Macrophage

How
allergens trigger the T helper 2 (Th2) response that
ILC2s
[2], these cells secrete very little IL-4 protein [3]. ILC2
characterizes
allergic lung inflammation is not well un-
derstood.
Epithelium-derived alarmins released after an
allergen
encounter activate the innate immune system,
including
group 2 innate lymphoid cells (ILC2s) which
produce
the type 2 interleukins IL-5 and IL-13. It has been
recently
shown that ILC2-derived cytokines are respon-
sible
not only for the innate responses underlying aller-
gic
inflammation but also for the initiation of the
adaptive
Th2 response. We review the role of lung ILC2s
in
the development of allergic inflammation and, in the
context
of recent findings, propose a common pathway
wherein
ILC2s, activated by the epithelium-derived cy-
tokine
IL-33, link the innate and the adaptive responses
after
allergen encounter in the lung.

Inflammatory episodes observed in multiple sclerosis are characterized by perivascular infiltration of central nervous system (CNS) tissue by circulating leucocytes directed by chemokines and activation of both microglia and astrocytes. An in vitro approach, using a three-dimensional aggregate culture system derived from foetal rat brain tissue, is being taken to study the effect of inflammatory mediators on CNS cells. These aggregates model the brain in vivo in terms of glial and neuronal development and cell-cell interactions. Aggregates cultures were treated with lipopolysaccharide (LPS) and the pro-inflammatory cytokines tumour necrosis factor-alpha (TNF-α) and interferon-gamma (IFNγ). The effect of these treatments on the expression of a range of chemokine receptors (CCR1, CCR2, CCR5, CXCR3 and CX3CR1) and other markers of cell activation (MHC class I and II, CR3) was determined at the mRNA level by semiquantitative RT-PCR and at the protein level by confocal microscopy. Rat peritoneal macrophages were loaded with a fluorescent cell-tracer and their ability to infiltrate inflamed aggregates treated with IFNγ was analysed by FACS and confocal microscopy.

Adipose tissue resident macrophages have important roles in the maintenance of tissue homeostasis and regulate insulin sensitivity for example by secreting pro-inflammatory or anti-inflammatory cytokines. Here, we show that M2-like macrophages in adipose tissue regulate systemic glucose homeostasis by inhibiting adipocyte progenitor proliferation via the CD206/TGFβ signaling pathway. We show that adipose tissue CD206(+) cells are primarily M2-like macrophages, and ablation of CD206(+) M2-like macrophages improves systemic insulin sensitivity, which was associated with an increased number of smaller adipocytes. Mice genetically engineered to have reduced numbers of CD206(+) M2-like macrophages show a down-regulation of TGFβ signaling in adipose tissue, together with up-regulated proliferation and differentiation of adipocyte progenitors. Our findings indicate that CD206(+) M2-like macrophages in adipose tissues create a microenvironment that inhibits growth and differentiation of adi...

<p>(A) The initial oxidative DNA damage was measured in monocytes and macrophages using an FPG-modified alkaline Comet assay. Cells were treated with PMA for 15 min and then incubated for additional 45 min in PMA free medium. Monocytes and macrophages showed similar levels of initial DNA damage. (B) In parallel, 8OHdG was detected via immunostaining. Both monocytes and macrophages displayed clear 8OHdG staining after PMA treatment compared to the solvent control. (C) DNA strand breaks were measured at different times after the ROS burst was induced by 15 min PMA treatment. Monocytes displayed increasing levels of strand breaks over time compared to macrophages. (D) Monocytes and macrophages were treated with PMA for 15 min and cell death was measured 48 h later. Monocytes displayed increased apoptosis compared to macrophages, which were resistant. Control, untreated cells; solvent, DMSO control (see <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0170347#sec002" target="_blank">material and methods</a>). Data are the mean of at least three independent experiments ± SEM, 1-way ANOVA, Tukey’s Multiple Comparison Test, **p < 0.01, ***p < 0.001.</p

Adipose tissue resident macrophages have important roles in the maintenance of tissue homeostasis and regulate insulin sensitivity for example by secreting pro-inflammatory or anti-inflammatory cytokines. Here, we show that M2-like macrophages in adipose tissue regulate systemic glucose homeostasis by inhibiting adipocyte progenitor proliferation via the CD206/TGFβ signaling pathway. We show that adipose tissue CD206(+) cells are primarily M2-like macrophages, and ablation of CD206(+) M2-like macrophages improves systemic insulin sensitivity, which was associated with an increased number of smaller adipocytes. Mice genetically engineered to have reduced numbers of CD206(+) M2-like macrophages show a down-regulation of TGFβ signaling in adipose tissue, together with up-regulated proliferation and differentiation of adipocyte progenitors. Our findings indicate that CD206(+) M2-like macrophages in adipose tissues create a microenvironment that inhibits growth and differentiation of adi...

The NF-kB pathway plays an important role in regulating the immunity response in animals. In this study, small interfering RNAs (siRNA) were used to specifically inhibit NF-kB 1 expression and to elucidate the role of NF-kB in the signal transduction pathway of the Salmonella challenge in the chicken HD11 cell line. The cells were transfected with either NF-kB 1 siRNA, glyceraldehyde 3-phosphate dehydrogenase siRNA (positive control) or the negative control siRNA for 24 h, followed by Salmonella enteritidis (SE) challenge or non-challenge for 1 h and 4 h. Eight candidate genes related to the signal pathway of SE challenge were selected to examine the effect of NF-kB 1 inhibition on their expressions by mRNA quantification. The results showed that, with a 36% inhibition of NF-kB 1 expression, gene expression of both Toll-like receptor (TLR) 4 and interleukin (IL)-6 was consistently and significantly increased at both 1 h and 4 h following SE challenge, whereas the gene expression of MyD88 and IL-1β was increased at 1 h and 4 h, respectively. These findings suggest a likely inhibitory regulation by NF-kB 1, and could lay the foundation for studying the gene network of the innate immune response of SE infection in chickens.

Breast cancer is the leading causes of cancer-related death among women. The vast majority of breast cancers are carcinomas that originate from cells lining the milk-forming ducts of the mammary gland. Numerous articles indicate that breast tumors exhibit diverse phenotypes depending on their distinct physiopathological signatures, clinical courses, and therapeutic possibilities. The human cytomegalovirus (HCMV) is a multifaceted highly host specific betaherpesvirus that is regarded as asymptomatic or mildly pathogenic virus in immunocompetent host. HCMV may cause serious in utero infections as well as acute and chronic complications in immunocompromised individual. The involvement of HCMV in late inflammatory complications underscores its possible role in inflammatory diseases and cancer. HCMV targets a variety of cell types in vivo, including macrophages, epithelial cells, endothelial cells, fibroblasts, stromal cells, neuronal cells, smooth muscle cells, and hepatocytes. HCMV can...

ABSTRACTTrehalose 6,6′-dimycolate (TDM) is a cell wall glycolipid and an important virulence factor of mycobacteria. In order to study the role of TDM in the innate immune response toMycobacterium tuberculosis, microarray analysis was used to examine gene regulation in murine bone marrow-derived macrophages in response to 90-μm-diameter polystyrene microspheres coated with TDM. A large number of genes, particularly those involved in the immune response and macrophage function, were up- or downregulated in response to these TDM-coated beads compared to control beads. Genes involved in the immune response were specifically upregulated in a myeloid differentiation primary response gene 88 (MyD88)-dependent manner. The complexity of the transcriptional response also increased greatly between 2 and 24 h. Matrix metalloproteinases (MMPs) were significantly upregulated at both time points, and this was confirmed by quantitative real-time reverse transcription-PCR (RT-PCR). Using anin vivoM...

Megakaryocytopoiesis is the process by which stem cells go through a process of commitment, proliferation and differentiation leading to the production of platelets. In the mouse, this process is accomplished within the bone marrow (BM) and spleen microenvironment and is carried out by regulatory molecules and accessory cells including macrophages, fibroblasts and endothelial-like cells. Previously, we have reported that macrophage depletion following administration of liposomal clodronate (LIP-CLOD) provokes enhancement of both, megakaryocytopoiesis and thrombocytopoiesis. In this report, we investigated the changes in the compartment of megakaryocyte progenitor cells (MK-CFU), their correlation with plasmatic thrombopoietin (TPO) and TPO transcription levels after macrophage depletion. LIP-CLOD-treated mice showed an increase of the MK-CFU in BM and spleen. Concerning TPO plasma levels, kinetic studies revealed a 1.5- and 1.3-fold increase in the TPO concentration at 12 and 24 hr ...

Pneumocystis is a respiratory fungal pathogen that causes pneumonia (PcP) in immunocompromised patients. Alveolar macrophages are critical effectors for CD4(+) T cell-dependent clearance of Pneumocystis, and prior studies found that alternative macrophage activation accelerates fungal clearance during PcP-related immune reconstitution inflammatory syndrome (IRIS). However, the requirement of either classically or alternatively activated macrophages for Pneumocystis clearance has not been determined. Therefore, RAG2(-/-) mice lacking either the IFNγ receptor or the IL-4 receptor α were infected with Pneumocystis. These mice were then immune reconstituted with wild type lymphocytes to preserve the normal T helper response while preventing downstream effects of Th1 or Th2 effector cytokines on macrophage polarization. As expected, RAG2(-/-) mice developed severe disease, but effectively cleared Pneumocystis and resolved IRIS. Neither RAG/IFNγR(-/-) nor RAG/IL-4Rα(-/-) mice displayed im...

Immunopathology plays important roles in the development of different life-threatening diseases, such as atherosclerosis and its consequences (acute myocardial infarction and stroke), cancer, chronic inflammatory diseases. Effective modulation of the immune system may significantly increase the efficacy of prevention and therapy efforts. Currently there are no marketed drugs capable of normalizing immune system function in an intrinsic and comprehensive way. Here, we describe a test system designed for complex analysis of monocyte activity in individuals to diagnose immunopathology and monitor treatment efficacy. This cell-based test system may also be useful for screening compounds with an immune-correcting effects. Both diagnostic and screening systems are based on primary culture of human monocytes and/or monocyte-derived macrophages. This is the first step in creating a method for assessment of macrophage activity, which is required for further development of immune-correcting drugs. The existing preliminary data provide the basis for realization of this idea.

Periodontal disease is a prevalent chronic inflammatory condition characterised by an aberrant host response to a pathogenic plaque biofilm resulting in local tissue damage and frustrated healing that can result in tooth loss. Cysteine proteases (gingipains) from the key periodontal pathogen Porphyromonas gingivalis have been implicated in periodontal disease pathogenesis by inhibiting inflammation resolution and are linked with systemic chronic inflammatory conditions such as rheumatoid arthritis. Efficient clearance of apoptotic cells is essential for the resolution of inflammation and tissue restoration. Here we sought to characterise the innate immune clearance of apoptotic cells and its modulation by gingipains. We examined the capacity of gingipain-treated macrophages to migrate towards and phagocytose apoptotic cells. Lysine gingipain treatment of macrophages impaired macrophage migration towards apoptotic neutrophils. Furthermore, lysine gingipain treatment reduced surface e...

Iron oxide nanoparticles/microparticles are widely present in a variety of environments, e.g., as a byproduct of steel and iron degradation, as, for example, in railway brakes (e.g., metro station) or in welding fumes. As all particulate material, these metallic nanoparticles are taken up by macrophages, a cell type playing a key role in the innate immune response, including pathogen removal phagocytosis, secretion of free radical species such as nitric oxide or by controlling inflammation via cytokine release. In this paper, we evaluated how macrophages functions were altered by two iron based particles of different size (100 nm and 20 nm). We showed that at high, but subtoxic concentrations (1 mg/mL, large nanoparticles induced stronger perturbations in macrophages functions such as phagocytic capacity (tested with fluorescent latex microspheres) and the ability to respond to bacterial endotoxin lipopolysaccharide stimulus (LPS) in secreting nitric oxide and pro-cytokines (e.g., I...

Proceedings: AACR 103rd Annual Meeting 2012‐‐ Mar 31‐Apr 4, 2012; Chicago, IL Macrophages are key players in the inflammatory response and exhibit significant roles in the different stages of tumor progression. We have previously reported deficient functions of peritoneal macrophages of D1-DMBA3 mammary tumors bearers (T-PEMs). We showed that T-PEMs are impaired in inflammatory activity due to diminished expression of transcription factors NFκB and C/EBP. We have also demonstrated that T-PEMs display neither M1 nor M2 phenotypes, exhibit deficiencies in the production of several inflammatory cytokines, are less differentiated and show increased apoptosis. Importantly, we showed for the first time that their apoptosis in periphery contributes to increased myelopoiesis. We examined the blood monocytes from these tumor mice and demonstrated that these cells are neither inflammatory nor suppressive and are less differentiated, similar to the T-PEMs they later become. In the present study we investigate tumor-associated macrophages (TAMs) from the same tumor model and compare them with T-PEMs and with peritoneal macrophages from normal mice (N-PEMs). Our results show that TAMs downregulate IL-12p70, but upregulate IL-12p40, IL-23, IL-6 and IL-10 and chemokines and their receptors are very differently expressed in these two macrophages subpopulations. NFκB and C/EBP family members are decreased in TAMs as compared with T-PEMs, however NFκBp50 homodimers, STAT1/pSTAT1 and STAT3/pSTAT3 are all overexpressed. Moreover TAMs block T-cell proliferation and are more prone to apoptosis than T-PEMs due to a higher expression of activated caspase-3 and downregulation of Bcl-X. Our results show that T-PEMs and TAMs have equally impaired phagocytic capacity compared with fully-phagocytic N-PEMs. Moreover, TAMs constitutively express iNOS, produce nitric oxide but no arginase and are Gr-1high and CD11blow, thus are not classic myeloid-derived suppressor cells. Collectively, our results show that the exposure to different locations and tumor factor gradients determine macrophage phenotypes and functions. The tumor microenvironment, as the setting in most intimate contact with tumor cells is the one that most alters macrophage activity. Targeting tumor factors and other cells in the tumor microenvironment may allow reversion of macrophage dysfunction. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 398. doi:1538-7445.AM2012-398

Knowlege of the mechanism of atherosclerosis in chronic and inflammatory diseases is important in health care management. According to the World Health Organization, approximately 17.9 million people die from atherosclerosis annually. Macrophages played a major role in the immune response and pathophysiology of atherosclerosis. This review presents the role of macrophage in the development of atherosclerosis.

Photoacoustic Tomography (PAT) is a deep-tissue imaging modality, with potential clinical applications in the diagnosis of arthritis, cancer and other disease conditions. Here, we identified Clofazimine (CFZ), a red-pigmented dye and anti-inflammatory FDA-approved drug, as a macrophage-targeting photoacoustic (PA) imaging agent. Spectroscopic experiments revealed that CFZ and its various protonated forms yielded optimal PAT signals at wavelengths −450 to 540 nm. CFZ's macrophage-targeting chemical and structural forms were detected with PA microscopy at a high contrast-to-noise ratio (CNR > 22 dB) as well as with macroscopic imaging using synthetic gelatin phantoms. In vivo, natural and synthetic CFZ formulations also demonstrated significant anti-inflammatory activity. Finally, the injection of CFZ was monitored via a real-time ultrasound-photoacoustic (US-PA) dual imaging system in a live animal and clinically relevant human hand model. These results demonstrate an anti-inflammatory drug repurposing strategy, while identifying a new PA contrast agent with potential applications in the diagnosis and treatment of arthritis. The preclinical to clinical translation of new therapeutic and diagnostic agents is a very costly and high risk affair 1,2. Because there are many uncertainties in the efficacy and safety profiles of new therapeutic agents, the development of drug repurposing and repositioning strategies for the clinical translation of established, FDA-approved drugs has experienced a boom during the past few years 1,3. Usually, it takes more than a decade to get FDA-approval for a new chemical entity. Drug repositioning is revolutionising translational research by minimising the number of regulatory hurdles required to assure efficacy and safety, so the time for a new therapy to reach the clinic can be reduced to as little as three years 4. While drug repositioning strategies typically involve using an established therapeutic entity for treating patients with disease conditions outside the drugs' intended therapeutic activity 1,5–7 , the potential of transforming drugs into bioimaging contrast agents for diagnostic applications remains unexplored. As most diseases stem from either acute or chronic inflammation caused by a variety of molecular, biochemical or physical factors 8–11 , an anti-inflammatory drug that can be re-formulated as a bioimaging agent could be tremendously beneficial in the clinic, either as a diagnostic tool or as a contrast agent to facilitate image-guided clinical interventions 12. Independently, efforts aimed at exploiting immune cell-targeted diagnostic and therapeutic strategies 13,14 prompted us to begin exploring the feasibility of repurposing a macrophage (MΦ)-targeted, biocompati-ble, non-toxic, photoacoustically active contrast agent from a pharmacopeia of FDA-approved, clinically used small-molecule anti-inflammatory drugs. Results Photoacoustic (PA) detection relies on intrinsic absorption at specific excitation laser-generated wavelengths resulting in ultrasonic waves detected via conventional acoustic transducers 15. For imaging applications, longer wavelengths are advantageous because they afford greater imaging depth, with reduced potential for phototoxic-ity 16. Therefore, to search for candidate small molecule drugs with potential applications as PA contrast agents, we

Macrophages are pivotal cells of the immune system and play a key role in the host defence mechanism against pathogens. To date, the importance of macrophages and the role of humoral response in eliciting macrophage activity against Mycoplasma mycoides subsp. mycoides small colony (Mmm‑SC), the causative agent of contagious bovine pleuropneumonia (CBPP), have only been marginally elucidated or are almost unknown. The present study was undertaken to investigate the changes in surface morphology of macrophages after in vitro infection with Mmm‑SC in the presence of bovine immune serum. Morphological analysis was performed on macrophage cultures at 6 h post infection using the three-dimensional vision of scanning electron microscopy. Non-infected macrophages in the presence of negative or immune serum and macro phages infected with Mmm‑SC in the absence of serum showed only minor cell surface changes. In contrast, clear surface modifications, broad veils, fine philopodia highlighting cell activation and small aggregates of mycoplasma closely attached to the macrophage membrane, were observed in infected macrophage cultures in the presence of immune serum. Our results suggest that specific humoral response to Mmm‑SC may contribute and support phagocytic activity of macrophages.