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Activation of a collaborative innate-adaptive immune response suppresses metastatic breast and ovarian cancer in mice

ABSTRACT: Many cancers recruit monocytes/macrophages and polarize them into tumor-associated macrophages (TAMs). TAMs promote tumor growth and metastasis and inhibit cytotoxic T cells, preventing immune control of the cancer. However, macrophages polarized by lipopolysaccharide (a bacteria-derived toll-like receptor 4 [TLR4] agonist) and interferon gamma (IFNγ) instead kill cancer cells. They do so via nitric oxide (NO), generated by inducible NO synthase (iNOS). Altering the polarization of macrophages might therefore be a strategy for controlling tumors. Here, we show that monophosphoryl lipid A (MPLA, a TLR4 agonist used as a vaccine adjuvant)- and IFNγ-activated human macrophages from metastatic breast cancers to kill the same patients’ cancer cells in vitro. Excitingly, intratumoral injection of MPLA with IFNγ not only controlled local tumor growth but also led to reduced metastasis in mouse models of metastatic luminal and triple negative breast cancers. Furthermore, intraperitoneal administration of MPLA and IFNγ reprogrammed peritoneal macrophages and suppressed metastasis in ID8-p53-/- ovarian tumor-bearing mice. We found that the combination of MPLA and IFNγ reprogrammed the immunosuppressive microenvironment to be immunostimulatory by recruiting leukocytes, stimulating type I interferon signaling, reprogramming tumor-associated (CD206+) macrophages to tumoricidal (iNOS+) macrophages, and activating cytotoxic T cells through macrophage-secreted IL12 and TNFα. Both macrophages and T cells, including memory T cells (CD44+CD62L-), were critical for the anti-metastatic effects of MPLA and IFNγ. MPLA and IFNγ are used individually in humans, so our strategy to engage the anti-tumor immune response, which requires no knowledge of unique tumor antigens, may be ready for near-future clinical testing.

ORGANISM(S): Mus musculus

PROVIDER: GSE146211 | GEO | 2020/09/01

REPOSITORIES: GEO

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Project description:Interferon (IFN)γ and interleukin (IL)-4 are central regulators of T helper 1 (Th1) and T helper 2 (Th2) immune responses, respectively. Both cytokines have a major impact on macrophage phenotypes: IFNγ–priming and subsequent TLR4 activation induces so called classically activated macrophages that are characterized by pronounced pro-inflammatory responses, whereas IL-4–treated macrophages, commonly called alternatively activated, are known to develop enhanced capacity for endocytosis, antigen presentation, and tissue repair and are generally considered anti-inflammatory. Considering IL-4 as priming rather than activating stimulus, we now compared the TLR4–dependent global gene activation program in IFNγ– versus IL-4–pretreated mouse macrophages, which has rarely been studied so far. Although both cytokines frequently induced opposing effects on gene transcription, the subsequent activation of bone marrow-derived macrophages by lipopolysaccharide (LPS) produced a strong, priming dependent pro-inflammatory response in both macrophage types. For example, the production of key pro-inflammatory cytokines IL-6 and IL-12 was significantly higher in IL-4– versus IFNγ–primed macrophages and several cytokine genes, including Il19, Ccl17, Ccl22, Ccl24 and Cxcl5, were preferentially induced in alternatively primed and LPS activated mouse macrophages. In a subset of genes, including IL12a, IFNγ priming was actually found to suppress LPS–induced gene expression in a Stat1–dependent manner. Our data suggest that IL-4–priming is not per se anti-inflammatory but generates a macrophage that is “tissue protective” but still capable of mounting a strong inflammatory response after TLR4–dependent activation. Keywords: Gene expression profiling Gene expression was investigated in mouse bone marrow-derived macrophages (BMM). On day 7, BMM were stimulated with either IL-4 or IFNγ overnight (18h in total). LPS treatment was performed in primed and unprimed macrophages 4 h prior to harvesting. At least three independent experiments were performed for each condition.

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Activation of a collaborative innate-adaptive immune response suppresses metastatic breast and ovarian cancer in mice

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