DEL-1 promotes macrophage efferocytosis and clearance of inflammation

Efferocytosis in atherosclerosis

Cardiovascular disease is the leading cause of death worldwide, and it commonly results from atherosclerotic plaque progression. One of the increasingly recognized drivers of atherosclerosis is dysfunctional efferocytosis, a homeostatic mechanism responsible for the clearance of dead cells and the resolution of inflammation. In atherosclerosis, the capacity of phagocytes to participate in efferocytosis is hampered, leading to the accumulation of apoptotic and necrotic tissue within the plaque, which results in enlargement of the necrotic core, increased luminal stenosis and plaque inflammation, and predisposition to plaque rupture or erosion. In this Review, we describe the different forms of programmed cell death that can occur in the atherosclerotic plaque and highlight the efferocytic machinery that is normally implicated in cardiovascular physiology. We then discuss the mechanisms by which efferocytosis fails in atherosclerosis and other cardiovascular and cardiometabolic diseases, including myocardial infarction and diabetes mellitus, and discuss therapeutic approaches that might reverse this pathological process.

EDIL3/Del-1 prevents aortic dissection through enhancing internalization and degradation of apoptotic vascular smooth muscle cells

Thoracic aortic dissection (TAD) is a severe disease, characterized by numerous apoptotic vascular smooth muscle cells (VSMCs). EDIL3/Del-1 is a secreted protein involved in macrophage efferocytosis in acute inflammation. Here, we aimed to investigate whether EDIL3 promoted the internalization and degradation of apoptotic VSMCs during TAD. The levels of EDIL3 were decreased in the serum and aortic tissue from TAD mice. Global edil3 knockout (edil3-/-) mice and edil3-/- bone marrow chimeric mice exhibited a considerable exacerbation in β-aminopropionitrile monofumarate (BAPN)-induced TAD, accompanied with increased apoptotic VSMCs accumulating in the damaged aortic tissue. Two types of phagocytes, RAW264.7 cells and bone marrow-derived macrophages (BMDMs) were used for in vitro efferocytosis assay. edil3-deficient phagocytes exhibited inefficient internalization and degradation of apoptotic VSMCs. Instead, EDIL3 promoted the internalization phase through interacting with phosphatidylserine (PtdSer) on apoptotic VSMCs and binding to the macrophage ITGAV/αv-ITGB3/β3 integrin. In addition, EDIL3 accelerated the degradation phase through activating LC3-associated phagocytosis (LAP). Mechanically, following the engulfment, EDIL3 enhanced the activity of SMPD1/acid sphingomyelinase in the phagosome through blocking ITGAV-ITGB3 integrin, which facilitates phagosomal reactive oxygen species (ROS) production by NAPDH oxidase CYBB/NOX2. Furthermore, exogenous EDIL3 supplementation alleviated BAPN-induced TAD and promoted apoptotic cell clearance. EDIL3 may be a novel factor for the prevention and treatment of TAD.Abbreviations: BAPN: β-aminopropionitrile monofumarate; BMDM: bone marrow-derived macrophage; C12FDG: 5-dodecanoylaminofluorescein-di-β-D-galactopyranoside; CTRL: control; CYBB/NOX2: cytochrome b-245, beta polypeptide; DCFH-DA: 2',7'-dichlorofluorescin diacetate; EDIL3/Del-1: EGF-like repeats and discoidin I-like domains 3; EdU: 5-ethynyl-2'-deoxyuridine; EVG: elastic van Gieson; H&E: hematoxylin and eosin; IL: interleukin; LAP: LC3-associated phagocytosis; MAP1LC3/LC3: microtubule-associated protein 1 light chain 3; NAC: N-acetylcysteine; PtdSer: phosphatidylserine; rEDIL3: recombinant EDIL3; ROS: reactive oxygen species; SMPD1: sphingomyelin phosphodiesterase 1; TAD: thoracic aortic dissection; TEM: transmission electron microscopy; VSMC: vascular smooth muscle cell; WT: wild-type.

Hierarchically structured nanofibrous scaffolds spatiotemporally mediate the osteoimmune micro-environment and promote osteogenesis for periodontitis-related alveolar bone regeneration

Periodontitis suffer from inflammation-induced destruction of periodontal tissues, resulting in the serious loss of alveolar bone. Controlling inflammation and promoting bone regeneration are two crucial aspects for periodontitis-related alveolar bone defect treatment. Herein, we developed a hierarchically structured nanofibrous scaffold with a nano-embossed sheath and a bone morphogenetic protein 2-loaded core to match the periodontitis-specific features that spatiotemporally modulated the osteoimmune environment and promoted periodontal bone regeneration. We investigated the potential of this unique scaffold to treat periodontitis-related alveolar bone defects in vivo and in vitro. The results demonstrated that the hierarchically structured scaffold effectively reduced the inflammatory levels in macrophages and enhanced the osteogenic potential of bone mesenchymal stem cells in an inflammatory microenvironment. Moreover, in vivo experiments revealed that the hierarchically structured scaffold significantly ameliorated inflammation in the periodontium and inhibited alveolar bone resorption. Notably, the hierarchically structured scaffold also exhibited a prolonged effect on promoting alveolar bone regeneration. These findings highlight the significant therapeutic potential of hierarchically structured nanofibrous scaffolds for the treatment of periodontitis, and their promising role in the field of periodontal tissue regeneration. STATEMENT OF SIGNIFICANCE: We present a novel hierarchically structured nanofibrous scaffold of coupling topological and biomolecular signals for precise spatiotemporal modulation of the osteoimmune micro-environment. Specifically, the scaffold was engineered via coaxial electrospinning of the poly(ε-caprolactone) sheath and a BMP-2/polyvinyl alcohol core, followed by surface-directed epitaxial crystallization to generate cyclic nano-lamellar embossment on the sheath. With this unique hierarchical structure, the cyclic nano-lamellar sheath provided a direct nano-topographical cue to alleviate the osteoimmune environment, and the stepwise release of BMP-2 from the core provided a biological cue for bone regeneration. This research underscores the potential of hierarchically structured nanofibrous scaffolds as a promising therapeutic approach for periodontal tissue regeneration and highlights their role in advancing periodontal tissue engineering.

Analysis of immunogenic cell death in periodontitis based on scRNA-seq and bulk RNA-seq data

Background

Recent studies have suggested that cell death may be involved in bone loss or the resolution of inflammation in periodontitis. Immunogenic cell death (ICD), a recently identified cell death pathway, may be involved in the development of this disease.

Methods

By analyzing single-cell RNA sequencing (scRNA-seq) for periodontitis and scoring gene set activity, we identified cell populations associated with ICD, which were further verified by qPCR, enzyme linked immunosorbent assay (ELISA) and immunofluorescence (IF) staining. By combining the bulk transcriptome and applying machine learning methods, we identified several potential ICD-related hub genes, which were then used to build diagnostic models. Subsequently, consensus clustering analysis was performed to identify ICD-associated subtypes, and multiple bioinformatics algorithms were used to investigate differences in immune cells and pathways between subtypes. Finally, qPCR and immunohistochemical staining were performed to validate the accuracy of the models.

Results

Single-cell gene set activity analysis found that in non-immune cells, fibroblasts had a higher ICD activity score, and KEGG results showed that fibroblasts were enriched in a variety of ICD-related pathways. qPCR, Elisa and IF further verified the accuracy of the results. From the bulk transcriptome, we identified 11 differentially expressed genes (DEGs) associated with ICD, and machine learning methods further identified 5 hub genes associated with ICD. Consensus cluster analysis based on these 5 genes showed that there were differences in immune cells and immune functions among subtypes associated with ICD. Finally, qPCR and immunohistochemistry confirmed the ability of these five genes as biomarkers for the diagnosis of periodontitis.

Conclusion

Fibroblasts may be the main cell source of ICD in periodontitis. Adaptive immune responses driven by ICD may be one of the pathogenesis of periodontitis. Five key genes associated with ICD (ENTPD1, TLR4, LY96, PRF1 and P2RX7) may be diagnostic biomarkers of periodontitis and future therapeutic targets.

The intricate interplay between ferroptosis and efferocytosis in cancer: unraveling novel insights and therapeutic opportunities

The complex interplay between ferroptosis and efferocytosis in cancer has attracted significant interest recently. Efferocytosis, the process of eliminating apoptotic cells, is essential for preserving tissue homeostasis and reducing inflammation. However, dysregulation of efferocytosis can have profound effects on cancer. Apoptotic cells accumulate because of impaired efferocytosis, which triggers chronic inflammation and the release of pro-inflammatory chemicals. Surprisingly, accumulating evidence suggests that dysregulation of ferroptosis- a form of controlled cell death characterized by lipid peroxidation and the buildup iron-dependent reactive oxygen species (ROS)-can influence efferocytic activities within the tumor microenvironment. Dysfunctional iron metabolism and increased lipid peroxidation, are associated with ferroptosis, resulting in inadequate apoptotic cell clearance. Conversely, apoptotic cells can activate ferroptotic pathways, increasing oxidative stress and inducing cell death in cancer cells. This reciprocal interaction emphasizes the complex relationship between efferocytosis and ferroptosis in cancer biology. Understanding and managing the delicate balance between cell clearance and cell death pathways holds significant therapeutic potential in cancer treatment. Targeting the efferocytosis and ferroptosis pathways may offer new opportunities for improving tumor clearance, reducing inflammation, and sensitizing cancer cells to therapeutic interventions. Further research into the interaction between efferocytosis and ferroptosis in cancer will provide valuable insights for the development of novel therapies aimed at restoring tissue homeostasis and improving patient outcomes.

Peptidyl arginine deiminase-4 inhibitor ameliorates pulmonary fibrosis through positive regulation of developmental endothelial locus-1

Recurring lung injury, chronic inflammation, aberrant tissue repair and impaired tissue remodelling contribute to the pathogenesis of pulmonary fibrosis (PF). Neutrophil extracellular traps (NETs) are released by activated neutrophils to trap, immobilise and kill invading pathogen and is facilitated by peptidyl arginine deiminase-4 (PAD-4). Dysregulated NETs release and abnormal PAD-4 activation plays a crucial role in activating pro-fibrotic events in PF. Developmental endothelial locus-1 (Del-1), expressed by the endothelial cells of lungs and brain acts as an endogenous inhibitor of inflammation and fibrosis. We have hypothesised that PAD-4 inhibitor exerts anti-inflammatory and anti-fibrotic effects in mice model of PF. We have also hypothesised by PAD-4 regulated the transcription of Del-1 through co-repression and its inhibition potentiates anti-fibrotic effects of Del-1. In our study, the PAD-4 inhibitor chloro-amidine (CLA) demonstrated anti-NETotic and anti-inflammatory effects in vitro in differentiated HL-60 cells. In a bleomycin-induced PF mice model, CLA administration in two doses (3 mg/kg, I.P and 10 mg/kg, I.P) improved lung function, normalized bronchoalveolar lavage fluid parameters, and attenuated fibrotic events, including markers of extracellular matrix and epithelial-mesenchymal transition. Histological analyses confirmed the restoration of lung architecture and collagen deposition with CLA treatment. ELISA, IHC, IF, RT-PCR, and immunoblot analysis supported the anti-NETotic effects of CLA. Furthermore, BLM-induced PF reduced Del-1 and p53 expression, which was normalized by CLA treatment. These findings suggest that inhibition of PAD-4 results in amelioration of PF in animal model and may involve modulation of Del-1 and p53 pathways, warranting further investigation.

Mechanism of Efferocytosis in Determining Ischaemic Stroke Resolution-Diving into Microglia/Macrophage Functions and Therapeutic Modality

After ischaemic cerebral vascular injury, efferocytosis-a process known as the efficient clearance of apoptotic cells (ACs) by various phagocytes in both physiological and pathological states-is crucial for maintaining central nervous system (CNS) homeostasis and regaining prognosis. The mechanisms of efferocytosis in ischaemic stroke and its influence on preventing inflammation progression from secondary injury were still not fully understood, despite the fact that the fundamental process of efferocytosis has been described in a series of phases, including AC recognition, phagocyte engulfment, and subsequent degradation. The genetic reprogramming of macrophages and brain-resident microglia after an ischaemic stroke has been equated by some researchers to that of the peripheral blood and brain. Based on previous studies, some molecules, such as signal transducer and activator of transcription 6 (STAT6), peroxisome proliferator-activated receptor γ (PPARG), CD300A, and sigma non-opioid intracellular receptor 1 (SIGMAR1), were discovered to be largely associated with aspects of apoptotic cell elimination and accompanying neuroinflammation, such as inflammatory cytokine release, phenotype transformation, and suppressing of antigen presentation. Exacerbated stroke outcomes are brought on by defective efferocytosis and improper modulation of pertinent signalling pathways in blood-borne macrophages and brain microglia, which also results in subsequent tissue inflammatory damage. This review focuses on recent researches which contain a number of recently discovered mechanisms, such as studies on the relationship between benign efferocytosis and the regulation of inflammation in ischaemic stroke, the roles of some risk factors in disease progression, and current immune approaches that aim to promote efferocytosis to treat some autoimmune diseases. Understanding these pathways provides insight into novel pathophysiological processes and fresh characteristics, which can be used to build cerebral ischaemia targeting techniques.

Crosstalk between ferroptosis and macrophages: potential value for targeted treatment in diseases

Ferroptosis is a newly identified form of programmed cell death that is connected to iron-dependent lipid peroxidization. It involves a variety of physiological processes involving iron metabolism, lipid metabolism, oxidative stress, and biosynthesis of nicotinamide adenine dinucleotide phosphate, glutathione, and coenzyme Q10. So far, it has been discovered to contribute to the pathological process of many diseases, such as myocardial infarction, acute kidney injury, atherosclerosis, and so on. Macrophages are innate immune system cells that regulate metabolism, phagocytize pathogens and dead cells, mediate inflammatory reactions, promote tissue repair, etc. Emerging evidence shows strong associations between macrophages and ferroptosis, which can provide us with a deeper comprehension of the pathological process of diseases and new targets for the treatments. In this review, we summarized the crosstalk between macrophages and ferroptosis and anatomized the application of this association in disease treatments, both non-neoplastic and neoplastic diseases. In addition, we have also addressed problems that remain to be investigated, in the hope of inspiring novel therapeutic strategies for diseases.

Bite-sized immunology; damage and microbes educating immunity at the gingiva

Immune cells residing at the gingiva experience diverse and unique signals, tailoring their functions to enable them to appropriately respond to immunological challenges and maintain tissue integrity. The gingiva, defined as the mucosal barrier that surrounds and supports the teeth, is the only barrier site completely transected by a hard structure, the tooth. The tissue is damaged in early life during tooth eruption and chronically throughout life by the process of mastication. This occurs alongside challenges typical of barrier sites, including exposure to invading pathogens, the local commensal microbial community and environmental antigens. This review will focus on the immune network safeguarding gingival integrity, which is far less understood than that resident at other barrier sites. A detailed understanding of the gingiva-resident immune network is vital as it is the site of the inflammatory disease periodontitis, the most common chronic inflammatory condition in humans which has well-known detrimental systemic effects. Furthering our understanding of how the immune populations within the gingiva develop, are tailored in health, and how this is dysregulated in disease would further the development of effective therapies for periodontitis.

Evaluation of salivary interleukin‐17 and developmental endothelial locus‐1 in patients with periodontitis with and without type 2 diabetes mellitus

Background

Bidirectional positive relationship between periodontitis and type 2 diabetes mellitus (T2DM) has been recognized, interleukin 17 (IL‐17) and developmental endothelial locus‐1 (Del‐1) are proposed to play roles in periodontitis and T2DM. This study aims to investigate the association of IL‐17 and Del‐1 in patients with periodontitis with and without T2DM by measuring their salivary levels.

Methods

A total of 80 participants were enrolled in a cross‐sectional study and divided into healthy (H, n = 27), periodontitis (P, n = 29) and periodontitis with diabetes (PDM, n = 24) groups based on their periodontal and diabetic examination results. Periodontal parameters (plaque index [PI], bleeding on probing [BOP], probing depth [PD], and clinical attachment level [CAL]) as well as diabetic parameters (fasting plasma glucose [FG] and glycated hemoglobin [HbA1c]) were documented and unstimulated saliva was collected. Salivary IL‐1β, active‐matrix metalloproteinase‐8 (aMMP‐8), tumor necrosis factor‐α (TNF‐α), IL‐6, IL‐8, IL‐17, and Del‐1 were determined through enzyme‐linked immunosorbent assay (ELISA) and their relationships with periodontal and diabetic parameters were examined.

Results

The periodontitis and periodontitis with diabetes groups showed significantly higher levels of IL‐17 and lower levels of Del‐1 compared with healthy group. The periodontitis with diabetes group exhibited higher levels of IL‐17 and lower levels of Del‐1 compared with the periodontitis group. After correlation analysis, there were significant correlations between salivary IL‐17 and Del‐1 and clinical parameters, IL‐17 and Del‐1 were correlated with PD (r = 0.36, ‐0.39, p < 0.01), CAL (r = 0.40, ‐0.42, p < 0.01) and BOP (r = 0.35, ‐0.37, p < 0.01), they were correlated with FG (r = 0.26, ‐0.25, p < 0.05) and HbA1c (r = 0.28, ‐0.40, p < 0.05). Positive relationships were observed between IL‐17 and IL‐1β and between IL‐17 and aMMP‐8 (r = 0.80, 0.77, p < 0.01), while Del‐1 exhibited negative correlations with IL‐1β and aMMP‐8 (r = 0.59, 0.69 p < 0.01). Comparison between IL‐17 and Del‐1 confirmed an inverse relationship (r = ‐0.71, p < 0.01). Salivary Del‐1 levels in the older group were lower compared with young group across the H, P and PDM groups, although these differences were not statistically significant (p > 0.05).

Conclusions

Salivary IL‐17 and Del‐1 levels in the periodontitis with diabetes group showed significant changes compared with the periodontitis group, they exhibited an inverse relationship and were both correlated with periodontal parameters (PD, CAL, and BOP) and diabetic parameters (FG and HbA1c).

Plain Language Summary

Periodontitis and type 2 diabetes mellitus (T2DM) are two common diseases all over the world, some inflammatory mediators (interleukin 17 [IL‐17] and developmental endothelial locus‐1 [Del‐1]) regulate neutrophil production, recruitment and clearance when the body becomes infected and believed to be involved in the progress of diseases of periodontitis and diabetes. In this study, we enrolled healthy subjects, patients with periodontitis, patients with periodontitis and diabetes. We performed dental examinations and evaluated their blood glucose levels, collected their saliva, and detected IL‐17 and Del‐1 levels in their saliva. We found both patients with periodontitis and patients with periodontitis and diabetes showed higher IL‐17 levels and lower Del‐1 levels compared with healthy subjects. Patients with periodontitis and diabetes showed higher IL‐17 levels and lower Del‐1 levels compared with patients with periodontitis. Salivary IL‐17 and Del‐1 levels were both correlated with dental examination results and blood glucose levels, and salivary IL‐17 and Del‐1 displayed an inverse relationship.

EDIL3 alleviates Mannan-induced psoriatic arthritis by slowing the intracellular glycolysis process in mononuclear-derived dendritic cells

Psoriatic arthritis (PsA) is an immune-mediated, chronic inflammatory joint disease that commonly occurs as a complication of psoriasis. EGF-like repeats and discoidal I-like domain 3 (EDIL3) is a secreted protein with multiple structural domains and associated with various physiological functions. In this study, we employed a mannan-induced psoriatic arthritis model to investigate the impact of EDIL3 on PsA pathogenesis. Notably, a downregulation of EDIL3 expression was observed in the PsA model, which correlated with increased disease severity. EDIL3 knockout mice exhibited a more severe phenotype of PsA, which was ameliorated upon re-infusion of recombinant EDIL3 protein. The mitigation effect of EDIL3 on PsA depends on its regulation of the activation of monocyte-derived DCs (MoDCs) and T-help 17 cells (Th17). After inhibiting the function of MoDCs and Th17 cells with neutralizing antibodies, the beneficial effects of EDIL3 on PsA were lost. By inducing adenosine monophosphate (AMP)-activated protein kinase (AMPK) phosphorylation and suppressing protein kinase B (AKT) phosphorylation, EDIL3 attenuates intracellular glycolysis in MoDCs stimulated by glucose, thereby impeding their maturation and differentiation. Moreover, it diminishes the differentiation of Th17 cells and decelerates the progression of PsA. In conclusion, our findings elucidate the role and mechanism of EDIL3 in the development of PsA, providing a new target for clinical diagnosis and treatment.

Therapeutic delivery of CCL2 modulates immune response and restores host-microbe homeostasis

Many chronic inflammatory diseases are attributed to disturbances in host-microbe interactions, which drive immune-mediated tissue damage. Depending on the anatomic setting, a chronic inflammatory disease can exert unique local and systemic influences, which provide an exceptional opportunity for understanding disease mechanism and testing therapeutic interventions. The oral cavity is an easily accessible environment that allows for protective interventions aiming at modulating the immune response to control disease processes driven by a breakdown of host-microbe homeostasis. Periodontal disease (PD) is a prevalent condition in which quantitative and qualitative changes of the oral microbiota (dysbiosis) trigger nonresolving chronic inflammation, progressive bone loss, and ultimately tooth loss. Here, we demonstrate the therapeutic benefit of local sustained delivery of the myeloid-recruiting chemokine (C-C motif) ligand 2 (CCL2) in murine ligature-induced PD using clinically relevant models as a preventive, interventional, or reparative therapy. Local delivery of CCL2 into the periodontium inhibited bone loss and accelerated bone gain that could be ascribed to reduced osteoclasts numbers. CCL2 treatment up-regulated M2-macrophage and downregulated proinflammatory and pro-osteoclastic markers. Furthermore, single-cell ribonucleic acid (RNA) sequencing indicated that CCL2 therapy reversed disease-associated transcriptomic profiles of murine gingival macrophages via inhibiting the triggering receptor expressed on myeloid cells-1 (TREM-1) signaling in classically activated macrophages and inducing protein kinase A (PKA) signaling in infiltrating macrophages. Finally, 16S ribosomal ribonucleic acid (rRNA) sequencing showed mitigation of microbial dysbiosis in the periodontium that correlated with a reduction in microbial load in CCL2-treated mice. This study reveals a novel protective effect of CCL2 local delivery in PD as a model for chronic inflammatory diseases caused by a disturbance in host-microbe homeostasis.

In silico analysis of DEL-1 and inflammation-related genes in lung squamous cell carcinoma

AIM

Twenty to thirty percent of non-small cell lung cancers (NSCLC) are caused by lung squamous cell carcinoma (LUSC), especially in smokers and there has been limited study previously evaluating the situation in terms of the genome and gene expression profile, which demonstrates the relationship among DEL-1, leucocyte recruitment, and pro-inflammatory cytokines in LUSC.

MATERIAL AND METHODS

In the current study, the m-RNA expression patterns and mutation profiles of our target genes, such as, pro-inflammatory cytokines, chemoattractant molecules, and DEL-1 genes, in 511 LUSC patients. To find the harmful mutations, the PolyPhen-2 and SNAP programs were employed. Not only gene expression was detected, but also survival analysis and correlation between DEL-1 and other target genes' expression levels were explored too.

RESULTS

Target genes such as, DEL-1, TNF, IL-18, IL-1, CXCL8, CXCL13, and IL-6 were found to have a total genetic anomaly carrying rate of 16.4%. Seven mutations were found, and two of those mutations have a pathogenic aspect. Deep deletion and gene amplification of the genetic anomalies were also observed. According to gene expression analysis results in the LUSC patient group; DEL-1 and IL-6 levels were significantly lower than those of the control group, whereas the CXCL13 level was found to be higher.

CONCLUSION

Findings of the current study revealed that, there is a significant role of DEL-1 in LUSC pathogenesis. Since present study is an in silico-centered study, this approach can give more insight on experimental studies. These events may support that one of the cancer improvement mechanisms depending on DEL-1 gene at the molecular level.

Developmental endothelial locus 1: the present and future of an endogenous factor in vessels

Developmental Endothelial Locus-1 (DEL-1), also known as EGF-like repeat and discoidin I-like domain-3 (EDIL3), is increasingly recognized for its multifaceted roles in immunoregulation and vascular biology. DEL-1 is a protein that is mainly produced by endothelial cells. It interacts with various integrins to regulate the behavior of immune cells, such as preventing unnecessary recruitment and inflammation. DEL-1 also helps in resolving inflammation by promoting efferocytosis, which is the process of clearing apoptotic cells. Its potential as a therapeutic target in immune-mediated blood disorders, cardiovascular diseases, and cancer metastasis has been spotlighted due to its wide-ranging implications in vascular integrity and pathology. However, there are still unanswered questions about DEL-1's precise functions and mechanisms. This review provides a comprehensive examination of DEL-1's activity across different vascular contexts and explores its potential clinical applications. It underscores the need for further research to resolve existing controversies and establish the therapeutic viability of DEL-1 modulation.

P53 Alleviates the Progression of Periodontitis by Reducing M1-type Macrophage Differentiation

Our objective is to explore the effect of P53 on the progression of periodontitis by regulating macrophages differentiation both in vitro and in vivo. Eighteen normal and periodontitis gingival tissues were collected for detecting P53 expression and macrophages infiltration by immunofluorescence, real-time PCR (qPCR) and western-blot. The differentiation and the inflammatory cytokines (TNF-α and IL-6) expression of THP-1, RAW264.7 and bone marrow derived macrophage (BMDM) cells, treating with Pifithrin-α (P53 inhibitor) or Nutlin-3a (P53 activator) under lipopolysaccharide (LPS) stimulation, were observed by flow cytometry, qPCR and ELISA. The severity of periodontitis, inflammatory cytokines expression and macrophages infiltration were measured in experimental periodontitis wild-type mice and p53 gene conditional knocked-out (p53-CKO) mice, which were established by ligation and LPS injection. A higher number of P53-positive macrophages was found infiltrated in periodontitis tissues. In vitro experiments showed that compared with Nutlin-3a, the proportion of M1-type macrophages and the expression of TNF-α and IL-6 were higher in Pifithrin-α treated cells under LPS stimulation. In vivo experimental periodontitis mice, the Pifithrin-α intraperitoneal injection group showed greater alveolar bone loss, higher levels of TNF-α and IL-6 secretion and more M1-type macrophages infiltration, while the Nutlin-3a intraperitoneal injection group were observed mild symptoms compared with mice in the periodontitis group. P53-CKO mice exhibited more severe periodontitis and more M1-type macrophages infiltrated in local tissues compared with wild-type mice. The activation of p53 gene could alleviate periodontitis by reducing M1-type macrophage polarization. P53 may serve as keeper in the progression of periodontitis, providing new insights into periodontitis treatment.

Nischarin inhibits the epithelial-mesenchymal transition process and angiogenesis in breast cancer cells by inactivating FAK/ERK signaling pathway via EGF like repeats and discoidin domains 3

BACKGROUND

Our previous study has demonstrated that Nischarin (NISCH) exerts its antitumor effects in breast cancer (BC) by suppressing cell migration and invasion. This study aims to explore the underlying mechanism through which NISCH functions in BC.

METHODS AND RESULTS

The relevance between EGF Like Repeats and Discoidin Domains 3 (EDIL3) mRNA expression and the overall survival of tumor patients was depicted by the Kaplan-Meier curve. The findings revealed that overexpressed NISCH attenuated cell motility and colony-forming capacities of Hs578T cells, yet silenced NISCH in MDA-MB-231 cells led to contrasting results. Western blot (WB) analysis indicated that overexpression of NISCH significantly down-regulated the Vimentin and Slug expression, and inactivated the FAK/ERK signaling pathway. RNA sequencing (RNA-seq) was performed in NISCH-overexpressed Hs578T cells and the control cells to analyze differentially expressed genes (DeGs), and the results showed a significant down-regulation of EDIL3 mRNA level upon overexpression of NISCH. Subsequent functional analyses demonstrated that overexpression of EDIL3 attenuated the inhibitory effect of NISCH on cell migration, invasion, colony formation, and tube formation.

CONCLUSION

In summary, our finding preliminarily revealed that NISCH inhibits the epithelial-mesenchymal transition (EMT) process and angiogenesis in BC cells by down-regulating EDIL3 to inactivate the FAK/ERK signaling pathway, thereby suppressing the progression of BC. Our results hold promise for contributing to the deep understanding of BC pathogenesis and identifying new therapeutic strategies for clinical application.

Clonal hematopoiesis driven by mutated DNMT3A promotes inflammatory bone loss

Clonal hematopoiesis of indeterminate potential (CHIP) arises from aging-associated acquired mutations in hematopoietic progenitors, which display clonal expansion and produce phenotypically altered leukocytes. We associated CHIP-DNMT3A mutations with a higher prevalence of periodontitis and gingival inflammation among 4,946 community-dwelling adults. To model DNMT3A-driven CHIP, we used mice with the heterozygous loss-of-function mutation R878H, equivalent to the human hotspot mutation R882H. Partial transplantation with Dnmt3aR878H/+ bone marrow (BM) cells resulted in clonal expansion of mutant cells into both myeloid and lymphoid lineages and an elevated abundance of osteoclast precursors in the BM and osteoclastogenic macrophages in the periphery. DNMT3A-driven clonal hematopoiesis in recipient mice promoted naturally occurring periodontitis and aggravated experimentally induced periodontitis and arthritis, associated with enhanced osteoclastogenesis, IL-17-dependent inflammation and neutrophil responses, and impaired regulatory T cell immunosuppressive activity. DNMT3A-driven clonal hematopoiesis and, subsequently, periodontitis were suppressed by rapamycin treatment. DNMT3A-driven CHIP represents a treatable state of maladaptive hematopoiesis promoting inflammatory bone loss.

Sequential immunotherapy: towards cures for autoimmunity

Despite major progress in the treatment of autoimmune diseases in the past two decades, most therapies do not cure disease and can be associated with increased risk of infection through broad suppression of the immune system. However, advances in understanding the causes of autoimmune disease and clinical data from novel therapeutic modalities such as chimeric antigen receptor T cell therapies provide evidence that it may be possible to re-establish immune homeostasis and, potentially, prolong remission or even cure autoimmune diseases. Here, we propose a 'sequential immunotherapy' framework for immune system modulation to help achieve this ambitious goal. This framework encompasses three steps: controlling inflammation; resetting the immune system through elimination of pathogenic immune memory cells; and promoting and maintaining immune homeostasis via immune regulatory agents and tissue repair. We discuss existing drugs and those in development for each of the three steps. We also highlight the importance of causal human biology in identifying and prioritizing novel immunotherapeutic strategies as well as informing their application in specific patient subsets, enabling precision medicine approaches that have the potential to transform clinical care.

Stiffness sensing via Piezo1 enhances macrophage efferocytosis and promotes the resolution of liver fibrosis

Tissue stiffening is a predominant feature of fibrotic disorders, but the response of macrophages to changes in tissue stiffness and cellular context in fibrotic diseases remains unclear. Here, we found that the mechanosensitive ion channel Piezo1 was up-regulated in hepatic fibrosis. Macrophages lacking Piezo1 showed sustained inflammation and impaired spontaneous resolution of early liver fibrosis. Further analysis revealed an impairment of clearance of apoptotic cells by macrophages in the fibrotic liver. Macrophages showed enhanced efferocytosis when cultured on rigid substrates but not soft ones, suggesting stiffness-dependent efferocytosis of macrophages required Piezo1 activation. Besides, Piezo1 was involved in the efficient acidification of the engulfed cargo in the phagolysosomes and affected the subsequent expression of anti-inflammation genes after efferocytosis. Pharmacological activation of Piezo1 increased the efferocytosis capacity of macrophages and accelerated the resolution of inflammation and fibrosis. Our study supports the antifibrotic role of Piezo1-mediated mechanical sensation in liver fibrosis, suggesting that targeting PIEZO1 to enhance macrophage efferocytosis could induce fibrosis regression.

CX3CR1 deficiency promotes resolution of hepatic ischemia-reperfusion injury by regulating homeostatic function of liver infiltrating macrophages

Hepatic ischemia-reperfusion injury(HIRI) remains to be an unsolved risk factor that contributes to organ failure after liver surgery. Our clinical retrospective study showed that lower donor liver CX3-C chemokine receptor-1(CX3CR1) mRNA expression level were correlated with upregulated pro-resolved macrophage receptor MERTK, as well as promoted restoration efficiency of allograft injury in liver transplant. To further characterize roles of CX3CR1 in regulating resolution of HIRI, we employed murine liver partial warm ischemia-reperfusion model by Wt & Cx3cr1-/- mice and the reperfusion time was prolonged from 6 h to 4-7 days. Kupffer cells(KCs) were depleted by clodronate liposome(CL) in advance to focus on infiltrating macrophages, and repopulation kinetics were determined by FACS, IF and RNA-Seq. CX3CR1 antagonist AZD8797 was injected i.p. to interrogate potential pharmacological therapeutic strategies. In vitro primary bone marrow macrophages(BMMs) culture by LXR agonist DMHCA, as well as molecular and functional studies, were undertaken to dissect roles of CX3CR1 in modulating macrophages cytobiological development and resolutive functions. We observed that deficiency or pharmacological inhibition of CX3CR1 facilitated HIRI resolution via promoted macrophages migration in CCR1/CCR5 manner, as well as enhanced MerTK-mediated efferocytosis. Our study demonstrated the critical roles of CX3CR1 in progression of HIRI and identified it as a potential therapeutic target in clinical liver transplantation.

Dipotassium glycyrrhizate and hinokitiol enhance macrophage efferocytosis by regulating recognition, uptake, and metabolism of apoptotic cells in vitro

BACKGROUND AND OBJECTIVE

Efferocytosis is a process whereby macrophages remove apoptotic cells, such as neutrophils, that have accumulated in tissues, which is required for resolution of inflammation. Efferocytosis is impaired in individuals with increasing age and in those with various systemic diseases. Recently, efferocytosis has been reported to be related to the pathogenesis and progression of periodontitis, and enhancement of efferocytosis, especially in the subjects with impaired efferocytosis, was suggested to lead to periodontitis prevention and care. Various anti-inflammatory ingredients are used in oral care products, but their effect on efferocytosis is unclear. Here, we aimed to identify ingredients contained in oral care products that are effective for efferocytosis regulation.

METHODS

The ability of dead cells to induce inflammation in human gingival fibroblast (HGF) cells were evaluated by measuring IL-6 secretion. Six ingredients in oral care products used as anti-inflammatory agents were evaluated for their effect on efferocytosis using flow cytometry. The expression of various efferocytosis-related molecules, such as MERTK and LRP1 involved in recognition, and LXRα and ABCA1 that function in metabolism, were measured in RAW264.7 cells with or without ingredient treatment. Rac1 activity, which is related to the uptake of dead cells, was measured using the G-LISA kit.

RESULTS

Dead cells elicited IL-6 secretion in HGF cells. Among the six ingredients, GK2 and hinokitiol enhanced efferocytosis activity. GK2 and hinokitiol significantly increased the expression of MERTK and LRP1, and also enhanced LXRα and ABCA1 expression after efferocytosis. Furthermore, they increased Rac1 activity in the presence of dead cells.

CONCLUSION

Among the six ingredients tested, GK2 and hinokitiol promoted efferocytosis by regulating apoptotic cell recognition, uptake, and metabolism-related molecules. Efferocytosis upregulation may be one of the mechanisms of GK2 and hinokitiol in the treatment of inflammatory diseases, such as periodontitis.

Diagnostic and predictive abilities of myokines in patients with heart failure

Myokines are defined as a heterogenic group of numerous cytokines, peptides and metabolic derivates, which are expressed, synthesized, produced, and released by skeletal myocytes and myocardial cells and exert either auto- and paracrine, or endocrine effects. Previous studies revealed that myokines play a pivotal role in mutual communications between skeletal muscles, myocardium and remote organs, such as brain, vasculature, bone, liver, pancreas, white adipose tissue, gut, and skin. Despite several myokines exert complete divorced biological effects mainly in regulation of skeletal muscle hypertrophy, residential cells differentiation, neovascularization/angiogenesis, vascular integrity, endothelial function, inflammation and apoptosis/necrosis, attenuating ischemia/hypoxia and tissue protection, tumor growth and malignance, for other occasions, their predominant effects affect energy homeostasis, glucose and lipid metabolism, adiposity, muscle training adaptation and food behavior. Last decade had been identified 250 more myokines, which have been investigating for many years further as either biomarkers or targets for heart failure management. However, only few myokines have been allocated to a promising tool for monitoring adverse cardiac remodeling, ischemia/hypoxia-related target-organ dysfunction, microvascular inflammation, sarcopenia/myopathy and prediction for poor clinical outcomes among patients with HF. This we concentrate on some most plausible myokines, such as myostatin, myonectin, brain-derived neurotrophic factor, muslin, fibroblast growth factor 21, irisin, leukemia inhibitory factor, developmental endothelial locus-1, interleukin-6, nerve growth factor and insulin-like growth factor-1, which are suggested to be useful biomarkers for HF development and progression.

Efferocytosis in dendritic cells: an overlooked immunoregulatory process

Efferocytosis, the process of engulfing and removing apoptotic cells, plays an essential role in preserving tissue health and averting undue inflammation. While macrophages are primarily known for this task, dendritic cells (DCs) also play a significant role. This review delves into the unique contributions of various DC subsets to efferocytosis, highlighting the distinctions in how DCs and macrophages recognize and handle apoptotic cells. It further explores how efferocytosis influences DC maturation, thereby affecting immune tolerance. This underscores the pivotal role of DCs in orchestrating immune responses and sustaining immune equilibrium, providing new insights into their function in immune regulation.

[Strong as death or how efferocytotic macrophages promote the resolution of inflammation]

The resolution of inflammation is an active process leading to the restoration of tissue homeostasis. A critical step in the initiation of this process is the elimination of apoptotic immune cells by macrophages. This well-organized process, called efferocytosis, involves four different steps, namely the attraction of macrophages to the site where the cells die, the recognition of apoptotic cells, their internalization and their digestion leading to the activation of different metabolic pathways. All these steps are responsible for the reprogramming of macrophages towards a pro-resolving profile. Efferocytic macrophages produce several factors involved in the resolution of inflammation. These factors include lipids (i.e., specialized pro-resolving mediators such as lipoxins), and proteins (e.g., IL-10 or TGF-β). Here, we describe the different steps of efferocytosis and the mechanisms responsible for both macrophage reprogramming and the release of pro-resolving factors. These factors may represent a new therapeutic approach, called resolution therapy.

The Role of Macrophage Death in Periodontitis: A Review

Periodontitis, an infectious inflammatory disease influenced by various factors, disrupts the delicate balance between the host microbiota and immunity. The resulting excessive immune response exacerbates the progressive destruction of the supporting periodontal tissue. Macrophages are essential elements of the host innate immune system. They are pivotal components in the periodontal immune microenvironment and actively participate in both physiological and pathological processes of periodontal tissue. When confronted with periodontitis-related irritant factors, macrophages may differentiate to pro- or anti-inflammatory subtypes that affect tissue homeostasis. Additionally, macrophages may die in response to bacterial infections, potentially affecting the severity of periodontitis. This article reviews the typical mechanisms underlying macrophage death and its effects on periodontitis. We describe five forms of macrophage death in periodontitis: apoptosis, pyroptosis, necroptosis, ferroptosis, and ETosis. Our review of macrophage death in the pathophysiology of periodontitis enhances comprehension of the pathogenesis of periodontitis that will be useful for clinical practice. Although our review elucidates the complex mechanisms by which macrophage death and inflammatory pathways perpetuate periodontitis, unresolved issues remain, necessitating further research.

Transcriptomic features of programmed and inflammatory cell death in gingival tissues

The local gingival tissue environment with homeostasis and tissue-destructive events of periodontitis demonstrates major changes in histological features and biology of the oral/sulcular epithelium, fibroblasts, vascular cells, inflammatory cell infiltration, and alveolar bone.

OBJECTIVE

This study used an experimental periodontitis model to detail the gingival transcriptome related to cell death processes of pyroptosis, necroptosis, ferroptosis, and cuproptosis.

MATERIALS AND METHODS

Healthy Macaca mulatta primates stratified by age, ≤3 years (young), 7-12 years (adolescent), 12-15 years (adult), and 17-23 years (aged), provided gingival tissue biopsies for microarray analysis focused on 257 genes representative of the four cell death processes and bacterial plaque samples for 16S rRNA gene analysis.

RESULTS

Age differences in the profiles of gene expression in healthy tissues were noted for cuproptosis, ferroptosis, necroptosis, and pyroptosis. Major differences were then observed with disease initiation, progression, and resolution also related to the age of the animals. Distinct bacterial families/consortia of species were significantly related to the gene expression differences for the cell death pathways.

CONCLUSIONS

These results emphasized age-associated differences in the gingival tissue molecular response to changes in the quality and quantity of bacteria accumulating with the disease process reflected in regulated cell death pathways that are both physiological and pathophysiological.

Targeting SLC22A5 fosters mitophagy inhibition-mediated macrophage immunity against septic acute kidney injury upon CD47-SIRPα axis blockade

Efferocytosis of apoptotic neutrophils (PMNs) by macrophages is helpful for inflammation resolution and injury repair, but the role of efferocytosis in intrinsic nature of macrophages during septic acute kidney injury (AKI) remains unknown. Here we report that CD47 and signal regulatory protein alpha (SIRPα)-the anti-efferocytotic 'don't eat me' signals-are highly expressed in peripheral blood mononuclear cells (PBMCs) from patients with septic AKI and kidney samples from mice with polymicrobial sepsis and endotoxin shock. Conditional knockout (CKO) of SIRPA in macrophages ameliorates AKI and systemic inflammation response in septic mice, accompanied by an escalation in mitophagy inhibition of macrophages. Ablation of SIRPA transcriptionally downregulates solute carrier family 22 member 5 (SLC22A5) in the lipopolysaccharide (LPS)-stimulated macrophages that efferocytose apoptotic neutrophils (PMNs). Targeting SLC22A5 renders mitophagy inhibition of macrophages in response to LPS stimuli, improves survival and deters development of septic AKI. Our study supports further clinical investigation of CD47-SIRPα signalling in sepsis and proposes that SLC22A5 might be a promising immunotherapeutic target for septic AKI.

Harnessing anti-inflammatory pathways and macrophage nano delivery to treat inflammatory and fibrotic disorders

Targeting specific organs and cell types using nanotechnology and sophisticated delivery methods has been at the forefront of applicative biomedical sciences lately. Macrophages are an appealing target for immunomodulation by nanodelivery as they are heavily involved in various aspects of many diseases and are highly plastic in their nature. Their continuum of functional "polarization" states has been a research focus for many years yielding a profound understanding of various aspects of these cells. The ability of monocyte-derived macrophages to metamorphose from pro-inflammatory to reparative and consequently to pro-resolving effectors has raised significant interest in its therapeutic potential. Here, we briefly survey macrophages' ontogeny and various polarization phenotypes, highlighting their function in the inflammation-resolution shift. We review their inducing mediators, signaling pathways, and biological programs with emphasis on the nucleic acid sensing-IFN-I axis. We also portray the polarization spectrum of macrophages and the characteristics of their transition between different subtypes. Finally, we highlighted different current drug delivery methods for targeting macrophages with emphasis on nanotargeting that might lead to breakthroughs in the treatment of wound healing, bone regeneration, autoimmune, and fibrotic diseases.

Developmental endothelial locus-1 promotes osteogenic differentiation and alveolar bone regeneration in experimental periodontitis with type 2 diabetes mellitus

OBJECTIVES

This study sought to explore the role of developmental endothelial locus-1 (DEL-1) in osteogenic differentiation of human periodontal ligament stem cells (hPDLSCs) and investigate the therapeutic effect of DEL-1 in ligature-induced experimental periodontitis with type 2 diabetes mellitus (T2DM).

BACKGROUND

T2DM is a significant risk factor for periodontitis. Treatment modalities for periodontitis with T2DM are being explored. DEL-1 is a versatile protein that can modulate the different stages of inflammatory diseases including periodontitis. The direct effect of DEL-1 on osteogenic differentiation of PDLSCs in periodontitis with T2DM is poorly understood.

METHODS

Primary hPDLSCs were isolated from periodontal ligament tissue and identified by flow cytometry. In osteogenesis experiments, alkaline phosphatase (ALP), Alizarin Red staining and western blot were used to assess the osteogenic effect of DEL-1 on hPDLSCs in high glucose and inflammation environments. The mouse model of ligature-induced experimental periodontitis was established. H&E and Masson's trichrome staining were used to assess the change of periodontal tissue after local periodontal injection of DEL-1. Immunohistochemical staining was used to evaluate osteogenic-related protein expression.

RESULTS

hPDLSCs expressed mesenchymal stem cell (MSC)-specific surface markers and were negative for hematopoietic cell surface markers. hPDLSCs had the potential for multidirectional differentiation. DEL-1 could enhance the osteogenic differentiation of hPDLSCs in high glucose and inflammation environments, although it did not return to the control level. Histological staining showed that DEL-1 contributed to alveolar bone regeneration and osteogenic-related protein expression, but the degree of improvement in T2DM mice was lower than in non-T2DM mice.

CONCLUSIONS

In summary, we demonstrated that DEL-1 could promote osteogenic differentiation of hPDLSCs in high glucose and inflammation environment and rescue alveolar bone loss in experimental periodontitis with T2DM, which could provide a novel therapeutic target for periodontitis with T2DM.

Indoleamine 2, 3-dioxygenase 1 activation in macrophage exacerbates hepatic ischemia-reperfusion injury by triggering hepatocyte ferroptosis

BACKGROUND

Hepatic Ischemia-reperfusion (I/R) injury, critical challenge in liver surgery and transplantation, exerts a significant impact on the prognosis and survival of patients. Inflammation and cell death play pivotal roles in pathogenesis of hepatic I/R injury. Indoleamine 2, 3-dioxygenase 1 (IDO-1), a key enzyme involved in the kynurenine pathway, has been extensively investigated for its regulatory effects on innate immune responses and cell ferroptosis. However, the precise involvement of IDO-1 in hepatic I/R injury remains unclear.

METHODS

IDO-1 knockout mice were generated to establish a murine model of liver partial warm ischemia and reperfusion, while an in vitro Hypoxia/Reoxygenation (H/R) model was employed to simulate ischemia/reperfusion injury.

RESULTS

The involvement of ferroptosis was observed to be involved in hepatic I/R injury, and effective mitigation of liver injury was achieved through the inhibition of ferroptosis. In the context of hepatic I/R injury, up-regulation of IDO-1 was found in macrophages exhibiting prominent M1 polarization and impaired efferocytosis. Deficiency or inhibition of IDO-1 alleviated hepatocytes ferroptosis and M1 polarization induced by hepatic I/R injury, while also enhancing M2 polarization and promoting efferocytosis in macrophages. Furthermore, depletion of macrophages attenuated ferroptosis in hepatocytes induced by hepatic I/R injury.

CONCLUSION

This study highlights the crucial role of IDO-1 activation in macrophages in triggering ferroptosis in hepatocytes during hepatic ischemia-reperfusion injury. Our findings suggest that targeting IDO-1 could be a promising therapeutic strategy for mitigating hepatic I/R injury associated with liver surgery and transplantation.

The Role of Macrophage Efferocytosis in the Pathogenesis of Apical Periodontitis

Macrophages (Mφs) play a crucial role in the homeostasis of the periapical immune micro-environment caused by bacterial infection. Mφ efferocytosis has been demonstrated to promote the resolution of multiple infected diseases via accelerating Mφ polarization into M2 type. However, the Mφ efferocytosis-apical periodontitis (AP) relationship has not been elucidated yet. This study aimed to explore the role of Mφ efferocytosis in the pathogenesis of AP. Clinical specimens were collected to determine the involvement of Mφ efferocytosis in the periapical region via immunohistochemical and immunofluorescence staining. For a further understanding of the moderator effect of Mφ efferocytosis in the pathogenesis of AP, both an in vitro AP model and in vivo AP model were treated with ARA290, a Mφ efferocytosis agonist. Histological staining, micro-ct, flow cytometry, RT-PCR and Western blot analysis were performed to detect the inflammatory status, alveolar bone loss and related markers in AP models. The data showed that Mφ efferocytosis is observed in the periapical tissues and enhancing the Mφ efferocytosis ability could effectively promote AP resolution via facilitating M2 Mφ polarization. Collectively, our study demonstrates the functional importance of Mφ efferocytosis in AP pathology and highlights that accelerating Mφ efferocytosis via ARA290 could serve as an adjuvant therapeutic strategy for AP.

The neutrophil-osteogenic cell axis promotes bone destruction in periodontitis

The immune-stromal cell interactions play a key role in health and diseases. In periodontitis, the most prevalent infectious disease in humans, immune cells accumulate in the oral mucosa and promote bone destruction by inducing receptor activator of nuclear factor-κB ligand (RANKL) expression in osteogenic cells such as osteoblasts and periodontal ligament cells. However, the detailed mechanism underlying immune-bone cell interactions in periodontitis is not fully understood. Here, we performed single-cell RNA-sequencing analysis on mouse periodontal lesions and showed that neutrophil-osteogenic cell crosstalk is involved in periodontitis-induced bone loss. The periodontal lesions displayed marked infiltration of neutrophils, and in silico analyses suggested that the neutrophils interacted with osteogenic cells through cytokine production. Among the cytokines expressed in the periodontal neutrophils, oncostatin M (OSM) potently induced RANKL expression in the primary osteoblasts, and deletion of the OSM receptor in osteogenic cells significantly ameliorated periodontitis-induced bone loss. Epigenomic data analyses identified the OSM-regulated RANKL enhancer region in osteogenic cells, and mice lacking this enhancer showed decreased periodontal bone loss while maintaining physiological bone metabolism. These findings shed light on the role of neutrophils in bone regulation during bacterial infection, highlighting the novel mechanism underlying osteoimmune crosstalk.

A novel macrolide-Del-1 axis to regenerate bone in old age

Aging is associated with increased susceptibility to chronic inflammatory bone loss disorders, such as periodontitis, in large part due to the impaired regenerative potential of aging tissues. DEL-1 exerts osteogenic activity and promotes bone regeneration. However, DEL-1 expression declines with age. Here we show that systemically administered macrolide antibiotics and a non-antibiotic erythromycin derivative, EM-523, restore DEL-1 expression in 18-month-old ("aged") mice while promoting regeneration of bone lost due to naturally occurring age-related periodontitis. These compounds failed to induce bone regeneration in age-matched DEL-1-deficient mice. Consequently, these drugs promoted DEL-1-dependent functions, including alkaline phosphatase activity and osteogenic gene expression in the periodontal tissue while inhibiting osteoclastogenesis, leading to net bone growth. Macrolide-treated aged mice exhibited increased skeletal bone mass, suggesting that this treatment may be pertinent to systemic bone loss disorders. In conclusion, we identified a macrolide-DEL-1 axis that can regenerate bone lost due to aging-related disease.

Del-1 Plays a Protective Role against COPD Development by Inhibiting Inflammation and Apoptosis

Neutrophilic inflammation is a prominent feature of chronic obstructive pulmonary disease (COPD). Developmental endothelial locus-1 (Del-1) has been reported to limit excessive neutrophilic inflammation by inhibiting neutrophil adhesion to the vascular endothelial cells. However, the effects of Del-1 in COPD are not known. We investigated the role of Del-1 in the pathogenesis of COPD. Del-1 protein expression was decreased in the lungs of COPD patients, especially in epithelial cells and alveolar macrophages. In contrast to human lung tissue, Del-1 expression was upregulated in lung tissue from mice treated with cigarette smoke extracts (CSE). Overexpression of Del-1 significantly suppressed IL-8 release and apoptosis in CSE-treated epithelial cells. In contrast, knockdown of Del-1 enhanced IL-8 release and apoptosis. In macrophages, overexpression of Del-1 significantly suppressed inflammatory cytokine release, and knockdown of Del-1 enhanced it. This anti-inflammatory effect was mediated by inhibiting the phosphorylation and acetylation of NF-κB p65. Nuclear factor erythroid 2-related factor 2 (Nrf2) activators, such as quercetin, resveratrol, and sulforaphane, increased Del-1 in both cell types. These results suggest that Del-1, mediated by Nrf2, plays a protective role against the pathogenesis of COPD, at least in part through anti-inflammatory and anti-apoptotic effects.

An IL-10/DEL-1 axis supports granulopoiesis and survival from sepsis in early life

The limited reserves of neutrophils are implicated in the susceptibility to infection in neonates, however the regulation of neutrophil kinetics in infections in early life remains poorly understood. Here we show that the developmental endothelial locus (DEL-1) is elevated in neonates and is critical for survival from neonatal polymicrobial sepsis, by supporting emergency granulopoiesis. Septic DEL-1 deficient neonate mice display low numbers of myeloid-biased multipotent and granulocyte-macrophage progenitors in the bone marrow, resulting in neutropenia, exaggerated bacteremia, and increased mortality; defects that are rescued by DEL-1 administration. A high IL-10/IL-17A ratio, observed in newborn sepsis, sustains tissue DEL-1 expression, as IL-10 upregulates while IL-17 downregulates DEL-1. Consistently, serum DEL-1 and blood neutrophils are elevated in septic adult and neonate patients with high serum IL-10/IL-17A ratio, and mortality is lower in septic patients with high serum DEL-1. Therefore, IL-10/DEL-1 axis supports emergency granulopoiesis, prevents neutropenia and promotes sepsis survival in early life.

Restoring periodontal tissue homoeostasis prevents cognitive decline by reducing the number of Serpina3nhigh astrocytes in the hippocampus

Cognitive decline has been linked to periodontitis through an undetermined pathophysiological mechanism. This study aimed to explore the mechanism underlying periodontitis-related cognitive decline and identify therapeutic strategies for this condition. Using single-nucleus RNA sequencing we found that changes in astrocyte number, gene expression, and cell‒cell communication were associated with cognitive decline in mice with periodontitis. In addition, activation of the NOD-like receptor family pyrin domain containing 3 (NLRP3) inflammasome was observed to decrease the phagocytic capability of macrophages and reprogram macrophages to a more proinflammatory state in the gingiva, thus aggravating periodontitis. To further investigate this finding, lipid-based nanoparticles carrying NLRP3 siRNA (NPsiNLRP3) were used to inhibit overactivation of the NLRP3 inflammasome in gingival macrophages, restoring the oral microbiome and reducing periodontal inflammation. Furthermore, gingival injection of NPsiNLRP3 reduced the number of Serpina3nhigh astrocytes in the hippocampus and prevented cognitive decline. This study provides a functional basis for the mechanism by which the destruction of periodontal tissues can worsen cognitive decline and identifies nanoparticle-mediated restoration of gingival macrophage function as a novel treatment for periodontitis-related cognitive decline.

The role of secreted proteins in efferocytosis

The clearance of apoptotic cells known as efferocytosis is the final stage of apoptosis, and includes the recognition, phagocytosis, and degradation of apoptotic cells. The maintenance of tissue homeostasis requires the daily elimination of billions of apoptotic cells from the human body via the process of efferocytosis. Accordingly, aberrations in efferocytosis underlie a growing list of diseases, including atherosclerosis, cancer, and infections. During the initial phase of apoptosis, "Eat-Me" signals are exposed and recognized by phagocytes either directly through phagocyte receptors or indirectly through secreted proteins that function as bridge molecules that cross-link dying cells to phagocytes. Here, we set out to provide a comprehensive review of the molecular mechanisms and biological significance of secreted proteins in apoptotic cell clearance. Specifically, it focuses on how these secreted proteins act as bridging molecules to facilitate the clearance process.

Mechanism of pro-MMP9 activation in co-culture of pro-inflammatory macrophages and cardiomyocytes

OBJECTIVE

A wide range of cardiac diseases is associated with inflammation. "Inflamed" heart tissue is infiltrated with pro-inflammatory macrophages which extensively secrete matrix metalloproteinase 9 (MMP9), a regulator of extracellular matrix turnover. As MMP9 is released from macrophages in a latent form, it requires activation. The present study addresses the role of cardiomyocytes in the course of this activation process.

METHODS AND RESULTS

In mono- and co-cultures of pro-inflammatory rat macrophages (bone marrow-derived and peritoneal) and cardiomyocytes (H9C2 cell line) gelatin zymography demonstrated that activated macrophages robustly secreted latent pro-MMP9, whereas cardiomyocytes could not produce the enzyme. Co-culturing of the two cell species was critical for pro-MMP9 activation and was also accompanied by processing of cardiomyocyte-secreted pro-MMP2. A cascade of pro-MMP9 activation was initiated on macrophage membrane with pro-MMP2 cleavage. Namely, pro-inflammatory macrophages expressed an active membrane type 1 MMP (MT1MMP), which activated pro-MMP2, which in turn converted pro-MMP9. Downregulation of MT1MMP in macrophages by siRNA abolished activation of both pro-MMP2 and pro-MMP9 in co-culture. In addition, both cell species secreted MMP13 as a further pro-MMP9 activator. In co-culture, activation of pro-MMP13 occurred on membranes of macrophages and was enhanced in presence of active MMP2. Using incubations with recombinant MMPs and isolated macrophage membranes, we demonstrated that while both MMP2 and MMP13 individually had the ability to activate pro-MMP9, their combined action provided a synergistic effect.

CONCLUSION

Activation of pro-MMP9 in a co-culture of pro-inflammatory macrophages and cardiomyocytes was the result of a complex interaction of several MMPs on the cell membrane and in the extracellular space. Both cell types contributed critically to pro-MMP9 processing.

Amelioration of experimental autoimmune encephalomyelitis by in vivo reprogramming of macrophages using pro-resolving factors

BACKGROUND

Reinstating inflammation resolution represents an innovative concept to regain inflammation control in diseases marked by chronic inflammation. While most therapeutics target inflammatory molecules and inflammatory effector cells and mediators, targeting macrophages to initiate inflammation resolution to control neuroinflammation has not yet been attempted. Resolution-phase macrophages are critical in the resolution process to regain tissue homeostasis, and are programmed through the presence and elimination of apoptotic leukocytes. Hence, inducing resolution-phase macrophages might represent an innovative therapeutic approach to control and terminate dysregulated neuroinflammation.

METHODS

Here, we investigated if the factors released by in vitro induced resolution-phase macrophages (their secretome) are able to therapeutically reprogram macrophages to control neuroinflammation in the model of experimental autoimmune encephalomyelitis (EAE).

RESULTS

We found that injection of the pro-resolutive secretome reduced demyelination and decreased inflammatory cell infiltration in the CNS, notably through the in vivo reprogramming of macrophages at the epigenetic level. Adoptive transfer experiments with in vivo or in vitro reprogrammed macrophages using such pro-resolutive secretome confirmed the stability and transferability of this acquired therapeutic activity.

CONCLUSIONS

Overall, our data confirm the therapeutic activity of a pro-resolution secretome in the treatment of ongoing CNS inflammation, via the epigenetic reprogramming of macrophages and open with that a new therapeutic avenue for diseases marked by neuroinflammation.

Effects of neutrophil fate on inflammation

INTRODUCTION

Neutrophils are important participants in the innate immune response. They rapidly and efficiently identify and clear infectious agents by expressing large numbers of membrane receptors. Upon tissue injury or pathogen invasion, neutrophils are the first immune cells to reach the site of injury and participate in the inflammatory response.

MATERIALS AND METHODS

A thorough search on PubMed related to neutrophil death or clearance pathways was performed.

CONCLUSION

Inflammatory response and tissue damage can be aggravated when neutrophils are not removed rapidly from the site of injury. Recent studies have shown that neutrophils can be cleared through a variety of pathways, including non-inflammatory and inflammatory death, as well as reverse migration. Non-inflammatory death pathways include apoptosis and autophagy. Inflammatory death pathways include necroptosis, pyroptosis and NETosis. This review highlights the basic properties of neutrophils and the impact of their clearance pathways on the inflammatory response.

Construction of inflammatory associated risk gene prognostic model of NSCLC and its correlation with chemotherapy sensitivity

BACKGROUND

Inflammation is an important pathogenic factor of most malignant tumors. It is essential to understand mechanism underlying inflammation and cancer development, so as to formulate and develop anti-cancer treatment strategies. However, inflammatory-related gene characterization as well as risk model construction in prognosis and response chemotherapy or immunotherapy in NSCLC are still remain unclear.

METHODS

A total of 1014 lung cancer samples with RNA-seqencing results were download from The Cancer Genome Atlas (TCGA) database. The patient cohort was randomized as a training and test cohorts, and 200 inflammatory-related genes were selected based on previously published data. Consensus clustering and Enrichment and immune function analyses base on Differential expression genes (DEGs) were performed. Prognosis Prediction Model were Constructed and Chemotherapy and immunotherapy sensitivity base on this model were performed. At last, H1299 and HCC827 cells were used to tested the mitoxantrone and oxal iplatin sensitivity after KRT6A knockdown.

RESULTS

We identified the inflammatory-related genes from NSCLC datasets to build one prognosis prediction signature based on cluster inflammatory-related genes to lay a certain foundation for distinguishing high-risk NSCLC cases with dismal prognostic outcome. The nomogram provides the AUC values for 1-, 3-, and 5-year overall survival were 0.831, 0.853, and 0.86 in validation cohort. Morover, different sensitivity of immunotherapy or chemotherapy also were classified base on the different risk groups in NSCLC patients, which provided potent clinical reference. At last, targeting KRT6A sensitive to mitoxantrone and oxaliplatin in H1299 and HCC827 cells.

CONCLUSIONS

Inflammatory-related gene risk-score is the potential chemotherapeutic and immunotherapeutic biomarker for NSCLC, and targeting KRT6A sensitive to mitoxantrone and oxaliplatin in NSCLC.HighlightsInflammatory-related genes can lay a certain foundation for distinguishing high-risk NSCLC cases with dismal prognostic outcome.Risk-score base on inflammatory-related genes is positive correlated with CD274, TGFBR1 and TGFB1 expression.Targeting KRT6A sensitive to mitoxantrone and oxaliplatin in H1299 and HCC827 cells.

Macrophage phenotypes and functions: resolving inflammation and restoring homeostasis

Inflammation must be tightly regulated to both defend against pathogens and restore tissue homeostasis. The resolution of inflammatory responses is a dynamic process orchestrated by cells of the immune system. Macrophages, tissue-resident innate immune cells, are key players in modulating inflammation. Here, we review recent work highlighting the importance of macrophages in tissue resolution and the return to homeostasis. We propose that enhancing macrophage pro-resolution functions represents a novel and widely applicable therapeutic strategy to dampen inflammation, promote repair, and restore tissue integrity and function.

DEL-1 deficiency aggravates pressure overload-induced heart failure by promoting neutrophil infiltration and neutrophil extracellular traps formation

Recent studies have shown that neutrophils play an important role in the development and progression of heart failure. Developmental endothelial locus-1 (DEL-1) is an anti-inflammatory glycoprotein that has been found to have protective effects in various cardiovascular diseases. However, the role of DEL-1 in chronic heart failure is not well understood. In a mouse model of pressure overload-induced non-ischemic cardiac failure, we found that neutrophil infiltration in the heart increased and DEL-1 levels decreased in the early stages of heart failure. DEL-1 deficiency worsened pressure overload-induced cardiac dysfunction and remodeling in mice. Mechanistically, DEL-1 deficiency promotes neutrophil infiltration and the formation of neutrophil extracellular traps (NETs) through the regulation of P38 signaling. In vitro experiments showed that DEL-1 can inhibit P38 signaling and NETs formation in mouse neutrophils in a MAC-1-dependent manner. Depleting neutrophils, inhibiting NETs formation, and inhibiting P38 signaling all reduced the exacerbation of heart failure caused by DEL-1 deletion. Overall, our findings suggest that DEL-1 deficiency worsens pressure overload-induced heart failure by promoting neutrophil infiltration and NETs formation.

Extracellular vesicles modulate key signalling pathways in refractory wound healing

Chronic wounds are wounds that cannot heal properly due to various factors, such as underlying diseases, infection or reinjury, and improper healing of skin wounds and ulcers can cause a serious economic burden. Numerous studies have shown that extracellular vesicles (EVs) derived from stem/progenitor cells promote wound healing, reduce scar formation and have significant advantages over traditional treatment methods. EVs are membranous particles that carry various bioactive molecules from their cellular origins, such as cytokines, nucleic acids, enzymes, lipids and proteins. EVs can mediate cell-to-cell communication and modulate various physiological processes, such as cell differentiation, angiogenesis, immune response and tissue remodelling. In this review, we summarize the recent advances in EV-based wound healing, focusing on the signalling pathways that are regulated by EVs and their cargos. We discuss how EVs derived from different types of stem/progenitor cells can promote wound healing and reduce scar formation by modulating the Wnt/β-catenin, phosphoinositide 3-kinase/protein kinase B/mammalian target of rapamycin, vascular endothelial growth factor, transforming growth factor β and JAK-STAT pathways. Moreover, we also highlight the challenges and opportunities for engineering or modifying EVs to enhance their efficacy and specificity for wound healing.

Efferocytosis and Respiratory Disease

Cells are the smallest units that make up living organisms, which constantly undergo the processes of proliferation, differentiation, senescence and death. Dead cells need to be removed in time to maintain the homeostasis of the organism and keep it healthy. This process is called efferocytosis. If the process fails, this may cause different types of diseases. More and more evidence suggests that a faulty efferocytosis process is closely related to the pathological processes of respiratory diseases. In this review, we will first introduce the process and the related mechanisms of efferocytosis of the macrophage. Secondly, we will propose some methods that can regulate the function of efferocytosis at different stages of the process. Next, we will discuss the role of efferocytosis in different lung diseases and the related treatment approaches. Finally, we will summarize the drugs that have been applied in clinical practice that can act upon efferocytosis, in order to provide new ideas for the treatment of lung diseases.

Macrophages polarize to the pro-inflammatory phenotype and delay neutrophil efferocytosis to augment Aggregatibacter actinomycetemcomitance JP2 clearance

OBJECTIVE

The study examines how neutrophils cross-talk with macrophages during JP2 Aggregatibacter actinomycetemcomitance infection and factors that are involved in inflammatory resolution and efferocytosis.

BACKGROUND

Although sub-gingival bacteria constitute the primary initiating factor in the pathogenesis of molar-incisor pattern periodontitis (MIPP), the non-resolved host response has a major role in tissue destruction. While evidence links neutrophils to MIPP pathogenesis, their clearance during inflammatory resolution, governed by macrophages, is poorly understood.

METHODS

Human neutrophils (differentiated from HL60 cells) and macrophages (differentiated from THP1 cells) were inoculated with JP2. The supernatants were collected and exposed to naïve neutrophils or macrophages with or without exposure to JP2. Reactive oxygen species (ROS) were measured with 2'-7'-dichlorofluorescein-diacetate and a fluorescent plate reader. Immunofluorescence labeling of CD47 and cell vitality were examined using flow cytometry. Macrophage polarization was tested by immunofluorescence staining for CD163 and CD68 and a fluorescent microscope, and TNFα and IL-10 secretion was tested using ELISA and RT-PCR. Efferocytosis was examined by pHrodo and carboxyfluorescein succinimidyl ester staining and fluorescent microscopy. In vivo, macrophages were depleted from C57Bl/6 mice and neutrophil CD47 levels were tested using the subcutaneous chamber model.

RESULTS

Neutrophils exposed to macrophage supernatant show increased ROS, mainly extracellularly, that increased during JP2 infection. Macrophages showed pro-inflammatory M1 phenotype polarization during JP2 infection, and their supernatants prolonged neutrophil survival by inhibiting CD47 down-expression and reducing neutrophil necrosis and apoptosis. Also, the macrophages delay neutrophil efferocytosis during JP2 infection which, in turn, enhanced JP2 clearance. Depletion of macrophages in mice mildly prevented neutrophils CD47 reduction and reduced JP2 clearance. The JP2 infection in mice also led to macrophage M1 polarization similar to the in vitro results.

CONCLUSIONS

As shown in this study, neutrophil efferocytosis potentially may be reduced during JP2 infection, promoting JP2 clearance, which may contribute to the inflammatory-mediated periodontal tissue damage.

Advances of nanotechnology for intracerebral hemorrhage therapy

Intracerebral hemorrhage (ICH), the most devastating subtype of stoke, is of high mortality at 5 years and even those survivors usually would suffer permanent disabilities. Fortunately, various preclinical active drugs have been approached in ICH, meanwhile, the therapeutic effects of these pharmaceutical ingredients could be fully boosted with the assistance of nanotechnology. In this review, besides the pathology of ICH, some ICH therapeutically available active drugs and their employed nanotechnologies, material functions, and therapeutic principles were comprehensively discussed hoping to provide novel and efficient strategies for ICH therapy in the future.

Melatonin Engineering M2 Macrophage-Derived Exosomes Mediate Endoplasmic Reticulum Stress and Immune Reprogramming for Periodontitis Therapy

Periodontitis is a chronic infectious disease caused by bacterial irritation. As an essential component of the host immunity, macrophages are highly plastic and play a crucial role in inflammatory response. An appropriate and timely transition from proinflammatory (M1) to anti-inflammatory (M2) macrophages is indispensable for treating periodontitis. As M2 macrophage-derived exosomes (M2-exos) can actively target inflammatory sites and modulate immune microenvironments, M2-exos can effectively treat periodontitis. Excessive endoplasmic reticulum stress (ER stress) and unfolded protein response (UPR) are highly destructive pathological characteristics during inflammatory periodontal bone loss. Although melatonin has antioxidant and anti-inflammatory effects, studies focusing on melatonin ER stress modulation remain limited. This study fabricates engineered M2-exos loading with melatonin (Mel@M2-exos) for treating periodontitis. As a result, M2-exos drive an appropriate and timely macrophage reprogramming from M1 to M2 type, which resolves chronic inflammation and accelerated periodontal healing. Melatonin released from Mel@M2-exos rescues the osteogenic and cementogenic differentiation capacity in inflammatory human periodontal ligament cells (hPDLCs) by reducing excessive ER stress and UPR. Injectable gelatin methacryloyl (GelMA) hydrogels with sustained-release Mel@M2-exos accelerate periodontal bone regeneration in rats with ligation-induced periodontitis. Taken together, melatonin engineering M2 macrophage-derived exosomes are promising candidates for inflammatory periodontal tissue regeneration.

Blood-brain crosstalk: the roles of neutrophils, platelets, and neutrophil extracellular traps in neuropathologies

Systemic inflammation, neurovascular dysfunction, and coagulopathy often occur concurrently in neuropathologies. Neutrophils and platelets have crucial synergistic roles in thromboinflammation and are increasingly suspected as effector cells contributing to the pathogenesis of neuroinflammatory diseases. In this review, we summarize the roles of platelet-neutrophil interactions in triggering complex pathophysiological events affecting the brain that may lead to the disruption of brain barriers, infiltration of toxic factors into the parenchyma, and amplification of neuroinflammation through the formation of neutrophil extracellular traps (NETs). We highlight the clinical significance of thromboinflammation in neurological disorders and examine the contributions of damage-associated molecular patterns (DAMPs) derived from platelets and neutrophils. These DAMPs originate from both infectious and non-infectious risk factors and contribute to the activation of inflammasomes during brain disorders. Finally, we identify knowledge gaps in the molecular mechanisms underlying neurodegenerative disease pathogenesis and emphasize the potential of interventions targeting platelets and neutrophils to treat neuroinflammatory diseases.

The adiponectin receptor agonist AdipoAI attenuates periodontitis in diabetic rats by inhibiting gingival fibroblast-induced macrophage migration

BACKGROUND AND PURPOSE

Low-grade inflammation, a common feature of both diabetes and periodontitis, partly accounts for the complexity and refractoriness of diabetes-associated periodontitis. Adiponectin (APN), the most abundant adipokine in human blood, has been widely reported to have anti-inflammatory functions. Herein, we investigated the ability of an APN receptor agonist, AdipoAI, to alleviate diabetes-associated periodontitis. Furthermore, we revealed the possible mechanism underlying its anti-inflammatory effects.

EXPERIMENTAL APPROACH

The maxillary first molar of Zucker diabetic fatty (ZDF) rats was ligated to construct a diabetes-associated periodontitis model, and rats were administered AdipoAI by gavage. We examined diabetes-related indexes, pathological changes in insulin target organs, alveolar bone resorption and systemic and local inflammation. In vitro, transwell assays were used to evaluate monocyte/macrophage migration induced by human gingival fibroblasts (hGFs) with/without AdipoAI treatment. Additionally, we examined chemokine expression levels in hGFs and hGF-induced monocyte/macrophage migration upon siRNA knockdown of Adiponectin receptor expression. Expression of Adipo1/Adipo2 receptors and inflammation-related signalling pathways were examined by IHC and WB, followed by confirmation with an NF-κB P65 inhibitor (BAY 11-7082).

KEY RESULTS

AdipoAI lowered fasting blood glucose and serum insulin in ZDF rats and alleviated inflammation in insulin target tissues. Locally, AdipoAI reduced alveolar bone absorption and gingival inflammation. Mechanistically, AdipoAI inhibited hGF-induced monocyte/macrophage migration by reducing CCL2 secretion. In hGFs, AdipoAI attenuated LPS-induced activation of NF-κB P65 and CCL2 expression, which was dependent on the Adipo receptor 1.

CONCLUSION AND IMPLICATIONS

AdipoAI, with its ability to alleviate inflammatory damage in tissues, is a candidate for diabetes-associated periodontitis treatment.