Macrophages in Tissue Repair, Regeneration, and Fibrosis

Hybrid cell membrane coating orchestrates foreign-body reactions, anti-adhesion, and pro-regeneration in abdominal wall reconstruction

Tension-free synthetic meshes are the clinical standard for hernia repair, but they often trigger immune response-mediated complications such as severe foreign-body reactions (FBR), visceral adhesions, and fibrotic healing, increasing the risk of recurrence. Herein, we developed a hybrid cell membrane coating for macroscale mesh fibers that acts as an immune orchestrator, capable of balancing immune responses with tissue regeneration. Cell membranes derived from red blood cells (RBCs) and platelets (PLTs) were covalently bonded to fiber surfaces using functionalized-liposomes and click chemistry. The fusion of clickable liposomes with cell membranes significantly improved coating efficiency, coverage uniformity, and in vivo stability. Histological and flow cytometric analyses of subcutaneous implantation in rats and mice demonstrated significant biofunctional heterogeneity among various cell membrane coatings in FBR. Specifically, the RBC-PLT-liposome hybrid cell membrane coating markedly mitigated FBR, facilitated host cell infiltration, and promoted M2-type macrophage polarization. Importantly, experimental results of abdominal wall defect repairs in rats indicate that the hybrid cell membrane coating effectively prevented visceral adhesions, promoted muscle regenerative healing, and enhanced the recruitment of Pax7+/MyoD+ muscle satellite cells. Our findings suggest that the clickable hybrid cell membrane coating offers a promising approach to enhance clinical outcomes of hernia mesh in abdominal wall reconstruction.

Dual functional photocatalytic hydrogel coupled with hydrogen evolution and glucose depletion for diabetic wound therapy

Diabetic foot ulcers (DFUs), a common and serious complication of diabetes mellitus, are exacerbated by hyperglycemia-induced chronic inflammation and oxidative stress, which collectively impede the wound-healing process. Effective management requires coordinated regulation of the pathological microenvironment through localized glucose reduction, anti-inflammatory modulation, and reactive oxygen species (ROS) scavenging. This study developed an injectable functionalized hydrogel incorporating a Bi nanocrystal-decorated bismuth tungstate/hydrogen-doped titanium dioxide (Bi2WO6/H-TiO2) heterojunction with dual photocatalytic properties: glucose degradation and hydrogen evolution. Upon exposure to light, the hydrogel exploits glucose in the wound as the sacrificial substrate to simultaneously decrease local glucose concentrations and facilitate in situ hydrogen production. The released hydrogen exhibits potent antioxidant and anti-inflammatory activities, synergizing with glucose consumption to inhibit cellular apoptosis and accelerate tissue repair. A systematic evaluation revealed enhanced cell proliferation and migration in hyperglycemic in vitro models. In vivo experiments using a diabetic murine model demonstrated 50 % wound closure within 3 days, accompanied by improved angiogenesis and collagen remodeling. This photocatalytic synergistic strategy represents a clinically promising modality for diabetic wound treatment by regulating the microenvironment and restoring redox homeostasis.

Molybdoenzymes-emulating bio-heterojunction hydrogel with rapid disinfection and macrophage reprogramming for wound regeneration

Developing hydrogel dressings with the capabilities to accommodate irregular wounds and provide a cascade disinfective-regenerative microenvironment for wound repair is of great importance to combating pathogenic bacteria-infected wounds but remains an ongoing challenge. To address the conundrum, we devise a molybdoenzymes-emulating bio-heterojunction (M-bioHJ) doped double network (DN) hydrogel dressing for bacterial-infected wound healing. The near-infrared (NIR) photothermal effect of the M-bioHJ facilitates the exchange of multiple dynamic crosslinking sites in the hydrogel, endowing the hydrogel with photo-remote reprocessing capabilities to completely accommodate the encountered irregular wounds and ultimately accomplish the admirable therapeutic effect. Meanwhile, the introduced M-bioHJ shows NIR light-enhanced photodynamic activity to induce a massive engendering of reactive oxygen species (ROS), allowing rapid sterilization without reliance on exogenous hydrogen peroxide. Furthermore, the Mo ions released from the M-bioHJ-encapsulated hydrogel can play a crucial role in reprogramming the macrophage phenotype and determining tissue regeneration. Both in vitro and in vivo evidences authenticate the accelerated healing potential of infected wounds through the synergistic effects of photo-reprocessing, disinfection, and macrophage-reprogramming facilitated by the hydrogel. These findings highlight the promising application prospects of such neoteric M-bioHJ-encapsulated hydrogel dressings for wound disinfection and tissue regeneration.

Endogenous dual-responsive and self-adaptive silk fibroin-based scaffold with enhancement of immunomodulation for skull regeneration

Despite the current biomaterials (e.g. titanium mesh and polyether ether ketone) have been applied to clinical skull repair, the limitations on mechanical match, shape adaptability, bioactivity and osteointegration have greatly limited their clinical application. In this work, we constructed a water and inflammatory microenvironment dual-responsive self-adaptive silk fibroin-magnesium oxide-based scaffold with the matrix metalloproteinase-2-responsive gelatin-methacryloyl-interleukin-4 (IL-4) coating, which presented good mechanical compliance, quickly shape matching and intraoperative reprocessability. With the capability of responding to an acute inflammation microenvironment followed by a triggered on-demand release of the IL-4, the combination of immunoactive IL-4 and Mg2+ co-ordinately facilitated metabolic reprogramming by suppressing glycolysis, promoting mitochondrial oxidative phosphorylation and modulating adenosine 5'-monophosphate-activated protein kinase (AMPK) signalling pathways in macrophages, resulting in significantly facilitating M2 macrophage activation. During the stage of tissue remodelling, the sustained release of Mg2+ further promoted macrophage M2 polarization and the expression of anti-inflammatory cytokines, significantly reduced immune response and improved ectopic osteogenesis ability. Meanwhile, the cranial defect models of male rats demonstrated that this scaffold could significantly enhance biomineralized deposition and vascularisation, and achieve good bone regeneration of cranial defects. Overall, the bioactive scaffold provides a promising biomaterial and alternative repair strategy for critical-size skull defect repair.

Multiple omics-based machine learning reveals specific macrophage sub-clusters in renal ischemia-reperfusion injury and constructs predictive models for transplant outcomes

BACKGROUND

Ischemia-reperfusion injury (IRI) is closely associated with numerous severe postoperative complications, including acute rejection, delayed graft function (DGF) and graft failure. Macrophages are central to modulating the aseptic inflammatory response during the IRI process. The objective of this study is to conduct an analysis of the developmental and differentiation characteristics of macrophages in IRI, identify distinct molecules subtypes of IRI, and establish robust predictive strategies for DGF and graft survival.

METHOD

We analyzed scRNA-Seq data from GEO database to identify macrophage sub-clusters specific to renal IRI, and use the hdWGCNA algorithm to screen gene modules closely associated with this sub-cluster. Integrating these module genes with the results from bulk RNA-Seq differential analysis to obtain hub genes, and delineating the different IRI molecular subtypes through consensus clustering based on the expression profiles of hub genes. Innovatively, the gene expression matrix was transformed into a unique graphic pixel module and applied advanced computer vision processing algorithms to construct a DGF predictive model. Additionally, we also employed 111 combinations of 10 machine learning algorithms to develop a predictive signature for graft survival. Finally, we validated the expression of the key gene ANXA1 in a mouse IRI model using qRT-PCR, WB, and IHC.

RESULT

This study successfully identified a subset of macrophages closely associated with renal IRI, and cell communication and pseudo-time analysis implied that they may be instrumental in both the maintenance and exacerbation of the IRI process. Utilizing the expression patterns of hub genes, recipients can be clustered into two subtypes (CI and C2) with unique clinical and molecular features. We innovatively applied deep learning algorithms to construct a model for DGF prediction, which can effectively mitigate batch effects among IRI recipients. Compared to other existing models, our model demonstrated superior performance with AUC of 0.816 and 0.845 in the training and validation set. Furthermore, we also used the random survival forest algorithm to develop a high-precision predictive signature for graft failure. The mouse IRI model confirmed a marked upregulation of ANXA1 mRNA and protein expression in renal tissue following IRI.

CONCLUSION

This study successfully revealed the macrophage sub-cluster closely associated with renal IRI. Two distinct IRI subgroups with different characteristics were identified and robust strategies were constructed for predicting DGF and graft survival, which can offer potential therapeutic targets for the treatment of IRI and reference for early prevention of various postoperative complications.

Macrophage response to fibrin structure mediated by Tgm2-dependent mitochondrial mechanosensing

Following an injury at the implantation position, blood-material interactions form a fibrin architecture, which serves as the initial activator of foreign body response (FBR). However, there is limited knowledge regarding how the topography of fibrin architectures regulates macrophage behavior in mitigating FBR. Mechanical cues of the microenvironment have been reported to shape immune cell functions. Here, we investigated macrophage mechanobiology at the organelle level by constructing heterogeneous fibrin networks. Based on findings in vivo, we demonstrated that adhesion-mediated differentiation of mitochondrial function modulated macrophage polarization. The finite activation of integrin signaling upregulated transglutaminase 2 (Tgm2) in a trans-manner, augments PGC1α-mediated mitochondrial biogenesis. Our study highlighted the previously overlooked spatial structures of host proteins adsorbed on material surfaces, advocating for a paradigm shift in material design strategies, from focusing solely on physical properties to considering the modification of host proteins.

Reprogramming peritoneal macrophages with outer membrane vesicle-coated PLGA nanoparticles for endometriosis prevention

Endometriosis is a chronic inflammatory disease that primarily affects women of reproductive age. The current hormonal treatments are unsuitable for women who wish to conceive, highlighting the need for non-hormonal therapeutic alternatives. In this study, we engineered outer membrane vesicle (OMV)-coated poly (lactic-co-glycolic acid) (PLGA) nanoparticles (OMV-NPs) as a potential therapy for endometriosis. These OMV-NPs were internalized by macrophages more efficiently than bacterial OMVs and preserved the immunostimulatory properties of OMVs. In vivo administration of OMV-NPs in mice achieved prolonged retention in the peritoneal cavity, with effective uptake by nearly 80 % of the peritoneal macrophages. Notably, treatment with OMV-NPs reprogrammed macrophages toward the M1 phenotype, resulting in a significant decrease in the M2 to M1 ratio within the peritoneal cavity and in endometriotic lesions. This shift from M2 to M1 was associated with reduced TGF-β1 production and suppressed myofibroblast activation, which led to substantial inhibition of endometriosis progression. Furthermore, immunohistochemical imaging of paired eutopic and ectopic endometrial tissues from endometriosis patients revealed a positive correlation between M2-polarized macrophages and fibrosis. This finding suggests that reprogramming macrophages with OMV-NPs could be a promising therapeutic approach for endometriosis.

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 practice, always imposing a significant economic burden and causing patient suffering. Herein, MgZnYNd magnesium alloy rod implantation in mouse femur resulted in substantial subperiosteal new bone formation, with osteoimmunomodulation playing a pivotal role. Abundant macrophages were 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) blockade effectively diminished the MgZnYNd alloy-induced subperiosteal osteogenesis. Mechanistically, the degradation products of MgZnYNd alloy promoted M2 macrophage polarization and the secretion of anti-inflammatory cytokine IL-10, which enhanced periosteum-derived stem cells (PDSCs) osteogenesis through the JAK1-STAT3 pathway. An anti-IL-10 neutralizing antibody or STAT3 inhibitor significantly inhibited M2 macrophage-mediated osteogenic differentiation of PDSCs. Transcriptomics and proteomics revealed that periostin is the core regulator of PDSCs osteogenic differentiation. Furthermore, a novel clinical translation application of Mg-induced subperiosteal osteogenesis was 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.

Sirt5-mediated polarization and metabolic reprogramming of macrophage sustain brain function following ischemic stroke

Ischemic stroke has become the leading cause of morbidity and mortality in adults. Reperfusion may initiate inflammatory response and cause damage to brain. Macrophage is supposed to be the major contributor of neuroinflammation and immune response. Hypersuccinylation correlates with neuropathological process post cerebral ischemia, rendering the possibility of functional role of succinylation in regulating recovery from injury. Here we reported that ischemic stroke causes upregulation of global protein succinylation dramatically. Mechanically, Sirt5 expression is repressed upon ischemic stroke, which exerts a crucial role in orchestrating global protein succinylation level. Furthermore, deficiency of Sirt5 enhances infiltration, M1 polarization and metabolic programming of macrophage in response to stroke via succinylation of Pkm2. Physiologically, depletion of Sirt5 enlarges damage region of brain during stroke. Utilization of Sirt5 agonist resveratrol efficiently ameliorates the destructive effects induced by stroke, thereby supporting recovery from brain injury. Our study not only reveal a heretofore unrecognized mechanism underlying the relation between stroke and protein succinylation, but also shed light on clinical potential for management of stroke injury via targeting protein succinylation.

miR-210 overexpression increases pressure overload-induced cardiac fibrosis

Aortic stenosis, a common valvular heart disease, can lead to left ventricular pressure overload, triggering pro-fibrotic responses in the heart. miR-210 is a microRNA that responds to hypoxia and ischemia and plays a role in immune regulation and in cardiac remodeling upon myocardial infarction. This study investigated the effects of miR-210 on cardiac fibrosis caused by pressure overload. Using a mouse model with inducible miR-210 over-expression, we subjected mice to transverse aortic constriction (TAC) to induce pressure overload. Mice with miR-210 over-expression developed eccentric hypertrophy, heightened expression of hypertrophic markers (Nppa and Nppb) and increased cross sectional area of cardiomyocytes, impacting the free wall of the left ventricle. These findings suggest that miR-210 worsens cardiac dysfunction. Furthermore, miR-210 over-expression led to a more robust and sustained inflammatory response in the heart, increased interstitial and perivascular fibrosis, and activation of myofibroblasts. miR-210 also promoted angiogenesis. In vitro, cardiac fibroblasts over-expressing miR-210 showed increased adhesion, wound healing and migration capacity. Our results demonstrate that miR-210 contributes to adverse cardiac remodeling in response to pressure overload, including eccentric hypertrophy, inflammation, and fibrosis.

Topological cues of microparticles train stem cells for tissue repair via mechanotransduction

Microspheres (MPs) and porous microspheres (PMPs) are the two most widely used microparticles in tissue engineering and stem cell therapy. However, how stem cells perceive the topological differences between them to regulate cell function remains to be unclear. Here, we systematically studied the changes in stem cell function under the action of MPs and PMPs and elucidated the related mechanisms. Our findings show that the porous structure of PMPs can be sensed by focal adhesions (FAs), which triggers the synthesis of F-actin to inhibit the phosphorylation and degradation of Yes-associated protein (YAP), while also transmitting stress to the nucleus through the contraction of F-actin, thereby enhancing the nuclear translocation of YAP protein. The activation of YAP significantly enhances the proliferation, osteogenesis, paracrine and glucose metabolism of BMSCs, making them exhibit stronger bone repair ability in both in vivo and in vitro experiments. In summary, this study provides a comprehensive and reliable understanding of the behavior of BMSCs in response to MPs and PMPs. It also deepens our understanding of the association between microparticles' topological cues and biological functions, which will provide valuable guidance for the construction of bone tissue engineering (BTE) scaffolds.

Combined metabolomics and network pharmacology to elucidate the mechanisms of Huiyang Shengji decoction in treating diabetic skin ulcer mice

BACKGROUND

Diabetic skin ulcer is a clinical disorder of glucose metabolism that has a long treatment period and is prone to recurrent episodes. Huiyang Shengji decoction (HYSJD) is an effective traditional Chinese medicine for its clinical treatment, but its metabolic effects in patients with diabetic skin ulcers have not been well studied.

PURPOSE

Our study aimed to investigate the mechanism of pharmacological treatment of HYSJD in treating diabetic skin ulcers.

METHODS

The potential mechanism underlying diabetic wound treatment by HYSJD was screened using network pharmacology. Ultra-high performance liquid chromatography-MS/MS metabolomics analysis and correlation analysis were performed to investigate potential target pathways and genes. Furthermore, the db/db diabetic wound tissues and RAW264.7 macrophage inflammation model verified the mechanism using molecular biology experiments.

RESULTS

In network pharmacology, HYSJD played a mainly therapeutic effect by regulating PI3K/AKT signaling pathway, EGFR tyrosine kinase inhibitor resistance, metabolic pathway, and other related metabolic-related pathways. Metabolomics analysis disclosed that L-lysine content increased, while those of linoleic and deoxycholic acids decreased in plasma between the HYSJD-treated group and the control group, participating in biotin metabolism. Among them, PPARγ played an important role. The experiments conducted in db/db mice indicated that HYSJD facilitates VEGF secretion and PPARγ expression. In vitro experiments have revealed that HYSJD inhibits macrophage ROS production, augments mitochondrial ATP production, elevates mitochondrial membrane potential, and diminishes the mitochondrial ECAR rate. Furthermore, these effects culminate in promoting M2 macrophage polarization through PPARγ activation. The molecular docking results revealed that the active compounds from HYSJD were capable of binding to PPARγ protein primarily through hydrogen bonding interactions. Notably, all binding energies were found to be lower than -3 kcal/mol, indicating strong and favorable interactions between the active compounds and the target receptor.

CONCLUSIONS

The findings suggested that HYSJD regulates biotin metabolism by reducing excess levels of linoleic and deoxycholic acids and increasing levels of L-lysine, which in turn promotes diabetic wound healing by promoting M2 macrophage polarization through PPARγ up-regulation. These findings indicated that HYSJD is a decoction that can effectively treat diabetic skin ulcers.

Molecular and cellular mechanisms underlying peripheral nerve injury-induced cellular ecological shifts: Implications for neuroregeneration

The peripheral nervous system is a complex ecological network, and its injury triggers a series of fine-grained intercellular regulations that play a crucial role in the repair process. The peripheral nervous system is a sophisticated ecological network, and its injury initiates a cascade of intricate intercellular regulatory processes that are instrumental in the repair process. Despite the advent of sophisticated microsurgical techniques, the repair of peripheral nerve injuries frequently proves inadequate, resulting in adverse effects on patients' quality of life. Accordingly, the continued pursuit of more efficacious treatments is of paramount importance. In this paper, a review of the relevant literature from recent years was conducted to identify the key cell types involved after peripheral nerve injury. These included Schwann cells, macrophages, neutrophils, endothelial cells, and fibroblasts. The review was conducted in depth. This paper analyses the phenotypic changes of these cells after injury, the relevant factors affecting these changes, and how they coordinate with neurons and other cell types. In addition, it explores the potential mechanisms that mediate the behaviour of these cells. Understanding the interactions between these cells and their mutual regulation with neurons is of great significance for the discovery of new neuroregenerative treatments and the identification of potential therapeutic targets.

K+-H+ coupling strategy for immune regulation and bone defect repair

Ion homeostasis is crucial for maintaining cell function. Potassium ion (K+) is one of the most important cations in the human body, and it plays key role in maintaining biological activities and cellular functions, including the intricate balance of ion homeostasis that underpins both physiological and pathological processes. This study explored a novel role of K+ ions in regulating immune cell function and promoting tissue repair, especially in macrophage-mediated environments after severe tissue injury. We designed and synthesized a platelet-liposome vesicles loaded KHCO3 (KHCO3@PLV) that precisely delivered potassium bicarbonate to the site of injury extracellular after intravenous injection; then, precise ultrasound-triggered K+ release regulated extracellular K+ concentrations in the local macrophage environment. These effects collectively validate the K+-H+ coupling strategy - a novel mechanism whereby extracellular K+ elevation induces intracellular pH modulation, subsequently activating the AMPK/Nrf2 axis to reprogram macrophage metabolism and facilitating tissue regeneration through resolution of chronic inflammation. The main conclusion of the study is that an elevated extracellular K+ environment, which is an innovative treatment, is a potentially effective strategy for regulating immune responses and promoting repair after severe tissue injury.

Sodium butyrate alleviates colitis by inhibiting mitochondrial ROS mediated macrophage pyroptosis

Inflammatory bowel disease (IBD) is a chronic inflammatory bowel disease with unclear causes and limited treatment options. Sodium butyrate (NaB), a byproduct of dietary fiber in the intestine, has demonstrated efficacy in treating inflammation. However, the precise anti-inflammatory mechanisms of NaB in colon inflammation remain largely unexplored. This study aims to investigate the effects of NaB on dextran sulfate sodium (DSS)-induced colitis in rats. The findings indicate that oral administration of NaB effectively prevent colitis and reduce levels of serum or colon inflammatory factors. Additionally, NaB demonstrated in vitro inhibition of RAW264.7 inflammation cytokines induced by LPS, along with suppression of the ERK and NF-κB signaling pathway activation. Moreover, NaB mitigated LPS and Nigericin-induced RAW264.7 pyroptosis by reducing indicators of mitochondrial damage, including increased mitochondrial membrane potential (JC-1) levels and decreased Mito-ROS production. NaB increases ZO-1 and Occludin expression in CaCo2 cells by inhibiting RAW264.7 pyroptosis. These results suggest that NaB could be utilized as a therapeutic agent or dietary supplement to alleviate colitis.

Cerebral [18F]AIF-FAPI-42-Based PET Imaging of Fibroblast Activation Protein for Non-invasive Quantification of Fibrosis After Ischemic Stroke

The development of fibrosis after injury to the brain or spinal cord limits the regeneration of the central nervous system in adult mammals. However, the extent of fibrosis in the injured brain has not been systematically investigated in mammals in vivo. This study aimed to assess whether [18F]AlF-FAPI-42-based cerebral positron emission tomography (PET) can be utilized to assess the extent of fibrosis in ischemic regions of the brain in vivo. Sprague-Dawley rats underwent permanent occlusion of the right middle cerebral artery (MCAO). On days 3, 7, 14, and 21 after MCAO, the uptake of [18F]AlF-FAPI-42 in the ischemic region of the brain in the MCAO groups surpassed that in the control group (day 0). The specific expression of fibroblast activation protein-α (FAP) in ischemic regions of the brain was also confirmed in immunohistofluorescence experiments in vitro. [18F]AlF-FAPI-42 intensity correlated with the density of collagen deposition in the ischemic hemisphere (p < 0.001). [18F]AlF-FAPI-42 PET/CT imaging demonstrated a specific uptake of radioactivity in the infarcted area in an ischemic stroke patient. PET imaging by using [18F]AlF-FAPI-42 offers a promising non-invasive method for monitoring the progression of cerebral fibrosis caused by ischemic stroke and may facilitate the clinical management of stroke patients. Trial registration: chictr.org.cn ChiCTR2200059004. Registered April 22, 2022.

Mechanisms and Therapeutic Strategies of Macrophage Polarization in Intervertebral Disc Degeneration

Background

Intervertebral disc degeneration (IVDD) is a leading cause of low back pain (LBP), contributing significantly to global disability and productivity loss. Its pathogenesis involves complex processes, including inflammation, cellular senescence, angiogenesis, fibrosis, neural ingrowth, and sensitization. Emerging evidence highlights macrophages as central immune regulators infiltrating degenerated discs, with macrophage polarization implicated in IVDD progression. However, the mechanisms linking macrophage polarization to IVDD pathology remain poorly elucidated.

Methods

A comprehensive literature review was conducted by searching major databases (PubMed, Web of Science, and Scopus) for studies published in the last decade (2014-2024). Keywords included "intervertebral disc degeneration," "macrophage polarization," "inflammation," "senescence," and "therapeutic strategies." Relevant articles were selected, analyzed, and synthesized to evaluate the role of macrophage polarization in IVDD.

Results

Macrophage polarization dynamically influences IVDD through multiple pathways. Pro-inflammatory M1 macrophages exacerbate disc degeneration by amplifying inflammatory cytokines (e.g., TNF-α, IL-1β), promoting cellular senescence, and stimulating abnormal angiogenesis and neural ingrowth. In contrast, anti-inflammatory M2 macrophages may mitigate degeneration by suppressing inflammation and enhancing tissue repair. Therapeutic strategies targeting macrophage polarization include pharmacological agents (e.g., cytokines, small-molecule inhibitors), biologic therapies, gene editing, and physical interventions. Challenges persist, such as incomplete understanding of polarization triggers, lack of targeted delivery systems, and limited translational success in preclinical models.

Conclusion

Macrophage polarization is a pivotal regulator of IVDD pathology, offering promising therapeutic targets. Future research should focus on elucidating polarization mechanisms, optimizing spatiotemporal control of macrophage phenotypes, and developing personalized therapies. Addressing these challenges may advance innovative strategies to halt or reverse IVDD progression, ultimately improving clinical outcomes for LBP patients.

Gold nanoparticles modulate macrophage polarization to promote skeletal muscle regeneration

Skeletal muscle regeneration is a complex process that depends on the interplay between immune responses and muscle stem cell (MuSC) activity. Macrophages play a crucial role in this process, exhibiting distinct polarization states-M1 (pro-inflammatory) and M2 (anti-inflammatory)-that significantly affect tissue repair outcomes. Recent advancements in nanomedicine have positioned gold nanoparticles (Au NPs) as promising tools for modulating macrophage polarization and enhancing muscle regeneration. This review examines the role of Au NPs in influencing macrophage behavior, focusing on their physicochemical properties, biocompatibility, and mechanisms of action. We discuss how Au NPs can promote M2 polarization, facilitating tissue repair through modulation of cytokine production, interaction with cell surface receptors, and activation of intracellular signaling pathways. Additionally, we highlight the benefits of Au NPs on MuSC function, angiogenesis, and extracellular matrix remodeling. Despite the potential of Au NPs in skeletal muscle regeneration, challenges remain in optimizing nanoparticle design, developing targeted delivery systems, and understanding long-term effects. Future directions should focus on personalized medicine approaches and combination therapies to enhance therapeutic efficacy. Ultimately, this review emphasizes the transformative potential of Au NPs in regenerative medicine, offering hope for improved treatments for muscle injuries and diseases.

3D bioprinted biomimetic MOF-functionalized hydrogel scaffolds for bone regeneration: Synergistic osteogenesis and osteoimmunomodulation

Critical-size bone defects remain a significant clinical challenge. The lack of endogenous stem cells with osteogenic differentiation potential in the defect area, combined with the inflammatory responses induced by scaffold implantation, highlights the need for biomaterials that can deliver stem cells and possess inflammatory regulation properties. In this study, we developed a 3D bioprinted gelatin methacrylate (GelMA) hydrogel scaffold modified with luteolin-loaded ZIF-8 (LUT@ZIF-8) nanoparticles, designed to deliver bone marrow mesenchymal stem cells (BMSCs) to the defect site and release bioactive components that promote osteogenesis and modulate the immune microenvironment. The LUT@ZIF-8/GelMA hydrogel scaffolds demonstrated excellent physical properties and biocompatibility. The sustained release of luteolin and zinc ions from the LUT@ZIF-8 nanoparticles conferred antibacterial, osteoinductive, and inflammatory regulation effects. The immune microenvironment modulated by LUT@ZIF-8/GelMA hydrogel scaffolds facilitated osteogenic differentiation of BMSCs. Furthermore, in vivo experiments confirmed the osteogenic and inflammatory regulation capabilities of the LUT@ZIF-8/GelMA hydrogel scaffolds. In conclusion, the 3D bioprinted LUT@ZIF-8/GelMA hydrogel scaffolds exhibit osteoimmunomodulatory properties, presenting a promising strategy for the treatment of bone defects.

Thermo-responsive hydrogel via sustained Co-delivery of TA and PDGF to modulate the diabetic microenvironment and accelerate diabetic wound healing

In modern society, the need for diabetic wound healing is increasing due to the increase in the number of diabetic patients. In particular, chronic inflammation is a major problem in diabetic wounds due to excessive accumulation of reactive oxygen species (ROS). Therefore, it is essential to remove ROS and promote angiogenesis for effective diabetic wound healing. In this study, we developed a thermo-responsive poly(organophosphazene) hydrogel system (TSP-TP) designed to deliver antioxidants and growth factors for a long period of time. The TSP-TP hydrogel stably loads and continuously releases tannic acid (TA) and platelet-derived growth factor (PDGF) through various physical interactions. Effective ROS scavenging induced macrophage polarization and alleviated chronic inflammation, while the sustained release of PDGF promoted angiogenesis, ultimately maximizing wound healing efficacy in a diabetic mouse model. Based on these results, the proposed TSP-TP hydrogel demonstrates synergistic effects through sustained delivery of antioxidants and growth factors, demonstrating a promising system with high applicability in diabetic wound treatment.

A Single-Cell Atlas-Inspired Hitchhiking Therapeutic Strategy for Acute Pancreatitis by Restricting ROS in Neutrophils

Neutrophils can undergo transcriptional and epigenetic reprogramming in disease, thus causing inflammation or modulating tissue repair and fibrosis. A thorough understanding of the neutrophil subpopulation composition and their polarization processes in acute pancreatitis (AP) is essential to open up design of treatments tailored to individual patients. Herein, this study distinct subgroups and two differentiation pathways associated with N1 and N2 polarization during AP by single-cell sequencing. Inspired by this, a hollow manganese dioxide (HMnO2)-based nanoreactor (Pyp@APHM) conjugated with neutrophil-binding Ly-6G antibody and loaded with porphyrin is developed for targeted and in situ modulation of neutrophil polarization. Pyp@APHM can enrich the AP site by hitchhiking on neutrophils and then degrade in response to a weakly acidic environment to simultaneously release manganese ions and porphyrin ligands, enabling in situ synthesis of manganese porphyrin antioxidants. Leveraging this strategy, Pyp@APHM can effectively eliminate reactive oxygen species (ROS) and broadly inhibit both N1 and N2 polarization, as well as enhance tissue oxygenation by generating O2, thereby further mitigating pancreatic inflammation. This study provides a comprehensive single-cell atlas of neutrophils in AP and proposes an innovative hitchhiking therapeutic strategy for AP by restricting ROS in neutrophils.

Angiogenesis, signaling pathways, and animal models

ABSTRACT

The vasculature plays a critical role in homeostasis and health as well as in the development and progression of a wide range of diseases, including cancer, cardiovascular diseases, metabolic diseases (and their complications), chronic inflammatory diseases, ophthalmic diseases, and neurodegenerative diseases. As such, the growth of the vasculature mediates normal development and physiology, as well as disease, when pathologically induced vessels are morphologically and functionally altered owing to an imbalance of angiogenesis-stimulating and angiogenesis-inhibiting factors. This review offers an overview of the angiogenic process and discusses recent findings that provide additional interesting nuances to this process, including the roles of intussusception and angiovasculogenesis, which may hold promise for future therapeutic interventions. In addition, we review the methodology, including those of in vitro and in vivo assays, which has helped build the vast amount of knowledge on angiogenesis available today and identify important remaining knowledge gaps that should be bridged through future research.

M2 Macrophages Mitigate Ocular Surface Inflammation and Promote Recovery in a Mouse Model of Dry Eye

Dry eye disease (DED) is a chronic, progressive, multifactorial condition characterized by tear film instability and ocular surface damage. Ocular surface inflammation, triggered by multiple pathogenic factors, represents one of the key mechanisms in DED pathogenesis. This study aims to investigate the therapeutic effects of anti-inflammatory M2 macrophages conditioned medium (M2-CM) on ocular surface inflammation and their potential mechanisms in improving dry eye symptoms in a mouse model. Mouse macrophages (RAW264.7) were polarized into M2 macrophages by IL-4 under different osmolarities, and M2-CM was collected. Flow cytometry and ELISA were applied to measure the cytokine expression of the M2 macrophages. Primary mouse corneal epithelial cells (CECs) were co-cultured with RAW264.7 and M2 macrophages using a Transwell system. The viability and migration of CECs were assessed using CCK-8 and scratch assays. Mouse DED was established by subcutaneous injection of scopolamine, and the therapeutic effects of M2-CM were evaluated by phenol red thread test, fluorescein staining, and tear film breakup time (TBUT). PCR and immunofluorescence staining were applied to observe inflammatory factors and cells on the ocular surface. M2 macrophages enhanced CEC viability, proliferation, and migration, but hyperosmolarity inhibited M2 macrophage polarization. In the DED model, M2-CM improved ocular surface conditions, reduced pro-inflammatory cytokine expression, and increased anti-inflammatory factors. Immunofluorescence revealed reduced pro-inflammatory cells (M1 macrophages, Th1, and Th17) and increased M2 macrophages in the ocular tissues after M2-CM treatment. These results suggest that M2-CM ameliorates ocular surface inflammation and promotes recovery in DED, offering a potential therapeutic strategy for DED.

The Mechanosensitive PIEZO1 Channel Contributes to the Reaction of RAW264.7 Macrophages to Mechanical Strain

The mechanosensitive channel 'piezo type mechanosensitive ion channel component 1' (PIEZO1) plays a regulatory role in the response of periodontal ligament fibroblasts (PDLFs) to the mechanical strain that occurs during orthodontic tooth movement. In addition to PDLFs, immune cells such as macrophages are also exposed to mechanical stimuli. Macrophages respond to mechanical strain with increased expression of inflammatory mediators. The role of PIEZO1 in this response remains elusive. To investigate the effect of PIEZO1 activation, RAW264.7 macrophages were stimulated with the PIEZO1 activator YODA1 without concurrent application of pressure. To further examine the specific role of PIEZO1 during mechanical strain, RAW264.7 macrophages were exposed to mechanical strain without and with simultaneous inhibition of PIEZO1 either by chemical inhibition (GsMTx4) or siRNA silencing. The expression of genes and proteins involved in orthodontic tooth movement was examined by quantitative PCR, western blot, and enzyme-linked immunosorbent assay (ELISA). Activation of PIEZO1 by YODA1 or mechanical strain increased the expression of inflammatory cytokines and osteoprotegerin (Opg), which is critically involved in bone remodeling processes. Conversely, inhibition of the PIEZO1 channel attenuates the effects of mechanical stress. In conclusion, our data demonstrate that the PIEZO1 channel is a major contributor to the response of macrophages to mechanical strain encountered during orthodontic tooth movement and affects the expression of inflammatory and bone remodeling factors.

Dysfunctional crosstalk between macrophages and fibroblasts under LPS-infected and hyperglycemic environment in diabetic wounds

Diabetic wounds, especially diabetic foot ulcers, present a major clinical challenge due to delayed healing and prolonged inflammation. Macrophage-fibroblast interactions are essential for wound repair, yet this crosstalk is disrupted in diabetic wounds due to hyperglycemia and bacterial infection. This study investigates the dysfunctional communication between macrophages and fibroblasts, focusing on autocrine, paracrine, and juxtacrine signaling in simulated diabetic environments. Using monoculture and co-culture models of THP-1-derived macrophages and primary human dermal fibroblasts, we simulated conditions of normal glucose, LPS-induced infection, high glucose (with AGEs), and combined high glucose (with AGEs) and LPS. Macrophages in hyperglycemic and LPS-infected environments exhibited a pro-inflammatory M1 phenotype with elevated expression of CD80, and STAT1 and increased production of IL-1β, TNF-α, and MMP9. Fibroblast migration was significantly impaired under high glucose conditions, particularly in paracrine model. Secretome profiling showed heightened pro-inflammatory cytokines and proteases, with reduced anti-inflammatory markers (IL-10 and VEGF-A) under hyperglycemic conditions. Paracrine signaling exacerbated the inflammatory response, while juxtacrine signaling showed more moderate effects, conducive to healing. These findings highlight the pathological macrophage-fibroblast crosstalk in diabetic wounds, particularly under hyperglycemic and LPS-infected conditions, offering insights for potential immunomodulatory therapies aimed at restoring effective signaling and improving wound healing outcomes.

Using eQTL Mendelian randomization and transcriptomic analysis to identify the relationship between ion channel genes and intracranial aneurysmal subarachnoid hemorrhage

Aneurysmal subarachnoid hemorrhage (aSAH) is a complex condition associated with high disability and mortality rates, leading to poor clinical outcomes. Previous observational studies have suggested a link between ion channel genes and aSAH, but the causal relationship remains uncertain. This study utilized Mendelian randomization (MR) to explore the causal association between ion channel genes and aSAH, employing 5 MR methods: inverse variance weighted (IVW), MR-Egger, maximum likelihood, weighted median, and weighted mode. If results from these methods are inconclusive, IVW will be prioritized as the primary outcome. Additionally, MR-Egger, MR-PRESSO, and Cochrane Q tests were conducted to assess heterogeneity and pleiotropy. The stability of MR findings was evaluated using the leave-one-out approach; Bonferroni correction tested the strength of the causal relationship between exposure and outcome. The MR analysis revealed that CACNA2D3 was positively correlated with aSAH (OR 1.245; 95% confidence intervals [CI] 1.008-1.537; P = .042), while ANO6 showed a negative correlation (OR 0.728; 95% CI 0.533-0.993; P = .045). Our findings indicate that increased expression of CACNA2D3 promotes aSAH whereas elevated levels of ANO6 inhibit it. Transcriptome data from intracranial aneurysm samples confirmed significant differential expression of CACNA2D3 and ANO6 between ruptured and unruptured groups. CACNA2D3 being higher in ruptured cases while ANO6 was more expressed in unruptured ones. Furthermore, GeneMANIA analysis along with functional enrichment provided insights into risk factors for aSAH. Through MR analysis, we established a causal link between ion channel genes and aSAH, which helps to better understand the pathogenesis of aSAH and provide new therapeutic targets.

Lung tumor immunity: redirecting macrophages through infection-induced inflammation

Macrophages play a central role in maintaining tissue homeostasis and in surveillance against pathogens and disease. In the lung, they can adopt either proinflammatory or anti-inflammatory states depending on the nature of the stimulus. As the predominant immune cells in both the lung tumor microenvironment and in sites of lung infection, the functional plasticity of macrophages makes them key players in determining disease outcome. Accurately defining their inflammatory profiles offers an opportunity to reprogram infection-associated macrophages towards enhanced tumor-killing phenotypes. This review explores how acute inflammation can drive macrophage-mediated antitumor immunity and highlights key molecules and signaling pathways that may be leveraged to therapeutically modulate macrophage function.

Basal and AT2 cells promote IPF-lung cancer co-occurrence via EMT: Single-cell analysis

Idiopathic pulmonary fibrosis (IPF) is a chronic, progressive, fibrotic interstitial lung disease. With IPF, the probability of complication with lung cancer (LCA) increases considerably, and the prognosis is worse than that of simple IPF. To understand the pathological mechanisms and molecular pathways shared by these two diseases, we used the single-cell analysis from the Gene Expression Omnibus (GEO) database, and find that basal cells (BCs) and alveolar type 2 cells (AT2 cells) are important components of lung epithelial cells. Changes in molecular pathways in BCs and AT2 cells may be involved in the common pathogenesis of IPF and LCA. KRT17 and S100A14 in BCs may promote the IPF co-occurrence with LCA by mediating the EMT. WFDC2 and KRT19 may be the elements in AT2 cells that activate the EMT process to promote IPF co-occurrence with LCA. In both IPF and LCA, FN1-WNT axis may be involved in the interaction between BCs and AT2 cells. Importantly, the results of immunofluorescence colocalization experiments on tissue samples from patients with IPF and LCA were consistent with these conclusions. Basal-macrophage interactions may have also induced the IPF co-occurrence with LCA via the CYBA-ERK1/2 axis. The regulation of M2 macrophage polarization by JUN/SOD2-glycolysis axis may therefore be involved in the co-morbidity mechanism of IPF and LCA. Therefore, our results suggest that molecular changes in BCs, AT2 cells and macrophages may play important roles in the pathogenesis of IPF co-occurrence with LCA, and the cellular interactions between these cells may be critical for the progression of both diseases.

Advanced Biomimetic Materials in the Prevention of Tendon Adhesions: Design, Preparation, and Application of Hydrogel and Electrospun fiber Membranes

Tendon adhesion formation results from a fibrotic process between the tendon and surrounding tissues, typically occurring after tendon injury or surgery. This condition significantly impacts the quality of life and motor function. Currently, treating adhesions following the repair of injured tendons remains challenging and is a prominent clinical issue that needs to be addressed. This review compiles the existing pathophysiological mechanisms underlying tendon adhesion formation, with a particular focus on the critical roles of inflammation and inflammatory pathways, growth factors and their associated pathways, as well as peritendinous cellular behaviors in promoting adhesion formation. Furthermore, this paper is dedicated to summarizing the evaluation of hydrogels and electrospun fiber membranes as anti-adhesion materials, emphasizing their design, preparation, and application. Additionally, the success of composite patches created by combining these two materials in preventing tendon adhesions is reviewed, which demonstrates the broad applicability of the hydrogel and electrospun film combination. Finally, the review provides insights into future directions for preventing tendon adhesion formation, focusing on material structure and functional design.

Overexpression of TAFA4 in the dorsal root ganglion ameliorates neuropathic pain in male rats through promoting macrophage M2-Skewing

Neuro-immune interactions between macrophages and primary sensory neurons have been implicated in nerve injury and associated pain. This study aims to explore the function of the TAFA4 as a crucial neuroimmune regulator in modulating macrophage states within the context of neuropathic pain. To elucidate the role of TAFA4 in dorsal root ganglia (DRG) following a chronic constriction injury (CCI) model in male rats, immunofluorescent staining, western blot, flow cytometry analysis and enzyme-linked immunosorbent assay were performed. Microinjection of self-complementary adeno-associated virus expressing TAFA4 mRNA into the L4 and L5 DRGs was conducted to overexpress TAFA4 in the DRGs. Following peripheral nerve injury, we observed a downregulation of TAFA4 in ipsilateral DRG neurons. Restoring this downregulation effectively alleviated the mechanical and thermal nociceptive hypersensitivity by inhibiting pro-inflammatory mediators while promoting the secretion of anti-inflammatory cytokines on day 14 post-CCI. Notably, scAAV-TAFA4 microinjection also facilitated the polarization of macrophages in the DRGs towards the M2 phenotype. Mechanistically, TAFA4 modulates the functions of macrophages in a lipoprotein receptor-related protein 1-dependent manner. Our findings revealed the role of TAFA4 in shifting macrophages in favor of an anti-inflammatory phenotype and enhancing interleukin 10 concentrations in the DRG, suggesting it is a potential analgesic target for alleviating neuropathic pain.

GPR40 activation alleviates pulmonary fibrosis by repressing M2 macrophage polarization through the PKD1/CD36/TGF-β1 pathway

Idiopathic pulmonary fibrosis (IPF) is a chronic, progressive interstitial lung disease characterized by complex aetiologies involving the accumulation of inflammatory cells, such as macrophages, in the alveoli. This process is driven by uncontrolled extracellular matrix (ECM) deposition and the development of fibrous connective tissues. Here, we observed that the mRNA expression of Ffar1, the gene encoding G protein-coupled receptor 40 (GPR40), is repressed, while Cd36 is increased in the bronchoalveolar lavage fluid (BALF), which is predominantly composed of alveolar macrophages, of IPF patients. Furthermore, the GPR40 protein was found to be largely adhered to macrophages and was pathologically downregulated in the lungs of bleomycin (BLM)-induced PF model mice (PF mice) compared with those of control mice. Specific knockdown of GPR40 in pulmonary macrophages by adeno-associated virus 9-F4/80-shGPR40 (AAV9-shGPR40) exacerbated the fibrotic phenotype in the PF mice, and activation of GPR40 by its determined agonist compound SC (1,3-dihydroxy-8-methoxy-9H-xanthen-9-one) effectively protected the PF mice from pathological exacerbation. Moreover, Ffar1 or Cd36 gene knockout mouse-based assays were performed to explore the mechanism underlying the regulation of GPR40 activation in pulmonary macrophages with compound SC as a probe. We found that compound SC mitigated pulmonary fibrosis progression by preventing M2 macrophage polarization from exerting profibrotic effects through the GPR40/PKD1/CD36 axis. Our results strongly support the therapeutic potential of targeting intrinsic GPR40 activation in pulmonary macrophages for IPF and highlight the potential of compound SC in treating this disease.

Nerve- and airway-associated interstitial macrophages mitigate SARS-CoV-2 pathogenesis via type I interferon signaling

Despite vaccines, rapidly mutating viruses such as severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) continue to threaten human health due to an impaired immunoregulatory pathway and a hyperactive immune response. Our understanding of the local immune mechanisms used by tissue-resident macrophages to safeguard the host from excessive inflammation during SARS-CoV-2 infection remains limited. Here, we found that nerve- and airway-associated interstitial macrophages (NAMs) are required to control mouse-adapted SARS-CoV-2 (MA-10) infection. Control mice restricted lung viral distribution and survived infection, whereas NAM depletion enhanced viral spread and inflammation and led to 100% mortality. Mechanistically, type I interferon receptor (IFNAR) signaling by NAMs was critical for limiting inflammation and viral spread, and IFNAR deficiency in CD169+ macrophages mirrored NAM-depleted outcomes and abrogated their expansion. These findings highlight the essential protective role of NAMs in regulating viral spread and inflammation, offering insights into SARS-CoV-2 pathogenesis and underscoring the importance of NAMs in mediating host immunity and disease tolerance.

In vivo and in vitro anti-inflammatory activity of the methanolic leaves extract of Gymnopodium floribundum Rolfe

ETHNOPHARMACOLOGICAL RELEVANCE

Gymnopodium floribundum Rolfe, known locally as "Dzidzilche" or "Ts'its'ilche," is a native species from Mexico and Central America. In Mayan communities, this plant is used to relieve inflammation and diverse respiratory diseases such as colds, catarrh, bronchitis, and asthma. Usually, a decoction of leaves or flowers is prepared and administered orally.

AIM

This research explores the anti-inflammatory effects of the methanol extract of Gymnopodium floribundum Rolfe leaves (MGF) using in vitro and in vivo animal models of inflammation.

METHODS

MGF was characterized by GC-MS, and cytotoxicity was assessed using hemolysis and MTT assays. The antiphlogistic effect in vitro was measuring the release of cytokines, hydrogen peroxide, and nitric oxide in macrophages stimulated with LPS. Additionally, anti- and pro-inflammatory cytokines, prostaglandins, and leukotrienes in serum were quantified in carrageenan-induced mouse paw edema. Finally, 1-fluoro-2,4-dinitrobenzene (DNFB)-induced delayed-type hypersensitivity and TPA-induced ear edema models were analyzed.

RESULTS

Compounds found in MGF, such as D-pinitol and protocatechuic (3,4-dihydroxybenzoic) acid, are reported to exert anti-inflammatory effects. MGF showed no hemolytic or cytotoxic effects. Nevertheless, it displayed in vitro anti-inflammatory activity by decreasing the release of IL-6, IL-1β, TNF-α, hydrogen peroxide, and nitric oxide levels; on the other hand, it increased IL-10 production. Furthermore, the MGF significantly reduced inflammation in mouse models and reduced the release of leukotrienes, prostaglandins, and pro-inflammatory cytokines.

CONCLUSION

Gymnopodium floribundum Rolfe exhibits anti-inflammatory activity by suppressing pro-inflammatory mediators, altering cell migration mechanisms, and raising IL-10 production.

Identification of key genes and immune infiltration mechanisms in limb ischemia-reperfusion injury: a bioinformatics and experimental study

Aim of the study

To establish a cross-tissue bioinformatics model for identifying conserved key genes and immune infiltration mechanisms in ischemia-reperfusion injury (IRI) with experimental validation in limb IRI, including pharmacological targeting of the WNT5A/PLC pathway.

Materials and methods

Transcriptomic data from CTGF-stimulated cardiac myocytes (GSE36073) were analyzed as a surrogate for limb IRI due to shared pathological mechanisms. Random forest, LASSO regression, algorithms identified feature genes, validated in a rat limb IRI model using RT-qPCR, and histology. Pharmacological inhibition (WNT5A inhibitor Box5, PLC inhibitor U-73122) was performed to assess pathway involvement. Immune cell infiltration patterns were analyzed via CIBERSORT.

Results

From 169 differentially expressed genes (116 upregulated, 53 downregulated), machine learning identified four key genes (WNT5A, PLCG, ITPR1, CAMK2A), significantly upregulated in experimental limb IRI (P<0.01). Pharmacological inhibition confirmed their functional roles: Box5 and U-73122 treatment reduced expression of WNT5A and PLC versus IRI controls (P<0.05), showing IRI-induced muscle fiber disruption, edema, and inflammation. Immune analysis revealed myeloid polarization shifts (increased M1, decreased M2 macrophages; P<0.05). WNT5A correlated negatively with memory immune cells, while PLCG, ITPR1, and CAMK2A correlated with lymphocyte subpopulations.

Conclusion

We identified a conserved molecular signature across cardiac and skeletal muscle IRI, with WNT5A/PLC pathway components as mechanistically validated therapeutic targets. Our cross-tissue bioinformatic approach, reinforced by pharmacological and histological evidence, provides a novel framework for IRI analysis when direct patient data are unavailable. Combined targeting of macrophage polarization and cellular activation the WNT5A/PLC axis may offer synergistic therapeutic potential.

Natural saponins and macrophage polarization: Mechanistic insights and therapeutic perspectives in disease management

Macrophage polarization plays a pivotal role in immune homeostasis and disease progression across inflammatory, neoplastic, and metabolic disorders. Saponins, which are natural compounds with steroidal/triterpenoid structures, demonstrate therapeutic potential through immunomodulatory, anti-inflammatory, and anti-tumor activities. This study aims to highlight the potential of key saponins-such as ginsenosides, astragaloside IV, dioscin, platycodin D, pulsatilla saponins, and panax notoginseng saponins-in modulating macrophage polarization and enhancing conventional therapies, particularly in oncology. We conducted structured searches in PubMed, Google Scholar, and SciFinder (2013-2024) using controlled vocabulary, including "saponins," "macrophage polarization," and "therapeutic effects." Our findings demonstrate that saponins significantly modulate immune responses and improve treatment efficacy. However, clinical translation is hindered by challenges such as poor bioavailability and safety concerns, which limit systemic exposure and therapeutic utility. To overcome these barriers, innovative delivery strategies, including nanoemulsions and engineered exosomes, are essential for enhancing pharmacokinetics and therapeutic index. Future research should prioritize elucidating the molecular mechanisms underlying saponin-mediated macrophage polarization, identifying novel therapeutic targets, and optimizing drug formulations. Addressing these challenges will enable the restoration of immune balance and more effective management of diverse diseases.

A Novel Injectable Cell-Loaded Hydrogel System for Cartilage Repair: In Vivo and In Vitro Study

Polyhydroxyalkanoates are promising biomaterials, but their application in cartilage repair is still limited. In this study, an injectable thermosensitive hydrogel poly(3-hydroxybutyrate-co-3-hydroxyvalerate-co-3-hydroxyhexanoate)-Polyethylene Glycol (PEG)/hyaluronic acid/kartogenin was prepared from 3-hydroxybutyrate, 3-hydroxyvalerate, 3-hydroxyhexanoate, hyaluronic acid, and kartogenin. The hydrogels are porous, temperature-sensitive, and hydrophilic and have good compressive modulus. Mesenchymal stem cells derived from peripheral blood can proliferate on the hydrogels under two- and three-dimensional cultures. In addition, the hydrogel has the ability to induce chondrogenic differentiation of stem cells and induce M2 differentiation of macrophages. The hydrogel loaded with peripheral blood mesenchymal stem cells can repair cartilage defects in the knee joints of New Zealand rabbits and the newly formed cartilage was identified as type II collagen. Overall, this newly developed system could provide a new treatment option for repairing cartilage defects. Impact Statement In this study, poly(3-hydroxybutyrate-co-3-hydroxyvalerate-co-3-hydroxyhexanoate) was modified with hyaluronic acid and kartogenin to synthesize a thermosensitive injectable hydrogel scaffold. The scaffold has anti-inflammatory and cartilage-promoting effects. This study used the scaffold to carry peripheral blood mesenchymal stem cells to repair cartilage defects in rabbit knee joints, providing a new idea for the treatment of cartilage defects.

Endoneurial immune interplay in peripheral nerve repair: insights and implications for future therapeutic interventions

The mechanisms underlying axonal injury and repair in peripheral nerves, whether due to traumatic damage or autoimmune neuropathies, are complex and not yet fully understood. Recent research indicates that an orchestrated interplay between damaged neurons, Schwann cells, and especially endoneurial immune cells such as macrophages or T cells is crucial to achieve satisfactory nerve recovery. Following axonal injury, degenerating axons and reactive Schwann cells release chemoattractants and cytokines that recruit immune cells into the endoneurium. Among them, macrophages play a pivotal role by clearing axonal and myelin debris and subsequently creating a pro-regenerative microenvironment that supports axonal outgrowth. There is evidence that the timely switch of a pro-inflammatory M1 toward a pro-regenerative M2 macrophage polarization state is crucial for satisfactory nerve recovery, and supportive cellular and humoral factors that influence the endoneurial microenvironment, such as T cells and their cytokines, can substantially impact this fragile recovery process. The latter explains the limited nerve recovery in immune neuropathies, where a pathologic pro-inflammatory shift within the endoneurial immune cell signature hampers axonal outgrowth. This review aims to provide insights into cellular and humoral determinants of the endoneurial microenvironment during nerve damage and repair, which are assumed to hold substantial potential for future therapeutic interventions, especially since current strategies to enhance peripheral nerve recovery are limited to either surgical interventions in traumatic neuropathies or immunomodulatory drugs in immune neuropathies that often fail to achieve satisfactory functional results.

A dual-fluorescence assay for gene delivery vehicle screening in macrophages with an inflammation-inducible reporter construct

Background

Macrophages are a promising target for therapeutics in various applications such as regenerative medicine and immunotherapy for cancer. Due to their plastic nature, macrophages can switch from a non-activated state to activated with the smallest environmental change. For macrophages to be effective in their respective applications, screening for phenotypic changes is necessary to elucidate the cell response to different delivery vehicles, vaccines, small molecules, and other stimuli.

Methods

We created a sensitive and dynamic high-throughput screening method for macrophages based on the activation of NF-κB. For this reporter, we placed an mRFP1 fluorescence gene under the control of an inflammatory promoter, which recruits NF-κB response elements to promote expression during the inflammatory response in macrophages. We characterized the inflammatory reporter based on key markers of an inflammatory response in macrophages including TNF-α cytokine release and immunostaining for inflammatory and non-inflammatory cell surface markers. We compared gene delivery and inflammation of several clinically relevant viral vehicles and commercially available non-viral vehicles. Statistical analysis between groups was performed with a one-way ANOVA with post-hoc Tukey's test.

Results

The reporter macrophages demonstrated a dynamic range after LPS stimulation with an EC50 of 0.61 ng/mL that was highly predictive of TNF-α release. Flow cytometry revealed heterogeneity between groups but confirmed population level shifts in pro-inflammatory markers. Finally, we demonstrated utility of the reporter by showing divergent effects with various leading gene delivery vehicles.

Discussion

This screening technique developed here provides a dynamic, high-throughput screening technique for determining inflammatory response by mouse macrophages to specific stimuli. The method presented here provides insight into the inflammatory response in mouse macrophages to different viral and non-viral gene delivery methods and provides a tool for high-throughput screening of novel vehicles.

Supplementary Information

The online version contains supplementary material available at 10.1186/s44330-025-00030-x.

Extracellular Adipose Matrix Hydrogel Laden with Adipose-Derived Stem Cell Modulates Macrophage Polarization for Enhanced Full-Thickness Skin Wound Repair

Adipose-derived stem cells (ADSC) represent a promising approach for wound healing, while the limited survival rate has restricted their application. To address this, we equipped a hydrogel from acellular porcine adipose tissue (HAPA) with ADSC to fabricate the HAPA + ADSC composite hydrogel. In addition to serving as a carrier for stem cell delivery, the bioactive components of the HAPA hydrogel support immune regulation and tissue repair. In this study, we demonstrated that the HAPA + ADSC composite could effectively modulate macrophage polarization, promote angiogenesis, and regulate extracellular matrix (ECM) deposition and remodeling, thereby substantially accelerating wound healing. Additionally, transcriptomic sequencing analysis indicated that the HAPA + ADSC composite upregulated Nfkbia and Nfkbie to inhibit the nuclear transcription of RelA-p50 heterodimer so that macrophages polarization toward an M1 phenotype is suppressed. The combined effects of ADSC and HAPA hydrogel make it a promising candidate for functional skin wound healing.

Controlled release of ionic carrier hydrogels for sequential immunomodulation to facilitate stage-specific treatment of infectious wound

Infected wounds present a significant clinical challenge, exacerbated by antibiotic resistance, which complicates effective treatment. This study introduces a hydrogel (CC/AP@CM) embedded with core-shell bioactive glass nanoparticles designed for the controlled, sequential release of copper (Cu2+) and magnesium (Mg2+) ions. The hydrogel is crosslinked via a Schiff base reaction, endowing it with injectable, self-healing, and adhesive properties. Notably, the bilayer structure of the bioactive glass within the hydrogel allows an initial release of Cu2+ ions to trigger an early-stage pro-inflammatory and antimicrobial response, followed by Mg2+ ions that support tissue repair and an anti-inflammatory environment. This design aligns with natural wound healing stages, promoting a shift in macrophage polarization from the M1 to M2 phenotype, effectively balancing antibacterial defense with tissue regeneration. The hydrogel demonstrated robust antibacterial efficacy against MRSA, increased angiogenesis, and enhanced fibroblast proliferation and migration in vitro. In a murine wound model, it significantly accelerated wound closure and immune activation, including responses from dendritic cells and T cells. These findings suggest that this hydrogel, through its stage-specific immunomodulatory properties and temporally controlled ion release, offers a promising strategy for treating complex wound infections, supporting both immune defense and tissue healing.

Advances in biomimetic hydrogel for articular cartilage defect repair: Enabling immunomodulation and chondrogenesis

Articular cartilage defects, as a core pathologic feature in the progression of osteoarthritis, and their irreversible degenerative changes lead to functional impairment and socioeconomic burden for tens of millions of patients worldwide. Hydrogels have become key biomaterials in cartilage regeneration with the three-dimensional network structure, programmable mechanical properties, and cell-adaptive microenvironment of biomimetic extracellular matrix. In recent years, several hydrogel systems with in vitro/in vivo repair potential have been developed by modulating the material topology, dynamic mechanical response, and delivery of bioactive factors, and some of them have entered the clinical translation stage. This review systematically explains the biomimetic design principles of hydrogels. It analyzes the immunomodulation and chondrogenic mechanisms mediated by hydrogels, providing a theoretical framework for the development of next-generation smart cartilage repair materials.

M2 Macrophages Mitigate Ocular Surface Inflammation and Promote Recovery in a Mouse Model of Dry Eye

PURPOSE

Dry eye disease (DED) is a chronic, progressive, multifactorial condition characterized by tear film instability and ocular surface damage. Ocular surface inflammation is one of the main mechanisms of DED. This study aims to investigate the therapeutic effects of anti-inflammatory M2 macrophages on ocular surface inflammation and their potential mechanisms in improving dry eye symptoms in a mouse model.

METHODS

Mouse macrophages (RAW264.7) were polarized into M2 macrophages by IL-4 under different osmolarities, and M2 macrophage conditioned medium (M2-CM) was collected. Flow cytometry and ELISA were applied to measure the cytokine expression of the M2 macrophages. Primary mouse corneal epithelial cells (CECs) were co-cultured with RAW264.7 and M2 macrophages using a Transwell system. The viability and migration of CECs were assessed using CCK-8 and scratch assays. Mouse DED was established by subcutaneous injection of scopolamine, and the therapeutic effects of M2-CM were evaluated by phenol red thread test, fluorescein staining, and tear film breakup time (BUT). PCR and immunofluorescence staining were applied to observe inflammatory factors and cells on the ocular surface.

RESULTS

M2 macrophages enhanced CEC viability, proliferation, and migration, but hyperosmolarity inhibited M2 macrophage polarization. In the DED model, M2-CM improved ocular surface conditions, reduced pro-inflammatory cytokine expression, and increased anti-inflammatory factors. Immunofluorescence revealed reduced pro-inflammatory cells (M1 macrophages, Th1, and Th17) and increased M2 macrophages in the ocular tissues after M2-CM treatment.

CONCLUSION

These results suggest that M2-CM ameliorates ocular surface inflammation and promotes recovery in DED, offering a potential therapeutic strategy for DED.

Cellular crosstalk in fibrosis: insights into macrophage and fibroblast dynamics

Pathological fibrosis, the excessive deposition of extracellular matrix and tissue stiffening that causes progressive organ dysfunction, underlies diverse chronic diseases. The fibrotic microenvironment is driven by the dynamic microenvironmental interaction between various cell types; macrophages and fibroblasts play central roles in fibrotic disease initiation, maintenance, and progression. Macrophage functional plasticity to microenvironmental stimuli modulates fibroblast functionality by releasing pro-inflammatory cytokines, growth factors, and matrix remodeling enzymes that promote fibroblast proliferation, activation, and differentiation into myofibroblasts. Activated fibroblasts and myofibroblasts serve as the fibrotic effector cells, secreting extracellular matrix components and initiating microenvironmental contracture. Fibroblasts also modulate macrophage function through the release of their own pro-inflammatory cytokines and growth factors, creating bidirectional crosstalk that reinforces the chronic fibrotic cycle. The intricate interplay between macrophages and fibroblasts, including their secretomes and signaling interactions, leads to tissue damage and pathological loss of tissue function. In this review, we examine macrophage-fibroblast reciprocal dynamic interactions in pathological fibrotic conditions. We discuss the specific lineages and functionality of macrophages and fibroblasts implicated in fibrotic progression, with focus on their signal transduction pathways and secretory signalling that enables their pro-fibrotic behaviour. We then finish with a set of recommendations for future experimentation with the goal of developing a set of potential targets for anti-fibrotic therapeutic candidates. Understanding the cellular interactions between macrophages and fibroblasts provides valuable insights into potential therapeutic strategies to mitigate fibrotic disease progression.

Macrophage polarization in cancer and beyond: from inflammatory signaling pathways to potential therapeutic strategies

Macrophages are innate immune cells distributed throughout the body that play vital roles in organ development, tissue homeostasis, and immune surveillance. Macrophages acquire a binary M1/M2 polarized phenotype through signaling cascades upon sensing different signaling molecules in the environment, thereby playing a core role in a series of immune tasks, rendering precise regulation essential. M1/M2 macrophage phenotypes regulate inflammatory responses, while controlled activation of inflammatory signaling pathways is involved in regulating macrophage polarization. Among the relevant signaling pathways, we focus on the six well-characterized NF-κB, MAPK, JAK-STAT, PI3K/AKT, inflammasome, and cGAS-STING inflammatory pathways, and elucidate their roles and crosstalk in macrophage polarization. Furthermore, the effects of many environmental signals that influence macrophage polarization are investigated by modulating these pathways in vivo and in vitro. We thus detail the physiological and pathophysiological status of these six inflammatory signaling pathways and involvement in regulating macrophage polarization in cancer and beyond, as well as describe potential therapeutic approaches targeting these signaling pathways. In this review, the latest research advances in inflammatory signaling pathways regulating macrophage polarization are reviewed, as targeting these inflammatory signaling pathways provides suitable strategies to intervene in macrophage polarization and various tumor and non-tumor diseases.

Human umbilical cord mesenchymal stem cells improve the survial of flaps by promoting angiogenesis in mice

BACKGROUND

Flap necrosis post-operation disturbs surgeons during plastic and reconstructive surgery. This is caused by hypoperfusion and subsequent ischemia-reperfusion injury, where restricted blood flow followed by restored circulation paradoxically exacerbates tissue damage. Mesenchymal stem cells, which show multidirectional differentiation, provide hematopoietic support and are involved in immune regulation and anti-fibrosis, have inspired research on improving the blood supply of flaps.

METHODS

Primary human umbilical cord mesenchymal stem cells (HuMSCs), were obtained and subcultured for expansion. The cells of the third generation were incubated in a gelatin sponge. Thirty Kunming mice were randomly divided into three groups, and saline, HuMSCs, and HuMSCs-CM were injected preoperatively into the skin of the back. The vessel density was assessed on the tenth day. Forty-eight Kunming mice were divided into two groups. Group A was subdivided into the saline group, HuMSCs, and HuMSCs-CM groups and pretreated as described above. In Group B, the intervention was changed from injection to subcutaneous embedding. Random flaps were made on the back in both groups on the tenth day after pretreatment. The survival rate of the flap was calculated on the seventh day.

RESULTS

HuMSCs-CM significantly increased the microvessel density on the tenth day after pretreatment. The flap survival rate was higher in the cell and CM groups, rising from approximately 13% to 60% in Group A, and to about 75% in Group B. Moreover, subcutaneous embedding of cell-carrying gelatin sponges improved flap survival compared to other interventions.

CONCLUSION

Improved cell incubation conditions can enhance its utility. The application of HuMSCs and their conditioned medium promoted the survival of the flap by inducing neovasculogenesis.

Multi-modal microcarriers reprogram mitochondrial metabolism and activate efferocytosis in macrophages for osteoporotic bone repair

Osteoporotic bone repair remains challenging due to the ineffectiveness of traditional bone repair materials in adapting to the complex immune microenvironment of aging bone tissue. Exploiting the key role of macrophages in regulating this immune environment through the rational design of osteoimmunomodulatory biomaterials has emerged as a promising approach. However, current designs inadequately address the complexity of macrophage functions in aging environments, resulting in suboptimal regulatory effects. Hence, we explored multi-modal microcarriers for enhancing macrophage functionality. In this work, we developed a VGX-1027-loaded mesoporous silica nanosphere composite PLLA microcarrier. The dual-carrier system, featuring a micro-nano hybrid design by spatially separating the mesoporous silica nanoparticles and PLLA microspheres, enables sustained intracellular release of VGX-1027, addressing the chronic nature of osteoporotic fractures. Our studies demonstrate this VGX-1027 microcarrier (PMVGX) promotes M2 macrophage polarization by reprogramming mitochondrial metabolism. Simultaneously, it enhances efferocytosis, facilitating the clearance of dead or senescent cells and reducing inflammatory responses, thus reshaping the aging osteoimmunomodulatory. Furthermore, PMVGX induces macrophages to release osteogenic exosomes containing miR-5106 through paracrine signaling, significantly enhancing osteogenic function. In a postmenopausal osteoporosis animal model, PMVGX exhibited remarkable efficacy in repairing osteoporotic bone defects. This proof-of-concept study demonstrates that our multi-modal microcarrier effectively regulates macrophage functions via mitochondrial homeostasis, efferocytosis, and exosome content, offering great potential for osteoporotic bone repair.

Inhalable myofibroblast targeting nanoparticles for synergistic treatment of pulmonary fibrosis

Pulmonary fibrosis (PF) is a life-threatening interstitial lung disease, characterized by excessive fibroblast activation and collagen deposition, leading to progressive pulmonary function decline and limited therapeutic efficacy. Here, the inhalable, myofibroblast-targeted, and pH-responsive liposomes (FL-NI) were developed for effective codelivery of nintedanib, a mainstream antifibrotic drug in clinic, and siIL11, a small interfering RNA that silences the key profibrosis cytokine IL-11. Notably, FL-NI achieved a 117.8% increase in pulmonary drug delivery by noninvasive inhalation and a 71.5% increase in delivery specifically to fibroblast activation protein-positive myofibroblasts while reducing nonspecific immune cell and epithelial uptake by 29.8 and 55.8%, respectively. The accurate inhalation codelivery of nintedanib and siIL11 into myofibroblasts achieved synergistic effects, effectively enhanced myofibroblast deactivation, reduced pathological collagen deposition by 50.8%, and promoted epithelial tissue repair. FL-NI remodeled the aberrant immune microenvironment without inducing systemic toxicities. Therefore, this work demonstrated the notable potential for this pluripotent strategy for improving PF outcomes and its promising clinical translation.

Macrophage ATG16L1 promotes liver regeneration after partial hepatectomy

Background & Aims

Autophagy plays an important role in liver regeneration. However, most studies are limited to hepatocytes, and the function and mechanism of macrophage autophagy in liver regeneration remain unclear. This study investigated the role of the essential autophagy gene encoding autophagy-related 16-like 1 (ATG16L1), which regulates the macrophage phenotype in liver regeneration.

Methods

We generated FloxP-Atg16l1 (Atg16l1 FL/FL ), Lyz2-Cre Atg16l1 knockout (KO) (Atg16l1 M-KO ), and myeloid-specific Atg16l1-overexpression-knock-in (Atg16l1 OE ) mice. These mice were subjected to 70% partial hepatectomy to demonstrate the role of ATG16L1 in macrophages during liver regeneration.

Results

ATG16L1 expression was significantly upregulated in macrophages during the early stages of liver regeneration. ATG16L1 deletion in macrophages substantially delayed liver regeneration in mice and caused a marked imbalance in Ly6Chi and Ly6Clo macrophage proportions in the liver. RNA-sequencing analysis revealed that, compared with macrophages isolated from Atg16l1 FL/FL mice, those from Atg16l1 M-KO mice exhibited significant downregulation of genes associated with oxidative phosphorylation and upregulation of proinflammatory gene expression. Mechanistically, ATG16L1 loss impaired mitophagy in macrophages, leading to the accumulation of mitochondrial damage and a metabolic shift that promoted proinflammatory macrophage polarization. ATG16L1 deficiency not only promoted macrophage mitochondrial (mt)DNA release and cyclic GMP-AMP synthase-stimulator of interferon genes (STING) activation, but also suppressed STING degradation. Sustained STING hyperactivation and subsequent increased release of downstream interferons further contributed to the inhibition of liver regeneration. Notably, pharmacological activation or genetic overexpression of ATG16L1 significantly enhanced liver regeneration in mice.

Conclusions

ATG16L1 has a pivotal role in liver regeneration by affecting the phenotype and function of macrophages. Thus, targeting ATG16L1 in macrophages could present a novel strategy for promoting liver regeneration.

Impact and implications

The autophagy-related gene ATG16L1 mediates mitophagy, facilitating the clearance of damaged mitochondria in macrophages following partial hepatectomy and maintaining a reparative macrophage phenotype. ATG16L1 deficiency triggers excessive STING activation and inhibits its degradation, thereby suppressing liver regeneration. Thus, targeting ATG16L1 in macrophages could represent a novel strategy to promote liver regeneration.

Monitoring Macrophage Polarization in Infectious Disease, Lesson From SARS-CoV-2 Infection

The concept of macrophage polarization has been largely used in human diseases to define a typology of activation of myeloid cells reminiscent of lymphocyte functional subsets. In COVID-19, several studies have investigated myeloid compartment dysregulation and macrophage polarization as an indicator of disease prognosis and monitoring. SARS-CoV-2 induces an in vitro activation state in monocytes and macrophages that does not match the polarization categories in most studies. In COVID-19 patients, monocytes and macrophages are activated but they do not show a polarization profile. Therefore, the investigation of polarization under basic conditions was not relevant to assess monocyte and macrophage activation. The analysis of monocytes and macrophages with high-throughput methods has allowed the identification of new functional subsets in the context of COVID-19. This approach proposes an innovative stratification of myeloid cell activation. These new functional subsets of myeloid cells would be better biomarkers to assess the risk of complications in COVID-19, reserving the concept of polarization for pharmacological programme evaluation. This review reappraises the polarization of monocytes and macrophages in viral infections, particularly in COVID-19.

Cardiomyocyte proliferation: Advances and insights in macrophage-targeted therapy for myocardial injury

In the mammalian heart, cardiomyocytes undergo a transient window of proliferation that leads to regenerative impairment, limiting cardiomyocyte proliferation and myocardial repair capacity. Cardiac developmental patterns exacerbate the progression of heart disease characterized by myocardial cell loss, ultimately leading to cardiac dysfunction and heart failure. Myocardial infarction causes the death of partial cardiomyocytes, which triggers an immune response to remove debris and restore tissue integrity. Interestingly, when transient myocardial injury triggers irreversible loss of cardiomyocytes, the subsequent macrophages responsible for proliferation and regeneration have a unique immune phenotype that promotes the formation of pre-existing new cardiomyocytes. During mammalian regeneration, mononuclear-derived macrophages and self-renewing resident cardiac macrophages provide multiple cytokines and molecular signals that create a regenerative environment and cellular plasticity capacity in postnatal cardiomyocytes, a pivotal strategy for achieving myocardial repair. Consistent with other human tissues, cardiac macrophages originating from the embryonic endothelium produce a hierarchy of contributions to monocyte recruitment and fate specification. In this review, we discuss the novel functions of macrophages in triggering cardiac regeneration and repair after myocardial infarction and provide recent advances and prospective insights into the phenotypic transformation and heterogeneous features involving cardiac macrophages. In conclusion, macrophages contribute critically to regeneration, repair, and remodeling, and are challenging targets for cardiovascular therapeutic interventions.