Expression Profile Of Macrophages Research Articles

MiR-511-3p protects against cockroach allergen-induced lung inflammation by antagonizing CCL2.

miR-511-3p, encoded by CD206/Mrc1, was demonstrated to reduce allergic inflammation and promote alternative (M2) macrophage polarization. Here, we sought to elucidate the fundamental mechanism by which miR-511-3p attenuates allergic inflammation and promotes macrophage polarization. Compared with WT mice, the allergen-challenged Mrc1-/- mice showed increased airway hyperresponsiveness (AHR) and inflammation. However, this increased AHR and inflammation were significantly attenuated when these mice were pretransduced with adeno-associated virus-miR-511-3p (AAV-miR-511-3p). Gene expression profiling of macrophages identified Ccl2 as one of the major genes that was highly expressed in M2 macrophages but antagonized by miR-511-3p. The interaction between miR-511-3p and Ccl2 was confirmed by in silico analysis and mRNA-miR pulldown assay. Further evidence for the inhibition of Ccl2 by miR-511-3p was given by reduced levels of Ccl2 in supernatants of miR-511-3p-transduced macrophages and in bronchoalveolar lavage fluids of AAV-miR-511-3p-infected Mrc1-/- mice. Mechanistically, we demonstrated that Ccl2 promotes M1 macrophage polarization by activating RhoA signaling through Ccr2. The interaction between Ccr2 and RhoA was also supported by coimmunoprecipitation assay. Importantly, inhibition of RhoA signaling suppressed cockroach allergen-induced AHR and lung inflammation. These findings suggest a potentially novel mechanism by which miR-511-3p regulates allergic inflammation and macrophage polarization by targeting Ccl2 and its downstream Ccr2/RhoA axis.

Hyperglycemia acts in synergy with hypoxia to maintain the pro-inflammatory phenotype of macrophages.

Diabetic foot ulcers (DFUs) are characterized by a chronic inflammation state which prevents cutaneous wound healing, and DFUs eventually lead to infection and leg amputation. Macrophages located in DFUs are locked in an pro-inflammatory phenotype. In this study, the effect of hyperglycemia and hypoxia on the macrophage phenotype was analyzed. For this purpose, a microarray was performed to study the gene expression profile of macrophages cultivated in a high glucose concentration. Hyperglycemia upregulated the expression of pro-inflammatory cytokines such as TNF-α, IL-1, IL-6, chemokines and downregulated the expression of two receptors involved in phagocytosis (CD 36 and Class B scavenger type I receptors). In addition, eleven anti-apoptotic factors were upregulated whereas three pro-apoptotic genes were downregulated. Subsequently, the contribution of hypoxia and hyperglycemia to chronic inflammation and their potential synergistic effect was evaluated on activated THP-1 derived macrophages. A long term post activation effect (17 hours) was only observed on the upregulation of pro-inflammatory cytokines when hypoxia was combined with a high glucose concentration. In contrast, hyperglycemia and hypoxia did not have any effect on wound healing molecules such as TGF-β1. Taken together, the results show that hyperglycemia acts in synergy with hypoxia to maintain a chronic inflammation state in macrophages.

Galanin is a potent modulator of cytokine and chemokine expression in human macrophages

The regulatory peptide galanin is broadly distributed in the central- and peripheral nervous systems as well as in non-neuronal tissues, where it exerts its diverse physiological functions via three G-protein-coupled receptors (GAL1-3-R). Regulatory peptides are important mediators of the cross-communication between the nervous- and immune systems and have emerged as a focus of new therapeutics for a variety of inflammatory diseases. Studies on inflammatory animal models and immune cells revealed both pro- and anti-inflammatory functions of galanin. Here, we probed specific immune-related functions of the galanin system and found galanin and GAL1-R and GAL2-R mRNA to be expressed in a range of human immune cells. In particular, macrophages displayed differentiation- and polarization-dependent expression of galanin and its receptors. Exposure to exogenous galanin affected the cytokine/chemokine expression profile of macrophages differently, depending on their differentiation and polarization, and mainly modulated the expression of chemokines (CCL2, CCL3, CCL5 and CXCL8) and anti-inflammatory cytokines (TGF-β, IL-10 and IL-1Ra), especially in type-1 macrophages. Cytokine/chemokine expression levels in interferon-gamma- and lipopolysaccharide-polarized macrophages were upregulated whereas in unpolarized macrophages they were downregulated upon galanin treatment for 20 hours. This study illuminates the regulation of important cytokines/chemokines in macrophages by galanin, depending on specific cell activation.

H3K4me3 Profiles of LPS and Immune Complex-Activated Macrophages

Abstract Macrophages play an important role in immune response such as inflammation, phagocytosis, metabolism and tissue homeostasis. Lipopolysaccharide (LPS)-stimulated macrophages produces pro-inflammatory cytokines such as TNFα, IL-6 and IL-12 while repeated stimulation with LPS can lead to unresponsive state called LPS tolerance. Stimulation with LPS in the presence of immune complex (IC) drastically changes gene expression profiles of macrophages. LPS/IC-stimulated macrophages produce high level of IL-10 and low level of IL-12. In this study, we investigated the plasticity between LPS-stimulated and LPS/IC-stimulated macrophages and compared active histone marks (trimethylation on lysine 4 on histone 3 (H3K4me3)) in LPS-stimulated macrophages and LPS/IC-stimulated macrophages using bone marrow derived murine macrophages by the ChIP-seq approach. Stimulation with LPS that was followed immediately by LPS/IC did not result in IL-10 production. Defects in activation of p38, p44/42 Erk and NF-kB p65 were observed. In contrast, the resting of 2 days between LPS and LPS/IC yielded IL-10hiIL-12lo phenotype. Our ChIP-seq data suggested that the global H3K4me3 profiles differed between these LPS- and LPS/IC-stimulated macrophages. Some key genes that are uniquely upregulated in LPS/IC-stimulated macrophages were found to contain H3K4me3 in the regulatory region. Taken together, LPS/IC-stimulated macrophages exhibits unique H3K4me3 profiles and our results may help explain the plasticity of LPS vs. LPS/IC-stimulated macrophages.

Inhibition of RON kinase potentiates anti-CTLA-4 immunotherapy to shrink breast tumors and prevent metastatic outgrowth

ABSTRACTThe advent of immune checkpoint blockade as a new strategy for immunotherapy has changed the outlook for many aggressive cancers. Although complete tumor eradication is attainable in some cases, durable clinical responses are observed only in a small fraction of patients, underlining urgent need for improvement. We previously showed that RON, a receptor tyrosine kinase expressed in macrophages, suppresses antitumor immune responses, and facilitates progression and metastasis of breast cancer. Here, we investigated the molecular changes that occur downstream of RON activation in macrophages, and whether inhibition of RON can cooperate with checkpoint immunotherapy to eradicate tumors. Activation of RON by its ligand, MSP, altered the gene expression profile of macrophages drastically and upregulated surface levels of CD80 and PD-L1, ligands for T-cell checkpoint receptors CTLA-4 and PD-1. Genetic deletion or pharmacological inhibition of RON in combination with anti-CTLA-4, but not with anti-PD-1, resulted in improved clinical responses against orthotopically transplanted tumors compared to single-agent treatment groups, resulting in complete tumor eradication in 46% of the animals. Positive responses to therapy were associated with higher levels of T-cell activation markers and tumor-infiltrating lymphocytes. Importantly, co-inhibition of RON and anti-CTLA-4 was also effective in clearing metastatic breast cancer cells in lungs, resulting in clinical responses in nearly 60% of the mice. These findings suggest that RON inhibition can be a novel approach to potentiate responses to checkpoint immunotherapy in breast cancer.

Abstract 3135: Single-cell RNA sequencing identifies macrophage-specific expression signatures associated with phagocytosis of multiple myeloma after treatment with cIAP antagonist

Abstract Multiple myeloma (MM) is the second most common hematologic cancer, accounting for roughly 2% of all cancer deaths. Unfortunately, MM remains incurable and nearly all patients experience relapse. Recently, we have identified a novel cIAP1 antagonist, LCL161, with remarkable anti-MM effects. Interestingly, unlike in other tumor types, our previous work found that LCL161 does not directly induce apoptosis of MM cells, but rather drives activation and infiltration of macrophages to the tumor bed and phagocytosis of tumor cells. Furthermore, in vitro experiments demonstrate that the anti-MM activity of the agent relies on the presence of the tumor, with no observed increase in MM phagocytosis when macrophages are treated in isolation. However, LCL161 is a strong and indiscriminate transcriptional activator and thus, the molecular mechanisms underlying this immune response in MM remain poorly understood. In an effort to characterize molecular signatures associated with this response, we collected whole spleens from seven WT mice and eleven mice with VK12598 transplanted myeloma for single cell RNA-seq. Of the eleven tumor-bearing mice, three remained untreated, three were treated with LCL161, three with bortezomib, and three with cyclophosphamide. Additionally, one of the WT mice was treated with LCL161. Using the 10X genomics chromium platform, we measured mRNA levels in over 90,000 individual cells. We identified groups of cells with shared expression profiles, corresponding to known cell types, using graph-based clustering. Consistent with our previous work, we observed a marked reduction in tumor cells and activation of the noncanonical NFkB pathway in mice treated with LCL161. Turning our attention to cells identified as monocytes, with a particular focus on putative macrophages, we sought to identify molecular signatures associated with LCL161 treatment. Indeed, using a binomial model we identified over 500 upregulated genes in LCL161-treated macrophages. However, our previous data suggested that the efficacy of LCL161 was dependent on the presence of tumor cells. Thus, we refined these results by comparing the expression profile of macrophages treated with LCL161 in WT and tumor-bearing mice. These contrasts identified dozens of genes that were significantly upregulated in macrophages from LCL161 treated, tumor-bearing mice. Of note, we identified a small number of genes (including Spp1, Irg1, and Lipg) that were active only in macrophages from mice treated with LCL161 and bearing a transplanted tumor and unexpressed in all other cells. We believe these genes—and the pathways in which they are active—hold promise for the development of novel targeted therapies to better treat MM. Citation Format: Nicholas Banovich, Martin Boateng, Marta Chesi, Leif Bergsagel, Jonathan Keats. Single-cell RNA sequencing identifies macrophage-specific expression signatures associated with phagocytosis of multiple myeloma after treatment with cIAP antagonist [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 3135.

High-Resolution Mapping and Dynamics of the Transcriptome, Transcription Factors, and Transcription Co-Factor Networks in Classically and Alternatively Activated Macrophages.

Macrophages are the prime innate immune cells of the inflammatory response, and the combination of multiple signaling inputs derived from the recognition of host factors [e.g., interferon-g (IFN-γ)] and invading pathogen products (e.g., toll-like receptors (TLRs) agonists) are required to maintain essential macrophage function. The profound effects on biological outcomes of inflammation associated with IFN-γ pretreatment (“priming”) and TLR4 ligand bacterial lipopolysaccharide (LPS)-induced macrophage activation (M1 or classical activation) have long been recognized, but the underlying mechanisms are not well defined. Therefore, we analyzed gene expression profiles of macrophages and identified genes, transcription factors (TFs), and transcription co-factors (TcoFs) that are uniquely or highly expressed in IFN-γ-mediated TLR4 ligand LPS-inducible versus only TLR4 ligand LPS-inducible primary macrophages. This macrophage gene expression has not been observed in macrophage cell lines. We also showed that interleukin (IL)-4 and IL-13 (M2 or alternative activation) elicited the induction of a distinct subset of genes related to M2 macrophage polarization. Importantly, this macrophage gene expression was also associated with promoter conservation. In particular, our approach revealed novel roles for the TFs and TcoFs in response to inflammation. We believe that the systematic approach presented herein is an important framework to better understand the transcriptional machinery of different macrophage subtypes.

Global gene expression analysis of macrophage response induced by nonporous and porous silica nanoparticles

Little is known about the global gene expression profile of macrophages in response to changes in size and porosity of silica nanoparticles (SNPs). Spherical nonporous SNPs of two different diameters, and mesoporous spherical SNPs with comparable size were characterized. Reactive oxygen species, mitochondrial membrane potential, lysosome degradation capacity, and lysosome pH were measured to evaluate the influence of nonporous and mesoporous SNPs on mitochondrial and lysosomal function. RNA-sequencing was utilized to generate transcriptional profiles of RAW264.7 macrophages exposed to non-toxic SNP doses. DESeq2, limma, and BinReg2 software were used to analyze the data based on both unsupervised and supervised strategies to identify genes with greatest differences among NP treatments. Utilizing GATHER and DAVID software, possible induced pathways were studied. We found that mesoporous silica nanoparticles are capable of altering gene expression in macrophages at doses that do not elicit acute cytotoxicity, while gene transcription was minimally affected by nonporous SNPs.

Quantitative proteomic analysis of host responses triggered by Mycobacterium tuberculosis infection in human macrophage cells.

Macrophages are primary host of Mycobacterium tuberculosis (M.tb) and the central effector of in vivo innate immune responses against bacteria. Though the interaction between macrophages and mycobacteria has been widely investigated, the molecular mechanisms of M.tb pathogenesis in macrophages are still not clear. In this work, we investigated the altered protein expression profiles of macrophages after virulent H37Rv strain and avirulent H37Ra strain infection by tandem mass tag-based quantitative proteomics. Among 6762 identified proteins of macrophages, the expression levels of 235 proteins were significantly altered, which is supposed to be related to the infection of different strains. By bioinformatics analysis at systems level, we found that these proteins are mainly involved in the biological process of apoptosis, blood coagulation, oxidative phosphorylation, and others. The enormous variation in protein profiles between macrophages infected with H37Ra and H37Rv suggests the existence of four different immunity mechanisms that decide the fates of macrophages and M.tb. These data may provide a better understanding of M.tb pathogenesis within the host, which contributes to the prevention and clinical treatment of tuberculosis.

Incorporation of cerium oxide into hydroxyapatite coating regulates osteogenic activity of mesenchymal stem cell and macrophage polarization.

Biomedical coatings for orthopedic implants should facilitate osseointegration and mitigate implant-induced inflammatory reactions. Cerium oxide (CeO2) ceramics possess anti-oxidative properties and can be used to decrease mediators of inflammation, which makes them attractive for biomedical applications. In our work, two kinds of CeO2 incorporated hydroxyapatite coatings (HA-10Ce and HA-30Ce) were prepared via plasma spraying technique and the effects of CeO2 addition on the responses of bone mesenchymal stem cells (BMSCs) and RAW264.7 macrophages were investigated. An increase in CeO2 content in the HA coatings resulted in better osteogenic behaviors of BMSCs in terms of cell proliferation, alkaline phosphatase (ALP) activity and mineralized nodule formation. RT-PCR and western blot analysis suggested that the incorporation of CeO2 may promote the osteogenic differentiation of BMSCs through the Smad-dependent BMP signaling pathway, which activated Runx2 expression and subsequently enhanced the expression of ALP and OCN. The expression profiles of macrophages cultured on the CeO2 modified coating revealed a tendency toward a M2 phenotype, because of an upregulation of M2 surface markers (CD163 and CD206), anti-inflammatory cytokines (TNF-α and IL-6) and osteoblastogenesis-related genes (BMP2 and TGF-β1) as well as a downregulation of M1 surface markers (CCR7 and CD11c), proinflammatory cytokines (IL-10 and IL-1ra) and reactive oxygen species production. The results suggested the regulation of BMSCs behaviors and macrophage-mediated responses at the coating's surface were associated with CeO2 incorporation. The incorporation of CeO2 in HA coatings can be a valuable strategy to promote osteogenic responses and reduce inflammatory reactions.

Activin promotes skin carcinogenesis by attraction and reprogramming of macrophages.

Activin has emerged as an important player in different types of cancer, but the underlying mechanisms are largely unknown. We show here that activin overexpression is an early event in murine and human skin tumorigenesis. This is functionally important, since activin promoted skin tumorigenesis in mice induced by the human papillomavirus 8 oncogenes. This was accompanied by depletion of epidermal γδ T cells and accumulation of regulatory T cells. Most importantly, activin increased the number of skin macrophages via attraction of blood monocytes, which was prevented by depletion of CCR2‐positive monocytes. Gene expression profiling of macrophages from pre‐tumorigenic skin and bioinformatics analysis demonstrated that activin induces a gene expression pattern in skin macrophages that resembles the phenotype of tumor‐associated macrophages in different malignancies, thereby promoting angiogenesis, cell migration and proteolysis. The functional relevance of this finding was demonstrated by antibody‐mediated depletion of macrophages, which strongly suppressed activin‐induced skin tumor formation. These results demonstrate that activin induces skin carcinogenesis via attraction and reprogramming of macrophages and identify novel activin targets involved in tumor formation.

Guanylate-binding protein 5 is a marker of interferon-γ-induced classically activated macrophages.

Macrophage activation is the main immunological process occurring during the development of several diseases, and the heterogeneity of macrophage activation or differentiation has been suggested to be involved in disease progression. In the present study, we attempted to identify molecules specifically expressed on human classically activated macrophages (M1) to investigate the significance of the M1-like phenotype in human diseases. Human monocyte-derived macrophages were differentiated into M1, M2a, M2b and M2c phenotypes, and also M1(−) (the M1 phenotype differentiated with interferon-γ) to eliminate the strong effects of lipopolysaccharides (LPS) on the gene expression profile. The gene expression profiles of those macrophage phenotypes were analyzed by a cDNA microarray analysis and were used for a bioinformatics examination to identify the markers of the M1 phenotype that are expressed in both M1 and M1(−). The gene expression profiles of murine macrophages were also evaluated. We identified guanylate-binding protein 5 (GBP5), which is associated nucleotide-binding domain and leucine-rich repeat containing gene family, pyrin domain containing 3 (NLRP3)-mediated inflammasome assembly in the M1 macrophages of both humans and mice. Notably, the expression of GBP5 protein was detected in cultured M1(−) as well as in M1 macrophages by western blotting, which means that GBP5 is a more generalized marker of the M1 phenotype compared with the M1 markers that can be induced by LPS stimulation. GBP5 is a useful candidate marker of the M1 phenotype.

Abstract 725: HMGB1-mediated RAGE activation mechanism in M2 macrophages

Abstract Tumor-associated macrophages display M2 phenotype and promote immunosuppression, tumor growth, angiogenesis and metastasis. We have previously reported that M2 macrophages express the receptor of advanced glycation end-products (RAGE) and their protumoral activities enhanced by HMGB1, a RAGE ligand highly abundant at the cancer microenvironment. However, RAGE is highly expressed by M1 macrophages and it is unknown if proinflammatory and antitumor cytotoxicity of M1 macrophages become skewed from classical antitumor activities to a tumor permissive profile when M2 macrophages are induced by HMGB1. In order to clarify whether RAGE contributes to inflammatory response inhibition in M2 macrophages, we look at some microRNAs, a tolerance-like state as well as to some epigenetic changes. Polarized M1 and M2 macrophages were derived from wild-type and RAGE-targeted knock-down THP-1 cells and treated with HMGB1 at different times. NFkB activation was assessed by p65, IKBalpha western blots, and p50 and p65 Transcription Factor Assay. Additionally, we analyzed changes of chromatin activity related to HMGB1 treatment by quantitative chromatin immunoprecipitation (ChIP) with antibodies against acetylated or methylated histone H3 at the IL-10 promoter. We showed that RAGE activation by HMGB1 did not produce NFkB activation, as assessed by either IKB alpha and phospho p65 western blots or by p65 and p50 trascription factor assays. In addition, HMGB1 did not modify M2 macrophage expression profile of relevant microRNAs for macrophage polarization such as miR-155, miR-21 and miR-125b. However, ChIP analysis showed that HMGB1 induced a transcription-prone histone modification at the IL-10 promoter in M2 macrophages and this epigenetic imprinting correlated with HMGB1-induced IL-10 production, leading to immunosupression. These results demonstrate that RAGE activation on M2 macrophages did not induce NFkB activation and suggest that epigenetic changes are a major mechanism by which activities described for M1 macrophages upon RAGE activation have become skewed during macrophage polarization. Citation Format: Armando Rojas, Paulina Araya, Jacqueline Romero, Fernando Delgado-López, Ramón Pérez-Castro, Ileana González, Carolina Añazco, Erik Morales, Jorge Llanos, Fernando Vidal-Vanaclocha. HMGB1-mediated RAGE activation mechanism in M2 macrophages. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 725.

The contribution of arachidonate 15-lipoxygenase in tissue macrophages to adipose tissue remodeling.

Cellular plasticity in adipose tissue involves adipocyte death, its clearance, and de novo adipogenesis, enabling homeostatic turnover and adaptation to metabolic challenges; however, mechanisms regulating these serial events are not fully understood. The present study investigated the roles of arachidonate 15-lipoxygenase (Alox15) in the clearance of dying adipocytes by adipose tissue macrophages. First, upregulation of Alox15 expression and apoptotic adipocyte death in gonadal white adipose tissue (gWAT) were characterized during adipose tissue remodeling induced by β3-adrenergic receptor stimulation. Next, an in vitro reconstruction of adipose tissue macrophages and apoptotic adipocytes recapitulated adipocyte clearance by macrophages and demonstrated that macrophages co-cultured with apoptotic adipocytes increased the expression of efferocytosis-related genes. Genetic deletion and pharmacological inhibition of Alox15 diminished the levels of adipocyte clearance by macrophages in a co-culture system. Gene expression profiling of macrophages isolated from gWAT of Alox15 knockout (KO) mice demonstrated distinct phenotypes, especially downregulation of genes involved in lipid uptake and metabolism compared to wild-type mice. Finally, in vivo β3-adrenergic stimulation in Alox15 KO mice failed to recruit crown-like structures, a macrophage network clearing dying adipocytes in gWAT. Consequently, in Alox15 KO mice, proliferation/differentiation of adipocyte progenitors and β3-adrenergic remodeling of gWAT were impaired compared to wild-type control mice. Collectively, our data established a pivotal role of Alox15 in the resolution of adipocyte death and in adipose tissue remodeling.

Expression Profiling of Macrophages Reveals Multiple Populations with Distinct Biological Roles in an Immunocompetent Orthotopic Model of Lung Cancer.

Macrophages represent an important component of the tumor microenvironment and play a complex role in cancer progression. These cells are characterized by a high degree of plasticity, and they alter their phenotype in response to local environmental cues. Whereas the M1/M2 classification of macrophages has been widely used, the complexity of macrophage phenotypes has not been well studied, particularly in lung cancer. In this study we employed an orthotopic immunocompetent model of lung adenocarcinoma in which murine lung cancer cells are directly implanted into the left lobe of syngeneic mice. Using multimarker flow cytometry, we defined and recovered several distinct populations of monocytes/macrophages from tumors at different stages of progression. We used RNA-seq transcriptional profiling to define distinct features of each population and determine how they change during tumor progression. We defined an alveolar resident macrophage population that does not change in number and expresses multiple genes related to lipid metabolism and lipid signaling. We also defined a population of tumor-associated macrophages that increase dramatically with tumor and selectively expresses a panel of chemokine genes. A third population, which resembles tumor-associated monocytes, expresses a large number of genes involved in matrix remodeling. By correlating transcriptional profiles with clinically prognostic genes, we show that specific monocyte/macrophage populations are enriched in genes that predict outcomes in lung adenocarcinoma, implicating these subpopulations as critical determinants of patient survival. Our data underscore the complexity of monocytes/macrophages in the tumor microenvironment, and they suggest that distinct populations play specific roles in tumor progression.

Inflammatory response of TLR4 deficient spleen macrophages (CRL 2471) to Brucella abortus S19 and an isogenic ΔmglA deletion mutant

Brucellosis is a worldwide distributed zoonosis caused by members of the genus Brucella. One of them, Brucella abortus, is the etiological agent of bovine brucellosis. With the attenuated strain B. abortus S19 a vaccine is available. However, both, virulence (safety) and the ability to induce a protective B and T cell response (efficacy) have to be tested in suitable assays before successful use in the field. For this purpose, several macrophage cell lines of various origins have been used while splenic macrophages are the preferred host cells in vivo.We here characterized the in vitro response of the murine splenic macrophage cell line CRL 2471(I-13.35) to B. abortus. This cell line still depends on the presence of colony-stimulating factor 1 (CSF1) and is derived from LPS resistant (TLR4 deficient) C3H/HeJ mice. For infection the vaccine strain B. abortus S19A as well as the formerly described isogenic deletion mutant B. abortus S19A ΔmglA 3.14 were used.While numbers of viable bacteria did not differ significantly between the vaccine strain and the deletion mutant at 6h post infection, a higher bacterial load was measured in case of the mutant at 24h and 48h after infection. This was also true, when IFNγ was used for macrophage activation.A comprehensive gene expression profile of macrophages was analysed 6 and 24h after infection by means of an RT-PCR based gene expression array. The mutant strain B. abortus S19A ΔmglA 3.14 elicited a stronger cellular response of the splenic macrophages as compared to the parental vaccine strain. This was most prominent for the pro-inflammatory cytokines IL-1α, IL-1β, TNF-α and IL6 as well as for the chemokine ligands CXCL1, CXCL2, CXCL10, CCL2, CCL5, CCL7, CCL17 and the co-stimulatory molecules CD40 and ICAM1. While these differences were also present in IFNγ-stimulated macrophages, an addition of IFNγ after infection not only resulted in a dramatic increase of the translation of the afore mentioned genes but also resulted in the translation of IFNß1, IL12ß, MIP1α and β (CCL3, CCL4), NOS2 (and SOD2) and FAS. ConclusionThe TLR4 deficient murine splenic macrophage cell line CRL 2471 was used for the first time for the characterization of macrophage-Brucella interaction to investigate the pre-immune phase of brucellosis in vitro. Typical pro-inflammatory cytokines and certain surface receptors were differentially induced by B. abortus S19 A and an isogenic ΔmglA deletion mutant in vitro. This model may be useful for further studies to characterize the inflammatory response of splenic macrophages to intracellular gram-negative bacteria avoiding cell responses to soluble LPS.

Inecalcitol, a Novel Adjuvant Therapy Inhibiting Chronic Myeloid Leukemia (CML) Stem Cells, Activates a Macrophage Differentiation Pathway in Leukemic Progenitors

▪Despite the major success obtained with their use in chronic myeloid leukemia (CML), recent data obtained from treatment discontinuation trials suggest that tyrosine kinase inhibitors (TKI) alone are not sufficient to eradicate the most primitive CML stem cells in the majority of the patients. The mechanisms of this inefficiency might involve cell autonomous (activation of alternate signaling, reduced BCR-ABL expression) or non-cell autonomous (niche-related) pathways. Several strategies of targeting the primitive stem cell compartment, in association with TKI, are currently being studied. Inecalcitol (ICC) is a vitamin D3 analog exerting antiproliferative effects in several types of cancer cells. ICC was tested in CD34+ cells isolated from CML patients at diagnosis (n=18) in clonogenic assays as well as in the more primitive LTC-IC-derived progenitors. ICC alone inhibits the clonogenic growth in the majority of the CML patients at diagnosis (15/18 patients). The combination of ICC with either, Imatinib (IM), Dasatinib (DA) or Nilotinib (NIL) in clonogenic assays showed a synergistic effect for the inhibition of CFC growth (10-25% CFC survival) with no toxicity on normal progenitors. Synergistic effects of ICC and TKI was also demonstrated in LTC-IC-derived progenitors with IM, NIL and DA. To determine possible mechanism of action of ICC in CML stem cells, we have performed a gene profiling analysis of CD34+ cells obtained at diagnosis from 4 CML patients. CD34+ cells were cultured for 7 days in the presence of growth factors with or without ICC. In phenotypic analyses, CD34+ cells treated in the presence of ICC showed an increase of monocyte/macrophage differentiation features with increased expression of CD13/CD14 as well as CD11b expression. Day 0 and Day7 RNA with or without ICC treatment were then studied by transcriptome hybridation on human-v2 (8*60k) Agilent technologies microarrays. Data were treated with Feature Extraction 11.5.11, Genespring GX12, Mev 4.9, R software and GSEA 2.2.20. Gene set enrichment analysis performed at day 7 of culture between ICC condition and control untreated cells showed an increase of cell differentiation markers under ICC (Normalized enrichment score = +1.94, p-value < 0.001) One way ANNOVA with False Discovery Rate (FDR) correction allowed to discover 7176 modulated probes between the 3 experimental conditions (Day 0, Day7 without ICC, Day 7 with ICC). CYP24A1 was the gene with the greatest induction by the treatment (Fold Change = +150). CYP24A1 is responsible of the degradation of 1.25(OH)2D3 by the monocyte/macrophage cells. Unsupervised classification with 372 macrophage connected genes (ANOVA p<0.01, FDR with 1000 permutations) allowed to separate samples by their experimental classes. This macrophage expression profile allows to discriminate samples from Day7 control to those of treated cells at the same time on hierarchical classification. This was confirmed by first factorial map of principal component analysis which explained 72% (PCA1 axis) hematopoietic differentiation during 7 days and 10% (PCA2 axis) effect of the treatment at the end of the differentiation. 23 macrophagic genes were indeed found to be specifically induced by the treatment with a fold change greater than 2 as compared to the untreated control: 11 of them participate to integrin-interleukins-chemokines signalizations pathways (p-value adjust FDR = 4.04e-10). Some macrophagic ligands and receptors are over-expressed in CML cells treated with ICC, including CSF2, OSM, TNFSF11, CXCL12 as well as FAS and CXCR2. In summary, these results suggest that one of the major mechanisms of action of ICC in the leukemic progenitors involve differentiation and activation of macrophagic expression profile. This profile could be used to design further therapeutic actions and to predict response to ICC, which is now tested in combination with IM in a clinical trial in France. DisclosuresDufour-Lamartinie:Hybrigenics: Employment, Equity Ownership, Membership on an entity's Board of Directors or advisory committees. Delansorne:Hybrigenics: Employment, Equity Ownership, Membership on an entity's Board of Directors or advisory committees. Turhan:Bristol Myers Squibb: Consultancy; Novartis: Research Funding.

Changes in Macrophage Gene Expression Associated with Leishmania (Viannia) braziliensis Infection.

Different Leishmania species cause distinct clinical manifestations of the infectious disease leishmaniasis. It is fundamentally important to understand the mechanisms governing the interaction between Leishmania and its host cell. Little is known about this interaction between Leishmania (Viannia) braziliensis and human macrophages. In this study, we aimed to identify differential gene expression between non-infected and L. (V) braziliensis-infected U937-derived macrophages. We deployed a whole human transcriptome microarray analysis using 72 hours post-infection samples and compared those samples with their non-infected counterparts. We found that 218 genes were differentially expressed between infected and non-infected macrophages. A total of 71.6% of these genes were down-regulated in the infected macrophages. Functional enrichment analyses identified the steroid and sterol/cholesterol biosynthetic processes between regulatory networks down-regulated in infected macrophages. RT-qPCR further confirmed this down-regulation in genes belonging to these pathways. These findings contrast with those from studies involving other Leishmania species at earlier infection stages, where gene up-regulation for this metabolic pathway has been reported. Sterol biosynthesis could be an important biological process associated with the expression profile of macrophages infected by L. (V.) braziliensis. Differential transcriptional results suggest a negative regulation of the genetic regulatory network involved in cholesterol biosynthesis.

IL-32 is a molecular marker of a host defense network in human tuberculosis.

Tuberculosis is a leading cause of infectious disease-related death worldwide; however, only 10% of people infected with Mycobacterium tuberculosis develop disease. Factors that contribute to protection could prove to be promising targets for M. tuberculosis therapies. Analysis of peripheral blood gene expression profiles of active tuberculosis patients has identified correlates of risk for disease or pathogenesis. We sought to identify potential human candidate markers of host defense by studying gene expression profiles of macrophages, cells that, upon infection by M. tuberculosis, can mount an antimicrobial response. Weighted gene coexpression network analysis revealed an association between the cytokine interleukin-32 (IL-32) and the vitamin D antimicrobial pathway in a network of interferon-γ- and IL-15-induced "defense response" genes. IL-32 induced the vitamin D-dependent antimicrobial peptides cathelicidin and DEFB4 and to generate antimicrobial activity in vitro, dependent on the presence of adequate 25-hydroxyvitamin D. In addition, the IL-15-induced defense response macrophage gene network was integrated with ranked pairwise comparisons of gene expression from five different clinical data sets of latent compared with active tuberculosis or healthy controls and a coexpression network derived from gene expression in patients with tuberculosis undergoing chemotherapy. Together, these analyses identified eight common genes, including IL-32, as molecular markers of latent tuberculosis and the IL-15-induced gene network. As maintaining M. tuberculosis in a latent state and preventing transition to active disease may represent a form of host resistance, these results identify IL-32 as one functional marker and potential correlate of protection against active tuberculosis.

The Ron receptor tyrosine kinase, macrophage heterogeneity and obesity associated disease. (P5070)

Abstract Macrophages play a central role in the progression of obesity associated disease. Macrophages are generally classified into two distinct programs, termed M1 and M2 macrophages, polar ends of a spectrum of potential macrophage activation states. The ability to tip the balance of macrophage activation away from inflammatory M1 cells and toward a reparative M2 phenotype could be beneficial in the treatment of chronic inflammation associated with obesity. The Ron receptor is expressed on tissue resident macrophages and plays a critical role in suppressing inflammation while promoting hallmarks of M2 macrophage activation. Here we show that Ron plays a protective role in the progression of atherosclerosis and hepatic steatosis in obese animals, associated with decreased inflammatory cytokine expression and decreased lipid deposition in these tissues. In lean animals, Ron is highly expressed on resident macrophages in adipose tissue. Upon weight gain, the expression of Ron is decreased and there is shift in the relative percentages of M1/M2 cells in Ron deficient mice, favoring an inflammatory environment. The percentage of Ron+ cells was also reduced in the liver and atherosclerotic plaques, while pro-inflammatory cytokine expression in isolated macrophages was enhanced in the absence of Ron. We predict that Ron is a potential marker for reparative macrophages and that the gene expression profile of macrophages from obese animals will correlate with Ron expression in these cells.