Macrophage polarization and function with emphasis on the evolving roles of coordinated regulation of cellular signaling pathways

Tatarinan T, an α-asarone-derived lignin, attenuates osteoclastogenesis induced by RANKL via the inhibition of NFATc1/c-Fos expression

We have previously reported that the lignin-like compounds, Tatarinan O (TO) and Tatarinan N (TN), extracted from the roots of Acorus tatarinowii Schott, inhibit receptor activator of nuclear factor-κB ligand (RANKL)-induced osteoclastogenesis. In the present study, the potential function of the α-asarone-derived lignins, Tatarinan T (TT) and Tatarinan A (TA), to regulate RANKL-induced osteoclastogenesis was investigated, and it was found that only early treatment with TT may inhibit RANKL-triggered formation of osteoclasts and resorption. The results revealed repressed expression levels of several osteoclast marker genes, including ATPase H⁺ -transporting V0 subunit d2 (Atp6v0d2), αvβ3 integrin, and osteoclast-associated receptor (OSCAR), following TT treatment during osteoclastogenesis. Moreover, TT reduced the expression levels of the core transcription elements, nuclear factor of activated T-cells cytoplasmic 1 (NFATc1) and c-Fos. However, western blotting analysis showed that TT treatment did not alter nuclear factor-κΒ (NF-κB) activation or mitogen-activated protein kinase (MAPK) or Syk/Btk/phospholipase Cγ2 (PLCγ2) phosphorylation. Taken together, these results suggest the potential of TT in the treatment of diseases of increased bone resorption.

MSC-secreted TGF-β regulates lipopolysaccharide-stimulated macrophage M2-like polarization via the Akt/FoxO1 pathway

BACKGROUND

An uncontrolled inflammatory response is a critical pathophysiological feature of sepsis. Mesenchymal stem cells (MSCs) induce macrophage phenotype polarization and reduce inflammation in sepsis. MSC-secreted transforming growth factor beta (TGF-β) participated in the immune modulatory function of MSCs. However, the underlying mechanism of MSC-secreted TGF-β was not fully elucidated in regulation macrophage M2-like polarization.

METHODS

The paracrine effects of MSCs on macrophage polarization were studied using a co-culture protocol with LPS-stimulated RAW264.7 cells/mouse peritoneal macrophages and MSCs. The effect of TGF-β in the co-culture system was blocked by the TGF-β receptor inhibitor. To determine the role of MSC-secreted TGF-β, we used recombinant TGF-β to culture with LPS-stimulated RAW264.7 cells. In addition, we employed antibody microarray analysis to determine the mechanisms of MSC secreted TGF-β on LPS-stimulated RAW264.7 cell/mouse peritoneal macrophage M2-like polarization. Furthermore, we used an Akt inhibitor and a FoxO1 inhibitor to inhibit the Akt/FoxO1 pathway. The nuclear translocation of FoxO1 was detected by Western blot.

RESULTS

MSCs induced LPS-stimulated RAW264.7 cell/mouse peritoneal macrophage polarization towards the M2-like phenotype and significantly reduced pro-inflammatory cytokine levels via paracrine, which was inhibited by TGF-β receptor inhibitor. Furthermore, we found that MSC-secreted TGF-β enhanced the macrophage phagocytic ability. The antibody microarray analysis and Western blot verified that TGF-β treatment activated the Akt/FoxO1 pathway in LPS-stimulated macrophages, TGF-β-induced FoxO1 nuclear translocation and obviously expressed in the cytoplasm, the effects of TGF-β regulatory effects on LPS-stimulated macrophage were inhibited by pre-treatment with Akt inhibitor and FoxO1 inhibitor.

CONCLUSIONS

TGF-β secreted by MSCs could skew LPS-stimulated macrophage polarization towards the M2-like phenotype, reduce inflammatory reactions, and improve the phagocytic ability via the Akt/FoxO1 pathway, providing potential therapeutic strategies for sepsis.

Amblyomma americanum ticks utilizes countervailing pro and anti-inflammatory proteins to evade host defense

Feeding and transmission of tick-borne disease (TBD) agents by ticks are facilitated by tick saliva proteins (TSP). Thus, defining functional roles of TSPs in tick evasion is expected to reveal potential targets in tick-antigen based vaccines to prevent TBD infections. This study describes two types of Amblyomma americanum TSPs: those that are similar to LPS activate macrophage (MΦ) to express pro-inflammation (PI) markers and another set that suppresses PI marker expression by activated MΦ. We show that similar to LPS, three recombinant (r) A. americanum insulin-like growth factor binding-related proteins (rAamIGFBP-rP1, rAamIGFBP-rP6S, and rAamIGFBP-rP6L), hereafter designated as PI-rTSPs, stimulated both PBMC -derived MΦ and mice RAW 267.4 MΦ to express PI co-stimulatory markers, CD40, CD80, and CD86 and cytokines, TNFα, IL-1, and IL-6. In contrast, two A. americanum tick saliva serine protease inhibitors (serpins), AAS27 and AAS41, hereafter designated as anti-inflammatory (AI) rTSPs, on their own did not affect MΦ function or suppress expression of PI markers, but enhanced expression of AI cytokines (IL-10 and TGFβ) in MΦ that were pre-activated by LPS or PI-rTSPs. Mice paw edema test demonstrated that in vitro validated PI- and AI-rTSPs are functional in vivo since injection of HEK293-expressed PI-rTSPs (individually or as a cocktail) induced edema comparable to carrageenan-induced edema and was characterized by upregulation of CD40, CD80, CD86, TNF-α, IL-1, IL-6, and chemokines: CXCL1, CCL2, CCL3, CCL5, and CCL11, whereas the AI-rTSPs (individually and cocktail) were suppressive. We propose that the tick may utilize countervailing PI and AI TSPs to regulate evasion of host immune defenses whereby TSPs such as rAamIGFBP-rPs activate host immune cells and proteins such as AAS27 and AAS41 suppress the activated immune cells.

Several studies have documented immuno-suppressive activities in whole tick saliva and salivary gland protein extracts. We have made contribution toward understanding the molecular basis of tick feeding, as we have described functions of defined tick saliva immuno-modulatory proteins. We have shown that A. americanum injects two groups of functionally opposed tick saliva proteins: those that could counter-intuitively be characterized as pro-host defense, and those that are expected to have anti-host immune defense functions. Based on our data, we propose that the tick evades host defense using countervailing pro- and anti- inflammatory proteins in which the pro-host defense tick saliva proteins stimulate host immune cells such as macrophages, and the anti-host defense tick saliva proteins suppress functions of the activated immune cells.

Dietary Approaches to Attain Fish Health with Special Reference to their Immune System

Fish despite their low collocation in the vertebrate phylum possess a complete immune system. In teleost fish both innate and adaptive immune responses have been described with melanomacrophage centers (MMCs) equivalent to mammalian germinal centers. Primary lymphoid organs are represented by the thymus and kidney, while spleen and mucosa-associated lymphoid tissues act as secondary lymphoid organs. Functions of either innate immune cells (e.g., macrophages and dendritic cells) or adaptive immune cells (T and B lymphocytes) will be described in detail, even including their products, such as cytokines and antibodies. In spite of a robust immune arsenal, fish are very much exposed to infectious agents (marine bacteria, parasites, fungi, and viruses) and, consequentially, mortality is very much enhanced especially in farmed fish. In fact, in aquaculture stressful events (overcrowding), microbial infections very frequently lead to a high rate of mortality. With the aim to reduce mortality of farmed fish through the reinforcement of their immune status the current trend is to administer natural products together with the conventional feed. Then, in the second part of the present review emphasis will be placed on a series of products, such as prebiotics, probiotics and synbiotics, β-glucans, vitamins, fatty acids and polyphenols all used to feed farmed fish. With special reference to polyphenols, results of our group using red grape extracts to feed farmed European sea bass will be illustrated. In particular, determination of cytokine production at intestinal and splenic levels, areas of MMCs and development of hepatopancreas will represent the main biomarkers considered. All together, our own data and those of current literature suggests that natural product administration to farmed fish for their beneficial effects may, in part, solve the problem of fish mortality in aquaculture, enhancing their immune responses.

Mechanisms of African swine fever virus pathogenesis and immune evasion inferred from gene expression changes in infected swine macrophages

African swine fever (ASF) is a swine disease caused by a large, structurally complex, double-stranded DNA virus, African swine fever virus (ASFV). In domestic pigs, acute infection by highly virulent ASF viruses causes hemorrhagic fever and death. Previous work has suggested that ASFV pathogenesis is primarily mediated by host cytokines produced by infected monocytes and macrophages. To better understand molecular mechanisms mediating virus pathogenesis and immune evasion, we used transcriptome analysis to identify gene expression changes after ASFV infection in ex vivo swine macrophages. Our results suggest that the cytokines of TNF family including FASLG, LTA, LTB, TNF, TNFSF4, TNFSF10, TNFSF13B and TNFSF18 are the major causative cytokine factors in ASF pathogenesis via inducing apoptosis. Other up-regulated proinflammatory cytokines (IL17F and interferons) and down-regulated anti-inflammatory cytokine (IL10) may also significantly contribute to ASF pathogenesis and cause excessive tissue inflammatory responses. The differential expression of genes also indicates that ASFV could evade both the innate and adaptive immune responses by (i) inhibiting MHC Class II antigen processing and presentation, (ii) avoiding CD8+ T effector cells and neutrophil extracellular traps via decreasing expression of neutrophil/CD8+ T effector cell-recruiting chemokines, (iii) suppressing M1 activation of macrophages, (iv) inducing immune suppressive cytokines, and (v) inhibiting the processes of macrophage autophagy and apoptosis. These results provide novel information to further investigate and better understand the mechanism of pathogenesis and immune evasion of this devastating swine disease.

The CSF-1-receptor inhibitor, JNJ-40346527 (PRV-6527), reduced inflammatory macrophage recruitment to the intestinal mucosa and suppressed murine T cell mediated colitis

BACKGROUND & AIMS

Originally believed to be primarily a disorder of T-cell signaling, evidence shows that macrophage-lineage cells also contribute to the pathogenesis of Crohn's disease (CD). Colony stimulating factor-1 (CSF-1) is a key regulator of the macrophage lineage, but its role in CD has not been well established. We examined transcriptional data from CD mucosa for evidence of CSF-1 pathway activation and tested JNJ-40346527 (PRV-6527), a small molecule inhibitor of CSF-1 receptor kinase (CSF-1R), for its ability to inhibit disease indices in murine colitis.

METHODS

A CSF-1 pathway gene set was created from microarray data of human whole blood cultured ex vivo with CSF-1 and compared to a TNFα-induced gene set generated from epithelial-lineage cells. Gene set variation analysis was performed using existing Crohn's mucosa microarray data comparing patients who either responded or failed to respond to anti-TNFα therapy. Commencing day 14 or day 21, mice with T-cell transfer colitis were treated with vehicle or JNJ-40346527 until study termination (day 42). Endpoints included colon weight/length ratios and histopathology scores, and macrophage and T cells were assessed by immunohistochemistry. Mucosal gene expression was investigated using RNAseq.

RESULTS

Both the CSF-1 and the TNFα gene sets were enriched in the colonic mucosal transcriptomes of Crohn's disease and in mouse colitis, and expression of both gene sets was highest in patients who did not respond to anti-TNFα therapy. In these patients neither set was reduced by therapy. In the mouse model, JNJ-40346527 inhibited the increase in colon weight/length ratio by ∼50%, reduced histological disease scores by ∼60%, and reduced F4/80+ mononuclear cell and CD3+ lymphocyte numbers. RNAseq analysis confirmed the CSF-1 gene set was sharply reduced in treated mice, as were gene sets enriched in "M1" inflammatory and "M0" resident macrophages and in activated T cells.

CONCLUSIONS

CSF-1 biology is activated in Crohn's disease and in murine T cell transfer colitis. Inhibition of CSF-1R by JNJ-40346527 was associated with attenuated clinical disease scores and reduced inflammatory gene expression in mice. These data provide rationale for testing JNJ-40346527 (PRV-6527) in human inflammatory bowel disease.

The Mechanism of Electroacupuncture at Zusanli Promotes Macrophage Polarization during the Fibrotic Process in Contused Skeletal Muscle

INTRODUCTION

Currently, many clinical experiments are being conducted to study the effect of acupuncture on skeletal muscle contusions, and its therapeutic effect has been confirmed to some extent. However, the mechanism of recovery by electroacupuncture (EA) in skeletal muscles after blunt trauma remains unknown.

OBJECTIVE

To determine whether EA at Zusanli can contribute to the regeneration of contused skeletal muscle and the molecular mechanism involved.

METHODS

Masson's trichrome staining and hematoxylin and eosin staining were used to measure the area of fibrotic tissue and determine the number of centrally nucleated muscle fibers respectively. The different immune phenotypes of macrophages were determined by flow cytometry. Then, ELISA was used to analyze the levels of interleukin-4 (IL-4), IL-6, interferon-α (IFN-α) and interferon-γ (IFN-γ) in the injured tissue. Finally, the expression of MyoD in the tissue was detected by quantitative real-time polymerase chain reaction.

RESULTS

EA at Zusanli helped regenerate contused skeletal muscle by alleviating fibrosis and increasing the size of the regenerating myofibres in the injured skeletal muscle. EA at Zusanli increased the number of M2 macrophages and decreased the number of M1 macrophages in contused skeletal muscle. EA at Zusanli decreased the level of cytokine IFN-γ and increased the levels of IL-4, interleukin-13 (IL-13), and IFN-α, which promoted macrophage polarization during the fibrosis recovery process in the contused skeletal muscle. EA at Zusanli could increase the expression of MyoD in tissues.

CONCLUSIONS

EA at Zusanli promoted macrophage polarization during the fibrotic process in contused skeletal muscle by decreasing cytokine IFN-γ and increasing IL-4, IL-13, and IFN-α, which contributed to the regeneration of the contused skeletal muscle.

Antitumor properties of triptolide: phenotype regulation of macrophage differentiation

Tumor-associated macrophages (TAMs), which generally exhibit an M2-like phenotype, play a critical role in tumor development. Triptolide exerts a unique bioactive spectrum of anticancer activities. The aim of this study was to determine whether triptolide has any effect on the activation of TAMs and the production of tumor-promoting mediators. ICR-1 mice with azoxymethane/dextran sulfate sodium (AOM/DSS)-induced colon tumors and BALB/c mice co-inoculated with 4T1 cells and M2-polarized RAW264.7 cells were used to examine whether the inhibitory effect of triptolide on tumor progression was mediated by the targeting of TAMs. Real-time PCR, Western blot, immunofluorescence staining, and flow cytometry assays were performed to determine the expression of cell surface markers and cytokine production. The results showed that triptolide inhibited macrophage differentiation toward the M2 phenotype and abolished M2 macrophage-mediated tumor progression. Furthermore, triptolide inhibited the expression of M2 markers, such as CD206, Arginase 1, and CD204, and inhibited the secretion of anti-inflammatory cytokines. Thus our study indicated that triptolide selectively inhibited the functions of M2-polarized macrophages and TAMs, and this inhibitory effect of triptolide on TAM viability, differentiation, and cytokine production might elucidate the major mechanisms underlying its antitumor activity. Our findings provide important information for the potential clinical application of triptolide in cancer therapy.

The emerging role of long non-coding RNAs in tumor-associated macrophages

Tumor-associated macrophages (TAMs) are an important cellular component of the tumor microenvironment (TME) and play an essential role in tumor immunity. Recently, numerous studies have indicated that long non-coding RNAs (lncRNAs) can affect several functions of TAMs. In the present review, we summarize the versatile role of lncRNAs in the polarization, epigenetic modulation, and classic signaling pathways of TAMs, which represent a potential target for tumor diagnosis or treatment.

Dual inhibition of CSF1R and MAPK pathways using supramolecular nanoparticles enhances macrophage immunotherapy

Among the numerous immune interactions, or lack-thereof, that occur during cancer progression, tumor-associated macrophages (TAMs) - cancer cell interactions have been shown to play an important role in modulating the tumor-microenvironment to an immune suppressive mode, promoting accelerated tumor growth, survival and metastatic spread. TAMs are predominantly polarized to a pro-tumorigenic M2-phenotype through macrophage colony stimulating factor 1 (MCSF) cytokines that bind to the colony-stimulating factor 1 receptor (CSF1R), a class III receptor tyrosine kinase. This MCSF-CSF1R interaction results in autophosphorylation of CSF1R and subsequent phosphorylation and activation of downstream signaling pathways including mitogen-activated protein kinase (MAPK) pathway leading to proliferation, survival and functional activity of M2 TAMs. Therapeutic inhibition of CSF1R and MAPK signaling could effectively re-polarize M2 macrophages to an anti-tumorigenic M1 phenotype; however, this is challenging. In this study, we demonstrate that concurrent and sustained inhibition of the CSF1R and MAPK signaling pathways using dual-kinase inhibitor-loaded supramolecular nanoparticles (DSNs) enhance repolarization of pro-tumorigenic M2 macrophages to the anti-tumorigenic M1 phenotype. The supramolecular nanoparticles exhibited physical stability of over 7 days during storage conditions at 4 °C and over 24 h in human serum, released the inhibitors in a sustained manner and showed significantly higher internalization and accumulation of inhibitors in the M2 macrophages even at longer time points. When tested in a highly aggressive 4T1 breast cancer model, the supramolecular nanoparticles accumulated in TAMs at a significantly higher concentration, increased M1-like phenotype at significantly higher proportion and improved anti-tumor efficacy as compared to combination of single-inhibitor nanoparticles or the small molecule inhibitors. Our data suggests that concurrent, vertical inhibition of multiple intracellular kinase signaling pathways is important for repolarization of M2 macrophages to M1 phenotype, and by utilizing dual-inhibitor loaded supramolecular nanoparticles, further increase the ability to produce more M1 macrophages as compared to M2 macrophages in the tumor microenvironment. This results in enhanced tumor growth inhibition and reduced toxicity. Therefore, vertical, co-inhibition of CSF1R and downstream signaling pathways like MAPK could be a promising macrophage immunotherapy strategy for aggressive cancers.

Dynamic Function and Composition Changes of Immune Cells During Normal and Pathological Pregnancy at the Maternal-Fetal Interface

A successful pregnancy requires a fine-tuned and highly regulated balance between immune activation and embryonic antigen tolerance. Since the fetus is semi-allogeneic, the maternal immune system should exert tolerant to the fetus while maintaining the defense against infection. The maternal-fetal interface consists of different immune cells, such as decidual natural killer (dNK) cells, macrophages, T cells, dendritic cells, B cells, and NKT cells. The interaction between immune cells, decidual stromal cells, and trophoblasts constitute a vast network of cellular connections. A cellular immunological imbalance may lead to adverse pregnancy outcomes, such as recurrent spontaneous abortion, pre-eclampsia, pre-term birth, intrauterine growth restriction, and infection. Dynamic changes in immune cells at the maternal-fetal interface have not been clearly stated. While many studies have described changes in the proportions of immune cells in the normal maternal-fetus interface during early pregnancy, few studies have assessed the immune cell changes in mid and late pregnancy. Research on pathological pregnancy has provided clues about these dynamic changes, but a deeper understanding of these changes is necessary. This review summarizes information from previous studies, which may lay the foundation for the diagnosis of pathological pregnancy and put forward new ideas for future studies.

mTORC1-mediated polarization of M1 macrophages and their accumulation in the liver correlate with immunopathology in fatal ehrlichiosis

A polarized macrophage response into inflammatory (M1) or regenerative/anti-inflammatory (M2) phenotypes is critical in host response to multiple intracellular bacterial infections. Ehrlichia is an obligate Gram-negative intracellular bacterium that causes human monocytic ehrlichiosis (HME): a febrile illness that may progress to fatal sepsis with multi-organ failure. We have shown that liver injury and Ehrlichia-induced sepsis occur due to dysregulated inflammation. Here, we investigated the contribution of macrophages to Ehrlichia-induced sepsis using murine models of mild and fatal ehrlichiosis. Lethally-infected mice showed accumulation of M1 macrophages (iNOS-positive) in the liver. In contrast, non-lethally infected mice showed polarization of M2 macrophages and their accumulation in peritoneum, but not in the liver. Predominance of M1 macrophages in lethally-infected mice was associated with expansion of IL-17-producing T, NK, and NKT cells. Consistent with the in vivo data, infection of bone marrow-derived macrophages (BMM) with lethal Ehrlichia polarized M0 macrophages into M1 phenotype under an mTORC1-dependent manner, while infection with non-lethal Ehrlichia polarized these cells into M2 types. This work highlights that mTORC1-mediated polarization of macrophages towards M1 phenotype may contribute to induction of pathogenic immune responses during fatal ehrlichiosis. Targeting mTORC1 pathway may provide a novel aproach for treatment of HME.

Exosomes derived from pro-inflammatory bone marrow-derived mesenchymal stem cells reduce inflammation and myocardial injury via mediating macrophage polarization

Exosomes are served as substitutes for stem cell therapy, playing important roles in mediating heart repair during myocardial infarction injury. Evidence have indicated that lipopolysaccharide (LPS) pre-conditioning bone marrow-derived mesenchymal stem cells (BMSCs) and their secreted exosomes promote macrophage polarization and tissue repair in several inflammation diseases; however, it has not been fully elucidated in myocardial infarction (MI). This study aimed to investigate whether LPS-primed BMSC-derived exosomes could mediate inflammation and myocardial injury via macrophage polarization after MI. Here, we found that exosomes derived from BMSCs, in both Exo and L-Exo groups, increased M2 macrophage polarization and decreased M1 macrophage polarization under LPS stimulation, which strongly depressed LPS-dependent NF-κB signalling pathway and partly activated the AKT1/AKT2 signalling pathway. Compared with Exo, L-Exo had superior therapeutic effects on polarizing M2 macrophage in vitro and attenuated the post-infarction inflammation and cardiomyocyte apoptosis by mediating macrophage polarization in mice MI model. Consequently, we have confidence in the perspective that low concentration of LPS pre-conditioning BMSC-derived exosomes may develop into a promising cell-free treatment strategy for clinical treatment of MI.

Asaronic Acid Attenuates Macrophage Activation toward M1 Phenotype through Inhibition of NF-κB Pathway and JAK-STAT Signaling in Glucose-Loaded Murine Macrophages

Macrophage polarization has been implicated in the pathogenesis of obesity and type 2 diabetes, which are recognized as chronic proinflammatory diseases. This study investigated that high level of glucose, similar to lipopolysaccharide (LPS), activated macrophages toward M1 phenotypes and 1-20 μM asaronic acid (AA) counteracted diabetic macrophage activation. AA reduced the LPS-promoted secretion of proinflammatory interleukin (IL)-6 and monocyte chemoattractant protein-1. The LPS markedly elevated the macrophage induction of the M1 markers of Toll-like receptor 4 (TLR4), CD36, and CD68, which was attenuated by AA. Also, the LPS significantly enhanced the nuclear factor (NF)-κB transactivation, signal transducers, and activators of transcription 1 (STAT1)/STAT3 activation and suppressor of cytokine signaling 3 (SOCS3) induction in macrophages. However, AA highly suppressed the aforementioned effects of LPS. Glucose-stimulated macrophages expressed advanced glycation end products (AGEs) and receptor for AGE (RAGE). Administration of 20 μM AA to macrophages partly but significantly attenuated such effects (1.65 ± 0.12 vs 0.95 ± 0.25 times glucose control for AGE; 2.33 ± 0.31 vs 1.40 ± 0.22 times glucose control for RAGE). Furthermore, glucose enhanced the macrophage induction of TLR4 and inducible nitric oxide synthase and IL-6 production, while it demoted the production of anti-inflammatory arginase-1 and IL-10. In contrast, AA reversed the induction of these markers in glucose-loaded macrophages. AA dose-dependently and significantly encumbered NF-κB transactivation, Janus kinase 2 (JAK2) and STAT1/STAT3 activation, and SOCS3 induction upregulated in glucose-supplemented macrophages. These results demonstrated for the first time that AA may limit diabetic macrophage activation toward the M1 phenotype through the inhibition of TLR4-/IL-6-mediated NF-κB/JAK2-STAT signaling entailing AGE-RAGE interaction.

CCL5 deficiency promotes liver repair by improving inflammation resolution and liver regeneration through M2 macrophage polarization

Despite the diverse etiologies of drug-induced liver injury (DILI), innate immunity activation is a common feature involved in DILI progression. However, the involvement of innate immunity regulation in inflammation resolution and liver regeneration in DILI remains obscure. Herein, we identified the chemokine CCL5 as a central mediator of innate immunity regulation in the pathogenesis of DILI. First, we showed that serum and hepatic CCL5 levels are elevated in both DILI patients and an APAP-induced liver injury (AILI) mouse model. Interestingly, both nonparenchymal cells and stressed hepatocytes are cell sources of CCL5 induction in response to liver injury. Functional experiments showed that CCL5 deficiency has no effect on the early phase of AILI but promotes liver repair in the late phase mainly by promoting inflammation resolution and liver regeneration, which are associated with an increased number of hepatic M2 macrophages. Mechanistically, CCL5 can directly activate M1 polarization and impede M2 polarization through the CCR1- and CCR5-mediated activation of the MAPK and NF-κB pathways. We then showed that CCL5 inhibition mediated by either a CCL5-neutralizing antibody or the antagonist Met-CCL5 can greatly alleviate liver injury and improve survival in an AILI mouse model. Our data demonstrate CCL5 induction during DILI, identify CCL5 as a novel innate immunity regulator in macrophage polarization, and suggest that CCL5 blockage is a promising therapeutic strategy for the treatment of DILI.

Developmental programming of adult haematopoiesis system

The Barker hypothesis of 'foetal origin of adult diseases' has led to emphasize the concept of 'developmental programming', based on the crucial role of epigenetic factors. Accordingly, it has been demonstrated that parental adversity (before conception and during pregnancy) and foetal factors (i.e., hypoxia, malnutrition and placental insufficiency) permanently modify the physiological systems of the progeny, predisposing them to premature ageing and chronic disease during adulthood. Thus, an altered functionality of the endocrine, immune, nervous and cardiovascular systems is observed in the progeny. However, it remains to be understood whether the haematopoietic system itself also represents a portrait of foetal programming. Here, we provide evidence, reporting and discussing related theories, and results of studies described in the literature. In addition, we have outlined our opinions and suggest how it is possible to intervene to correct foetal mal-programming. Some pro-health interventions and recommendations are proposed, with the hope of guarantee the health of future generations and trying to combat the continuous increase in age-related diseases in human populations.

Kinsenoside attenuates osteoarthritis by repolarizing macrophages through inactivating NF-κB/MAPK signaling and protecting chondrocytes

The objective was to investigate the effect of kinsenoside (Kin) treatments on macrophage polarity and evaluate the resulting protection of chondrocytes to attenuate osteoarthritis (OA) progression. RAW264.7 macrophages were polarized to M1/M2 subtypes then administered with different concentrations of Kin. The polarization transitions were evaluated with quantitative real-time polymerase chain reaction (qRT-PCR), confocal observation and flow cytometry analysis. The mechanism of Kin repolarizing M1 macrophages was evaluated by Western blot. Further, macrophage conditioned medium (CM) and IL-1β were administered to chondrocytes. Micro-CT scanning and histological observations were conducted in vivo on anterior cruciate ligament transection (ACLT) mice with or without Kin treatment. We found that Kin repolarized M1 macrophages to the M2 phenotype. Mechanistically, Kin inhibited the phosphorylation of IκBα, which further reduced the downstream phosphorylation of P65 in nuclear factor-κB (NF-κB) signaling. Moreover, Kin inhibited mitogen-activated protein kinases (MAPK) signaling molecules p-JNK, p-ERK and p-P38. Additionally, Kin attenuated macrophage CM and IL-1β-induced chondrocyte damage. In vivo, Kin reduced the infiltration of M1 macrophages, promoted M2 macrophages in the synovium, inhibited subchondral bone destruction and reduced articular cartilage damage induced by ACLT. All the results indicated that Kin is an effective therapeutic candidate for OA treatment.

Crocin inhibits titanium particle-induced inflammation and promotes osteogenesis by regulating macrophage polarization

Wear particle-induced periprosthetic inflammatory osteolysis and resultant aseptic loosening are major causes of orthopedic implant failure, for which there are no effective treatments other than revision surgery. Crocin, a carotenoid compound derived from crocus flowers, has anti-inflammatory properties, but its immunomodulatory function and role in particle-induced osteolysis are not well characterized. Here we report the effect of crocin on titanium (Ti) particle-induced macrophage polarization and osteogenic differentiation. We found that crocin induced anti-inflammatory (M2) macrophage polarization and attenuated Ti particle-induced inflammation by promoting the expression of anti-inflammatory cytokines in vitro as well as in vivo in a mouse air-pouch model. Additionally, crocin pre-treated macrophages promoted osteogenic differentiation of co-cultured mouse bone mesenchymal stem cells (BMSCs). These effects were mediated via inhibition of p38 and c-Jun N-terminal kinase signaling. Our results indicate that crocin suppresses Ti particle-induced inflammation and enhances osteogenic differentiation of BMSCs by inducing M2 macrophage polarization, highlighting its therapeutic potential for preventing wear particle-induced osteolysis.

Emerging therapies in rheumatoid arthritis: focus on monoclonal antibodies

Advances in the treatment of rheumatoid arthritis (RA) are attributed to several aspects such as new classification criteria enabling early diagnosis and intensive treatment with the application of treat-to-target principles as well as better understanding of the pathogenesis of RA contributing to the development of targeted therapies. However, reaching remission is still not achieved in most patients with RA, which is one of the driving forces behind the continuous development of novel therapies and the optimization of therapeutic strategies. This review will outline several new therapeutic antibodies modulating anti-inflammatory cytokines interleukin (IL)-2 and IL-10 and pro-inflammatory mediators granulocyte-macrophage colony-stimulating factor, fractalkine, and IL-6 that are in various stages of clinical development as well as the progress in manufacturing biotechnologies contributing to the next generation of antibodies and their potential to expand the therapeutic armamentarium for RA. In addition, the fate of unsuccessful therapies including agents targeting IL-15, the IL-20 family, IL-21, chemokine CXCL10, B-cell activating factor (BAFF), and regulatory T (Treg) cells or a novel concept targeting synovial fibroblasts via cadherin-11 will be discussed.

Tissue Iron Promotes Wound Repair via M2 Macrophage Polarization and the Chemokine (C-C Motif) Ligands 17 and 22

Macrophages are important for effective iron recycling and erythropoiesis, but they also play a crucial role in wound healing, orchestrating tissue repair. Recently, we demonstrated a significant accumulation of iron in healing wounds and a requirement of iron for effective repair. Herein, we sought to determine the influence of iron on macrophage function in the context of wound healing. Interestingly, wound macrophages extensively sequestered iron throughout healing, associated with a prohealing M2 phenotype. In delayed healing diabetic mouse wounds, both macrophage polarization and iron sequestration were impaired. In vitro studies revealed that iron promotes differentiation, while skewing macrophages toward a hypersecretory M2-like polarization state. These macrophages produced high levels of chemokine (C-C motif) ligands 17 and 22, promoting wound reepithelialization and extracellular matrix deposition in a human ex vivo wound healing model. Together, these findings reveal a novel, unappreciated role for iron in modulating macrophage behavior to promote subsequent wound repair. These findings support therapeutic evaluation of iron use to promote wound healing in the clinic.

Functional aspects, phenotypic heterogeneity, and tissue immune response of macrophages in infectious diseases

Macrophages are a functionally heterogeneous group of cells with specialized functions depending not only on their subgroup but also on the function of the organ or tissue in which the cells are located. The concept of macrophage phenotypic heterogeneity has been investigated since the 1980s, and more recent studies have identified a diverse spectrum of phenotypic subpopulations. Several types of macrophages play a central role in the response to infectious agents and, along with other components of the immune system, determine the clinical outcome of major infectious diseases. Here, we review the functions of various macrophage phenotypic subpopulations, the concept of macrophage polarization, and the influence of these cells on the evolution of infections. In addition, we emphasize their role in the immune response in vivo and in situ, as well as the molecular effectors and signaling mechanisms used by these cells. Furthermore, we highlight the mechanisms of immune evasion triggered by infectious agents to counter the actions of macrophages and their consequences. Our aim here is to provide an overview of the role of macrophages in the pathogenesis of critical transmissible diseases and discuss how elucidation of this relationship could enhance our understanding of the host-pathogen association in organ-specific immune responses.

Long non-coding RNA expressed in macrophage co-varies with the inflammatory phenotype during macrophage development and polarization

Advances in microarray, RNA‐seq and omics techniques, thousands of long non‐coding RNAs (lncRNAs) with unknown functions have been discovered. LncRNAs have presented a diverse perspective on gene regulation in diverse biological processes, especially in human immune response. Macrophages participate in the whole phase of immune inflammatory response. They are able to shape their phenotype and arouse extensive functional activation after receiving physiological and pathological stimuli. Emerging studies indicated that lncRNAs participated in the gene regulatory network during complex biological processes of macrophage, including macrophage‐induced inflammatory responses. Here, we reviewed the existing knowledges of lncRNAs in the processes of macrophage development and polarization, and their roles in several different inflammatory diseases. Specifically, we focused on how lncRNAs function in macrophage, which might help to discover some potential therapeutic targets and diagnostic biomarkers.

DUSP6 Inhibitor (E/Z)-BCI Hydrochloride Attenuates Lipopolysaccharide-Induced Inflammatory Responses in Murine Macrophage Cells via Activating the Nrf2 Signaling Axis and Inhibiting the NF-κB Pathway

Macrophages play a fundamental role in human chronic diseases such as rheumatoid arthritis, atherosclerosis, and cancer. In the present study, we demonstrated that dual-specificity phosphatase 6 (DUSP6) was upregulated by lipopolysaccharide (LPS) treatment of macrophages. (E/Z)-BCI hydrochloride (BCI) functions as a small molecule inhibitor of DUSP6, and BCI treatment inhibited DUSP6 expression in LPS-activated macrophages. BCI treatment inhibited LPS-triggered inflammatory cytokine production, including IL-1β and IL-6, but not TNF-α, and also affected macrophage polarization to an M1 phenotype. In addition, BCI treatment decreased reactive oxygen species (ROS) production and significantly elevated the levels of Nrf2. Interestingly, pharmacological inhibition of DUSP6 attenuated LPS-induced inflammatory responses was independent of extracellular signal-regulated kinase (ERK) signaling. Furthermore, BCI treatment inhibited phosphorylation of P65 and nuclear P65 expression in LPS-activated macrophages. These results demonstrated that pharmacological inhibition of DUSP6 attenuated LPS-induced inflammatory mediators and ROS production in macrophage cells via activating the Nrf2 signaling axis and inhibiting the NF-κB pathway. These anti-inflammatory effects indicated that BCI may be considered as a therapeutic agent for blocking inflammatory disorders.

12-Lipoxygenase is a Critical Mediator of Type II Pneumocyte Senescence, Macrophage Polarization and Pulmonary Fibrosis after Irradiation

Radiation-induced pulmonary fibrosis (RIPF) is a chronic, progressive complication of therapeutic irradiation of the thorax. It has been suggested that senescence of type II pneumocytes (AECIIs), an alveolar stem cell, plays a role in the development of RIPF through loss of replicative reserve and via senescent AECII-driven release of proinflammatory and profibrotic cytokines. Within this context, we hypothesized that arachidonate 12-lipoxygenase (12-LOX) is a critical mediator of AECII senescence and RIPF. Treatment of wild-type AECIIs with 12S-hydroxyeicosateraenoic acid (12S-HETE), a downstream product of 12-LOX, was sufficient to induce senescence in a NADPH oxidase 4 (NOX4)-dependent manner. Mice deficient in 12-LOX exhibited reduced AECII senescence, pulmonary collagen accumulation and accumulation of alternatively activated (M2) macrophages after thoracic irradiation (5 × 6 Gy) compared to wild-type mice. Conditioned media from irradiated or 12S-HETE-treated primary pneumocytes contained elevated levels of IL-4 and IL-13 compared to untreated pneumocytes. Primary macrophages treated with conditioned media from irradiated AECII demonstrated preferential M2 type polarization when AECIIs were derived from wild-type mice compared to 12-LOX-deficient mice. Together, these data identified 12-LOX as a critical component of RIPF and a therapeutic target for radiation-induced lung injury.

Interaction of transforming growth factor-β-Smads/microRNA-362-3p/CD82 mediated by M2 macrophages promotes the process of epithelial-mesenchymal transition in hepatocellular carcinoma cells

Abnormal tumor microenvironment and the epithelial‐mesenchymal transition (EMT) are important features of tumor metastasis. However, it remains unknown how signals can form complicated networks to regulate the sustainability of the EMT process. The aim of our study is to explore the possible interaction between tumor‐associated macrophages and tumor cells in the EMT process mediated by microRNA (miR)‐362‐3p. In this study, we found that by releasing TGF‐β, M2 macrophages mediate binding of Smad2/3 to miR‐362‐3p promoter, leading to overexpression of miR‐362‐3p. MicroRNA‐362‐3p maintains EMT by regulating CD82, one of the most important members of the family of tetraspanins. Our finding suggests that miR‐362‐3p can serve as a core factor mediating cross‐talk between the TGF‐β pathway in tumor‐associated macrophages and tetraspanins in tumor cells, and thus facilitates the EMT process.

FuFangChangTai Decoction Activates Macrophages via Inducing Autophagy

The traditional Chinese medicine decoction FuFangChangTai (FFCT) has been used in the therapy of colon cancer clinically, yielding alleviated toxicity and enhanced immunity. In our previous study, FFCT exerted its antitumor activity not only by inducing apoptosis but also by activating autophagy to eliminate tumor cells. However, its mechanism is not well understood. The purpose of this study was to investigate the relationship between macrophages activation and FFCT-induced autophagy. Results showed that FFCT could induce autophagy in colon cancer, as demonstrated by increased level of intracellular autophagy marker LC3 II in CT26.WT cells by fluorescence microscope and western blot assay. FFCT also facilitated numbers of vesicular bodies with bilayer membrane in CT26.WT cells, which were indicative of autophagosomes formation. Autophagosomes secreted by FFCT-treated CT26.WT cells can activate M1 type macrophages, accompanied with increased expression of costimulatory molecules CD86 and CD40 on the surface of RAW264.7 cells, and more inflammatory cytokines secretion, such as TNF-α, IL-6, MCP-1, and IL-1β. mRNA expressions of M2 macrophages markers, such as IL-10, CD206, Arg-1, and FIZZ-1, were downregulated. And this process helps regulate the polarization of macrophages and promote the immune response. These findings support a mechanism of FFCT-induced autophagy and provide novel evidence demonstrating that macrophages are involved in FFCT-induced autophagy progression.

Aspergillus fumigatus enhances human NK cell activity by regulating M1 macrophage polarization

The progression of disease caused by fungal infection is closely associated with the human immune system. Macrophages and natural killer cells (NK cells) are two important types of innate immune cells that serve an important role in anti-infection immunity. There has been limited research into the interactions between fungi and macrophages. In the present in vitro study, reverse transcription-quantitative PCR, ELISA and flow cytometry were performed to reveal that the interaction between macrophages and NK cells, regulated by Aspergillus fumigatus conidia, induced macrophages to polarize into M1 macrophages by secreting large quantities of tumor necrosis factor-α, interleukin-18 and Galectin-9. In addition, when NK cells were co-cultured with the conidia of A. fumigatus-stimulated M1 macrophages, they exhibited increased activation levels and secretion of interferon-γ (IFN-γ). It was further demonstrated via antibody neutralization and gene silencing experiments that galectin-9 served an important role in the interaction between macrophages and NK cells regulated by A. fumigatus. In conclusion, it was demonstrated that A. fumigatus induced the polarization of macrophages into M1 macrophages by secreting Galectin-9, which then promoted NK cell activity and IFN-γ secretion. The results provided improved understanding of the role of innate immune cells in invasive fungal infections. The present study also provided novel insight into the study of macrophages and NK cells in inflammatory infections caused by A. fumigatus and potential strategies to control the progression of inflammation.

Transcriptomics Analysis Reveals New Insights into the Roles of Notch1 Signaling on Macrophage Polarization

Naïve macrophages (Mφ) polarize in response to various environmental cues to a spectrum of cells that have distinct biological functions. The extreme ends of the spectrum are classified as M1 and M2 macrophages. Previously, we demonstrated that Notch1 deficiency promotes Tgf-β2 dependent M2-polarization in a mouse model of abdominal aortic aneurysm. The present studies aimed to characterize the unique set of genes regulated by Notch1 signaling in macrophage polarization. Bone marrow derived macrophages isolated from WT or Notch1+/- mice (n = 12) were differentiated to Mφ, M1 or M2-phenotypes by 24 h exposure to vehicle, LPS/IFN-γ or IL4/IL13 respectively and total RNA was subjected to RNA-Sequencing (n = 3). Bioinformatics analyses demonstrated that Notch1 haploinsufficiency downregulated the expression of 262 genes at baseline level, 307 genes with LPS/IFN-γ and 254 genes with IL4/IL13 treatment. Among these, the most unique genes downregulated by Notch1 haploinsufficiency included fibromodulin (Fmod), caspase-4, Has1, Col1a1, Alpl and Igf. Pathway analysis demonstrated that extracellular matrix, macrophage polarization and osteogenesis were the major pathways affected by Notch1 haploinsufficiency. Gain and loss-of-function studies established a strong correlation between Notch1 haploinsufficiency and Fmod in regulating Tgf-β signaling. Collectively, our studies suggest that Notch1 haploinsufficiency increases M2 polarization through these newly identified genes.

Combination of G-CSF and AMD3100 Improves the Anti-inflammatory Effect of Mesenchymal Stem Cells on Inducing M2 Polarization of Macrophages Through NF-κB-IL1RA Signaling Pathway

Mobilized peripheral blood-derived mesenchymal stem cells (PB-MSCs) mainly derived from bone marrow-derived MSCs (BM-MSCs) exert a similar anti-inflammatory effect. However, the mechanism of anti-inflammatory effect of mobilized PB-MSCs by a combination of G-CSF and AMD3100 remains unclear. Cultured rat PB-MSCs mobilized by G-CSF/AMD3100 have shown typical surface markers and potential for multiple differentiations, similar to non-mobilized BM-MSCs. In a co-culture system, rat M0-type macrophages co-cultured with PB-MSCs have shown higher expression of M2 markers including CD206, Arg-1, IL-10, and CCL-22 than BM-MSCs, indicating that PB-MSCs induced greater M0 polarization to M2. Furthermore, compared with BM-MSCs, PB-MSCs in a co-culture system with lipopolysaccharide-induced M1-type macrophages more efficiently promoted M1 polarization to M2, accompanied by increasing expression of CD206, Arg-1, IL-10, and CCL-22 while decreasing expression of M1 markers including iNOS, TNF-α, IL-1β and IL-6, indicating that PB-MSCs triggered greater M1 polarization to M2. Subsequently, polymerase chain reaction arrays showed higher expressions of both IL1rn and Tnfrsf11b in PB-MSCs versus BM-MSCs. In response to an inflammatory niche, such as TNF-α, PB-MSCs have shown higher expression and release of IL1RA, causing greater M2 polarization of macrophages, and the special effects may be almost entirely abolished through the neutralization antibody of IL1RA. Mechanistic studies determined that PB-MSCs showed higher levels NF-κBp65 and NF-κBp-p65 than BM-MSCs, which could be obviously enhanced by TNF-α. And the increased IL1RA expression by TNF-α in PB-MSCs could be markedly canceled by an NF-κB inhibitor PDTC. Interestingly, mimicking the mobilized PB-MSCs by a combination of G-CSF and AMD3100 in vivo, BM-MSCs were treated with G-CSF and/or AMD3100 in vitro, showing the increased expressions of NF-κBp65 and IL1RA, which could be prominently abolished by PDTC. Therefore, targeting IL1rn, gene modification or drug intervention for MSCs may provide a novel therapeutic strategy for human diseases, especially inflammatory diseases.

Macrophage Polarization in the Development and Progression of Ovarian Cancers: An Overview

Ovarian cancer is the most lethal gynecological malignancy worldwide. Most patients are diagnosed at late stages because of atypical symptoms and the lack of effective early diagnostic measures. The mechanisms underlying the oncogenesis and development of ovarian cancer are not clear. Macrophages, immune cells derived from the innate immune system, have two states of polarization (M1 and M2) that develop in response to different stimuli. The polarization and differentiation of macrophages into the cancer-inhibiting M1 and cancer-promoting M2 types represent the two states of macrophages in the tumor microenvironment. The interaction of polarized macrophages with cancer cells plays a crucial role in a variety of cancers. However, the effects of macrophage M1/M2 polarization on ovarian cancer have not yet been systematically and fully discussed. In this review, we discuss not only the occurrence, development and influences of macrophage polarization but also the association between macrophage polarization and ovarian cancer. The polarization of macrophages into the M1 and M2 phenotypes plays a pivotal role in ovarian cancer initiation, progression, and metastasis, and provides targets for macrophage-centered treatment in the cancer microenvironment for ovarian cancer therapy. We also addressed the regulation of macrophage polarization in ovarian cancer via noncoding RNAs, exosomes, and epigenetics.

Immune Cell Metabolism in Tumor Microenvironment

Tumor microenvironment (TME) is composed of tumor cells, immune cells, cytokines, extracellular matrix, etc. The immune system and the metabolisms of glucose, lipids, amino acids, and nucleotides are integrated in the tumorigenesis and development. Cancer cells and immune cells show metabolic reprogramming in the TME, which intimately links immune cell functions and edits tumor immunology. Recent findings in immune cell metabolism hold the promising possibilities toward clinical therapeutics for treating cancer. This chapter introduces the updated understandings of metabolic reprogramming of immune cells in the TME and suggests new directions in manipulation of immune responses for cancer diagnosis and therapy.

Additive effects of inhibiting both mTOR and glutamine metabolism on the arthritis in SKG mice

Glutamine metabolism and the mechanistic target of rapamycin (mTOR) pathway are activated cooperatively in the differentiation and activation of inflammatory immune cells. But the combined inhibition of both pathways was rarely investigated. This study investigated how inhibiting both glutamine metabolism with 6-diazo-5-oxo-L-norleucine (DON) and mTOR with rapamycin affects immune cells and the arthritis in a mouse model. We revealed that rapamycin and DON additively suppressed CD4⁺ T cell proliferation, and both of them inhibited Th17 cell differentiation. While DON inhibited the differentiation of dendritic cells and macrophages and facilitated that of Ly6G⁺ granulocytic (G)-MDSCs more strongly than did rapamycin, G-MDSCs treated with rapamycin but not DON suppressed CD4⁺ T cell proliferation in vitro. The combination of rapamycin and DON significantly suppressed the arthritis in SKG mice more strongly than did each monotherapy in vivo. The numbers of CD4⁺ T and Th17 cells in the spleen were lowest in mice treated with the combination therapy. Thus, combined treatment with rapamycin and DON additively ameliorated the arthritis in SKG mice, possibly by suppressing CD4⁺ T cell proliferation and Th17 differentiation. These results suggest the combination of rapamycin and DON may be a potential novel therapy for arthritis.

Advanced antibacterial activity of biocompatible tantalum nanofilm via enhanced local innate immunity

Tantalum (Ta) has been shown to enhance osseointegration in clinical practice, yet little is known about whether Ta nanofilms can be used as antimicrobial coatings in vivo. A highly biocompatible Ta nanofilm was developed using magnetron sputtering technology to further study the mechanism of its antibacterial effects in vivo and elucidate its potential for clinical translation. The Ta nanofilms exhibited effective antimicrobial activity against soft tissue infections but did not show an intrinsic antimicrobial effect in vitro. This inconsistency between the in vivo and in vitro antimicrobial effects was further investigated using ex vivo models. The Ta nanofilms could enhance the phagocytosis of bacteria by polymorphonuclear neutrophils (PMNs, neutrophils), reduce the lysis of neutrophils and enhance the proinflammatory cytokine release of macrophages. This accumulative enhancement of the local host defenses contributed to the favorable antibacterial effect in vivo. The alleviated osteolysis observed in the presence of the Ta nanofilms in the osteomyelitis model further proved the practicality of this antibacterial strategy in the orthopedic field. In summary, Ta nanofilms show excellent biocompatibility and in vivo antimicrobial activity mediated by the enhancement of local innate immunity and are promising for clinical application. STATEMENT OF SIGNIFICANCE: In this study, Ta nanofilms were deposited on titanium substrate by magnetron sputtering. Ta nanofilms exhibited excellent in vivo and in vitro biocompatibility. In vivo antimicrobial effects of Ta nanofilms were revealed by soft tissue infection and osteomyelitis models, while no direct antibacterial activity was observed in vitro. Comprehensive ex vivo models revealed that Ta nanofilms could enhance the phagocytosis of bacteria by neutrophils, reduce the lysis of neutrophils and promote the release of proinflammatory cytokines from macrophages. This immunomodulatory effect helps host to eliminate bacteria. In contrast to traditional antimicrobial nanocoatings which apply toxic materials to kill bacteria, this work proposes a safe, practical and effective Ta nanofilm immunomodulatory antimicrobial strategy with clinical translational prospect.

TIMP-1 Mediates Inflammatory and Immune Response to IL-6 in Adult Orbital Xanthogranulomatous Disease

Purpose: To explore the pathogenesis that TIMP-1 mediated in adult orbital xanthogranulomatous disease (AOXGD), a rare type of non-Langerhans histiocytosis that damages the appearance and quality of life of patientsMethods: We reviewed 22 patients diagnosed with AOXGD based on clinical manifestations and histological analysis, and then investigated the expression of TIMP-1 and IL-6 with q-PCR and IHC in AOXGD tissues and the possible mechanism involved in the induction of TIMP-1 by IL-6.Results: IL-6 and TIMP-1 were significantly increased in AOXGD tissues. IL-6 promoted TIMP-1 production by M1 macrophages by stimulating the phosphorylation of JAK2 and STAT3. Moreover, IL-17 and IFN-γ, the classical markers of Th1 and Th17 cells, were increased in AOXGD.Conclusion: These data implied that the IL6~JAK2/STAT3-TIMP-1 signalling pathway is activated in AOXGD and that adaptive Th1 and Th17 responses are involved in the development of AOXGD.

Soluble receptor for advanced glycation end-products enhanced the production of IFN-γ through the NF-κB pathway in macrophages recruited by ischemia/reperfusion

The current study investigated the role of sRAGE in the production of IFN‑γ in macrophages with I/R treatment. The number of macrophages in myocardial tissues treated with I/R with or without sRAGE was determined via immunohistochemical staining. Proliferative activity of macrophages was analyzed by a 5‑BrdU incorporation assay. Differentiation of macrophages was detected via immunofluorescence staining of iNOS (M1 macrophage marker). IFN‑γ production, due to sRAGE stimulation, in Raw 264.7 macrophages and the NF‑κB signaling pathway were measured using western blotting. A ChIP assay was used to examine the interactions between NF‑κB and the promoter of IFN‑γ. The results showed that the number of macrophages in I/R‑treated myocardial tissues was increased following sRAGE infusion. Proliferation of macrophages was increased significantly in the presence of sRAGE; after I/R treatment, the cells preferred to differentiate into M1 macrophages. IFN‑γ expression in Raw 264.7 macrophages was suppressed by an NF‑κB inhibitor (Bay117082) but enhanced by sRAGE, with or without I/R treatment. Furthermore, sRAGE increased the phosphorylation of IκB, IKK and NF‑κB, as well as the translocation of NF‑κB into the nucleus of Raw 264.7 macrophages, with or without I/R treatment. ChIP results showed that sRAGE promoted NF‑κB binding to the promoter of IFN‑γ in Raw 264.7 macrophages. Therefore, the findings of the present study indicated that sRAGE protected the heart from I/R injuries, which might be mediated by promoting infiltration and the differentiation of macrophages into M1, which would then synthesize and secrete IFN‑γ through activating the NF‑κB signaling pathway.

Defective Induction of COX-2 Expression by Psoriatic Fibroblasts Promotes Pro-inflammatory Activation of Macrophages

Fibroblasts play an important role as members of the innate immune system through the secretion of COX-2-derived inflammatory mediators such as prostaglandin E₂ (PGE₂). However, it has been described that dermal fibroblasts behave like mesenchymal stem cells reducing lymphocyte recruitment and dendritic cell activation through PGE₂ release. As the role of fibroblasts in psoriasis remains poorly characterized, in the present study we have evaluated the possible influence of PGE₂ derived from dermal fibroblasts as modulator of the immune response in psoriatic skin. Our results indicate that under inflammatory conditions, psoriatic fibroblasts showed defective induction of COX-2, which resulted in diminished production of PGE₂, in contrast to healthy fibroblasts. This phenotype correlated with deficient c-Jun N-terminal kinase (JNK) activation, in accordance with the hypothesis that alterations in members of the JNK pathway are associated with psoriasis. Furthermore, conditioned medium from psoriatic fibroblasts promoted the polarization of monocytic cells toward a pro-inflammatory profile, effect that was mimicked in healthy fibroblasts after pre-incubation with indomethacin. These results are consistent with a prominent role of dermal fibroblasts in the regulation of inflammatory response through the participation of COX-derived metabolites. This resolutive behavior seems to be defective in psoriatic fibroblasts, offering a possible explanation for the chronification of the disease and for the exacerbation triggered by nonsteroidal anti-inflammatory drugs (NSAIDS) such as indomethacin.

Psychological Stress and Mitochondria: A Conceptual Framework

BACKGROUND

The integration of biological, psychological, and social factors in medicine has benefited from increasingly precise stress response biomarkers. Mitochondria, a subcellular organelle with its own genome, produce the energy required for life and generate signals that enable stress adaptation. An emerging concept proposes that mitochondria sense, integrate, and transduce psychosocial and behavioral factors into cellular and molecular modifications. Mitochondrial signaling might in turn contribute to the biological embedding of psychological states.

METHODS

A narrative literature review was conducted to evaluate evidence supporting this model implicating mitochondria in the stress response, and its implementation in behavioral and psychosomatic medicine.

RESULTS

Chronically, psychological stress induces metabolic and neuroendocrine mediators that cause structural and functional recalibrations of mitochondria, which constitutes mitochondrial allostatic load. Clinically, primary mitochondrial defects affect the brain, the endocrine system, and the immune systems that play a role in psychosomatic processes, suggesting a shared underlying mechanistic basis. Mitochondrial function and dysfunction also contribute to systemic physiological regulation through the release of mitokines and other metabolites. At the cellular level, mitochondrial signaling influences gene expression and epigenetic modifications, and modulates the rate of cellular aging.

CONCLUSIONS

This evidence suggests that mitochondrial allostatic load represents a potential subcellular mechanism for transducing psychosocial experiences and the resulting emotional responses-both adverse and positive-into clinically meaningful biological and physiological changes. The associated article in this issue of Psychosomatic Medicine presents a systematic review of the effects of psychological stress on mitochondria. Integrating mitochondria into biobehavioral and psychosomatic research opens new possibilities to investigate how psychosocial factors influence human health and well-being across the life-span.

Activation of Nicotinic Acetylcholine α7 Receptor Attenuates Progression of Monocrotaline-Induced Pulmonary Hypertension in Rats by Downregulating the NLRP3 Inflammasome

Background: Inflammation and altered immunity contribute to the development of pulmonary arterial hypertension (PH). The alpha 7 nicotinic acetylcholine receptor (α7nAChR) possesses anti-inflammatory activities. The current study was performed to investigate the effects of a selective α7nAChR agonist, PNU-282987, on controlling a monocrotaline (MCT)-induced rat model of PH and explored the underlying mechanisms.

Methods: Sprague-Dawley rats were injected with MCT and treated with PNU-282987 at the prevention (starting 1 week before MCT) and treatment (starting 2 weeks after MCT) settings. Four weeks after MCT injection, hemodynamic changes, right ventricular structure, and lung morphological features were assessed. Enzyme-linked immunosorbent assay, Western blot and qRT-PCR were performed to assess levels of inflammatory cytokines and NLRP3 (Nod-like receptor family pyrin domain-containing 3) inflammasome pathway in the rat lung tissues. In addition, the lung macrophage line NR8383 was used to confirm the in vivo data.

Results: Monocrotaline injection produced PH in rats and downregulated α7nAChR mRNA and protein expression in rat lung tissues compared to sham controls. Pharmacological activation of α7nAChR by PNU-282987 therapy improved the rat survival rate, attenuated the development of PH as assessed by remodeling of pulmonary arterioles, reduced the right ventricular (RV) systolic pressure, and ameliorated the hypertrophy and fibrosis of the RV in rats with MCT-induced PH. The expression of TNF-α, IL-6, IL-1β, and IL-18 were downregulated in rat lung tissues, which implied that PNU-282987 therapy may help regulate inflammation. These protective effects involved the inhibition of the NLRP3 inflammasome. In vitro assays of cultured rat lung macrophages confirmed that the anti-inflammation effect of PNU-282987 therapy may contribute to the disturbance of NLRP3 inflammasome activation.

Conclusion: Targeting α7nAChR with PNU-282987 could effectively prevent and treat PH with benefits for preventing ongoing inflammation in the lungs of rats with MCT-induced PH by inhibiting NLRP3 inflammasome activation.

M2 Macrophages as a Potential Target for Antiatherosclerosis Treatment

Atherosclerosis is a chronic progressive inflammation course, which could induce life-threatening diseases such as stroke and myocardial infarction. Optimal medical treatments for atherosclerotic risk factors with current antihypertensive and lipid-lowering drugs (for example, statins) are widely used in clinical practice. However, many patients with established disease still continue to have recurrent cardiovascular events in spite of treatment with a state-of-the-art therapy. Atherosclerotic cardiovascular disease (ASCVD) remains the leading cause of mortality worldwide. Hence, current treatment of atherosclerosis is still far from being satisfactory. Recently, M2 macrophages have been found associated with atherosclerosis regression. The M2 phenotype can secrete anti-inflammatory factors such as IL-10 and TGF-β, promote tissue remodeling and repairing through collagen formation, and clear dying cells and debris by efferocytosis. Therefore, modulators targeting macrophages' polarization to the M2 phenotype could be another promising treatment strategy for atherosclerosis. Two main signaling pathways, the Akt/mTORC/LXR pathway and the JAK/STAT6 pathway, are found playing important roles in M2 polarization. In addition, researchers have reported several potential approaches to modulate M2 polarization. Inhibiting or activating some kinds of enzymes, affecting transcription factors, or acting on several membrane receptors could regulate the polarization of the M2 phenotype. Besides, biomolecules, for example vitamin D, were found to affect the process of M2 polarization. Pomegranate juice could promote M2 polarization via unclear mechanism. In this review, we will discuss how M2 macrophages affect atherosclerosis regression, signal transduction in M2 polarization, and outline potential targets and compounds that affect M2 polarization, thus controlling the progress of atherosclerosis.

Leukadherin-1-Mediated Activation of CD11b Inhibits LPS-Induced Pro-inflammatory Response in Macrophages and Protects Mice Against Endotoxic Shock by Blocking LPS-TLR4 Interaction

Dysregulation of macrophage has been demonstrated to contribute to aberrant immune responses and inflammatory diseases. CD11b, expressed on macrophages, plays a critical role in regulating pathogen recognition, phagocytosis, and cell survival. In the present study, we explored the effect of leukadherin-1 (LA1), an agonist of CD11b, on regulating LPS-induced pro-inflammatory response in macrophages and endotoxic shock. Intriguingly, we found that LA1 could significantly reduce mortalities of mice and alleviated pathological injury of liver and lung in endotoxic shock. In vivo studies showed that LA1-induced activation of CD11b significantly inhibited the LPS-induced pro-inflammatory response in macrophages of mice. Moreover, LA1-induced activation of CD11b significantly inhibited LPS/IFN-γ-induced pro-inflammatory response in macrophages by inhibiting MAPKs and NF-κB signaling pathways in vitro. Furthermore, the mice injected with LA1-treated BMDMs showed fewer pathological lesions than those injected with vehicle-treated BMDMs in endotoxic shock. In addition, we found that activation of TLR4 by LPS could endocytose CD11b and activation of CD11b by LA1 could endocytose TLR4 in vitro and in vivo, subsequently blocking the binding of LPS with TLR4. Based on these findings, we concluded that LA1-induced activation of CD11b negatively regulates LPS-induced pro-inflammatory response in macrophages and subsequently protects mice from endotoxin shock by partially blocking LPS-TLR4 interaction. Our study provides a new insight into the role of CD11b in the pathogenesis of inflammatory diseases.

Telmisartan induces browning of fully differentiated white adipocytes via M2 macrophage polarization

Telmisartan is a well-known anti-hypertensive drug acting as an angiotensin 2 receptor blocker (ARB), but it also possesses partial PPARγ agonistic activity and induces insulin sensitivity. In the present study, we investigated the effects of telmisartan on macrophage polarization in association with its browning capacity, because PPARγ plays a key role in M2 polarization and in the browning of white adipocytes. Telmisartan induced M2 marker expression in murine macrophages concentration dependently, which was confirmed by flow cytometry. Both PPARγ and PPARδ activations appear to be responsible for telmisartan-induced M2 polarization. Telmisartan-treated conditioned medium (Tel-CM) of RAW264.7 cells and of bone marrow derived macrophages (BMDM) induced the expressions of browning markers in fully differentiated white adipocytes with reduced lipid droplets, and increased oxygen consumption rate and mitochondrial biogenesis. Levels of catecholamines (CA) released into the conditioned medium as well as intracellular tyrosine hydroxylase (TH) mRNAs were found to be increased by telmisartan, and browning effects of Tel-CM were lessened by β3 receptor antagonist (L-748,337), suggesting CA secreted into CM play a role in Tel-CM-induced adipocyte browning. Acute administration of telmisartan (2 weeks, p.o.) to C57BL/6J mice increased the expressions of browning markers and M2 markers in white adipose tissues, whereas macrophage depletion by clodronate liposome pretreatment attenuated the telmisartan-induced expressions of browning markers. Together, telmisartan was observed to induce the browning of fully differentiated white adipocytes, at least in part, via PPAR activation-mediated M2 polarization.

INT-HA induces M2-like macrophage differentiation of human monocytes via TLR4-miR-935 pathway

As a major component of the microenvironment of solid tumors, tumor-associated macrophages (TAMs) facilitate tumor progression. Intermediate-sized hyaluronan (INT-HA) fragments have an immunological function in cell differentiation; however, their role in promoting the polarization of non-activated macrophages to an M2-like TAM phenotype has not been characterized, and the underlying mechanisms remain unclear. Here, we used a miRNA microarray to find that some miRNAs (especially miR-935) were differentially regulated in INT-HA-induced M2-like macrophages. According to RT-qPCR and Western blot, there was an association between miR-935 and C/EBPβ, that control the polarization of macrophages. Moreover, we found that INT-HA induced an M2-like phenotype via the TLR4 receptor. In our study, there was a negative correlation between plasma HA and miR-935 in monocytes from the peripheral blood of patients with solid tumors. There was also a negative correlation between miR-935 and M2-like macrophage markers in monocytes. These findings suggest that HA fragments interact with TLR4 and educate macrophage polarization to an M2-like phenotype via miR-935. Therefore, this study provides new insight into the role of miR-935 in INT-HA-induced M2-like polarization, and suggests a potential therapeutic target for antitumor treatment.