Promoting M2 Macrophage Research Articles

IDO1-mediated M2 macrophage polarization alleviates the progression of ankylosing spondylitis

Indoleamine 2,3-dioxygenase 1 (IDO1) plays an anti-inflammatory role in autoimmune disease. However, its specific function in ankylosing spondylitis (AS) remain unclear. This study aimed to investigate the potential role of IDO1 in AS. Immunofluorescence, RT-qPCR, and western blot assays were employed to measure gene expression, while ELISA was used to quantify the release of M1 macrophage and M2 macrophage markers. CCK-8, EdU, flow cytometry, ALP staining, and Alizarin red staining (ARS) assays were conducted for functional analysis. JASPAR predicted the binding sites between PPARγ and the promoter, which were further validated by luciferase and ChIP assays. Our findings revealed that the expression of IDO1 was markedly elevated in AS patients. IDO1 overexpression promoted the proliferation of THP-1 cells and M2 macrophage polarization. Conversely, IDO1 knockdown facilitated the osteogenic differentiation of BMSCs. Furthermore, IDO1-mediated upregulation of PPARγ modulated RUNX2 transcription. PPARγ overexpression counteracted the effects of IDO1 knockdown, thereby inhibiting the osteogenic differentiation of BMSCs. In conclusion, the IDO1/PPARγ/RUNX2 signaling pathway may protect against AS by promoting M2 macrophage polarization and inhibiting osteogenic differentiation.

Vitexin mitigates oxidative stress, mitochondrial damage, pyroptosis and regulates small nucleolar RNA host gene 1/DNA methyltransferase 1/microRNA-495 axis in sepsis-associated acute lung injury.

This study examinedvitexin's effect on sepsis-induced acute lung injury. We used network pharmacology and in vivo and in vitro experiments were performed to elucidate vitexin's role in preventing pyroptosis and regulating small nucleolar RNA host gene 1 (SNHG1)/DNA methyltransferase 1 (DNMT1)/microRNA-495 (miR-495 axis. We developed an acute lung injury model using C57BL/6 mice and MLE-12 cells. Through a combination of network pharmacology and in vitro screening, vitexin was identified as the most promising anti-inflammatory compound. Multiple techniques such as western blotting, real-time PCR, Hematoxylin and eosin staining, immunohistochemistry, andTUNEL assay were used. Additionally, immunofluorescence, DCFDA and TMRE staining, flow cytometry, methylation-specific PCR, and gene transfection techniques were performed to elucidate vitexin's potential targets and underlying mechanisms. Vitexin treatment significantly reduced lung damage, neutrophil infiltration, and inflammation while improving tight junction integrity. In LPS-treated RAW264.7 macrophages and a septic mouse BALF-induced MLE-12 cell injury model, vitexin demonstrated anti-inflammatory effects, promoted M2 macrophage polarization, and enhanced regenerative markers. It also decreased oxidative stress, mitigated apoptosis and pyroptosis, and improved mitochondrial function. Our research uncovered a novel epigenetic regulatory mechanism involving lncRNA SNHG1, DNMT1, and miR-495. Vitexin's ability to reduce inflammation, counteract oxidative stress, and modulate epigenetic processes. These findings underscore the promising role of vitexin as a treatment for ALI generated by sepsis. The SNHG1/miR-495 axis, which has been identified, represents a new target for future therapies in acute lung injury.

The CCL5/CCR5/SHP2 axis sustains Stat1 phosphorylation and activates NF-κB signaling promoting M1 macrophage polarization and exacerbating chronic prostatic inflammation

Background and objectiveChronic prostatitis (CP) is a condition markered by persistent prostate inflammation, yet the specific cytokines driving its progression remain largely undefined. This study aims to identify key cytokines involved in CP and investigate their role in driving inflammatory responses through mechanistic and therapeutic exploration.MethodsA 48-cytokine panel test was conducted to compare the plasma cytokine profiles between participants with CP-like symptoms (CP-LS) and healthy controls. Experimental autoimmune prostatitis (EAP) models were used for functional validation, with further mechanistic studies performed through in vivo and in vitro assays. Pharmacological inhibition was applied using maraviroc, and pathway inhibitors to assess therapeutic potential.ResultsOur analysis identified CCL5 as one of the most prominently elevated cytokines in CP-LS patients. Further validation in the EAP model mice confirmed elevated CCL5 levels, highlighting its role in driving prostatic inflammation. Mechanistic studies revealed that CCL5 interacts with the CCR5 receptor, promoting M1 macrophage polarization and activating key inflammatory signaling pathways, including Stat1 and NF-κB, as indicated by increased phosphorylation of Stat1 and p65. In vitro, CCL5 combined with LPS stimulation amplified these effects, further promoting M1 polarization. CCL5 also sustained Stat1 activation by inhibiting its dephosphorylation through reduced interaction with SHP2, leading to prolonged inflammatory signaling. Single-cell transcriptomics confirmed high CCR5 expression in macrophages, correlating with inflammatory pathways. Pharmacological inhibition of CCR5, or its downstream signaling, significantly reduced macrophage-driven inflammation both in vivo and in vitro.ConclusionThese findings establish the CCL5/CCR5 axis as a critical driver of persistant prostatic inflammation and present it as a potential therapeutic target for CP.Graphic The graphic abstract illustrates the central role of the CCL5/CCR5 axis in promoting chronic prostatitis progression. CCL5 binds to the CCR5 receptor on macrophages, enhancing M1 polarization and activating key inflammatory pathways, including Stat1 and NF-κB, as shown by the increased phosphorylation of Stat1 and p65. The interaction also inhibits SHP2-mediated Stat1 dephosphorylation, sustaining prolonged inflammatory signaling. Pharmacological inhibition of CCR5 or its downstream pathways attenuates macrophage-driven inflammation, highlighting this axis as a critical driver and potential therapeutic target for chronic prostatitis.

MSCs-derived ECM functionalized hydrogel regulates macrophage reprogramming for osteoarthritis treatment by improving mitochondrial function and energy metabolism

Osteoarthritis (OA) is a degenerative disease that affects the entire joint, with synovial inflammation being a major pathological feature. Macrophages, as the most abundant immune cells in the synovium, have an M1/M2 imbalance that is closely related to the occurrence and development of OA. Mesenchymal stem cells (MSCs) have been shown to effectively suppress inflammation in the treatment of OA, but they still pose issues such as immune rejection and tumorigenicity. The extracellular matrix (ECM), as a major mediator of MSCs' immunoregulatory effects, offers a cell-free therapy to circumvent these risks. In this study, we developed an ECM-functionalized hydrogel by combining MSC-derived ECM with gelatin methacryloyl (GelMA). To enhance the immunomodulatory potential of MSCs, we pre-stimulated MSCs with the inflammatory factor interleukin-6 (IL-6) present in OA. In vitro results showed that the ECM-functionalized hydrogel promoted M2 macrophage polarization and inhibited the expression of various inflammatory genes, strongly indicating the hydrogel's powerful immunoregulatory capabilities. In an in vivo rat OA model, the ECM-functionalized hydrogel significantly reduced synovial inflammation and cartilage matrix degradation, alleviating the progression of OA. Furthermore, we utilized proteomics and transcriptomics analysis to reveal that the hydrogel accomplished macrophage metabolic reprogramming by regulating mitochondrial function and energy metabolism, thereby reducing inflammation. These findings suggest that the ECM-functionalized hydrogel is a promising biomaterial-based strategy for treating OA by targeting key pathological mechanisms.

A Biodegradable Magnesium Alloy Promotes Subperiosteal Osteogenesis Via Interleukin-10-Dependent Macrophage Immunomodulation

In situ bone regeneration and vertical bone augmentation have been huge problems in clinical, always imposing a significant economic burden and causing patient suffering. Herein, MgZnYNd magnesium alloy rod implantation in mice femur results in substantial subperiosteal new bone formation, with osteoimmunomodulation playing a pivotal role. Abundant macrophages are attracted to the subperiosteal new bone region and proved to be the most important regulation cells for bone regeneration. Periosteum stripping, macrophage depletion, and interleukin-10 (IL-10) blockage effectively diminish the MgZnYNd alloy-induced subperiosteal osteogenesis. Mechanistically, the degradation products of MgZnYNd alloy promote M2 macrophage polarization and the secretion of anti-inflammatory cytokine IL-10, which enhances periosteum-derived stem cells (PDSCs) osteogenesis through the JAK1-STAT3 pathway. An anti-IL-10 neutralizing antibody or STAT3 inhibitor significantly inhibits M2 macrophage-mediated osteogenic differentiation of PDSCs. Transcriptomic and proteomics reveal that periostin is the core regulator of PDSCs osteogenesis differentiation. Furthermore, a novel clinical translation application of Mg-induced subperiosteal osteogenesis is developed, demonstrating its ability to preserve the height and width of the alveolar crest in rats and rabbits following tooth extraction. Collectively, these findings unveil a previously undefined role for Mg alloy-induced subperiosteal osteogenesis via macrophage-mediated osteoimmunomodulation, suggesting the therapeutic potential of magnesium alloy in bone regeneration and bone augmentation.

Bone marrow mesenchymal stem cell-derived exosomal miR-181a-5p promotes M2 macrophage polarization to alleviate acute pancreatitis through ZEB2-mediated RACK1 ubiquitination.

As a common digestive disease, acute pancreatitis (AP) often threatens the life of patients. Bone marrow mesenchymal stem cells (BMSCs) derived exosomes have exhibited some benefits for AP. However, the mechanism remains unclear and deserves to be further investigated. The characteristics of BMSCs-exosomes (BMSCs-Exos) were identified. The abundance of genes and proteins was evaluated using quantitative real-time PCR (RT-qPCR), western blot, enzyme-linked immunosorbent assay (ELISA) and IF assay. Cell apoptosis and CD206-positive cells were measured by flow cytometry. The interactions among miR-181a-5p, Zinc finger E-box binding homeobox2 (ZEB2) and Receptor for Activated C Kinase 1 (RACK1) were verified using dual luciferase reporter assay, RNA immunoprecipitation (RIP), coimmunoprecipitation (Co-IP). BMSCs-Exos effectively improved AP injury through restraining AR42J cell apoptosis and promoting M2 macrophage polarization, which was realized due to BMSCs-Exos harboring an abundance of miR-181a-5p. Further experiments validated miR-181a-5p silenced ZEB2 and ZEB2 reduced RACK1 expression through mediating RACK1 ubiquitination. ZEB2 knockdown decreased AR42J cell apoptosis and induced M2 macrophage polarization to alleviate AP injury, whereas RACK1 downregulation abolished these phenomena. BMSCs-Exos harboring miR-181a-5p suppressed AR42J cell apoptosis and promoted M2 macrophage polarization to delay AP progression through ZEB2-mediated RACK1 ubiquitination.

BMSCs Downregulate CXCL12 by Secreting Exosomal miR-20a-5p to Promote Macrophage M2 Polarization and Alleviate the Development of Sepsis

ABSTRACT Objective Sepsis is a syndrome of the systemic inflammatory response caused by infection that can endanger a patient’s life. The aim of this study was to explore the molecular mechanism by which bone marrow mesenchymal stem cells-derived exosomes (BMSCs-exo) carrying miR-20a-5p regulate the progression of sepsis. Methods Clinical samples from sepsis patients were collected. Mouse and cell models of sepsis were induced by lipopolysaccharide (LPS). The levels of related genes and proteins were determined by RT‒qPCR, Western blotting and ELISA. CCK-8 and flow cytometry assays were used to assess cell viability, apoptosis, and markers of macrophage polarization. Results In septic patients, miR-20a-5p levels were significantly lower and CXCL12 expression was significantly increased. After LPS induction, M2 polarization of macrophages was significantly reduced, the level of inflammatory factors was increased, and apoptosis was increased. The addition of BMSCs-exo increased the miR-20a-5p level and decreased the expression of CXCL12 in macrophages, thereby promoting macrophage M2 polarization and reducing the levels of inflammatory factors. Conclusion This study demonstrated for the first time that BMSCs-exo promoted the polarization of M2 macrophages through the miR-20a-5p/CXCL12 axis, thus alleviating the development of sepsis. These findings provide a new theoretical basis for the targeted treatment of sepsis with exosomes or miR-20a-5p.

Norepinephrine stimulates M2 macrophage polarization via β2-adrenergic receptor-mediated IL-6 production in breast cancer cells

Previous studies have demonstrated that norepinephrine (NE) released during chronic stress promotes breast cancer (BC) metastasis via adrenergic receptors (ARs). However, the effect of NE on tumor-associated macrophage polarization and the underlying mechanisms remain largely unknown. In this study, we aimed to investigate the influence of NE on M2 macrophage polarization, with a particular focus on the crosstalk between macrophages and BC cells. Our results demonstrated that, although NE alone did not directly induce the expression of M2 macrophage markers, conditioned medium from NE-treated MDA-MB-231 human BC cells (NE CM) significantly promoted M2 macrophage polarization in THP-1 macrophages. We found that NE stimulated IL-6 production in MDA-MB-231 cells via β2-AR/NF-κB pathway, which activated STAT3 in THP-1 cells to induce M2 macrophage polarization. NE failed to induce IL-6 production and NF-κB activation when ADRB2 was knocked down in MDA-MB-231 cells. Furthermore, ADRB2 knockdown in cancer cells suppressed NE CM-induced M2 macrophage polarization, as well as M2 macrophage-induced cancer cell migration. Taken together, our results suggest that NE stimulates M2 macrophage polarization by inducing IL-6 secretion from BC cells through a β2-AR-dependent mechanism, which subsequently promotes cancer cell migration. Targeting β2-AR may represent a promising strategy to prevent chronic stress-induced BC metastasis.

3D bioprinting of engineered exosomes secreted from M2-polarized macrophages through immunomodulatory biomaterial promotes in vivo wound healing and angiogenesis

Biomaterial composition and surface charge play a critical role in macrophage polarization, providing a molecular cue for immunomodulation and tissue regeneration. In this study, we developed bifunctional hydrogel inks for accelerating M2 macrophage polarization and exosome (Exo) cultivation for wound healing applications. For this, we first fabricated polyamine-modified three-dimensional (3D) printable hydrogels consisting of alginate/gelatin/polydopamine nanospheres (AG/NSPs) to boost M2-exosome (M2-Exo) secretion. The cultivated M2-Exo were finally encapsulated into a biocompatible collagen/decellularized extracellular matrix (COL@d-ECM) bioink for studying angiogenesis and in vivo wound healing study. Our findings show that 3D-printed AGP hydrogel promoted M2 macrophage polarization by Janus kinase/signal transducer of activation (JAK/STAT), peroxisome proliferator-activated receptor (PPAR) signaling pathways and facilitated the M2-Exo secretion. Moreover, the COL@d-ECM/M2-Exo was found to be biocompatible with skin cells. Transcriptomic (RNA-Seq) and real-time PCR (qRT-PCR) study revealed that co-culture of fibroblast/keratinocyte/stem cells/endothelial cells in a 3D bioprinted COL@d-ECM/M2-Exo hydrogel upregulated the skin-associated signature biomarkers through various regulatory pathways during epidermis remodeling and downregulated the mitogen-activated protein kinase (MAPK) signaling pathway after 7 days. In a subcutaneous wound model, the 3D bioprinted COL@d-ECM/M2-Exo hydrogel displayed robust wound remodeling and hair follicle (HF) induction while reducing canonical pro-inflammatory activation after 14 days, presenting a viable therapeutic strategy for skin-related disorders.

MiR-122/NEGR1 axis contributes colorectal cancer liver metastasis by PI3K/AKT pathway and macrophage modulation

Colorectal cancer (CRC) is a prevalent malignant tumor in the gastrointestinal tract, with around 50% of patients experiencing distant metastases, predominantly to the liver. Colorectal cancer liver metastasis (CRLM) is a leading cause of CRC-related death, and effective treatments remain limited. This study aims to identify new targets for predicting and treating CRLM. Bioinformatics analysis highlighted the miR-122/NEGR1 axis as crucial in CRLM. In vitro assays (Colony formation, Wound healing, Transwell) explored the impact of this axis on CRC cell proliferation, invasion, and migration. Dual-Luciferase Reporter Gene Assay and RNA-pulldown confirmed miR-122/NEGR1 interaction. In vivo, CRLM model mice were used to investigate the axis’s effects on tumor metastasis and macrophage polarization. Immunofluorescence (IF), Quantitative Real-time PCR (qRT-PCR), Enzyme-linked Immunosorbent Assay (ELISA), and Western Blot (WB) analyzed macrophage polarization markers and cytokine/protein/RNA expression. Results showed increased miR-122 and decreased NEGR1 in liver metastases compared to primary tumors. The miR-122/NEGR1 axis enhanced CRC cell proliferation, migration, invasion, and affected the PI3K/AKT pathway. Furthermore, reduced NEGR1 promoted M2 macrophage polarization and accelerated liver metastasis in CRLM model mice. In conclusion, the miR-122/NEGR1 axis drives CRC progression and liver metastasis through the PI3K/AKT pathway and M2 macrophage polarization, representing a potential target for the therapy of CRLM.

YAP1 preserves tubular mitochondrial quality control to mitigate diabetic kidney disease

Renal tubule cells act as a primary site of injury in diabetic kidney disease (DKD), with dysfunctional mitochondrial quality control (MQC) closely associated with progressive kidney dysfunction in this context. Our investigation delves into the observed inactivation of yes-associated protein 1 (YAP1) and consequential dysregulation of MQC within renal tubule cells among DKD subjects through bioinformatic analysis of transcriptomics data from the Gene Expression Omnibus (GEO) dataset. Receiver operating characteristic curve analysis unequivocally underscores the robust diagnostic accuracy of YAP1 and MQC-related genes for DKD. Furthermore, we observed YAP1 inactivation, accompanied by perturbed MQC, within cultured tubule cells exposed to high glucose (HG) and palmitic acid (PA). This pattern was also evident in the tubulointerstitial compartment of kidney sections from biopsy-approved DKD patients. Additionally, renal tubule cell-specific Yap1 deletion exacerbated kidney injury in diabetic mice. Mechanistically, Yap1 deletion disrupted MQC, leading to mitochondrial aberrations in mitobiogenesis and mitophagy within tubule cells, ultimately culminating in histologic tubular injury. Notably, Yap1 deletion-induced renal tubule injury promoted the secretion of C-X-C motif chemokine ligand 1 (CXCL1), potentially augmenting M1 macrophage infiltration within the renal microenvironment. These multifaceted events were significantly ameliorated by administrating the YAP1 activator XMU-MP-1 in DKD mice. Consistently, bioinformatic analysis of transcriptomics data from the GEO dataset revealed a noteworthy upregulation of tubule cells-derived chemokine CXCL1 associated with macrophage infiltration among DKD patients. Crucially, overexpression of YAP1 via adenovirus transfection sustained mitochondrial membrane potential, mtDNA copy number, oxygen consumption rate, and activity of mitochondrial respiratory chain complex, but attenuated mitochondrial ROS production, thereby maintaining MQC and subsequently suppressing CXCL1 generation within cultured tubule cells exposed to HG and PA. Collectively, our study establishes a pivotal role of tubule YAP1 inactivation-mediated MQC dysfunction in driving DKD progression, at least in part, facilitated by promoting M1 macrophage polarization through a paracrine-dependent mechanism.

An advanced chitosan based sponges dressing system with antioxidative, immunoregulation, angiogenesis and neurogenesis for promoting diabetic wound healing

Promoting wound nerve regeneration and synchronously initiating angiogenesis are critical factors in the healing process of diabetic wounds. However, existing research on diabetic wounds mainly focuses on angiogenesis, bacterial infection and reactive oxygen species, often failing to coordinate neurogenesis and angiogenesis. To coordinate the symbiosis of nerves and blood vessels in the diabetic wounds, we successfully designed a multifunctional chitosan (CS)-based sponges by regulating the structure of CS specifically for diabetic wound healing. This sponge, which facilitates effective exudate transfer and modulates the wound microenvironment, was constructed using hydroxybutyl CS grafted with thioctic acid (TA), named as HCT sponge. When applied in a humid environment, the hydrophobic side chains of the HCT sponge interact with self-assembled hydrophobic domains, forming gel-sponge composite. Experimental results showed that the adhesion strength of the HCT sponge to wet porcine skin was 70.3 kPa. Additionally, the sponge exhibited favorable degradability, cytocompatibility and antioxidant properties. As it is shown in the experiments in vitro, sponge can not only promote cell proliferation, migration, and blood vessel formation, but also promote M2 macrophage polarization. Moreover, the rat liver and femoral artery injury model validated that the HCT sponge can effectively treat heavy bleeding from wounds efficacy through quickly sealing wounds and the formation of multiple hemostatic dams. In vivo studies indicated that the HCT sponge significantly accelerated the diabetic wound healing process compared to the recombinant bovine basic fibroblast growth factor gel, achieving a better recovery from the HCT sponge after 15 days. Pathological results show that the designed novel sponge holds considerable promise for treating diabetic wound, allowing regenerative neurogenesis and angiogenesis at the wound site, which provides a significant potential for further improving clinical applications.

Luteolin ameliorates periodontitis by modulating mitochondrial dynamics and macrophage polarization via the JAK2/STAT3 pathway

BackgroundPeriodontal disease (PD) is a chronic inflammatory condition affecting oral and systemic health. Luteolin (LUT), a natural flavonoid, has shown anti-inflammatory effects, but its therapeutic potential and mechanisms in PD remain unclear. ObjectiveThis study aimed to investigate the effects of LUT on PD, focusing on its impact on mitochondrial dynamics, macrophage polarization, and the JAK2/STAT3 signaling pathway. MethodsA combination of network pharmacology analysis and in vivo and in vitro experiments was employed. The efficacy of LUT was evaluated using a ligature-induced rat PD model and LPS-stimulated THP-1-derived macrophages. Key assessments included micro-CT for bone loss, flow cytometry for macrophage polarization, and Western blot for pathway analysis. ResultsLUT significantly reduced alveolar bone loss and enhanced M2 macrophage polarization, as indicated by increased CD206 and Arg1 expression. Additionally, it improved mitochondrial function by reducing ROS and restoring membrane potential, decreasing mitochondrial fission, and promoting mitochondrial fusion. Mechanistically, LUT inhibited JAK2/STAT3 phosphorylation, promoting anti-inflammatory effects. ConclusionThese findings suggest that LUT ameliorates periodontal inflammation and bone loss by modulating mitochondrial dynamics, promoting M2 macrophage polarization, and suppressing the JAK2/STAT3 signaling pathway. This highlights LUT as a promising multitarget candidate for PD treatment.

Contribution of IL-17C-mediated macrophage polarization to Type 17 inflammation in neutrophilic asthma

BackgroundIL-17C has been described in a variety of inflammatory diseases driven by neutrophils. However, the role of IL-17C in neutrophilic asthma has not been completely characterized.MethodsThe level of IL-17C in asthmatic patients and mice was assessed. Il-17c-deficient mice or mice treated with exogenous rmIL-17C were performed for OVA/CFA-induced asthmatic mice model. Pulmonary inflammation was evaluated by histological analysis, flow cytometry and cytokine analysis. Il-17re-overexpressed Raw264.7 were used in vitro to investigate the role of IL-17C in macrophage polarization.ResultsHere, we show IL-17C were increased in serum or plasma from asthmatic patients and OVA/CFA-induced asthma mice. In the OVA/CFA-induced model, exogenous rmIL-17C aggravated neutrophil- and Type 17-dominated inflammation and promoted M1 macrophage differentiation, whereas deficiency of Il-17c reversed the pro-inflammatory phenotypes and inhibited the expansion of M1 macrophages. In vitro, IL-17C in synergy with IFN-γ induced STAT1 activation in Il-17re overexpressed Raw264.7 to upregulate M1-related genes expression, and promoted pro-inflammatory M1 polymerization, whereas IL-17C in contrast to the effect of IL-4 inhibited STAT6 activation, to reduce Raw264.7 differentiation to M2 macrophage and functional M2-related genes expression.ConclusionsIL-17C promotes allergic inflammation via M1 polarization of pulmonary macrophages in neutrophilic asthma. Modulation of the IL-17C/IL-17RE axis represents a novel therapeutic target in neutrophilic asthma.

Rational Design of Advanced Gene Delivery Carriers: Macrophage Phenotype Matters.

Nucleic acid delivery in hard-to-transfect macrophages have attracted increasing attention in diverse applications such as defence against bacterial infection. Regulated by microenvironments in specific applications, macrophages have a heterogenous nature and exist in different phenotypes with diverse functions, e.g., pro-inflammatory and anti-inflammatory. However, it is not clear whether macrophage phenotype affects nucleic acid delivery, and which one is harder to transfect, and the design of nucleic acid carriers in harder-to-transfect macrophage phenotypes is largely unexplored. Herein, it is first revealed that nucleic acid delivery efficacy in macrophages is influenced by phenotype: IL-4-treated "M2-like" macrophages with suppressed mammalian target of rapamycin complex 1 (mTORC1) levels are harder-to-transfect than "M1-like" macrophages for mRNA and DNA. This knowledge is then translated to the purpose-design of gene delivery carriers for harder-to-transfect M2 phenotype macrophages dominant upon bacteria immune evasion. By loading chloroquine in tetrasulfide bond-containing organosilica nanoparticles, the resultant composite promotes macrophage M2 polarization to M1 and increases mTORC1 levels for enhanced translation. The design is demonstrated in vitro and in vivo for pathogenic Escherichia coli (E. coli) and methicillin-resistant Staphylococcus aureus (MRSA) infections. It is expected that the findings may provide new knowledge and gene delivery solutions in other applications where the M2 phenotype macrophage is dominant.

HMGB1 Modulates Macrophage Metabolism and Polarization in Ulcerative Colitis by Inhibiting Cpt1a Expression.

Macrophage polarization is involved in the development of ulcerative colitis (UC). This study investigated the mechanism by which high mobility group box-1 protein (HMGB1) regulates macrophage polarization through metabolic reprogramming, thereby contributing to the pathogenesis of UC. Dextran sulfate sodium (DSS) was used to induce colitis in mice. RAW264.7 cells were polarized to M1 or M2 macrophages in vitro by stimulating with lipopolysaccharide (LPS)/interferon-γ (IFN-γ) or Interleukin-4 (IL-4), respectively. Macrophage infiltration and distribution within colon tissue were assessed by immunohistochemistry and flow cytometry. Glycolysis, fatty acid oxidation (FAO), and inflammatory factors were evaluated using relevant reagent kits. Chromatin Immunoprecipitation (ChIP) and luciferase reporter experiments were performed to study the regulation of Carnitine palmitoyltransferase 1A (Cpt1a) promoter transcriptional activity by HMGB1. The mouse UC model showed upregulated HMGB1 and increased macrophage infiltration. Overexpression of HMGB1 promoted M1 macrophage polarization, increased glycolysis, and reduced FAO, whereas knockdown of HMGB1 promoted M2 macrophage polarization, reduced glycolysis, and increased FAO. HMGB1 negatively regulated Cpt1a expression by inhibiting transcription of the Cpt1a promoter. Knockdown of Cpt1a reversed the effects of small interfering RNA targeting HMGB1 (si-HMGB1) on macrophage metabolism and polarization. Administration of adeno-associated virus (AAV)-shHMGB1 in vivo caused a reduction in UC symptoms and inflammation. HMGB1 modulates macrophage metabolism in UC by inhibiting Cpt1a expression, leading to increased M1 polarization. This provides a theoretical basis for the clinical application of HMGB1 inhibitors in the treatment of UC.

BMSC-derived exosomes promote osteoporosis alleviation via M2 macrophage polarization

Osteoporosis is characterized by reduced bone mass due to imbalanced bone metabolism. Exosomes derived from bone mesenchymal stem cells (BMSCs) have been shown to play roles in various diseases. This study aimed to clarify the regulatory function and molecular mechanism of BMSCs-derived exosomes in osteogenic differentiation and their potential therapeutic effects on osteoporosis. Exosomes were extracted from BMSCs. Bone marrow-derived macrophages (BMDMs) were cultured and internalized with BMSCs-derived exosomes. Real-time quantitative PCR was used to detect the expression of macrophage surface markers and tripartite motif (TRIM) family genes. BMDMs were co-cultured with human osteoblasts to assess osteogenic differentiation. Western blot was performed to analyze the ubiquitination of triggering receptor expressed on myeloid cell 1 (TREM1) mediated by TRIM25. An ovariectomized mice model was established to evaluate the role of TRIM25 and exosomes in osteoporosis. Exosomes were successfully isolated from BMSCs. BMSCs-derived exosomes upregulated TRIM25 expression, promoting M2 macrophage polarization and osteogenic differentiation. TRIM25 facilitated the ubiquitination and degradation of TREM1. Overexpression of TREM1 reversed the enhanced M2 macrophage polarization and osteogenic differentiation caused by TRIM25 overexpression. TRIM25 enhanced the protective effect of BMSCs-derived exosomes against bone loss in mice. These findings suggested that BMSCs-derived exosomes promoted osteogenic differentiation by regulating M2 macrophage polarization through TRIM25-mediated ubiquitination and degradation of TREM1. This mechanism might provide a novel approach for treating osteoporosis.

Immunoregulative coating for scarless healing in anterior cruciate ligament reconstruction

Polyethylene terephthalate (PET) artificial ligaments are widely used in anterior cruciate ligament (ACL) reconstruction due to their high tensile strength. However, bone tunnel enlargement around PET ligaments poses a risk for surgical failure. PET's inert surface, lower bioactivity, and mechanical abrasion trigger an M1 macrophage-mediated inflammatory response, leading to excessive, disorganized scar tissue. This scar tissue creates a space-occupying effect at the interface, obstructing graft-bone integration and contributing to bone tunnel enlargement. To address this issue, we developed a multi-layered immune-regulating hydrogel coating for scar-free PET-bone integration. Comprising gelatin methacrylate (GelMA), polyethyleneglycol diacrylate (PEGDA), and sulfated polysaccharide (SCS), the hydrogel forms a hydrogen-bonded lubricating layer to reduce friction. The sustained release of SCS also down-regulates M1 macrophage polarization, inhibiting early scar formation. By eliminating the space-occupying effect of scar tissue, SCS subsequently promotes M2 macrophage polarization. This shift releases endogenous factors that enhance blood vessel formation and new bone growth, ultimately achieving high-quality graft-bone integration. The application of this multi-layered, inflammation-modulating hydrogel coating not only removes scar tissue barriers but also improves graft-bone integration through enhanced angiogenesis and osteogenesis. Moreover, it avoids the overuse of exogenous growth factors and potential complications, offering a more convenient and feasible therapeutic strategy.

Loureirin B Accelerates Diabetic Wound Healing by Promoting TGFβ/Smad-Dependent Macrophage M2 Polarization: A Concerted Analytical Approach Through Single-Cell RNA Sequencing and Experimental Verification.

Diabetic wound (DW) represent a significant clinical challenge and often fail to heal effectively. Loureirin B (LB), a flavonoid extracted from dragon's blood, has shown potential by influencing macrophage polarization and promoting wound healing. However, its mechanisms and efficacy in DW remain to be explored. This study employed single-cell RNA sequencing to analyze the classification of cells in diabetic foot ulcers and to identify the related mechanisms influenced by macrophages. Molecular docking was used to predict the interactions of LB with key proteins in the TGFβ/Smad signaling pathway. The effects of LB on macrophage polarization and wound healing were further validated through invitro and invivo experiments using a DW model. Single-cell analysis identified specific macrophage subtypes involved in the DW healing process and highlighted the role of the TGFβ/Smad pathway. Molecular docking suggested the potential action within the TGFβ/Smad pathway. Invitro studies showed that under high glucose conditions, LB promoted macrophage polarization from pro-inflammatory M1 to healing-promoting M2 and ECM production in fibroblasts by activating TGF-β/Smad signaling. Invivo, LB treatment enhanced wound healing rates in diabetic mice and promoted macrophage M2 polarization and fibroblast synthesis of ECM by activating TGF-β/Smad signaling. LB regulates macrophage M2 polarization and fibroblast synthesis of ECM by activating TGF-β/Smad signaling to promote DW healing. These findings suggest that LB could be a potential therapeutic agent for improving DW healing, emphasizing the need for further clinical studies to explore its efficacy and mechanisms in human subjects.

Pancreatic cancer-derived exosomal miR-510 promotes macrophage M2 polarization and facilitates cancer cell aggressive phenotypes.

Extensive tumor microenvironment (TME) and tumor-associated macrophages (TAMs) contribute to the initiation and progression of pancreatic cancer (PC). Cancer cell-derived exosomal miRNAs that stimulate macrophage M2 polarization might play an important role in the process. In the current study, we observed significant upregulation of miR-510 in PC cell lines in comparison to normal HPDE cell line, with PANC-1 exhibiting the highest and MIA PaCa-2 the lowest miR-510 levels. Functional assays demonstrated that miR-510 overexpression enhanced, while its inhibition reduced, PC cell viability, migration, invasion, and EMT. In vivo, miR-510 mimics promoted tumor growth and macrophage M2 polarization, whereas miR-510 inhibition had the opposite effect. Exosomes from PANC-1 and MIA PaCa-2 cells, characterized by nanoparticle tracking analysis and TEM, contained significantly higher miR-510 levels than those from HPDE cells. Macrophages incubated with conditioned media from these PC cells showed increased M2 polarization markers, a process inhibited by the exosome inhibitor GW4869. The delivery of miR-510 via PC cell-derived exosomes facilitated macrophage M2 polarization and regulated the STAT signaling pathway, suggesting that exosomal miR-510 plays a crucial role in the tumor microenvironment of PC by modulating macrophage M2 polarization.