Facilitates Macrophage Polarization Research Articles

Dichloroacetate: A metabolic game-changer in alleviating macrophage inflammation and enhancing recovery after myocardial infarction.

Dichloroacetate (DCA) has shown potential in modulating cellular metabolism and inflammation, particularly in cardiac conditions. This study investigates DCA's protective effects in a mouse model of myocardial infarction (MI), focusing on its ability to enhance cardiac function, reduce inflammation, and shift macrophage polarization from the pro-inflammatory M1 to the anti-inflammatory M2 phenotype. An acute MI model was created using left anterior descending coronary artery ligation. Mice were assigned to four groups: normal control, MI control, MI + 50 mM DCA, and MI + 100 mM DCA. Cardiac fibrosis and injury were assessed through H&E staining. Cardiac function was evaluated via echocardiography, and serum levels of creatine kinase-MB (CK-MB) and lactate dehydrogenase (LDH) were measured. Inflammation and apoptosis were analyzed through immunohistochemistry, ELISA, western blotting, and flow cytometry in heart tissue and RAW264.7 cells. Additionally, macrophage polarization and relevant signaling pathways were examined. DCA significantly improved cardiac function in MI mice, evidenced by reduced myocardial injury and lower CK-MB and LDH levels. It also decreased inflammatory cytokines (TNF-α, IL-6 and IL-1β) and facilitated macrophage polarization from M1 to M2. Western blotting revealed that DCA inhibited iNOS and COX2 while enhancing Arg1 expression, alongside improved mitochondrial function and reduced apoptosis. Additionally, by injecting AAV-PDHK4 (pyruvate dehydrogenase kinase) into MI mice, we found that DCA effectively inhibited the progression of MI through the suppression of PDHK4. DCA protects against myocardial infarction by enhancing cardiac function, reducing inflammation, and promoting macrophage polarization, likely through inhibition of PDHK4 and NF-κB pathways, positioning it as a potential therapeutic strategy for cardiac repair post-MI.

Therapeutic Potential of Vanillic Acid in Ulcerative Colitis Through Microbiota and Macrophage Modulation.

This study investigated the protective effects of the dietary polyphenol vanillic acid (VA) on dextran sulfate sodium-induced acute ulcerative colitis (UC) in mice, focusing on its impact on the gut microbiota and inflammatory responses. VA was supplemented following dextran sulfate sodium administration, and key indicators, including body weight, disease activity index, colon length, spleen index, and inflammatory markers, were assessed. VA supplementation significantly alleviated UC symptoms, preserved intestinal barrier integrity, and reduced pro-inflammatory cytokine levels. Additionally, VA positively altered the gut microbiota composition, promoting beneficial bacteria such as Akkermansia muciniphila while suppressing the arachidonic acid metabolism pathway. Fecal microbiota transplantation confirmed that the VA-modified gut microbiota contributed to these protective effects. VA also facilitated macrophage polarization from the pro-inflammatory M1 phenotype to the anti-inflammatory M2 phenotype, further mitigating inflammation. These findings highlight the potential of VA as a natural dietary intervention for UC, emphasizing its role in regulating the gut microbiota and inflammatory pathways, which may have significant nutritional relevance in managing inflammatory bowel diseases.

In Situ Proefferocytosis Microspheres as Macrophage Polarity Converters Accelerate Osteoarthritis Treatment.

Efferocytosis in macrophages typically engages an anti-inflammatory positive feedback regulatory mechanism. In osteoarthritis (OA), characterized by imbalanced inflammatory homeostasis, the proinflammatory state of macrophages in the immune microenvironment can be reversed through enhanced efferocytosis. This study develops an in situ proefferocytosis hydrogel microsphere (macrophage polarity converter, H-C@IL) for OA treatment. Immunoliposomes (IL), CD16/32 antibody-modified clodronate liposomes, are initially prepared using the Re-emulsion method. Then, the IL is loaded into CCL19-modified HAMA microspheres through microfluidic technology. In vitro, H-C@IL can specifically recruit M0 and M1 macrophages via CCL19, induce apoptosis in M1 macrophages through secondary targeting with IL, and provide "Find/Eat-me" signals to enhance in situ efferocytosis. Additionally, it promotes macrophage polarization toward the M2 phenotype. In vivo, behavioral, imaging, and histological analyses demonstrate that H-C@IL effectively facilitates macrophage polarization toward M2, inhibits inflammation, and promotes cartilage regeneration. Mechanistically, H-C@IL enhances efferocytosis by activating proteins such as PROS1 and TIMD4 in M0 macrophages. Concurrently, signaling pathways, including PQLC2-Arg-Rac1 and Pbx1/IL-10, are activated to drive the polarization of macrophages from M0 to M2. In summary, H-C@IL promotes M0 macrophage efferocytosis in situ, facilitates macrophage polarization toward M2, restores inflammatory homeostasis, and promotes cartilage regeneration, offering a comprehensive treatment strategy for OA.

Colon Cancer-Derived Exosomal LncRNA-XIST Promotes M2-like Macrophage Polarization by Regulating PDGFRA.

Colon cancer ranks second in overall cancer-related deaths and poses a serious risk to human life and health. In recent years, exosomes are believed to play an important and significant role in cancer, especially tumor-derived exosomes (TDEs). Previous studies have highlighted the pivotal role of exosomes in tumor development, owing to their ability to mediate communication between tumor cells and macrophages, induce macrophage M2 polarization, and facilitate the progression of tumorigenesis. In this study, we revealed that colon cancer-derived exosomes promoted M2-like macrophage polarization. Moreover, exosome-induced M2-like macrophages, in turn, promoted the proliferation, migration, and invasion abilities of colon cancer cells. Specifically, CT26- and HCT116-derived exosomes led to the activation of AKT, ERK, and STAT3/6 signaling pathways in THP-1(Mφ) cells. Furthermore, our findings showed that colon cancer-derived exosomes secreted lncXIST to sponge miR-17-5p, which, in turn, promoted the expression of PDGFRA, a common gene found in all three signaling pathways, to facilitate M2-like macrophage polarization. Dual-luciferase reporter assays confirmed the binding relationship between lncXIST and miR-17-5p, as well as miR-17-5p and PDGFRA. Collectively, our results highlight the novel role of lncXIST in facilitating macrophage polarization by sponging miR-17-5p and regulating PDGFRA expression.

Netrin1-Enriched Exosomes From Genetically Modified ADSCs as a Novel Treatment for Diabetic Limb Ischemia.

Diabetic limb ischemia (DLI) is a frequent complication of diabetes and the leading cause of non-traumatic amputation. Traditional treatments like stent placement and bypass surgery may not suit all patients. Exosome transplantation has emerged as a promising therapy. Netrin1, a protective cardiovascular factor, has an unclear role in DLI. This study investigates the role of Netrin1 in DLI patients and evaluates the therapeutic potential of exosomes derived from Netrin1-overexpressing adipose-derived stem cells (N-ADSCs). The expression of Netrin1 is significantly decreased in both endothelial cells and serum of DLI patients, highlighting its potential as a biomarker or therapeutic target. In vitro, Netrin1-enriched exosomes (N-Exos) promoted human umbilical vein endothelial cell (HUVEC)proliferation, migration, tube formation, and increased resistance to apoptosis under high glucose conditions. These protective effects are mediated through PI3K/AKT/eNOS and MEK/ERK pathways, and N-Exos further facilitated macrophage polarization from M1 to M2. In vivo, N-Exos demonstrates superior therapeutic effects over ADSC exosomes (Exos), including enhanced angiogenesis, improved collateral artery remodeling, reduced inflammation, and muscle protection. Collectively, these findings identify Netrin1 as a critical factor in DLI and underscore its significance in disease progression and therapeutic strategies. N-Exos offers a promising non-cellular therapeutic approach for the treatment of DLI.

Deletion of TP signaling in macrophages delays liver repair following APAP-induced liver injury by reducing accumulation of reparative macrophage and production of HGF

BackgroundAcetaminophen (APAP)-induced liver injury is the most common cause of acute liver failure. Macrophages are key players in liver restoration following APAP-induced liver injury. Thromboxane A2 (TXA2) and its receptor, thromboxane prostanoid (TP) receptor, have been shown to be involved in tissue repair. However, whether TP signaling plays a role in liver repair after APAP hepatotoxicity by affecting macrophage function remains unclear.MethodsMale TP knockout (TP−/−) and C57BL/6 wild-type (WT) mice were treated with APAP (300 mg/kg). In addition, macrophage-specific TP-knockout (TP△mac) and control WT mice were treated with APAP. We explored changes in liver inflammation, liver repair, and macrophage accumulation in mice treated with APAP.ResultsCompared with WT mice, TP−/− mice showed aggravated liver injury as indicated by increased levels of alanine transaminase (ALT) and necrotic area as well as delayed liver repair as indicated by decreased expression of proliferating cell nuclear antigen (PCNA). Macrophage deletion exacerbated APAP-induced liver injury and impaired liver repair. Transplantation of TP-deficient bone marrow (BM) cells to WT or TP−/− mice aggravated APAP hepatotoxicity with suppressed accumulation of macrophages, while transplantation of WT-BM cells to WT or TP−/− mice attenuated APAP-induced liver injury with accumulation of macrophages in the injured regions. Macrophage-specific TP−/− mice exacerbated liver injury and delayed liver repair, which was associated with increased pro-inflammatory macrophages and decreased reparative macrophages and hepatocyte growth factor (HGF) expression. In vitro, TP signaling facilitated macrophage polarization to a reparative phenotype. Transfer of cultured BM-derived macrophages from control mice to macrophage-specific TP−/− mice attenuated APAP-induced liver injury and promoted liver repair. HGF treatment mitigated APAP-induced inflammation and promoted liver repair after APAP-induced liver injury.ConclusionsDeletion of TP signaling in macrophages delays liver repair following APAP-induced liver injury, which is associated with reduced accumulation of reparative macrophages and the hepatotrophic factor HGF. Specific activation of TP signaling in macrophages may be a potential therapeutic target for liver repair and regeneration after APAP hepatotoxicity.

Infection-Sensitive SPION/PLGA Scaffolds Promote Periodontal Regeneration via Antibacterial Activity and Macrophage-Phenotype Modulation.

Inflammation caused by a bacterial infection and the subsequent dysregulation of the host immune-inflammatory response are detrimental to periodontal regeneration. Herein, we present an infection-sensitive scaffold prepared by layer-by-layer assembly of Feraheme-like superparamagnetic iron oxide nanoparticles (SPIONs) on the surface of a three-dimensional-printed polylactic-co-glycolic acid (PLGA) scaffold. The SPION/PLGA scaffold is magnetic, hydrophilic, and bacterial-adhesion resistant. As indicated by gene expression profiling and confirmed by quantitative real-time reverse transcription polymerase chain reaction and flow cytometry analysis, the SPION/PLGA scaffold facilitates macrophage polarization toward the regenerative M2 phenotype by upregulating IL-10, which is the molecular target of repair promotion, and inhibits macrophage polarization toward the proinflammatory M1 phenotype by downregulating NLRP3, which is the molecular target of anti-inflammation. As a result, macrophages modulated by the SPS promote osteogenic differentiation of bone marrow mesenchymal stromal cells (BMSCs) in vitro. In a rat periodontal defect model, the SPION/PLGA scaffold increased IL-10 secretion and decreased NLRP3 and IL-1β secretion with Porphyromonas gingivalis infection, achieving superior periodontal regeneration than the PLGA scaffold alone. Therefore, this antibacterial SPION/PLGA scaffold has anti-inflammatory and bacterial antiadhesion properties to fight infection and promote periodontal regeneration by immunomodulation. These findings provide an important strategy for developing engineered scaffolds to treat periodontal defects.

NGF facilitates ICAM-1-dependent monocyte adhesion and M1 macrophage polarization in rheumatoid arthritis

Rheumatoid arthritis (RA) is a chronic autoimmune inflammatory disorder in which monocytes adhering to synovial tissue differentiate into the pro-inflammatory M1 macrophage phenotype. Nerve growth factors (NGF) referred to as neurotrophins have been associated with inflammatory events; however, researchers have yet to elucidate the role of NGF in RA. Our examination of clinical tissue samples and analysis of data sourced from the Gene Expression Omnibus dataset unveiled elevated expression levels of M1 macrophage markers in human RA synovial tissue samples compared to normal tissue, with no such distinction observed for M2 markers. Furthermore, immunofluorescence data depicted increased expression levels of NGF and M1 macrophages in RA mice in contrast to normal mice. It appears that NGF stimulation facilitates macrophage polarization from the M0 to the M1 phenotype. It also appears that NGF promotes ICAM-1 production in human RA synovial fibroblasts, which enhances monocyte adhesion through the TrkA, MEK/ERK, and AP-1 signaling cascades. Our findings indicate NGF/TrkA axis as a novel target for the treatment of RA.

Reshaped commensal wound microbiome via topical application of Calvatia gigantea extract contributes to faster diabetic wound healing.

Calvatia gigantea (CG) is widely used as a traditional Chinese medicine for wound treatment. In this study, we aimed to determine the effects of CG extract (CGE) on diabetic wound healing and the commensal wound microbiome. A wound model was established using leptin receptor-deficient db/db mice, with untreated mice as the control group and CGE-treated mice as the treatment group. The wound healing rate, inflammation and histology were analyzed. Additionally, wound microbiome was evaluated via 16S ribosomal RNA (rRNA) gene sequencing. CGE significantly accelerated the healing of diabetic ulcer wounds, facilitated re-epithelialization, and downregulated the transcription levels of the inflammatory cytokines, interleukin-1β and tumor necrosis factor-α. Furthermore, CGE treatment positively affected the wound microbiome, promoting diversity of the microbial community and enrichment of Escherichia-Shigella bacteria in the CGE-treated group. Overall, CGE enhanced diabetic wound healing by modulating the wound microbiome and facilitating macrophage polarization during inflammation. These findings suggest modulation of the commensal wound microbiome using medicinal plants as a potential therapeutic strategy for diabetic wounds.

A guanosine/konjac glucomannan supramolecular hydrogel with antioxidant, antibacterial and immunoregulatory properties for cutaneous wound treatment

Developing naturally-derived wound dressing materials with intrinsic therapeutic effects is desirable for the clinical applications. Recently, guanosine-based supramolecular G-quadruplex (G4) hydrogel exhibited great potential in preparing biological materials due to its simple fabrication method and responsive gel networks. However, the weak mechanical properties and the consequent burst release of bioactive molecules restrict its clinical applications. Herein, we found that konjac glucomannan (KGM) with immunoregulatory effect did not affect the self-assembly of G-quadruplexes and thus effectively enhancing the mechanical properties of G4 hydrogel. Aloin, as a model drug, was in situ loaded into gel networks, finally obtaining the G4/Aloin-KGM hydrogel. This hydrogel exhibited porous morphology, swelling ability and hemostatic capability. Boronate bonds in G4 networks and aloin collectively endowed the hydrogel with excellent antioxidant performance. Meanwhile, aloin also provided outstanding in vitro and in vivo bactericidal ability. The wounds treated with this biocompatible hydrogel demonstrated faster regeneration of epithelial and dermal tissues, and the whole wound healing stages were accelerated by promoting collagen deposition, facilitating macrophage polarization towards M2 phenotype, down-regulating the expression level of IL-6, and up-regulating the expression level of IL-10, CD31 and α-SMA.

Moluodan promotes DSS-induced intestinal inflammation involving the reprogram of macrophage function and polarization

Ethnopharmacological relevanceMoluodan (MLD) is a traditional Chinese medicine that is composed of 18 herbal medicines based on traditional Chinese medicine theory and practice. It has long been used in treating chronic gastritis and its components were traditionally used in dealing with intestinal inflammation. However, its specific pharmacological mechanism is still unclear. Aim of the studyThe upper and lower digestive tract diseases are correlated. In clinical practice, some chronic gastritis patients are also accompanied by intestinal inflammation. Due to the unclear pharmacological mechanism of MLD and its effect on intestinal inflammation, there is doubt whether MLD is still suitable for this type of patient. Therefore, this study aims to elucidate the pharmacological mechanism of MLD and identify its effect in the mouse model of intestinal inflammation. Materials and methodsMice intestinal inflammation model was induced by 2.5% dextran sulfate sodium (DSS). The mice were given different concentrations of MLD via oral gavage (0.25, 0.5 g/kg b.w.). Pharmacodynamic indicators were assessed including body weight, colon length, disease activity index (DAI), bloody stool score, inflammatory factors, histological change, etc. RAW264.7 macrophage cells were used for in vitro experiments that illuminated the role of MLD in reprogramming macrophage function and polarization. RT-qPCR and western blots were performed to measure the mRNA and protein levels of macrophage polarization marker and effector molecules. The functions of polarized macrophages were tested using ROS detection probes, Edu assay and wound healing assay. ResultsThe administration of MLD exhibited obvious hemostatic effects, while unexpectedly accentuating various aspects of the DSS-induced intestinal inflammation in mice, including increased body weight loss and colon shortening, elevated disease activity index, and intensified colonic tissue damage. Additionally, MLD treatment induced more severe inflammatory cell infiltration and higher proinflammatory cytokines expression in colon tissue. Further results showed that MLD promoted M1 macrophage polarization and stimulated its proinflammatory cytokines expression, while only slightly affecting the function of M2 macrophage. Western blot analysis revealed that MLD induced the phosphorylation of AKT and NF-κB. The polarization of M1 macrophages induced by MLD was inhibited by either an Akt inhibitor or a NF-κB inhibitor. ConclusionsAlthough MLD has an obvious hemostatic effect, it generally promoted the severity of DSS-induced colitis in mice by facilitating macrophage polarization toward the M1 phenotype through the AKT/NF-κB pathway. Our study suggested that MLD may not be suitable for colitis, especially during the acute inflammation stage.

Stereotactic ablative radiotherapy and FAPα-based cancer vaccine suppresses metastatic tumor growth in 4T1 mouse breast cancer

Background and purposeThis study tested the hypothesis that a novel combination of stereotactic ablation radiotherapy (SABR) and a cancer vaccine against fibroblast activation protein-alpha (FAPα) can suppress established tumor growth and impede potential metastasis. MethodsThe poorly immunogenic metastatic mouse mammary carcinoma 4T1 was used as a model. Mice were randomly assigned to five treatment groups: (1) untreated control, (2) FAPα-based cancer vaccine, (3) SABR, (4) SABR + pCDH (lentiviral control vector), (5) SABR + FAPα-based cancer vaccine (SABR/FAPα-Vax). FAPα-based cancer vaccine were administered subcutaneously every week for a total of three treatments. SABR was delivered to the primary tumor by 3 × 8 Gy after the first vaccination. ResultsConsistent with the poorly immunogenic nature of 4T1, tumor-bearing mice receiving FAPα-based cancer vaccine or SABR monotherapy showed a modest reduction in tumor volume and increased animal lifespan. In contrast, SABR/FAPα-Vax was well-tolerated, significantly reduced tumor burden, and increased survival compared to monotherapy. The increased survival correlated with inhibition of extracellular matrix (ECM) production, tumor vascularization and lymphangiogenesis. SABR/FAPα-Vax also resulted in an abscopal effect capable of eliminating lung metastases. SABR/FAPα-Vax recruited and activated CD8 + T cells to attack tumor cells and FAPα + stromal cells, and initiated suppressor cell reprogramming, including facilitating macrophage polarization toward an anti-tumor (M1) state, as well as depleting myeloid-derived suppressor cells (MDSCs) and regulatory T cells (Tregs). ConclusionThese findings provide a novel therapeutic combination of radiation and FAPα-based cancer vaccine with promising results against poorly immunogenic metastatic cancer. This study may pave the way to overcome the therapeutic resistance caused by FAPα + CAFs.

Biocompatible Cryogel with Good Breathability, Exudate Management, Antibacterial and Immunomodulatory Properties for Infected Diabetic Wound Healing.

Due to the complex microenvironment and healing process of diabetic wounds, developing wound dressing with good biocompatibility, mechanical stability, breathability, exudate management, antibacterial ability, and immunomodulatory property is highly desired but remains a huge challenge. Herein, a multifunctional cryogel is designed and prepared with bio-friendly bacterial cellulose, gelatin, and dopamine under the condition of sodium periodate oxidation. Bacterial cellulose can enhance the mechanical stability of the cryogel by improving the skeleton supporting effect and crosslinking degree. The cryogel shows outstanding breathability and exudate management capability thanks to the interpenetrated porous structures. I2 and sodium iodides produced in situ by reduction of sodium periodate provide efficient antibacterial properties for the cryogel. The cryogel facilitates macrophage polarization from M1 to M2, thus regulating the immune microenvironment of infected diabetic wounds. With these advantages, the multifunctional cryogel effectively promotes collagen deposition and neovascularization, thus accelerating the healing of infected diabetic wounds.

Hydroxyapatite nanoparticles promote TLR4 agonist-mediated anti-tumor immunity through synergically enhanced macrophage polarization.

Macrophages represent the most prevalent immune cells in the tumor micro-environment, making them an appealing target for tumor immunotherapy. One of our previous studies showed that hydroxyapatite nanoparticles (HANPs) enhanced Toll-like receptor 4 (TLR4) signal transduction in macrophages. This study was proposed to investigate how HANPs manipulated the phenotype and function of macrophage against 4T1 breast tumors in the presence or absence of MPLA, a low toxic Toll-like receptor 4 (TLR4) agonist. The results demonstrated that the addition of HANPs to MPLA significantly promoted cytokine secretion and macrophage polarization toward a tumoricidal M1 phenotype. Further, the resulting supernatant from HANPs/MPLA co-stimulated macrophages enhanced 4T1 tumor cells apoptosis compared to that from macrophages treated with a single component or PBS control. In particular, we found HANPs elicited immunogenic cell death (ICD) indicated by the increased expression of "danger signals", including HMGB1, CRT and ATP in 4T1 cells. Subsequently, the ICD derivatives-containing supernatant from HANPs-treated 4T1 cells activated macrophage and shifted the phenotype of the cells toward M1 type. Moreover, in a tumor-bearing mice model, HANPs and MPLA synergistically delayed tumor growth compared to PBS control, which was positively associated with the promoted macrophage polarization and ICD induction. Therefore, our findings demonstrated a potential platform to modulate the function of macrophages, and shed a new insight into the mechanism involving the immunomodulatory effect of HANPs for tumor therapy. STATEMENT OF SIGNIFICANCE: Polarizing macrophage toward tumoricidal phenotype by harnessing Toll-like receptor (TLR) agonists has been proven effective for tumor immunotherapy. However, the immunomodulatory potency of TLR agonists is limited due to immune suppression or tolerance associated with TLR activation in immune cells. Herein, we introduced hydroxyapatite nanoparticles (HANPs) to MPLA, a TLR4 agonist. The results demonstrated that the addition of HANPs to MPLA promoted macrophage shift toward tumoricidal M1 phenotype, supported a "hot" tumor transformation, and delayed 4T1 tumor growth. Moreover, we found that HANPs elicited immunogenic cell death that produced "danger" signals from cancer cells thereby further facilitated macrophage polarization. This work is significant to direct the rational design of HANPs coupled with or without TLR agonists for tumor immunotherapy.

Inhibition of Toll-Like Receptor 4 Signaling Pathway Accelerates the Repair of Avascular Necrosis of Femoral Epiphysis through Regulating Macrophage Polarization in Perthes Disease.

Legg-Calvé-Perthes disease (LCPD) is still a refractory disease in children's orthopedics. With the introduction of the concept of "osteoimmunology", the immune-inflammatory mechanisms between bone and immune system have become a research focus of LCPD. However, few studies have reported on the pathological role of inflammation-related receptors such as toll-like receptors (TLRs) as well as immune cells such as macrophages in LCPD. This study was for investigating the mechanism of TLR4 signaling pathway on the direction of macrophage polarization and the repair of avascular necrosis of femoral epiphysis in LCPD. With GSE57614 and GSE74089, differentially expressed genes were screened. Through enrichment analysis and protein-protein interaction network, the functions of TLR4 were explored. Furthermore, immunohistochemistry, enzyme-linked immunosorbent assay (ELISA), hematoxylin & eosin (H&E) staining, micro-CT, tartrate-resistant acid phosphatase (TRAP) dyeing and western blotting were performed for determining the influences of TAK-242 (a TLR4 inhibitor) on the repair of avascular necrosis of femoral epiphysis in rat models. Totally 40 co-expression genes were screened as well as enriched in TLR4 signaling pathway. Immunohistochemistry and ELISA analyses certified that TLR4 facilitated macrophage polarization toward the M1 phenotype and prevented macrophage polarization toward the M2 phenotype. Besides, the results of H&E and TRAP staining, micro-CT, and western blotting showed that TAK-242 can inhibit osteoclastogenesis and promote osteogenesis. Inhibition of TLR4 signaling pathway accelerated the repair of avascular necrosis of femoral epiphysis by regulating macrophage polarization in LCPD.

Hypoxic bone marrow mesenchymal stromal cells-derived exosomal miR-182-5p promotes liver regeneration via FOXO1-mediated macrophage polarization.

Mesenchymal stromal cells (MSCs) are attractive candidates for treating hepatic disorders given their potential to enhance liver regeneration and function. The paracrine paradigm may be involved in the mechanism of MSC-based therapy, and exosomes (Exo) play an important role in this paracrine activity. Hypoxia significantly improves the effectiveness of MSC transplantation. However, whether hypoxia preconditioned MSCs (Hp-MSCs) can enhance liver regeneration, and whether this enhancement is mediated by Exo, are unknown. In this study, mouse bone marrow-derived MSCs (BM-MSCs) and secreted Exo were injected through the tail vein. We report that Hp-MSCs promote liver regeneration after partial hepatectomy in mice through their secreted exosomes. Interestingly, MSC-Exo were concentrated in liver 6h after administration and mainly taken up by macrophages, but not hepatocytes. Compared with normoxic MSC-Exo (N-Exo), hypoxic MSC-Exo (Hp-Exo) enhanced M2 macrophage polarization both in vivo and in vitro. Microarray analysis revealed significant enrichment of microRNA (miR)-182-5p in Hp-Exo compared with that in N-Exo. In addition, miR-182-5p knockdown partially abolished the beneficial effect of Hp-Exo. Finally, Hp-MSC-derived exosomal miR-182-5p inhibited theprotein expression of forkhead box transcription factor 1 (FOXO1) in macrophages, which inhibited toll-like receptor 4 (TLR4) expression and subsequently induced an anti-inflammatory response. These results highlight the therapeutic potential of Hp-Exo in liver regeneration and suggest that miR-182-5p from Hp-Exo facilitates macrophage polarization during liver regeneration by modulating the FOXO1/TLR4 signaling pathway.

Abstract 10391: Elevated Plasma Branched-Chain Amino Acids Level Promotes Atherosclerosis Progression by Facilitating Macrophage Polarization Toward M1 Phenotype That Results in the Increase of Inflammation

Introduction: Few studies have reported that whether elevated plasma branched-chain amino acids (BCAA) level is causally related to atherosclerosis (AS) and the mechanism involved. Methods: First, the plasma BCAA level of 258 atherosclerotic cardiovascular disease (ASCVD) patients and 188 normal people was measured. Second, plaque volume, stability and inflammation of AS mice were evaluated. Third, we assayed BCAA level, catabolism-promoting genes and inflammation in the circulating monocytes of ASCVD patients and abdominal macrophages of AS mice. Fourth, inflammation and macrophage polarization were evaluated in BCAA catabolic deficient RAW 264.7 cells. Finally, mitochondrial hydrogen peroxide (mtH 2 O 2 ), nuclear H 2 O 2 and High mobility group box 1 (HMGB1) levels in RAW 264.7 cells were measured and RAW 264.7 cells-overexpressing catalase targeted to mitochondria (MCAT), nucleus (NCAT) and HMGB1KD RAW 264.7 cells were built to detect their effect on macrophage polarization. Results: First, we found that plasma BCAA level was an independent risk factor of ASCVD. Second, we also found plasma BCAA level was elevated in AS mice, which led to the increase of plaque volume and instability, as well as inflammation. The growth of plaque instability was characterized by increased macrophage amounts and decreased smooth muscle cells (SMCs) and collagen contents. Conversely, when plasma BCAA level was lowered, the above phenomena could be reversed. Third, elevated plasma BCAA level resulting from BCAA catabolic defect occurred in the monocytes of ASCVD patients and the abdominal macrophages of AS mice, which increased inflammatory response by promoting the polarization of macrophages toward M1 phenotype. Fourth, elevated BCAA level-mediated macrophage polarization toward M1 phenotype was regulated by increasing mtH 2 O 2 level to induce secretion of HMGB1 by increasing nuclear H 2 O 2 level. Finally, the improvement of BCAA catabolism of macrophages alleviated AS progression in mice. Conclusions: Our data demonstrates that elevated plasma BCAA level is an independent risk factor of ASCVD and promotes AS progression, indicating that plasma BCAA level might be a therapeutic target for ASCVD.

Abstract 1384: Selective PI3Kγ inhibitor ZX-4081 reprograms the tumor microenvironment to facilitate anti-cancer immunity

Abstract PI3Kγ is highly expressed in leukocytes and also known to play a critical role in activation of myeloid cells at sites of inflammation and tumorigenesis, T cell recruitment into tumor microenvironment, and chemokine-mediated chemotaxis as well as growth factor signaling. Previous studies reported that blockade of PI3Kγ-AKT signaling is able to inhibit tumor growth and metastasis by increasing CD8+T cell activation and M1(anti-tumoral)-like macrophage appearance in the tumor milieu, and thereby overcome resistance to immune checkpoint inhibitors (e.g., anti-PD1 antibody). In this report, we present a highly selective PI3Kγ inhibitor ZX-4081 with an IC50 of 1.5 nM for PI3Kγ- and over 1000-fold selectivity over the other isoform (α, β, and δ) in biochemical assay. To confirm inhibitory effect of ZX-4081 on PI3Kγ-AKT activation, LPS-stimulated THP-1 cells (monocytic cells) were treated with 10 nM or 500 nM ZX-4081, and their AKT phosphorylation (at T308 and S473 sites) were examined by immunoblotting. The immunoblot result indicated that both T308 and S473 phosphorylation was down-regulated by ZX-4081 in a time-dependent and dose-dependent manner. Next, to verify whether ZX-4081 can alter macrophage polarization, M-CSF-stimulated human peripheral blood mononuclear cells (PBMCs) were subsequently either induced into M1-like macrophages with LPS and IFN-γ or induced into M2-like macrophages with IL-4 and IL-13 in the absence (vehicle) or presence of ZX4081 (from 1.52 to1000 nM). The flow cytometry result exhibited that ZX-4081 effectively facilitated macrophage polarization toward M1-like phenotype, evidenced by an increase (a 2.5-fold increase at 10 nM compared to vehicle) in iNOS and CD86 expressions of M1-like macrophages; however, CD206 expression (M2-like phenotype) was not changed by ZX-4081 treatment in M2-like macrophages. Additionally, ZX-4081 could reduce both IL-10 protein and mRNA levels in M2-like macrophages (2-5 times lower than vehicle). The cell proliferation assessment showed that ZX-4081(< 5μM) did not exert potent growth inhibitory effects on solid tumor cell lines including HT-29, HT-1197, 4T1, B16-F10, and CT-26 cells. In the 4T1 syngeneic mouse model, ZX-4081 treatment at 25 mg/kg (p.o, BID), 50 mg/kg (p.o., QD), and 50 mg/kg (p.o., BID) for 28 days gave rise to a reduction in tumor growth by 34.6%, 21.2%, and 44.1% in size, respectively (p< 0.0001). Therefore, the in vivo inhibitory effect of ZX-4081 on 4T1 tumor growth was attributed to its modulation on the mouse anti-tumor immunity. Overall, our data suggest that ZX-4081 possesses ability of tumor growth inhibition by reprogramming tumor microenvironment via impairing PI3Kγ-AKT-mediated macrophage polarization to enhance anti-cancer immunity. Citation Format: Ying-Ying Li, Kun Guo, Zhiyuan Peng, Deming Kong, Xiaolin Hao, Jinfu Yang, Xiaoli (Shelley) Qin. Selective PI3Kγ inhibitor ZX-4081 reprograms the tumor microenvironment to facilitate anti-cancer immunity [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr 1384.

Mesenchymal Stem Cells Enhance Therapeutic Effect and Prevent Adverse Gastrointestinal Reaction of Methotrexate Treatment in Collagen-Induced Arthritis.

Rheumatoid arthritis (RA) is a systemic autoimmune disease characterized by articular destruction and functional loss. Methotrexate (MTX) is effective in RA treatment. However, MTX induces several adverse events and 20%-30% of patients do not respond to MTX. Thus, it is urgent to enhance the therapeutic effects and reduce the side effects of MTX. Recent studies showed that mesenchymal stem cells (MSCs) were participants in anti-inflammation, immunoregulation, and tissue regeneration. However, whether the combined application of MSCs and MTX promotes the therapeutic effects and reduces the side effects of MTX has not been studied. In this study, we used bovine type II collagen to induce rheumatoid arthritis in mice (collagen-induced arthritis, CIA). Then, CIA mice were subjected to MTX or MSC treatment, or both. The therapeutic effect and adverse events of different treatments on RA were evaluated with micro-CT, HE staining, and immunohistochemistry in vivo. Apoptosis and proliferation of MODE-K cells were measured after treated with MTX or/and cocultured with UCs. To test M2 polarization, Raw264.7 macrophages were stimulated by MTX with different concentrations or cocultured with UCs. We found that the combined application of MSCs and MTX increased the therapeutic effects on RA, as evidenced by decreased arthritis score, inflammatory responses, and mortality. Moreover, in this combination remedy, MTX prefers to suppress inflammation by facilitating macrophage polarization to M2 type while UCs prefer to eliminate gastrointestinal side effects of MTX via mitigating the apoptosis of intestinal epithelial cells. Thus, a combination of MTX and UCs is a promising strategy for RA treatment.

Fibrinogen-like protein 2 deficiency aggravates renal fibrosis by facilitating macrophage polarization

Renal fibrosis has no effective target for its prevention or reversal. Fibinogen-like protein 2 (Fgl2) is a novel prothrombinase exhibiting coagulation activity and immunomodulatory effects. Although Fgl2 is known to play a vital role in the development of liver and interstitial fibrosis, its function in renal fibrosis remains unclear. In this study, Fgl2 expression was found to be markedly increased in kidney tissues from mice with unilateral ureteral obstruction (UUO)-induced renal fibrosis and patients with chronic kidney disease. However, Fgl2 deficiency aggravated UUO-induced renal fibrosis, as evidenced by the significantly increasing collagen I, fibronectin, and α-SMA expression, extracellular matrix deposition, and profibrotic factor (TGF-β1) secretion. Administration of rmFgl2 (recombinant mouse Fgl2) significantly alleviated UUO-induced renal fibrosis in mice, suggesting that the increased fibrosis can be reversed by supplementing rmFgl2. Although there was no difference in the percentages of total macrophages between Fgl2+/+ and Fgl2–/– mice, Fgl2 deficiency remarkably facilitated M2 macrophage polarization and accelerated M1 macrophage polarization to a low degree, during UUO-induced renal fibrosis development in mice. Similar results were observed when Fgl2+/+ and Fgl2–/– mice bone marrow-derived macrophages were treated for M1 or M2 polarization. Moreover, Fgl2 deficiency significantly increased the phosphorylation of STAT6, a critical mediator of M2 polarization, in both UUO-induced fibrotic kidney tissues and bone marrow-derived M2 macrophages. In conclusion, the aggravation of renal fibrosis by Fgl2 deficiency is facilitated by the p-STAT6-dependent upregulation of macrophage polarization, especially of M2.