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Anti-PD-1 therapy redirects macrophages from an M2 to an M1 phenotype inducing regression of OS lung metastases.

ABSTRACT: Osteosarcoma (OS) pulmonary metastasis translates into poor patient survival. The implication of PD-1-PD-L1 pathway in the context of NK cells and/or macrophages in OS is unknown. We investigated the effect of anti-PD-1 in OS lung metastasis and the role of NK cells and/or macrophages in anti-PD-1 responses. A human LM7 OS mouse model was used. Immunohistochemistry for tissues (PD-L1, caspase-3, Ki-67, NK cells, macrophages), and Western blotting for OS lung tumors (p-Stat3, p-Erk1/2) was performed. NK and macrophages were assessed using flow cytometry. NK cell and macrophage depletion were conducted using anti-asialo GM1 and clodrosome, respectively. PD-L1 expression was observed in human OS cells and OS patient lung metastases. Anti-PD1 antibody led to a significant decrease in the number of OS lung metastases, enhanced tumor apoptosis, decreased tumor cell proliferation, and p-STAT-3/p-Erk1/2 signaling blockade in OS lung tumors. NK cells and macrophages in OS lung tumors expressed PD-1 and anti-PD1 increased NK cell and macrophage tumor infiltration. Increased numbers of antitumor M1 macrophages and decreased pro-inflammatory M2 macrophages were seen. NK depletion did not affect therapeutic effect of anti-PD-1, suggesting that NK cells were not directly involved. However, macrophage depletion significantly compromised anti-PD1 efficacy, confirming their role in efficacy of anti-PD-1 against OS lung metastasis. Our findings suggest that OS lung metastases regression by anti-PD1 can be attributed to activated tumor M1 macrophages and reduced M2 macrophages. Owing to the co-relation of M1 macrophages with OS patient outcome, we provide a novel mechanism of PD-1 blockade and a basis for future clinical trials for anti-PD-1 antibodies in OS.

SUBMITTER: Dhupkar P

PROVIDER: S-EPMC6010882 | biostudies-other | 2018 Jun

REPOSITORIES: biostudies-other

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Anti-PD-1 therapy redirects macrophages from an M2 to an M1 phenotype inducing regression of OS lung metastases.

Dhupkar Pooja P Gordon Nancy N Stewart John J Kleinerman Eugenie S ES

Cancer medicine 20180507 6

Osteosarcoma (OS) pulmonary metastasis translates into poor patient survival. The implication of PD-1-PD-L1 pathway in the context of NK cells and/or macrophages in OS is unknown. We investigated the effect of anti-PD-1 in OS lung metastasis and the role of NK cells and/or macrophages in anti-PD-1 responses. A human LM7 OS mouse model was used. Immunohistochemistry for tissues (PD-L1, caspase-3, Ki-67, NK cells, macrophages), and Western blotting for OS lung tumors (p-Stat3, p-Erk1/2) was perfor ...[more]

PMID: 29733528

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Project description:BackgroundToll-like receptors (TLRs) and macrophages play an important role in rheumatoid arthritis (RA). Currently, it is not clear whether inflammatory M1 or anti-inflammatory M2 predominate among the resident macrophages in the synovium. In the present study, we set out to investigate the impact of TLR stimulation on monocyte-derived M1 and M2 macrophage function and phenotype by mimicking the exposure to abundant TLR agonists as occurs in the context of RA. The response of macrophage subsets to TLR2 and TLR4 activation was evaluated on cluster of differentiation (CD) marker profile; cytokine secretion; gene expression; and NF-?B, interferon regulatory factors 3 and 7 (IRF3/7), and mitogen-activated protein kinase (MAPK) activation.MethodsHuman monocytes were isolated from peripheral blood of healthy individuals and patients with RA and differentiated into M1-like and M2-like macrophages by granulocyte-macrophage colony-stimulating factor (GM-CSF) and macrophage colony-stimulating factor (M-CSF), respectively. Cells were either (1) stimulated with TLR ligands Pam3 or lipopolysaccharide (LPS) or (2) classically activated via interferon (IFN)-?/LPS. Cytokine production was measured by enzyme-linked immunosorbent assay, and gene expression was measured by qPCR. Cells were stained for CD markers and analyzed by fluorescence-activated cell sorting. NF-?B, IRF3/7, and MAPKs were detected by Western blotting.ResultsMonocyte-derived macrophages of healthy donors (HD) or patients with RA displayed comparable subset-specific phenotypes upon exposure to TLR agonists. CD14 and CD163 marker expression on M2 macrophages did not change upon TLR2 and TLR4 engagement. By contrast, M2 gene markers HMOX1, FOLR2, and SLC40A1 were decreased. Importantly, M2 macrophages derived from HD or patients with RA showed both a decreased ratio of interleukin (IL)-10/IL-6 and IL-10/IL-8 upon stimulation with TLR2 ligand Pam3 compared with TLR4 ligand LPS. Gene expression of TLR2 was increased, whereas TLR4 expression was decreased, by TLR ligand stimulation. MAPKs p38, extracellular signal-regulated kinase 1/2, and c-Jun N-terminal kinase were activated more strongly in M2 than in M1 macrophages by Pam3 or LPS.ConclusionsWe show that the anti-inflammatory activity of M2 macrophages is reduced in the presence of abundant TLR2 ligands without significant changes in cell surface markers. Thus, the classical M1/M2 paradigm based on cellular markers does not apply to macrophage functions in inflammatory conditions such as RA.

Project description:BackgroundAlpha-momorcharin (α-MMC) is a natural medicine derived from bitter melon and has been found to exert immunomodulatory effects. Our previous study indicated that α-MMC can regulate cytokine release from monocytes, but it remains unknown about its regulatory effect on different types of cytokines, such as inflammatory cytokines or anti-inflammatory cytokines.MethodsLPS-induced M1-type macrophages model and IL-4-induced M2-type macrophages model were established, and the expression of proinflammatory cytokines and anti-inflammatory cytokines were assessed by ELISA after α-MMC was administered. Then, a LPS-induced acute pneumonia mouse model was established, the proinflammatory cytokines levels and inflammatory lesions in lung tissues were examined by ELISA or H&E staining. Furthermore, omics screening analysis and Western blotting verification were performed on TLR4 and JAK1-STAT6 signalling pathway-related proteins to elucidate the regulatory mechanism of α-MMC in those M1 macrophages and M2 macrophages.ResultsAt a noncytotoxic dose of 0.3 μg/mL, α-MMC significantly inhibited the LPS-induced expression of inflammatory cytokines, such as TNF-α, IL-1β, IL-6, IL-8, MIP-1α and MCP-1, by M1 macrophages in a time-dependent manner, but α-MMC did not inhibit the IL-4-induced synthesis of anti-inflammatory cytokines, such as IL-10, IL-1RA, EGF, VEGF, TGF-β and CCL22, by M2 macrophages. Moreover, α-MMC also inhibited inflammatory cytokine expression in an LPS-induced acute pneumonia mouse model and alleviated inflammation in lung tissues. Furthermore, omics screening and Western blotting analysis confirmed that α-MMC inhibited TAK1/p-TAK1 and subsequently blocked the downstream MAPK and NF-κB pathways, thus inhibiting the LPS-induced inflammatory cytokine expression.ConclusionOur results reveal that α-MMC inhibits proinflammatory cytokine expression by M1 macrophages but not anti-inflammatory cytokine expression by M2 macrophages. The efficacy of α-MMC in selectively inhibiting proinflammatory cytokine expression renders it particularly suitable for the treatment of severe inflammation and autoimmune diseases characterized by cytokine storms.

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Anti-PD-1 therapy redirects macrophages from an M2 to an M1 phenotype inducing regression of OS lung metastases.

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Anti-PD-1 therapy redirects macrophages from an M2 to an M1 phenotype inducing regression of OS lung metastases.

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