Macrophage Inflammatory Response Research Articles

Development of hyaluronic acid hydrogel containing prednisolone-encapsulated nonphospholipid liposomes for the treatment of rheumatoid arthritis.

Rheumatoid arthritis (RA) requires therapeutic approaches that alleviate symptoms and inhibit the progression of joint damage. Glucocorticoids (GCs) have been a cornerstone of RA treatment, yet their use is often limited by side effects. Recent advancements suggest that liposome-based delivery systems can improve GC biodistribution, minimizing toxicity. This study introduces an innovative tool for RA treatment using prednisone-encapsulated nonphospholipid liposomes (NPLs) in combination with a hyaluronic acid (HA) hydrogel. Our methodology involved incorporating prednisone (PR) with palmitic acid and cholesterol to formulate stable NPLs using a thin-film hydration technique. The synthesized PR-NPLs, characterized by a mean size of 150 nm, demonstrated uniform distribution and higher drug encapsulation in comparison with conventional phospholipid liposomes. In vitro assays revealed that PR-NPL markedly reduced inflammatory responses in macrophages. Additionally, we successfully incorporated PR-NPL into an HA hydrogel, employing a photoinitiated cross-linking process. This novel composite offered modulable PR release, governed by the degree of hydrogel cross-linking. The developed system presents a promising advancement in RA management, especially suited for intraarticular injections. It potentially enables targeted, controlled drug release with a reduced risk of side effects, signifying a significant improvement over existing RA therapies.

β-catenin mediates monocrotaline-induced pulmonary hypertension via glycolysis in rats

BackgroundMetabolic abnormalities and immune inflammation are deeply involved in pulmonary vascular remodelling and the development of pulmonary hypertension (PH). However, the regulatory mechanisms of glycolysis in macrophages are still elusive. Cumulative evidence indicates that β-catenin plays a crucial role in metabolic reprogramming. This study aimed to investigate the effect of β-catenin on macrophage glycolysis in PH.MethodsLPS-induced BMDMs were generated via in vitro experiments. A monocrotaline (MCT)-induced PH rat model was established, and the β-catenin inhibitor XAV939 was administered in vivo. The role of β-catenin in glycolysis was analysed. The degree of pulmonary vascular remodelling was measured.Resultsβ-catenin was significantly increased in both in vitro and in vivo models. In LPS-induced BMDMs, β-catenin increased the levels of hexokinase 2 (HK2), phosphofructokinase (PFK), M2-pyruvate kinase (PKM2), lactate dehydrogenase (LDH), and lactate (LA) and the expression of inflammatory cytokines and promoted PASMC proliferation and migration in vitro. XAV939 decreased the level of glycolysis and downregulated the expression of inflammatory cytokines in vivo. MCT promoted pulmonary arterial structural remodelling and right ventricular hypertrophy, and XAV939 alleviated these changes.ConclusionsOur findings suggest that β-catenin is involved in the development of PH by promoting glycolysis and the inflammatory response in macrophages. Inhibition of β-catenin could improve the progression of PH.

Dioscin attenuates lupus nephritis in NZB/W F1 mice by decreasing NF-κB activation and NLRP3 inflammasome.

. Dioscin, a natural steroid saponin, has anticancer, anti-inflammatory, anti-hyperlipidemic, and glycemic capabilities. This study focused on dioscin roles and its related mechanisms in experimental lupus nephritis. . Lupus-prone NZB/W F1 mice were intragastrically administered with dioscin, prednisone or vehicle, and kidney, urine and blood samples were harvested after the mice were sacrificed. Proteinuria, blood urea nitrogen (BUN), creatinine, anti-dsDNA, IL-1β, and IL-18 levels in serum as well as IFN-γ, IL-6, IL-17 and TNF-α levels in kidney tissues were assessed. Renal histopathology was examined through hematoxylin-eosin staining. IgG and C3 expression in kidney was evaluated using immunofluorescence staining. The number of glomerular F4/80-positive cells and NLRP3-positive cells was determined by immunohistochemical staining. The protein expression was examined by western blotting. . Dioscin alleviated lupus nephritis in NZB/W F1 mice. Dioscin declined serum anti-dsDNA level, prevented deposition of immune complexes in renal glomeruli, and inhibited the inflammatory response and infiltration of macrophages into mouse kidneys. Dioscin inhibited NF-κB and NLRP3 inflammasome in NZB/W F1 mice. . Dioscin ameliorates lupus nephritis through inhibition of NLRP3 inflammasome and NF-κB signaling.

Deletion of myeloid HDAC3 promotes efferocytosis to ameliorate retinal ischemic injury

Ischemia-induced retinopathy is a hallmark finding of common visual disorders including diabetic retinopathy (DR) and central retinal artery and vein occlusions. Treatments for ischemic retinopathies fail to improve clinical outcomes and the design of new therapies will depend on understanding the underlying disease mechanisms. Histone deacetylases (HDACs) are an enzyme class that removes acetyl groups from histone and non-histone proteins, thereby regulating gene expression and protein function. HDACs have been implicated in retinal neurovascular injury in preclinical studies in which nonspecific HDAC inhibitors mitigated retinal injury. Histone deacetylase 3 (HDAC3) is a class I histone deacetylase isoform that plays a central role in the macrophage inflammatory response. We recently reported that myeloid cells upregulate HDAC3 in a mouse model of retinal ischemia-reperfusion (IR) injury. However, whether this cellular event is an essential contributor to retinal IR injury is unknown. In this study, we explored the role of myeloid HDAC3 in ischemia-induced retinal neurovascular injury by subjecting myeloid-specific HDAC3 knockout (M-HDAC3 KO) and floxed control mice to retinal IR. The M-HDAC3 KO mice were protected from retinal IR injury as shown by the preservation of inner retinal neurons, vascular integrity, and retinal thickness. Electroretinography confirmed that this neurovascular protection translated to improved retinal function. The retinas of M-HDAC3 KO mice also showed less proliferation and infiltration of myeloid cells after injury. Interestingly, myeloid cells lacking HDAC3 more avidly engulfed apoptotic cells in vitro and after retinal IR injury in vivo compared to wild-type myeloid cells, suggesting that HDAC3 hinders the reparative phagocytosis of dead cells, a process known as efferocytosis. Further mechanistic studies indicated that although HDAC3 KO macrophages upregulate the reparative enzyme arginase 1 (A1) that enhances efferocytosis, the inhibitory effect of HDAC3 on efferocytosis is not solely dependent on A1. Finally, treatment of wild-type mice with the HDAC3 inhibitor RGFP966 ameliorated the retinal neurodegeneration and thinning caused by IR injury. Collectively, our data show that HDAC3 deletion enhances macrophage-mediated efferocytosis and protects against retinal IR injury, suggesting that inhibiting myeloid HDAC3 holds promise as a novel therapeutic strategy for preserving retinal integrity after ischemic insult.

Mechanism of Lian Hua Qing Wen capsules regulates the inflammatory response caused by M1 macrophage based on cellular experiments and computer simulations

PurposeThe polarization of macrophages with the resulting inflammatory response play a crucial part in tissue and organ damage due to inflammatory. Study has proved Lian Hua Qing Wen capsules (LHQW) can reduce activation of inflammatory response and damage of tissue derived from the inflammatory reactions. However, the mechanism of LHQW regulates the macrophage-induced inflammatory response is unclear. Therefore, we investigated the mechanism of LHQW regulated the inflammatory response of M1 macrophages by cellular experiments and computer simulations. MethodsThis study has analysed the targets and mechanisms of macrophage regulating inflammatory response at gene and protein levels through bioinformatics. The monomeric components of LHQW were analyzed by High Performance Liquid Chromatography (HPLC). We established the in vitro cell model by M1 macrophages (Induction of THP-1 cells into M1 macrophages). RT-qPCR and immunofluorescence were used to detect changes in gene and protein levels of key targets after LHQW treatment. Computer simulations were utilized to verify the binding stability of monomeric components and protein targets. ResultsMacrophages had 140690 gene targets, inflammatory response had 12192 gene targets, intersection gene targets were 11772. Key monomeric components (including: Pinocembrin, Fargesone-A, Nodakenin and Bowdichione) of LHQW were screened by HPLC. The results of cellular experiments indicated that LHQW could significantly reduce the mRNA expression of CCR5, CSF2, IFNG and TNF, thereby alleviating the inflammatory response caused by M1 macrophage. The computer simulations further validated the binding stability and conformation of key monomeric components and key protein targets, and IFNG/Nodakenin was able to form the most stable binding conformation for its action. ConclusionIn this study, the mechanism of LHQW inhibits the polarization of macrophages and the resulting inflammatory response was investigated by computer simulations and cellular experiments. We found that LHQW may not only reduce cell damage and death by acting on TNF and CCR5, but also inhibit the immune recognition process and inflammatory response by regulating CSF2 and IFNG to prevent polarization of macrophages. Therefore, these results suggested that LHQW may act through multiple targets to inhibit the polarization of macrophages and the resulting inflammatory response.

RNF149 Destabilizes IFNGR1 in Macrophages to Favor Post-Infarction Cardiac Repair.

Macrophage-driven inflammation critically involves in cardiac injury and repair following myocardial infarction (MI). However, the intrinsic mechanisms that halt the immune response of macrophages, which is critical to preserve homeostasis and effective infarct repair, remain to be fully defined. Here, we aimed to determine the ubiquitination-mediated regulatory effects on averting exaggerated inflammatory responses in cardiac macrophages. We used transcriptome analysis of mouse cardiac macrophages and bone marrow-derived macrophages to identify the E3 ubiquitin ligase RNF149 (RING finger protein 149) as a modulator of macrophage response to MI. Employing loss-of-function methodologies, bone marrow transplantation approaches, and adenovirus-mediated RNF149 overexpression in macrophages, we elucidated the functional role of RNF149 in MI. We explored the underlying mechanisms through flow cytometry, transcriptome analysis, immunoprecipitation/mass spectrometry analysis, and functional experiments. RNF149 expression was measured in the cardiac tissues of patients with acute MI and healthy controls. RNF149 was highly expressed in murine and human cardiac macrophages at the early phase of MI. Knockout of RNF149, transplantation of Rnf149-/- bone marrow, and bone marrow macrophage-specific RNF149-knockdown markedly exacerbated cardiac dysfunction in murine MI models. Conversely, overexpression of RNF149 in macrophages attenuated the ischemia-induced decline in cardiac contractile function. RNF149 deletion increased infiltration of proinflammatory monocytes/macrophages, accompanied by a hastened decline in reparative subsets, leading to aggravation of myocardial apoptosis and impairment of infarct healing. Our data revealed that RNF149 in infiltrated macrophages restricted inflammation by promoting ubiquitylation-dependent proteasomal degradation of IFNGR1 (interferon gamma receptor 1). Loss of IFNGR1 rescued deleterious effects of RNF149 deficiency on MI. We further demonstrated that STAT1 activation induced Rnf149 transcription, which, in turn, destabilized the IFNGR1 protein to counteract type-II IFN (interferon) signaling, creating a feedback control mechanism to fine-tune macrophage-driven inflammation. These findings highlight the significance of RNF149 as a molecular brake on macrophage response to MI and uncover a macrophage-intrinsic posttranslational mechanism essential for maintaining immune homeostasis and facilitating cardiac repair following MI.

Antimicrobial peptide 2K4L inhibits the inflammatory response in macrophages and Caenorhabditis elegans and protects against LPS-induced septic shock in mice

2K4L is a rationally designed analog of the short α-helical peptide temporin-1CEc, a natural peptide isolated and purified from the skin secretions of the Chinese brown frog Rana chensinensis by substituting amino acid residues. 2K4L displayed improved and broad-spectrum antibacterial activity than temporin-1CEc in vitro. Here, the antibacterial and anti-inflammatory activities of 2K4L in macrophages, C. elegans and mice were investigated. The results demonstrated that 2K4L could enter THP-1 cells to kill a multidrug-resistant Acinetobacter baumannii strain (MRAB 0227) and a sensitive A. baumannii strain (AB 22933), as well as reduce proinflammatory responses induced by MRAB 0227 by inhibiting NF-κB signaling pathway. Similarly, 2K4L exhibited strong bactericidal activity against A. baumannii uptake into C. elegans, extending the lifespan and healthspan of the nematodes. Meanwhile, 2K4L alleviated the oxidative stress response by inhibiting the expression of core genes in the p38 MAPK/PMK-1 signaling pathway and downregulating the phosphorylation level of p38, thereby protecting the nematodes from damage by A. baumannii. Finally, in an LPS-induced septic model, 2K4L enhanced the survival of septic mice and decreased the production of proinflammatory cytokines by inhibiting the signaling protein expression of the MAPK and NF-κB signaling pathways and protecting LPS-induced septic mice from a lethal inflammatory response. In conclusion, 2K4L ameliorated LPS-induced inflammation both in vitro and in vivo.

Repression of BRD4 mitigates NLRP3 inflammasome-mediated pyroptosis in Mycobacterium-infected macrophages by repressing endoplasmic reticulum stress

Tuberculosis (TB) is the leading cause of human death worldwide due to Mycobacterium tuberculosis (Mtb) infection. Multiple lines of evidences have illuminated the emerging role of NLRP3 inflammasome-mediated pyroptosis in the clearance of pathogenic infection. In the current study, we sought to investigate the functional role and feasible potential mechanism of BRD4 in Mtb-infected macrophages. We observed that BRD4 was distinctly ascended in THP-1 macrophages upon Mtb infection. Functionally, intervention of BRD4 or pretreated with JQ1 obviously restricted Mtb-triggered cell pyroptosis, as evidenced by declination of protein level of the specific pyroptosis markers including Cleaved Caspase 1, gasdermin D (GSDMD-N) and Cleaved-IL-1β. In the meanwhile, disruption of BRD4 or JQ1 application remarkably prohibited excessive inflammatory responses as characterized by reduce the production of the inflammatory factors such as IL-1β and IL-18. Concomitantly, disruption of BRD4 or administrated with JQ1 manifestly repressed Mtb-aroused Nod-like receptor family pyrindomain-containing 3 (NLRP3) inflammasome activation, as witnessed by attenuation of protein levels of NLRP3, Pro-Caspase1 and apoptosis-associated speck-like protein (ASC). The above findings clearly demonstrated that suppression of BRD4 exerted great influence on regulating Mtb-elicited inflammatory response by coordinating NLRP3 inflammasome-mediated pyroptosis. More importantly, perturbation of BRD4 or JQ1 employment notably restrained endoplasmic reticulum (ER) stress triggered by Mtb-infection, as reflected by noticeably lessened the levels of GRP78, CHOP and ATF6. In terms of mechanism, ER stress agonist tunicamycin profoundly abrogated the favorable effects of BRD4 inhibition on Mtb-triggered pyroptosis, inflammation reaction and inflammasome activation. Collectively, these preceding outcomes strongly illuminated that inhibition of BRD4 targeted ER stress to retard NLRP3 inflammasome activation and subsequent cell pyroptosis and prevention of inflammatory response in Mtb-infected macrophages, highlighting that blocking BRD4 might serve as a promising candidate for protection against Mtb-triggered inflammatory injury.

SENP3 sensitizes macrophages to ferroptosis via de-SUMOylation of FSP1

Ferroptosis, driven by an imbalance in redox homeostasis, has recently been identified to regulate macrophage function and inflammatory responses. SENP3 is a redox-sensitive de-SUMOylation protease that plays an important role in macrophage function. However, doubt remains on whether SENP3 and SUMOylation regulate macrophage ferroptosis. For the first time, the results of our study suggest that SENP3 sensitizes macrophages to RSL3-induced ferroptosis. We showed that SENP3 promotes the ferroptosis of M2 macrophages to decrease M2 macrophage proportion in vivo. Mechanistically, we identified the ferroptosis repressor FSP1 as a substrate for SUMOylation and confirmed that SUMOylation takes place mainly at its K162 site. We found that SENP3 sensitizes macrophages to ferroptosis by interacting with and de-SUMOylating FSP1 at the K162 site. In summary, our study describes a novel type of posttranslational modification for FSP1 and advances our knowledge of the biological functions of SENP3 and SUMOylation in macrophage ferroptosis.

Differential changes in end organ immune cells and inflammation in salt-sensitive hypertension: effects of increasing M2 macrophages.

Salt-sensitive hypertension (SSHTN) is associated with M1 macrophage polarization and inflammatory responses, leading to inflammation-associated lymphangiogenesis and functional impairment across multiple organs, including kidneys and gonads. However, it remains unclear whether promoting M2 macrophage polarization can alleviate the hypertension, inflammation, and end organ damage in mice with salt sensitive hypertension (SSHTN). Male and female mice were made hypertensive by administering nitro-L-arginine methyl ester hydrochloride (L-NAME; 0.5 mg/ml) for 2 weeks in the drinking water, followed by a 2-week interval without any treatments, and a subsequent high salt diet for 3 weeks (SSHTN). AVE0991 (AVE) was intraperitoneally administered concurrently with the high salt diet. Control mice were provided standard diet and tap water. AVE treatment significantly attenuated BP and inflammation in mice with SSHTN. Notably, AVE promoted M2 macrophage polarization, decreased pro-inflammatory immune cell populations, and improved function in renal and gonadal tissues of mice with SSHTN. Additionally, AVE decreased lymphangiogenesis in the kidneys and testes of male SSHTN mice and the ovaries of female SSHTN mice. These findings highlight the effectiveness of AVE in mitigating SSHTN-induced elevated BP, inflammation, and end organ damage by promoting M2 macrophage polarization and suppressing pro-inflammatory immune responses. Targeting macrophage polarization emerges as a promising therapeutic approach for alleviating inflammation and organ damage in SSHTN. Further studies are warranted to elucidate the precise mechanisms underlying AVE-mediated effects and to assess its clinical potential in managing SSHTN.

Metabolic flux in macrophages in obesity and type-2 diabetes.

Recent literature extensively investigates the crucial role of energy metabolism in determining the inflammatory response and polarization status of macrophages. This rapidly expanding area of research highlights the importance of understanding the link between energy metabolism and macrophage function. The metabolic pathways in macrophages are intricate and interdependent, and they can affect the polarization of macrophages. Previous studies suggested that glucose flux through cytosolic glycolysis is necessary to trigger pro-inflammatory phenotypes of macrophages, and fatty acid oxidation is crucial to support anti-inflammatory responses. However, recent studies demonstrated that this understanding is oversimplified and that the metabolic control of macrophage polarization is highly complex and not fully understood yet. How the metabolic flux through different metabolic pathways (glycolysis, glucose oxidation, fatty acid oxidation, ketone oxidation, and amino acid oxidation) is altered by obesity- and type 2 diabetes (T2D)-associated insulin resistance is also not fully defined. This mini-review focuses on the impact of insulin resistance in obesity and T2D on the metabolic flux through the main metabolic pathways in macrophages, which might be linked to changes in their inflammatory responses. We closely evaluated the experimental studies and methodologies used in the published research and highlighted priority research areas for future investigations.

Size-Dependent Effect of Titania Nanotubes on Endoplasmic Reticulum Stress to Re-establish Diabetic Macrophages Homeostasis.

In patients with diabetes, endoplasmic reticulum stress (ERS) is a crucial disrupting factor of macrophage homeostasis surrounding implants, which remains an obstacle to oral implantation success. Notably, the ERS might be modulated by the implant surface morphology. Titania nanotubes (TNTs) may enhance diabetic osseointegration. However, a consensus has not been achieved regarding the tube-size-dependent effect and the underlying mechanism of TNTs on diabetic macrophage ERS. We manufactured TNTs with small (30 nm) and large diameters (100 nm). Next, we assessed how the different titanium surfaces affected diabetic macrophages and regulated ERS and Ca2+ homeostasis. TNTs alleviated the inflammatory response, oxidative stress, and ERS in diabetic macrophages. Furthermore, TNT30 was superior to TNT100. Inhibiting ERS abolished the positive effect of TNT30. Mechanistically, topography-induced extracellular Ca2+ influx might mitigate excessive ERS in macrophages by alleviating ER Ca2+ depletion and IP3R activation. Furthermore, TNT30 attenuated the peri-implant inflammatory response and promoted osseointegration in diabetic rats. TNTs with small nanodiameters attenuated ERS and re-established diabetic macrophage hemostasis by inhibiting IP3R-induced ER Ca2+ depletion.

Gasdermin D silencing alleviates airway inflammation and remodeling in an ovalbumin-induced asthmatic mouse model

Emerging evidence demonstrates that pyroptosis has been implicated in the pathogenesis of asthma. Gasdermin D (GSDMD) is the pyroptosis executioner. The mechanism of GSDMD in asthma remains unclear. The aim of this study was to elucidate the potential role of GSDMD in asthmatic airway inflammation and remodeling. Immunofluorescence staining was conducted on airway epithelial tissues obtained from both asthma patients and healthy controls (HCs) to evaluate the expression level of N-GSDMD. ELISA was used to measure concentrations of cytokines (IL-1β, IL-18, IL-17A, and IL-10) in serum samples collected from asthma patients and healthy individuals. We demonstrated that N-GSDMD, IL-18, and IL-1β were significantly increased in samples with mild asthma compared with those from the controls. Then, wild type and Gsdmd-knockout (Gsdmd−/−) mice were used to establish asthma model. We performed histopathological staining, ELISA, and flow cytometry to explore the function of GSDMD in allergic airway inflammation and tissue remodeling in vivo. We observed that the expression of N-GSDMD, IL-18, and IL-1β was enhanced in OVA-induced asthma mouse model. Gsdmd knockout resulted in attenuated IL-18, and IL-1β production in both bronchoalveolar lavage fluid (BALF) and lung tissue in asthmatic mice. In addition, Gsdmd−/− mice exhibit a significant reduction in airway inflammation and remodeling, which might be associated with reduced Th17 inflammatory response and M2 polarization of macrophages. Further, we found that GSDMD knockout may improve asthmatic airway inflammation and remodeling through regulating macrophage adhesion, migration, and macrophage M2 polarization by targeting Notch signaling pathway. These findings demonstrate that GSDMD deficiency profoundly alleviates allergic inflammation and tissue remodeling. Therefore, GSDMD may serve as a potential therapeutic target against asthma.

Macrophage-derived FGFR1 drives atherosclerosis through PLCγ-mediated activation of NF-κB inflammatory signaling pathway.

Atherosclerosis is a leading cause of cardiovascular morbidity and mortality. Atherosclerotic lesions show increased levels of proteins associated with the fibroblast growth factor receptor (FGFR) pathway. However, the functional significance and mechanisms governed by FGFR signaling in atherosclerosis are not known. In the present study, we investigated FGFR1 signaling in atherosclerosis development and progression. Examination of human atherosclerotic lesions and aortas of Apoe-/- mice fed a high-fat diet (HFD) showed increased levels of FGFR1 in macrophages. We deleted myeloid-expressed Fgfr1 in Apoe-/- mice and showed that Fgfr1 deficiency reduces atherosclerotic lesions and lipid accumulations in both male and female mice upon HFD feeding. These protective effects of myeloid Fgfr1 deficiency were also observed when mice with intact FGFR1 were treated with FGFR inhibitor AZD4547. To understand the mechanistic basis of this protection, we harvested macrophages from mice and show that FGFR1 is required for macrophage inflammatory responses and uptake of oxidized LDL. RNA sequencing showed that FGFR1 activity is mediated through phospholipase-C-gamma (PLCγ) and the activation of nuclear factor-κB (NF-κB) but is independent of FGFR substrate 2. Our study provides evidence of a new FGFR1-PLCγ- NF-κB axis in macrophages in inflammatory atherosclerosis, supporting FGFR1 as a potentially therapeutic target for atherosclerosis-related diseases.

Untangling the inflammatory responses of liver x receptor (LXR) activation in human macrophages

Abstract Funding Acknowledgements Type of funding sources: Public Institution(s). Main funding source(s): Rembrandt Institute for Cardiovascular Science (grant 2022) The regulation of cholesterol and fatty acid homeostasis is essential and the Liver X Receptor (LXR) plays a crucial role in this process. When activated, LXR promotes cholesterol efflux and suppresses the transcription of pro-inflammatory genes in mouse macrophages, making it a promising therapy against atherosclerosis. Studies indeed have shown that LXR agonism is effective in pre-clinical atherosclerotic mouse models. However, the limited data on human macrophages suggests that LXR activation may have additional pro-inflammatory effects in humans, and the mechanisms contributing to this are not yet fully understood. To investigate the inflammatory properties of LXR activation in human macrophages, monocytes were isolated from buffy coats of healthy donors and differentiated into macrophages using M-CSF. The macrophages were exposed to synthetic and endogenous LXR ligands, such as GW3965, T0901317, and desmosterol, respectively, followed by stimulation with lipopolysaccharide (LPS) for six hours. We used qPCR and ELISA to analyze experiments and plan to supplement our data with RNA-Seq and multiplex assays. Preliminary results show that LXR activation reduces LPS-induced activation of interferon-mediated genes like CXCL9 and CXCL10, similar to mice. However, it promotes the transcription of NF-kB target genes like IL1B and IL12B upon LPS activation. These findings suggest that LXR activation in human macrophages not solely suppresses inflammatory responses in macrophages and that LXR activation has different effects on the regulation of genes mediated by interferon or NF-kB. Our research aims to further uncover the regulatory mechanisms behind LXR activation in human macrophages as central regulators in atherosclerosis.

EZH2 inhibition reduces macrophage inflammatory responses in atherosclerosis

Abstract Funding Acknowledgements Type of funding sources: Foundation. Main funding source(s): Dutch Heart Foundation (Hartstichting) Aim Epigenetic processes are essential modulators of macrophage inflammatory responses. We postulate that interference in the epigenetic machinery of macrophages might offer novel approaches to combat atherosclerosis. Here, we investigate the repressive histone modification H3K27Me3 deposited by the polycomb repressive complex 2 (PRC2) with its catalytic component EZH2. We studied the therapeutic potential of macrophage EZH2 inhibition in the context of atherosclerosis. Methods Human monocyte-derived macrophages and murine peritoneal and bone-marrow derived macrophages were treated with the EZH2-specific inhibitor GSK126 and subsequently activated with LPS to mimic TLR4-inflammatory responses. The impact of Ezh2 inhibition on macrophage differentiation and activation compared to vehicle (DMSO) was assessed by RNA-seq, ChIP-seq, flow cytometry, western blot, and ELISA. To study its impact on atherosclerosis, female Ldlr-/- mice on a high-cholesterol diet (9weeks) were treated the last four weeks with GSK126 or control. Results Ezh2 inhibition by GSK126 in vitro lowered global H3K27Me3 levels without altering macrophage viability and differentiation, showcasing effective EZH2 inhibition. RNA-seq revealed that of more than one-third of the LPS-induced genes were significantly downregulated by EZH2 inhibition. Subsequent pathway analysis identified cytokine and interferon signaling, co-stimulation, and cell migration as the top down-regulated pathways (padj<0.05). Furthermore, ChIP-seq revealed considerably altered regulation of H3K27Me3 deposition. Indeed, we confirmed that gene and cytokine expression of the inflammatory mediators IL-6, IL-12, and TNF were reduced. Furthermore, membrane marker expression of co-stimulatory CD40, CD80, and CD86 were significantly decreased. In murine atherosclerosis, we observed a reduction in the Virmani plaque severity score and are currently assessing lesion size and composition. Conclusion Overall, we show that EZH2 inhibition reduces inflammatory responses in human and murine macrophages in vitro. We are currently assessing the impact of EZH2 inhibition on lesion size and composition in murine atherosclerosis. Additionally, we are performing ex vivo experiments on human endarterectomy plaques to assess the therapeutic potential of EZH2 inhibition on human atherosclerosis.

Decreased atherosclerosis and abdominal aortic aneurysm in mice deficient in polymeric immunoglobulin receptor

Abstract Funding Acknowledgements Type of funding sources: Foundation. Main funding source(s): La Caixa Banking Foundation and Comunidad de Madrid Background Polymeric immunoglobulin receptor (PIGR) is a transmembrane protein involved in the transcytosis of polymeric immunoglobulins that is widely expressed in mucosal epithelial cells. Recent data from our group described increased PIGR levels in plasma and tissue of atherosclerotic subjects. However, the role for PIGR in the mechanisms involved in vascular remodeling has not been addressed. Purpose To analyse the role for PIGR in experimental mouse models of atherosclerosis and abdominal aortic aneurysm (AAA). Methods We analyzed PIGR expression, secretion and distribution in early atherosclerotic plaques and AAA tissues compared to healthy aortic samples, as well as in macrophages derived from the human monocytic THP-1 cell line. Next, we studied the effect of global PIGR deficiency in experimental atherosclerosis (Ldlr-/- Pigr-/- mice fed with atherogenic diet for 10 weeks). In addition, the contribution of hematopoietic PIGR was assessed in both experimental atherosclerosis and AAA (Ldlr-/- mice fed with atherogenic diet and 1 µg/Kg/min angiotensin II infusion for 28 days) by bone marrow transplantation experiments. Finally, bone marrow-derived macrophages (BMDMs) from Pigr-/- and control mice were isolated to assess their inflammatory expression profile and modulation of polarization in response to oxidized LDL (ox-LDL), as well as their ability to promote foam cell formation. Results PIGR expression was increased in the intima of early human atherosclerotic lesions and showed colocalization with CD68+ expression. PIGR expression was also increased during the in vitro differentiation of THP-1 monocytes to macrophages with phorbol myristate acetate. Both global and hematopoietic-specific PIGR deficient mice displayed reduced plaque size in the aortic sinuses as well as a strong decrease in macrophage infiltration (CD68+ cells), while no changes in smooth muscle cells (α-SMA+ cells) and collagen content were observed. Regarding AAA, increased PIGR levels were found in human AAA tissues, associated with infiltrating CD68+ cells. PIGR deficiency in hematopoietic cells also showed significantly reduced AAA dilatation and reduced macrophage infiltration. In vitro experiments with BMDMs obtained from Pigr-/- mice and stimulated with ox-LDL showed reduced proinflammatory gene expression (TNF-a and IL-6) and M1 markers (iNOS and CD11c) as well as diminished foam cell formation. Conclusions PIGR deficiency in hematopoietic cells decreases atherosclerosis and AAA progression by modulating macrophage inflammatory responses, suggesting a novel proinflammatory role for PIGR in vascular pathologies. Future experiments will test the potential therapeutic effect of modulating PIGR to dampen the inflammatory profile in vascular diseases.Results in human and mouse studies

Identification of Mycoplasma pneumoniae proteins interacting with NOD2 and their role in macrophage inflammatory response.

Mycoplasma pneumoniae (M. pneumoniae, Mp) is a cell wall-deficient microorganism known to cause chronic respiratory infections in both children and adults. Nucleotide-binding oligomerization domain-containing protein 2 (NOD2) is an intracellular pattern recognition receptor primarily responsible for identifying muramyl dipeptide (MDP) found in bacterial cell walls. Previous experiments have demonstrated that Mycoplasma ovipneumoniae induces macrophage autophagy through NOD2. In this study, we conducted RNA-seq analysis on macrophages infected with M. pneumoniae and observed an up-regulation in the expression of genes associated with the NOD2 signaling pathway. Mechanistic investigations further revealed the involvement of the NOD2 signaling pathway in the inflammatory response of macrophages activated by M. pneumoniae. We utilized GST pull-down technology in conjunction with liquid chromatography-tandem mass spectrometry (LC-MS/MS) to pinpoint the M. pneumoniae proteins that interact with NOD2. Additionally, co-immunoprecipitation (Co-IP) and immunofluorescence co-localization techniques were used to confirm the interaction between DUF16 protein and NOD2. We found that DUF16 protein can enter macrophages and induce macrophage inflammatory response through the NOD2/RIP2/NF-κB pathway. Notably, the region spanning amino acids 13-90 was identified as a critical region necessary for DUF16-induced inflammation. This research not only broadens our comprehension of the recognition process of the intracellular receptor NOD2, but also deepens our understanding of the development of M. pneumoniae infection.

Effects of interleukin-10 treated macrophages on bone marrow mesenchymal stem cells via signal transducer and activator of transcription 3 pathway.

Alveolar bone defects caused by inflammation are an urgent issue in oral implant surgery that must be solved. Regulating the various phenotypes of macrophages to enhance the inflammatory environment can significantly affect the progression of diseases and tissue engineering repair process. To assess the influence of interleukin-10 (IL-10) on the osteogenic differentiation of bone marrow mesenchymal stem cells (BMSCs) following their interaction with macrophages in an inflammatory environment. IL-10 modulates the differentiation of peritoneal macrophages in Wistar rats in an inflammatory environment. In this study, we investigated its impact on the proliferation, migration, and osteogenesis of BMSCs. The expression levels of signal transducer and activator of transcription 3 (STAT3) and its activated form, phosphorylated-STAT3, were examined in IL-10-stimulated macrophages. Subsequently, a specific STAT3 signaling inhibitor was used to impede STAT3 signal activation to further investigate the role of STAT3 signaling. IL-10-stimulated macrophages underwent polarization to the M2 type through substitution, and these M2 macrophages actively facilitated the osteogenic differentiation of BMSCs. Mechanistically, STAT3 signaling plays a crucial role in the process by which IL-10 influences macrophages. Specifically, IL-10 stimulated the activation of the STAT3 signaling pathway and reduced the macrophage inflammatory response, as evidenced by its diminished impact on the osteogenic differentiation of BMSCs. Stimulating macrophages with IL-10 proved effective in improving the inflammatory environment and promoting the osteogenic differentiation of BMSCs. The IL-10/STAT3 signaling pathway has emerged as a key regulator in the macrophage-mediated control of BMSCs' osteogenic differentiation.

Xiaowugui decoction alleviates experimental rheumatoid arthritis by suppressing Rab5a-mediated TLR4 internalization in macrophages

BackgroundRheumatoid arthritis (RA) is a chronic autoimmune disorder characterized by exacerbated synovial inflammation and joint destruction. Recent studies suggest toll-like receptor 4 (TLR4) internalization facilitate inflammatory response of macrophage. The role of TLR4 internalization in the pathogenesis of RA is unknown. PurposeTo investigate the role and mechanism of TLR4 internalization in macrophage inflammatory response of RA and explore whether TLR4 internalization mediates the anti-arthritic effect of Xiaowugui (XWG) decoction, a patented herbal formula used in China. MethodsThe co-expression of TLR4 and the internalization marker, early endosome antigen 1 (EEA1), in the synovial samples of RA patients and joint tissue of collagen-induced arthritis (CIA) mice, were evaluated using immunofluorescence. The effect of Rab5a-mediated early internalization of TLR4 on the activation induced by lipopolysaccharide (LPS) in RAW264.7 cells was investigated using small interfering RNAs that act against Rab5a. CIA was induced in Rab5a−/− mice to evaluate the role of Rab5a in vivo. The disease progression and expression of Rab5a and TLR4 in the joint tissue were evaluated in CIA mice treated with XWG. Inflammatory factors production, TLR4 internalization, and activation of downstream signaling pathways were examined in RAW264.7 cells treated with XWG in vitro. ResultsThe co-expression and co-localization of TLR4 and EEA1 were elevated in the synovial samples of RA patients and joint tissue of CIA mice. Pharmaceutical inhibition of TLR4 internalization reduced macrophages inflammatory responses induced by LPS. The co-expression and co-localization of Rab5a and TLR4 were significantly increased in macrophages treated with LPS. Silencing Rab5a reduced LPS-induced TLR4 internalization, inflammatory factors production, and phosphorylation of Jun N-terminal kinases (JNK) and p65. Genetic deletion of Rab5a inhibited TLR4 internalization and the development of arthritis in vivo. The co-expression of TLR4 and Rab5a was also elevated in the synovial samples of RA patients. XWG treatment of mice with CIA alleviated arthritis and reduced the co-expression of Rab5a and TLR4 in the joint tissue. XWG treatment of macrophage inhibited LPS-induced IL-6 and TNF-α production, co-expression of Rab5a and TLR4, and phosphorylation of JNK and p65. ConclusionsOur findings highlight the pathogenic role of TLR4 internalization in patients with RA and identify a novel Rab5a-dependent internalization pathway that promotes macrophage inflammatory response. XWG treatment demonstrated outstanding therapeutic effects in experimental arthritis, and targeting the Rab5a-mediated internalization of TLR4 may be the main underlying mechanism.