Macrophages play a key role in tissue repair and regeneration

Shaping the immune landscape: Multidimensional environmental stimuli refine macrophage polarization and foster revolutionary approaches in tissue regeneration

In immunology, the role of macrophages extends far beyond their traditional classification as mere phagocytes; they emerge as pivotal architects of the immune response, with their function being significantly influenced by multidimensional environmental stimuli. This review investigates the nuanced mechanisms by which diverse external signals ranging from chemical cues to physical stress orchestrate macrophage polarization, a process that is crucial for the modulation of immune responses. By transitioning between pro-inflammatory (M1) and anti-inflammatory (M2) states, macrophages exhibit remarkable plasticity, enabling them to adapt to and influence their surroundings effectively. The exploration of macrophage polarization provides a compelling narrative on how these cells can be manipulated to foster an immune environment conducive to tissue repair and regeneration. Highlighting cutting-edge research, this review presents innovative strategies that leverage the dynamic interplay between macrophages and their environment, proposing novel therapeutic avenues that harness the potential of macrophages in regenerative medicine. Moreover, this review critically evaluates the current challenges and future prospects of translating macrophage-centered strategies from the laboratory to clinical applications.

Targeted Macrophage Re-Programming: Synergistic Therapy With Methotrexate and RELA siRNA Folate-Liposome in RAW264.7 Cells and Arthritic Rats

Rheumatoid arthritis (RA) is a chronic autoimmune disorder characterized by joint inflammation and destruction. Current treatments, such as Methotrexate (MTX), though effective, often face limitations such as high plasma Cmax and lack of sustained release. This study explores a synergistic approach to RA therapy using folate-liposomal co-delivery of MTX and RELA siRNA (short interfering RNA), targeting RAW264.7 macrophage repolarization via nuclear factor kappa B (NF-κB) pathway inhibition. Extensive in vitro characterizations demonstrate the stability and biocompatibility of this therapy via folate-liposomes. In the collagen-induced arthritis (CIA) rat model, treatment leads to reduced synovial inflammation and improved mobility. The combined MTX and RELA siRNA approach indirectly inhibits inflammatory cytokines, rheumatoid factor (RF), and C-reactive protein (CRP). Targeted macrophage delivery shows marked therapeutic effects in RAW264.7 murine macrophages, potentially modulating M1 to M2 polarization. This research presents a promising avenue for innovative RA therapies by inhibiting the inflammatory cascade and preventing joint damage.

Macrophages and Gut Barrier Function: Guardians of Gastrointestinal Health in Post-Inflammatory and Post-Infection Responses

The gut barrier is essential for protection against pathogens and maintaining homeostasis. Macrophages are key players in the immune system, are indispensable for intestinal health, and contribute to immune defense and repair mechanisms. Understanding the multifaceted roles of macrophages can provide critical insights into maintaining and restoring gastrointestinal (GI) health. This review explores the essential role of macrophages in maintaining the gut barrier function and their contribution to post-inflammatory and post-infectious responses in the gut. Macrophages significantly contribute to gut barrier integrity through epithelial repair, immune modulation, and interactions with gut microbiota. They demonstrate active plasticity by switching phenotypes to resolve inflammation, facilitate tissue repair, and regulate microbial populations following an infection or inflammation. In addition, tissue-resident (M2) and infiltration (M1) macrophages convert to each other in gut problems such as IBS and IBD via major signaling pathways mediated by NF-κB, JAK/STAT, PI3K/AKT, MAPK, Toll-like receptors, and specific microRNAs such as miR-155, miR-29, miR-146a, and miR-199, which may be good targets for new therapeutic approaches. Future research should focus on elucidating the detailed molecular mechanisms and developing personalized therapeutic approaches to fully harness the potential of macrophages to maintain and restore intestinal permeability and gut health.

LLLT accelerates experimental wound healing under microgravity conditions via PI3K/AKT-CCR2 signal axis

Background and Purpose

The risk of skin injuries in space is increasing with longer space missions and a growing astronaut population. This highlights the importance of understanding the adverse effects of weightlessness on wound healing. The objective of this research was to examine the therapeutic potential of Low-Level Light Therapy (LLLT) on skin healing processes under simulated microgravity (SMG) conditions and uncover the underlying molecular mechanisms, thus providing innovative solutions and a sound theoretical basis for space skin injuries.

Methods

Hindlimb unloading (HU) mice models were used to simulate weightlessness conditions, with or without a complete management of LLLT for 14 days. A systematic testing consisting of HE, Masson and immunohistochemical staining was performed against the standardized mouse tissue specimens. In vitro assessment of cellular biological functions under SMG conditions was carried out in the rotation system of culture (RSOC) using HaCaT and NIH3T3 cell-lines.

Results

Under SMG conditions, LLLT significantly reduced skin wound area in HU mice, especially on Days 10 (p < 0.001), accompanied by increased collagen deposition and elevated levels of Ki67 and CD31. Moreover, LLLT showed impressive anti-inflammatory effects represented by the reduced in pro-inflammatory markers including LY6G, F4/80 and CD86, as well as the decreased levels of IL-1β, IL-6 and TNF-α. Conversely, an elevation in the anti-inflammatory marker CD206 was observed. By employing bioinformatics technology, we further found the PI3K/AKT signaling was prominent in the KEGG pathway analysis and CCR2 acted as a hub gene in the interaction network. Therefore, we demonstrated that LLLT could enhance the phosphorylation of PI3K/AKT and reduce CCR2 expression under SMG conditions, while CCR2 knockdown promoted the phosphorylation of PI3K/AKT, suggesting an important role of CCR2/PI3K/AKT signal axis in LLLT-accelerated wound healing under SMG conditions.

Conclusion

LLLT induced activation of the PI3K/AKT signaling pathway through suppression of CCR2 expression, which significantly enhanced skin wound healing under SMG conditions.s.

Vascular mimicry in zebrafish fin regeneration: how macrophages build new blood vessels

Vascular mimicry has been thoroughly investigated in tumor angiogenesis. In this study, we demonstrate for the first time that a process closely resembling tumor vascular mimicry is present during physiological blood vessel formation in tissue regeneration using the zebrafish fin regeneration assay. At the fin-regenerating front, vasculature is formed by mosaic blood vessels with endothelial-like cells possessing the morphological phenotype of a macrophage and co-expressing both endothelial and macrophage markers within single cells. Our data demonstrate that the vascular segments of the regenerating tissue expand, in part, through the transformation of adjacent macrophages into endothelial-like cells, forming functional, perfused channels and contributing to the de novo formation of microvasculature. Inhibiting the formation of tubular vascular-like structures by CVM-1118 prevents vascular mimicry and network formation resulting in a 70% shorter regeneration area with 60% reduced vessel growth and a complete absence of any signs of regeneration in half of the fin area. Additionally, this is associated with a significant reduction in macrophages. Furthermore, depleting macrophages using macrophage inhibitor PLX-3397, results in impaired tissue regeneration and blood vessel formation, namely a reduction in the regeneration area and vessel network by 75% in comparison to controls.

Assessment of inflammatory suppression and fibroblast infiltration in tissue remodelling by supercritical CO2 acellular dermal matrix (scADM) utilizing Sprague Dawley models

Human skin-derived ECM aids cell functions but can trigger immune reactions; therefore it is addressed through decellularization. Acellular dermal matrices (ADMs), known for their regenerative properties, are used in tissue and organ regeneration. ADMs now play a key role in plastic and reconstructive surgery, enhancing aesthetics and reducing capsular contracture risk. Innovative decellularization with supercritical carbon dioxide preserves ECM quality for clinical use. The study investigated the cytotoxicity, biocompatibility, and anti-inflammatory properties of supercritical CO2 acellular dermal matrix (scADM) in vivo based on Sprague Dawley rat models. Initial experiments in vitro with fibroblast cells confirmed the non-toxic nature of scADM and demonstrated cell infiltration into scADMs after incubation. Subsequent tests in vitro revealed the ability of scADM to suppress inflammation induced by lipopolysaccharides (LPS) presenting by the reduction of pro-inflammatory cytokines TNF-α, IL-6, IL-1β, and MCP-1. In the in vivo model, histological assessment of implanted scADMs in 6 months revealed a decrease in inflammatory cells, confirmed further by the biomarkers of inflammation in immunofluorescence staining. Besides, an increase in fibroblast infiltration and collagen formation was observed in histological staining, which was supported by various biomarkers of fibroblasts. Moreover, the study demonstrated vascularization and macrophage polarization, depicting increased endothelial cell formation. Alteration of matrix metalloproteinases (MMPs) was analyzed by RT-PCR, indicating the reduction of MMP2, MMP3, and MMP9 levels over time. Simultaneously, an increase in collagen deposition of collagen I and collagen III was observed, verified in immunofluorescent staining, RT-PCR, and western blotting. Overall, the findings suggested that scADMs offer significant benefits in improving outcomes in implant-based procedures as well as soft tissue substitution.

Macrophages modulate fibrosis during newt lens regeneration

BACKGROUND

Previous studies have suggested that macrophages are present during lens regeneration in newts, but their role in the process is yet to be elucidated.

METHODS

Here we generated a transgenic reporter line using the newt, Pleurodeles waltl, that traces macrophages during lens regeneration. Furthermore, we assessed early changes in gene expression during lens regeneration using two newt species, Notophthalmus viridescens and Pleurodeles waltl. Finally, we used clodronate liposomes to deplete macrophages during lens regeneration in both species and tested the effect of a subsequent secondary injury after macrophage recovery.

RESULTS

Macrophage depletion abrogated lens regeneration, induced the formation of scar-like tissue, led to inflammation, decreased iris pigment epithelial cell (iPEC) proliferation, and increased rates of apoptosis in the eye. Some of these phenotypes persisted throughout the last observation period of 100 days and could be attenuated by exogenous FGF2 administration. A distinct transcript profile encoding acute inflammatory effectors was established for the dorsal iris. Reinjury of the newt eye alleviated the effects of macrophage depletion, including the resolution of scar-like tissue, and re-initiated the regeneration process.

CONCLUSIONS

Together, our findings highlight the importance of macrophages for facilitating a pro-regenerative environment in the newt eye by regulating fibrotic responses, modulating the overall inflammatory landscape, and maintaining the proper balance of early proliferation and late apoptosis of the iPECs.

HEBE project: Healthy aging versus inflamm-aging: The role of physical exercise in modulating the biomarkers of age-associated and environmentally determined chronic diseases, study protocol

Inflamm-aging refers to the chronic low-grade inflammation that occurs with aging and cellular senescence, and it is linked to various diseases. Understanding the markers involved in inflammation and aging, as well as their interaction with environmental factors and bodily control mechanisms, can provide crucial tools for assessing the resilience (i.e. the ability to adapt and improve) of the human body, particularly in the presence of chronic degenerative conditions or vulnerable life stages, that place the individual and the community to which he belongs in a state of potential fragility. HEBE focuses on physical exercise, along with nutritional and lifestyle recommendations, to reduce systemic inflammation and promote healthy aging. HEBE encompasses multiple research lines (LR). In the ongoing LR1 ("proof of concept"), healthy lifestyle recommendations were provided to University of Milan employees, and changes in quality of life and well-being were assessed using a specialized questionnaire. The first 100 eligible subjects, who expressed their willingness to participate, underwent a personalized physical exercise protocol based on clinical and objective assessments. Biomedical samples were collected at baseline (T0) and follow-up (T1) to establish a shared biobank and identify non-invasive biomarkers that monitor the impact of physical exercise on individual characteristics such as cardiovascular and metabolic health. Subsequently (LR2-LR10), the proof of concept findings will be expanded to include various conditions of vulnerability such as obesity, cancer, endocrine disorders, cardiovascular diseases, infertility, functional syndromes, respiratory disorders, neurodegenerative diseases, and autoimmune conditions. The research lines will leverage the expertise of the 94 participating investigators to form a collaborative network that maximizes the potential for investigation and knowledge exchange. This approach fosters a culture of health promotion and disease prevention. ClinicalTrials.gov Identifier: NCT05815732.

The guardians of pulmonary harmony: alveolar macrophages orchestrating the symphony of lung inflammation and tissue homeostasis

Recent breakthroughs in single-cell sequencing, advancements in cellular and tissue imaging techniques, innovations in cell lineage tracing, and insights into the epigenome collectively illuminate the enigmatic landscape of alveolar macrophages in the lung under homeostasis and disease conditions. Our current knowledge reveals the cellular and functional diversity of alveolar macrophages within the respiratory system, emphasising their remarkable adaptability. By synthesising insights from classical cell and developmental biology studies, we provide a comprehensive perspective on alveolar macrophage functional plasticity. This includes an examination of their ontology-related features, their role in maintaining tissue homeostasis under steady-state conditions and the distinct contribution of bone marrow-derived macrophages (BMDMs) in promoting tissue regeneration and restoring respiratory system homeostasis in response to injuries. Elucidating the signalling pathways within inflammatory conditions, the impact of various triggers on tissue-resident alveolar macrophages (TR-AMs), as well as the recruitment and polarisation of macrophages originating from the bone marrow, presents an opportunity to propose innovative therapeutic approaches aimed at modulating the equilibrium between phenotypes to induce programmes associated with a pro-regenerative or homeostasis phenotype of BMDMs or TR-AMs. This, in turn, can lead to the amelioration of disease outcomes and the attenuation of detrimental inflammation. This review comprehensively addresses the pivotal role of macrophages in the orchestration of inflammation and resolution phases after lung injury, as well as ageing-related shifts and the influence of clonal haematopoiesis of indeterminate potential mutations on alveolar macrophages, exploring altered signalling pathways and transcriptional profiles, with implications for respiratory homeostasis.

Intestinal macrophages in pathogenesis and treatment of gut leakage: current strategies and future perspectives

Macrophages play key roles in tissue homeostasis, defense, disease, and repair. Macrophages are highly plastic and exhibit distinct functional phenotypes based on micro-environmental stimuli. In spite of several advancements in understanding macrophage biology and their different functional phenotypes in various physiological and pathological conditions, currently available treatment strategies targeting macrophages are limited. Macrophages' high plasticity and diverse functional roles-including tissue injury and wound healing mechanisms-mark them as potential targets to mine for efficient therapeutics to treat diseases. Despite mounting evidence on association of gut leakage with several extraintestinal diseases, there is no targeted standard therapy to treat gut leakage. Therefore, there is an urgent need to develop therapeutic strategies to treat this condition. Macrophages are the cells that play the largest role in interacting with the gut microbiota in the intestinal compartment and exert their intended functions in injury and repair mechanisms. In this review, we have summarized the current knowledge on the origins and phenotypes of macrophages. The specific role of macrophages in intestinal barrier function, their role in tissue repair mechanisms, and their association with gut microbiota are discussed. In addition, currently available therapies and the putative tissue repair mediators of macrophages for treating microbiota dysbiosis induced gut leakage are also discussed. The overall aim of this review is to convey the intense need to screen for microbiota induced macrophage-released prorepair mediators, which could lead to the identification of potential candidates that could be developed for treating the leaky gut and associated diseases.

3D Printing of Alginate/Chitosan-Based Scaffold Empowered by Tyrosol-Loaded Niosome for Wound Healing Applications: In Vitro and In Vivo Performances

This study introduces a tyrosol-loaded niosome integrated into a chitosan-alginate scaffold (Nio-Tyro@CS-AL), employing advanced electrospinning and 3D printing techniques for wound healing applications. The niosomes, measuring 185.40 ± 6.40 nm with a polydispersity index of 0.168 ± 0.012, encapsulated tyrosol with an efficiency of 77.54 ± 1.25%. The scaffold's microsized porous structure (600-900 μm) enhances water absorption, promoting cell adhesion, migration, and proliferation. Mechanical property assessments revealed the scaffold's enhanced resilience, with niosomes increasing the compressive strength, modulus, and strain to failure, indicative of its suitability for wound healing. Controlled tyrosol release was demonstrated in vitro, essential for therapeutic efficacy. The scaffold exhibited significant antibacterial activity against Pseudomonas aeruginosa and Staphylococcus aureus, with substantial biofilm inhibition and downregulation of bacterial genes (ndvb and icab). A wound healing assay highlighted a notable increase in MMP-2 and MMP-9 mRNA expression and the wound closure area (69.35 ± 2.21%) in HFF cells treated with Nio-Tyro@CS-AL. In vivo studies in mice confirmed the scaffold's biocompatibility, showing no significant inflammatory response, hypertrophic scarring, or foreign body reaction. Histological evaluations revealed increased fibroblast and macrophage activity, enhanced re-epithelialization, and angiogenesis in wounds treated with Nio-Tyro@CS-AL, indicating effective tissue integration and repair. Overall, the Nio-Tyro@CS-AL scaffold presents a significant advancement in wound-healing materials, combining antibacterial properties with enhanced tissue regeneration, and holds promising potential for clinical applications in wound management.

Hepatic Transcriptome and Its Regulation Following Soluble Epoxide Hydrolase Inhibition in Alcohol-Associated Liver Disease

Alcohol-associated liver disease (ALD) is a serious public health problem with limited pharmacologic options. The goal of the current study was to investigate the efficacy of pharmacologic inhibition of soluble epoxide hydrolase (sEH), an enzyme involved in lipid metabolism, in experimental ALD, and to examine the underlying mechanisms. C57BL/6J male mice were subjected to acute-on-chronic ethanol (EtOH) feeding with or without the sEH inhibitor 4-[[trans-4-[[[[4-trifluoromethoxy phenyl]amino]carbonyl]-amino]cyclohexyl]oxy]-benzoic acid (TUCB). Liver injury was assessed by multiple end points. Liver epoxy fatty acids and dihydroxy fatty acids were measured by targeted metabolomics. Whole-liver RNA sequencing was performed, and free modified RNA bases were measured by mass spectrometry. EtOH-induced liver injury was ameliorated by TUCB treatment as evidenced by reduced plasma alanine aminotransferase levels and was associated with attenuated alcohol-induced endoplasmic reticulum stress, reduced neutrophil infiltration, and increased numbers of hepatic M2 macrophages. TUCB altered liver epoxy and dihydroxy fatty acids and led to a unique hepatic transcriptional profile characterized by decreased expression of genes involved in apoptosis, inflammation, fibrosis, and carcinogenesis. Several modified RNA bases were robustly changed by TUCB, including N6-methyladenosine and 2-methylthio-N6-threonylcarbamoyladenosine. These findings show the beneficial effects of sEH inhibition by TUCB in experimental EtOH-induced liver injury, warranting further mechanistic studies to explore the underlying mechanisms, and highlighting the translational potential of sEH as a drug target for this disease.

Medrysone promotes corneal injury repair by promoting M2-like polarization of macrophages

BACKGROUND

Accumulated evidence suggests that M2-like polarized macrophages plays an important role in reducing inflammation, promoting and accelerating wound healing process and tissue repair. Thus, M2-like TAMs (Tumour-associated macrophages) was an appealing target for therapy intervention.

METHOD

Flow cytometry and RT-PCR assay were used to detect the polarization of macrophages induced by Medrysone, and the rat corneal mechanical injury model was established to evaluate the efficacy of Medrysone in cornel repair.

RESULTS

Here we found that Medrysone enhanced IL-4 induced M2 polarization of macrophages, as illustrated by increased expression of CD206, up-regulation of M2 marker mRNAs. Medrysone promoted VEGF and CCL2 secretion in IL-4 induced M2-like polarization. IL-4 triggered STAT6 activation was further enhanced by Medrysone and silencing of STAT6 partially abrogated the stimulatory effect of Medrysone. Medrysone improved migration-promoting feature of M2-like macrophages, as indicated by increased migration of endothelial cells. Further, Medrysone promoted corneal injury repair by inducing M2 polarization of macrophages in vivo.

CONCLUSION

Our study suggest that Medrysone promotes corneal injury repair by inducing the M2 polarization of macrophages, providing a theoretical basis for the application of Medrysone in the treatment of corneal injury.

Macrophage polarization in tissue fibrosis

Fibrosis can occur in all major organs with relentless progress, ultimately leading to organ failure and potentially death. Unfortunately, current clinical treatments cannot prevent or reverse tissue fibrosis. Thus, new and effective antifibrotic therapeutics are urgently needed. In recent years, a growing body of research shows that macrophages are involved in fibrosis. Macrophages are highly heterogeneous, polarizing into different phenotypes. Some studies have found that regulating macrophage polarization can inhibit the development of inflammation and cancer. However, the exact mechanism of macrophage polarization in different tissue fibrosis has not been fully elucidated. This review will discuss the major signaling pathways relevant to macrophage-driven fibrosis and profibrotic macrophage polarization, the role of macrophage polarization in fibrosis of lung, kidney, liver, skin, and heart, potential therapeutics targets, and investigational drugs currently in development, and hopefully, provide a useful review for the future treatment of fibrosis.

Development and Prospective Applications of 3D Membranes as a Sensor for Monitoring and Inducing Tissue Regeneration

For decades, tissue regeneration has been a challenging issue in scientific modeling and human practices. Although many conventional therapies are already used to treat burns, muscle injuries, bone defects, and hair follicle injuries, there remains an urgent need for better healing effects in skin, bone, and other unique tissues. Recent advances in three-dimensional (3D) printing and real-time monitoring technologies have enabled the creation of tissue-like membranes and the provision of an appropriate microenvironment. Using tissue engineering methods incorporating 3D printing technologies and biomaterials for the extracellular matrix (ECM) containing scaffolds can be used to construct a precisely distributed artificial membrane. Moreover, advances in smart sensors have facilitated the development of tissue regeneration. Various smart sensors may monitor the recovery of the wound process in different aspects, and some may spontaneously give feedback to the wound sites by releasing biological factors. The combination of the detection of smart sensors and individualized membrane design in the healing process shows enormous potential for wound dressings. Here, we provide an overview of the advantages of 3D printing and conventional therapies in tissue engineering. We also shed light on different types of 3D printing technology, biomaterials, and sensors to describe effective methods for use in skin and other tissue regeneration, highlighting their strengths and limitations. Finally, we highlight the value of 3D bioengineered membranes in various fields, including the modeling of disease, organ-on-a-chip, and drug development.

Inflammasome Coordinates Senescent Chronic Wound Induced by Thalassophryne nattereri Venom

Thalassophryne nattereri toadfish (niquim) envenomation, common in the hands and feet of bathers and fishermen in the north and northeast regions of Brazil, is characterized by local symptoms such as immediate edema and intense pain. These symptoms progress to necrosis that lasts for an extended period of time, with delayed healing. Wound healing is a complex process characterized by the interdependent role of keratinocytes, fibroblasts, and endothelial and innate cells such as neutrophils and macrophages. Macrophages and neutrophils are actively recruited to clear debris during the inflammatory phase of wound repair, promoting the production of pro-inflammatory mediators, and in the late stage, macrophages promote tissue repair. Our hypothesis is that injury caused by T. nattereri venom (VTn) leads to senescent wounds. In this study, we provide valuable information about the mechanism(s) behind the dysregulated inflammation in wound healing induced by VTn. We demonstrate in mouse paws injected with the venom the installation of γH2AX/p16^Ink4a-dependent senescence with persistent neutrophilic inflammation in the proliferation and remodeling phases. VTn induced an imbalance of M1/M2 macrophages by maintaining a high number of TNF-α-producing M1 macrophages in the wound but without the ability to eliminate the persistent neutrophils. Chronic neutrophilic inflammation and senescence were mediated by cytokines such as IL-1α and IL-1β in a caspase-1- and caspase-11-dependent manner. In addition, previous blocking with anti-IL-1α and anti-IL-β neutralizing antibodies and caspase-1 (Ac YVAD-CMK) and caspase-11 (Wedelolactone) inhibitors was essential to control the pro-inflammatory activity of M1 macrophages induced by VTn injection, skewing towards an anti-inflammatory state, and was sufficient to block neutrophil recruitment and senescence.

Macrophage–Neuroglia Interactions in Promoting Neuronal Regeneration in Zebrafish

The human nervous system exhibits limited regenerative capabilities following damage to the central nervous system (CNS), leading to a scarcity of effective treatments for nerve function recovery. In contrast, zebrafish demonstrate remarkable regenerative abilities, making them an ideal model for studying the modulation of inflammatory processes after injury. Such research holds significant translational potential to enhance our understanding of recovery from damage and disease. Macrophages play a crucial role in tissue repair and regeneration, with their subpopulations indirectly promoting axonal regeneration through developmental signals. The AP-1 signaling pathway, mediated by TNF/Tnfrsf1a, can elevate HDAC1 expression and facilitate regeneration. Furthermore, following spinal cord injury (SCI), pMN progenitors have been observed to switch between oligodendrocyte and motor neuron fates, with macrophage-secreted TNF-α potentially regulating the differentiation of ependymal–radial glia progenitors and oligodendrocytes. Radial glial cells (RGs) are also essential for CNS regeneration in zebrafish, as they perform neurogenesis and gliogenesis, with specific RG subpopulations potentially existing for the generation of neurons and oligodendrocytes. This review article underscores the critical role of macrophages and their subpopulations in tissue repair and regeneration, focusing on their secretion of TNF-α, which promotes axonal regeneration in zebrafish. We also offer insights into the molecular mechanisms underlying TNF-α’s ability to facilitate axonal regeneration and explore the potential of pMN progenitor cells and RGs following SCI in zebrafish. The review concludes with a discussion of various unresolved questions in the field, and ideas are suggested for future research. Studying innate immune cell interactions with neuroglia following injury may lead to the development of novel strategies for treating the inflammatory processes associated with regenerative medicine, which are commonly observed in injury and disease.