Bulk Gene Expression Deconvolution Reveals Infiltration of M2 Macrophages in Retinal Neovascularization

The osseointegration is the stable and functional union between the bone and a titanium surface. A new bone can be found on the surface of the implant about 1 week after its installation; the bone remodeling begins between 6 and 12 weeks and continues throughout life. After the implant insertion, depending on the energy of the surface, the plasma fluid immediately adheres, in close contact with the surface, promoting the adsorption of proteins and inducing the indirect interaction of the cells with the material. Macrophages are cells found in the tissues and originated from bone marrow monocytes. The M1 macrophages orchestrate the phagocytic phase in the inflammatory region and also produce inflammatory cytokines involved with the chronic inflammation and the cleaning of the wound and damaged tissues from bacteria. On the other hand, alternative-activated macrophages (M2) are activated by IL-10, the immune complex. Its main function consists on regulating negatively the inflammation through the secretion of the immunosuppressant IL-10. The M2 macrophages present involvement with the immunosuppression, besides having a low capacity for presenting antigens and high production of cytokines; these can be further divided into M2a, M2b, and M2c, based on the gene expression profile.

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The inflammation-resolution promoting molecule resolvin-D1 prevents atrial proarrhythmic remodelling in experimental right heart disease

Cardiovascular Research ◽

10.1093/cvr/cvaa186 ◽

2020 ◽

Cited By ~ 2

Author(s):

Roddy Hiram ◽

Feng Xiong ◽

Patrice Naud ◽

Jiening Xiao ◽

Martin Sirois ◽

...

Keyword(s):

Gene Expression ◽

Heart Disease ◽

M2 Macrophages ◽

Gene Microarray ◽

Resolvin D1 ◽

Right Heart ◽

M1 Macrophages ◽

Anti Inflammatory ◽

Inflammation Resolution ◽

Inflammatory Signalling

Abstract Aims Inflammation plays a role in atrial fibrillation (AF), but classical anti-inflammatory molecules are ineffective. Recent evidence suggests that failure of inflammation-resolution causes persistent inflammatory signalling and that a novel drug-family called resolvins promotes inflammation-resolution. Right heart disease (RHD) is associated with AF; experimental RHD shows signs of atrial inflammatory-pathway activation. Here, we evaluated resolvin-therapy effects on atrial arrhythmogenic remodelling in experimental RHD. Methods and results Pulmonary hypertension and RHD were induced in rats with an intraperitoneal injection of 60 mg/kg monocrotaline (MCT). An intervention group received daily resolvin-D1 (RvD1), starting 1 day before MCT administration. Right atrial (RA) conduction and gene-expression were analysed respectively by optical mapping and qPCR/gene-microarray. RvD1 had no or minimal effects on MCT-induced pulmonary artery or right ventricular remodelling. Nevertheless, in vivo transoesophageal pacing induced atrial tachyarrhythmias in no CTRL rats vs. 100% MCT-only rats, and only 33% RvD1-treated MCT rats (P < 0.001 vs. MCT-only). Conduction velocity was significantly decreased by MCT, an effect prevented by RvD1. RHD caused RA dilation and fibrosis. RvD1 strongly attenuated RA fibrosis but had no effect on RA dilation. MCT increased RA expression of inflammation- and fibrosis-related gene-expression pathways on gene-microarray transcriptomic analysis, effects significantly attenuated by RvD1 (334 pathways enriched in MCT-rats vs. control; only 177 dysregulated by MCT with RvD1 treatment). MCT significantly increased RA content of type 1 (proinflammatory) CD68-positive M1 macrophages without affecting type 2 (anti-inflammatory) M2 macrophages. RvD1-treated MCT-rat RA showed significant reductions in proinflammatory M1 macrophages and increases in anti-inflammatory M2 macrophages vs. MCT-only. MCT caused statistically significant increases in protein-expression (western blot) of COL3A1, ASC, CASP1, CASP8, IL1β, TGFβ3, CXCL1, and CXCL2, and decreases in MMP2, vs. control. RvD1-treatment suppressed all these MCT-induced protein-expression changes. Conclusion The inflammation-resolution enhancing molecule RvD1 prevents AF-promoting RA remodelling, while suppressing inflammatory changes and fibrotic/electrical remodelling, in RHD. Resolvins show potential promise in combating atrial arrhythmogenic remodelling by suppressing ongoing inflammatory signalling.

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Increased Alternative Macrophage-2 (M2) Polarization with Trib1 Gene over Expression in Myeloma Patients with Progressive Disease and Jak2 Inhibitors Reduce M2 Polarization

Blood ◽

10.1182/blood.v126.23.1011.1011 ◽

2015 ◽

Vol 126 (23) ◽

pp. 1011-1011 ◽

Cited By ~ 1

Author(s):

Haiming Chen ◽

Mingjie Li ◽

Eric Sanchez ◽

Abigail Gillespie ◽

Cathy Wang ◽

...

Keyword(s):

Gene Expression ◽

Tumor Growth ◽

Tumor Cells ◽

Progressive Disease ◽

Scid Mice ◽

Human Monocytes ◽

M2 Macrophages ◽

Jak2 Inhibitor ◽

M2 Polarization ◽

M1 And M2 Macrophages

Abstract Introduction: The bone marrow (BM) microenvironment plays an important role in multiple myeloma (MM). The BM niche is composed of multiple cell types including macrophages. Macrophages polarize into pro-inflammatory macrophage-1 (M1) or alternative M2 states that promote tumor growth and metastasis. We evaluated the proportion of M2 macrophages in BM from MM pts either showing complete response (CR) or progressive disease (PD), the effects of MM cells on M1 and M2 differentiation, and the role of Trib1 in M2 differentiation in MM BM. Since the JAK-STAT signaling pathway plays key roles in macrophages, we also evaluated the effects of the JAK2 inhibitor ruxolitinib (RUX) on M2 polarization in MM. Methods: Using immunofluorescence (IFC), we determined the proportion of M1 and M2 macrophages in BM biopsies and aspirates from MM pts with PD or CR. The BM biopsy samples were stained with antibodies directed against human iNOS and CD86 for M1 and arginase 1(ARG1) and CD36 for M2 cells. MM BM aspirates were also examined using flow cytometric analysis (FCA). Human monocytes isolated from healthy subjects or the THP1 monocyte cell line were co-cultured with MM cell lines (RPMI8226 and U266) or primary MM tumor cells. The effects of RUX at low concentrations (IC20) on M2 polarization were determined. The percentages of M1 and M2 macrophages were determined using FCA. Total RNA was extracted from monocytes. Quantitative PCR was measured with TaqMan technology. For the in vivo studies, human MM tumors (LAGκ-2) were surgically implanted into the left superficial gluteal muscle of SCID mice and tumor volume measured on a weekly basis. Results: The proportion of M2 macrophages (CD36+/ARG1+) was markedly increased in BM biopsies or mononuclear cells from MM pts with PD compared with those in CR using IFC staining. FCA also showed the percentage of M2 macrophages in BM was significantly increased in MM pts with PD (n=25) compared to those in CR (n=10; P=0.005) whereas there was no difference in the percentage of M1 (CD86+/iNOS+) macrophages in BM derived from MM pts with PD compared to those in CR. Trib1 gene mRNA levels were higher among pts with PD compared to those in CR whereas the gene expression of Trib2 and Trib3 was not different. Next, we co-cultured MM cell lines (U266) or fresh MM BMMCs with purified healthy human monocytes for one week. The percentage of M2 cells markedly increased and the proportion of M1 cells decreased. Trib1 gene expression increased during co-culture whereas there was no change in expression of the other two Tribs. When direct cell-to-cell contact occurred between the MM tumor cells and the monocytes, the percentage of M2 macrophages markedly increased. We investigated the effects of the JAK2 inhibitor RUX on M2 differentiation induced with MM tumor cells. After exposure to a low concentration of RUX, the percentage of M2 cells decreased when the monocytes were co-cultured with MM tumor cells. Trib1 gene expression of the monocytes treated with RUX was also notably reduced compared with cells not treated with the JAK2 inhibitor. Using our human MM xenograft model LAGκ-2, RUX (1.5mg/kg) reduced tumor growth and decreased the proportion of M2 macrophages in the tumor tissue of MM tumor-bearing SCID mice. Conclusion: M2 cells are present at high levels in BM derived from MM pts with PD compared to those in CR, MM cells induce monocytes to become M2 macrophages and increase Trib1 gene expression. This induces monocyte differentiation into M2 macrophages that support MM tumor cell growth.. Notably, the JAK2 inhibitor RUX inhibits both M2 macrophage polarization and Trib1 gene expression in MM, and reduces tumor growth in SCID mice bearing human MM. These results suggest that RUX may be effective for treating MM pts. Disclosures No relevant conflicts of interest to declare.

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Tumor evolution of glioma intrinsic gene expression subtype associates with immunological changes in the microenvironment

10.1101/052076 ◽

2016 ◽

Cited By ~ 5

Author(s):

Qianghu Wang ◽

Xin Hu ◽

Baoli Hu ◽

Florian Muller ◽

Hoon Kim ◽

...

Keyword(s):

Gene Expression ◽

Tumor Microenvironment ◽

T Lymphocytes ◽

Intratumoral Heterogeneity ◽

Tumor Evolution ◽

M2 Macrophage ◽

M2 Macrophages ◽

Wild Type ◽

Recurrent Gliomas ◽

Intrinsic Gene

SummaryWe leveraged IDH wild type glioblastomas and derivative neurospheres to define tumor-intrinsic transcription phenotypes. Transcriptomic multiplicity correlated with increased intratumoral heterogeneity and tumor microenvironment presence. In silico cell sorting demonstrated that M2 macrophages/microglia are the most frequent type of immune cells in the glioma microenvironment, followed by CD4 T lymphocytes and neutrophils. Hypermutation associated with CD8+ T cell enrichment. Longitudinal transcriptome analysis of 124 pairs of primary and recurrent gliomas showed expression subtype is retained in 53% of cases with no proneural to mesenchymal transition being apparent. Inference of the tumor microenvironment through gene signatures revealed a decrease in invading monocytes but a subtype dependent increase in M2 macrophages/microglia cells after disease recurrence. All expression datasets are accessible through http://recur.bioinfo.cnio.es/.SignificanceIDH wild type glioblastoma expression phenotypes have been related to tumor characteristics including genomic abnormalities and treatment response. We explored the intratumoral transcriptomic landscape, including a definition of tumor-intrinsic gene expression subtypes and how they relate to the different cellular components of the tumor immune environment. Comparison of matching primary and recurrent gliomas provided insights into the treatment-induced phenotypic tumor evolution. Proneural to mesenchymal transitions have long been suspected but were not apparent, while intratumoral heterogeneity was a predictor of subtype transition upon recurrence. Characterizing the evolving glioblastoma transcriptome en tumor microenvironment aids in designing more effective immunotherapy trials. Our study provides a comprehensive transcriptional and cellular landscape of IDH wild type GBM during treatment modulated tumor evolution.HighlightsNext generation GBM-intrinsic transcriptional subtypes: proneural, classical, mesenchymalM2 macrophages, CD4+ T-lymphocytes and neutrophils dominate glioblastoma microenvironmentSensitivity to radiotherapy may associate with M2 macrophage presenceCD8+ T cells are enriched in hypermutated GBMs at diagnosis and recurrence

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Possibility of tuning the differentiation state of tumor associated macrophages towards tumor controlling phenotypes

10.7287/peerj.preprints.27747v1 ◽

2019 ◽

Author(s):

Wenfa Ng

Keyword(s):

Gene Expression ◽

Tumor Microenvironment ◽

Tumor Growth ◽

Immune Cells ◽

Cellular Differentiation ◽

Expression Patterns ◽

Gene Cassette ◽

Gene Expression Patterns ◽

M2 Macrophages ◽

M1 And M2 Macrophages

Although various immune cells could infiltrate the cellular and tissue environment surrounding a tumor, the tumor microenvironment nevertheless presents immunosuppressive conditions unfavorable for immune cells to conduct large scale attack on cancer cells. For example, T-cells that make it to the tumor microenvironment are typically non-functional in containing tumor growth. On the other hand, macrophages could infiltrate the tumor microenvironment and is an important cell type modulated by and which also modulates the tumor. Specifically, two variants of macrophages with different phenotypes are known to exhibit close interactions with tumors. Known as M1 and M2 macrophages, they present dichotomously different signals to the tumor. Specifically, M1 macrophages control tumor growth while M2 macrophages promote tumor growth. Thus, from a treatment perspective, it would be desirable to tune the phenotypes and cell differentiation program of macrophages towards the M1 subset. To do that, differential gene expression of macrophages in the M1 and M2 lineages must be understood. Such a goal could be achieved with the profiling of tumor associated macrophages from tumor biopsy samples for gene expression patterns characteristic of the two dominant macrophage lineages. Single cell RNA-sequencing conducted after flow cytometry sorting of M1 and M2 macrophages would highlight gene expression patterns associated with each lineage, and the cellular differentiation programs that prompted entry into particular macrophage subtype. Knowledge of gene expression pattern associated with each macrophage lineage is not useful for tuning their differentiation state unless specific transcription factor that trigger the regulon could be identified. To this end, transcription factors that have been upregulated in the differentiation program could be profiled from the transcriptome data, and help inform the design of vectors for targeted overexpression of specific transcription factor for modulating cellular differentiation of macrophage. Given their low immunogenicity, adeno-associated virus (AAV) could serve as vectors for ferrying the gene cassette containing specific transcription factors into macrophages. Delivery methods for the AAV could be via targeted local infusion of vectors to tumors or through the systemic circulation, but the latter approach would result in lower transfection efficiency. Collectively, possibility exists of tuning the differentiation state of macrophage associated with tumors for enabling tumor controlling lineage to be dominant. Such immuno-targeted therapy would harness the body’s macrophages for controlling tumor growth and represents a treatment option that may yield fewer side effects compared to conventional chemotherapy. But, identification of genes that control lineage-specific differentiation program and the delivery of gene cassette to macrophages for modulating their differentiation remain key challenges.

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Possibility of tuning the differentiation state of tumor associated macrophages towards tumor controlling phenotypes

10.7287/peerj.preprints.27747 ◽

2019 ◽

Author(s):

Wenfa Ng

Keyword(s):

Gene Expression ◽

Tumor Microenvironment ◽

Tumor Growth ◽

Immune Cells ◽

Cellular Differentiation ◽

Expression Patterns ◽

Gene Cassette ◽

Gene Expression Patterns ◽

M2 Macrophages ◽

M1 And M2 Macrophages

Although various immune cells could infiltrate the cellular and tissue environment surrounding a tumor, the tumor microenvironment nevertheless presents immunosuppressive conditions unfavorable for immune cells to conduct large scale attack on cancer cells. For example, T-cells that make it to the tumor microenvironment are typically non-functional in containing tumor growth. On the other hand, macrophages could infiltrate the tumor microenvironment and is an important cell type modulated by and which also modulates the tumor. Specifically, two variants of macrophages with different phenotypes are known to exhibit close interactions with tumors. Known as M1 and M2 macrophages, they present dichotomously different signals to the tumor. Specifically, M1 macrophages control tumor growth while M2 macrophages promote tumor growth. Thus, from a treatment perspective, it would be desirable to tune the phenotypes and cell differentiation program of macrophages towards the M1 subset. To do that, differential gene expression of macrophages in the M1 and M2 lineages must be understood. Such a goal could be achieved with the profiling of tumor associated macrophages from tumor biopsy samples for gene expression patterns characteristic of the two dominant macrophage lineages. Single cell RNA-sequencing conducted after flow cytometry sorting of M1 and M2 macrophages would highlight gene expression patterns associated with each lineage, and the cellular differentiation programs that prompted entry into particular macrophage subtype. Knowledge of gene expression pattern associated with each macrophage lineage is not useful for tuning their differentiation state unless specific transcription factor that trigger the regulon could be identified. To this end, transcription factors that have been upregulated in the differentiation program could be profiled from the transcriptome data, and help inform the design of vectors for targeted overexpression of specific transcription factor for modulating cellular differentiation of macrophage. Given their low immunogenicity, adeno-associated virus (AAV) could serve as vectors for ferrying the gene cassette containing specific transcription factors into macrophages. Delivery methods for the AAV could be via targeted local infusion of vectors to tumors or through the systemic circulation, but the latter approach would result in lower transfection efficiency. Collectively, possibility exists of tuning the differentiation state of macrophage associated with tumors for enabling tumor controlling lineage to be dominant. Such immuno-targeted therapy would harness the body’s macrophages for controlling tumor growth and represents a treatment option that may yield fewer side effects compared to conventional chemotherapy. But, identification of genes that control lineage-specific differentiation program and the delivery of gene cassette to macrophages for modulating their differentiation remain key challenges.

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Abstract A17: Differential gene expression and tumor mutanome analysis reveal significantly enriched pathways associated with higher tumor burden of M1 and M2 macrophages

10.1158/2326-6074.tumimm16-a17 ◽

2017 ◽

Author(s):

Nitin Mandloi ◽

Ashwini Patil ◽

Rekha Sathian ◽

Aparna Mohan ◽

Malini Manoharan ◽

...

Keyword(s):

Gene Expression ◽

Differential Gene Expression ◽

Tumor Burden ◽

M2 Macrophages ◽

Differential Gene ◽

M1 And M2 Macrophages

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The Immune Cell Landscape in Different Anatomical Structures of Knee in Osteoarthritis: A Gene Expression-Based Study

BioMed Research International ◽

10.1155/2020/9647072 ◽

2020 ◽

Vol 2020 ◽

pp. 1-21 ◽

Cited By ~ 1

Author(s):

Ziming Chen ◽

Yuanchen Ma ◽

Xuerui Li ◽

Zhantao Deng ◽

Minghao Zheng ◽

...

Keyword(s):

Gene Expression ◽

Dendritic Cells ◽

Mast Cells ◽

Subchondral Bone ◽

Immune Cells ◽

Immune Cell ◽

M2 Macrophages ◽

Anatomical Structures ◽

Normal Tissues ◽

Immunological Mechanisms

Background. Immunological mechanisms play a vital role in the pathogenesis of knee osteoarthritis (KOA). Moreover, the immune phenotype is a relevant prognostic factor in various immune-related diseases. In this study, we used CIBERSORT for deconvolution of global gene expression data to define the immune cell landscape of different structures of knee in osteoarthritis. Methods and Findings. By applying CIBERSORT, we assessed the relative proportions of immune cells in 76 samples of knee cartilage, 146 samples of knee synovial tissue, 40 samples of meniscus, and 50 samples of knee subchondral bone. Enumeration and activation status of 22 immune cell subtypes were provided by the obtained immune cell profiles. In synovial tissues, the differences in proportions of plasma cells, M1 macrophages, M2 macrophages, activated dendritic cells, resting mast cells, and eosinophils between normal tissues and osteoarthritic tissues were statistically significant (P<0.05). The area under the curve was relatively large in resting mast cells, dendritic cells, and M2 macrophages in receiver operating characteristic analyses. In subchondral bones, the differences in proportions of resting master cells and neutrophils between normal tissues and osteoarthritic tissues were statistically significant (P<0.05). In subchondral bones, the proportions of immune cells, from the principle component analyses, displayed distinct group-bias clustering. Resting mast cells and T cell CD8 were the major component of first component. Moreover, we revealed the potential interaction between immune cells. There was almost no infiltration of immune cells in the meniscus and cartilage of the knee joint. Conclusions. The immune cell composition in KOA differed substantially from that of healthy joint tissue, while it also differed in different anatomical structures of the knee. Meanwhile, activated mast cells were mainly associated with high immune cell infiltration in OA. Furthermore, we speculate M2 macrophages in synovium and mast cells in subchondral bone may play an important role in the pathogenesis of OA.

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High Expression of NREP Correlated With Worse Survival and M2 Macrophage Infiltrates in Gastric Cancer

10.21203/rs.3.rs-832381/v1 ◽

2021 ◽

Author(s):

Tailiang Lu ◽

Chenlong Li ◽

Wei Peng ◽

Cailing Xiang ◽

Yongqiang Gong ◽

...

Keyword(s):

Gene Expression ◽

Gastric Cancer ◽

T Cell ◽

Mrna Expression ◽

Inflammatory Responses ◽

Gene Set Enrichment Analysis ◽

The Cancer Genome Atlas ◽

High Expression ◽

M2 Macrophage ◽

M2 Macrophages

Abstract Background: Neuronal Regeneration Related Protein (NREP) is a highly conserved protein and is a newly discovered protein that may be closely related to tumor cell migration. We aim at investigating the prognostic role of NREP in gastric cancer (GC). Methods: Tumor Immune Estimation Resource (TIMER), The Cancer Genome Atlas (TCGA) and Gene Expression Omnibus (GEO) databases were used to analysis NREP mRNA expression in GC. Correlations between NREP mRNA expression and clinicopathological characteristic were analyzed. TCGA and GEO data were analyzed by The Gene Expression Profiling Interactive Analysis (GEPIA) and Kaplan–Meier plotter databases respectively to assess prognostic value of NREP in GC. Gene set enrichment analysis (GSEA) was performed to identify the keg pathways related to NREP expression. TIMER and CIBERSORT analysis were used to found tumor-infiltrating immune cells associated with NREP mRNA expression. Results: NREP was over expressed in GC and significantly associated with T stage (P<0.001), Histologic grade (P = 0.022) and OS events (P = 0.007) of GC patients. High mRNA expression of NREP correlated with worse survival. The significantly kegg pathways enriched in samples with NREP high expression involved in cell adhesion, tumorigenesis, and immune and inflammatory responses. NREP mRNA expression was positively associated with CD4+T cell(r = 0.294, P = 1.04e−08), CD8+T cell(r = 0.125, P = 0.0167), Neutrophil(r = 0.169, P = 0.00116), Dendritic(r = 0.314, P = 1.03e−09), and was strongly associated with Macrophage (r = 0.547, P = 5.44e−30). The CIBERSORT database revealed that NREP mRNA expression was correlated with the activated memory CD4+ T cells(p<0.01), Monocytes(p<0.001) and M2 Macrophages(p<0.001). NREP is strongly correlated with the markers genes of M2 macrophages and tumor-associated macrophages (TAMs). Conclusion: NREP might be served as a novel prognostic biomarker of GC and associated with M2 macrophage infiltrates.

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Increased M2 Macrophages and Higher Levels Of The Tribble Family Member Trib1 In Monocytes Are Associated With Progressive Disease In Multiple Myeloma (MM) Patients

Blood ◽

10.1182/blood.v122.21.3127.3127 ◽

2013 ◽

Vol 122 (21) ◽

pp. 3127-3127

Author(s):

Haiming Chen ◽

Mingjie Li ◽

Suzie Vardanyan ◽

Jillian Gottlieb ◽

Cathy Wang ◽

...

Keyword(s):

Gene Expression ◽

Multiple Myeloma ◽

Progressive Disease ◽

Flow Cytometric Analysis ◽

Human Monocytes ◽

M2 Macrophages ◽

Rt Pcr ◽

Macrophage Differentiation ◽

Flow Cytometric ◽

M1 And M2 Macrophages

Abstract Macrophages consist of two subgroups, M1 and M2. M1 macrophages are pro-inflammatory cells against bacterial and viral infections whereas M2 macrophages are anti-inflammatory and associated with tumor progression. The mammalian tribble (Trib) family of genes, Trib1, Trib2 and Trib3, encode pseudokinase proteins that have important roles in monocyte/macrophage proliferation, differentiation, and apoptosis. Trib1 is a critical factor that induces M2 macrophage differentiation in the bone marrow (BM). First, we investigated the proportion of M1 and M2 macrophages in BM mononuclear cells (MCs) from multiple myeloma (MM) patients with progressive disease or in remission using flow cytometric analysis. The percentage of M2 (CD36+/CD86-) macrophages in BM was significantly increased in MM patients with progressive disease (n=15) compared to those in remission (n=5; P<0.05) whereas there was no difference in the percentage of M1 (CD86+/CD14+) macrophages in BM derived from MM patients with progressive disease compared to those in remission. Using immunohistochemical (IHC) analysis, the proportion of M2 macrophages was also determined in MM BM biopsies from patients with progressive disease and remission. The samples were cut into five-micrometer sections and double stained with two antibodies following a standard IHC protocol. IHC demonstrated that the percentage of M2 macrophages (CD36+/CD14+) was markedly increased in BM sections from MM patients with progressive disease compared to those in remission. In contrast, the percentage of M1 (CD86+/CD14+) macrophages was not different among those patients with progressive disease compared to those in remission. Next, we analyzed Trib1, Trib2 and Trib3 gene expression in BMMCs obtained from MM patients with progressive disease or in remission. RT-PCR results showed Trib1 expression levels were much higher among patients with progressive disease compared to those in remission. In contrast, the expression Trib2 and Trib3 was not related to the MM patient's clinical status. To determine whether MM tumor cells affected monocyte/macrophage differentiation and Trib gene expression, we co-cultured fresh MM tumor cells with purified healthy human monocytes. BMMCs from MM patients were co-cultured with human monocytes from normal subjects using Transwell plates and the percentage of M1 and M2 macrophages was determined using flow cytometric analysis following 2, 5 and 7 days of culture. The percentage of M2 cells increased whereas the proportion of M1 cells decreased. Gene expression of Trib1, Trib2 and Trib3 was analyzed using RT-PCR following 2, 5, and 7 days of co-culture. The expression of Trib 1 increased during the 7 days of co-culture whereas the expression of Trib2 and Trib3 did not change. Moreover, when direct cell-to-cell contact occurred between the MM cells and the monocytes, the percentage of M2 macrophages (CD36+) markedly increased after 7 days of incubation. We have shown that MM cells induce monocytes to increase Trib1 gene expression, which stimulates M2 differentiation in monocytes. M2 cells, in turn, induce tumor progression, providing a positive feedback loop on Trib1 expression, monocyte differentiation and tumor cell growth. Overall, we propose that Trib1 may be considered as a potential novel therapeutic target for the treatment of MM. Disclosures: No relevant conflicts of interest to declare.

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