Function of Macrophages in Disease: Current Understanding on Molecular Mechanisms

Development of Itaconate Polymers Microparticles for Intracellular Regulation of Pro-Inflammatory Macrophage Activation

Itaconate (IA) is an endogenous metabolite and a potent regulator of the innate immune system. It's use in immunomodulatory therapies has faced limitations due to challenges in controlled delivery and requirements of high extracellular concentrations for internalization of the highly polar small molecule to achieve its intracellular therapeutic activity. Microparticle (MP)-based delivery strategies are a promising approach for intracellular delivery of small molecule metabolites through macrophage phagocytosis and subsequent intracellular polymer degradation-based delivery. Toward the goal of intracellular delivery of IA, degradable polyester polymer- (poly(dodecyl itaconate)) based IA polymer microparticles (IA-MPs) are generated using an emulsion method, forming micron-scale (≈1.5 µm) degradable microspheres. IA-MPs are characterized with respect to their material properties and IA release kinetics to inform particle fabrication. Treatment of murine bone marrow-derived macrophages with an optimized particle concentration of 0.1 mg million-1 cells enables phagocytosis-mediated internalization and low levels of cytotoxicity. Flow cytometry demonstrates IA-MP-specific regulation of IA-sensitive inflammatory targets. Metabolic analyses demonstrate that IA-MP internalization inhibits oxidative metabolism and induced glycolytic reliance, consistent with the established mechanism of IA-associated inhibition of succinate dehydrogenase. This development of IA-based polymer microparticles provides a basis for additional innovative metabolite-based microparticle drug delivery systems for the treatment of inflammatory disease.

PTEN inhibits scavenger receptor-mediated phagocytosis of methicillin-resistant Staphylococcus aureus

Phagocytosis requires the coordination of various classes of receptors and the activation of multiple signaling programs, culminating in actin cytoskeletal rearrangement and ingestion. Given the pleiotropic nature of the events necessary for proper microbial ingestion, identifying molecules that control distinct steps of phagocytosis could reveal potential strategies to enhance microbial clearance. PTEN is a lipid/protein phosphatase traditionally recognized as a tumor suppressor. While PTEN inhibits various arms of the innate immune response, its role during Staphylococcus aureus infection remains unclear. We hypothesize that PTEN inhibits the functions of scavenger receptors (SRs) and the actin cytoskeleton during methicillin-resistant S. aureus (MRSA) infection in macrophages. RNAseq analysis of PTEN KO immortalized bone marrow-derived macrophages (iBMDMs) unveiled increased expression of genes involved in actin polymerization, pathogen recognition, and SRs, which leads to enhanced MRSA phagocytosis in both iBMDMs and primary peritoneal macrophages lacking PTEN. PTEN is physically associated with 2 SRs, MARCO and CD36, and blocking these receptors prevents the increased phagocytosis seen in PTEN KO macrophages. PTEN binds to the actin depolymerizing factor cofilin-1 during infection, inhibiting F-actin (the essential form of actin for phagocytosis) while increasing G-actin pools. Cytometry by time of flight (CyTOF) analysis of human myeloid cell populations from a PTEN-haploinsufficient patient suggests that PTEN is necessary for generating specific monocyte and dendritic subclasses. This study identifies the role of PTEN in macrophage phagocytosis of a gram-positive pathogen and in the development of monocyte subsets. This highlights the spectrum of PTEN importance in host defense mechanisms in both murine and human phagocytes.

Macrophage Polarization in Lung Diseases: From Mechanisms to Therapeutic Strategies

Macrophages are pivotal immune cells involved in maintaining immune homeostasis and defending against pathogens. They exhibit significant plasticity and heterogeneity, enabling polarization into pro-inflammatory M1 or anti-inflammatory M2 phenotypes in response to distinct microenvironmental cues. The process of macrophage polarization is tightly regulated by complex signaling pathways and transcriptional networks. This review explores the factors influencing macrophage polarization, the associated signaling pathways, and their roles in the pathogenesis of lung diseases, including fibrosis, cancer, and chronic inflammatory conditions. By summarizing recent advances, we aim to provide insights into the immunoregulatory functions of macrophages and their therapeutic potential. Based on our review, it is believed that targeting macrophage polarization emerges as a promising approach for developing effective treatments for lung diseases, balancing inflammation and repair while mitigating disease progression.

Macrophage-derived lncRNAs in cancer: regulators of tumor progression and therapeutic targets

Macrophages are key tumor microenvironment (TME) regulators, exhibiting remarkable plasticity that enables them to either suppress or promote cancer progression. Emerging evidence highlights the critical role of macrophage-derived long non-coding RNAs (lncRNAs) in shaping tumor immunity, influencing macrophage polarization, immune evasion, angiogenesis, metastasis, and therapy resistance. This review comprehensively elucidates the functional roles of M1- and M2-associated lncRNAs, detailing their molecular mechanisms and impact on cancer pathogenesis. In summary, elucidating the roles of lncRNAs derived from macrophages in cancer progression offers new avenues for therapeutic strategies, significantly improving patient outcomes in the fight against the disease. Further research into the functional significance of these lncRNAs and the development of targeted therapies is essential to harness their potential fully in clinical applications. We further explore their potential as biomarkers for cancer prognosis and therapeutic targets for modulating macrophage activity to enhance anti-cancer immunity. Targeting macrophage-derived lncRNAs represents a promising avenue for precision oncology, offering novel strategies to reshape the TME and improve cancer treatment outcomes.

Development of itaconate polymer microparticles for intracellular regulation of pro-inflammatory macrophage activation

Itaconate (IA) is an endogenous metabolite and a potent regulator of the innate immune system. Its use in immunomodulatory therapies has faced limitations due to inherent challenges in achieving controlled delivery and requirements for high extracellular concentrations to achieve internalization of the highly polar small molecule to achieve its intracellular therapeutic activity. Microparticle (MP)-based delivery strategies are a promising approach for intracellular delivery of small molecule metabolites through macrophage phagocytosis and subsequent intracellular polymer degradation-based delivery. Toward the goal of intracellular delivery of IA, degradable polyester polymer-(poly(itaconate-co-dodecanediol)) based IA polymer microparticles (IA-MPs) were generated using an emulsion method, forming micron-scale (∼ 1.5 µm) degradable microspheres. IA-MPs were characterized with respect to their material properties and IA release kinetics to inform particle fabrication. Treatment of murine bone marrow-derived macrophages with an optimized particle concentration of 0.1 mg/million cells enabled phagocytosis-mediated internalization and low levels of cytotoxicity. Flow cytometry demonstrated IA-MP-specific regulation of IA-sensitive inflammatory targets. Metabolic analyses demonstrated that IA-MP internalization inhibited oxidative metabolism and induced glycolytic reliance, consistent with the established mechanism of IA-associated inhibition of succinate dehydrogenase. This development of IA-based polymer microparticles provides a basis for additional innovative metabolite-based microparticle drug delivery systems for the treatment of inflammatory disease.

The role of fibroblast in chronic rhinosinusitis with nasal polyps: a key player in the inflammatory process

INTRODUCTION

Fibroblasts are the primary supporting cells in connective tissue and have long been thought to contribute to chronic rhinosinusitis with nasal polyps (CRSwNP) by producing extracellular matrix (ECM), leading to fibrosis and tissue remodeling. However, recent studies have highlighted the critical role of nasal polyp-derived fibroblasts (NPDFs) in triggering and intensifying the inflammatory response in CRSwNP.

AREAS COVERED

This review undertook a comprehensive literature search across the PubMed database, Web of Science since 2000, offering an in-depth summary of the pivotal role of NPDFs in tissue remodeling and inflammatory responses in CRSwNP. Additionally, single-cell RNA sequencing data provides a deeper exploration of the heterogeneity and functional mechanisms of fibroblasts in CRSwNP. Consequently, these insights point to fibroblasts as promising therapeutic targets for effectively treating CRSwNP.

EXPERT OPINION

Current data underscore the essential role of fibroblasts in the pathogenesis of CRSwNP. Fully elucidating the specific mechanisms by which fibroblasts contribute to the disease process is crucial for developing targeted therapies. Furthermore, advancements in single-cell RNA sequencing pave the way for selectively targeting and depleting pathological fibroblast subpopulations. Despite these advancements, the clinical development of fibroblast-targeted therapies in CRSwNP remains challenging.

Silica-induced ROS in alveolar macrophages and its role on the formation of pulmonary fibrosis via polarizing macrophages into M2 phenotype: a review

Alveolar macrophages (AMs), the first line against the invasion of foreign invaders, play a predominant role in the pathogenesis of silicosis. Studies have shown that inhaled silica dust is recognized and engulfed by AMs, resulting in the production of large amounts of silica-induced reactive oxygen species (ROS), including particle-derived ROS and macrophage-derived ROS. These ROS change the microenvironment of the AMs where the macrophage phenotype is stimulated to swift from M0 to M1 and/or M2, and ultimately emerge as the M2 phenotype to trigger silicosis. This is a complex process accompanied by various molecular biological events. Unfortunately, the detailed processes and mechanisms have not been systematically described. In this review, we first systematically introduce the process of ROS induced by silica in AMs. Then, describe the role and molecular mechanism of M2-type macrophage polarization caused by silica-induced ROS. Finally, we review the mechanism of pulmonary fibrosis induced by M2 polarized AMs. We conclude that silica-induced ROS initiate the fibrotic process of silicosis by inducing macrophage into M2 phenotype, and that targeted intervention of silica-induced ROS in AMs can reprogram the macrophage polarization and ameliorate the pathogenesis of silicosis.

The physiological role of macrophages in reproductive organs

Background

Macrophages are essential immune cells critical to reproductive physiology. They regulate key processes such as follicular development, ovulation, and luteinization in the ovaries. Macrophages are also involved in endometrial remodeling, immune tolerance, and placentation in the uterus.

Methods

This review examined the biological characteristics of macrophages and their role in ovarian, uterine, and fallopian tube physiology. It focused on findings from both animal and human studies to provide a comprehensive understanding of macrophage functions.

Main Findings

In the ovaries, M1 macrophages play a role in folliculogenesis and ovulation through the inflammatory and angiogenic pathways. Macrophages also maintain the corpus luteum and vascular integrity. In the uterus, macrophages regulate tissue repair and remodeling during the menstrual cycle and play a critical role in implantation by maintaining immune tolerance and supporting decidualization. Dysregulation of the M1/M2 balance can cause implantation failure. In the fallopian tubes, macrophages mediate tissue repair and immune responses. Macrophage polarization dynamically adapts to physiological and pathological conditions in all reproductive organs highlighting the functional plasticity of these cells.

Conclusion

Macrophage polarization and functions are pivotal in maintaining reproductive health. Hence, understanding the role of macrophages in various reproductive organs provides a foundation for developing new therapies.

Sex-specific transcriptomic effects of low-dose inorganic arsenic exposure on bone marrow-derived macrophages

Both tissue-resident macrophages and monocytes recruited from the bone marrow that transform into tissue-resident cells play critical roles in mediating homeostasis as well as in the pathology of inflammatory diseases. Inorganic arsenic (iAs) is the most common drinking water contaminant worldwide and represents a major public health concern. There are numerous diseases caused by iAs exposure in which macrophages are involved, including cardiovascular disease, cancer, and increased risk of (respiratory) infectious diseases. Notably, prenatal iAs exposure is also associated with negative birth outcomes and developmental immunotoxicity (DIT) contributing to long-term adverse outcomes of these immune-related diseases. Therefore, understanding the effects of iAs exposure on macrophages, particularly during immune development or tissue injury and inflammation, can help us better grasp the full range of arsenic immunotoxicity and better design therapeutic targets for iAs-induced diseases particularly in exposed populations. In contrast to prior published studies which often only focused on the effect of iAs on mature macrophages after development, in this study, we analyzed the transcriptome of M0-, M1- and M2-polarized male and female murine bone marrow-derived macrophages (BMDMs) which were exposed to iAs during the differentiation phase, as a model to study iAs (developmental) immunotoxicity. We identified differentially expressed genes by iAs in a sex- and stimulation-dependent manner and used bioinformatics tools to predict protein-protein interactions, transcriptional regulatory networks, and associated biological processes. Overall, our data suggest that M1-stimulated, especially female-derived, BMDMs are most susceptible to iAs exposure during differentiation. Most notably, we observed significant downregulation of major proinflammatory transcription factors, like IRF8, and its downstream targets, as well as genes encoding proteins involved in pattern recognition and antigen presentation, such as TLR7, TLR8, and H2-D1, potentially providing causal insight regarding the role of (early-life) arsenic exposure in perturbing immune responses to infectious diseases. We also observed significant downregulation of genes involved in processes crucial to coordinating a proinflammatory response including leukocyte migration, differentiation, and cytokine and chemokine production and response. Finally, we discovered that 24 X-linked genes were dysregulated in iAs-exposed female stimulation groups compared to only 3 across the iAs-exposed male stimulation groups. These findings elucidate the potential mechanisms underlying the sex-differential iAs-associated immune-related disease risk.

Sirt3-Mediated Opa1 Deacetylation Protects Against Sepsis-Induced Acute Lung Injury by Inhibiting Alveolar Macrophage Pro-Inflammatory Polarization

Aims: Mitochondrial dynamics in alveolar macrophages (AMs) are associated with sepsis-induced acute lung injury (ALI). In this study, we aimed to investigate whether changes in mitochondrial dynamics could alter the polarization of AMs in sepsis-induced ALI and to explore the regulatory mechanism of mitochondrial dynamics by focusing on sirtuin (SIRT)3-induced optic atrophy protein 1 (OPA1) deacetylation. Results: The AMs of sepsis-induced ALI showed imbalanced mitochondrial dynamics and polarization to the M1 macrophage phenotype. In sepsis, SIRT3 overexpression promotes mitochondrial dynamic equilibrium in AMs. However, 3-(1H-1, 2, 3-triazol-4-yl) pyridine (3TYP)-specific inhibition of SIRT3 increased the mitochondrial dynamic imbalance and pro-inflammatory polarization of AMs and further aggravated sepsis-induced ALI. OPA1 is directly bound to and deacetylated by SIRT3 in AMs. In AMs of sepsis-induced ALI, SIRT3 protein expression was decreased and OPA1 acetylation was increased. OPA1 acetylation at the lysine 792 amino acid residue (OPA1-K792) promotes self-cleavage and is associated with an imbalance in mitochondrial dynamics. However, decreased acetylation of OPA1-K792 reversed the pro-inflammatory polarization of AMs and protected the barrier function of alveolar epithelial cells in sepsis-induced ALI. Innovation: Our study revealed, for the first time, the regulation of mitochondrial dynamics and AM polarization by SIRT3-mediated deacetylation of OPA1 in sepsis-induced ALI, which may serve as an intervention target for precision therapy of the disease. Conclusions: Our data suggest that imbalanced mitochondrial dynamics promote pro-inflammatory polarization of AMs in sepsis-induced ALI and that deacetylation of OPA1 mediated by SIRT3 improves mitochondrial dynamic equilibrium, thereby ameliorating lung injury. Antioxid. Redox Signal. 41, 1014-1030.

Development of molecular sensors based on fluorescent proteins for polarized macrophages identification

Macrophages are a type of white blood cells that play key roles in innate immune responses as a part of cellular immunity for host defence and tissue homeostasis. To perform diverse functions, macrophages show high plasticity by transforming to polarized states. They are mainly identified as unpolarized, pro-inflammatory and antiinflammatory states and termed as M0, M1 and M2 macrophages respectively. Discriminating polarized states is important due to strict implication with inflammatory conditions resulting in many diseases as chronic inflammation, neurodegeneration, and cancer etc. Many polarization protein markers have been identified and applied to investigate expression profiles through PCR and other techniques with antibodies. However, they are time and cost consuming and sometimes show insufficient performances. We focused on the mannose receptor (CD206) as representative marker of M2 macrophage recognising terminal mannose. We developed dose dependent mannosylated fluorescent proteins (FPs) by conjugations with mannose derivative for around 20 modifiable sites on FPs surfaces. Maximum modifications did not spoil various features of FPs. We found further sensitive and specific discriminations among M2, M1 and M0 macrophages after treating polarized macrophages with adequately conditioned FPs compared to already established approaches using anti CD206 antibody through flow cytometric analysis. These results might be derived from direct ligand utilizations and increased avidity due to multivalent bindings with abundantly modified multimeric FPs. Our strategy is simple but addresses disadvantages of preceding methods. Moreover, this strategy is applicable to detect other cell surface receptors as FPs can be modified with ligands or recognizable aptamer like molecules.

Sentinels of neuroinflammation: the crucial role of myeloid cells in the pathogenesis of gliomas and neurodegenerative diseases

The inflammatory processes that drive pathologies of the central nervous system (CNS) are complex and involve significant contributions from the immune system, particularly myeloid cells. Understanding the shared and distinct pathways of myeloid cell regulation in different CNS diseases may offer critical insights into therapeutic development. This review aims to elucidate the mechanisms underlying myeloid cell dysfunction and neuroinflammation in two groups of neurological pathologies with significant social impact and a limited efficacy of their treatments: the most common primary brain tumors -gliomas-, and the most prevalent neurodegenerative disorders -Alzheimer's and Parkinson's disease. Despite their distinct clinical manifestations, these diseases share key pathological features, including chronic inflammation and immune dysregulation. The role of myeloid cells in neuroinflammation has garnered special interest in recent years in both groups, as evidenced by the growing focus on therapeutic research centred on myeloid cells. By examining the cellular and molecular dynamics that govern these conditions, we hope to identify common and unique therapeutic targets that can inform the development of more effective treatments. Recent advances in single-cell technologies have revolutionized our understanding of myeloid cell heterogeneity, revealing diverse phenotypes and molecular profiles across different disease stages and microenvironments. Here, we present a comprehensive analysis of myeloid cell involvement in gliomas, Alzheimer's and Parkinson's disease, with a focus on phenotypic acquisition, molecular alterations, and therapeutic strategies targeting myeloid cells. This integrated approach not only addresses the limitations of current treatments but also suggests new avenues for therapeutic intervention, aimed at modulating the immune landscape to improve patient outcomes.

Single-cell RNA sequencing analysis identifies acute changes in the tumor microenvironment induced by interferon α gene therapy in a murine bladder cancer model

Introduction

Nadofaragene firadenovec (Ad-IFNα/Syn3) is now approved for BCG-unresponsive bladder cancer (BLCA). IFNα is a pleiotropic cytokine that causes direct tumor cell killing via TRAIL-mediated apoptosis, angiogenesis inhibition, and activation of the innate and adaptive immune system. We established an immunocompetent murine BLCA model to study the effects of murine adenoviral IFNα (muAd-Ifnα) gene therapy on cancer cells and the tumor microenvironment using a novel murine equivalent of Nadofaragene firadenovec (muAd-Ifnα).

Methods

Tumors were induced by instilling MB49 cells into the bladders of mice; luciferase imaging confirmed tumor development. Mice were treated with adenovirus control (Ad-Ctrl; empty vector), or muAd-Ifnα (3x1011 VP/mL), and survival analysis was performed. For single-cell sequencing (scRNAseq) analysis (72h), bladders were harvested and treated with collagenase/hyaluronidase and TrypLE for cell dissociation. Single cells were suspended in PBS/1% FBS buffer; viability was assessed with Vicell cell counter. scRNAseq analysis was performed using 10X genomics 3' sequencing. Raw RNAseq data were pre-processed using Cell Ranger single-cell software. Seurat (R package) was used to normalize and cluster the scRNA data. Pooled differential gene expression analysis in specific cell clusters was performed with DESeq2.

Results

We identified 16 cell clusters based on marker expression which were grouped into epithelial (tumor), uroplakin-enriched, endothelial, T-cells, neutrophils, and macrophage clusters. Top differentially expressed genes between muAd-Ifnα and Ad-Ctrl were identified. Within the specific cell clusters, IPA analysis revealed significant differences between muAd-Ifnα and control. IFNα signaling and hypercytokinemia/chemokinemia were upregulated in all clusters. Cell death pathways were upregulated in tumor and endothelial clusters. T-cells demonstrated upregulation of the immunogenic cell death signaling pathway and a decrease in the Th2 pathway genes. Macrophages showed upregulation of PD1/PD-L1 pathways along with downregulation of macrophage activation pathways (alternate and classical). Multiplex immunofluorescence confirmed increased infiltration with macrophages in muAd-Ifnα treated tumors compared to controls. PD1/PD-L1 expression was reduced at 72h.

Discussion

This single-cell analysis builds upon our understanding of the impact of Ad-IFNα on tumor cells and other compartments of the microenvironment. These data will help identify mechanisms to improve patient selection and therapeutic efficacy of Nadofaragene firadenovec.

Shear Stress Induces a Time-Dependent Inflammatory Response in Human Monocyte-Derived Macrophages

Macrophages are innate immune cells that are known for their extreme plasticity, enabling diverse phenotypes that lie on a continuum. In a simplified model, they switch between pro-inflammatory (M1) and anti-inflammatory (M2) phenotypes depending on surrounding microenvironmental cues, which have been implicated in disease outcomes. Although considerable research has been focused on macrophage response to biochemical cues and mechanical signals, there is a scarcity of knowledge surrounding their behavior in response to shear stress. In this study, we applied varying magnitudes of shear stress on human monocyte-derived macrophages (MDMs) using a cone-and-plate viscometer and evaluated changes in morphology, gene expression, protein expression, and cytokine secretion over time. MDMs exposed to shear stress exhibited a rounder morphology compared to statically-cultured controls. RT-qPCR results showed significant upregulation of TNF-α, and analysis of cytokine release revealed increased secretion of IL-8, IL-18, fractalkine, and other chemokines. The upregulation of pro-inflammatory factors was evident with both increasing magnitudes of shear and time. Taken together, these results indicate that prolonged shear exposure induced a pro-inflammatory phenotype in human MDMs. These findings have implications for medical technology development, such as in situ vascular graft design wherein macrophages are exposed to shear and have been shown to affect graft resorption, and in delineating disease pathophysiology, for example to further illuminate the role of macrophages in atherosclerosis where shear is directly related to disease outcome.

IL-10R inhibition reprograms tumor-associated macrophages and reverses drug resistance in multiple myeloma

Multiple myeloma (MM) is the cancer of plasma cells within the bone marrow and remains incurable. Tumor-associated macrophages (TAMs) within the tumor microenvironment often display a pro-tumor phenotype and correlate with tumor proliferation, survival, and therapy resistance. IL-10 is a key immunosuppressive cytokine that leads to recruitment and development of TAMs. In this study, we investigated the role of IL-10 in MM TAM development as well as the therapeutic application of IL-10/IL-10R/STAT3 signaling inhibition. We demonstrated that IL-10 is overexpressed in MM BM and mediates M2-like polarization of TAMs in patient BM, 3D co-cultures in vitro, and mouse models. In turn, TAMs promote MM proliferation and drug resistance, both in vitro and in vivo. Moreover, inhibition of IL-10/IL-10R/STAT3 axis using a blocking IL-10R monoclonal antibody and STAT3 protein degrader/PROTAC prevented M2 polarization of TAMs and the consequent TAM-induced proliferation of MM, and re-sensitized MM to therapy, in vitro and in vivo. Therefore, our findings suggest that inhibition of IL-10/IL-10R/STAT3 axis is a novel therapeutic strategy with monotherapy efficacy and can be further combined with current anti-MM therapy, such as immunomodulatory drugs, to overcome drug resistance. Future investigation is warranted to evaluate the potential of such therapy in MM patients.

Pancreatic Adenocarcinoma Up-Regulated Factor (PAUF) Transforms Human Monocytes into Alternative M2 Macrophages with Immunosuppressive Action

Tumor-associated macrophages (TAMs) in the tumor microenvironment (TME) promote immune evasion, cancer cell proliferation, and metastasis. Ongoing research is focused on finding ways to prevent tumor growth by inhibiting TAM polarization, which has shown a correlation with unfavorable prognosis in clinical studies. Pancreatic adenocarcinoma up-regulated factor (PAUF) is a protein secreted from pancreatic cancer (PC) and acts as a TME modulator that affects the TME by acting on not only cancer cells but also stromal cells and immune cells. Tumor cells can evade the immune system by PAUF binding to Toll-like receptor (TLR) in monocytes, as this research shows. In this study, the examination centered around the recruitment of human monocytes by PAUF and the subsequent differentiation into macrophages. In an in vitro chemotaxis assay, PAUF induced chemotactic migration of TLR2-mediated monocytes. In addition, PAUF induced differentiation of monocytes into M2 macrophages, which was verified based on expressing surface markers and cytokines and morphological analysis. The inhibition of T cell proliferation and function was observed in differentiated M2 macrophages. To conclude, these findings indicate that PAUF functions as a promoter of cancer progression by regulating the recruitment and differentiation of macrophages within TMEs, ultimately causing immunosuppression.

Role of the type 6 secretion system on apoptosis and macrophage polarization during Burkholderia pseudomallei infection

Burkholderia pseudomallei (Bpm) is the causative agent of the disease melioidosis. As a facultative intracellular pathogen, Bpm has a complex lifestyle that culminates in cell-to-cell fusion and multinucleated giant cells (MNGCs) formation. The virulence factor responsible for MNGC formation is the type 6 secretion system (T6SS), a contractile nanomachine. MNGC formation is a cell-to-cell spread strategy that allows the bacteria to avoid the extracellular immune system and our previous data highlighted cell death, apoptosis, and inflammation as pathways significantly impacted by T6SS activity. Thusly, we investigated how the T6SS influences these phenotypes within the macrophage and pulmonary models of infection. Here we report that the T6SS is responsible for exacerbating apoptotic cell death during infection in both macrophages and the lungs of infected mice. We also demonstrate that although the T6SS does not influence differential macrophage polarization, the M2 polarization observed is potentially beneficial for Bpm pathogenesis and replication. Finally, we show that the T6SS contributes to the severity of inflammatory nodule formation in the lungs, which might be potentially connected to the amount of apoptosis that is triggered by the bacteria.

The involvement and significance of M2 macrophages in neuropathic pain following spinal cord injury: a systematic review

Neuropathic pain (NeP) is a type of persistent pain initiated by diseases or injuries of the nervous system. Although the underlying pathophysiological mechanisms of NeP are poorly understood, the immune system plays a key role in this condition. M2 macrophages have a key role in tissue healing and the reduction of inflammation. This systematic study aims to provide an overview of the role and importance of M2 macrophages in NeP after spinal cord injury (SCI). A comprehensive systematic review was conducted utilizing Scopus, PubMed, Embase, and ISI Web of Science databases. Two independent reviewers conducted the article selection. All publications examine the impact of M2 macrophages on NeP following spinal cord injuries. A quality assessment was conducted on bias entities that had been predetermined. Eleven papers met the criteria. According to the findings, focusing on immune cell polarization presents viable therapeutic options for treating NeP and enhancing recovery after SCI. M2 macrophages are essential for reducing neuropathic pain and promoting recovery after spinal cord injury. The modulation of M2 macrophages by a number of therapeutic approaches, including ivermectin-functionalized MWCNTs, isorhamnetin, Neuregulin-1 administration, TMEM16F inhibition, lentivirus-mediated delivery of anti-inflammatory cytokines, epigallocatechin-3-gallate, and red-light therapy promotes neuroregeneration, decreases neuroinflammatory cytokines, and reduces NeP. The results of these preclinical investigations must, however, be interpreted with caution, according to the quality assessment and risk of bias analysis of the studies that were included. Targeting M2 macrophages may have therapeutic benefits as they are essential for the management of NeP and recovery following spinal cord damage.

Enrichment of novel CD3+F4/80+ cells in brown adipose tissue following adrenergic stimulation

Macrophages play a multifaceted role in maintaining tissue homeostasis, fighting infections, and regulating cold-induced thermogenesis. The brown adipose tissue (BAT) is crucial for maintaining body temperature during cold exposure. Cold stress triggers the sympathetic nervous system to release norepinephrine (NE), which activates BAT via β3-adrenergic receptors, initiating lipolysis and glycolysis. BAT-infiltrating macrophages can either hinder or enhance thermogenesis by controlling the interplay between BAT cells and sympathetic nerves. In this study we report on a unique population of CD3+F4/80+ dual lineage co-expressing (DE) cells within the interscapular BAT (iBAT), that increased following chronic adrenergic stimulation. In forward scatter/side scatter plots, they formed a cluster distinct from lymphocytes, appearing larger and more complex. These CD3+F4/80+ DE cells demonstrated the lack of T cell markers CD62L and TCRβ and expressed higher levels of Ly6C, F4/80, and CD11b markers compared to T cells and CD3- macrophages. Furthermore, analysis revealed two subpopulations within the CD3+F4/80+ DE population based on MHCII expression, with the proportion of MHCII-low subset increasing with adrenergic stimulation. This novel DE population within iBAT, unequivocally identified by the its unique surface marker profile, warrants further investigation into the intricate mechanisms governing adaptive thermogenesis regulation.

Immunoregulatory role of platelet derivatives in the macrophage-mediated immune response

Background

Macrophages are innate immune cells that display remarkable phenotypic heterogeneity and functional plasticity. Due to their involvement in the pathogenesis of several human conditions, macrophages are considered to be an attractive therapeutic target. In line with this, platelet derivatives have been successfully applied in many medical fields and as active participants in innate immunity, cooperation between platelets and macrophages is essential. In this context, the aim of this review is to compile the current evidence regarding the effects of platelet derivatives on the phenotype and functions of macrophages to identify the advantages and shortcomings for feasible future clinical applications.

Methods

A total of 669 articles were identified during the systematic literature search performed in PubMed and Web of Science databases.

Results

A total of 27 articles met the inclusion criteria. Based on published findings, platelet derivatives may play an important role in inducing a dynamic M1/M2 balance and promoting a timely M1-M2 shift. However, the differences in procedures regarding platelet derivatives and macrophages polarization and the occasional lack of information, makes reproducibility and comparison of results extremely challenging. Furthermore, understanding the differences between human macrophages and those derived from animal models, and taking into account the peculiarities of tissue resident macrophages and their ontogeny seem essential for the design of new therapeutic strategies.

Conclusion

Research on the combination of macrophages and platelet derivatives provides relevant information on the function and mechanisms of the immune response.

Macrophages as Targets in Hepatocellular Carcinoma Therapy

Hepatocellular carcinoma (HCC) is a malignant tumor with a complex and diverse immunosuppressive microenvironment. Tumor-associated macrophages (TAM) are an essential component of the tumor immune microenvironment. TAMs typically exist in two primary states: anti-tumor M1 macrophages and protumor M2 macrophages. Remarkably, TAMs possess high plasticity, enabling them to switch between different subtypes or alter their biological functions in response to the tumor microenvironment. Based on research into the biological role of TAMs in the occurrence and development of malignant tumors, including HCC, TAMs are emerging as promising targets for novel tumor treatment strategies. In this review, we provide a detailed introduction to the origin and subtypes of TAMs, elucidate their interactions with other cells in the complex tumor microenvironment of HCC, and describe the biological roles, characteristics, and mechanisms of TAMs in the progression of HCC. Furthermore, we furnish an overview of the latest therapeutic strategies targeting TAMs.

In Silico Prediction of NOS2, NOS3 and Arginase 1 Genes Targeting by Micro RNAs Upregulated in Systemic Sclerosis

Introduction:

Systemic sclerosis (SSc) is a chronic disorder, characterised by endothelial dysfunction and fibrosis of skin and internal organs. Endothelium dysfunction leads to a decrease in nitric oxide levels, consequent to reduced Nitric Oxide synthase 3 (NOS3) activity due to decreased NOS3 gene function. Besides endothelium, macrophages too play an important role in the pathogenesis of SSc; classically activated M1 macrophages (express NOS2) and alternatively activated M2 macrophages (express Arginase1) are differentially altered in favour of M2 macrophages. Micro-RNAs (miRNAs) regulate expression of various genes and may favour disease phenotype.

Aim:

Our aim was to identify differentially expressed micro-RNAs in SSc, which target NOS2, NOS3 and Arginase1 genes by in-silico approach.

Methods:

Data on miRNAs upregulation reported in various studies was collected and their sequence ID from miRBase was identified in FASTA format from NCBI. Binding strength of these miRNAs against NOS2, NOS3 and Arginase1 genes was evaluated by RNA22.

Results:

After scanning 39 publications reporting miRNA expression in SSc, a total of 13 miRNAs were found to be up-regulated for NOS2 (Gibbs free energy ≤18.0Kj/mol) and 15 miRNAs up-regulated for NOS3 (Gibbs free energy ≤18.0Kj/mol) whereas for Arginase1 only 2 miRNAs were up-regulated.

Conclusion:

There is differential upregulation of miRNAs in SSc. Micro RNAs targeting NOS2 and NOS3 genes are highly up-regulated in comparison to Arginase 1. Role of epigenetic regulation of genes by miRNAs may play a key role in pathogenesis of SSc.

C5aR1 inhibition reprograms tumor associated macrophages and reverses PARP inhibitor resistance in breast cancer

Although Poly (ADP-ribose) polymerase (PARP) inhibitors (PARPi) have been approved in multiple diseases, including BRCA1/2 mutant breast cancer, responses are usually transient requiring the deployment of combination therapies for optimal efficacy. Here we thus explore mechanisms underlying sensitivity and resistance to PARPi using two intrinsically PARPi sensitive (T22) and resistant (T127) syngeneic murine breast cancer models in female mice. We demonstrate that tumor associated macrophages (TAM) potentially contribute to the differential sensitivity to PARPi. By single-cell RNA-sequencing, we identify a TAM_C3 cluster, expressing genes implicated in anti-inflammatory activity, that is enriched in PARPi resistant T127 tumors and markedly decreased by PARPi in T22 tumors. Rps19/C5aR1 signaling is selectively elevated in TAM_C3. C5aR1 inhibition or transferring C5aR1hi cells increases and decreases PARPi sensitivity, respectively. High C5aR1 levels in human breast cancers are associated with poor responses to immune checkpoint blockade. Thus, targeting C5aR1 may selectively deplete pro-tumoral macrophages and engender sensitivity to PARPi and potentially other therapies.

Systematic Review of Chemical Compounds with Immunomodulatory Action Isolated from African Medicinal Plants

A robust, well-functioning immune system is the cornerstone of good health. Various factors may influence the immune system's effectiveness, potentially leading to immune system failure. This review aims to provide an overview of the structure and action of immunomodulators isolated from African medicinal plants. The research was conducted according to PRISMA guidelines. Full-text access research articles published in English up to December 2023, including plant characteristics, isolated phytochemicals, and immuno-modulatory activities, were screened. The chemical structures of the isolated compounds were generated using ChemDraw® (version 12.0.1076), and convergent and distinctive signaling pathways were highlighted. These phytochemicals with demonstrated immunostimulatory activity include alkaloids (berberine, piperine, magnoflorine), polysaccharides (pectin, glucan, acemannan, CALB-4, GMP90-1), glycosides (syringin, cordifolioside, tinocordiside, aucubin), phenolic compounds (ferulic acid, vanillic acid, eupalitin), flavonoids (curcumin, centaurein, kaempferin, luteolin, guajaverin, etc.), terpenoids (oleanolic acid, ursolic acid, betulinic acid, boswellic acids, corosolic acid, nimbidin, andrographolides). These discussed compounds exert their effects through various mechanisms, targeting the modulation of MAPKs, PI3K-Akt, and NF-kB. These mechanisms can support the traditional use of medicinal plants to treat immune-related diseases. The outcomes of this overview are to provoke structural action optimization, to orient research on particular natural chemicals for managing inflammatory, infectious diseases and cancers, or to boost vaccine immunogenicity.

Targeted Therapy for Highly Desmoplastic and Immunosuppressive Tumor Microenvironment of Pancreatic Ductal Adenocarcinoma

Pancreatic ductal adenocarcinoma (PDAC) is a highly lethal malignancy with a very poor prognosis. Despite advancements in treatment strategies, PDAC remains recalcitrant to therapies because patients are often diagnosed at an advanced stage. The advanced stage of PDAC is characterized by metastasis, which typically renders it unresectable by surgery or untreatable by chemotherapy. The tumor microenvironment (TME) of PDAC comprises highly proliferative myofibroblast-like cells and hosts the intense deposition of a extracellular matrix component that forms dense fibrous connective tissue, a process called the desmoplastic reaction. In desmoplastic TMEs, the incessant aberration of signaling pathways contributes to immunosuppression by suppressing antitumor immunity. This feature offers a protective barrier that impedes the targeted delivery of drugs. In addition, the efficacy of immunotherapy is compromised because of the immune cold TME of PDAC. Targeted therapy approaches towards stromal and immunosuppressive TMEs are challenging. In this review, we discuss cellular and non-cellular TME components that contain actionable targets for drug development. We also highlight findings from preclinical studies and provide updates about the efficacies of new investigational drugs in clinical trials.

Lipid nanoparticle encapsulated large peritoneal macrophages migrate to the lungs via the systemic circulation in a model of clodronate-mediated lung-resident macrophage depletion

Rationale: A mature tissue resident macrophage (TRM) population residing in the peritoneal cavity has been known for its unique ability to migrate to peritoneally located injured tissues and impart wound healing properties. Here, we sought to expand on this unique ability of large peritoneal macrophages (LPMs) by investigating whether these GATA6+ LPMs could also intravasate into systemic circulation and migrate to extra-peritoneally located lungs upon ablating lung-resident alveolar macrophages (AMs) by intranasally administered clodronate liposomes in mice. Methods: C12-200 cationic lipidoid-based nanoparticles were employed to selectively deliver a small interfering RNA (siRNA)-targeting CD-45 labeled with a cyanine 5.5 (Cy5.5) dye to LPMs in vivo via intraperitoneal injection. We utilized a non-invasive optical technique called Diffuse In Vivo Flow Cytometry (DiFC) to then systemically track these LPMs in real time and paired it with more conventional techniques like flow cytometry and immunocytochemistry to initially confirm uptake of C12-200 encapsulated siRNA-Cy5.5 (siRNA-Cy5.5 (C12-200)) into LPMs, and further track them from the peritoneal cavity to the lungs in a mouse model of AM depletion incited by intranasally administered clodronate liposomes. Also, we stained for LPM-specific marker zinc-finger transcription factor GATA6 in harvested cells from biofluids like broncho-alveolar lavage as well as whole blood to probe for Cy5.5-labeled LPMs in the lungs as well as in systemic circulation. Results: siRNA-Cy5.5 (C12-200) was robustly taken up by LPMs. Upon depletion of lung-resident AMs, these siRNA-Cy5.5 (C12-200) labeled LPMs rapidly migrated to the lungs via systemic circulation within 12-24 h. DiFC results showed that these LPMs intravasated from the peritoneal cavity and utilized a systemic route of migration. Moreover, immunocytochemical staining of zinc-finger transcription factor GATA6 further confirmed results from DiFC and flow cytometry, confirming the presence of siRNA-Cy5.5 (C12-200)-labeled LPMs in the peritoneum, whole blood and BALF only upon clodronate-administration. Conclusion: Our results indicate for the very first time that selective tropism, migration, and infiltration of LPMs into extra-peritoneally located lungs was dependent on clodronate-mediated AM depletion. These results further open the possibility of therapeutically utilizing LPMs as delivery vehicles to carry nanoparticle-encapsulated oligonucleotide modalities to potentially address inflammatory diseases, infectious diseases and even cancer.

Identification of PPARG as key gene to link coronary atherosclerosis disease and rheumatoid arthritis via microarray data analysis

BACKGROUND

Inflammation is the common pathogenesis of coronary atherosclerosis disease (CAD) and rheumatoid arthritis (RA). Although it is established that RA increases the risk of CAD, the underlining mechanism remained indefinite. This study seeks to explore the molecular mechanisms of RA linked CAD and identify potential target gene for early prediction of CAD in RA patients.

MATERIALS AND METHODS

The study utilized five raw datasets: GSE55235, GSE55457, GSE12021 for RA patients, and GSE42148 and GSE20680 for CAD patients. Gene Set Enrichment Analysis (GSEA) was used to investigate common signaling pathways associated with RA and CAD. Then, weighted gene co-expression network analysis (WGCNA) was performed on RA and CAD training datasets to identify gene modules related to single-sample GSEA (ssGSEA) scores. Overlapping module genes and differentially expressed genes (DEGs) were considered as co-susceptible genes for both diseases. Three hub genes were screened using a protein-protein interaction (PPI) network analysis via Cytoscape plug-ins. The signaling pathways, immune infiltration, and transcription factors associated with these hub genes were analyzed to explore the underlying mechanism connecting both diseases. Immunohistochemistry and qRT-PCR were conducted to validate the expression of the key candidate gene, PPARG, in macrophages of synovial tissue and arterial walls from RA and CAD patients.

RESULTS

The study found that Fc-gamma receptor-mediated endocytosis is a common signaling pathway for both RA and CAD. A total of 25 genes were screened by WGCNA and DEGs, which are involved in inflammation-related ligand-receptor interactions, cytoskeleton, and endocytosis signaling pathways. The principal component analysis(PCA) and support vector machine (SVM) and receiver-operator characteristic (ROC) analysis demonstrate that 25 DEGs can effectively distinguish RA and CAD groups from normal groups. Three hub genes TUBB2A, FKBP5, and PPARG were further identified by the Cytoscape software. Both FKBP5 and PPARG were downregulated in synovial tissue of RA and upregulated in the peripheral blood of CAD patients and differential mRNAexpreesion between normal and disease groups in both diseases were validated by qRT-PCR.Association of PPARG with monocyte was demonstrated across both training and validation datasets in CAD. PPARG expression is observed in control synovial epithelial cells and foamy macrophages of arterial walls, but was decreased in synovial epithelium of RA patients. Its expression in foamy macrophages of atherosclerotic vascular walls exhibits a positive correlation (r = 0.6276, p = 0.0002) with CD68.

CONCLUSION

Our findings suggest that PPARG may serve as a potentially predictive marker for CAD in RA patients, which provides new insights into the molecular mechanism underling RA linked CAD.

IL-12p40 Monomer: A Potential Player in Macrophage Regulation

Macrophages are myeloid phagocytic leukocytes whose functions are to protect against infections, mediate T-cell responses, and maintain tissue homeostasis. IL-12p40 monomer is a cytokine that is largely produced by macrophages, and it has, for the longest time, been considered a largely non-functional cytokine of the IL-12 family. However, new research has emerged that demonstrates that this p40 monomer may play a bigger role in shaping immune environments. To shed light on the specific effects of p40 monomer on macrophages and their surrounding environment, we showed, through cell culture studies, qPCR, ELISA, and immunofluorescence analyses, that the direct administration of recombinant p40 monomer to RAW 264.7 cells and primary lung macrophages stimulated the production of both pro-inflammatory (TNFα) and anti-inflammatory (IL-10) signals. Accordingly, p40 monomer prevented the full pro-inflammatory effects of LPS, and the neutralization of p40 monomer by mAb a3-3a stimulated the pro-inflammatory effects of LPS. Furthermore, we demonstrated that the intranasal administration of p40 monomer upregulated TNFα+IL-10+ macrophages in vivo in the lungs of mice. Collectively, these results indicate an important immunoregulatory function of p40 monomer in the upregulation of both pro- and anti-inflammatory molecules in macrophages.

Advances in the Immunology of the Host-Parasite Interactions in African Trypanosomosis, including Single-Cell Transcriptomics

Trypanosomes are single-celled extracellular parasites that infect mammals, including humans and livestock, causing global public health concerns and economic losses. These parasites cycle between insect vectors, such as tsetse flies and vertebrate hosts, undergoing morphological, cellular, and biochemical changes. They have remarkable immune evasion mechanisms to escape the host's innate and adaptive immune responses, such as surface coat antigenic variation and the induction of the loss of specificity and memory of antibody responses, enabling the prolongation of infection. Since trypanosomes circulate through the host body in blood and lymph fluid and invade various organs, understanding the interaction between trypanosomes and tissue niches is essential. Here, we present an up-to-date overview of host-parasite interactions and survival strategies for trypanosomes by introducing and discussing the latest studies investigating the transcriptomics of parasites according to life cycle stages, as well as host cells in various tissues and organs, using single-cell and spatial sequencing applications. In recent years, this information has improved our understanding of trypanosomosis by deciphering the diverse populations of parasites in the developmental process, as well as the highly heterogeneous immune and tissue-resident cells involved in anti-trypanosome responses. Ultimately, the goal of these approaches is to gain an in-depth understanding of parasite biology and host immunity, potentially leading to new vaccination and therapeutic strategies against trypanosomosis.

Oral Excretion Kinetics of Food-Additive Silicon Dioxides and Their Effect on In Vivo Macrophage Activation

A food additive, silicon dioxide (SiO2) is commonly used in the food industry as an anti-caking agent. The presence of nanoparticles (NPs) in commercial food-grade SiO2 has raised concerns regarding their potential toxicity related to nano size. While recent studies have demonstrated the oral absorption and tissue distribution of food-additive SiO2 particles, limited information is available about their excretion behaviors and potential impact on macrophage activation. In this study, the excretion kinetics of two differently manufactured (fumed and precipitated) SiO2 particles were evaluated following repeated oral administration to rats for 28 d. The excretion fate of their intact particles, decomposed forms, or ionic forms was investigated in feces and urine, respectively. Monocyte uptake, Kupffer cell activation, and cytokine release were assessed after the oral administration of SiO2 particles. Additionally, their intracellular fates were determined in Raw 264.7 cells. The results revealed that the majority of SiO2 particles were not absorbed but directly excreted via feces in intact particle forms. Only a small portion of SiO2 was eliminated via urine, predominantly in the form of bioconverted silicic acid and slightly decomposed ionic forms. SiO2 particles were mainly present in particle forms inside cells, followed by ionic and silicic acid forms, indicating their slow conversion into silicic acid after cellular uptake. No effects of the manufacturing method were observed on excretion and fates. Moreover, no in vivo monocyte uptake, Kupffer cell polarization, or cytokine release were induced by orally administered SiO2 particles. These finding contribute to understanding the oral toxicokinetics of food-additive SiO2 and provide valuable insights into its potential toxicity.

CD163 protein inhibits lipopolysaccharide-induced macrophage transformation from M2 to M1 involved in disruption of the TWEAK-Fn14 interaction

Macrophages play a crucial role in regulating inflammation and innate immune responses, and their polarization into distinct phenotypes, such as M1 and M2, is involved in various diseases. However, the specific role of CD163, a scavenger receptor expressed by macrophages, in the transformation of M2 to M1 macrophages remains unclear. Here, dexamethasone-induced M2 macrophages were treated with lipopolysaccharide (LPS) to induce the transformation of M2 to M1 macrophages. We found that treatment with lipopolysaccharide (LPS) induced the transformation of M2-like macrophages to an M1-like phenotype, as evidenced by increased mRNA levels of Il1b and Tnf, decreased mRNA levels of Cd206 and Il10, and increased TNF-α secretion. Knockdown of CD163 enhanced the phenotypic features of M1 macrophages, while treatment with recombinant CD163 protein (rmCD163) inhibited the LPS-induced M2-to-M1 transformation. Furthermore, LPS stimulation resulted in the activation of P38, ERK, JNK, and NF-κB P65 signaling pathways, and this activation was increased after CD163 knockdown and suppressed after rmCD163 treatment during macrophage transformation. Additionally, we observed that LPS treatment reduced the expression of CD163 in dexamethasone-induced M2 macrophages, leading to a decrease in the CD163-TWEAK complex and an increase in the interaction between TWEAK and Fn14. Overall, our findings suggest that rmCD163 can inhibit the LPS-induced transformation of M2 macrophages to M1 by disrupting the TWEAK-Fn14 interaction and modulating the MAPK-NF-κB pathway.

Advanced lung organoids for respiratory system and pulmonary disease modeling

Amidst the recent coronavirus disease 2019 (COVID-19) pandemic, respiratory system research has made remarkable progress, particularly focusing on infectious diseases. Lung organoid, a miniaturized structure recapitulating lung tissue, has gained global attention because of its advantages over other conventional models such as two-dimensional (2D) cell models and animal models. Nevertheless, lung organoids still face limitations concerning heterogeneity, complexity, and maturity compared to the native lung tissue. To address these limitations, researchers have employed co-culture methods with various cell types including endothelial cells, mesenchymal cells, and immune cells, and incorporated bioengineering platforms such as air-liquid interfaces, microfluidic chips, and functional hydrogels. These advancements have facilitated applications of lung organoids to studies of pulmonary diseases, providing insights into disease mechanisms and potential treatments. This review introduces recent progress in the production methods of lung organoids, strategies for improving maturity, functionality, and complexity of organoids, and their application in disease modeling, including respiratory infection and pulmonary fibrosis.

Loss of CFTR function in macrophages alters the cell transcriptional program and delays lung resolution of inflammation

Cystic fibrosis (CF) is an autosomal recessive genetic disorder caused by mutations in the CF Transmembrane-conductance Regulator (CFTR) gene. The most severe pathologies of CF occur in the lung, manifesting as chronic bacterial infection, persistent neutrophilic inflammation, and mucopurulent airway obstruction. Despite increasing knowledge of the CF primary defect and the resulting clinical sequelae, the relationship between the CFTR loss of function and the neutrophilic inflammation remains incompletely understood. Here, we report that loss of CFTR function in macrophages causes extended lung inflammation. After intratracheal inoculation with Pseudomonas aeruginosa, mice with a macrophage-specific Cftr-knockout (Mac-CF) were able to mount an effective host defense to clear the bacterial infection. However, three days post-inoculation, Mac-CF lungs demonstrated significantly more neutrophil infiltration and higher levels of inflammatory cytokines, suggesting that Mac-CF mice had a slower resolution of inflammation. Single-cell RNA sequencing revealed that absence of CFTR in the macrophages altered the cell transcriptional program, affecting the cell inflammatory and immune responses, antioxidant system, and mitochondrial respiration. Thus, loss of CFTR function in macrophages influences cell homeostasis, leading to a dysregulated cellular response to infection that may exacerbate CF lung disease.

Efferocytosis: a double-edged sword in microbial immunity

Efferocytosis is characterized as the rapid and efficient process by which dying or dead cells are removed. This type of clearance is initiated via "find-me" signals, and then, carries on by "eat-me" and "don't-eat-me" ones. Efferocytosis has a critical role to play in tissue homeostasis and innate immunity. However, some evidence suggests it as a double-edged sword in microbial immunity. In other words, some pathogens have degraded efferocytosis by employing efferocytic mechanisms to bypass innate immune detection and promote infection, despite the function of this process for the control and clearance of pathogens. In this review, the efferocytosis mechanisms from the recognition of dying cells to phagocytic engulfment are initially presented, and then, its diverse roles in inflammation and immunity are highlighted. In this case, much focus is also laid on some bacterial, viral, and parasitic infections caused by Mycobacterium tuberculosis (M. tb), Mycobacterium marinum (M. marinum), Listeria monocytogenes (L. monocytogenes), Chlamydia pneumoniae (CP), Klebsiella pneumoniae (KP), Influenza A virus (IAV), human immunodeficiency virus (HIV), and Leishmania, respectively.

Burkholderia pseudomallei BicA protein promotes pathogenicity in macrophages by regulating invasion, intracellular survival, and virulence

Burkholderia pseudomallei (Bpm) is the causative agent of melioidosis disease. Bpm is a facultative intracellular pathogen with a complex life cycle inside host cells. Pathogenic success depends on a variety of virulence factors with one of the most critical being the type 6 secretion system (T6SS). Bpm uses the T6SS to move into neighboring cells, resulting in multinucleated giant cell (MNGC) formation, a strategy used to disseminate from cell to cell. Our prior study using a dual RNA-seq analysis to dissect T6SS-mediated virulence on intestinal epithelial cells identified BicA as a factor upregulated in a T6SS mutant. BicA regulates both type 3 secretion system (T3SS) and T6SSs; however, the extent of its involvement during disease progression is unclear. To fully dissect the role of BicA during systemic infection, we used two macrophage cell lines paired with a pulmonary in vivo challenge murine model. We found that ΔbicA has a distinct intracellular replication defect in both immortalized and primary macrophages, which begins as early as 1 h post-infection. This intracellular defect is linked with the lack of cell-to-cell dissemination and MNGC formation as well as a defect in T3SS expression. The in vitro phenotype translated in vivo as ΔbicA was attenuated in a pulmonary model of infection, demonstrating a distinct macrophage activation profile and a lack of pathological features present in the wild type. Overall, these results highlight the role of BicA in regulating intracellular virulence and demonstrate that specific regulation of secretion systems has a significant effect on host response and Bpm pathogenesis. IMPORTANCE Melioidosis is an understudied tropical disease that still results in ~50% fatalities in infected patients. It is caused by the Gram-negative bacillus Burkholderia pseudomallei (Bpm). Bpm is an intracellular pathogen that disseminates from the infected cell to target organs, causing disseminated disease. The regulation of secretion systems involved in entry and cell-to-cell spread is poorly understood. In this work, we characterize the role of BicA as a regulator of secretion systems during infection of macrophages in vitro and in vivo. Understanding how these virulence factors are controlled will help us determine their influence on the host cells and define the macrophage responses associated with bacterial clearance.

PROMOTING MITOCHONDRIAL DYNAMIC EQUILIBRIUM ATTENUATES SEPSIS-INDUCED ACUTE LUNG INJURY BY INHIBITING PROINFLAMMATORY POLARIZATION OF ALVEOLAR MACROPHAGES

ABSTRACT

Sepsis-induced acute lung injury (ALI)/acute respiratory distress syndrome (ARDS) is characterized by widespread pulmonary inflammation and immune response, in which proinflammatory polarization of alveolar macrophages (AMs) plays an important role. Mitochondria are the key intracellular signaling platforms regulating immune cell responses. Moreover, accumulating evidence suggests that the mitochondrial dynamics of macrophages are imbalanced in sepsis and severe ALI/ARDS. However, the functional significance of mitochondrial dynamics of AMs in septic ALI/ARDS remains largely unknown, and whether it regulates the polarized phenotype of AMs is also unclear. Here, we demonstrated that the mitochondrial dynamics of AMs are imbalanced, manifested by impaired mitochondrial fusion, increased fission and mitochondrial cristae remodeling, both in septic models and ARDS patients. However, suppressing excessive mitochondrial fission with Mdivi-1 or promoting mitochondrial fusion with PM1 to maintain mitochondrial dynamic equilibrium in AMs could inhibit the polarization of AMs into proinflammatory phenotype and attenuate sepsis-induced ALI. These data suggest that mitochondrial dynamic imbalance mediates altered polarization of AMs and exacerbates sepsis-induced ALI. This study provides new insights into the underlying mechanisms of sepsis-induced ALI, suggesting the possibility of identifying future drug targets from the perspective of mitochondrial dynamics in AMs.

Glucocorticoids Impair the 7α-Hydroxycholesterol-Enhanced Innate Immune Response

Glucocorticoids suppress the vascular inflammation that occurs under hypercholesterolemia, as demonstrated in an animal model fed a high-cholesterol diet. However, the molecular mechanisms underlying these beneficial effects remain poorly understood. Because cholesterol is oxidized to form cholesterol oxides (oxysterols) that are capable of inducing inflammation, we investigated whether glucocorticoids affect the immune responses evoked by 7α-hydroxycholesterol (7αOHChol). The treatment of human THP-1 monocytic cells with dexamethasone (Dex) and prednisolone (Pdn) downregulated the expression of pattern recognition receptors (PRRs), such as TLR6 and CD14, and diminished 7αOHChol-enhanced response to FSL-1, a TLR2/6 ligand, and lipopolysaccharide, which interacts with CD14 to initiate immune responses, as determined by the reduced secretion of IL-23 and CCL2, respectively. Glucocorticoids weakened the 7αOHChol-induced production of CCL2 and CCR5 ligands, which was accompanied by decreased migration of monocytic cells and CCR5-expressing Jurkat T cells. Treatment with Dex or Pdn also reduced the phosphorylation of the Akt-1 Src, ERK1/2, and p65 subunits. These results indicate that both Dex and Pdn impair the expression of PRRs and their downstream products, chemokine production, and phosphorylation of signaling molecules. Collectively, glucocorticoids suppress the innate immune response and activation of monocytic cells to an inflammatory phenotype enhanced or induced by 7αOHChol, which may contribute to the anti-inflammatory effects in hypercholesterolemic conditions.

Activatable Nanoreporters for Real-Time Tracking of Macrophage Phenotypic States Associated with Disease Progression

Diagnosis of inflammatory diseases is characterized by identifying symptoms, biomarkers, and imaging. However, conventional techniques lack the sensitivities and specificities to detect disease early. Here, it is demonstrated that the detection of macrophage phenotypes, from inflammatory M1 to alternatively activated M2 macrophages, corresponding to the disease state can be used to predict the prognosis of various diseases. Activatable nanoreporters that can longitudinally detect the presence of the enzyme Arginase 1, a hallmark of M2 macrophages, and nitric oxide, a hallmark of M1 macrophages are engineered, in real-time. Specifically, an M2 nanoreporter enables the early imaging of the progression of breast cancer as predicted by selectively detecting M2 macrophages in tumors. The M1 nanoreporter enables real-time imaging of the subcutaneous inflammatory response that rises from a local lipopolysccharide (LPS) administration. Finally, the M1-M2 dual nanoreporter is evaluated in a muscle injury model, where an initial inflammatory response is monitored by imaging M1 macrophages at the site of inflammation, followed by a resolution phase monitored by the imaging of infiltrated M2 macrophages involved in matrix regeneration and wound healing. It is anticipated that this set of macrophage nanoreporters may be utilized for early diagnosis and longitudinal monitoring of inflammatory responses in various disease models.

IL-1β/IL-1R1 signaling is involved in the propagation of α-synuclein pathology of the gastrointestinal tract to the brain

The pathological hallmark of Parkinson's disease (PD) is the intraneuronal accumulation of misfolded alpha-synuclein (termed Lewy bodies) in dopaminergic neurons of substantia nigra par compacta (SNc). It is assumed that the α-syn pathology is induced by gastrointestinal inflammation and then transfers to the brain by the gut-brain axis. Therefore, the relationship between gastrointestinal inflammation and α-syn pathology leading to PD remains to be investigated. In our study, rotenone (ROT) oral administration induces gastrointestinal tract (GIT) inflammation in mice. In addition, we used pseudorabies virus (PRV) for tracing studies and performed behavioral testing. We observed that ROT treatments enhance macrophage activation, inflammatory mediator expression, and α-syn pathology in the GIT 6-week post-treatment (P6). Moreover, pathological α-syn was localized with IL-1R1 positive neural cells in GIT. In line with these findings, we also find pS129-α-syn signals in the dorsal motor nucleus of the vagus (DMV) and tyrosine hydroxylase in the nigral-striatum dynamically change from 3-week post-treatment (P3) to P6. Following that, pS129-α-syn was dominant in the enteric neural cell, DMV, and SNc, accompanied by microglial activation, and these phenotypes were absent in IL-1R1r/r mice. These data suggest that IL-1β/IL-1R1-dependent inflammation of GIT can induce α-syn pathology, which then propagates to the DMV and SNc, resulting in PD.

Corruptive Reprograming of Macrophages into Tumor-Associated Macrophages: The Transcriptional, Epigenetic and Metabolic Basis

The tumor microenvironment (TME) is an important place with regard to the growth and sustenance of tumor cells [...].

A role for platelets in metabolic reprogramming of tumor-associated macrophages

Cancer incidence and mortality are growing worldwide. With a lack of optimal treatments across many cancer types, there is an unmet need for the development of novel treatment strategies for cancer. One approach is to leverage the immune system for its ability to survey for cancer cells. However, cancer cells evolve to evade immune surveillance by establishing a tumor microenvironment (TME) that is marked by remarkable immune suppression. Macrophages are a predominant immune cell within the TME and have a major role in regulating tumor growth. In the TME, macrophages undergo metabolic reprogramming and differentiate into tumor-associated macrophages (TAM), which typically assume an immunosuppressive phenotype supportive of tumor growth. However, the plasticity of macrophage biology offers the possibility that macrophages may be promising therapeutic targets. Among the many determinants in the TME that may shape TAM biology, platelets can also contribute to cancer growth and to maintaining immune suppression. Platelets communicate with immune cells including macrophages through the secretion of immune mediators and cell-cell interaction. In other diseases, altering platelet secretion and cell-cell communication has been shown to reprogram macrophages and ameliorate inflammation. Thus, intervening on platelet-macrophage biology may be a novel therapeutic strategy for cancer. This review discusses our current understanding of the interaction between platelets and macrophages in the TME and details possible strategies for reprogramming macrophages into an anti-tumor phenotype for suppressing tumor growth.

Cell-targeted vaccines: implications for adaptive immunity

Recent advancements in immunology and chemistry have facilitated advancements in targeted vaccine technology. Targeting specific cell types, tissue locations, or receptors can allow for modulation of the adaptive immune response to vaccines. This review provides an overview of cellular targets of vaccines, suggests methods of targeting and downstream effects on immune responses, and summarizes general trends in the literature. Understanding the relationships between vaccine targets and subsequent adaptive immune responses is critical for effective vaccine design. This knowledge could facilitate design of more effective, disease-specialized vaccines.

Transcriptomic Effects of Low-Dose Inorganic Arsenic Exposure on Murine Bone Marrow-Derived Macrophages

Both tissue-resident macrophages and monocytes recruited from the bone marrow that transform into tissue-resident cells play critical roles in mediating homeostasis as well as in the pathology of inflammatory diseases. Inorganic arsenic (iAs) is the most common drinking water contaminant worldwide and represents a major public health concern. Several diseases that macrophages have implicated involvement in are caused by iAs exposure, including cardiovascular disease, cancer, and increased risk of infectious disease. Therefore, understanding the effects of iAs exposure on macrophages can help us better grasp the full range of arsenic immunotoxicity and better design therapeutic targets for iAs-induced diseases particularly in exposed populations. In this study, we analyzed the transcriptome of low dose iAs-exposed male and female murine bone marrow-derived macrophages (BMDMs) with either M0, M1, or M2 stimulation. We identified differentially expressed genes by iAs in a sex- and stimulation-dependent manner and used bioinformatics tools to predict protein-protein interactions, transcriptional regulatory networks, and associated biological processes. Overall, our data suggest that M1-stimulated, especially female-derived, BMDMs are most susceptible to iAs exposure. Most notably, we observed significant downregulation of major proinflammatory transcription factors, like IRF8, and its downstream targets, as well as genes encoding proteins involved in pattern recognition and antigen presentation, such as TLR7, TLR8, and H2-D1, potentially providing causal insight regarding arsenic's role in perturbing immune responses to infectious diseases. We also observed significant downregulation of genes involved in processes crucial to coordinating a proinflammatory response including leukocyte migration, differentiation, and cytokine and chemokine production and response. Finally, we discovered that 24 X-linked genes were dysregulated in iAs-exposed female stimulation groups compared to only 3 across the iAs-exposed male stimulation groups. These findings elucidate the potential mechanisms underlying the sex-differential iAs-associated immune-related disease risk.

Damage-mediated macrophage polarization in sterile inflammation

Most of the leading causes of death, such as cardiovascular diseases, cancer, dementia, neurodegenerative diseases, and many more, are associated with sterile inflammation, either as a cause or a consequence of these conditions. The ability to control the progression of inflammation toward tissue resolution before it becomes chronic holds significant clinical potential. During sterile inflammation, the initiation of inflammation occurs through damage-associated molecular patterns (DAMPs) in the absence of pathogen-associated molecules. Macrophages, which are primarily localized in the tissue, play a pivotal role in sensing DAMPs. Furthermore, macrophages can also detect and respond to resolution-associated molecular patterns (RAMPs) and specific pro-resolving mediators (SPMs) during sterile inflammation. Macrophages, being highly adaptable cells, are particularly influenced by changes in the microenvironment. In response to the tissue environment, monocytes, pro-inflammatory macrophages, and pro-resolution macrophages can modulate their differentiation state. Ultimately, DAMP and RAMP-primed macrophages, depending on the predominant subpopulation, regulate the balance between inflammatory and resolving processes. While sterile injury and pathogen-induced reactions may have distinct effects on macrophages, most studies have focused on macrophage responses induced by pathogens. In this review, which emphasizes available human data, we illustrate how macrophages sense these mediators by examining the expression of receptors for DAMPs, RAMPs, and SPMs. We also delve into the signaling pathways induced by DAMPs, RAMPs, and SPMs, which primarily contribute to the regulation of macrophage differentiation from a pro-inflammatory to a pro-resolution phenotype. Understanding the regulatory mechanisms behind the transition between macrophage subtypes can offer insights into manipulating the transition from inflammation to resolution in sterile inflammatory diseases.

Breaking down the tumor immune infiltration within pediatric sarcomas

Immunotherapies are a promising therapeutic option, yet for a variety of reasons, these treatments have achieved limited success against sarcomas. The immunosuppressive tumor microenvironment (TME) of sarcomas as well as lack of predictive biomarkers, decreased T-cell clonal frequency, and high expression of immunosuppressive infiltrating cells has thus far prevented major success using immunotherapies. By breaking down the TME into its individual components and understanding how the various cell types interact with each other as well as in the context of the complex immune microenvironment, can lead to effective therapeutic immunotherapy treatments, potentially improving outcomes for those with metastatic disease.

Activation of Kupffer cells in NAFLD and NASH: mechanisms and therapeutic interventions

Non-alcoholic fatty liver disease (NAFLD) and non-alcoholic steatohepatitis (NASH) are emerging as the leading causes of liver disease worldwide. These conditions can lead to cirrhosis, liver cancer, liver failure, and other related ailments. At present, liver transplantation remains the sole treatment option for end-stage NASH, leading to a rapidly growing socioeconomic burden. Kupffer cells (KCs) are a dominant population of macrophages that reside in the liver, playing a crucial role in innate immunity. Their primary function includes phagocytosing exogenous substances, presenting antigens, and triggering immune responses. Moreover, they interact with other liver cells during the pathogenesis of NAFLD, and this crosstalk may either delay or exacerbate disease progression. Stimulation by endogenous signals triggers the activation of KCs, resulting in the expression of various inflammatory factors and chemokines, such as NLRP3, TNF-α, IL-1B, and IL-6, and contributing to the inflammatory cascade. In the past 5 years, significant advances have been made in understanding the biological properties and immune functions of KCs in NAFLD, including their interactions with tissue molecules, underlying molecular mechanisms, signaling pathways, and relevant therapeutic interventions. Having a comprehensive understanding of these mechanisms and characteristics can have enormous potential in guiding future strategies for the prevention and treatment of NAFLD.

The Important Roles of Natural Killer Cells in Liver Fibrosis

Liver fibrosis accompanies the development of various chronic liver diseases and promotes their progression. It is characterized by the abnormal accumulation of extracellular matrix proteins (ECM) and impaired ECM degradation. Activated hepatic stellate cells (HSCs) are the major cellular source of ECM-producing myofibroblasts. If liver fibrosis is uncontrolled, it may lead to cirrhosis and even liver cancer, primarily hepatocellular carcinoma (HCC). Natural killer (NK) cells are a key component of innate immunity and have miscellaneous roles in liver health and disease. Accumulating evidence shows that NK cells play dual roles in the development and progression of liver fibrosis, including profibrotic and anti-fibrotic functions. Regulating NK cells can suppress the activation of HSCs and improve their cytotoxicity against activated HSCs or myofibroblasts to reverse liver fibrosis. Cells such as regulatory T cells (Tregs) and molecules such as prostaglandin E receptor 3 (EP3) can regulate the cytotoxic function of NK cells. In addition, treatments such as alcohol dehydrogenase 3 (ADH3) inhibitors, microRNAs, natural killer group 2, member D (NKG2D) activators, and natural products can enhance NK cell function to inhibit liver fibrosis. In this review, we summarized the cellular and molecular factors that affect the interaction of NK cells with HSCs, as well as the treatments that regulate NK cell function against liver fibrosis. Despite a lot of information about NK cells and their interaction with HSCs, our current knowledge is still insufficient to explain the complex crosstalk between these cells and hepatocytes, liver sinusoidal endothelial cells, Kupffer cells, B cells, and T cells, as well as thrombocytes, regarding the development and progression of liver fibrosis.

Exosomal Non-Coding RNAs: Novel Regulators of Macrophage-Linked Intercellular Communication in Lung Cancer and Inflammatory Lung Diseases

Macrophages are innate immune cells and often classified as M1 macrophages (pro-inflammatory states) and M2 macrophages (anti-inflammatory states). Exosomes are cell-derived nanovesicles that range in diameter from 30 to 150 nm. Non-coding RNAs (ncRNAs), including microRNAs (miRNAs), long noncoding RNAs (lncRNAs), and circular RNAs (circRNAs), are abundant in exosomes and exosomal ncRNAs influence immune responses. Exosomal ncRNAs control macrophage-linked intercellular communication via their targets or signaling pathways, which can play positive or negative roles in lung cancer and inflammatory lung disorders, including acute lung injury (ALI), asthma, and pulmonary fibrosis. In lung cancer, exosomal ncRNAs mediated intercellular communication between lung tumor cells and tumor-associated macrophages (TAMs), coordinating cancer proliferation, migration, invasion, metastasis, immune evasion, and therapy resistance. In inflammatory lung illnesses, exosomal ncRNAs mediate macrophage activation and inflammation to promote or inhibit lung damage. Furthermore, we also discussed the possible applications of exosomal ncRNA-based therapies for lung disorders.

Culture density influences the functional phenotype of human macrophages

Macrophages (MΦ) are commonly cultured in vitro as a model of their biology and functions in tissues. Recent evidence suggests MΦ to engage in quorum sensing, adapting their functions in response to cues about the proximity of neighboring cells. However, culture density is frequently overlooked in the standardization of culture protocols as well as the interpretation of results obtained in vitro. In this study, we investigated how the functional phenotype of MΦ was influenced by culture density. We assessed 10 core functions of human MΦ derived from the THP-1 cell line as well as primary monocyte-derived MΦ. THP-1 MΦ showed increasing phagocytic activity and proliferation with increasing density but decreasing lipid uptake, inflammasome activation, mitochondrial stress, and secretion of cytokines IL-10, IL-6, IL-1β, IL-8, and TNF-α. For THP-1 MΦ, the functional profile displayed a consistent trajectory with increasing density when exceeding a threshold (of 0.2 x 103 cells/mm2), as visualized by principal component analysis. Culture density was also found to affect monocyte-derived MΦ, with functional implications that were distinct from those observed in THP-1 MΦ, suggesting particular relevance of density effects for cell lines. With increasing density, monocyte-derived MΦ exhibited progressively increased phagocytosis, increased inflammasome activation, and decreased mitochondrial stress, whereas lipid uptake was unaffected. These different findings in THP-1 MΦ and monocyte-derived MΦ could be attributed to the colony-forming growth pattern of THP-1 MΦ. At the lowest density, the distance to the closest neighboring cells showed greater influence on THP-1 MΦ than monocyte-derived MΦ. In addition, functional differences between monocyte-derived MΦ from different donors could at least partly be attributed to differences in culture density. Our findings demonstrate the importance of culture density for MΦ function and demand for awareness of culture density when conducting and interpreting in vitro experiments.

Cytotoxicity and Autophagy Induced by Ivermectin via AMPK/mTOR Signaling Pathway in RAW264.7 Cells

The widespread and excessive use of ivermectin (IVM) will not only cause serious environmental pollution, but will also affect metabolism of humans and other mammals that are exposed. IVM has the characteristics of being widely distributed and slowly metabolized, which will cause potential toxicity to the body. We focused on the metabolic pathway and mechanism of toxicity of IVM on RAW264.7 cells. Colony formation and LDH detection assay showed that IVM significantly inhibited the proliferation of and induced cytotoxicity in RAW264.7 cells. Intracellular biochemical analysis using Western blotting assay showed that LC3-B and Beclin-1 were upregulated and p62 was down-regulated. The combination of confocal fluorescence, calcein-AM/CoCl₂, and fluorescence probe results showed that IVM could induce the opening of the mitochondrial membrane permeability transition pore, reduce mitochondrial content, and increase lysosome content. In addition, we focused on induction of IVM in the autophagy signal pathway. The Western blotting results showed that IVM increased expression of p-AMPK and decreased p-mTOR and p-S6K expression in protein levels, indicating that IVM activated the AMPK/mTOR signaling pathway. Therefore, IVM may inhibit cell proliferation by inducing cell cycle arrest and autophagy.