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

20-Hydroxy-3-Oxolupan-28-Oic Acid Attenuates Inflammatory Responses by Regulating PI3K⁻Akt and MAPKs Signaling Pathways in LPS-Stimulated RAW264.7 Macrophages

20-Hydroxy-3-oxolupan-28-oic acid (HOA), a lupane-type triterpene, was obtained from the leaves of Mahonia bealei, which is described in the Chinese Pharmacopeia as a remedy for inflammation and related diseases. The anti-inflammatory mechanisms of HOA, however, have not yet been fully elucidated. Therefore, the objective of this study was to characterize the molecular mechanisms of HOA in lipopolysaccharide (LPS)-stimulated RAW264.7 cells. HOA suppressed the release of nitric oxide (NO), pro-inflammatory cytokine tumor necrosis factor α (TNF-α), and interleukin 6 (IL-6) in LPS-stimulated RAW264.7 macrophages without affecting cell viability. Quantitative real-time reverse-transcription polymerase chain reaction (RT-qPCR) analysis indicated that HOA also suppressed the gene expression of inducible NO synthase (iNOS), TNF-α, and IL-6. Further analyses demonstrated that HOA inhibited the phosphorylation of upstream signaling molecules, including p85, PDK1, Akt, IκBα, ERK, and JNK, as well as the nuclear translocation of nuclear factor κB (NF-κB) p65. Interestingly, HOA had no effect on the LPS-induced nuclear translocation of activator protein 1 (AP-1). Taken together, these results suggest that HOA inhibits the production of cytokine by downregulating iNOS, TNF-α, and IL-6 gene expression via the downregulation of phosphatidylinositol 3-kinase (PI3K)/Akt and mitogen-activated protein kinases (MAPKs), and the inhibition of NF-κB activation. Our findings indicate that HOA could potentially be used as an anti-inflammatory agent for medical use.

Amplified Host Defense by Toll-Like Receptor-Mediated Downregulation of the Glucocorticoid-Induced Leucine Zipper (GILZ) in Macrophages

Activation of toll-like receptors (TLRs) plays a pivotal role in the host defense against bacteria and results in the activation of NF-κB-mediated transcription of proinflammatory mediators. Glucocorticoid-induced leucine zipper (GILZ) is an anti-inflammatory mediator, which inhibits NF-κB activity in macrophages. Thus, we aimed to investigate the regulation and role of GILZ expression in primary human and murine macrophages upon TLR activation. Treatment with TLR agonists, e.g., Pam₃CSK₄ (TLR1/2) or LPS (TLR4) rapidly decreased GILZ mRNA and protein levels. In consequence, GILZ downregulation led to enhanced induction of pro-inflammatory mediators, increased phagocytic activity, and a higher capacity to kill intracellular bacteria (Salmonella enterica serovar typhimurium), as shown in GILZ knockout macrophages. Treatment with the TLR3 ligand polyinosinic: polycytidylic acid [Poly(I:C)] did not affect GILZ mRNA levels, although GILZ protein expression was decreased. This effect was paralleled by sensitization toward TLR1/2- and TLR4-agonists. A bioinformatics approach implicated more than 250 miRNAs as potential GILZ regulators. Microarray analysis revealed that the expression of several potentially GILZ-targeting miRNAs was increased after Poly(I:C) treatment in primary human macrophages. We tested the ability of 11 of these miRNAs to target GILZ by luciferase reporter gene assays. Within this small set, four miRNAs (hsa-miR-34b^*,−222,−320d,−484) were confirmed as GILZ regulators, suggesting that GILZ downregulation upon TLR3 activation is a consequence of the synergistic actions of multiple miRNAs. In summary, our data show that GILZ downregulation promotes macrophage activation. GILZ downregulation occurs both via MyD88-dependent and -independent mechanisms and can involve decreased mRNA or protein stability and an attenuated translation.

Implantation of VEGF-functionalized cell-free vascular grafts: regenerative and immunological response

Recently, our group demonstrated that immobilized VEGF can capture flowing endothelial cells (ECs) from the blood in vitro and promote endothelialization and patency of acellular tissue-engineered vessels (A-TEVs) into the arterial system of an ovine animal model. Here, we demonstrate implantability of submillimeter diameter heparin and VEGF-decorated A-TEVs in a mouse model and discuss the cellular and immunologic response. At 1 mo postimplantation, the graft lumen was fully endothelialized, as shown by expression of EC markers such as CD144, eNOS, CD31, and VEGFR2. Interestingly, the same cells coexpressed leukocyte/macrophage (Mϕ) markers CD14, CD16, VEGFR1, CD38, and EGR2. Notably, there was a stark difference in the cellular makeup between grafts containing VEGF and those containing heparin alone. In VEGF-containing grafts, infiltrating monocytes (MCs) converted into anti-inflammatory M2-Mϕs, and the grafts developed well-demarcated luminal and medial layers resembling those of native arteries. In contrast, in grafts containing only heparin, MCs converted primarily into M1-Mϕs, and the endothelial and smooth muscle layers were not well defined. Our results indicate that VEGF may play an important role in regulating A-TEV patency and regeneration, possibly by regulating the inflammatory response to the implants.-Smith, R. J., Jr., Yi, T., Nasiri, B., Breuer, C. K., Andreadis, S. T. Implantation of VEGF-functionalized cell-free vascular grafts: regenerative and immunological response.

Zoledronic acid promotes TLR-4-mediated M1 macrophage polarization in bisphosphonate-related osteonecrosis of the jaw

Bisphosphonate-related osteonecrosis of the jaw (BRONJ) is a detrimental side effect of the long-term administration of bisphosphonates. Although macrophages were reported to be an important mediator of BRONJ, the detailed potential mechanism of BRONJ remains unclear. Here, we reported an elevated TLR-4 expression in macrophages under action of zoledronic acid (ZA), resulting in enhanced M1 macrophage polarization and decreased M2 macrophage polarization both in vitro and in vivo. After inhibiting the TLR-4 signaling pathway, the activation of the TLR-4/NF-κB signaling pathway and the induction of NF-κB nuclear translocation and production of proinflammatory cytokines by ZA were suppressed in macrophages, thereby inhibiting M1 macrophage polarization. By utilizing the TLR-4^-/- mice, development of BRONJ was markedly ameliorated, and M1 macrophages were significantly attenuated in the extraction socket tissues in the TLR-4^-/- mice. Importantly, the systemic administration of the TLR-4 inhibitor TAK-242 improved the wound healing of the extraction socket and decreased the incidence rate of BRONJ. Taken together, our findings suggest that TLR-4-mediated macrophage polarization participates in the pathogenesis of BRONJ in mice, and TLR-4 may be a potential target for the prevention and therapeutic treatment of BRONJ.-Zhu, W., Xu, R., Du, J., Fu, Y., Li, S., Zhang, P., Liu, L., Jiang, H. Zoledronic acid promotes TLR-4-mediated M1 macrophage polarization in bisphosphonate-related osteonecrosis of the jaw.

Macrophages in Renal Fibrosis

Monocytes/macrophages are highly involved in the process of renal injury, repair and fibrosis in many aspects of experimental and human renal diseases. Monocyte-derived macrophages, characterized by high heterogeneity and plasticity, are recruited, activated, and polarized in the whole process of renal fibrotic diseases in response to local microenvironment. As classically activated M1 or CD11b⁺/Ly6C^high macrophages accelerate renal injury by producing pro-inflammatory factors like tumor necrosis factor-alpha (TNFα) and interleukins, alternatively activated M2 or CD11b⁺/Ly6C^intermediate macrophages may contribute to kidney repair by exerting anti-inflammation and wound healing functions. However, uncontrolled M2 macrophages or CD11b⁺/Ly6C^low macrophages promote renal fibrosis via paracrine effects or direct transition to myofibroblast-like cells via the process of macrophage-to-myofibroblast transition (MMT). In this regard, therapeutic strategies targeting monocyte/macrophage recruitment, activation, and polarization should be emphasized in the treatment of renal fibrosis.

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.

Role of macrophages in peripheral nerve injury and repair

Resident and inflammatory macrophages are essential effectors of the innate immune system. These cells provide innate immune defenses and regulate tissue and organ homeostasis. In addition to their roles in diseases such as cancer, obesity and osteoarthritis, they play vital roles in tissue repair and disease rehabilitation. Macrophages and other inflammatory cells are recruited to tissue injury sites where they promote changes in the microenvironment. Among the inflammatory cell types, only macrophages have both pro-inflammatory (M1) and anti-inflammatory (M2) actions, and M2 macrophages have four subtypes. The co-action of M1 and M2 subtypes can create a favorable microenvironment, releasing cytokines for damaged tissue repair. In this review, we discuss the activation of macrophages and their roles in severe peripheral nerve injury. We also describe the therapeutic potential of macrophages in nerve tissue engineering treatment and highlight approaches for enhancing M2 cell-mediated nerve repair and regeneration.

Macrophage plasticity, polarization and function in response to curcumin, a diet-derived polyphenol, as an immunomodulatory agent

Monocytes and macrophages are important cells of the innate immune system that have diverse functions, including defense against invading pathogens, removal of dead cells by phagocytosis, antigen presentation in the context of MHC class I and class II molecules, and production of various pro-inflammatory cytokines and chemokines such as IL-1β, IL-6, TNF-α and MCP-1. In addition, pro-inflammatory (M1) and anti-inflammatory (M2) macrophages clearly play important roles in the progression of several inflammatory diseases. Therefore, therapies that target macrophage polarization and function by either blocking their trafficking to sites of inflammation, or skewing M1 to M2 phenotype polarization may hold clinical promise in several inflammatory diseases. Dietary-derived polyphenols have potent natural anti-oxidative properties. Within this group of polyphenols, curcumin has been shown to suppress macrophage inflammatory responses. Curcumin significantly reduces co-stimulatory molecules and also inhibits MAPK activation and the translocation of NF-κB p65. Curcumin can also polarize/repolarize macrophages toward the M2 phenotype. Curcumin-treated macrophages have been shown to be highly efficient at antigen capture and endocytosis via the mannose receptor. These novel findings provide new perspectives for the understanding of the immunopharmacological role of curcumin, as well as its therapeutic potential for impacting macrophage polarization and function in the context of inflammation-related disease. However, the precise effects of curcumin on the migration, differentiation, polarization and immunostimulatory functions of macrophages remain unknown. Therefore, in this review, we summarized whether curcumin can influence macrophage polarization, surface molecule expression, cytokine and chemokine production and their underlying pathways in the prevention of inflammatory diseases.

Involvement of M1 Macrophage Polarization in Endosomal Toll-Like Receptors Activated Psoriatic Inflammation

Psoriasis is a chronic inflammatory skin disorder that affects ~2%–3% of the worldwide population. Inappropriate and excessive activation of endosomal Toll-like receptors 7, 8, and 9 (TLRs 7–9) at the psoriatic site has been shown to play a pathogenic role in the onset of psoriasis. Macrophage is a major inflammatory cell type that can be differentiated into phenotypes M1 and M2. M1 macrophages produce proinflammatory cytokines, and M2 macrophages produce anti-inflammatory cytokines. The balance between these two types of macrophages determines the progression of various inflammatory diseases; however, whether macrophage polarization plays a role in psoriatic inflammation activated by endosomal TLRs has not been investigated. In this study, we investigated the function and mechanism of macrophages related to the pathogenic role of TLRs 7–9 in the progression of psoriasis. Analysis of clinical data in database revealed significantly increased expression of macrophage markers and inflammatory cytokines in psoriatic tissues over those in normal tissues. In animal studies, depletion of macrophages in mice ameliorated imiquimod, a TLR 7 agonist-induced psoriatic response. Imiquimod induced expression of genes and cytokines that are signature of M1 macrophage in the psoriatic lesions. In addition, treatment with this TLR 7 agonist shifted macrophages in the psoriatic lesions to a higher M1/M2 ratio. Both of the exogenous and endogenous TLR 7–9 ligands activated M1 macrophage polarization. M1 macrophages expressed higher levels of proinflammatory cytokines and TLRs 7–9 than M2 macrophages. These results suggest that by rendering macrophages into a more inflammatory status and capable of response to their ligands in the psoriatic sites, TLR 7–9 activation drives them to participate in endosomal TLR-activated psoriatic inflammation, resulting in an amplified inflammatory response. Our results also suggest that blocking M1 macrophage polarization could be a strategy which enables inhibition of psoriatic inflammation activated by these TLRs.

Gamma secretase dependent release of the CD44 cytoplasmic tail upregulates IFI16 in cd44-/- tumor cells, MEFs and macrophages

The adhesion molecule and co-receptor of receptor tyrosine kinases, CD44, is expressed in all cells of the immune system, but also in numerous non-immune cells. CD44 plays roles in the cellular response to different pathogens. The molecular actions of CD44 during these processes are by and large still unknown. The CD44 molecule undergoes a sequential proteolytic cleavage which leads to the release of a soluble intracellular domain (CD44-ICD). Previous reports had shown that the CD44-ICD is taken up into the nucleus where it enhances transcription of specific target genes. By RNA profiling we identified a CD44-dependent transcriptional increase of interferon-responsive genes, among them IFI16. IFI16 is important in the innate immune response. It senses and binds pathogenic DNA and, together with cGAS, activates the cGAS-cGAMP-STING pathway and induces the expression of genes relevant for the response, e.g. IFN-β. Our results show that the enhancement of IFI16 expression depended on CD44 cleavage. A CD44-negative tumor cell line, embryonic fibroblasts and bone marrow-derived macrophages from cd44^-/- mice were reduced in their response to IFN-γ, to viral DNA fragments and to Listeria monocytogenes infection. We could rescue the deficiency of CD44 negative RPM-MC cells and cd44^-/- MEFs by expressing only the soluble CD44-ICD in the absence of any other CD44 domain. Expression of the CD44-ICD carrying a mutation that prevented the uptake into the nucleus, could not rescue the absence of CD44. This molecular aspect of regulation by CD44 may explain part of the immune phenotypes of mice with cd44 gene disruption.

Exploitation of Synthetic mRNA To Drive Immune Effector Cell Recruitment and Functional Reprogramming In Vivo

Therapeutic strategies based on in vitro-transcribed mRNA (IVT) are attractive because they avoid the permanent signature of genomic integration that is associated with DNA-based therapy and result in the transient production of proteins of interest. To date, IVT has mainly been used in vaccination protocols to generate immune responses to foreign Ags. In this "proof-of-principle" study, we explore a strategy of combinatorial IVT to recruit and reprogram immune effector cells to acquire divergent biological functions in mice in vivo. First, we demonstrate that synthetic mRNA encoding CCL3 is able to recruit murine monocytes in a nonprogrammed state, exhibiting neither bactericidal nor tissue-repairing properties. However, upon addition of either Ifn-γ mRNA or Il-4 mRNA, we successfully polarized these cells to adopt either M1 or M2 macrophage activation phenotypes. This cellular reprogramming was demonstrated through increased expression of known surface markers and through the differential modulation of NADPH oxidase activity, or the superoxide burst. Our study demonstrates how IVT strategies can be combined to recruit and reprogram immune effector cells that have the capacity to fulfill complex biological tasks in vivo.

Gene Network Analysis of Interstitial Macrophages After Treatment with Induced Pluripotent Stem Cells Secretome (iPSC-cm) in the Bleomycin Injured Rat Lung

Idiopathic pulmonary fibrosis (IPF) is a complex disease involving various cell types. Macrophages are essential in maintenance of physiological homeostasis, wound repair and fibrosis in the lung. Macrophages play a crucial role in repair and remodeling by altering their phenotype and secretory pattern in response to injury. The secretome of induced pluripotent stem cells (iPSC-cm) attenuates injury and fibrosis in bleomycin injured rat lungs. In the current study, we evaluate the effect of iPSC-cm on gene expression and phenotype of interstitial macrophage in bleomycin injured rat lungs in vivo. iPSC-cm was intratracheally instilled 7 days after bleomycin induced lung injury and assessed 7 days later and single cell isolation was performed. Macrophages were FACS sorted and microarray analysis was performed. We characterized changes in the rat lung interstitial macrophages using transcriptional profiling. iPSC-cm reduced the total collagen content of the lung and reduced different macrophage populations. Gene set enrichment analysis revealed involvement of three essential pathways (a) immune modulation, (b) branching morphogenesis and (c) canonical Wnt signaling. This study demonstrates that iPSC-cm reduces fibrosis in bleomycin injured rat lung by partially altering the macrophages and regulating their gene expression.

Abdominal paracentesis drainage ameliorates severe acute pancreatitis in rats by regulating the polarization of peritoneal macrophages

AIM

To investigate the role of peritoneal macrophage (PM) polarization in the therapeutic effect of abdominal paracentesis drainage (APD) on severe acute pancreatitis (SAP).

METHODS

SAP was induced by 5% Na-taurocholate retrograde injection in Sprague-Dawley rats. APD was performed by inserting a drainage tube with a vacuum ball into the lower right abdomen of the rats immediately after the induction of SAP. To verify the effect of APD on macrophages, PMs were isolated and cultured in an environment, with the peritoneal inflammatory environment simulated by the addition of peritoneal lavage in complete RPMI 1640 medium. Hematoxylin and eosin staining was performed. The levels of pancreatitis biomarkers amylase and lipase as well as the levels of inflammatory mediators in the blood and peritoneal lavage were determined. The polarization phenotypes of the PMs were identified by detecting the marker expression of M1/M2 macrophages via flow cytometry, qPCR and immunohistochemical staining. The protein expression in macrophages that had infiltrated the pancreas was determined by Western blot.

RESULTS

APD treatment significantly reduced the histopathological scores and levels of amylase, lipase, tumor necrosis factor-α and interleukin (IL)-1β, indicating that APD ameliorates the severity of SAP. Importantly, we found that APD treatment polarized PMs towards the M2 phenotype, as evidenced by the reduced number of M1 macrophages and the reduced levels of pro-inflammatory mediators, such as IL-1β and L-selectin, as well as the increased number of M2 macrophages and increased levels of anti-inflammatory mediators, such as IL-4 and IL-10. Furthermore, in an in vitro study wherein peritoneal lavage from the APD group was added to the cultured PMs to simulate the peritoneal inflammatory environment, PMs also exhibited a dominant M2 phenotype, resulting in a significantly lower level of inflammation. Finally, APD treatment increased the proportion of M2 macrophages and upregulated the expression of the anti-inflammatory protein Arg-1 in the pancreas of SAP model rats.

CONCLUSION

These findings suggest that APD treatment exerts anti-inflammatory effects by regulating the M2 polarization of PMs, providing novel insights into the mechanism underlying its therapeutic effect.

Suppression of TLR4 by miR-448 is involved in Diabetic development via regulating Macrophage polarization

OBJECTIVES

Lipopolysaccharide (LPS) contributed to the development and progression of type 2 diabetes mellitus (T2D), while TLR4 is reported to mediate the LPS-induced inflammation in macrophages. However, the potential molecular mechanisms for TLR4-mediated macrophages activation in T2D have not yet to be fully clarified.

METHODS

Type 2 diabetes models in C57BL/6J mice were generated by a combination administration of streptozotocin (STZ) and a high-fat diet (HFD). Cell proportions of M1 and M2 macrophages were analyzed using flow cytometry. Expression profiles of miR-448 and TLR 4 were determined by qRT-PCR and Western blot.

KEY FINDINGS

LPS/IFN-γ significantly induced M1 polarization in macrophages characterized by the increased levels of TNF-α, IL-6, IL-12, iNOS and decreased levels of TNF-β, CCL-22, IL-10 and Arg-1, with a higher expression of toll-like receptor 4 (TLR4) in vitro. Consistently, T2D mice-derived macrophages had a significantly elevated expression of TLR4 mRNA and decreased expression of miR-448. We further confirmed that miR-448 could inhibit TLR4 expression by targeting the 3'-UTR of TLR4, rescuing the LPS/IFN-γ-induced M1 macrophage polarization.

CONCLUSIONS

Taken together, our results indicated that decreased miR-448 in diabetic macrophages may contribute to LPS-induced M1 polarization by targeting TLR4, thereby modulating T2D development.

Inhibition of osteoclastogenesis by opsonized Porphyromonas gingivalis

A crucial step in the pathogenesis of periodontal disease (PD) is activation of osteoclasts (OC) by numerous virulence factors produced by Porphyromonas gingivalis (Pg). To understand pathogenesis of PD and the role of specific adaptive immune responses, effects of antibodies on Pg‐induced OC differentiation and function were investigated. Human peripheral blood‐derived monocytes were differentiated to OC in the presence or absence of: (a) Pg; (b) antibodies to Pg; and (c) antibody‐opsonized Pg. Findings suggest significant induction of osteoclastogenesis by Pg when compared to control cultures, whereas opsonization decreased osteoclastogenesis by 45%. Immune receptor gene expression profile in the presence of opsonized Pg showed marked upregulation of TLR1 (three‐fold) and TLR2 (twofold) along with FcγRIIB (two‐fold) and FcγRIII receptors (five‐fold), but not TLR4 and FcRγ receptors. Interestingly, blocking FcγRIIB, but not FcγRIII receptor, reversed the inhibitory effects of opsonized Pg suggesting a critical role played by FcγRIIB in osteoclastogenesis. Furthermore, opsonized Pg transformed OC precursors to a “macrophage phenotype” suggesting a bone protective role of the immune complexes in modulating osteoclastogenesis, probably by competing as an agonist for pattern recognition receptors, and inducing selective activation of FcγRs with simultaneous suppression of FcRγ which regulates bone resorptive process. Further defining effective antibody isotypes, avidity, and antigenic specificity could improve targets for eliciting protective immunity.

Active vitamin D regulates macrophage M1/M2 phenotypes via the STAT-1-TREM-1 pathway in diabetic nephropathy

AIM

Imbalance of M1/M2 macrophages phenotype activation is a key point in diabetic nephropathy (DN). This study aimed to investigate whether active vitamin D (VD) suppresses macrophage transition to the M1 phenotype via inhibiting the high glucose-induced STAT-1 phosphorylation to reduce TREM-1 expression.

METHODS

In vivo, pathological changes in kidney tissue were detected and the expression of CD68 TREM-1, STAT-1, M1 makers, and M2 makers were acquired in renal tissue of patients with DN and 18w DN rats. In vitro, RAW 264.7 cells were incubated in the presence of high glucose with or without VD_. Silencing and overexpression of TREM-1 and silencing and activate of STAT-1 were explored to elucidate the underlying mechanism. The expression of TREM-1 and STAT-1 and the changes of macrophage phenotype were examined separately by western blot and immunofluorescence staining.

RESULTS

(a) Expression of TREM-1, p-STAT-1, and M1 markers (iNOS and TNF-α) were increased and positively correlated in kidneys from patients with DN. (b) In DN rats, the enlargement of glomerular surface area, expansion of glomerular mesangial matrix, the expression of CD68, TREM-1, p-STAT-1, and M1 marker (iNOS) were significantly increased in comparison with the normal control group, whereas above changes were markedly decreased in the diabetic group treated with the VD group. (c) In vitro, VD significantly decreased high glucose-induced CD68, TREM-1, p-STAT-1, and M1 marker (iNOS) expression. However, above-mentioned effects of VD are abolished when TREM-1 is overexpressed or STAT-1 is activated. Reductions in STAT-1 expression decreased the TREM-1 expression.

CONCLUSION

VD can inhibit macrophage transition to the M1 phenotype through the STAT-1/TREM-1 pathway.

Screening of biopolymeric materials for cardiovascular surgery toxicity-Evaluation of their surface relief with assessment of morphological aspects of monocyte/macrophage polarization in atherosclerosis patients

The morphotypes of human macrophages (MPh) were studied in the culture on nano-structured biopolymer substrates, made from polyhydroxyalcanoates (PHAs) of five various monomer compositions, followed by the solvent evaporation. Its surface relief, which was further in direct contact with human cells in vitro, was analyzed by atomic force microscopy (AFM) and scanning electron microscopy (SEM). It was shown, that the features of the micro/nano relief depend on the monomeric composition of the polymer substrates. Monocytes (MN) of patients with atherosclerosis and cardiac ischemia, undergoing stenting and conventional anti-atherosclerotic therapy, were harvested prior and after stenting. MN were isolated and cultured, with the transformation into MPh in direct contact with biopolymer culture substrates with different monomer composition and nano-reliefs, and transformed into MPh, in comparison with the same process on standard culture plastic. Sub-populations of cells with characteristic morphology in each phenotypic class were described, and their quantitative ratios for each sample of polymers were counted as an intermediate result in the development of "smart" material for cardiovascular devices. The results obtained allow us to assume, that the processes of MPh differentiation and polarization in vitro depend not only on the features of the micro/nano relief of biopolymer substrates, but also on the initial state of MN in vivo and general response of patients.

NF-κB/MAPK activation underlies ACVR1-mediated inflammation in human heterotopic ossification

BACKGROUND

Inflammation helps regulate normal growth and tissue repair. Although bone morphogenetic proteins (BMPs) and inflammation are known contributors to abnormal bone formation, how these pathways interact in ossification remains unclear.

METHODS

We examined this potential link in patients with fibrodysplasia ossificans progressiva (FOP), a genetic condition of progressive heterotopic ossification caused by activating mutations in the Activin A type I receptor (ACVR1/ALK2). FOP patients show exquisite sensitivity to trauma, suggesting that BMP pathway activation may alter immune responses. We studied primary blood, monocyte, and macrophage samples from control and FOP subjects using multiplex cytokine, gene expression, and protein analyses; examined CD14+ primary monocyte and macrophage responses to TLR ligands; and assayed BMP, TGF-β activated kinase 1 (TAK1), and NF-κB pathways.

RESULTS

FOP subjects at baseline without clinically evident heterotopic ossification showed increased serum IL-3, IL-7, IL-8, and IL-10. CD14+ primary monocytes treated with the TLR4 activator LPS showed increased CCL5, CCR7, and CXCL10; abnormal cytokine/chemokine secretion; and prolonged activation of the NF-κB pathway. FOP macrophages derived from primary monocytes also showed abnormal cytokine/chemokine secretion, increased TGF-β production, and p38MAPK activation. Surprisingly, SMAD phosphorylation was not significantly changed in the FOP monocytes/macrophages.

CONCLUSIONS

Abnormal ACVR1 activity causes a proinflammatory state via increased NF-κB and p38MAPK activity. Similar changes may contribute to other types of heterotopic ossification, such as in scleroderma and dermatomyositis; after trauma; or with recombinant BMP-induced bone fusion. Our findings suggest that chronic antiinflammatory treatment may be useful for heterotopic ossification.

Hypothalamic Microglial Activation in Obesity: A Mini-Review

Emerging data demonstrate that microglia activation plays a pivotal role in the development of hypothalamic inflammation in obesity. Early after the introduction of a high-fat diet, hypothalamic microglia undergo morphological, and functional changes in response to excessive dietary saturated fats. Initially the resident microglia are affected; however, as diet-induced obesity persists, bone marrow-derived myeloid cells gradually replace resident microglia. Genetic and pharmacological approaches aimed at dampening the inflammatory activity in the hypothalamus of experimental models of obesity have proven beneficial to correct the obese phenotype and improve metabolic abnormalities commonly associated with obesity. These approaches provide an experimental proof-of-concept that hypothalamic inflammation is central to the pathophysiology of obesity; understanding the details of the roles played by microglia in this process may help the development of preventive and therapeutic advances in the field. In this review, we discuss the potential mechanisms underlying hypothalamic microglial activation in high-fat induced obesity.

Transcriptional and functional diversity of human macrophage repolarization

BACKGROUND

Macrophage plasticity allows cells to adopt different phenotypes, a property with important implications in disorders such as cystic fibrosis (CF) and asthma.

OBJECTIVE

We sought to examine the transcriptional and functional significance of macrophage repolarization from an M1 to an M2 phenotype and assess the role of a common human genetic disorder (CF) and a prototypical allergic disease (asthma) in this transformation.

METHODS

Monocyte-derived macrophages were collected from healthy subjects and patients with CF and polarized to an M2 state by using IL-4, IL-10, glucocorticoids, apoptotic PMNs, or azithromycin. We performed transcriptional profiling and pathway analysis for each stimulus. We assessed the ability of M2-repolarized macrophages to respond to LPS rechallenge and clear apoptotic neutrophils and used murine models to determine conserved functional responses to IL-4 and IL-10. We investigated whether M2 signatures were associated with alveolar macrophage phenotypes in asthmatic patients.

RESULTS

We found that macrophages exhibit highly diverse responses to distinct M2-polarizing stimuli. Specifically, IL-10 activated proinflammatory pathways and abrogated LPS tolerance, allowing rapid restoration of LPS responsiveness. In contrast, IL-4 enhanced LPS tolerance, dampening proinflammatory responses after repeat LPS challenge. A common theme observed across all M2 stimuli was suppression of interferon-associated pathways. We found that CF macrophages had intact reparative and transcriptional responses, suggesting that macrophage contributions to CF-related lung disease are primarily shaped by their environment. Finally, we leveraged in vitro-derived signatures to show that allergen provocation induces distinct M2 state transcriptional patterns in alveolar macrophages.

CONCLUSION

Our findings highlight the diversity of macrophage polarization, attribute functional consequences to different M2 stimuli, and provide a framework to phenotype macrophages in disease states.

Purification, identification and functional characterization of an immunomodulatory protein from Pleurotus eryngii

Pleurotus eryngii contains bioactive compounds that can activate the immune system. Here we report the identification, purification, and functional characterization of the bioactive P. eryngii protein (PEP) 1b. PEP 1b was discovered to be a 21.9 kDa protein with the ability to induce the M1-polarization of the macrophage cell line RAW 264.7 cells. Biochemical measurements showed that PEP 1b stimulated nitric oxide (NO), IL-1β, IL-6 and TNF-α production and regulated inducible NO synthase. Phosphorylation and inhibitor studies revealed that PEP 1b promoted the translocation of NF-kB from the cytosol to the nucleus allowing the induction of target gene expression and NO production. The phosphorylation of JNK and ERK1/2 was found to be necessary for NO production. Each phosphorylation pathway was found to require a Toll-like receptor (TLR) 4 as a prerequisite for PEP 1b-induced NO production. This study suggests that PEP 1b is an immunomodulatory protein that can boost cellular immune responses through the activation of the TLR4-NF-κB and MAPK signaling pathways.

Cold Atmospheric Pressure Plasma Treatment Modulates Human Monocytes/Macrophages Responsiveness

Monocytes are involved in innate immune surveillance, establishment and resolution on inflammation, and can polarize versus M1 (pro-inflammatory) or M2 (anti-inflammatory) macrophages. The possibility to control and drive immune cells activity through plasma stimulation is therefore attractive. We focused on the effects induced by cold-atmospheric plasma on human primary monocytes and monocyte-derived macrophages. Monocytes resulted more susceptible than monocyte-derived macrophages to the plasma treatment as demonstrated by the increase in reactive oxygen (ROS) production and reduction of viability. Macrophages instead were not induced to produce ROS and presented a stable viability. Analysis of macrophage markers demonstrated a time-dependent decrease of the M1 population and a correspondent increase of M2 monocyte-derived macrophages (MDM). These findings suggest that plasma treatment may drive macrophage polarization towards an anti-inflammatory phenotype.

Azithromycin promotes alternatively activated macrophage phenotype in systematic lupus erythematosus via PI3K/Akt signaling pathway

Alternatively activated macrophages have been reported to be helpful to alleviate systematic lupus erythematosus (SLE), and azithromycin could serve as an immunomodulator by promoting alternatively activated macrophage phenotype. However, the effect of azithromycin in SLE and the involved mechanism remain undetermined. The aim of this study is to characterize azithromycin and the underlying mechanism contributing to SLE therapy. First, we compared monocytes from SLE patients and matched healthy donors, and found monocytes from SLE patients exhibited more CD14⁺CD86⁺ cells, impaired phagocytic activity, and elevated interleukin (IL)-1β, IL-6, and tumor necrosis factor (TNF)-α (the classical activated phenotype), which could be blocked by azithromycin. On the contrary, there were fewer CD14⁺CD163⁺ cells in SLE patients, accompanied by decreased arginase (Arg)-1 and found in inflammatory zone (Fizz)-1 (the alternatively activated phenotype). And IL-10, the crucial immune regulatory factor secreted by alternatively activated monocytes/macrophages, also showed a decreased trend in SLE patients. In addition, all these markers were up-regulated after azithromycin treatment. Next, we used activated lymphocyte-derived-DNA to imitate SLE macrophages in vitro to investigate the possible mechanism involved. Azithromycin showed the same effect in imitated SLE macrophages, with distinct Akt phosphorylation at 30 min and 12 h. After inhibiting Akt phosphorylation by LY294002, the down-regulation of CD80, IL-1β, IL-6, and TNF-α caused by azithromycin raised again, meanwhile, the up-regulation of CD206, Arg-1, Fizz-1, and IL-10 due to azithromycin was abolished. Additionally, insulin-like growth factor 1 (IGF-1), the specific agonist of Akt, played a similar role to azithromycin in imitated SLE macrophages. Taken together, our data indicated a novel role of azithromycin in alleviating SLE by promoting alternatively activated macrophage phenotype, and the PI3K/Akt signaling pathway was involved. Our findings provide a rationale for further investigation of novel therapeutic strategy for SLE patients.

Upregulation of miR-196b-5p attenuates BCG uptake via targeting SOCS3 and activating STAT3 in macrophages from patients with long-term cigarette smoking-related active pulmonary tuberculosis

Background

Cigarette smoking (CS) triggers an intense and harmful inflammatory response in lungs mediated by alveolar and blood macrophages, monocytes, and neutrophils and is closely associated with prevalence of tuberculosis (TB). The risk of death in patients with long-term cigarette smoking-related pulmonary tuberculosis (LCS-PTB) is approximately 4.5 times higher than those with nonsmoking pulmonary tuberculosis (N-PTB). However, the mechanisms underlying the harmful inflammatory responses in the setting of LCS-PTB have not been well documented.

Methods

28 cases LCS-PTB patients, 22 cases N-PTB patients and 20 cases healthy volunteers were enrolled in this study. Monocytes were isolated from peripheral blood mononuclear cells. Differentiated human MDM and U937 cell were prepared with M-CSF and PMA stimulation, respectively. The miR-196b-5p, STAT1, STAT3, STAT4, STAT5A, STAT5B, STAT6, SOCS1 and SOCS3 mRNA expression were detected by qRT-PCR. Western blot was performed according to SOCS1, SOCS3, and pSTAT3 expression. The mycobacterial uptake by MDMs from different groups of patients after Bacillus Calmette–Guérin (BCG) infection and agomir-196b-5p or antagomir-196b-5p transfection were used by flow cytometry analysis. Human IL-6, IL-10 and TNF-α levels on the plasma and cell culture supernatant samples were measured using ELISA. For dual-luciferase reporter assay, the SOCS3 3′-UTR segments, containing the binding elements of miR-196b-5p or its mutant versions were synthesized as sense and antisense linkers.

Results

In this study, we found that IL-6, TNF-α production, SOCS3 mRNA expression were downregulated, while miR-196b-5p and STAT3 mRNA expression were upregulated in monocytes from LCS-PTB patients as compared to N-PTB patients. Meanwhile, we demonstrated that miR-196b-5p could target SOCS3 and activate STAT3 signaling pathway, which may possibly contribute to attenuation of BCG uptake and decrease in IL-6 and TNF-α production in macrophages.

Conclusions

Our findings revealed that CS exposure regulates inflammatory responses in monocyte/macrophages from LCS-PTB patients via upregulating miR-196b-5p, and further understanding of the specific role of miR-196b-5p in inflammatory responses mightfacilitate elucidating the pathogenesis of LCS-PTB, thus leading to the development of new therapeutic strategies for PTB patients with long-term cigarette smoking.

Electronic supplementary material

The online version of this article (10.1186/s12967-018-1654-9) contains supplementary material, which is available to authorized users.

Challenges facing nanotoxicology and nanomedicine due to cellular diversity

This review examines the interaction of nanomaterials (NMs) with cells from the perspective of major cellular differentiations. The structure and composition of cells reflect their role and function in a particular organ or environment. The normal differentiated-state and diseased cells may respond to NMs very differently. This review progresses with due care on nanotoxicology while emphasizing the potential of NMs in treating stress-associated disorders, including cancer and degeneration. The striking potential of NMs in inducing ROS, scavenging ROS, depleting cellular antioxidants, replenishing antioxidants, mimicking antioxidant enzyme activity, and modulating the immune system all show their considerable potential in treating cancer and other aging-associated disorders. It is now clear that NMs become more active and versatile when they come into contact with biological machinery, surprisingly in some cases, in a manner dependent on cell type. The mechanisms leading to the contrasting bioresponse of NMs ranging from toxicity to anticancer and from cell survival to carcinogenicity followed by their immuno-modulating potential show NMs to be a highly promising agent in biomedical therapy. This first-of-its-kind article seeks the challenges to be addressed that could provide a solid rationale in translating the promises of nanomedicine. A thorough understanding of normal and cancer biology could help to minimize the gap between basic and translational research in nanotechnology-based therapy.

Mesenchymal stem cells are attracted to latent HIV-1-infected cells and enable virus reactivation via a non-canonical PI3K-NFκB signaling pathway

Persistence of latent HIV-1 in macrophages (MACs) and T-helper lymphocytes (THLs) remain a major therapeutic challenge. Currently available latency reversing agents (LRAs) are not very effective in vivo. Therefore, understanding of physiologic mechanisms that dictate HIV-1 latency/reactivation in reservoirs is clearly needed. Mesenchymal stromal/stem cells (MSCs) regulate the function of immune cells; however, their role in regulating virus production from latently-infected MACs & THLs is not known. We documented that exposure to MSCs or their conditioned media (MSC-CM) rapidly increased HIV-1 p24 production from the latently-infected U1 (MAC) & ACH2 (THL) cell lines. Exposure to MSCs also increased HIV-1 long terminal repeat (LTR) directed gene expression in the MAC and THL reporter lines, U937-VRX and J-Lat (9.2), respectively. MSCs exposed to CM from U1 cells (U1-CM) showed enhanced migratory ability towards latently-infected cells and retained their latency-reactivation potential. Molecular studies showed that MSC-mediated latency-reactivation was dependent upon both the phosphatidyl inositol-3-kinase (PI3K) and nuclear factor-κB (NFκB) signaling pathways. The pre-clinically tested inhibitors of PI3K (PX-866) and NFκB (CDDO-Me) suppressed MSC-mediated HIV-1 reactivation. Furthermore, coexposure to MSC-CM enhanced the latency-reactivation efficacy of the approved LRAs, vorinostat and panobinostat. Our findings on MSC-mediated latency-reactivation may provide novel strategies against persistent HIV-1 reservoirs.

Modulation of macrophage polarization by level-1 Yo-Yo intermittent recovery test in young football players

The aim of this study was to examine the effect of the level-1 Yo-Yo intermittent recovery test (YYIRT1) on polarization of macrophages in young football players.Fourteen male football players (19.9 ± 1.4 years old) were enrolled in this study. YYIRT1 was performed with 20-meter shuttle runs at increasing speeds and 10-second active recovery in a 5-meter distance between runs till exhaustion. Fasting blood samples were collected before and immediately after YYIRT1. Analysis for macrophage polarization by flow cytometry, reactive oxygen species (ROS) by flow cytometry, biochemical parameters by chemical reactions, and serum cytokines by ELISA were performed. The rating of perceived exertion (RPE) and cardiovascular parameters were recorded.The time to exhaustion was 714.1 ± 114.4 seconds. The oxygen uptake ((Equation is included in full-text article.)) was 48.7 ± 5.6 mL/min/kg, RPE scale was 19 ± 1, resting heart rate and maximal heart rate were 64.9 ± 8.8 beat/min and 181.9 ± 9.3 beat/min, respectively, indicating a high level of cardiopulmonary fitness. The expression of macrophage-specific CD14 and M1 marker HLA-ABC, but not M2 marker CD206, was down-regulated after YYIRT1. The intracellular ROS levels in macrophages had no significant change. In biochemical profile, the serum levels of lactic dehydrogenase (LDH), a marker of muscle damage, increased after YYIRT1 whereas no significant alteration was noted in creatine phosphokinase (CPK), blood urine nitrogen, creatinine, aspartate transaminase (AST), alanine transaminase (ALT), and C-reactive protein. The serum levels of interleukin (IL)-6, IL-10 and tumor necrosis factor (TNF)-α had no significant change.The YYIRT1 may induce muscle damage accompanied by modulation of macrophage polarization toward suppression of M1 phenotype in young football players.

Zinc-Modified Sulfonated Polyetheretherketone Surface with Immunomodulatory Function for Guiding Cell Fate and Bone Regeneration

The cytokines released by immune cells are considered important factors to induce bone tissue regeneration. However, the pathway of those bone-targeting macrophage cytokines induced by biomaterial surface under tissue microenvironment is rarely reported. In this study, the immunomodulatory capability of zinc ions on macrophage polarization and its effects on osteogenic differentiation are investigated. Hence, a layer of zinc ions are incorporated on sulfonated polyetheretherketone (SPEEK) biomaterials by using a customized magnetron sputtering technique. The results reveal that the microenvironment on Zn-coated SPEEK can modulate nonactivated macrophage polarization to an anti-inflammatory phenotype and induce the secretion of anti-inflammatory and osteogenic cytokines. The osteogenic differentiation capability of bone marrow stromal cells (BMSCs) is therefore enhanced, leading to improved osteointegration between the zinc-coated SPEEK and bone tissue. This study verifies that zinc ion is a promising additive in the osteoimmunomodulation process and provides knowledge that may pave the way to develop the next generation of immunomodulatory biomaterials.

Regulation of Macrophage Activation and Polarization by HCC-Derived Exosomal lncRNA TUC339

Exosomes released by cells can serve as vehicles for delivery of biological materials and signals. Long non-coding RNAs (lncRNAs) are non-coding RNAs longer than 200 nt, which roles are increasingly appreciated in various biological content. Tumor-derived exosomal lncRNAs have been implicated as signaling mediators to orchestrate cell function among neighbor tumor cells. However, the role of tumor-derived lncRNAs in cross-talk with environmental macrophages has yet to be explored. In this paper, we demonstrated that hepatocellular carcinoma (HCC) cells–derived exosomes contain elevated levels of lncRNA TUC339 and that HCC-derived exosomes could be taken up by THP-1 cells. In seeking to dissect the biological function of tumor secreting TUC339 in macrophages, we applied loss-of-function and gain-of-function strategies. We observed increased pro-inflammatory cytokine production, increased co-stimulatory molecule expression, and enhanced phagocytosis upon suppression of TUC339 by siRNA in THP-1 cells, and the opposite effect upon over-expression of this lncRNA, which indicates that TUC339 was involved in the regulation of macrophage activation. Moreover, we detected an elevated level of TUC339 in M(IL-4) macrophages as compared to M(IFN-γ + LPS) macrophages and a down-regulation of TUC339 expression during M(IL-4)-to-M(IFN-γ + LPS) repolarization and vice versa. Furthermore, suppression of TUC339 in macrophages diminished the expression of M(IL-4) markers upon IL-4 treatment while overexpression of TUC339 in macrophages enhanced M(IL-4) markers upon IFN-γ + LPS treatment, which suggests a critical function of TUC339 in the regulation of macrophage M1/M2 polarization. Lastly, using microarray analysis, we identified cytokine-cytokine receptor interaction, CXCR chemokine receptor binding, Toll-like receptor signaling, FcγR-mediated phagocytosis, regulation of the actin cytoskeleton, and cell proliferation are related with TUC339 function in macrophages. Our results provide evidence for a novel regulatory function of tumor-derived exosomal lncRNA TUC339 in environmental macrophages and shed light on the complicated interactions between tumor and immune cells through exosomal lncRNAs.

Modular bioinformatics analysis demonstrates that a Toll‑like receptor signaling pathway is involved in the regulation of macrophage polarization

In recent years, an increasing number of studies on the roles of macrophages in tumors, immune responses and metabolism have been published, in which macrophage polarization has been an extensively discussed topic. In the present study, differentially expressed genes in various types of macrophages were analyzed using the Gene Expression Omnibus database. Cluster analysis of differentially expressed genes was conducted, and a protein-protein interaction (PPI) network was constructed. Finally, modular analysis and functional enrichment analysis revealed that a Toll-like receptor (TLR) signaling pathway is involved in the regulation of macrophage polarization. Furthermore, the high-degree proteins in the PPI network that are involved in the molecular regulation of macrophage polarization are closely associated with proteins of the TLR signaling pathway. These results suggested that the TLR signaling pathways may be a principal direction of future research on the regulation of macrophage polarization.

Transcriptomic Analysis of Hepatic Cells in Multicellular Organotypic Liver Models

Liver homeostasis requires the presence of both parenchymal and non-parenchymal cells (NPCs). However, systems biology studies of the liver have primarily focused on hepatocytes. Using an organotypic three-dimensional (3D) hepatic culture, we report the first transcriptomic study of liver sinusoidal endothelial cells (LSECs) and Kupffer cells (KCs) cultured with hepatocytes. Through computational pathway and interaction network analyses, we demonstrate that hepatocytes, LSECs and KCs have distinct expression profiles and functional characteristics. Our results show that LSECs in the presence of KCs exhibit decreased expression of focal adhesion kinase (FAK) signaling, a pathway linked to LSEC dedifferentiation. We report the novel result that peroxisome proliferator-activated receptor alpha (PPARα) is transcribed in LSECs. The expression of downstream processes corroborates active PPARα signaling in LSECs. We uncover transcriptional evidence in LSECs for a feedback mechanism between PPARα and farnesoid X-activated receptor (FXR) that maintains bile acid homeostasis; previously, this feedback was known occur only in HepG2 cells. We demonstrate that KCs in 3D liver models display expression patterns consistent with an anti-inflammatory phenotype when compared to monocultures. These results highlight the distinct roles of LSECs and KCs in maintaining liver function and emphasize the need for additional mechanistic studies of NPCs in addition to hepatocytes in liver-mimetic microenvironments.

Osthole inhibits pancreatic cancer progression by directly exerting negative effects on cancer cells and attenuating tumor-infiltrating M2 macrophages

Pancreatic cancer has remained a major cause of cancer-related deaths. A hallmark of pancreatic cancer is extensive stromal reactions, resulting in a unique tumor microenvironment, especially the involvement of macrophages. These tumor-educated cells limit the efficacy of chemotherapy. Therefore, it is necessary to identify an effective treatment strategy. In this study, we aimed to explore the anti-tumor and immunomodulatory effects of osthole on pancreatic cancer. We found that osthole suppressed Panc 02 cell migration and proliferation and induced apoptosis as shown in vitro. Osthole also attenuated the development of pancreatic cancer in mice by inhibiting tumor-infiltrating M2 macrophages in our study. Additionally, osthole inhibited the polarization of primary bone marrow cells into M2 macrophages and inhibited the expression of MRC1, CCL22 and TGF-β in the M2 polarization process in vitro. Detection of the related signaling pathways revealed that osthole exerted immunomodulatory effects on M2 macrophages by down-regulating p-STAT6 and the p-ERK1/2-C/EBP β axis. These results indicated that osthole has effective anti-tumor and immunomodulatory effects on pancreatic cancer.

Coagulation Factor X Regulated by CASC2c Recruited Macrophages and Induced M2 Polarization in Glioblastoma Multiforme

Tumor-associated macrophages (TAMs) constitute a major component of inflammatory cells in the glioblastoma multiforme (GBM) tumor microenvironment. TAMs have been implicated in GBM angiogenesis, invasion, local tumor recurrence, and immunosuppression. Coagulation factor X (FX) is a vitamin K-dependent plasma protein that plays a role in the regulation of blood coagulation. In this study, we first found that FX was highly expressed and positively correlated with TAM density in human GBM. FX exhibited a potent chemotactic capacity to recruit macrophages and promoted macrophages toward M2 subtype polarization, accelerating GBM growth. FX bound to extracellular signal-related kinase (ERK)1/2 and inhibited p-ERK1/2 in GBM cells. FX was secreted in the tumor microenvironment and increased the phosphorylation and activation of ERK1/2 and AKT in macrophages, which may have been responsible for the M2 subtype macrophage polarization. Moreover, although the lncRNA CASC2c has been verified to function as a miR-101 competing endogenous RNA (ceRNA) to promote miR-101 target genes in GBM cells, we first confirmed that CASC2c did not function as a miR-338-3p ceRNA to promote FX expression, and that FX was a target gene of miR-338-3p. CASC2c interacted with and reciprocally repressed miR-338-3p. Both CASC2c and miR-388-3p bound to FX and commonly inhibited its expression and secretion. CASC2c repressed M2 subtype macrophage polarization. Taken together, our findings revealed a novel mechanism highlighting CASC2c and FX as potential therapeutic targets to improve GBM patients by altering the GBM microenvironment.

A designer self-assembled supramolecule amplifies macrophage immune responses against aggressive cancer

Effectively activating macrophages that can ‘eat’ cancer cells is challenging. In particular, cancer cells secrete macrophage colony stimulating factor (MCSF), which polarizes tumour-associated macrophages from an antitumour M1 phenotype to a pro-tumourigenic M2 phenotype. Also, cancer cells can express CD47, an ‘eat me not’ signal that ligates with the signal regulatory protein alpha (SIRPα) receptor on macrophages to prevent phagocytosis. Here, we show that a supramolecular assembly consisting of amphiphiles inhibiting the colony stimulating factor 1 receptor (CSF-1R) and displaying SIRPα-blocking antibodies with a drug-to-antibody ratio of 17,000 can disable both mechanisms. The supramolecule homes onto SIRPα on macrophages, blocking the CD47-SIRPα signalling axis while sustainedly inhibiting CSF-1R. The supramolecule enhances the M2-to-M1 repolarization within the tumour microenvironment, and significantly improves antitumour and antimetastatic efficacies in two aggressive animal models of melanoma and breast cancer, with respect to clinically available small-molecule and biologic inhibitors of CSF-1R signalling. Simultaneously blocking the CD47-SIRPα and MCSF-CSF-1R signalling axes may constitute a promising immunotherapy.

First Insights Into the M2 Inflammatory Response After Adipose-Tissue-Derived Stem Cell Injections in Radiation-Injured Muscles

The cutaneous radiation syndrome is the clinical consequence of local high-dose irradiation. It is characterized by extensive inflammation, necrosis, and poor revascularization of the skin, resulting in muscle inflammation and fibrosis. Based on these physiopathological processes, subcutaneous injections of adipose-tissue-derived stem/stromal cells have shown favorable effects on skin-wound healing in a minipig model of cutaneous radiation syndrome, in which muscle fibrosis persisted. Since fibrosis is mainly due to the inflammatory processes that often affect underlying tissues as well, the beneficial effects of intramuscular injections of adipose-tissue-derived stem/stromal cells on tissue recovery were evaluated. The polarization of the inflammatory response of irradiated muscle in a minipig model of cutaneous radiation syndrome was determined after acute local irradiation with 50 Gy gamma rays in a preliminary study (six minipigs). Analysis of the main inflammatory cytokines of the inflammatory response M1 (IL-1-beta and IL-6) and M2 (IL-10 and TGF-beta) by western blotting and in situ hybridization, as well as analysis of CD80/CD206 M1/M2 macrophage-specific markers by immunohistochemistry on minipig muscle samples, was performed 76 d after irradiation. The treatment of irradiated muscles with autologous adipose-tissue-derived stem/stromal cells led to an increase in IL-10 and TGF-beta, being associated with an increase in CD68+/CD206+ cells in this area. This highlights a polarization of M2 in the inflammatory response and indicates that adipose-tissue-derived stem/stromal cells may direct the irradiated tissues' inflammatory response towards a proregenerative outcome.

Insulin-Like Growth Factor-1 Signaling in Lung Development and Inflammatory Lung Diseases

Insulin-like growth factor-1 (IGF-1) was firstly identified as a hormone that mediates the biological effects of growth hormone. Accumulating data have indicated the role of IGF-1 signaling pathway in lung development and diseases such as congenital disorders, cancers, inflammation, and fibrosis. IGF-1 signaling modulates the development and differentiation of many types of lung cells, including airway basal cells, club cells, alveolar epithelial cells, and fibroblasts. IGF-1 signaling deficiency results in alveolar hyperplasia in humans and disrupted lung architecture in animal models. The components of IGF-1 signaling pathways are potentiated as biomarkers as they are dysregulated locally or systemically in lung diseases, whereas data may be inconsistent or even paradoxical among different studies. The usage of IGF-1-based therapeutic agents urges for more researches in developmental disorders and inflammatory lung diseases, as the majority of current data are collected from limited number of animal experiments and are generally less exuberant than those in lung cancer. Elucidation of these questions by further bench-to-bedside researches may provide us with rational clinical diagnostic approaches and agents concerning IGF-1 signaling in lung diseases.

Steroidal alkaloid solanine A from Solanum nigrum Linn. exhibits anti-inflammatory activity in lipopolysaccharide/interferon γ-activated murine macrophages and animal models of inflammation

Solanine A is a novel steroidal alkaloid isolated from Solanum nigrum Linn., a medicinal and edible plant which is widely used for treating various inflammatory diseases. In this study, we found that solanine A markedly suppressed the production of nitric oxide (NO) and prostaglandin E₂ (PGE₂) in lipopolysaccharide/interferon-γ (LPS/IFNγ)-stimulated RAW264.7 cells, and attenuated xylene, carrageenan and agar-induced inflammation in mice. The mRNA levels of inducible nitric oxide synthase (iNOS), cyclooxygenase-2 (COX2), tumor necrosis factor-α (TNF-α), interleukin-6 (IL-6), and -1β (IL-1β), as well as C-X-C motif chemokine ligand-9 (CXCL9), were significantly decreased by solanine A. Furthermore, solanine A also suppressed LPS/IFNγ-induced protein expression of iNOS and COX2. Mechanistically, solanine A inhibited the nuclear translocation of nuclear factor-κB (NF-κB) through the prevention of NF-κB p65 and inhibitory κB-α (IκBα) phosphorylation and IκBα degradation, and it also suppressed activation of extracellular regulated protein kinases (ERK), signal transducers and activators of transcription-1 (STAT1) and serine/threonine protein kinase Akt in LPS/IFNγ-stimulated RAW264.7 macrophages and agar-induced granuloma model in mice. Taken together, solanine A exhibits a potent anti-inflammatory activity in LPS/IFNγ- activated macrophages and animal models of inflammation through inhibition of NF-κB, ERK1/2, Akt and STAT1 signaling pathways, suggesting that solanine A may be a valuable leading compound in the treatment of inflammatory diseases.

Mechanisms of Fish Macrophage Antimicrobial Immunity

Overcrowding conditions and temperatures shifts regularly manifest in large-scale infections of farmed fish, resulting in economic losses for the global aquaculture industries. Increased understanding of the functional mechanisms of fish antimicrobial host defenses is an important step forward in prevention of pathogen-induced morbidity and mortality in aquaculture setting. Like other vertebrates, macrophage-lineage cells are integral to fish immune responses and for this reason, much of the recent fish immunology research has focused on fish macrophage biology. These studies have revealed notable similarities as well as striking differences in the molecular strategies by which fish and higher vertebrates control their respective macrophage polarization and functionality. In this review, we address the current understanding of the biological mechanisms of teleost macrophage functional heterogeneity and immunity, focusing on the key cytokine regulators that control fish macrophage development and their antimicrobial armamentarium.

Multifaceted Roles for Macrophages in Prostate Cancer Skeletal Metastasis

Bone-metastatic prostate cancer is common in men with recurrent castrate-resistant disease. To date, therapeutic focus has largely revolved around androgen deprivation therapy (ADT) and chemotherapy. While second-generation ADTs and combination ADT/chemotherapy approaches have been successful in extending overall survival, the disease remains incurable. It is clear that molecular and cellular components of the cancer-bone microenvironment contribute to the disease progression and potentially to the emergence of therapy resistance. In bone, metastatic prostate cancer cells manipulate bone-forming osteoblasts and bone-resorbing osteoclasts to produce growth and survival factors. While osteoclast-targeted therapies such as bisphosphonates have improved quality of life, emerging data have defined important roles for additional cells of the bone microenvironment, including macrophages and T cells. Disappointingly, early clinical trials with checkpoint blockade inhibitors geared at promoting cytotoxic T cell response have not proved as promising for prostate cancer compared to other solid malignancies. Macrophages, including bone-resident osteomacs, are a major component of the bone marrow and play key roles in coordinating normal bone remodeling and injury repair. The role for anti-inflammatory macrophages in the progression of primary prostate cancer is well established yet relatively little is known about macrophages in the context of bone-metastatic prostate cancer. The focus of the current review is to summarize our knowledge of macrophage contribution to normal bone remodeling and prostate-to-bone metastasis, while also considering the impact of standard of care and targeted therapies on macrophage behavior in the tumor-bone microenvironment.

Hematopoietic stem cell loss and hematopoietic failure in severe aplastic anemia is driven by macrophages and aberrant podoplanin expression

Severe aplastic anemia (SAA) results from profound hematopoietic stem cell loss. T cells and interferon gamma (IFNγ) have long been associated with SAA, yet the underlying mechanisms driving hematopoietic stem cell loss remain unknown. Using a mouse model of SAA, we demonstrate that IFNγ-dependent hematopoietic stem cell loss required macrophages. IFNγ was necessary for bone marrow macrophage persistence, despite loss of other myeloid cells and hematopoietic stem cells. Depleting macrophages or abrogating IFNγ signaling specifically in macrophages did not impair T-cell activation or IFNγ production in the bone marrow but rescued hematopoietic stem cells and reduced mortality. Thus, macrophages are not required for induction of IFNγ in SAA and rather act as sensors of IFNγ. Macrophage depletion rescued thrombocytopenia, increased bone marrow megakaryocytes, preserved platelet-primed stem cells, and increased the platelet-repopulating capacity of transplanted hematopoietic stem cells. In addition to the hematopoietic effects, SAA induced loss of non-hematopoietic stromal populations, including podoplanin-positive stromal cells. However, a subset of podoplanin-positive macrophages was increased during disease, and blockade of podoplanin in mice was sufficient to rescue disease. Our data further our understanding of disease pathogenesis, demonstrating a novel role for macrophages as sensors of IFNγ, thus illustrating an important role for the microenvironment in the pathogenesis of SAA.

ER-localized protein-Herpud1 is a new mediator of IL-4-induced macrophage polarization and migration

ER-localized proteins have been reported function in endoplasmic reticulum, unfolded protein degradation and destruction of misfolded proteins by the ER-associated protein degradation (ERAD) system, but their function in the chemotaxis of macrophage cells remained un-addressed. Here, we showed that ER protein with ubiquitin like domain 1(Herpud1) was upregulated in IL-4-treated M2 macrophage cells and its expression pattern was similar with macrophage polarization markers, such as Arg1, Mrc1 and Fizz1. Inhibition of Herpud1 by using specific target shRNA decreased these marker's expression at mRNA and protein level in IL-4-treated or -untreated M2 macrophage cells. IL-4 treatment promoted M2 macrophage cell migration and polarization, but this promotion was weakened by Herpud1 depletion and we got similar results by inhibition of ER stress response with chemical molecule 4-phenylbutyric acid (4-PBA) in IL-4-treated or untreated-M2 macrophage cells with Herpud1 overexpression. These results indicated that depending on ER-associated protein degradation (ERAD) to help unfolded protein degradation or destruction is not the only function of Herpud1 and acting as a mediator of IL-4 induced macrophage activation and polarization maybe another unrevealed function, elucidating the role of Herpud1-associated M2 macrophage cell polarization and activation are helpful for exploration the function of macrophage cells in immune response.

Clinical Effects of CpG-Based Treatment on the Efficacy of Hepatocellular Carcinoma by Skewing Polarization Toward M1 Macrophage from M2

OBJECTIVE

This study aims to explore the clinical efficacy of CpG-based therapy for treating hepatocellular carcinoma (HCC) by skewing polarization toward M1 macrophage from M2.

METHODS

Pulmonary metastasis rate, overall survival time, and remission rate of 10 patients with HCC treated with transcatheter arterial chemoembolization (TACE) combined with CpG therapy and 10 age-, gender-, and TNM₀-matched patients treated with TACE (control group) were compared.

RESULTS

No pulmonary metastasis rate was 70% in the combined treatment group and 40% in the control group, respectively; and the differences between the two groups were statistically significant (p < 0.05). Median overall survival time was 22 months in the combined treatment group, compared with 6.65 months in the control group (p < 0.05). Remission rate in the combined treatment group (70%) was higher than in the control group (30%), but the differences between these two groups were not statistically significant (p > 0.05).

CONCLUSION

Compared with TACE, CpG combined with TACE can decrease the pulmonary metastasis rate. This combined therapy can also improve the overall survival time of patients.

Renal protective effect of Paeoniflorin by inhibition of JAK2/STAT3 signaling pathway in diabetic mice

Paeoniflorin is the main bioactive components of the root of P.lactiflora Pall., and has been widely used as an anti-inflammation and immunomodulatory agent. However, the effect and mechanisms of Paeoniflorin in diabetic nephropathy (DN) remains to be elucidated. In the present study, streptozotocin (STZ)-induced type 1 diabetic mice model was used to investigate the protective effect of Paeoniflorin and the role of the Janus kinase (JAK) 2/signal transducer (STAT) 3 signaling pathway on DN. After treatment with Paeoniflorin at a dose of 25, 50 and 100 mg/kg once a day for 12 weeks, both the functional and histological damage to diabetic mice kidney had been attenuated significantly. Additionally, these reno-protective effects were associated with alleviating macrophage infiltration and inflammatory factors expression as well as suppression of the JAK2/STAT3 signaling pathway. These data reveal that Paeoniflorin attenuates renal lesions in diabetic mice and these protective effects may be associated with the prevention of macrophage infiltration and inhibition of the JAK2/STAT3 signaling pathway.

IPSC‑MSC inhibition assessment in Raw 264.7 cells following oxygen and glucose deprivation reveals a distinct function for cardiopulmonary resuscitation

Hypoxia is a serious stress state. The nervous system is less tolerant to hypoxia, and cell death due to hypoxia is irreversible. With the incidence of cardiovascular disease gradually increasing, the sudden cardiac death rate is additionally increasing. Although cardiopulmonary resuscitation (CPR) is an important development, recovery is frequently poor. In a successful recovery population, ~40% of the population was in a vegetative state or subsequently succumbed to their condition, and ~20% had brain damage. Therefore, the recovery of the brain is of particular importance in CPR. Immune disorders are one of the major mechanisms of cerebral resuscitation following CPR. Studies have demonstrated that induced pluripotent stem cell-derived mesenchymal stem cells (IPSC-MSCs) have a strong immune regulatory effect during tissue repair and anti-inflammatory effects. IPSC-MSCs may inhibit the inflammatory response by means of the inflammatory reaction network to improve brain function following CPR, although the cellular and molecular mechanisms remain unclear. Macrophages are a bridge between innate immune and specific immune responses in the body; therefore, it was hypothesized that macrophages may be the important effector cell of the role of IPSC-MSCs in improving brain function following recovery of spontaneous respiration and circulation subsequent to cardiopulmonary resuscitation. In the present study, IPSC-MSCs were applied to the oxygen and glucose deprivation (OGD) model. It was observed that intervention with IPSC-MSCs was able to alter the polarization direction of macrophages. The difference in the proportions of M1 and M2 macrophages was statistically significant at 6, 12, 24 and 48 h (P=0.037, P<0.05) in the OGD + IPSC-MSCs group (M1, 33.48±5.6%; M2, 50.84±6.9%) and in the OGD group (M1, 83.55±7.3%; M2, 11.41±3.2%), and over time this trend was more obvious. The polarization direction of macrophages is associated with the neurogenic locus notch homolog protein 1 (Notch-1) signaling pathway. In conclusion, it was observed that IPSC-MSCs may be associated with altered macrophage polarization, which may be accomplished by inhibiting the Notch-1 signaling pathway.

The innate immune response to ischemic injury: a multiscale modeling perspective

Background

Cell death as a result of ischemic injury triggers powerful mechanisms regulated by germline-encoded Pattern Recognition Receptors (PRRs) with shared specificity that recognize invading pathogens and endogenous ligands released from dying cells, and as such are essential to human health. Alternatively, dysregulation of these mechanisms contributes to extreme inflammation, deleterious tissue damage and impaired healing in various diseases. The Toll-like receptors (TLRs) are a prototypical family of PRRs that may be powerful anti-inflammatory targets if agents can be designed that antagonize their harmful effects while preserving host defense functions. This requires an understanding of the complex interactions and consequences of targeting the TLR-mediated pathways as well as technologies to analyze and interpret these, which will then allow the simulation of perturbations targeting specific pathway components, predict potential outcomes and identify safe and effective therapeutic targets.

Results

We constructed a multiscale mathematical model that spans the tissue and intracellular scales, and captures the consequences of targeting various regulatory components of injury-induced TLR4 signal transduction on potential pro-inflammatory or pro-healing outcomes. We applied known interactions to simulate how inactivation of specific regulatory nodes affects dynamics in the context of injury and to predict phenotypes of potential therapeutic interventions. We propose rules to link model behavior to qualitative estimates of pro-inflammatory signal activation, macrophage infiltration, production of reactive oxygen species and resolution. We tested the validity of the model by assessing its ability to reproduce published data not used in its construction.

Conclusions

These studies will enable us to form a conceptual framework focusing on TLR4-mediated ischemic repair to assess potential molecular targets that can be utilized therapeutically to improve efficacy and safety in treating ischemic/inflammatory injury.