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Arteriosclerosis, Thrombosis, and... Jan 2020Macrophages play a central role in the development of atherosclerotic cardiovascular disease (ASCVD), which encompasses coronary artery disease, peripheral artery... (Review)
Review
Macrophages play a central role in the development of atherosclerotic cardiovascular disease (ASCVD), which encompasses coronary artery disease, peripheral artery disease, cerebrovascular disease, and aortic atherosclerosis. In each vascular bed, macrophages contribute to the maintenance of the local inflammatory response, propagate plaque development, and promote thrombosis. These central roles, coupled with their plasticity, makes macrophages attractive therapeutic targets in stemming the development of and stabilizing existing atherosclerosis. In the context of ASCVD, classically activated M1 macrophages initiate and sustain inflammation, and alternatively activated M2 macrophages resolve inflammation. However, this classification is now considered an oversimplification, and a greater understanding of plaque macrophage physiology in ASCVD is required to aid in the development of therapeutics to promote ASCVD regression. Reviewed herein are the macrophage phenotypes and molecular regulators characteristic of ASCVD regression, and the current murine models of ASCVD regression.
Topics: Animals; Atherosclerosis; Coronary Artery Disease; Disease Progression; Humans; Leukocyte Count; Macrophage Activation; Macrophages; Phenotype; Plaque, Atherosclerotic
PubMed: 31722535
DOI: 10.1161/ATVBAHA.119.312802 -
Proceedings of the National Academy of... Aug 2022Animal tissues comprise diverse cell types. However, the mechanisms controlling the number of each cell type within tissue compartments remain poorly understood. Here,...
Animal tissues comprise diverse cell types. However, the mechanisms controlling the number of each cell type within tissue compartments remain poorly understood. Here, we report that different cell types utilize distinct strategies to control population numbers. Proliferation of fibroblasts, stromal cells important for tissue integrity, is limited by space availability. In contrast, proliferation of macrophages, innate immune cells involved in defense, repair, and homeostasis, is constrained by growth factor availability. Examination of density-dependent gene expression in fibroblasts revealed that Hippo and TGF-β target genes are both regulated by cell density. We found YAP1, the transcriptional coactivator of the Hippo signaling pathway, directly regulates expression of , the lineage-specific growth factor for macrophages, through an enhancer of that is specifically active in fibroblasts. Activation of YAP1 in fibroblasts elevates expression and is sufficient to increase the number of macrophages at steady state. Our data also suggest that expression programs in fibroblasts that change with density may result from sensing of mechanical force through actin-dependent mechanisms. Altogether, we demonstrate that two different modes of population control are connected and coordinated to regulate cell numbers of distinct cell types. Sensing of the tissue environment may serve as a general strategy to control tissue composition.
Topics: Animals; Cell Count; Cell Proliferation; Fibroblasts; Hippo Signaling Pathway; Macrophages; Transforming Growth Factor beta; YAP-Signaling Proteins
PubMed: 35930670
DOI: 10.1073/pnas.2205360119 -
International Journal of Molecular... Jul 2022Chronic inflammation is implicated in numerous human pathologies. In particular, low-grade inflammation is currently recognized as an important mechanism of... (Review)
Review
Chronic inflammation is implicated in numerous human pathologies. In particular, low-grade inflammation is currently recognized as an important mechanism of osteoarthritis (OA), at least in some patients. Among the signs of the inflammatory process are elevated macrophage numbers detected in the OA synovium compared to healthy controls. High macrophage counts also correlate with clinical symptoms of the disease. Macrophages are central players in the development of chronic inflammation, pain, cartilage destruction, and bone remodeling. However, macrophages are also involved in tissue repair and remodeling, including cartilage. Therefore, reduction of macrophage content in the joints correlates with deleterious effects in OA models. Macrophage population is heterogeneous and dynamic, with phenotype transitions being induced by a variety of stimuli. In order to effectively use the macrophage inflammatory circuit for treatment of OA, it is important to understand macrophage heterogeneity and interactions with surrounding cells and tissues in the joint. In this review, we discuss functional phenotypes of macrophages and specific targeting approaches relevant for OA treatment development.
Topics: Humans; Inflammation; Macrophages; Osteoarthritis; Phenotype; Synovial Membrane
PubMed: 35955514
DOI: 10.3390/ijms23158381 -
Immunobiology May 2022The present study intends to clarify the hypothesis that PVL-positive Methicillin-resistant S. aureus strain (PVL-MRSA)-infected macrophages regulate autophagy and thus...
The present study intends to clarify the hypothesis that PVL-positive Methicillin-resistant S. aureus strain (PVL-MRSA)-infected macrophages regulate autophagy and thus in turn inhibit phagocytosis through the in vitro and in vivo experiments. The autophagy of mouse macrophage cell line RAW264.7 was observed by fluorescence microscopy, and counted based on the number of each cell dot-like structure GFP-LC3. The protein levels of the phagocytic factors associated with autophagy were determined by western blotting. The phagocytosis of RAW264.7 on MRSA was determined by counting the colony. The clinically isolated and identified PVL-MRSA strain was used to infect BALB/c mice (left nasal drip) to establish a mouse pneumonia model. PVL-MRSA mice were then treated with 3-MA or linezolid. Bronchoalveolar lavage fluid (BALF) from mice was collected for macrophage counting by Flow cytometry assay. The right lung was aseptically isolated for counting the amount of bacteria. The results showed that PVL-MRSA could induced the autophagy of macrophages, which in turn reduced the damage from macrophages, which were respectively alleviated by 3-MA and aggravated by rapamycin. Exogenous rPVL administrated into PVL-MRSA-infected macrophages caused the autophagy of macrophage. Exogenous rPVL, particularly A-Luk S-PV, administrated into macrophages also caused the autophagy of macrophage, which was reversed by PMX53, a C5aR antagonist. In a mouse pneumonia model, PVL-MRSA could induced the autophagy of macrophages, which in turn reduced the damage from macrophages, which were respectively alleviated by 3-MA or linezolid. In conclusion, this study indicated PVL-MRSA regulated macrophage autophagy, which in turns inhibit the phagocytosis of S. aureus by macrophage. This study may provide a potential target against S. aureus infection.
Topics: Animals; Autophagy; Bacterial Toxins; Exotoxins; Leukocidins; Linezolid; Macrophages; Methicillin-Resistant Staphylococcus aureus; Mice; Staphylococcal Infections; Staphylococcus aureus
PubMed: 35552111
DOI: 10.1016/j.imbio.2022.152223 -
BioFactors (Oxford, England) 2014Macrophages are among the first cellular actors facing the invasion of microorganisms. These cells are able to internalize pathogens and destroy them by means of toxic... (Review)
Review
Macrophages are among the first cellular actors facing the invasion of microorganisms. These cells are able to internalize pathogens and destroy them by means of toxic mediators, many of which are produced enzymatically and have strong oxidizing capacity. Indeed, macrophages count on the NADPH oxidase complex activity, which is triggered during pathogen invasion and leads to the production of superoxide radical inside the phagosome. At the same time, the induction of nitric oxide synthase results in the production of nitric oxide in the cytosol which is able to readily diffuse to the phagocytic vacuole. Superoxide radical and nitric oxide react at diffusion controlled rates with each other inside the phagosome to yield peroxynitrite, a powerful oxidant capable to kill micro-organisms. Peroxynitrite toxicity resides on oxidations and nitrations of biomolecules in the target cell. The central role of peroxynitrite as a key effector molecule in the control of infections has been proven in a wide number of models. However, some microorganisms and virulent strains adapt to survive inside the potentially hostile oxidizing microenvironment of the phagosome by either impeding peroxynitrite formation or rapidly detoxifying it once formed. In this context, the outcome of the infection process is a result of the interplay between the macrophage-derived oxidizing cytotoxins such as peroxynitrite and the antioxidant defense machinery of the invading pathogens.
Topics: Animals; Host-Pathogen Interactions; Humans; Immunity, Innate; Macrophages; Oxidation-Reduction; Peroxynitrous Acid; Phagocytosis; Phagosomes
PubMed: 24281946
DOI: 10.1002/biof.1150 -
Oncoimmunology 2020Early trials for immune checkpoint inhibitors in sarcomas have delivered mixed results, and efforts to improve outcomes now look to combinatorial strategies with novel...
Early trials for immune checkpoint inhibitors in sarcomas have delivered mixed results, and efforts to improve outcomes now look to combinatorial strategies with novel immunotherapeutics, including some that target macrophages. To enhance our understanding of the sarcoma immune landscape, we quantified and characterized tumor-associated macrophage infiltration and expression of the targetable macrophage-related immune checkpoint CD47/SIRPα across sarcoma types. We surveyed immunohistochemical expression of CD68, CD163, CD47, and SIRPα in tissue microarrays of 1242 sarcoma specimens (spanning 24 types). Non-translocation sarcomas, particularly undifferentiated pleomorphic sarcoma and dedifferentiated liposarcoma, had significantly higher counts of both CD68+ and CD163+ macrophages than translocation-associated sarcomas. Across nearly all sarcoma types, macrophages outnumbered tumor-infiltrating lymphocytes and CD163+ (M2-like) macrophages outnumbered CD68+ (M1-like) macrophages. These findings were supported by data from The Cancer Genome Atlas, which showed a correlation between increasing macrophage contributions to immune infiltration and several measures of DNA damage. CD47 expression was bimodal, with most cases showing either 0% or >90% tumor cell staining, and the highest CD47 scores were observed in chordoma, angiosarcoma, and pleomorphic liposarcoma. SIRPα scores correlated well with CD47 expression. Given the predominance of macrophage infiltrates over tumor-infiltrating lymphocytes, the bias toward M2-like (immunosuppressive) macrophage polarization, and the generally high scores for CD47 and SIRPα, macrophage-focused immunomodulatory agents, such as CD47 or IDO-1 inhibitors, may be particularly worthwhile to pursue in sarcoma patients, alone or in combination with lymphocyte-focused agents.
Topics: Humans; Lymphocytes, Tumor-Infiltrating; Macrophages; Receptors, Immunologic; Sarcoma; Tumor-Associated Macrophages
PubMed: 32313727
DOI: 10.1080/2162402X.2020.1747340 -
Archives of Histology and Cytology 1990The normal role that the macrophage plays in tissue homeostasis is presented along with the morphological and functional changes that occur to the macrophage population... (Review)
Review
The normal role that the macrophage plays in tissue homeostasis is presented along with the morphological and functional changes that occur to the macrophage population as the lymphoedema progresses from the latent to the chronic phase and then with the treatment with a representative benzopyrone called coumarin. Underlying the lymphoedema, there is a chronic inflammation. It is this, in association with the accumulating protein and the subsequent alterations it produces in the tissues that attract monocytes and macrophages to the affected area. Despite the fact that macrophages are facultative anaerobes, and that larger numbers than normal accumulate, the tissue conditions result in a depression in their activity levels. Apart from these tissue conditions there is the possible production of deactivating proteins such as transforming growth factor beta 1 and 2. Evidence for this deactivation comes from enzymatic studies in which levels of typical macrophage enzymes are reduced and from morphological work which has shown a reduction in pseudopods and a tendency to accumulate large amounts of lipid in their vacuoles. As a consequence of this deactivation further protein accumulation occurs thereby osmotically attracting fluid. Also there is a tendency for the tissues to become fibrotic as the balance between collagen lysis and deposition shifts towards the latter since it has been shown that macrophages have an important role in collagen lysis. The administration of coumarin stimulates the macrophages resulting to their return to normal or supranormal activity levels within the lymphoedematous tissues. As well as this there is an increase in macrophage numbers. The reasons for stimulation are uncertain, however, alterations in the fine structure of the proteins and complement which make these more attractive for phagocytosis seem the most likely. The end result is an rapid enhanced breakup of the excess interstitial protein and the removal of the osmotically attracted fluid together with a more gradual removal of the deposits of fibrotic tissue by the non-stimulated macrophage. Clinically this manifests itself as a softening of the tissues, a reduction in circumference of the lymphoedematous extremity, a return to normal tissue remodelling processes and a range of subjective improvements for the patient.
Topics: Animals; Cell Count; Coumarins; Humans; Lymphedema; Macrophages
PubMed: 2252630
DOI: 10.1679/aohc.53.suppl_209 -
Scientific Reports Jan 2023Even when treated comprehensively by surgery, chemotherapy, and radiotherapy, soft-tissue sarcoma has an unfavorable outcome. Because soft-tissue sarcoma is rare, it is...
Even when treated comprehensively by surgery, chemotherapy, and radiotherapy, soft-tissue sarcoma has an unfavorable outcome. Because soft-tissue sarcoma is rare, it is the subject of fewer clinicopathological studies, which are important for clarifying pathophysiology. Here, we examined tumor-associated macrophages in the intratumoral and marginal areas of sarcomas to increase our knowledge about the pathophysiology. Seventy-five sarcoma specimens (not limited to a single histological type), resected at our institution, were collected, and the number of CD68-, CD163-, and CD204-positive macrophages in the intratumoral and marginal areas was counted. We then performed statistical analysis to examine links between macrophage numbers, clinical factors, and outcomes. A high number of macrophages positive for all markers in both areas was associated with worse disease-free survival (DFS). Next, we divided cases according to the FNCLCC classification (Grade 1 and Grades 2/3). In the Grade 1 group, there was no significant association between macrophage number and DFS. However, in the Grade 2/3 group, high numbers of CD163- and CD204-positive macrophages in the marginal area were associated with poor DFS. By contrast, there was no significant difference between the groups with respect to high or low numbers of CD68-, CD163-, or CD204-positive macrophages in the intratumoral area. Multivariate analysis identified the number of CD163- and CD204-positive macrophages in the marginal area as an independent prognostic factor. Macrophage numbers in the marginal area of soft-tissue sarcoma may better reflect clinical behavior.
Topics: Humans; Prognosis; Macrophages; Soft Tissue Neoplasms; Antigens, Differentiation, Myelomonocytic; Sarcoma
PubMed: 36690825
DOI: 10.1038/s41598-023-28024-1 -
Journal of Visualized Experiments : JoVE Feb 2022Quantification of cells is necessary for a wide range of biological and biochemical studies. Conventional image analysis of cells typically employs either fluorescence...
Quantification of cells is necessary for a wide range of biological and biochemical studies. Conventional image analysis of cells typically employs either fluorescence detection approaches, such as immunofluorescent staining or transfection with fluorescent proteins or edge detection techniques, which are often error-prone due to noise and other non-idealities in the image background. We designed a new algorithm that could accurately count and distinguish macrophages and fibroblasts, cells of different phenotypes that often colocalize during tissue regeneration. MATLAB was used to implement the algorithm, which differentiated distinct cell types based on differences in height from the background. A primary algorithm was developed using an area-based method to account for variations in cell size/structure and high-density seeding conditions. Non-idealities in cell structures were accounted for with a secondary, iterative algorithm utilizing internal parameters such as cell coverage computed using experimental data for a given cell type. Finally, an analysis of coculture environments was carried out using an isolation algorithm in which various cell types were selectively excluded based on the evaluation of relative height differences within the image. This approach was found to accurately count cells within a 5% error margin for monocultured cells and within a 10% error margin for cocultured cells.
Topics: Algorithms; Coculture Techniques; Fibroblasts; Image Processing, Computer-Assisted; Macrophages
PubMed: 35253803
DOI: 10.3791/63058 -
Current Medical Science Aug 2023Tumor-associated macrophages (TAMs) of the M2 phenotype are frequently associated with cancer progression. Invasive cancer cells undergoing epithelial-mesenchymal...
OBJECTIVE
Tumor-associated macrophages (TAMs) of the M2 phenotype are frequently associated with cancer progression. Invasive cancer cells undergoing epithelial-mesenchymal transition (EMT) have a selective advantage as TAM activators. Cyclin D1b is a highly oncogenic splice variant of cyclin D1. We previously reported that cyclin D1b enhances the invasiveness of breast cancer cells by inducing EMT. However, the role of cyclin D1b in inducing macrophage differentiation toward tumor-associated macrophage-like cells remains unknown. This study aimed to explore the relationship between breast cancer cells overexpressing cyclin D1b and TAMs.
METHODS
Mouse breast cancer 4T1 cells were transfected with cyclin D1b variant and co-cultured with macrophage cells in a Transwell coculture system. The expression of characteristic cytokines in differentiated macrophages was detected using qRT-PCR, ELISA and zymography assay. Tumor-associated macrophage distribution in a transplanted tumor was detected by immunofluorescence staining. The proliferation and migration ability of breast cancer cells was detected using the cell counting kit-8 (CCK-8) assay, wound healing assay, Transwell invasion assay, and lung metastasis assay. Expression levels of mRNAs were detected by qRT-PCR. Protein expression levels were detected by Western blotting. The integrated analyses of The Cancer Genome Atlas (TCGA) datasets and bioinformatics methods were adopted to discover gene expression, gene coexpression, and overall survival in patients with breast cancer.
RESULTS
After co-culture with breast cancer cells overexpressing cyclin D1b, RAW264.7 macrophages were differentiated into an M2 phenotype. Moreover, differentiated M2-like macrophages promoted the proliferation and migration of breast cancer cells in turn. Notably, these macrophages facilitated the migration of breast cancer cells in vivo. Further investigations indicated that differentiated M2-like macrophages induced EMT of breast cancer cells accompanied with upregulation of TGF-β1 and integrin β3 expression.
CONCLUSION
Breast cancer cells transfected with cyclin D1b can induce the differentiation of macrophages into a tumor-associated macrophage-like phenotype, which promotes tumor metastasis in vitro and in vivo.
Topics: Animals; Mice; Tumor-Associated Macrophages; Macrophages; Lung Neoplasms; Cell Differentiation; Phenotype
PubMed: 37391677
DOI: 10.1007/s11596-023-2762-1