From Monocytes to M1/M2 Macrophages: Phenotypical vs. Functional Differentiation

Inflammatory monocytes and NK cells play a crucial role in DNAM-1-dependent control of cytomegalovirus infection

Jonjic et al. show that inflammatory macrophages play an essential role in the control of murine CMV (MCMV) infection through a DNAM-1–PVR pathway.

The poliovirus receptor (PVR) is a ubiquitously expressed glycoprotein involved in cellular adhesion and immune response. It engages the activating receptor DNAX accessory molecule (DNAM)-1, the inhibitory receptor TIGIT, and the CD96 receptor with both activating and inhibitory functions. Human cytomegalovirus (HCMV) down-regulates PVR expression, but the significance of this viral function in vivo remains unknown. Here, we demonstrate that mouse CMV (MCMV) also down-regulates the surface PVR. The m20.1 protein of MCMV retains PVR in the endoplasmic reticulum and promotes its degradation. A MCMV mutant lacking the PVR inhibitor was attenuated in normal mice but not in mice lacking DNAM-1. This attenuation was partially reversed by NK cell depletion, whereas the simultaneous depletion of mononuclear phagocytes abolished the virus control. This effect was associated with the increased expression of DNAM-1, whereas TIGIT and CD96 were absent on these cells. An increased level of proinflammatory cytokines in sera of mice infected with the virus lacking the m20.1 and an increased production of iNOS by inflammatory monocytes was observed. Blocking of CCL2 or the inhibition of iNOS significantly increased titer of the virus lacking m20.1. In this study, we have demonstrated that inflammatory monocytes, together with NK cells, are essential in the early control of CMV through the DNAM-1–PVR pathway.

The transcriptional coregulator GRIP1 controls macrophage polarization and metabolic homeostasis

Diet-induced obesity causes chronic macrophage-driven inflammation in white adipose tissue (WAT) leading to insulin resistance. WAT macrophages, however, differ in their origin, gene expression and activities: unlike infiltrating monocyte-derived inflammatory macrophages, WAT-resident macrophages counteract inflammation and insulin resistance, yet, the mechanisms underlying their transcriptional programming remain poorly understood. We recently reported that a nuclear receptor cofactor—glucocorticoid receptor (GR)-interacting protein (GRIP)1—cooperates with GR to repress inflammatory genes. Here, we show that GRIP1 facilitates macrophage programming in response to IL4 via a GR-independent pathway by serving as a coactivator for Kruppel-like factor (KLF)4—a driver of tissue-resident macrophage differentiation. Moreover, obese mice conditionally lacking GRIP1 in macrophages develop massive macrophage infiltration and inflammation in metabolic tissues, fatty livers, hyperglycaemia and insulin resistance recapitulating metabolic disease. Thus, GRIP1 is a critical regulator of immunometabolism, which engages distinct transcriptional mechanisms to coordinate the balance between macrophage populations and ultimately promote metabolic homeostasis.

GRIP1 cooperates with the glucocorticoid receptor to repress inflammatory genes. Here the authors show that GRIP1 also controls macrophage polarization, by promoting KLF4-driven activation in response to IL-4, and that mice lacking GRIP1 in macrophages develop severe metabolic dysfunction on a high-fat diet.

Circulating Blood Monocyte Subclasses and Lipid-Laden Adipose Tissue Macrophages in Human Obesity

BACKGROUND

Visceral adipose tissue foam cells are increased in human obesity, and were implicated in adipose dysfunction and increased cardio-metabolic risk. In the circulation, non-classical monocytes (NCM) are elevated in obesity and associate with atherosclerosis and type 2 diabetes. We hypothesized that circulating NCM correlate and/or are functionally linked to visceral adipose tissue foam cells in obesity, potentially providing an approach to estimate visceral adipose tissue status in the non-surgical obese patient.

METHODS

We preformed ex-vivo functional studies utilizing sorted monocyte subclasses from healthy donors. Moreover, we assessed circulating blood monocyte subclasses and visceral fat adipose tissue macrophage (ATM) lipid content by flow-cytometry in paired blood and omental-fat samples collected from patients (n = 65) undergoing elective abdominal surgery.

RESULTS

Ex-vivo, NCM and NCM-derived macrophages exhibited lower lipid accumulation capacity compared to classical or intermediate monocytes/-derived macrophages. Moreover, of the three subclasses, NCM exhibited the lowest migration towards adipose tissue conditioned-media. In a cohort of n = 65, increased %NCM associated with higher BMI (r = 0.250,p<0.05) and ATM lipid content (r = 0.303,p<0.05). Among patients with BMI≥25Kg/m2, linear regression models adjusted for age, sex or BMI revealed that NCM independently associate with ATM lipid content, particularly in men.

CONCLUSIONS

Collectively, although circulating blood NCM are unlikely direct functional precursor cells for adipose tissue foam cells, their increased percentage in the circulation may clinically reflect higher lipid content in visceral ATMs.

Enhancement of Anti-Hypoxic Activity and Differentiation of Cardiac Stem Cells by Supernatant Fluids from Cultured Macrophages that Phagocytized Dead Mesenchymal Stem Cells

Background: Most mesenchymal stem cells (MSCs) die shortly after transplantation into a myocardial infarcted area. Dead MSCs (dMSCs) are phagocytized by macrophages (pMΦ) in vivo and in vitro; however, the effects of pMΦ on cardiac stem cells (CSCs) remain unknown. Methods: MSCs, CSCs, and macrophages were obtained from bone marrow, hearts, and peritoneal cavity of mice, respectively. dMSCs were harvested after hypoxia for 24 h, and incubated with macrophages (2:1) for another 2 days with or without lipopolysaccharide (LPS, 50 ng/mL) and sorted by flow cytometry to obtain pMΦ. Viability and apoptosis of CSCs were respectively evaluated with the cell counting kit-8 (CCk-8) assay and Annexin V-PE/7-AAD staining at 0, 6, 12, and 24 h of culture with supernatant fluids from macrophages (MΦ), LPS-stimulated macrophages (LPS-pMΦ), pMΦ, and MSCs. GATA-4 and c-TnI expression was measured by flow cytometry on the seventh day. Expression of inflammation and growth factors was assessed by real-time polymerase chain reaction (RT-PCR) in MΦ, LPS-pMΦ, and pMΦ cells. Results: pMΦ expressed higher levels of interleukin-10 (IL-10) and transforming growth factor-β (TGF-β)and lower levels of tumor necrosis factor-α(TNF-α)and IL-6 than LPS-pMΦ, higher levels of growth factors and of GATA-4 and c-TnI at the 7th day, which were similar to those in MSCs. CSCs cultured with supernatant fluids of pMΦ exhibited higher proliferative, anti-hypoxic, and differentiation activities. Conclusion: The supernatant fluids of macrophages that had phagocytized dead MSCs encouraged changes in phenotype and growth factor expression, enhanced proliferation, differentiation, and anti-hypoxic activity of CSCs, which is relevant to understanding the persistent therapeutic effect of MSCs after their massive demise upon transplantation in myocardial infarction. Furthermore, some miRNAs or proteins which were extracted from the supernatant fluids may give us a new insight into the treatment of myocardial infarction in the future.

Melanoma exosome induction of endothelial cell GM-CSF in pre-metastatic lymph nodes may result in different M1 and M2 macrophage mediated angiogenic processes

Angiogenesis is a key process in the preparation of lymph nodes for melanoma metastasis. Granulocyte macrophage colony stimulating factor (GM-CSF) induces hypoxia inducible factor 1 alpha (HIF-1α) in M1 or HIF-2α in M2 polarized macrophages. HIF-1α promotes neoangiogenesis while HIF-2α facilitates morphogenic normalization of neovasculature. Melanoma exosomes induce GM-CSF expression by endothelial cells in vitro and HIF-1α expression in pre-metastatic lymph nodes in vivo. This suggest a relationship between melanoma exosome induced endothelial GM-CSF and macrophage mediated angiogenesis in lymph nodes. Theoretically, induction of endothelial cell derived GM-CSF by melanoma exosomes mediates different angiogenic functions in pre-metastatic lymph nodes depending on subcapsular sinus (SCS) macrophage polarity. To explore this hypothesis, experiments utilizing melanoma exosomes in a lymph node model are outlined. Despite their opposing immune functions, indirect melanoma exosome stimulation of M1 or M2 SCS macrophages via endothelial derived GM-CSF in lymph nodes may induce different although complementary pro-tumor angiogenic processes.

Macrophage polarization in interstitial lung diseases

The role of bronchoalveolar lavage fluid (BALf) examination in differential diagnosis of interstitial lung diseases (ILD) was established. Currently, functional polarization into M1 (pro-inflammatory) and M2 (anti-inflammatory) subpopulations is emphasized. The aim of our study was to compare the proportion of M1 and M2 in BALf of patients with different ILD. BALf samples were collected from 75 ILD patients: sarcoidosis (SA, 36), hypersensitivity pneumonitis (HP, 10), non-specific interstitial pneumonia (NSIP, 8), idiopathic pulmonary fibrosis (IPF, 6) and other ILD (15). Phenotyping was performed by immunocytochemistry with anti-CD40 and CD163 antibodies (for M1 and M2, respectively). For both, CD40 and CD163, three populations of cells have been specified: small cells with strong (+++), large cells with weak (+) and cells with no (-) reaction. Due to lack of statistically significant differences between patients with HP, NSIP and IPF, they were classified into a common group and compared to the group of patients with sarcoidosis. The median proportion of macrophage population was as follows: for CD40: 61%, 35%, 2% in patients with SA and 49%, 47%, 3% in patients with other ILD and for CD163: 55%, 35%, 5% in SA and 53%, 43%, 1% in ILD patients, respectively. We found a significantly higher proportion of M1 in SA when compared with other ILD. Our study showed no evidence of defined polarization of alveolar macrophages in different types of interstitial lung diseases. However, we emphasized the role of CD40 positive cells in sarcoidosis and the role of CD163 positive cells in fibrotic diffuse lung diseases.

The Anti-Inflammatory Effects and Mechanisms of Eupafolin in Lipopolysaccharide-Induced Inflammatory Responses in RAW264.7 Macrophages

Eupafolin is a flavone isolated from Artemisia princeps Pampanini (family Asteraceae). The aim of this study was to examine the anti-inflammatory effects of eupafolin in lipopolysaccharide (LPS)-treated RAW264.7 macrophages and LPS-induced mouse skin and lung inflammation models and to identify the mechanism underlying these effects. Eupafolin decreased the LPS-induced release of inflammatory mediators (iNOS, COX-2 and NO) and proinflammatory cytokines (IL-6 and TNF-α) from the RAW264.7 macrophages. Eupafolin inhibited the LPS-induced phosphorylation of p38 MAPK, ERK1/2, JNK, AKT and p65 and the nuclear translocation of p65 and c-fos. These effects were mainly mediated by the inhibition of JNK. In the mouse paw and lung models, eupafolin effectively suppressed the LPS-induced edema formation and down-regulated iNOS and COX-2 expression. These results demonstrated that eupafolin exhibits anti-inflammatory properties and suggested that eupafolin can be developed as an anti-inflammatory agent.

Human Cardiac Mesenchymal Stromal Cells with CD105+CD34- Phenotype Enhance the Function of Post-Infarction Heart in Mice

Aims

The aim of the present study was to isolate mesenchymal stromal cells (MSC) with CD105⁺CD34^- phenotype from human hearts, and to investigate their therapeutic potential in a mouse model of hindlimb ischemia and myocardial infarction (MI). The study aimed also to investigate the feasibility of xenogeneic MSCs implantation.

Methods and Results

MSC isolated from human hearts were multipotent cells. Separation of MSC with CD105⁺CD34^- phenotype limited the heterogeneity of the originally isolated cell population. MSC secreted a number of anti-inflammatory and proangiogenic cytokines (mainly IL-6, IL-8, and GRO). Human MSC were transplanted into C57Bl/6NCrl mice. Using the mouse model of hindlimb ischemia it was shown that human MSC treated mice demonstrated a higher capillary density 14 days after injury. It was also presented that MSC administrated into the ischemic muscle facilitated fast wound healing (functional recovery by ischemic limb). MSC transplanted into an infarcted myocardium reduced the post-infarction scar, fibrosis, and increased the number of blood vessels both in the border area, and within the post-infarction scar. The improvement of left ventricular ejection fraction was also observed.

Conclusion

In two murine models (hindlimb ischemia and MI) we did not observe the xenotransplant rejection. Indeed, we have shown that human cardiac mesenchymal stromal cells with CD105⁺CD34^- phenotype exhibit therapeutic potential. It seems that M2 macrophages are essential for healing and repair of the post-infarcted heart.

Human amnion favours tissue repair by inducing the M1-to-M2 switch and enhancing M2 macrophage features

Human amniotic mesenchymal cells (hAMTCs) possess interesting immunomodulatory properties, making them attractive candidates for regenerative medicine applications. Recent in vivo reports argue in favour of an important role for macrophages as targets of hAMTC‐mediated suppression of inflammation and the enhancement of tissue repair. However, a comprehensive study of the effects of hAMTCs and their conditioned medium (CM) on human macrophage differentiation and function is unavailable. In the present study we found that hAMTCs and CM induce the differentiation of myeloid cells (U937 and monocytes) towards macrophages. We then investigated their effects on monocytes differentiated toward pro‐inflammatory M1 and anti‐inflammatory M2 macrophages. Monocytes treated under M1 conditions in the presence of hAMTCs or CMs shifted towards M2‐like macrophages, which expressed CD14, CD209, CD23, CD163 and PM‐2 K, possessed higher phagocytic activity and produced higher IL‐10 and lower pro‐inflammatory cytokines. They were also poor T cell stimulators and Th1 inducers, while they were able to increase activated and naïve suppressive Treg subsets. We show that prostaglandins, and not IL‐6, play a role in determining the M2 activation status. Instead, monocytes treated under M2 conditions in the presence of hAMTCs or CM retained M2‐like features, but with an enhanced anti‐inflammatory profile, having a reduced expression of the co‐stimulatory molecule CD80, reduced phagocytosis activity and decreased the secretion of inflammatory chemokines. Importantly, we provide evidence that macrophages re‐educated by CM improve tissue regeneration/repair in wound‐healing models. In conclusion, we identified new cell targets of hAMTCs and their bioactive factors and here provide insight into the beneficial effects observed when these cells are used in therapeutic approaches in vivo. © 2016 The Authors Journal of Tissue Engineering and Regenerative Medicine Published by John Wiley & Sons Ltd.

Monocyte Heterogeneity: Consequences for Monocyte-Derived Immune Cells

Blood monocytes are precursors of dendritic cells, macrophages, and osteoclasts. They are a heterogeneous cell population with differences in size, phenotype, and function. Although monocytes maintain several tissue-specific populations of immune cells in homeostasis, their contribution to populations of dendritic cells, macrophages, and osteoclasts is significantly increased in inflammation. Identification of a growing number of functionally different subsets of cells within populations of monocyte-derived immune cells has recently put monocyte heterogeneity into sharp focus. Here, we summarize recent findings in monocyte heterogeneity and their differentiation into dendritic cells, macrophages, and osteoclasts. We also discuss these advances in the context of the formation of functionally different monocyte-derived subsets of dendritic cells, macrophages, and osteoclasts.

The macrophages in testis function

Testicular macrophages are the largest leukocyte population in the testis. Their environment is characterized by the seemingly contradictory needs for tolerance against the autoantigenic germ cells and the capacity to mount pro-inflammatory innate immune responses against invading pathogens. During the past years considerable progress has been made in our understanding how intracellular signaling events enable testicular macrophages to adequately respond to inflammatory stimuli with the capacity to clear pathogens, but avoid excessive tissue damage to maintain fertility. Moreover, new data add to our understanding that testicular macrophages play essential roles in normal testis homeostasis and fetal testicular development.

Maternal monocytes in pregnancy and preeclampsia in humans and in rats

Monocytes are short-lived cells, arising from the bone marrow and maturing in the circulation. They play an important role in immune responses and are thought to be important for healthy pregnancy. In humans, 3 subpopulations of monocytes have been identified: classical, intermediate and non-classical monocytes. These subpopulations have different functions and phenotypical characteristics. Healthy pregnancy is characterized by a pro-inflammatory condition, with increased numbers of monocytes and monocyte activation as well as with increased numbers of intermediate monocytes and decreased numbers of classical monocytes. This may suggest monocyte maturation. Preeclampsia is an important pregnancy complication characterized by hypertension and proteinuria developing in the second half of pregnancy. The pathophysiology of preeclampsia is associated with further activation of the inflammatory response, further activation of monocytes and further monocyte maturation. In the present review we focus on the role of monocyte activation and maturation in healthy and preeclamptic pregnancy.

Current advances in orthodontic pain

Orthodontic pain is an inflammatory pain that is initiated by orthodontic force-induced vascular occlusion followed by a cascade of inflammatory responses, including vascular changes, the recruitment of inflammatory and immune cells, and the release of neurogenic and pro-inflammatory mediators. Ultimately, endogenous analgesic mechanisms check the inflammatory response and the sensation of pain subsides. The orthodontic pain signal, once received by periodontal sensory endings, reaches the sensory cortex for pain perception through three-order neurons: the trigeminal neuron at the trigeminal ganglia, the trigeminal nucleus caudalis at the medulla oblongata and the ventroposterior nucleus at the thalamus. Many brain areas participate in the emotion, cognition and memory of orthodontic pain, including the insular cortex, amygdala, hippocampus, locus coeruleus and hypothalamus. A built-in analgesic neural pathway—periaqueductal grey and dorsal raphe—has an important role in alleviating orthodontic pain. Currently, several treatment modalities have been applied for the relief of orthodontic pain, including pharmacological, mechanical and behavioural approaches and low-level laser therapy. The effectiveness of nonsteroidal anti-inflammatory drugs for pain relief has been validated, but its effects on tooth movement are controversial. However, more studies are needed to verify the effectiveness of other modalities. Furthermore, gene therapy is a novel, viable and promising modality for alleviating orthodontic pain in the future.

Monocyte Differentiation towards Protumor Activity Does Not Correlate with M1 or M2 Phenotypes

Macrophages facilitate breast cancer progression. Macrophages were initially classified as M1 or M2 based on their distinct metabolic programs and then expanded to include antitumoral (M1) and protumoral (M2) activities. However, it is still uncertain what markers define the pro- and antitumoral phenotypes and what conditions lead to their formation. In this study, monocytic cell lines and primary monocytes were subjected to commonly reported protocols of M1/M2 polarization and conditions known to engage monocytes into protumoral functions. The results showed that only IDO enzyme and CD86 M1 markers were upregulated correlating with M1 polarization. TNF-α, CCR7, IL-10, arginase I, CD36, and CD163 were expressed indistinguishably from M1 or M2 polarization. Similarly, protumoral engaging resulted in upregulation of both M1 and M2 markers, with conditioned media from the most aggressive breast cancer cell line promoting the greatest changes. In spite of the mixed phenotype, M1-polarized macrophages exhibited the highest expression/secretion of inflammatory mediators, many of which have previously been associated with breast cancer aggressiveness. These data argue that although the existence of protumoral macrophages is unquestionable, their associated phenotypes and the precise conditions driving their formation are still unclear, and those conditions may need both M1 and M2 stimuli.

IL4 induces IL6-producing M2 macrophages associated to inhibition of neuroinflammation in vitro and in vivo

Background

Myeloid cells, such as macrophages and microglia, play a crucial role in neuroinflammation and have been recently identified as a novel therapeutic target, especially for chronic forms. The general aim would be to change the phenotype of myeloid cells from pro- to anti-inflammatory, favoring their tissue-trophic and regenerative functions. Myeloid cells, however, display a number of functional phenotypes, not immediately identifiable as pro- or anti-inflammatory, and associated to ambiguous markers.

Methods

We employed in vitro assays to study macrophage polarization/differentiation in the presence of classical polarizing stimuli such as IFNγ (pro-inflammatory) and IL4 (anti-inflammatory). We induced neuroinflammation in mice by immunization with a myelin antigen and treated diseased mice with intracisternal delivery of an IL4-expressing lentiviral vector. We analyzed clinical, pathological, and immunological outcomes with a focus on myeloid cells.

Results

We found that IL6, usually considered a pro-inflammatory cytokine, was released in vitro by macrophages treated with the anti-inflammatory cytokine IL4. We show the existence of macrophages expressing IL6 along with classical anti-inflammatory markers such as CD206 and demonstrate that these cells are immunosuppressive in vitro. In neuroinflamed mice, we show that IL4 delivery in the central nervous system (CNS) is associated with clinical and pathological protection from disease, associated with increased IL6 expression in infiltrating macrophages.

Conclusions

IL6 is known to mediate both pro- and anti-inflammatory effects, having two distinct ways to induce cell-signaling: either through the membrane bound receptor (anti-inflammatory) or through trans-signaling (pro-inflammatory). We show here that IL6-expressing macrophages are associated to protection from neuroinflammation, suggesting that IL6 anti-inflammatory properties prevail in the CNS, and calling for a general reconsideration of IL6 in macrophage polarization.

Electronic supplementary material

The online version of this article (doi:10.1186/s12974-016-0596-5) contains supplementary material, which is available to authorized users.

Establishing a Proteomics-Based Monocyte Assay To Assess Differential Innate Immune Activation Responses

Innate immune cells are complex systems that can be simultaneously activated in a variety of ways. Common methods currently used to estimate the response of innate immune cells to stimuli are usually biased toward a single mode of activation. The aim of this study was to assess the possibility of designing an assay based on unbiased proteome analysis that would be capable of predicting the complex response of the innate immune system to various challenges. Monocytes were used as representative cells of the innate immune system. The underlying hypothesis was that their proteome response to different activating molecules would reflect the immunogenicity of these molecules. To identify the main modes of response, we treated the human monocytic THP-1 cell line with nine different stimuli. Differentiation and activation were determined to be the two major modes of monocyte response, with PMA causing the strongest differentiation and Pam3CSK4 causing the strongest proinflammatory activation. The established assay was applied to characterize the monocyte response to epidermal growth factor peptide containing isoaspartate, which induced differentiation but not proinflammatory activation. Because of its versatility, robustness, and specificity, this new assay is likely to find a niche among the more established immunological methods.

Monocyte and interferon based therapy for the treatment of ovarian cancer

Cytokines and cells of the innate immune system have been shown to be critical regulators in the elimination, equilibrium and escape of malignant cells. Despite in vitro and in vivo evidence, components of the innate immune system have shown limited efficacy in the treatment of ovarian cancer. Intraperitoneal immunotherapies are a promising field that has not yet been fully explored in ovarian cancer. Cytokine immunotherapy using interferon alpha (IFN-α) and interferon gamma (IFN-γ) has predominantly been used intraperitoneally in ovarian cancer, with promising results. Early studies also showed that autologous monocytes infused into the peritoneum have anti-tumor properties. Combination therapies have been shown to be more effective in treating cancer than mono-therapies. Based on these observations the combination of cell therapy with cytokine therapy may provide a unique strategy for the treatment of chemotherapy resistant solid cancers.

Detection and treatment of atherosclerosis using nanoparticles

Atherosclerosis is the key pathogenesis of cardiovascular disease, which is a silent killer and a leading cause of death in the United States. Atherosclerosis starts with the adhesion of inflammatory monocytes on the activated endothelial cells in response to inflammatory stimuli. These monocytes can further migrate into the intimal layer of the blood vessel where they differentiate into macrophages, which take up oxidized low-density lipoproteins and release inflammatory factors to amplify the local inflammatory response. After accumulation of cholesterol, the lipid-laden macrophages are transformed into foam cells, the hallmark of the early stage of atherosclerosis. Foam cells can die from apoptosis or necrosis, and the intracellular lipid is deposed in the artery wall forming lesions. The angiogenesis for nurturing cells is enhanced during lesion development. Proteases released from macrophages, foam cells, and other cells degrade the fibrous cap of the lesion, resulting in rupture of the lesion and subsequent thrombus formation. Thrombi can block blood circulation, which represents a major cause of acute heart events and stroke. There are generally no symptoms in the early stages of atherosclerosis. Current detection techniques cannot easily, safely, and effectively detect the lesions in the early stages, nor can they characterize the lesion features such as the vulnerability. While the available therapeutic modalities cannot target specific molecules, cells, and processes in the lesions, nanoparticles appear to have a promising potential in improving atherosclerosis detection and treatment via targeting the intimal macrophages, foam cells, endothelial cells, angiogenesis, proteolysis, apoptosis, and thrombosis. Indeed, many nanoparticles have been developed in improving blood lipid profile and decreasing inflammatory response for enhancing therapeutic efficacy of drugs and decreasing their side effects. WIREs Nanomed Nanobiotechnol 2017, 9:e1412. doi: 10.1002/wnan.1412 For further resources related to this article, please visit the WIREs website.

The effect of hypothermia on influx of leukocytes in the digital lamellae of horses with oligofructose-induced laminitis

Sepsis-related laminitis (SRL) is a common complication in the septic/endotoxemic critically-ill equine patient, in which lamellar injury and failure commonly lead to crippling distal displacement of the distal phalanx. Similar to organ injury in human sepsis, lamellar injury in SRL has been associated with inflammatory events, including the influx of leukocytes into the lamellar tissue and markedly increased expression of a wide array of inflammatory mediators at the onset of Obel grade 1 (OG1) laminitis. The only treatment reported both clinically and experimentally to protect the lamellae in SRL, local hypothermia ("cryotherapy"), has been demonstrated to effectively inhibit lamellar expression of multiple inflammatory mediators when initiated at the time of administration of a carbohydrate overload in experimental models of SRL. However, the effect of hypothermia on leukocyte influx into affected tissue has not been assessed. We hypothesized that cryotherapy inhibits leukocyte emigration into the digital lamellae in SRL. Immunohistochemical staining using leukocyte markers MAC387 (marker of neutrophils, activated monocytes) and CD163 (monocyte/macrophage-specific marker) was performed on archived lamellar tissue samples from an experimental model of SRL in which one forelimb was maintained at ambient temperature (AMB) and one forelimb was immersed in ice water (ICE) immediately following enteral oligofructose administration (10g/kg, n=14 horses). Lamellae were harvested at 24h post-oligofructose administration (DEV, n=7) or at the onset of OG1 laminitis (OG1, n=7). Both MAC387-positive and CD163-positive cells were counted by a single blinded investigator on images [n=10 (40× fields/digit for MAC387 and 20x fields/digit for CD163)] obtained using Aperio microscopy imaging analysis software. Data were assessed for normality and analyzed with a paired t-test and one-way ANOVA with significance set at p<0.05. MAC387-positive cells were present in low numbers in the lamellar tissue and were decreased in the hypothermic limbs (vs. AMB limbs, p<0.05) in the OG1 group; no change in CD163-positive cell numbers was noted across the conditions of the model. This study demonstrated that hypothermia of the distal limbs instituted early in the disease process in the horse at risk of SRL significantly attenuates the increase of MAC387-positive leukocytes in the digital lamellae, but has minimal effect on increases in lamellar concentrations of the major leukocyte cell type present in that tissue, CD163-positive mononuclear cells.

Enhanced Activity of the Macrophage M1/M2 Phenotypes and Phenotypic Switch to M1 in Periodontal Infection

BACKGROUND

Macrophages are central players in the pathogenesis of periodontitis. However, the phenotypic switch of macrophage M1/M2 remains uncertain.

METHODS

Adult male mice were divided into periodontitis (P) or control (C) groups. Bone marrow-derived macrophages (BMMs) were stimulated with Porphyromonas gingivalis lipopolysaccharide (LPS). In both the periodontium and serum, macrophage M1 and M2 phenotypes were detected in vivo and in vitro via the following: 1) immunofluorescence; 2) immunohistochemistry; 3) electrochemiluminescence immunoassays; 4) quantitative polymerase chain reaction assays; and 5) enzyme-linked immunosorbent assays. The M1-type markers used included the following: 1) nitric oxide synthase (NOS)-2; 2) tumor necrosis factor-alpha; 3) interleukin (IL)-1β; 4) IL-6; and 5) C-reactive protein. The M2-type markers were as follows: 1) arginase-1; 2) cluster of differentiation (CD) 206; and 3) IL-10.

RESULTS

Compared with the C group, the P group had a 14-fold increase in F4/80(+) NOS2(+) cells and four-fold more F4/80(+) CD206(+) cells with an enhanced NOS2/CD206 ratio in the periodontium (P <0.01). NOS2(-) CD206(+) and dual NOS2(+) CD206(+) macrophages dominated in the C and P groups, respectively. The P group had significantly increased M1- and M2-type cytokines in both the periodontium and serum and also had an enhanced IL-6/IL-10 ratio in the serum (P <0.05). M1-type markers were significantly upregulated at the mRNA level, whereas M2-type markers were downregulated at both the mRNA and protein levels in BMMs after LPS stimulation (P <0.01).

CONCLUSION

Periodontal inflammation is associated with an enhancement of both the M1 and M2 phenotypes of macrophages, in which a phenotypic switch of M2 to M1 might be a critical mechanism in mediating periodontal tissue damage, including alveolar bone loss.

The Innate Immune System: A Trigger for Many Chronic Inflammatory Intestinal Diseases

Background

Mononuclear phagocytes, such as monocytes, macrophages, and dendritic cells, are important cellular components of the innate immune system that contribute to the pathogenesis of many intestinal inflammatory diseases.

Summary

While mononuclear phagocytes play a key role in the induction of inflammation in many different tissues through production of pro-inflammatory cytokines and chemokines (such as IL-1, TNF, IL-6, IL-8 and MCP-1), free oxygen radicals (also termed 'oxidative burst'), proteases (such as cathepsins) and tissue-degrading enzymes (such as metalloproteinases), resident macrophages as well as dendritic cells in the intestine display an anergic and 'tolerogenic' phenotype mediating tolerance to commensal bacteria. In recent years many single nucleotide polymorphisms (SNPs) in genes mainly expressed in the above-mentioned cell types have been identified to convey an increased risk of autoimmune diseases. SNPs in the NOD2, ATG16L1 and TNFSF15 genes, which are involved in the function of the innate immune cells, are identified as risk factors for Crohn's disease (CD). Of note, these genes are involved in the different functions in the innate immune cells. For example, while NOD2 is required for intracellular recognition of microbial components, ATG16L1 is involved in autophagy responses against intracellular microbes. Likewise, TNFSF15 contributes to the induction of inflammatory responses by innate immune cells. Furthermore, the frequency of mutations in these genes differs by ethnicity. Genetic variations in the NOD2 and ATG16L1 genes are associated with CD in Caucasians but much less in Eastern Asian populations, whereas SNPs in TNFSF15 are dominated in Asian populations. Thus, different genetic risks may eventually lead to similar impairments in innate immune cells, thereby developing the same disease in Western and Asian patients with CD.

Key Messages

Despite differences in risk genes, similar mechanisms associated with the innate immune system may trigger autoimmune and chronic inflammatory intestinal diseases in East and West.

Macrophages: sentinels and regulators of the immune system

The important role of macrophages in host defense against a variety of pathogens has long been recognized and has been documented and reviewed in numerous publications. Recently, it has become clear that tissue macrophages are not entirely derived from monocytes, as has been assumed for a long time, but rather show an ontogenetic dichotomy in most tissues: while part of the tissue macrophages are derived from monocytes, a major subset is prenatally seeded from the yolk sac. The latter subset shows a remarkable longevity and is maintained by self-renewal in the adult animal. This paradigm shift poses interesting questions: are these two macrophage subsets functionally equivalent cells that are recruited into the tissue at different development stages, or are both macrophage subsets discrete cell types with distinct functions, which have to exist side by side? Is the functional specialization that can be observed in most macrophages due to their lineage or due to their anatomical niche? This review will give an overview about what we know of macrophage ontogeny and will discuss the influence of the macrophage lineage and location on their functional specialization.

Engineering nanomaterials to address cell-mediated inflammation in atherosclerosis

Atherosclerosis is an inflammatory disorder with a pathophysiology driven by both innate and adaptive immunity and a primary cause of cardiovascular disease (CVD) worldwide. Vascular inflammation and accumulation of foam cells and their products induce maturation of atheromas, or plaques, which can rupture by metalloprotease action, leading to ischemic stroke or myocardial infarction. Diverse immune cell populations participate in all stages of plaque maturation, many of which directly influence plaque stability and rupture via inflammatory mechanisms. Current clinical treatments for atherosclerosis focus on lowering serum levels of low-density lipoprotein (LDL) using therapeutics such as statins, administration of antithrombotic drugs, and surgical intervention. Strategies that address cell-mediated inflammation are lacking, and consequently have recently become an area of considerable research focus. Nanomaterials have emerged as highly advantageous tools for these studies, as they can be engineered to target specific inflammatory cell populations, deliver therapeutics of wide-ranging solubilities and enhance analytical methods that include imaging and proteomics. Furthermore, the highly phagocytic nature of antigen presenting cells (APCs), a diverse cell population central to the initiation of immune responses and inflammation, make them particularly amenable to targeting and modulation by nanoscale particulates. Nanomaterials have therefore become essential components of vaccine formulations and treatments for inflammation-driven pathologies like autoimmunity, and present novel opportunities for immunotherapeutic treatments of CVD. Here, we review recent progress in the design and use of nanomaterials for therapeutic assessment and treatment of atherosclerosis. We will focus on promising new approaches that utilize nanomaterials for cell-specific imaging, gene therapy and immunomodulation.

Avian Influenza Viruses, Inflammation, and CD8(+) T Cell Immunity

Avian influenza viruses (AIVs) circulate naturally in wild aquatic birds, infect domestic poultry, and are capable of causing sporadic bird-to-human transmissions. AIVs capable of infecting humans include a highly pathogenic AIV H5N1, first detected in humans in 1997, and a low pathogenic AIV H7N9, reported in humans in 2013. Both H5N1 and H7N9 cause severe influenza disease in humans, manifested by acute respiratory distress syndrome, multi-organ failure, and high mortality rates of 60% and 35%, respectively. Ongoing circulation of H5N1 and H7N9 viruses in wild birds and poultry, and their ability to infect humans emphasizes their epidemic and pandemic potential and poses a public health threat. It is, thus, imperative to understand the host immune responses to the AIVs so we can control severe influenza disease caused by H5N1 or H7N9 and rationally design new immunotherapies and vaccines. This review summarizes our current knowledge on AIV epidemiology, disease symptoms, inflammatory processes underlying the AIV infection in humans, and recent studies on universal pre-existing CD8(+) T cell immunity to AIVs. Immune responses driving the host recovery from AIV infection in patients hospitalized with severe influenza disease are also discussed.

Tumor infiltrating immune cells in gliomas and meningiomas

Tumor-infiltrating immune cells are part of a complex microenvironment that promotes and/or regulates tumor development and growth. Depending on the type of cells and their functional interactions, immune cells may play a key role in suppressing the tumor or in providing support for tumor growth, with relevant effects on patient behavior. In recent years, important advances have been achieved in the characterization of immune cell infiltrates in central nervous system (CNS) tumors, but their role in tumorigenesis and patient behavior still remain poorly understood. Overall, these studies have shown significant but variable levels of infiltration of CNS tumors by macrophage/microglial cells (TAM) and to a less extent also lymphocytes (particularly T-cells and NK cells, and less frequently also B-cells). Of note, TAM infiltrate gliomas at moderate numbers where they frequently show an immune suppressive phenotype and functional behavior; in contrast, infiltration by TAM may be very pronounced in meningiomas, particularly in cases that carry isolated monosomy 22, where the immune infiltrates also contain greater numbers of cytotoxic T and NK-cells associated with an enhanced anti-tumoral immune response. In line with this, the presence of regulatory T cells, is usually limited to a small fraction of all meningiomas, while frequently found in gliomas. Despite these differences between gliomas and meningiomas, both tumors show heterogeneous levels of infiltration by immune cells with variable functionality. In this review we summarize current knowledge about tumor-infiltrating immune cells in the two most common types of CNS tumors-gliomas and meningiomas-, as well as the role that such immune cells may play in the tumor microenvironment in controlling and/or promoting tumor development, growth and control.

CD163(+) M2-type tumor-associated macrophage support the suppression of tumor-infiltrating T cells in osteosarcoma

Osteosarcoma is one of the most common childhood cancers with high numbers of cancer-related deaths. Progress in conventional therapies is showing limited improvement. An adaptive T cell-based immunotherapy represents a promising new therapeutic option, but to improve its efficacy, regulatory mechanisms in osteosarcoma need further elucidation. Here, to evaluate the regulatory effect of tumor microenvironment of T cells in osteosarcoma, we examined the peripheral blood (PB) and tumor infiltrating (TI) T cells, and their correlations with PB and tumor immune characteristics. We found that TI T cells contained significantly higher levels of TIM-3(+)PD-1(-) and TIM-3(+)PD-1(+) cells than their PB counterparts. Similar to that in chronic HIV and HCV infections, these TIM-3(+)PD-1(-) and TIM-3(+)PD-1(+) T cells presented reduced proliferation and proinflammatory cytokine secretion in response to stimulation. Presence of M2-type (CD163(+)) macrophages exacerbated T cell immunosuppression, since frequencies of CD163(+) tumor-associated macrophages were directly correlated with the frequencies of suppressed TIM-3(+)PD-1(+) T cells. Moreover, depletion of CD163(+) macrophages significantly improved T cell proliferation and proinflammatory cytokine production. Overall, our data presented an intratumoral T cell-specific immunosuppression that was amplified by M2-type tumor-associated macrophages.

Macrophages: An Inflammatory Link Between Angiogenesis and Lymphangiogenesis

Angiogenesis and lymphangiogenesis often occur in response to tissue injury or in the presence of pathology (e.g., cancer), and it is these types of environments in which macrophages are activated and increased in number. Moreover, the blood vascular microcirculation and the lymphatic circulation serve as the conduits for entry and exit for monocyte-derived macrophages in nearly every tissue and organ. Macrophages both affect and are affected by the vessels through which they travel. Therefore, it is not surprising that examination of macrophage behaviors in both angiogenesis and lymphangiogenesis has yielded interesting observations that suggest macrophages may be key regulators of these complex growth and remodeling processes. In this review, we will take a closer look at macrophages through the lens of angiogenesis and lymphangiogenesis, examining how their dynamic behaviors may regulate vessel sprouting and function. We present macrophages as a cellular link that spatially and temporally connects angiogenesis with lymphangiogenesis, in both physiological growth and in pathological adaptations, such as tumorigenesis. As such, attempts to therapeutically target macrophages in order to affect these processes may be particularly effective, and studying macrophages in both settings will accelerate the field's understanding of this important cell type in health and disease.

BMP-7 Treatment Increases M2 Macrophage Differentiation and Reduces Inflammation and Plaque Formation in Apo E-/- Mice

Inflammation plays a fundamental role in the inception and development of atherosclerosis (ATH). Mechanisms of inflammation include the infiltration of monocytes into the injured area and subsequent differentiation into either pro-inflammatory M1 macrophages or anti-inflammatory M2 macrophages. We have previously published data suggesting bone morphogenetic protein-7 (BMP-7) enhances M2 macrophage differentiation and anti-inflammatory cytokine secretion in vitro. In this regard, we hypothesized BMP-7 would inhibit plaque formation in an animal model of ATH through monocytic plasticity mediation. ATH was generated in male and female Apo E(-/-) mice via partial left carotid artery (PLCA) ligation and mice were divided into 3 groups: Sham, PLCA, and PLCA+BMP-7 (200 ug/kg; i.v.). Our data suggest that BMP-7 inhibits plaque formation and increases arterial systolic velocity. Furthermore, we report inhibition of monocyte infiltration and a decrease in associated pro-inflammatory cytokines (MCP-1, TNF-α, and IL-6) in the PLCA+BMP-7 mice. In contrast, our data suggest a significant (p<0.05) increase in M2 macrophage populations with consequential enhanced anti-inflammatory cytokine (IL-1RA, IL-10, and Arginase 1) expression following BMP-7 treatment. We have also observed that mechanisms promoting monocyte into M2 macrophage differentiation by BMP-7 involve the upregulation and activation of the BMP-7 receptor (BMP-7RII). In conclusion, we report that BMP-7 has the potential to mediate cellular plasticity and mitigate the inflammatory immune response, which results in decreased plaque formation and improved blood velocity.

Myeloid Extracellular Vesicles: Messengers from the Demented Brain

Blood-borne monocyte derived cells play a pivotal, initially unrecognized, role in most central nervous system disorders, including diseases initially classified as purely neurodegenerative (i.e., Alzheimer’s disease, Parkinson’s disease, and ALS). Their trafficking to the brain and spinal cord has been extensively studied in classical neuroinflammatory disorders such as multiple sclerosis. Central nervous system resident myeloid cells, namely microglia and perivascular macrophages, also are in the spotlight of investigations on neurological disorders. Myeloid cells, such as infiltrating macrophages and microglia, have been described as having both protective and destructive features in neurological disorders, thus identification of their functional phenotype during disease evolution would be of paramount importance. Extracellular vesicles, namely exosomes and shed vesicles, are released by virtually any cell type and can be detected and identified in terms of cell origin in biological fluids. They therefore constitute an ideal tool to access information on cells residing in an inaccessible site such as the brain. We will review here available information on extracellular vesicles detection in neurological disorders with special emphasis on neurodegenerative diseases.

Alterations in Monocyte Phenotypes and Functions after a Hip Fracture in Elderly Individuals: A 6-Month Longitudinal Study

BACKGROUND

Healthy elderly individuals are particularly prone to catastrophic events at any moment of their lives. One stressful event for individuals aged 65 and older is a fall that results in a fracture of the hip (HF). HF causes a state of inflammation that may affect immune responses. In this connection, we have reported that HF induced alterations in neutrophil functions.

OBJECTIVE

To assess the impact of HF on classical (cM), intermediate (iM) and non-classical (ncM) monocyte subsets.

METHODS

Distribution, functions (chemotaxis, phagocytosis, superoxide production and cytokine production), phenotype and activation (NF-x03BA;B and PI3K) were evaluated in monocyte subsets before surgery and 6 weeks and 6 months after the event.

RESULTS

The distribution of cM and ncM was unchanged, but iM transiently increased before surgery. Sustained increases (iM response to CCL2 and CX3CL1) and decreases (cM and ncM response to CCL2) in chemotaxis were observed. Phagocytosis and superoxide production were impaired in cM but not in iM or ncM. Sustained expression of HLA-DR occurred in cM but not in iM and ncM. Sustained decreased expression of CD11b occurred only in ncM. Sustained decreases (cM and ncM) and increases (iM) in CCR2 expression were observed. An elevated expression of CX3CR1 was found only in iM. cM produced elevated quantities of TNFα. There was a transient oxidative burst of production before surgery in iM and a sustained decrease in ncM. IL-10 production was severely impaired in cM and decreased in iM prior to surgery. Sustained activation (cM), inhibition (ncM) and transient activation (iM) of NF-x03BA;B were observed. Activation of PI3K was severely impaired in cM and ncM but was sustained in iM.

CONCLUSION

HF had more impact on cM and ncM functions than on iM. HF triggered a switch in cM functions from phagocytic to inflammatory elevated TNFα-producing cells. These changes may impact clinical outcomes of HF with respect to inflammation, opportunistic infections and physical recovery.

The Role of Decidual Macrophages During Normal and Pathological Pregnancy

Macrophages perform many specific functions including host defense, homeostasis, angiogenesis, and tissue development. Macrophages are the second most abundant leukocyte population in the non-pregnant endometrium and pregnant decidua and likely play a central role in the establishment and maintenance of normal pregnancy. Importantly, aberrantly activated uterine macrophages can affect trophoblast function and placental development, which may result in various adverse pregnancy outcomes ranging from pre-eclampsia to fetal growth restriction or demise. Only by fully understanding the roles of macrophage in pregnancy will we be able to develop interventions for the treatment of these various pregnancy complications. This review discusses the general origin and classification of monocytes and macrophages and focuses on the phenotype and functional roles of decidual macrophage at the maternal-fetal interface in normal pregnancy, as well as discussing the potential contribution of the abnormal state of these cells to various aspects of pregnancy pathologies.

Directing immunomodulation using biomaterials for endogenous regeneration

Stem cell therapy and tissue engineering hold considerable potential for innovative and transformative strategies to repair damaged tissue form and function. Although many approaches are adopting ex vivo expanded cells for transplantation, an alternative is to manipulate the biomaterial-host interactions that recruit the patients' own stem cells endogenously for regeneration. There are several considerations in targeting the biomaterial-host interactions therapeutically, not the least of which is the biomimetic design of extracellular matrix (ECM)-mimicking materials and the administration of navigation cues and small molecules that target specific aspects of the native healing cascades to stimulate homing of endogenous stem cells and, thereafter, their expansion and differentiation. A sequence of coordinated interactions between the local niche cells and implanted biomaterials offers signals and sign posts that may instruct the cells traveling toward the injured tissues. Furthermore, stem cell function is critically influenced by extrinsic signals provided by the niche as well as by the implanted biomaterials. Novel strategies harnessing growth factors and immunological cues to design materials not only can modulate the behavior of stem cells but also can alter innate and adaptive immunity in a controlled manner. We envisage that successful and safe endogenous regeneration will involve at least three aspects, i.e., homing of sufficient stem cells, controlling cell fate determination, and blunting host immune responses to outside biomaterial devices. Improving our understanding of the biological and physicochemical signals of biomimetic biomaterials that govern immunomodulation for in situ tissue regeneration, particularly context-dependent macrophage (Mφ) polarization, will lead to a concurrent improvement in clinical outcomes.

An Immunomodulatory Device Improves Insulin Resistance in Obese Porcine Model of Metabolic Syndrome

Obesity is associated with tissue inflammation which is a crucial etiology of insulin resistance. This inflammation centers around circulating monocytes which form proinflammatory adipose tissue macrophages (ATM). Specific approaches targeting monocytes/ATM may improve insulin resistance without the adverse side effects of generalized immunosuppression. In this regard, a biomimetic membrane leukocyte processing device, called the selective cytopheretic device (SCD), was evaluated in an Ossabaw miniature swine model of insulin resistance with metabolic syndrome. Treatment with the SCD in this porcine model demonstrated a decline in circulating neutrophil activation parameters and monocyte counts. These changes were associated with improvements in insulin resistance as determined with intravenous glucose tolerance testing. These improvements were also reflected in lowering of homeostatic model assessment- (HOMA-) insulin resistant (IR) scores for up to 2 weeks after SCD therapy. These results allow for the planning of first-in-man studies in obese type 2 diabetic patients.

Estragole and methyl-eugenol-free extract of Artemisia dracunculus possesses immunomodulatory effects

OBJECTIVE

Some evidence suggests that chronic uptake of estragole and methyl-eugenol, found in the essential oil of Artemisia dracunculus (tarragon), may be associated with an increased risk of hepato-carcinogenicity. The present study was conducted to investigate the immumodulatory and anti-inflammatory potentials of estragole and methyl-eugenol free extract of tarragon.

MATERIALS AND METHODS

Aqueous, hydroalcoholic, methanol and hexane extracts of dried and milled tarragon was prepared and analyzed by GC-MS. The estragole and methyl-eugenol free extract was characterized and used for evaluation of immunity in NMRI mice after challenging with sheep red blood cells.

RESULTS

It was shown that the aqueous extract of tarragon was free from potentially harmful estragole or methyl-eugenol. Moreover, the immunomodulatory effect of the aqueous extract of tarragon (100 mg/kg for 21 consecutive days) was investigated. The extract significantly increased the level of anti-sheep red blood cells (SRBC (antibody and simultaneously decreased the level of cellular immunity in the treatment group. Moreover, tarragon caused a significant reduction in the production of pro-inflammatory IL-17 and IFN-γ in parallel with a reduction in the ratio of INF-γ to Il-10 or IL-17 to IL-10 in the splenocytes. In addition, the levels of the respiratory burst and nitric oxide production in peritoneal macrophages were significantly decreased. Additionally, the phagocytosis potential of macrophages was significantly increased in treated mice.

CONCLUSION

These data showed that the aqueous extract of tarragon may be used as a natural source to modulate the immune system, because it can inhibit pro-inflammatory cytokines and induce anti-inflammatory macrophages.

Macrophage phenotypes in the adipose tissue of postmenopausal women

Atherosclerosis pathology is the interplay between high intravascular LDL particle concentration and monocyte/macrophage presence within the sub-endothelial space of the artery. In this project, phenotypes of macrophages connected with subclinical inflammation in adipose tissue of living kidney donors were studied. Samples of subcutaneous adipose tissue of living kidney donors (n=36) were exposed to collagenase. Stromal vascular fraction (SVF) was eluted from the samples, then labeled with monoclonal antibodies (anti-CD14 and anti-calprotectin), conjugated with fluorochromes and analyzed by flow cytometry. The positive correlation between the number of total macrophages and calprotectin-positive macrophages with BMI in the subcutaneous adipose tissue of postmenopausal women was demonstrated (p<0.05; R=0.43 and p<0.01; R=0.60), whereas no positive correlation in premenopausal women and men was shown. In conclusion, we documented a significant effect of BMI increase on the presence of total macrophages in adipose tissue of postmenopausal women, in contrast to premenopausal women. This difference was much more pronounced when proinflammatory macrophages with membrane-bound calprotectin were analyzed.

Brazilian Red Propolis Attenuates Inflammatory Signaling Cascade in LPS-Activated Macrophages

Although previous studies suggested an anti-inflammatory property of Brazilian red propolis (BRP), the mechanisms involved in the anti-inflammatory effects of BRP and its activity on macrophages were still not elucidated. This study aimed to evaluate whether BRP attenuates the inflammatory effect of LPS on macrophages and to investigate its underlying mechanisms. BRP was added to RAW 264.7 murine macrophages after activation with LPS. NO production, cell viability, cytokines profile were evaluated. Activation of inflammatory signaling pathways and macrophage polarization were determined by RT-qPCR and Western blot. BRP at 50 μg/ml inhibited NO production by 78% without affecting cell viability. Cd80 and Cd86 were upregulated whereas mrc1 was down regulated by BRP indicating macrophage polarization at M1. BRP attenuated the production of pro-inflammatory mediators IL-12, GM-CSF, IFN-Ɣ, IL-1β in cell supernatants although levels of TNF- α and IL-6 were slightly increased after BRP treatment. Levels of IL-4, IL-10 and TGF-β were also reduced by BRP. BRP significantly reduced the up-regulation promoted by LPS of transcription of genes in inflammatory signaling (Pdk1, Pak1, Nfkb1, Mtcp1, Gsk3b, Fos and Elk1) and of Il1β and Il1f9 (fold-change rate > 5), which were further confirmed by the inhibition of NF-κB and MAPK signaling pathways. Furthermore, the upstream adaptor MyD88 adaptor-like (Mal), also known as TIRAP, involved in TLR2 and TLR4 signaling, was down- regulated in BRP treated LPS-activated macrophages. Given that BRP inhibited multiple signaling pathways in macrophages involved in the inflammatory process activated by LPS, our data indicated that BRP is a noteworthy food-source for the discovery of new bioactive compounds and a potential candidate to attenuate exhacerbated inflammatory diseases.

CD11c(hi) Dendritic Cells Regulate Ly-6C(hi) Monocyte Differentiation to Preserve Immune-privileged CNS in Lethal Neuroinflammation

Although the roles of dendritic cells (DCs) in adaptive defense have been defined well, the contribution of DCs to T cell-independent innate defense and subsequent neuroimmunopathology in immune-privileged CNS upon infection with neurotropic viruses has not been completely defined. Notably, DC roles in regulating innate CD11b⁺Ly-6C^hi monocyte functions during neuroinflammation have not yet been addressed. Using selective ablation of CD11c^hiPDCA-1^int/lo DCs without alteration in CD11c^intPDCA-1^hi plasmacytoid DC number, we found that CD11c^hi DCs are essential to control neuroinflammation caused by infection with neurotropic Japanese encephalitis virus, through early and increased infiltration of CD11b⁺Ly-6C^hi monocytes and higher expression of CC chemokines. More interestingly, selective CD11c^hi DC ablation provided altered differentiation and function of infiltrated CD11b⁺Ly-6C^hi monocytes in the CNS through Flt3-L and GM-CSF, which was closely associated with severely enhanced neuroinflammation. Furthermore, CD11b⁺Ly-6C^hi monocytes generated in CD11c^hi DC-ablated environment had a deleterious rather than protective role during neuroinflammation, and were more quickly recruited into inflamed CNS, depending on CCR2, thereby exacerbating neuroinflammation via enhanced supply of virus from the periphery. Therefore, our data demonstrate that CD11c^hi DCs provide a critical and unexpected role to preserve the immune-privileged CNS in lethal neuroinflammation via regulating the differentiation, function, and trafficking of CD11b⁺Ly-6C^hi monocytes.

Immunoregulatory Role of Myeloid-derived Cells in Inflammatory Bowel Disease

As the frontiers of immunological research expand, new insights into the pathogenesis of long poorly understood diseases, such as inflammatory bowel disease (IBD), are opening up new possible avenues for treatment. Myeloid-derived cells (i.e., monocytes, macrophages, neutrophils, and dendritic cells), long believed to be effector cells driving the initiation of inflammation, have been increasingly shown to have immunoregulatory effects previously underappreciated. Dysfunction in the immunoregulatory roles of these cells may play a part in the pathogenesis of a subset of patients with IBD. The role of myeloid-derived suppressor cells, initially described in cancer, have been shown to play an important role in the balancing of effector and regulatory T cells in inflammation as well, and their role in IBD is also explored. The potential for future cell-based therapies for IBD is enhanced by the advances being made in the understanding of the innate immune system in the intestine.

Driving change: kidney proximal tubule CSF-1 polarizes macrophages

Macrophage colony-stimulating factor (CSF-1 or M-CSF) is important for kidney repair after acute kidney injury (AKI). CSF-1 is upregulated in tubule epithelial cells in response to kidney injury stimuli and binds to its sole receptor, CSF1R, in an autocrine and paracrine manner. Wang and colleagues used a genetic approach to constitutively delete Csf1 in proximal tubules to establish that proximal tubule production of CSF-1 is important for polarizing and skewing macrophages toward an M2 phenotype, and for recovery from AKI.

GM-CSF and the role of myeloid regulatory cells in the pathogenesis and treatment of Crohn's disease

Background

Intestinal monocytes/macrophages sustain the intestinal immune homeostasis and might be an attractive therapeutic target for the management of inflammatory bowel disease (IBD). Granulocyte macrophage colony-stimulating factor (GM-CSF) exerts beneficial effects on intestinal inflammation and promotes signal transducer and activator of transcription 3 (STAT3)-mediated expansion of myeloid-derived suppressor cells (MDSCs). However, the full action mechanism of GM-CSF, and especially whether monocytes mediate its therapeutic effects in vivo, had not been previously elucidated.

Conclusions

This review article summarizes recent developments in the immunology of mucosal diseases and describes new aspects of the role of myeloid regulatory cells in IBD and the function of GM-CSF in maintaining the intestinal immune homeostasis in Crohn’s disease (CD). This review article highlights the exploration of stimulating in addition to suppressive therapies for patients with IBD and underpins that myeloid regulatory cells might become a promising novel cell-based therapeutic option.

Bisphosphonates for cancer treatment: Mechanisms of action and lessons from clinical trials

A growing body of evidence points toward an important anti-cancer effect of bisphosphonates, a group of inexpensive, safe, potent, and long-term stable pharmacologicals that are widely used as osteoporosis drugs. To date, they are already used in the prevention of complications of bone metastases. Because the bisphosphonates can also reduce mortality in among other multiple myeloma, breast, and prostate cancer patients, they are now thoroughly studied in oncology. In particular, the more potent nitrogen-containing bisphosphonates have the potential to improve prognosis. The first part of this review will elaborate on the direct and indirect anti-tumoral effects of bisphosphonates, including induction of tumor cell apoptosis, inhibition of tumor cell adhesion and invasion, anti-angiogenesis, synergism with anti-neoplastic drugs, and enhancement of immune surveillance (e.g., through activation of γδ T cells and targeting macrophages). In the second part, we shed light on the current clinical position of bisphosphonates in the treatment of hematological and solid malignancies, as well as on ongoing and completed clinical trials investigating the therapeutic effect of bisphosphonates in cancer. Based on these recent data, the role of bisphosphonates is expected to further expand in the near future outside the field of osteoporosis and to open up new avenues in the treatment of malignancies.

Is the Amount of Coronary Perivascular Fat Related to Atherosclerosis?

Interesting and stimulating data about the effect of the perivascular adipose tissue size on atherogenesis are based mainly on CT findings. We studied this topic by directly analyzing perivascular adipose tissue in explanted hearts from patients undergoing transplantation. Ninety-six consecutive patients were included, including 58 with atherosclerotic coronary heart disease (CHD) and 38 with dilation cardiomyopathy (DCMP). The area of perivascular fat, area of the coronary artery wall, and ratio of CD68-positive macrophages within the perivascular fat and within the vascular wall were quantified by immunohistochemistry. There was no significant difference in the perivascular adipose tissue size between the two groups. Nevertheless, there was a significantly higher number of macrophages in the coronary arterial wall of CHD patients. In addition, we found a close relationship between the ratio of macrophages in the arterial wall and adjacent perivascular adipose tissue in the CHD group, but not in the DCMP group. According to our data interaction between macrophages in the arterial wall and macrophages in surrounding adipose tissue could be more important mechanism of atherogenesis than the size of this tissue itself.

From Antigen Delivery System to Adjuvanticy: The Board Application of Nanoparticles in Vaccinology

In the last years, nanotechnologies have raised great interest because of the potential applications of engineered nanoparticles in nanomedicine (i.e., in vaccination, in diagnostic imaging procedures, and as therapeutic drug delivery systems). The use of nanoparticles in medicine has brought about the issue of their interaction with the immune system for two main reasons: first, understanding how long nanomedicines could persist in the organism and exert their beneficial effects before being recognized and eliminated by our defensive systems; second, understanding how the immune responses can be modulated by nanoparticles in order to obtain optimal effects. This issue is crucial in vaccine formulations based on the use of nanoparticles, which can operate both as a delivery system to enhance antigen processing and as an immunostimulatory adjuvant to induce and amplify protective immunity, in part because of their ability to activate the inflammasome and induce the maturation of interleukin 1β. Nanoparticles can be excellent adjuvants due to their biocompatibility and their physicochemical properties (e.g., size, shape, and surface charge), which can be tailored to obtain different immunological effects. This review provides an overview of recent strategies for the use of nanoparticles as promising/attractive adjuvants for novel prophylactic and therapeutic vaccines. The use of nanovaccines, with their practically infinite possibilities of specific design, could open the way to precision vaccinology, i.e., vaccine formulations tailored on the individual immune reactivity status.