Search Results (1,174)

Introduction: Cutaneous T cell lymphoma (CTCL), most commonly known as mycosis fungoides (MF), is characterized by an increasingly immunosuppressive tumor microenvironment (TME) as the disease progresses. Cancer-associated fibroblasts (CAFs) are key stromal components that support a permissive niche, in part through the secretion of small extracellular vesicles (sEVs), predominantly exosomes, that mediate intercellular communication. We investigated the immunomodulatory role of exosome-enriched sEVs derived from MF fibroblasts (MF-Fs) compared to normal fibroblasts (N-Fs). Materials and Methods: Primary MF-Fs from early-stage MF biopsies and N-Fs from healthy skin were cultured in vitro. sEVs enriched with exosomes were isolated by ultracentrifugation and characterized by flow cytometry (CD81), electron microscopy, Nanosight analysis, and protein quantification, and their uptake by normal peripheral blood mononuclear cells (nPBMCs) was confirmed using PKH26-labeled sEVs. nPBMCs, monocytes, CD4⁺ and CD8⁺ T cells from healthy donors were exposed to MF-F or N-F sEVs. Cell viability was assessed using MTT and trypan blue exclusion assays. Mass cytometry (CyTOF) profiled immune subsets and regulatory proteins for preliminary observation. Monocyte polarization was evaluated by flow cytometry for M1 (CD80, CD86) and M2 (CD163, CD206) markers and PD-L1 expression; M1/M2-associated cytokines and sEV-microRNAs were quantified by qRT-PCR. Results: Both MF-F and N-F sEVs were internalized by nPBMCs and reduced their viability, with a more pronounced effect observed for MF-F sEVs. In nPBMCs, MF-F sEVs also increased the frequency of M2-like macrophages, decreased M1 polarization, and enhanced PD-L1 expression. In primary monocytes, MF-F- compared with N-F-derived sEVs upregulated M2-associated cytokines (IL-10, TGF-β), increased PD-L1 expression, and generated M2-like cells that suppressed CD4⁺ and CD8⁺ T cell viability. Conclusions: MF-F sEVs promote an immunosuppressive TME and represent potential therapeutic or biomarker targets in MF. Full article

Tumor-associated macrophages (TAMs) are among the most important myeloid cell populations in the tumor microenvironment of digestive system tumors and are characterized by marked plasticity, heterogeneity, and context dependence. This review focuses on gastric, colorectal, liver, and pancreatic cancers as representative digestive system solid tumors in which TAM spatial organization has been increasingly characterized by single-cell and spatial omics studies. Traditional M1/M2 polarization or fixed subtype-based classification is insufficient to capture the continuous state transitions of TAMs across tumor types, disease stages, and tissue regions. Recent evidence suggests that TAM heterogeneity reflects dynamic functional states shaped within distinct spatial niches by local oxygen supply, metabolic stress, stromal architecture, vascular status, and interactions with neighboring cells. From a spatial-niche perspective, this review synthesizes current evidence on TAM distribution patterns, phenotypic changes, and functional biases across six recurrent spatial contexts: the hypoxic core, invasive front, fibrotic septa, perivascular regions, tertiary lymphoid structure (TLS)-adjacent regions, and necrotic borders. By linking these niches with cross-niche functional axes and evidence-supported molecular programs, we provide a structured niche-to-function framework for comparing TAM spatial heterogeneity and its major functional dimensions, including metabolic adaptation, tissue remodeling, and immune-inflammatory regulation. This context-sensitive framework may help guide future studies of niche-specific TAM reprogramming and rational combinations with immunotherapy and other treatment strategies. Full article

Background: Mitochondrial bioenergetic dysregulation disrupts immune−metabolic homeostasis and promotes pro−inflammatory microenvironments in osteoarthritis (OA) synovitis. However, the mechanistic contributions of mitochondrial energy metabolism to synovitis pathogenesis in OA remain poorly defined. Methods: We analyzed mitochondrial energy metabolism−related genes (MEMRGs) in OA synovitis by integrating transcriptomic data from OA synovial tissues (GSE55235, GSE55457). LASSO regression and maximal clique centrality (MCC) algorithms were applied to identify hub genes, and single−cell RNA sequencing (GSE152805) was used to examine cell−type−specific expression patterns. Functional validation was performed in IRS2−knockdown THP−1 macrophages. Results: We identified 22 mitochondrial energy metabolism−related differentially expressed genes (MEMR−DEGs), which were enriched in the AMPK signaling, glucagon signaling, and insulin signaling pathways. Four hub genes (FOXO3, FASN, PTGS2, IRS2) were identified, and their expression was negatively correlated with synovial macrophage infiltration. Single−cell RNA sequencing revealed that IRS2 was specifically upregulated in a synovial macrophage cluster. Functional studies in IRS2−knockdown THP−1 macrophages demonstrated that IRS2 deficiency impaired IL−4−induced M2 macrophage polarization and reduced mitochondrial membrane potential and ATP synthesis, which was mediated by the suppression of the AKT/FOXO1 signaling. Conclusions: IRS2 potentially influences mitochondrial energy metabolism, as evidenced by the maintenance of mitochondrial membrane potential and ATP synthesis, via the AKT/FOXO1 signaling pathways to maintain synovial macrophage M2 polarization homeostasis. These findings provide novel molecular targets for addressing immune−metabolic pathways in OA therapy. Full article

Periodontitis is a chronic inflammatory disease characterized by alveolar bone loss driven by dysregulated immune responses. We previously showed that extracellular vesicles derived from retinoic acid-induced regulatory T lymphocytes (RA-Treg EVs) suppress pathogenic CD4⁺ T-lymphocyte responses and reduce alveolar bone loss during periodontitis. Herein, we investigated whether RA-Treg EVs also modulate macrophage and CD8⁺ T-lymphocyte responses during experimental periodontitis. Ligature-induced periodontitis was generated in mice, followed by local administration of RA-Treg EVs. Alveolar bone loss was analyzed by micro-computed tomography, and periodontal tissues and cervical lymph nodes were analyzed by flow cytometry to quantify antigen-presenting cells, macrophages, macrophage subsets, and CD8⁺ T lymphocytes. The direct effects of RA-Treg EVs on macrophage phenotype and CD8⁺ T-cell proliferation and activation were assessed in vitro. RA-Treg EV treatment attenuated alveolar bone loss and preserved trabecular microarchitecture. This effect was associated with reduced macrophage infiltration into periodontal tissues, modulation of macrophage polarization, and restoration of CD8⁺ T-cell abundance in periodontal tissues and draining cervical lymph nodes, without major changes in CD8⁺IFN-γ⁺ or CD8⁺RANKL⁺ cells. In vitro, RA-Treg EVs induced heterogeneous macrophage phenotypes distinct from the classical M1/M2 polarization states while markedly enhancing CD8⁺ T-cell proliferation and activation. These findings indicate that RA-Treg EVs preserve alveolar bone during experimental periodontitis while selectively modulating macrophage and CD8⁺ T-lymphocyte responses. Full article

Background: Colorectal cancer (CRC) remains a leading cause of cancer-related mortality worldwide, with poor survival rates of late-stage disease. While immune checkpoint blockade (ICB) therapy has transformed treatment for mismatch repair-deficient (MMRd)/microsatellite instability-high (MSI-H) tumors, most CRC cases are mismatch repair-proficient (MMRp)/microsatellite-stable (MSS) and derive little to no benefit from current immunotherapy regimens. Tumor-associated macrophages (TAMs) constitute a significant component of the tumor microenvironment (TME) and exhibit a phenotypic gradient between pro-inflammatory (M1-like) and anti-inflammatory, immunosuppressive (M2-like) states. Although their polarization status is increasingly recognized as a key modulator of immunotherapy efficacy in CRC, a comprehensive synthesis of the literature regarding macrophage polarization and its relevance to improving CRC immunotherapy remains lacking. Methods: A systematic literature search was conducted across PubMed, EMBASE, and ScienceDirect from inception to December 2025 using terms encompassing macrophages, immunotherapy, immune checkpoint expression, colorectal cancer, and microsatellite stability status. Title, abstract, and full-text screening were performed independently by multiple authors. Sixty-five studies were included following PRISMA guidelines. The protocol was prospectively registered on PROSPERO (ID: CRD420251244320). Results: Three key themes were identified: (1) macrophage-mediated mechanisms of resistance to ICB, including M2 polarization driven by the PI3Kγ, STAT3, mTOR, and SIRT-1 axes, immunosuppressive cytokine production (IL-10, TGF-β), and altered immune checkpoint ligand expression; (2) macrophage polarization status and associated biomarkers as prognostic indicators of therapeutic response; (3) emerging macrophage-targeted therapeutic strategies in ongoing clinical trials, including CSF1R inhibitors, CD40 agonists, CD47/SIRPα blockade, and STING agonists. Conclusions: TAM polarization is a critical determinant of immunotherapy resistance and patient prognosis in CRC. Macrophage-targeted strategies, particularly M2-to-M1 repolarization approaches used in combination with existing ICB regimens, represent a promising avenue for expanding immunotherapy efficacy beyond MSI-H disease. Further translational research and randomized controlled trials are needed to validate these targets clinically. Full article

Introduction: Neuroinflammation is a key feature of both Alzheimer’s disease (AD) and glioblastoma, although it leads to different outcomes in each disorder. In AD, chronic activation of microglia and astrocytes by amyloid-β and tau contributes to neuronal injury and cognitive decline. In glioblastoma, tumor cells exploit inflammatory pathways to create an immunosuppressive microenvironment that supports tumor growth. This review compares the shared and distinct neuroinflammatory mechanisms in AD and glioblastoma and highlights their therapeutic relevance. Materials and Methods: This study was conducted as a narrative review based on a PubMed search performed by three reviewers. English-language articles on AD, glioblastoma, and neuroinflammatory pathways were included, covering original studies, reviews, meta-analyses, and experimental and clinical reports. Keywords included neuroinflammation, microglia, astrocytes, tumor-associated macrophages, inflammasomes, NLRP3, NF-κB, HIF-1α, cytokines, blood–brain barrier, and miRNAs. Due to study heterogeneity, findings were synthesized descriptively. Results: AD and glioblastoma share major neuroinflammatory mechanisms, including microglial and astrocytic activation, cytokine signaling, inflammasome activity, blood–brain barrier dysfunction, hypoxia-related changes, and miRNA regulation. In AD, these pathways promote chronic inflammation, synaptic loss, and neurodegeneration, with NLRP3, NF-κB, and M1-like microglial polarization playing central roles. In glioblastoma, similar pathways are redirected toward tumor progression through tumor-associated macrophages, reactive astrocytes, angiogenesis, immune evasion, and therapy resistance. Key overlapping mediators include IL-1β, TNF-α, NF-κB, HIF-1α, GSK-3β, and selected miRNAs. Conclusions: AD and glioblastoma are connected by common neuroinflammatory pathways, but these processes result in neurodegeneration in AD and tumor support in glioblastoma. Understanding these shared and divergent mechanisms may guide the development of biomarkers and targeted therapies focused on microglia, inflammasomes, cytokines, and immune reprogramming in both diseases. Full article

Reparative macrophage polarization and macrophage-derived reactive oxygen species (ROS) are required for ischemia-induced revascularization in peripheral artery disease (PAD). Our previous study showed that mitochondrial fission protein dynamin-related protein 1 (DRP1) promotes reparative polarization and metabolic reprogramming in macrophages and post-ischemic neovascularization. However, the redox-dependent mechanism governing DRP1 activation in this context remains elusive. Here, using a mouse hindlimb ischemia (HLI) model of PAD, we identify cysteine sulfenylation (CysOH) of DRP1 as a critical redox modification induced in ischemic bone marrow (BM)-derived cells. BM chimeric mice reconstituted with CRISPR/Cas9-generated “redox-dead” DRP1-C631A knock-in mutant (Drp1^C/A) BM exhibited markedly reduced limb perfusion recovery and CD31⁺ capillary density in ischemic muscles following HLI. These defects were associated with enhanced Ly6G⁺ neutrophil accumulation, pro-inflammatory F4/80⁺CD80⁺ M1-like macrophages and reduced anti-inflammatory F4/80⁺CD206⁺ M2-like macrophages in ischemic muscle. Mechanistically, using an in vitro PAD model, hypoxia serum starvation (HSS) rapidly induced NADPH oxidase 2-dependent cytosolic ROS production and DRP1-CysOH formation in wild-type macrophages. In contrast, Drp1^C/A macrophages failed to undergo DRP1-CysOH-dependent mitochondrial fission under HSS, resulting in aberrant metabolic reprogramming characterized by enhanced glycolysis and mitochondrial ROS, pro-inflammatory p-NF-κB and M1-genes, and suppressed anti-inflammatory p-AMPK, efferocytosis and M2-genes. Thus, our findings establish DRP1 sulfenylation as a previously unrecognized redox-sensing mechanism that links ischemia-induced ROS to reparative macrophage reprogramming and revascularization, identifying a novel therapeutic target for PAD. Full article

Cutaneous leishmaniasis (CL) is the most common clinical form of leishmaniasis, characterized by persistent skin ulcers and nodules. Standard chemotherapeutic agents have substantial toxicity and do nothing to repair the damaged tissue, an unmet need that motivates the search for adjunctive strategies. Mesenchymal stem cells (MSCs) can modulate macrophage activity and support tissue regeneration, yet their role in CL has received limited attention. In this study, we tested whether bone marrow-derived MSCs (BM-MSCs) could attenuate Leishmania mexicana-induced inflammation and facilitate skin repair. Indirect co-culture of BM-MSCs with infected RAW264.7 macrophages shifted the macrophage phenotype from M1 toward M2, with higher IL-10 and Arg-1 expression and lower iNOS and IL-1β. In BALB/c mice with established CL, three weekly intravenous injections of BM-MSCs reduced paw swelling, improved skin histology, decreased type I collagen deposition, lowered Integrin β1 and Cytokeratin 17 expression, and reduced tissue parasite load. Immunofluorescence confirmed a predominantly M2 macrophage distribution in treated lesions. We inferred that BM-MSCs acted on both the immune and reparative aspects of the disease process, supporting their potential as an adjunct to conventional anti-leishmanial therapy. Full article

Diabetic wounds are characterized by persistent hyperglycemia, excessive ROS accumulation, sustained inflammation, and impaired angiogenesis, yet current treatments remain suboptimal. To address these challenges, we developed a mild heat stimulating and microenvironment reprogramming hydrogel (termed C-4-N) via a green synthetic strategy. L-Arginine (L-Arg) triggered the spontaneous self-polymerization of protocatechuic aldehyde (PA) into poly (protocatechuic aldehyde) (PPA) nanoparticles, onto which ginsenoside Compound K (CK) was subsequently loaded, yielding CK/L-Arg/PPA nanoparticles. These nanoparticles were then uniformly embedded into a dynamic disulfide network composed of α-lipoic acid (LA)-modified chitosan (CS-LA) and 4-arm-PEG-SH under UV irradiation without toxic photo-initiators, forming the C-4-N hydrogel. The C-4-N hydrogel reprogrammed the diabetic wound microenvironment through three synergistic mechanisms, lowering blood glucose and scavenging ROS via the coordinated actions of LA, CK and PPA, promoting M1-to-M2 macrophage polarization via downregulation of pro-inflammatory cytokines (TNF-α, IL-6) and upregulation of anti-inflammatory cytokines (IL-10, TGF-β1), further amplified by mild photothermal stimulation of 40–43 °C. In a diabetic rat model, the C-4-N hydrogel achieved a near-complete wound closure rate of 99.49 ± 0.10% on day 13 upon mild photothermal stimulation, accompanied by enhanced re-epithelialization, organized collagen deposition, vascular maturation, and systemic glucose regulation. In summary, this green synthesized, mild heat-stimulating hydrogel establishes a synergistic microenvironment reprogramming paradigm for chronic diabetic wound managements. Full article

Prolonged use of clear aligners promotes bacterial colonization and biofilm formation, which can compromise orthodontic outcomes. There is a clear clinical demand for approaches that can suppress pathogenic activity while preserving the fundamental functional and material characteristics of the aligners. To address this need, a novel strategy of fabricating metal–organic framework (MOF) coatings on aligners was adopted. Metal–organic frameworks (MOFs) have emerged as promising antibacterial coating materials by combining antimicrobial metal ions with biocompatible organic ligands. Three distinct porphyrin-based MOFs (Ag-, Cu-, and Ce-TCPP) were synthesized and fabricated as coatings on clear aligner surfaces via a coordination-driven self-assembly approach. The coated aligners were comprehensively assessed in vitro to determine their antibacterial performance, anti-inflammatory potential, biocompatibility, and key physical characteristics. Among the three coatings, Ag-TCPP showed the most favorable overall antibacterial and anti-biofilm performance in the present experimental system and facilitated macrophage polarization toward an anti-inflammatory M2-like phenotype. Ag-TCPP exhibited a significant inhibition zone of 6.75 ± 0.25 mm and reduced biofilm biomass by 72.2%. All MOF coatings exhibited excellent biocompatibility, and their application did not compromise the aligners’ mechanical integrity or aesthetic properties (light transmittance). This study reports the successful development of a novel metal–organic framework (MOF)-based coating strategy for clear aligners. Among the formulations investigated, the Ag-TCPP coating exhibited outstanding antibacterial and immunomodulatory performance while maintaining the critical mechanical integrity and aesthetic qualities of the aligner. The findings of this work offer a practical approach to designing multifunctional orthodontic devices that may reduce biofilm-related complications and improve clinical outcomes. Full article

Background/Objectives: Obesity is a major public health problem associated with chronic inflammation and functional alterations in multiple organs and systems. Few studies have examined colostrum from obese mothers, particularly with respect to macrophage function, enzyme and cytokine concentrations, and the role of melatonin in immune modulation. This study aimed to evaluate melatonin levels and their effects on macrophage polarization, cytokine concentrations, nitric oxide synthase [iNOS], and arginase in colostrum from obese mothers. Colostrum samples were collected from eutrophic mothers [BMI: 18.5–24.9 kg/m²] and obese mothers [BMI: ≥30 kg/m²]. Methods: Macrophages were isolated by density gradient and treated with melatonin. The expression of M1 and M2 macrophages and cytokine concentrations were assessed by flow cytometry, while melatonin levels in colostrum supernatants, iNOS, and arginase in cell lysates were determined by ELISA. Results: An endogenous increase in melatonin was also observed in the colostrum of obese mothers. Maternal obesity has been shown to reduce M1 and M2 macrophage expression, increase nitric oxide synthase [NOS] activity, and elevate interleukin-6 [IL-6] and interleukin-17 [IL-17] levels. However, melatonin treatment restored M1 and M2 macrophage levels and reduced inducible nitric oxide synthase [iNOS] and arginase production to levels similar to those observed in mothers of healthy weight. Conclusions: these findings suggest that maternal obesity creates a pro-inflammatory environment in colostrum, characterized by altered macrophage polarization, altered cytokine secretion, and an imbalance in the enzymatic activities of iNOS and arginase within the L-arginine metabolic pathway. Both natural and supplemental melatonin exhibited immunomodulatory, antioxidant, and anti-inflammatory effects, helping to restore immune balance in colostrum. These results emphasize the potential benefits of melatonin as an immunometabolic modulator and its contribution to understanding immunometabolic regulation in obese mothers. Full article

The treatment of intracellular bacterial infections such as Chlamydia remains a significant clinical challenge due to rising antibiotic resistance and persistent, immunopathology-driven tissue damage. Macrophages are essential for host defense; they can originate from both tissue-resident precursors and circulating monocytes. During infection, macrophages at infected sites are largely derived from monocytes that migrate and differentiate there, where they phagocytose pathogens and orchestrate immune responses. The chemokine receptor CCR2 is a key regulator of this process, yet its role beyond monocyte trafficking is not fully understood. Previous studies have shown that CCR2 deficiency impairs monocyte mobilization and exacerbates disease during Chlamydia infection, shifting immune responses away from protective Th1 immunity toward pathological Th2 and Th17 polarization. Here, we investigate how CCR2 regulates macrophage function to balance protective Th1 versus pathological Th2/Th17 immunity during Chlamydia respiratory infection. Our results show that CCR2 deficiency reduces pulmonary infiltration of Ly6C^hi and Ly6C^low monocytes and shifts macrophage differentiation away from an M1-like toward an M2-like phenotype. Mechanistically, CCR2 deficiency compromises macrophage endocytosis and survival, elevates ROS production, and activates the NLRP3 inflammasome, leading to Caspase-3/GSDME-mediated pyroptosis with increased IL-1β and IL-18, while suppressing the Caspase-1/GSDMD pathway. These findings were recapitulated in vitro using C. muridarum-stimulated Ccr2-deficient bone marrow-derived macrophages (BMDMs), which also showed impaired migration, reduced M1-like polarization, diminished endocytosis, and enhanced ROS/NLRP3/pyroptosis. Furthermore, co-culture of these BMDMs with CD4⁺ T cells revealed that Th1 differentiation was inhibited, whereas Th2 and Th17 responses were promoted. Collectively, CCR2 orchestrates monocyte–macrophage function by driving M1-like polarization and inhibiting NLRP3/Caspase-3/GSDME pyroptosis to rebalance Th1/Th2/Th17 immunity, thereby enhancing bacterial clearance while mitigating immunopathological tissue damage during Chlamydia infection. Full article

Background: The incidence of inflammatory bowel disease (IBD) is growing in the population. At present, the etiology of inflammatory bowel disease remains unclear, and there is no effective and low-toxic therapeutic drug. This study aimed to investigate the role of Lobenzarit (Lbz) in the treatment of colitis in mice as well as the underlying mechanism. Methods: In this experiment, colitis was induced in mice with dextran sulphate sodium (Dss). Subsequently, the role of Lbz in colitis and its underlying mechanisms were examined using H&E staining, TEM, ELISA, PCR, and other assays. Results: Lbz significantly attenuated the related symptoms of Dss-induced colitis in mice. In addition, Lbz suppressed neutrophil infiltration and restored macrophage polarization towards an anti-inflammatory state. Lbz also inhibited (p < 0.05) the activation of signaling pathways TLR4 and MAPK (51.61% decrease for TLR4 and 56.94% decrease for MAPK), reduced the release of inflammatory factors as it significantly decreased (p < 0.05) colonic IL-1β, TNF-α, IFN-γ, COX2, and VEGF (47.63, 42.49, 53.42, 58.74, and 61.28% decreases respectively) thereby attenuating the inflammatory response in mice. Lbz administration also restored the permeability of the intestinal barrier by increasing (p < 0.05) tight junction-associated proteins (claudin-1, occludin, and ZO-1 with a 5.36- and 2.26-fold increase for claudin-1 and ZO-1, respectively) and decreasing (p < 0.05) MALK levels by 53.51%. In addition, Lbz upregulated colonic Cytochrome C oxidase II, PDH, and ATP synthase levels and upregulated CD163, CD206, c-Maf, and PPAR-γ levels as compared to the DSS-treated group. Conclusions: Lbz has a repairing effect on Dss-induced colitis and may alleviate Dss-induced colitis by targeting the TLR4 pathway and promoting intestinal stem cell proliferation. Full article

Background/Objectives: Pediatric group 3 (G3) medulloblastomas (MB) are therapy resistant and have a significantly worse prognosis than the other MB subtypes. Aggressive radiation/chemotherapy improves survival, but potential long-term comorbidities include neurocognitive deficits. In previous work, we demonstrated that low-dose X-ray radiation (LDXR) acts as an immunological adjuvant. Recent studies have demonstrated that galectin-3 (Gal-3) expression in MB tumors accelerates M2 macrophage infiltration and restricts T cell receptor (TCR)-mediated signaling. Immunotherapy with an agonistic anti-4-1BB monoclonal antibody (mAb) activates CD8+ T cells, promoting their survival and acquisition of potent cytolytic properties. Building on these findings, we hypothesized that immune priming via sublethal LDXR, combined with a Gal-3 inhibitor and an anti-4-1BB mAb, would boost anti-tumor effects, resulting in survival benefits. Methods: We tested this hypothesis in vitro in co-cultures of human MB cells and in vivo, in an immunocompetent G3MB mouse model (MP1). Treatment effects were assessed using Western blot, flow cytometry, hematoxylin and eosin (H&E) staining, immunofluorescence imaging, and analysis of cytokine and chemokine expression. Results: Our data demonstrated higher Gal-3 expression in MB patient-derived tumor tissue than in non-tumor tissue. LDXR modulated major histocompatibility complex molecules, and, combined with a Gal-3 inhibitor and an anti-4-1BB mAb, altered T-cell/tumor-cell interactions, enhanced T-cell-mediated MB cell death, and shifted cytokine production to drive microglial polarization toward the M1 subtype. Furthermore, H&E-stained tumor sections showed a ~70% reduction in tumor size compared with untreated controls. Conclusions: These preclinical findings suggest that combining immune priming with sublethal LDXR, Gal-3 inhibition, and 4-1BB activation may be an effective treatment strategy for G3MB. Full article

Bone loss in the maxillofacial region arises from multiple causes, including periodontal disease, trauma, surgical procedures, infection, congenital anomalies, and cancer. Traditional treatment relies on bone grafting, either alone or in combination with biomaterials. Advances in tissue engineering have introduced synthetic or natural scaffolds to mimic the mineralized bone matrix. Natural scaffolds offer excellent biocompatibility and similarity to native tissue but often lack sufficient mechanical strength and exhibit poor degradation rates. Synthetic scaffolds provide tunable porosity and mechanical stability; however, their biological inertness makes them poor sources of osteogenic signaling. A key factor in the success of any scaffold is its interaction with the host immune system. Upon implantation, the innate immune response is initiated, with neutrophils and macrophages being the first cells to contact the scaffold. Macrophage polarization toward proinflammatory (M1) or anti-inflammatory (M2) phenotypes determines whether the microenvironment favors inflammation or remodeling. The adaptive immune response also plays a critical role: T and B lymphocytes may promote tolerance and integration through Th2/Treg pathways and antibody-mediated regulation, or they may trigger chronic inflammation and rejection through Th1/Th17 activation. This review examines the natural and synthetic materials used for bone remodeling and their biological properties. It then outlines the sequence of immune events occurring from the moment a scaffold is implanted to its potential integration or failure. Finally, this study highlights the relevance of cellular models and in vitro assays for the early evaluation of immunogenicity and biocompatibility, which are essential for optimizing scaffold design and improving outcomes in maxillofacial bone regeneration. Full article