PSVI-13 Anti-inflammatory effects of polyphenol-rich red osier dogwood extracts in Caco-2 mono- and Caco-2/EA.hy926 co-culture models

Abstract An impaired intestinal barrier function results in aggravating inflammatory response at a systemic scale, eventually leading to rising risk for systemic diseases (e.g., muscle myopathy and vascular disorders). In the present study, the impact of intake polyphenol-rich red osier dogwood extracts (RWE) on the inflammation of endothelial cells was exploited. A strong anti-inflammatory activity of RWE was found to suppress the expression of pro-inflammatory mediators (e.g., IL-8, TNF-α, IL-6, and ICAM) in the inflamed intestinal epithelial cell model. Furthermore, the intestinal transported RWE derived phenolic compounds was shown to protect the endothelial cells against both oxidative and inflammatory damages in a Caco-2/EA.hy926 co-culture cell model. Their protective activities in EA.hy926 was found to be strongly associated with intestinal absorption efficiency. The accumulation of transported rutin and unknown monoglyceride quercetin from RWE were identified across the Caco-2 BBe1 monolayer by HPLC up to 24 h. The highest concentration of transported rutin and monoglyceride quercetin derived from RWE were detected as 2.0 ± 0.22 µg/mL and 0.5 ± 0.08 µg/mL in the basolateral compartment after 12 h and 24 h of incubation, respectively. Profound anti-inflammatory effects of RWE derived polyphenols was observed to suppress pro-inflammatory mediator expression, including IL-8, TNF-α, IL-6, ICAM, VCAM and Cox2, in the TNF-α or oxidized low-density lipoprotein (oxLDL)-induced basolateral EA.hy926 cells (co-culture model). Moreover, we observed a significant inhibitory effect of the transported RWE on oxLDL-induced inflammation after 6 h incubation rather than 24 h, indicating the potential health benefits of RWE is determined by its bioavailability. Results of this study demonstrated that phenolic compounds derived from RWE could be delivered into the circulation system to mitigate inflammatory responses thereby being a promising dietary agent for preventing systemic diseases (e.g., cardiovascular diseases in humans and white stripping/woody meat in broiler chickens).

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Challenge with LPS or TNF-α Demonstrates Unique Differences in Primary Arterial Endothelial Cells Pretreated with Recombinant Human Activated Protein C.

Blood ◽

10.1182/blood.v104.11.1935.1935 ◽

2004 ◽

Vol 104 (11) ◽

pp. 1935-1935

Author(s):

James A. Martin ◽

David E. Joyce ◽

Rashna Balsara ◽

Victoria A. Ploplis ◽

Francis J. Castellino

Keyword(s):

Endothelial Cells ◽

Protein C ◽

Inflammatory Responses ◽

Transcript Levels ◽

Total Rna ◽

Inflammatory Agent ◽

Tnf Α ◽

Anti Inflammatory ◽

Arterial Endothelial Cells ◽

Rna Transcript

Abstract A human recombinant form of the endogenous anticoagulant APC (rhAPC) has been approved for treatment of severe sepsis, a condition with 30-50% mortality and affecting 750,000 US patients per year. Clinical and in vitro studies show that rhAPC has pro-fibrinolytic, anti-inflammatory, and anti-apoptotic properties. In order to better understand the anti-inflammatory mechanism of rhAPC and its receptor EPCR on primary murine aortic endothelial cells (EC), responses were compared between wild type (WT) and low-expressing endothelial protein C receptor (EPCRδ/δ) EC by total RNA for specified endothelial inflammatory markers. The purpose was to determine the effect of rhAPC and low expression of EPCR on murine arterial EC responses to tumor necrosis factor alpha (TNF-α) or endotoxin (LPS). EC from C57BL/6 mice aorta, WT or EPCRδ/δ, were isolated, cultured, and positively selected for EC markers (CD105, CD106). EC in serum free media were pretreated with 5ug/mL rhAPC (Eli Lilly) for 16 hours followed by challenge with 100ng/mL TNF-α or 10ug/mL LPS for 8 hours. Total RNA was analyzed by Quantitative Real-time PCR (QRT-PCR) for CXC chemokines MIP-2 and KC, adhesion markers E-Selectin or ICAM-1, cytokines MCP-1 and IL-6, and NFκB-1. Mean +/− standard error of the mean for the time points (T0, 0.5hr, 1hr, 2hr, 4hr, and 8hr) after TNF-α or LPS were compared between treatment groups. Both TNF-α and LPS produced expected characteristic fold changes of RNA expression over the eight hour time period in the murine EC. Without rhAPC EPCRδ/δ EC showed a similar response compared to WT EC. When pretreated with rhAPC for 16 hours followed by LPS challenge, EC RNA transcript levels for CXC chemokines and adhesion markers were suppressed more in EPCRδ/δ compared to WT EC. When pretreated with rhAPC for 16 hours followed by TNF-α challenge, RNA transcript levels for CXC chemokines and adhesion markers were elevated or showed little change in WT EC and EPCRδ/δ EC compared to EC not given rhAPC. Nuclear factor NFκB-1 RNA was suppressed in both WT EC and EPCRδ/δ EC with rhAPC pretreatment and subsequent inflammatory agent (LPS or TNF-α). Most striking was the unexpected suppressed response of rhAPC pretreated EPCRδ/δ EC compared to WT EC after addition of either inflammatory agent. Further studies suggested that surface EPCR protein did not appear to be enhanced with any treatment combination, or with rhAPC alone. These results are consistent with previously reported endothelial cell specific rhAPC response of CXC chemokines and the ability of rhAPC to suppress other TNF-α mediated inflammatory responses (eg. MCP-1 and NFkB-1). In addition, rhAPC pretreatment appeared to suppress LPS mediated inflammatory responses, including CXC chemokines. The enhanced suppression of inflammatory responses seen in arterial EPCRδ/δ EC compared to WT EC remains unexplained. Results from this study also indicate primary murine arterial endothelial cells treated with rhAPC respond differently to challenge with TNF-α versus LPS.

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Insulin and IGF1 receptors in human cardiac microvascular endothelial cells: metabolic, mitogenic and anti-inflammatory effects

Journal of Endocrinology ◽

10.1530/joe-12-0261 ◽

2012 ◽

Vol 215 (1) ◽

pp. 89-96 ◽

Cited By ~ 16

Author(s):

Karolina Bäck ◽

Rakibul Islam ◽

Git S Johansson ◽

Simona I Chisalita ◽

Hans J Arnqvist

Keyword(s):

Gene Expression ◽

Endothelial Cells ◽

Inflammatory Responses ◽

Receptor Protein ◽

Microvascular Endothelial Cells ◽

Tnf Α ◽

Glucose Accumulation ◽

Anti Inflammatory ◽

Microvascular Endothelial ◽

Cardiac Microvascular Endothelial Cells

Diabetes is associated with microcirculatory dysfunction and heart failure and changes in insulin and IGF1 levels. Whether human cardiac microvascular endothelial cells (HMVEC-Cs) are sensitive to insulin and/or IGF1 is not known. We studied the role of insulin receptors (IRs) and IGF1 receptors (IGF1Rs) in metabolic, mitogenic and anti-inflammatory responses to insulin and IGF1 in HMVEC-Cs and human umbilical vein endothelial cells (HUVECs). IR and IGF1R gene expression was studied using real-time RT-PCR. Receptor protein expression and phosphorylation were determined by western blot and ELISA. Metabolic and mitogenic effects were measured as glucose accumulation and thymidine incorporation. An E-selectin ELISA was used to investigate inflammatory responses. According to gene expression and protein in HMVEC-Cs and HUVECs, IGF1R is more abundant than IR. Immunoprecipitation with anti-IGF1R antibody and immunoblotting with anti-IR antibody and vice versa, showed insulin/IGF1 hybrid receptors in HMVEC-Cs. IGF1 at a concentration of 10−8 mol/l significantly stimulated phosphorylation of both IGF1R and IR in HMVEC-Cs. In HUVECs IGF1 10−8 mol/l phosphorylated IGF1R. IGF1 stimulated DNA synthesis at 10−8 mol/l and glucose accumulation at 10−7 mol/l in HMVEC-Cs. TNF-α dramatically increased E-selectin expression, but no inflammatory or anti-inflammatory effects of insulin, IGF1 or high glucose were seen. We conclude that HMVEC-Cs express more IGF1Rs than IRs, and mainly react to IGF1 due to the predominance of IGF1Rs and insulin/IGF1 hybrid receptors. TNF-α has a pronounced pro-inflammatory effect in HMVEC-Cs, which is not counteracted by insulin or IGF1.

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Chios Mastic Gum Extract and Isolated Phytosterol Tirucallol Exhibit Anti-Inflammatory Activity in Human Aortic Endothelial Cells

Experimental Biology and Medicine ◽

10.3181/0811-rm-338 ◽

2009 ◽

Vol 234 (5) ◽

pp. 553-561 ◽

Cited By ~ 27

Author(s):

Stella Loizou ◽

Sotirios Paraschos ◽

Sofia Mitakou ◽

George P. Chrousos ◽

Ioannis Lekakis ◽

...

Keyword(s):

Endothelial Cells ◽

Adhesion Molecules ◽

U937 Cells ◽

Aortic Endothelial Cells ◽

Tnf Α ◽

Chios Mastic Gum ◽

Anti Inflammatory ◽

The Impact ◽

Human Aortic Endothelial Cells ◽

Aortic Endothelial

Chios mastic gum (CMG) is a white, semitransparent, natural resin that is obtained as a trunk exudate from mastic trees. Triterpenic compounds and phytosterols like tirucallol are among its major components. CMG has been associated with cardiovascular protection, exerting its effect mainly through increasing the antioxidant defense system, and effectively lowering the levels of serum cholesterol in human subjects. However, data on its anti-inflammatory effect on endothelium are scarce. Attachment of leukocytes to the vascular endothelium and the subsequent migration of cells into the vessel wall are early events in atherogenesis, and this process requires the expression of endothelial adhesion molecules. In this study, we examined the effect of CMG neutral extract (25–200 μ g/ml) and tirucallol (0.1–100 μ M) on the following: 1) the expression of adhesion molecules (VCAM-1 and ICAM-1) by Cell ELISA and 2) the attachment of monocytes (U937 cells) in TNF-α stimulated Human Aortic Endothelial Cells (HAEC) by Adhesion assay. The impact of treatment with CMG neutral extract and tirucallol in NFkB phosphorylation was also examined by a cell-based ELISA kit. Both CMG extract and tirucallol inhibit significantly VCAM-1 and ICAM-1 expression in TNF-α-stimulated HAEC. They also inhibit significantly the binding of U937 cells to TNF-α-stimulated HAEC and attenuate the phosphorylation of NFkB p65. This study extends existing data regarding the cardioprotective effect of CMG, expands the spectrum of known phytosterols with potent antiatheromatic activity, provides new insight into the mechanisms underlying the beneficial effect of CMG on endothelial function, and may aid in design of new therapy for intervention in atherosclerosis.

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Nootkatone Inhibits Acute and Chronic Inflammatory Responses in Mice

Molecules ◽

10.3390/molecules25092181 ◽

2020 ◽

Vol 25 (9) ◽

pp. 2181 ◽

Cited By ~ 2

Author(s):

Lindaiane Bezerra Rodrigues Dantas ◽

Ana Letícia Moreira Silva ◽

Cícero Pedro da Silva Júnior ◽

Isabel Sousa Alcântara ◽

Maria Rayane Correia de Oliveira ◽

...

Keyword(s):

Chronic Inflammation ◽

Acute Inflammation ◽

Inflammatory Responses ◽

In Silico Analysis ◽

Histamine Receptor ◽

Tnf Α ◽

Cox 2 ◽

Anti Inflammatory ◽

Acute And Chronic Inflammation ◽

The Impact

Nootkatone (NTK) is a sesquiterpenoid found in essential oils of many species of Citrus (Rutaceae). Considering previous reports demonstrating that NTK inhibited inflammatory signaling pathways, this study aimed to investigate the effects of this compound in mice models of acute and chronic inflammation. Murine models of paw edema induced by carrageenan, dextran, histamine, and arachidonic acid, as well as carrageenan-induced peritonitis and pleurisy, were used to evaluate the effects of NTK on acute inflammation. A murine model of granuloma induced by cotton pellets was used to access the impact of NTK treatment on chronic inflammation. In the acute inflammation models, NTK demonstrated antiedematogenic effects and inhibited leukocyte recruitment, which was associated with decreased vascular permeability, inhibition of myeloperoxidase (MPO), interleukin (IL)1-β, and tumor necrosis factor (TNF)-α production. In silico analysis suggest that NTZ anti-inflammatory effects may also occur due to inhibition of cyclooxygenase (COX)-2 activity and antagonism of the histamine receptor type 1 (H1). These mechanisms might have contributed to the reduction of granuloma weight and protein concentration in the homogenates, observed in the chronic inflammation model. In conclusion, NTK exerted anti-inflammatory effects that are associated with inhibition of IL1-β and TNF-α production, possibly due to inhibition of COX-2 activity and antagonism of the H1 receptor. However, further studies are required to characterize the effects of this compound on chronic inflammation.

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Anti-Inflammatory Effect and Cellular Uptake Mechanism of Carbon Nanodots in in Human Microvascular Endothelial Cells

Nanomaterials ◽

10.3390/nano11051247 ◽

2021 ◽

Vol 11 (5) ◽

pp. 1247

Author(s):

Sarah Belperain ◽

Zi Yae Kang ◽

Andrew Dunphy ◽

Brandon Priebe ◽

Norman H. L. Chiu ◽

...

Keyword(s):

Endothelial Cells ◽

Interleukin 1 ◽

Antioxidant Properties ◽

Synthesis Method ◽

Microvascular Endothelial Cells ◽

Carbon Nanodots ◽

Uptake Mechanism ◽

Tnf Α ◽

Anti Inflammatory ◽

Microvascular Endothelial

Cardiovascular disease (CVD) has become an increasingly important topic in the field of medical research due to the steadily increasing rates of mortality caused by this disease. With recent advancements in nanotechnology, a push for new, novel treatments for CVD utilizing these new materials has begun. Carbon Nanodots (CNDs), are a new form of nanoparticles that have been coveted due to the green synthesis method, biocompatibility, fluorescent capabilities and potential anti-antioxidant properties. With much research pouring into CNDs being used as bioimaging and drug delivery tools, few studies have been completed on their anti-inflammatory potential, especially in the cardiovascular system. CVD begins initially by endothelial cell inflammation. The cause of this inflammation can come from many sources; one being tumor necrosis factor (TNF-α), which can not only trigger inflammation but prolong its existence by causing a storm of pro-inflammatory cytokines. This study investigated the ability of CNDs to attenuate TNF-α induced inflammation in human microvascular endothelial cells (HMEC-1). Results show that CNDs at non-cytotoxic concentrations reduce the expression of pro-inflammatory genes, mainly Interleukin-8 (IL-8), and interleukin 1 beta (IL-1β). The uptake of CNDs by HMEC-1s was examined. Results from the studies involving channel blockers and endocytosis disruptors suggest that uptake takes place by endocytosis. These findings provide insights on the interaction CNDs and endothelial cells undergoing TNF-α induced cellular inflammation.

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In Vitro Evaluation of the Anti-Inflammatory Effect of KMUP-1 and in Vivo Analysis of Its Therapeutic Potential in Osteoarthritis

Biomedicines ◽

10.3390/biomedicines9060615 ◽

2021 ◽

Vol 9 (6) ◽

pp. 615

Author(s):

Shang-En Huang ◽

Erna Sulistyowati ◽

Yu-Ying Chao ◽

Bin-Nan Wu ◽

Zen-Kong Dai ◽

...

Keyword(s):

Articular Cartilage ◽

Inflammatory Responses ◽

Therapeutic Potential ◽

Antioxidant Properties ◽

Serum Levels ◽

Gene Expressions ◽

Tnf Α ◽

Anti Inflammatory

Osteoarthritis is a degenerative arthropathy that is mainly characterized by dysregulation of inflammatory responses. KMUP-1, a derived chemical synthetic of xanthine, has been shown to have anti-inflammatory and antioxidant properties. Here, we aimed to investigate the in vitro anti-inflammatory and in vivo anti-osteoarthritis effects of KMUP-1. Protein and gene expressions of inflammation markers were determined by ELISA, Western blotting and microarray, respectively. RAW264.7 mouse macrophages were cultured and pretreated with KMUP-1 (1, 5, 10 μM). The productions of TNF-α, IL-6, MMP-2 and MMP- 9 were reduced by KMUP-1 pretreatment in LPS-induced inflammation of RAW264.7 cells. The expressions of iNOS, TNF-α, COX-2, MMP-2 and MMP-9 were also inhibited by KMUP-1 pretreatment. The gene expression levels of TNF and COX families were also downregulated. In addition, KMUP-1 suppressed the activations of ERK, JNK and p38 as well as phosphorylation of IκBα/NF-κB signaling pathways. Furthermore, SIRT1 inhibitor attenuated the inhibitory effect of KMUP-1 in LPS-induced NF-κB activation. In vivo study showed that KMUP-1 reduced mechanical hyperalgesia in monoiodoacetic acid (MIA)-induced rats OA. Additionally, KMUP-1 pretreatment reduced the serum levels of TNF-α and IL-6 in MIA-injected rats. Moreover, macroscopic and histological observation showed that KMUP-1 reduced articular cartilage erosion in rats. Our results demonstrated that KMUP-1 inhibited the inflammatory responses and restored SIRT1 in vitro, alleviated joint-related pain and cartilage destruction in vivo. Taken together, KMUP-1 has the potential to improve MIA-induced articular cartilage degradation by inhibiting the levels and expression of inflammatory mediators suggesting that KMUP-1 might be a potential therapeutic agent for OA.

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Comparative Phenotypic and Functional Analyses of the Effects of IL-10 or TGF-β on Porcine Macrophages

Animals ◽

10.3390/ani11041098 ◽

2021 ◽

Vol 11 (4) ◽

pp. 1098

Author(s):

Tania Carta ◽

Elisabetta Razzuoli ◽

Floriana Fruscione ◽

Susanna Zinellu ◽

Dionigia Meloni ◽

...

Keyword(s):

Macrophage Polarization ◽

Phagocytic Cells ◽

Mhc Ii ◽

Tnf Α ◽

Regulated Expression ◽

Inflammatory Phenotype ◽

Anti Inflammatory ◽

Functional Analyses ◽

The Impact ◽

Immunosuppressive Cytokines

Macrophages are phagocytic cells involved in maintaining tissue homeostasis and defense against pathogens. Macrophages may be polarized into different functionally specialized subsets. M2c macrophages arise following stimulation with IL-10 or TGF-β and mediate anti-inflammatory and tissue repair functions. M2c macrophages remain poorly characterized in the pig, thus we investigated the impact of these regulatory cytokines on porcine monocyte-derived macrophages (moMΦ). The phenotype and functionality of these cells was characterized though confocal microscopy, flow cytometry, ELISA, and RT-qPCR. Both cytokines induced CD14 and MHC II DR down-regulation and reduced IL-6, TNF-α, and CD14 expression, suggestive of an anti-inflammatory phenotype. Interestingly, neither IL-10 or TGF-β were able to trigger IL-10 induction or release by moMΦ. Differences between these cytokines were observed: stimulation with IL-10, but not TGF-β, induced up-regulation of both CD16 and CD163 on moMΦ. In addition, IL-10 down-regulated expression of IL-1β and IL-12p40 4h post-stimulation and induced a stronger impairment of moMΦ ability to respond to either TLR2 or TLR4 agonists. Overall, our results provide an overview of porcine macrophage polarization by two immunosuppressive cytokines, revealing differences between IL-10 and TGF-β, and reporting some peculiarity of swine, which should be considered in translational studies.

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Abstract 116: Slit-Robo Signaling Regulates Lipopolysaccharide-induced Endothelial Inflammation and Expression of Slit/Robo is Dysregulated During Endotoxemia

Circulation Research ◽

10.1161/res.113.suppl_1.a116 ◽

2013 ◽

Vol 113 (suppl_1) ◽

Author(s):

Helong Zhao ◽

Appakkudal Anand ◽

Ramesh Ganju

Keyword(s):

Endothelial Cells ◽

Cell Adhesion ◽

Inflammatory Responses ◽

Umbilical Vein ◽

Model Studies ◽

Endothelial Inflammation ◽

Anti Inflammatory ◽

Whole Heart

Abstract Introduction: Lipopolysaccharide (LPS) is one of the critical factors which induce endothelial inflammation during the pathogenesis of atherosclerosis, endocarditis and sepsis shock induced heart injury. The secretory Slit2 protein and its endothelial receptors Robo1 and Robo4 have been shown to regulate mobility and permeability of endothelial cells, which could be functional in regulating LPS induced endothelial inflammation. Hypothesis: We hypothesized that in addition to regulating permeability and migration of endothelial cells, Slit2-Robo1/4 signaling might regulate other LPS-induced endothelial inflammatory responses. Methods and Results: Using Human Umbilical Vein Endothelial Cells (HUVEC) culture, we observed that Slit2 treatment suppressed LPS-induced secretion of pro-inflammatory cytokines (including GM-CSF), cell adhesion molecule upregulation and monocyte (THP-1 cell) adhesion. With siRNA knock down techniques, we further confirmed that this anti-inflammatory effect is mediated by the interaction of Slit2 with its dominant receptor in endothelial cells, Robo4, though the much lesser expressed minor receptor Robo1 is pro-inflammatory. Our signaling studies showed that downstream of Robo4, Slit2 suppressed inflammatory gene expression by inhibiting the Pyk2 - NF-kB pathway following LPS-TLR4 interaction. In addition, Slit2 can induce a positive feedback to its expression and downregulate the pro-inflammatory Robo1 receptor via mediation of miR-218. Moreover, both in in vitro studies using HUVEC and in vivo mouse model studies indicated that LPS also causes endothelial inflammation by downregulating the anti-inflammatory Slit2 and Robo4 and upregulating the pro-inflammatory Robo1 during endotoxemia, especially in mouse arterial endothelial cells and whole heart. Conclusions: Slit2-Robo1/4 signaling is important in regulation of LPS induced endothelial inflammation, and LPS in turn causes inflammation by interfering with the expression of Slit2, Robo1 and Robo4. This implies that Slit2-Robo1/4 is a key regulator of endothelial inflammation and its dysregulation during endotoxemia is a novel mechanism for LPS induced cardiovascular pathogenesis.

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Methyl jasmonate reduces the inﬂammation and apoptosis of HK-2 cells induced by LPS by regulating the NF-κB pathway

10.22514/10.22514/sv.2021.079 ◽

2021 ◽

Keyword(s):

Cell Viability ◽

Methyl Jasmonate ◽

Cell Apoptosis ◽

Cell Model ◽

Tubular Epithelial Cell ◽

Cell Protein ◽

Epithelial Cell Line ◽

Tnf Α ◽

Iκbα Phosphorylation ◽

Anti Inflammatory

Background: Methyl jasmonate is a bioactive oxylipid that participates in the defense-related mechanisms of plants. The anti-inflammatory and anti-oxidative capacities of methyl jasmonate against lipopolysaccharide (LPS) induced arthritis have been widely investigated. However, the role of methyl jasmonate in LPS-induced cell model of tubular-interstitial nephritis (TIN) has not been reported. Methods: LPS (5 µg/mL) was applied to treat human renal tubular epithelial cell line (HK-2) for the establishment of TIN cell model. LPS-induced HK-2 was incubated with 10 or 20 µM methyl jasmonate, cell viability and apoptosis were assessed by MTT and flow cytometry. ELISA and qRT-PCR were performed to determine the levels of interleukin (IL)-1 beta (IL-1β), IL-6, IL-8 and tumor necrosis factor-α (TNF-α). The downstream pathway was investigated by western blot. Results: LPS induced cytotoxicity in HK-2 cell accompanied by decrease of cell viability and increase of cell apoptosis. Methyl jasmonate dosage dependently enhanced the cell viability and reduced cell apoptosis to ameliorate the cytotoxicity. LPS also induced inflammatory response in HK-2 cell with increased IL-1β, IL-6, IL-8 and TNF-α. Methyl jasmonate attenuated LPS-induced inflammation in HK-2 cell. Protein expression of IκBα was down-regulated, p65 and IκBα phosphorylation were up-regulated in LPS-induced HK-2. Methyl jasmonate attenuated LPS-induced decrease of IκBα and increase of p65 and IκBα phosphorylation in HK-2 cell. Conclusion: Methyl jasmonate demonstrated anti-apoptotic and anti-inflammatory effects on LPS-induced HK-2 cell through suppression of NF-κB activation.

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Abstract 553: Siglec-1 (CD169) on Monocytes/Macrophages: A New Receptor For Extracellular Self-RNA in Triggering Inflammatory Responses via the Sheddase TACE/ADAM17

Arteriosclerosis Thrombosis and Vascular Biology ◽

10.1161/atvb.35.suppl_1.553 ◽

2015 ◽

Vol 35 (suppl_1) ◽

Author(s):

Hector A Cabrera-Fuentes ◽

Klaus T Preissner ◽

William A Boisvert

Keyword(s):

Inflammatory Cytokines ◽

Inflammatory Responses ◽

Transmembrane Protein ◽

Macrophage Polarization ◽

Extracellular Rna ◽

Tnf Α ◽

M1 Phenotype ◽

Phenotype Markers ◽

Anti Inflammatory

As an important component of atherosclerosis, monocytes/macrophages respond to external stimuli with rapid changes in their expression of many inflammation-related genes to undergo polarization towards the M1 (pro-inflammatory) or M2 (anti-inflammatory) phenotype. Although sialoadhesin (Sn), also known as SIGLEC-1 or CD169, is a transmembrane protein receptor expressed on monocytes and macrophages whether it has a role in macrophage polarization and ultimately, macrophage-driven atherogenesis, has not been investigated. We have previously shown that, independently of Toll-like receptor signaling, extracellular RNA (eRNA) could exert pro-thrombotic and pro-inflammatory properties in the cardiovascular system by inducing cytokine mobilization. In the current study, recombinant mouse macrophage CSF[[Unable to Display Character: –]]driven bone marrow-derived macrophage (BMDM) differentiation was found to be skewed towards the M1 phenotype by exposure of cells to eRNA. This resulted in up-regulation of inflammatory markers, whereas anti-inflammatory genes were significantly down-regulated by eRNA. Interestingly, eRNA was released from BMDM under hypoxia and induced TNF-α liberation by activating TNF-α converting enzyme (TACE) to provoke inflammation. Conversely, TNF-α promoted eRNA release, especially under hypoxia, feeding a vicious cycle of cell damage. Administration of RNase1 or TAPI (a TACE-inhibitor) prevented the production of inflammatory mediators. Murine BMDM isolated from mice deficient in sialoadhesin had the opposite reaction to eRNA treatment with a prominent down-regulation of pro-inflammatory cytokines/M1 phenotype markers, while anti-inflammatory cytokines/M2 phenotype markers were significantly raised. In keeping with the proposed role of eRNA as a pro-inflammatory “alarm signal”, these data further shed light on the role of eRNA in macrophage function in the context of chronic inflammatory diseases such as atherosclerosis. The identification of sialoadhesin as putative eRNA recognition site on macrophages may allow further investigation of the underlying mechanisms of eRNA-macrophage interaction and related signal transduction pathways. Siglec-1 thereby may provides a new target to treat eRNA-mediated vascular diseases.

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