Macrophages sequentially change their functional phenotype in response to changes in microenvironmental influences

Transferrin Enhances Microglial Phagocytic Capacity

Transferrin (Tf) is a glycoprotein playing a critical role in iron homeostasis and transport and distribution throughout the body and within tissues and cells. This molecule has been shown to accelerate the process of myelination and remyelination in the central nervous system (CNS) in vivo and induce oligodendroglial cell maturation in vitro. While the mechanisms involved in oligodendroglial precursor cell (OPC) differentiation have not been fully elucidated yet, our group has previously described the first molecular events taking place in OPC in response to extracellular Tf. Here, we show the effect of Tf on the different glial cell populations. We demonstrate that, after a CNS demyelinating injury, Tf can be incorporated by all glial cells-i.e., microglia, astrocytes, and OPC-and that, acting on microglial cells in vitro, Tf increases microglial proliferation rates and phagocytic capacity. It may be then speculated that the in vivo correlation of this process could generate a favorable microenvironment for OPC maturation and remyelination.

Splenectomy Promotes Macrophage Polarization in a Mouse Model of Concanavalin A- (ConA-) Induced Liver Fibrosis

Background

Splenectomy can improve liver function and survival in patients with autoimmune hepatitis (AIH) and liver cirrhosis. We investigated the underlying mechanism in a mouse model of concanavalin A- (ConA-) induced liver fibrosis.

Methods

We used ConA to induce immune liver fibrosis in BALB/c mice. Splenectomy was performed alone or with the administration of dexamethasone (DEX). Changes in blood and liver tissues were evaluated.

Results

Mice treated with ConA for 7 weeks developed advanced liver fibrosis, while splenectomy suppressed liver fibrosis. Although the populations of macrophages/monocytes and M1 macrophages decreased after splenectomy, the inflammatory factors associated with M2 macrophages increased after splenectomy. Furthermore, the population of circulating CD11b⁺Ly6C^high myeloid-derived suppressor cells (MDSCs) increased after splenectomy. After ConA treatment, elevated levels of activated and total NF-kBp65/p50 combined with DNA were observed in hepatic tissues. In contrast, the levels of NF-κB p65/p50 decreased after splenectomy.

Conclusions

Splenectomy may promote the polarization of CD11b⁺Ly6C^high MDSCs and the differentiation of M2 macrophages while restricting the level of NF-κB p65-p50 heterodimers. These factors may suppress the progression of liver fibrosis.

Identification of alterations in macrophage activation associated with disease activity in systemic lupus erythematosus

Systemic lupus erythematosus (SLE) is characterized by abnormalities in B cell and T cell function, but the role of disturbances in the activation status of macrophages (Mϕ) has not been well described in human patients. To address this, gene expression profiles from isolated lymphoid and myeloid populations were analyzed to identify differentially expressed (DE) genes between healthy controls and patients with either inactive or active SLE. While hundreds of DE genes were identified in B and T cells of active SLE patients, there were no DE genes found in B or T cells from patients with inactive SLE compared to healthy controls. In contrast, large numbers of DE genes were found in myeloid cells (MC) from both active and inactive SLE patients. Among the DE genes were several known to play roles in Mϕ activation and polarization, including the M1 genes STAT1 and SOCS3 and the M2 genes STAT3, STAT6, and CD163. M1-associated genes were far more frequent in data sets from active versus inactive SLE patients. To characterize the relationship between Mϕ activation and disease activity in greater detail, weighted gene co-expression network analysis (WGCNA) was used to identify modules of genes associated with clinical activity in SLE patients. Among these were disease activity-correlated modules containing activation signatures of predominantly M1-associated genes. No disease activity-correlated modules were enriched in M2-associated genes. Pathway and upstream regulator analysis of DE genes from both active and inactive SLE MC were cross-referenced with high-scoring hits from the drug discovery Library of Integrated Network-based Cellular Signatures (LINCS) to identify new strategies to treat both stages of SLE. A machine learning approach employing MC gene modules and a generalized linear model was able to predict the disease activity status in unrelated gene expression data sets. In summary, altered MC gene expression is characteristic of both active and inactive SLE. However, disease activity is associated with an alteration in the activation of MC, with a bias toward the M1 proinflammatory phenotype. These data suggest that while hyperactivity of B cells and T cells is associated with active SLE, MC potentially direct flare-ups and remission by altering their activation status toward the M1 state.

Significance of M2 macrophage in tubulointerstitial disease secondary to primary Sjogren's disease

Objective: M2 Macrophages could improve tubulointerstitial disease in animal models. HIF-1αpromotes macrophage polarization and is involved in tubular injury. The study aims to observe the clinicopathologic significance of M2 macrophage and HIF-1α in tubulointerstitial injury secondary to primary Sjogren's disease.

Methods: Renal tissue samples from patients with tubulointerstitial disease secondary to primary Sjogren's disease (SS, n = 10), chronic tubulointerstitial nephritis secondary to drug (CIN, n = 8) were included in this study. The expression of CD163, CD68 and HIF-1α were examined by immunohistochemistry or immunofluorescence.

Results: (1) Renal involvement was the first manifestation in seven of ten (7/10) patients with pSS, including proteinuria, renal dysfunction, renal tubular acidosis and multiple renal stone; and two patient had intractable hypokalemia. (2) There were numerous CD163- positive cells and CD68- positive cells infiltration in tubulointerstitial injury of pSS, especially in patients with hypokalemia. CD163 positive cells and HIF-1αwere mainly expressed in acute tubulointerstitial injury of pSS, which positively correlated to N-acetyl-β-D-glucosaminidase and β2-microglobulin. (3) Compared with CIN, patients with pSS had higher serum globulin level, erythrocyte sedimentation rate (ESR) and lower urinary osmotic pressure. (4) During follow-up of one year, six patients with pSS and acute tubular injury acquired improved renal function on therapy of steroid and total glucosides of peony. The remaining four patients with pSS had stable renal function.

Conclusion: M2 macrophages are involved in acute tubular injury in patients with primary Sjogren's disease. Early intervention can improve renal function of tubulointerstitial injury secondary to primary Sjogren's disease.

Dental pulp-derived stem cell conditioned medium to regenerate peripheral nerves in a novel animal model of dysphagia

In nerve regeneration studies, various animal models are used to assess nerve regeneration. However, because of the difficulties in functional nerve assessment, a visceral nerve injury model is yet to be established. The superior laryngeal nerve (SLN) plays an essential role in swallowing. Although a treatment for SLN injury following trauma and surgery is desirable, no such treatment is reported in the literature. We recently reported that stem cells derived from human exfoliated deciduous teeth (SHED) have a therapeutic effect on various tissues via macrophage polarization. Here, we established a novel animal model of SLN injury. Our model was characterized as having weight loss and drinking behavior changes. In addition, the SLN lesion caused a delay in the onset of the swallowing reflex and gain of laryngeal residue in the pharynx. Systemic administration of SHED-conditioned media (SHED-CM) promoted functional recovery of the SLN and significantly promoted axonal regeneration by converting of macrophages to the anti-inflammatory M2 phenotype. In addition, SHED-CM enhanced new blood vessel formation at the injury site. Our data suggest that the administration of SHED-CM may provide therapeutic benefits for SLN injury.

Membrane PD-L1 expression and soluble PD-L1 plasma levels in idiopathic pulmonary fibrosis-a pilot study

Background

Idiopathic pulmonary fibrosis (IPF) has common risk factors with cancer and significant similarities in the pathobiology process, both diseases having poor outcomes. Immune checkpoint PD-L1 has become the target of checkpoint inhibitory therapy that unleashes antitumor T cells and has revolutionized cancer treatment. This is a pilot study exploring membrane immune checkpoint PD-L1 expression in human IPF lung tissue samples and its soluble form, soluble PD-L1 (sPD-L1) plasma concentrations in IPF patients, in order to investigate potential role of PD-L1 as an IPF biomarker.

Methods

Twelve human IPF lung tissue samples (formalin-fixed, paraffin-embedded) obtained by surgical biopsy, have been tested for PD-L1 expression by PD-L1 IHC 22C3 pharmDx assay, while plasma samples for examination of sPD-L1 forms, PD-L1 (B7-H1/CD274) blood concentration, originated from 23 patients with IPF who did not undergo surgical biopsy.

Results

Membrane PD-L1 expression in IPF lung tissue samples was positive to overexpression of PD-L1 in 9 samples out of 12. Only very few cells in the interstitium have shown a discrete PD-L1 expression, but not of a membrane type. As for sPD-L1 forms, we have found elevated concentrations of sPD-L1 in the serum of IPF patients 314.3 ng/L (117.7-483.1 ng/L), significantly higher compared with healthy control group 91.0 ng/L (52.4-119.7 ng/L), P<0.01.

Conclusions

For IPF with PD-L1 expression on alveolar macrophages, further studies are necessary to elucidate this phenomenon. Serum sPD-1/PD-L1 is easily detected in clinical practice and should be further evaluated as a potential prognostic or/and predictive biomarker in IPF.

Molecular Interactions Between Innate and Adaptive Immune Cells in Chronic Lymphocytic Leukemia and Their Therapeutic Implications

Innate immunity constitutes the first line of host defense against various anomalies in humans, and it also guides the adaptive immune response. The function of innate immune components and adaptive immune components are interlinked in hematological malignancies including chronic lymphocytic leukemia (CLL), and molecular interactions between innate and adaptive immune components are crucial for the development, progression and the therapeutic outcome of CLL. In this leukemia, genetic mutations in B cells and B cell receptors (BCR) are key driving factors along with evasion of cytotoxic T lymphocytes and promotion of regulatory T cells. Similarly, the release of various cytokines from CLL cells triggers the protumor phenotype in macrophages that further edges the CLL cells. Moreover, under the influence of various cytokines, dendritic cells are unable to mature and trigger T cell mediated antitumor response. The phenotypes of these cells are ultimately controlled by respective signaling pathways, the most notables are BCR, Wnt, Notch, and NF-κB, and their activation affects the cytokine profile that controls the pathogenesis of CLL, and challenge its treatment. There are several novel substances for CLL under clinical development, including kinase inhibitors, antibodies, and immune-modulators that offer new hopes. DC-based vaccines and CAR T cell therapy are promising tools; however, further studies are required to precisely dissect the molecular interactions among various molecular entities. In this review, we systematically discuss the involvement, common targets and therapeutic interventions of various cells for the better understanding and therapy of CLL.

The role of the hypoxia-Nrp-1 axis in the activation of M2-like tumor-associated macrophages in the tumor microenvironment of cervical cancer

To explore the mechanisms through which hypoxic tumor microenvironment (TME) modulates the transition of tumor-associated macrophages (TAMs). The migration ability of RAW264.7 macrophages was determined by transwell assay. Flow cytometric, western blot and immunofluorescence analyses of CD206 further validated the M2 polarization of macrophages. Immunofluorescence, western blot and qRT-PCR were performed to detect the expression of neuropilin-1 (Nrp-1) and carbonic anhydrase IX (CAIX). An intermittent hypobaric hypoxia (IH) animal model was established to evaluate the role of hypoxia in activating M2-like TAMs in vivo. We also used immunohistochemistry to analyze the association between CAIX, CD163+ macrophages and Nrp-1 in a series of 72 human cervical cancer specimens. We found that the hypoxic cervical TME educated the recruited macrophages to transform into the M2 phenotype. Nrp-1 expression was significantly increased in hypoxia-primed cervical cancer cells. Blocking Nrp-1 expression prevented hypoxic cells from recruiting and polarizing macrophages towards the M2 phenotype. Hypoxia exposure significantly increased the expression of Nrp-1 as well as the infiltration of macrophages in vivo. Consistently, immunochemical staining in serial tissue sections of cervical cancer revealed upregulated levels of Nrp-1 in CAIX-positive hypoxic regions along with a concurrent significant elevation of M2 macrophages. Nrp-1 and M2-like TAMs were related to the malignant properties of cervical cancer, such as the FIGO stage and lymph node metastasis. Nrp-1 plays critical roles in hypoxic TME-induced activation and pro-tumoral effects of TAMs in cervical cancer. Interfering with Nrp-1 may be a potential therapeutic strategy in treating cervical cancer.

NecroX-5 ameliorates inflammation by skewing macrophages to the M2 phenotype

This study aimed to evaluate the role of NecroX-5, a powerful anti-inflammatory agent, on the functional plasticity of macrophages and the possible underlying mechanism using RAW264.7 cells, thioglycollate-elicited peritoneal macrophages from C57BL/6 mice, and a murine model of dextran sodium sulfate (DSS)-induced colitis. The change in cell morphology was examined by scanning electron microscopy. The expression of CD206, arginase (Arg)-1, and inducible nitric oxide synthase (iNOS) were examined by western blotting. The production of inflammatory cytokines was detected by enzyme-linked immunosorbent assays and statistical comparisons were made. The results showed that treatment of RAW264.7 cells with NecroX-5 caused an elongated shape in comparison to non-treated cells. The expression levels of macrophage mannose receptor CD206 and Arg-1, specific markers of M2 cells, were significantly upregulated by NecroX-5 treatment, while those of iNOS (M1 macrophages) was decreased. In addition, NecroX-5 significantly reduced the secretion of inflammatory cytokines, while interleukin (IL)-4 and IL-13 secretion in the supernatant was significantly enhanced. Treatment with NecroX-5 considerably ameliorated the progression of DSS-induced colitis and significantly inhibited the mRNA expression of pro-inflammatory cytokines, including tumor necrosis factor-α and IL-1β. Taken together, our findings demonstrated that NecroX-5 might dampen inflammation by switching the M1 phenotype to the M2 phenotype due to IL-4 and IL-13 induction.

Transcriptome Analysis Provides Insights into the Markers of Resting and LPS-Activated Macrophages in Grass Carp (Ctenopharyngodon idella)

Macrophages are very versatile immune cells, with the characteristics of a proinflammatory phenotype in response to pathogen-associated molecular patterns. However, the specific activation marker genes of macrophages have not been systematically investigated in teleosts. In this work, leukocytes (WBC) were isolated using the Percoll gradient method. Macrophages were enriched by the adherent culture of WBC, then stimulated with lipopolysaccharide (LPS). Macrophages were identified by morphological features, functional activity and authorized cytokine expression. Subsequently, we collected samples, constructed and sequenced transcriptomic libraries including WBC, resting macrophage (Mø) and activated macrophage (M(LPS)) groups. We gained a total of 20.36 Gb of clean data including 149.24 million reads with an average length of 146 bp. Transcriptome analysis showed 708 differential genes between WBC and Mø, 83 differentially expressed genes between Mø and M(LPS). Combined with RT-qPCR, we proposed that four novel cell surface marker genes (CD22-like, CD63, CD48 and CD276) and two chemokines (CXCL-like and CCL39.3) would be emerging potential marker genes of macrophage in grass carp. Furthermore, CD69, CD180, CD27, XCL32a.2 and CXCL8a genes can be used as marker genes to confirm whether macrophages are activated. Transcriptome profiling reveals novel molecules associated with macrophages in C. Idella, which may represent a potential target for macrophages activation.

Visceral fat and insulin resistance - what we know?

One of the most significant challenges of current medicine is the increasing prevalence of obesity worldwide that is accompanied by a wide range of chronic health complications and increased mortality. White adipose tissue actively contributes to metabolic regulation by production of a variety of hormones and cytokines, commonly referred to as adipokines. The spectrum and quantity of adipokines produced by the adipose tissue of obese patients is directly or indirectly involved in much obesity-related pathology (type 2 diabetes mellitus, cardiovascular disease, inflammatory response). One of the underlying mechanisms linking obesity, diabetes, and cardiovascular complications is subclinical inflammation, primarily arising in visceral adipose tissue. Adipocyte size, number and polarization of lymphocytes and infiltrated macrophages are closely related to metabolic and obesity-related diseases. The storage capacity of hypertrophic adipocytes in obese patients is limited. This results in chronic energy overload and leads to increased apoptosis of adipocytes that in turn stimulates the infiltration of visceral adipose tissue by immune cells, in particular macrophages. These cells produce many proinflammatory factors; while the overall production of anti-inflammatory cytokines and adipokines is decreased. The constant release of proinflammatory factors into the circulation then contributes to a subclinical systemic inflammation, which is directly linked to the metabolic and cardiovascular complications of obesity.

Macrophage Polarization in Leishmaniasis: Broadening Horizons

Leishmaniasis is a vector-borne neglected tropical disease that affects more than 700,000 people annually. Leishmania parasites cause the disease, and different species trigger a distinct immune response and clinical manifestations. Macrophages are the final host cells for the proliferation of Leishmania parasites, and these cells are the key to a controlled or exacerbated response that culminates in clinical manifestations. M1 and M2 are the two main macrophage phenotypes. M1 is a pro-inflammatory subtype with microbicidal properties, and M2, or alternatively activated, is an anti-inflammatory/regulatory subtype that is related to inflammation resolution and tissue repair. The present review elucidates the roles of M1 and M2 polarization in leishmaniasis and highlights the role of the salivary components of the vector and the action of the parasite in the macrophage plasticity.

Distinct monocyte subset phenotypes in patients with different clinical forms of chronic Chagas disease and seronegative dilated cardiomyopathy

Background

Chronic infection with Trypanosoma cruzi leads to a constant stimulation of the host immune system. Monocytes, which are recruited in response to inflammatory signals, are divided into classical CD14^hiCD16^—, non-classical CD14^loCD16⁺ and intermediate CD14^hiCD16⁺ subsets. In this study, we evaluated the frequencies of monocyte subsets in the different clinical stages of chronic Chagas disease in comparison with the monocyte profile of seronegative heart failure subjects and seronegative healthy controls. The effect of the anti-parasite drug therapy benznidazole on monocyte subsets was also explored.

Methodology/Principal findings

The frequencies of the different monocyte subsets and their phenotypes were measured by flow cytometry. Trypanosoma cruzi-specific antibodies were quantified by conventional serological tests. T. cruzi-infected subjects with mild or no signs of cardiac disease and patients suffering from dilated cardiomyopathy unrelated to T. cruzi infection showed increased levels of non-classical CD14^loCD16⁺ monocytes compared with healthy controls. In contrast, the monocyte profile in T. cruzi-infected subjects with severe cardiomyopathy was skewed towards the classical and intermediate subsets. After benznidazole treatment, non-classical monocytes CD14^loCD16⁺ decreased while classical monocytes CD14^hiCD16^—increased.

Conclusions/Significance

The different clinical stages of chronic Chagas disease display distinct monocyte profiles that are restored after anti-parasite drug therapy. T. cruzi-infected subjects with severe cardiac disease displayed a profile of monocytes subsets suggestive of a more pronounced inflammatory environment compared with subjects suffering from heart failure not related to T. cruzi infection, supporting that parasite persistence might also alter cell components of the innate immune system.

Monocytes are key players during infection, and they leave the bloodstream and migrate into tissues in response to inflammatory signals. Although the recruitment of monocytes is essential for the effective control and clearance of microorganisms, they can also be highly damaging to neighboring tissues. Based on the expression of CD14 and CD16, monocytes are classified into classical, non-classical and intermediate subsets, all of which exert different functions. Because chronic T. cruzi infection induces a constant activation of the host immune system, inflammatory signals are exacerbated, possibly leading to alterations in the frequencies of monocyte subsets. In this study, we evaluated the monocyte profile in Trypanosoma cruzi-infected subjects with different degrees of cardiac dysfunction and explored whether this profile was similar between seropositive and seronegative subjects with heart failure. We found that the different clinical stages of chronic Chagas disease displayed distinct monocyte profiles, which are susceptible to being restored by modulating the parasite load with anti-parasite drug therapy. T. cruzi-infected subjects with severe cardiac disease displayed a profile of monocytes subsets suggestive of a more pronounced inflammatory environment compared with subjects suffering from heart failure not related to T. cruzi infection, supporting that parasite persistence might be a detrimental factor in the evolution of the cardiac disease induced by T. cruzi.

Dehydrocorydaline attenuates bone cancer pain by shifting microglial M1/M2 polarization toward the M2 phenotype

Bone cancer pain remains a major challenge in patients with primary or metastatic bone cancer due to a lack of understanding the mechanisms. Previous studies have revealed the two distinct functional polarization states of microglia (classically activated M1 and alternatively activated M2) in the spinal cord in nerve injury–induced neuropathic pain. However, whether microglia in the spinal cord polarize to M1 and M2 phenotypes and contribute to the development of bone cancer pain remains unclear. In this study, we used a mouse model with bone cancer to characterize the M1/M2 polarization of microglia in the spinal cord during the development of bone cancer pain, and investigated the antinociceptive effects of dehydrocorydaline, an alkaloidal component isolated from Rhizoma corydalis on bone cancer pain. Our results show that microglia in the spinal cord presented increased M1 polarization and decreased M2 polarization, while overproduction of IL-1β and inhibited expression of IL-10 was detected during bone cancer pain development. Intraperitoneal administration of dehydrocorydaline (10 mg/kg) had significant antinociceptive effects on day 14 after osteosarcoma cell implantation, accompanied by suppressed M1 phenotype and upregulated M2 phenotype of microglia in the spinal cord, while alleviated inflammatory response was observed then. These results suggest that the imbalanced polarization of microglia toward the M1 phenotype in the spinal cord may contribute to the development of bone cancer pain, while dehydrocorydaline helps to attenuate bone cancer pain, with microglial polarization shifting toward the M2 phenotype in the spinal cord.

Immunology of Wound Healing

Purpose of Review

Chronic wounds are a tremendous burden on the healthcare system and lead to significant patient morbidity and mortality. Normal cutaneous wound healing occurs through an intricate and delicate interplay between the immune system, keratinocytes, and dermal cells. Each cell type contributes signals that drive the normal phases of wound healing: hemostasis, inflammation, proliferation, and remodeling. This paper reviews how various immunological cell types and signaling molecules influence the way wounds develop, persist, and heal.

Recent Findings

Concurrent with the achievement of hemostasis, neutrophils are the first cells to migrate to the wound bed, brought in by pro-inflammatory signals including IL-8. Their apoptosis and engulfment by macrophages (efferocytosis) provides a key signal to the local immune milieu, including macrophages, to transition to an anti-inflammatory, pro-repair state, where angiogenesis occurs and granulation tissue is laid down. Myofibroblasts, activated through contractile forces and signaling molecules, then drive remodeling, where granulation tissue becomes scar. Unchecked inflammation at this stage can result in abnormal scar formation.

Summary

Although the derangement of immune signals at any stage can result in impaired wound healing, recent research has shown that the key transition point lies between the inflammatory and the proliferative phases. This review summarizes the events that facilitate this transition and discusses how this process can be disrupted, leading to chronic, non-healing wounds.

Estrogen Regulation of T-Cell Function and Its Impact on the Tumor Microenvironment

Epidemiologic studies demonstrate significant gender-specific differences in immune system function. Males are more prone to infection and malignancies, while females are more vulnerable to autoimmune diseases. These differences are thought to be due to the action of gonadal hormones: Estrogen increases the inflammatory response and testosterone dampens it. More specifically, estrogen stimulation induces inflammatory cytokine production including interferon γ, interleukin (IL) 6, and tumor necrosis factor α, while testosterone induces IL-10, IL-4, and transforming growth factor β. More recent studies demonstrate threshold effects of estrogen stimulation on immune cell function: physiologic doses of estrogen (approximately 0.5 nmol/L) stimulate inflammatory cytokine production, but superphysiologic dosages (above 50 nmol/L) can result in decreased inflammatory cytokine production. This review reports findings concerning the impact of estrogen on CD8+ cytotoxic T cells and the overall immune response in the tumor microenvironment. Variables examined include dosage of hormone, the diversity of immune cells involved, and the nature of the immune response in cancer. Collective review of these points may assist in future hypotheses and studies to determine sex-specific differences in immune responses that may be used as targets in disease prevention and treatment.

Effect of nano-structural properties of biomimetic hydroxyapatite on osteoimmunomodulation

Immune cells are sensitive to the microstructural and textural properties of materials. Tuning the structural features of synthetic bone grafts could be a valuable strategy to regulate the specific response of the immune system, which in turn modulates the activity of bone cells. The aim of this study was to analyse the effect of the structural characteristics of biomimetic calcium deficient hydroxyapatite (CDHA) on the innate immune response of macrophages and the subsequent impact on osteogenesis and osteoclastogenesis. Murine RAW 264.7 cells were cultured, under standard and inflammatory conditions, on chemically identical CDHA substrates that varied in microstructure and porosity. The impact on osteogenesis was evaluated by incubating osteoblastic cells (SaOS-2) with RAW-CDHA conditioned extracts. The results showed that macrophages were sensitive to different textural and structural properties of CDHA. Under standard conditions, the impact of inflammatory cytokine production by RAW cells cultured on CDHA played a significant role in the degradation of substrates, suggesting the impact of resorptive behaviour of RAW cells on biomimetic surfaces. Osteoblast differentiation was stimulated by the conditioned media collected from RAW cells cultured on needle-like nanostructured CDHA. The results demonstrated that needle-like nanostructured CDHA was able to generate a favourable osteoimmune environment to regulate osteoblast differentiation and osteogenesis. Under inflammatory conditions, the incubation of RAW cells with less porous CDHA resulted in a decreased gene expression and release of pro-inflammatory cytokines.

Overexpression of Mechano-Growth Factor Modulates Inflammatory Cytokine Expression and Macrophage Resolution in Skeletal Muscle Injury

In muscle regeneration, infiltrating myeloid cells, such as macrophages mediate muscle inflammation by releasing key soluble factors. One such factor, insulin-like growth factor 1 (IGF-1), suppresses inflammatory cytokine expression and mediates macrophage polarization to anti-inflammatory phenotype during muscle injury. Previously the IGF-1Ea isoform was shown to be anti-inflammatory. Another isoform of IGF-1, mechano-growth factor (MGF), is structurally and functionally distinct from IGF-1Ea, but its role in muscle inflammation has not yet been characterized. In this study, we hypothesized that MGF expression in muscle injury modulates muscle inflammation. We first investigated changes of transcription and expression of MGF in response to skeletal muscle injury induced by cardiotoxin (CTX) in vivo. At 1–2 days post-injury, Mgf expression was significantly upregulated and positively correlated with that of inflammatory cytokines. Immunostaining revealed that infiltration of neutrophils and macrophages coincided with Mgf upregulation. Furthermore, infiltrating neutrophils and macrophages expressed Mgf, suggesting their contribution to MGF upregulation in muscle injury. Macrophages seem to be the predominant source of MGF in muscle injury, whereas neutrophil depletion did not affect muscle Mgf expression. Given the association of MGF and macrophages, we then studied whether MGF could affect macrophage infiltration and polarization. To test this, we overexpressed MGF in CTX-injured muscles and evaluated inflammatory marker expression, macrophage populations, and muscle regeneration outcomes. MGF overexpression delayed the resolution of macrophages, particularly the pro-inflammatory phenotype. This coincided with upregulation of inflammatory markers. Annexin V-based flow cytometry revealed that MGF overexpression likely delays macrophage resolution by limiting macrophage apoptosis. Although MGF overexpression did not obviously affect muscle regeneration outcomes, the findings are novel and provide insights on the physiological roles of MGF in muscle regeneration.

Microglia Responses to Pro-inflammatory Stimuli (LPS, IFNγ+TNFα) and Reprogramming by Resolving Cytokines (IL-4, IL-10)

Microglia respond to CNS injuries and diseases with complex reactions, often called "activation." A pro-inflammatory phenotype (also called classical or M1 activation) lies at one extreme of the reactivity spectrum. There were several motivations for this study. First, bacterial endotoxin (lipopolysaccharide, LPS) is the most commonly used pro-inflammatory stimulus for microglia, both in vitro and in vivo; however, pro-inflammatory cytokines (e.g., IFNγ, TNFα) rather than LPS will be encountered with sterile CNS damage and disease. We lack direct comparisons of responses between LPS and such cytokines. Second, while transcriptional profiling is providing substantial data on microglial responses to LPS, these studies mainly use mouse cells and models, and there is increasing evidence that responses of rat microglia can differ. Third, the cytokine milieu is dynamic after acute CNS damage, and an important question in microglial biology is: How malleable are their responses? There are very few studies of effects of resolving cytokines, particularly for rat microglia, and much of the work has focused on pro-inflammatory outcomes. Here, we first exposed primary rat microglia to LPS or to IFNγ+TNFα (I+T) and compared hallmark functional (nitric oxide production, migration) and molecular responses (almost 100 genes), including surface receptors that can be considered part of the sensome. Protein changes for exemplary molecules were also quantified: ARG1, CD206/MRC1, COX-2, iNOS, and PYK2. Despite some similarities, there were notable differences in responses to LPS and I+T. For instance, LPS often evoked higher pro-inflammatory gene expression and also increased several anti-inflammatory genes. Second, we compared the ability of two anti-inflammatory, resolving cytokines (IL-4, IL-10), to counteract responses to LPS and I+T. IL-4 was more effective after I+T than after LPS, and IL-10 was surprisingly ineffective after either stimulus. These results should prove useful in modeling microglial reactivity in vitro; and comparing transcriptional responses to sterile CNS inflammation in vivo.

The Anaphylatoxin C3a Receptor Expression on Human M2 Macrophages Is Down-Regulated by Stimulating the Histamine H4 Receptor and the IL-4 Receptor

The anaphylatoxin C3a triggers inflammation by binding to its specific G-protein-coupled C3a receptor (C3aR). Since the number of C3aR, which is expressed on the cell surface, affects the response to C3a, we investigated the expression levels of C3aR on human M2 macrophages in allergic situations where high levels of the Th2 cytokine IL-4 and histamine are present in a local microenvironment. The histamine H1 receptor (H1R), H2R and the H4R mRNA expressions were induced or up-regulated during the differentiation process of M2 macrophages. The presence of histamine or agonists targeting the H1R, H2R and, in particular, the H4R during in vitro differentiation from monocytes to macrophages modified the M2 phenotype by regulating the macrophage differentiation marker CD68 and CD163 expressions. In -addition, the C3aR expression was also down-regulated by -ST-1006 during this process. Histamine and ST-1006 down-regulated the expression of C3aR with different time kinetics on fully differentiated M2 macrophages. By analysing C3a-induced IL-6 mRNA expression, we observed a diminished response to C3a in ST-1006-treated M2 macrophages when compared to un-treated cells. Expression of C3 was not affected by histamine, whereas IL-4 strongly down-regulated C3aR and C3 expressions. Our data suggests that down-regulation of C3aR expression by mediators present in allergic situations such as IL-4 or histamine has an anti-inflammatory impact by reducing the sensitivity to C3a-induced down-stream signaling, thereby contributing to the regulation of local inflammatory responses in the skin.

Antigen conjugated nanoparticles reprogrammed the tumor-conditioned macrophages toward pro-immunogenic type through regulation of NADPH oxidase and p38MAPK

Tumor associated macrophages (TAMs) are pertinent to cancer cell growth in the tumor microenvironment. Indeed, TAMs differentiate from monocytes (MΦ) due to specific growth factors present in the tumor microenvironment. TAMs show mostly an M2-like phenotype is due to the absence of pro-inflammatory signals and supply fuel to tumor growth. Several attempts have been taken to switch TAMs into a pro-immunogenic type. To address context, we used a tumor microenvironment by in vitro coculturing human blood MΦ with cancer cell conditioned media (TC-MΦ). We showed that the antigen cobalt oxide nanoparticles (Ag-NPs) can reprogram TC-MΦ to pro-immunogenic type to build up an antitumor immune response. Our results demonstrate that NPs-Ag induced a marked activation of NADPH oxidase in TC-MΦ, likely through stimulation of ROS linked to activation of p38 MAPK. These activated p38 MAPK up-regulated the IFN-γ, TNF-α and initial IL-12 production, in turn, the activation of IFN-γ prolonged IL-12 production.

Modulating Macrophage Polarization through CCR2 Inhibition and Multivalent Engagement

Excessive or prolonged recruitment of inflammatory monocytes to damaged tissue can significantly worsen patient outcomes. Monocytes migrate to sites of tissue inflammation in response to high local concentrations of CCL2, a chemokine that binds to and signals through the CCR2 receptor. While the role of CCR2 in cellular migration is well studied, it is unclear how CCR2 inhibition affects macrophage polarization and if multivalency can increase downstream signaling effects. Using affinity selection with a phage library, we identified a novel single-chain variable fragment (scFv) (58C) that binds specifically and with high affinity to the N-terminal domain of CCR2 ( KD = 59.8 nM). The newly identified 58C-scFv bound to native CCR2 expressed on macrophages and MDA-MB-231 cells, inhibited migration, and induced a pro-inflammatory M1-phenotype in macrophages. The M1/M2 macrophage phenotype ratio for monomeric 58C-scFv was significantly increased over the negative control by 1.0 × 104-fold (iNOS/Arg-1), 5.1 × 104-fold (iNOS/Mgl2), 3.4 × 105-fold (IL-6/Arg-1), and 1.7 × 106-fold (IL-6/Mgl2). The multivalent display of 58C-scFv on liposomes further reduced migration of both cell types by 25-40% and enhanced M1 polarization by 200% over monomeric 58C-scFv. These studies demonstrate that CCR2 inhibition polarizes macrophages toward an inflammatory M1 phenotype, and that multivalent engagement of CCR2 increases the effects of 58C-scFv on polarization and migration. These data provide important insights into the role of multivalency in modulating binding, downstream signaling, and cellular fate.

Macrophages Switch Their Phenotype by Regulating Maf Expression during Different Phases of Inflammation

Macrophages manifest distinct phenotype according to the organs in which they reside. In addition, they flexibly switch their character in adaptation to the changing environment. However, the molecular basis that explains the conversion of the macrophage phenotype has so far been unexplored. We find that CD169⁺ macrophages change their phenotype by regulating the level of a transcription factor Maf both in vitro and in vivo in C57BL/6J mice. When CD169⁺ macrophages were exposed to bacterial components, they expressed an array of acute inflammatory response genes in Maf-dependent manner and simultaneously start to downregulate Maf. This Maf suppression is dependent on accelerated degradation through proteasome pathway and microRNA-mediated silencing. The downregulation of Maf unlocks the NF-E2-related factor 2-dominant, cytoprotective/antioxidative program in the same macrophages. The present study provides new insights into the previously unanswered question of how macrophages initiate proinflammatory responses while retaining their capacity to repair injured tissues during inflammation.

CCR2-dependent monocytes/macrophages exacerbate acute brain injury but promote functional recovery after ischemic stroke in mice

Rationale: Peripheral blood monocytes are recruited into the ischemic brain and transform into macrophages after stroke. Nevertheless, the exact role of CCR2-dependent monocytes/macrophages in brain injury after stroke remains elusive.

Methods: We used CCR2 knockout (KO) mice and the CCR2 pharmacological inhibitor, propagermanium (PG), to address the role of CCR2-dependent monocytes/macrophages in the acute stage and neurological functional recovery after middle cerebral artery (MCA) occlusion and reperfusion.

Results: CCR2 KO resulted in smaller infarct size and lower mortality than in wild type (WT) mice, when measured 3 days after stroke. However, from 5 to 28 days after stroke, the KO mice had higher mortality and showed no obvious neurological functional recovery. In addition, WT mice treated with PG had similar stroke outcomes compared with CCR2 KO, as measured by T2 weighted MRI. Flow cytometry and real-time PCR analyses suggest that monocyte-derived macrophages (MoDMs) in the stroke brains mainly polarized to pro-inflammatory macrophages at the early stage, but gradually switched to anti-inflammatory macrophages at 7 days after stroke. In addition, adoptive transfer of anti-inflammatory macrophages into CCR2 KO mice at 4 and 6 days after stroke alleviated mortality and promoted neurological recovery.

Conclusion: CCR2-dependent monocytes/macrophages are a double-edged sword; they worsen acute brain injury, but are essential for neurological recovery by promoting anti-inflammatory macrophage polarization.

Implications of macrophage polarization in autoimmunity

Macrophages are extremely heterogeneous and plastic cells with an important role not only in physiological conditions, but also during inflammation (both for initiation and resolution). In the early 1990s, two different phenotypes of macrophages were described: one of them called classically activated (or inflammatory) macrophages (M1) and the other alternatively activated (or wound-healing) macrophages (M2). Currently, it is known that functional polarization of macrophages into only two groups is an over-simplified description of macrophage heterogeneity and plasticity; indeed, it is necessary to consider a continuum of functional states. Overall, the current available data indicate that macrophage polarization is a multifactorial process in which a huge number of factors can be involved producing different activation scenarios. Once a macrophage adopts a phenotype, it still retains the ability to continue changing in response to new environmental influences. The reversibility of polarization has a critical therapeutic value, especially in diseases in which an M1/M2 imbalance plays a pathogenic role. In this review, we assess the high plasticity of macrophages and their potential to be exploited to reduce chronic/detrimental inflammation. On the whole, the evidence detailed in this review underscores macrophage polarization as a target of interest for immunotherapy.

Expression of CD206 and CD163 on intermediate CD14++CD16+ monocytes are increased in hemorrhagic fever with renal syndrome and are correlated with disease severity

BACKGROUND

Hantaan virus infection causes lethal hemorrhagic fever with renal syndrome (HFRS) in humans. Little is known about how monocytes contribute to HFRS pathogenesis. In this study, we aimed to investigate changes in various monocyte subsets in HFRS patients.

METHODS

A total of 41 HFRS patients and 17 age-, sex-, and ethnicity-matched healthy control subjects were included in this study. Numbers/percentages of various monocyte subsets were quantitatively determined using flow cytometry. Serum levels of interleukin (IL)-10, IL-12, and tumor necrosis factor alpha (TNF-α) were detected using a cytometric bead array (CBA).

RESULTS

CD14⁺⁺CD16⁺ intermediate monocytes were significantly higher in HFRS patients compared to healthy controls (P < 0.01), especially during the acute phase. The expression of both CD163 and CD206 on CD14⁺⁺CD16⁺ intermediate monocytes were increased during the acute phase of HFRS (P < 0.01 and P < 0.05, respectively) when comparing the convalescent phase and healthy controls. Furthermore, the numbers of CD14⁺⁺CD16⁺ monocytes during the acute phase, and the percentages of CD14⁺⁺CD16⁺CD163⁺ monocytes in patients with severe/critical HFRS were much higher compared to patients with mild/moderate HFRS. This also positively correlated with increased levels of white blood cells (WBC), blood urea nitrogen (BUN), and creatinine (Cr). However, the percentages of CD14⁺⁺CD16⁺CD206⁺monocytes were higher in mild/moderate HFRS than in severe/critical HFRS, and they negatively correlated with platelets (PLT) and Cr.

CONCLUSIONS

Higher frequency of the CD14⁺⁺CD16⁺ intermediate monocytes and increased expression of CD163⁺ and CD206⁺ markers on CD14⁺⁺CD16⁺ monocytes were detected in patients with HFRS. The changes in the frequency of CD14⁺⁺CD16⁺ monocytes and expression of CD163 and CD206 markers on CD14⁺⁺CD16⁺ monocytes positively correlated with the severity of HFRS.

Tuberculosis in the elderly: Why inflammation matters

Growing old is associated with an increase in the basal inflammatory state of an individual and susceptibility to many diseases, including infectious diseases. Evidence is growing to support the concept that inflammation and disease susceptibility in the elderly is linked. Our studies focus on the infectious disease tuberculosis (TB), which is caused by Mycobacterium tuberculosis (M.tb), a pathogen that infects approximately one fourth of the world's population. Aging is a major risk factor for developing TB, and inflammation has been strongly implicated. In this review we will discuss the relationship between inflammation in the lung and susceptibility to develop and succumb to TB in old age. Further understanding of the relationship between inflammation, age, and M.tb will lead to informed decisions about TB prevention and treatment strategies that are uniquely designed for the elderly.

Redirecting tumor-associated macrophages to become tumoricidal effectors as a novel strategy for cancer therapy

Cancer research in recent decades has highlighted the potential influence of the tumor microenvironment on the progression and metastasis of most known cancer types. Within the established microenvironment, tumor-associated macrophages (TAMs) are one of the most abundant and crucial non-neoplastic cell types. The polarization of macrophages into tumor-suppressive M1 or tumor-promoting M2 types is a fundamental event in the establishment of the tumor microenvironment. Although ample evidence indicates that TAMs are primarily M2 polarized, the mechanisms responsible for the regulation and maintenance of M1 and M2 polarization imbalance remain unclear. The manipulation of this critical axis through three main approaches may provide new strategies for cancer therapy - (I) specific interference with M2-like TAM survival or inhibiting their signaling cascades, (II) repression of macrophage recruitment to tumors, and (III) repolarization of tumor-promoting M2-like TAMs to a tumoricidal M1-like phenotype. This review summarizes current strategies for cancer intervention via manipulation of macrophage polarization, with particular focus on composition of the tumor microenvironment and its influence on cancer progression and metastasis. It is clear that additional fundamental and preclinical research is required to confirm the efficacy and practicality of this novel and promising strategy for treating cancer.

Tailoring the immuno-responsiveness of anodized nano-engineered titanium implants

Owing to its biocompatibility and corrosion resistance, titanium is one of the most commonly used implantable biomaterials. Numerous in vitro and in vivo investigations have established that titanium surfaces with a nanoscale topography outperform conventional smooth or micro-rough surfaces in terms of achieving desirable bonding with bone (i.e. enhanced bioactivity). Among these nanoscale topographical modifications, ordered nanostructures fabricated via electrochemical anodization, especially titania nanotubes (TNTs), are particularly attractive. This is due to their ability to augment bioactivity, deliver drugs and the potential for easy/cost-effective translation into the current implant market. However, the potential of TNT-modified implants to modulate the host immune-inflammatory response, which is critical for achieving timely osseointegration, remains relatively unexplored. Such immunomodulatory effects may be achieved by modifying the physical and chemical properties of the TNTs. Furthermore, therapeutic/bioactive enhancements performed on these nano-engineered implants (such as antibacterial or osteogenic functions) are likely to illicit an immune response which needs to be appropriately controlled. The lack of sufficient in-depth studies with respect to immune cell responses to TNTs has created research gaps that must be addressed in order to facilitate the design of the next generation of immuno-modulatory titanium implants. This review article focuses on the chemical, topographical and mechanical features of TNT-modified implants that can be manipulated in order to achieve immuno-modulation, as well as providing an insight into how modulating the immune response can augment implant performance.

The histamine H4 receptor modulates the differentiation process of human monocyte-derived M1 macrophages and the release of CCL4/MIP-1β from fully differentiated M1 macrophages

OBJECTIVE

Histamine is an important mediator of biological functions and present in high amounts in inflammatory skin lesions which are characterised by a marked infiltration of myeloid derived cell populations. The aim of the study was to investigate the expression and function of histamine receptors, with a focus on the histamine H4 receptor (H4R) in detail during the differentiation process from monocytes to macrophages and on fully differentiated M1 macrophages.

METHODS

Quantitative PCR, ELISA technique, and flow cytometry were applied to analyze expression levels of histamine receptors, of CXCL10, CCL4, CCL3, or IL-23 and of the macrophage differentiation marker CD68, respectively.

RESULTS

We demonstrated that monocytes and fully differentiated M1 macrophages express H1R-, H2R-, and H4R mRNA which were differentially regulated during the differentiation process and in IFN-Ƴ and LPS classically activated M1 macrophages. The H3R mRNA was not expressed. During in vitro differentiation from monocytes to macrophages, the H4R agonist ST-1006 modified the M1 phenotype by up-regulating the macrophage differentiation marker CD68, by down-regulating the production of CXCL10, and by changing the morphology. In fully differentiated M1 macrophages, histamine or ST-1006 decreased the IFN-Ƴ- and LPS-induced CCL4 mRNA expression and protein production, whereas CCL3 or IL-23 production was not regulated via H4R.

CONCLUSIONS

We describe novel immunomodulatory functions of the H4R during the differentiation process of human monocyte-derived macrophages and in fully differentiated M1 macrophages. The down-regulation of Th1-related chemokines during the differentiation process or in classically activated macrophages via H4R may contribute to decreased migration of immune cells to the site of inflammation. This may have implications for the treatment of allergic diseases with H4R ligands regulating the dysbalance of Th2/Th1 polarizations in these disorders.

Macrophage polarization, inflammatory signaling, and NF-κB activation in response to chemically modified titanium surfaces

Functionalization of titanium devices with various bioactive molecules enhances many of their properties as implants, including biocompatibility, which is typically assessed by macrophage activation and inflammation. However, functionalization requires prior introduction of reactive groups, to which bioactive agents can then be grafted. Thus, we investigated the inflammatory properties of titanium pretreated with NaOH, titanium pretreated with NaOH and then with 3-aminopropyl triethoxysilane, and titanium pretreated with dopamine. Inflammation, macrophage polarization, and activation of NF-κB signaling were assessed by real-time PCR and western blotting. The data demonstrate that silanized titanium is the least inflammatory, and promotes macrophage M2 polarization with modest engagement of the NF-κB signaling pathway. Importantly, silanization introduces a reactive amino group, providing more opportunities for further functionalization.

Matrix metalloproteinases in emphysema

Several studies have implicated a causative role for specific matrix metalloproteinases (MMPs) in the development and progression of cigarette smoke-induced chronic obstructive pulmonary disease (COPD) and its severe sequela, emphysema. However, the precise function of any given MMP in emphysema remains an unanswered question. Emphysema results from the degradation of alveolar elastin - among other possible mechanisms - a process that is often thought to be caused by elastolytic proteinases made by macrophages. In this article, we discuss the data suggesting, supporting, or refuting causative roles of macrophage-derived MMPs, with a focus on MMPs-7, -9, -10, -12, and 28, in both the human disease and mouse models of emphysema. Findings from experimental models suggest that some MMPs, such as MMP-12, may directly breakdown elastin, whereas others, particularly MMP-10 and MMP-28, promote the development of emphysema by influencing the proteolytic and inflammatory activities of macrophages.

Distinct Properties of Human M-CSF and GM-CSF Monocyte-Derived Macrophages to Simulate Pathological Lung Conditions In Vitro: Application to Systemic and Inflammatory Disorders with Pulmonary Involvement

Macrophages play a central role in the pathogenesis of inflammatory and fibrotic lung diseases. However, alveolar macrophages (AM) are poorly available in humans to perform in vitro studies due to a limited access to broncho-alveolar lavage (BAL). In this study, to identify the best alternative in vitro model for human AM, we compared the phenotype of AM obtained from BAL of patients suffering from three lung diseases (lung cancers, sarcoidosis and Systemic Sclerosis (SSc)-associated interstitial lung disease) to human blood monocyte-derived macrophages (MDMs) differentiated with M-CSF or GM-CSF. The expression of eight membrane markers was evaluated by flow cytometry. Globally, AM phenotype was closer to GM-CSF MDMs. However, the expression levels of CD163, CD169, CD204, CD64 and CD36 were significantly higher in SSc-ILD than in lung cancers. Considering the expression of CD204 and CD36, the phenotype of SSc-AM was closer to MDMs, from healthy donors or SSc patients, differentiated by M-CSF rather than GM-CSF. The comparative secretion of IL-6 by SSc-MDMs and SSc-AM is concordant with these phenotypic considerations. Altogether, these results support the M-CSF MDM model as a relevant in vitro alternative to simulate AM in fibrotic disorders such as SSc.

Macrophages, Wound Healing, and Fibrosis: Recent Insights

PURPOSE OF REVIEW

Macrophages are central players in the immune response following tissue injury. These cells perform many functions, and the changing tissue microenvironment during injury shapes macrophage phenotype down a variety of polarized pathways. This review summarizes the current knowledge on the roles of macrophages during different stages of tissue injury, repair, and-if repair is not achieved-fibrosis.

RECENT FINDINGS

Macrophages present early in inflammation are functionally distinct from those at later stages. The predominant macrophage phenotype must transition from pro-inflammatory to pro-reparative to facilitate wound healing and scar resolution. If macrophages fail to acquire a tissue-healing phenotype, dysregulated signals can be drivers of disease processes, such as sustained, exuberant inflammation-as occurs in arthropathies-and fibrosis. Comprehensive understanding of the roles of specific macrophage populations at different stages of the repair process will support the development of immune-targeted therapies for diseases such as fibrosis.

CD5L Promotes M2 Macrophage Polarization through Autophagy-Mediated Upregulation of ID3

CD5L (CD5 molecule-like) is a secreted glycoprotein that controls key mechanisms in inflammatory responses, with involvement in processes such as infection, atherosclerosis, and cancer. In macrophages, CD5L promotes an anti-inflammatory cytokine profile in response to TLR activation. In the present study, we questioned whether CD5L is able to influence human macrophage plasticity, and drive its polarization toward any specific phenotype. We compared CD5L-induced phenotypic and functional changes to those caused by IFN/LPS, IL4, and IL10 in human monocytes. Phenotypic markers were quantified by RT-qPCR and flow cytometry, and a mathematical algorithm was built for their analysis. Moreover, we compared ROS production, phagocytic capacity, and inflammatory responses to LPS. CD5L drove cells toward a polarization similar to that induced by IL10. Furthermore, IL10- and CD5L-treated macrophages showed increased LC3-II content and colocalization with acidic compartments, thereby pointing to the enhancement of autophagy-dependent processes. Accordingly, siRNA targeting ATG7 in THP1 cells blocked CD5L-induced CD163 and Mer tyrosine kinase mRNA and efferocytosis. In these cells, gene expression profiling and validation indicated the upregulation of the transcription factor ID3 by CD5L through ATG7. In agreement, ID3 silencing reversed polarization by CD5L. Our data point to a significant contribution of CD5L-mediated autophagy to the induction of ID3 and provide the first evidence that CD5L drives macrophage polarization.

Rhinovirus infection induces distinct transcriptome profiles in polarized human macrophages

Infections with rhinovirus (RV) cause asthma exacerbations. Recent studies suggest that macrophages play a role in asthmatic airway inflammation and the innate immune response to RV infection. Macrophages exhibit phenotypes based on surface markers and gene expression. We hypothesized that macrophage polarization state alters gene expression in response to RV infection. Cells were derived from human peripheral blood derived monocytes. M1 and M2 polarization was carried out by using IFN-γ and IL-4, respectively, and RNA was extracted for Affymetrix Human Gene ST2.1 exon arrays. Selected genes were validated by quantitative (q)PCR. Treatment of nonactivated (M0) macrophages with IFN-γ and IL-4 induced the expression of 252 and 153 distinct genes, respectively, including previously-identified M1 and M2 markers. RV infection of M0 macrophages induced upregulation of 232 genes; pathway analysis showed significant overrepresentation of genes involved in IFN-α/β signaling and cytokine signaling in the immune system. RV infection induced differential expression of 195 distinct genes in M1-like macrophages but only seven distinct genes in M2-like-polarized cells. In a secondary analysis, comparison between M0-, RV-infected, and M1-like-polarized, RV-infected macrophages revealed differential expression of 227 genes including those associated with asthma and its exacerbation. qPCR demonstrated increased expression of CCL8, CXCL10, TNFSF10, TNFSF18, IL6, NOD2, and GSDMD and reduced expression of VNN1, AGO1, and AGO2. Together, these data show that, in contrast to M2-like-polarized macrophages, gene expression of M1-like macrophages is highly regulated by RV.

Transcription Factor Target Gene Network governs the Logical Abstraction Analysis of the Synthetic Circuit in Leishmaniasis

With the advent of synthetic biology in medicine many synthetic or engineered proteins have made their way to therapeutics and diagnostics. In this paper, the downstream gene network of CD14-TNF-EGFR pathway in leishmaniasis, a tropical disease, is reconstructed. Network analysis showed that NFkB links the signaling and gene network, used as a point of intervention through a synthetic circuit embedded within the negative autoregulatory feedback loop. A chimeric protein kinase C (PKC) is incorporated in the synthetic circuit, under the transcriptional regulation of Lac repressor and IPTG, as an inducer. The chimeric PKC_ζα via IκKb phosphorylation activates NFκB, and modulates the gene expression from an anti-inflammatory to a pro-inflammatory phenotype in in vitro L. major infected macrophage model. This is the first ever report of a synthetic device construction in leishmania.

Mesenchymal stem cells and macrophages interact through IL-6 to promote inflammatory breast cancer in pre-clinical models

Inflammatory breast cancer (IBC) is a unique and deadly disease with unknown drivers. We hypothesized the inflammatory environment contributes to the IBC phenotype. We used an in vitro co-culture system to investigate interactions between normal and polarized macrophages (RAW 264.7 cell line), bone-marrow derived mesenchymal stem cells (MSCs), and IBC cells (SUM 149 and MDA-IBC3). We used an in vivo model that reproduces the IBC phenotype by co-injecting IBC cells with MSCs into the mammary fat pad. Mice were then treated with a macrophage recruitment inhibitor, anti-CSF1. MSC and macrophages grown in co-culture produced higher levels of pro-tumor properties such as enhanced migration and elevated IL-6 secretion. IBC cells co-cultured with educated MSCs also displayed enhanced invasion and mammosphere formation and blocked by anti-IL-6 and statin treatment. The treatment of mice co-injected with IBC cells and MSCs with anti-CSF1 inhibited tumor associated macrophages and inhibited pSTAT3 expression in tumor cells. Anti-CSF1 treated mice also exhibited reduced tumor growth, skin invasion, and local recurrence. Herein we demonstrate reciprocal tumor interactions through IL-6 with cells found in the IBC microenvironment. Our results suggest IL-6 is a mediator of these tumor promoting influences and is important for the IBC induced migration of MSCs.

Significance and In Vivo Detection of Iron-Laden Microglia in White Matter Multiple Sclerosis Lesions

Microglia are resident immune cells that fulfill protective and homeostatic functions in the central nervous system (CNS) but may also promote neurotoxicity in the aged brain and in chronic disease. In multiple sclerosis (MS), an autoimmune demyelinating disease of the CNS, microglia and macrophages contribute to the development of white matter lesions through myelin phagocytosis, and possibly to disease progression through diffuse activation throughout myelinated white matter. In this review, we discuss an additional compartment of myeloid cell activation in MS, i.e., the rim and normal adjacent white matter of chronic active lesions. In chronic active lesions, microglia and macrophages may contain high amounts of iron, express markers of proinflammatory polarization, are activated for an extended period of time (years), and drive chronic tissue damage. Iron-positive myeloid cells can be visualized and quantified with quantitative susceptibility mapping (QSM), a magnetic resonance imaging technique. Thus, QSM has potential as an in vivo biomarker for chronic inflammatory activity in established white matter MS lesions. Reducing chronic inflammation associated with iron accumulation using existing or novel MS therapies may impact disease severity and progression.

Galectin-9 modulates immunity by promoting Th2/M2 differentiation and impacts survival in patients with metastatic melanoma

Galectin-9, a β-galactoside-binding protein, is defined as a negative regulator of T helper 1 (Th1) immune responses, favoring Th2 bias. Systemic immunity in patients with metastatic melanoma is predominantly Th2 biased. We hypothesized that galectin-9 can modulate systemic immunity toward Th2 polarization in patients with advanced melanoma. The presence or concentration of galectin-9 was assessed in tumors and plasma, in patients with metastatic melanoma. The immunomodulatory function of galectin-9 was determined by exposing human peripheral blood mononuclear cells to galectin-9 in vitro. Galectin-9 was expressed in 57% of tumors and was significantly (3.6-fold) increased in the plasma of patients with advanced melanoma compared with healthy controls (P<0.001). High plasma galectin-9 concentration was associated with systemic Th2 polarization and reduced 2-year survival compared with low/no galectin-9 expression. In-vitro, galectin-9 reduced proliferation of healthy peripheral blood mononuclear cells, and promoted Th1 cell apoptosis, Th2-biased cell phenotypes, and cytokine secretion. Galectin-9 also stimulated monocyte differentiation toward an M2 macrophage phenotype, as assessed by chemokine/cytokine secretion and CD206 expression, observed both in vitro as well as in patients with metastatic melanoma. Elevated galectin-9 in patient plasma correlated with Th2 systemic bias and less favorable clinical outcomes for patients with metastatic melanoma. This Th2 bias appears to be not only a feature of the known mechanisms of Th1 apoptosis by T-cell immunoglobulin and mucin-domain containing-3 binding, but also mediated by myeloid cell differentiation toward an M2 phenotype, that favors tumor progression. These data support galectin-9 as a novel therapeutic target for patients with metastatic melanoma.

SPON2 Promotes M1-like Macrophage Recruitment and Inhibits Hepatocellular Carcinoma Metastasis by Distinct Integrin-Rho GTPase-Hippo Pathways

Tumor-associated macrophages (TAM) represent key regulators of the complex interplay between cancer and the immune microenvironment. Matricellular protein SPON2 is essential for recruiting lymphocytes and initiating immune responses. Recent studies have shown that SPON2 has complicated roles in cell migration and tumor progression. Here we report that, in the tumor microenvironment of hepatocellular carcinoma (HCC), SPON2 not only promotes infiltration of M1-like macrophages but also inhibits tumor metastasis. SPON2-α4β1 integrin signaling activated RhoA and Rac1, increased F-actin reorganization, and promoted M1-like macrophage recruitment. F-Actin accumulation also activated the Hippo pathway by suppressing LATS1 phosphorylation, promoting YAP nuclear translocation, and initiating downstream gene expression. However, SPON2-α5β1 integrin signaling inactivated RhoA and prevented F-actin assembly, thereby inhibiting HCC cell migration; the Hippo pathway was not noticeably involved in SPON2-mediated HCC cell migration. In HCC patients, SPON2 levels correlated positively with prognosis. Overall, our findings provide evidence that SPON2 is a critical factor in mediating the immune response against tumor cell growth and migration in HCC.Significance: Matricellular protein SPON2 acts as an HCC suppressor and utilizes distinct signaling events to perform dual functions in HCC microenvironment.Graphical Abstract: http://cancerres.aacrjournals.org/content/canres/78/9/2305/F1.large.jpg Cancer Res; 78(9); 2305-17. ©2018 AACR.

Expression of Adipocyte/Macrophage Fatty Acid-Binding Protein in Tumor-Associated Macrophages Promotes Breast Cancer Progression

Tumor-associated macrophages (TAM) play a critical role in cancer development and progression. However, the heterogeneity of TAM presents a major challenge to identify clinically relevant markers for protumor TAM. Here, we report that expression of adipocyte/macrophage fatty acid-binding protein (A-FABP) in TAM promotes breast cancer progression. Although upregulation of A-FABP was inversely associated with breast cancer survival, deficiency of A-FABP significantly reduced mammary tumor growth and metastasis. Furthermore, the protumor effect of A-FABP was mediated by TAM, in particular, in a subset of TAM with a CD11b⁺F4/80⁺MHCII^-Ly6C^- phenotype. A-FABP expression in TAM facilitated protumor IL6/STAT3 signaling through regulation of the NFκB/miR-29b pathway. Collectively, our results suggest A-FABP as a new functional marker for protumor TAM.Significance: These findings identify A-FABP as a functional marker for protumor macrophages, thus offering a new target for tumor immunotherapy. Cancer Res; 78(9); 2343-55. ©2018 AACR.

Novel mechanisms of Collagenase Santyl Ointment (CSO) in wound macrophage polarization and resolution of wound inflammation

Collagenases are useful in enzymatic wound debridement. Clostridial collagenase, marketed as Collagenase Santyl Ointment (CSO), is FDA approved for such use. Building on the scientific premise that collagenases as well as collagen degradation products may regulate immune cell function, we sought to investigate the potential role of CSO in wound inflammation. We tested the hypothesis that in addition to enacting debridement, CSO contributes to the resolution of persistent wound inflammation. Wound macrophages were isolated from PVA sponges loaded with CSO or petrolatum and implanted in mice. Significant increase in pro-reparative and decrease in pro-inflammatory polarization was noted in macrophages of acute as well as diabetic wounds. Wound macrophages from CSO-treated group displayed increased production of anti-inflammatory cytokines IL-10 and TGF-β, and decreased levels of pro-inflammatory cytokines TNF-α and IL-1β. The active ingredient of CSO, CS-API, induced the expression of mϕ^heal /M(IL-4) polarization markers ex vivo. CS-API treatment attenuated transactivation of NF-κB and significantly induced STAT6 phosphorylation. A significant role of a novel PGE2-EP4 pathway in CS-API induced STAT6 activation and the mϕ^heal /M(IL-4) polarization was identified. Taken together, findings of this work reposition CSO as a potential agent that may be effective in resolving wound inflammation, including diabetic wounds.