Temporal phenotypic features distinguish polarized macrophages in vitro

Partners in health and disease: pineal gland and purinergic signalling

In mammal's pineal glands, ATP interacts with the high-affinity P2Y1 and the low-affinity P2X7 receptors. ATP released from sympathetic nerve terminals potentiates noradrenaline-induced serotonin N-acetyltransferase (Snat) transcription, N-acetylserotonin (NAS), and melatonin (MLT) synthesis. Circulating melatonin impairs the expression of adhesion molecules in endothelial cells, blocking the migration of leukocytes. Acute defence response induced by pathogen- and danger/damage-associated molecular patterns (PAMPs and DAMPs) triggers the NF-κB pathway in pinealocytes and blocks the transcription of Snat. Therefore, the darkness hormone is not released, and neutrophils and monocytes migrate to the lesion sites. ATP released in high amounts from apoptotic and death cells was considered a DAMP, and the blockage of P2X7 receptors was tested as a new class of drugs for treating brain damage. However, this is not a simple equation. High ATP injected in a lateral ventricle blocked MLT, but not NAS, synthesis as it impairs the transcription of acetyl serotonin N-methyltransferase. NAS is released in the plasma and the cerebral spinal fluid. NAS also blocks the rolling and adhesion of leukocytes to endothelial cells. Otherwise, it is metabolised specifically in each brain area to provide the requested concentration of MLT as a neuroprotector. As observed in physiological conditions, high extracellular ATP, different from the other DAMPs, reports the environmental light/dark cycle rhythm because NAS substitutes MLT as the nocturnal chemical indicator, the darkness hormone. Thus, blocking the P2X7R should not be considered a universal therapy for improving acute strokes, as MLT and ATP are partners in health and disease.

Macrophage efferocytosis in health and disease

Creating cellular homeostasis within a defined tissue typically relates to the processes of apoptosis and efferocytosis. A great example here is cell debris that must be removed to prevent unwanted inflammatory responses and then reduce autoimmunity. In view of that, defective efferocytosis is often assumed to be responsible for the improper clearance of apoptotic cells (ACs). This predicament triggers off inflammation and even results in disease development. Any disruption of phagocytic receptors, molecules as bridging groups, or signaling routes can also inhibit macrophage efferocytosis and lead to the impaired clearance of the apoptotic body. In this line, macrophages as professional phagocytic cells take the lead in the efferocytosis process. As well, insufficiency in macrophage efferocytosis facilitates the spread of a wide variety of diseases, including neurodegenerative diseases, kidney problems, types of cancer, asthma, and the like. Establishing the functions of macrophages in this respect can be thus useful in the treatment of many diseases. Against this background, this review aimed to recapitulate the knowledge about the mechanisms related to macrophage polarization under physiological or pathological conditions, and shed light on its interaction with efferocytosis.

M1 to M2 induction in macrophages using a retinoic acid-releasing mesenchymal stem cell scaffold

BACKGROUND

Modulation of macrophage polarization is required for effective tissue repair and regenerative therapies. Therapeutic modulation of macrophages from an inflammatory M1 to a fibrotic M2 phenotype could help in diseases, such as chronic wounds, which are stalled in a prolonged and heightened inflammatory stage within the wound healing process.

OBJECTIVE

This study evaluates the efficiency of a pullulan/gelatin nanofiber scaffold loaded with retinoic acid (RA) and adipose-derived mesenchymal stem cells (ASCs) to modulate M1 to M2 anti-inflammatory transition.

METHODS

Scaffolds were fabricated by electrospinning, and crosslinked using ethylene glycol diglycidyl ether (EGDE). Exposure of RA and/or ASCs to cultured macrophages have been shown to promote M1 to M2 transition. Pullulan was chosen as a scaffold material due to its ability to quench reactive oxygen species, key signaling molecules that play an important role in the progression of inflammation, as well as for its excellent mechanical properties. Gelatin was chosen as an additional scaffold component due to the presence of cell-binding motifs and its biocompatibility. Scaffold compositions examined were 75:25 and 50:50, pullulan:gelatin. The scaffolds were crosslinked in 1:70 and 1:50 EGDE:EtOH. The scaffold composition was determined via FTIR. For the present study, the 75:25 pullulan:gelatin crosslinked with 1:70 EGDE:EtOH, forming nanofibers 328 ± 47.9 nm (mean ± SD) in diameter, was chosen as the scaffold composition due to its lower degradation and release rate, which allows a sustained delivery of RA.

RESULTS

The scaffold composition degraded to approximately 80% after 14 days, with approximately 38% of the drug released after 7 days. THP-1 monocytic cells were induced into a M1 macrophage phenotype through stimulation with lipopolysaccharide (LPS) and gamma interferon (IFN-γ). These M1 macrophages were the exposed to scaffolds loaded with RA and ASCs, to induce differentiation to an M2 phenotype.

CONCLUSION

Gene expression quantitation by qPCR showed a reduction of M1 biomarkers, tumor necrosis factor alpha (TNFα) and interleukin 1β (IL1β), and an increase of M2 biomarker CCL22 after 2 days of exposure, suggesting successful M1 to M2 transition.

Chemokine CCL7 mediates trigeminal neuropathic pain via CCR2/CCR3-ERK pathway in the trigeminal ganglion of mice

BACKGROUND

Chemokine-mediated neuroinflammation plays an important role in the pathogenesis of neuropathic pain. The chemokine CC motif ligand 7 (CCL7) and its receptor CCR2 have been reported to contribute to neuropathic pain via astrocyte-microglial interaction in the spinal cord. Whether CCL7 in the trigeminal ganglion (TG) involves in trigeminal neuropathic pain and the involved mechanism remain largely unknown.

METHODS

The partial infraorbital nerve transection (pIONT) was used to induce trigeminal neuropathic pain in mice. The expression of Ccl7, Ccr1, Ccr2, and Ccr3 was examined by real-time quantitative polymerase chain reaction. The distribution of CCL7, CCR2, and CCR3 was detected by immunofluorescence double-staining. The activation of extracellular signal-regulated kinase (ERK) was examined by Western blot and immunofluorescence. The effect of CCL7 on neuronal excitability was tested by whole-cell patch clamp recording. The effect of selective antagonists for CCR1, CCR2, and CCR3 on pain hypersensitivity was checked by behavioral testing.

RESULTS

Ccl7 was persistently increased in neurons of TG after pIONT, and specific inhibition of CCL7 in the TG effectively relieved pIONT-induced orofacial mechanical allodynia. Intra-TG injection of recombinant CCL7 induced mechanical allodynia and increased the phosphorylation of ERK in the TG. Incubation of CCL7 with TG neurons also dose-dependently enhanced the neuronal excitability. Furthermore, pIONT increased the expression of CCL7 receptors Ccr1, Ccr2, and Ccr3. The intra-TG injection of the specific antagonist of CCR2 or CCR3 but not of CCR1 alleviated pIONT-induced orofacial mechanical allodynia and reduced ERK activation. Immunostaining showed that CCR2 and CCR3 are expressed in TG neurons, and CCL7-induced hyperexcitability of TG neurons was decreased by antagonists of CCR2 or CCR3.

CONCLUSION

CCL7 activates ERK in TG neurons via CCR2 and CCR3 to enhance neuronal excitability, which contributes to the maintenance of trigeminal neuropathic pain. CCL7-CCR2/CCR3-ERK pathway may be potential targets for treating trigeminal neuropathic pain.

Effects of Stromal Cell Conditioned Medium and Antipurinergic Treatment on Macrophage Phenotype

The immunomodulatory capacity of the human mesenchymal stromal cell (MSC) secretome has been a critical driver for the development of cell-free MSC products, such as conditioned medium (CM), for regenerative medicine applications. This is particularly true as cell-free MSC products present several advantages over direct autologous or allogeneic MSC delivery with respect to safety, manufacturability, and defined potency. Recently, significant effort has been placed into creating novel MSC CM formulations with an immunomodulatory capacity tailored for specific regenerative contexts. For instance, the immunoregulatory nature of MSC CM has previously been tuned through a number of cytokine-priming strategies. Herein, we propose an alternate method to tailor the immunomodulatory "phenotype" of cytokine-primed MSC CM through coupling with the pharmacological agent, suramin. Suramin interferes with the signaling of purines including extracellular adenosine triphosphate (ATP), which plays a critical role in the activation of the innate immune system after injury. Toward this end, human THP-1-derived macrophages were activated to a proinflammatory phenotype and treated with (1) unprimed/native MSC CM, (2) interferon-γ/tumor necrosis factor α-primed MSC CM (primed CM), (3) suramin alone, or (4) primed MSC CM and suramin (primed CM/suramin). Markers of key macrophage functions-cytokine secretion, autophagy, oxidative stress modulation, and activation/migration-were assessed. Consistent with previous literature, primed CM elevated macrophage secretion of several proinflammatory and pleiotropic cytokines relative to native CM; whereas addition of suramin imparted consistent shifts in terms of TNFα (↓), interleukin-10 (↓), and hepatocyte growth factor (↑) irrespective of CM. In addition, both primed CM and suramin, individually and combined, increased reactive oxygen species production relative to native CM, and addition of suramin to primed CM shifted levels of CX3CL1, a factor involved in ATP-associated macrophage regulation. Varimax rotation assessment of the secreted cytokine profiles confirmed that primed CM/suramin resulted in a THP-1 phenotypic shift away from the lipopolysaccharide-activated proinflammatory state that was distinct from that of primed CM or native CM alone. This altered primed CM/suramin-associated phenotype may prove beneficial for healing in certain regenerative contexts. These results may inform future work coupling antipurinergic treatments with MSC-derived therapies in regenerative medicine applications.

SNPs in 3'UTR miRNA Target Sequences Associated with Individual Drug Susceptibility

The complementary interaction of microRNAs (miRNAs) with their binding sites in the 3'untranslated regions (3'UTRs) of target gene mRNAs represses translation, playing a leading role in gene expression control. MiRNA recognition elements (MREs) in the 3'UTRs of genes often contain single nucleotide polymorphisms (SNPs), which can change the binding affinity for target miRNAs leading to dysregulated gene expression. Accumulated data suggest that these SNPs can be associated with various human pathologies (cancer, diabetes, neuropsychiatric disorders, and cardiovascular diseases) by disturbing the interaction of miRNAs with their MREs located in mRNA 3'UTRs. Numerous data show the role of SNPs in 3'UTR MREs in individual drug susceptibility and drug resistance mechanisms. In this review, we brief the data on such SNPs focusing on the most rigorously proven cases. Some SNPs belong to conventional genes from the drug-metabolizing system (in particular, the genes coding for cytochromes P450 (CYP 450), phase II enzymes (SULT1A1 and UGT1A), and ABCB3 transporter and their expression regulators (PXR and GATA4)). Other examples of SNPs are related to the genes involved in DNA repair, RNA editing, and specific drug metabolisms. We discuss the gene-by-gene studies and genome-wide approaches utilized or potentially utilizable to detect the MRE SNPs associated with individual response to drugs.

Macrophage subsets and their role: co-relation with colony-stimulating factor-1 receptor and clinical relevance

Macrophages are one of the first innate immune cells to reach the site of infection or injury. Diverse functions from the uptake of pathogen or antigen, its killing, and presentation, the release of pro- or anti-inflammatory cytokines, activation of adaptive immune cells, clearing off tissue debris, tissue repair, and maintenance of tissue homeostasis have been attributed to macrophages. Besides tissue-resident macrophages, the circulating macrophages are recruited to different tissues to get activated. These are highly plastic cells, showing a spectrum of phenotypes depending on the stimulus received from their immediate environment. The macrophage differentiation requires colony-stimulating factor-1 (CSF-1) or macrophage colony-stimulating factor (M-CSF), colony-stimulating factor-2 (CSF-2), or granulocyte–macrophage colony-stimulating factor (GM-CSF) and different stimuli activate them to different phenotypes. The richness of tissue macrophages is precisely controlled via the CSF-1 and CSF-1R axis. In this review, we have given an overview of macrophage origin via hematopoiesis/myelopoiesis, different phenotypes associated with macrophages, their clinical significance, and how they are altered in various diseases. We have specifically focused on the function of CSF-1/CSF-1R signaling in deciding macrophage fate and the outcome of aberrant CSF-1R signaling in relation to macrophage phenotype in different diseases. We further extend the review to briefly discuss the possible strategies to manipulate CSF-1R and its signaling with the recent updates.

Cut loose TIMP-1: an emerging cytokine in inflammation

Appreciation of the entire biological impact of an individual protein can be hampered by its original naming based on one function only. Tissue inhibitor of metalloproteinases-1 (TIMP-1), mostly known for its eponymous function to inhibit metalloproteinases, exhibits only a fraction of its cellular effects via this feature. Recently, TIMP-1 emerged as a potent cytokine acting via various cell-surface receptors, explaining a so-far under-appreciated role of TIMP-1-mediated signaling on immune cells. This, at least partly, resolved why elevated blood levels of TIMP-1 correlate with progression of numerous inflammatory diseases. Here, we emphasize the necessity of unbiased name-independent recognition of structure-function relationships to properly appreciate the biological potential of TIMP-1 and other cytokines in complex physiological processes such as inflammation.

Macrophage-Mediated Inflammation in Skin Wound Healing

Macrophages are key immune cells that respond to infections, and modulate pathophysiological conditions such as wound healing. By possessing phagocytic activities and through the secretion of cytokines and growth factors, macrophages are pivotal orchestrators of inflammation, fibrosis, and wound repair. Macrophages orchestrate the process of wound healing through the transitioning from predominantly pro-inflammatory (M1-like phenotypes), which present early post-injury, to anti-inflammatory (M2-like phenotypes), which appear later to modulate skin repair and wound closure. In this review, different cellular and molecular aspects of macrophage-mediated skin wound healing are discussed, alongside important aspects such as macrophage subtypes, metabolism, plasticity, and epigenetics. We also highlight previous studies demonstrating interactions between macrophages and these factors for optimal wound healing. Understanding and harnessing the activity and capability of macrophages may help to advance new approaches for improving healing of the skin.

CCL7 as a novel inflammatory mediator in cardiovascular disease, diabetes mellitus, and kidney disease

Chemokines are key components in the pathology of chronic diseases. Chemokine CC motif ligand 7 (CCL7) is believed to be associated with cardiovascular disease, diabetes mellitus, and kidney disease. CCL7 may play a role in inflammatory events by attracting macrophages and monocytes to further amplify inflammatory processes and contribute to disease progression. However, CCL7-specific pathological signaling pathways need to be further confirmed in these chronic diseases. Given the multiple redundancy system among chemokines and their receptors, further experimental and clinical studies are needed to clarify whether direct CCL7 inhibition mechanisms could be a promising therapeutic approach to attenuating the development of cardiovascular disease, diabetes mellitus, and kidney disease.

The extended effect of adsorbed damage-associated molecular patterns and Toll-like receptor 2 signaling on macrophage-material interactions

Implanted biomaterials elicit an immune-mediated foreign body reaction (FBR) that results in the fibrous encapsulation of the implant and can critically impact the performance of some implants. Consequently, understanding the molecular mechanisms that underpin cell-materials interactions that initiate biomaterial-induced inflammation and fibrosis is critical to improving the performance of biomaterial implants negatively impacted by the FBR. Damage-associated molecular patterns (DAMPs) are endogenous mediators of inflammation that are released upon tissue injury and induce sterile inflammation via Toll-like receptors (TLRs). However, the prevalence of DAMPs within the adsorbed protein layer on material surfaces and their role mediating cell-material interactions is unclear. Previously, our group demonstrated that molecules in fibroblast lysates adsorbed to various biomaterials and induced a potent TLR2-dependent inflammatory response in macrophages at 24 h. In this study, we examined the extended response of RAW-Blue reporter macrophages on lysate or serum-adsorbed Teflon™ AF surfaces to understand the potential role of adsorbed DAMPs in macrophage-material interactions at later time points. Lysate-conditioned surfaces maintained increased nuclear factor kappa B (NF-κB) and activator protein 1 (AP-1) transcription factor activity and increased expression Regulated upon Activation, Normal T Cell Expressed and Presumably Secreted (RANTES/CCL5) at 72 h and 120 h, compared to FBS-conditioned surfaces. In contrast, monocyte chemoattractant protein 1 (MCP-1/CCL2) was only elevated at 72 h in lysate conditions. Transforming growth factor beta 1 (TGF-β1) secretion was significantly increased on lysate-conditioned surfaces, while conditioned media from macrophages on lysate-conditioned surfaces induced alpha smooth muscle actin (αSMA) expression in 3T3 fibroblasts. TLR2 neutralizing antibody treatment significantly decreased NF-κB/AP-1 activity and attenuated TGF-β1 expression at both time points, and MCP-1 and RANTES at 72 h. Finally, multinucleated cells were observed on lysate-conditioned surfaces at 72 h, indicating adsorbed DAMPs induced a fusion permissive environment for adherent macrophages. This study demonstrates that adsorbed DAMPs continue to influence macrophage-material responses beyond the initial 24-h period and maintain a pro-inflammatory and fibrotic response that models aspects of the early FBR. Furthermore, the transient inhibition of TLR2 continued to exert an effect at these later time points, suggesting TLR2 may be a target for therapeutic interventions in FBR.

Development of Aging-Related Emphysematous and Lymphoma-Like Lesions is Enhanced by the Lack of Secretoglobin 3A2 in Mouse Lungs

Background

Secretoglobin (SCGB) 3A2 is a novel bioactive molecule with anti-inflammatory and anti-fibrotic activities. SCGB3A2 also promotes the maturation of bronchial divergence and the lungs during embryonic development. However, much remains unknown concerning the roles of SCGB3A2 in diseases associated with aging.

Methods

The lungs of Scgb3a2-knockout (KO) mice and their wild-type (WT) littermates were subjected to histological analysis, Victoria blue staining to evaluate of elastic fibers, and lung morphometric analysis during the postnatal period (birth to 8 weeks) and during aging (8 weeks to 2 years). Their spleens were also histologically evaluated. The expression of lung surfactant protein (SP) mRNAs was examined by quantitative reverse transcriptase-polymerase chain reaction. RNA sequencing (RNAseq) analysis was performed on 3-month-old KO and WT mouse lungs.

Results

The alveolar spaces of KO mice continuously expanded between 0.5 and 2 years of age, accompanied by increases of the mean linear intercept and destructive index. KO mouse lungs displayed inflammation associated with lymphocyte aggregate starting at 1 year of age, and the inflammation was worse than that of WT mouse lungs. A high number of lymphoma-like cells were presented in 2-year-old KO mouse lungs. White pulp fusion was detected in the spleens of both WT and KO mice older than 0.5 years; however, the fusion was more severe in KO mice than in WT mice. The expression of surfactant protein (SP)-A, SP-B, SP-C, and SP-D mRNAs in KO mouse lungs decreased with age, and after 1 year of age, the expression of most SPs was significantly lower in KO mice than in WT mice. RNAseq demonstrated that the expression of immune system-related genes was highly altered in KO mouse lungs.

Conclusion

SCGB3A2 may be required for maintaining homeostasis and immune activity in the lungs during aging. SCGB3A2 deficiency might increase the risk of emphysema of the lung.

Intratumoral administration of the antisecretory peptide AF16 cures murine gliomas and modulates macrophage functions

Glioblastoma has remained the deadliest primary brain tumor while its current therapy offers only modest survival prolongation. Immunotherapy has failed to record notable benefits in routine glioblastoma treatment. Conventionally, immunotherapy relies on T cells as tumor-killing agents; however, T cells are outnumbered by macrophages in glioblastoma microenvironment. In this study, we explore the effect of AF16, a peptide from the endogenous antisecretory factor protein, on the survival of glioma-bearing mice, the tumor size, and characteristics of the tumor microenvironment with specific focus on macrophages. We elucidate the effect of AF16 on the inflammation-related secretome of human and murine macrophages, as well as human glioblastoma cells. In our results, AF16 alone and in combination with temozolomide leads to cure in immunocompetent mice with orthotopic GL261 gliomas, as well as prolonged survival in immunocompromised mice. We recorded decreased tumor size and changes in infiltration of macrophages and T cells in the murine glioma microenvironment. Human and murine macrophages increased expression of proinflammatory markers in response to AF16 treatment and the same effect was seen in human primary glioblastoma cells. In summary, we present AF16 as an immunomodulatory factor stimulating pro-inflammatory macrophages with a potential to be implemented in glioblastoma treatment protocols.

Macrophage Related Chronic Inflammation in Non-Healing Wounds

Persistent hyper-inflammation is a distinguishing pathophysiological characteristic of chronic wounds, and macrophage malfunction is considered as a major contributor thereof. In this review, we describe the origin and heterogeneity of macrophages during wound healing, and compare macrophage function in healing and non-healing wounds. We consider extrinsic and intrinsic factors driving wound macrophage dysregulation, and review systemic and topical therapeutic approaches for the restoration of macrophage response. Multidimensional analysis is highlighted through the integration of various high-throughput technologies, used to assess the diversity and activation states as well as cellular communication of macrophages in healing and non-healing wound. This research fills the gaps in current literature and provides the promising therapeutic interventions for chronic wounds.

M2a macrophage can rescue proliferation and gene expression of benign prostate hyperplasia epithelial and stroma cells from insulin-like growth factor 1 knockdown

BACKGROUND

Benign prostatic hyperplasia (BPH) is a common disease in elderly men and is often accompanied by chronic inflammation. Macrophages (several subtypes) are the main inflammatory cells that infiltrate the hyperplastic prostate and are found to secrete cytokines and growth factors. The current study aims to explore the effect of M2a macrophages on the development of BPH via insulin-like growth factor 1 (IGF-1).

METHODS

Human prostate tissues, prostate, and monocyte cell lines (WPMY-1, BPH-1, and THP-1) were used. THP-1 was polarized into several subtypes with cytokines. The expression and localization of IGF-1 and M2 macrophages were determined via immunofluorescent staining, quantitative real-time polymerase chain reaction, and Western blot analysis. Flow cytometry and 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) assays were used to investigate the effects of different subtypes of macrophages on prostate cells. IGF-1 in WPMY-1 and BPH-1 cells was silenced and cocultured with or without M2a macrophages. Cell proliferation, apoptosis, cell cycle, epithelial-mesenchymal transition (EMT), and fibrosis processes were examined.

RESULTS

The polarized subtypes of macrophages were verified by amplifying their specific markers. M2a macrophages enhanced prostate cell proliferation more significantly and CD206 was more expressed in hyperplastic prostate. IGF-1 was localized in both epithelial and stromal components of prostate and upregulated in BPH tissues. M2a macrophages expressed more IGF-1 than other subtypes. Knockdown of IGF-1 in WPMY-1 and BPH-1 cells attenuated cell proliferation, promoted cell apoptosis, retarded cell cycle at the G0/G1 phase, and suppressed the EMT process in BPH-1 cells as well as the fibrotic process in WPMY-1 cells, which was reversible when cocultured with M2a macrophages.

CONCLUSION

These data demonstrated that knockdown of IGF-1 expression in cultured BPH epithelial and stromal cells reduces proliferation and increases apoptosis. These effects are reversed by coculture with M2a macrophages.

Pro-Tumorigenic Macrophage Infiltration in Oral Squamous Cell Carcinoma and Possible Macrophage-Aimed Therapeutic Interventions

In Oral Squamous Cell Carcinomas (OSCC), as in other solid tumors, stromal cells strongly support the spread and growth of the tumor. Macrophages in tumors (tumor-associated macrophages or “TAMs”), can swing between a pro-inflammatory and anti-tumorigenic (M1-like TAMs) state or an anti‐inflammatory and pro-tumorigenic (M2-like TAMs) profile depending on the tumor microenvironment cues. Numerous clinical and preclinical studies have demonstrated the importance of macrophages in the prognosis of patients with different types of cancer. Here, our aim was to review the role of M2-like TAMs in the prognosis of patients with OSCC and provide a state of the art on strategies for depleting or reprogramming M2-like TAMs as a possible therapeutic solution for OSCC. The Clinical studies reviewed showed that higher density of CD163+ M2-like TAMs associated with worse survival and that CD206+ M2-TAMs are involved in OSCC progression through epidermal growth factor (EGF) secretion, underlining the important role of CD206 as a marker of OSCC progression and as a therapeutic target. Here, we provide the reader with the current tools, in preclinical and clinical stage, for depleting M2-like TAMs, re-educating them towards M1-like TAMs, and exploiting TAMs as drug delivery vectors.

Lactobacillus plantarum and Bifidobacterium bifidum alleviate dry eye in mice with exorbital lacrimal gland excision by modulating gut inflammation and microbiota

In order to understand the efficacy of probiotics against dry eye syndrome, we selected anti-inflammatory probiotics Lactobacillus plantarum NK151 and Bifidobacterium bifidum NK175, which increased the ratio of IL-10 to TNF-α expression, from the human gut bacteria collection and examined their effects on tear secretion and cornea/conjunctiva inflammation in mice with excision of the unilateral exorbital lacrimal gland and 1% atropine and 0.1% benzalkonium chloride solution (ELA)-induced dry eye. Exposure to ELA significantly reduced tear secretion in mice, assessed by the phenol red thread tear test. However, oral gavage of NK151 and/or NK175 significantly increased ELA-suppressed tear secretion, IL-10 expression, and goblet cell population and decreased the ELA-induced corneal fluorescein-staining score, IL-1β and TNF-α expression in the conjunctiva. They also suppressed ELA-induced myeloperoxidase, IL-1β, and TNF-α expression. In particular, they increased the ratio of IL-10 to TNF-α expression in the colon. Their treatments increased ELA-induced α-diversity reduction to that of the control group and partially restored ELA-shifted β-diversity to that of the control group. Oral gavage of NK151 and/or NK175 reduced ELA-induced Verrucomicrobia and Actinobacteria populations at the phylum level. Furthermore, they reduced ELA-induced Bacteroidaceae, Akkemansiaceae, and AC160630_f populations and increased ELA-suppressed Lactobacillaceae and Muribaculaceae populations at the family level. These gut bacteria populations exhibited significant correlation with the tear secretion volume. In conclusion, NK151 and/or NK175 alleviated dry eye by modulating the expression ratio of pro-inflammatory cytokines such as TNF-α and anti-inflammatory cytokines such as IL-10 and gut microbiota composition.

Cytokine Analysis: A Fresh Perspective

It is recognized that a balance of different cytokines (synergistic versus antagonistic cytokines) determines the outcome in regulation of different actions such as inflammation, polarization, and secretion of macrophages, induction and secretion of T helper cells, and angiogenesis. It is also known that cytokine secretion is highly variable between individuals. These facts red flag the practice of only comparing absolute values of 1 or 2 cytokines in various studies. It is recognized that ratios of opposing functions yield better quantification of the equilibrium than just observing single values. It is the purpose of this article to (1) emphasize the need to measure a combination of cytokines selected in a manner so that ratios of these may be derived to yield more information about the homeostasis in body and (2) to offer a list of synergistic and antagonistic cytokines from which future investigators may select for more meaningful results.

CDllb+ targeted depletion of macrophages negatively affects bone fracture healing

Inflammation is an important part of the fracture repair process which requires osteogenic cells to interact with innate immune cells such as macrophages. All murine macrophages express the F4/80 cell surface marker but they may be further subdivided into two main phenotypes: M1 (proinflammatory) or M2 (anti-inflammatory) based on surface marker expression and function. Macrophages polarize between these two main classes in response to inflammation while differentially regulating the healing process. Studies have shown that F4/80+ cell ablation impairs fracture healing, however, the distinct phenotypes that participate in the early healing process is unclear. We hypothesized that the M1 subtype is essential for the early steps of fracture healing and their depletion would impair fracture repair. To test this hypothesis, M1 (F4/80+/MHCII+/CD86+/CDllb+) macrophages were depleted using a saporin conjugated Mac-1 antibody (Mac1SAP) in vitro using primary macrophages and in vivo using a mouse femur fracture model. Primary macrophages isolated from mice femoral bone marrow were either left undifferentiated (+PBS), differentiated into M1 macrophages (+LPS), or differentiated to M2 macrophages (+IL-4), and then treated with either vehicle or 10 pM Mac1SAP. Samples were collected at day 2 and 5 post Mac1SAP treatment. Macrophage subtypes were identified by flow cytometry and cytokine secretion profiles were quantified using xMAP. For the in vivo model, mice were treated with Mac1SAP 24 h prior to fracture. Femur bone marrow samples were collected and analyzed by flow cytometry, xMAP, immunohistochemistry, MicroCT, and histology. The results demonstrated that Mac1SAP significantly depleted M1 macrophages both in vivo and in vitro. Mac1SAP treatment altered expression of 75% of cytokines in vitro and 30% of cytokines in vivo including IL-6, TNF-a, and IP-10. In both the in vitro and in vivo models, the M1 subtype correlated highly with cytokines G-CSF, IL-1α, IL-6, IL-10, LIX, KC, MCP-1, IP-10, MIP1α, MIP1β, RANTES, IL-9, IL-2 and TNFα. M1 depletion was also found to reduced callus properties at day 14 via microCT analysis. Overall, the data suggests that depletion of M1 macrophages by Mac1SAP treatment alters the cytokine expression profiles during early bone repair which ultimately impairs bone healing.

Macrophage subtype and cytokine expression characterization during the acute inflammatory phase of mouse bone fracture repair

Fracture repair is a complex process requiring heterotypic interactions between osteogenic cells and immune cells. Recent evidence indicates that macrophages are critically involved in fracture repair. Polarized macrophage populations differentially promote and regulate inflammation in other tissues, but little is known about the various macrophage subtypes and their signaling activities following a bone fracture. The authors hypothesized that classically activated (M1 subtype) and alternatively activated (M2 subtype) macrophages are active during the early repair process to initiate and regulate the inflammatory response. To test our hypothesis, bone marrow was collected from intact femurs (naïve group), contralateral and fractured femurs of mice on days 0, 1, 2, 4, and 7 postfracture. Macrophages were isolated from the bone marrow and macrophage subtypes were identified using flow cytometry with antibodies to F4/80, MHC II, CD86, CD11c, and CD40. Bone marrow cytokine levels were measured using xMAP. Flow cytometry revealed dynamic changes in M1 subtype (F4/80+/MHC II+/CD86+), M2 subtype (F4/80+/MHC II-/CD86-), and dendritic cell (DCs; MHCII+/CD11c+/CD40+) populations following fracture as compared to naïve controls. M1 subtype levels were correlated with IL-1α, IL-1ß, IL-2, IL-17, Eotaxin, and MCP-1, while DCs were correlated with IL-6, G-CSF, LIF, KC, and VEGF-A. The results indicate that M1 and M2 subtypes and DCs are recruited to the fracture site early during the repair process and consequently may work in tandem to regulate the inflammatory response required to recruit osteogenic cells needed for later stages of repair.

The effects of macrophages on cardiomyocyte calcium-handling function using in vitro culture models

Following myocardial infarction (MI), myocardial inflammation plays a crucial role in the pathogenesis of MI injury and macrophages are among the key cells activated during the initial phases of the host response regulating the healing process. While macrophages have emerged as attractive effectors in tissue injury and repair, the contribution of macrophages on cardiac cell function and survival is not fully understood due to complexity of the in vivo inflammatory microenvironment. Understanding the key cells involved and how they communicate with one another is of paramount importance for the development of effective clinical treatments. Here, novel in vitro myocardial inflammation models were developed to examine how both direct and indirect interactions with polarized macrophage subsets present in the post-MI microenvironment affect cardiomyocyte function. The indirect model using conditioned medium from polarized macrophage subsets allowed examination of the effects of macrophage-derived factors on stem cell-derived cardiomyocyte function for up to 3 days. The results from the indirect model demonstrated that pro-inflammatory macrophage-derived factors led to a significant downregulation of cardiac troponin T (cTnT) and sarcoplasmic/endoplasmic reticulum calcium ATPase (Serca2) gene expression. It also demonstrated that inhibition of macrophage-secreted matricellular protein, osteopontin (OPN), led to a significant decrease in cardiomyocyte store-operated calcium entry (SOCE). In the direct model, stem cell-derived cardiomyocytes were co-cultured with polarized macrophage subsets for up to 3 days. It was demonstrated that anti-inflammatory macrophages significantly increased cardiomyocyte Ca²⁺ fractional release while macrophages independent of their subtypes led to significant downregulation of SOCE response in cardiomyocytes. This study describes simplified and controlled in vitro myocardial inflammation models, which allow examination of potential beneficial and deleterious effects of macrophages on cardiomyocytes and vise versa. This can lead to our improved understanding of the inflammatory microenvironment post-MI, otherwise difficult to directly investigate in vivo or by using currently available in vitro models.

Targeting the vascular endothelial growth factor receptor-1 by the monoclonal antibody D16F7 to increase the activity of immune checkpoint inhibitors against cutaneous melanoma

The vascular endothelial growth factor receptor-1 (VEGFR-1) is a membrane receptor for VEGF-A, placenta growth factor (PlGF) and VEGF-B that plays a crucial role in melanoma invasiveness, vasculogenic mimicry and tumor-associated angiogenesis. Furthermore, activation of VEGFR-1 is involved in the mobilization of myeloid progenitors from the bone marrow that infiltrate the tumor. Myeloid-derived suppressor cells and tumor-associated macrophages have been involved in tumor progression and resistance to cancer treatment with immune checkpoint inhibitors (ICIs). We have recently demonstrated that the anti-VEGFR-1 monoclonal antibody (mAb) D16F7 developed in our laboratories is able to inhibit melanoma growth in preclinical in vivo models and to reduce monocyte/macrophage progenitor mobilization and tumor infiltration by myeloid cells. Aim of the study was to investigate whether the anti-VEGFR-1 mAb D16F7 affects the activity of protumoral M2 macrophages in vitro in response to PlGF and inhibits the recruitment of these cells to the melanoma site in vivo. Finally, we tested whether, through its multi-targeted action, D16F7 mAb might increase the efficacy of ICIs against melanoma. The results indicated that VEGFR-1 expression is up-regulated in human activated M2 macrophages compared to activated M1 cells and exposure to the D16F7 mAb decreases in vitro chemotaxis of activated M2 macrophages. In vivo treatment with the anti-VEGFR-1 mAb D16F7 of B6D2F1 mice injected with syngeneic B16F10 melanoma cells resulted in tumor growth inhibition associated with the modification of tumor microenvironment that involves a decrease of melanoma infiltration by M2 macrophages and PD-1+ and FoxP3+ cells. These alterations result in increased M1/M2 and CD8+/FoxP3+ ratios, which favor an antitumor and immunostimulating milieu. Accordingly, D16F7 mAb increased the antitumor activity of the ICIs anti-CTLA-4 and anti-PD-1 mAbs. Overall, these data reinforce the role of VEGFR-1-mediated-signalling as a valid target for reducing tumor infiltration by protumoral macrophages and for improving the efficacy of immunotherapy with ICIs.

Impaired functional capacity of polarised neonatal macrophages

Neonatal sepsis is accompanied by impaired apoptotic depletion of monocytes and macrophages (MΦ), aberrant cytokine production, impaired cell metabolism, and sustained inflammation. Macrophage-colony stimulating factor (M-CSF) triggers the differentiation from monocytes into MΦ (MΦ-0). Interleukin-10 (IL10) and Interferon-gamma (IFNy) further differentiate MΦ subpopulations, the anti-inflammatory MΦ-IL10 and the pro-inflammatory MΦ-IFNy subtype. We previously have shown significant differences between adult (PBMΦ) and cord blood (CBMΦ) in the metabolism of all subtypes. To test the hypothesis whether the competence to differentiate monocytes into MΦ-0 and to polarise into MΦ-IFNy and MΦ-IL10 was diminished in CBMΦ as compared to PBMΦ, we polarised monocytes by cultivation with M-CSF for 72 h, followed by stimulation with IFNy or IL10, for 48 h. After flow cytometry based immunotyping, we tested four functions: Phagocytosis of GFP-E. coli, uptake of erythrocytes, T-cell proliferation, induction of regulatory T-cells as well as phosphorylation analysis of AKT and STAT1/STAT3. Phosphorylation of STAT-1 and STAT-3, obligatory to differentiate into MΦ-IFNγ, MΦ-0 and MΦ-IL10, was found to be aberrant in CBMΦ. Whereas infected MΦ-0 showed identical phagocytic indices and intracellular degradation, TLR4-expression, NFkB up-regulation, IL10-, IL6-, and TNFα production of CBMΦ-0 were reduced. In addition, the capacity to bind aged erythrocytes and the consecutive IL10 production was lower in CBMΦ-IL10. Polarised PBMΦ-IFNy and PBMΦ-IL10 expressed higher levels of co-stimulatory receptors (CD80, CD86), had a higher capacity to stimulate T-cells and induced higher amounts of regulatory T-cells (all p < 0.05 vs. corresponding CBMΦ). Hypoxia-inducible-factor-1α (HIF-1α) was stronger expressed in CBMΦ-IFNy and upregulated in infected CBMΦ-0, whereas heme-oxygenase 1 (HO-1) expression was similar to adult PBMΦ. Neonatal MΦ-0, MΦ-IFNy and MΦ-IL10 polarisation is impaired with respect to phenotype and functions tested which may contribute to sustained inflammation in neonatal sepsis.

Deriving a Boolean dynamics to reveal macrophage activation with in vitro temporal cytokine expression profiles

BACKGROUND

Macrophages show versatile functions in innate immunity, infectious diseases, and progression of cancers and cardiovascular diseases. These versatile functions of macrophages are conducted by different macrophage phenotypes classified as classically activated macrophages and alternatively activated macrophages due to different stimuli in the complex in vivo cytokine environment. Dissecting the regulation of macrophage activations will have a significant impact on disease progression and therapeutic strategy. Mathematical modeling of macrophage activation can improve the understanding of this biological process through quantitative analysis and provide guidance to facilitate future experimental design. However, few results have been reported for a complete model of macrophage activation patterns.

RESULTS

We globally searched and reviewed literature for macrophage activation from PubMed databases and screened the published experimental results. Temporal in vitro macrophage cytokine expression profiles from published results were selected to establish Boolean network models for macrophage activation patterns in response to three different stimuli. A combination of modeling methods including clustering, binarization, linear programming (LP), Boolean function determination, and semi-tensor product was applied to establish Boolean networks to quantify three macrophage activation patterns. The structure of the networks was confirmed based on protein-protein-interaction databases, pathway databases, and published experimental results. Computational predictions of the network evolution were compared against real experimental results to validate the effectiveness of the Boolean network models.

CONCLUSION

Three macrophage activation core evolution maps were established based on the Boolean networks using Matlab. Cytokine signatures of macrophage activation patterns were identified, providing a possible determination of macrophage activations using extracellular cytokine measurements.

Siglec-F is induced by granulocyte-macrophage colony-stimulating factor and enhances interleukin-4-induced expression of arginase-1 in mouse macrophages

Siglecs are cell surface lectins that recognize sialic acids and are primarily expressed in hematopoietic cells. Previous studies showed that some Siglecs regulate macrophage function. In the present study, we examined the induction and putative roles of mouse Siglec-F in bone-marrow-derived macrophages in mice. A quantitative RT-PCR analysis showed that the basal expression of Siglec-F was weak in bone-marrow-derived macrophages differentiated by macrophage colony-stimulating factor. However, a 24-hr stimulation with granulocyte-macrophage colony-stimulating factor (GM-CSF) enhanced Siglec-F expression. GM-CSF also enhanced Siglec-F expression in thioglycollate-induced peritoneal macrophages. The inhibition of signal transducer and activator of transcription 5 (STAT5), but not that of phosphoinositide 3-kinase or mitogen-activated protein kinase kinase, significantly reduced the induction of Siglec-F. Interleukin-3, which uses a common β-chain shared with the GM-CSF receptor to stimulate the STAT5 pathway, also enhanced Siglec-F expression. The knockdown of Siglec-F by a specific small interfering RNA enhanced GM-CSF-induced STAT5 phosphorylation, suggesting that Siglec-F down-regulates its own expression upon prolonged GM-CSF stimulation. Furthermore, the knockdown of Siglec-F reduced the STAT6 phosphorylation and expression of arginase-1 in interleukin-4-stimulated macrophages. These results suggest that Siglec-F fine-tunes the immune responses of macrophages.

Immunomodulatory aspects in the progression and treatment of oral malignancy

Inflammation substantially affects the risk of oral malignancy. Pro-inflammatory cytokine, interferon (IFN)-γ, confers anti-tumor activity using several different mechanisms. Conversely, higher expression of interleukin (IL)-17 is associated with worse prognosis. Monocyte chemotactic protein (MCP)-1 correlates positively with poor long-term survival of head and neck squamous cell carcinoma (HNSCC) patients. IL-1α affects cancer associated fibroblasts and macrophages, and promote several malignant phenotypes including immune suppression. Some anti-inflammatory cytokines, including IL-10 and transforming growth factor (TGF)-β, relate to pro-tumoral activities. Among immune checkpoint modulators, programmed death (PD-)1 and PD-ligand (L)1 facilitate oral squamous cell carcinoma (OSCC) cell evasion from immune surveillance, and the expression status of these has a prognostic value. OSCCs contain tumor associated macrophages (TAMs) as major stromal cells of their tumor microenvironment. Among the two distinctive states, M2 macrophages support tumor invasion, metastasis and immune suppression. Crosstalk between TAMs and OSCC or cancer-associated fibroblasts (CAF) plays an important role in the progression of OSCC. Clinical trials with blocking antibodies against IL-1α or melanoma-associated antigens have been reported as therapeutic approaches against OSCCs. The most promising approach activating antitumor immunity is the blockade of PD-1/PD-L1 axis. Manipulating the polarization of pro-tumorigenic macrophages has been reported as a novel therapeutic approach.

Sequential drug delivery to modulate macrophage behavior and enhance implant integration

Macrophages are major upstream regulators of the inflammatory response to implanted biomaterials. Sequential functions of distinct macrophage phenotypes are essential to the normal tissue repair process, which ideally results in vascularization and integration of implants. Improper timing of M1 or M2 macrophage activation results in dysfunctional healing in the form of chronic inflammation or fibrous encapsulation of the implant. Thus, biphasic drug delivery systems that modulate macrophage behavior are an appealing approach to promoting implant integration. In this review, we describe the timing and roles of macrophage phenotypes in healing, then highlight current drug delivery systems designed to sequentially modulate macrophage behavior.

Association of monocyte-to-high density lipoprotein-cholesterol ratio with peripheral neuropathy in patients with Type II diabetes mellitus

Aim: We assessed the association of monocyte count to high-density lipoprotein cholesterol ratio (MHR) with diabetic peripheral neuropathy (DPN) and its role as a marker for identification of high-risk patients for DPN. Methods: A total of 180 patients with Type II diabetes mellitus (T2DM) were enrolled in the study. MHR, erythrocyte sedimentation rate and serum CRP along with other tests for T2DM and DPN were measured. Results: Duration of T2DM (p = 0.013), insulin use (p = 0.006) and serum CRP levels (p = 0.008) were significantly higher in patients with DPN. MHR was similar between groups (p = 0.447). Duration of diabetes (OR: 1.048; p = 0.038) and the serum CRP levels (OR: 1.073; p = 0.026) were found as independent predictors for the presence of DPN, however, MHR was not. Conclusion: Higher MHR indicates an enhanced inflammation and oxidative stress which was not found to be associated with the presence of DPN.

Early Post-stroke Activation of Vascular Endothelial Growth Factor Receptor 2 Hinders the Receptor 1-Dependent Neuroprotection Afforded by the Endogenous Ligand

Vascular endothelial growth factor (VEGF) has long been connected to the development of tissue lesion following ischemic stroke. Contradictory findings either situate VEGF as a promoter of large infarct volumes or as a potential attenuator of damage due to its well documented neuroprotective capability. The core of this discrepancy mostly lies on the substantial number of pleiotropic functions driven by VEGF. Mechanistically, these effects are activated through several VEGF receptors for which various closely related ligands exist. Here, we tested in an experimental model of stroke how the differential activation of VEGF receptors 1 and 2 would modify functional and histological outcomes in the acute phase post-ischemia. We also assessed whether VEGF-mediated responses would involve the modulation of inflammatory mechanisms and how this trophic factor acted specifically on neuronal receptors. We produced ischemic infarcts in adult rats by transiently occluding the middle cerebral artery and induced the pharmacological inhibition of VEGF receptors by i.c.v. administration of the specific VEGFR2 inhibitor SU1498 and the pan-VEGFR blocker Axitinib. We evaluated the neurological performance of animals at 24 h following stroke and the occurrence of brain infarctions analyzed at the gross metabolic and neuronal viability levels. We also assessed the induction of peripheral pro- and anti-inflammatory cytokines in the cerebrospinal fluid and blood and assessed the polarization of activated microglia. Finally, we studied the direct involvement of cortical neuronal receptors for VEGF with in vitro assays of excitotoxic damage. Preferential VEGFR1 activation by the endogenous ligand promotes neuronal protection and prevents the presentation of large volume infarcts that highly correlate with neurological performance, while the concomitant activation of VEGFR2 reduces this effect, even in the presence of exogenous ligand. This process partially involves the polarization of microglia to the state M2. At the cellular level, neurons also responded better to the preferential activation of VEGFR1 when challenged to N-methyl-D-aspartate-induced excitotoxicity. Endogenous activation of VEGFR2 hinders the neuroprotective mechanisms mediated by the activation of VEGFR1. The selective modulation of these concurrent processes might enable the development of therapeutic approaches that target specific VEGFR1-mediated signaling during the acute phase post-stroke.

RNAseq Profiling of Leukocyte Populations in Zebrafish Larvae Reveals a cxcl11 Chemokine Gene as a Marker of Macrophage Polarization During Mycobacterial Infection

Macrophages are phagocytic cells from the innate immune system, which forms the first line of host defense against invading pathogens. These highly dynamic immune cells can adopt specific functional phenotypes, with the pro-inflammatory M1 and anti-inflammatory M2 polarization states as the two extremes. Recently, the process of macrophage polarization during inflammation has been visualized by real time imaging in larvae of the zebrafish. This model organism has also become widely used to study macrophage responses to microbial pathogens. To support the increasing use of zebrafish in macrophage biology, we set out to determine the complete transcriptome of zebrafish larval macrophages. We studied the specificity of the macrophage signature compared with other larval immune cells and the macrophage-specific expression changes upon infection. We made use of the well-established mpeg1, mpx, and lck fluorescent reporter lines to sort and sequence the transcriptome of larval macrophages, neutrophils, and lymphoid progenitor cells, respectively. Our results provide a complete dataset of genes expressed in these different immune cell types and highlight their similarities and differences. Major differences between the macrophage and neutrophil signatures were found within the families of proteinases. Furthermore, expression of genes involved in antigen presentation and processing was specifically detected in macrophages, while lymphoid progenitors showed expression of genes involved in macrophage activation. Comparison with datasets of in vitro polarized human macrophages revealed that zebrafish macrophages express a strongly homologous gene set, comprising both M1 and M2 markers. Furthermore, transcriptome analysis of low numbers of macrophages infected by the intracellular pathogen Mycobacterium marinum revealed that infected macrophages change their transcriptomic response by downregulation of M2-associated genes and overexpression of specific M1-associated genes. Among the infection-induced genes, a homolog of the human CXCL11 chemokine gene, cxcl11aa, stood out as the most strongly overexpressed M1 marker. Upregulation of cxcl11aa in Mycobacterium-infected macrophages was found to require the function of Myd88, a critical adaptor molecule in the Toll-like and interleukin 1 receptor pathways that are central to pathogen recognition and activation of the innate immune response. Altogether, our data provide a valuable data mining resource to support infection and inflammation research in the zebrafish model.

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

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

Effect of tumor microenvironment on pathogenesis of the head and neck squamous cell carcinoma: a systematic review

The tumor microenvironment (TME) is comprised of many different cell populations, such as cancer-associated fibroblasts and various infiltrating immune cells, and non-cell components of extracellular matrix. These crucial parts of the surrounding stroma can function as both positive and negative regulators of all hallmarks of cancer development, including evasion of apoptosis, induction of angiogenesis, deregulation of the energy metabolism, resistance to the immune detection and destruction, and activation of invasion and metastasis. This review represents a summary of recent studies focusing on describing these effects of microenvironment on initiation and progression of the head and neck squamous cell carcinoma, focusing on oral squamous cell carcinoma, since it is becoming clear that an investigation of differences in stromal composition of the head and neck squamous cell carcinoma microenvironment and their impact on cancer development and progression may help better understand the mechanisms behind different responses to therapy and help define possible targets for clinical intervention.

Cellulose nanocrystals modulate alveolar macrophage phenotype and phagocytic function

Nanocellulose is a promising bio-nanomaterial with attractive properties suitable for multiple industrial applications. The increased use of nanocellulose may lead to occupational exposure and negative health outcomes. However, knowledge on its health effects is limited, and while nanocellulose exposure may induce acute inflammatory responses in the lung, the underlying mechanisms are unknown. Alveolar macrophages are key cells in alveolar particle clearance. Their activation and function may be affected by various particles. Here, we investigated the uptake of pristine cellulose nanocrystals (CNC), and their effects on alveolar macrophage polarization and biological function. CNC uptake enhanced the secretion of several cytokines but did not on its own induce a complete macrophage polarization. In presence of macrophage activators, such as LPS/IFNG and IL4/IL13, CNC exposure enhanced the expression of M1 phenotype markers and the secretion of pro-inflammatory cytokines and chemokines, while decreasing M2 markers. CNC exposure also affected the function of activated alveolar macrophages resulting in a prominent cytokine burst and altered phagocytic activity. In conclusion, CNC exposure may result in dysregulation of macrophage activation and function that are critical in inflammatory responses in the lung.

Decreased Expression of TGR5 in Vogt-Koyanagi-Harada (VKH) Disease

Purpose: To investigate the role of G-protein-coupled bile acid receptor-1, Gpbar1 (TGR5) in the pathogenesis of Vogt-Koyanagi-Harada (VKH) disease.Methods: The mRNA level of TGR5, iNOS, Arg1, CD16, and CD206 in macrophages was assayed by real-time PCR. ELISA was used to detect the production of cytokines in cell culture supernatants. The frequencies of CD4⁺IFN-γ⁺ and CD4⁺ IL-17⁺ T cells were tested by flow cytometry.Results: A decreased expression of TGR5 in M1 macrophages was observed in active VKH patients as compared with normal controls. TGR5 stimulation of M1 macrophages with INT-777 caused a shift of the inflammatory M1 toward the anti-inflammatory M2 macrophage subtype. TGR5 activation of macrophages co-cultured with CD4⁺ T cells inhibited Th1 and Th17 polarization, as well as the release of IFN-γ and IL-17 in the culture supernatant.Conclusion: Our results show that a decreased TGR5 expression might contribute to the pathogenesis of VKH disease.

High glucose induces a priming effect in macrophages and exacerbates the production of pro-inflammatory cytokines after a challenge

Introduction

Painful diabetic neuropathy is associated with chronic inflammation, in which macrophages are the key effectors. We utilized an in vitro approach to determine the effects of high glucose on macrophage phenotype.

Materials and methods

We exposed human THP-1 macrophages to normal glucose (5 mM) and a clinically relevant high glucose environment (15 mM) and measured the expression and concentration of molecules associated with a diabetic cellular phenotype.

Results

We found that THP-1 macrophages in high glucose conditions did not influence the basal expression of cyclooxygenase-2, Toll-like receptor-4, or class A scavenger receptor mRNA, or the concentrations of the cytokines interleukin (IL)-6, monocyte chemoattractant protein (MCP)-1, and IL-10, but induced a priming effect on tumor necrosis factor (TNF)-α. Then, we stimulated THP-1 macrophages with a strong pro-inflammatory stimulus lipopolysaccharide (LPS; 5 µg/mL). After stimulation with LPS, we observed an exacerbated increase in TNF-α, IL-6, and MCP-1 concentration in the high glucose condition compared to the normal glucose environment. THP-1 macrophages in high glucose conditions developed tolerance to IL-10 anti-inflammatory effects (TNF-α production) when challenged with LPS.

Conclusion

Our in vitro approach allows the study of macrophages as potential targets for therapeutic purposes since it compares them to primary human macrophages exposed to high glucose and macrophages from patients with diabetes or complications of painful diabetic neuropathy (i.e. ulcers, adipocytes, and pancreas).

Nicotinamide Phosphate Transferase (NAMPT) Increases in Plasma in Patients with Acute Coronary Syndromes, and Promotes Macrophages to M2 Polarization

Atherosclerosis is an inflammatory disease; monocytes and macrophages play an important role in the progression of this disease. However, the mechanisms are not fully understood yet. Nicotinamide phosphate transferase (NAMPT) is the rate limiting enzyme in the synthesis of NAD, but extracellular NAMPT shows the characteristics of cytokines/adipokines, suggesting that it may be a link between metabolism and inflammation. In this study, we compared the expression levels of the NAMPT/NAD+/Sirt1 signaling pathway as well as NAMPT, CRP and IL-6 in the peripheral blood mononuclear cell (PBMC), and plasma in patients with acute coronary syndromes and healthy subjects, and analyzed their association with macrophage polarization. The relationship between eNAMPT and iNAMPT and the polarization of macrophages was analyzed by NAD+, NAMPT blocker, and neutralizing antibody treatment. The results showed that the expression of the NAMPT/NAD+/Sirt1 signaling pathway was up-regulated in the peripheral blood of patients with ACS. Inhibition of iNAMPT expression can reduce M1 polarization; however, there was no significant effect on eNAMPT secretion and M2 polarization. Neutralizing eNAMPT by neutralizing antibodies can reduce M2 polarization and decrease the expression levels of IL-10, IL-13, IL-4 and IL-1ra. The addition of NAD+ in the cell culture supernatant had no significant effect on the polarization of M1 but increased the M2 polarization and the expression levels of IL-10 and IL-1ra. Our findings suggested that NAMPT is involved in the pathogenesis of atherosclerosis; the increased expression of eNAMPT in ACS patients may play a protective role by the up regulation of the NAMPT/NAD+/Sirt1 signaling pathway.

Therapeutic implication of vascular endothelial growth factor receptor-1 (VEGFR-1) targeting in cancer cells and tumor microenvironment by competitive and non-competitive inhibitors

The vascular endothelial growth factor receptor-1 (VEGFR-1) is a tyrosine kinase receptor for VEGF-A, VEGF-B, and placental growth factor (PlGF) ligands that is expressed in endothelial, myelomonocytic and tumor cells. VEGF-B and PlGF exclusively bind to VEGFR-1, whereas VEGF-A also binds to VEGFR-2. At variance with VEGFR-2, VEGFR-1 does not play a relevant role in physiological angiogenesis in the adult, while it is important in tumor-associated angiogenesis. VEGFR-1 and PlGF are expressed in a variety of tumors, promote invasiveness and contribute to resistance to anti-VEGF-A therapy. The currently approved antiangiogenic therapies for the treatment of a variety of solid tumors hamper VEGF-A signaling mediated by both VEGFR-2 and VEGFR-1 [i.e., the monoclonal antibody (mAb) anti-VEGF-A bevacizumab, the chimeric molecule aflibercept and several small molecule tyrosine kinase inhibitors] or exclusively by VEGFR-2 (i.e., the mAb anti-VEGFR-2 ramucirumab). However, molecules that interfere with VEGF-A/VEGFR-2 signaling determine severe adverse effects due to inhibition of physiological angiogenesis and their efficacy is hampered by tumor infiltration of protumoral myeloid cells. Blockade of VEGFR-1 may exert anti-tumor activity by multiple mechanisms: a) inhibition of tumor-associated angiogenesis; b) reduction of myeloid progenitor mobilization and tumor infiltration by VEGFR-1 expressing M2 macrophages, which contribute to tumor progression and spreading; c) inhibition of invasiveness, vasculogenic mimicry and survival of VEGFR-1 positive tumor cells. As a consequence of these properties, molecules targeting VEGFR-1 are expected to produce less adverse effects and to counteract resistance towards anti-VEGF-A therapies. More interestingly, selective VEGFR-1 inhibition might enhance the efficacy of immunotherapy with immune checkpoint inhibitors. In this review, we will examine the experimental evidence available so far that supports targeting VEGFR-1 signal transduction pathway for cancer treatment by competitive inhibitors that prevent growth factor interaction with the receptor and non-competitive inhibitors that hamper receptor activation without affecting ligand binding.

Association between gene polymorphisms and clinical features in idiopathic thrombocytopenic purpura patients

: Immune thrombocytopenic purpura (ITP) is an autoimmune disease in which increased platelet destruction and thrombocytopenia are diagnostic features. In fact, the exact pathogenesis of this disease is still unknown, but genetic changes can be a potential factor in the development of ITP. In this study, the relationship between polymorphisms with platelet destruction has been studied, which leads to decreased platelet count. Relevant literature was identified by a PubMed search (2000-2016) of English language papers using the terms 'ITP', 'polymorphism,' and 'immune system'. The majority of genetic changes (polymorphisms) occur in immune system genes, including interferon (IFN)-γ gene. These changes lead to the dysfunction of immune system and production of pathogenic antibodies against platelet surface glycoproteins such as glycoprotein IIb/IIIa, which eventually result in the destruction of platelets and increasing disease severity. In addition, IFN-γ as well as factors and cytokines involved in megakaryopoiesis, including stem cell factor and interleukin-3 (IL-3), leads to the differentiation of megakaryocytes and platelet release. Considering the fact that IFN-γ is a factor of inflammation and thrombocytopenia, coexistence of this cytokine with thrombopoietin, stem cell factor, and IL-3 results in megakaryocytes differentiation and platelet production, which can be effective to reduce disease severity and increase the platelet counts.

Curcumin reduces Ly6Chi monocyte infiltration to protect against liver fibrosis by inhibiting Kupffer cells activation to reduce chemokines secretion

Curcumin has been reported to have anti-fibrotic effect. However, the anti-fibrotic mechanism of curcumin for liver fibrosis remains obscure. In the presenting study, we aimed to investigate whether curcumin reduce chemokines secretion by inhibiting kupffer cells (KCs) activation to decrease Ly6C^hi monocyte infiltration in the treatment of liver fibrosis. Liver fibrosis was induced by intraperitoneal carbon tetrachloride (CCl₄)-injection in mice. Mice in curcumin group received curcumin treatment by gavage. Pretreatment with curcumin significantly protected mice from liver inflammation and fibrosis. Compared to CCl₄ group, mice in the curcumin group showed significantly less intrahepatic infiltration of Ly6C^hi monocytes, but no difference of other leucocyte subtypes. Moreover, curcumin significantly reduced Ly6C^hi monocytes associated pro-inflammatory and pro-fibrogenic cytokines, which was in line with the decreased numbers of intrahepatic Ly6C^hi monocytes. Further study found that curcumin is able to decrease KCs activation and monocyte chemokines, which explains why curcumin can reduce Ly6C^hi monocytes infiltration during liver fibrosis. In vitro, we discovered that curcumin prevents the polarization of macrophages toward M1 and reduces monocyte chemokines secretion, which is involved with ERK1/2 and p38 pathways. Taken together, for the first time, we verified that curcumin can reduce chemokines secretion by inhibiting KCs activation to decrease Ly6C^hi monocyte infiltration in the treatment of liver fibrosis. These results suggested that curcumin may be considered a promising candidate in the prevention and treatment of liver fibrosis.

Transcriptome profile of rat genes in bone marrow-derived macrophages at different activation statuses by RNA-sequencing

The underlying mechanisms of macrophage polarization have been detected by genome-wide transcriptome analysis in a variety of mammals. However, the transcriptome profile of rat genes in bone marrow-derived macrophages (BMM) at different activation statuses has not been reported. Therefore, we performed RNA-Sequencing to identify gene expression signatures of rat BMM polarized in vitro with different stimuli. The differentially expressed genes (DEGs) among unactivated (M0), classically activated pro-inflammatory (M1), and alternatively activated anti-inflammatory macrophages (M2) were analyzed by using Gene Ontology and Kyoto Encyclopedia of Genes and Genomes enrichment analysis. In this study, not only we have identified the changes of global gene expression in rat M0, M1 and M2, but we have also made clear systematically the key genes and signaling pathways in the differentiation process of M0 to M1 and M2. These will provide a foundation for future researches of macrophage polarization.

Immune cells regulate VEGF signalling via release of VEGF and antagonistic soluble VEGF receptor-1

Vascular endothelial growth factor (VEGF) is an important regulator of physiological and pathological angiogenesis. Besides malignant and stromal cells, local immune cells shape VEGF signalling in the tumour microenvironment. Aminobisphosphonates such as zoledronic acid (Zol) are drugs known to inhibit osteoclast activity and bone resorption, but also have immunomodulatory and anti-tumour effects. These properties have been linked previously to the down-regulation of VEGF and interference with tumour neo-angiogenesis. It was therefore surprising to find that treatment with Zol in combination with low-dose interleukin (IL)-2 increased serum VEGF levels in cancer patients. In this study we aimed to characterize the effect of Zol and IL-2 on VEGF signalling of blood-derived immune cells in vitro. Upon stimulation with IL-2, T cells and natural killer (NK) cells increase production of VEGF consecutively to the release of proinflammatory interferon (IFN)-γ, and Zol accelerates this response specifically in γδ T cells. VEGF can, in turn, be antagonized by soluble VEGF receptor (sVEGFR)-1, which is released depending on stimulatory conditions and the presence of monocytes. Additionally, malignant cells represented by leukaemia and lymphoma cell lines produce VEGF and some release sVEGFR-1 simultaneously. Our findings indicate a mechanism by which the VEGF and the sVEGFR-1 production by immune cells regulates local VEGF signalling. Therefore, immunotherapeutic interventions may enable both pro- as well as anti-tumour effects via immune cell-mediated alterations of VEGF homeostasis.

Plasma immunological markers in pregnancy and cord blood: A possible link between macrophage chemo-attractants and risk of childhood type 1 diabetes

PROBLEM

Previous studies have suggested that immune perturbations during pregnancy can affect offspring type 1 diabetes (T1D) risk. We aimed to identify immunological markers that could predict offspring T1D or that were linked to T1D risk factors.

METHOD OF STUDY

We quantified selected circulating immunological markers in mid-pregnancy (interleukin [IL]-1β, IL-1ra, IL-2Rα, IL-2, -4, -5, -6, -10, -12p70, 13, -17A, GM-CSF, IFN-γ, CXCL10, CCL 2, CCL3, CCL4, TNF) and cord blood plasma (neopterin and kynurenine/tryptophan ratio) in a case-control study with 175 mother/child T1D cases (median age 5.8, range 0.7-13.0 years) and 552 controls.

RESULTS

Pre-pregnancy obesity was positively associated with CCL4, CXCL10, kynurenine/tryptophan ratio and neopterin (P < .01). The established T1D SNPs rs1159465 (near IL2RA) and rs75352297 (near CCR2 and CCR3) were positively associated with IL-2Rα and CCL4, respectively (P < .01). There was a borderline association of CCL4 and offspring T1D risk, independent of maternal obesity and genotype. When grouping the immunological markers, there was a borderline association (P = .05) with M1 phenotype and no association between M2-, Th1-, Th2- or Th17 phenotypes and offspring T1D risk.

CONCLUSION

Increased mid-pregnancy CCL4 levels showed borderline associations with increased offspring T1D risk, which may indicate a link between environmental factors in pregnancy and offspring T1D risk.

CCL2, CCL5, and IGF-1 participate in the immunomodulation of osteogenesis during M1/M2 transition in vitro

The modulation of macrophage phenotype from pro-inflammatory (M1) to tissue healing (M2) via exogenous addition of interleukin-4 (IL-4) facilitates osteogenesis; however, the molecular mediators underlying this phenomenon remain unknown. This study characterizes the IL-4-dependent paracrine crosstalk between macrophages and osteoprogenitors and its effect on osteogenesis in vitro. Primary murine M1 were co-cultured with MC3T3 cells (M1-MC3T3) in both transwell plates and direct co-cultures. To modulate M1 to M2, M1-MC3T3 were treated with IL-4 (20 ng/mL) at day 3 after seeding (M1 + IL-4-MC3T3). Selected molecular targets were assessed at days 3 and 6 after seeding at protein and mRNA levels. Mineralization was assessed at day 21. Transwell M1 + IL-4-MC3T3 significantly enhanced the secretion of CCL2/MCP-1, IGF-1 and to a lesser degree, CCL5/RANTES at day 6. At day 3, alkaline phosphatase (Alpl) was upregulated in direct M1-MC3T3. At day 6, Smurf2 and Insulin growth factor-1 (IGF-1) were downregulated and upregulated, respectively, in direct M1 + IL-4-MC3T3. Finally, M1 + IL-4-MC3T3 increased bone matrix mineralization compared with MC3T3 cells in transwell, but this was significantly less than M1-MC3T3. Taken together, macrophage subtypes enhanced the osteogenesis in transwell setting and the transition from M1 to M2 was associated with an increase in bone anabolic factors CCL2/MCP-1, CCL5/RANTES and IGF-1 in vitro. © 2017 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 105A: 3069-3076, 2017.

Role of tumour-associated macrophages in oral squamous cells carcinoma progression: an update on current knowledge

BACKGROUND

Oral squamous cell carcinoma (OSCC) accounts over 90% of malignant neoplasms of the oral cavity. This pathological entity is associated to a high mortality rate that has remained unchanged over the past decades. Tumour-associated macrophages (TAMs) are believed to have potential involvement in OSCC progression. However, the molecular networks involved in communication between stroma and cancer cells have not yet been fully elucidated.

MAIN BODY

The role of M2 polarized cells in oral carcinogenesis is supported by a correlation between TAMs accumulation into OSCC stroma and poor clinical outcome. Signalling pathways such as the NF-κB and cytokines released in the tumour microenvironment promote a bidirectional cross-talk between M2 and OSCC cells. These interactions consequently result in an increased proliferation of malignant cells and enhances aggressiveness, thus reducing patients' survival time.

CONCLUSIONS

Here, we present a comprehensive review of the role of interleukin (IL)-1, IL-4, IL-6, IL-8, IL-10 and the receptor tyrosine kinase Axl in macrophage polarization to an M2 phenotype and OSCC progression. Understanding the molecular basis of oral carcinogenesis and metastatic spread of OSCC would promote the development of targeted treatment contributing to a more favourable prognosis.

Absence of CCR2 results in an inflammaging environment in young mice with age-independent impairments in muscle regeneration

Skeletal muscle regeneration requires coordination between dynamic cellular populations and tissue microenvironments. Macrophages, recruited via CCR2, are essential for regeneration; however, the contribution of macrophages and the role of CCR2 on nonhematopoietic cells has not been defined. In addition, aging and sex interactions in regeneration and sarcopenia are unclear. Muscle regeneration was measured in young (3-6 mo), middle (11-15 mo), old (24-32 mo) male and female CCR2^-/- mice. Whereas age-related muscle atrophy/sarcopenia was present, regenerated myofiber cross-sectional area (CSA) in CCR2^-/- mice was comparably impaired across all ages and sexes, with increased adipocyte area compared with wild-type (WT) mice. CCR2^-/- mice myofibers achieved approximately one third of baseline CSA even 84 d after injury. Regenerated CSA and clearance of necrotic tissue were dependent on bone marrow-derived cellular expression of CCR2. Myogenic progenitor cells isolated from WT and CCR2^-/- mice exhibited comparable proliferation and differentiation capacity. The most striking cellular anomaly in injured muscle of CCR2^-/- mice was markedly decreased macrophages, with a predominance of Ly6C^- anti-inflammatory monocytes/macrophages. Ablation of proinflammatory TLR signaling did not affect muscle regeneration or resolution of necrosis. Of interest, many proinflammatory, proangiogenic, and chemotactic cytokines were markedly elevated in injured muscle of CCR2^-/- relative to WT mice despite impairments in macrophage recruitment. Collectively, these results suggest that CCR2 on bone marrow-derived cells, likely macrophages, were essential to muscle regeneration independent of TLR signaling, aging, and sex. Decreased proinflammatory monocytes/macrophages actually promoted a proinflammatory microenvironment, which suggests that inflammaging was present in young CCR2^-/- mice.

Effects of IRF1 and IFN-β interaction on the M1 polarization of macrophages and its antitumor function

Macrophages that differentiate from precursor monocytes can be polarized into a classically activated (M1) or alternatively activated (M2) status depending on different stimuli. Generally, interferon (IFN)-γ and lipopolysaccharide (LPS) are considered the classical stimuli with which to establish M1 polarization. IFN regulatory factor (IRF)1 and IFN-β are two crucial molecules involved in IFN-γ- and LPS-initialed signaling. However, the association between IRF1 and IFN-β in the context of the M1 polarization of macrophages is not yet fully understood. In this study, we demonstrate that U937-derived macrophages, in response to IFN-γ and LPS stimulation, readily acquire an M1 status, indicated by the increased expression of interleukin (IL)-12, IL-6, IL-23, tumor necrosis factor (TNF)-α and the M1-specific cell surface antigen, CD86, and the decreased expression of the M2-specific mannose receptor, CD206. However, the knockdown of IRF1 in U937-derived macrophages led to an impaired M1 status, as indicated by the decreased expression of the above-mentioned M1 markers, and the increased expression of the M2 markers, CD206 and IL-10. A similar phenomenon was observed in the M1 macrophages in which IFN-β was inhibited. Furthermore, we demonstrated that IRF1 and IFN-β may interact with each other in the IFN-γ- and LPS-initiated signaling pathway, and contribute to the IRF5 regulation of M1 macrophages. In addition, the conditioned medium collected from the M1 macrophages in which IRF1 or IFN-β were inhibited, exerted pro-tumor effects on the HepG2 and SMMC-7721 cells, as indicated by an increase in proliferation, the inhibition of apoptosis and an enhanced invasion capability. The findings of our study suggest that the interactions of IRF1, IFN-β and IRF5 are involved in the M1 polarization of macro phages and have antitumor functions. These data may provide a novel antitumor strategy for targeted cancer therapy.

IL12, IL10, IFNγ and TNFα Expression in Human Primary Monocytes Stimulated with Bacterial Heat Shock GroEL (Hsp64) Protein

Actinobacillus (Aggregatibacter) actinomycetemicomitans (Aa) is a bacterium that lives in the oral cavity and plays an important role in periodontal diseases. The effect of A.actinomycetemcomitans's heat shock family protein GroEL on host or immune cells including monocytes is quite limited. In this study, the recombinant A.actinomycetemcomitans's GroEL protein (rAaGroEL) was used as an antigen and its effects on monocytes of peripheral blood mononuclear cells (PBMCs) was investigated. To do that, PBMCs were stimulated with rAaGroEL protein at different time points (16h to 96h) and the cytokines of CD14+ monocytes were detected with intracellular cytokine staining by Flow cytometry. Data showed that AaGroEL protein has an antigenic effect on human primary monocytes. AaGroEL protein responsive CD14 monocytes stimulates the expression of IL12, IL10, IFNγ and TNFα cytokines with different kinetics and expression profile. Therefore, A. actinomycetemcomitans's heat shock GroEL protein can modulate innate and adaptive immune responses and contribute to an inflammatory diseases pathology.

Dynamic macrophage polarization-specific miRNA patterns reveal increased soluble VEGF receptor 1 by miR-125a-5p inhibition

Dynamic, epigenetic mechanisms can regulate macrophage phenotypes following exposure to different stimulating conditions and environments. However, temporal patterns of microRNAs (miRNAs or miRs) across multiple macrophage polarization phenotypes have not been defined. We determined miRNA expression in bone marrow-derived murine macrophages over multiple time points (0.5, 1, 3, 24 h) following exposure to cytokines and/or LPS. We hypothesized that dynamic changes in miRNAs regulate macrophage phenotypes. Changes in macrophage polarization markers were detected as early as 0.5 and as late as 24 h; however, robust responses for most markers occurred within 3 h. In parallel, many polarization-specific miRNAs were also changed by 3 h and expressed divergent patterns between M1 and M2a conditions, with increased expression in M1 (miR-155, 199a-3p, 214-3p, 455-3p, and 125a) or M2a (miR-511 and 449a). Specifically, miR-125a-5p exhibited divergent patterns: increased at 12-24 h in M1 macrophages and decreasing trend in M2a. VEGF in the culture media of macrophages was dependent upon the polarization state, with greatly diminished VEGF in M2a compared with M1 macrophage culture media despite similar VEGF in cell lysates. Inhibition of miR-125a-5p in media-only controls (MO) and M1 macrophages greatly increased expression and secretion of soluble VEGF receptor-1 (sVEGFR1) leading to diminished VEGF in the culture media, partially converting MO and M1 into an M2a phenotype. Thus, the divergent expression patterns of polarization-specific miRNAs led to the identification and demonstrated the regulation of a specific macrophage polarization phenotype, sVEGFR1 by inhibition of miR-125a-5p.