Macrophage Transition Research Articles

Retinoic acid ameliorates rheumatoid arthritis by attenuating inflammation and modulating macrophage polarization through MKP-1/MAPK signaling pathway.

Macrophages are innate immune cells connected with the development of inflammation. Retinoic acid has previously been proved to have anti-inflammatory and anti-arthritic properties. However, the exact mechanism through which retinoic acid modulates arthritis remains unclear. This study aimed to investigate whether retinoic acid ameliorates rheumatoid arthritis by modulating macrophage polarization. This study used retinoic acid to treat mice with adjuvant arthritis and evaluated anti-inflammatory effects by arthritis score, thermal nociceptive sensitization test, histopathologic examination and immunofluorescence assays. In addition, its specific anti-arthritic mechanism was investigated by flow cytometry, cell transfection and inflammatory signaling pathway assays in RAW264.7 macrophages in vitro. Retinoic acid significantly relieved joint pain and attenuated inflammatory cell infiltration in mice. Furthermore, this treatment modulated peritoneal macrophage polarization, increased levels of arginase 1, as well as decreased inducible nitric oxide synthase expression. In vitro, we verified that retinoic acid promotes macrophage transition from the M1 to M2 type by upregulating mitogen-activated protein kinase (MAPK) phosphatase 1 (MKP-1) expression and inhibiting P38, JNK and ERK phosphorylation in lipopolysaccharide-stimulated RAW264.7 cells. Notably, the therapeutic effects of retinoic acid were inhibited by MKP-1 knockdown. Retinoic acid exerts a significant therapeutic effect on adjuvant arthritis in mice by regulating macrophage polarization through the MKP-1/MAPK pathway, and play an important role in the treatment of rheumatic diseases.

Abstract 4113617: Single-cell Analysis Reveals Endothelial Cell CD45 Deficiency Prevents Endothelial-to-Mesenchymal Transition (EndMT) in Atherosclerosis

Introduction: Protein-tyrosine-phosphatase CD45 is exclusively expressed in all nucleated cells of the hematopoietic system but is rarely expressed in endothelial cells (ECs). However, a recent study indicated that activation of the endogenous CD45 promoter in human endothelial colony forming cells induced expression of EndMT marker genes. Also, the CD45 phosphatase inhibitor blocked EndMT activities in TGFβ1-treated ovine mitral valve endothelial cells. EndMT contributes to atherosclerotic pathobiology and is associated with more complex plaques. We identified CD45-positive ECs undergoing EndMT in atherosclerotic ApoE-deficient (ApoE -/- ) mice. Here, we aim to investigate whether endothelial CD45-specific deletion can prevent EndMT in a mouse model of atherosclerosis. Methods and Results: We generated a tamoxifen-inducible EC-specific CD45-deficient mouse strain (EC-iCD45KO) on an ApoE -/- background (C57BL/6) and fed these mice a Western diet for 16 weeks. We isolated and enriched mouse aortic endothelial cells with CD31 beads to perform single-cell RNA-seq. Cells populated 15 major clusters after integrating the single-cell transcriptomic profiles. In the EC-iCD45KO group, the population of endothelial, resident macrophage, and mesenchymal-endothelial transition cells increased while vascular smooth muscle, EndMT, and fibroblast cells decreased. In EndMT cells, EC markers (Cdh5, Cldn5, Pecam1) increased, but SMC markers (Acta2) and EndMT markers (Col1a2 and Col3a1）decreased. In addition, we characterized EndMT cells into two sub-clusters: 1 and 2. EC-specific CD45 deletions reduced the cell numbers in the EndMT2 sub-cluster in atherosclerotic mice but had less impact on the EndMT1 sub-cluster. FGFR pathways were potentiated while TGFβ1 and Tgfbr2 decreased in EndMT1 sub-cluster， and the genes controlling endothelial cell development were upregulated but the genes controlling actin cytoskeleton organization were downregulated in both EndMT1 and 2 sub-clusters. Conclusion: Our single-cell analysis indicates that the loss of endothelial CD45 protects against EndMT-driven atherosclerosis, inhibiting TGFβ and EndoMT marker expression while stimulating FGFR pathways. Consistently, EC-iCD45KO/ApoE -/- mice showed reduced plaque macrophages, expression of cell adhesion molecules, foam cell formation, and lesion development when compared to ApoE -/- controls. Thus, targeting endothelial CD45 may be a novel therapeutic strategy for EndMT and atherosclerosis.

In Vitro Assessment of the Neuroprotective Effects of Pomegranate (Punica granatum L.) Polyphenols Against Tau Phosphorylation, Neuroinflammation, and Oxidative Stress.

Oxidative stress and chronic inflammation, at both the systemic and the central level, are critical early events in atherosclerosis and Alzheimer's disease (AD). To investigate the oxidative stress-, inflammation-, and Tau-phosphorylation-lowering effects of pomegranate polyphenols (PPs) (punicalagin, ellagic acid, peel, and aril extracts). We used flow cytometry to quantify the protein expression of proinflammatory cytokines (IL-1β) and anti-inflammatory mediators (IL-10) in THP-1 macrophages, as well as M1/M2 cell-specific marker (CD86 and CD163) expression in human microglia HMC3 cells. The IL-10 protein expression was also quantified in U373-MG human astrocytes. The effect of PPs on human amyloid beta 1-42 (Aβ1-42)-induced oxidative stress was assessed in the microglia by measuring ROS generation and lipid peroxidation, using 2',7'-dichlorofluorescein diacetate (DCFH-DA) and thiobarbituric acid reactive substance (TBARS) tests, respectively. Neuronal viability and cell apoptotic response to Aβ1-42 toxicity were assayed using the MTT (3-(4,5-dimethylthiazolyl-2)-2,5-diphenyltetrazolium bromide) assay and the annexin-V-FITC apoptosis detection kit, respectively. Finally, flow cytometry analysis was also performed to evaluate the ability of PPs to modulate Aβ1-42-induced Tau-181 phosphorylation (pTau-181). Our data indicate that PPs are significantly (p < 0.05) effective in countering Aβ1-42-induced inflammation through increasing the anti-inflammatory cytokines (IL-10) in U373-MG astrocytes and THP1 macrophages and decreasing proinflammatory marker (IL-1β) expression in THP1 macrophages. The PPs were also significantly (p < 0.05) effective in inducing the phenotypic transition of THP-1 macrophages and microglial cells from M1 to M2 by decreasing CD86 and increasing CD163 surface receptor expression. Moreover, our treatments have a significant (p < 0.05) beneficial impact on oxidative stress, illustrated in the reduction in TBARS and ROS generation. Our treatments have significant (p < 0.05) cell viability improvement capacities and anti-apoptotic effects on human H4 neurons. Furthermore, our results suggest that Aβ1-42 significantly (p < 0.05) increases pTau-181. This effect is significantly (p < 0.05) attenuated by arils, peels, and punicalagin and drastically reduced by the ellagic acid treatment. Overall, our results attribute to PPs anti-inflammatory, antioxidant, anti-apoptotic, and anti-Tau-pathology potential. Future studies should aim to extend our knowledge of the potential role of PPs in Aβ1-42-induced neurodegeneration, particularly concerning its association with the tauopathy involved in AD.

The STAT3/SETDB2 axis dictates NF-κB-mediated inflammation in macrophages during wound repair.

Macrophage transition from an inflammatory to reparative phenotype after tissue injury is controlled by epigenetic enzymes that regulate inflammatory gene expression. We have previously identified that the histone methyltransferase SETDB2 in macrophages drives tissue repair by repressing NF-κB-mediated inflammation. Complementary ATAC-Seq and RNA-Seq of wound macrophages isolated from mice deficient in SETDB2 in myeloid cells revealed that SETDB2 suppresses the inflammatory gene program by inhibiting chromatin accessibility at NF-κB-dependent gene promoters. We found that STAT3 was required for SETDB2 expression in macrophages, yet paradoxically, it also functioned as a binding partner of SETDB2 where it repressed SETDB2 activity by inhibiting its interaction with the NF-κB component, RELA, leading to increased RELA/NF-κB-mediated inflammatory gene expression. Furthermore, RNA-Seq in wound macrophages from STAT3-deficient mice corroborated this and revealed STAT3 and SETDB2 transcriptionally coregulate overlapping genes. Finally, in diabetic wound macrophages, STAT3 expression and STAT3/SETDB2 binding were increased. We have identified what we believe to be a novel STAT3/SETDB2 axis that modulates macrophage phenotype during tissue repair and may be an important therapeutic target for nonhealing diabetic wounds.

SFRP2 modulates functional phenotype transition and energy metabolism of macrophages during diabetic wound healing.

Diabetic foot ulcer (DFU) is a serious complication of diabetes mellitus, which causes great health damage and economic burden to patients. The pathogenesis of DFU is not fully understood. We screened wound healing-related genes using bioinformatics analysis, and full-thickness skin injury mice model and cellular assays were used to explore the role of target genes in diabetic wound healing. SFRP2 was identified as a wound healing-related gene, and the expression of SFRP2 is associated with immune cell infiltration in DFU. In vivo study showed that suppression of SFRP2 delayed the wound healing process of diabetic mice, impeded angiogenesis and matrix remodeling, but did not affect wound healing process of control mice. In addition, suppression of SFRP2 increased macrophage infiltration and impeded the transition of macrophages functional phenotypes during diabetic wound healing, and affected the transcriptome signatures-related to inflammatory response and energy metabolism at the early stage of wound healing. Extracellular flux analysis (EFA) showed that suppression of SFRP2 decreased mitochondrial energy metabolism and increased glycolysis in injury-related macrophages, but impeded both glycolysis and mitochondrial energy metabolism in inflammatory macrophages. In addition, suppression of SFRP2 inhibited wnt signaling-related genes in macrophages. Treatment of AAV-SFRP2 augmented wound healing in diabetic mice and demonstrated the therapeutic potential of SFRP2. In conclusions, SFRP2 may function as a wound healing-related gene in DFU by modulating functional phenotype transition of macrophages and the balance between mitochondrial energy metabolism and glycolysis.

Sporidiobolus pararoseus polysaccharides relieve rheumatoid arthritis by regulating arachidonic acid metabolism and bone remodeling signaling pathway

Rheumatoid arthritis (RA) is an autoimmune-mediated disease with the highest disability rate. Sporidiobolus pararoseus polysaccharides (SPP) have been demonstrated to have anti-rheumatoid and microbiota-modulatory effects; however, the underlying mechanisms remain unclear. This study employed collagen-induced arthritis (CIA) mice to explore the metabolic and genetic pathways. The results revealed SPP intervention significantly reduced the serum levels of rheumatoid and pro-inflammatory complement factors. SPP promoted the transition of macrophages of CIA mice toward the M2 phenotype (F4/80+/CD206+) from an inflammatory phenotype (F4/80+/CD86+) using flow cytometry analysis. A total of 44 metabolites were upregulated, and 110 metabolites were significantly downregulated by SPP compared to those in RA group. The decreased metabolites, 12(S)-HPETE, prostaglandin H2, 15-HETE, hepoxilin B3, and 15-keto-prostaglandin F2a, were mostly enriched in arachidonic acid metabolism (enrichment = 11.4 %), which was highly correlated with the anti-rheumatic activity of SPP. Gene expression analysis revealed that SPP significantly regulated OPG/RANKL/TRAF6 signaling pathway, stimulating osteogenic remodeling. Furthermore, arachidonic acid metabolism was identified as the critical metabolic driver of RA phenotypes and osteoclast differentiation, potentially associated with SPP-reshaped intestinal microbiota (i.e., Rikenellaceae_RC9_gut_group, Bacteroides, and Parabacteroides). Collectively, this study utilized an integrated approach of metabolomics and gene expression analysis to investigate the regulatory role of SPP in RA progression.

Sono-Catalytic Tooth Whitening and Oral Health Enhancement with Oxygen Vacancies-Enriched Mesoporous TiO2 Nanospheres: A Nondestructive Approach for Daily Tooth Care.

Tooth discoloration and the breeding of oral microorganisms pose threats to both one's aesthetic appearance and oral health. Clinical whitening agents based on H2O2 with high concentrations are effective in tooth whitening and bacterial elimination but may also cause enamel demineralization, gingival irritation, or cytotoxicity, necessitating professional supervision. Herein, leveraging sono-catalysis effects, a nondestructive and convenient tooth whitening strategy was developed, utilizing oxygen vacancies (OVs)-enriched mesoporous TiO2 nanospheres. The introduction of OVs leads to TiO2 bandgap narrowing, boosting the generation of reactive oxygen species (ROS) by TiO2 under ultrasound treatment. Additionally, through the chemocatalysis effect, the ROS yield can be further augmented by employing OVs-enriched TiO2 in conjunction with an extremely low concentration of H2O2 (1%) during ultrasound treatment. Hence, under ultrasound treatment simulating daily tooth brushing using an electronic toothbrush, the combination of OVs-enriched TiO2 and 1% H2O2 proves to be effective in whitening teeth stained by tea, coffee, and mix juice. Furthermore, the combination of OVs-enriched TiO2 and 1% H2O2 demonstrates potent bacterial-killing and biofilm-eradicating effects under ultrasound treatment within an extremely short duration (5 min). Additionally, given the mesoporous structure, curcumin, serving as an anti-inflammatory agent, can be efficiently loaded into OVs-enriched TiO2 and then controllably released through ultrasound treatment. The curcumin-loaded TiO2 facilitates the transition of macrophages to the anti-inflammatory M2 phenotype, potentially alleviating oral inflammation induced by bacterial infection without showing any biotoxicity. The OVs-enriched TiO2 based sono-catalysis tooth whitening procedure provides the convenience of whitening teeth during daily brushing without requiring professional supervision.

CXCR4 regulates macrophage M1 polarization by altering glycolysis to promote prostate fibrosis

BackgroundC-X-C receptor 4(CXCR4) is widely considered to be a highly conserved G protein-coupled receptor, widely involved in the pathophysiological processes in the human body, including fibrosis. However, its role in regulating macrophage-related inflammation in the fibrotic process of prostatitis has not been confirmed. Here, we aim to describe the role of CXCR4 in modulating macrophage M1 polarization through glycolysis in the development of prostatitis fibrosis.MethodsUse inducible experimental chronic prostatitis as a model of prostatic fibrosis. Reduce CXCR4 expression in immortalized bone marrow-derived macrophages using lentivirus. In the fibrotic mouse model, use adenovirus carrying CXCR4 agonists to detect the silencing of CXCR4 and assess the in vivo effects.ResultsIn this study, we demonstrated that reducing CXCR4 expression during LPS treatment of macrophages can alleviate M1 polarization. Silencing CXCR4 can inhibit glycolytic metabolism, enhance mitochondrial function, and promote macrophage transition from M1 to M2. Additionally, in vivo functional experiments using AAV carrying CXCR4 showed that blocking CXCR4 in experimental autoimmune prostatitis (EAP) can alleviate inflammation and experimental prostate fibrosis development. Mechanistically, CXCR4, a chemokine receptor, when silenced, weakens the PI3K/AKT/mTOR pathway as its downstream signal, reducing c-MYC expression. PFKFB3, a key enzyme involved in glucose metabolism, is a target gene of c-MYC, thus impacting macrophage polarization and glycolytic metabolism processes.

Engineered Enucleated Mesenchymal Stem Cells Regulating Immune Microenvironment and Promoting Wound Healing.

Persistent excessive inflammation caused by neutrophil and macrophage dysfunction in the wound bed leads to refractory response during wound healing. However, previous studies using cytokines or drugs often suffer from short half-lives and limited targeting, resulting in unsatisfactory therapeutic effects. Herein, the enucleated mesenchymal stem cell is engineered by aptamer bioorthogonal chemistry to modify the cell membrane and mRNA loading in the cell cytoplasm as a novel delivery vector (Cargocyte) with accurate targeting and sustained cytokine secretion. Cargocytes can successfully reduce NETosis by targeting the nuclear chromatin protein DEK protein with aptamers and sustaining interleukin (IL)-4 expression to overcome the challenges associated with the high cost and short half-life of IL-4 protein and significantly prevent the transition of macrophages into the M1 phenotype. Therapeutic effects have been demonstrated in murine and porcine wound models and have powerful potential to improve wound immune microenvironments effectively. Overall, the use of engineered enucleated mesenchymal stem cells as a delivery system may be a promising approach for wound healing.

Canine mesenchymal stem cell-derived exosomes attenuate renal ischemia-reperfusion injury through miR-146a-regulated macrophage polarization.

The most common factor leading to renal failure or death is renal IR (ischemia-reperfusion). Studies have shown that mesenchymal stem cells (MSCs) and their exosomes have potential therapeutic effects for IR injury by inhibiting M1 macrophage polarization and inflammation. In this study, the protective effect and anti-inflammatory mechanism of adipose-derived mesenchymal stem cell-derived exosomes (ADMSC-Exos) after renal IR were investigated. Initially, ADMSC-Exos were intravenously injected into IR experimental beagles, and the subsequent assessment focused on inflammatory damage and macrophage phenotype. Furthermore, an in vitro inflammatory model was established by inducing DH82 cells with LPS. The impact on inflammation and macrophage phenotype was then evaluated using ADMSC and regulatory miR-146a. Following the administration of ADMSC-Exos in IR canines, a shift from M1 to M2 macrophage polarization was observed. Similarly, in vitro experiments demonstrated that ADMSC-Exos enhanced the transformation of LPS-induced macrophages from M1 to M2 type. Notably, the promotion of macrophage polarization by ADMSC-Exos was found to be attenuated upon the inhibition of miR-146a in ADMSC-Exos. These findings suggest that miR-146a plays a significant role in facilitating the transition of LPS-induced macrophages from M1 to M2 phenotype. As a result, the modulation of macrophage polarization by ADMSC-Exos is achieved via the encapsulation and conveyance of miR-146a, leading to diminished infiltration of inflammatory cells in renal tissue and mitigation of the inflammatory reaction following canine renal IR.

The alternative polyadenylation regulator CFIm25 promotes macrophage differentiation and activates the NF-κβ pathway.

Macrophages are required for our body's development and tissue repair and protect against microbial attacks. We previously reported a crucial role for regulation of mRNA 3'-end cleavage and polyadenylation (C/P) in monocyte to macrophage differentiation. The CFIm25 subunit of the C/P complex showed a striking increase upon differentiation of monocytes with Phorbol Myristate Acetate, suggesting that it promotes this process. To test this hypothesis, CFIm25 was overexpressed in two different monocytic cell lines, followed by differentiation. Both cell lines showed a significant increase in macrophage characteristics and an earlier slowing of the cell cycle. In contrast, depletion of CFIm25 hindered differentiation. Cell cycle slowing upon CFIm25 overexpression was consistent with a greater decrease in the proliferation markers PCNA and cyclin D1, coupled with increased 3'UTR lengthening of cyclin D1 mRNA. Since choice of other poly(A) sites could be affected by manipulating CFIm25, we identified additional genes with altered use of poly(A) sites during differentiation and examined how this changed upon CFIm25 overexpression. The mRNAs of positive regulators of NF-κB signaling, TAB2 and TBL1XR1, and NFKB1, which encodes the NF-κB p50 precursor, underwent 3'UTR shortening that was associated with increased protein expression compared to the control. Cells overexpressing CFIm25 also showed elevated levels of phosphorylated NF-κB-p65 and the NF-κB targets p21, Bcl-XL, ICAM1 and TNF-α at an earlier time and greater resistance to NF-κB chemical inhibition. In conclusion, our study supports a model in which CFIm25 accelerates the monocyte to macrophage transition by promoting alternative polyadenylation events which lead to activation of the NF-κB pathway.

IKKε-deficient macrophages impede cardiac repair after myocardial infarction by enhancing the macrophage–myofibroblast transition

The regulatory role of the inhibitor of NF-kB kinase ε (IKKε) in postmyocardial infarction (MI) inflammation remains uncertain. Using an MI mouse model, we examined the cardiac outcomes of IKKε knockout (KO) mice and wild-type mice. We employed single-cell RNA sequencing (scRNA-seq) and phosphorylated protein array techniques to profile cardiac macrophages. IKKε KO mice exhibited compromised survival, heightened inflammation, pronounced cardiac fibrosis, and a reduced ejection fraction. A distinct cardiac macrophage subset in IKKε KO mice exhibited increased fibrotic marker expression and decreased phosphorylated p38 (p-p38) levels, indicating an enhanced macrophage–myofibroblast transition (MMT) post-MI. While cardiac inflammation is crucial for initiating compensatory pathways, the timely resolution of inflammation was impaired in the IKKε KO group, while the MMT in macrophages accelerated post-MI, leading to cardiac failure. Additionally, our study highlighted the potential of 5-azacytidine (5-Aza), known for its anti-inflammatory and cardioprotective effects, in restoring p-p38 levels in stimulated macrophages. The administration of 5-Aza significantly reduced the MMT in cardiac macrophages from the IKKε KO group. These findings underscore the regulation of the inflammatory response and macrophage transition by the IKKε-p38 axis, indicating that the MMT is a promising therapeutic target for ischemic heart disease.

Natural compound phloretin restores periodontal immune homeostasis via HIF-1α-regulated PI3K/Akt and glycolysis in macrophages

Periodontitis is a chronic inflammatory disease that affects about 45 %-50 % of adults worldwide, but the efficacy of current clinical therapies is unsatisfactory due to the complicated periodontal immune microenvironment. Thus, developing drugs that can regulate innate immune cells (e.g., macrophages) is a potent strategy to treat periodontitis. Here, we report that phloretin, a food plant-derived natural compound, is sufficient to alleviate periodontitis through immune regulation. In vivo, phloretin treatment could significantly reduce alveolar bone resorption and periodontal inflammation in mouse periodontitis models. In vitro, phloretin could suppress proinflammatory (M1-like) polarization and cytokine release in macrophages induced by LPS. Mechanistically, the immune regulatory role of phloretin in macrophages may be due to its metabolic regulation effect. Phloretin might restore the balance of M1/M2 macrophage transition in periodontitis by inhibiting HIF-1α-mediated glycolysis and PI3k/Akt pathways, thereby reducing the proinflammatory effect and immune disorder caused by over-activated M1 macrophages. Together, this study highlights that natural compound, such as phloretin, can restore periodontal immune homeostasis by metabolic regulation of macrophages, which may provide novel insight into the treatment of periodontitis.

Identification of a Novel ECM Remodeling Macrophage Subset in AKI to CKD Transition by Integrative Spatial and Single-Cell Analysis.

The transition from acute kidney injury (AKI) to chronic kidney disease (CKD) is a critical clinical issue. Although previous studies have suggested macrophages as a key player in promoting inflammation and fibrosis during this transition, the heterogeneity and dynamic characterization of macrophages are still poorly understood. Here, we used integrated single-cell RNA sequencing and spatial transcriptomic to characterize the spatiotemporal heterogeneity of macrophages in murine AKI-to-CKD model of unilateral ischemia-reperfusion injury. A marked increase in macrophage infiltration at day 1 was followed by a second peak at day 14 post AKI. Spatiotemporal profiling revealed that injured tubules and macrophages co-localized early after AKI, whereas in late chronic stages had spatial proximity to fibroblasts. Further pseudotime analysis revealed two distinct lineages of macrophages in this transition: renal resident macrophages differentiated into the pro-repair subsets, whereas infiltrating monocyte-derived macrophages contributed to chronic inflammation and fibrosis. A novel macrophage subset, extracellular matrix remodeling-associated macrophages (EAMs) originating from monocytes, linked to renal fibrogenesis and communicated with fibroblasts via insulin-like growth factors (IGF) signalling. In sum, our study identified the spatiotemporal dynamics of macrophage heterogeneity with a unique subset of EAMs in AKI-to-CKD transition, which could be a potential therapeutic target for preventing CKD development.

TLR4/TNFR1 blockade suppresses STAT1/STAT3 expression and increases SOCS3 expression in modulation of LPS-induced macrophage responses

Due to the urgent need to create appropriate treatment techniques, which are currently unavailable, LPS-induced sepsis has become a serious concern on a global scale. The primary active component in the pathophysiology of inflammatory diseases such as sepsis is the Gram-negative bacterial lipopolysaccharide (LPS). LPS interacts with cell surface TLR4 in macrophages, causing the formation of reactive oxygen species (ROS), TNF-α, IL-1β and oxidative stress. It also significantly activates the MAPKs and NF-κB pathway. Excessive production of pro-inflammatory cytokines is one of the primary characteristic features in the onset and progression of inflammation. Cytokines mainly signal through the JAK/STAT pathway. We hypothesize that blocking of TLR4 along with TNFR1 might be beneficial in suppressing the effects of STAT1/STAT3 due to the stimulation of SOCS3 proteins. Prior to the LPS challenge, the macrophages were treated with antibodies against TLR4 and TNFR1 either individually or in combination. On analysis of the macrophage populations by flowcytometry, it was seen that receptor blockade facilitated the phenotypic shift of the M1 macrophages towards M2 resulting in lowered oxidative stress. Blocking of TLR4/TNFR1 upregulated the SOCS3 and mTOR expressions that enabled the transition of inflammatory M1 macrophages towards the anti-inflammatory M2 phenotype, which might be crucial in curbing the inflammatory responses. Also the reduction in the production of inflammatory cytokines such as IL-6, IL-1β due to the reduction in the activation of the STAT1 and STAT3 molecules was observed in our combination treatment group. All these results indicated that neutralization of both TLR4 and TNFR1 might provide new insights in establishing an alternative therapeutic strategy for LPS-sepsis.

CAMP signaling of Bordetella adenylate cyclase toxin blocks M-CSF triggered upregulation of iron acquisition receptors on differentiating CD14+ monocytes.

Bordetella pertussis infects the upper airways of humans and disarms host defense by the potent immuno-subversive activities of its pertussis (PT) and adenylate cyclase (CyaA) toxins. CyaA action near-instantly ablates the bactericidal activities of sentinel CR3-expressing myeloid phagocytes by hijacking cellular signaling pathways through the unregulated production of cAMP. Moreover, CyaA-elicited cAMP signaling also inhibits the macrophage colony-stimulating factor (M-CSF)-induced differentiation of incoming inflammatory monocytes into bactericidal macrophages. We show that CyaA/cAMP signaling via protein kinase A (PKA) downregulates the M-CSF-elicited expression of monocyte receptors for transferrin (CD71) and hemoglobin-haptoglobin (CD163), as well as the expression of heme oxygenase-1 (HO-1) involved in iron liberation from internalized heme. The impact of CyaA action on CD71 and CD163 levels in differentiating monocytes is largely alleviated by the histone deacetylase inhibitor trichostatin A (TSA), indicating that CyaA/cAMP signaling triggers epigenetic silencing of genes for micronutrient acquisition receptors. These results suggest a new mechanism by which B. pertussis evades host sentinel phagocytes to achieve proliferation on airway mucosa.IMPORTANCETo establish a productive infection of the nasopharyngeal mucosa and proliferate to sufficiently high numbers that trigger rhinitis and aerosol-mediated transmission, the pertussis agent Bordetella pertussis deploys several immunosuppressive protein toxins that compromise the sentinel functions of mucosa patrolling phagocytes. We show that cAMP signaling elicited by very low concentrations (22 pM) of Bordetella adenylate cyclase toxin downregulates the iron acquisition systems of CD14+ monocytes. The resulting iron deprivation of iron, a key micronutrient, then represents an additional aspect of CyaA toxin action involved in the inhibition of differentiation of monocytes into the enlarged bactericidal macrophage cells. This corroborates the newly discovered paradigm of host defense evasion mechanisms employed by bacterial pathogens, where manipulation of cellular cAMP levels blocks monocyte to macrophage transition and replenishment of exhausted phagocytes, thereby contributing to the formation of a safe niche for pathogen proliferation and dissemination.

Enhanced fibrocartilage regeneration at the tendon-bone interface injury through extracellular matrix hydrogel laden with bFGF-overexpressing human urine-derived stem cells

The tendon-bone interface (TBI) is crucial in the transfer of mechanical loads; however, it is susceptible to injuries that frequently result in healing via fibrous scar tissue formation. Consequently, regeneration of the fibrocartilaginous zone has become a pivotal area subject. At present, the use of stem cells represents a notably promising approach for TBI treatment. Especially, human urine-derived stem cells (hUSCs) present a practical option for cell-based therapies. Nevertheless, the chondrogenic differentiation potential of hUSCs is limited. To address this, basic fibroblast growth factor (bFGF) was transinfected into hUSCs to bolster their differentiation capacity and facilitate the formation of fibrocartilage in the target area. Additionally, the local immune microenvironment dramatically influences TBI healing, with macrophages playing a vital role. Effective healing relies on the phenotype transition of macrophages, with an imbalance often leading to insufficient regeneration and scar tissue formation. Innovations in biomaterials have provided new avenues for TBI repair, such as the porcine small intestinal submucosa (SIS) hydrogel developed in our prior research. In addition to serving as a carrier for stem cell delivery, the hydrogel’s bioactive components support tissue repair and immune regulation. In the present study, SIS hydrogel loaded with hUSCs that overexpress bFGF was used for the treatment of TBI injury, which is expected to correct inflammatory response imbalances, and promote macrophage polarization towards healing phenotypes, creating a favorable immune microenvironment. The combined effects of bFGF and the optimized immune setting are anticipated to enhance hUSCs’ chondrogenic potential, aiding in the functional restoration of TBI injuries.

Excessive accumulation of epicardial adipose tissue promotes microvascular obstruction formation after myocardial ischemia/reperfusion through modulating macrophages polarization

BackgroundOwing to its unique location and multifaceted metabolic functions, epicardial adipose tissue (EAT) is gradually emerging as a new metabolic target for coronary artery disease risk stratification. Microvascular obstruction (MVO) has been recognized as an independent risk factor for unfavorable prognosis in acute myocardial infarction patients. However, the concrete role of EAT in the pathogenesis of MVO formation in individuals with ST-segment elevation myocardial infarction (STEMI) remains unclear. The objective of the study is to evaluate the correlation between EAT accumulation and MVO formation measured by cardiac magnetic resonance (CMR) in STEMI patients and clarify the underlying mechanisms involved in this relationship.MethodsFirstly, we utilized CMR technique to explore the association of EAT distribution and quantity with MVO formation in patients with STEMI. Then we utilized a mouse model with EAT depletion to explore how EAT affected MVO formation under the circumstances of myocardial ischemia/reperfusion (I/R) injury. We further investigated the immunomodulatory effect of EAT on macrophages through co-culture experiments. Finally, we searched for new therapeutic strategies targeting EAT to prevent MVO formation.ResultsThe increase of left atrioventricular EAT mass index was independently associated with MVO formation. We also found that increased circulating levels of DPP4 and high DPP4 activity seemed to be associated with EAT increase. EAT accumulation acted as a pro-inflammatory mediator boosting the transition of macrophages towards inflammatory phenotype in myocardial I/R injury through secreting inflammatory EVs. Furthermore, our study declared the potential therapeutic effects of GLP-1 receptor agonist and GLP-1/GLP-2 receptor dual agonist for MVO prevention were at least partially ascribed to its impact on EAT modulation.ConclusionsOur work for the first time demonstrated that excessive accumulation of EAT promoted MVO formation by promoting the polarization state of cardiac macrophages towards an inflammatory phenotype. Furthermore, this study identified a very promising therapeutic strategy, GLP-1/GLP-2 receptor dual agonist, targeting EAT for MVO prevention following myocardial I/R injury.

Curcumin-Encapsulated Co-ZIF-8 for Ulcerative Colitis Therapy: ROS Scavenging and Macrophage Modulation Effects.

Ulcerative colitis (UC) is a chronic inflammatory bowel disease characterized by the disruption of the intestinal epithelial barrier. This study described the synthesis and characterization of CCM-Co-ZIF-8, a novel composite material with enzyme-like activities similar to catalase, peroxidase, and superoxide dismutase. CCM-Co-ZIF-8 demonstrated the ability to scavenge reactive oxygen species that play a critical role in UC pathogenesis. In vitro studies using lipopolysaccharide-induced RAW264.7 cells showed that CCM-Co-ZIF-8 exhibited anti-inflammatory activity by promoting the transition of macrophages from an M1 to an M2 phenotype. In vivo experiments using a mouse model of UC demonstrated that CCM-Co-ZIF-8 suppressed the expression of proinflammatory cytokines. These findings suggested that CCM-Co-ZIF-8 might hold promise as a therapeutic strategy for the treatment of UC.

THE INFLUENCE OF ULTRA-WIDEBAND LOW-INTENSITY ULTRASOUND ON THE FUNCTIONAL ACTIVITY OF PERITONEAL MACROPHAGES IN VITRO

Studies have been conducted on the influence of various modes of ultrasound on the functional activity of peritoneal macrophages in nitro. It was found that the use of low-intensity broadband ultrasound (UMUS) significantly increases the cytotoxic and respiratory activity of macrophages compared to low-intensity pulsed ultrasound (LIPUS) and control. There was a significant increase in the level of endogenous peroxidase in the macrophage lysate, as well as a transition of macrophages from the M1 (pro-inflammatory) to M2 (anti-inflammatory) state when using UMUS.