oxide production, which may be related to impaired glycolytic capacity.
Project description:Macrophage polarization has been implicated in the pathogenesis of metabolic diseases such as obesity, diabetes, and atherosclerosis. Macrophages responsiveness to polarizing signals can result in their functional phenotype shifts. This study examined whether high glucose induced the functional transition of M2 macrophages, which was inhibited by asaronic acid, one of purple perilla constituents. J774A.1 murine macrophages were incubated with 40 ng/mL interleukin (IL)-4 or exposed to 33 mM glucose in the presence of 1-20 ?? asaronic acid. In macrophages treated with IL-4 for 48 h, asaronic acid further accelerated cellular induction of the M2 markers of IL-10, arginase-1, CD163, and PPAR? via increased IL-4-IL-4R? interaction and activated Tyk2-STAT6 pathway. Asaronic acid promoted angiogenic and proliferative capacity of M2-polarized macrophages, through increasing expression of VEGF, PDGF, and TGF-?. In glucose-loaded macrophages, there was cellular induction of IL-4, IL-4 R?, arginase-1, and CD163, indicating that high glucose skewed naïve macrophages toward M2 phenotypes via an IL-4-IL-4R? interaction. However, asaronic acid inhibited M2 polarization in diabetic macrophages in parallel with inactivation of Tyk2-STAT6 pathway and blockade of GLUT1-mediated metabolic pathway of Akt-mTOR-AMPK?. Consequently, asaronic acid deterred functional induction of COX-2, CTGF, ?-SMA, SR-A, SR-B1, and ABCG1 in diabetic macrophages with M2 phenotype polarity. These results demonstrated that asaronic acid allayed glucose-activated M2-phenotype shift through disrupting coordinated signaling of IL-4R?-Tyk2-STAT6 in parallel with GLUT1-Akt-mTOR-AMPK pathway. Thus, asaronic acid has therapeutic potential in combating diabetes-associated inflammation, fibrosis, and atherogenesis through inhibiting glucose-evoked M2 polarization.
Project description:The immune responses of type 2 T helper cells (Th2) play an important role in asthma and promote the differentiation of alternatively activated (M2) macrophages. M2 macrophages have been increasingly understood to contribute to Th2 immunity. We hypothesized that M2 macrophages are altered in asthma and modulate Th2 responses. The aim of this study was to characterize the phenotype and function of human monocyte-derived M2 and bronchoalveolar lavage fluid (BALF) macrophages from healthy control subjects and subjects with asthma. Phenotypic characteristics and effector function of M2 macrophages were examined using monocyte-derived and BALF macrophages obtained from subjects with asthma (n?=?28) and healthy volunteers (n?=?9) by flow cytometry and quantitative PCR. Resting monocyte-derived (M0) and M2 macrophages were generated by the addition of macrophage colony-stimulating factor or macrophage colony-stimulating factor plus IL-4, respectively. M2 macrophage cytokine expression and their impact on dendritic and CD4+ T cell activation were examined in vitro. High levels of CD206 and major histocompatibility complex class II expression identify macrophages with an M2 phenotype that are increased 2.9-fold in the BALF of subjects with asthma compared with control subjects. M2 macrophages have elevated IL-6, IL-10, and IL-12p40 production compared with conventional macrophages and modulate dendritic and CD4+ T cell interactions. Histamine receptor 1 and E-cadherin expression identify M2 macrophage subsets associated with increased airflow obstruction. M2 macrophages have a distinct cell surface and effector phenotype and are found in increased numbers in subjects with asthma. These findings suggest that M2 macrophages may play an important role in allergic asthma through their bidirectional interactions with immune and structural cells, and inflammatory mediators.
Project description:The polarization of adipose tissue-resident macrophages toward the alternatively activated, anti-inflammatory M2 phenotype is believed to improve insulin sensitivity. However, the mechanisms controlling tissue macrophage activation remain unclear. Here we show that adipocytes are a source of Th2 cytokines, including IL-13 and to a lesser extent IL-4, which induce macrophage PPARdelta/beta (Ppard/b) expression through a STAT6 binding site on its promoter to activate alternative activation. Coculture studies indicate that Ppard ablation renders macrophages incapable of transition to the M2 phenotype, which in turns causes inflammation and metabolic derangement in adipocytes. Remarkably, a similar regulatory mechanism by hepatocyte-derived Th2 cytokines and macrophage PPARdelta is found to control hepatic lipid metabolism. The physiological relevance of this paracrine pathway is demonstrated in myeloid-specific PPARdelta(-/-) mice, which develop insulin resistance and show increased adipocyte lipolysis and severe hepatosteatosis. These findings provide a molecular basis to modulate tissue-resident macrophage activation and insulin sensitivity.
Project description:Metabolic reprogramming has been intrinsically linked to macrophage activation. Alveolar macrophages are known to play an important role in the pathogenesis of pulmonary fibrosis. However, systematic characterization of expression profile in these cells is still lacking. Furthermore, main metabolic programs and their regulation of cellular phenotype are completely unknown. In this study, we comprehensively analyzed the expression profile and main metabolic programs in alveolar macrophages from mice with or without experimental pulmonary fibrosis. We found that alveolar macrophages from both bleomycin and active TGF-?1-induced fibrotic mouse lungs demonstrated a primarily profibrotic M2-like profile that was distinct from the well-defined M1 or any of the M2 subtypes. More importantly, we found that fibrotic lung alveolar macrophages assumed augmented glycolysis, which was likely attributed to enhanced expression of multiple key glycolytic mediators. We also found that fatty acid oxidation was upregulated in these cells. However, the profibrotic M2-like profile of fibrotic lung alveolar macrophages was not dependent on fatty acid oxidation and synthesis or lipolysis, but instead on glycolysis, in contrast to the typical IL-4-induced macrophages M(IL-4). Additionally, glutaminolysis, a key metabolic program that has been implicated in numerous pathologies, was not required for the profibrotic M2-like phenotype of these macrophages. In summary, our study identifies a unique expression and metabolic profile in alveolar macrophages from fibrotic lungs and suggests glycolytic inhibition as an effective antifibrotic strategy in treating lung fibrosis.
Project description:Backgrounds and Aims: Hepatocyte Growth Factor (HGF)-MET signaling is known to promote biological functions such as cell survival, cell motility, and cell proliferation. However, it is unknown if HGF-MET alters the macrophage phenotype. In this study, we aimed to study the effects of HGF-MET signaling on the M1 macrophage phenotype. Methods and Materials: Bone marrow-derived macrophages (BMDMs) isolated from mice were either polarized to an M1 phenotype by IFN-? and LPS treatment or to an M2 phenotype by IL-4 treatment. Changes in M1 or M2 markers induced by HGF-MET signaling were evaluated. Mechanisms responsible for alternations in the macrophage phenotype and intracellular metabolism were analyzed. Results: c-Met was expressed especially in M1 macrophages polarized by treatment with IFN-? and LPS. In M1 macrophages, HGF-MET signaling induced the expression of Arg-1 mRNA and secretion of IL-10 and TGF-?1 and downregulated the mRNA expression of iNOS, TNF-?, and IL-6. In addition, activation of the PI3K pathway and inactivation of NF?B were also observed in M1 macrophages treated with HGF. The increased Arg-1 expression and IL-10 secretion were abrogated by PI3K inhibition, whereas, no changes were observed in TNF-? and IL-6 expression. The inactivation of NF?B was found to be independent of the PI3K pathway. HGF-MET signaling shifted the M1 macrophages to an M2-like phenotype, mainly through PI3K-mediated induction of Arg-1 expression. Finally, HGF-MET signaling also shifted the M1 macrophage intracellular metabolism toward an M2 phenotype, especially with respect to fatty acid metabolism. Conclusion: Our results suggested that HGF treatment not only promotes regeneration in epithelial cells, but also leads to tissue repair by altering M1 macrophages to an M2-like phenotype.
Project description:Macrophages activated by the TLR4 agonist LPS undergo dramatic changes in their metabolic activity. We here show that LPS induces expression of the key metabolic regulator Pyruvate Kinase M2 (PKM2). Activation of PKM2 using two well-characterized small molecules, DASA-58 and TEPP-46, inhibited LPS-induced Hif-1? and IL-1?, as well as the expression of a range of other Hif-1?-dependent genes. Activation of PKM2 attenuated an LPS-induced proinflammatory M1 macrophage phenotype while promoting traits typical of an M2 macrophage. We show that LPS-induced PKM2 enters into a complex with Hif-1?, which can directly bind to the IL-1? promoter, an event that is inhibited by activation of PKM2. Both compounds inhibited LPS-induced glycolytic reprogramming and succinate production. Finally, activation of PKM2 by TEPP-46 in vivo inhibited LPS and Salmonella typhimurium-induced IL-1? production, while boosting production of IL-10. PKM2 is therefore a critical determinant of macrophage activation by LPS, promoting the inflammatory response.
Project description:BACKGROUND:Macrophage plasticity allows cells to adopt different phenotypes, a property with important implications in disorders such as cystic fibrosis (CF) and asthma. OBJECTIVE:We sought to examine the transcriptional and functional significance of macrophage repolarization from an M1 to an M2 phenotype and assess the role of a common human genetic disorder (CF) and a prototypical allergic disease (asthma) in this transformation. METHODS:Monocyte-derived macrophages were collected from healthy subjects and patients with CF and polarized to an M2 state by using IL-4, IL-10, glucocorticoids, apoptotic PMNs, or azithromycin. We performed transcriptional profiling and pathway analysis for each stimulus. We assessed the ability of M2-repolarized macrophages to respond to LPS rechallenge and clear apoptotic neutrophils and used murine models to determine conserved functional responses to IL-4 and IL-10. We investigated whether M2 signatures were associated with alveolar macrophage phenotypes in asthmatic patients. RESULTS:We found that macrophages exhibit highly diverse responses to distinct M2-polarizing stimuli. Specifically, IL-10 activated proinflammatory pathways and abrogated LPS tolerance, allowing rapid restoration of LPS responsiveness. In contrast, IL-4 enhanced LPS tolerance, dampening proinflammatory responses after repeat LPS challenge. A common theme observed across all M2 stimuli was suppression of interferon-associated pathways. We found that CF macrophages had intact reparative and transcriptional responses, suggesting that macrophage contributions to CF-related lung disease are primarily shaped by their environment. Finally, we leveraged in vitro-derived signatures to show that allergen provocation induces distinct M2 state transcriptional patterns in alveolar macrophages. CONCLUSION:Our findings highlight the diversity of macrophage polarization, attribute functional consequences to different M2 stimuli, and provide a framework to phenotype macrophages in disease states.
Project description:Inflammation is pivotal in atherosclerosis. Monocyte-macrophages are crucial in atherosclerosis. Monocytes can develop into subsets: classically (M1) or alternatively (M2) activated cells. Several studies point to a proinflammatory role for C-reactive protein (CRP). Because there is a paucity of data on the effects of CRP on macrophage phenotype, we tested effects of CRP on macrophage polarization.Monocytes were incubated with CRP (0 to 50 ?g/mL) and differentiated into macrophages for 7 days. Phenotypic characterization of M1 and M2 macrophages was performed using flow cytometry. CRP treatment resulted in increased population of M1 macrophages (tumor necrosis factor [TNF]/interleukin [IL]-12/C-C chemokine receptor 2, TNF/IL-12/monocyte chemotactic protein-1, or TNF/IL-1/IL-12). These effects were not abrogated by polymixin B or small interfering RNA to Toll-like receptor-4, but they were abrogated by boiled CRP. Administration of human CRP to rats in vivo increased polarization of macrophages to M1 phenotype compared with human serum albumin. When macrophages were primed to the M2 phenotype with IL-4, addition of CRP resulted in significantly increased secretion of TNF-?, MCP-1, and IL-1 and conversion of macrophages from the M2 to the M1 phenotype. CRP failed to prime macrophages to the M1 phenotype in presence of CD32/CD64 small interfering RNA or dominant-negative nuclear factor kappa B.Collectively, these results further support a role for CRP in promoting differentiation of human monocytes toward a proinflammatory M1 phenotype.