Mitochondrial metabolism coordinates stage-specific repair processes in macrophages during wound healing

Regulating macrophage glucose metabolism homeostasis via mitochondrial rheostats by short fiber-microsphere scaffolds for bone repair

The alterations in glucose metabolism flux induced by mitochondrial function changes are crucial for regulating bone immune homeostasis. The restoration of mitochondrial homeostasis, serving as a pivotal rheostat for balancing glucose metabolism in immune cells, can effectively mitigate inflammation and initiate osteogenesis. Herein, an ion-activated mitochondrial rheostat fiber-microsphere polymerization system (FM@CeZnHA) was innovatively constructed. Physical-chemical and molecular biological methods confirmed that CeZnHA, characterized by a rapid degradation rate, releases Ce/Zn ions that restore mitochondrial metabolic homeostasis and M1/M2 balance of macrophages through swift redox reactions. This process reduces the glycolysis level of macrophages by down-regulating the NF-κB p65 signaling pathway, enhances their mitochondrial metabolic dependence, alleviates excessive early inflammatory responses, and promptly initiates osteogenesis. The FM network provided a stable platform for macrophage glycolytic transformation and simulated extracellular matrix microenvironment, continuously restoring mitochondrial homeostasis and accelerating ossification center formation through the release of metal ions from the internal CeZnHA for efficient bone immune cascade reactions. This strategy of bone immunity mediated by the restoration of macrophage mitochondrial metabolic function and glucose metabolic flux homeostasis opens up a new approach to treating bone defects.

Exosomes Derived From Human Gingival Mesenchymal Stem Cells Induce Metabolic Reprogramming of Inflammatory Macrophages

AIM

To investigate the influence and mechanism of exosomes derived from human gingival mesenchymal stem cells (GMSC-Exo) regulating macrophage polarisation through metabolic reprogramming.

MATERIALS AND METHODS

Human acute monocytic leukaemia cells (THP-1)-derived macrophages were treated with GMSC-Exo or Porphyromonas gingivalis lipopolysaccharide (P.g-LPS) in vitro. Metabolic inhibitors were used to study the role of metabolic reprogramming in GMSC-Exo-induced polarisation, while the hypoxia-inducible factor-1 alpha (HIF-1α) modulators were employed to explore the HIF-1α signalling pathway's impact on macrophage metabolic reprogramming. The impact of GMSC-Exo on periodontitis and macrophage metabolism was assessed using a rat model in vivo.

RESULTS

In vitro experiments confirmed that GMSC-Exo promoted the polarisation of macrophages from pro-inflammatory M1 type (classically activated) to anti-inflammatory M2 type (alternatively activated) by promoting metabolic reprogramming (glycolysis to oxidative phosphorylation). In this process, the activation of the HIF-1α signalling pathway was inhibited. In vivo experiments revealed that GMSC-Exo could regulate the inflammatory microenvironment of periodontal tissue and the metabolic pattern of macrophages.

CONCLUSION

By inhibiting the activation of HIF-1α signalling pathway, GMSC-Exo trigger metabolic reprogramming in macrophages, thereby regulating the macrophage transformation from pro-inflammatory M1 phenotype to anti-inflammatory M2 phenotype. This change enhances the local inflammatory environment, aiding tissue repair and regeneration.

Protein O-GlcNAcylation reprograms macrophage-mediated bone remodeling in medication-related osteonecrosis of the jaw

O-Linked N-acetylglucosamine (O-GlcNAcylation) is an essential nutrient-sensitive post-translational modification (PTM) that has emerged as a critical regulator bridging immunometabolic reprogramming and skeletal homeostasis. Medication-related osteonecrosis of the jaw (MRONJ) is a severe complication of anti-resorptive therapy, with limited effective treatments available. Despite four decades of research since its discovery, the therapeutic potential of targeting O-GlcNAcylation in MRONJ remains underexplored. Macrophages orchestrate a pro-inflammatory/anti-inflammatory milieu by polarization and paracrine signaling to promote bone resorption/formation. However, during MRONJ progression, metabolic alterations reshape macrophage function, leading to immune dysregulation and impaired bone remodeling. O-GlcNAcylation serves as a metabolic sensor of nutritional status and cellular stress, influences macrophage phenotype and function, making it a potential target for therapeutic intervention. Currently, extensive research on biomaterials for bone regeneration primarily focuses on enhancing osteogenesis or inhibiting osteoclast activity, often overlooking the impact of PTMs on bone remodeling. In this review, we highlight the emerging role of O-GlcNAcylation in macrophage regulation, discuss its implications in MRONJ pathogenesis, and explore its potential applications in macrophage-targeted biomaterials and nanotherapeutics.

Platelet-rich plasma-derived exosomes accelerate the healing of diabetic foot ulcers by promoting macrophage polarization toward the M2 phenotype

Diabetic foot ulcers (DFUs) impose a significant clinical and socioeconomic burden on patients and healthcare systems. Although platelet-rich plasma (PRP) and platelet-rich plasma-derived exosomes (PRP-Exos) have emerged as promising therapeutic agents in tissue regeneration, the mechanisms underlying the immunomodulatory effects of PRP and PRP-Exos-particularly their role in macrophage polarization-remain poorly understood. In this study, we isolated and characterized PRP-Exos and systematically evaluated their therapeutic potential in diabetic wound healing via comprehensive in vivo and in vitro experiments. Our results revealed that both PRP-gel and PRP-Exos significantly enhanced diabetic wound healing by promoting macrophage polarization toward the anti-inflammatory M2 phenotype. These findings suggest that PRP-Exos represent a novel and effective therapeutic strategy for DFUs, providing a robust rationale for future clinical translation.

Dual-corn-derived nanofiber membrane for subconjunctival injury: Sequential release of dual-natural products for programmed anti-inflammation and anti-fibrosis

Subconjunctival injuries represent significant clinical challenges due to the complexities of post-injury inflammation and subsequent fibrosis, which lead to vision impairment; however, currently, no clinical interventions are available to resolve this problem. In this work, a novel dual drug-loaded core-shell nanofiber membrane based on two corn derivatives was fabricated via coaxial electrospinning to address this unmet clinical need. The nanofiber structure, comprising a polylactic acid shell and a zein core, sequentially released two natural products, rutin and celastrol. The rutin loaded in the polylactic acid shell was rapidly released to produce anti-inflammatory effects, whereas the celastrol loaded in the zein core was slowly released in the later stage to inhibit subconjunctival fibrosis. The in vitro results indicated that this nanofiber membrane platform significantly decreased the secretion of key proinflammatory cytokines and fibrosis biomarkers and reduced the risk of early bacterial invasion. Moreover, the in vivo results revealed that this platform not only ameliorated inflammation but also inhibited late-stage fibrosis, suggesting a promising therapeutic strategy. This study provides an effective exploration of a controlled and safe drug delivery platform, serving as a reference for effective interventions in other related diseases.

Intercellular communication after myocardial infarction: Macrophage as the centerpiece

Post-myocardial infarction (MI) injury, repair, and remodeling are complex biological events orchestrated by the heart and immune cell populations, with immune-inflammation at the core. Macrophages, as the main immune cell population active throughout the post-MI injury to repair processes, are the core of this "drama". Recently, single-cell sequencing and other techniques have revealed the heterogeneity of macrophage origins and the complexity of macrophage subpopulation transformation and intercellular communication after MI. Defining the changes in macrophage subpopulation dynamics and macrophage-centered intercellular communication after MI may represent new targeted therapeutic strategies. It also helps to select the optimal time point for anti-inflammatory or pro-repair accurately. Therefore, in this review, we summarize the major macrophage subpopulations active at different times after MI and their functional characteristics based on gene expression profiles. Meanwhile, we summarize macrophage-centered intercellular communication, focusing on how macrophages interact with cardiomyocytes, neutrophils, fibroblasts, endothelial cells, and other cardiac cells. Together, these dominate the transition from inflammatory injury to fibrotic repair in the infarcted heart. We also focus on the regulatory potential of immune metabolism in macrophage subpopulation transformation and intercellular communication after MI, particularly providing new insights about lactylation. We conclude by emphasizing macrophage-centric targeting strategies and clinical translational potential, to provide ideas for the clinical treatment of MI.

Electroactive Electrospun Nanofibrous Scaffolds: Innovative Approaches for Improved Skin Wound Healing

The incidence and burden of skin wounds, especially chronic and complex wounds, have a profound impact on healthcare. Effective wound healing strategies require a multidisciplinary approach, and advances in materials science and bioengineering have paved the way for the development of novel wound healing dressing. In this context, electrospun nanofibers can mimic the architecture of the natural extracellular matrix and provide new opportunities for wound healing. Inspired by the bioelectric phenomena in the human body, electrospun nanofibrous scaffolds with electroactive characteristics are gaining widespread attention and gradually emerging. To this end, this review first summarizes the basic process of wound healing, the causes of chronic wounds, and the current status of clinical treatment, highlighting the urgency and importance of wound dressings. Then, the biological effects of electric fields, the preparation materials, and manufacturing techniques of electroactive electrospun nanofibrous (EEN) scaffolds are discussed. The latest progress of EEN scaffolds in enhancing skin wound healing is systematically reviewed, mainly including treatment and monitoring. Finally, the importance of EEN scaffold strategies to enhance wound healing is emphasized, and the challenges and prospects of EEN scaffolds are summarized.

A Visible-Light Photocatalysis/Hydrolysis Hydrogen-Generating Nanoplatform for Dynamic Inflammation Management via Immune Metabolism Orchestration during Wound Repair

Effective management of inflammation is one of the promising strategies to prevent the formation of chronic wounds. Despite hydrogen being a prospective molecule for anti-inflammatory effects, the on-demand delivery of hydrogen that could synchronize with the dynamic inflammation stages has yet remained unaddressed. Moreover, its specific immunomodulatory mechanisms are still veiled. In this study, we introduced ISO-ZIF-8@AB, a hydrogen-generating nanoplatform that integrated visible-light photocatalysis and hydrolysis reactions to achieve controllable hydrogen release on demand, functioning with an initial peak release and following a sustained release. With ISO-ZIF-8@AB further loaded into an aligned ECM-like scaffold, the complex significantly alleviated inflammation and prevented protracted unhealing. The bulk-RNA sequencing combined with single-cell RNA sequencing revealed that hydrogen treatment effectively reduced the excessive aggregation and infiltration of innate immune cells. Specifically, hydrogen reduced the proportion of Ptgs2+Nos2+ pro-inflammatory macrophages (PIMs) by mitigating mitochondrial stress and suppressing HIF-1α-induced glycolysis, the immune-metabolic regulation of which reduced harmful crosstalk between PIMs and hypodermal fibroblasts and facilitated extracellular matrix production accompanied by the ultimate wound repair. Overall, this study presented a strategy for controllable hydrogen release in terms of timing and rate, with further discussions regarding the underlying immune-metabolic regulation mechanisms of hydrogen therapy.

Mechanisms and therapeutic opportunities in metabolic aberrations of diabetic wounds: a narrative review

Metabolic aberrations are fundamental to the complex pathophysiology and challenges associated with diabetic wound healing. These alterations, induced by the diabetic environment, trigger a cascade of events that disrupt the normal wound-healing process. Key factors in this metabolic alternation include chronic hyperglycemia, insulin resistance, and dysregulated lipid and amino acid metabolism. In this review, we summarize the underlying mechanisms driving these metabolic changes in diabetic wounds, while emphasizing the broad implications of these disturbances. Additionally, we discuss therapeutic approaches that target these metabolic anomalies and how their integration with existing wound-healing treatments may yield synergistic effects, offering promising avenues for innovative therapies.

USP14-IMP2-CXCL2 axis in tumor-associated macrophages facilitates resistance to anti-PD-1 therapy in gastric cancer by recruiting myeloid-derived suppressor cells

Resistance to anti-PD-1 therapy remains a significant challenge in gastric cancer (GC) treatment. Here, we revealed that the USP14-IMP2-CXCL2 axis in tumor-associated macrophages (TAMs) drove resistance by recruiting myeloid-derived suppressor cells (MDSCs). Endoscopic biopsy samples were obtained from patients with inoperable GC who were candidates for anti-PD-1 therapy. Single-cell RNA sequencing (scRNA-seq) analysis showed a higher prevalence of USP14+ TAMs in therapy-resistant cases, where USP14 was linked to the immunosuppressive phenotype of TAMs. Clinically, GC samples with elevated USP14+ TAM infiltration exhibited decreased CD8+ T cell presence and increased MDSC infiltration. In vivo experiments further confirmed that USP14+ TAMs facilitated resistance to anti-PD-1 therapy in GC, reduced the infiltration of CD8+ T cells, and significantly increased the infiltration of MDSCs. In particular, USP14+ TAMs markedly enhanced the recruitment of MDSCs into the GC microenvironment through the secretion of CXCL2. Mechanistically, USP14 stabilized the m6A reader IMP2 through deubiquitination, thus enhancing CXCL2 expression and secretion. Conversely, the E3 ligase RNF40 facilitated IMP2 degradation via increasing its ubiquitination, with USP14 and RNF40 dynamically balancing IMP2's protein abundance. Furthermore, animal experiments demonstrated that targeted intervention of USP14 markedly enhanced the sensitivity of GC to anti-PD-1 therapy. This study provided a comprehensive exploration of USP14's oncogenic roles in TAMs, suggesting a novel strategy to enhance the efficacy of anti-PD-1 therapy by inhibiting the USP14/IMP2/CXCL2 signaling axis in GC.

Nicotinamide mononucleotide supplementation ameliorates testicular damage induced by ischemia-reperfusion through reshaping macrophage and neutrophil inflammatory properties

BACKGROUND

Ischemia-reperfusion (I/R) injury is the main pathophysiology of testicular torsion-detorsion (T/D). However, there is no safe and effective treatment for testicular I/R injury.

METHODS

The levels of NAD+ related genes were measured in the sham group, I/R + saline-treated group, and I/R + NMN-treated group by quantitative reverse transcription PCR (qRT-PCR). Testicular NAD+, Malondialdehyde (MDA), and superoxide dismutase (SOD) were evaluated. The markers of testicular function, including sperm quality, testosterone secretion, and the number of germ cells, were compared between groups. The reactive oxygen species (ROS), apoptosis, and immune cells were analyzed by flow cytometry. The expression of inflammatory genes, germ cell markers, and the phosphorylation of p65 and STAT3 were assessed by qRT-PCR, immunofluorescence, and western blot, respectively.

RESULTS

In this study, we analyzed the therapeutic potentials of NMN supplementation in testicular injury induced by torsion-detorsion in mice. NMN supplementation could increase testicular NAD+ content, increase serum testosterone levels, prevent Leydig cell and germ cell injury, and improve sperm quantity. Mechanistically, NMN supplementation relieved the sharply hostile immune microenvironment. Specifically, NMN supplementation could mitigate the oxidative stress and cell apoptosis in the I/R injured testes, downregulate the protein expression of p-p65 and p-STAT3 in inflammatory pathways, limit the excessive activation of inflammatory responses in testicular tissues, and reshape the inflammatory properties of macrophages and neutrophils.

CONCLUSIONS

The beneficial effects of NMN supplementation indicated that boosting NAD+ may be a promising and safe strategy to improve clinical outcomes in I/R-induced testicular damage.

Nature-derived microneedles with metal-polyphenolic networks encapsulation for chronic soft tissue defects repair: Responding and remodeling the regenerative microenvironment

The treatment outcomes of traditional patches for chronic soft tissue defects (CSTDs) are unsatisfactory in clinical, owing to the lack of intrinsic bioactivities to orchestrate the intricate regenerative process. To tackle this deficiency, nature-derived microneedles (NMs) composed of silk methacrylate and snail mucus are developed in this study. The resultant NMs have excellent mechanical strength and biological adhesiveness, ensuring suture-free but reliable fixation on implanted site. To enhance the intrinsic bioactivities, metal-polyphenolic networks (MPNs) coordinated from copper (Cu) and curcumin (Cur) are designed and encapsulated into NMs. Cu-Cur MPNs harness the anti-oxidative and anti-inflammatory properties of Cur with the pro-angiogenic properties of Cu, targeting different negative aspects in CSTDs repair. Furthermore, the pH-responsive disassembly of Cu-Cur MPNs can respond to the acidic microenvironment, allowing for burst-free and on-demand drug delivery. Both in-vitro and in-vivo experiments demonstrate that NMs with Cu-Cur MPNs encapsulation (Cu-Cur-NMs) can restore redox homeostasis, reduce inflammatory response, and promote blood vessel formation, thus remodeling the regenerative microenvironment to greatly improve the repair quality of CSTDs. Therefore, the combined advantages of microneedles-based patch system and MPNs-based nanotherapeutic agent are explored for the first time, and our proposed Cu-Cur-NMs represent a multifunctional and promising device for CSTDs repair.

Silk Nonwoven Fabric-Based Dressing with Antibacterial and ROS-Scavenging Properties for Modulating Wound Microenvironment and Promoting Diabetic Wound Healing

The microenvironment of diabetic wounds is exceptionally complex, characterized notably by persistent bacterial infections and the excessive production of reactive oxygen species (ROS). Traditional treatment methods often fall short of achieving ideal results. Consequently, there is an urgent need to develop and implement more advanced and efficient treatment strategies to effectively address the complexity and recalcitrance of diabetic wounds. This study pioneers a novel approach by fabricating a silk fibroin-based nonwoven dressing (SF-Ag-HCA) under neutral conditions, integrating silver ions with dihydrocaffeic acid-modified silk fibroin. Uniquely, this dressing achieves dual functionality: exceptional antibacterial efficacy against common pathogens (E. coli, S. aureus, P. aeruginosa) and robust ROS-scavenging capabilities, effectively mitigating oxidative stress and promoting immune homeostasis. The SF-Ag-HCA dressing not only surpasses conventional materials in regulating the wound microenvironment but also accelerates re-epithelialization and collagen deposition. Animal studies further validate its superior performance in healing diabetic and infected wounds compared to commercial alternatives. This innovative dressing represents a significant advancement in wound care, offering an integrated, cost-effective solution tailored for complex chronic wound management.

A Feedback Loop Driven by H4K12 Lactylation and HDAC3 in Macrophages Regulates Lactate-Induced Collagen Synthesis in Fibroblasts Via the TGF-β Signaling

The decrease in fibroblast collagen is a primary contributor to skin aging. Lactate can participate in collagen synthesis through lysine lactylation by regulating gene transcription. However, the precise mechanism by which lactate influences collagen synthesis requires further investigation. This study demonstrates that the depletion of macrophages mitigates the stimulating effect of lactate on collagen synthesis in fibroblasts. Through joint CUT&Tag and RNA-sequencing analyses, a feedback loop between H4K12 lactylation (H4K12la) and histone deacetylase 3 (HDAC3) in macrophages that drives lactate-induced collagen synthesis are identified. Macrophages can uptake extracellular lactate via monocarboxylate transporter-1 (MCT1), leading to an up-regulation of H4K12la levels through a KAT5-KAT8-dependent mechanism in response to Poly-L-Lactic Acid (PLLA) stimulation, a source of low concentration and persistent lactate, thereby promoting collagen synthesis in fibroblasts. Furthermore, H4K12la is enriched at the promoters of TGF-β1 and TGF-β3, enhancing their transcription. Hyperlactylation of H4K12la inhibits the expression of the eraser HDAC3, while the activation of HDAC3 reduces H4K12la in macrophages and suppresses collagen synthesis in fibroblasts. In conclusion, this study illustrates that macrophages play a critical role in lactate-induced collagen synthesis in the skin, and targeting the lactate-H4K12la-HDAC3-TGF-β axis may represent a novel approach for enhancing collagen production to combat skin aging.

A Constant Filgotinib Delivery Adhesive Platform Based on Polyethylene Glycol (PEG) Hydrogel for Accelerating Wound Healing via Restoring Macrophage Mitochondrial Homeostasis

Skin wound healing is often hindered by disrupted mitochondrial homeostasis and imbalanced macrophage glucose metabolism, posing a critical challenge to improve patient outcomes. Developing new wound healing dressings capable of effectively regulating macrophage immune-metabolic functions remains a pressing issue. Herein, a highly adhesive polyethylene glycol (PEG) hydrogel loaded with the Janus kinase 1 (JAK1) inhibitor Filgotinib (Fil@GEL) is prepared to modulate macrophage metabolic reprogramming and restore normal mitochondrial function. Fil@GEL exhibits superior shear adhesion strength compared to commercially available tissue binder products, providing adequate adhesion for skin wound closure. Additionally, Fil@GEL exhibits the capacity to inhibit M1-type macrophage polarization by suppressing the JAK-STAT signaling pathway, and induces a metabolic shift in macrophages from aerobic glycolysis to oxidative phosphorylation, which results in decreased lactate production, reduced reactive oxygen species (ROS) levels, and the restoration of mitochondrial homeostasis. The Fil@GEL hydrogel significantly accelerates skin wound healing compared to the control group, reduces intra-wound inflammation, and promotes collagen regeneration. In summary, this highly adhesive hydrogel demonstrates exceptional performance as a drug carrier, exerting immunometabolic modulation through firm wound adhesion and sustained filgotinib release, underscoring its substantial potential as an effective wound dressing.

Synergistic Antitumor Immunotherapy via Mitochondria Regulation in Macrophages and Tumor Cells by an Iridium Photosensitizer

Mitochondrial targeting has emerged as an attractive method for antitumor treatment. However, most of the mitochondria targeted drugs focused on inhibiting tumor cells, while their potential for activation of immune responses in the tumor microenvironment has rarely been described. In this study, we report a photosensitive iridium complex MitoIrL2, which enabled the simultaneous mitochondrial modulation of macrophages and tumor cells to achieve synergistic antitumor immunity. The adjustment of the mitochondrial respiratory chain, HIF-1α, and the NF-κB pathway in macrophages drove the metabolic reprogramming from oxidative phosphorylation (OXPHOS) to glycolysis, converting protumor M2 into the antitumor M1 phenotype. Downregulated expression of immunosuppressive checkpoint SIRPα has also been observed on macrophages. Meanwhile, the mitochondrial targeting MitoIrL2 enhanced the immunogenic cell death of tumor cells and reversed the immunosuppressive tumor microenvironment, which activated the systemic immune response and established long-term immune memory in vivo. This work illustrates a promising strategy to simultaneously regulate macrophages toward the antitumor phenotype and enhance immunogenic cell death in tumor cells for synergistic antitumor immunotherapy.

Macrophage peroxisomes guide alveolar regeneration and limit SARS-CoV-2 tissue sequelae

Peroxisomes are vital but often overlooked metabolic organelles. We found that excessive interferon signaling remodeled macrophage peroxisomes. This loss of peroxisomes impaired inflammation resolution and lung repair during severe respiratory viral infections. Peroxisomes were found to modulate lipid metabolism and mitochondrial health in a macrophage type-specific manner and enhanced alveolar macrophage-mediated tissue repair and alveolar regeneration after viral infection. Peroxisomes also prevented excessive macrophage inflammasome activation and IL-1β release, limiting accumulation of KRT8high dysplastic epithelial progenitors following viral injury. Pharmacologically enhancing peroxisome biogenesis mitigated both acute symptoms and post-acute sequelae of COVID-19 (PASC) in animal models. Thus, macrophage peroxisome dysfunction contributes to chronic lung pathology and fibrosis after severe acute respiratory syndrome coronavirus 2 infection.

Spatiotemporal single-cell roadmap of human skin wound healing

Wound healing is vital for human health, yet the details of cellular dynamics and coordination in human wound repair remain largely unexplored. To address this, we conducted single-cell multi-omics analyses on human skin wound tissues through inflammation, proliferation, and remodeling phases of wound repair from the same individuals, monitoring the cellular and molecular dynamics of human skin wound healing at an unprecedented spatiotemporal resolution. This singular roadmap reveals the cellular architecture of the wound margin and identifies FOSL1 as a critical driver of re-epithelialization. It shows that pro-inflammatory macrophages and fibroblasts sequentially support keratinocyte migration like a relay race across different healing stages. Comparison with single-cell data from venous and diabetic foot ulcers uncovers a link between failed keratinocyte migration and impaired inflammatory response in chronic wounds. Additionally, comparing human and mouse acute wound transcriptomes underscores the indispensable value of this roadmap in bridging basic research with clinical innovations.

An active shrinkage and antioxidative hydrogel with biomimetic mechanics functions modulates inflammation and fibrosis to promote skin regeneration

Achieving scar-free skin regeneration in clinical settings presents significant challenges. Key issues such as the imbalance in macrophage phenotype transition, delayed re-epithelialization, and excessive proliferation and differentiation of fibroblasts hinder wound healing and lead to fibrotic repair. To these, we developed an active shrinkage and antioxidative hydrogel with biomimetic mechanical functions (P&G@LMs) to reshape the healing microenvironment and effectively promote skin regeneration. The hydrogel's immediate hemostatic effect initiated sequential remodeling, the active shrinkage property sealed and contracted the wound at body temperature, and the antioxidative function eliminated ROS, promoting re-epithelialization. The spatiotemporal release of LMs (ACEI) during the inflammation phase regulated macrophage polarization towards the anti-inflammatory M2 phenotype, promoting progression to the proliferation phase. However, the profibrotic niche of macrophages induced a highly contractile α-SMA positive state in myofibroblasts, whereas the sustained LMs release could regulate this niche to control fibrosis and promote the correct biomechanical orientation of collagen. Notably, the biomimetic mechanics of the hydrogel mimicked the contraction characteristics of myofibroblasts, and the skin-like elastic modulus could accommodate the skin dynamic changes and restore the mechanical integrity of wound defect, partially substituting myofibroblasts' mechanical role in tissue repair. This study presents an innovative strategy for skin regeneration.

Common immunotoxicity mechanisms of hepatotoxicity induced by raw Polygonum multiflorum and Polygonum multiflorum praeparata: Inhibition of M2 macrophage polarization

Macrophage polarization has been linked to hepatotoxicity induced by raw Polygonum multiflorum (RPM) and Polygonum multiflorum praeparata (PMP), but the regulatory mechanisms behind this remain unclear. This study aims to investigate the regulatory effects of RPM and PMP on M2 macrophages and the potential mechanisms. Sprague-Dawley rats were exposed to RPM and PMP under lipopolysaccharide (LPS) stimulation. RAW264.7 cells induced with IL-4 were treated with RPM and PMP. Under LPS stimulation, both RPM and PMP increased serum enzyme levels and pro-inflammatory factor levels and induced histopathological injury. M1 macrophage infiltration and M1 gene expression in the liver increased, whereas M2 macrophage infiltration and M2 gene expression decreased. RPM and PMP inhibited M2 gene expression and reduced green fluorescence intensity. RNA sequencing and metabolomics revealed that RPM regulated sphingolipid signaling and Janus kinase/signal transducer and activator of transcription signaling pathways, while PMP influenced arginine and proline metabolism, arginine biosynthesis, and cholesterol metabolism pathways. RPM and PMP orchestrate distinct signaling pathways, thereby inhibiting M2 macrophage polarization and inducing hepatotoxicity. This study not only elucidates the pathophysiology underlying RPM- and PMP-induced hepatotoxicity, but also provides insights for the development of new therapeutic interventions.

Mitochondria in cutaneous health, disease, ageing and rejuvenation-the 3PM-guided mitochondria-centric dermatology

Association of both intrinsic and extrinsic risk factors leading to accelerated skin ageing is reflected in excessive ROS production and ir/reversible mitochondrial injury and burnout, as abundantly demonstrated by accumulating research data. Due to the critical role of mitochondrial stress in the pathophysiology of skin ageing and disorders, maintained (primary care) and restored (secondary care) mitochondrial health, rejuvenation and homoeostasis are considered the most effective holistic approach to advance dermatological treatments based on systemic health-supportive and stimulating measures. Per evidence, an effective skin anti-ageing protection, wound healing and scarring quality - all strongly depend on the sustainable mitochondrial functionality and well-balanced homoeostasis. The latter can be objectively measured and, if necessary, restored in a systemic manner by pre- and rehabilitation algorithms tailored to individualised patient profiles. The entire spectrum of corresponding innovations in the area includes natural and systemic skin rejuvenation, aesthetic and reconstructive medicine, sustainable skin protection and targeted treatments of skin disorders. Contextually, mitochondria-centric dermatology is instrumental for advanced 3PM-guided approach which makes a good use of predictive multi-level diagnostics and targeted protection of skin against both - the health-to-disease transition and progression of relevant disorders. Cost-effective targeted protection and new treatment avenues focused on sustainable mitochondrial health and physiologic homoeostasis are proposed in the article including in-depth analysis of patient cases and exemplified 3PM-guided care with detailed mechanisms and corresponding expert recommendations presented.

Pro-inflammatory macrophages produce mitochondria-derived superoxide by reverse electron transport at complex I that regulates IL-1β release during NLRP3 inflammasome activation

Macrophages stimulated by lipopolysaccharide (LPS) generate mitochondria-derived reactive oxygen species (mtROS) that act as antimicrobial agents and redox signals; however, the mechanism of LPS-induced mitochondrial superoxide generation is unknown. Here we show that LPS-stimulated bone-marrow-derived macrophages produce superoxide by reverse electron transport (RET) at complex I of the electron transport chain. Using chemical biology and genetic approaches, we demonstrate that superoxide production is driven by LPS-induced metabolic reprogramming, which increases the proton motive force (∆p), primarily as elevated mitochondrial membrane potential (Δψm) and maintains a reduced CoQ pool. The key metabolic changes are repurposing of ATP production from oxidative phosphorylation to glycolysis, which reduces reliance on F1FO-ATP synthase activity resulting in a higher ∆p, while oxidation of succinate sustains a reduced CoQ pool. Furthermore, the production of mtROS by RET regulates IL-1β release during NLRP3 inflammasome activation. Thus, we demonstrate that ROS generated by RET is an important mitochondria-derived signal that regulates macrophage cytokine production.

In situ photocrosslinkable hydrogel treats radiation-induced skin injury by ROS elimination and inflammation regulation

The clinical management of radiation-induced skin injury (RSI) poses a significant challenge, primarily due to the acute damage caused by an overabundance of reactive oxygen species (ROS) and the ongoing inflammatory microenvironment. Here, we designed a dual-network hydrogel composed of 5 % (w/v) Pluronic F127 diacrylate and 2 % (w/v) hyaluronic acid methacryloyl, termed the FH hydrogel. To confer antioxidant and anti-inflammation properties to the hydrogel, we incorporated PVP-modified Prussian blue nanoparticles (PPBs) and resveratrol (Res) to form PHF@Res hydrogels. PHF@Res hydrogels not only exhibited multiple free radical scavenging activities (DPPH, ABTS), but also displayed multiple enzyme-like activities (POD-, catalase). Meanwhile, PHF@Res-2 hydrogels significantly suppressed intracellular ROS and promoted the migration of fibroblasts in a high-oxidative stress environment. Moreover, in the RSI mouse model, the PHF@Res-2 hydrogel regulated inflammatory factors and collagen deposition, significantly reduced epithelial hyperplasia, promoted limb regeneration and neovascularization, and accelerated wound healing, outperforming the commercial antiradiation formulation, Kangfuxin. The PHF@Res-2 hydrogel dressing shows great potential in accelerating wound healing in RSI, offering tremendous promise for clinical wound management and regeneration.

MSCs-EVs harboring OA immune memory reprogram macrophage phenotype via modulation of the mt-ND3/NADH-CoQ axis for OA treatment

BACKGROUND

Osteoarthritis (OA) is a prevalent degenerative joint disease and current therapies are insufficient to halt its progression. Mesenchymal stem cells-derived extracellular vesicles (MSCs-EVs) offer promising therapeutic potential for OA treatment, and their efficacy can be enhanced through strategic engineering approaches.

METHODS

Inspired by the immune memory of the adaptive immune system, we developed an engineered strategy to impart OA-specific immune memory to MSCs-EVs. Using Luminex technology, inflammatory factors (IFN-γ, IL-6, and TNF-α), which mimic the OA inflammatory microenvironment, were identified and used to prime MSCs, generating immune memory-bearing MSCs-EVs (iEVs). Proteomic analysis and complementary experiments were conducted to evaluate iEVs' effects on macrophage phenotypic reprogramming.

RESULTS

iEVs, particularly IL-6-EV, exhibited potent immunoregulatory functions along with the ability to modulate mitochondrial metabolism. Both in vitro and in vivo, IL-6-EV significantly reprogrammed macrophages towards the M2 subtype, effectively suppressing articular inflammation and OA progression. Mechanistic studies revealed that IL-6-EV facilitated M2 polarization by regulating mitochondrial oxidative phosphorylation via the mt-ND3/NADH-CoQ axis.

CONCLUSION

This study introduces a strategy to enhance MSCs-EVs' therapeutic efficacy in OA. Multi-omics analysis and biological validation demonstrate its potential, providing new insights for MSCs-EVs' future application in OA and other clinical conditions.

Functional transformation of macrophage mitochondria in cardiovascular diseases

Mitochondria are pivotal in the modulation of macrophage activation, differentiation, and survival. Furthermore, macrophages are instrumental in the onset and progression of cardiovascular diseases. Hence, it is imperative to investigate the role of mitochondria within macrophages in the context of cardiovascular disease. In this review, we provide an updated description of the origin and classification of cardiac macrophages and also focused on the relationship between macrophages and mitochondria in cardiovascular diseases with respect to (1) proinflammatory or anti-inflammatory macrophages, (2) macrophage apoptosis, (3) macrophage pyroptosis, and (4) macrophage efferocytosis. Clarifying the relationship between mitochondria and macrophages can aid the exploration of novel therapeutic strategies for cardiovascular disease.

Effects of a Bioengineered Allogeneic Cellularized Construct (BACC) on Primary Human Macrophage Phenotype

The mechanisms behind the pro-healing effects of multicellular, bioengineered allogeneic cellularized constructs (BACC) are not known. Macrophages are key regulators of every phase of the wound healing process and the primary cells that mediate the response to biomaterials. It is hypothesized that cells within the BACC modulate macrophage behavior, which may contribute to the mechanism by which BACC promotes healing. To probe the influence of cells within the BACC compared to effects of the underlying collagen substrate, primary human macrophages are cultured in direct or indirect contact with BACC or with the same collagen substrate used in the BACC manufacturing. Macrophage phenotype is characterized over time via multiplex gene expression, protein secretion, multidimensional flow cytometry, and functional assays with fibroblasts and endothelial cells. The BACC causes macrophages to exhibit a predominately reparative phenotype over time compared to relevant collagen substrate controls, with multiple subpopulations expressing both pro-inflammatory and reparative markers. Conditioned media from macrophage-BACC co-cultures causes distinct effects on fibroblast and endothelial cell proliferation, migration, and network formation. Given the critical role of the reparative macrophage phenotype in wound healing, these results suggest that modulation of macrophage phenotype may be a critical part of the mechanisms behind BACC's pro-healing effects.

Silica-induced ROS in alveolar macrophages and its role on the formation of pulmonary fibrosis via polarizing macrophages into M2 phenotype: a review

Alveolar macrophages (AMs), the first line against the invasion of foreign invaders, play a predominant role in the pathogenesis of silicosis. Studies have shown that inhaled silica dust is recognized and engulfed by AMs, resulting in the production of large amounts of silica-induced reactive oxygen species (ROS), including particle-derived ROS and macrophage-derived ROS. These ROS change the microenvironment of the AMs where the macrophage phenotype is stimulated to swift from M0 to M1 and/or M2, and ultimately emerge as the M2 phenotype to trigger silicosis. This is a complex process accompanied by various molecular biological events. Unfortunately, the detailed processes and mechanisms have not been systematically described. In this review, we first systematically introduce the process of ROS induced by silica in AMs. Then, describe the role and molecular mechanism of M2-type macrophage polarization caused by silica-induced ROS. Finally, we review the mechanism of pulmonary fibrosis induced by M2 polarized AMs. We conclude that silica-induced ROS initiate the fibrotic process of silicosis by inducing macrophage into M2 phenotype, and that targeted intervention of silica-induced ROS in AMs can reprogram the macrophage polarization and ameliorate the pathogenesis of silicosis.

Histone lactylation in macrophage biology and disease: from plasticity regulation to therapeutic implications

Epigenetic modifications have been identified as critical molecular determinants influencing macrophage plasticity and heterogeneity. Among these, histone lactylation is a recently discovered epigenetic modification. Research examining the effects of histone lactylation on macrophage activation and polarization has grown substantially in recent years. Evidence increasingly suggests that lactate-mediated changes in histone lactylation levels within macrophages can modulate gene transcription, thereby contributing to the pathogenesis of various diseases. This review provides a comprehensive analysis of the role of histone lactylation in macrophage activation, exploring its discovery, effects, and association with macrophage diversity and phenotypic variability. Moreover, it highlights the impact of alterations in macrophage histone lactylation in diverse pathological contexts, such as inflammation, tumorigenesis, neurological disorders, and other complex conditions, and demonstrates the therapeutic potential of drugs targeting these epigenetic modifications. This mechanistic understanding provides insights into the underlying disease mechanisms and opens new avenues for therapeutic intervention.

The Mitochondrial Transplantation: A New Frontier in Plastic Surgery

Challenges such as difficult wound healing, ischemic necrosis of skin flaps, and skin aging are prevalent in plastic surgery. Previous research has indeed suggested that these challenges in plastic surgery are often linked to cellular energy barriers. As the powerhouses of the cell, mitochondria play a critical role in sustaining cellular vitality and health. Fundamentally, issues like ischemic and hypoxic damage to organs and tissues, as well as aging, stem from mitochondrial dysfunction, which leads to a depletion of cellular energy. Hence, having an adequate number of high-quality, healthy mitochondria is vital for maintaining tissue stability and cell survival. In recent years, there has been preliminary exploration into the protective effects of mitochondrial transplantation against cellular damage in systems such as the nervous, cardiovascular, and respiratory systems. For plastic surgery, mitochondrial transplantation is an extremely advanced research topic. This review focuses on the novel applications and future prospects of mitochondrial transplantation in plastic surgery, providing insights for clinicians and researchers, and offering guidance to patients seeking innovative and effective treatment options.

Orchestration of Macrophage Polarization Dynamics by Fibroblast-Secreted Exosomes during Skin Wound Healing

Macrophages undertake pivotal yet dichotomous functions during skin wound healing, mediating both early proinflammatory immune activation and late anti-inflammatory tissue remodeling processes. The timely phenotypic transition of macrophages from inflammatory M1 to proresolving M2 activation states is essential for efficient healing. However, the endogenous mechanisms calibrating macrophage polarization in accordance with the evolving tissue milieu remain undefined. In this study, we reveal an indispensable immunomodulatory role for fibroblast-secreted exosomes in directing macrophage activation dynamics. Fibroblast-derived exosomes permitted spatiotemporal coordination of macrophage phenotypes independent of direct intercellular contact. Exosomes enhanced macrophage sensitivity to both M1 and M2 polarizing stimuli, yet they also accelerated timely switching from M1 to M2 phenotypes. Exosome inhibition dysregulated macrophage responses, resulting in aberrant inflammation and impaired healing, whereas provision of exogenous fibroblast-derived exosomes corrected defects. Topical application of fibroblast-derived exosomes onto chronic diabetic wounds normalized dysregulated macrophage activation to resolve inflammation and restore productive healing. Our findings elucidate fibroblast-secreted exosomes as remote programmers of macrophage polarization that calibrate immunological transitions essential for tissue repair. Harnessing exosomes represents a previously unreported approach to steer productive macrophage activation states with immense therapeutic potential for promoting healing in chronic inflammatory disorders.

Hydrogen-Rich Saline Combined With Vacuum Sealing Drainage Promotes Wound Healing by Altering Biotin Metabolism

Impaired wound healing affects the life quality of patients and causes a substantial financial burden. Hydrogen-rich medium is reported to have antioxidant and anti-inflammatory effects. However, the role of hydrogen-rich saline (HRS) in cutaneous wound healing remains largely unexplored, especially by metabolomics. Thus, untargeted metabolomics profiling was analysed to study the effects and mechanism of HRS combined with vacuum sealing drainage (VSD) in a rabbit full-thickness wound model. Our results indicated that the combination treatment of HRS and VSD could accelerate wound healing. In vitro experiments further confirmed its effects on HaCaT keratinocytes. We found that 45 metabolites were significantly changed between the VSD + HRS group and the VSD + saline-treated group. Pathway enrichment analysis indicated that biotin metabolism was the potential target pathway. The biochemical interpretation analysis demonstrated that combining HRS and VSD might enhance mitochondrial function, ATP synthesis, and GSH homeostasis by altering biotin metabolism. The detection of representative indicators of oxidative stress supported the critical metabolic pathway analysis as well. In summary, VSD combined with HRS might provide a new strategy to enhance wound healing.

Imperfect wound healing sets the stage for chronic diseases

Although the age of the genome gave us much insight about how our organs fail with disease, it also suggested that diseases do not arise from mutations alone; rather, they develop as we age. In this Review, we examine how wound healing might act to ignite disease. Wound healing works well when we are younger, repairing damage from accidents, environmental assaults, and battles with pathogens. Yet, with age and accumulation of mutations and tissue damage, the repair process can devolve, leading to inflammation, fibrosis, and neoplastic signaling. We discuss healthy wound responses and how our bodies might misappropriate these pathways in disease. Although we focus predominantly on epithelial-based (lung and skin) diseases, similar pathways might operate in cardiac, muscle, and neuronal diseases.

TREM2-mediated Macrophage Glycolysis Promotes Skin Wound Angiogenesis via the Akt/mTOR/HIF-1α Signaling Axis

OBJECTIVE

The trigger receptor expressed on myeloid cells-2 (TREM2) pathway in myeloid cells is a key disease-inducing immune signaling hub that is essential for detecting tissue damage and limiting its pathological spread. However, the role and potential mechanisms of TREM2 in wound repair remain unclear. The purpose of this study was to determine the role and mechanism of TREM2 in skin wound healing in mice.

METHODS

Immunofluorescence staining was used to determine the expression and cellular localization of TREM2 and test the effects of TREM2 knockout on angiogenesis, glycolysis, and lactylation in skin tissue. Western blotting was used to analyze the expression of the Akt/mTOR/HIF-1α signaling pathway in the wounded skin tissues of wild-type (WT) and TREM2 knockout mice. A coimmunoprecipitation assay was used to determine whether HIF-1α, which mediates angiogenesis, is modified by lactylation.

RESULTS

The number of TREM2+ macrophages was increased, and TREM2+ macrophages mediated angiogenesis after skin injury. TREM2 promoted glycolysis and lactylation in macrophages during wound healing. Mechanistically, TREM2 promoted macrophage glycolysis and angiogenesis in wounded skin tissues by activating the Akt/mTOR/HIF-1α signaling pathway. HIF-1α colocalized with Klac to mediate lactylation in macrophages, and lactate could stabilize the expression of the HIF-1α protein through lactylation. Lactate treatment ameliorated the impaired angiogenesis and delayed wound healing in wounded skin in TREM2 knockout mice.

CONCLUSION

TREM2+ macrophage-mediated glycolysis can promote angiogenesis and wound healing. Our findings provide an effective strategy and target for promoting skin wound healing.

Peripheral nerve-derived CSF1 induces BMP2 expression in macrophages to promote nerve regeneration and wound healing

The precise mechanisms regulating inflammatory and prorepair macrophages have not been fully elucidated, despite the pivotal role played by innate immunity in wound healing. We first employed a denervation wound model to validate the crosstalk between neurons and macrophages. Compared to normal wound healing, the denervation wound healing process involved fewer macrophages, decreased angiogenesis, and delayed wound healing. Consistent with the results of the scRNA-seq libraries, the number of early-phase wound proinflammatory and late-phase wound prorepair macrophages were decreased during the denervation wound healing process. We profiled early-phase and late-phase skin wounds in mice at the transcriptional and functional levels and compared them to those of normal wounds. We revealed a neuroimmune regulatory pathway driven by peripheral nerve-derived CSF1 that induces BMP2 expression in prorepair macrophages and enhances nerve regeneration. Crosstalk between neurons and macrophages facilitates the healing process of wounds and provides a potential strategy for wound healing therapy.

Cellular and molecular roles of reactive oxygen species in wound healing

Wound healing is a highly coordinated spatiotemporal sequence of events involving several cell types and tissues. The process of wound healing requires strict regulation, and its disruption can lead to the formation of chronic wounds, which can have a significant impact on an individual's health as well as on worldwide healthcare expenditure. One essential aspect within the cellular and molecular regulation of wound healing pathogenesis is that of reactive oxygen species (ROS) and oxidative stress. Wounding significantly elevates levels of ROS, and an array of various reactive species are involved in modulating the wound healing process, such as through antimicrobial activities and signal transduction. However, as in many pathologies, ROS play an antagonistic pleiotropic role in wound healing, and can be a pathogenic factor in the formation of chronic wounds. Whilst advances in targeting ROS and oxidative stress have led to the development of novel pre-clinical therapeutic methods, due to the complex nature of ROS in wound healing, gaps in knowledge remain concerning the specific cellular and molecular functions of ROS in wound healing. In this review, we highlight current knowledge of these functions, and discuss the potential future direction of new studies, and how these pathways may be targeted in future pre-clinical studies.

Single cell-spatial transcriptomics and bulk multi-omics analysis of heterogeneity and ecosystems in hepatocellular carcinoma

This study profiled global single cell-spatial-bulk transcriptome landscapes of hepatocellular carcinoma (HCC) ecosystem from six HCC cases and a non-carcinoma liver control donor. We discovered that intratumoral heterogeneity mainly derived from HCC cells diversity and pervaded the genome-transcriptome-proteome-metabolome network. HCC cells are the core driving force of taming tumor-associated macrophages (TAMs) with pro-tumorigenic phenotypes for favor its dominant growth. Remarkably, M1-types TAMs had been characterized by disturbance of metabolism, poor antigen-presentation and immune-killing abilities. Besides, we found simultaneous cirrhotic and HCC lesions in an individual patient shared common origin and displayed parallel clone evolution via driving disparate immune reprograms for better environmental adaptation. Moreover, endothelial cells exhibited phenotypically conserved but executed differential functions in a space-dependent manner. Further, the spatiotemporal traits of rapid recurrence niche genes were identified and validated by immunohistochemistry. Our data unravels the great significance of HCC cells in shaping vibrant tumor ecosystems corresponding to clinical scenarios.

Mitochondrial Bioenergetics of Functional Wound Closure is Dependent on Macrophage-Keratinocyte Exosomal Crosstalk

Tissue nanotransfection (TNT)-based fluorescent labeling of cell-specific exosomes has shown that exosomes play a central role in physiological keratinocyte-macrophage (mϕ) crosstalk at the wound-site. Here, we report that during the early phase of wound reepithelialization, macrophage-derived exosomes (Exomϕ), enriched with the outer mitochondrial membrane protein TOMM70, are localized in leading-edge keratinocytes. TOMM70 is a 70 kDa adaptor protein anchored in the mitochondrial outer membrane and plays a critical role in maintaining mitochondrial function and quality. TOMM70 selectively recognizes cytosolic chaperones by its tetratricopeptide repeat (TPR) domain and facilitates the import of preproteins lacking a positively charged mitochondrial targeted sequence. Exosomal packaging of TOMM70 in mϕ was independent of mitochondrial fission. TOMM70-enriched Exomϕ compensated for the hypoxia-induced depletion of epidermal TOMM70, thereby rescuing mitochondrial metabolism in leading-edge keratinocytes. Thus, macrophage-derived TOMM70 is responsible for the glycolytic ATP supply to power keratinocyte migration. Blockade of exosomal uptake from keratinocytes impaired wound closure with the persistence of proinflammatory mϕ in the wound microenvironment, pointing toward a bidirectional crosstalk between these two cell types. The significance of such bidirectional crosstalk was established by the observation that in patients with nonhealing diabetic foot ulcers, TOMM70 is deficient in keratinocytes of wound-edge tissues.

Multiomics reveals age-dependent metabolic reprogramming of macrophages by wound bed niche secreted signals

The cellular metabolism of macrophages depends on tissue niches and can control macrophage inflammatory or resolving phenotypes. Yet, the identity of signals within tissue niches that control macrophage metabolism is not well understood. Here, using single-cell RNA sequencing of macrophages in early mouse wounds, we find that, rather than gene expression of canonical inflammatory or resolving polarization markers, metabolic gene expression defines distinct populations of early wound macrophages. Single-cell secretomics and transcriptomics identify inflammatory and resolving cytokines expressed by early wound macrophages, and we show that these signals drive metabolic inputs and mitochondrial metabolism in an age-dependent manner. We show that aging alters the metabolome of early wound macrophages and rewires their metabolism from mitochondria to glycolysis. We further show that macrophage-derived Chi3l3 and IGF-1 can induce metabolic inputs and mitochondrial mass/metabolism in aged and bone marrow-derived macrophages. Together, these findings reveal that macrophage-derived signals drive the mitochondrial metabolism of macrophages within early wounds in an age-dependent manner and have implications for inflammatory diseases, chronic injuries, and age-related inflammatory diseases.

In Brief

This study reveals that macrophage subsets in early inflammatory stages of skin wound healing are defined by their metabolic profiles rather than polarization phenotype. Using single-cell secretomics, we establish key macrophage cytokines that comprise the in vivo wound niche and drive mitochondrial-based metabolism. Aging significantly alters macrophage heterogeneity and increases glycolytic metabolism, which can be restored to OxPHOS-based metabolism with young niche cytokines. These findings highlight the importance of the tissue niche in driving macrophage phenotypes, with implications for aging-related impairments in wound healing.

Highlights

Single cell transcriptional analysis reveals that reveals that metabolic gene expression identifies distinct macrophage populations in early skin wounds.Single-cell secretomic data show that young macrophages contribute to the wound bed niche by secreting molecules such as IGF-1 and Chi3l3.Old wound macrophages display altered metabolomics, elevated glycolytic metabolism and glucose uptake, and reduced lipid uptake and mitochondrial mass/metabolism.Chi3l3 but not IGF-1 secretion is altered in macrophages in an age dependent manner.Chi3l3 can restore mitochondrial mass/metabolism in aged macrophages.

Light-activated nanoclusters with tunable ROS for wound infection treatment

Infected wounds pose a significant clinical challenge due to bacterial resistance, recurrent infections, and impaired healing. Reactive oxygen species (ROS)-based strategies have shown promise in eradicating bacterial infections. However, the excess ROS in the infection site after treatments may cause irreversible damage to healthy tissues. To address this issue, we developed bovine serum albumin-iridium oxide nanoclusters (BSA-IrOx NCs) which enable photo-regulated ROS generation and scavenging using near infrared (NIR) laser. Upon NIR laser irradiation, BSA-IrOx NCs exhibit enhanced photodynamic therapy, destroying biofilms and killing bacteria. When the NIR laser is off, the nanoclusters' antioxidant enzyme-like activities prevent inflammation and repair damaged tissue through ROS clearance. Transcriptomic and metabolomic analyses revealed that BSA-IrOx NCs inhibit bacterial nitric oxide synthase, blocking bacterial growth and biofilm formation. Furthermore, the nanoclusters repair impaired skin by strengthening cell junctions and reducing mitochondrial damage in a fibroblast model. In vivo studies using rat infected wound models confirmed the efficacy of BSA-IrOx NCs. This study presents a promising strategy for treating biofilm-induced infected wounds by regulating the ROS microenvironment, addressing the challenges associated with current ROS-based antibacterial approaches.

Plant-inspired visible-light-driven bioenergetic hydrogels for chronic wound healing

Chronic bioenergetic imbalances and inflammation caused by hyperglycemia are obstacles that delay diabetic wound healing. However, it is difficult to directly deliver energy and metabolites to regulate intracellular energy metabolism using biomaterials. Herein, we propose a light-driven bioenergetic and oxygen-releasing hydrogel (PTKM@HG) that integrates the thylakoid membrane-encapsulated polyphenol nanoparticles (PTKM NPs) to regulate the energy metabolism and inflammatory response in diabetic wounds. Upon red light irradiation, the PTKM NPs exhibited oxygen generation and H2O2 deletion capacity through a photosynthetic effect to restore hypoxia-induced mitochondrial dysfunction. Meanwhile, the PTKM NPs could produce exogenous ATP and NADPH to enhance mitochondrial function and facilitate cellular anabolism by regulating the leucine-activated mTOR signaling pathway. Furthermore, the PTKM NPs inherited antioxidative and anti-inflammatory ability from polyphenol. Finally, the red light irradiated PTKM@HG hydrogel augmented the survival and migration of cells keratinocytes, and then accelerated angiogenesis and re-epithelialization of diabetic wounds. In short, this study provides possibilities for effectively treating diseases by delivering key metabolites and energy based on such a light-driven bioenergetic hydrogel.

A wearable and stretchable dual-wavelength LED device for home care of chronic infected wounds

Phototherapy can offer a safe and non-invasive solution against infections, while promoting wound healing. Conventional phototherapeutic devices are bulky and limited to hospital use. To overcome these challenges, we developed a wearable, flexible red and blue LED (r&bLED) patch controlled by a mobile-connected system, enabling safe self-application at home. The patch exhibits excellent skin compatibility, flexibility, and comfort, with high safety under system supervision. Additionally, we synthesized a sprayable fibrin gel (F-gel) containing blue light-sensitive thymoquinone and red light-synergistic NADH. Combined with bLED, thymoquinone eradicated microbes and biofilms within minutes, regardless of antibiotic resistance. Furthermore, NADH and rLED synergistically improved macrophage and endothelial cell mitochondrial function, promoting wound healing, reducing inflammation, and enhancing angiogenesis, as validated in infected diabetic wounds in mice and minipigs. This innovative technology holds great promise for revolutionizing at-home phototherapy for chronic infected wounds.

Microenvironment-responsive nanomedicines: a promising direction for tissue regeneration

Severe tissue defects present formidable challenges to human health, persisting as major contributors to mortality rates. The complex pathological microenvironment, particularly the disrupted immune landscape within these defects, poses substantial hurdles to existing tissue regeneration strategies. However, the emergence of nanobiotechnology has opened a new direction in immunomodulatory nanomedicine, providing encouraging prospects for tissue regeneration and restoration. This review aims to gather recent advances in immunomodulatory nanomedicine to foster tissue regeneration. We begin by elucidating the distinctive features of the local immune microenvironment within defective tissues and its crucial role in tissue regeneration. Subsequently, we explore the design and functional properties of immunomodulatory nanosystems. Finally, we address the challenges and prospects of clinical translation in nanomedicine development, aiming to propose a potent approach to enhance tissue regeneration through synergistic immune modulation and nanomedicine integration.

SFRP2 modulates functional phenotype transition and energy metabolism of macrophages during diabetic wound healing

Diabetic foot ulcer (DFU) is a serious complication of diabetes mellitus, which causes great health damage and economic burden to patients. The pathogenesis of DFU is not fully understood. We screened wound healing-related genes using bioinformatics analysis, and full-thickness skin injury mice model and cellular assays were used to explore the role of target genes in diabetic wound healing. SFRP2 was identified as a wound healing-related gene, and the expression of SFRP2 is associated with immune cell infiltration in DFU. In vivo study showed that suppression of SFRP2 delayed the wound healing process of diabetic mice, impeded angiogenesis and matrix remodeling, but did not affect wound healing process of control mice. In addition, suppression of SFRP2 increased macrophage infiltration and impeded the transition of macrophages functional phenotypes during diabetic wound healing, and affected the transcriptome signatures-related to inflammatory response and energy metabolism at the early stage of wound healing. Extracellular flux analysis (EFA) showed that suppression of SFRP2 decreased mitochondrial energy metabolism and increased glycolysis in injury-related macrophages, but impeded both glycolysis and mitochondrial energy metabolism in inflammatory macrophages. In addition, suppression of SFRP2 inhibited wnt signaling-related genes in macrophages. Treatment of AAV-SFRP2 augmented wound healing in diabetic mice and demonstrated the therapeutic potential of SFRP2. In conclusions, SFRP2 may function as a wound healing-related gene in DFU by modulating functional phenotype transition of macrophages and the balance between mitochondrial energy metabolism and glycolysis.

Hydrogel Microneedle Patches Loaded with Stem Cell Mitochondria-Enriched Microvesicles Boost the Chronic Wound Healing

Rescuing or compensating mitochondrial function represents a promising therapeutic avenue for radiation-induced chronic wounds. Adult stem cell efficacies are primarily dependent on the paracrine secretion of mitochondria-containing extracellular vesicles (EVs). However, effective therapeutic strategies addressing the quantity of mitochondria and mitochondria-delivery system are lacking. Thus, in this study, we aimed to design an effective hydrogel microneedle patch (MNP) loaded with stem cell-derived mitochondria-rich EVs to gradually release and deliver mitochondria into the wound tissues and boost wound healing. We, first, used metformin to enhance mitochondrial biogenesis and thereby increasing the secretion of mitochondria-containing EVs (termed "Met-EVs") in adipose-derived stem cells. To verify the therapeutic effects of Met-EVs, we established an in vitro and an in vivo model of X-ray-induced mitochondrial dysfunction. The Met-EVs ameliorated the mitochondrial dysfunction by rescuing mitochondrial membrane potential, increasing adenosine 5'-triphosphate levels, and decreasing reactive oxygen species production by transferring active mitochondria. To sustain the release of EVs into damaged tissues, we constructed a Met-EVs@Decellularized Adipose Matrix (DAM)/Hyaluronic Acid Methacrylic Acid (HAMA)-MNP. Met-EVs@DAM/HAMA-MNP can load and gradually release Met-EVs and their contained mitochondria into wound tissues to alleviate mitochondrial dysfunction. Moreover, we found Met-EVs@DAM/HAMA-MNP can markedly promote macrophage polarization toward the M2 subtype with anti-inflammatory and regenerative functions, which can, in turn, enhance the healing process in mice with skin wounds combined radiation injuries. Collectively, we successfully fabricated a delivery system for EVs, Met-EVs@DAM/HAMA-MNP, to effectively deliver stem cell-derived mitochondria-rich EVs. The effectiveness of this system has been demonstrated, holding great potential for chronic wound treatments in clinic.

Self-crosslinking hyaluronic acid-based hydrogel with promoting vascularization and ROS scavenging for wound healing

Skin wound dressings are commonly utilized for the treatment of skin injuries, as they effectively facilitate wound healing and possess anti-inflammatory and antibacterial properties. However, conventional dressings fail to inhibit ROS production and promote vascularization, leading to delayed wound healing. Here, we developed injectable self-crosslinking hydrogels through thiolated hyaluronic acid (HASH/rhCOLIII) with enhancing the ROS inhibitory capacity while preserving the cell adhesion ability of hyaluronic acid. Additionally, recombinant humanized collagen type III (rhCOLIII) is incorporated via electrostatic adsorption to further enhance mechanical strength and angiogenesis properties of the hydrogel. The HASH/rhCOLIII demonstrated excellent biocompatibility, remarkable ROS scavenging ability, as well as hemostatic and angiogenic properties. Cell experiment results show that HASH/rhCOLIII has excellent biocompatibility and can significantly promote angiogenesis. Animal experiments results showed that HASH/rhCOLIII exhibits anti-inflammatory effects, significantly accelerating wound healing in a full-thickness skin defect model. These findings highlight that HASH/rhCOLIII hydrogel holds great promise as an advanced dressing for effective wound healing.

Sphingosine Kinase 1 Aggravates Liver Fibrosis by Mediating Macrophage Recruitment and Polarization

BACKGROUND & AIMS

Sphingosine kinase 1 (SphK1) has distinct roles in the activation of Kupffer cells and hepatic stellate cells in liver fibrosis. Here, we aim to investigate the roles of SphK1 on hepatic macrophage recruitment and polarization in liver fibrosis.

METHODS

Liver fibrosis was induced by carbon tetrachloride in wild-type and SphK1-/- mice to study the recruitment and polarization of macrophages. The effects of SphK1 originated from macrophages or other liver cell types on liver fibrosis were further strengthened by bone marrow transplantation. The direct effects of SphK1 on macrophage polarization were also investigated in vitro. Expression analysis of SphK1 and macrophage polarization index was conducted with human liver samples.

RESULTS

SphK1 deletion attenuated the recruitment of hepatic macrophages along with reduced M1 and M2 polarization in mice induced by carbon tetrachloride. SphK1 deficiency in endogenous liver cells attenuated macrophage recruitment via C-C motif chemokine ligand 2. Macrophage SphK1 activated the ASK1-JNK1/2-p38 signaling pathway to promote M1 polarization. Furthermore, macrophage SphK1 downregulated small ubiquitin-like modifier-specific peptidase1 to decrease de-SUMOylation of Kruppel-like factor 4 to promote M2 polarization. Finally, we confirmed that SphK1 expression was elevated and positively correlated with macrophage M1 and M2 polarization in human fibrosis livers.

CONCLUSIONS

Our findings demonstrated that SphK1 aggravated liver fibrosis by promoting macrophage recruitment and M1/M2 polarization. SphK1 in macrophages is a potential therapeutic target for the treatment of liver fibrosis.

A study of scarless wound healing through programmed inflammation, proliferation and maturation using a redox balancing nanogel

In the study, we have shown the efficacy of an indigenously developed redox balancing chitosan gel with impregnated citrate capped Mn3O4 nanoparticles (nanogel). Application of the nanogel on a wound of preclinical mice model shows role of various signaling molecules and growth factors, and involvement of reactive oxygen species (ROS) at every stage, namely hemostasis, inflammation, and proliferation leading to complete maturation for the scarless wound healing. While in vitro characterization of nanogel using SEM, EDAX, and optical spectroscopy reveals pH regulated redox buffering capacity, in vivo preclinical studies on Swiss albino involving IL-12, IFN-γ, and α-SMA signaling molecules and detailed histopathological investigation and angiogenesis on every stage elucidate role of redox buffering for the complete wound healing process.

Cdc42 deletion yielded enamel defects by disrupting mitochondria and producing reactive oxygen species in dental epithelium

Developmental defects of enamel are common due to genetic and environmental factors before and after birth. Cdc42, a Rho family small GTPase, regulates prenatal tooth development in mice. However, its role in postnatal tooth development, especially enamel formation, remains elusive. Here, we investigated Cdc42 functions in mouse enamel development and tooth repair after birth. Cdc42 showed highly dynamic temporospatial patterns in the developing incisors, with robust expression in ameloblast and odontoblast layers. Strikingly, epithelium-specific Cdc42 deletion resulted in enamel defects in incisors. Ameloblast differentiation was inhibited, and hypomineralization of enamel was observed upon epithelial Cdc42 deletion. Proteomic analysis showed that abnormal mitochondrial components, phosphotransferase activity, and ion channel regulator activity occurred in the Cdc42 mutant dental epithelium. Reactive oxygen species accumulation was detected in the mutant mice, suggesting that abnormal oxidative stress occurred after Cdc42 depletion. Moreover, Cdc42 mutant mice showed delayed tooth repair and generated less calcified enamel. Mitochondrial dysfunction and abnormal oxygen consumption were evidenced by reduced Apool and Timm8a1 expression, increased Atp5j2 levels, and reactive oxygen species overproduction in the mutant repair epithelium. Epithelium-specific Cdc42 deletion attenuated ERK1/2 signaling in the labial cervical loop. Aberrant Sox2 expression in the mutant labial cervical loop after clipping might lead to delayed tooth repair. These findings suggested that mitochondrial dysfunction, up-regulated oxidative stress, and abnormal ion channel activity may be among multiple factors responsible for the observed enamel defects in Cdc42 mutant incisors. Overall, Cdc42 exerts multidimensional and pivotal roles in enamel development and is particularly required for ameloblast differentiation and enamel matrix formation.

Metabolism and bioenergetics in the pathophysiology of organ fibrosis

Fibrosis is the tissue scarring characterized by excess deposition of extracellular matrix (ECM) proteins, mainly collagens. A fibrotic response can take place in any tissue of the body and is the result of an imbalanced reaction to inflammation and wound healing. Metabolism has emerged as a major driver of fibrotic diseases. While glycolytic shifts appear to be a key metabolic switch in activated stromal ECM-producing cells, several other cell types such as immune cells, whose functions are intricately connected to their metabolic characteristics, form a complex network of pro-fibrotic cellular crosstalk. This review purports to clarify shared and particular cellular responses and mechanisms across organs and etiologies. We discuss the impact of the cell-type specific metabolic reprogramming in fibrotic diseases in both experimental and human pathology settings, providing a rationale for new therapeutic interventions based on metabolism-targeted antifibrotic agents.

Bone Marrow Mesenchymal Stem Cells-Derived Extracellular Vesicle miR-208a-3p Alleviating Spinal Cord Injury via Regulating the Biological Function of Spinal Cord Neurons

We aim to explore the potential mechanism of bone marrow mesenchymal stem cells-derived extracellular vesicles (BMSCs-Exo) in improving spinal cord injury (SCI). Thirty male 12-week specific pathogen-free (SPF) Sprague-Dawley (SD) rats were used to construct SCI model in vivo. Ten male 12-week SPF SD rats were used to extract BMSCs. The Basso, Beattie, Bresnahan (BBB) score was used to evaluate the motor function of rats. Real-time fluorescence quantitative PCR (RT-PCR), western blot (WB), and double luciferase assay were used to explore the regulation between rno-miR-208a-3p and Cdkn1a (p21) in BMSCs. Primary spinal cord neurons were treated with lipopolysaccharide (100 ng/mL) for 30 min to mimic SCI in vitro. Compared with the model group (14 scores), BMSCs-Exo increased BBB score (19 scores) in SCI rats. Compared with the sham group, Cdkn1a was upregulated, whereas rno-miR-208a-3p was downregulated in the model group. However, compared with the model group, Cdkn1a was downregulated, whereas rno-miR-208a-3p was upregulated in the BMSCs-Exo group. In addition, rno-miR-208a-3p inhibited the expression of Cdkn1a via direct binding way. BMSCs-Exo-rno-miR-208a-3p promoted the proliferation of primary spinal neurons via inhibiting apoptosis in vitro. Moreover, BMSCs-Exo-rno-miR-208a-3p promoted cyclin D1, CDK6, and Bcl-2 and inhibited Bax expression in a cell model of SCI. In conclusion, BMSCs-Exo-carried rno-miR-208a-3p significantly protects rats from SCI via regulating the Cdkn1a pathway.