Probiotics protect mice from CoCrMo particles-induced osteolysis

Wear particle-induced inflammatory osteolysis is the primary cause of aseptic loosening, which is the most common reason for total hip arthroplasty (THA) failure in the med- and long term. Recent studies have suggested an important role of gut microbiota (GM) in modulating the host metabolism and immune system, leading to alterations in bone mass. Probiotic bacteria administered in adequate amounts can alter the composition of GM and confer health benefits to the host. Given the inflammatory osteolysis that occurs in wear debris-induced prosthesis loosening, we examined whether the probiotic Lactobacillus casei could reduce osteolysis in a mouse calvarial resorption model. In this study, L. casei markedly protected mice from CoCrMo particles (CoPs)-induced osteolysis. Osteoclast gene markers and the number of osteoclasts were significantly decreased in L. casei-treated mice. Probiotic treatment decreased the M1-like macrophage phenotype indicated by downregulation of tumor necrosis factor α (TNF-α), interleukin (IL)-6 and inducible nitric oxide synthase (iNOS) and increased the M2-like macrophage phenotype indicated by upregulation of IL-4, IL-10 and arginase. Collectively, these results indicated that the L. casei treatment modulated the immune status and suppressed wear particle-induced osteolysis in vivo. Thus, probiotic treatment may represent a potential preventive and therapeutic approach to reduced wear debris-induced osteolysis.

Establishment of NF-κB sensing and interleukin-4 secreting mesenchymal stromal cells as an "on-demand" drug delivery system to modulate inflammation

Chronic inflammation is associated with up-regulation of the transcription factor nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB) and excessive inflammatory cytokine secretion by M1 macrophages. The anti-inflammatory cytokine interleukin (IL)-4 converts pro-inflammatory M1 macrophages into an anti-inflammatory and tissue-regenerative M2 phenotype, thus reducing inflammation and enhancing tissue regeneration. We have generated NF-κB responsive, or constitutively active IL-4 expression lentiviral vectors transduced into murine bone marrow-derived mesenchymal stromal cells (MSCs). MSCs with a constitutively active IL-4 expression vector produced large quantities of IL-4 continuously, whereas IL-4 secretion was significantly induced by lipopolysaccharide (LPS) in the NF-κB sensing MSCs. In contrast, LPS had no effect on MSCs with IL-4 secretion driven by a constitutively active promoter. We also found that intermittent and continuous LPS treatment displayed distinct NF-κB activation profiles, and this regulation was independent of IL-4 signaling. The supernatant containing IL-4 from the LPS-treated MSCs suppressed M1 marker (inducible nitric oxide synthase [iNOS] and tumor necrosis factor alpha [TNFα]) expression and enhanced M2 marker (Arginase 1, CD206 and IL1 receptor antagonist [IL1Ra]) expression in primary murine macrophages. The IL-4 secretion at the basal, non-LPS induced level was sufficient to suppress TNFα and enhance Arginase 1 at a lower level, but had no significant effects on iNOS, CD206 and IL1Ra expression. Finally, IL-4 secretion at basal or LPS-induced levels significantly suppressed osteogenic differentiation of MSCs. Our findings suggest that the IL-4 secreting MSCs driven by NF-κB sensing or constitutive active promoter have great potential for mitigating the effects of chronic inflammation and promoting earlier tissue regeneration.

Macrophage Polarization Contributes to the Anti-Tumoral Efficacy of Mesoporous Nanovectors Loaded with Albumin-Bound Paclitaxel

Therapies targeted to the immune system, such as immunotherapy, are currently shaping a new, rapidly developing branch of promising cancer treatments, offering the potential to change the prognosis of previously non-responding patients. Macrophages comprise the most abundant population of immune cells in the tumor microenvironment (TME) and can undergo differentiation into functional phenotypes depending on the local tissue environment. Based on these functional phenotypes, tumor-associated macrophages (TAMs) can either aid tumor progression (M2 phenotype) or inhibit it (M1 phenotype). Presence of M2 macrophages and a high ratio of M2/M1 macrophages in the TME are clinically associated with poor prognosis in many types of cancers. Herein, we evaluate the effect of macrophage phenotype on the transport and anti-cancer efficacy of albumin-bound paclitaxel (nAb-PTX) loaded into porous silicon multistage nanovectors (MSV). Studies in a coculture of breast cancer cells (3D-spheroid) with macrophages and in vivo models were conducted to evaluate the therapeutic efficacy of MSV-nAb-PTX as a function of macrophage phenotype. Association with MSV increased drug accumulation within the macrophages and the tumor spheroids, shifting the inflammation state of the TME toward the pro-inflammatory, anti-tumorigenic milieu. Additionally, the treatment increased macrophage motility toward cancer cells, promoting the active transport of therapeutic nanovectors into the tumor lesion. Consequently, apoptosis of cancer cells was increased and proliferation decreased in the MSV-nAb-PTX-treated group as compared to controls. The results also confirmed that the tested system shifts the macrophage differentiation toward an M1 phenotype, possessing an anti-proliferative effect toward the breast cancer cells. These factors were further incorporated into a mathematical model to help analyze the synergistic effect of the macrophage polarization state on the efficacy of MSV-nAb-PTX in alleviating hypovascularized tumor lesions. In conclusion, the ability of MSV-nAb-PTX to polarize TAM to the M1 phenotype, causing (1) enhanced penetration of the drug-carrying macrophages to the center of the tumor lesion and (2) increased toxicity to tumor cells may explain the increased anti-cancer efficacy of the system in comparison to nAb-PTX and other controls.

Regulation of RAW264.7 macrophage polarization on smooth and rough surface topographies by galectin-3

Recognition of topographical features induces phenotypic changes in macrophages although the receptors and signaling pathways are not completely characterized. As integrin molecules in focal adhesions/podosomes are in intimate contact with topography and topography modulates the NFkB pathway through cholesterol enriched raft-associated adhesive signaling structures we hypothesized that a cell-surface signaling complex comprised of galectin-3 together with its ligand CD98 and integrinβ1 is important for topography-directed lineage determination. This study used polished, sand blasted and acid etched (SLA) surfaces and two novel grooved topographies (G1 and G2) produced by anisotropic etching of Si <1 1 0> to evaluate the role of galectin-3 in macrophage polarization in RAW 264.7 macrophages, as determined by gene expression and morphology. In the presence of the galectin-3 inhibitor, lactose, the M2 marker (mannose receptor) was down-regulated while the M1 marker (iNOS) was up-regulated on smooth and rough surfaces. This skewing of phenotype suggests a role for galectin-3 in macrophage polarization towards the M2 phenotype. Additionally, we evaluated the role of PI3K on polarization using PI3K inhibitor LY294002. We found that the M2 marker was down-regulated on both PO (surface polished) and G1 surfaces implicating PI3K in lineage determination. We also found that surface topography altered cell morphology; macrophages had a larger area on G2 surfaces. Lactose treatment significantly reduced the cell area on all topographies suggesting that the galectin-3 is also involved in signaling complexes triggering the rearrangement of the actin cytoskeleton. © 2017 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 105A: 2499-2509, 2017.

2-Deoxy-d-Glucose Treatment Decreases Anti-inflammatory M2 Macrophage Polarization in Mice with Tumor and Allergic Airway Inflammation

As important effector cells in inflammation, macrophages can be functionally polarized into either inflammatory M1 or alternatively activated anti-inflammatory M2 phenotype depending on surroundings. The key roles of glycolysis in M1 macrophage polarization have been well defined. However, the relationship between glycolysis and M2 polarized macrophages is still poorly understood. Here, we report that 2-deoxy-d-glucose (2-DG), an inhibitor of the glycolytic pathway, markedly inhibited the expressions of Arg, Ym-1, Fizz1, and CD206 molecules, the hall-markers for M2 macrophages, during macrophages were stimulated with interleukin 4. The impacted M2 macrophage polarization by 2-DG is not due to cell death but caused by the impaired cellular glycolysis. Molecular mechanism studies indicate that the effect of 2-DG on M2 polarized macrophages relies on AMPK-Hif-1α-dependent pathways. Importantly, 2-DG treatment significantly decreases anti-inflammatory M2 macrophage polarization and prevents disease progression in a series of mouse models with chitin administration, tumor, and allergic airway inflammation. Thus, the identification of the master role of glycolysis in M2 macrophage polarization offers potential molecular targets for M2 macrophages-mediated diseases. 2-DG therapy may have beneficial effects in patients with tumors or allergic airway inflammation by its negative regulation on M2 macrophage polarization.

Relaxin abrogates renal interstitial fibrosis by regulating macrophage polarization via inhibition of Toll-like receptor 4 signaling

Renal fibrosis is a common feature of chronic kidney disease (CKD). To inhibit the CKD process, it is important to prevent renal fibrosis, though CKD remains incurable. Renal fibrosis can be inhibited by relaxin in several experimental models, but the mechanism of relaxin for antifibrotic potential is still not clear. And here we have studied the role of relaxin in macrophage polarization and renal inflammation after unilateral ureteral obstruction (UUO). Our results show that relaxin can downregulate the Toll-like receptor (TLR) 4 signaling, shift macrophage polarization toward the M2 phenotype and ameliorat renal fibrosis in the early stages of UUO. In vitro experiments, it has been confirmed that relaxin can downregulate the TLR4 signaling and induce the M2 macrophage transition. Furthermore, the transitional actions of macrophage phenotype induced by relaxin are significantly blocked by TAK-242, a TLR4 antagonist, in vitro experiments. Thus, there is a novel mechanism of relaxin for antifibrosis that shifts macrophage polarization toward the M2 phenotype via inhibition of TLR4 signaling.

M2-like macrophage polarization in high lactic acid-producing head and neck cancer

Reprogramming of glucose metabolism in tumor cells is referred to as the Warburg effect and results in increased lactic acid secretion into the tumor microenvironment. We have previously shown that lactic acid has important roles as a pro‐inflammatory and immunosuppressive mediator and promotes tumor progression. In this study, we examined the relationship between the lactic acid concentration and expression of LDHA and GLUT1, which are related to the Warburg effect, in human head and neck squamous cell carcinoma (HNSCC). Tumors expressing lower levels of LDHA and GLUT1 had a higher concentration of lactic acid than those with higher LDHA and GLUT1 expression. Lactic acid also suppressed the expression of LDHA and GLUT1 in vitro. We previously reported that lactic acid enhances expression of an M2 macrophage marker, ARG1, in murine macrophages. Therefore, we investigated the relationship between the lactic acid concentration and polarization of M2 macrophages in HNSCC by measuring the expression of M2 macrophage markers, CSF1R and CD163, normalized using a pan‐macrophage marker, CD68. Tumors with lower levels of CD68 showed a higher concentration of lactic acid, whereas those with higher levels of CSF1R showed a significantly higher concentration of lactic acid. A similar tendency was observed for CD163. These results suggest that tumor‐secreted lactic acid is linked to the reduction of macrophages in tumors and promotes induction of M2‐like macrophage polarization in human HNSCC.

Identification of the histone lysine demethylase KDM4A/JMJD2A as a novel epigenetic target in M1 macrophage polarization induced by oxidized LDL

Oxidized low density lipoprotein (oxLDL) induces macrophage activation, an event essential for atherosclerosis. Emerging evidence supports that epigenetic regulation plays important roles in macrophage activation and function. However, it remains unclear which epigenetic modulator is responsible for oxLDL-induced macrophage activation. Here, we identify for the first time KDM4A (JMJD2A) as an epigenetic modifying enzyme that controls oxLDL-induced pro-inflammatory M1 polarization of macrophages. OxLDL triggered M1 polarization of murine and human macrophages, characterized by expression of iNOS and robust production of inflammatory cytokines (e.g., TNF-α, MCP-1, IL-1β). In contrast, protein level of the M2 marker Arg1 was clearly decreased after treated with oxLDL. Notably, exposure to oxLDL resulted in markedly increased expression of KDM4A in macrophages. Functionally, shRNA knockdown of KDM4A significantly impaired M1 polarization and expression of inflammatory cytokines induced by oxLDL, accompanied by increased expression of Arg1 and VEGF. However, inhibition of KDM4A by shRNA or the pan-selective KDM inhibitor JIB-04 did not affect oxLDL-mediated activation of the NF-κB and hypoxia inducible factor (HIF) pathways, and vice versa. In addition, JIB-04 induced apoptosis of macrophages in a dose-dependent manner, an event attenuated by oxLDL. Together, these findings argue that KDM4A might represent a novel epigenetic modulator that acts to direct oxLDL-induced M1 polarization of macrophages, while its up-regulation is independent of NF-κB and HIF activation, two signals critical for pro-inflammatory activation of macrophages. They also suggest that KDM4A might serve as a potential target for epigenetic therapy in prevention and treatment of inflammatory diseases such as atherosclerosis.

Antimicrobial and Immunomodulatory Surface-Functionalized Electrospun Membranes for Bone Regeneration

Guided bone regeneration (GBR) is a surgical procedure utilizing occlusive membranes for providing space maintenance and enabling selective repopulation of the damaged area. While this technique is effective in regenerating bone, bacterial infiltration occurs frequently and can compromise the regenerative outcome. In this study, the authors describe the development and characterization of a GBR membrane made of medical grade polycaprolactone (mPCL) electrospun fibers with antibacterial and immunomodulatory properties. This is achieved by the immobilization of the antibiotic azithromycin into the membrane via a solvent evaporation technique leading to a sustained release of the drug over 14 d. In vitro testing shows that this controlled release of azithromycin is proficient at inhibiting the growth of Staphylococcus aureus for 14 d. Implantation of azithromycin loaded mPCL membrane in a rodent calvarial defect induces macrophage polarization toward the M2 phenotype after one week and results in significantly more bone regeneration eight weeks post-surgery. The results suggest that this antibacterial membrane should be effective at preventing infection and also impacts on the macrophage polarization enhancing bone regeneration. The drug loading technique developed in this study is simple, effective with a strong potential for clinical translation and can be applied to different types of scaffolds and implants for applications in craniofacial and orthopedics applications.

Targeting resolution of neuroinflammation after ischemic stroke with a lipoxin A4 analog: Protective mechanisms and long-term effects on neurological recovery

BACKGROUND

Resolution of inflammation is an emerging new strategy to reduce damage following ischemic stroke. Lipoxin A₄ (LXA ₄) is an anti-inflammatory, pro-resolution lipid mediator that reduces neuroinflammation in stroke. Since LXA ₄ is rapidly inactivated, potent analogs have been synthesized, including BML-111. We hypothesized that post-ischemic, intravenous treatment with BML-111 for 1 week would provide neuroprotection and reduce neurobehavioral deficits at 4 weeks after ischemic stroke in rats. Additionally, we investigated the potential protective mechanisms of BML-111 on the post-stroke molecular and cellular profile.

METHODS

A total of 133 male Sprague-Dawley rats were subjected to 90 min of transient middle cerebral artery occlusion (MCAO) and BML-111 administration was started at the time of reperfusion. Two methods of week-long BML-111 intravenous administration were tested: continuous infusion via ALZET ^® osmotic pumps (1.25 and 3.75 μg μl^-1 hr^-1), or freshly prepared daily single injections (0.3, 1, and 3 mg/kg). We report for the first time on the stability of BML-111 and characterized an optimal dose and a dosing schedule for the administration of BML-111.

RESULTS

One week of BML-111 intravenous injections did not reduce infarct size or improve behavioral deficits 4 weeks after ischemic stroke. However, post-ischemic treatment with BML-111 did elicit early protective effects as demonstrated by a significant reduction in infarct volume and improved sensorimotor function at 1 week after stroke. This protection was associated with reduced pro-inflammatory cytokine and chemokine levels, decreased M1 CD40+ macrophages, and increased alternatively activated, anti-inflammatory M2 microglia/macrophage cell populations in the post-ischemic brain.

CONCLUSION

These data suggest that targeting the endogenous LXA ₄ pathway could be a promising therapeutic strategy for the treatment of ischemic stroke. More work is necessary to determine whether a different dosing regimen or more stable LXA ₄ analogs could confer long-term protection.

The effect of engineered nanotopography of electrospun microfibers on fiber rigidity and macrophage cytokine production

Currently, it is unknown how the mechanical properties of electrospun fibers, and the presentation of surface nanotopography influence macrophage gene expression and protein production. By further elucidating how specific fiber properties (mechanical properties or surface properties) alter macrophage behavior, it may be possible to create electrospun fiber scaffolds capable of initiating unique cellular and tissue responses. In this study, we determined the elastic modulus and rigidity of fibers with varying topographies created by finely controlling humidity and including a non-solvent during electrospinning. In total,five fiber scaffold types were produced. Analysis of fiber physical properties demonstrated no change in fiber diameter amongst the five different fiber groups. However, the four different fibrous scaffolds with nanopits or divots each possessed different numbers of pits with different nanoscale dimensions. Unpolarized bone marrow derived murine macrophages (M0), macrophages polarized towards a pro-inflammatory phenotype (M1), or macrophages polarized towards anti-inflammatory phenotype (M2b) were placed onto each of the scaffolds and cytokine RNA expression and protein production were analyzed. Specific nanotopographies did not appreciably alter cytokine production from undifferentiated macrophages (M0) or anti-inflammatory macrophages (M2b), but a specific fiber (with many small pits) did increase IL-12 transcript and IL-12 protein production compared to fibers with small divots. When analyzing the mechanical properties between fibers with divots or with many small pits,divoted fibers possessed similar elastic moduli but different stiffness values. In total,we present techniques capable of creating unique electrospun fibers. These unique fibers have varying fiber mechanical characteristics and modestly modulate macrophage cytokine expression.

Pro-tumor activities of macrophages in the progression of melanoma

Macrophages are located in essentially all tissues due to their “janitor” function. Macrophages can exert either anti- or pro-tumor activities depending upon the specific tumor microenvironment they inhabit. Substantial evidence indicates that macrophages, owing to their plasticity, can be reeducated to adopt a protumoral phenotype within a tumor microenvironment through the help of growth factors in the microenvironment and intercellular interactions. As the lethality of malignant melanoma is due to its aggressive capacity for metastasis and resistance to therapy, considerable effort has gone toward treatment of metastatic melanoma. In the present review, we focus on the pro-tumor activities of macrophages in melanoma. Based upon the information presented in this review it is anticipated that new therapies will soon be developed that target pro-tumor activities of macrophages for use in the treatment of melanoma.

Promising landscape for regulating macrophage polarization: epigenetic viewpoint

Macrophages are critical myeloid cells with the hallmark of phenotypic heterogeneity and functional plasticity. Macrophages phenotypes are commonly described as classically-activated M1 and alternatively-activated M2 macrophages which play an essential role in the tissues homeostasis and diseases pathogenesis. Alternations of macrophage polarization and function states require precise regulation of target-gene expression. Emerging data demonstrate that epigenetic mechanisms and transcriptional factors are becoming increasingly appreciated in the orchestration of macrophage polarization in response to local environmental signals. This review is to focus on the advanced concepts of epigenetics changes involved with the macrophage polarization, including microRNAs, DNA methylation and histone modification, which are responsible for the altered cellular signaling and signature genes expression during M1 or M2 polarization. Eventually, the persistent investigation and understanding of epigenetic mechanisms in tissue macrophage polarization and function will enhance the potential to develop novel therapeutic targets for various diseases.

Defining the Balance between Regeneration and Pathological Ossification in Skeletal Muscle Following Traumatic Injury

Heterotopic ossification (HO) is characterized by the formation of bone at atypical sites. This type of ectopic bone formation is most prominent in skeletal muscle, most frequently resulting as a consequence of physical trauma and associated with aberrant tissue regeneration. The condition is debilitating, reducing a patient's range of motion and potentially causing severe pathologies resulting from nerve and vascular compression. Despite efforts to understand the pathological processes governing HO, there remains a lack of consensus regarding the micro-environmental conditions conducive to its formation, and attempting to define the balance between muscle regeneration and pathological ossification remains complex. The development of HO is thought to be related to a complex interplay between factors released both locally and systemically in response to trauma. It develops as skeletal muscle undergoes significant repair and regeneration, and is likely to result from the misdirected differentiation of endogenous or systemically derived progenitors in response to biochemical and/or environmental cues. The process can be sequentially delineated by the presence of inflammation, tissue breakdown, adipogenesis, hypoxia, neo-vasculogenesis, chondrogenesis and ossification. However, exactly how each of these stages contributes to the formation of HO is at present not well understood. Our previous review examined the cellular contribution to HO. Therefore, the principal aim of this review will be to comprehensively outline changes in the local tissue micro-environment following trauma, and identify how these changes can alter the balance between skeletal muscle regeneration and ectopic ossification. An understanding of the mechanisms governing this condition is required for the development and advancement of HO prophylaxis and treatment, and may even hold the key to unlocking novel methods for engineering hard tissues.

Regulators of mitochondrial quality control differ in subcutaneous fat of metabolically healthy and unhealthy obese monkeys

OBJECTIVE

Obesity exists with and without accompanying cardiometabolic disease, termed metabolically unhealthy obesity (MUO) and healthy obesity (MHO), respectively. Underlying differences in the ability of subcutaneous (SQ) fat to respond to nutrient excess are emerging as a key pathway. This study aimed to document the first spontaneous animal model of MHO and MUO and differences in SQ adipose tissue.

METHODS

Vervet monkeys (Chlorocebus aethiops; N = 171) were screened for metabolic syndrome. A subset of MHO and MUO monkeys (n = 6/group) had SQ fat biopsies collected for histological evaluations and examination of key mitochondrial proteins.

RESULTS

Obesity was seen in 20% of monkeys, and within this population, 31% were healthy, which mirrors human prevalence estimates. MUO monkeys had more than 60% lower adiponectin concentrations despite similar fat cell size, uncoupling protein 3, and activated macrophage abundance. However, alternatively activated/anti-inflammatory macrophages were 70% lower. Deficiencies of 50% or more in mitochondrial quality control regulators and selected mitochondrial fission and fusion markers were observed in the SQ fat of MUO monkeys despite comparable mitochondrial content.

CONCLUSIONS

A novel and translatable spontaneously obese animal model of MHO and MUO, occurring independently of dietary factors, was characterized. Differences in mitochondrial quality and inflammatory cell populations of subcutaneous fat may underpin divergent metabolic health.

Geraniin Inhibits LPS-Induced THP-1 Macrophages Switching to M1 Phenotype via SOCS1/NF-κB Pathway

M1 macrophage polarization is proved to promote inflammation in atherosclerosis process. In this study, we evaluated the inhibitory effect of geraniin, a bioactive polyphenolic compound, on the LPS-induced switch of THP-1 macrophages to M1 phenotype, and we propose a molecular basis for its action. Flow cytometry analysis indicated that geraniin significantly inhibited LPS-induced M1 macrophage polarization. Geraniin downregulated the protein and the mRNA level of typical cytokines of M1 macrophage, including tumor necrosis factor α (TNF-α) and interleukin 6 (IL-6), indicating that geraniin can suppress typical mediators of M1 macrophage at the transcriptional level. Moreover, geraniin inhibited LPS-induced reactive oxygen species (ROS) and nitric oxide (NO) production, as well as inducible nitric oxide synthase (iNOS) activity, in THP-1 macrophages. Furthermore, western blot analysis indicated that geraniin decreased both LPS-induced phosphorylation of NF-κB-p65 and NF-κB-p65 expression without affecting the level of IκB-α. This suggested that geraniin inhibited NF-κB, a transcription factor pivotal in the LPS-induced expression of pro-inflammatory genes and an important player in M1 macrophage polarization. Moreover, an electrophoretic mobility shift assay (EMSA) demonstrated that geraniin blocked the LPS-induced translocation of NF-κB to the nucleus. Moreover, we found that geraniin up-regulated the expression of SOCS1, an upstream regulator of NF-κB activation that can directly bind to NF-κB-p65 and downregulate it, thus inhibiting NF-κB activation. In conclusion, geraniin inhibits LPS-induced THP-1 macrophages switching to M1 phenotype through SOCS1/NF-κB pathway.

Bosutinib Therapy Ameliorates Lung Inflammation and Fibrosis in Experimental Silicosis

Silicosis is an occupational lung disease for which no effective therapy exists. We hypothesized that bosutinib, a tyrosine kinase inhibitor, might ameliorate inflammatory responses, attenuate pulmonary fibrosis, and thus improve lung function in experimental silicosis. For this purpose, we investigated the potential efficacy of bosutinib in the treatment of experimental silicosis induced in C57BL/6 mice by intratracheal administration of silica particles. After 15 days, once disease was established, animals were randomly assigned to receive DMSO or bosutinib (1 mg/kg/dose in 0.1 mL 1% DMSO) by oral gavage, twice daily for 14 days. On day 30, lung mechanics and morphometry, total and differential cell count in alveolar septa and granuloma, levels of interleukin (IL)-1β, tumor necrosis factor (TNF)-α, interferon (IFN)-γ, IL-4, transforming growth factor (TGF)-β, and vascular endothelial growth factor in lung homogenate, M1 and M2 macrophages, total leukocytes, and T cells in BALF, lymph nodes, and thymus, and collagen fiber content in alveolar septa and granuloma were analyzed. In a separate in vitro experiment, RAW264.7 macrophages were exposed to silica particles in the presence or absence of bosutinib. After 24 h, gene expressions of arginase-1, IL-10, IL-12, inducible nitric oxide synthase (iNOS), metalloproteinase (MMP)-9, tissue inhibitor of metalloproteinase (TIMP)-1, and caspase-3 were evaluated. In vivo, in silicotic animals, bosutinib, compared to DMSO, decreased: (1) fraction area of collapsed alveoli, (2) size and number of granulomas, and mononuclear cell granuloma infiltration; (3) IL-1β, TNF-α, IFN-γ, and TGF-β levels in lung homogenates, (4) collagen fiber content in lung parenchyma, and (5) viscoelastic pressure and static lung elastance. Bosutinib also reduced M1 cell counts while increasing M2 macrophage population in both lung parenchyma and granulomas. Total leukocyte, regulatory T, CD4⁺, and CD8⁺ cell counts in the lung-draining lymph nodes also decreased with bosutinib therapy without affecting thymus cellularity. In vitro, bosutinib led to a decrease in IL-12 and iNOS and increase in IL-10, arginase-1, MMP-9, and TIMP-1. In conclusion, in the current model of silicosis, bosutinib therapy yielded beneficial effects on lung inflammation and remodeling, therefore resulting in lung mechanics improvement. Bosutinib may hold promise for silicosis; however, further studies are required.

Devitalized Stem Cell Microsheets for Sustainable Release of Osteogenic and Vasculogenic Growth Factors and Regulation of Anti-Inflammatory Immune Response

The objective of this work was to investigate the effect of devitalized human mesenchymal stem cells (hMSCs) and endothelial colony-forming cells (ECFCs) seeded on mineralized nanofiber microsheets on protein release, osteogenesis, vasculogenesis, and macrophage polarization. Calcium phosphate nanocrystals were grown on the surface of aligned, functionalized nanofiber microsheets. The microsheets were seeded with hMSCs, ECFCs, or a mixture of hMSCs+ECFCs, cultured for cell attachment, differentiated to the osteogenic or vasculogenic lineage, and devitalized by lyophilization. The release kinetic of total protein, bone morphogenetic protein-2 (BMP2), and vascular endothelial growth factor (VEGF) from the devitalized microsheets was measured. Next, hMSCs and/or ECFCs were seeded on the devitalized cell microsheets and cultured in the absence of osteo-/vasculo-inductive factors to determine the effect of devitalized cell microsheets on hMSC/ECFC differentiation. Human macrophages were seeded on the microsheets to determine the effect of devitalized cells on macrophage polarization. Based on the results, devitalized undifferentiated hMSC and vasculogenic-differentiated ECFC microsheets had highest sustained release of BMP2 and VEGF, respectively. The devitalized hMSC microsheets did not affect M2 macrophage polarization while vascular-differentiated, devitalized ECFC microsheets did not affect M1 polarization. Both groups stimulated higher M2 macrophage polarization compared to M1.

What is new in the histogenesis of granulomatous skin diseases?

A granuloma is a form of inflammation, which predominantly consists of macrophages. It typically develops when the immune system attempts to enclose substances that are usually insoluble and cannot be eliminated to prevent the spread of these substances to the other body compartments. According to the source of the substances, granulomatous diseases can be divided into two groups: infectious and non-infectious. The mechanisms of infectious granuloma formation have been widely investigated because of its easy reproducibility in experimental models, both in vivo and in vitro. On the contrary, mechanisms of non-infectious granuloma formation have not been well investigated because of the difficulty to reproduce this formation in experimental models. In this article, we review our recent understanding of the histogenesis and pathogenesis of granuloma formation, confirmed from studies of infectious granulomas, and we present potential hypotheses of the histogenesis and pathogenesis of non-infectious granulomas based on clinical investigations.

Metformin prevents cancer metastasis by inhibiting M2-like polarization of tumor associated macrophages

Accumulated evidence suggests that M2-like polarized tumor associated macrophages (TAMs) plays an important role in cancer progression and metastasis, establishing TAMs, especially M2-like TAMs as an appealing target for therapy intervention. Here we found that metformin significantly suppressed IL-13 induced M2-like polarization of macrophages, as illustrated by reduced expression of CD206, down-regulation of M2 marker mRNAs, and inhibition of M2-like macrophages promoted migration of cancer cells and endothelial cells. Metformin triggered AMPKα1 activation in macrophage and silencing of AMPKα1 partially abrogated the inhibitory effect of metformin in IL-13 induced M2-like polarization. Administration of AICAR, another activator of AMPK, also blocked the M2-like polarization of macrophages. Metformin greatly reduced the number of metastases of Lewis lung cancer without affecting tumor growth. In tumor tissues, the percentage of M2-like macrophage was decreased and the area of pericyte-coated vessels was increased. Further, the anti-metastatic effect of metformin was abolished when the animals were treated with macrophages eliminating agent clodronate liposome. These findings suggest that metformin is able to block the M2-like polarization of macrophages partially through AMPKα1, which plays an important role in metformin inhibited metastasis of Lewis lung cancer.

Xenogeneic Bio-Root Prompts the Constructive Process Characterized by Macrophage Phenotype Polarization in Rodents and Nonhuman Primates

Tissue or organ regeneration using xenogeneic matrices is a promising approach to address the shortage of donor matrices for allotransplantation. Success of such approach has been demonstrated to correlate with macrophage-mediated fibrotic homeostasis and tissue remodeling. The previous studies have demonstrated that treated dentin matrix (TDM) could be a suitable bioactive substrate for allogeneic tooth root regeneration. This study constructed xenogeneic bioengineered tooth root (bio-root) via a combination of porcine TDM (pTDM) with allogeneic dental follicle cells (DFCs). Macrophage phenotypes are used to evaluate the remodeling process of xenogeneic bio-roots in vitro and in vivo. pTDM can facilitate odontoblast differentiation of human derived DFCs. Xenogeneic bio-roots in rat subcutaneous tissue prompt constructive response via M1 macrophage infiltration during early postimplantation stages and increase restorative M2 phenotype at later stages. After implantation of bio-roots into jaws of rhesus monkeys for six months, periodontal ligament-like fibers accompanied by macrophage polarization are observed, which are positive for COL-1, Periostin, βIII-tubulin and display such structures as fibroblasts and blood vessels. The reconstructed bio-root possesses biomechanical properties for the dissipation of masticatory forces. These results support that xenogeneic bio-root could maintain fibrotic homeostasis during remodeling process and highlight the potential application of xenogeneic matrices in regenerative medicine.

Long-Term Administration of Eicosapentaenoic Acid Improves Post-Myocardial Infarction Cardiac Remodeling in Mice by Regulating Macrophage Polarization

Background

Consumption of n‐3 fatty acids reduces the incidence of cardiovascular mortality in populations that consume diets rich in fish oil. Eicosapentaenoic acid (EPA) is an n‐3 fatty acid known to reduce the frequency of nonfatal coronary events; however, the frequency of mortality after myocardial infarction (MI) is not reduced. The aims of this study were to determine whether long‐term administration of EPA regulated cardiac remodeling after MI and to elucidate the underlying therapeutic mechanisms of EPA.

Methods and Results

C57BL/6J mice were divided into control (phosphate‐buffered saline–treated) and EPA‐treated groups. After 28 days of treatment, the mice were subjected to either sham surgery or MI by left anterior descending coronary artery ligation. Mortality due to MI or heart failure was significantly lower in the EPA‐treated mice than in the phosphate‐buffered saline–treated mice. However, the incidence of cardiac rupture was comparable between the EPA‐treated mice and the phosphate‐buffered saline–treated mice after MI. Echocardiographic tests indicated that EPA treatment attenuated post‐MI cardiac remodeling by preventing issues such as left ventricular systolic dysfunction and left ventricle dilatation 28 days after MI induction. Moreover, during the chronic remodeling phase, ie, 28 days after MI, flow cytometry demonstrated that EPA treatment significantly inhibited polarization toward proinflammatory M1 macrophages, but not anti‐inflammatory M2 macrophages, in the infarcted heart. Furthermore, EPA treatment attenuated fibrosis in the noninfarcted remote areas during the chronic phase.

Conclusions

Long‐term administration of EPA improved the prognosis of and attenuated chronic cardiac remodeling after MI by modulating the activation of proinflammatory M1 macrophages.

The response of human osteoblasts, epithelial cells, fibroblasts, macrophages and oral bacteria to nanostructured titanium surfaces: a systematic study

Nanotopography modification is a major focus of interest in current titanium surface design; however, the influence of the nanostructured surface on human cell/bacterium behavior has rarely been systematically evaluated. In this study, a homogeneous nanofiber structure was prepared on a titanium surface (Nano) by alkali-hydrothermal treatment, and the effects of this Nano surface on the behaviors of human MG-63 osteoblasts, human gingival epithelial cells (HGECs) and human gingival fibroblasts (HGFs) were evaluated in comparison with a smooth titanium surface (Smooth) by polishing and a micro-rough titanium surface (Micro) by sandblasting and acid etching. In addition, the impacts of these different surface morphologies on human THP-1 macrophage polarization and Streptococcus mutans attachment were also assessed. Our findings showed that the nanostructured surface enhanced the osteogenic activity of MG-63 cells (Nano=Micro>Smooth) at the same time that it improved the attachment of HGECs (Nano>Smooth>Micro) and HGFs (Nano=Micro>Smooth). Furthermore, the surface with nanotexture did not affect macrophage polarization (Nano=Micro=Smooth), but did reduce initial bacterial adhesion (Nano Collapse

Key Words

• antimicrobial effect
• macrophage polarization
• nanotopography
• osteogenic differentiation
• soft tissue barrier

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MESH Headings

• Cell Adhesion/drug effects
• Cell Line
• Cell Polarity/drug effects
• Epithelial Cells/cytology
• Epithelial Cells/drug effects
• Fibroblasts/cytology
• Fibroblasts/drug effects
• Gingiva/cytology
• Gingiva/drug effects
• Humans
• Macrophages/cytology
• Macrophages/drug effects
• Mouth/microbiology
• Nanostructures/chemistry
• Osteoblasts/cytology
• Streptococcus mutans/drug effects
• Surface Properties
• Titanium/chemistry
• Titanium/pharmacology

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Affiliation(s)

Xinchao Miao Department of Prosthodontics Oral Bioengineering Lab, Shanghai Research Institute of Stomatology, Ninth People’s Hospital Affiliated to Shanghai Jiao Tong University, School of Medicine, Shanghai Key Laboratory of Stomatology
Donghui Wang State Key Laboratory of High Performance Ceramics and Superfine Microstructure, Shanghai Institute of Ceramics, Chinese Academy of Sciences University of Chinese Academy of Sciences, Beijing
Lianyi Xu Department of Prosthodontics Oral Bioengineering Lab, Shanghai Research Institute of Stomatology, Ninth People’s Hospital Affiliated to Shanghai Jiao Tong University, School of Medicine, Shanghai Key Laboratory of Stomatology
Jie Wang Department of Prosthodontics Oral Bioengineering Lab, Shanghai Research Institute of Stomatology, Ninth People’s Hospital Affiliated to Shanghai Jiao Tong University, School of Medicine, Shanghai Key Laboratory of Stomatology
Deliang Zeng Department of Prosthodontics Oral Bioengineering Lab, Shanghai Research Institute of Stomatology, Ninth People’s Hospital Affiliated to Shanghai Jiao Tong University, School of Medicine, Shanghai Key Laboratory of Stomatology
Shuxian Lin Department of Prosthodontics Oral Bioengineering Lab, Shanghai Research Institute of Stomatology, Ninth People’s Hospital Affiliated to Shanghai Jiao Tong University, School of Medicine, Shanghai Key Laboratory of Stomatology
Cui Huang The State Key Laboratory Breeding Base of Basic Science of Stomatology (Hubei-MOST) & Key Laboratory of Oral Biomedicine Ministry of Education (KLOBM), School & Hospital of Stomatology, Wuhan University, Wuhan, Hubei, People’s Republic of China
Xuanyong Liu State Key Laboratory of High Performance Ceramics and Superfine Microstructure, Shanghai Institute of Ceramics, Chinese Academy of Sciences
Xinquan Jiang Department of Prosthodontics Oral Bioengineering Lab, Shanghai Research Institute of Stomatology, Ninth People’s Hospital Affiliated to Shanghai Jiao Tong University, School of Medicine, Shanghai Key Laboratory of Stomatology

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The shift of macrophages toward M1 phenotype promotes aortic valvular calcification

OBJECTIVE

The purpose of the present study was to comprehensively compare the phenotype profile of infiltrated macrophages in human noncalcified and calcific aortic valves, and to determine whether the shift of macrophage polarization modulates valvular calcification in vitro.

METHODS

Cell surface markers of macrophages and inflammatory cytokines expression in 90 cases of human noncalcified and calcific aortic valve leaflets were analyzed. The normal aortic valve interstitial cells were isolated and cultured in vitro. After incubation with nonconditioned medium and conditioned medium from unstimulated or lipopolysaccharide-stimulated U937 monocytes, valve interstitial cells were evaluated by osteogenic differentiation markers.

RESULTS

Infiltration of macrophages was enhanced in the calcific aortic valves, and M1 phenotype was the predominant macrophage subsets. In addition, both proinflammatory and anti-inflammatory cytokines were significantly upregulated in the calcific aortic valves. Furthermore, lipopolysaccharide-stimulated monocytes presented with increased expression of inducible nitric oxide synthase and high proportional CD11c-positive (M1) macrophages. Conditioned medium from unstimulated monocytes promoted the osteogenic differentiation of valve interstitial cells in vitro, as evidenced by increased markers such as bone morphogenetic protein 2, osteopontin, and alkaline phosphatase. Conditioned medium from M1 macrophages further enhanced valve interstitial cells calcification. Enzyme-linked immunosorbent assay showed that M1 phenotype macrophages secreted tumor necrosis factors α and interleukin 6, and neutralizing antibodies to these 2 proinflammatory cytokines attenuated induction of osteogenic differentiation and calcification by the conditioned media.

CONCLUSIONS

Both total numbers and polarization of macrophage influence the process of calcification in human aortic valve. The shift toward M1 phenotype might promote valve interstitial cell calcification.

Perturbed microRNA Expression by Mycobacterium tuberculosis Promotes Macrophage Polarization Leading to Pro-survival Foam Cell

Tuberculosis (TB) is one of the prevalent causes of death worldwide, with 95% of these deaths occurring in developing countries, like India. The causative agent, Mycobacterium tuberculosis (MTb) has the tenacious ability to circumvent the host’s immune system for its own advantage. Macrophages are one of the phagocytic cells that are central to immunity against MTb. These are highly plastic cells dependent on the milieu and can showcase M1/M2 polarization. M1 macrophages are bactericidal in action, but M2 macrophages are anti-inflammatory in their immune response. This computational study is an effort to elucidate the role of miRNAs that influences the survival of MTb in the macrophage. To identify the miRNAs against critical transcription factors, we selected only conserved hits from TargetScan database. Further, validation of these miRNAs was achieved using four databases viz. DIANA-microT, miRDB, miRanda-mirSVR, and miRNAMap. All miRNAs were identified through a conserved seed sequence against the 3′-UTR of transcription factors. This bioinformatics study found that miR-27a and miR-27b has a putative binding site at 3′-UTR of IRF4, and miR-302c against IRF5. miR-155, miR-132, and miR-455-5p are predicted microRNAs against suppressor of cytokine signaling transcription factors. Several other microRNAs, which have an affinity for critical transcription factors, are also predicted in this study. This MTb-associated modulation of microRNAs to modify the expression of the target gene(s) plays a critical role in TB pathogenesis. Other than M1/M2 plasticity, MTb has the ability to convert macrophage into foam cells that are rich in lipids and cholesterol. We have highlighted few microRNAs which overlap between M2/foam cell continuums. miR-155, miR-33, miR-27a, and miR-27b plays a dual role in deciding macrophage polarity and its conversion to foam cells. This study shows a glimpse of microRNAs which can be modulated by MTb not only to prevent its elimination but also to promote its survival.

Curcumin Attenuates Titanium Particle-Induced Inflammation by Regulating Macrophage Polarization In Vitro and In Vivo

Periprosthetic inflammatory osteolysis and subsequent aseptic loosening are commonly observed in total joint arthroplasty. Other than revision surgery, few approved treatments are available for this complication. Wear particle-induced inflammation and macrophage polarization state play critical roles in periprosthetic osteolysis. We investigated the effects of curcumin, a polyphenol extracted from Curcuma longa, on titanium (Ti) particle-induced inflammation and macrophage polarization in vitro using the murine cell line RAW 264.7 and in vivo using a murine air pouch model. The expression of specific macrophage markers was qualitatively analyzed by immunofluorescence (inducible nitric oxide synthase and CD206) and quantitatively analyzed by flow cytometry (CCR7 and CD206), representing M1 and M2 macrophages, respectively. Our results show that curcumin induced a higher percentage of M2 macrophages together with a higher concentration of anti-inflammatory cytokine IL-10, and a lower percentage of M1 macrophages with a lower concentration of pro-inflammatory cytokines (TNF-α and IL-6). The genes encoding CD86 (M1) and CD163 (M2), two additional markers, were shifted by curcumin toward an M2 phenotype. C57BL/J6 mice were injected with air and Ti particles to establish an air pouch model. Curcumin reduced cell infiltration in the pouch membrane and decreased membrane thickness. The analysis of exudates obtained from pouches demonstrated that the effects of curcumin on macrophage polarization and cytokine production were similar to those observed in vitro. These results prove that curcumin suppresses Ti particle-induced inflammation by regulating macrophage polarization. Thus, curcumin could be developed as a new therapeutic candidate for the prevention and treatment of inflammatory osteolysis and aseptic loosening.

Ornithine decarboxylase regulates M1 macrophage activation and mucosal inflammation via histone modifications

Macrophage activation is a critical step in host responses during bacterial infections. Ornithine decarboxylase (ODC), the rate-limiting enzyme in polyamine metabolism, has been well studied in epithelial cells and is known to have essential roles in many different cellular functions. However, its role in regulating macrophage function during bacterial infections is not well characterized. We demonstrate that macrophage-derived ODC is a critical regulator of M1 macrophage activation during both Helicobacter pylori and Citrobacter rodentium infection. Myeloid-specific Odc deletion significantly increased gastric and colonic inflammation, respectively, and enhanced M1 activation. Add-back of putrescine, the product of ODC, reversed the increased macrophage activation, indicating that ODC and putrescine are regulators of macrophage function. Odc-deficient macrophages had increased histone 3, lysine 4 (H3K4) monomethylation, and H3K9 acetylation, accompanied by decreased H3K9 di/trimethylation both in vivo and ex vivo in primary macrophages. These alterations in chromatin structure directly resulted in up-regulated gene transcription, especially M1 gene expression. Thus, ODC in macrophages tempers antimicrobial, M1 macrophage responses during bacterial infections through histone modifications and altered euchromatin formation, leading to the persistence and pathogenesis of these organisms.

Glucose regulates the intrinsic inflammatory response of the heart to surgically induced hypothermic ischemic arrest and reperfusion

We investigated the isolated working rat heart as a model to study early transcriptional remodeling induced in the setting of open heart surgery and stress hyperglycemia. Hearts of male Sprague Dawley rats were cold-arrested in Krebs-Henseleit buffer and subjected to 60 min normothermic reperfusion in the working mode with buffer supplemented with noncarbohydrate substrates plus glucose (25 mM) or mannitol (25 mM; osmotic control). Gene expression profiles were determined by microarray analysis and compared with those of nonperfused hearts. Perfused hearts displayed a transcriptional signature independent from the presence of glucose showing a more than twofold increase in expression of 71 genes connected to inflammation, cell proliferation, and apoptosis. These transcriptional alterations were very similar to the ones taking place in the hearts of open heart surgery patients. Prominent among those alterations was the upregulation of the three master regulators of metabolic reprogramming, MYC, NR4A1, and NR4A2. Targeted pathway analysis revealed an upregulation of metabolic processes associated with the proliferation and activation of macrophages and fibroblasts. Glucose potentiated the upregulation of a subset of genes associated with polarization of tissue reparative M2-like macrophages, an effect that was lost in perfused hearts from rats rendered insulin resistant by high-sucrose feeding. The results expose the heart as a significant source of proinflammatory mediators released in response to stress associated with cardiac surgery with cardiopulmonary bypass, and suggest a major role for glucose as a signal in the determination of resident cardiac macrophage polarization.

Inflammation and macrophage polarization in cutaneous melanoma: Histopathological and immunohistochemical study

Tumor-associated macrophages (TAMs) are considered to affect tumor growth and progression. Macrophages can be classified into two states of polarized activation, namely classically activated M1 macrophages and alternatively activated M2 macrophages. The dynamic balance between TAMs and tumor cells has an important impact on tumor homeostasis and progression. The aim of this study was to characterize the phenotype of TAMs present in different subtypes of superficial spreading cutaneous melanoma and their relationship with the lymphocytic infiltrate in order to identify new histopathological tools for melanoma prognosis and suitable targets for melanoma therapy. We selected four groups of patients with malignant melanoma in order to analyze the profile of polarized macrophage activation using immunohistochemical methods. Histopathological analysis showed that the macrophage polarization state appears to be more related to the lymphocytic infiltrate than to the thickness of the lesions. Further studies are necessary to increase understanding of the immunopathological dynamic of melanoma that may be modulated by future targeted immunotherapies.

Reduced angiogenic gene expression in morbillivirus-triggered oncolysis in a translational model for histiocytic sarcoma

Histiocytic sarcoma represents a rare malignant tumour with a short survival time, indicating the need of novel treatment strategies including oncolytic virotherapy. The underlying molecular mechanisms of viral oncolysis are largely unknown. As cancer in companion animals shares striking similarities with human counterparts, we chose a permanent canine histiocytic sarcoma cell line (DH82 cells) to identify global transcriptome changes following infection with canine distemper virus (CDV), a paramyxovirus closely related to human measles virus. Microarray analysis identified 3054 differentially expressed probe sets (DEPs), encoding for 892 up‐ and 869 down‐regulated unique canine genes, respectively, in DH82 cells persistently infected with the vaccine strain Onderstepoort of CDV (DH82‐Ond‐pi), compared to non‐infected DH82 cells. Up‐regulated genes were predominantly related to immune processes, as demonstrated by functional enrichment analysis. Moreover, there was substantial enrichment of genes characteristic for classically activated M1 and alternatively activated M2 macrophages in DH82‐Ond‐pi; however, significant polarization into either of both categories was lacking. ‘Angiogenesis’ was the dominant enriched functional term for the down‐regulated genes, highlighting decreased blood vessel generation as a potential mechanism of paramyxovirus‐induced oncolysis in DH82 cells. The anti‐angiogenic effect of infection was verified by immunohistochemistry, which revealed a lower blood vessel density in an in vivo mouse model, xenotransplanted with DH82‐Ond‐pi, compared to mice transplanted with non‐infected DH82 cells. Reduction in angiogenesis appears to be an important oncolytic mechanism of CDV in DH82 cells, suggesting that similar mechanisms might account for human histiocytic sarcoma and maybe other tumours in conjunction with measles virus.

Rediscovering peritoneal macrophages in a murine endometriosis model

STUDY QUESTION

What are the features of peritoneal macrophage subgroups and T helper cells in the development of murine endometriosis?

SUMMARY ANSWER

During the development of endometriosis in a murine model, large peritoneal macrophages (LPMs) and small peritoneal macrophages (SPMs) are polarized into M1 and M2 cells, respectively, and the proportions of T helper (Th) 1, Th17 and T regulatory (T_reg) cells are increased.

WHAT IS KNOWN ALREADY

Numerous studies investigating the etiology and pathogenesis of endometriosis have focused on the polarization states of peritoneal macrophages in endometriosis models and patients, but the results are inconclusive. Further studies indicate that peritoneal macrophages are composed of two distinct subsets: LPMs and SPMs, although their roles in endometriosis are unknown.

STUDY DESIGN, SIZE, DURATION

This study involves a prospective and randomized experiment. Fifty C57BL/6 female mice were randomly allocated to five control and five experimental groups (n = 5/group) according to the presence or absence of transplantation. The transplant periods are 0.25, 3, 14, 28 and 42 days.

PARTICIPANTS/MATERIALS, SETTING, METHODS

C57BL/6 mice were utilized to establish an endometriosis model by i.p. injection of allogeneic endometrial segments. Dynamic changes of peritoneal macrophage subsets and polarization profiles were evaluated by flow cytometry (FCM). Macrophage morphology and density were assessed by cell counting under a microscope. Dynamic changes of Th1, Th2, Th17 and T_reg cells were estimated by FCM.

MAIN RESULTS AND THE ROLE OF CHANCE

Peritoneal macrophages are composed of two distinct subsets: LPMs and SPMs. The proportion of SPMs increased immediately after peritoneal injection of endometrial tissues, whereas LPMs showed an opposite trend. Peritoneal macrophages differentiated into both M1 and M2 macrophages. The bidirectional polarization of macrophages was caused by the inverse trends of polarization of LPMs and SPMs. Consistently, the proportions of Th1, Th17 and T_reg cells were all increased in mice with endometriosis.

LARGE SCALE DATA

N/A.

LIMITATIONS, REASONS FOR CAUTION

In this study, detection was only performed in a murine endometriosis model. Clinical data and more intervention experiments are required in understanding the roles of LPMs and SPMs in endometriosis.

WIDER IMPLICATIONS OF THE FINDINGS

The dramatic changes of LPMs and SPMs in proportion and polarization profiles clarified the varying differentiation states of peritoneal macrophages. In addition, LPMs and SPMs may play different roles in the pathogenesis of endometriosis in different stages of endometriosis. Therefore, the new classification should be included in future relevant basic and clinical studies on endometriosis.

STUDY FUNDING/COMPETING INTERESTS

This research was supported totally by grant 81270671 from the National Natural Science Foundation of China. The authors report no conflict of interest.

Immuno-Informed 3D Silk Biomaterials for Tailoring Biological Responses

Macrophages, the key players in immunoregulation, are actively involved in tissue remodelling and vascularization. Recent advances in tissue engineering and regenerative medicine illustrate the importance of "immuno-informed" biomaterials to regulate the microenvironment of biomedical implants. In the current study, silk-based 3D hydrogels were utilized to regulate cytokine delivery for macrophage, a type of immune cell, differentiation and polarization. Three different hydrogel variants, silk-poly(ethylene glycol) (PEG) (SP), silk-horseradish peroxidase (HRP) (SH) and silk-sonicated (SS) hydrogels were studied. Hydrogels were loaded with the M1 and M2 polarizing cytokines interferon-γ (IFN-γ) and interleukin-4 (IL-4), respectively. Functional cytokine release and macrophage polarization studies were conducted using three cytokine exposure approaches: only cytokine encapsulation (macrophage in culture well), only macrophage encapsulation (cytokine in culture media) and cytokine with macrophage encapsulation. The extent of macrophage polarization by cytokine-eluting and macrophage-encapsulating hydrogels was investigated using gene expression analysis for C-C chemokine receptor 7 (CCR7), Interleukin-1 beta (IL-1β), cluster of differentiation 206 (CD206) and cluster of differentiation 209 (CD209). The released cytokines polarized macrophages from an M0 phenotype to an M1/M2 phenotype. Also, lineage committed M1/M2 macrophages could be "switched" to their M2/M1 counterparts (M1-to-M2 or M2-to-M1 transition) exhibiting their well-established plasticity. When macrophages were encapsulated in hydrogels, polarization could be induced to the lineage committed M1 or M2 phenotypes either in polarizing media or when coencapsulated with cytokines. Through this study, silk hydrogels demonstrated utility as a novel system for focal delivery of cytokines and macrophages as "immuno-informed" 3D silk-biomaterials.

Sphingosine-1 Phosphate: A New Modulator of Immune Plasticity in the Tumor Microenvironment

In the last 15 years, increasing evidences demonstrate a strong link between sphingosine-1-phosphate (S1P) and both normal physiology and progression of different diseases, including cancer and inflammation. Indeed, numerous studies show that tissue levels of this sphingolipid metabolite are augmented in many cancers, affecting survival, proliferation, angiogenesis, and metastatic spread. Recent insights into the possible role of S1P as a therapeutic target has attracted enormous attention and opened new opportunities in this evolving field. In this review, we will focus on the role of S1P in cancer, with particular emphasis in new developments that highlight the many functions of this sphingolipid in the tumor microenvironment. We will discuss how S1P modulates phenotypic plasticity of macrophages and mast cells, tumor-induced immune evasion, differentiation and survival of immune cells in the tumor milieu, interaction between cancer and stromal cells, and hypoxic response.

IL-4/IL-13-mediated polarization of renal macrophages/dendritic cells to an M2a phenotype is essential for recovery from acute kidney injury

Cytokines IL-4 and IL-13 play important roles in polarization of macrophages/dendritic cells to an M2 phenotype, which is important for recovery from acute kidney injury. Both IL-4 and IL-13 activate JAK3/STAT6 signaling. In mice with diphtheria toxin receptor expression in proximal tubules (selective injury model), a relatively selective JAK3 inhibitor, tofacitinib, led to more severe kidney injury, delayed recovery from acute kidney injury, increased inflammatory M1 phenotype markers and decreased reparative M2 phenotype markers of macrophages/dendritic cells, and development of more severe renal fibrosis after diphtheria toxin administration. Similarly, there was delayed recovery and increased tubulointerstitial fibrosis in these diphtheria toxin-treated mice following tamoxifen-induced deletion of both IL-4 and IL-13, with increased levels of M1 and decreased levels of M2 markers in the macrophages/dendritic cells. Furthermore, deletion of IL-4 and IL-13 led to a decrease of tissue reparative M2a phenotype markers but had no effect on anti-inflammatory M2c phenotype markers. Deletion of IL-4 and IL-13 also inhibited recovery from ischemia-reperfusion injury in association with increased M1 and decreased M2 markers and promoted subsequent tubulointerstitial fibrosis. Thus, IL-4 and IL-13 are required to effectively polarize macrophages/dendritic cells to an M2a phenotype and to promote recovery from acute kidney injury.

Endothelial cell-derived angiopoietin-2 is a therapeutic target in treatment-naive and bevacizumab-resistant glioblastoma

Glioblastoma multiforme (GBM) is treated by surgical resection followed by radiochemotherapy. Bevacizumab is commonly deployed for anti‐angiogenic therapy of recurrent GBM; however, innate immune cells have been identified as instigators of resistance to bevacizumab treatment. We identified angiopoietin‐2 (Ang‐2) as a potential target in both naive and bevacizumab‐treated glioblastoma. Ang‐2 expression was absent in normal human brain endothelium, while the highest Ang‐2 levels were observed in bevacizumab‐treated GBM. In a murine GBM model, VEGF blockade resulted in endothelial upregulation of Ang‐2, whereas the combined inhibition of VEGF and Ang‐2 leads to extended survival, decreased vascular permeability, depletion of tumor‐associated macrophages, improved pericyte coverage, and increased numbers of intratumoral T lymphocytes. CD206⁺ (M2‐like) macrophages were identified as potential novel targets following anti‐angiogenic therapy. Our findings imply a novel role for endothelial cells in therapy resistance and identify endothelial cell/myeloid cell crosstalk mediated by Ang‐2 as a potential resistance mechanism. Therefore, combining VEGF blockade with inhibition of Ang‐2 may potentially overcome resistance to bevacizumab therapy.

Regulation of the IL-10-driven macrophage phenotype under incoherent stimuli

Macrophages are ubiquitous innate immune cells that play a central role in health and disease by adopting distinct phenotypes, which are broadly divided into classical inflammatory responses and alternative responses that promote immune suppression and wound healing. Although macrophages are attractive therapeutic targets, incomplete understanding of this functional choice limits clinical manipulation. While individual stimuli, pathways, and genes involved in macrophage functional responses have been identified, how macrophages evaluate complex in vivo milieus comprising multiple divergent stimuli remains poorly understood. Here, we used combinations of "incoherent" stimuli-those that individually promote distinct macrophage phenotypes-to elucidate how the immunosuppressive, IL-10-driven macrophage phenotype is induced, maintained, and modulated under such combinatorial stimuli. The IL-10-induced immunosuppressive phenotype was largely insensitive to co-administered IL-12, which has been reported to modulate macrophage phenotype, but maintaining the immunosuppressive phenotype required sustained exposure to IL-10. Our data implicate the intracellular protein, BCL3, as a key mediator of the IL-10-driven phenotype. Notably, co-administration of IFN-γ disrupted an IL-10-mediated positive feedback loop that may reinforce the immunosuppressive phenotype. This novel combinatorial perturbation approach thus generated new insights into macrophage decision making and local immune network function.

MicroRNA-720 suppresses M2 macrophage polarization by targeting GATA3

Macrophages are highly plastic cells with the ability to differentiate into both M1- and M2-polarized phenotypes. As a distinct M2-polarized population, tumour-associated macrophages (TAMs) promote tumorigenesis owing to their pro-angiogenic and immune-suppressive functions in tumour microenvironment. In the present study, we found that the microRNA-720 (miR-720) was down-regulated in TAMs isolated from breast carcinomas and M2-polarization macrophages. Overexpression of miR-720 attenuated M2 phenotype expression and thus inhibited M2 polarization. We further identified GATA binding protein 3 (GATA3), a transcriptional factor that plays an important role in M2 macrophage polarization, was the downstream target of miR-720. Ectopic expression of GATA3 restored the M2 phenotype in miR-720 overexpressed macrophages. Importantly, overexpression of miR-720 inhibited pro-migration behaviour and phagocytic ability of M2-polarized macrophages. Thus, our data suggest that miR-720 plays an important role in regulating M2 macrophage polarization and function.

Tim-3 promotes tumor-promoting M2 macrophage polarization by binding to STAT1 and suppressing the STAT1-miR-155 signaling axis

T cell Ig mucin-3 (Tim-3), an immune checkpoint inhibitor, shows therapeutic potential. However, the molecular mechanism by which Tim-3 regulates immune responses remains to be determined. In particular, very little is known about how Tim-3 works in innate immune cells. Here, we demonstrated that Tim-3 is involved in the development of tumor-promoting M2 macrophages in colon cancer. Manipulation of the Tim-3 pathway significantly affected the polarization status of intestinal macrophages and the progression of colon cancer. The Tim-3 signaling pathway in macrophages was explored using microarray, co-immunoprecipitation, gene mutation, and high-content analysis. For the first time, we demonstrated that Tim-3 polarizes macrophages by directly binding to STAT1 via residue Y256 and Y263 in its intracellular tail and inhibiting the STAT1-miR-155-SOCS1 signaling axis. We also identified a new signaling adaptor of Tim-3 in macrophages, and, by modulating the Tim-3 pathway, demonstrated the feasibility of altering macrophage polarization as a potential tool for treating this kind of disease.

Contact-dependent carcinoma aggregate dispersion by M2a macrophages via ICAM-1 and β2 integrin interactions

Tumor-associated macrophages (TAMs) can constitute up to 50% of the tumor mass and have strong implications in tumor progression and metastasis. Macrophages are plastic and can polarize to various subtypes that differ in terms of surface receptor expression as well as cytokine and chemokine production and effector function. Conventionally, macrophages are grouped into two major subtypes: the classically activated M1 macrophages and the alternatively activated M2 macrophages. M1 macrophages are pro-inflammatory, promote T helper (Th) 1 responses, and show tumoricidal activity, whereas M2 macrophages contribute to tissue repair and promote Th2 responses. Herein, we present a microfluidic system integrating tumor cell aggregates and subtypes of human monocyte-derived macrophages in a three-dimensional hydrogel scaffold, in close co-culture with an endothelial monolayer to create an in vitro tumor microenvironment. This platform was utilized to study the role of individual subtypes of macrophages (M0, M1, M2a, M2b and M2c) in human lung adenocarcinoma (A549) aggregate dispersion, as a representation of epithelial-mesenchymal transition (EMT). A significant difference was observed when M2a macrophages were in direct contact with or separated from A549 aggregates, suggesting a possible mechanism for proximity-induced, contact-dependent dissemination via ICAM-1 and integrin β2 interactions. Indeed, M2a macrophages tended to infiltrate and release cells from carcinoma cell aggregates. These findings may help in the development of immunotherapies based on enhancing the tumor-suppressive properties of TAMs.

Paracoccin Induces M1 Polarization of Macrophages via Interaction with TLR4

The fungal human pathogen Paracoccidioides brasiliensis contains paracoccin (PCN), a multi-domain protein that has lectin and N-acetyl-glucosaminidase activities, which account for its effects on the growth and morphogenesis of the fungus and on the activation of host macrophages through its interaction with TLR N-glycans. With the purpose of detailing the knowledge on the effects of PCN on macrophages, we used recombinant PCN expressed in Pichia pastoris (p-rPCN) to stimulate isolated murine peritoneal macrophages. The activation of these cells manifested through the release of high levels of inflammatory mediators, such as nitric oxide, TNF-α, IL-12p40, and IL-6. Furthermore, peritoneal macrophages stimulated with p-rPCN increased the relative expression of STAT1, SOCS3, and iNOS2 mRNA (M1 polarization markers). However, the expression of Arginase-1, Ym-1, and FIZZ1 (M2 polarization markers) remained at basal levels. Interestingly, the observed M1 macrophages’ polarization triggered by p-rPCN was abolished in cells obtained from knockout Toll-like receptor-4 mice. In this case, the p-rPCN-induced production of pro-inflammatory mediators was blocked too. These results demonstrate that the classical activation of macrophages induced by paracoccin depends on TLR4. Taken together, the results of our study indicate that paracoccin acts as a TLR agonist able to modulate immunity and exerts biological activities that favor its applicability as an immunotherapeutic agent to combat systemic fungal infections.

A phased strategy to differentiate human CD14+monocytes into classically and alternatively activated macrophages and dendritic cells

There are currently several in vitro strategies to differentiate human CD14(+) monocytes isolated from peripheral blood mononuclear cells (PBMCs) into the M1 or M2 macrophage cell types. Each cell type is then verified using flow cytometric analysis of cell-surface markers. Human CD14(+) monocytes have the potential to differentiate into M1 and M2 macrophages, both of which demonstrate varying degrees of cell-surface antigen overlap. Using multiple surface markers with current macrophage polarization protocols, our data reveal several limitations of currently used methods, such as highly ambiguous cell types that possess cell-surface marker overlap and functional similarities. Utilizing interleukin-6 (IL-6) and two phases of cytokine exposure, we have developed a protocol to differentiate human monocytes into M1, M2, or dendritic cells (DCs) with greater efficiency and fidelity relative to macrophages and DCs that are produced by commonly used methods. This is achieved via alterations in cytokine composition, dosing, and incubation times, as well as improvements in verification methodology. Our method reliably reproduces human in vitro monocyte-derived DCs and macrophage models that will aid in better defining and understanding innate and adaptive immunity, as well as pathologic states.

Colonic macrophage polarization in homeostasis, inflammation, and cancer

Our review focuses on the colonic macrophage, a monocyte-derived, tissue-resident macrophage, and the role it plays in health and disease, specifically in inflammatory conditions such as inflammatory bowel disease and cancer of the colon and rectum. We give special emphasis to macrophage polarization, or phenotype, in these different states. We focus on macrophages because they are one of the most numerous leukocytes in the colon, and because they normally contribute to homeostasis through an anti-inflammatory phenotype. However, in conditions such as inflammatory bowel disease, proinflammatory macrophages are increased in the colon and have been linked to disease severity and progression. In colorectal cancer, tumor cells may employ anti-inflammatory macrophages to promote tumor growth and dissemination, whereas proinflammatory macrophages may antagonize tumor growth. Given the key roles that this cell type plays in homeostasis, inflammation, and cancer, the colonic macrophage is an intriguing therapeutic target. As such, potential macrophage-targeting strategies are discussed.

CD11b(+) Mononuclear Cells Mitigate Hyperoxia-Induced Lung Injury in Neonatal Mice

Bronchopulmonary dysplasia (BPD) is a common consequence of life-saving interventions for infants born with immature lungs. Resident tissue myeloid cells regulate lung pathology, but their role in BPD is poorly understood. To determine the role of lung interstitial myeloid cells in neonatal responses to lung injury, we exposed newborn mice to hyperoxia, a neonatal mouse lung injury model with features of human BPD. In newborn mice raised in normoxia, we identified a CD45(+) F4/80(+) CD11b(+), Ly6G(lo-int) CD71(+) population of cells in lungs of neonatal mice present in significantly greater percentages than in adult mice. In response to hyperoxia, surface marker and gene expression in whole lung macrophages/monocytes was biased to an alternatively activated phenotype. Partial depletion of these CD11b(+) mononuclear cells using CD11b-diphtheria toxin (DT) receptor transgenic mice resulted in 60% mortality by 40 hours of hyperoxia exposure with more severe lung injury, perivascular edema, and alveolar hemorrhage compared with DT-treated CD11b-DT receptor-negative controls, which displayed no mortality. These results identify an antiinflammatory population of CD11b(+) mononuclear cells that are protective in hyperoxia-induced neonatal lung injury in mice, and suggest that enhancing their beneficial functions may be a treatment strategy in infants at risk for BPD.

Update on the role of alternatively activated macrophages in asthma

Lung macrophages link innate and adaptive immune responses during allergic airway inflammatory responses. Alveolar macrophages (AMs) and interstitial macrophages are two different phenotypes that differentially exert immunological function under physiological and pathological conditions. Exposure to pathogen induces polarization of AM cells into classically activated macrophages (M1 cells) and alternatively activated macrophages (M2 cells). M1 cells dominantly express proinflammatory cytokines such as TNF-α and IL-1 β and induce lung inflammation and tissue damage. M2 cells are further divided into M2a and M2c subsets. M2a cells dominantly produce allergic cytokines IL-4 and IL-13, but M2c cells dominantly produce anti-inflammatory cytokine IL-10. M2a and M2c cells are differently involved in initiation, inflammation resolution, and tissue remodeling in the different stages of asthma. Microenvironment dynamically influences polarization of AM cells. Cytokines, chemokines, and immune-regulatory cells interplay and affect the balance between the polarization of M1 and M2 cells, subsequently influencing disease progression. Thus, modulation of AM phenotypes through molecular intervention has therapeutic potential in the treatment of asthma and other allergic inflammatory diseases. This review updated recent advances in polarization and functional specialization of these macrophage subtypes with emphasis on modulation of polarization of M2 cells in asthma of human subjects and animal models.

MiR-16 regulates mouse peritoneal macrophage polarization and affects T-cell activation

MiR‐16 is a tumour suppressor that is down‐regulated in certain human cancers. However, little is known on its activity in other cell types. In this study, we examined the biological significance and underlying mechanisms of miR‐16 on macrophage polarization and subsequent T‐cell activation. Mouse peritoneal macrophages were isolated and induced to undergo either M1 polarization with 100 ng/ml of interferon‐γ and 20 ng/ml of lipopolysaccharide, or M2 polarization with 20 ng/ml of interleukin (IL)‐4. The identity of polarized macrophages was determined by profiling cell‐surface markers by flow cytometry and cytokine production by ELISA. Macrophages were infected with lentivirus‐expressing miR‐16 to assess the effects of miR‐16. Effects on macrophage–T cell interactions were analysed by co‐culturing purified CD4⁺ T cells with miR‐16‐expressing peritoneal macrophages, and measuring activation marker CD69 by flow cytometry and cytokine secretion by ELISA. Bioinformatics analysis was applied to search for potential miR‐16 targets and understand its underlying mechanisms. MiR‐16‐induced M1 differentiation of mouse peritoneal macrophages from either the basal M0‐ or M2‐polarized state is indicated by the significant up‐regulation of M1 marker CD16/32, repression of M2 marker CD206 and Dectin‐1, and increased secretion of M1 cytokine IL‐12 and nitric oxide. Consistently, miR‐16‐expressing macrophages stimulate the activation of purified CD4⁺ T cells. Mechanistically, miR‐16 significantly down‐regulates the expression of PD‐L1, a critical immune suppressor that controls macrophage–T cell interaction and T‐cell activation. MiR‐16 plays an important role in shifting macrophage polarization from M2 to M1 status, and functionally activating CD4⁺ T cells. This effect is potentially mediated through the down‐regulation of immune suppressor PD‐L1.

Dynamic changes of mononuclear phagocytes in circulating, pulmonary alveolar and interstitial compartments in a mouse model of experimental silicosis

CONTEXT

Silicosis is a devastating, irreversible lung fibrosis condition exposed to crystalline silica. The mononuclear phagocyte system plays an important role in the pathogenesis of silicosis.

OBJECTIVE

The present study was aimed to explore the dynamic changes of mononuclear phagocytes in circulating, pulmonary alveolar and interstitial compartments in experimental silicosis model.

MATERIALS AND METHODS

A mouse model of lung fibrosis was developed with crystalline silica particles (2 mg/40 μL via oropharyngeal instillation) using male C57BL/6 mice, and were killed on days 1, 3, 7, 14, and 28. The lung inflammation and fibrosis was investigated using hematoxylin-eosin staining and bronchoalveolar lavage fluid (BALF) analysis, Masson's trichrome staining, and immunofluorescence. Circulating monocyte subsets (Ly6C(hi) and Ly6C(lo)), polarization state of BALF-derived alveolar macrophages (AMϕ) and lung interstitial macrophages (IMϕ, derived from enzymatically digested lung tissue) were analyzed by flow cytometry.

RESULTS

The percentage of Ly6C(hi) monocytes significantly increased on day 1 after silica exposure, which reached the peak level from day 7 till day 28. Moreover, M2 (alternative activation) AMϕ (PI - CD64 + CD206+) was dramatically and progressively increased from day 1 to day 28. A parallel increase in IMϕ with M2 polarization (PI-CD64 + CD11b + CD206+) was also observed from day 1 to day 28.

CONCLUSION

Our data demonstrate a dynamic view of mononuclear phagocyte change in three compartments after silica challenge, which highlights the remodeling of mononuclear phagocyte system as a potential therapeutic target for silicosis.

Effects of diesel exhaust particles on macrophage polarization

BACKGROUND

Exposure to diesel exhaust particles (DEP) has long been associated with increased cardiovascular morbidity and mortality. The development of DEP toxicity seems to be linked to inflammation in which macrophages play a critical role. Macrophages can be polarized into proinflammatory M1 or anti-inflammatory M2 macrophages. The aim of this study was to identify the role of inflammation in DEP-induced toxicity by assessing the effects of DEP on macrophage polarization.

METHODS

Monocyte-derived macrophages (Mϕ) were stimulated with interferon γ and lipopolysaccharide or interleukin (IL)-4 to obtain M1 and M2 subtypes, respectively. To test the polarization capacity of DEP, Mϕ cells were exposed to DEP and compared to Mϕ, M1, and M2. We also studied the effects of DEP on already-polarized M1 or M2. The M1 markers assessed were tumor necrosis factor α (TNF-α) and IL-1β, while the M2 markers were the mannose receptor C type 1 (MRC-1) and transglutaminase 2 (TGM2).

RESULTS

Western blots revealed a 31 kDa band corresponding to pro-IL-1β, but only in M1-polarized macrophages. In M1, we also observed an upregulation of TNF-α messenger RNA (mRNA) expression. MRC-1 and TGM2 mRNA expression were only significantly enhanced in M2. DEP had no effect on any of the M1/M2 markers assessed. Moreover, DEP were not able to modify the phenotype of already-polarized M1 or M2.

CONCLUSION

Mϕ incubation with DEP did not have any effect on macrophage polarization, at least on the markers assessed in this study, namely, TNF-α/IL-1β for M1, and MRC-1/TGM2 for M2. Hence, these data argue against an important role of inflammation in DEP-induced vascular toxicity.

Shp2 Deficiency Impairs the Inflammatory Response Against Haemophilus influenzae by Regulating Macrophage Polarization

Macrophages can polarize and differentiate to regulate initiation, development, and cessation of inflammation during pulmonary infection with nontypeable Haemophilus influenzae (NTHi). However, the underlying molecular mechanisms driving macrophage phenotypic differentiation are largely unclear. Our study investigated the role of Shp2, a Src homology 2 domain-containing phosphatase, in the regulation of pulmonary inflammation and bacterial clearance. Shp2 levels were increased upon NTHi stimulation. Selective inhibition of Shp2 in mice led to an attenuated inflammatory response by skewing macrophages toward alternatively activated macrophage (M2) polarization. Upon pulmonary NTHi infection, Shp2(-/-) mice, in which the gene encoding Shp2 in monocytes/macrophages was deleted, showed an impaired inflammatory response and decreased antibacterial ability, compared with wild-type controls. In vitro data demonstrated that Shp2 regulated activated macrophage (M1) gene expression via activation of p65-nuclear factor-κB signaling, independent of p38 and extracellular regulated kinase-mitogen-activated proteins kinase signaling pathways. Taken together, our study indicates that Shp2 is required to orchestrate macrophage function and regulate host innate immunity against pulmonary bacterial infection.

TGF-β3-induced miR-494 inhibits macrophage polarization via suppressing PGE2 secretion in mesenchymal stem cells

Abnormal macrophage polarization at the maternal-fetal interface may contribute to the development of Preeclampsia (PE). The reason why macrophage polarization changed in PE is still unclear. Decidual mesenchymal stem cells (dMSCs) could regulate macrophage polarization. However, miRNA in dMSCs of PE were maladjusted. Therefore, we speculated that miRNA may affect dMSC-regulated macrophage polarization. In this study, we found that miR-494-overexpressed dMSCs inhibit M2 macrophage polarization and this inhibitory effect is mediated by miR-494-reduced PGE2 secretion. Furthermore, we proved that miR-494 is induced by TGF-β3. In summary, our findings suggest that the high expression of TGF-β3 in PE decidua stimulates miR-494 in dMSCs and attenuates the regulation of MSC switching the macrophage toward M2 type, contributing to an immune imbalance at maternal-fetal interface.

Pioglitazone alleviates inflammation in diabetic mice fed a high-fat diet via inhibiting advanced glycation end-product-induced classical macrophage activation

Classically activated macrophages (M1) are associated with inflammation in diabetic patients. Inflammation is a known risk factor in diabetes. The present study tested the hypothesis that pioglitazone (PIO) alleviates inflammation in diabetic mice fed a high-fat diet by inhibiting advanced glycation end-product (AGE)-induced classical macrophage activation. It was found that AGE treatment promoted the transcription of pro-inflammatory molecules and M1 surface markers, whereas PIO increased the expression of anti-inflammatory genes and decreased the expression of pro-inflammatory mediators in bone marrow-derived macrophages (BMDMs) in a dose-dependent manner. Furthermore, pretreatment with PIO abrogated the effects of AGE on pro-inflammatory markers and partly inhibited AGE-induced nuclear factor-κB (NF-κB) activation. PIO treatment partly reduced the inflammatory phenotype in diabetic ApoE(-/-) mice, and significantly reduced NF-κB activation in plaques. Therefore, we conclude that PIO blocks classical activation of macrophages and attenuates inflammation in mouse models of diabetes.