Immune Response Of Macrophages Research Articles

Potentilla anserina L. polysaccharide ameliorates LPS-induced acute lung injury and relevant intestinal mucosal barrier impairment.

Acute lung injury (ALI) is a life-threatening condition that occurs in patients triggered with complex factors, contributing to multiple organ dysfunction and mortality. Therefore, it is crucial to seek novel targets for treating ALI. To investigate the effects of Potentilla anserina L. polysaccharide (PAP) on ALI and associated damage to the intestinal mucosal barrier induced by lipopolysaccharide (LPS), ALI mouse model was adopted. Mice were intraperitoneal injection of LPS, with or without PAP., then serum, lung, spleen, small intestine, and bronchoalveolar lavage fluid (BALF) samples of mice obtained were used to discuss the treatment of PAP on ALI and relevant organ damage. Meanwhile, the underlying signal pathway was searched from GeneCards and DisGeNET databases, and then verified it by western blot. These results indicated that PAP effectively reduced inflammatory levels in LPS-induced ALI and associated intestinal mucosal barrier impairment, as well as the M1 macrophage immune response by activating the Rap1 signal pathway. These results suggested that the medicinal herb PAP is a therapeutic potential anti-inflammatory agent for ALI and relevant organ dysfunction.

Mitochondria complex III-generated superoxide is essential for IL-10 secretion in macrophages.

Mitochondrial electron transport chain (ETC) function modulates macrophage biology; however, mechanisms underlying mitochondria ETC control of macrophage immune responses are not fully understood. Here, we report that mutant mice with mitochondria ETC complex III (CIII)-deficient macrophages exhibit increased susceptibility to influenza A virus (IAV) and LPS-induced endotoxic shock. Cultured bone marrow-derived macrophages (BMDMs) isolated from these mitochondria CIII-deficient mice released less IL-10 than controls following TLR3 or TLR4 stimulation. Unexpectedly, restoring mitochondrial respiration without generating superoxide using alternative oxidase (AOX) was not sufficient to reverse LPS-induced endotoxic shock susceptibility or restore IL-10 release. However, activation of protein kinase A (PKA) rescued IL-10 release in mitochondria CIII-deficient BMDMs following LPS stimulation. In addition, mitochondria CIII deficiency did not affect BMDM responses to interleukin-4 (IL-4) stimulation. Thus, our results highlight the essential role of mitochondria CIII-generated superoxide in the release of anti-inflammatory IL-10 in response to TLR stimulation.

Regulation of macrophage-mediated osteogenesis by kaempferol liposomes in trauma-induced heterotopic ossification.

Heterotopic ossification (HO) is characterized by abnormal bone formation outside the skeleton following injury or inherited disease, leading to limb dysfunction and neurological deficits. Current treatment options for HO are largely ineffective. A network pharmacological analysis was conducted to identify the active ingredients and protein targets in Astragalus and Cinnamon Twig Five-Substance Decoction (ACTFSD) on HO. Protein-protein interaction analysis and Gene Ontology Enrichment Analysis were used to investigate the key genes associated with the target proteins. Molecular docking was employed to validate the interactions between the core components and targets of ACTFSD. Kaempferol was encapsulated in liposomes synthesized via the thin-film dispersion method. In vitro and in vivo experiments were conducted to evaluate the therapeutic effects of kaempferol liposomes. Kaempferol, an active ingredient in ACTFSD, effectively inhibits the PTGS2\ NF-κB pathway, regulates macrophage immune responses, and reduces cytokine released by macrophages induce abnormal osteogenesis in tendon stem cells (TDSCs), thereby slowing the formation of HO. Kaempferol liposomes demonstrate better therapeutic effect than kaempferol alone. This study indicates that targeting macrophages may represent an effective therapeutic strategy for HO. Furthermore, kaempferol liposomes appear to be a promising treatment for trauma-induced HO. These findings provide potential new directions for future HO treatment strategies.

Piezo1 Enhances Macrophage Phagocytosis and Pyrin Activation to Ameliorate Fungal Keratitis.

Fungal keratitis (FK) remains a treatment challenge, necessitating new therapeutic targets. Piezo1, a mechanosensitive ion channel, regulates calcium signaling and immune cell function. This study investigates its role in macrophage-mediated antifungal responses in FK. Piezo1 and Pyrin expression in corneas and bone marrow-derived macrophages (BMDMs) were assessed by RNAseq, quantitative real-time PCR (qRT-PCR), Western blot, and immunofluorescence. Intracellular calcium ion concentration was detected by Fluo-4 AM fluorescent probe staining. Heterozygous Piezo1 deficiency (Piezo1+/-) mice and Yoda1 were performed to regulate the expression of Piezo1. Our investigation demonstrates elevated expression of Piezo1 in the corneas of patients with FK and infected mice. This upregulation of Piezo1 corresponded with the swift recruitment of macrophages via the limbus. Additionally, Piezo1+/- mice exacerbate the progression of FK in the infection model. Furthermore, Piezo1 knockdown in macrophages exhibit a notable reduction phagocytic capacity, accompanied by an increase in viable colony-forming units in an in vitro model of fungal infection. Moreover, using a pharmacologic activator of Piezo1 (Yoda1), a calcium ion (Ca2+) chelator of BAPTA or Piezo1+/- mice, we demonstrate that Piezo1 activation triggers the Pyrin inflammasome via augmented calcium ion influx, which is required for protection against FK in murine hosts. Piezo1 is crucial for innate immunity in FK, enhancing macrophage recruitment, activation, and Pyrin inflammasome-mediated antifungal activity via calcium signaling. Using Piezo1+/- mice and Yoda1, we confirm Piezo1's role in fungal clearance. Targeting Piezo1 offers a novel strategy to improve FK outcomes by boosting macrophage function and immune response.

Analysis of the effect of ALA-PDT on macrophages in footpad model of mice infected with Fonsecaea monophora based on single-cell sequencing.

Chromoblastomycosis (CBM) is a chronic neglected fungal disease that causes serious damage to the physical and mental health of patients. 5-Aminolevulinic acid photodynamic therapy (ALA-PDT) has garnered significant attention in the recent era for the treatment of CBM and has exhibited promising effects in several clinical case reports. We established a mice footpad infection model with Fonsecaea monophora and analyzed the impact of PDT treatment on the immune response of macrophages using single-cell sequencing. The results showed that infection of the mouse footpad skin with F. monophora results in an increase in inflammatory cells, primarily mononuclear-macrophages, with the activation of complement and enhancement of cell chemotaxis, leading to upregulation of anti-infection-related pathways. After ALA-PDT treatment, the number of inflammatory cells decreased, while macrophages upregulated the expression of antigen-recognition-related genes, enhancing phagocytosis and autophagy-related biological functions.

Macrophages in sepsis-induced acute lung injury: exosomal modulation and therapeutic potential.

Sepsis-induced acute lung injury (ALI) remains a leading cause of mortality in critically ill patients. Macrophages, key modulators of immune responses, play a dual role in both promoting and resolving inflammation. Exosomes, small extracellular vesicles released by various cells, carry bioactive molecules that influence macrophage polarization and immune responses. Emerging researchers have identified exosomes as crucial mediators that modulate macrophage activity during sepsis-induced ALI. This review explores the role of exosomes in modulating macrophage functions, focusing on the cellular interactions within the lung microenvironment and their potential as therapeutic targets. It highlights the regulation of macrophages by exosomes derived from pathogenic germs, neutrophils, alveolar epithelial cells, and mesenchymal stromal cells. By understanding these mechanisms, it aims to uncover innovative therapeutic strategies for sepsis-induced ALI.

A specific and adaptable approach to track CD206+ macrophages by molecular MRI and fluorescence imaging.

Rationale: The mannose receptor (CD206, expressed by the gene Mrc1) is a surface marker overexpressed by anti-inflammatory and pro-tumoral macrophages. As such, CD206+ macrophages play key roles in the immune response to different pathophysiological conditions and represent a promising diagnostic and therapeutic target. However, methods to specifically target these cells remain challenging. In this study, we describe a multi-mannose approach to develop CD206-targeting fluorescent and MRI agents that specifically and sensitively detect and monitor CD206+ macrophage immune response in different disease conditions. Methods: We designed and synthesized fluorescent agents MR1-cy5 and MR2-cy5, and MRI agents Mann2-DTPA-Gd and MannGdFish. Cellular assays using pro-inflammatory and anti-inflammatory macrophages differentiated from RAW 264.7 cells were performed, and signals were detected by fluorescence microscopy and inductively coupled plasma mass spectrometry (ICP-MS) to validate specificity in vitro. In vivo specificity and efficacy of the agents were evaluated by MRI in a subcutaneous wound healing model and experimental glioma with Mrc1 +/+ without and with D-mannose treatment, Mrc1 +/-, and Mrc1 -/- mice, and in stroke. One-way ANOVA and two-way ANOVA tests were used for data analysis. P < 0.05 was considered statistically different. Results: Both in vitro fluorescence imaging with MR2-cy5, ICP-MS with Mann2-DTPA-Gd, and in vivo MRI in Mrc1 -/- mice confirmed the specificity of our approach. Mann2-DTPA-Gd MRI can track the changes of CD206+ macrophages at different stages of wound healing, correlating well with flow cytometry data using another anti-inflammatory macrophage marker (arginase-1). The specificity and efficacy of Mann2-DPTA-Gd were further validated in experimental glioma, in which Mann2-DTPA-Gd imaging detected CD206+ tumor-associated macrophages (TAMs), demonstrated significantly decreased signals in Mrc1 +/- mice and Mrc1 -/- mice, and tracked treatment changes in D-mannose-treated Mrc1 +/+ mice. Furthermore, Mann2-DTPA-Gd can report microglia/macrophages and correlate with histology in stroke. The more Gd-stable agent MannGdFish demonstrated similar efficacy as Mann2-DTPA-Gd in vivo with favorable biodistribution and pharmacokinetics. Conclusion: We have developed a fluorescent agent (MR2-cy5) and MRI agents (Mann2-DTPA-Gd and MannGdFish) with two mannose moieties that are highly specific to CD206 and can track CD206+ macrophages in disease models of wound healing, tumor, and neurological disease. Importantly, MannGdFish, with its high specificity, stability, favorable biodistribution, and pharmacokinetics, is a promising translational candidate to noninvasively monitor CD206+ macrophages in repair/regeneration and tumors in patients. In addition, with the specific binding motif to CD206, other imaging modalities and therapeutic agents could also be introduced for theranostic applications.

Pullulan-spermine enhance the tolerance of probiotics and immune stimulation of macrophages.

The application of probiotics as adjunctive therapy in colorectal cancer treatment is hindered by the paucity of strains with specialized functions and the instability of their in vivo efficacy. The design of innovative and simple encapsulation strategies to enhance their stability and efficacy of probiotics has garnered substantial interest. This study investigated four Bifidobacterium longum strains from human feces for tolerance and cytotoxicity, and then synthesized a cationic polysaccharide, pullulan-spermine (PS), for probiotic encapsulation. The results indicated that the encapsulation by PS hold superior protective capacity and elevated the level of TNF-α and IL-12. In vivo studies further confirmed the retention capacity and safety of this probiotic-PS complex. Generally, this research presents an effective probiotic encapsulation strategy that could enhance macrophage immune responses, offering novel insights for probiotic-based therapies in major diseases like colon cancer treatment.

Preclinical evaluation of 68Ga-labeled folic acid conjugates for visualization of inflammatory foci.

Folate receptors (FR) have been considered a convenient target for different radiopharmaceuticals in recent years. Multifarious 68Ga-labeled folate conjugates have been proposed as promising agents for the PET imaging of FR-overexpressing malignant neoplasms. In addition, radiolabeled folate-based conjugates can be effective for imaging non-tumor pathological foci characterized by a pronounced cluster of activated macrophages. We previously reported that a conjugate of folic acid with the NODAGA-chelator, labeled with gallium-68 and containing a (His-Glu)2-tag ([68Ga]Ga-NODAGA-[Lys-(HE)2]-folic acid), is suitable for imaging tumor lesions characterized by an increased density of FR. Introduction of the (His-Glu)2-tag into the structure of the folate radioconjugate significantly reduced its accumulation in non-target tissues (e.g., kidneys), leaving the accumulation in tumors at least at the same level, and even increasing it. The present study assessed the suitability of the developed molecule (in comparison with the unmodified analog) for imaging foci of non-oncological etiology characterized by a pronounced macrophage response. Systemic juvenile idiopathic arthritis (JIA), reproduced in Wistar rats, was used as the pathology model. Acute inflammatory processes of soft tissues of septic and aseptic etiologies were selected as differential models. The results obtained in this study showed a significantly elevated level of accumulation in the JIA focus compared to healthy rat paws and accumulation in the foci of differential models of the inflammatory process, which confirms the macrophage-mediated pathway of accumulation of the studied compounds. Simultaneously, the ratio of accumulation in pathology to accumulation in comparable healthy tissues in all studied pathologies was significantly high. The data obtained allowed us to conclude the diagnostic potential of new radiolabeled folate-based conjugate with (His-Glu)2-tag for pharmacokinetic property optimization in the radionuclide diagnosis of rheumatoid and other diseases characterized by a pronounced macrophage immune response. The mathematical compartment model quantitatively confirmed that the additional (His-Glu)2 fragment introduced in the molecule acts in favor of potential radiopharmaceutical use to visualize inflammatory processes by positron emission tomography.

Exogenous acetate attenuates inflammatory responses through HIF-1α-dependent glycolysis regulation in macrophage

Cytokine storm is a hallmark for acute systemic inflammatory disease like sepsis. Intrinsic microbiome-derived short-chain fatty acid (SCFAs) like acetate modulates immune cell function and metabolism has been well studied. However, it remains poorly investigated about the effects and the underlying mechanism of exogenous acetate in acute inflammation like sepsis. Here, we observed that serum acetate accumulates in patients undergoing abdominal gastrointestinal surgery and in septic mice. Short exposure to high-dose exogenous acetate protects mice from sepsis by inhibiting glycolysis in macrophages, both in vivo and in vitro. Hypoxia-inducible factor 1 subunit alpha (HIF-1α) stabilization or overexpression reverses the decreased glycolysis and pro-inflammatory cytokine production in macrophages and abrogates acetate’s protective effect in septic mice. Meanwhile, we also found acetyl-CoA synthetase-2, but not GPR41 or GPR43, plays a key role in acetate’s immunosuppressive effect. Acetate transiently increases acetyl-coenzyme A production, promoting histone acetylation and decreasing acetyl-transfer to NF-κB p65. These findings suggest that short exposure to mM-level acetate inhibits macrophage immune response linked to HIF-1α-dependent glycolysis. Taken together, we demonstrate short-term exposure of exogenous acetate could regulate inflammatory responses through attenuating HIF-1α-dependent glycolysis.

USP7 Inhibition Promotes Early Osseointegration in Senile Osteoporotic Mice

Although elderly osteoporotic patients have similar implant survival rates compared with those of normal individuals, they require longer healing periods to achieve proper osseointegration. This may be related to chronic inflammatory responses and impaired stem cell repair functions in the osteoporotic bone microenvironment. Recently, the deubiquitinating enzyme, ubiquitin-specific peptidase 7 (USP7), was found to regulate the macrophage immune response and modulate stem cell osteogenic differentiation. The selective inhibitor of USP7, P5091, has also been found to promote bone repair and homeostasis in osteoporotic conditions. However, the roles of USP7 and P5091 in osteoimmunology and dental implant osseointegration under senile osteoporotic conditions remain unclear. In this study, USP7 depletion and P5091 were shown to inhibit inflammation in senescent bone marrow–derived macrophages (BMDMs) and promote osteogenic differentiation in aged bone marrow mesenchymal stromal cells (BMSCs). Furthermore, mRNA-Seq revealed that USP7 depletion could enhance efferocytosis in senescent BMDMs through the EPSIN1/low-density lipoprotein receptor-related protein 1 (LRP1) pathway and selectively induce apoptosis (senolysis) in aged BMSCs. In senile osteoporotic mice, we found that the osseointegration period was prolonged compared with young mice, and P5091 promoted the early stage of osseointegration, which may be related to macrophage efferocytosis around the implant. Collectively, this study suggests that USP7 inhibition may accelerate the osseointegration process in senile osteoporotic conditions by promoting macrophage efferocytosis and aged BMSCs apoptosis. This has implications for understanding the cellular interactions and signaling mechanisms in the peri-implant bone microenvironment under osteoporotic conditions. It may also provide clinical significance in developing new therapies to enhance osseointegration quality and shorten the edentulous period in elderly osteoporotic patients.

In Vitro Antileishmanial and Immune Modulation of Trigonelline Against Leishmania major.

The mechanistic study of new pharmaceutical compounds is crucial for evaluating their efficacy, identifying potential side effects, and optimising drug formulations. This study aimed to investigate the mechanism of action of trigonelline on the promastigote and amastigote stages of Leishmania major (MRHO/IR/75/ER). An initial in silico study was conducted to examine the pharmacological effects of trigonelline using molecular docking to evaluate the potential binding affinity of trigonelline with nitrate, a crucial molecule in the macrophage immune response against Leishmania. In this experimental study, the inhibitory mechanism of trigonelline on promastigotes was evaluated by measuring metacaspase expression levels. In the amastigote stage of L. major, the expression levels of inducible nitric oxide synthase (iNOS), interleukin 12 (IL-12), interferon-gamma (IFN-γ), tumour necrosis factor alpha (TNF-α), transforming growth factor-β (TGF-β) and interleukin 10 (IL-10) genes were assessed using Real-time PCR. Trigonelline demonstrated a high-binding affinity to the iNOS molecule in computer modelling. In macrophages treated with various concentrations of trigonelline, glucantime and their combination, the expression levels of metacaspase, IL-12, TNF-α, IFN-γ and iNOS genes significantly increased compared to the control group (p < 0.05), whereas IL-10 and TGF-β gene expression levels significantly decreased (p < 0.05). Trigonelline exerts its antileishmanial effects through its high antioxidant properties, non-cytotoxicity to macrophages, and its ability to enhance apoptosis and cell cycle arrest in promastigotes of L. major.

Exploring the Antimycobacterial Potential of Podocarpusflavone A from Kielmeyera membranacea: In Vitro and In Vivo Insights.

Background/Objectives: Tuberculosis (TB) is one of the leading infectious causes of death worldwide, highlighting the importance of identifying new anti-TB agents. In previous research, our team identified antimycobacterial activity in Kielmeyera membranacea leaf extract; therefore, this study aims to conduct further exploration of its potential. Methods: Classical chromatography was applied for fractionation and spectrometric techniques were utilized for chemical characterization. For in vitro tests, samples were assessed against Mycobacterium tuberculosis and Mycobacterium marinum. The toxicity and efficacy of active samples were evaluated in vivo using different zebrafish models. Chemogenomics studies were applied to predict the isolated active compound's potential mode of action. Results: We performed fractionation of K. membranacea ethanolic extract (EE) and then its dichloromethane fraction (DCM), and the biflavonoid podocarpusflavone A (PCFA) was isolated and identified as a promising active compound. The EE and PCFA were found to be non-toxic to zebrafish larvae and were able to inhibit M. tuberculosis growth extracellularly. Additionally, PCFA demonstrated antimycobacterial activity within infected macrophages, especially when combined with isoniazid. In addition, the EE, DCM, and PCFA have shown the ability to inhibit M. marinum's growth during in vivo zebrafish larvae yolk infection. Notably, PCFA also effectively countered systemic infection established through the caudal vein, showing a similar inhibitory activity profile to rifampicin, both at 32 µM. A reduction in the transcriptional levels of pro-inflammatory cytokines confirmed the infection resolution. The protein tyrosine phosphatase B (PtpB) of M. tuberculosis, which inhibits the macrophage immune response, was predicted as a theoretical target of PCFA. This finding is in agreement with the higher activity observed for PCFA intracellularly and in vivo on zebrafish, compared with the direct action in M. tuberculosis. Conclusions: Here, we describe the discovery of PCFA as an intracellular inhibitor of M. tuberculosis and provide evidence of its in vivo efficacy and safety, encouraging its further development as a combination drug in novel therapeutic regimens for TB.

Chlamydia psittaci infection induces IFN-I and IL-1β through the cGAS-STING-IRF3/NLRP3 pathway via mitochondrial oxidative stress in human macrophages

Chlamydia psittaci (C. psittaci) is a multi-host pathogen that elicits robust innate immune responses in macrophages. Chlamydiae target host mitochondria to manipulate the cellular fate and metabolic functions. However, the effect of C. psittaci on the host mitochondria remains obscure. This study investigated how C. psittaci, post-infection in human macrophages, induces mitochondrial oxidative stress and damage to activate the cGAS-STING-IRF3/NLRP3 pathway for IFN-I and IL-1β production. Results demonstrate that C. psittaci increased mitochondrial ROS (mtROS) production. This induced the release of oxidized mitochondrial DNA (mtDNA) into the cytoplasm of macrophages. It also augmented IFN-I and IL-1β production dependent on the cGAS-STING pathway. Macrophages pre-treated with mtROS inhibitor mito-TEMPO displayed reduced oxidized mtDNA. This consequently lowered IFN-I and IL-1β production via the cGAS-STING pathway induced by C. psittaci. Additionally, we found that mtROS production may inhibit C. psittaci proliferation through the synergistic action of IFN-I and IL-1β. In conclusion, our study reveals that C. psittaci induces mtROS production leading to mtDNA release. This activates the cGAS-STING-IRF3/NLRP3 pathway to increase IFN-I and IL-1β production. This study elucidates a novel mechanism of bacterial pathogen activation in the cGAS-STING pathway. This reveals the molecular mechanisms underlying the immune response to C. psittaci infection and proposes potential targets for the treatment of C. psittaci related diseases.

PARP7i Clinical Candidate RBN-2397 Exerts Antiviral Activity by Modulating Interferon-β Associated Innate Immune Response in Macrophages.

Polyadenosine diphosphate-ribose polymerase 7 (PARP7) acts as a suppressor of the type I interferon (IFN) signaling pathway via suppressing TANK-binding protein 1 (TBK1). Research study indicates that inhibition of PARP7 could potentially regulate tumor immunity. However, the effect of PARP7 inhibition on innate antiviral immunity in macrophages as well as the underlying mechanism have not been demonstrated else well. We report herein that PARP7 inhibitor clinical candidate RBN-2397 could augment type I interferon (IFN-I) production in macrophages by elevating retinoic acid-inducible gene I (RIG-I) and stimulator of interferon genes (STING) signaling pathways. Treatment with RBN-2397 leads to increased pattern recognition ligands-induced interferon-β production in primary bone marrow-derived macrophages (BMDM) and RAW264.7 cells. Additionally, RBN-2397 suppresses viral replication efficiency in macrophages infected by vesicular stomatitis virus (VSV) and amplifies the expression of interferon-stimulated chemokine genes (ISGs). Mechanistically, RBN-2397 promotes TBK1 phosphorylation, consequently leading to the amplified activation of RIG-I and STING signaling pathways. Furthermore, RBN-2397 enhances the phosphorylation of signal transducer and activator of transcription 1 (STAT1) and STAT2 induced by IFN-α/β and the expression of chemokine genes in macrophages in response to IFN stimulation. In vivo experiments demonstrated that RBN-2397 enhances innate antiviral immunity in mice infected with VSV, resulting in increased serum IFN-β levels, reduced viral loads, and alleviated pulmonary inflammatory responses of the VSV-infected mice. In conclusion, our findings highlight the potential of RBN-2397 as a promising antiviral therapeutic agent for enhancing the IFN-relative antiviral immune defense in host.

Targeting Macrophage Phenotype for Treating Heart Failure: A New Approach.

Heart failure (HF) is a disease with high morbidity and mortality rates worldwide and significantly affects human health. Currently, the treatment options for HF are limited, and there is an urgent need to discover new therapeutic targets and strategies. Macrophages are innate immune cells involved in the development of HF. They play a crucial role in maintaining cardiac homeostasis and regulating cardiac stress. Recently, macrophages have received increasing attention as potential targets for treating HF. With the improvement of technological means, the study of macrophages in HF has made great progress. This article discusses the biological functions of macrophage phagocytosis, immune response, and tissue repair. The polarization, pyroptosis, autophagy, and apoptosis are of macrophages, deeply involved in the pathogenesis of HF. Modulation of the phenotypic changes of macrophages can improve immune-inflammation, myocardial fibrosis, energy metabolism, apoptosis, and angiogenesis in HF.

Novel 3D printed bioactive SiC orthopedic screw promotes bone growth associated activities by macrophages, neurons, and osteoblasts.

Ceramic additive manufacturing currently relies on binders or high-energy lasers, each with limitations affecting final product quality and suitability for medical applications. To address these challenges, our laboratory has devised a surface activation technique for ceramic particles that eliminates the necessity for polymer binders or high-energy lasers in ceramic additive manufacturing. We utilized this method to 3D print bioactive SiC orthopedic screws and evaluated their properties. The study's findings reveal that chemical oxidation of SiC activated its surface, enabling 3D printing of orthopedic screws in a binder jet printer. Post-processing impregnation with NaOH and/or NH4OH strengthened the scaffold by promoting silica crystallization or partial conversion of silicon oxide into silicon nitride. The silica surface of the SiC 3D printed orthopedic screws facilitated osteoblast and neuron adhesion and extensive axon synthesis. The silicate ions released from the 3D printed SiC screws favorably modulated macrophage immune responses toward an M1 phenotype as indicated by the inhibition of TNFα secretions and of reactive oxygen species (ROS) expression along with the promotion of IL6R shedding. In contrast, under the same experimental conditions, Ti ions released from Ti6Al4V discs promoted macrophage TNFα secretion and ROS expression. In vivo tests demonstrated direct bone deposition on the SiC scaffold and a strong interfacial bond between the implanted SiC and bone. Immunostaining showed innervation, mineralization, and vascularization of the newly formed bone at the interface with SiC. Taken altogether, the 3D printed SiC orthopedic screws foster a favorable environment for wound healing and bone regeneration. The novel 3D printing method, based on ceramic surface activation represents a significant advancement in ceramic additive manufacturing and is applicable to a wide variety of materials.

Activation Pathways of Murine Macrophages by Lipophosphoglycan from Strains of Leishmania major (FV1 and LV39).

Lipophosphoglycan (LPG) is an important Leishmania virulence factor. It is the most abundant surface glycoconjugate in promastigotes, playing an important role in the interaction with phagocytic cells. While LPG is known to modulate the macrophage immune response during infection, the activation mechanisms triggered by this glycoconjugate have not been fully elucidated. This work investigated the role that LPGs purified from two strains of Leishmania major (FV1 and LV39) play in macrophage activation, considering the differences in their biochemical structures. Bone marrow-derived macrophages from BALB/c mice were stimulated with 10 μg/mL purified LPG from the LV39 and FV1 strains. We then measured the production of nitric oxide (NO) and cytokines, the expression of inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2), and the activation of MAPK pathways. LPG from the LV39 strain, which has longer poly-galactosylated side chains, induced a more pro-inflammatory profile than that from the FV1 strain. This included higher production of NO, TNF-α, and PGE2, and increased expression of COX-2 and iNOS. Additionally, the phosphorylation of ERK-1/2 and JNK was elevated in macrophages exposed to LPG from the LV39 strain. No difference in IL-10 production was observed in cells stimulated by both LPG. Thus, intraspecific structural differences in LPG contribute to distinct innate immune responses in macrophages.

The miR-26a/SIRT6/HIF-1α axis regulates glycolysis and inflammatory responses in host macrophages during Mycobacterium tuberculosis infection.

Mycobacterium tuberculosis (Mtb) is the causative agent of tuberculosis. Here, a macrophage infection model was used to unravel the role of the histone deacetylase sirtuin 6 (SIRT6) in Mtb-triggered regulation of the innate immune response. Mtb infection downregulated microRNA-26a and upregulated its target SIRT6. SIRT6 suppressed glycolysis and expression of HIF-1α-dependent glycolytic genes during infection. In addition, SIRT6 regulated the levels of intracellular succinate which controls stabilization of HIF-1α, as well as the release of interleukin (IL)-1β. Furthermore, SIRT6 inhibited inducible nitric oxide synthase (iNOS) and proinflammatory IL-6 but augmented anti-inflammatory arginase expression. The miR-26a/SIRT6/HIF-1α axis therefore regulates glycolysis and macrophage immune responses during Mtb infection. Our findings link SIRT6 to rewiring of macrophage signaling pathways facilitating dampening of the antibacterial immune response.

Involvement of mitochondrial fatty acid β-oxidation in the antiviral innate immune response in head kidney macrophages of large yellow croaker (Larimichthys crocea)

As a vital pathway for cellular energy production, mitochondrial fatty acid β-oxidation (FAO) is essential in regulating immune responses to bacterial pathogens and maintaining intracellular homeostasis in vertebrates. However, the specific role of FAO in antiviral innate immune response in macrophages remains insufficiently understood. In this study, virus infection simulated by poly(I:C) inhibited FAO, as indicated by the reduced expression of FAO-related genes and proteins in the head kidney of large yellow croaker, with similar results observed in poly(I:C)-stimulated macrophages. Then, inhibition of FAO by supplementary mildronate in vivo and etomoxir treatment in vitro revealed varying increases in the mRNA expression of antiviral innate immune response genes after stimulated by poly(I:C) in the head kidney and macrophages. Notably, etomoxir significantly facilitated the transcriptional up-regulation of the IFNh promoter by IRF3. Moreover, inhibiting FAO by knockdown of cpt1b promoted antiviral innate immune response triggered by poly(I:C) in macrophages. Conversely, activating FAO through overexpression of cpt1b or cpt2 significantly reduced the mRNA levels of antiviral response genes in macrophages stimulated by poly(I:C). Unlike etomoxir, cpt1b overexpression inhibited the transcriptional up-regulation of the IFNh promoter by IRF3. Furthermore, in vivo dietary palm oil feeding and in vitro exposure to palmitic acid inhibited the antiviral innate immune response triggered by poly(I:C) in the head kidney and macrophages, respectively. These effects were partly associated with FAO activation, as evidenced by etomoxir. In summary, this study elucidates FAO's critical role in regulating antiviral innate immune response in head kidney macrophages. These findings not only deepen insights into the interaction between metabolic remodeling and host immune responses, but also offer valuable guidance for developing nutritional strategies to improve antiviral immunity in aquaculture.