Colony stimulating factor-1 receptor signaling networks inhibit mouse macrophage inflammatory responses by induction of microRNA-21

Defining mesenchymal stem/stromal cell-induced myeloid-derived suppressor cells using single-cell transcriptomics

Mesenchymal stem/stromal cells (MSCs) modulate the immune response through interactions with innate immune cells. We previously demonstrated that MSCs alleviate ocular autoimmune inflammation by directing bone marrow cell differentiation from pro-inflammatory CD11bhiLy6ChiLy6Glo cells into immunosuppressive CD11bmidLy6CmidLy6Glo cells. Herein, we analyzed MSC-induced CD11bmidLy6Cmid cells using single-cell RNA sequencing and compared them with CD11bhiLy6Chi cells. Our investigation revealed seven distinct immune cell types including myeloid-derived suppressor cells (MDSCs) in the CD11bmidLy6Cmid cells, while CD11bhiLy6Chi cells included mostly monocytes/macrophages with a small cluster of neutrophils. These MSC-induced MDSCs highly expressed Retnlg, Cxcl3, Cxcl2, Mmp8, Cd14, and Csf1r as well as Arg1. Comparative analyses of CSF-1RhiCD11bmidLy6Cmid and CSF-1RloCD11bmidLy6Cmid cells demonstrated that the former had a homogeneous monocyte morphology and produced elevated levels of interleukin-10. Functionally, these CSF-1RhiCD11bmidLy6Cmid cells, compared with the CSF-1RloCD11bmidLy6Cmid cells, inhibited CD4+ T cell proliferation and promoted CD4+CD25+Foxp3+ Treg expansion in culture and in a mouse model of experimental autoimmune uveoretinitis. Resistin-like molecule (RELM)-γ encoded by Retnlg, one of the highly upregulated genes in MSC-induced MDSCs, had no direct effects on T cell proliferation, Treg expansion, or splenocyte activation. Together, our study revealed a distinct transcriptional profile of MSC-induced MDSCs and identified CSF-1R as a key cell-surface marker for detection and therapeutic enrichment of MDSCs.

Macrophages in cardiovascular diseases: molecular mechanisms and therapeutic targets

The immune response holds a pivotal role in cardiovascular disease development. As multifunctional cells of the innate immune system, macrophages play an essential role in initial inflammatory response that occurs following cardiovascular injury, thereby inducing subsequent damage while also facilitating recovery. Meanwhile, the diverse phenotypes and phenotypic alterations of macrophages strongly associate with distinct types and severity of cardiovascular diseases, including coronary heart disease, valvular disease, myocarditis, cardiomyopathy, heart failure, atherosclerosis and aneurysm, which underscores the importance of investigating macrophage regulatory mechanisms within the context of specific diseases. Besides, recent strides in single-cell sequencing technologies have revealed macrophage heterogeneity, cell-cell interactions, and downstream mechanisms of therapeutic targets at a higher resolution, which brings new perspectives into macrophage-mediated mechanisms and potential therapeutic targets in cardiovascular diseases. Remarkably, myocardial fibrosis, a prevalent characteristic in most cardiac diseases, remains a formidable clinical challenge, necessitating a profound investigation into the impact of macrophages on myocardial fibrosis within the context of cardiac diseases. In this review, we systematically summarize the diverse phenotypic and functional plasticity of macrophages in regulatory mechanisms of cardiovascular diseases and unprecedented insights introduced by single-cell sequencing technologies, with a focus on different causes and characteristics of diseases, especially the relationship between inflammation and fibrosis in cardiac diseases (myocardial infarction, pressure overload, myocarditis, dilated cardiomyopathy, diabetic cardiomyopathy and cardiac aging) and the relationship between inflammation and vascular injury in vascular diseases (atherosclerosis and aneurysm). Finally, we also highlight the preclinical/clinical macrophage targeting strategies and translational implications.

Low-Intensity Pulsed Ultrasound: A Physical Stimulus with Immunomodulatory and Anti-inflammatory Potential

Ultrasound has expanded into the therapeutic field as a medical imaging and diagnostic technique. Low-intensity pulsed ultrasound (LIPUS) is a kind of therapeutic ultrasound that plays a vital role in promoting fracture healing, wound repair, immunomodulation, and reducing inflammation. Its anti-inflammatory effects are manifested by decreased pro-inflammatory cytokines and chemokines, accelerated regression of immune cell invasion, and accelerated damage repair. Although the anti-inflammatory mechanism of LIPUS is not very clear, many in vitro and in vivo studies have shown that LIPUS may play its anti-inflammatory role by activating signaling pathways such as integrin/Focal adhesion kinase (FAK)/Phosphatidylinositol 3-kinase (PI3K)/Serine threonine kinase (Akt), Vascular endothelial growth factor (VEGF)/endothelial nitric oxide synthase (eNOS), or inhibiting signaling pathways such as Toll-like receptors (TLRs)/Nuclear factor kappa-B (NF-κB) and p38-Mitogen-activated protein kinase (MAPK). As a non-invasive physical therapy, the anti-inflammatory and immunomodulatory effects of LIPUS deserve further exploration.

Drug repurposing screen identifies novel anti-inflammatory activity of sunitinib in macrophages

Inflammation is a driver of human disease and an unmet clinical need exists for new anti-inflammatory medicines. As a key cell type in both acute and chronic inflammatory pathologies, macrophages are an appealing therapeutic target for anti-inflammatory medicines. Drug repurposing - the use of existing medicines for novel indications - is an attractive strategy for the identification of new anti-inflammatory medicines with reduced development costs and lower failure rates than de novo drug discovery. In this study, FDA-approved medicines were screened in a murine macrophage NF-κB reporter cell line to identify potential anti-inflammatory drug repurposing candidates. The multi-tyrosine kinase inhibitor sunitinib was found to be a potent inhibitor of NF-κB activity and suppressor of inflammatory mediator production in murine bone marrow derived macrophages. Furthermore, oral treatment with sunitinib in mice was found to reduce TNFα production, inflammatory gene expression and organ damage in a model of endotoxemia via inhibition of NF-κB. Finally, we revealed sunitinib to have immunomodulatory effects in a model of chronic cardiovascular inflammation by reducing circulating TNFα. This study validates drug repurposing as a strategy for the identification of novel anti-inflammatory medicines and highlights sunitinib as a potential drug repurposing candidate for inflammatory disease via inhibition of NF-κB signalling.

MAFB shapes human monocyte-derived macrophage response to SARS-CoV-2 and controls severe COVID-19 biomarker expression

Monocyte-derived macrophages, the major source of pathogenic macrophages in COVID-19, are oppositely instructed by macrophage CSF (M-CSF) or granulocyte macrophage CSF (GM-CSF), which promote the generation of antiinflammatory/immunosuppressive MAFB+ (M-MØ) or proinflammatory macrophages (GM-MØ), respectively. The transcriptional profile of prevailing macrophage subsets in severe COVID-19 led us to hypothesize that MAFB shapes the transcriptome of pulmonary macrophages driving severe COVID-19 pathogenesis. We have now assessed the role of MAFB in the response of monocyte-derived macrophages to SARS-CoV-2 through genetic and pharmacological approaches, and we demonstrate that MAFB regulated the expression of the genes that define pulmonary pathogenic macrophages in severe COVID-19. Indeed, SARS-CoV-2 potentiated the expression of MAFB and MAFB-regulated genes in M-MØ and GM-MØ, where MAFB upregulated the expression of profibrotic and neutrophil-attracting factors. Thus, MAFB determines the transcriptome and functions of the monocyte-derived macrophage subsets that underlie pulmonary pathogenesis in severe COVID-19 and controls the expression of potentially useful biomarkers for COVID-19 severity.

Macrophage polarization in spinal cord injury repair and the possible role of microRNAs: A review

The prevention, treatment, and rehabilitation of spinal cord injury (SCI) have always posed significant medical challenges. After mechanical injury, disturbances in microcirculation, edema formation, and the generation of free radicals lead to additional damage, impeding effective repair processes and potentially exacerbating further dysfunction. In this context, inflammatory responses, especially the activation of macrophages, play a pivotal role. Different phenotypes of macrophages have distinct effects on inflammation. Activation of classical macrophage cells (M1) promotes inflammation, while activation of alternative macrophage cells (M2) inhibits inflammation. The polarization of macrophages is crucial for disease healing. A non-coding RNA, known as microRNA (miRNA), governs the polarization of macrophages, thereby reducing inflammation following SCI and facilitating functional recovery. This study elucidates the inflammatory response to SCI, focusing on the infiltration of immune cells, specifically macrophages. It examines their phenotype and provides an explanation of their polarization mechanisms. Finally, this paper introduces several well-known miRNAs that contribute to macrophage polarization following SCI, including miR-155, miR-130a, and miR-27 for M1 polarization, as well as miR-22, miR-146a, miR-21, miR-124, miR-223, miR-93, miR-132, and miR-34a for M2 polarization. The emphasis is placed on their potential therapeutic role in SCI by modulating macrophage polarization, as well as the present developments and obstacles of miRNA clinical therapy.

Differential effects of microRNAs miR-21, miR-99 and miR-145 on lung regeneration and inflammation during recovery from influenza pneumonia

In a mouse model of influenza pneumonia, we previously documented that proliferating alveolar type II (AT2) cells are the major stem cells involved in early lung recovery. Profiling of microRNAs revealed significant dysregulation of specific ones, including miR-21 and miR-99a. Moreover, miR-145 is known to exhibit antagonism to miR-21. This follow-up study investigated the roles of microRNAs miR-21, miR-99a, and miR-145 in the murine pulmonary regenerative process and inflammation during influenza pneumonia. Inhibition of miR-21 resulted in severe morbidity, and in significantly decreased proliferating AT2 cells due to impaired transition from innate to adaptive immune responses. Knockdown of miR-99a culminated in moderate morbidity, with a significant increase in proliferating AT2 cells that may be linked to PTEN downregulation. In contrast, miR-145 antagonism did not impact morbidity nor the proliferating AT2 cell population, and was associated with downregulation of TNF-alpha, IL1-beta, YM1, and LY6G. Hence, a complex interplay exists between expression of specific miRNAs, lung regeneration, and inflammation during recovery from influenza pneumonia. Inhibition of miR-21 and miR-99a (but not miR-145) can lead to deleterious cellular and molecular effects on pulmonary repair and inflammatory processes during influenza pneumonia.

Differential regulation of microglial states by colony stimulating factors

Recent studies have emphasized the role of microglia in the progression of many neurodegenerative diseases. The colony stimulating factors, CSF-1 (M-CSF), granulocyte-macrophage CSF (GM-CSF) and granulocyte CSF (G-CSF) regulate microglia through different cognate receptors. While the receptors for GM-CSF (GM-CSFR) and G-CSF (G-CSFR) are specific for their ligands, CSF-1 shares its receptor, the CSF-1 receptor-tyrosine kinase (CSF-1R), with interleukin-34 (IL-34). All four cytokines are expressed locally in the CNS. Activation of the CSF-1R in macrophages is anti-inflammatory. In contrast, the actions of GM-CSF and G-CSF elicit different activated states. We here review the roles of each of these cytokines in the CNS and how they contribute to the development of disease in a mouse model of CSF-1R-related leukodystrophy. Understanding their roles in this model may illuminate their contribution to the development or exacerbation of other neurodegenerative diseases.

Artificially induced in situ macrophage polarization: An emerging cellular therapy for immuno-inflammatory diseases

Macrophages are the mature form of monocytes that have high plasticity and can shift from one phenotype to another by the process of macrophage polarization. Macrophage has several vital pharmacological tasks like eliminating microorganism invasion, clearing dead cells, causing inflammation, repairing damaged tissues, etc. The function of macrophages is based on their phenotype. M1 macrophages are mostly responsible for the body's immune responses and M2 macrophages have healing properties. Inappropriate activation of any one of the phenotypes often leads to ROS-induced tissue damage and affects wound healing and angiogenesis. Therefore, maintaining tissue macrophage homeostasis is necessary. Studies are being done to find techniques for macrophage polarization. But, the process of macrophage polarization is very complex as it involves multiple signalling pathways involving innate immunity. Thus, identifying the right pathways for macrophage polarization is essential to apply the polarizing technique for the treatment of various inflammatory diseases where macrophage physiology influences the disease pathology. In this review, we highlighted the various techniques so far used to change macrophage plasticity. We believe that soon macrophage targeting therapeutics will hit the market for the management of inflammatory disease. Hence this review will help macrophage researchers choose suitable methods and materials/agents to polarize macrophages artificially in various disease models.

MiR-34a targets SIRT1 to reduce p53 deacetylation and promote sevoflurane inhalation anesthesia-induced neuronal autophagy and apoptosis in neonatal mice

This study is to investigate the function of miR-34a and interactions between miR-34a, SIRT1, and p53 in sevoflurane-induced neuronal apoptosis and autophagy in neonatal mice. A mouse model was established by inhalation anesthesia with sevoflurane and injected with genetic reagents, followed by tests of learning and memory abilities and histological staining of the hippocampus. CCK-8 and AnnexinV/PI staining respectively measured the survival and apoptosis rates of primary hippocampal neurons cultured with sevoflurane. The expression levels of miR-34a, SIRT1, p53, Ac-p53, and autophagy- or apoptosis-related proteins were measured. Sevoflurane impaired the learning and memory abilities of mice, increased TUNEL-positive cells in their hippocampus, and hindered the survival of hippocampal neurons. Sevoflurane increased miR-34a, Bax, cleaved caspase-3, and the ratio of LC3-II/LC3-I and reduced SIRT1 and p62. MiR-34a overexpression promoted sevoflurane-induced neural damage, whereas SIRT1 inhibition or p53 upregulation counteracted the neuroprotection of miR-34a knockdown. SIRT1 was a target of miR-34a and promoted p53 deacetylation. MiR-34a promotes sevoflurane-stimulated neuronal apoptosis and autophagy in neonatal mice by inhibiting SIRT1 expression and subsequent p53 deacetylation.

Supramolecular immunotherapy on diversiform immune cells

Supramolecular immunotherapy employs supramolecular materials to stimulate the immune system for inhibiting tumor cell growth and metastasis, reducing the cancer recurrence rate, and improving the quality of the patient's life. Additionally, it can lessen patient suffering and the deterioration of their illness, as well as increase their survival rate. This paper will outline the fundamentals of tumor immunotherapy based on supramolecular materials as well as its current state of development and potential applications. To be more specific, we will first introduce the basic principles of supramolecular immunotherapy, including the processes, advantages and limitations of immunotherapy, the construction of supramolecular material structures, and its benefits in treatment. Second, considering the targeting of supramolecular drugs to immune cells, we comprehensively discuss the unique advantages of applying supramolecular drugs with different types of immune cells in tumor immunotherapy. The current research advances in supramolecular immunotherapy, including laboratory research and clinical applications, are also described in detail. Finally, we reveal the tremendous promise of supramolecular materials in tumor immunotherapy, as well as discuss the opportunities and challenges that may be faced in future development.

Supramolecular Biomaterials for Cancer Immunotherapy

Cancer immunotherapy has achieved tremendous successful clinical results and obtained historic victories in tumor treatments. However, great limitations associated with feeble immune responses and serious adverse effects still cannot be neglected due to the complicated multifactorial etiology and pathologic microenvironment in tumors. The rapid development of nanomedical science and material science has facilitated the advanced progress of engineering biomaterials to tackle critical issues. The supramolecular biomaterials with flexible and modular structures have exhibited unparalleled advantages of high cargo-loading efficiency, excellent biocompatibility, and diversiform immunomodulatory activity, thereby providing a powerful weapon for cancer immunotherapy. In past decades, supramolecular biomaterials were extensively explored as versatile delivery platforms for immunotherapeutic agents or designed to interact with the key moleculars in immune system in a precise and controllable manner. In this review, we focused on the crucial role of supramolecular biomaterials in the modulation of pivotal steps during tumor immunotherapy, including antigen delivery and presentation, T lymphocyte activation, tumor-associated macrophage elimination and repolarization, and myeloid-derived suppressor cell depletion. Based on extensive research, we explored the current limitations and development prospects of supramolecular biomaterials in cancer immunotherapy.

Innate immune cellular therapeutics in transplantation

Successful organ transplantation provides an opportunity to extend the lives of patients with end-stage organ failure. Selectively suppressing the donor-specific alloimmune response, however, remains challenging without the continuous use of non-specific immunosuppressive medications, which have multiple adverse effects including elevated risks of infection, chronic kidney injury, cardiovascular disease, and cancer. Efforts to promote allograft tolerance have focused on manipulating the adaptive immune response, but long-term allograft survival rates remain disappointing. In recent years, the innate immune system has become an attractive therapeutic target for the prevention and treatment of transplant organ rejection. Indeed, contemporary studies demonstrate that innate immune cells participate in both the initial alloimmune response and chronic allograft rejection and undergo non-permanent functional reprogramming in a phenomenon termed "trained immunity." Several types of innate immune cells are currently under investigation as potential therapeutics in transplantation, including myeloid-derived suppressor cells, dendritic cells, regulatory macrophages, natural killer cells, and innate lymphoid cells. In this review, we discuss the features and functions of these cell types, with a focus on their role in the alloimmune response. We examine their potential application as therapeutics to prevent or treat allograft rejection, as well as challenges in their clinical translation and future directions for investigation.

Inhibition of LXR controls the polarization of human inflammatory macrophages through upregulation of MAFB

Monocyte-derived macrophages contribute to pathogenesis in inflammatory diseases and their effector functions greatly depend on the prevailing extracellular milieu. Whereas M-CSF primes macrophages for acquisition of an anti-inflammatory profile, GM-CSF drives the generation of T cell-stimulatory and pro-inflammatory macrophages. Liver X Receptors (LXRα and LXRβ) are nuclear receptors that control cholesterol metabolism and regulate differentiation of tissue-resident macrophages. Macrophages from rheumatoid arthritis and other inflammatory pathologies exhibit an enriched LXR pathway, and recent reports have shown that LXR activation raises pro-inflammatory effects and impairs the acquisition of the anti-Inflammatory profile of M-CSF-dependent monocyte-derived macrophages (M-MØ). We now report that LXR inhibition prompts the acquisition of an anti-inflammatory gene and functional profile of macrophages generated within a pathological environment (synovial fluid from Rheumatoid Arthritis patients) as well as during the GM-CSF-dependent differentiation of human monocyte-derived macrophages (GM-MØ). Mechanistically, inhibition of LXR results in macrophages with higher expression of the v-Maf Avian Musculoaponeurotic Fibrosarcoma Oncogene Homolog B (MAFB) transcription factor, which governs the macrophage anti-inflammatory profile, as well as over-expression of MAFB-regulated genes. Indeed, gene silencing experiments on human macrophages evidenced that MAFB is required for the LXR inhibitor to enhance the anti-inflammatory nature of human macrophages. As a whole, our results demonstrate that LXR inhibition prompts the acquisition of an anti-inflammatory transcriptional and functional profile of human macrophages in a MAFB-dependent manner, and propose the use of LXR antagonists as potential therapeutic alternatives in macrophage re-programming strategies during inflammatory responses.

Role of microRNA in Endocrine Disruptor-Induced Immunomodulation of Metabolic Health

The prevalence of poor metabolic health is growing exponentially worldwide. This condition is associated with complex comorbidities that lead to a compromised quality of life. One of the contributing factors recently gaining attention is exposure to environmental chemicals, such as endocrine-disrupting chemicals (EDCs). Considerable evidence suggests that EDCs can alter the endocrine system through immunomodulation. More concerning, EDC exposure during the fetal development stage has prominent adverse effects later in life, which may pass on to subsequent generations. Although the mechanism of action for this phenomenon is mostly unexplored, recent reports implicate that non-coding RNAs, such as microRNAs (miRs), may play a vital role in this scenario. MiRs are significant contributors in post-transcriptional regulation of gene expression. Studies demonstrating the immunomodulation of EDCs via miRs in metabolic health or towards the Developmental Origins of Health and Disease (DOHaD) Hypothesis are still deficient. The aim of the current review was to focus on studies that demonstrate the impact of EDCs primarily on innate immunity and the potential role of miRs in metabolic health.

Macrophage subsets and their role: co-relation with colony-stimulating factor-1 receptor and clinical relevance

Macrophages are one of the first innate immune cells to reach the site of infection or injury. Diverse functions from the uptake of pathogen or antigen, its killing, and presentation, the release of pro- or anti-inflammatory cytokines, activation of adaptive immune cells, clearing off tissue debris, tissue repair, and maintenance of tissue homeostasis have been attributed to macrophages. Besides tissue-resident macrophages, the circulating macrophages are recruited to different tissues to get activated. These are highly plastic cells, showing a spectrum of phenotypes depending on the stimulus received from their immediate environment. The macrophage differentiation requires colony-stimulating factor-1 (CSF-1) or macrophage colony-stimulating factor (M-CSF), colony-stimulating factor-2 (CSF-2), or granulocyte–macrophage colony-stimulating factor (GM-CSF) and different stimuli activate them to different phenotypes. The richness of tissue macrophages is precisely controlled via the CSF-1 and CSF-1R axis. In this review, we have given an overview of macrophage origin via hematopoiesis/myelopoiesis, different phenotypes associated with macrophages, their clinical significance, and how they are altered in various diseases. We have specifically focused on the function of CSF-1/CSF-1R signaling in deciding macrophage fate and the outcome of aberrant CSF-1R signaling in relation to macrophage phenotype in different diseases. We further extend the review to briefly discuss the possible strategies to manipulate CSF-1R and its signaling with the recent updates.

Suppression of Hepatic PPARα in Primary Biliary Cholangitis Is Modulated by miR-155

Background: PPARα is a ligand-activated transcription factor that shows protective effects against metabolic disorders, inflammation and apoptosis. Primary biliary cholangitis and primary sclerosing cholangitis result in the intrahepatic accumulation of bile acids that leads to liver dysfunction and damage. Small, non-coding RNAs such as miR-155 and miR-21 are associated with silencing PPARα. Methods: The expression of miR-155, miR-21 and PPARα were evaluated using real-time PCR on liver tissue, as well as on human hepatocytes (HepG2) or cholangiocytes (NHCs) following exposure to lipopolysaccharide (LPS), glycodeoxycholic acid (GCDCA), lithocholic acid (LCA) and/or ursodeoxycholic acid (UDCA). Results: A reduction of PPARα in primary biliary cholangitis (PBC) livers was associated with miR-21 and miR-155 upregulation. Experimental overexpression of either miR-155 or miR-21 inhibited PPARα in hepatocytes, whereas, in cholangiocytes, only miR-21 suppressed PPARα. Both GCDCA and LCA induced the cell type-specific upregulation of miR-155 or miR-21. In HepG2, LPS-induced miR-155 expression was blocked by a cotreatment with UDCA and was associated with PPARα upregulation. In NHC cells, the expression of miR-21 was induced by LPS but did not affect PPARα expression. Conclusions: Hepatic PPARα expression is reduced in PBC livers as a likely result of miR-155 overexpression. UDCA effectively reduced both baseline and LPS-induced miR-155 expression, thus preventing the suppression of PPARα.

Osteoclast-like stromal giant cells in breast cancer likely belong to the spectrum of immunosuppressive tumor-associated macrophages

Background: Breast cancer with osteoclast-like stromal giant cells (OSGC) is an exceedingly rare morphological pattern of invasive breast carcinoma. The tumor immune microenvironment (TIME) of these tumors is populated by OSGC, which resemble osteoclasts and show a histiocytic-like immunophenotype. Their role in breast cancer is unknown. The osteoclast maturation in the bone is regulated by the expression of cytokines that are also present in the TIME of tumors and in breast cancer tumor-associated macrophages (TAMs). TAMs-mediated anti-tumor immune pathways are regulated by miRNAs akin to osteoclast homeostasis. Here, we sought to characterize the different cellular compartments of breast cancers with OSGC and investigate the similarities of OSGC with tumor and TIME in terms of morphology, protein, and miRNA expression, specifically emphasizing on monocytic signatures.

Methods and Results: Six breast cancers with OSGC were included. Tumor-infiltrating lymphocytes (TILs) and TAMs were separately quantified. The different cellular populations (i.e., normal epithelium, cancer cells, and OSGC) were isolated from tissue sections by laser-assisted microdissection. After RNA purification, 752 miRNAs were analyzed using a TaqMan Advanced miRNA Low-Density Array for all samples. Differentially expressed miRNAs were identified by computing the fold change (log2Ratio) using the Kolmogorov-Smirnov test and p values were corrected for multiple comparisons using the false discovery rate (FDR) approach. As a similarity analysis among samples, we used the Pearson test. The association between pairs of variables was investigated using Fisher exact test. Classical and non-classical monocyte miRNA signatures were finally applied. All OSGC displayed CD68 expression, TILs (range, 45–85%) and high TAMs (range, 35–75%). Regarding the global miRNAs profile, OSGC was more similar to cancer cells than to non-neoplastic ones. Shared deregulation of miR-143-3p, miR-195-5p, miR-181a-5p, and miR-181b-5p was observed between OSGC and cancer cells. The monocyte-associated miR-29a-3p and miR-21-3p were dysregulated in OSGCs compared with non-neoplastic or breast cancer tissues.

Conclusion: Breast cancers with OSGC have an activated TIME. Shared epigenetic events occur during the ontogenesis of breast cancer cells and OSGC but the innumophenotype and miRNA profiles of the different cellular compartmens suggest that OSGC likely belong to the spectrum of M2 TAMs.

Nrf2-mediated anti-inflammatory polarization of macrophages as therapeutic targets for osteoarthritis

Macrophages are the most abundant immune cells within the synovial joints, and also the main innate immune effector cells triggering the initial inflammatory responses in the pathological process of osteoarthritis (OA). The transition of synovial macrophages between pro-inflammatory and anti-inflammatory phenotypes can play a key role in building the intra-articular microenvironment. The pro-inflammatory cascade induced by TNF-α, IL-1β, and IL-6 is closely related to M1 macrophages, resulting in the production of pro-chondrolytic mediators. However, IL-10, IL1RA, CCL-18, IGF, and TGF are closely related to M2 macrophages, leading to the protection of cartilage and the promoted regeneration. The inhibition of NF-κB signaling pathway is central in OA treatment via controlling inflammatory responses in macrophages, while the nuclear factor erythroid 2-related factor 2 (Nrf2) signaling pathway appears not to attract widespread attention in the field. Nrf2 is a transcription factor encoding a large number of antioxidant enzymes. The activation of Nrf2 can have antioxidant and anti-inflammatory effects, which can also have complex crosstalk with NF-κB signaling pathway. The activation of Nrf2 can inhibit the M1 polarization and promote the M2 polarization through potential signaling transductions including TGF-β/SMAD, TLR/NF-κB, and JAK/STAT signaling pathways, with the regulation or cooperation of Notch, NLRP3, PI3K/Akt, and MAPK signaling. And the expression of heme oxygenase-1 (HO-1) and the negative regulation of Nrf2 for NF-κB can be the main mechanisms for promotion. Furthermore, the candidates of OA treatment by activating Nrf2 to promote M2 phenotype macrophages in OA are also reviewed in this work, such as itaconate and fumarate derivatives, curcumin, quercetin, melatonin, mesenchymal stem cells, and low-intensity pulsed ultrasound.

Snail-regulated exosomal microRNA-21 suppresses NLRP3 inflammasome activity to enhance cisplatin resistance

BACKGROUND

Compared with the precise targeting of drug-resistant mutant cancer cells, strategies for eliminating non-genetic adaptation-mediated resistance are limited. The pros and cons of the existence of inflammasomes in cancer have been reported. Nevertheless, the dynamic response of inflammasomes to therapies should be addressed.

METHODS

Tumor-derived exosomes were purified by differential ultracentrifugation and validated by nanoparticle tracking analysis and transmission electron microscopy. A proximity ligation assay and interleukin-1β (IL-1β) level were used for detecting activation of NLRP3 inflammasomes. RNA sequencing was used to analyze the exosomal RNAs. MIR21 knocked out human monocytic THP cells and mir21 knocked out murine oral cancer MTCQ1 cells were generated for confirming the exosomal delivery of microRNA (miR)-21. Syngeneic murine models for head and neck cancer (C57BLJ/6J), breast cancer (BALB/C) and lung cancer (C57BL/6J) were applied for examining the impact of Snail-miR21 axis on inflammasome activation in vivo. Single-cell RNA sequencing was used for analyzing the tumor-infiltrated immune cells. Head and neck patient samples were used for validating the findings in clinical samples.

RESULTS

We demonstrated that in cancer cells undergoing Snail-induced epithelial-mesenchymal transition (EMT), tumor cells suppress NLRP3 inflammasome activities of tumor-associated macrophages (TAMs) in response to chemotherapy through the delivery of exosomal miR-21. Mechanistically, miR-21 represses PTEN and BRCC3 to facilitate NLRP3 phosphorylation and lysine-63 ubiquitination, inhibiting NLRP3 inflammasome assembly. Furthermore, the Snail-miR-21 axis shapes the post-chemotherapy tumor microenvironment (TME) by repopulating TAMs and by activating CD8⁺ T cells. In patients with head and neck cancer, the Snail-high cases lacked post-chemotherapy IL-1β surge and were correlated with a worse response.

CONCLUSIONS

This finding reveals the mechanism of EMT-mediated resistance beyond cancer stemness through modulation of post-treatment inflammasome activity. It also highlights the dynamic remodeling of the TME throughout metastatic evolution.

Hypoxic lung cancer cell-derived exosomal miR-21 mediates macrophage M2 polarization and promotes cancer cell proliferation through targeting IRF1

Background

Hypoxia is the hallmark of the tumor microenvironment (TME) and plays a critical role during the progress of tumor development. A variety of microRNAs (miRNAs) transmitted by tumor-derived exosomes were involved in intercellular communication. We aimed to elucidate the precise mechanism by which tumor cell-derived exosomes promote lung cancer development by affecting macrophage polarization under hypoxic conditions.

Methods

CD163 signal in tumor tissue from lung cancer patients was detected by immunohistochemical (IHC). The M2 polarization-related markers were assessed by flow cytometry and western blot. Exosomes were isolated from normoxic and hypoxic lung cancer cell culture and characterized by transmission electron microscope (TEM), dynamic light scattering (DLS), and western blot. RNA sequencing was performed to show the abnormally expressed miRNAs in exosomes from normoxic and hypoxic lung cancer cell culture. In addition, CCK-8 and clone formation assays were used to assess cell proliferation. Dual luciferase reporter assay was used to evaluate the relationship between miR-21 and IRF1. For in vivo experiment, the male nude mice were injected with H1299 cells with exosomes and miR-21 mimic treatment.

Results

Firstly, we found a strong CD163 signal in tumor tissue from lung cancer patients by IHC. Subsequently, we co-cultured lung cancer cell line H1299 with M0 macrophage THP-1 and found that H1299 in a hypoxic environment promoted THP-1 M2 polarization. PKH67 fluorescence staining experiments confirmed that exosomes of H1299 origin were able to enter THP-1 and induced M2 polarization. RNA sequencing of exosomes showed that miR-21 level was significantly higher in the hypoxic culture group compared to the normoxic group. Subsequent cellular assays showed that miR-21 inhibited the expression of IRF1 by targeting it. In addition, the overexpression of IRF1 reversed the role of miR-21 on macrophage M2 polarization. Finally, we have confirmed through animal experiments that either hypoxic environment or high miR-21 level promoted tumor progression.

Conclusions

High miR-21 level in hypoxic environments promoted macrophage M2 polarization and induced lung cancer progression through targeting IRF1.

Stem Cells in the Tumor Immune Microenvironment -Part of the Cure or Part of the Disease? Ontogeny and Dichotomy of Stem and Immune Cells has Led to better Understanding

Stem cells are at the basis of tissue homeostasis, hematopoiesis and various regenerative processes. Epigenetic changes in their somatically imprinted genes, prolonged exposure to mutagens/carcinogens or alteration of their niche can lead to the development of an enabling environment for tumor growth and progression. The involvement of stem cells in both health and disease becomes even more compelling with ontogeny as embryonic and extraembryonic stem cells which persist into adulthood in well established and specific niche may have distinct implications in tumorigenesis. Immune surveillance plays an important role in this interplay since the response of immune cells toward the oncogenic process can range from reactivity to placidity and even complicity, being orchestrated by intercellular molecular dialogues with the other key players of the tumor microenvironment. With the current understanding that every developing and adult tissue contains inherent stem and progenitor cells, in this manuscript we review the most relevant interactions carried out between the stem cells, tumor cells and immune cells in a bottom-up incursion through the tumor microenvironment beginning from the perivascular niche and going through the tumoral parenchyma and the related stroma. With the exploitation of various factors that influence the behavior of immune effectors toward stem cells and other resting cells in their niche, new therapeutic strategies to tackle the polarization of immune effectors toward a more immunogenic phenotype may arise.

Emerging Roles and Potential Applications of Non-Coding RNAs in Cervical Cancer

Cervical cancer (CC) is a preventable disease using proven interventions, specifically prophylactic vaccination, pervasive disease screening, and treatment, but it is still the most frequently diagnosed cancer in women worldwide. Patients with advanced or metastatic CC have a very dismal prognosis and current therapeutic options are very limited. Therefore, understanding the mechanism of metastasis and discovering new therapeutic targets are crucial. New sequencing tools have given a full visualization of the human transcriptome's composition. Non-coding RNAs (NcRNAs) perform various functions in transcriptional, translational, and post-translational processes through their interactions with proteins, RNA, and even DNA. It has been suggested that ncRNAs act as key regulators of a variety of biological processes, with their expression being tightly controlled under physiological settings. In recent years, and notably in the past decade, significant effort has been made to examine the role of ncRNAs in a variety of human diseases, including cancer. Therefore, shedding light on the functions of ncRNA will aid in our better understanding of CC. In this review, we summarize the emerging roles of ncRNAs in progression, metastasis, therapeutics, chemo-resistance, human papillomavirus (HPV) regulation, metabolic reprogramming, diagnosis, and as a prognostic biomarker of CC. We also discussed the role of ncRNA in the tumor microenvironment and tumor immunology, including cancer stem cells (CSCs) in CC. We also address contemporary technologies such as antisense oligonucleotides, CRISPR-Cas9, and exosomes, as well as their potential applications in targeting ncRNAs to manage CC.

Changes in the Small Noncoding RNAome During M1 and M2 Macrophage Polarization

Macrophages belong to a special phagocytic subgroup of human leukocytes and are one of the important cells of the human immune system. Small noncoding RNAs are a group of small RNA molecules that can be transcribed without the ability to encode proteins but could play a specific function in cells. SncRNAs mainly include microRNAs (miRNAs) and piwi-interacting RNAs (piRNAs), small nucleolar RNAs (snoRNAs), small nuclear RNAs (snRNAs) and repeat RNAs. We used high-throughput sequencing analysis and qPCR to detect the expression changes of the small noncoding RNAome during macrophage polarization. Our results showed that 84 miRNAs and 47 miRNAs with were downregulated during M1 macrophage polarization and that 11 miRNAs were upregulated and 19 miRNAs were downregulated during M2 macrophage polarization. MiR-novel-3-nature and miR-27b-5p could promote expression of TNF-α which was marker gene of M1 macrophages. The piRNA analysis results showed that 69 piRNAs were upregulated and 61 piRNAs were downregulated during M1 macrophage polarization and that 3 piRNAs were upregulated and 10 piRNAs were downregulated during M2 macrophage polarization. DQ551351 and DQ551308 could promote the mRNA expression of TNF-α and DQ551351overexpression promoted the antitumor activity of M1 macrophages. SnoRNA results showed that 62 snoRNAs were upregulated and 59 snoRNAs were downregulated during M1 macrophage polarization, whereas 6 snoRNAs were upregulated and 10 snoRNAs were downregulated during M2 macrophage polarization. Overexpression of snoRNA ENSMUST00000158683.2 could inhibit expression of TNF-α. For snRNA, we found that 12 snRNAs were upregulated and 15 snRNAs were downregulated during M1 macrophage polarization and that 2 snRNAs were upregulated during M2 macrophage polarization. ENSMUSG00000096786 could promote expression of IL-1 and iNOS and ENSMUSG00000096786 overexpression promoted the antitumor activity of M1 macrophages. Analysis of repeat RNAs showed that 7 repeat RNAs were upregulated and 9 repeat RNAs were downregulated during M1 macrophage polarization and that 2 repeat RNAs were downregulated during M2 macrophage polarization. We first reported the expression changes of piRNA, snoRNA, snRNA and repeat RNA during macrophage polarization, and preliminarily confirmed that piRNA, snoRNA and snRNA can regulate the function of macrophages.

Abnormal Epigenetic Regulations in the Immunocytes of Sjögren’s Syndrome Patients and Therapeutic Potentials

Sjögren’s syndrome (SjS), characterized by keratoconjunctivitis sicca and dry mouth, is a common autoimmune disease, especially in middle-aged women. The immunopathogenesis of SjS is caused by the sequential infiltration of T and B cells into exocrine glands, including salivary and lacrimal glands. Effector cytokines produced by these immunocytes, such as interferons (IFNs), IL-17, IL-22, IL-21, IL-4, TNF-α, BAFF and APRIL, play critical roles in promoting autoimmune responses and inducing tissue damages. Epigenetic regulations, including DNA methylation, histone modification and non-coding RNAs, have recently been comprehensively studied during the activation of various immunocytes. The deficiency of key epigenetic enzymes usually leads to aberrant immune activation. Epigenetic modifications in T and B cells are usually found to be altered during the immunopathogenesis of SjS, and they are closely correlated with autoimmune responses. In particular, the important role of methylation in activating IFN pathways during SjS progression has been revealed. Thus, according to the involvement of epigenetic regulations in SjS, target therapies to reverse the altered epigenetic modifications in auto-responsive T and B cells are worthy of being considered as a potential therapeutic strategy for SjS.

Impact of non-coding RNAs on cancer directed immune therapies: Now then and forever

Accumulating evidence demonstrates that the host genome's epigenetic modifications are essential for living organisms to adapt to extreme conditions. DNA methylation, covalent modifications of histone, and inter-association of non-coding RNAs facilitate the cellular manifestation of epigenetic changes in the genome. Out of various factors involved in the epigenetic programming of the host, non-coding RNAs (ncRNAs) such as microRNA (miRNA), long non-coding RNA (lncRNA), circular RNA, snoRNA and piRNA are new generation non-coding molecules that influence a variety of cellular processes like immunity, cellular differentiation, and tumor development. During tumor development, temporal changes in miRNA/LncRNA rheostat influence sterile inflammatory responses accompanied by the changes in the carcinogenic signaling in the host. At the cellular level, this is manifested by the up-regulation of Inflammasome and inflammatory pathways, which promotes cancer-related inflammation. Given this, we discuss the potential of lncRNAs, miRNAs, circular RNA, snoRNA and piRNA in regulating inflammation and tumor development in the host. This article is protected by copyright. All rights reserved.

Activation of LXR Nuclear Receptors Impairs the Anti-Inflammatory Gene and Functional Profile of M-CSF-Dependent Human Monocyte-Derived Macrophages

Liver X Receptors (LXR) control cholesterol metabolism and exert anti-inflammatory actions but their contribution to human macrophage polarization remains unclear. The LXR pathway is enriched in pro-inflammatory macrophages from rheumatoid arthritis as well as in tumors-associated macrophages from human tumors. We now report that LXR activation inhibits the anti-inflammatory gene and functional profile of M-CSF-dependent human macrophages, and prompts the acquisition of a pro-inflammatory gene signature, with both effects being blocked by an LXR inverse agonist. Mechanistically, the LXR-stimulated macrophage polarization shift correlates with diminished expression of MAFB and MAF, which govern the macrophage anti-inflammatory profile, and with enhanced release of activin A. Indeed, LXR activation impaired macrophage polarization in response to tumor-derived ascitic fluids, as well as the expression of MAF- and MAFB-dependent genes. Our results demonstrate that LXR activation limits the anti-inflammatory human macrophage polarization and prompts the acquisition of an inflammatory transcriptional and functional profile.

MicroRNA-200c Attenuates the Tumor-Infiltrating Capacity of Macrophages

Simple Summary

The tumor microenvironment determines the prognosis and outcome for cancer patients. Herein, tumor-associated macrophages are not only highly abundant, but also play a crucial role in shaping a tumor-supporting microenvironment. Both their recruitment to the tumor as well as their functional polarization toward a pro-tumorigenic phenotype are mediated by tumor-derived factors including microRNAs. However, the impact of most microRNAs on the tumor cell-macrophage crosstalk remains to be elucidated. Thus, we reached out to investigate the role of hsa-miR-200c-3p (miR-200c) in tumor cell–macrophage interactions, as it was shown to be differentially expressed during cancer progression and metastasis. miR-200c was highly expressed in MCF7 breast tumor cells compared to macrophages. Furthermore, we identified a CD36-dependent uptake of miR-200c, derived from apoptotic tumor cells, into macrophages. In macrophages, elevated miR-200c levels reduced the expression of numerous migration-associated mRNAs, consequently reducing the capacity of macrophages to infiltrate into tumor spheroids. Finally, a distinct signature of miR-200c-repressed, predicted targets was identified, which strongly correlated with tumor infiltration. Targeting the miR-200c transfer from dying tumor cells to macrophages might therefore provide the opportunity to specifically modulate tumor-associated macrophage recruitment.

Abstract

Macrophages constitute a major part of the tumor-infiltrating immune cells. Within the tumor microenvironment, they acquire an alternatively activated, tumor-supporting phenotype. Factors released by tumor cells are crucial for the recruitment of tumor-associated macrophages. In the present project, we aimed to understand the role of hsa-miR-200c-3p (miR-200c) in the interplay between tumor cells and macrophages. To this end, we employed a coculture system of MCF7 breast tumor cells and primary human macrophages and observed the transfer of miR-200c from apoptotic tumor cells to macrophages, which required intact CD36 receptor in macrophages. We further comprehensively determined miR-200c targets in macrophages by mRNA-sequencing and identified numerous migration-associated mRNAs to be downregulated by miR-200c. Consequently, miR-200c attenuated macrophage infiltration into 3-dimensional tumor spheroids. miR-200c-mediated reduction in infiltration further correlated with a miR-200c migration signature comprised of the four miR-200c-repressed, predicted targets PPM1F, RAB11FIB2, RDX, and MSN.

The Role of miRNA in Regulating the Fate of Monocytes in Health and Cancer

Monocytes represent a heterogeneous population of blood cells that provide a link between innate and adaptive immunity. The unique potential of monocytes as both precursors (e.g., of macrophages) and effector cells (as phagocytes or cytotoxic cells) makes them an interesting research and therapeutic target. At the site of a tumor, monocytes/macrophages constitute a major population of infiltrating leukocytes and, depending on the type of tumor, may play a dual role as either a bad or good indicator for cancer recovery. The functional activity of monocytes and macrophages derived from them is tightly regulated at the transcriptional and post-transcriptional level. This review summarizes the current understanding of the role of small regulatory miRNA in monocyte formation, maturation and function in health and cancer development. Additionally, signatures of miRNA-based monocyte subsets and the influence of exogenous miRNA generated in the tumor environment on the function of monocytes are discussed.

Colony stimulating factors in the nervous system

Although traditionally seen as regulators of hematopoiesis, colony-stimulating factors (CSFs) have emerged as important players in the nervous system, both in health and disease. This review summarizes the cellular sources, patterns of expression and physiological roles of the macrophage (CSF-1, IL-34), granulocyte-macrophage (GM-CSF) and granulocyte (G-CSF) colony stimulating factors within the nervous system, with a particular focus on their actions on microglia. CSF-1 and IL-34, via the CSF-1R, are required for the development, proliferation and maintenance of essentially all CNS microglia in a temporal and regional specific manner. In contrast, in steady state, GM-CSF and G-CSF are mainly involved in regulation of microglial function. The alterations in expression of these growth factors and their receptors, that have been reported in several neurological diseases, are described and the outcomes of their therapeutic targeting in mouse models and humans are discussed.

MicroRNA in extracellular vesicles regulates inflammation through macrophages under hypoxia

Extracellular vesicle (EV), critical mediators of cell-cell communication, allow cells to exchange proteins, lipids, and genetic material and therefore profoundly affect the general homeostasis. A hypoxic environment can affect the biogenesis and secrete of EVs, and the cargoes carried can participate in a variety of physiological and pathological processes. In hypoxia-induced inflammation, microRNA(miRNA) in EV participates in transcriptional regulation through various pathways to promote or reduce the inflammatory response. Meanwhile, as an important factor of immune response, the polarization of macrophages is closely linked to miRNAs, which will eventually affect the inflammatory state. In this review, we outline the possible molecular mechanism of EV changes under hypoxia, focusing on the signaling pathways of several microRNAs involved in inflammation regulation and describing the process and mechanism of EV-miRNAs regulating macrophage polarization in hypoxic diseases.

PLX3397, a CSF1 receptor inhibitor, limits allotransplantation-induced vascular remodelling

AIMS

Graft vascular disease (GVD), a clinically important and highly complex vascular occlusive disease, arises from the interplay of multiple cellular and molecular pathways. While occlusive intimal lesions are composed predominantly of smooth-muscle-like cells (SMLCs), the origin of these cells and the stimuli leading to their accumulation in GVD are uncertain. Macrophages have recently been identified as both potential drivers of intimal hyperplasia and precursors that undergo transdifferentiation to become SMLCs in non-transplant settings. Colony-stimulating factor-1 (CSF1) is a well-known regulator of macrophage development and differentiation, and prior preclinical studies have shown that lack of CSF1 limits GVD. We sought to identify the origins of SMLCs and of cells expressing the CSF1 receptor (CSF1R) in GVD, and to test the hypothesis that pharmacologic inhibition of CSF1 signalling would curtail both macrophage and SMLC activities and decrease vascular occlusion.

METHODS AND RESULTS

We used genetically modified mice and a vascular transplant model with minor antigen mismatch to assess cell origins. We found that neointimal SMLCs derive from both donor and recipient, and that transdifferentiation of macrophages to SMLC phenotype is minimal in this model. Cells expressing CSF1R in grafts were identified as recipient-derived myeloid cells of Cx3cr1 lineage, and these cells rarely expressed smooth muscle marker proteins. Blockade of CSF1R activity using the tyrosine kinase inhibitor PLX3397 limited the expression of genes associated with innate immunity and decreased levels of circulating monocytes and intimal macrophages. Importantly, PLX3397 attenuated the development of GVD in arterial allografts.

CONCLUSION

These studies provide proof of concept for pharmacologic inhibition of the CSF1/CSF1R signalling pathway as a therapeutic strategy in GVD. Further preclinical testing of this pathway in GVD is warranted.

Macrophage migration inhibitory factor of Thelazia callipaeda induces M2-like macrophage polarization through TLR4-mediated activation of the PI3K-Akt pathway

Macrophage migration inhibitory factor (MIF), an immunoregulatory cytokine plays an important role in inflammation and the immune response, and has been described as having a potential role in immune evasion by parasites. Thelazia callipaeda, a vector-borne zoonotic eye worm with a broad host range, has been documented as an agent of ocular infection of thelaziosis. The ability of T. callipaeda to persist in an immunologically competent host has led to the suggestion that it has evolved specific measures to counter immune defenses. To date, whether the immune evasion of T. callipaeda is related to MIF and the possible related signaling pathway and molecular mechanism have remained unclear. In the present study, we examined the effect of T. callipaeda MIF (T. cp-MIF) on macrophages. We analyzed the antigenic epitopes of the candidate T. cp-MIF and found that it exhibited an ideal antigenic index. Morphology, Flow cytometry, and cytokine analysis showed that T. cp-MIF induced the dynamic polarization of THP-1 macrophages from the M1-like phenotype to the M2-like phenotype. The chemotaxis assay revealed an inhibitory effect of T. cp-MIF on THP-1 macrophages. Western blotting suggested that, compared to the control, THP-1 macrophages exposed to T. cp-MIF had higher TLR4 protein expression and the phosphatidylinositol 3'-kinase (PI3K) -Akt pathway activation. In conclusion, T. cp-MIF induces M2-like macrophage polarization through TLR4-mediated activation of the PI3K-Akt pathway, which might provide a basis for future research on how it affects the immune system of the host.

The Role of microRNAs in Pulp Inflammation

The dental pulp can be affected by thermal, physical, chemical, and bacterial phenomena that stimulate the inflammatory response. The pulp tissue produces an immunological, cellular, and vascular reaction in an attempt to defend itself and resolve the affected tissue. The expression of different microRNAs during pulp inflammation has been previously documented. MicroRNAs (miRNAs) are endogenous small molecules involved in the transcription of genes that regulate the immune system and the inflammatory response. They are present in cellular and physiological functions, as well as in the pathogenesis of human diseases, becoming potential biomarkers for diagnosis, prognosis, monitoring, and safety. Previous studies have evidenced the different roles played by miRNAs in proinflammatory, anti-inflammatory, and immunological phenomena in the dental pulp, highlighting specific key functions of pulp pathology. This systematized review aims to provide an understanding of the role of the different microRNAs detected in the pulp and their effects on the expression of the different target genes that are involved during pulp inflammation.

MicroRNA-21 Deficiency Promotes the Early Th1 Immune Response and Resistance toward Visceral Leishmaniasis

MicroRNA-21 (miR-21) inhibits IL-12 expression and impairs the Th1 response necessary for control of Leishmania infection. Recent studies have shown that Leishmania infection induces miR-21 expression in dendritic cells and macrophages, and inhibition of miR-21 restores IL-12 expression. Because miR-21 is known to be expressed due to inflammatory stimuli in a wide range of hematopoietic cells, we investigated the role of miR-21 in regulating immune responses during visceral leishmaniasis (VL) caused by Leishmania donovani infection. We found that miR-21 expression was significantly elevated in dendritic cells, macrophages, inflammatory monocytes, polymorphonuclear neutrophils, and in the spleen and liver tissues after L. donovani infection, concomitant with an increased expression of disease exacerbating IL-6 and STAT3. Bone marrow dendritic cells from miR-21 knockout (miR-21KO) mice showed increased IL-12 production and decreased production of IL-10. On L. donovani infection, miR-21KO mice exhibited significantly greater numbers of IFN-γ- and TNF-α-producing CD4⁺ and CD8⁺ T cells in their organs that was associated with increased production of Th1-associated IFN-γ, TNF-α, and NO from the splenocytes. Finally, miR-21KO mice displayed significantly more developing and mature hepatic granulomas leading to reduction in organ parasitic loads compared with wild type counterparts. Similar results were noted in L. donovani-infected wild type mice after transient miR-21 depletion. These observations indicate that miR-21 plays a critical role in pathogenesis of VL by suppressing IL-12- and Th1-associated IFN-γ and also inducing disease-promoting induction of the IL-6 and STAT-3 signaling pathway. miR-21 could therefore be used as a potential target for developing host-directed treatment for VL.

Macrophage-Derived MicroRNA-21 Drives Overwhelming Glycolytic and Inflammatory Response during Sepsis via Repression of the PGE2/IL-10 Axis

Myeloid cells are critical for systemic inflammation, microbial control, and organ damage during sepsis. MicroRNAs are small noncoding RNAs that can dictate the outcome of sepsis. The role of myeloid-based expression of microRNA-21 (miR-21) in sepsis is inconclusive. In this study, we show that sepsis enhanced miR-21 expression in both peritoneal macrophages and neutrophils from septic C57BL/6J mice, and the deletion of miR-21 locus in myeloid cells (miR-21^Δmyel mice) enhanced animal survival, decreased bacterial growth, decreased systemic inflammation, and decreased organ damage. Resistance to sepsis was associated with a reduction of aerobic glycolysis and increased levels of the anti-inflammatory mediators PGE₂ and IL-10 in miR-21^Δmyel in vivo and in vitro. Using blocking Abs and pharmacological tools, we discovered that increased survival and decreased systemic inflammation in septic miR-21^Δmyel mice is dependent on PGE₂/IL-10-mediated inhibition of glycolysis. Together, these findings demonstrate that expression of miR-21 in myeloid cells orchestrates the balance between anti-inflammatory mediators and metabolic reprogramming that drives cytokine storm during sepsis.

Exosomes as Part of the Human Adipose-Derived Stem Cells Secretome- Opening New Perspectives for Cell-Free Regenerative Applications

Human adipose-derived stem cells (hASCs) represent a great resource for regenerative medicine based on their accessibility, self-renewal potential, low immunogenicity, high proliferative rate and potential to differentiate on multiple lineages. Their secretome is rich in chemokines, cytokines and protein growth factors that are actively involved in regeneration processes. In addition, part of this secretome are also the exosomes (hASC-exos), which display high content in proteins, messenger RNAs (mRNAs) and non-coding RNAs (ncRNAs). Due to their content, exosomes promote tissue regeneration by different mechanisms, either by activating or inhibiting several signaling pathways involved in wound healing, extracellular matrix remodeling, immunomodulation, angiogenesis, anti-apoptotic activity and cell migration, proliferation and differentiation. The use of hASC-exos may provide an improved alternative to standard therapies used in regenerative medicine, as a cell-free new approach with multiple possibilities to be modulated according to the patient needs. This review offers an updated overview on the functions and applications of hASC-exos in all areas of tissue regeneration, aiming to highlight to the reader the benefits of using hASCs in modern tissue engineering and regenerative medicine applications.

The roles of macrophage polarization in the host immune response to sepsis

Sepsis is a life-threatening clinical syndrome caused by infection. Its pathogenesis is complex and entails coagulation dysfunction, inflammation, and immune disorders. Macrophages are important components of innate and adaptive immunity that are highly heterogeneous and plastic. They can polarize into a multi-dimensional spectrum of phenotypes with different functions relating to immune regulation in response to changes in the microenvironment of specific tissues. We reviewed studies that examined the role of macrophage polarization with a focus on the classical activated (M1-like) and alternative activated (M2-like) macrophages as the two main phenotypes involved in the host immune response to sepsis. A complex regulatory network is involved in the process of macrophage polarization, which is influenced by a variety of signaling molecules, transcription factors, epigenetic modifications, and metabolic reprogramming. M1-like macrophages release large quantities of pro-inflammatory mediators, while M2-like macrophages release large quantities of anti-inflammatory mediators. An imbalance between M1-like and M2-like macrophages induces the occurrence and development of sepsis. Therefore, targeted regulation of the process of macrophage polarization could be a useful approach to normalize the immune balance of the host, offering a new treatment modality for different stages of sepsis.

Context-Dependent miR-21 Regulation of TLR7-Mediated Autoimmune and Foreign Antigen-Driven Antibody-Forming Cell and Germinal Center Responses

MicroRNAs (miRNAs) are involved in healthy B cell responses and the loss of tolerance in systemic lupus erythematosus (SLE), although the role of many miRNAs remains poorly understood. Dampening miR-21 activity was previously shown to reduce splenomegaly and blood urea nitrogen levels in SLE-prone mice, but the detailed cellular responses and mechanism of action remains unexplored. In this study, using the TLR7 agonist, imiquimod-induced SLE model, we observed that loss of miR-21 in Sle1b mice prevented the formation of plasma cells and autoantibody-producing Ab-forming cells (AFCs) without a significant effect on the magnitude of the germinal center (GC) response. We further observed reduced dendritic cell and monocyte numbers in the spleens of miR-21-deficient Sle1b mice that were associated with reduced IFN, proinflammatory cytokines, and effector CD4⁺ T cell responses. RNA sequencing analysis on B cells from miR-21-deficient Sle1b mice revealed reduced activation and response to IFN, and cytokine and target array analysis revealed modulation of numerous miR-21 target genes in response to TLR7 activation and type I IFN stimulation. Our findings in the B6.Sle1bYaa (Sle1b ^Yaa) spontaneous model recapitulated the miR-21 role in TLR7-induced responses with an additional role in autoimmune GC and T follicular helper responses. Finally, immunization with T-dependent Ag revealed a role for miR-21 in foreign Ag-driven GC and Ab, but not AFC, responses. Our data suggest a potential multifaceted, context-dependent role for miR-21 in autoimmune and foreign Ag-driven AFC and GC responses. Further study is warranted to delineate the cell-intrinsic requirements and mechanisms of miR-21 during infection and SLE development.

Dermal bacterial LPS-stimulation reduces susceptibility to intradermal Trypanosoma brucei infection

Infections with Trypanosoma brucei sp. are established after the injection of metacyclic trypomastigotes into the skin dermis by the tsetse fly vector. The parasites then gain access to the local lymphatic vessels to infect the local draining lymph nodes and disseminate systemically via the bloodstream. Macrophages are considered to play an important role in host protection during the early stage of systemic trypanosome infections. Macrophages are abundant in the skin dermis, but relatively little is known of their impact on susceptibility to intradermal (ID) trypanosome infections. We show that although dermal injection of colony stimulating factor 1 (CSF1) increased the local abundance of macrophages in the skin, this did not affect susceptibility to ID T. brucei infection. However, bacterial LPS-stimulation in the dermis prior to ID trypanosome infection significantly reduced disease susceptibility. In vitro assays showed that LPS-stimulated macrophage-like RAW264.7 cells had enhanced cytotoxicity towards T. brucei, implying that dermal LPS-treatment may similarly enhance the ability of dermal macrophages to eliminate ID injected T. brucei parasites in the skin. A thorough understanding of the factors that reduce susceptibility to ID injected T. brucei infections may lead to the development of novel strategies to help reduce the transmission of African trypanosomes.

Combined Effects of Myeloid Cells in the Neuroblastoma Tumor Microenvironment

Despite multimodal treatment, survival chances for high-risk neuroblastoma patients remain poor. Immunotherapeutic approaches focusing on the activation and/or modification of host immunity for eliminating tumor cells, such as chimeric antigen receptor (CAR) T cells, are currently in development, however clinical trials have failed to reproduce the preclinical results. The tumor microenvironment is emerging as a major contributor to immune suppression and tumor evasion in solid cancers and thus has to be overcome for therapies relying on a functional immune response. Among the cellular components of the neuroblastoma tumor microenvironment, suppressive myeloid cells have been described as key players in inhibition of antitumor immune responses and have been shown to positively correlate with more aggressive disease, resistance to treatments, and overall poor prognosis. This review article summarizes how neuroblastoma-driven inflammation induces suppressive myeloid cells in the tumor microenvironment and how they in turn sustain the tumor niche through suppressor functions, such as nutrient depletion and generation of oxidative stress. Numerous preclinical studies have suggested a range of drug and cellular therapy approaches to overcome myeloid-derived suppression in neuroblastoma that warrant evaluation in future clinical studies.

A narrative review of tumor-associated macrophages in lung cancer: regulation of macrophage polarization and therapeutic implications

Lung cancer is the deadliest malignancy worldwide. An inflammatory microenvironment is a key factor contributing to lung tumor progression. Tumor-Associated Macrophages (TAMs) are prominent components of the cancer immune microenvironment with diverse supportive and inhibitory effects on growth, progression, and metastasis of lung tumors. Two main macrophage phenotypes with different functions have been identified. They include inflammatory or classically activated (M1) and anti-inflammatory or alternatively activated (M2) macrophages. The contrasting functions of TAMs in relation to lung neoplasm progression stem from the presence of TAMs with varying tumor-promoting or anti-tumor activities. This wide spectrum of functions is governed by a network of cytokines and chemokines, cell-cell interactions, and signaling pathways. TAMs are promising therapeutic targets for non-small cell lung cancer (NSCLC) treatment. There are several strategies for TAM targeting and utilizing them for therapeutic purposes including limiting monocyte recruitment and localization through various pathways such as CCL2-CCR2, CSF1-CSF1R, and CXCL12-CXCR4, targeting the activation of TAMs, genetic and epigenetic reprogramming of TAMs to antitumor phenotype, and utilizing TAMs as the carrier for anti-cancer drugs. In this review, we will outline the role of macrophages in the lung cancer initiation and progression, pathways regulating their function in lung cancer microenvironment as well as the role of these immune cells in the development of future therapeutic strategies.

Withholding of M-CSF Supplement Reprograms Macrophages to M2-Like via Endogenous CSF-1 Activation

Macrophage colony-stimulating factor (M-CSF or CSF-1) is known to have a broad range of actions on myeloid cells maturation, including the regulation of macrophage differentiation, proliferation and survival. Macrophages generated by M-CSF stimulus have been proposed to be alternatively activated or M2 phenotype. M-CSF is commonly overexpressed by tumors and is also known to enhance tumor growth and aggressiveness via stimulating pro-tumor activities of tumor-associated macrophages (TAMs). Currently, inhibition of CSF-1/CSF-1R interaction by therapeutic antibody to deplete TAMs and their pro-tumor functions is becoming a prevalent strategy in cancer therapy. However, its antitumor activity shows a limited single-agent effect. Therefore, macrophages in response to M-CSF interruption are pending for further investigation. To achieve this study, bone marrow derived macrophages were generated in vitro by M-CSF stimulation for 7 days and then continuously grown until day 21 in M-CSF absence. A selective pressure for cell survival was initiated after withdrawal of M-CSF. The surviving cells were more prone to M2-like phenotype, even after receiving interleukin-4 (IL-4) stimulation. The transcriptome analysis unveiled that endogenous CSF-1 level was dramatically up-regulated and numerous genes downstream to CSF-1 covering tumor necrosis factor (TNF), ras-related protein 1 (Rap1) and phosphatidylinositol 3-kinase (PI3K)-protein kinase B (AKT) signaling pathway were significantly modulated, especially for proliferation, migration and adhesion. Moreover, the phenomenal increase of miR-21-5p and genes related to pro-tumor activity were observed in parallel. In summary, withholding of CSF-1/CSF-1R interaction would rather augment than suspend the M-CSF-driven pro-tumor activities of M2 macrophages in a long run.

Retinoic acid abrogates LPS-induced inflammatory response via negative regulation of NF-kappa B/miR-21 signaling

CONTEXT

Macrophages are essential components of the immune system, with significant roles in inflammation modulation. They can be activated into pro-inflammatory M1 or anti-inflammatory M2 phenotypes, depending on their micro-environment. Molecular factors that modulate macrophage polarization are hot targets for therapeutic strategies to counter chronic inflammatory pathological conditions.

OBJECTIVE

The current study aimed to elucidate the molecular mechanisms by which Retinoic acid (RA), a potent immunomodulator, suppresses LPS-induced inflammatory response in macrophages.

MATERIALS AND METHODS

RAW 264.7 macrophages were treated with RA and/or LPS, and analyzed for inflammatory genes and miR-21 by PCR. The roles of miR-21 and NF-ĸB signaling pathway were also assessed by knock-down experiments, immunofluorescence, and ChIP assays.

RESULTS

Pretreatment with RA quenched the LPS-induced inflammatory responses, including phagocytosis, ROS generation, and NO production. RA shifted the polarization away from the M1 state by negative regulation of IKKα/β, p65, and miR-21. RA hindered the phosphorylation of IKKα/β, translocation of p65 into the nucleus, and the subsequent upregulation of miR-21. Knock-in and knock-down experiments showed that miR-21 is central for the polarization shift toward the pro-inflammatory M1 state.

CONCLUSION

miR-21 is involved in the LPS-induced pro-inflammatory profile of macrophages and that RA negatively regulates the inflammatory response by targeting NF-ĸB/miR-21 signaling. Our data exposes RA's potential as a pharmacological agent to manipulate miR-21 and counteract hyper-inflammatory response.

The Potential of Exosomal RNAs in Atherosclerosis Diagnosis and Therapy

Atherosclerosis is an inflammatory disease that can lead to cardiovascular disorders and stroke. In the atherosclerosis microenvironment, exosomes secreted from various cells, especially macrophage-derived exosomes, play an important role in cell–cell communication and cellular biological functions. In this article, we review previous studies on exosomal RNAs and discuss their potential value in atherosclerosis diagnosis and therapy. Based on our research, we concluded that macrophage exosomes have potential value in atherosclerosis diagnosis and therapy. However, there is a need for future studies to further investigate methods of exosome isolation and targeting.

MicroRNAs as Potential Regulators of Immune Response Networks in Asthma and Chronic Obstructive Pulmonary Disease

Chronic respiratory diseases (CRDs) are an important factor of morbidity and mortality, accounting for approximately 6% of total deaths worldwide. The main CRDs are asthma and chronic obstructive pulmonary disease (COPD). These complex diseases have different triggers including allergens, pollutants, tobacco smoke, and other risk factors. It is important to highlight that although CRDs are incurable, various forms of treatment improve shortness of breath and quality of life. The search for tools that can ensure accurate diagnosis and treatment is crucial. MicroRNAs (miRNAs) are small non-coding RNAs and have been described as promising diagnostic and therapeutic biomarkers for CRDs. They are implicated in multiple processes of asthma and COPD, regulating pathways associated with inflammation, thereby showing that miRNAs are critical regulators of the immune response. Indeed, miRNAs have been found to be deregulated in several biofluids (sputum, bronchoalveolar lavage, and serum) and in both structural lung and immune cells of patients in comparison to healthy subjects, showing their potential role as biomarkers. Also, miRNAs play a part in the development or termination of histopathological changes and comorbidities, revealing the complexity of miRNA regulation and opening up new treatment possibilities. Finally, miRNAs have been proposed as prognostic tools in response to both conventional and biologic treatments for asthma or COPD, and miRNA-based treatment has emerged as a potential approach for clinical intervention in these respiratory diseases; however, this field is still in development. The present review applies a systems biology approach to the understanding of miRNA regulatory networks in asthma and COPD, summarizing their roles in pathophysiology, diagnosis, and treatment.

Review on experimental study and clinical application of low-intensity pulsed ultrasound in inflammation

Low-intensity pulsed ultrasound (LIPUS), as physical therapy, is widely used in both research and clinical settings. It induces multiple bioeffects, such as alleviating pain, promoting tissue repair, and shortening disease duration. LIPUS can also mediate inflammation. This paper reviews the application of LIPUS in inflammation and discusses the underlying mechanism. In basic experiments, LIPUS can regulate inflammatory responses at the cellular level by affecting some signaling pathways. In a clinical trial, LIPUS has been shown to alleviate inflammatory responses efficiently. As a cheap, safe, and convenient physical method, LIPUS is promising as anti-inflammatory therapy.