PD-L2+ wound zone macrophage-like cells display M1/M2-mixed activation and restrain the effector Th1 responses

Loss of LXN promotes macrophage M2 polarization and PD-L2 expression contributing cancer immune-escape in mice

Latexin (LXN) plays an important role in tumorigenesis and inflammatory response and as a tumor suppressor in many tumors. However, whether LXN regulates tumorigenesis through immune regulation remains uncertain. Here, we demonstrate that LXN deficiency increases hematopoietic stem cells, as well as affects the proportion of immune cells in the peripheral system. Animal studies show that mice loss of LXN promotes tumor growth in subcutaneous tumor model and AOM/DSS-induced colorectal cancer model. We found that loss of LXN promotes macrophage M2 polarization and PD-L2 expression in macrophage, thus, inhibits the function of T cells. Adoptive transfer of wild-type macrophage rescues the function of T cells in LXN-deficient mice. LXN deficiency in hematopoietic lineage exacerbates colorectal carcinogenesis, and targeted inhibition of PD-L2 ameliorates cancer growth in LXN-deficient mice. Mechanistically, we demonstrate that LXN inhibits STAT3 transcriptional activity by targeting inhibition of JAK1 in macrophages. LXN deficiency enhances PD-L2 expression rather than PD-L1 in macrophages, which lead to inhibition of T cells in tumor microenvironment. Collectively, we define a critical role of LXN/JAK1/STAT3 signal in macrophage and highlights the potential role of LXN in tumor immune-escape by regulating macrophage polarization, as well as the expression of immune checkpoint PD-L2.

Gene-selective transcription promotes the inhibition of tissue reparative macrophages by TNF

Pro-inflammatory TNF is a highly gene-selective inhibitor of the gene expression program of tissue repair and wound healing macrophages.

Anti-TNF therapies are a core anti-inflammatory approach for chronic diseases such as rheumatoid arthritis and Crohn’s Disease. Previously, we and others found that TNF blocks the emergence and function of alternative-activated or M2 macrophages involved in wound healing and tissue-reparative functions. Conceivably, anti-TNF drugs could mediate their protective effects in part by an altered balance of macrophage activity. To understand the mechanistic basis of how TNF regulates tissue-reparative macrophages, we used RNAseq, scRNAseq, ATACseq, time-resolved phospho-proteomics, gene-specific approaches, metabolic analysis, and signaling pathway deconvolution. We found that TNF controls tissue-reparative macrophage gene expression in a highly gene-specific way, dependent on JNK signaling via the type 1 TNF receptor on specific populations of alternative-activated macrophages. We further determined that JNK signaling has a profound and broad effect on activated macrophage gene expression. Our findings suggest that TNF’s anti-M2 effects evolved to specifically modulate components of tissue and reparative M2 macrophages and TNF is therefore a context-specific modulator of M2 macrophages rather than a pan-M2 inhibitor.

Parameters of Tumor Microenvironment Determine Effectiveness of Anti-PD-1/PD-L1 Therapy

Undoubtedly, one of the most promising approaches to the treatment of cancer is creation of the pathogenetically based therapeutic drugs. Researchers from all over the world are trying to answer the question on how to select a target that would be effective and, in general, they are quite successful at that. The Nobel Prize-winning discovery of mechanisms for regulating activity of the immune system cells through checkpoint molecules, as well as discovery of the ability of tumor cells to use these mechanisms to suppress immune responses was an impetus for the development of modern immunotherapy, and now such inhibitors of the immune checkpoints as PD-1/PD-L1 are included in the routine chemotherapy. Use of such drugs can prolong the patient's life, but, unfortunately, not cure the disease. This is partially due to heterogeneity of tumor cells and microenvironment, but the main reasons may be in the complex relationships between the tumor and microenvironment, which, at times, are so plastic that they can change, adjusting to newly emerging conditions. Main characteristic of the tumor microenvironment is the type of the ongoing immune-inflammatory response (IIR), and since inhibitors of the immune checkpoints act on the cells involved in IIR, it is obvious that the outcomes of cancer therapy, including outcomes of hyperprogressive disease, can be associated with this parameter. The presented review reveals the essence of interactions between the tumor and its microenvironment during therapy with PD-L1 inhibitors.

α1-Acid Glycoprotein Enhances the Immunosuppressive and Protumor Functions of Tumor-Associated Macrophages

Blood levels of acute-phase protein α₁-acid glycoprotein (AGP, orosmucoid) increase in patients with cancer. Although AGP is produced from hepatocytes following stimulation by immune cell-derived cytokines under conditions of inflammation and tumorigenesis, the functions of AGP in tumorigenesis and tumor progression remain unknown. In the present study, we revealed that AGP contributes directly to tumor development by induction of programmed death ligand 1 (PD-L1) expression and IL6 production in macrophages. Stimulation of AGP induced PD-L1 expression in both human monocyte-derived macrophages through STAT1 activation, whereas AGP had no direct effect on PD-L1 expression in tumor cells. AGP also induced IL6 production from macrophages, which stimulated proliferation in tumor cells by IL6R-mediated activation of STAT3. Furthermore, administration of AGP to AGP KO mice phenocopied effects of tumor-associated macrophages (TAM) on tumor progression. AGP decreased IFNγ secretion from T cells and enhanced STAT3 activation in subcutaneous tumor tissues. In addition, AGP regulated PD-L1 expression and IL6 production in macrophages by binding with CD14, a coreceptor for Toll-like receptor 4 (TLR4), and inducing TLR4 signaling. These results provide the first evidence that AGP is directly involved in tumorigenesis by interacting with TAMs and that AGP might be a target molecule for anticancer therapy. SIGNIFICANCE: AGP-mediated suppression of antitumor immunity contributes to tumor progression by inducing PD-L1 expression and IL6 production in TAMs.

Estrogen/ER in anti-tumor immunity regulation to tumor cell and tumor microenvironment

As the essential sexual hormone, estrogen and its receptor has been proved to participate in the regulation of autoimmunity diseases and anti-tumor immunity. The adjustment of tumor immunity is related to the interaction between cancer cells, immune cells and tumor microenvironment, all of which is considered as the potential target in estrogen-induced immune system regulation. However, the specific mechanism of estrogen-induced immunity is poorly understood. Typically, estrogen causes the nuclear localization of estrogen/estrogen receptor complex and alternates the transcription pattern of target genes, leading to the reprogramming of tumor cells and differentiation of immune cells. However, the estrogen-induced non-canonical signal pathway activation is also crucial to the rapid function of estrogen, such as NF-κB, MAPK-ERK, and β-catenin pathway activation, which has not been totally illuminated. So, the investigation of estrogen modulatory mechanisms in these two manners is vital for the tumor immunity and can provide the potential for endocrine hormone targeted cancer immunotherapy. Here, this review summarized the estrogen-induced canonical and non-canonical signal transduction pathway and aimed to focus on the relationship among estrogen and cancer immunity as well as immune-related tumor microenvironment regulation. Results from these preclinical researches elucidated that the estrogen-target therapy has the application prospect of cancer immunotherapy, which requires the further translational research of these treatment strategies.

Treatment with a DC-SIGN ligand reduces macrophage polarization and diastolic dysfunction in the aging female but not male mouse hearts

Cardiac diastolic dysfunction in aging arises from increased ventricular stiffness caused by inflammation and interstitial fibrosis. The diastolic dysfunction contributes to heart failure with preserved ejection fraction (HFpEF), which in the aging population is more common in women. This report examines its progression over 12 weeks in aging C57BL/6J mice and correlates its development with changes in macrophage polarization and collagen deposition.

Aged C57BL/6J mice were injected with dendritic cell–specific intercellular adhesion molecule-3-grabbing nonintegrin (DC-SIGN) ligand 1 (DCSL1, an anti-inflammatory agent) or saline for 12 weeks. Echo and Doppler measurements were performed before and after 4 and 12 weeks of treatment. DCSL1 prevented the worsening of diastolic dysfunction over time in females but not in males. Cardiac single cell suspensions analyzed by flow cytometry revealed changes in the inflammatory infiltrate: (1) in males, there was an increased total number of leukocytes with an increased pro-inflammatory profile compared with females and they did not respond to DCSL1; (2) by contrast, DCSL1 treatment resulted in a shift in macrophage polarization to an anti-inflammatory phenotype in females. Notably, DCSL1 preferentially targeted tumor necrosis factor-α (TNFα⁺) pro-inflammatory macrophages. The reduction in pro-inflammatory macrophage polarization was accompanied by a decrease in collagen content in the heart.

Age-associated diastolic dysfunction in mice is more severe in females and is associated with unique changes in macrophage polarization in cardiac tissue. Treatment with DCSL1 mitigates the changes in inflammation, cardiac function, and fibrosis. The characteristics of diastolic dysfunction in aging female mice mimic similar changes in aging women.