A Monocyte-Orchestrated IFN-I-to-IL-4 Cytokine Axis Instigates Protumoral Macrophages and Thwarts Poly(I:C) Therapy

IL-6/ERK signaling pathway participates in type I IFN-programmed, unconventional M2-like macrophage polarization

Type I interferons (IFN-Is) have been harnessed for cancer therapies due to their immunostimulatory functions. However, certain tumor-tolerating activities by IFN-Is also exist, and may potentially thwart their therapeutic effects. In this respect, our previous studies have demonstrated a monocyte-orchestrated, IFN-I-to-IL-4 cytokine axis, which can subsequently drive M2-skewed pro-tumoral polarization of macrophages. Whether other IFN-dependent signals may also contribute to such an unconventional circumstance of M2-like macrophage skewing remain unexplored. Herein, we first unveil IL-6 as another ligand that participates in IFN-dependent induction of a typical M2 marker (ARG1) in transitional monocytes. Indeed, IL-6 significantly promotes IL-4-dependent induction of a major group of prominent M2 markers in mouse bone marrow-derived macrophages (BMDMs) and human peripheral blood-derived macrophages, while it alone does not engage marked increases of these markers. Such a pattern of regulation is confirmed globally by RNAseq analyses in BMDMs, which in turn suggests an association of IL-6-amplified subset of M2 genes with the ERK1/2 signaling pathway. Interestingly, pharmacological experiments establish the role of SHP2-ERK cascade in mediating IL-6's enhancement effect on these M2 targets. Similar approaches also validate the involvement of IL-6/ERK signaling in promoting the IFN-dependent, unconventional M2-skewing phenotype in transitional monocytes. Furthermore, an inhibitor of ERK signaling cooperates with an IFN-I inducer to enable a greater antitumor effect, which correlates with suppression of treatment-elicited ARG1. The present work establishes a role of IL-6/ERK signaling in promoting M2-like macrophage polarization, and suggests this axis as a potential therapeutic target for combination with IFN-I-based cancer treatments.

Precise tumor immune rewiring via synthetic CRISPRa circuits gated by concurrent gain/loss of transcription factors

Reinvigoration of antitumor immunity has recently become the central theme for the development of cancer therapies. Nevertheless, the precise delivery of immunotherapeutic activities to the tumors remains challenging. Here, we explore a synthetic gene circuit-based strategy for specific tumor identification, and for subsequently engaging immune activation. By design, these circuits are assembled from two interactive modules, i.e., an oncogenic TF-driven CRISPRa effector, and a corresponding p53-inducible off-switch (NOT gate), which jointly execute an AND-NOT logic for accurate tumor targeting. In particular, two forms of the NOT gate are developed, via the use of an inhibitory sgRNA or an anti-CRISPR protein, with the second form showing a superior performance in gating CRISPRa by p53 loss. Functionally, the optimized AND-NOT logic circuit can empower a highly specific and effective tumor recognition/immune rewiring axis, leading to therapeutic effects in vivo. Taken together, our work presents an adaptable strategy for the development of precisely delivered immunotherapy.

“Reinvigoration of antitumor immunity has recently become the central theme for the development of cancer therapies. Here the authors present an adaptable gene circuit to harness the CRISPRa for tumorlocalized immune activation.”

NLRP4 negatively regulates type I interferon response and influences the outcome in anti-PD-1/PD-L1 therapy

The challenge to improve the clinical efficacy and enlarge the population that benefits from immune checkpoint inhibitors (ICIs) for non‐small‐cell lung cancer (NSCLC) is significant. Based on whole‐exosome sequencing analysis of biopsies from NSCLC patients before anti‐programmed cell death protein‐2 (PD‐1) treatment, we identified NLRP4 mutations in the responders with a longer progression‐free survival (PFS). Knockdown of NLRP4 in mouse Lewis lung cancer cell line enhanced interferon (IFN)‐α/β production through the cGAS‐STING‐IRF3/IRF7 axis and promoted the accumulation of intratumoral CD8⁺ T cells, leading to tumor growth retardation in vivo and a synergistic effect with anti‐PD‐ligand 1 therapy. This was consistent with clinical observations that more tumor‐infiltrating CD8⁺ T cells and elevated peripheral IFN‐α before receiving nivolumab treatment were associated with a longer PFS in NSCLC patients. Our study highlights the roles of tumor‐intrinsic NLRP4 in remodeling the immune contextures in the tumor microenvironment, making regional type I IFN beneficial for ICI treatment.