THP-1 and human peripheral blood mononuclear cell-derived macrophages differ in their capacity to polarize in vitro

Aberrant expressions of TAM receptors are associated with postoperative recurrence in chronic rhinosinusitis with nasal polyps

OBJECTIVES

TAM receptors (TYRO3, AXL, and MER) play important roles in inflammatory responses, but their effects in chronic rhinosinusitis with nasal polyps (CRSwNP) remain elucidated. We aim to evaluate the values of TAM receptors in disease severity and postoperative recurrence of CRSwNP.

METHODS

We initially enrolled 160 patients with CRSwNP who were treated with functional endoscopic sinus surgery (FESS) and postoperative recurrence was evaluated during the follow-up period. Circulating TAM receptor levels were detected by enzyme-linked immunosorbent assay (ELISA), and tissue expressions were measured by real-time polymerase chain reaction (RT-PCR) and immunohistochemical (IHC). The relationships between TAM receptor levels and postoperative recurrence were examined.

RESULTS

A total of 150 patients completed the follow-up schedule, 49 patients experienced postoperative recurrence and the remaining 101 patients were non-recurrent. In recurrent CRSwNP patients, serum levels of TAM receptors were increased compared to those in non-recurrent patients and were positively correlated with disease severity scores (P < 0.05). Circulating TYRO3 and MER were identified as potential predictors of postoperative recurrence based on receiver operating characteristics (ROC) and Kaplan-Meier plots (P < 0.05). Furthermore, tissue TAM receptor levels, as determined by both RT-PCR and IHC, were enhanced in the recurrent group than in the non-recurrent group (P < 0.05) and were predictive of postoperative recurrence (P < 0.05). Interestingly, circulating TYRO3 and MER concentrations, as well as tissue TYRO3 expression, were found to be significantly increased in patients who experienced postoperative recurrence (P < 0.05). IHC images from the same patients revealed that TAM expressions were enhanced in the recurrent tissues compared to their baseline tissue levels.

CONCLUSIONS

Our laboratory results demonstrated that TAM receptors were increased in recurrent CRSwNP patients and associated with postoperative recurrence. Moreover, the new laboratory findings suggested that measuring circulating levels of TAM receptors might serve as a promising new approach to assess disease progression and predict the risk of postoperative recurrence.

Treponema pallidum protein Tp47 induced prostaglandin E2 to inhibit the phagocytosis in human macrophages

BACKGROUND

During Treponema pallidum (T. pallidum) infection, the host's immune system actively engages in pursuit and elimination of T. pallidum, while T. pallidum skillfully employs various mechanisms to evade immune recognition. Macrophages exhibit incomplete clearance of T. pallidum in vitro and the underlying mechanism of how T. pallidum resists the attack of macrophage remains unclear.

OBJECTIVES

To investigate the effect of T. pallidum membrane protein Tp47 on the phagocytosis of macrophages.

METHODS

THP-1-derived macrophages were used to investigate the role of Tp47 in the secretion of Prostaglandin E2 (PGE2) in macrophages and the mechanism by which Tp47 induced the production of PGE2, as well as the impact of PGE2 on the macrophage's phagocytosis.

RESULTS

Tp47 (1-10 μg/mL) significantly inhibited the phagocytosis of latex beads and T. pallidum in macrophages (p ≤ 0.05). PGE2 production by macrophages could be induced by Tp47, and the phagocytic function of macrophages could be restored using PGE2 antibody. Tp47 produced PGE2 by activating the PERK/NF-κB/COX-2 pathway in macrophages. Inhibitors targeting PERK, NF-κB and COX-2, respectively, reduced the level of PGE2 and restored the phagocytic function of macrophages.

CONCLUSION

Tp47-induced PGE2 production via the PERK/NF-κB/COX-2 pathway contributed to macrophage phagocytosis inhibition, which potentially contributes to immune evasion during the T. pallidum infection.

Hyaluronic Acid Viscosupplement Modulates Inflammatory Mediators in Chondrocyte and Macrophage Coculture via MAPK and NF-κB Signaling Pathways

Osteoarthritis (OA) is a chronic musculoskeletal disorder characterized by cartilage degeneration and synovial inflammation. Paracrine interactions between chondrocytes and macrophages play an essential role in the onset and progression of OA. In this study, in replicating the inflammatory response during OA pathogenesis, chondrocytes were treated with interleukin-1β (IL-1β), and macrophages were treated with lipopolysaccharide and interferon-γ. In addition, a coculture system was developed to simulate the biological situation in the joint. In this study, we examined the impact of hyaluronic acid (HA) viscosupplement, particularly Hyruan Plus, on chondrocytes and macrophages. Notably, this viscosupplement has demonstrated promising outcomes in reducing inflammation; however, the underlying mechanism of action remains elusive. The viscosupplement attenuated inflammation, showing an inhibitory effect on nitric oxide production, downregulating proinflammatory cytokines such as matrix metalloproteinases (MMP13 and MMP3), and upregulating the expression levels of type II collagen and aggrecan in chondrocytes. HA also reduced the expression level of inflammatory cytokines such as IL-1β, TNF-α, and IL-6 in macrophages, and HA exerted an overall protective effect by partially suppressing the MAPK pathway in chondrocytes and p65/NF-κB signaling in macrophages. Therefore, HA shows potential as a viscosupplement for treating arthritic joints.

Industrial-produced lemon nanovesicles ameliorate experimental colitis-associated damages in rats via the activation of anti-inflammatory and antioxidant responses and microbiota modification

Plant-derived nanovesicles (PDNVs) have recently emerged as natural delivery systems of biofunctional compounds toward mammalian cells. Considering their already described composition, anti-inflammatory properties, stability, and low toxicity, PDNVs offer a promising path for developing new preventive strategies for several inflammatory diseases, among which the inflammatory bowel disease (IBD). In this study, we explore the protective effects of industrially produced lemon vesicles (iLNVs) in a rat model of IBD. Characterization of iLNVs reveals the presence of small particles less than 200 nm in size and a profile of bioactive compounds enriched in flavonoids and organic acids with known beneficial properties. In vitro studies on human macrophages confirm the safety and anti-inflammatory effects of iLNVs, as evidenced by the reduced expression of pro-inflammatory cytokines and increased levels of anti-inflammatory markers. As evidenced by in vivo experiments, pre-treatment with iLNVs significantly alleviates symptoms and histological features in 2,4 dinitrobenzensulfuric acid (DNBS)-induced colitis in rats. Molecular pathway analysis reveals modulation of NF-κB and Nrf2, indicating anti-inflammatory and antioxidant effects. Finally, iLNVs affects gut microbiota composition, improving the consistent colitis-related alterations. Overall, we demonstrated the protective role of industrially produced lemon nanovesicles against colitis and emphasized their potential in managing IBD through multifaceted mechanisms.

Mineralized collagen scaffolds for regenerative engineering applications

Collagen is a primary constituent of the tissue extracellular matrix. As a result, collagen has been a common component of tissue engineering biomaterials, including those to promote bone regeneration or to investigate cell-material interactions in the context of bone homeostasis or disease. This review summarizes key considerations regarding current state-of-the-art design and use of collagen biomaterials for these applications. We also describe strategic opportunities for collagen biomaterials to address a new era of challenges, including immunomodulation and appropriate consideration of sex and other patient characteristics in biomaterial design.

Low-dose cadmium telluride quantum dots trigger M1 polarization in macrophages through mTOR-mediated transcription factor EB activation

The increasing application of quantum dots (QDs) increases interactions with organisms. The inflammatory imbalance is a significant manifestation of immunotoxicity. Macrophages maintain inflammatory homeostasis. Using macrophages differentiated by phorbol 12-myristate 13-acetate-induced THP-1 cells as models, the study found that low-dose (5 μM) cadmium telluride QDs (CdTe-QDs) hindered monocyte-macrophage differentiation. CD11b is a surface marker of macrophage, and the addition of CdTe-QDs during induction resulted in a decrease in CD11b expression. Moreover, exposure of differentiated THP-1 macrophage (dTHP-1) to 5 μM CdTe-QDs led to the initiation of M1 polarization. This was indicated by the increased surface marker CD86 expression, along with elevated level of NF-κB and IL-1β proteins. The potential mechanisms are being explored. The transcription factor EB (TFEB) plays a significant role in immune regulation and serves as a crucial regulator of the autophagic lysosomal pathway. After exposed to CdTe-QDs, TFEB activation-mediated autophagy and M1 polarization were observed to occur simultaneously in dTHP-1. The mTOR signaling pathway contributed to TFEB activation induced by CdTe-QDs. However, mTOR-independent activation of TFEB failed to promote M1 polarization. These results suggest that mTOR-TFEB is an advantageous target to enhance the biocompatibility of CdTe-QDs.

Tolerogenic probiotics Lactobacillus delbrueckii and Lactobacillus rhamnosus promote anti-inflammatory profile of macrophages-derived monocytes of newly diagnosed patients with systemic lupus erythematosus

Systemic lupus erythematosus (SLE) is known as an autoimmune disorder that is characterized by the breakdown of self-tolerance, resulting in disease onset and progression. Macrophages have been implicated as a factor in the development of SLE through faulty phagocytosis of dead cells or an imbalanced M1/M2 ratio. The study aimed to investigate the immunomodulatory effects of Lactobacillus delbrueckii and Lactobacillus rhamnosus on M1 and M2 macrophages in new case lupus patients. For this purpose, blood monocytes were collected from lupus patients and healthy people and were cultured for 5 days to produce macrophages. For 48 h, the macrophages were then cocultured with either probiotics or lipopolysaccharides (LPS). Flow cytometry and real-time polymerase chain reaction were then used to analyze the expression of cluster of differentiation (CD) 14, CD80, and human leukocyte antigen - DR (HLADR) markers, as well as cytokine expression (interleukin [IL]1-β, IL-12, tumor necrosis factor α [TNF-α], IL-10, and transforming growth factor beta [TGF-β]). The results indicated three distinct macrophage populations, M0, M1, and M2. In both control and patient-derived macrophage-derived monocytes (MDMs), the probiotic groups showed a decrease in CD14, CD80, and HLADR expression compared to the LPS group. This decrease was particularly evident in M0 and M2 macrophages from lupus patients and M1 macrophages from healthy subjects. In addition, the probiotic groups showed increased levels of IL-10 and TGF-β and decreased levels of IL-12, IL1-β, and TNF-α in MDMs from both healthy and lupus subjects compared to the LPS groups. Although there was a higher expression of pro-inflammatory cytokines in lupus patients, there was a higher expression of anti-inflammatory cytokines in healthy subjects. In general, L. delbrueckii and L. rhamnosus could induce anti-inflammatory effects on MDMs from both healthy and lupus subjects.

IL-4-induced M2 macrophages inhibit fibrosis of endometrial stromal cells

BACKGROUND

Intrauterine adhesions (IUA) refers to endometrial fibrosis caused by irreversible damage of the endometrial basal layer. As the key regulators in tissue repair, regeneration, and fibrosis, macrophages play an essential role in endometrial regeneration and repair during the normal menstrual cycle. However, the mechanism of macrophages involved in IUA remains unclear.

METHODS

In the late stages of proliferation, the endometrium was collected to make paraffin sections. HE and Masson staining were used to observing endometrial morphology and endometrial fibrosis. Immunohistochemistry and Western blotting were used to detect the expression level of fibrosis indexes COL1A1 and α-SMA. The macrophage infiltration was evaluated by immunohistochemistry for the expression levels of CD 206 and CD163. Next, we cultured the primary human endometrial stromal cells (HESCs), and then an IUA cell model was established with 10 ng/ml TGF-β1 for 72 h. THP 1 cells were differentiated by 100 ng/ml PMA into macrophages for 48 h, then macrophages were polarized to M2 macrophages by 20 ng/ml IL-4 for 24 h. The culture supernatants (M(IL-4) -S) of M2 macrophages were applied to the IUA cell model. The expression of fibrosis markers was then assessed using immunofluorescence and Western blotting.

RESULTS

The results show that Patients with IUA have fewer endometrial glands and significantly increased fibrosis levels. Moreover, the infiltration of CD206-positive (M2) macrophages was significantly reduced in IUA patients, and negatively correlated with the expression of endometrial fibrosis indexes α-SMA and COL1A1. In addition, the primary HESCs treated with 10 ng/ml TGF-β1 for 72 h were found to have significantly increased levels of fibrosis indexes. Furthermore, supernatants from IL4-induced M2 macrophages inhibit the TGF-β1-induced fibrosis of HESCs.

CONCLUSIONS

M2 macrophages may negatively regulate the expression of COL1A1 and α-SMA, inhibiting the TGF-β1-induced fibrosis of HESCs. Our study suggests that targeting macrophage phenotypes and promoting the polarization of macrophages to M2 may become a novel strategy for the clinical treatment of IUA.

Advancing CAR-based immunotherapies in solid tumors: CAR- macrophages and neutrophils

Macrophages and neutrophils are the main components of the innate immune system and play important roles in promoting angiogenesis, extracellular matrix remodeling, cancer cell proliferation, and metastasis in the tumor microenvironment (TME). They can also be harnessed to mediate cytotoxic tumor killing effects and orchestrate effective anti-tumor immune responses with proper stimulation and modification. Therefore, macrophages and neutrophils have strong potential in cancer immunotherapy. In this review, we briefly outlined the applications of macrophages or neutrophils in adoptive cell therapies, and focused on chimeric antigen receptor (CAR)-engineered macrophages (CAR-Ms) and neutrophils (CAR-Ns). We summarized the construction strategies, the preclinical and clinical studies of CAR-Ms and CAR-Ns. In the end, we briefly discussed the limitations and challenges of CAR-Ms and CAR-Ns, as well as future research directions to extend their applications in treating solid tumors.

Characterization of polarization states of canine monocyte derived macrophages

Macrophages can reversibly polarize into multiple functional subsets depending on their micro-environment. Identification and understanding the functionality of these subsets is relevant for the study of immune‑related diseases. However, knowledge about canine macrophage polarization is still in its infancy. In this study, we polarized canine monocytes using GM-CSF/IFN- γ and LPS towards M1 macrophages or M-CSF and IL-4 towards M2 macrophages and compared them to undifferentiated monocytes (M0). Polarized M1 and M2 macrophages were thoroughly characterized for morphology, surface marker features, gene profiles and functional properties. Our results showed that canine M1-polarized macrophages obtained a characteristic large, roundish, or amoeboid shape, while M2-polarized macrophages were smaller and adopted an elongated spindle-like morphology. Phenotypically, all macrophage subsets expressed the pan-macrophage markers CD14 and CD11b. M1-polarized macrophages expressed increased levels of CD40, CD80 CD86 and MHC II, while a significant increase in the expression levels of CD206, CD209, and CD163 was observed in M2-polarized macrophages. RNAseq of the three macrophage subsets showed distinct gene expression profiles, which are closely associated with immune responsiveness, cell differentiation and phagocytosis. However, the complexity of the gene expression patterns makes it difficult to assign clear new polarization markers. Functionally, undifferentiated -monocytes, and M1- and M2- like subsets of canine macrophages can all phagocytose latex beads. M2-polarized macrophages exhibited the strongest phagocytic capacity compared to undifferentiated monocytes- and M1-polarized cells. Taken together, this study showed that canine M1 and M2-like macrophages have distinct features largely in parallel to those of well-studied species, such as human, mouse and pig. These findings enable future use of monocyte derived polarized macrophages particularly in studies of immune related diseases in dogs.

Study of tissue transglutaminase spliced variants expressed in THP-1 derived macrophages exhibiting distinct functional phenotypes

Tissue transglutaminase (TG2) expressed in monocytes and macrophage is known to participate in processes during either early and resolution stages of inflammation. The alternative splicing of tissue transglutaminase gene is a mechanism that increases its functional diversity. Four spliced variants are known with truncated C-terminal domains (TGM2_v2, TGM2_v3, TGM2_v4a, TGM2_v4b) but scarce information is available about its expression in human monocyte and macrophages. We studied the expression of canonical TG2 (TGM2_v1) and its short spliced variants by RT-PCR during differentiation of TPH-1 derived macrophages (dTHP-1) using two protocols (condition I and II) that differ in Phorbol-12-myristate-13-acetate dose and time schedule. The production of TNF-α and IL-1β in supernatant of dTHP-1, measured by ELISA in supernatants showed higher proinflammatory milieu in condition I. We found that the expression of all mRNA TG2 spliced variants were up-regulated during macrophage differentiation and after IFN-γ treatment of dTHP-1 cells in both conditions. Nevertheless, the relative fold increase or TGM2_v3 in relation with TGM2_v1 was higher only with the condition I. M1/M2-like THP-1 macrophages obtained with IFN-γ/IL-4 treatments showed that the up-regulation of TGM2_v1 induced by IL-4 was higher in relation with any short spliced variants. The qualitative profile of relative contribution of spliced variants in M1/M2-like THP-1 cells showed a trend to higher expression of TGM2_v3 in the inflammatory functional phenotype. Our results contribute to the knowledge about TG2 spliced variants in the biology of monocyte/macrophage cells and show how the differentiation conditions can alter their expression and cell function.

Soluble TAM Receptor Tyrosine Kinases Correlate with Disease Severity and Predict the Early Responsiveness of Sublingual Immunotherapy in Allergic Rhinitis

Background

Allergic rhinitis (AR) is a common allergic disease, and SLIT has shown effectiveness as a treatment method. This study focuses on the evaluation of serum TAM receptor tyrosine kinases (TYRO3, AXL, and MER) levels as potential indicators of disease severity and predictive markers for sublingual immunotherapy (SLIT) responsiveness in AR patients.

Methods

A total of 160 AR subjects, including 40 mild AR (MAR) and 120 moderate-severe AR (MSAR) patients, and 40 healthy controls (HC) were recruited. Serum concentrations of TYRO3, AXL, and MER were measured and their relationships with disease severity were examined. In the MSAR group, 102 patients underwent SLIT, and the early efficacy was evaluated. The correlations between the baseline serum concentrations of TYRO3, AXL, and MER and the early responsiveness of SLIT were analyzed.

Results

Serum concentrations of TYRO3, AXL, and MER were significantly reduced in AR patients, particularly in those MSAR subjects. Correlation analysis results indicated that serum TYRO3 and MER levels were negatively correlated with the visual analog scale (VAS) and the total nasal symptom score (TNSS). After one year of follow-up, 80 AR patients completed the treatment and were divided into effective and ineffective groups. Serum baseline levels of TYRO3 and MER were found to be lower in the effective group compared to the ineffective group. Additionally, there was a significant increase in serum TYRO3 and MER levels compared to baseline levels. Receiver operating characteristic (ROC) analysis revealed that circulating TYRO3 and MER had potential values for reflecting AR severity and predicting early SLIT responsiveness.

Conclusion

Serum TYRO3 and MER concentrations were decreased in AR patients and negatively associated with disease severity. Circulating TYRO3 and MER seem to be promising indicators for monitoring the efficacy of SLIT in AR patients.

Nanoscaled Discovery of a Shunt Rifamycin from Salinispora arenicola Using a Three-Color GFP-Tagged Staphylococcus aureus Macrophage Infection Assay

Antimicrobial resistance has emerged as a global public health threat, and development of novel therapeutics for treating infections caused by multi-drug resistant bacteria is urgent. Staphylococcus aureus is a major human and animal pathogen, responsible for high levels of morbidity and mortality worldwide. The intracellular survival of S. aureus in macrophages contributes to immune evasion, dissemination, and resilience to antibiotic treatment. Here, we present a confocal fluorescence imaging assay for monitoring macrophage infection by green fluorescent protein (GFP)-tagged S. aureus as a front-line tool to identify antibiotic leads. The assay was employed in combination with nanoscaled chemical analyses to facilitate the discovery of a new, active rifamycin analogue. Our findings indicate a promising new approach for the identification of antimicrobial compounds with macrophage intracellular activity. The antibiotic identified here may represent a useful addition to our armory in tackling the silent pandemic of antimicrobial resistance.

Optimization of differentiation and transcriptomic profile of THP-1 cells into macrophage by PMA

THP-1 monocyte, which can be differentiated into macrophages by PMA, is widely used in researches on pathogen infection and host innate immunity, but reports on the induction methods of PMA are different and lack a unified standard, and the transcriptome characteristics of macrophage compared with THP-1 cells remains unclear. In this research, we examined the differentiation effect of three factors including induction time, cell seeding density and PMA concentration by detecting the positive rate of CD14 expression. The concentration of 80ng/ml of PMA, the induction time of 24h, and the cell seeding density of 5×105 cells/ml, could respectively facilitates a relatively higher CD14 positive rate in THP-1 cells. Under this optimized conditions, the CD14 positive rate of THP-1 cells can reach 66.52%. Transcriptome sequencing showed that after the above induction, the mRNA expression of 3113 genes which were closely related to cell communication, signal transduction, cell response to stimulus, signaling receptor binding and cytokine activity were up-regulated, and the top 10 genes were RGS1, SPP1, GDF15, IL-1B, HAVCR2, SGK1, EGR2, TRAC, IL-8 and EBI3. While the mRNA expression of 2772 genes which were associated with cell cycle process, DNA binding and replication and cell division, were down-regulated, and the top genes were SERPINB10, TRGC2, SERPINB2, TRGC1, MS4A3, MS4A4E, TRGJP1, MS4A6A, TRGJP2, MS4A4A. This research optimized the induction method on THP-1 cell differentiation from three aspects and delineated the transcriptomic profile of PMA-induced THP-1 cells, laying a foundation for the construction method of cell model and for the functional study of macrophage.

Lipoprotein(a) induces caspase-1 activation and IL-1 signaling in human macrophages

Introduction

Lipoprotein(a) (Lp(a)) is an LDL-like particle with an additional apolipoprotein (apo)(a) covalently attached. Elevated levels of circulating Lp(a) are a risk factor for atherosclerosis. A proinflammatory role for Lp(a) has been proposed, but its molecular details are incompletely defined.

Methods and results

To explore the effect of Lp(a) on human macrophages we performed RNA sequencing on THP-1 macrophages treated with Lp(a) or recombinant apo(a), which showed that especially Lp(a) induces potent inflammatory responses. Thus, we stimulated THP-1 macrophages with serum containing various Lp(a) levels to investigate their correlations with cytokines highlighted by the RNAseq, showing significant correlations with caspase-1 activity and secretion of IL-1β and IL-18. We further isolated both Lp(a) and LDL particles from three donors and then compared their atheroinflammatory potentials together with recombinant apo(a) in primary and THP-1 derived macrophages. Compared with LDL, Lp(a) induced a robust and dose-dependent caspase-1 activation and release of IL-1β and IL-18 in both macrophage types. Recombinant apo(a) strongly induced caspase-1 activation and IL-1β release in THP-1 macrophages but yielded weak responses in primary macrophages. Structural analysis of these particles revealed that the Lp(a) proteome was enriched in proteins associated with complement activation and coagulation, and its lipidome was relatively deficient in polyunsaturated fatty acids and had a high n-6/n-3 ratio promoting inflammation.

Discussion

Our data show that Lp(a) particles induce the expression of inflammatory genes, and Lp(a) and to a lesser extent apo(a) induce caspase-1 activation and IL-1 signaling. Major differences in the molecular profiles between Lp(a) and LDL contribute to Lp(a) being more atheroinflammatory.

Detection and characterization of free oxygen radicals induced protein adduct formation in differentiating macrophages

Reactive oxygen species play a key role in cellular homeostasis and redox signaling at physiological levels, where excessive production affects the function and integrity of macromolecules, specifically proteins. Therefore, it is important to define radical-mediated proteotoxic stress in macrophages and identify target protein to prevent tissue dysfunction. A well employed, THP-1 cell line was utilized as in vitro model to study immune response and herein we employ immuno-spin trapping technique to investigate radical-mediated protein oxidation in macrophages. Hydroxyl radical formation along macrophage differentiation was confirmed by electron paramagnetic resonance along with confocal laser scanning microscopy using hydroxyphenyl fluorescein. Lipid peroxidation product, malondialdehyde, generated under experimental conditions as detected using swallow-tailed perylene derivative fluorescence observed by confocal laser scanning microscopy and high-performance liquid chromatography, respectively. The results obtained from this study warrant further corroboration and study of specific proteins involved in the macrophage activation and their role in inflammations.

Tumor-Associated Macrophage Subsets: Shaping Polarization and Targeting

The tumor microenvironment (TME) is a critical regulator of tumor growth, progression, and metastasis. Among the innate immune cells recruited to the tumor site, macrophages are the most abundant cell population and are present at all stages of tumor progression. They undergo M1/M2 polarization in response to signals derived from TME. M1 macrophages suppress tumor growth, while their M2 counterparts exert pro-tumoral effects by promoting tumor growth, angiogenesis, metastasis, and resistance to current therapies. Several subsets of the M2 phenotype have been observed, often denoted as M2a, M2b, M2c, and M2d. These are induced by different stimuli and differ in phenotypes as well as functions. In this review, we discuss the key features of each M2 subset, their implications in cancers, and highlight the strategies that are being developed to harness TAMs for cancer treatment.

Anti-inflammatory properties of an aldehydes-enriched fraction of grapefruit essential oil

Chronic inflammation is linked to the development of numerous diseases and is accompanied by increased cytokine secretion. Macrophages provide a first line of defense against pathogens that under inflammatory stimuli release pro-inflammatory cytokines. The essential oil (EO) fractions obtained from Citrus spp. rich in different compounds have gained the attention of both researchers and users during the last decades. In particular, grapefruit (Citrus paradisi) peel is rich in phenolics and flavonoids with several health benefits, including anti-inflammatory actions. Additionally, its EO consists of a large number of compounds such as monoterpenes, sesquiterpenes, alcohols, aldehydes, esters, and oxides. Among the methods for encapsulating EOs, spray-drying is the main one. In the present study, we aimed to determine the in vitro anti-inflammatory activity of EO from C. paradisi (grapefruit essential oil [GEO]) (whole and fractions) in a lipopolysaccharide (LPS)-induced inflammation model. Results indicate that Fr-GEO and Fr-GEO_SD exert protective effects against LPS-induced inflammation by decreasing gene expression and levels of pro-inflammatory cytokines as IL-6 and TNF-α. Monoterpenes as the most common components, as well as aldehydes and sesquiterpenes, might be responsible for such effects, although a synergistic action is not excluded. Furthermore, a higher percent of aldehydes is linked to improved olfactory properties. Our findings support the anti-inflammatory effects of selected Fr-GEO with a great potential for the development of new nutraceuticals and/or functional food for the treatment of inflammatory-associated diseases. PRACTICAL APPLICATION: The findings of this study support the anti-inflammatory effects of selected Fr-GEO with a great potential for the development of new nutraceuticals and/or functional food for the treatment of inflammatory-associated diseases.

Human Keratinocyte-Derived Exosomal MALAT1 Promotes Diabetic Wound Healing by Upregulating MFGE8 via microRNA-1914-3p

Purpose

Diabetic wound is a highly prevalent and refractory disease. Extensive studies have confirmed that keratinocytes and macrophages play an important role in the process of wound healing. Additionally, exosomes are regarded as a vital intercellular communication tool. This study aimed to investigate the role of human keratinocyte-derived exosomal MALAT1 in the treatment of diabetic wound by influencing the biological function of macrophages.

Methods

We mainly assessed the function of MALAT1 on the biological changes of macrophages, and the expression of MALAT1 in the keratinocyte-exosomes analyzed by quantitative real-time polymerase chain reaction (RT-qPCR). The downstream interaction between RNAs or proteins was assessed by mechanistic experiments. Besides, we evaluated the effects of human keratinocyte-derived exosomal MALAT1 on diabetic wound healing in vivo to verify in vitro results.

Results

We demonstrated that human keratinocyte-derived exosomal MALAT1 enhanced the biological functions of high glucose-injured macrophages, including phagocytosis, converting to a pro-healing phenotype and reducing apoptosis. Mechanistically, MALAT1 accelerated the expression of MFGE8 by competitively binding to miR-1914-3p, thereby affecting the function of macrophages and the signal axis of TGFB1/SMAD3, and finally promoting the healing of diabetic wounds. Human keratinocyte-derived exosomal MALAT1 might promote collagen deposition, ECM remodeling, and expression of MFGE8, VEGF, and CD31 but reduce the expression of TGFB and SMAD3 in an in vivo model of diabetic mice wounds, which accelerated diabetic wound healing and restored its function.

Conclusion

The current study revealed that human keratinocyte-derived exosomal MALAT1 would suppress miR-1914-3p to activate MFGE8 and eventually promote wound healing by enhancing macrophage phagocytosis, converting to a pro-healing phenotype and reducing apoptosis. It proposed that keratinocyte-derived exosomes might have the capacity to serve as a new method for the clinical treatment of diabetic wound.

A simple liposome-based bionic bacterium for tumor treatment by re-education of tumor-associated microphages in combination with chemotherapy

Re-education of tumor-associated macrophages (TAMs) into M1-like macrophages (Mφ1) has become one of the aims of tumor immunotherapy. Injection of live bacteria has been applied for this purpose; however, an acute innate immune response might be caused in this progress, and therefore a bacteria-based strategy with great security is needed. In this study, the bacterial walls of Staphylococcus aureus were inserted into the bilayer of liposome to construct liposome-based bionic bacteria (Bio-Bac), and doxorubicin (DOX) was encapsulated to form DOX@Bio-Bac. DOX@Bio-Bac re-educated the THP-1-derived TAMs into Mφ1 in vitro, and subsequently inhibited the migration and invasion of CAL27 cells. In a mouse model of hepatocellular carcinoma with lymphatic metastasis, the re-education of TAMs was proved, and an effective inhibition of tumor growth and metastasis in mice was observed. The liposome-based bionic bacteria constructed in this study provide a new strategy for re-education of TAMs, replacing the bacterial therapy reported previously, and a more effective anti-tumor effect can be obtained by combining the chemotherapy drugs with this bionic bacterium.

M2 tumor-associated macrophage mediates the maintenance of stemness to promote cisplatin resistance by secreting TGF-β1 in esophageal squamous cell carcinoma

BACKGROUND

Esophageal squamous cell carcinoma (ESCC) is a deadly gastrointestinal malignancy, and chemotherapy resistance is a key factor leading to its poor prognosis. M2 tumor-associated macrophages (M2-TAMs) may be an important cause of chemoresistance in ESCC, but its exact mechanism is still unclear.

METHODS

In order to study the role of M2-TAMs in ESCC chemoresistance, CCK-8, clone formation assay, flow cytometric apoptosis assay, qRT-PCR, western blotting, and serum-free sphere formation assays were used. In vivo animal experiments and human ESCC tissues were used to confirm the findings.

RESULTS

In vitro and in vivo animal experiments, M2-TAMs reduced the sensitivity of ESCC cells to cisplatin. Mechanistically, M2-TAMs highly secreted TGF-β1 which activated the TGFβR1-smad2/3 pathway to promote and maintain the stemness characteristic of ESCC cells, which could inhibit the sensitivity to cisplatin. Using TGFβ signaling inhibitor SB431542 or knockdown of TGFβR1 could reverse the cisplatin resistance of ESCC cells. In 92 cases of human ESCC tissues, individuals with a high density of M2-TAMs had considerably higher levels of TGF-β1. These patients also had worse prognoses and richer stemness markers.

CONCLUSION

TGF-β1 secreted from M2-TAMs promoted and maintained the stemness characteristic to induce cisplatin resistance in ESCC by activating the TGFβ1-Smad2/3 pathway.

Macrophage polarization states in atherosclerosis

Atherosclerosis, a chronic inflammatory condition primarily affecting large and medium arteries, is the main cause of cardiovascular diseases. Macrophages are key mediators of inflammatory responses. They are involved in all stages of atherosclerosis development and progression, from plaque formation to transition into vulnerable plaques, and are considered important therapeutic targets. Increasing evidence suggests that the modulation of macrophage polarization can effectively control the progression of atherosclerosis. Herein, we explore the role of macrophage polarization in the progression of atherosclerosis and summarize emerging therapies for the regulation of macrophage polarization. Thus, the aim is to inspire new avenues of research in disease mechanisms and clinical prevention and treatment of atherosclerosis.

Temporal Analysis Reveals the Transient Differential Expression of Transcription Factors That Underlie the Trans-Differentiation of Human Monocytes to Macrophages

The activation of monocytes and their trans-differentiation into macrophages are critical processes of the immune response. Prior work has characterized the differences in the expression between monocytes and macrophages, but the transitional process between these cells is poorly detailed. Here, we analyzed the temporal changes of the transcriptome during trans-differentiation of primary human monocytes into M0 macrophages. We find changes with many transcription factors throughout the process, the vast majority of which exhibit a maximally different expression at the intermediate stages. A few factors, including AP-1, were previously known to play a role in immunological transitions, but most were not. Thus, these findings indicate that this trans-differentiation requires the dynamic expression of many transcription factors not previously discussed in immunology, and provide a foundation for the delineation of the molecular mechanisms associated with healthy or pathological responses that involve this transition.

Worldwide productivity and research trend of publications concerning glioma-associated macrophage/microglia: A bibliometric study

Glioma-associated macrophage/microglia (GAM) represents a key player in shaping a unique glioma ecosystem to facilitate tumor progression and therapeutic resistance. Numerous studies have been published concerning GAM, but no relevant bibliometric study has been performed yet. Our bibliometric study aimed to comprehensively summarize and analyze the global scientific output, research hotspots, and trendy topics of publications on GAM over time. Data on publications on GAM were collected using the Web of Science (WoS). The search date was 16 January 2022, and the publications were collected from 2002 to 2021. Totally, 1,224 articles and reviews were incorporated and analyzed in the current study. It showed that the annual publications concerning GAM kept increasing over the past 20 years. The United States had the largest number of publications and total citations. Holland, Kettenmann, and Gutmann were the top three authors in terms of citation frequency. Neuro-oncology represented the most influential journal in GAM studies, with the highest H-index, total citations, and publication numbers. The paper published by Hambardzumyan in 2016 had the highest local citations. Additionally, the analysis of keywords implied that "prognosis," "tumor microenvironment," and "immunotherapy" might become research hotspots. Furthermore, trendy topics in GAM studies suggested that "immune infiltration," "immune microenvironment," "bioinformatics," "prognosis," and "immunotherapy" deserved additional attention. In conclusion, this bibliometric study comprehensively analyzed the publication trend of GAM studies for the past 20 years, in which the research hotspots and trendy topics were also uncovered. This information offered scholars critical references for conducting in-depth studies on GAM in the future.

Effects of the media conditioned by various macrophage subtypes derived from THP-1 cells on tunneling nanotube formation in pancreatic cancer cells

Background

Tunneling nanotubes (TNTs) are special membrane structures for intercellular communications. Vital cargoes (such as mitochondria) could be delivered from healthy cells to rescue damaged ones through TNTs. The TNTs could be utilized for the purpose of systematic delivery of therapeutic agents between cells. However, there are insufficient studies on the controlled enhancement of TNT formations. The purpose of this study is to understand how macrophages influence the TNT formation in cancer cells.

Results

Here we compared the capabilities of inducing TNTs in human pancreatic cancer cells (PANC-1) of the media conditioned by M0, M1 and M2 macrophages derived from THP-1 cells. The M0 and M1 macrophage conditioned media promoted TNT formation. Using a focused ion beam to cut through a TNT, we observed tunnel-like structures inside dense cytoskeletons with scanning electron microscopy. The TNT formation correlated with raised motility, invasion, and epithelial–mesenchymal transition in the PANC-1 cells. Mitochondria and lysosomes were also found to be transported in the TNTs.

Conclusions

These results suggest that TNT formation could be one of the responses to the immune stress in pancreatic cancer cells caused by M0 and M1 macrophages. This finding is valuable for the development of macrophage-targeting cancer therapy.

Bud-Poplar-Extract-Embedded Chitosan Films as Multifunctional Wound Healing Dressing

Wounds represent a major global health challenge. Acute and chronic wounds are sensitive to bacterial infection. The wound environment facilitates the development of microbial biofilms, delays healing, and promotes chronic inflammation processes. The aim of the present work is the development of chitosan films embedded with bud poplar extract (BPE) to be used as wound dressing for avoiding biofilm formation and healing delay. Chitosan is a polymer with antimicrobial and hydrating properties used in wound dressing, while BPE has antibacterial, antioxidative, and anti-inflammatory properties. Chitosan-BPE films showed good antimicrobial and antibiofilm properties against Gram-positive bacteria and the yeast Candida albicans. BPE extract induced an immunomodulatory effect on human macrophages, increasing CD36 expression and TGFβ production during M1/M2 polarization, as observed by means of cytofluorimetric analysis and ELISA assay. Significant antioxidant activity was revealed in a cell-free test and in a human neutrophil assay. Moreover, the chitosan-BPE films induced a good regenerative effect in human fibroblasts by in vitro cell migration assay. Our results suggest that chitosan-BPE films could be considered a valid plant-based antimicrobial material for advanced dressings focused on the acceleration of wound repair.

Exosomes derived from M2 macrophages induce angiogenesis to promote wound healing

There is an urgent clinical need for an appropriate method to shorten skin healing time. Among most factors related to wound healing, M2 macrophages will be recruited to the wound area and play a pivotal role in a time-limiting factor, angiogenesis. The exploration of exosomes derived from M2 in angiogenesis promotion is an attractive research field. In this project, we found that exosomes from M2 (M2-EXO) promoted the angiogenic ability of HUVECs in vitro. With a series of characteristic experiments, we demonstrated that M2-EXO inhibited PTEN expression in HUVECs by transferring miR-21, and further activated AKT/mTOR pathway. Then, using a full-thickness cutaneous wound mice model, we demonstrated that M2-EXO could be used as a promotor of angiogenesis and regeneration in vivo. Furthermore, M2-EXO-treated skin wounds exhibited regeneration of functional microstructures. These results demonstrate that M2-EXO can be used as a promising nanomedicine strategy for therapeutic exploration of skin healing with the potential to be translated into clinical practice.

Macrophage-extracellular matrix interactions: Perspectives for tissue engineered heart valve remodeling

In situ heart valve tissue engineering approaches have been proposed as promising strategies to overcome the limitations of current heart valve replacements. Tissue engineered heart valves (TEHVs) generated from in vitro grown tissue engineered matrices (TEMs) aim at mimicking the microenvironmental cues from the extracellular matrix (ECM) to favor integration and remodeling of the implant. A key role of the ECM is to provide mechanical support to and attract host cells into the construct. Additionally, each ECM component plays a critical role in regulating cell adhesion, growth, migration, and differentiation potential. Importantly, the immune response to the implanted TEHV is also modulated biophysically via macrophage-ECM protein interactions. Therefore, the aim of this review is to summarize what is currently known about the interactions and signaling networks occurring between ECM proteins and macrophages, and how these interactions may impact the long-term in situ remodeling outcomes of TEMs. First, we provide an overview of in situ tissue engineering approaches and their clinical relevance, followed by a discussion on the fundamentals of the remodeling cascades. We then focus on the role of circulation-derived and resident tissue macrophages, with particular emphasis on the ramifications that ECM proteins and peptides may have in regulating the host immune response. Finally, the relevance of these findings for heart valve tissue engineering applications is discussed.

Phagocytosis of Erythrocytes from Gaucher Patients Induces Phenotypic Modifications in Macrophages, Driving Them toward Gaucher Cells

Gaucher disease (GD) is caused by glucocerebrosidase deficiency leading to the accumulation of sphingolipids in macrophages named “Gaucher’s Cells”. These cells are characterized by deregulated expression of cell surface markers, abnormal secretion of inflammatory cytokines, and iron sequestration. These cells are known to infiltrate tissues resulting in hematological manifestations, splenomegaly, and bone diseases. We have already demonstrated that Gaucher red blood cells exhibit altered properties suggesting their key role in GD clinical manifestations. We hypothesized that Gaucher’s erythrocytes could be prone to premature destruction by macrophages contributing to the formation of altered macrophages and Gaucher-like cells. We conducted in vitro experiments of erythrophagocytosis using erythrocytes from Gaucher’s patients or healthy donors. Our results showed an enhanced erythrophagocytosis of Gaucher red blood cells compared to healthy red blood cells, which is related to erythrocyte sphingolipids overload and reduced deformability. Importantly, we showed elevated expression of the antigen-presenting molecules CD1d and MHC-II and of the iron-regulator hepcidin in macrophages, as well as enhanced secretion of the pro-inflammatory cytokine IL-1β after phagocytosis of GD erythrocytes. These results strongly suggested that erythrophagocytosis in GD contribute to phenotypic modifications in macrophages. This present study shows that erythrocytes-macrophages interactions may be crucial in GD pathophysiology and pathogenesis.

Dealing with Macrophage Plasticity to Address Therapeutic Challenges in Head and Neck Cancers

The head and neck tumor microenvironment (TME) is highly infiltrated with macrophages. More specifically, tumor-associated macrophages (TAM/M2-like) are one of the most critical components associated with poor overall survival in head and neck cancers (HNC). Two extreme states of macrophage phenotypes are described as conducting pro-inflammatory/anti-tumoral (M1) or anti-inflammatory/pro-tumoral (M2) activities. Moreover, specific metabolic pathways as well as oxidative stress responses are tightly associated with their phenotypes and functions. Hence, due to their plasticity, targeting M2 macrophages to repolarize in the M1 phenotype would be a promising cancer treatment. In this context, we evaluated macrophage infiltration in 60 HNC patients and demonstrated the high infiltration of CD68+ cells that were mainly related to CD163+ M2 macrophages. We then optimized a polarization protocol from THP1 monocytes, validated by specific gene and protein expression levels. In addition, specific actors of glutamine pathway and oxidative stress were quantified to indicate the use of glutaminolysis by M2 and the production of reactive oxygen species by M1. Finally, we evaluated and confirmed the plasticity of our model using M1 activators to repolarize M2 in M1. Overall, our study provides a complete reversible polarization protocol allowing us to further evaluate various reprogramming effectors targeting glutaminolysis and/or oxidative stress in macrophages.

Mitochondrial apolipoprotein A-I binding protein alleviates atherosclerosis by regulating mitophagy and macrophage polarization

Apolipoprotein A-I binding protein (AIBP), a secreted protein, has been shown to play a pivotal role in the development of atherosclerosis. The function of intracellular AIBP, however, is not yet well characterized. Here, we found that AIBP is abundantly expressed within human and mouse atherosclerotic lesions and exhibits a distinct localization in the inner membrane of mitochondria in macrophages. Bone marrow-specific AIBP deficiency promotes the progression of atherosclerosis and increases macrophage infiltration and inflammation in low-density lipoprotein receptor-deficient (LDLR-/-) mice. Specifically, the lack of mitochondrial AIBP leads to mitochondrial metabolic disorders, thereby reducing the formation of mitophagy by promoting the cleavage of PTEN-induced putative kinase 1 (PINK1). With the reduction in mitochondrial autophagy, macrophages polarize to the M1 proinflammatory phenotype, which further promotes the development of atherosclerosis. Based on these results, mitochondrial AIBP in macrophages performs an antiatherosclerotic role by regulating of PINK1-dependent mitophagy and M1/M2 polarization. Video Abstract.

Raman Microspectroscopy Identifies Biochemical Activation Fingerprints in THP-1- and PBMC-Derived Macrophages

(1) The monocytic leukemia cell line THP-1 and primary monocyte-derived macrophages (MDMs) are popular in vitro model systems to study human innate immunity, wound healing, and tissue regeneration. However, both cell types differ significantly in their origin and response to activation stimuli. (2) Resting THP-1 and MDMs were stimulated with lipopolysaccharide (LPS) and interferon γ (IFNγ) and analyzed by Raman microspectroscopy (RM) before and 48 h after activation. Raman data were subsequently analyzed using principal component analysis. (3) We were able to resolve and analyze the spatial distribution and molecular composition of proteins, nucleic acids, and lipids in resting and activated THP-1 and MDMs. Our findings reveal that proinflammatory activation-induced significant spectral alterations at protein and phospholipid levels in THP-1. In MDMs, we identified that nucleic acid and non-membrane-associated intracellular lipid composition were also affected. (4) Our results show that it is crucial to carefully choose the right cell type for an in vitro model as the nature of the cells itself may impact immune cell polarization or activation results. Moreover, we demonstrated that RM is a sensitive tool for investigating cell-specific responses to activation stimuli and monitoring molecular changes in subcellular structures.

The effect of myeloperoxidase-oxidized LDL on THP-1 macrophage polarization and repolarization

Macrophages (Mφs) play a crucial role in the development of atherosclerosis by engulfing modified LDL particles and forming foam cells, the hallmark of atherosclerosis. Many studies suggest that myeloperoxidase-oxidized LDL (Mox-LDL) is an important pathophysiological model for LDL modification in vivo. Classically (M1) and alternatively activated (M2) Mφs are both implicated in the process of atherogenesis. Mφs are highly plastic cells whereby they undergo repolarization from M1 to M2 and vice versa. Since little is known about the effects of Mox-LDL on Mφ polarization and repolarization, our study aimed at evaluating the in vitro effects of Mox-LDL at this level through making use of the well-established model of human THP-1-derived Mφs. Resting M0-Mφs were polarized toward M1- and M2-Mφs, then M0-, M1- and M2-Mφs were all treated with physiological concentrations of Mox-LDL to assess the effect of Mox-LDL treatment on Mφ polarization and repolarization. Treatment of M0-Mφs with a physiological concentration of Mox-LDL had no significant effects at the level of their polarization. However, treatment of M1-Mφs with Mox-LDL resulted in a significant reduction in their IL-10 cytokine secretion. Our results point to a potential role of Mox-LDL in increasing the pro-inflammatory state in Mφs through reducing the release of the anti-inflammatory cytokine, IL-10.

The Immunomodulatory Effects of Statins on Macrophages

Statins are 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase inhibitors used worldwide to manage dyslipidaemia and thus limit the development of atherosclerotic disease and its complications. These atheroprotective drugs are now known to exert pleiotropic actions outside of their cholesterol-lowering activity, including altering immune cell function. Macrophages are phagocytic leukocytes that play critical functional roles in the pathogenesis of atherosclerosis and are directly targeted by statins. Early studies documented the anti-inflammatory effects of statins on macrophages, but emerging evidence suggests that these drugs can also enhance pro-inflammatory macrophage responses, creating an unresolved paradox. This review comprehensively examines the in vitro, in vivo, and clinical literature to document the statin-induced changes in macrophage polarization and immunomodulatory functions, explore the underlying mechanisms involved, and offer potential explanations for this paradox. A better understanding of the immunomodulatory actions of statins on macrophages should pave the way for the development of novel therapeutic approaches to manage atherosclerosis and other chronic diseases and conditions characterised by unresolved inflammation.

The SC cell line as an in vitro model of human monocytes

In vitro analysis of human macrophages is generally hampered by the necessity to differentiate them from peripheral blood monocytes. We have analyzed to which extent noncancerous SC monocytes could be used as an in vitro macrophage model. Macrophages differentiated from peripheral monocytes using standard CSF1 and CSF2 protocols for M2 and M1 precursors, respectively, were compared with THP-1-derived macrophages treated with PMA and with SC-derived macrophages differentiated either by CSF1, CSF2, or PMA according to different protocols. The optimal condition for generation of SC macrophages was treatment with PMA for 3 days, followed by 5-days culture without PMA and 24-h polarization with LPS/IFN-γ or IL-4/IL-13. Similar to THP-1, SC cells do not express the monocyte marker CD14 and differentiation to macrophages results neither in CD68 nor in CD14 expression, both of which were expressed by monocyte-derived macrophages. Similar to THP-1-macrophages, a proportion of SC macrophages can be polarized to the M1-like subtype that is characterized by higher expression of CD38, CD86, CD80, TNF-α, and IL-1ra, whereas treatment with IL4/IL13 did not lead to expression of the M2-associated receptors CD163, CD206, and only slightly increased the CD200R expression. Still, SC-M1 express much lower levels of the M1-associated markers compared with monocyte-derived M1 and no IL-1β. The data demonstrate that SC-derived macrophages differ from monocyte-derived macrophages in respect of their morphology, expression of important macrophage markers, phagocytosis. Yet, polarized SC-M1-like cells may with restrictions serve as a model for M1 macrophages, though this model does not provide significant advantages over already well-described THP-1-M1-like cells.

Immunomodulating Activity of Pleurotus eryngii Mushrooms Following Their In Vitro Fermentation by Human Fecal Microbiota

Recent studies have revealed the crucial role of several edible mushrooms and fungal compounds, mainly polysaccharides, in human health and disease. The investigation of the immunomodulating effects of mushroom polysaccharides, especially β-glucans, and the link between their anticancer and immunomodulatory properties with their possible prebiotic activity on gut micro-organisms has been the subject of intense research over the last decade. We investigated the immunomodulating effects of Pleurotus eryngii mushrooms, selected due to their high β-glucan content, strong lactogenic effect, and potent geno-protective properties, following in vitro fermentation by fecal inocula from healthy elderly volunteers (>60 years old). The immunomodulating properties of the fermentation supernatants (FSs) were initially investigated in U937-derived human macrophages. Gene expression as well as pro- (TNF-α, IL-1β) and anti-inflammatory cytokines (IL-10, IL-1Rα) were assessed and correlated with the fermentation process. The presence of P. eryngii in the fermentation process led to modifications in immune response, as indicated by the altered gene expression and levels of the cytokines examined, a finding consistent for all volunteers. The FSs immunomodulating effect on the volunteers’ peripheral blood mononuclear cells (PBMCs) was verified through the use of cytometry by time of flight (CyTOF) analysis.

Lysosomal exocytosis of HSP70 stimulates monocytic BMP6 expression in Sjögren's syndrome

BMP6 is a central cytokine in the induction of Sjögren's syndrome-associated (SS-associated) secretory hypofunction. However, the upstream initiation leading to the production of this cytokine in SS is unknown. In this study, RNA ISH on salivary gland sections taken from patients with SS indicated monocytic lineage cells as a cellular source of BMP6. RNA-Seq data on human salivary glands suggested that TLR4 signaling was an upstream regulator of BMP6, which was confirmed by in vitro cell assays and single-cell transcriptomics of human PBMCs. Further investigation showed that HSP70 was an endogenous natural TLR4 ligand that stimulated BMP6 expression in SS. Release of HSP70 from epithelial cells could be triggered by overexpression of lysosome-associated membrane protein 3 (LAMP3), a protein also associated with SS in several transcriptome studies. In vitro studies supported the idea that HSP70 was released as a result of lysosomal exocytosis initiated by LAMP3 expression, and reverse transcription PCR on RNA from minor salivary glands of patients with SS confirmed a positive correlation between BMP6 and LAMP3 expression. BMP6 expression could be experimentally induced in mice by overexpression of LAMP3, which developed an SS-like phenotype. The newly identified LAMP3/HSP70/BMP6 axis provided an etiological model for SS gland dysfunction and autoimmunity.

An Apple a Day Keeps the Doctor Away: Potential Role of miRNA 146 on Macrophages Treated with Exosomes Derived from Apples

The constant dialogue between the plant world and the animal world (including man among them) has been known since the time of Adam and Eve, where an apple was the origin of the evils of the world. Apart from Snow White—who might have something to object to when it comes to the use of apples—fruits, plants, and natural extracts have been known for millennia as remedies for human health-related ailments. In the light of such evidence, the aim of the present work was to investigate from a biological point of view the potential role of apple exosomes in inflammatory processes on human cells. To this end we isolated and characterized apple exosomes and treated human cells such as macrophages and NCTC L929 as cancer cells in order to evaluate the tumorigenic and anti-inflammatory effect of apple exomes. Microscopic and molecular biology analyses were conducted to characterize exosomes and to assess cell proliferation, death, and miRNA line, as well as gene expression and the uptake of exosomes by cells. The results confirm the absolute biological safety of exosomes and their anti-inflammatory effect, mediated mainly by miRNA146 production by M2 macrophages.

Ginsenoside Rb2 Alleviated Atherosclerosis by Inhibiting M1 Macrophages Polarization Induced by MicroRNA-216a

Introduction: Atherosclerosis is a chronic disease characterized by the inflammatory process and lipid depositions. We previously reported that microRNA-216a (miR-216a) can accelerate the progression of atherosclerosis by promoting the polarization of M1 pro-inflammatory phenotype. Ginsenoside Rb2 (Rb2), the major pharmacologically active compound extracted from ginseng, has a high affinity to miR-216a. In this study, we aimed to investigate whether Rb2 can counteract the effect of miR-216a in macrophages to ameliorate atherosclerosis.

Methods: The apolipoprotein E deficiency (ApoE^−/−) mice model was chronically infected with miR-216a adenovirus via the tail vein and then intraperitoneally injected with Rb2. The plaque lesion area and stability of thoracic aorta were examined. The human myeloid leukemia mononuclear cells (THP-1) or human peripheral blood mononuclear cells (PBMCs) were cultured in vitro, transfected with miR-216a mimics, and treated with Rb2 to explore the mechanisms of Rb2 on the polarization of M1 macrophages, inflammatory process, and lipid accumulation.

Results: In the atherosclerotic ApoE^−/− mice model, miR-216a greatly increased en face aortic lesion area of the thoracic aorta, lipid accumulation, and M1 macrophages infiltration in plaques, whereas these effects of miR-216a on atherosclerosis burden were significantly alleviated by Rb2 treatment. In the in vitro THP-1 model, the flow cytometry experiment showed that Rb2 treatment inhibited miR-216a–mediated polarization of M1 macrophages characterized by the surface marker CD86 expression but had no effects on M2 polarization characterized by the surface marker CD206 expression. Mechanistically, Rb2 suppressed the miR-216a–mediated inflammatory response through the Smad3/nuclear factor kappa B inhibitor alpha pathway. Moreover, Rb2 reduced the lipid uptake and promoted cholesterol efflux by counteracting the effects of miR-216a in the THP-1–derived foam cells and in the PBMC-derived foam cells under the oxidized low-density lipoproteins.

Conclusion: Our findings indicated that Rb2 might be a potential therapeutic molecule for atherosclerosis by attenuating the atherosclerosis plaque lesion, lipid accumulation, and M1 macrophages polarization by targeting miR-216a. Given that accumulation of foam cells in the intima takes place chronically, the role of Rb2 in atherosclerosis progression needs further investigation.

Concurrent suppression of Aβ aggregation and NLRP3 inflammasome activation for treating Alzheimer's disease

Alzheimer's disease (AD) is a neurodegenerative illness accompanied by severe memory loss, cognitive disorders and impaired behavioral ability. Amyloid β-peptide (Aβ) aggregation and nucleotide-binding oligomerization domain (NOD)-like receptor protein 3 (NLRP3) inflammasome play crucial roles in the pathogenesis of AD. Aβ plaques not only induce oxidative stress and impair neurons, but also activate the NLRP3 inflammasome, which releases inflammatory cytokine IL-1β to trigger neuroinflammation. A bifunctional molecule, 2-[2-(benzo[d]thiazol-2-yl)phenylamino]benzoic acid (BPBA), with both Aβ-targeting and inflammasome-inhibiting capabilities was designed and synthesized. BPBA inhibited self- and Cu²⁺- or Zn²⁺-induced Aβ aggregation, disaggregated the already formed Aβ aggregates, and reduced the neurotoxicity of Aβ aggregates; it also inhibited the activation of the NLRP3 inflammasome and reduced the release of IL-1β in vitro and vivo. Moreover, BPBA decreased the production of reactive oxygen species (ROS) and alleviated Aβ-induced paralysis in transgenic C. elegans with the human Aβ₄₂ gene. BPBA exerts an anti-AD effect mainly through dissolving Aβ aggregates and inhibiting NLRP3 inflammasome activation synergistically.

Bifunctional molecule BPBA inhibits Aβ aggregation and NLRP3 inflammasome activation, thereby decreasing ROS and IL-1β in vitro and vivo; it synergistically prevents Alzheimer's disease via alleviating Aβ neurotoxicity and reducing neuroinflammation.

Diffuse large B-cell lymphoma-derived exosomes push macrophage polarization toward M2 phenotype via GP130/STAT3 signaling pathway

Growing evidence shows that cancer progression links with both heterogeneity of the tumor microenvironment and dysregulated activity of immune cells. Cancer-secreted exosomes are being recognized as indispensable mediators of the exchange cargo between cancer and immune cells. The M2-phenotype tumor-associated macrophages have the function of promoting tumor progression and drug resistance. Diffuse large B-cell lymphoma(DLBCL) is a highly heterogeneous and very common malignant non-Hodgkin's lymphoma. Here, we demonstrate that different subtype DLBCL cell-derived exosomes are internalized by macrophages, which can affect macrophages polarization. The mechanism of DLBCL-derived exosomes on macrophage polarization remains unclear currently. This study showed that DLBCL-secreted exosomes could induce the transformation of macrophages to a protumor M2-like phenotype, and block the drug-induced apoptosis of DLBCL cells in an indirect co-culture system. Different DLBCL-derived exosomes could change the phenotype of macrophages through the STAT3 signaling, which upregulated the expression of oncogenic genes and classical markers of M2-like phenotype macrophages, such as IL-10, CD206, and CD163. The addition of DLBCL-derived exosomes resulted in the activation of the STAT3 signaling pathway of M0/M2 macrophages in an indirect co-culture system. GP130 was highly enriched in DLBCL-derived exosomes, which triggered the activation of STAT3 of macrophages and subsequently induced the downstream targets such as BCL2, SURVIVIN, and BAX. The parallel changes of STAT3 and GP130 in macrophages confirmed that GP130 of DLBCL-derived exosomes promoted macrophage polarization by activating STAT3 signaling. Furthermore, all of these effects could be reversed by the GP130 inhibitor SC144. The data indicated that DLBCL-derived exosomes could trigger macrophages polarization into a pro-survival M2-like phenotype, which was at least partially through the GP130/STAT3 signaling pathway. Collectively, this study showed that DLBCL-derived exosomes could promote macrophages transformation to protumor M2-like phenotype in the tumor microenvironment.

Platinum(IV) complexes as inhibitors of CD47-SIRPα axis for chemoimmunotherapy of cancer

Phagocytosis of cancer cells by antigen presenting cells (APCs) is critical to activate the host's immune responses. However, the targeting ability of APCs to cancer cells is limited by the upregulation of transmembrane protein CD47 on the cancer cell surface. Blocking CD47 can affect the macrophage-mediated phagocytosis. Two platinum-based immunomodulators MUP and DMUP were synthesized to enhance the phagocytic activity of macrophages by blocking the CD47-SIRPα axis. These Pt^IV complexes not only showed high antiproliferative activity against a panel of human cancer cell lines, but also cooperated with human peripheral blood mononuclear cells (PBMCs) to suppress cancer cells. They acted as immune checkpoint inhibitors to modulate the immune responses of both cancer and immune cells. In particular, DMUP decreased the expression of CD47 in tumor tissues and promoted the polarization of macrophages from M2 to M1 phenotype in a mouse model of non-small cell lung cancer, thereby enhancing the anticancer effect. By interfering with DNA synthesis and stimulating immune system, DMUP takes the advantage of chemotherapy and immunotherapy to inhibit cancer cells. The dual efficacy of DMUP makes it a potential chemoimmunotherapeutic agent in cancer therapy.

Neutrophil extracellular traps modulate inflammatory markers and uptake of oxidized LDL by human and murine macrophages

Neutrophil extracellular traps (NETs) are web-like structures, which are released upon neutrophil activation. It has previously been demonstrated that NETs are present in atherosclerotic lesions of both humans and animal models thus playing a decisive role in atherosclerosis. Besides, macrophages have a crucial role in disease progression, whereby classically activated M1 macrophages sustain inflammation and alternatively activated M2 macrophages display anti-inflammatory effects. Although NETs and macrophages were found to colocalize in atherosclerotic lesions, the impact of NETs on macrophage function is not fully understood. In the present study, we aimed to investigate the effect of NETs on human and murine macrophages in respect to the expression of pro-inflammatory cytokines, matrix metalloproteinases (MMPs) and uptake of oxidized LDL (oxLDL) in vitro. Human THP-1 and murine bone marrow-derived macrophages were cultured under M1 (LPS + IFN-γ)- and M2a (IL-4)-polarizing culture conditions and treated with NETs. To mimic intraplaque regions, cells were additionally cultured under hypoxic conditions. NETs significantly increased the expression of IL-1β, TNF-α and IL-6 in THP-M1 macrophages under normoxia but suppressed their expression in murine M1 macrophages under hypoxic conditions. Notably, NETs increased the number of oxLDL-positive M1 and M2 human and murine macrophages under normoxia, but did not influence formation of murine foam cells under hypoxia. However, oxLDL uptake did not strongly correlate with the expression of the LDL receptor CD36. Besides, upregulated MMP-9 expression and secretion by macrophages was detected in the presence of NETs. Again, hypoxic culture conditions dampened NETs effects. These results suggest that NETs may favor foam cell formation and plaque vulnerability, but exert opposite effects in respect to the inflammatory response of human and murine M1 macrophages. Moreover, effects of NETs on macrophages’ phenotype are altered under hypoxia.

GPNMB plays an active role in the M1/M2 balance

The phenotypic function of macrophages varies with the local microenvironment. Macrophages play an important role in the development of periodontitis. As one of the sources of GPNMB protein, the phenotype of macrophages is affected by GPNMB expression. In this study, activated macrophages were evaluated by flow cytometry, RT-qPCR and WB, and M2a macrophages had higher GPNMB expression than M0 and M1 macrophages. On this basis, a macrophage model with overexpression of GPNMB was established, and it was observed that GPNMB overexpression promoted the secretion of anti-inflammatory factors by macrophages and inhibited the secretion of pro-inflammatory factors by M1 macrophages.

Tumor-Derived Small Extracellular Vesicles Induce Pro-Inflammatory Cytokine Expression and PD-L1 Regulation in M0 Macrophages via IL-6/STAT3 and TLR4 Signaling Pathways

Tumor-associated macrophages play a key role in promoting tumor progression by exerting an immunosuppressive phenotype associated with the expression of programmed cell death ligand 1 (PD-L1). It is well known that tumor-derived small extracellular vesicles (SEVs) affect the tumor microenvironment, influencing TAM behavior. The present study aimed to examine the effect of SEVs derived from colon cancer and multiple myeloma cells on macrophage functions. Non-polarized macrophages (M0) differentiated from THP-1 cells were co-cultured with SEVs derived from a colorectal cancer (CRC) cell line, SW480, and a multiple myeloma (MM) cell line, MM1.S. The expression of PD-L1, interleukin-6 (IL-6), and other inflammatory cytokines as well as of the underlying molecular mechanisms were evaluated. Our results indicate that SEVs can significantly upregulate the expressions of PD-L1 and IL-6 at both the mRNA and protein levels and can activate the STAT3 signaling pathway. Furthermore, we identified the TLR4/NF-kB pathway as a convergent mechanism for SEV-mediated PD-L1 expression. Overall, these preliminary data suggest that SEVs contribute to the formation of an immunosuppressive microenvironment.

Towards in silico Models of the Inflammatory Response in Bone Fracture Healing

In silico modeling is a powerful strategy to investigate the biological events occurring at tissue, cellular and subcellular level during bone fracture healing. However, most current models do not consider the impact of the inflammatory response on the later stages of bone repair. Indeed, as initiator of the healing process, this early phase can alter the regenerative outcome: if the inflammatory response is too strongly down- or upregulated, the fracture can result in a non-union. This review covers the fundamental information on fracture healing, in silico modeling and experimental validation. It starts with a description of the biology of fracture healing, paying particular attention to the inflammatory phase and its cellular and subcellular components. We then discuss the current state-of-the-art regarding in silico models of the immune response in different tissues as well as the bone regeneration process at the later stages of fracture healing. Combining the aforementioned biological and computational state-of-the-art, continuous, discrete and hybrid modeling technologies are discussed in light of their suitability to capture adequately the multiscale course of the inflammatory phase and its overall role in the healing outcome. Both in the establishment of models as in their validation step, experimental data is required. Hence, this review provides an overview of the different in vitro and in vivo set-ups that can be used to quantify cell- and tissue-scale properties and provide necessary input for model credibility assessment. In conclusion, this review aims to provide hands-on guidance for scientists interested in building in silico models as an additional tool to investigate the critical role of the inflammatory phase in bone regeneration.