TcpC Inhibits M1 but Promotes M2 Macrophage Polarization via Regulation of the MAPK/NF-κB and Akt/STAT6 Pathways in Urinary Tract Infection

Molecular mechanisms of EGCG-CSH/n-HA/CMC in promoting osteogenic differentiation and macrophage polarization

2. This research investigates the impact of the EGCG-CSH/n-HA/CMC composite material on bone defect repair, emphasizing its influence on macrophage polarization and osteogenic differentiation of BMSCs. Comprehensive evaluations of the composite's physical and chemical characteristics were performed. BMSC response to the material was tested in vitro for proliferation, migration, and osteogenic potential. An SD rat model was employed for in vivo assessments of bone repair efficacy. Both transcriptional and proteomic analyses were utilized to delineate the mechanisms influencing macrophage behavior and stem cell differentiation. The material maintained excellent structural integrity and significantly promoted BMSC functions critical to bone healing. In vivo results confirmed accelerated bone repair, and molecular analysis highlighted the role of macrophage M2 polarization, particularly through changes in the SIRPA gene and protein expression. EGCG-CSH/n-HA/CMC plays a significant role in enhancing bone repair, with implications for macrophage and BMSC function. Our findings suggest that targeting SIRPA may offer new therapeutic opportunities for bone regeneration.

Ficolin-A induces macrophage polarization to a novel pro-inflammatory phenotype distinct from classical M1

BACKGROUND

Macrophages are key inflammatory immune cells that orchestrate the initiation and progression of autoimmune diseases. The characters of macrophage in diseases are determined by its phenotype in response to the local microenvironment. Ficolins have been confirmed as crucial contributors to autoimmune diseases, with Ficolin-2 being particularly elevated in patients with autoimmune diseases. However, whether Ficolin-A stimulates macrophage polarization is still poorly understood.

METHODS

We investigated the transcriptomic expression profile of murine bone marrow-derived macrophages (BMDMs) stimulated with Ficolin-A using RNA-sequencing. To further confirm a distinct phenotype activated by Ficolin-A, quantitative RT-PCR and Luminex assay were performed in this study. Additionally, we assessed the activation of underlying cell signaling pathways triggered by Ficolin-A. Finally, the impact of Ficolin-A on macrophages were investigated in vivo through building Collagen-induced arthritis (CIA) and Dextran Sulfate Sodium Salt (DSS)-induced colitis mouse models with Fcna-/- mice.

RESULTS

Ficolin-A activated macrophages into a pro-inflammatory phenotype distinct to LPS-, IFN-γ- and IFN-γ + LPS-induced phenotypes. The transcriptomic profile induced by Ficolin-A was primarily characterized by upregulation of interleukins, chemokines, iNOS, and Arginase 1, along with downregulation of CD86 and CD206, setting it apart from the M1 and M2 phenotypes. The activation effect of Ficolin-A on macrophages deteriorated the symptoms of CIA and DSS mouse models, and the deletion of Fcna significantly alleviated the severity of diseases in mice.

CONCLUSION

Our work used transcriptomic analysis by RNA-Seq to investigate the impact of Ficolin-A on macrophage polarization. Our findings demonstrate that Ficolin-A induces a novel pro-inflammatory phenotype distinct to the phenotypes activated by LPS, IFN-γ and IFN-γ + LPS on macrophages.

Lycopene promoted M2 macrophage polarization via inhibition of NOTCH1-PI3K-mTOR-NF-κB-JMJD3-IRF4 pathway in response to Escherichia coli infection in J744A.1 cells

Escherichia coli (E. coli) can induce severe clinical bovine mastitis, which is to blame for large losses experienced by dairy farms. Macrophage polarization into various states is in response to pathogen infections. Lycopene, a naturally occurring hydrocarbon carotenoid, relieved inflammation by controlling M1/M2 status of macrophages. Thus, we wanted to explore the effect of lycopene on polarization states of macrophages in E. coli-induced mastitis. Macrophages were cultivated with lycopene for 24, before E. coli inoculation for 6 h. Lycopene (0.5 μmol/L) significantly enhanced cell viabilities and significantly reduced lactic dehydrogenase (LDH) levels in macrophages, whereas 2 and 3 μmol/L lycopene significantly enhanced LDH activities. Lycopene treatment significantly reduced the increase in LDH release, iNOS, CD86, TNF-α, IL-1β and phosphatase and tensin homolog (PTEN) expressions in E. coli group. 0.5 μmol/L lycopene significantly increased E. coli-induced downregulation of CD206, arginase I (ARG1), indoleamine 2,3-dioxygenase (IDO), chitinase 3-like 3 (YM1), PI3K, AKT, p-AKT, mammalian target of rapamycin (mTOR), p-mTOR, jumonji domain-containing protein-3 (JMJD3) and interferon regulatory factor 4 (IRF4) levels. Moreover, Ginkgolic acid C17:1 (a specific PTEN inhibitor), 740YPDGFR (a specific PI3K activator), SC79 (a specific AKT activator) or CHPG sodium salt (a specific NF-κB activator) significantly decreased CD206, AGR1, IDO and YM1 expressions in lycopene and E. coli-treated macrophages. Therefore, lycopene increased M2 macrophages via inhibiting NOTCH1-PI3K-mTOR-NF-κB-JMJD3-IRF4 pathway in response to E. coli infection in macrophages. These results contribute to revealing the pathogenesis of E. coli-caused bovine mastitis, providing the new angle of the prevention and management of mastitis.

Multiwalled Carbon Nanotubes-Reprogrammed Macrophages Facilitate Breast Cancer Metastasis via NBR2/TBX1 Axis

In recent years, carbon nanotubes have emerged as a widely used nanomaterial, but their human exposure has become a significant concern. In our former study, we reported that pulmonary exposure of multiwalled carbon nanotubes (MWCNTs) promoted tumor metastasis of breast cancer; macrophages were key effectors of MWCNTs and contributed to the metastasis-promoting procedure in breast cancer, but the underlying molecular mechanisms remain to be explored. As a follow-up study, we herein demonstrated that MWCNT exposure in breast cancer cells and macrophage coculture systems promoted metastasis of breast cancer cells both in vitro and in vivo; macrophages were skewed into M2 polarization by MWCNT exposure. LncRNA NBR2 was screened out to be significantly decreased in MWCNTs-stimulated macrophages through RNA-seq; depletion of NBR2 led to the acquisition of M2 phenotypes in macrophages by activating multiple M2-related pathways. Specifically, NBR2 was found to positively regulate the downstream gene TBX1 through H3k27ac activation. TBX1 silence rescued NBR2-induced impairment of M2 polarization in IL-4 & IL-13-stimulated macrophages. Moreover, NBR2 overexpression mitigated the enhancing effects of MWCNT-exposed macrophages on breast cancer metastasis. This study uncovered the molecular mechanisms underlying breast cancer metastasis induced by MWCNT exposure.

Dehydroandrographolide facilitates M2 macrophage polarization by downregulating DUSP3 to inhibit sepsis-associated acute kidney injury

BACKGROUND

Sepsis is perceived as lethal tissue damage and significantly increases mortality in combination with acute kidney injury (AKI). M2 macrophages play important roles in the secretion of anti-inflammatory and tissue repair mediators. We aimed to study the role of Dehydroandrographolide (Deh) in sepsis-associated AKI in vitro and in vivo through lipopolysaccharide (LPS)-induced macrophages model and cecal ligation and puncture-induced AKI mice model, and to reveal the mechanism related to M2 macrophage polarization.

METHODS

Enzyme-linked immunosorbent assay kits were used to assess the levels of inflammatory factors. Expression of markers related to M1 macrophages and M2 macrophages were analyzed. Additionally, dual specificity phosphatase 3 (DUSP3) expression was tested. Cell apoptosis was evaluated by flow cytometry analysis and terminal-deoxynucleotidyl transferase-mediated nick end labeling staining. Moreover, renal histological assessment was performed by using hematoxylin and eosin staining.

RESULTS

Deh reduced inflammation of THP-1-derived macrophages exposed to LPS. Besides, Deh induced the polarization of M1 macrophages to M2 and downregulated DUSP3 expression in THP-1-derived macrophages under LPS conditions. Further, DUSP3 overexpression reversed the impacts of Deh on the inflammation and M2 macrophages polarization of THP-1-derived macrophages stimulated by LPS. Additionally, human proximal tubular epithelial cells (HK-2) in the condition medium from DUSP3-overexpressed THP-1-derived macrophages treated with LPS and Deh displayed decreased viability and increased apoptosis and inflammation. The in vivo results suggested that Deh improved the renal function, ameliorated pathological injury, induced the polarization of M1 macrophages to M2, suppressed inflammation and apoptosis, and downregulated DUSP3 expression in sepsis-induced mice.

CONCLUSION

Deh facilitated M2 macrophage polarization by downregulating DUSP3 to inhibit septic AKI.

miR-345-3p Modulates M1/M2 Macrophage Polarization to Inhibit Inflammation in Bone Infection via Targeting MAP3K1 and NF-κB Pathway

Infection after fracture fixation (IAFF), a complex infectious disease, causes inflammatory destruction of bone tissue and poses a significant clinical challenge. miR-345-3p is a biomarker for tibial infected nonunion; however, the comprehensive mechanistic role of miR-345-3p in IAFF is elusive. In this study, we investigated the role of miR-345-3p in IAFF pathogenesis through in vivo and in vitro experiments. In vivo, in a rat model of IAFF, miR-345-3p expression was downregulated, accompanied by increased M1 macrophage infiltration and secretion of proinflammatory factors. In vitro, LPS induced differentiation of primary rat bone marrow-derived macrophages into M1 macrophages, which was attenuated by miR-345-3p mimics. miR-345-3p promoted M1 to M2 macrophage transition-it reduced the expression of cluster of differentiation (CD) 86, inducible NO synthase, IL-1β, and TNF-α but elevated those of CD163, arginase-1, IL-4, and IL-10. MAPK kinase kinase 1 (MAP3K1), a target mRNA of miR-345-3p, was overexpressed in the bone tissue of IAFF rats compared with that in those of the control rats. The M1 to M2 polarization inhibited MAP3K1 signaling pathways in vitro. Conversely, MAP3K1 overexpression promoted the transition from M2 to M1. miR-345-3p significantly inhibited NF-κB translocation from the cytosol to the nucleus in a MAP3K1-dependent manner. In conclusion, miR-345-3p promotes the polarization of M1 macrophages to the M2 phenotype by inhibiting the MAP3K1 and NF-κB pathways. These findings provide insight into the pathogenesis and immunotherapeutic strategies for IAFF and offer potential new targets for subsequent research.

Deficiency of INPP4A promotes M2 macrophage polarization in eosinophilic chronic rhinosinusitis with nasal polyps

OBJECTIVE

The treatment of eosinophilic chronic rhinosinusitis with nasal polyps (E-CRSwNP) remains a challenge due to its complex pathogenesis. Inositol polyphosphate-4-phosphatase type IA (INPP4A), a lipid phosphatase, has been implicated in allergic asthma. However, the expression and function of INPP4A in E-CRSwNP remain unclear. This study aims to investigate the role of INPP4A in macrophages in E-CRSwNP.

METHODS

We assessed the expression of INPP4A in human and mouse nasal mucosal tissues via immunofluorescence staining. THP-1 cells were cultured and exposed to various cytokines to investigate the regulation of INPP4A expression and its functional role. Additionally, we established a murine nasal polyp (NP) model and administrated an INPP4A-overexpressing lentivirus evaluate its impact on NP.

RESULTS

The percentage of INPP4A + CD68 + macrophages among total macrophages decreased in the E-CRSwNP group compared to the control and the non-eosinophilic CRSwNP (NE-CRSwNP) groups, exhibiting an inverse correlation with an increased percentage of CD206 + CD68 + M2 macrophages among total macrophages. Overexpression of INPP4A led to a reduced percentage of THP-1 cells polarizing towards the M2 phenotype, accompanied by decreased levels of associated chemotactic factors including CCL18, CCL22, CCL24, and CCL26. We also validated the involvement of the PI3K-AKT pathway in the function of INPP4A in vitro. Furthermore, INPP4A overexpression in the murine NP model resulted in the attenuation of eosinophilic inflammation in the nasal mucosa.

CONCLUSIONS

INPP4A deficiency promotes macrophage polarization towards the M2 phenotype, leading to the secretion of chemokines that recruit eosinophils and Th2 cells, thereby amplifying eosinophilic inflammation in E-CRSwNP. INPP4A may exert a suppressive role in eosinophilic inflammation and could potentially serve as a novel therapeutic strategy.

Function and inhibition of P38 MAP kinase signaling: Targeting multiple inflammation diseases

Inflammation is a natural host defense mechanism that protects the body from pathogenic microorganisms. A growing body of research suggests that inflammation is a key factor in triggering other diseases (lung injury, rheumatoid arthritis, etc.). However, there is no consensus on the complex mechanism of inflammatory response, which may include enzyme activation, mediator release, and tissue repair. In recent years, p38 MAPK, a member of the MAPKs family, has attracted much attention as a central target for the treatment of inflammatory diseases. However, many p38 MAPK inhibitors attempting to obtain marketing approval have failed at the clinical trial stage due to selectivity and/or toxicity issues. In this paper, we discuss the mechanism of p38 MAPK in regulating inflammatory response and its key role in major inflammatory diseases and summarize the synthetic or natural products targeting p38 MAPK to improve the inflammatory response in the last five years, which will provide ideas for the development of novel clinical anti-inflammatory drugs based on p38 MAPK inhibitors.

Manganese and IL-12 treatment alters the ovarian tumor microenvironment

Metal immunotherapy is a novel adjuvant immunotherapy. Mn2+ can activate STING-a type I IFN response protein-that promotes innate immunity and increases anti-tumor activity by promoting macrophage phagocytosis. IL-12, a cytokine that increases the antigen-presenting ability to promote effector T-cell activation, has potent antitumor activity, albeit with severe adverse effects. In this study, we observed that the combination of Mn2+ and IL-12 has a better antitumor effect and possibly reflects a better safety profile, providing a novel approach and theoretical basis for safe and rapid cancer treatment.

Par3L, a polarity protein, promotes M1 macrophage polarization and aggravates atherosclerosis in mice via p65 and ERK activation

Proinflammatory M1 macrophages are critical for the progression of atherosclerosis. The Par3-like protein (Par3L) is a homolog of the Par3 family involved in cell polarity establishment. Par3L has been shown to maintain the stemness of mammary stem cells and promote the survival of colorectal cancer cells. In this study, we investigated the roles of the polar protein Par3L in M1 macrophage polarization and atherosclerosis. To induce atherosclerosis, Apoe-/- mice were fed with an atherosclerotic Western diet for 8 or 16 weeks. We showed that Par3L expression was significantly increased in human and mouse atherosclerotic plaques. In primary mouse macrophages, oxidized low-density lipoprotein (oxLDL, 50 μg/mL) time-dependently increased Par3L expression. In Apoe-/- mice, adenovirus-mediated Par3L overexpression aggravated atherosclerotic plaque formation accompanied by increased M1 macrophages in atherosclerotic plaques and bone marrow. In mouse bone marrow-derived macrophages (BMDMs) or peritoneal macrophages (PMs), we revealed that Par3L overexpression promoted LPS and IFNγ-induced M1 macrophage polarization by activating p65 and extracellular signal-regulated kinase (ERK) rather than p38 and JNK signaling. Our results uncover a previously unidentified role for the polarity protein Par3L in aggravating atherosclerosis and favoring M1 macrophage polarization, suggesting that Par3L may serve as a potential therapeutic target for atherosclerosis.

TRAM deletion attenuates monocyte exhaustion and alleviates sepsis severity

Monocyte exhaustion characterized by immune-suppressive features can develop during sepsis and contribute to adverse patient outcomes. However, molecular mechanisms responsible for the establishment of immune-suppressive monocytes with reduced expression of immune-enhancing mediators such as CD86 during sepsis are not well understood. In this study, we identified that the TLR4 intracellular adaptor TRAM plays a key role in mediating the sustained reduction of CD86 expression on exhausted monocytes and generating an immune-suppressive monocyte state. TRAM contributes to the prolonged suppression of CD86 through inducing TAX1BP1 as well as SARM1, collectively inhibiting Akt and NFκB. TRAM deficient mice are protected from cecal slurry-induced experimental sepsis and retain immune-competent monocytes with CD86 expression. Our data reveal a key molecular circuitry responsible for monocyte exhaustion and provide a viable target for rejuvenating functional monocytes and treating sepsis.

Thermoresponsive M1 macrophage-derived hybrid nanovesicles for improved in vivo tumor targeting

Despite the efforts and advances done in the last few decades, cancer still remains one of the main leading causes of death worldwide. Nanomedicine and in particular extracellular vesicles are one of the most potent tools to improve the effectiveness of anticancer therapies. In these attempts, the aim of this work is to realize a hybrid nanosystem through the fusion between the M1 macrophages-derived extracellular vesicles (EVs-M1) and thermoresponsive liposomes, in order to obtain a drug delivery system able to exploit the intrinsic tumor targeting capability of immune cells reflected on EVs and thermoresponsiveness of synthetic nanovesicles. The obtained nanocarrier has been physicochemically characterized, and the hybridization process has been validated by cytofluorimetric analysis, while the thermoresponsiveness was in vitro confirmed through the use of a fluorescent probe. Tumor targeting features of hybrid nanovesicles were in vivo investigated on melanoma-induced mice model monitoring the accumulation in tumor site through live imaging and confirmed by cytofluorimetric analysis, showing higher targeting properties of hybrid nanosystem compared to both liposomes and native EVs. These promising results confirmed the ability of this nanosystem to combine the advantages of both nanotechnologies, also highlighting their potential use as effective and safe personalized anticancer nanomedicine.

Dendrocandin U from Dendrobium officinale Kimura et Migo Inhibits M1 Polarization in Alveolar Macrophage by Suppressing NF-κB Signaling Pathway

Dendrobium officinale Kimura et Migo is a valuable and homologous medicine and food traditional Chinese medicine. Currently there are few studies on the anti-inflammatory activity of lipophilic components. The aim of this study was to explore the anti-inflammatory effect and mechanism of the lipophilic compounds in Dendrobium officinale. Six compounds were isolated and identified, including three bibenzyl compounds, dendrocandin U, dendronbibisline B, erianin, and three lignans, (-)-syringaresinol, (+)-syringaresinol-O-β-D-glucopyranoside, 5-methoxy-(+)-isolariciresinol. Among them, dendronbibisline B and 5-methoxy-(+)-isolariciresinol were isolated from Dendrobium officinale for the first time. Besides, we found dendrocandin U, dendronbibisline B and (-)-syringaresinol exhibited the anti-inflammation to inhibit nitric oxide secretion induced by lipopolysaccharide (LPS)/interferon (IFN-γ) in MH-S cells. Furthermore, dendrocandin U could inhibit the expression of tumor necrosis factor-α (TNF-α), Cluster of Differentiation 86 (CD86), and reduce inflammatory morphological changes of macrophages. Meanwhile, we confirmed that the anti-inflammation mechanism of dendrocandin U was to inhibit M1 polarization by suppressing toll-like receptor 4 (TLR4)/recombinant myeloid differentiation factor 88 (MyD88)/nuclear factor kappa B (NF-κB) signaling pathway. In this paper, dendrocandin U with significant anti-inflammatory activity was found from Dendrobium officinale, which could provide a basis for the study of its anti-inflammatory drugs.

Cancer stem cell-derived CHI3L1 activates the MAF/CTLA4 signaling pathway to promote immune escape in triple-negative breast cancer

BACKGROUND

Triple-negative breast cancer (TNBC) development may be associated with tumor immune escape. This study explores whether the CHI3L1/MAF/CTLA4/S100A4 axis affects immune escape in TNBC through interplay with triple-negative breast cancer stem cells (TN-BCSCs).

OBJECTIVE

The aim of this study is to utilize single-cell transcriptome sequencing (scRNA-seq) to uncover the molecular mechanisms by which the CHI3L1/MAF/CTLA4 signaling pathway may mediate immune evasion in triple-negative breast cancer through the interaction between tumor stem cells (CSCs) and immune cells.

METHODS

Cell subsets in TNBC tissues were obtained through scRNA-seq, followed by screening differentially expressed genes in TN-BCSCs and B.C.s (CD44+ and CD24-) and predicting the transcription factor regulated by CHI3L1. Effect of CHI3L1 on the stemness phenotype of TNBC cells investigated. Effects of BCSCs-231-derived CHI3L1 on CTLA4 expression in T cells were explored after co-culture of BCSCs-231 cells obtained from microsphere culture of TN-BCSCs with T cells. BCSCs-231-treated T cells were co-cultured with CD8+ T cells to explore the resultant effect on T cell cytotoxicity. An orthotopic B.C. transplanted tumor model in mice with humanized immune systems was constructed, in which the Role of CHI3L1/MAF/CTLA4 in the immune escape of TNBC was explored.

RESULTS

Eight cell subsets were found in the TNBC tissues, and the existence of TN-BCSCs was observed in the epithelial cell subset. CHI3L1 was related to the stemness phenotype of TNBC cells. TN-BCSC-derived CHI3L1 increased CTLA4 expression in T cells through MAF, inhibiting CD8+ T cell cytotoxicity and inducing immunosuppression. Furthermore, the CTLA4+ T cells might secrete S100A4 to promote the stemness phenotype of TNBC cells.

CONCLUSIONS

TN-BCSC-derived CHI3L1 upregulates CTLA4 expression in T cells through MAF, suppressing the function of CD8+ T cells, which promotes the immune escape of TNBC.

M1/M2 macrophages and their overlaps - myth or reality?

Macrophages represent heterogeneous cell population with important roles in defence mechanisms and in homoeostasis. Tissue macrophages from diverse anatomical locations adopt distinct activation states. M1 and M2 macrophages are two polarized forms of mononuclear phagocyte in vitro differentiation with distinct phenotypic patterns and functional properties, but in vivo, there is a wide range of different macrophage phenotypes in between depending on the microenvironment and natural signals they receive. In human infections, pathogens use different strategies to combat macrophages and these strategies include shaping the macrophage polarization towards one or another phenotype. Macrophages infiltrating the tumours can affect the patient's prognosis. M2 macrophages have been shown to promote tumour growth, while M1 macrophages provide both tumour-promoting and anti-tumour properties. In autoimmune diseases, both prolonged M1 activation, as well as altered M2 function can contribute to their onset and activity. In human atherosclerotic lesions, macrophages expressing both M1 and M2 profiles have been detected as one of the potential factors affecting occurrence of cardiovascular diseases. In allergic inflammation, T2 cytokines drive macrophage polarization towards M2 profiles, which promote airway inflammation and remodelling. M1 macrophages in transplantations seem to contribute to acute rejection, while M2 macrophages promote the fibrosis of the graft. The view of pro-inflammatory M1 macrophages and M2 macrophages suppressing inflammation seems to be an oversimplification because these cells exploit very high level of plasticity and represent a large scale of different immunophenotypes with overlapping properties. In this respect, it would be more precise to describe macrophages as M1-like and M2-like.

Hydralazine Promotes Central Nervous System Recovery after Spinal Cord Injury by Suppressing Oxidative Stress and Inflammation through Macrophage Regulation

OBJECTIVE

This study aims to investigate the effects of hydralazine on inflammation induced by spinal cord injury (SCI) in the central nervous system (CNS) and its mechanism in promoting the structural and functional recovery of the injured CNS.

METHODS

A compressive SCI mouse model was utilized for this investigation. Immunofluorescence and quantitative real-time polymerase chain reaction were employed to examine the levels of acrolein, acrolein-induced inflammation-related factors, and macrophages at the injury site and within the CNS. Western blotting was used to evaluate the activity of the phosphoinositide 3-kinase (PI3K)/AKT pathway to study macrophage regulation. The neuropathic pain and motor function recovery were evaluated by glutamic acid decarboxylase 65/67 (GAD65/67), vesicular glutamate transporter 1 (VGLUT1), paw withdrawal response, and Basso Mouse Scale score. Nissl staining and Luxol Fast Blue (LFB) staining were performed to investigate the structural recovery of the injured CNS.

RESULTS

Hydralazine downregulated the levels of acrolein, IL-1β, and TNF-α in the spinal cord. The downregulation of acrolein induced by hydralazine promoted the activation of the PI3K/AKT pathway, leading to M2 macrophage polarization, which protected neurons against SCI-induced inflammation. Additionally, hydralazine promoted the structural recovery of the injured spinal cord area. Mitigating inflammation and oxidative stress by hydralazine in the animal model alleviated neuropathic pain and altered neurotransmitter expression. Furthermore, hydralazine facilitated motor function recovery following SCI. Nissl staining and LFB staining indicated that hydralazine promoted the structural recovery of the injured CNS.

CONCLUSION

Hydralazine, an acrolein scavenger, significantly mitigated SCI-induced inflammation and oxidative stress in vivo, modulated macrophage activation, and consequently promoted the structural and functional recovery of the injured CNS.

α-Aminobutyric Acid Constrains Macrophage-Associated Inflammatory Diseases through Metabolic Reprogramming and Epigenetic Modification

Metabolites play critical roles in macrophage polarization and in their function in response to infection and inflammation. α-aminobutyric acid (AABA), a non-proteinogenic amino acid which can be generated from methionine, threonine, serine, and glycine, has not been studied extensively in relation to macrophage polarization and function. In this study, we aimed to investigate the immunomodulatory function of AABA in regulating M1 macrophage polarization and function in vitro and in vivo. We stimulated bone-marrow-derived macrophages with lipopolysaccharide (LPS) to generate M1 macrophages. Subsequently, we induced sepsis and colitis in mice, followed by treatment with AABA. We then analyzed the samples using ELISA, real-time PCR, Western blotting, flow cytometry, and histopathological analysis to evaluate cytokine secretion, inflammatory gene expression, macrophage activation, disease progression, and inflammation severity. Additionally, metabolomic and chromatin immunoprecipitation-qPCR were conducted to investigate the function of AABA on metabolic reprogramming and epigenetic modifications of M1 macrophages. Our results revealed that AABA inhibited M1 macrophage polarization and function, which led to prolonged survival in septic mice and reduced disease severity in colitis mice. Mechanically, AABA promoted oxidative phosphorylation (OXPHOS) and glutamine and arginine metabolism while inhibiting glycolysis. Moreover, AABA could increase the occupancy of trimethylation of histone H3K27 at the promoter regions of M1 macrophage-associated inflammatory genes, which contributed to the inhibition of M1 macrophage polarization. These findings suggest that AABA may have therapeutic potential for inflammatory diseases by regulating macrophage polarization and function through metabolic and epigenetic pathways.

Enhancer of zeste homolog 2 promotes renal fibrosis after acute kidney injury by inducing epithelial-mesenchymal transition and activation of M2 macrophage polarization

Long-term follow-up data indicates that 1/4 patients with acute kidney injury (AKI) will develop to chronic kidney disease (CKD). Our previous studies have demonstrated that enhancer of zeste homolog 2 (EZH2) played an important role in AKI and CKD. However, the role and mechanisms of EZH2 in AKI-to-CKD transition are still unclear. Here, we demonstrated EZH2 and H3K27me3 highly upregulated in kidney from patients with ANCA-associated glomerulonephritis, and expressed positively with fibrotic lesion and negatively with renal function. Conditional EZH2 deletion or pharmacological inhibition with 3-DZNeP significantly improved renal function and attenuated pathological lesion in ischemia/reperfusion (I/R) or folic acid (FA) mice models (two models of AKI-to-CKD transition). Mechanistically, we used CUT & Tag technology to verify that EZH2 binding to the PTEN promoter and regulating its transcription, thus regulating its downstream signaling pathways. Genetic or pharmacological depletion of EZH2 upregulated PTEN expression and suppressed the phosphorylation of EGFR and its downstream signaling ERK1/2 and STAT3, consequently alleviating the partial epithelial-mesenchymal transition (EMT), G2/M arrest, and the aberrant secretion of profibrogenic and proinflammatory factors in vivo and vitro experiments. In addition, EZH2 promoted the EMT program induced loss of renal tubular epithelial cell transporters (OAT1, ATPase, and AQP1), and blockade of EZH2 prevented it. We further co-cultured macrophages with the medium of human renal tubular epithelial cells treated with H₂O₂ and found macrophages transferred to M2 phenotype, and EZH2 could regulate M2 macrophage polarization through STAT6 and PI3K/AKT pathways. These results were further verified in two mice models. Thus, targeted inhibition of EZH2 might be a novel therapy for ameliorating renal fibrosis after acute kidney injury by counteracting partial EMT and blockade of M2 macrophage polarization.

Targeting macrophages in atherosclerosis using nanocarriers loaded with liver X receptor agonists: A narrow review

Macrophages are involved in the whole process of atherosclerosis, which is characterized by accumulation of lipid and inflammation. Presently, clinically used lipid-lowering drugs cannot completely retard the progress of atherosclerosis. Liver X receptor (LXR) plays a key role in regulation of lipid metabolism and inflammation. Accumulating evidence have demonstrated that synthetic LXR agonists can significantly retard the development of atherosclerosis. However, these agonists induce sever hypertriglyceridemia and liver steatosis. These side effects have greatly limited their potential application for therapy of atherosclerosis. The rapid development of drug delivery system makes it possible to delivery interested drugs to special organs or cells using nanocarriers. Macrophages express various receptors which can recognize and ingest specially modified nanocarriers loaded with LXR agonists. In the past decades, a great progress has been made in this field. These macrophage-targeted nanocarriers loaded with LXR agonists are found to decrease atherosclerosis by reducing cholesterol accumulation and inflammatory reactions. Of important, these nanocarriers can alleviate side effects of LXR agonists. In this article, we briefly review the roles of macrophages in atherosclerosis, mechanisms of action of LXR agonists, and focus on the advances of macrophage-targeted nanocarriers loaded with LXR agonists. This work may promote the potential clinical application of these nanocarriers.