Differential expression of complement receptors CR1/2 and CR4 by murine M1 and M2 macrophages

Cationic liposomes encapsulating IL-2 selectively induce apoptosis and significantly reduce the secretion of cytokines on M1-murine polarized macrophages

Inflammatory diseases pose a global challenge due to the critical role of macrophages in their pathogenesis. This study evaluated the effects of cationic liposomes encapsulating IL-2 (LIP-IL-2) on murine peritoneal macrophages (MP) polarized towards M1 and M2 phenotypes. M1 MP (CD86+), which overexpressed IL-2Rα and CD14 receptors, underwent apoptosis following LIP-IL-2 treatment, whereas M2 MP (CD206+) were unaffected. Furthermore, LIP-IL-2 significantly reduced the secretion of pro-inflammatory cytokines, including IL-6, TNF-α, IFN-γ, and IL-12, exclusively in M1 macrophages. These findings suggest that LIP-IL-2 could serve as a promising therapeutic tool for chronic inflammatory diseases by selectively inducing apoptosis in pro-inflammatory M1 macrophages without affecting M2 ones, opening avenues for targeted therapies in diseases where chronic macrophage-mediated inflammation is a key factor.

Excessive MYC Orchestrates Macrophages induced Chromatin Remodeling to Sustain Micropapillary-Patterned Malignancy in Lung Adenocarcinoma

Current understanding of micropapillary (MP)-subtype lung adenocarcinoma (LUAD) remains confined to biological activities and genomic landscapes. Unraveling the major regulatory programs underlying MP patterned malignancy offers opportunities to identify more feasible therapeutic targets for patients with MP LUAD. This study shows that patients with MP subtype LUAD have aberrant activation of the MYC pathway compared to patients with other subtypes. In vitro and xenograft mouse model studies reveal that MP pattern in malignancy cannot be solely due to aberrant MYC expression but requires the involvement of M2-like macrophages. Excessively expressed MYC leads to the accumulation of M2-like macrophages from the bone marrow, which secretes TGFβ, to induce the expression of FOSL2 in tumor cells, thereby remodeling chromatin accessibility at promoter regions of MP-pattern genes to promote the MYC-mediated de novo transcriptional regulation of these genes. Additionally, the MP-pattern in malignancy can be effectively alleviated by disrupting the TGFβ-FOSL2 axis. These findings reveal new functions for the M2-like macrophage-TGFβ-FOSL2 axis in MYC-overexpressing MP-subtype LUAD, identifying targetable vulnerabilities in this pathway.

Serotonin receptor 5-HT7 modulates inflammatory-associated functions of macrophages

The hormone and neurotransmitter serotonin regulates numerous physiological functions within the central nervous system and in the periphery upon binding to specific receptors. In the periphery, the serotonin receptor 7 (5-HT7R) is expressed on different immune cells including monocytes and macrophages. To investigate the impact of 5-HT7R-mediated signaling on macrophage properties, we used human THP-1 cells and differentiated them into pro-inflammatory M1- and anti-inflammatory M2-like macrophages. Pharmacological 5-HT7R activation with the specific agonist LP-211 especially modulates morphology of M1-like macrophages by increasing the number of rounded cells. Furthermore, 5-HT7R stimulation results in significantly reduced phagocytic and migratory ability of M1-like macrophages. Noteworthy, LP-211 treatment leads to changes in secretory properties of all macrophage types with the highest effects obtained for M0- and M2c-like macrophages. Finally, the importance of 5-HT7R for regulation of phagocytosis was confirmed in human primary CD14+ cells. These results indicate that 5-HT7R activation selectively impairs basic functions of macrophages and might thus be a new access point for the modulation of macrophage responses in the future treatment of inflammatory diseases.

Proteomic profiling of oleamide-mediated polarization in a primary human monocyte-derived tumor-associated macrophages (TAMs) model: a functional analysis

BACKGROUND

Tumor-associated macrophages (TAMs) play a critical function in the development of tumors and are associated with protumor M2 phenotypes. Shifting TAMs towards antitumor M1 phenotypes holds promise for tumor immunotherapy. Oleamide, a primary fatty acid amide, has emerged as a potent anticancer and immunomodulatory compound. However, the regulatory effects of oleamide on TAM phenotypes remain unclear.

METHODS

We used real-time quantitative reverse transcription polymerase chain reaction (qRT-PCR) and enzyme-linked immunosorbent assay (ELISA) techniques to study the influence of oleamide on primary human monocyte-derived TAM phenotypes, and we investigated the protein expression profiles based on mass spectrometry to analyze the effect of oleamide on macrophage polarization. Moreover, the advantageous binding scores between oleamide and these target candidate proteins are examined using molecular docking.

RESULTS

Our study revealed that oleamide effectively suppressed the M2-like TAM phenotype by reducing interleukin (IL)-10 production and downregulating M2-like markers, including vascular endothelial growth factor A (VEGFA), MYC proto-oncogene, bHLH transcription factor (c-Myc), and mannose receptor C-type 1 (CD206). Moreover, the conditioned medium derived from oleamide-treated TAMs induces apoptosis of MDA-MB-231 breast cancer cells. Proteomic analysis identified 20 candidate up- and down-regulation proteins targeted by oleamide, showing modulation activity associated with the promotion of the M1-like phenotype. Furthermore, molecular docking demonstrated favorable binding scores between oleamide and these candidate proteins. Collectively, our findings suggest that oleamide exerts a potent antitumor effect by promoting the antitumor M1-like TAM phenotype. These novel insights provide valuable resources for further investigations into oleamide and macrophage polarization which inhibit the progression of breast cancer, which may provide insight into immunotherapeutic approaches for cancer.

Targeting conserved TIM3+VISTA+ tumor-associated macrophages overcomes resistance to cancer immunotherapy

Despite the success of immunotherapy, overcoming immunoresistance in cancer remains challenging. We identified a unique niche of tumor-associated macrophages (TAMs), coexpressing T cell immunoglobulin and mucin domain-containing 3 (TIM3) and V-domain immunoglobulin suppressor of T cell activation (VISTA), that dominated human and mouse tumors resistant to most of the currently used immunotherapies. TIM3+VISTA+ TAMs were sustained by IL-4-enriching tumors with low (neo)antigenic and T cell-depleted features. TIM3+VISTA+ TAMs showed an anti-inflammatory and protumorigenic phenotype coupled with inability to sense type I interferon (IFN). This was established with cancer cells succumbing to immunogenic cell death (ICD). Dying cancer cells not only triggered autocrine type I IFNs but also exposed HMGB1/VISTA that engaged TIM3/VISTA on TAMs to suppress paracrine IFN-responses. Accordingly, TIM3/VISTA blockade synergized with paclitaxel, an ICD-inducing chemotherapy, to repolarize TIM3+VISTA+ TAMs to proinflammatory TAMs that killed cancer cells via tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) signaling. We propose targeting TIM3+VISTA+ TAMs to overcome immunoresistant tumors.

Identification of diagnostic signatures for ischemic stroke by machine learning algorithm

OBJECTIVE

Ischemic stroke (IS) is one of the major diseases threatening human health and survival and a leading cause of acquired mortality and disability in adults. The aim of this study was to screen diagnostic features of IS and to explore the characteristics of immune cell infiltration in IS pathogenesis.

METHODS

The microarray data of IS (GSE16561, GSE58294, GSE37587, and GSE124026) in the GEO database were merged after removing the batch effect. Then integrated bioinformatic analysis and machine-learning strategies were adopted to analyze the functional correlation and select diagnostic signatures. The WGCNA was used to identify the co-expression modules related to IS. The CIBERSORT algorithm was performed to assess the inflammatory state of IS and to investigate the correlation between diagnostic signatures and infiltrating immune cells.

RESULTS

Functional analysis of dysregulated genes showed that immune response-regulating signaling pathway and pattern recognition receptor activity were enriched in the pathophysiology of IS. The turquoise module was identified as the significant module with IS. By using Lasso and SVM-RFE learning methods, we finally obtained four diagnostic genes, including LAMP2, CR1, CLEC4E, and F5. The corresponding results of AUC of ROC prediction model in training and validation cohort were 0.954 and 0.862, respectively. The immune cell infiltration analysis suggested that plasma cells, resting and activated NK cells, activated dendritic cells, memory B cells, CD8+ T cells, naïve CD4+ T cells, and resting mast cells may be involved in the development of IS. Additionally, these diagnostic signatures might be correlated with multiple immune cells in varying degrees.

CONCLUSION

We identified four biologically relevant genes (LAMP2, CR1, CLEC4E, and F5) with diagnostic effects for IS, our results further provide novel insights regarding molecular mechanisms associated with various immune cells that related to IS for future investigations.

Efficient complement-mediated clearance of immunosuppressed T cells by macrophages

Cancer is one of the leading causes of death worldwide. Treatment outcome is largely dictated by the tumor type, disease stage, and treatment success rates, but also by the variation among patients in endogenous anti-tumor responses. Studies indicate that the presence of neutrophils in the tumor microenvironment is associated with a worse patient outcome due to their ability to suppress local anti-tumor T cell activity. Our previous studies investigated the mechanisms by which neutrophils suppress and damage T cells to become smaller in size (small T cells), debilitating their effector activities. Several studies indicate a role for tumor-associated macrophages in scavenging damaged or dead cells. We hypothesized that the observed lack of small T cells in the TME by confocal microscopy is due to immediate uptake by macrophages. In this study, we confirmed that indeed only the smaller, damaged T cells are taken up by macrophages, once serum-opsonized. Damaged T cells opsonized with complement factor C3 fragments were phagocytosed by macrophages, resulting in almost instantaneous and highly efficient uptake of these small T cells. Inhibition of the complement receptors CR1, CR3 and CR4 expressed by macrophages completely blocked phagocytosis. By contrast, actively proliferating T cells (large T cells) were neither impaired in neutrophil-MDSC activity nor opsonized for phagocytosis by macrophages. Rapid removal of damaged T cells suggests a role of complement and macrophages within the tumor microenvironment to clear suppressed T cells in cancer patients.