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Enhancing arginase 2 expression using target site blockers as a strategy to modulate macrophage phenotype.

ABSTRACT: Macrophages are plastic cells playing a crucial role in innate immunity. While fundamental in responding to infections, when persistently maintained in a pro-inflammatory state they can initiate and sustain inflammatory diseases. Therefore, a strategy that reprograms pro-inflammatory macrophages toward an anti-inflammatory phenotype could hold therapeutic potential in that context. We have recently shown that arginase 2 (Arg2), a mitochondrial enzyme involved in arginine metabolism, promotes the resolution of inflammation in macrophages and it is targeted by miR-155. Here, we designed and tested a target site blocker (TSB) that specifically interferes and blocks the interaction between miR-155 and Arg2 mRNA, leading to Arg2 increased expression and activity. In bone marrow-derived macrophages transfected with Arg2 TSB (in the presence or absence of the pro-inflammatory stimulus LPS), we observed an overall shift of the polarization status of macrophages toward an anti-inflammatory phenotype, as shown by significant changes in surface markers (CD80 and CD71), metabolic parameters (mitochondrial oxidative phosphorylation) and cytokines secretion (IL-1β, IL-6, and TNF). Moreover, in an in vivo model of LPS-induced acute inflammation, intraperitoneal administration of Arg2 TSB led to an overall decrease in systemic levels of pro-inflammatory cytokines. Overall, this proof-of-concept strategy represent a promising approach to modulating macrophage phenotype.

SUBMITTER: De Santi C

PROVIDER: S-EPMC9424864 | biostudies-literature | 2022 Sep

REPOSITORIES: biostudies-literature

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Enhancing arginase 2 expression using target site blockers as a strategy to modulate macrophage phenotype.

De Santi Chiara C Nally Frances K FK Afzal Remsha R Duffy Conor P CP Fitzsimons Stephen S Annett Stephanie L SL Robson Tracy T Dowling Jennifer K JK Cryan Sally-Ann SA McCoy Claire E CE

Molecular therapy. Nucleic acids 20220804

Macrophages are plastic cells playing a crucial role in innate immunity. While fundamental in responding to infections, when persistently maintained in a pro-inflammatory state they can initiate and sustain inflammatory diseases. Therefore, a strategy that reprograms pro-inflammatory macrophages toward an anti-inflammatory phenotype could hold therapeutic potential in that context. We have recently shown that arginase 2 (Arg2), a mitochondrial enzyme involved in arginine metabolism, promotes the ...[more]

PMID: 36090747

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Project description:A favourable immunotherapeutic strategy in the treatment of chronic inflammatory disease, is to dampen the pro-inflammatory macrophage response and upregulate the anti-inflammatory macrophage response. Previous studies have shown that Arginase-2 (Arg2), a mitochondrial enzyme, is a key regulator of the macrophage anti-inflammatory response with an essential role in IL-10 signalling. Here we show that IL-10 in the presence of LPS increased Arg2 expression in human macrophages and peripheral blood mononuclear cells. Target site blockers (TSBs) (locked nucleic acid antisense oligonucleotides) specifically designed to target the 3’ UTR of Arg2 messenger RNA were used to inhibit binding of specific microRNAs thus enhancing Arg2 expression. Eleven Arg2-TSBs were screened and the TSB targeting miR-155 (TSB-155) and the TSB targeting miR-3202 (TSB-3202) were found to increase Arg2 expression in human macrophages resulting in decreased gene expression and cytokine production of TNF-α and CCL2. In addition, following TSB-3202 stimulation, there were statistically significant increases in the ‘M2-like’ macrophage marker, CD206; and CD16, associated with an IL-10 response, and a decrease in the ‘M1-like’ macrophage marker, HLA-DR, indicating a shift in the macrophage phenotype. Proteomic analysis demonstrated that multiple pro-inflammatory responsive proteins including Signal Transducer and Activator of Transcription 1 (STAT-1), Toll-like receptors, Signalling Lymphocytic Activation Molecule F7 (SLAMF7) and Interferon Induced Protein with Tetratricopeptide Repeats 3 (IFIT3), were downregulated by TSB-155 and TSB-3202 while Sequestomsome-1 (SQSTM1) was increased after treatment. In silico analysis of significantly dysregulated proteins predicted that TSB-3202 supressed several upstream pro-inflammatory regulators including STAT-1 and Interferon α2 (IFNA2) while enhancing anti-inflammatory associated interleukin 1 receptor antagonist (IL1RN) and STAT-3. Proteomic data was validated by confirming increased levels of SQSTM1, decreased levels of phosphoylated-STAT-1 and STAT-1, and downregulation of Ifit3 and Slamf7 by TSB treatment. In conclusion, upregulation of Arg2 protein by TSBs inhibits several pro-inflammatory signalling proteins resulting in reduced pro-inflammatory cytokine secretion, reduced ‘M1-like’ marker expression and enhanced ‘M2-like’ macrophage marker expression. Arg2 is a promising novel therapeutic target to modulate inflammatory signalling in macrophages.

Project description:BackgroundArginase-1 (Arg1) expressing tumor-associated macrophages (TAMs) may create an immune-suppressive tumor microenvironment (TME), which is a significant challenge for cancer immunotherapy. We previously reported the existence of Arg1-specific memory T cells among peripheral blood mononuclear cells (PBMCs) and described that Arg-1-based immune modulatory vaccines (IMVs) control tumor growth and alter the M1/M2 macrophage ratio in murine models of cancer. In the present study, we investigated how Arg1-specific T cells can directly target TAMs and influence their polarization.MethodsMurine Arg1-specific CD4+T cells isolated from splenocytes of animals vaccinated with an Arg1-derived peptide in the adjuvant montanide were co-cultured with either in vitro M2-differentiated bone marrow-derived macrophages or ex vivo isolated F4/80+TAMs. Human Arg1-specific CD4+T cell clones were co-cultured with Arg1-expressing TAMs generated in vitro from either PBMC-derived CD14+cells or the myeloid cell lines MonoMac1 and THP-1. MHC class II-restricted Arg-1 peptide presentation by macrophages was confirmed by immunopeptidomics. T-cell-mediated changes in the macrophage immune phenotype and cytokine microenvironment were examined using flow cytometry, RT-qPCR and multiplex immunoassay. The effect of Arg1-derived peptide IMV on TAMs in vivo was assessed by multiplex gene analysis of F4/80+cells.ResultsWe show that Arg1-based IMV-mediated tumor control was linked to a decrease in multiple immunosuppressive pathways in the TAM population of the treated animals. Tumor-conditioned media (TCM) derived from Arg1-vaccinated mice induced significantly higher upregulation of MHC-II on exposed myeloid cells compared with controls. Furthermore, murine CD4+Arg1-specific T cells were able to target TAMs and effectively reprogram their phenotype ex vivo by secreting IL2 and IFNγ. Next, we established that human Arg1+TAMs present Arg1-derived peptides and are directly recognized by proinflammatory CD4+Arg1-specific T cell clones. These CD4+Arg1-specific T cells were able to reprogram TCM-conditioned macrophages as observed by increased expression of CD80 and HLA-DR.ConclusionsTAMs may be directly targeted and modulated by Arg1-specific CD4+T cells. These findings provide a strong rationale for future clinical development of Arg1-based IMVs to alter the immune-suppressive TME by reprogramming TAMs and promoting a proinflammatory TME.

Project description:Extracellular vesicles (EVs) mediate cell-to-cell communication by horizontally transferring biological materials from host cells to target cells. During exposure to pathogens, pathogen-associated molecular patterns (e.g., lipopolysaccharide, LPS) get in contact with endothelial cells and stimulate the secretion of endothelial cell-derived EVs (E-EVs). The triggered EVs secretion is known to have a modulating influence on the EVs-receiving cells. Macrophages, a major component of innate immunity, are polarized upon receiving external inflammatory stimuli, in which toll-like receptor4 (TLR4)-nuclear factor kappa B (NFκB) pathway plays a key role. However, the functions of LPS-induced E-EVs (ELPS-EVs) in modulating macrophage phenotype and activation remain elusive. We collected the EVs from quiescent endothelial cells (ENor-EVs) and ELPS-EVs to detect their stimulatory role on NR8383 macrophages. Isolated EVs were characterized by transmission electron microscopy (TEM), western blot assay, and nanoparticle tracking analysis (NTA). NR8383 macrophages were stimulated with ELPS-EVs, ENor-EVs, or PBS for 24 h. Hereafter, the uptake of EVs by the macrophages was investigated. Upon EVs stimulation, cellular viability was determined by MTT assay, while macrophage phenotype was analyzed by flow cytometry and immunofluorescence analysis. Furthermore, a western blot assay was conducted to evaluate the potentially involved TLR4-NFκB pathway. Interestingly, upon exposure to LPS, endothelial cells secreted significantly higher amounts of EVs (i.e., ELPS-EVs) when compared to quiescent cells or cells in PBS. The ELPS-EVs were also better internalized by NR8383 macrophages than ENor-EVs. The cellular viability of ELPS-EVs-treated macrophages was 1.2 times higher than those in the ENor-EVs and PBS groups. In addition, ELPS-EVs modulated NR8383 macrophages towards a proinflammatory macrophage M1-like phenotype. This was indicated by the significantly upregulated expressions of proinflammatory macrophage biomarkers CD86 and inducible nitric oxide synthase (iNOS) observed in ELPS-EVs-treated macrophages. The TLR4-NFκB signaling pathway was substantially activated in ELPS-EVs-treated macrophages, indicated by the elevated expressions of makers TLR4 and phosphorylated form of nuclear factor kappa B p65 subunit (p-NFκBp65). Overall, our results indicate that E-EVs play a crucial role in macrophage phenotype modulation under inflammatory conditions.

Dataset Information

Enhancing arginase 2 expression using target site blockers as a strategy to modulate macrophage phenotype.

Publications

Enhancing arginase 2 expression using target site blockers as a strategy to modulate macrophage phenotype.

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