Metabolic Reprogramming Of Macrophages Research Articles

Metabolic Reprogramming Induces Macrophage Polarization in the Tumor Microenvironment.

Macrophages are one of the most important cells in the innate immune system, they are converted into two distinct subtypes with completely different molecular phenotypes and functional features under different stimuli of the microenvironment: M1 macrophages induced by IFN-γ/lipopolysaccharides(LPS) and M2 macrophages induced by IL-4/IL-10/IL-13. Tumor-associated macrophages (TAMs) differentiate from macrophages through various factors in the tumor microenvironment (TME). TAMs have the phenotype and function of M2 macrophages and are capable of secreting multiple cytokines to promote tumor progression. Both tumor cells and macrophages can meet the energy needs for rapid cell growth and proliferation through metabolic reprogramming, so a comprehensive understanding of pro-tumor and antitumor metabolic switches in TAM is essential to understanding immune escape mechanisms. This paper focuses on the functions of relevant signaling pathways and cytokines during macrophage polarization and metabolic reprogramming, and briefly discusses the effects of different microenvironments and macrophage pathogenicity, in addition to describing the research progress of inhibitory drugs for certain metabolic and polarized signaling pathways.

Reprogramming Macrophage Metabolism and its Effect on NLRP3 Inflammasome Activation in Sepsis.

Sepsis, the most common life-threatening multi-organ dysfunction syndrome secondary to infection, lacks specific therapeutic strategy due to the limited understanding of underlying mechanisms. It is currently believed that inflammasomes play critical roles in the development of sepsis, among which NLRP3 inflammasome is involved to most extent. Recent studies have revealed that dramatic reprogramming of macrophage metabolism is commonly occurred in sepsis, and this dysregulation is closely related with the activation of NLRP3 inflammasome. In view of the fact that increasing evidence demonstrates the mechanism of metabolism reprogramming regulating NLRP3 activation in macrophages, the key enzymes and metabolites participated in this regulation should be clearer for better interpreting the relationship of NLRP3 inflammasome and sepsis. In this review, we thus summarized the detail mechanism of the metabolic reprogramming process and its important role in the NLRP3 inflammasome activation of macrophages in sepsis. This mechanism summarization will reveal the applicational potential of metabolic regulatory molecules in the treatment of sepsis.

Prognostic significance of crown-like structures to trastuzumab response in patients with primary invasive HER2 + breast carcinoma

Obesity can initiate, promote, and maintain systemic inflammation via metabolic reprogramming of macrophages that encircle adipocytes, termed crown-like structures (CLS). In breast cancer the presence of CLS has been correlated to high body mass index (BMI), larger mammary adipocyte size and postmenopausal status. However, the prognostic significance of CLS in HER2 + breast cancer is still unknown. We investigated the prognostic significance of CLS in a cohort of 69 trastuzumab-naïve and 117 adjuvant trastuzumab-treated patients with primary HER2 + breast cancer. Immunohistochemistry of tumour blocks was performed for CLS and correlated to clinical outcomes. CLS were more commonly found at the adipose-tumour border (B-CLS) (64.8% of patients). The presence of multiple B-CLS was associated with reduced time to metastatic disease (TMD) in trastuzumab treated patients with BMI ≥ 25 kg/m2 but not those with BMI < 25 kg/m2. Phenotypic analysis showed the presence of CD32B + B-CLS was strongly correlated to BMI ≥ 25 kg/m2 and reduced TMD in trastuzumab treated patients. Multivariable analysis suggested that CD32B + B-CLS positive tumours are associated with shorter TMD in trastuzumab-treated patients (HR 4.2 [95%CI, (1.01–17.4). This study indicates adipose-tumour border crown-like structures that are CD32B + potentially represent a biomarker for improved personalisation of treatment in HER2-overexpressed breast cancer patients.

Long noncoding RNAs in regulation of inflammation, immune response, and glucose metabolism

Noncoding RNAs (ncRNAs) are emerging players in cell signaling and metabolism. Studies from our laboratory demonstrate that long noncoding RNA (lncRNA) HOTAIR plays critical roles in inflammation via regulation of NF‐kB activation and cytokine expression. HOTAIR also regulates glucose metabolism in macrophages during inflammation. Importantly, metabolic reprogramming is critically linked to inflammation and macrophage activation. Therefore, our findings showing the HOTAIR mediated regulation of glucose metabolism in macrophages indicate potential roles of lncRNAs in macrophage activation and metabolic reprogramming. In a recent study, we explored potential involvement of other ncRNAs in inflammation and immune signaling. Based on independent RNAseq analyses in mouse and human macrophages, we have discovered a series novel mouse and human lncRNAs which are potential regulators of cytokine expression, inflammation, and immune response. Notably, there appear to be poor conservation among the lncRNAs between mouse and human. Mechanistic studies demonstrated that some of the novel inflammatory lncRNAs are regulated via NF‐kB pathways while others are not, suggesting distinct modes of action of different lncRNAs during inflammatory response in macrophages. Here, we will present the discovery of novel mouse and human lncRNAs that are potential regulators of inflammation and immune signaling and discuss functional roles of selected lncRNAs in cytokine regulation, inflammation, and glucose metabolism in macrophages.

Metabolic Reprogramming Mediates Macrophage Polarization After Myocardial Infarction

BackgroundMacrophages play a critical role in left ventricular (LV) remodeling after myocardial infarction (MI), and limiting macrophage‐mediated inflammatory responses while enhancing reparative roles is a promising therapeutic strategy. Monocyte‐derived M1 macrophages mediate the early inflammatory response, while M2 macrophages mediate the later wound healing and scar formation phase. Metabolic reprogramming from glycolysis to mitochondrial oxidative phosphorylation mediates M1 to M2 polarization. We hypothesized that metabolic reprogramming occurs in macrophages over the course of post‐MI remodeling, and that blocking macrophage glycolysis attenuates post‐MI inflammation.MethodsMI was induced in adult (16‐20 week old) male C57BL/6J mice by permanent ligation of the left coronary artery for 1, 3, or 7 days, and cardiac function was assessed by echocardiography. Macrophages were extracted from the LV infarct area by immunomagnetic sorting. Macrophage metabolic flux was assessed by Extracellular Flux Analysis (Seahorse); upon glucose administration, glycolysis was measured by extracellular acidification rate (ECAR) while glucose oxidation was measured by oxygen consumption (OCR). Leukocyte subtypes (neutrophils, monocytes, resident macrophages) were assessed by flow cytometry. Real‐time PCR was used to assess gene expression by relative mRNA levels. To specifically block macrophage glycolysis, LysMCre mice were crossed with mice floxed for Slc2a1, the major macrophage glucose transporter, to generate macrophage‐Slc2a1 null mice.ResultsMI led to LV contractile dysfunction (decreased ejection fraction; days 1, 3, and 7 versus day 0), thinning of the infarct wall (days 1, 3, and 7) and non‐infarct wall (day 7), and dilation (increased internal diameter at diastole and end‐diastolic volume; day 7). At day 1, increased neutrophils (Ly6G+) and monocytes (Ly6Chi) were observed in the infarcted LV; at day 7, neutrophils and monocytes returned to baseline levels and the majority of macrophages were resident M2 subtype (Ly6Clow versus day 1). Day 1 macrophages showed elevated glycolysis (ECAR versus day 0) and increased mRNA levels of the M1 marker Il1b (versus day 3 and 7); day 3 macrophages showed increased glycolysis (ECAR versus day 0) and decreased glucose oxidation (versus day 0); day 7 macrophages showed decreased glycolysis (ECAR versus day 1 and 3) and increased glucose oxidation (OCR versus day 1 and 3), and increased Slc2a1 mRNA, Krebs cycle genes (Pdha1, Idh1/2, Sdha/bmRNA), pentose phosphate pathway genes (G6pd2/x, Pgd, Rpia, Taldo1 mRNA), and Il10 (M2 marker) mRNA. In macrophage‐Slc2a1 null mice, macrophage glycolysis was decreased and glucose oxidation increased at day 3, and infarct levels of Il1b were decreased compared to floxed controls.ConclusionsOur results indicate that time‐dependent macrophage metabolic reprogramming occurs over the MI remodeling process, and that blocking macrophage glycolysis may be a promising strategy for limiting post‐MI inflammation and adverse remodeling.

KLF7 Alleviates Atherosclerotic Lesions and Inhibits Glucose Metabolic Reprogramming in Macrophages by Regulating HDAC4/miR-148b-3p/NCOR1

Objectives: Atherosclerosis (AS) remains a major contributor to death worldwide. This study sought to explore the role of Krüppel-like factor 7 (KLF7) in AS lesions via regulating glucose metabolic reprogramming (GMR) in macrophages. Methods: AS mouse and cell models were established via high-fat-diet feeding and oxidized low-density lipoprotein (ox-LDL) induction. KLF7, histone deacetylase 4 (HDAC4), miR-148b-3p, and nuclear receptor corepressor 1 (NCOR1) expressions in aortic tissue and cells were detected via reverse transcription quantitative polymerase chain reaction or Western blotting. Parameters of AS lesions and mouse metabolism were detected via hematoxylin-eosin, oil red O, and Masson staining, assay kits, glucose tolerance test, and enzymatic analysis. Peritoneal macrophages of mice were isolated and cellular metabolism was detected via Seahorse metabolic flux analysis, assay kits, ELISA, and Western blotting. Bindings among KLF7, HDAC4, microRNA (miR)-148b-3p, and NCOR1 were testified via the dual-luciferase assay and chromatin immunoprecipitation assay. Results: KLF7 was poorly expressed in AS mice and ox-LDL-induced RAW264.7 cells. KLF7 overexpression attenuated AS lesions and rescued metabolic abnormities in AS mice, and reduced glucose intake and GMR in ox-LDL-induced RAW264.7 cells. Mechanically, KLF7 bound to the HDAC4 promoter to activate HDAC4. HDAC4 reduced H3 and H4 acetylation levels in the miR-148b promoter to inhibit miR-148b-3p and promote NCOR1 transcription. HDAC4 downregulation abolished the protective role of KLF7 overexpression in AS mice and ox-LDL-induced RAW264.7 cells via the miR-148b-3p/NCOR1 axis. Conclusion: KLF7 bound to the HDAC4 promoter to activate HDAC4, inhibit miR-148b-3p via reducing acetylation level, and promote NCOR1 transcription, thereby limiting GMR in macrophages and alleviating AS lesions.

Comparison of Macrophage Immune Responses and Metabolic Reprogramming in Smooth and Rough Variant Infections of Mycobacterium mucogenicum.

Mycobacterium mucogenicum (Mmuc), a rapidly growing nontuberculous mycobacterium (NTM), can infect humans (posttraumatic wound infections and catheter-related sepsis). Similar to other NTM species, Mmuc exhibits colony morphologies of rough (Mmuc-R) and smooth (Mmuc-S) types. Although there are several case reports on Mmuc infection, no experimental evidence supports that the R-type is more virulent. In addition, the immune response and metabolic reprogramming of Mmuc have not been studied on the basis of morphological characteristics. Thus, a standard ATCC Mmuc strain and two clinical strains were analyzed, and macrophages were generated from mouse bone marrow. Cytokines and cell death were measured by ELISA and FACS, respectively. Mitochondrial respiration and glycolytic changes were measured by XF seahorse. Higher numbers of intracellular bacteria were found in Mmuc-R-infected macrophages than in Mmuc-S-infected macrophages. Additionally, Mmuc-R induced higher levels of the cytokines TNF-α, IL-6, IL-12p40, and IL-10 and induced more BMDM necrotic death. Furthermore, our metabolic data showed marked glycolytic and respiratory differences between the control and each type of Mmuc infection, and changes in these parameters significantly promoted glucose metabolism, extracellular acidification, and oxygen consumption in BMDMs. In conclusion, at least in the strains we tested, Mmuc-R is more virulent, induces a stronger immune response, and shifts bioenergetic metabolism more extensively than the S-type. This study is the first to report differential immune responses and metabolic reprogramming after Mmuc infection and might provide a fundamental basis for additional studies on Mmuc pathogenesis.

Understanding the molecular mechanisms of macrophage polarization and metabolic reprogramming in endometriosis: A narrative review.

BackgroundEndometriosis is an estrogen‐dependent disease and causes pelvic pain and infertility. The limits of current pharmacotherapy in women who desire to become pregnant prompt the development of various targeted molecules for more effective treatment. A review article focused on the unique aspect of cellular metabolic reprogramming of endometriotic cells has been reported. The cellular metabolic pathways are reprogrammed to adapt to a variety of environmental stresses (e.g., nutrient starvation or glucose deprivation, hypoxic stress, excessive reactive oxygen species generation, and other environmental factors). This review aims to summarize macrophage polarization and metabolic reprogramming in endometriosis.MethodsA literature search was performed between January 2000 and March 2022 in the PubMed and Google Scholar databases using a combination of specific terms.ResultsMacrophage cellular metabolism has a marked influence on its phenotype and function. Preclinical studies showed that metabolic conversion toward glycolysis or oxidative phosphorylation drives macrophage polarization to M1 or M2 phenotype, respectively. Such cellular metabolic rewiring can offer new therapeutic opportunities.ConclusionA better understanding of metabolic reprogramming biology in endometriosis‐associated macrophages is essential in considering novel therapeutic approach for endometriosis. However, there are currently no detailed studies on therapeutic strategies targeting the cellular metabolic properties of endometriosis‐associated macrophages.

Branched-Chain Ketoacids Derived from Cancer Cells Modulate Macrophage Polarization and Metabolic Reprogramming

Branched-Chain Ketoacids Derived from Cancer Cells Modulate Macrophage Polarization and Metabolic Reprogramming

Impact of STING Inflammatory Signaling during Intracellular Bacterial Infections.

The early detection of bacterial pathogens through immune sensors is an essential step in innate immunity. STING (Stimulator of Interferon Genes) has emerged as a key mediator of inflammation in the setting of infection by connecting pathogen cytosolic recognition with immune responses. STING detects bacteria by directly recognizing cyclic dinucleotides or indirectly by bacterial genomic DNA sensing through the cyclic GMP-AMP synthase (cGAS). Upon activation, STING triggers a plethora of powerful signaling pathways, including the production of type I interferons and proinflammatory cytokines. STING activation has also been associated with the induction of endoplasmic reticulum (ER) stress and the associated inflammatory responses. Recent reports indicate that STING-dependent pathways participate in the metabolic reprogramming of macrophages and contribute to the establishment and maintenance of a robust inflammatory profile. The induction of this inflammatory state is typically antimicrobial and related to pathogen clearance. However, depending on the infection, STING-mediated immune responses can be detrimental to the host, facilitating bacterial survival, indicating an intricate balance between immune signaling and inflammation during bacterial infections. In this paper, we review recent insights regarding the role of STING in inducing an inflammatory profile upon intracellular bacterial entry in host cells and discuss the impact of STING signaling on the outcome of infection. Unraveling the STING-mediated inflammatory responses can enable a better understanding of the pathogenesis of certain bacterial diseases and reveal the potential of new antimicrobial therapy.

Complement-containing small extracellular vesicles from adventitial fibroblasts induce proinflammatory and metabolic reprogramming in macrophages.

Pulmonary hypertension (PH) is a severe cardiopulmonary disease characterized by complement-dependent, fibroblast-induced perivascular accumulation and proinflammatory activation of macrophages. We hypothesized that, in PH, nanoscale-sized small extracellular vesicles (sEVs), released by perivascular/adventitial fibroblasts, are critical mediators of complement-dependent proinflammatory activation of macrophages. Pulmonary adventitial fibroblasts were isolated from calves with severe PH (PH-Fibs) and age-matched controls (CO-Fibs). PH-Fibs exhibited increased secretion of sEVs, compared with CO-Fibs, and sEV biological activity was tested on mouse and bovine bone marrow–derived macrophages (BMDMs) and showed similar responses. Compared with sEVs derived from CO-Fibs, sEVs derived from PH-Fibs (PH-Fib-sEVs) induced augmented expression of proinflammatory cytokines/chemokines and metabolic genes in BMDMs. Pharmacological blockade of exosome release from PH-Fibs resulted in significant attenuation of proinflammatory activation of BMDMs. “Bottom-up” proteomic analyses revealed significant enrichment of complement and coagulation cascades in PH-Fib-sEVs, including augmented expression of the complement component C3. We therefore examined whether the PH-Fib-sEV–mediated proinflammatory activation of BMDMs was complement C3 dependent. Treatment of PH-Fibs with siC3-RNA significantly attenuated the capacity of PH-Fib-sEVs for proinflammatory activation of BMDMs. PH-Fib-sEVs mediated proglycolytic alterations and complement-dependent activation of macrophages toward a proinflammatory phenotype, as confirmed by metabolomic studies. Thus, fibroblast-released sEVs served as critical mediators of complement-induced perivascular/microenvironmental inflammation in PH.

Meta-Inflammation and Metabolic Reprogramming of Macrophages in Diabetes and Obesity: The Importance of Metabolites.

Diabetes mellitus type II and obesity are two important causes of death in modern society. They are characterized by low-grade chronic inflammation and metabolic dysfunction (meta-inflammation), which is observed in all tissues involved in energy homeostasis. A substantial body of evidence has established an important role for macrophages in these tissues during the development of diabetes mellitus type II and obesity. Macrophages can activate into specialized subsets by cues from their microenvironment to handle a variety of tasks. Many different subsets have been described and in diabetes/obesity literature two main classifications are widely used that are also defined by differential metabolic reprogramming taking place to fuel their main functions. Classically activated, pro-inflammatory macrophages (often referred to as M1) favor glycolysis, produce lactate instead of metabolizing pyruvate to acetyl-CoA, and have a tricarboxylic acid cycle that is interrupted at two points. Alternatively activated macrophages (often referred to as M2) mainly use beta-oxidation of fatty acids and oxidative phosphorylation to create energy-rich molecules such as ATP and are involved in tissue repair and downregulation of inflammation. Since diabetes type II and obesity are characterized by metabolic alterations at the organism level, these alterations may also induce changes in macrophage metabolism resulting in unique macrophage activation patterns in diabetes and obesity. This review describes the interactions between metabolic reprogramming of macrophages and conditions of metabolic dysfunction like diabetes and obesity. We also focus on different possibilities of measuring a range of metabolites intra-and extracellularly in a precise and comprehensive manner to better identify the subsets of polarized macrophages that are unique to diabetes and obesity. Advantages and disadvantages of the currently most widely used metabolite analysis approaches are highlighted. We further describe how their combined use may serve to provide a comprehensive overview of the metabolic changes that take place intracellularly during macrophage activation in conditions like diabetes and obesity.

M6A mRNA methylation-directed myeloid cell activation controls progression of NAFLD and obesity.

SUMMARYN6-methyladenosine (m6A) RNA modification is a fundamental determinant of mRNA metabolism, but its role in innate immunity-driven non-alcoholic fatty liver disease (NAFLD) and obesity is not known. Here, we show that myeloid lineage-restricted deletion of the m6A “writer” protein Methyltransferase Like 3 (METTL3) prevents age-related and diet-induced development of NAFLD and obesity in mice with improved inflammatory and metabolic phenotypes. Mechanistically, loss of METTL3 results in the differential expression of multiple mRNA transcripts marked with m6A, with a notable increase of DNA Damage Inducible Transcript 4 (DDIT4) mRNA level. In METTL3-deficient macrophages, there is a significant downregulation of mammalian target of rapamycin (mTOR) and nuclear factor κB (NF-κB) pathway activity in response to cellular stress and cytokine stimulation, which can be restored by knockdown of DDIT4. Taken together, our findings identify the contribution of METTL3-mediated m6A modification of Ddit4 mRNA to macrophage metabolic reprogramming in NAFLD and obesity.

Disrupted macrophage metabolic reprogramming in aged soleus muscle during early recovery following disuse atrophy.

Aged skeletal muscle is characterized by poor muscle recovery following disuse coinciding with an impaired muscle pro‐inflammatory macrophage response. Macrophage inflammatory status is regulated by its metabolic state, but little is understood of macrophage metabolism and its relation to macrophage inflammation in the context of muscle recovery and aging. Therefore, the purpose of this study was to thoroughly characterize macrophage metabolism and inflammation in aged muscle during early recovery following disuse atrophy using single cell transcriptomics and functional assays. Young (4–5 months) and old (20–22 months) male C57BL/6 mice underwent 14 days of hindlimb unloading followed by 4 days of ambulatory recovery. CD45+ cells were isolated from solei muscles and analyzed using 10x Genomics single cell RNA sequencing. We found that aged pro‐inflammatory macrophage clusters were characterized with an impaired inflammatory and glycolytic transcriptome, and this dysregulation was accompanied by a suppression of HIF‐1α and its immediate downstream target, Glut1. As a follow‐up, bone marrow‐derived macrophages were isolated from a separate cohort of young and old mice at 4‐d recovery and were polarized to a pro‐inflammatory phenotype and used for glycolysis stress test, phagocytosis activity assay, and targeted GC‐MS metabolomics. Aged bone marrow‐derived pro‐inflammatory macrophages were characterized with impaired glycolysis and phagocytosis function, decreased succinate and an accumulation of glycolytic metabolic intermediates overall supporting reduced glycolytic flux and macrophage function. Our results indicate that the metabolic reprograming and function of aged skeletal muscle pro‐inflammatory macrophages are dysfunctional during early recovery from disuse atrophy possibly attributing to attenuated regrowth.

Tofacitinib therapy intercepts macrophage metabolic reprogramming instigated by SARS-CoV-2 Spike protein.

The molecular mechanism of severe acute respiratory syndrome coronavirus 2 (SARS‐CoV‐2) Spike protein was characterized to identify novel therapies. The impact of tofacitinib, IL‐6R Ab, or TNFi therapy was determined on Spike protein or LPS/IFN‐γ‐induced signaling, inflammation, and metabolic reprogramming in MΦs and/or rheumatoid arthritis (RA) fibroblast‐like synoviocyte (FLS). ACE2 frequency was markedly expanded in MΦs compared to T cells and RA FLS. Tofacitinib suppresses Spike protein potentiated STAT1 signaling, whereas this function was unchanged by TNFi. Tofacitinib impairs IL‐6/IFN/LPS‐induced STAT1 and STAT3 phosphorylation in RA MΦs and FLS. Interestingly, tofacitinib had a broader inhibitory effect on the monokines, glycolytic regulators, or oxidative metabolites compared to IL‐6R Ab and TNFi in Spike‐protein‐activated MΦs. In contrast, all three therapies disrupted IFN‐α and IFN‐β secretion in response to Spike protein; nonetheless, the IFN‐γ was only curtailed by tofacitinib or IL‐6R Ab. While tofacitinib counteracted MΦ metabolic rewiring instigated by Spike protein, it was inconsequential on the glycolysis expansion mediated via HK2 and/or LDHA in the activated RA MΦ and FLS. Nevertheless, the potentiated inflammatory response and the diminished oxidative phosphorylation modulated by Spike protein and/or LPS/IFN‐γ stimulation in MΦs or RA FLS were reversed by tofacitinib. In conclusion, tofacitinib suppresses MΦ inflammation and immunometabolism triggered by Spike protein and may provide a promising strategy for COVID‐19 patients.

Clinical significance of crown-like structures to trastuzumab response in patients with primary invasive HER2+ breast cancer.

e12533 Background: Obesity is associated with breast cancer development and worse survival. Obesity can initiate, promote, and maintain systemic inflammation via metabolic reprogramming of macrophages that encircle adipocytes, termed crown-like structures (CLS). In breast cancer patients, CLS are present in 36-50% of patients and have been associated with anthropometric parameters. Here we focus on HER2+ breast cancer. The role of adiposity in HER2+ breast cancer is conflicting which may be attributed to the tumour heterogeneity. Adiposity has also been shown to affect the local immune environment of solid tumours. However, the prognostic significance of CLS in HER2+ breast cancer is still unknown. Methods: We investigated the prognostic significance of CLS in a cohort of 219 patients with primary HER2+ breast cancer who were diagnosed between 1982 to 2012 in Southampton General Hospital. This cohort includes 76 HER2+ trastuzumab naïve patients and 143 HER2+ patients treated with adjuvant trastuzumab. We stained FFPE tumour samples for the expression of CD68, CD16 and CD32B on CLS and correlated these to clinical outcomes. CLS were defined as CLS within distant adipose tissue, CLS within the adipose-tumour border (B-CLS) and intratumoural CLS. CLS were quantified manually in full face sections by two independent scorers and descriptive and Cox regression analysis was carried out. Results: A total of 201 tumours were suitable for CLS analyses. The median follow-up was 34.74 months (range, 0.43-299.08). In the trastuzumab naive cohort, B-CLS≤1 and B-CLS &gt; 1 were present in 37 (52.11%) and 34 (47.89%), respectively. In the trastuzumab treated cohort, B-CLS≤1 were identified in 69 (53.08%) and B-CLS &gt; 1 were found in 61 (46.92%) of the tumours. CLS were more commonly found in the adipose-tumour border (60.89%) rather than in the distant adipose tissue (36.14%) or intratumorally (14.36%). The presence of any CLS was significantly associated with BMI≥25 kg/m2 (p = 0.018). There was strong evidence of association between CD68+CD32B+ B-CLS and BMI≥25 kg/m2 (p = 0.007). Co-expression of CD16 and CD32B by B-CLS was more frequent in patients with BMI≥25 kg/m2 (p = 0.036). Survival analysis showed shorter time to metastatic disease in patients with CD68+ B-CLS &gt; 1 (p = 0.011) in the trastuzumab treated cohort. Subgroup analysis revealed that in the BMI≥25 kg/m2 group, patients with CD68+ B-CLS &gt; 1 had shorter time to metastatic disease compared to patients with B-CLS≤1 (p = 0.004). Multivariate cox regression showed that B-CLS &gt; 1 is an independent prognostic factor for shorter time to metastatic disease in patients with primary HER2+ breast cancer that received adjuvant trastuzumab (HR 6.81, 95%CI (1.38-33.54), p = 0.018). Conclusions: B-CLS can be potentially used as a predictive biomarker to optimize the stratification and personalisation of treatment in HER2-overexpressed breast cancer patients.

STING regulates metabolic reprogramming in macrophages via HIF-1α during Brucella infection

Macrophages metabolic reprogramming in response to microbial insults is a major determinant of pathogen growth or containment. Here, we reveal a distinct mechanism by which stimulator of interferon genes (STING), a cytosolic sensor that regulates innate immune responses, contributes to an inflammatory M1-like macrophage profile upon Brucella abortus infection. This metabolic reprogramming is induced by STING-dependent stabilization of hypoxia-inducible factor-1 alpha (HIF-1α), a global regulator of cellular metabolism and innate immune cell functions. HIF-1α stabilization reduces oxidative phosphorylation and increases glycolysis during infection with B. abortus and, likewise, enhances nitric oxide production, inflammasome activation and IL-1β release in infected macrophages. Furthermore, the induction of this inflammatory profile participates in the control of bacterial replication since absence of HIF-1α renders mice more susceptible to B. abortus infection. Mechanistically, activation of STING by B. abortus infection drives the production of mitochondrial reactive oxygen species (mROS) that ultimately influences HIF-1α stabilization. Moreover, STING increases the intracellular succinate concentration in infected macrophages, and succinate pretreatment induces HIF-1α stabilization and IL-1β release independently of its cognate receptor GPR91. Collectively, these data demonstrate a pivotal mechanism in the immunometabolic regulation of macrophages during B. abortus infection that is orchestrated by STING via HIF-1α pathway and highlight the metabolic reprogramming of macrophages as a potential treatment strategy for bacterial infections.

Macrophage miR-210 induction and metabolic reprogramming in response to pathogen interaction boost life-threatening inflammation.

Unbalanced immune responses to pathogens can be life-threatening although the underlying regulatory mechanisms remain unknown. Here, we show a hypoxia-inducible factor 1α-dependent microRNA (miR)-210 up-regulation in monocytes and macrophages upon pathogen interaction. MiR-210 knockout in the hematopoietic lineage or in monocytes/macrophages mitigated the symptoms of endotoxemia, bacteremia, sepsis, and parasitosis, limiting the cytokine storm, organ damage/dysfunction, pathogen spreading, and lethality. Similarly, pharmacologic miR-210 inhibition improved the survival of septic mice. Mechanistically, miR-210 induction in activated macrophages supported a switch toward a proinflammatory state by lessening mitochondria respiration in favor of glycolysis, partly achieved by downmodulating the iron-sulfur cluster assembly enzyme ISCU. In humans, augmented miR-210 levels in circulating monocytes correlated with the incidence of sepsis, while serum levels of monocyte/macrophage-derived miR-210 were associated with sepsis mortality. Together, our data identify miR-210 as a fine-tuning regulator of macrophage metabolism and inflammatory responses, suggesting miR-210-based therapeutic and diagnostic strategies.

Metabolic reprogramming of macrophages and its involvement in inflammatory diseases.

Macrophages are critical effector cells of the innate immune system. The presence of microbes or the stimulation by inflammatory factors triggers the metabolic reprogramming of macrophages or macrophage polarization into two phenotypes: the classically activated macrophages (M1) displaying a pro-inflammatory phenotype and the alternatively activated macrophages (M2) having anti-inflammatory functions. The imbalance between the two phenotypes has been linked with various pathological states, such as fibrosis, hepatitis, colitis, and tumor progression. An avenue of potential therapeutic strategies based on macrophage polarization has emerged. Therefore, it is essential to understand the mechanisms of macrophage polarization. In this review, we focus on the macrophage polarization process and discuss the stimuli-dependent conversion into M1 and M2 phenotypes. We also present the metabolic patterns supporting their specific functions. The factors and signaling cascades involved in intra-class switching are also detailed. Finally, the role of macrophage polarization in disease progression is discussed.

Host succinate is an activation signal for Salmonella virulence during intracellular infection.

Key to the success of intracellular pathogens is the ability to sense and respond to a changing host cell environment. Macrophages exposed to microbial products undergo metabolic changes that drive inflammatory responses. However, the role of macrophage metabolic reprogramming in bacterial adaptation to the intracellular environment has not been explored. Here, using metabolic profiling and dual RNA sequencing, we show that succinate accumulation in macrophages is sensed by intracellular Salmonella Typhimurium (S. Tm) to promote antimicrobial resistance and type III secretion. S Tm lacking the succinate uptake transporter DcuB displays impaired survival in macrophages and in mice. Thus, S Tm co-opts the metabolic reprogramming of infected macrophages as a signal that induces its own virulence and survival, providing an additional perspective on metabolic host-pathogen cross-talk.