Evaluation of the phenotype pattern of macrophages isolated from malignant and non-malignant pleural effusions

Isolation of mouse mammary carcinoma-derived macrophages and cancer cells for co-culture assays

We recently established an in vitro co-culture system in which monophosphoryl lipid A + interferon-γ (MPLA+IFNγ)-treated tumor-associated macrophages (TAMs) killed cancer cells. Here, we describe a step-by-step protocol for isolating TAMs and cancer cells from mouse primary mammary carcinomas, the setup of the co-culture system, and the image acquisition approach. The technical difficulties in the co-culture assay involve isolating pure TAMs and cancer cells from the same tumor and staining them with different dyes to track the macrophages' tumoricidal activity. For complete details on the use and execution of this protocol, please refer to Sun et al. (2021).¹.

Erythritol modulates the polarization of macrophages: Potential role of tumor necrosis factor-α and Akt pathway

Low-calorie sweeteners are substitutes for sugar and frequently used by patients with cardiometabolic diseases. Erythritol, a natural low-calorie sugar alcohol, was linked to cardiometabolic diseases in several recent metabolomics studies. However, the characterization of its role in disease development is lacking. Macrophage polarization orchestrates the immune response in various inflammatory conditions, most notably cardiometabolic disease. Therefore, the physiological effects of Erythritol on THP-1 macrophages were investigated. We observed an increased cellular abundance of proinflammatory M1 macrophages, characterized by CD11c, TNF-α, CD64, CD38, and HLA-DR markers and decreased anti-inflammatory M2 macrophages, characterized by mannose receptor CD206. The, Erythritol increased ROS generation, and the activation of the AKT pathway, cytosolic calcium overload, and cell cycle arrest at the G1 phase. Concomitantly, an increased population of necroptotic macrophages was observed. In conclusion, we provide evidence that Erythritol induced the proinflammatory phenotype in THP-1 macrophages and this was associated with an increased population of necroptotic macrophages. PRACTICAL APPLICATIONS: This assessment provides evidence of the effects of Erythritol on macrophages, particularly THP-1-derived macrophages. Our results support the role of Erythritol in driving the inflammation that is associated with cardiometabolic diseases and provide insights in the role of Erythritol as an inducer of necroptosis in THP-1 derived macrophages that could be associated the disease.

Macrophage M1/M2 ratio as a predictor of pleural thickening in patients with tuberculous pleurisy

We evaluated the association between macrophage polarization and the development of pleural thickening in patients with tuberculous pleurisy. Patients with tuberculous pleurisy admitted to our hospital between October 2018 and March 2019 were prospectively recruited. Pleural fluid samples were obtained before treatment for detection of adenosine deaminase (ADA) and macrophage phenotype (M1: CD14+ CD86+; M2: CD14+ CD163+). Peripheral blood samples were subjected to interferon gamma release assay (IGRA). All subjects were administered standard anti-tuberculosis regimen (2HREZ/4HR); high-resolution CT was performed to determine pleural thickening (thickness>2mm) after completion of treatment. Pleural effusion in patients with thickened pleura had significantly more M1 but fewer M2 macrophages, and higher ADA level, as compared to those with normal pleura (P<0.05). No significant between-group difference was observed with respect to IGRA. In receiver operating characteristic (ROC) curve analysis, the optimal cut-off level of M1/M2 ratio for predicting pleural thickening was 1.149 (area under the curve: 0.842; sensitivity: 88.6%; specificity: 69.2%; positive predictive value: 86.3%; negative predictive value: 81.7%). M1/M2 ratio in the pleural fluid is a promising marker for predicting the development of pleural thickening in patients with tuberculous pleurisy. Macrophage-mediated immune response may play an important role in the pathogenesis of tuberculous pleurisy.

Efferocytosis fuels malignant pleural effusion through TIMP1

Malignant pleural effusion (MPE) results from the capacity of several human cancers to metastasize to the pleural cavity. No effective treatments are currently available, reflecting our insufficient understanding of the basic mechanisms leading to MPE progression. Here, we found that efferocytosis through the receptor tyrosine kinases AXL and MERTK led to the production of interleukin-10 (IL-10) by four distinct pleural cavity macrophage (Mφ) subpopulations characterized by different metabolic states and cell chemotaxis properties. In turn, IL-10 acts on dendritic cells (DCs) inducing the production of tissue inhibitor of metalloproteinases 1 (TIMP1). Genetic ablation of Axl and Mertk in Mφs or IL-10 receptor in DCs or Timp1 substantially reduced MPE progression. Our results delineate an inflammatory cascade-from the clearance of apoptotic cells by Mφs, to production of IL-10, to induction of TIMP1 in DCs-that facilitates MPE progression. This inflammatory cascade offers a series of therapeutic targets for MPE.

Single-cell RNA sequencing demonstrates the molecular and cellular reprogramming of metastatic lung adenocarcinoma

Advanced metastatic cancer poses utmost clinical challenges and may present molecular and cellular features distinct from an early-stage cancer. Herein, we present single-cell transcriptome profiling of metastatic lung adenocarcinoma, the most prevalent histological lung cancer type diagnosed at stage IV in over 40% of all cases. From 208,506 cells populating the normal tissues or early to metastatic stage cancer in 44 patients, we identify a cancer cell subtype deviating from the normal differentiation trajectory and dominating the metastatic stage. In all stages, the stromal and immune cell dynamics reveal ontological and functional changes that create a pro-tumoral and immunosuppressive microenvironment. Normal resident myeloid cell populations are gradually replaced with monocyte-derived macrophages and dendritic cells, along with T-cell exhaustion. This extensive single-cell analysis enhances our understanding of molecular and cellular dynamics in metastatic lung cancer and reveals potential diagnostic and therapeutic targets in cancer-microenvironment interactions.

Pleural or pericardial metastasis: A significant factor affecting efficacy and adverse events in lung cancer patients treated with PD-1/PD-L1 inhibitors

Background

Immunotherapy is a new paradigm for the treatment of non‐small‐cell lung cancer (NSCLC), and targeting the PD‐1 or PD‐L1 pathway is a promising therapeutic option. Although PD‐1/PD‐L1 inhibitors are more effective than standard chemotherapy in lung cancer, clinicians are afraid to actively use them because of hyperprogression and pseudoprogression. The aim of this study was to investigate the factors associated with tumor response and serious outcomes.

Methods

We retrospectively collected the medical records of 51 patients with advanced NSCLC who received PD‐1/PD‐L1 inhibitors between January 2016 and February 2018.

Results

The mean patient age was 63.9 years, and 72.5% (37/51) were male. Most (92.2%, 47/51) had received previous systemic treatment. The overall response rate was 21.6% (11/51). The response rate was significantly lower in patients with pleural or pericardial metastasis than in patients without pleural or pericardial metastasis (4.3% vs. 35.7%; P = 0.007). Patients with pleural or pericardial metastasis had a significantly higher rate of adverse events of any grade (91.3% vs. 50.0%; P = 0.002) and grade 3–5 adverse events (52.2% vs. 25.0%; P = 0.046).

Conclusion

Pleural or pericardial metastasis is a significant factor affecting the efficacy and rate of adverse events in advanced NSCLC patients treated with PD‐1/PD‐L1 inhibitors. Clinicians should pay attention to the use of immune checkpoint inhibitors in lung cancer patients with pleural or pericardial metastasis.

MiR-98 modulates macrophage polarization and suppresses the effects of tumor-associated macrophages on promoting invasion and epithelial-mesenchymal transition of hepatocellular carcinoma

BACKGROUND

Tumor-associated macrophages (TAMs) are generally recognized as a promoter of tumor progression. miR-98 has been shown to suppress the proliferation, migration, invasion and epithelial-mesenchymal transition (EMT) of hepatocellular carcinoma (HCC) cells. Here, we aim to investigate the role of miR-98-mediated macrophage polarization in HCC progression.

METHODS

Human blood monocytes were isolated from healthy male donors and incubated with culture medium collected from HepG2 cells for 7 days. The phenotype of the macrophages was detected. The protein expression was detected by Western blot. Levels of cytokines secreted in culture medium were measured using the specific enzyme-linked immunosorbent assay kits. To explore the role of miR-98 in HCC-conditioned TAMs, HCC cells HepG2 and SMMC7721 were cultured with conditioned medium from HCC-conditioned TAMs that had been transfected with miR-98 mimic/inhibitor. Cell proliferation, migration and invasion assays were performed.

RESULTS

HCC-conditioned TAMs possessed M2-like phenotype, including increased protein expression of CD163 and TNF-αlow, IL-1βlow, TGF-βhigh and IL-10high phenotype. HCC-conditioned TAMs also promoted proliferation, migration, invasion and EMT of HepG2 and SMMC7721 cells. Furthermore, miR-98 modulated macrophage polarization from M2 to M1 in HCC-conditioned TAMs, as evidenced by the alteration of M1- or M2-related cytokines. Moreover, miR-98 mimic significantly suppressed the HCC-conditioned TAMs-mediated promotion of cell migration, invasion and EMT in HepG2 and SMMC7721 cells compared with negative control, whereas miR-98 inhibitor exerted reversed effects.

CONCLUSIONS

miR-98 may play a vital role in regulating macrophage polarization, thereby suppressing the TAMs-mediated promotion of invasion and EMT in HCC.

Enhanced Suppressive Activity of Regulatory T Cells in the Microenvironment of Malignant Pleural Effusions

Cancer metastatic spread to serous cavity causes malignant pleural effusions (MPEs), indicating dismal prognosis. Tumor microenvironment can implement suppressive activity on host immune responses. Thus, we investigated the prevalence of Tregs and the relationship between them and TGF-β and IL-10 concentrations and measured expression of FOXP3, CTLA-4, CD28, and GITR genes, as well as protein expression of selected genes in benign effusions and MPEs. The percentage of Tregs was determined by means of multicolor flow cytometry system. TGF-β and IL-10 concentrations were measured using human TGF-β1 and IL-10 ELISA kit. Relative mRNA expression of studied genes was analyzed by real-time PCR. The frequency of Tregs was significantly higher in MPEs compared to benign effusions; however, the level of TGF-β and IL-10 in analyzed groups was comparable, and no correlation between concentrations of TGF-β and IL-10 and percentage of Tregs was observed. Relative mRNA expression of all the genes was higher in CD4⁺CD25⁺ compared to CD4⁺CD25⁻ cells. In CD4⁺CD25⁺ cells from MPEs, relative mRNA expression of FOXP3, CTLA-4, and CD28 genes was significantly higher than in benign effusions; however, the level of CD4⁺CD25⁺CTLA-4⁺ cells in analyzed groups showed no significant differences. We found numerous genes correlations in an entire CD4⁺CD25⁺ cell subset and CD4⁺CD25⁺ cells from MPEs. Enhanced suppressive activity of Tregs is observed in the microenvironment of MPEs. Understanding of relations between cellular and cytokine immunosuppressive factors in tumor microenvironment may determine success of anticancer response.

Concentrations of SP-A and HSP70 are associated with polarization of macrophages in pleural effusions of non-small cell lung cancer

Damage-associated molecular pattern (DAMP) molecules can initiate an immune response through Toll-like receptors (TLRs). DAMPs are released from cells as a response to the extracellular danger and can be by-products of tissue damage. In cancer microenvironment necrotic cells release debris which has potency to become DAMPs. Non-small cell lung cancer (NSCLC) is often accompanied by pleural effusion (PE), which contains a variety of DAMPs. Surfactant protein A (SP-A) and heat shock protein 70 (Hsp70) are important DAMPs in the respiratory tract. The aim of this study was to determine a correlation between SP-A or Hsp70 and development of PE in the course of NSCLC. Moreover, we aimed to determine relationships between DAMPs and certain humoral factors associated with formation and persistence of PE as well as pleural-residing macrophages. In 34 PE samples, we estimated concentration of SP-A, Hsp70, IL-6, IL-18, G-CSF, M-CSF, SCF, SDF1α, VEGF as well as the fraction of macrophages and their pattern of polarization. We have found correlations between the concentration of the SP-A and Hsp70 and the percentage of PE-derived macrophages, also between concentrations of SP-A and Hsp70, and cytokines which participate in inflammation and processes involved in remodeling of extracellular matrix (ECM). Our data indicate an important role of SP-A during the development of PE associated with NSCLC. We suggest that measurement of concentration level of SP-A can be helpful in the course of diagnosis of malignant PE associated with NSCLC.

Malignant Nonhematological Effusion Characterization by Flow Cytometry

With the exception of hematological malignancies, flow cytometry (FC) is infrequently applied as an ancillary tool in the diagnosis of malignant effusions in most institutions. However, FC may be effectively used to differentiate between epithelial cells, mesothelial cells and leukocytes using antibodies against both cell surface and intracellular proteins, offering the advantage of quantitative analysis. Additionally, FC may be applied to the quantitative detection of cancer-associated molecules, including stem cell markers, as well as assessment of critical cellular processes, such as proliferation and apoptosis. Some of the latter tests may have relevance for monitoring treatment response in the presence of metastatic disease, although this does not constitute routine practice to date. This review summarizes current knowledge regarding the application of FC to serous effusions in the diagnostic setting, as well as in research into cancer biology focusing on clinical specimens. The studies published to date suggest a role for this method in the clinical setting in the context of diagnosis, prediction and prognosis.

Precision immunotherapy; dynamics in the cellular profile of pleural effusions in malignant mesothelioma patients

OBJECTIVES

Clinical studies have proven the potential of immunotherapy in malignancies. To increase efficacy, a prerequisite is that treatment is tailored, so precision immune-oncology is the logical next step. In order to tailor treatment, characterization of the patient's tumor environment is key. Pleural effusion (PE) often accompanies malignant pleural mesothelioma (MPM) and is an important part of the MPM environment. Furthermore, the composition of PE is used as surrogate for the tumor. In this study, we provide an insight in the dynamics of the MPM environment through characterization of PE composition over time and show that the immunological characteristics of PE do not necessarily mirror those of the tumor.

MATERIALS AND METHODS

From 5 MPM patients, PE and tumor biopsies were acquired at the same time point. From one of these patients multiple PEs were obtained. PEs were acquired performing thoracocenteses and total cell amounts were determined. Immunohistochemistry was performed to quantify immune cell composition (T cells, macrophages) and tumor cells in PE derived cytospins and tumor biopsies.

RESULTS

The PE amount and (immune) cellular composition varied considerably over time between multiple (n=10) thoracocenteses. These dynamics could in part be attributed to the treatment regimen consisting of standard chemotherapy and dendritic cell (DC)-based immunotherapy. In addition, the presence of T cells and macrophages in PE did not necessarily mirror the infiltration of these immune cells within tumor biopsies in 4 out of 5 patients.

CONCLUSIONS

In this proof-of-concept study with limited sample size, we demonstrate that the composition of PE is dynamic and influenced by treatment. Furthermore, the immune cell composition of PE does not automatically reflect the properties of tumor tissue. This has major consequences when applying precision immunotherapy based on PE findings in patients. Furthermore, it implies a regulated trafficking of immune regulating cells within the tumor environment.

Differences in the distribution, phenotype and gene expression of subretinal microglia/macrophages in C57BL/6N (Crb1 rd8/rd8) versus C57BL6/J (Crb1 wt/wt) mice

Background

Microglia/macrophages (MG/MΦ) are found in the subretinal space in both mice and humans. Our goal was to study the spatial and temporal distribution, the phenotype, and gene expression of subretinal MG/MΦ in mice with normal retinas and compare them to mice with known retinal pathology.

Methods

We studied C57BL/6 mice with (C57BL/6N), or without (C57BL/6J) the rd8 mutation in the Crb1 gene (which, in the presence of yet unidentified permissive/modifying genes, leads to a retinal degeneration), and documented their fundus appearance and the change with aging. Immunostaining of retinal pigment epithelium (RPE) flat mounts was done for 1) Ionized calcium binding adaptor (Iba)-1, 2) FcγIII/II Receptor (CD16/CD32, abbreviated as CD16), and 3) Macrophage mannose receptor (MMR). Reverse-transcription quantitative PCR (RT-qPCR) was done for genes involved in oxidative stress, complement activation and inflammation.

Results

The number of yellow fundus spots correlated highly with subretinal Iba-1+ cells. The total number of subretinal MG/MΦ increased with age in the rd8 mutant mice, but not in the wild-type (WT) mice. There was a centripetal shift in the distribution of the subretinal MG/MΦ with age. Old rd8 mutant mice had a greater number of CD16+ MG/MΦ. CD16+ cells had morphological signs of activation, and this was most prominent in old rd8 mutant mice (P <1×10⁻⁸ versus old WT mice). Subretinal MG/MΦ in rd8 mutant mice also expressed iNOS and MHC-II, and had ultrastructural signs of activation. Finally, rd8 mutant mouse RPE/ MG/MΦ RNA isolates showed an upregulation of Ccl2, CFB, C3, NF-kβ, CD200R and TNF-alpha. The retinas of rd8 mutant mice showed upregulation of HO-1, C1q, C4, and Nrf-2.

Conclusions

When compared to C57BL/6J mice, C57BL/6N mice demonstrate increased accumulation of subretinal MG/MΦ, displaying phenotypical, morphological, and gene-expression characteristics consistent with a pro-inflammatory shift. These changes become more prominent with aging and are likely due to the combination of the rd8 mutation and yet unidentified permissive/modulatory genes in the C57BL/6N mice. In contrast, aging leads to a scavenging phenotype in the C57BL/6J subretinal microglia/macrophages.

Electronic supplementary material

The online version of this article (doi:10.1186/s12974-014-0221-4) contains supplementary material, which is available to authorized users.

Different subsets of macrophages in patients with new onset tuberculous pleural effusion

OBJECTIVE

Macrophages are the infiltrate components of tuberculous pleural effusion (TPE). This study is aimed at examining the role of different subsets of macrophages in pleural fluid (PF) and peripheral blood (PB) from patients with new onset TPE.

METHODS

The numbers of PB and PF CD163(+), CD206(+) and CD115(+) macrophages in 25 patients with new onset TPE and 17 healthy controls (HC) were determined by flow cytometry. The concentrations of serum and PF cytokines were determined by cytometric bead array (CBA) and enzyme-linked immunosorbentassay (ELISA). The potential association between the numbers of different subsets of macrophages and the values of clinical measures in TPE patients were analyzed.

RESULTS

The numbers of PB CD14(+)CD163(-) M1-like and CD14(+)CD163(-) interleukin (IL)-12(+) M1 macrophages were significantly higher than that in the HC, but lower than PF, and the numbers of PF CD14(+)CD163(+), CD14(+)CD163(+)CD206(+), CD14(+)CD163(+)CDll5(+) M2-like, and CD14(+)CD163(+)IL-10(+) M2 macrophages were less than PB in the TPE patients. The levels of serum IL-1, IL-6, IL-8, IL-12, tumor growth factor (TGF)-β1, and tumor necrosis factor (TNF)-α in the TPE patients were significantly higher than that in the HC, but lower than that in the PF. The levels of PF IL-10 were significantly higher than that in the PB of patients and HC. In addition, the levels of serum IL-12 and TNF-α were correlated positively with the values of erythrocyte sedimentation rate (ESR) and the numbers of ESAT-6- and culture filtrate protein 10 (CFP-10)-specific IFN-γ-secreting T cells, and the levels of PF TNF-α were correlated positively with the levels of PF adenosine deaminase (ADA) and lactate dehydrogenase (LDH) in those patients.

CONCLUSION

Our data indicate that Mycobacterium tuberculosis (M. tb) infection induces M1 predominant pro-inflammatory responses, contributing to the development of TPE in humans.

TLR2 in pleural fluid is modulated by talc particles during pleurodesis

The aim of this study was to examine the role of TLR2 molecule in pleural space during thoracoscopic talc pleurodesis period in patients with malignant pleural effusion. We analyzed TLR2 molecule in soluble form as well as on membrane of granulocytes in pleural fluid. Pleural fluid examination was done at three intervals during pleurodesis procedure: 1st—before the thoracoscopic procedure, 2nd—2 hours after the terminating thoracoscopic procedure with talc insufflation, 3rd—24 hours after the thoracoscopic procedure. We reported significant increase of soluble TLR2 molecule in pleural fluid effusion during talc pleurodesis from preoperative value. This increase was approximately 8-fold in the interval of 24 hours. The changes on granulocyte population were quite different. The mean fluorescent intensity of membrane TLR2 molecule examined by flow cytometry on granulocyte population significantly decreased after talc exposure with comparison to prethoracoscopic density. To estimate the prognostic value of TLR2 expression in pleural fluid patients were retrospectively classified into either prognostically favourable or unfavourable groups. Our results proved that patients with favourable prognosis had more than 3-fold higher soluble TLR2 level in pleural fluid early, 2 hours after talc pleurodesis intervention.

Macrophages in malignant pleural effusions - alternatively activated tumor associated macrophages

Pleural macrophages are involved in local defense mechanisms against environmental pollution, bacteria and cancer. Their main function encompasses phagocytosis of degenerated mesothelial cells. In human pleural effusions macrophages represent more than half of all cells. A model of polarized macrophage activation (M1 and M2) was proposed, which defines a functionally different macrophage populations generated in response to various factors present in the inflamed environment. Tumor associated macrophages are a major component of the inflammatory infiltrate of most cancers. They can promote the proliferation and spread of cancer cells in the early stages of carcinogenesis and during metastasis. Macrophages isolated from malignant pleural effusions as well as tumor associated macrophages exhibit weak cytotoxic activity against tumor cells, increase their proliferative activity and may protect tumor cells from apoptosis. Defining biology of macrophages present in specific environment of the pleural effusion could allow the introduction of innovative diagnostic and therapeutic strategies.

Increased microglia/macrophage gene expression in a subset of adult and pediatric astrocytomas

Glioblastoma (GBM) is a highly malignant brain tumor with a dismal prognosis. Gene expression profiling of GBM has revealed clinically relevant tumor subtypes, and this provides exciting opportunities to better understand disease pathogenesis. Results from an increasing number of studies demonstrate a role for the immune response in cancer progression, yet it is unclear how the immune response differs across tumor subtypes and how it affects outcome. Utilizing gene expression data from The Cancer Genome Atlas Project and the Gene Expression Omnibus database, we demonstrate an enrichment of immune response-related gene expression in the mesenchymal subtype of adult GBM (n = 173) and pediatric high-grade gliomas (n = 53). In an independent cohort of pediatric astrocytomas (n = 24) from UCSF, we stratified tumors into subtypes and confirmed these findings. Using novel immune cell-specific gene signatures we demonstrate selective enrichment of microglia/macrophage-related genes in adult and pediatric GBM tumors of the mesenchymal subtype. Furthermore, immunostaining of adult GBM tumors showed significantly higher cell numbers of microglia/macrophages in mesenchymal versus non-mesenchymal tumors (p = 0.04). Interestingly, adult GBM tumors with the shortest survival had significant enrichment of microglia/macrophage-related genes but this was not true for pediatric GBMs. Consistent with an association with poor outcome, immune response-related genes were highly represented in an adult poor prognosis gene signature, with the expression of genes related to macrophage recruitment and activation being most strongly associated with survival (p<0.05) using CoxBoost multivariate modeling. Using a microglia/macrophage high gene signature derived from quantification of tumor-infiltrating cells in adult GBM, we identified enrichment of genes characteristic of CD4 T cells, granulocytes, and microglia/macrophages (n = 573). These studies support a role for the immune response, particularly the microglia/macrophage response, in the biology of an important subset of GBM. Identification of this subset may be important for future therapeutic stratification.