Transcriptional profiling identifies novel regulators of macrophage polarization

A detailed insight into macrophages' role in shaping lung carcinogenesis

Despite significant advancements in cancer treatment in recent decades, the high mortality rate associated with lung cancer remains a significant concern. The development and proper execution of new targeted therapies needs more deep knowledge regarding the lung cancer associated tumour microenvironment. One of the key component of that tumour microenvironment is the lung resident macrophages. Although in normal physiological condition the lung resident macrophages are believed to maintain lung homeostasis, but they may also initiate a vicious inflammatory response in abnormal conditions which is linked to lung cancer development. Depending on the activation pathway, the lung resident macrophages are either of M1 or M2 sub-type. The M1 and M2 sub-types differ significantly in various prospectuses, from phenotypic markers to metabolic pathways. In addition to this generalized classification, the recent advancement of the multiomics technology is able to identify some other sub-types of lung resident macrophages. Researchers have also observed that these different sub-types can manipulate the pathogenesis of lung carcinogenesis in a context dependent manner and can either promote or inhibit the development of lung carcinogenesis upon receiving proper activation. As proper knowledge about the role played by the lung resident macrophages' in shaping the lung carcinogenesis is limited, so the main purpose of this review is to bring all the available information under the same roof. We also elaborated the different mechanisms involved in maintenance of the plasticity of M1/M2 sub-type, as this plasticity can be a good target for lung cancer treatment.

Stimulus-response signaling dynamics characterize macrophage polarization states

The functional state of cells is dependent on their microenvironmental context. Prior studies described how polarizing cytokines alter macrophage transcriptomes and epigenomes. Here, we characterized the functional responses of 6 differentially polarized macrophage populations by measuring the dynamics of transcription factor nuclear factor κB (NF-κB) in response to 8 stimuli. The resulting dataset of single-cell NF-κB trajectories was analyzed by three approaches: (1) machine learning on time-series data revealed losses of stimulus distinguishability with polarization, reflecting canalized effector functions. (2) Informative trajectory features driving stimulus distinguishability ("signaling codons") were identified and used for mapping a cell state landscape that could then locate macrophages conditioned by an unrelated condition. (3) Kinetic parameters, inferred using a mechanistic NF-κB network model, provided an alternative mapping of cell states and correctly predicted biochemical findings. Together, this work demonstrates that a single analyte's dynamic trajectories may distinguish the functional states of single cells and molecular network states underlying them. A record of this paper's transparent peer review process is included in the supplemental information.

Jagged2 targeting in lung cancer activates anti-tumor immunity via Notch-induced functional reprogramming of tumor-associated macrophages

Signaling through Notch receptors intrinsically regulates tumor cell development and growth. Here, we studied the role of the Notch ligand Jagged2 on immune evasion in non-small cell lung cancer (NSCLC). Higher expression of JAG2 in NSCLC negatively correlated with survival. In NSCLC pre-clinical models, deletion of Jag2, but not Jag1, in cancer cells attenuated tumor growth and activated protective anti-tumor T cell responses. Jag2-/- lung tumors exhibited higher frequencies of macrophages that expressed immunostimulatory mediators and triggered T cell-dependent anti-tumor immunity. Mechanistically, Jag2 ablation promoted Nr4a-mediated induction of Notch ligands DLL1/4 on cancer cells. DLL1/4-initiated Notch1/2 signaling in macrophages induced the expression of transcription factor IRF4 and macrophage immunostimulatory functionality. IRF4 expression was required for the anti-tumor effects of Jag2 deletion in lung tumors. Antibody targeting of Jagged2 inhibited tumor growth and activated IRF4-driven macrophage-mediated anti-tumor immunity. Thus, Jagged2 orchestrates immunosuppressive systems in NSCLC that can be overcome to incite macrophage-mediated anti-tumor immunity.

Myeloid A20 is critical for alternative macrophage polarization and type-2 immune-mediated helminth resistance

Background

Protective immunity against intestinal helminths requires induction of robust type-2 immunity orchestrated by various cellular and soluble effectors which promote goblet cell hyperplasia, mucus production, epithelial proliferation, and smooth muscle contractions to expel worms and re-establish immune homeostasis. Conversely, defects in type-2 immunity result in ineffective helminth clearance, persistent infection, and inflammation. Macrophages are highly plastic cells that acquire an alternatively activated state during helminth infection, but they were previously shown to be dispensable for resistance to Trichuris muris infection.

Methods

We use the in vivo mouse model A20myel-KO, characterized by the deletion of the potent anti-inflammatory factor A20 (TNFAIP3) specifically in the myeloid cells, the excessive type-1 cytokine production, and the development of spontaneous arthritis. We infect A20myel-KO mice with the gastrointestinal helminth Trichuris muris and we analyzed the innate and adaptive responses. We performed RNA sequencing on sorted myeloid cells to investigate the role of A20 on macrophage polarization and type-2 immunity. Moreover, we assess in A20myel-KO mice the pharmacological inhibition of type-1 cytokine pathways on helminth clearance and the infection with Salmonella typhimurium.

Results

We show that proper macrophage polarization is essential for helminth clearance, and we identify A20 as an essential myeloid factor for the induction of type-2 immune responses against Trichuris muris. A20myel-KO mice are characterized by persistent Trichuris muris infection and intestinal inflammation. Myeloid A20 deficiency induces strong classical macrophage polarization which impedes anti-helminth type-2 immune activation; however, it promotes detrimental Th1/Th17 responses. Antibody-mediated neutralization of the type-1 cytokines IFN-γ, IL-18, and IL-12 prevents myeloid-orchestrated Th1 polarization and re-establishes type-2-mediated protective immunity against T. muris in A20myel-KO mice. In contrast, the strong Th1-biased immunity in A20myel-KO mice offers protection against Salmonella typhimurium infection.

Conclusions

We hereby identify A20 as a critical myeloid factor for correct macrophage polarization and appropriate adaptive mucosal immunity in response to helminth and enteric bacterial infection.

Intracavitary Spraying of Nanoregulator-Encased Hydrogel Modulates Cholesterol Metabolism of Glioma-Supportive Macrophage for Postoperative Glioblastoma Immunotherapy

Glioblastoma multiforme (GBM) is notoriously resistant to immunotherapy due to its intricate immunosuppressive tumor microenvironment (TME). Dysregulated cholesterol metabolism is implicated in the TME and promotes tumor progression. Here, it is found that cholesterol levels in GBM tissues are abnormally high, and glioma-supportive macrophages (GSMs), an essential "cholesterol factory", demonstrate aberrantly hyperactive cholesterol metabolism and efflux, providing cholesterol to fuel GBM growth and induce CD8+ T cells exhaustion. Bioinformatics analysis confirms that high 7-dehydrocholesterol reductase (DHCR7) level in GBM tissues associates with increased cholesterol biosynthesis, suppressed tumoricidal immune response, and poor patient survival, and DHCR7 expression level is significantly elevated in GSMs. Therefore, an intracavitary sprayable nanoregulator (NR)-encased hydrogel system to modulate cholesterol metabolism of GSMs is reported. The degradable NR-mediated ablation of DHCR7 in GSMs effectively suppresses cholesterol supply and activates T-cell immunity. Moreover, the combination of Toll-like receptor 7/8 (TLR7/8) agonists significantly promotes GSM polarization to antitumor phenotypes and ameliorates the TME. Treatment with the hybrid system exhibits superior antitumor effects in the orthotopic GBM model and postsurgical recurrence model. Altogether, the findings unravel the role of GSMs DHCR7/cholesterol signaling in the regulation of TME, presenting a potential treatment strategy that warrants further clinical trials.

Investigating the Diagnostic and Therapeutic Potential of SREBF2-Related Lipid Metabolism Genes in Colon Cancer

Purpose

Colon cancer is one of the leading causes of death worldwide, and screening of effective molecular markers for the diagnosis is prioritised for prevention and treatment. This study aimed to investigate the diagnostic and predictive potential of genes related to the lipid metabolism pathway, regulated by a protein called sterol-regulatory element-binding transcription Factor 2 (SREBF2), for colon cancer and patient outcomes.

Methods

We used machine-learning algorithms to identify key genes associated with SREBF2 in colon cancer based on a public database. A nomogram was created to assess the diagnostic value of these genes and validated in the Cancer Genome Atlas. We also analysed the relationship between these genes and the immune microenvironment of colon tumours, as well as the correlation between gene expression and clinicopathological characteristics and prognosis in the China Medical University (CMU) clinical cohort.

Results

Three genes, 7-dehydrocholesterol reductase (DHCR7), hydroxysteroid 11-beta dehydrogenase 2 (HSD11B2), and Ral guanine nucleotide dissociation stimulator-like 1 (RGL1), were identified as hub genes related to SREBF2 and colon cancer. Using the TCGA dataset, receiver operating characteristic curve analysis showed the area under the curve values of 0.943, 0.976, and 0.868 for DHCR7, HSD11B2, and RGL1, respectively. In the CMU cohort, SREBF2 and DHCR7 expression levels were correlated with TNM stage and tumour invasion depth (P < 0.05), and high DHCR7 expression was related to poor prognosis of colon cancer (P < 0.05). Furthermore, DHCR7 gene expression was positively correlated with the abundance of M0 and M1 macrophages and inversely correlated with the abundance of M2 macrophages, suggesting that the immune microenvironment may play a role in colon cancer surveillance. There was a correlation between SREBF2 and DHCR7 expression across cancers in the TCGA database.

Conclusion

This study highlights the potential of DHCR7 as a diagnostic marker and therapeutic target for colon cancer.

Biochemical and molecular inducers and modulators of M2 macrophage polarization in clinical perspective

Macrophages as innate immune cells with great plasticity are of great interest for cell therapy. There are two main macrophage populations - pro- and anti-inflammatory cells also known as M1 and M2. High potential in cancer research contributed to the in-depth study of the molecular processes leading to the polarization of macrophages into the M1 phenotype, and much less attention has been paid to anti-inflammatory M2 macrophages, which can be successfully used in cell therapy of inflammatory diseases. This review describes ontogenesis of macrophages, main functions of pro- and and-inflammatory cells and four M2 subpopulations characterized by different functionalities. Data on agents (cytokines, microRNAs, drugs, plant extracts) that may induce M2 polarization through the changes in microenvironment, metabolism, and efferocytosis are summarized. Finally, recent attempts at stable macrophage polarization using genetic modifications are described. This review may be helpful for researchers concerned with the problem of M2 macrophage polarization and potential use of these anti-inflammatory cells for the purposes of regenerative medicine.

Macrophage Activity under Hyperglycemia: A Study of the Effect of Resveratrol and 3H-1,2-Dithiole-3-thione on Potential Polarization

Currently, research is focused on bioactive compounds with the potential to promote macrophage polarization with the aim of reducing the development of inflammatory-related diseases. However, the effect of bioactive compounds under oxidative-stress-induced hyperglycemia on macrophage polarization has been scarcely investigated. RAW 264.7 macrophages were incubated under standard (SG) or high glucose (HG) conditions and stimulated with lipopolysaccharide (LPS) (10, 60 and 100 ng/mL) to monitor macrophage polarization after resveratrol (RSV) or 3H-1,2-dithiole-3-thione (D3T) supplementation (2.5, 5, 10 and 20 µM). Under SG and HG conditions without LPS stimulation, RSV significantly decreased macrophage viability at the highest concentration (20 µM), whereas D3T had no or low effect. LPS stimulation at 60 and 100 ng/mL, under SG and HG conditions, increased significantly macrophage viability. Both RSV and D3T significantly decreased NO production in LPS-stimulated macrophages under HG condition, whereas only D3T increased GSH levels at 100 ng/mL and normalized MDA values at 60 ng/mL of LPS under HG condition. Under 60 ng/mL LPS stimulation and HG, mRNA IL-1 and IL-6 were higher. Interestingly, RSV decreased pro-inflammatory interleukins; meanwhile, D3T increased Arg1 and IL-10 relative expression. Overall, our results indicate that hyperglycemia plays a fundamental role in the modulation of macrophage-induced inflammation in response to bioactive compounds.

Early ART reduces viral seeding and innate immunity in liver and lungs of SIV-infected macaques

Identifying immune cells and anatomical tissues that contribute to the establishment of viral reservoirs is of central importance in HIV-1 cure research. Herein, we used rhesus macaques (RMs) infected with SIVmac251 to analyze viral seeding in the liver and lungs of either untreated or early antiretroviral therapy-treated (ART-treated) RMs. Consistent with viral replication and sensing, transcriptomic analyses showed higher levels of inflammation, pyroptosis, and chemokine genes as well as of interferon-stimulating gene (ISG) transcripts, in the absence of ART. Our results highlighted the infiltration of monocyte-derived macrophages (HLA-DR+CD11b+CD14+CD16+) in inflamed liver and lung tissues associated with the expression of CD183 and CX3CR1 but also with markers of tissue-resident macrophages (CD206+ and LYVE+). Sorting of myeloid cell subsets demonstrated that CD14+CD206-, CD14+CD206+, and CD14-CD206+ cell populations were infected, in the liver and lungs, in SIVmac251-infected RMs. Of importance, early ART drastically reduced viral seeding consistent with the absence of ISG detection but also of genes related to inflammation and tissue damage. Viral DNA was only detected in CD206+HLA-DR+CD11b+ cells in ART-treated RMs. The observation of pulmonary and hepatic viral rebound after ART interruption reinforces the importance of early ART implementation to limit viral seeding and inflammatory reactions.

Establishment and Characterization of Free-Floating 3D Macrophage Programming Model in the Presence of Cancer Cell Spheroids

Reprogramming of tumor-associated macrophages (TAMs) is a promising strategy for cancer immunotherapy. Several studies have shown that cancer cells induce/support the formation of immunosuppressive TAMs phenotypes. However, the specific factors that orchestrate this immunosuppressive process are unknown or poorly studied. In vivo studies are expensive, complex, and ethically constrained. Therefore, 3D cell interaction models could become a unique framework for the identification of important TAMs programming factors. In this study, we have established and characterized a new in vitro 3D model for macrophage programming in the presence of cancer cell spheroids. First, it was demonstrated that the profile of cytokines, chemokines, and surface markers of 3D-cultured macrophages did not differ conceptually from monolayer-cultured M1 and M2-programmed macrophages. Second, the possibility of reprogramming macrophages in 3D conditions was investigated. In total, the dynamic changes in 6 surface markers, 11 cytokines, and 22 chemokines were analyzed upon macrophage programming (M1 and M2) and reprogramming (M1→M2 and M2→M1). According to the findings, the reprogramming resulted in a mixed macrophage phenotype that expressed both immunosuppressive and anti-cancer immunostimulatory features. Third, cancer cell spheroids were shown to stimulate the production of immunosuppressive M2 markers as well as pro-tumor cytokines and chemokines. In summary, the newly developed 3D model of cancer cell spheroid/macrophage co-culture under free-floating conditions can be used for studies on macrophage plasticity and for the development of targeted cancer immunotherapy.

Expression of O-glycosylated oncofetal fibronectin in alternatively activated human macrophages

Macrophage (Mϕ) polarization is an essential phenomenon for the maintenance of homeostasis and tissue repair, and represents the event by which Mϕ reach divergent functional phenotypes as a result to specific stimuli and/or microenvironmental signals. Mϕ can be polarized into two main phenotypes, M1 or classically activated and M2 or alternatively activated. These two categories diverge in many aspects, such as secreted cytokines, markers of cell surface, and biological functions. Over the last 10 years, many potential markers have been proposed for both M1 and M2 human Mϕ. However, there is scarce information regarding the glycophenotype adopted by these cells. Here, we show that M2- but not M1-polarized Mϕ expresses high levels of an unusual glycoform of fibronectin (FN), named O-glycosylated oncofetal FN (onf-FN), found in fetal/cancer cells, but not in healthy tissues. The onf-FN expression was confirmed in vitro by Western blot and real-time RT-qPCR in primary and cell line monocyte-derived Mϕ. onf-FN was induced by IL-4 and IL-13, but not by pro-inflammatory stimuli (LPS and INF-γ). RNA and protein analysis clearly demonstrated that it is specifically associated with the M2 polarization. In conclusion, we show by the first time that O-glycosylated onf-FN is expressed by M2-polarized Mϕ.

Extracellular Vesicles in Inner Ear Therapies-Pathophysiological, Manufacturing, and Clinical Considerations

(1) Background: Sensorineural hearing loss is a common and debilitating condition. To date, comprehensive pharmacologic interventions are not available. The complex and diverse molecular pathology that underlies hearing loss may limit our ability to intervene with small molecules. The current review foccusses on the potential for the use of extracellular vesicles in neurotology. (2) Methods: Narrative literature review. (3) Results: Extracellular vesicles provide an opportunity to modulate a wide range of pathologic and physiologic pathways and can be manufactured under GMP conditions allowing for their application in the human inner ear. The role of inflammation in hearing loss with a focus on cochlear implantation is shown. How extracellular vesicles may provide a therapeutic option for complex inflammatory disorders of the inner ear is discussed. Additionally, manufacturing and regulatory issues that need to be addressed to develop EVs as advanced therapy medicinal product for use in the inner ear are outlined. (4) Conclusion: Given the complexities of inner ear injury, novel therapeutics such as extracellular vesicles could provide a means to modulate inflammation, stress pathways and apoptosis in the inner ear.

Exploring macrophage differentiation and its relation to Modic changes in human herniated disc tissue

Introduction

Cervical- and lumbosacral radiculopathy symptoms due to disc herniation are likely to be influenced by macrophage infiltration of the herniated disc. Vertebral endplate changes are hypothesized to, at least partially, correlate to the inflammatory condition of the disc and its environment.

Research question

The present study aims to evaluate several immunohistochemical M1-and M2-markers for their suitability to discern pro-inflammatory M1-and anti-inflammatory M2 macrophage differentiation patterns in herniated intervertebral disc tissue. In addition, their associations with Modic changes (MC) of the vertebral endplates will be evaluated.

Materials and methods

Herniated disc samples were collected from 45 patients undergoing surgery for cervical- or lumbosacral radiculopathy. Samples were processed for immunohistochemistry and stained for the presence of macrophages: CD68 (macrophage marker), CD40 (M1), iNOS (M1), CD192 (M1), CD163 (M2), Arg1 (M2) and CD209 (M2). T-cells (CD3) and neutrophil (CD15) expressions were studied additionally.

Results

CD68 positive cells were present with a median density of 50/cm², M2 markers CD163 and CD209 were expressed most dominantly, followed by M1 marker CD192. Other M1/M2 markers, T-cell and neutrophil expression was limited. Lumbar samples showed higher expression of iNOS and Arg1 compared to cervical samples. Presence of Modic changes was associated with higher levels of CD68⁺ cells (p ​= ​0.046), but no significant differences in M1/M2 markers were found.

Discussion and conclusion

For studying M1 macrophages, CD192 is the most suitable marker due to its high expression; whereas for M2 macrophages, this is CD163 due to its high expression and selectivity. Further, the relatively high expression of M2 markers indicates predominance of anti-inflammatory over pro-inflammatory macrophages in symptomatic lumbar and cervical disc herniations. No associations between M1/M2 markers and MC were seen in this limited number of samples. In order to further explore the role of macrophage differentiation and its relation with MC in radiculopathy, a large prospective trial with elaborate clinical follow-up is required.

Canine polarized macrophages express distinct functional and transcriptomic profiles

Macrophage differentiation and function in disease states is highly regulated by the local microenvironment. For example, macrophage exposure to IFN-γ (interferon gamma) initiates the development of inflammatory (M1) macrophages, which acquire anti-tumoral and antimicrobial activity, while exposure to IL-4 (interleukin-4) and IL-13 (interleukin-13) drives an anti-inflammatory (M2) macrophage phenotype, which promotes healing and suppression of inflammatory responses. Previous studies of canine polarized macrophages have identified several surface markers that distinguished GM-CSF (granulocyte macrophage colony stimulating factor), IFN-γ and LPS (lipopolysaccharide) derived M1 macrophages or M2 macrophages; and reported a subset of genes that can be used to differentiate between polarization states. However, the need remains to understand the underlying biological mechanisms governing canine macrophage polarization states. Therefore, in the present study we used transcriptome sequencing, a larger panel of flow cytometry markers, and the addition of antimicrobial functional assays to further characterize canine macrophage polarization. Transcriptome analysis revealed unique, previously unreported signatures and pathways for polarized canine M1 and M2 macrophages. New flow cytometric markers were also identified, along with new characterization of how macrophage polarization impacted antimicrobial functions. Taken together, the findings reported here provide new insights into canine macrophage biology and identify new tools for the evaluation of polarized macrophages in dogs.

High DHCR7 Expression Predicts Poor Prognosis for Cervical Cancer

DHCR7 is a rate-limiting enzyme in cholesterol synthesis. The expression pattern and prognostic value of DHCR7 in cervical cancer are unknown. We investigated the relationship between DHCR7 expression and clinicopathological features of cervical cancer patients. The dataset was acquired from TCGA database. The Wilcoxon rank sum test was used to explore DHCR7 expression level in cervical cancer. The Kruskal-Wallis test and the logistic regression were performed to estimate the association between the DHCR7 and clinical features. The Kaplan-Meier and Cox regression analyses were used to evaluate factors that affect cervical cancer prognosis. GSEA was used to screen the DHCR7-related pathways. We found that DHCR7 was increased in cervical cancer samples and increased DHCR7 was correlated with advanced T stage, lymph node invasion, and clinical stage (P < 0.05). Patients with elevated DHCR7 levels had poorer overall survival (P = 0.021), progression-free interval (P = 0.002), and disease-specific survival (P = 0.005). Cox analysis revealed that DHCR7 was an independent prognostic factor in cervical cancer (P = 0.005). WNT activated receptor activity, G2/M checkpoint, mTORC1 signaling, KRAS signaling, regulation of cholesterol biosynthetic, FGF signaling, T-cell receptor signaling, JAK/STAT signaling cascade T cell activation, and macrophage migration were enriched in high DHCR7 phenotype. Our data also showed that DHCR7 moderately correlates with T-cell infiltration, including CD8⁺ T-cells. Conclusion. Increased DHCR7 expression is associated with poor survival in cervical cancer.

Macrophages as a therapeutic target to promote diabetic wound healing

It is well‏ ‏established that macrophages are key regulators of wound healing, displaying impressive plasticity and an evolving phenotype, from an aggressive pro-inflammatory or "M1" phenotype to a pro-healing or "M2" phenotype, depending on the wound healing stage, to ensure proper healing. Because dysregulated macrophage responses have been linked to impaired healing of diabetic wounds, macrophages are being considered as a therapeutic target for improved wound healing. In this review, we first discuss the role of macrophages in a normal skin wound healing process and discuss the aberrations that occur in macrophages under diabetic conditions. Next we provide an overview of recent macrophage-based therapeutic approaches, including delivery of ex-vivo-activated macrophages and delivery of pharmacological strategies aimed at eliminating or re-educating local skin macrophages. In particular, we focus on strategies to silence key regulator genes to repolarize wound macrophages to the M2 phenotype, and we provide a discussion of their potential future clinical translation.

TREM2 macrophages induced by human lipids drive inflammation in acne lesions

Acne affects 1 in 10 people globally, often resulting in disfigurement. The disease involves excess production of lipids, particularly squalene, increased growth of Cutibacterium acnes, and a host inflammatory response with foamy macrophages. By combining single-cell and spatial RNA sequencing as well as ultrahigh-resolution Seq-Scope analyses of early acne lesions on back skin, we identified TREM2 macrophages expressing lipid metabolism and proinflammatory gene programs in proximity to hair follicle epithelium expressing squalene epoxidase. We established that the addition of squalene induced differentiation of TREM2 macrophages in vitro, which were unable to kill C. acnes. The addition of squalene to macrophages inhibited induction of oxidative enzymes and scavenged oxygen free radicals, providing an explanation for the efficacy of topical benzoyl peroxide in the clinical treatment of acne. The present work has elucidated the mechanisms by which TREM2 macrophages and unsaturated lipids, similar to their involvement in atherosclerosis, may contribute to the pathogenesis of acne.

Hypoxia-inducible lentiviral gene expression in engineered human macrophages

Background

Human immune cells, including monocyte-derived macrophages, can be engineered to deliver proinflammatory cytokines, bispecific antibodies, and chimeric antigen receptors to support immune responses in different disease settings. When gene expression is regulated by constitutively active promoters, lentiviral payload gene expression is unregulated, and can result in potentially toxic quantities of proteins. Regulated delivery of lentivirally encoded proteins may allow localized or conditional therapeutic protein expression to support safe delivery of adoptively transferred, genetically modified cells with reduced capacity for systemic toxicities.

Methods

In this study, we engineered human macrophages to express genes regulated by hypoxia responsive elements included in the lentiviral promoter region to drive conditional lentiviral gene expression only under hypoxic conditions. We tested transduced macrophages cultured in hypoxic conditions for the transient induced expression of reporter genes and the secreted cytokine, interleukin-12. Expression of hypoxia-regulated genes was investigated both transcriptionally and translationally, and in the presence of human tumor cells in a slice culture system. Finally, hypoxia-regulated gene expression was evaluated in a subcutaneous humanized-mouse cancer model.

Results

Engineered macrophages were shown to conditionally and tranisently express lentivirally encoded gene protein products, including IL-12 in hypoxic conditions in vitro. On return to normoxic conditions, lentiviral payload expression returned to basal levels. Reporter genes under the control of hypoxia response elements were upregulated under hypoxic conditions in the presence of human colorectal carcinoma cells and in the hypoxic xenograft model of glioblastoma, suggesting utility for systemic engineered cell delivery capable of localized gene delivery in cancer.

Conclusions

Macrophages engineered to express hypoxia-regulated payloads have the potential to be administered systemically and conditionally express proteins in tissues with hypoxic conditions. In contrast to immune cells that function or survive poorly in hypoxic conditions, macrophages maintain a proinflammatory phenotype that may support continued gene and protein expression when regulated by conditional hypoxia responsive elements and naturally traffic to hypoxic microenvironments, making them ideal vehicles for therapeutic payloads to hypoxic tissues, such as solid tumors. With the ability to fine-tune delivery of potent proteins in response to endogenous microenvironments, macrophage-based cellular therapies may therefore be designed for different disease settings.

IL4 stimulated macrophages promote axon regeneration after peripheral nerve injury by secreting uPA to stimulate uPAR upregulated in injured axons

Accumulating evidences suggest that M2 macrophages are involved with repair processes in the nervous system. However, whether M2 macrophages can promote axon regeneration by directly stimulating axons nor its precise molecular mechanism remains elusive. Here, the current study demonstrated that typical M2 macrophages, which were generated by IL4 simulation, had the capacity to stimulate axonal growth by their direct effect on axons and that the graft of IL4 stimulated macrophages into the region of Wallerian degeneration enhanced axon regeneration and improved functional recovery after PNI. Importantly, uPA (urokinase plasminogen activator)-uPA receptor (uPAR) was identified as the central axis underlying the axon regeneration effect of IL4 stimulated macrophages. IL4 stimulated macrophages secreted uPA, and its inhibition abolished their axon regeneration effect. Injured but not intact axons expressed uPAR to be sensitive to uPA. These results unveil a cellular and molecular mechanism underlying the macrophage related axon regeneration and provide a basis of a novel therapy for PNI.

Raman Microspectroscopy Identifies Biochemical Activation Fingerprints in THP-1- and PBMC-Derived Macrophages

(1) The monocytic leukemia cell line THP-1 and primary monocyte-derived macrophages (MDMs) are popular in vitro model systems to study human innate immunity, wound healing, and tissue regeneration. However, both cell types differ significantly in their origin and response to activation stimuli. (2) Resting THP-1 and MDMs were stimulated with lipopolysaccharide (LPS) and interferon γ (IFNγ) and analyzed by Raman microspectroscopy (RM) before and 48 h after activation. Raman data were subsequently analyzed using principal component analysis. (3) We were able to resolve and analyze the spatial distribution and molecular composition of proteins, nucleic acids, and lipids in resting and activated THP-1 and MDMs. Our findings reveal that proinflammatory activation-induced significant spectral alterations at protein and phospholipid levels in THP-1. In MDMs, we identified that nucleic acid and non-membrane-associated intracellular lipid composition were also affected. (4) Our results show that it is crucial to carefully choose the right cell type for an in vitro model as the nature of the cells itself may impact immune cell polarization or activation results. Moreover, we demonstrated that RM is a sensitive tool for investigating cell-specific responses to activation stimuli and monitoring molecular changes in subcellular structures.

The allergy mediator histamine confers resistance to immunotherapy in cancer patients via activation of the macrophage histamine receptor H1

Reinvigoration of antitumor immunity remains an unmet challenge. Our retrospective analyses revealed that cancer patients who took antihistamines during immunotherapy treatment had significantly improved survival. We uncovered that histamine and histamine receptor H1 (HRH1) are frequently increased in the tumor microenvironment and induce T cell dysfunction. Mechanistically, HRH1-activated macrophages polarize toward an M2-like immunosuppressive phenotype with increased expression of the immune checkpoint VISTA, rendering T cells dysfunctional. HRH1 knockout or antihistamine treatment reverted macrophage immunosuppression, revitalized T cell cytotoxic function, and restored immunotherapy response. Allergy, via the histamine-HRH1 axis, facilitated tumor growth and induced immunotherapy resistance in mice and humans. Importantly, cancer patients with low plasma histamine levels had a more than tripled objective response rate to anti-PD-1 treatment compared with patients with high plasma histamine. Altogether, pre-existing allergy or high histamine levels in cancer patients can dampen immunotherapy responses and warrant prospectively exploring antihistamines as adjuvant agents for combinatorial immunotherapy.

CCL2/MCP-1 serum chemokine level in patients with odontogenic infectious and inflammatory diseases of the soft tissues of the maxillofacial area and mediastinum

Aim. The paper was aimed at determining the CCL2/MCP-1 level in patients with odontogenic infectious and inflammatory diseases of soft tissues of the maxillofacial area and mediastinum. Methods. The study involved 46 patients with odontogenic infectious and inflammatory diseases of soft tissues of the maxillofacial area and 12 healthy volunteers. The level of patients' plasma CCL2/MCP-1 level was determined using a kit for specific ELISA. Results. The findings of the studies showed a statistically significant increase in the concentration of plasma CCL2/MCP-1 in patients of all study groups. Our study shows a significant increase in plasma CCL2/MCP-1 level in patients with odontogenic phlegmonas, abscesses and mediastinitis, compared to the group of healthy subjects. Conclusion. CCL2/MCP-1 may play an important role in the pathogenesis of odontogenic infectious and inflammatory diseases of soft tissues of the maxillofacial area and mediastinum, which requires a careful follow-up study.

Lipidome profiling with Raman microspectroscopy identifies macrophage response to surface topographies of implant materials

Biomaterial characteristics such as surface topographies have been shown to modulate macrophage phenotypes. The standard methodologies to measure macrophage response to biomaterials are marker-based and invasive. Raman microspectroscopy (RM) is a marker-independent, noninvasive technology that allows the analysis of living cells without the need for staining or processing. In the present study, we analyzed human monocyte-derived macrophages (MDMs) using RM, revealing that macrophage activation by lipopolysaccharides (LPS), interferons (IFN), or cytokines can be identified by lipid composition, which significantly differs in M0 (resting), M1 (IFN-γ/LPS), M2a (IL-4/IL-13), and M2c (IL-10) MDMs. To identify the impact of a biomaterial on MDM phenotype and polarization, we cultured macrophages on titanium disks with varying surface topographies and analyzed the adherent MDMs with RM. We detected surface topography-induced changes in MDM biochemistry and lipid composition that were not shown by less sensitive standard methods such as cytokine expression or surface antigen analysis. Our data suggest that RM may enable a more precise classification of macrophage activation and biomaterial-macrophage interaction.

Inhibition of microRNA-494-3p activates Wnt signaling and reduces proinflammatory macrophage polarization in atherosclerosis

We have previously shown that treatment with third-generation antisense oligonucleotides against miR-494-3p (3GA-494) reduces atherosclerotic plaque progression and stabilizes lesions, both in early and established plaques, with reduced macrophage content in established plaques. Within the plaque, different subtypes of macrophages are present. Here, we aimed to investigate whether miR-494-3p directly influences macrophage polarization and activation. Human macrophages were polarized into either proinflammatory M1 or anti-inflammatory M2 macrophages and simultaneously treated with 3GA-494 or a control antisense (3GA-ctrl). We show that 3GA-494 treatment inhibited miR-494-3p in M1 macrophages and dampened M1 polarization, while in M2 macrophages miR-494-3p expression was induced and M2 polarization enhanced. The proinflammatory marker CCR2 was reduced in 3GA-494-treated atherosclerosis-prone mice. Pathway enrichment analysis predicted an overlap between miR-494-3p target genes in macrophage polarization and Wnt signaling. We demonstrate that miR-494-3p regulates expression levels of multiple Wnt signaling components, such as LRP6 and TBL1X. Wnt signaling appears activated upon treatment with 3GA-494, both in cultured M1 macrophages and in plaques of hypercholesterolemic mice. Taken together, 3GA-494 treatment dampened M1 polarization, at least in part via activated Wnt signaling, while M2 polarization was enhanced, which is both favorable in reducing atherosclerotic plaque formation and increasing plaque stability.

Roles of Macrophages in Atherogenesis

Atherosclerosis is a chronic inflammatory disease that may ultimately lead to local proteolysis, plaque rupture, and thrombotic vascular disease, resulting in myocardial infarction, stroke, and sudden cardiac death. Circulating monocytes are recruited to the arterial wall in response to inflammatory insults and differentiate into macrophages which make a critical contribution to tissue damage, wound healing, and also regression of atherosclerotic lesions. Within plaques, macrophages take up aggregated lipoproteins which have entered the vessel wall to give rise to cholesterol-engorged foam cells. Also, the macrophage phenotype is influenced by various stimuli which affect their polarization, efferocytosis, proliferation, and apoptosis. The heterogeneity of macrophages in lesions has recently been addressed by single-cell sequencing techniques. This article reviews recent advances regarding the roles of macrophages in different stages of disease pathogenesis from initiation to advanced atherosclerosis. Macrophage-based therapies for atherosclerosis management are also described.

Role of Macrophage Polarization in Acute Respiratory Distress Syndrome

Acute Respiratory Distress Syndrome is a familiar and destructive clinical condition characterized by progressive, swift and impaired pulmonary state. It leads to mortality if not managed in a timely manner. Recently the role of imbalanced macrophage polarization has been reported in ARDS. Macrophages are known for their heterogeneity and plasticity. Under different microenvironmental stimuli, they (M0) can switch between classically activated macrophage (M1) and alternatively activated (M2) states. This switch is regulated by several signaling pathways and epigenetic changes. In this review, the importance of macrophage M1 and M2 has been discussed in the arena of ARDS citing the phase-wise impact of macrophage polarization. This will provide a further understanding of the molecular mechanism involved in ARDS and will help in developing novel therapeutic targets. Various biomarkers that are currently used concerning this pathophysiological feature have also been summarized.

Oxidation of Hemoglobin Drives a Proatherogenic Polarization of Macrophages in Human Atherosclerosis

Aim: The aim of our study was to explore the pathophysiologic role of oxidation of hemoglobin (Hb) to ferrylHb in human atherosclerosis. Results: We observed a severe oxidation of Hb to ferrylHb in complicated atherosclerotic lesions of carotid arteries with oxidative changes of the globin moieties, detected previously described oxidation hotspots in Hb (β1Cys93; β1Cys112; β2Cys112) and identified a novel oxidation hotspot (α1Cys104). After producing a monoclonal anti-ferrylHb antibody, ferrylHb was revealed to be localized extracellularly and also internalized by macrophages in the human hemorrhagic complicated lesions. We demonstrated that ferrylHb is taken up via phagocytosis as well as CD163 receptor-mediated endocytosis and then transported to lysosomes involving actin polymerization. Internalization of ferrylHb was accompanied by upregulation of heme oxygenase-1 and H-ferritin and accumulation of iron within lysosomes as a result of heme/iron uptake. Importantly, macrophages exposed to ferrylHb in atherosclerotic plaques exhibited a proinflammatory phenotype, as reflected by elevated levels of IL-1β and TNF-α. To find further signatures of ferrylHb in complicated lesions, we performed RNA-seq analysis on biopsies from patients who underwent endarterectomies. RNA-seq analysis demonstrated that human complicated lesions had a unique transcriptomic profile different from arteries and atheromatous plaques. Pathways affected in complicated lesions included gene changes associated with phosphoinositide 3-kinase (PI3K) signaling, lipid transport, tissue remodeling, and vascularization. Targeted analysis of gene expression associated with calcification, apoptosis, and hemolytic-specific clusters indicated an increase in the severity of complicated lesions compared with atheroma. A 39% overlap in the differential gene expression profiles of human macrophages exposed to ferrylHb and the complicated lesion profiles was uncovered. Among these 547 genes, we found inflammatory, angiogenesis, and iron metabolism gene clusters regulated in macrophages. Innovation and Conclusion: We conclude that oxidation of Hb to ferrylHb contributes to the progression of atherosclerosis via polarizing macrophages into a proatherogenic phenotype. Antioxid. Redox Signal. 35, 917-950.

Cortical bone stem cells modify cardiac inflammation after myocardial infarction by inducing a novel macrophage phenotype

Acute damage to the heart, as in the case of myocardial infarction (MI), triggers a robust inflammatory response to the sterile injury that is part of a complex and highly organized wound-healing process. Cortical bone stem cell (CBSC) therapy after MI has been shown to reduce adverse structural and functional remodeling of the heart after MI in both mouse and swine models. The basis for these CBSC treatment effects on wound healing are unknown. The present experiments show that CBSCs secrete paracrine factors known to have immunomodulatory properties, most notably macrophage colony-stimulating factor (M-CSF) and transforming growth factor-β, but not IL-4. CBSC therapy increased the number of galectin-3+ macrophages, CD4+ T cells, and fibroblasts in the heart while decreasing apoptosis in an in vivo swine model of MI. Macrophages treated with CBSC medium in vitro polarized to a proreparative phenotype are characterized by increased CD206 expression, increased efferocytic ability, increased IL-10, TGF-β, and IL-1RA secretion, and increased mitochondrial respiration. Next generation sequencing revealed a transcriptome significantly different from M2a or M2c macrophage phenotypes. Paracrine factors from CBSC-treated macrophages increased proliferation, decreased α-smooth muscle actin expression, and decreased contraction by fibroblasts in vitro. These data support the idea that CBSCs are modulating the immune response to MI to favor cardiac repair through a unique macrophage polarization that ultimately reduces cell death and alters fibroblast populations that may result in smaller scar size and preserved cardiac geometry and function.NEW & NOTEWORTHY Cortical bone stem cell (CBSC) therapy after myocardial infarction alters the inflammatory response to cardiac injury. We found that cortical bone stem cell therapy induces a unique macrophage phenotype in vitro and can modulate macrophage/fibroblast cross talk.

Study protocol: effect of infection, Modic and inflammation on clinical outcomes in surgery for radiculopathy (EIMICOR)

BACKGROUND

Evidence indicates that inflammatory processes are involved in radicular pain as well as in resorption of herniated disc tissue. Furthermore there are indications that the presence of vertebral end plate pathology (Modic changes; MC) is associated with a negative effect on inflammation. It is hypothesized that in patients with MC, the (possibly bacterial induced) inflammation will be accompanied by pro inflammatory cytokines that worsen the outcome, and that in patients without MC, the inflammation is accompanied by cytokines that induce a resorption process to accelerate recovery.

METHODS

This prospective cohort study will include 160 lumbar and 160 cervical patients (total of 320), which are scheduled for surgery for either a lumbar or cervical herniated disc with ages between 18 and 75. The main and interaction effects of local bacterial infection (culture), inflammatory cells in disc material (immunohistology), MC (MRI), and blood biomarkers indicating inflammation or infection (blood sample evaluation) will be evaluated. Clinical parameters to be evaluated are leg pain on the 11 point NRS pain scale, Oswestry (lumbar spine) or Neck (cervical spine) Disability Index, Global Perceived Recovery, Womac Questionnaire, and medication status, at baseline, and after 6, 16, 26 and 52 weeks.

DISCUSSION

Gaining insight in the aetiology of pain and discomfort in radiculopathy caused by a herniated disc could lead to more effective management of patients. If the type of inflammatory cells shows to be of major influence on the rate of recovery, new immunomodulating treatment strategies can be developed to decrease the duration and intensity of symptoms. Moreover, identifying a beneficial inflammatory response in the disc through a biomarker in blood could lead to early identification of patients whose herniations will resorb spontaneously versus those that require surgery.

TRIAL REGISTRATION

prospectively enrolled at trialregister.nl, ID: NL8464 .

SREBP1-induced fatty acid synthesis depletes macrophages antioxidant defences to promote their alternative activation

Macrophages exhibit a spectrum of activation states ranging from classical to alternative activation¹. Alternatively, activated macrophages are involved in diverse pathophysiological processes such as confining tissue parasites², improving insulin sensitivity³ or promoting an immune-tolerant microenvironment that facilitates tumour growth and metastasis⁴. Recently, the metabolic regulation of macrophage function has come into focus as both the classical and alternative activation programmes require specific regulated metabolic reprogramming⁵. While most of the studies regarding immunometabolism have focussed on the catabolic pathways activated to provide energy, little is known about the anabolic pathways mediating macrophage alternative activation. In this study, we show that the anabolic transcription factor sterol regulatory element binding protein 1 (SREBP1) is activated in response to the canonical T helper 2 cell cytokine interleukin-4 to trigger the de novo lipogenesis (DNL) programme, as a necessary step for macrophage alternative activation. Mechanistically, DNL consumes NADPH, partitioning it away from cellular antioxidant defences and raising reactive oxygen species levels. Reactive oxygen species serves as a second messenger, signalling sufficient DNL, and promoting macrophage alternative activation. The pathophysiological relevance of this mechanism is validated by showing that SREBP1/DNL is essential for macrophage alternative activation in vivo in a helminth infection model.

Placental Macrophages Demonstrate Sex-Specific Response to Intrauterine Inflammation and May Serve as a Marker of Perinatal Neuroinflammation

Preterm birth (PTB) is considered to be one of the most frequent causes of neonatal death. Prompt and effective measures to predict adverse fetal outcome following PTB are urgently needed. Placenta macrophages are a critical immune cell population during pregnancy, phenotypically divided into M1 and M2 subsets. An established mouse model of intrauterine inflammation (IUI) was applied. Placenta (labyrinth) and corresponding fetal brain were harvested within 24 hours post injection (hpi). Flow cytometry, Western blot, real-time qPCR, and regular histology were utilized to examine the cytokines, macrophage polarization, and sex-specificity. Placental exposure to LPS led to significantly reduced labyrinth thickness compared to PBS-exposed controls as early as 3 hpi, accompanied by apoptosis and necrosis. Pro-inflammatory M1 markers, Il-1β, and iNOS, and anti-inflammatory M2 marker Il-10 increased significantly in placentas exposed to IUI. Analysis of flow cytometry revealed that fetal macrophages (Hofbauer cell, HBCs) were mostly M1-like and that maternal inter-labyrinth macrophages (MIM) were M2-like in their features in IUI. Male fetuses displayed significantly decreased M2-like features in HBCs at 3 and 6 hpi, while female fetuses showed significant increase in M2-like features in MIM at 3 and 6 hpi. Furthermore, there was a significant correlation between the frequency of HBCs and corresponding microglial marker expression at 3 and 6 hpi. Placental macrophages demonstrated sex-specific features in response to IUI. Specifically, HBCs may be a potential biomarker for fetal brain injury at preterm birth.

Cholesterol-Ester Transfer Protein Alters M1 and M2 Macrophage Polarization and Worsens Experimental Elastase-Induced Pulmonary Emphysema

Cholesterol-ester transfer protein (CETP) plays a role in atherosclerosis, the inflammatory response to endotoxemia and in experimental and human sepsis. Functional alterations in lipoprotein (LP) metabolism and immune cell populations, including macrophages, occur during sepsis and may be related to comorbidities such as chronic obstructive pulmonary disease (COPD). Macrophages are significantly associated with pulmonary emphysema, and depending on the microenvironment, might exhibit an M1 or M2 phenotype. Macrophages derived from the peritoneum and bone marrow reveal CETP that contributes to its plasma concentration. Here, we evaluated the role of CETP in macrophage polarization and elastase-induced pulmonary emphysema (ELA) in human CETP-expressing transgenic (huCETP) (line 5203, C57BL6/J background) male mice and compared it to their wild type littermates. We showed that bone marrow-derived macrophages from huCETP mice reduce polarization toward the M1 phenotype, but with increased IL-10. Compared to WT, huCETP mice exposed to elastase showed worsened lung function with an increased mean linear intercept (Lm), reflecting airspace enlargement resulting from parenchymal destruction with increased expression of arginase-1 and IL-10, which are M2 markers. The cytokine profile revealed increased IL-6 in plasma and TNF, and IL-10 in bronchoalveolar lavage (BAL), corroborating with the lung immunohistochemistry in the huCETP-ELA group compared to WT-ELA. Elastase treatment in the huCETP group increased VLDL-C and reduced HDL-C. Elastase-induced pulmonary emphysema in huCETP mice promotes lung M2-like phenotype with a deleterious effect in experimental COPD, corroborating the in vitro result in which CETP promoted M2 macrophage polarization. Our results suggest that CETP is associated with inflammatory response and influences the role of macrophages in COPD.

Macrophage-Regulatory T Cell Interactions Promote Type 2 Immune Homeostasis Through Resistin-Like Molecule α

RELMα is a small, secreted protein expressed by type 2 cytokine-activated “M2” macrophages in helminth infection and allergy. At steady state and in response to type 2 cytokines, RELMα is highly expressed by peritoneal macrophages, however, its function in the serosal cavity is unclear. In this study, we generated RELMα TdTomato (Td) reporter/knockout (Rα^Td) mice and investigated RELMα function in IL-4 complex (IL-4c)-induced peritoneal inflammation. We first validated the RELMα^Td/Td transgenic mice and showed that IL-4c injection led to the significant expansion of large peritoneal macrophages that expressed Td but not RELMα protein, while RELMα^+/+ mice expressed RELMα and not Td. Functionally, RELMα^Td/Td mice had increased IL-4 induced peritoneal macrophage responses and splenomegaly compared to RELMα^+/+ mice. Gene expression analysis indicated that RELMα^Td/Td peritoneal macrophages were more proliferative and activated than RELMα^+/+ macrophages, with increased genes associated with T cell responses, growth factor and cytokine signaling, but decreased genes associated with differentiation and maintenance of myeloid cells. We tested the hypothesis that Rα^Td/Td macrophages drive aberrant T cell activation using peritoneal macrophage and T cell co-culture. There were no differences in CD4⁺ T cell effector responses when co-cultured with RELMα^+/+ or RELMα^Td/Td macrophages, however, RELMα^Td/Td macrophages were impaired in their ability to sustain proliferation of FoxP3⁺ regulatory T cells (Treg). Supportive of the in vitro results, immunofluorescent staining of the spleens revealed significantly decreased FoxP3⁺ cells in the RELMα^Td/Td spleens compared to RELMα^+/+ spleens. Taken together, these studies identify a new RELMα regulatory pathway whereby RELMα-expressing macrophages directly sustain Treg proliferation to limit type 2 inflammatory responses.

Single-cell RNA sequencing of freshly isolated bovine milk cells and cultured primary mammary epithelial cells

Bovine mammary function at molecular level is often studied using mammary tissue or primary bovine mammary epithelial cells (pbMECs). However, bulk tissue and primary cells are heterogeneous with respect to cell populations, adding further transcriptional variation in addition to genetic background. Thus, understanding of the variation in gene expression profiles of cell populations and their effect on function are limited. To investigate the mononuclear cell composition in bovine milk, we analyzed a single-cell suspension from a milk sample. Additionally, we harvested cultured pbMECs to characterize gene expression in a homogeneous cell population. Using the Drop-seq technology, we generated single-cell RNA datasets of somatic milk cells and pbMECs. The final datasets after quality control filtering contained 7,119 and 10,549 cells, respectively. The pbMECs formed 14 indefinite clusters displaying intrapopulation heterogeneity, whereas the milk cells formed 14 more distinct clusters. Our datasets constitute a molecular cell atlas that provides a basis for future studies of milk cell composition and gene expression, and could serve as reference datasets for milk cell analysis.

Anti-TNF treatment corrects IFN-γ-dependent proinflammatory signatures in Blau syndrome patient-derived macrophages

BACKGROUND

Blau syndrome (BS) is an autoinflammatory disease associated with mutations in nucleotide-binding oligomerization domain 2. Although treatments with anti-TNF agents have been reported to be effective, the underlying molecular mechanisms remain unclear.

OBJECTIVE

We aimed to elucidate the mechanisms of autoinflammation in patients with BS and to clarify how anti-TNF treatment controls the disease phenotype at the cellular level in clinical samples.

METHODS

Macrophages were differentiated from monocytes of 7 BS patients, and global transcriptional profiles of 5 patients were analyzed with or without IFN-γ stimulation. Macrophages were also generated from BS-specific induced pluripotent stem cells (iPSCs), and their transcriptome was examined for comparison.

RESULTS

Aberrant inflammatory responses were observed upon IFN-γ stimulation in macrophages from untreated BS patients, but not in those from patients treated with anti-TNF. iPSC-derived macrophages carrying a disease-associated mutation also showed IFN-γ-dependent accelerated inflammatory responses. Comparisons of peripheral blood- and iPSC-derived macrophages revealed the upregulation of nuclear factor kappa-light-chain enhancer of activated B cells (NF-κB) targets in unstimulated macrophages as a common feature.

CONCLUSIONS

IFN-γ stimulation is one of the key signals driving aberrant inflammatory responses in BS-associated macrophages. However, long-term treatment with anti-TNF agents ameliorates such abnormalities even in the presence of IFN-γ stimulation. Our data thus suggest that preexposure to TNF or functionally similar cytokines inducing NF-κB-driven proinflammatory signaling during macrophage development is a prerequisite for accelerated inflammatory responses upon IFN-γ stimulation in BS.

Response to Oxidative Burst-Induced Hypoxia Is Associated With Macrophage Inflammatory Profiles as Revealed by Cellular Genome-Wide Association

Background

In mammalian species, hypoxia is a prominent feature of inflammation. The role of hypoxia in regulating macrophage responses via alteration in metabolic pathways is well established. Recently, oxidative burst-induced hypoxia has been shown in murine macrophages after phagocytosis. Despite the available detailed information on the regulation of macrophage function at transcriptomic and epigenomic levels, the association of genetic polymorphism and macrophage function has been less explored. Previously, we have shown that host genetics controls approximately 80% of the variation in an oxidative burst as measured by nitric oxide (NO^-). Further studies revealed two clusters of transcription factors (hypoxia-related and inflammatory-related) are under the genetic control that shapes macrophages’ pro-inflammatory characteristics.

Material and Methods

In the current study, the association between 43,066 autosomal Single Nucleic Polymorphism (SNPs) and the ability of MDMs in production of NO^- in response to E. coli was evaluated in 58 Holstein cows. The positional candidate genes near significant SNPs were selected to perform functional analysis. In addition, the interaction between the positional candidate genes and differentially expressed genes from our previous study was investigated.

Results

Sixty SNPs on 22 chromosomes of the bovine genome were found to be significantly associated with NO^- production of macrophages. The functional genomic analysis showed a significant interaction between positional candidate genes and mitochondria-related differentially expressed genes from the previous study. Further examination showed 7 SNPs located in the vicinity of genes with roles in response to hypoxia, shaping approximately 73% of the observed individual variation in NO^- production by MDM. Regarding the normoxic condition of macrophage culture in this study, it was hypothesized that oxidative burst is responsible for causing hypoxia at the cellular level.

Conclusion

The results suggest that the genetic polymorphism via regulation of response to hypoxia is a candidate step that perhaps shapes macrophage functional characteristics in the pathway of phagocytosis leading to oxidative burst, hypoxia, cellular response to hypoxia and finally the pro-inflammatory responses. Since all cells in one individual carry the same alleles, the effect of genetic predisposition of sensitivity to hypoxia will likely be notable on the clinical outcome to a broad range of host-pathogen interactions.

The Long Non-coding RNA NEAT1/miR-224-5p/IL-33 Axis Modulates Macrophage M2a Polarization and A1 Astrocyte Activation

To identify potential regulators and investigate the molecular mechanism of macrophage polarization affecting astrocyte activation from the perspective of non-coding RNA regulation, we isolated mouse bone marrow mononuclear cells (BMMNCs)-induced macrophages toward M1 or M2a polarization. Long non-coding RNA NEAT1 and IL-33 expression levels were significantly upregulated in M2a macrophages; NEAT1 knockdown in M2a macrophages markedly reduced the protein levels of IL-33 and M2a markers, IL-4 and IL-13 concentrations, and the bacterial killing capacity of M2a macrophages. NEAT1 acted as a competing endogenous RNA (ceRNA) to regulate IL-33 expression by sponging miR-224-5p in M2a macrophages; NEAT1 knockdown upregulated miR-224-5p expression, while miR-224-5p inhibition increased the protein content and concentration of IL-33. miR-224-5p inhibition exerted the opposite effects on the protein levels of IL-33 and M2a markers, IL-4 and IL-13 concentrations, and the bacterial killing capacity of M2a macrophages compared to NEAT1 knockdown; the effects of NEAT1 knockdown were significantly reversed by miR-224-5p inhibition. M2a macrophage conditioned medium (CM) significantly suppressed the activation of A1 astrocytes. NEAT1 knockdown M2a macrophage CM led to enhanced A1 astrocyte activation while miR-224-5p-silenced M2a macrophage CM led to a blockade of A1 astrocyte activation; the effects of NEAT1 knockdown M2a macrophage CM on A1 astrocyte activation were significantly reversed by miR-224-5p inhibition in M2a macrophages. The NEAT1/miR-224-5p/IL-33 axis modulates macrophage M2a polarization, therefore affecting A1 astrocyte activation.

Sustained IL-4 priming of macrophages enhances the inflammatory response to TLR7/8 ligand R848

Macrophages (Mϕ) are highly plastic, and can acquire a variety of functional phenotypes depending on the presence of different stimuli in their local environment. Mφ stimulated by interleukin (IL)-4 induce an alternative activation state and function as anti-inflammatory cells and promote tissue repair. However, there is overwhelming evidence that IL-4 can play a role in promoting inflammation. In asthma and allergic inflammation, IL-4 mediates proinflammatory responses that lead to tissue damage. Thus the effect of IL-4 on the outcome of the immune responses is greatly influenced by other cofactors and cytokines present in the microenvironment. R848 (resiquimod), a TLR7/8 agonist is a novel vaccine adjuvant, triggering a strong Th1-skewed response but its efficacy as a vaccine adjuvant shows variable results. It is not currently known whether the presence of IL-4 can dampen or enhance immunity in response to TLR7 agonists. In the present study, we sought to investigate the impact of IL-4-induced Mφ polarization on the outcome of R848 stimulation. The activation marker expression and production of cytokines were measured in murine spleen-derived Mφ. Protein expression levels of innate recognition molecules and transcription factors involved, including retinoic-acid inducible gene I, mitochondrial antiviral signaling protein, stimulator of interferon genes (STING), and IFN regulatory factors were evaluated in activated Mφ. These play a crucial role in the control of viral replication and optimal CD8+ T cell priming. We report that sustained priming with IL-4 alone promotes an antiviral response in Mφ, and enhances proinflammatory responses to R848 treatment. This highlights the need for better understanding of IL-4 proinflammatory functions and its potential use as a broad-acting antiviral in combination with R848 may be used in combination with other therapies to target the innate arm of immunity against emerging infections.

The Role of Macrophages in the Pathogenesis of SARS-CoV-2-Associated Acute Respiratory Distress Syndrome

Macrophages are cells that mediate both innate and adaptive immunity reactions, playing a major role in both physiological and pathological processes. Systemic SARS-CoV-2-associated complications include acute respiratory distress syndrome (ARDS), disseminated intravascular coagulation syndrome, edema, and pneumonia. These are predominantly effects of massive macrophage activation that collectively can be defined as macrophage activation syndrome. In this review we focus on the role of macrophages in COVID-19, as pathogenesis of the new coronavirus infection, especially in cases complicated by ARDS, largely depends on macrophage phenotypes and functionalities. We describe participation of monocytes, monocyte-derived and resident lung macrophages in SARS-CoV-2-associated ARDS and discuss possible utility of cell therapies for its treatment, notably the use of reprogrammed macrophages with stable pro- or anti-inflammatory phenotypes.

Macrophages with reduced expressions of classical M1 and M2 surface markers in human bronchoalveolar lavage fluid exhibit pro-inflammatory gene signatures

The classical M1/M2 polarity of macrophages may not be applicable to inflammatory lung diseases including chronic obstructive pulmonary disease (COPD) due to the complex microenvironment in lungs and the plasticity of macrophages. We examined macrophage sub-phenotypes in bronchoalveolar lavage (BAL) fluid in 25 participants with CD40 (a M1 marker) and CD163 (a M2 marker). Of these, we performed RNA-sequencing on each subtype in 10 patients using the Illumina NextSeq 500. Approximately 25% of the macrophages did not harbor classical M1 or M2 surface markers (double negative, DN), and these cells were significantly enriched in COPD patients compared with non-COPD patients (46.7% vs. 14.5%, p < 0.001). 1886 genes were differentially expressed in the DN subtype compared with  all other subtypes at a 10% false discovery rate. The 602 up-regulated genes included 15 mitochondrial genes and were enriched in 86 gene ontology (GO) biological processes including inflammatory responses. Modules associated with cellular functions including oxidative phosphorylation were significantly down-regulated in the DN subtype. Macrophages in the human BAL fluid, which were negative for both M1/M2 surface markers, harbored a gene signature that was pro-inflammatory and suggested dysfunction in cellular homeostasis. These macrophages may contribute to the pathogenesis and manifestations of inflammatory lung diseases such as COPD.

Macrophage Polarization in Cardiac Tissue Repair Following Myocardial Infarction

Cardiovascular disease is the leading cause of mortality and morbidity around the globe, creating a substantial socio-economic burden as a result. Myocardial infarction is a significant contributor to the detrimental impact of cardiovascular disease. The death of cardiomyocytes following myocardial infarction causes an immune response which leads to further destruction of tissue, and subsequently, results in the formation of non-contractile scar tissue. Macrophages have been recognized as important regulators and participants of inflammation and fibrosis following myocardial infarction. Macrophages are generally classified into two distinct groups, namely, classically activated, or M1 macrophages, and alternatively activated, or M2 macrophages. The phenotypic profile of cardiac macrophages, however, is much more diverse and should not be reduced to these two subsets. In this review, we describe the phenotypes and functions of macrophages which are present in the healthy, as well as the infarcted heart, and analyze them with respect to M1 and M2 polarization states. Furthermore, we discuss therapeutic strategies which utilize macrophage polarization towards an anti-inflammatory or reparative phenotype for the treatment of myocardial infarction.

Polyphenols and Cannabidiol Modulate Transcriptional Regulation of Th1/Th2 Inflammatory Genes Related to Canine Atopic Dermatitis

Canine atopic dermatitis (AD) is a multifactorial allergic disease associated with immune and abnormal skin barrier dysfunction and it is one of the primary causes of pruritus. Using a novel in vitro model of AD, here we tried to revert the alteration of transcriptional regulation of AD canine key genes testing a nutraceutical mixture containing flavonoids, stilbene, and cannabinoids, which are already well-known for their applications within dermatology diseases. The nutraceutical mixture induced in inflamed cells a significant downregulation (p < 0.05) of the gene expression of ccl2, ccl17, and tslp in keratinocytes and of ccl2, ccl17, and il31ra in monocytes. Consistent with the observed alterations of tslp, ccl2, ccl17, and il31ra messenger RNA (mRNA) levels, a significant increase (p < 0.05) of DNA methylation at specific CpG sites on the gene regulatory regions was found. These results lay the foundation for the use of these natural bioactives in veterinary medicine and provide a model for deeper understanding of their mechanisms of action, with potential translation to human research.

A data-driven computational model enables integrative and mechanistic characterization of dynamic macrophage polarization

Macrophages are highly plastic immune cells that dynamically integrate microenvironmental signals to shape their own functional phenotypes, a process known as polarization. Here we develop a large-scale mechanistic computational model that for the first time enables a systems-level characterization, from quantitative, temporal, dose-dependent, and single-cell perspectives, of macrophage polarization driven by a complex multi-pathway signaling network. The model was extensively calibrated and validated against literature and focused on in-house experimental data. Using the model, we generated dynamic phenotype maps in response to numerous combinations of polarizing signals; we also probed into an in silico population of model-based macrophages to examine the impact of polarization continuum at the single-cell level. Additionally, we analyzed the model under an in vitro condition of peripheral arterial disease to evaluate strategies that can potentially induce therapeutic macrophage repolarization. Our model is a key step toward the future development of a network-centric, comprehensive "virtual macrophage" simulation platform.

NOX2-Derived Reactive Oxygen Species in Cancer

The formation of reactive oxygen species (ROS) by the myeloid cell NADPH oxidase NOX2 is critical for the destruction of engulfed microorganisms. However, recent studies imply that ROS, formed by NOX2⁺ myeloid cells in the malignant microenvironment, exert multiple actions of relevance to the growth and spread of neoplastic cells. By generating ROS, tumor-infiltrating myeloid cells and NOX2⁺ leukemic myeloid cells may thus (i) compromise the function and viability of adjacent cytotoxic lymphocytes, including natural killer (NK) cells and T cells, (ii) oxidize DNA to trigger cancer-promoting somatic mutations, and (iii) affect the redox balance in cancer cells to control their proliferation and survival. Here, we discuss the impact of NOX2-derived ROS for tumorigenesis, tumor progression, regulation of antitumor immunity, and metastasis. We propose that NOX2 may be a targetable immune checkpoint in cancer.

Ror β expression in activated macrophages and dental pulp stem cells

AIM

To assess the expression of Retinoic acid-related orphan receptor beta (Ror β) in human inflamed dental pulp stem cells (hI-DPSCs) and during macrophage phenotypic conversion.

METHODOLOGY

Commercially procured THP-1 monocytes conversion to macrophages was judged by their morphology, the percentage of adherent cells and the expression of CD-14 surface marker. THP-1 macrophage cell viability following LPS, IFN-γ/IL-4, IL-13 stimulus was evaluated at 24 and 48h. The phenotypic conversion of macrophages to M1 and M2 was confirmed by flow cytometry and Western blot analysis. Cytokine release following polarization was estimated by the BD cytokine flex kit. The expression of Ror β in THP-1 macrophages and hI-DPSCs following LPS, IFN-γ/IL-4, IL-13 stimulus was assessed by Western blot analysis. Statistical significance was analysed using one-way Anova followed by Tukey's Post hoc test.

RESULTS

THP-1 monocytes pretreated with PMA (100 ng mL^-1 ) for 48 h followed by culturing in PMA-free media for another 48 h yielded cells with morphological characteristics similar to macrophages with a high percentage of adherence capability and CD-14 expression. Macrophages treated with LPS 100 ng mL^-1 and IFN-γ 20 ng mL^-1 or IL-4 20 ng mL^-1 had high expression of the respective M1 and M2 CD markers in flow cytometry and Western blot analysis. Cytokine release studies demonstrated the expression of IL-1β, TNF-α and IL-10 in the M1-polarized macrophages (P < 0.01), whilst TGF- β levels were seen in the M1 and M2-polarized macrophages. Ror β expression was upregulated when macrophages and hI-DPSCs were treated with anti-inflammatory cytokines.

CONCLUSION

Ror β was expressed in THP-1 macrophages and hI-DPSCs during their resting stage. Upregulated expression of Ror β occurred following an anti-inflammatory stimulus.

Abundance of Non-Polarized Lung Macrophages with Poor Phagocytic Function in Chronic Obstructive Pulmonary Disease (COPD)

Lung macrophages are the key immune effector cells in the pathogenesis of Chronic Obstructive Pulmonary Disease (COPD). Several studies have shown an increase in their numbers in bronchoalveolar lavage fluid (BAL) of subjects with COPD compared to controls, suggesting a pathogenic role in disease initiation and progression. Although reduced lung macrophage phagocytic ability has been previously shown in COPD, the relationship between lung macrophages' phenotypic characteristics and functional properties in COPD is still unclear. (1) Methods: Macrophages harvested from bronchoalveolar lavage (BAL) fluid of subjects with and without COPD (GOLD grades, I-III) were immuno-phenotyped, and their function and gene expression profiles were assessed using targeted assays. (2) Results: BAL macrophages from 18 COPD and 10 (non-COPD) control subjects were evaluated. The majority of macrophages from COPD subjects were non-polarized (negative for both M1 and M2 markers; 77.9%) in contrast to controls (23.9%; p < 0.001). The percentages of these non-polarized macrophages strongly correlated with the severity of COPD (p = 0.006) and current smoking status (p = 0.008). Non-polarized macrophages demonstrated poor phagocytic function in both the control (p = 0.02) and COPD (p < 0.001) subjects. Non-polarized macrophages demonstrated impaired ability to phagocytose Staphylococcus aureus (p < 0.001). They also demonstrated reduced gene expression for CD163, CD40, CCL13 and C1QA&B, which are involved in pathogen recognition and processing and showed an increased gene expression for CXCR4, RAF1, amphiregulin and MAP3K5, which are all involved in promoting the inflammatory response. (3) Conclusions: COPD is associated with an abundance of non-polarized airway macrophages that is related to the severity of COPD. These non-polarized macrophages are predominantly responsible for the poor phagocytic capacity of lung macrophages in COPD, having reduced capacity for pathogen recognition and processing. This could be a key risk factor for COPD exacerbation and could contribute to disease progression.

Single-Cell Transcriptome Analysis Profile of Meniscal Tissue Macrophages in Human Osteoarthritis

Osteoarthritis (OA) has long been considered as a degenerative disease, but growing evidence suggests that inflammation plays a vital role in its pathogenesis. Unlike rheumatoid arthritis and other autoimmune diseases, inflammation in OA is chronic and, in relatively low grade, mainly mediated by the innate immune system, especially macrophages. However, due to its low abundance, there is a lack of systematic studies on macrophages in the OA condition. Here, we have used single-cell RNA sequencing analysis to gain insight into the heterogeneity and functional specialization of human knee macrophages. We also compared the gene expression profiles of macrophages in healthy people and OA patients and found the characteristic changes of special macrophages in the OA knee. We believe that this in-depth understanding of the basis of OA inflammation will bring hope for the development of new therapies.

M1hot tumor-associated macrophages boost tissue-resident memory T cells infiltration and survival in human lung cancer

BACKGROUND

The role of tumor-associated macrophages (TAMs) in determining the outcome between the antitumor effects of the adaptive immune system and the tumor's anti-immunity stratagems, is controversial. Macrophages modulate their activities and phenotypes by integration of signals in the tumor microenvironment. Depending on how macrophages are activated, they may adopt so-called M1-like, antitumor or M2-like, protumor profiles. In many solid tumors, a dominance of M2-like macrophages is associated with poor outcomes but in some tumor types, strong M1-like profiles are linked to better outcomes. We aimed to investigate the interrelationship of these TAM populations to establish how they modulate the efficacy of the adaptive immune system in early lung cancer.

METHODS

Macrophages from matched lung (non-tumor-associated macrophages (NTAMs)) and tumor samples (TAMs) from resected lung cancers were assessed by bulk and single-cell transcriptomic analysis. Protein expression of genes characteristic of M1-like (chemokine (C-X-C motif) ligand 9) or M2-like (matrix metallopeptidase 12) functions was confirmed by confocal microscopy. Immunohistochemistry related the distribution of TAM transcriptomic signatures to density of CD8+ tissue-resident memory T cells (TRM) in tumors and survival data from an independent cohort of 393 patients with lung cancer.

RESULTS

TAMs have significantly different transcriptomic profiles from NTAMs with >1000 differentially expressed genes. TAMs displayed a strong M2-like signature with no significant variation between patients. However, single-cell RNA-sequencing supported by immuno-stained cells revealed that additionally, in 25% of patients the M2-like TAMs also co-expressed a strong/hot M1-like signature (M1hot). Importantly, there was a strong association between the density of M1hot TAMs and TRM cells in tumors that was in turn linked to better survival. Our data suggest a mechanism by which M1hot TAMs may recruit TRM cells via CXCL9 expression and sustain them by making available more of the essential fatty acids on which TRM depend.

CONCLUSIONS

We showed that in early lung cancer, expression of M1-like and M2-like gene signatures are not mutually exclusive since the same TAMs can simultaneously display both gene-expression profiles. The presence of M1hot TAMs was associated with a strong TRM tumor-infiltrate and better outcomes. Thus, therapeutic approaches to re-program TAMs to an M1hot phenotype are likely to augment the adaptive antitumor responses.

Macrophage Modification Strategies for Efficient Cell Therapy

Macrophages, important cells of innate immunity, are known for their phagocytic activity, capability for antigen presentation, and flexible phenotypes. Macrophages are found in all tissues and therefore represent an attractive therapeutic target for the treatment of diseases of various etiology. Genetic programming of macrophages is an important issue of modern molecular and cellular medicine. The controllable activation of macrophages towards desirable phenotypes in vivo and in vitro will provide effective treatments for a number of inflammatory and proliferative diseases. This review is focused on the methods for specific alteration of gene expression in macrophages, including the controllable promotion of the desired M1 (pro-inflammatory) or M2 (anti-inflammatory) phenotypes in certain pathologies or model systems. Here we review the strategies of target selection, the methods of vector delivery, and the gene editing approaches used for modification of macrophages.

An association between mitochondria and microglia effector function. What do we think we know?

While resident innate immune cells of the central nervous system, the microglia, represent a cell population unique in origin, microenvironment, and longevity, they assume many properties displayed by peripheral macrophages. One prominent shared property is the ability to undergo a metabolic switch towards glycolysis and away from oxidative phosphorylation (OXPHOS) upon activation by the pro-inflammatory stimuli lipopolysaccharide. This shift serves to meet specific cellular demands and allows for cell survival, similar to the Warburg effect demonstrated in cancer cells. In contrast, normal survelliance phenotype or stimulation to a non-proinflammatory phenotype relies primarily on OXPHOS and fatty acid oxidation. Thus, mitochondria appear to function as a pivotal signaling platform linking energy metabolism and macrophage polarization upon activation. These unique shifts in cell bioenergetics in response to different stimuli are essential for proper effector responses at sites of infection, inflammation, or injury. Here we present a summary of recent developments as to how these dynamics characterized in peripheral macrophages are displayed in microglia. The new insights provided by an increased understanding of metabolic reprogramming in macrophages may allow for translation to the CNS and a better understanding of microglia heterogeneity, regulation, and function.