Abstract 464: Membrane Microparticles From Ischemic Muscle Induce In Vitro Progenitor Cells Differentiation And In Vivo Neovascularization.

Circulation ◽  
2007 ◽  
Vol 116 (suppl_16) ◽  
Author(s):  
Aurelie S Leroyer ◽  
Teni G Ebrahimian ◽  
Jose Vilar ◽  
Bernard I Levy ◽  
Alain Tedgui ◽  
...  
Keyword(s):  
Endothelial Cells ◽  
Progenitor Cells ◽  
Cell Activation ◽  
Mononuclear Cells ◽  
Artery Ligation ◽  
Control Muscle ◽  
Tissue Ischemia ◽  
Subunit Expression

Postischemic neovascularization is mediated, at least in part, by the homing of progenitor cells to sites of injury and their differentiation into endothelial cells (EC). However, the mechanisms of in situ progenitor differentiation remain for the most part unknown. We hypothesized that miproparticles (MPs) released following ischemia-induced cell activation or apoptosis are the endogenous signal of postischemic vasculogenesis. MPs were detected by electron microscopy as vesicles of 0.1 to 1 μm in diameter in mice ischemic hindlimb muscle, 48hrs after unilateral femoral artery ligation. After isolation by sequential centrifugations, flow cytometry analyses showed that AnnexinV+ MPs concentration in ischemic calf was 3.5-fold higher than in control muscle (1392±406 vs. 394±180 AnnV+MPs/mg, p<0.005) and mainly originated from endothelial cells (47% of MPs are CD144+). MPs isolated from ischemic muscles induced a more potent in vitro bone marrow-mononuclear cells (BM-MNC) differentiation into EPC, than those isolated from control muscle (6.1±1.0% vs. 3.5±0.7% Dil-LDL/BS1lectin+ cells/field, p<0.05). Moreover, MPs isolated from GFP+ ischemic muscles colocalized with differentiated BM-MNC. MPs isolated from atherosclerotic plaque were uneffective whereas those isolated from apoptotic or IL-1 activated EC also promoted BM-MNC differentiation. Interestingly, MPs from ischemic muscles produced more reactive oxygen species and expressed significantly higher levels of NADPH oxidase p47 (6 fold ; p<0.05) and p67 subunits (16 fold ; p<0.005) than those from control, whereas gp91 subunit expression was unchanged. The MPs-induced BM-MNC differentiation was reduced by two fold with MPs isolated from gp91-deficient mice (p<0.05). MPs effect on post-ischemic vasculogenesis and revascularization was examined in the ischemic hindlimb model. MPs isolated from ischemic muscles were injected into ischemic legs in parallel with venous injection of BM-MNC. MPs increased the pro-angiogenic effect of BM-MNC transplantation and this effect was blunted with MPs from gp91−/− mice. These results demonstrate that MPs produced after tissue ischemia stimulate progenitor cell differentiation and subsequently promote postnatal neovascularization.

Two Classes of Progenitor Cells in Patients with Myeloproliferative Disorders Are Capable of Generating JAK2V617F+CD31+CD144+ Endothelial Cells.

Blood ◽  
2007 ◽  
Vol 110 (11) ◽  
pp. 261-261
Author(s):  
Selcuk Sozer ◽  
Takefumi Ishii ◽  
Wei Zhang ◽  
Jiapeng Wang ◽  
Mingjiang Xu ◽  
...  
Keyword(s):  
Endothelial Cells ◽  
Progenitor Cells ◽  
Mononuclear Cells ◽  
Vascular Endothelial Cells ◽  
Inverse Correlation ◽  
Primary Myelofibrosis ◽  
Myeloproliferative Disorders ◽  
Growth Media

Abstract Patients with myeloproliferative disorders (MPD) are at a high risk of developing thrombotic events. We hypothesize that one of the contributory factors to this thrombotic tendency is the involvement of vascular endothelial cells (EC) by the malignant process. In vitro and in vivo assays were used to determine the involvement of EC in patients with MPD. Endothelial progenitor cells (EPC) were assayed from the peripheral blood (PB) mononuclear cells (MNCs) of 3 normal controls (NC) and 16 patients with MPD (12 polycythemia vera (PV), 4 primary myelofibrosis (PMF). MNC were cultured for 2 days in EC growth media on fibronectin(FN)-coated plates. The non-adherent cells were then harvested and transferred to a secondary FN-coated plate for additional 5–14 days. EC colonies were identified by their morphological appearance. The colonies were plucked and analyzed for PECAM-1(CD31), VE-Cadherin(CD144), VEGFR-2, vWF, Endoglin(CD105), ULEX-1, CD45, CD14 by flow cytometry and acetylated LDL(Ac-ADL) uptake. EC colonies were CD31+CD144+VEGFR2+ULEX-1+vWF+CD105+CD45+CD14+ and capable of taking up Ac-LDL and when exposed to TNF-α and IL-1β, expressing ICAM(CD54) and E-selectin(CD62e). MPD MNC formed fewer numbers of EC colonies than normal MNC (31.1±34.2 vs 78.8±28.9; p&lt;0.01) and required more prolonged periods of culture (14 vs 5days). MPD EC colonies were also analyzed for JAK2V617F(JAK2VF) by nested-PCR. 74.6% of MPD EC colonies were homozygous(homo) JAK2VF, 14.9% were heterozygous(hetero) JAK2VF and 10.4% were wild type(wt) JAK2. Interestingly, MNCs from JAK2VF−MPD(148±47) formed greater numbers of EC colonies than NC MNC (78.8±28.9; p≤0.01). MNC from patients with a high burden of JAK2VF alleles (10.3±18.5; p&lt;0.01) formed fewer EC colonies than NC or patients with a low burden of JAK2VF (65.9±28.15; p≤0.01). These EPC assayed in vitro which produced cells with both myeloid and endothelial markers are likely due either to contamination with JAK2VF myeloid cells or the result of the transdifferentiation of myeloid progenitor cells into EC (Bailey A, et al. PNAS.2006,103:13156). The inverse correlation between the JAK2VF burden and the ability of MPD MNC to form EC colonies is possibly a consequence of the increased sensitivity of EC to apoptosis due to the constitutive activation of JAK2 (Neria F, et al. Am J Physiol Cell Physiol.2007, 292:1123). In order to assay for more primitive EPC, 2 cord blood, and 16 JAK2VF+ MPD CD34+ (10 PV, 6 PMF) cells were transplanted into sublethally irradiated NOD/SCID mice. After 8 weeks, EC-rich organs (heart, lung, liver, vessels) were harvested, single cell suspensions were positively selected for either human(h) CD31+or hCD144+ cells by immunomagnetic cell sorting and analyzed for hVEGFR2, CD144, vWF, CD45, CD14 mRNA expression and JAK2VF. These CD31+or CD144+ cells contained transcripts for CD144, vWF, VEGFR2 but not CD45 and CD14. In 77.7% of the cases the hCD31+ or hCD144+ cells were homo JAK2VF, 5.5% were hetero JAK2VF and 16.6% were wt JAK2 and these CD31+or CD144+ cells composed ≤1% of the cells within the respective tissues. hCD144+ cells were also cultured with EC growth media for 7 days and displayed EC morphology and were shown to contain JAK2VF+ cells. These CD31+CD144+JAK2VF+CD14−CD45−cells likely represent the progeny of a malignant EPC which is distinct from an HSC. The involvement of EC by the malignant process in MPD might contribute to the development of thrombosis in MPD.

scholarly journals PD-L1hi plasmablasts limit the T cell response during the acute phase of parasite infections

2020 ◽  
Author(s):  
Melisa Gorosito Serrán ◽  
Facundo Fiocca Vernengo ◽  
Laura Almada ◽  
Cristian G Beccaria ◽  
Pablo F Canete ◽  
...  
Keyword(s):  
T Cell ◽  
Cell Response ◽  
Cell Activation ◽  
Mononuclear Cells ◽  
Plasma Cells ◽  
Chronic Phase ◽  
Surface Expression ◽  
T Cell Response

ABSTRACTDuring infections with protozoan parasites or virus, T cell immunosuppression is generated simultaneously with a high B cell activation. Here, we show that in T. cruzi infection, all plasmablasts detected had higher surface expression of PD-L1, than other mononuclear cells. PD-L1hi plasmablasts were induced in vivo in an antigen-specific manner and required help from Bcl-6+CD4+T cells. PD-L1hi expression was not a characteristic of all antibody-secreting cells since plasma cells found during the chronic phase of infection express PD-L1 but at lower levels. PD-L1hi plasmablasts were also present in mice infected with Plasmodium or with lymphocytic choriomeningitis virus, but not in mice with autoimmune disorders or immunized with T cell-dependent antigens. PD-L1hi plasmablasts suppressed T cell response, via PD-L1, in vitro and in vivo. Thus, this study reveals that extrafollicular PD-L1hi plasmablasts, which precede the germinal center (CG) response, are a suppressive population in infections that may influence T cell response.Brief summaryPathogens develop different strategies to settle in the host. We identified a plasmablats population induced by pathogens in acute infections which suppress T cell response.

scholarly journals Exosomes derived from induced vascular progenitor cells promote angiogenesis in vitro and in an in vivo rat hindlimb ischemia model

2019 ◽  
Vol 317 (4) ◽  
pp. H765-H776 ◽  
Author(s):  
Takerra K. Johnson ◽  
Lina Zhao ◽  
Dihan Zhu ◽  
Yang Wang ◽  
Yan Xiao ◽  
...  
Keyword(s):  
Endothelial Cells ◽  
Progenitor Cells ◽  
Ex Vivo ◽  
Aortic Ring ◽  
Size Exclusion ◽  
Hindlimb Ischemia ◽  
Vascular Progenitor Cells ◽  
Angiogenic Effect

Induced vascular progenitor cells (iVPCs) were created as an ideal cell type for regenerative medicine and have been reported to positively promote collateral blood flow and improve cardiac function in a rat model of myocardial ischemia. Exosomes have emerged as a novel biomedicine that mimics the function of the donor cells. We investigated the angiogenic activity of exosomes from iPVCs (iVPC-Exo) as a cell-free therapeutic approach for ischemia. Exosomes from iVPCs and rat aortic endothelial cells (RAECs) were isolated using a combination of ultrafiltration and size-exclusion chromatography. Nanoparticle tracking analysis revealed that exosome isolates fell within the exosomal diameter (<150 nm). These exosomes contained known markers Alix and TSG101, and their morphology was validated using transmission electron microscopy. When compared with RAECs, iVPCs significantly increased the secretion of exosomes. Cardiac microvascular endothelial cells and aortic ring explants were pretreated with RAEC-Exo or iVPC-Exo, and basal medium was used as a control. iVPC-Exo exerted an in vitro angiogenic effect on the proliferation, tube formation, and migration of endothelial cells and stimulated microvessel sprouting in an ex vivo aortic ring assay. Additionally, iVPC-Exo increased blood perfusion in a hindlimb ischemia model. Proangiogenic proteins (pentraxin-3 and insulin-like growth factor-binding protein-3) and microRNAs (-143-3p, -291b, and -20b-5p) were found to be enriched in iVPC-Exo, which may mediate iVPC-Exo induced vascular growth. Our findings demonstrate that treatment with iVPC-Exo promotes angiogenesis in vitro, ex vivo, and in vivo. Collectively, these findings indicate a novel cell-free approach for therapeutic angiogenesis. NEW & NOTEWORTHY The results of this work demonstrate exosomes as a novel physiological mechanism by which induced vascular progenitor cells exert their angiogenic effect. Moreover, angiogenic cargo of proteins and microRNAs may define the biological contributors in activating endothelial cells to form a new capillary plexus for ischemic vascular diseases. Listen to this article's corresponding podcast at https://ajpheart.podbean.com/e/angiogenic-exosomes-from-vascular-progenitor-cells/ .

Donor Origin of Multipotent Adult Progenitor Cells in Radiation Chimeras.

Blood ◽  
2005 ◽  
Vol 106 (11) ◽  
pp. 1395-1395
Author(s):  
Morayma Reyes ◽  
Jeffrey S. Chamberlain
Keyword(s):  
Stem Cells ◽  
Bone Marrow ◽  
Stem Cell ◽  
Progenitor Cells ◽  
Y Chromosome ◽  
Stromal Cells ◽  
Mononuclear Cells ◽  
Multipotent Adult Progenitor Cells

Abstract Multipotent Adult Progenitor Cells (MAPC) are bone marrow derived stem cells that can be extensively expanded in vitro and can differentiate in vivo and in vitro into cells of all three germinal layers: ectoderm, mesoderm, endoderm. The origin of MAPC within bone marrow (BM) is unknown. MAPC are believed to be derived from the BM stroma compartment as they are isolated within the adherent cell component. Numerous studies of bone marrow chimeras in human and mouse point to a host origin of bone marrow stromal cells, including mesenchymal stem cells. We report here that following syngeneic bone marrow transplants into lethally irradiated C57Bl/6 mice, MAPC are of donor origin. When MAPC were isolated from BM chimeras (n=12, 4–12 weeks post-syngeneic BM transplant from a transgenic mouse ubiquitously expressing GFP), a mixture of large and small GFP-positive and GFP-negative cells were seen early in culture. While the large cells stained positive for stroma cell markers (smooth muscle actin), mesenchymal stem cell makers (CD73, CD105, CD44) or macrophages (CD45, CD14), the small cells were negative for all these markers and after 30 cell doublings, these cells displayed the classical phenotype of MAPC (CD45−,CD105−, CD44−, CD73−, FLK-1+(vascular endothelial growth factor receptor 2, VEGFR2), Sca-1+,CD13+). In a second experiment, BM obtained one month post BM transplant (n=3) was harvested and mononuclear cells were sorted as GFP-positive and GFP-negative cells and were cultured in MAPC expansion medium. MAPC grew from the GFP-positive fraction. These GFP positive cells displayed the typical MAPC-like immunophenotypes, displayed a normal diploid karyotype and were expanded for more than 50 cell doublings and differentiated into endothelial cells, hepatocytes and neurons. To rule out the possibility that MAPC are the product of cell fusion between a host and a donor cell either in vivo or in our in vitro culture conditions, we performed sex mismatched transplants of female GFP donor BM cells into a male host. BM from 5 chimeras were harvested 4 weeks after transplant and MAPC cultures were established. MAPC colonies were then sorted as GFP-positive and GFP- negative and analyzed for the presence of Y-chromosome by FISH analysis. As expected all GFP-negative (host cells) contained the Y-chromosome whereas all GFP-positive cells (donor cells) were negative for the Y-chromosome by FISH. This proves that MAPC are not derived from an in vitro or in vivo fusion event. In a third study, BM mononuclear cells from mice that had been previously BM-transplanted with syngeneic GFP-positive donors (n=3) were transplanted into a second set of syngeneic recipients (n=9). Two months after the second transplant, BM was harvested and mononuclear cells were cultured in MAPC medium. The secondary recipients also contained GFP-positive MAPC. This is the first demonstration that BM transplantation leads to the transfer of cells that upon isolation in vitro generate MAPCs and, whatever the identity of this cell may be, is eliminated by irradiation. We believe this is an important observation as MAPC hold great clinical potential for stem cell and/or gene therapy and, thus, BM transplant may serve as a way to deliver and reconstitute the MAPC population. In addition, this study provides insight into the nature of MAPC. The capacity to be transplantable within unfractionated BM transplant renders a functional and physiological distinction between MAPC and BM stromal cells. This study validates the use of unfractionated BM transplants to study the nature and possible in vivo role of MAPC in the BM.

Circulating Endothelial Progenitor Cells Are Increased in Patients with Myelofibrosis and Do Not Harbor V617F JAK-2 or W515L MPL Mutations

Blood ◽  
2007 ◽  
Vol 110 (11) ◽  
pp. 1535-1535 ◽  
Author(s):  
Elisa Bonetti ◽  
Vittorio Rosti ◽  
Laura Villani ◽  
Rita Campanelli ◽  
Gaetano Bergamaschi ◽  
...  
Keyword(s):  
Endothelial Cells ◽  
Progenitor Cells ◽  
Endothelial Progenitor Cells ◽  
Healthy Subjects ◽  
Mononuclear Cells ◽  
Median Frequency ◽  
Endothelial Progenitor ◽  
Circulating Endothelial Progenitor Cells ◽  
Mutational Status

Abstract Bone marrow and spleen neoangiogenesis is a relevant feature of patients with myelofibrosis (MF). We have previously reported that patients with MF have an increased percentage of circulating endothelial progenitor cells (EPC) assessed as CD34+CD133+VEGFR2+ cells compared with patients with other Ph-negative myeloproliferative disorders (polycythemia vera, PV, and essential thrombocytemia, ET) and healthy subjects. However, neither the functional activity of these putative EPC nor their belonging to the malignant clone have been yet fully characterized. In order to address these issues we have grown in vitro EPC-derived colonies from the peripheral blood (PB) of 36 patients with MF, 9 patients with PV or ET and 10 healthy subjects. Seventeen MF patients harbored a V617F JAK-2 mutation (8 heterozygous and 9 homozygous) whereas 2 patients showed a W515L MPL mutation (both heterozygous). Eight out of 9 PV/ET patients had a V617F JAK-2 mutation (5 heterozygous and 3 homozygous). Mononuclear cells were cultured in collagen coated 6 well plates in the presence of EBM-2MV medium according to Ingram et al (Blood104:2752; 2004). The endothelial origin of the colonies was ascertained by assessment of the expression of CD105, CD146, CD144, CD31, vWf, VEGFR-2, CD14 and CD45 antigens. V617F JAK-2 and W515L MPL mutations were assessed by PCR, followed by enzymatic digestion, of endothelial cells after tripsinization of the EPC-derived colonies. The median frequency (number of colonies per 107 mononuclear cells plated) of EPC-derived colonies was statistically higher in MF patients (0.25, range 0–8.1) compared to healthy subjects (0.05, 0–0.3; P=0.037), but not different form that of PV/ET patients (0, 0–4.4; P=NS). Immunophenotyping confirmed that the cells expressed the endothelial antigens CD105, CD146, CD144, CD31, vWf, and VEGFR-2 but not the hematopoietic specific antigens CD45 and CD14. The capacity of colony-derived endothelial cells of MF patients to form capillary-like structures in the Matrigel assay was not different from that of healthy subjects. No correlation was found between the number of colonies and the mutational status of either JAK-2 or MPL. In 11 MF patients harboring either a JAK-2 (n=9) or a MPL (n=2) mutation, colony growth was observed and PCR was performed on EPC-derived colonies. In 0/9 and 0/2 cases neither JAK-2 nor MPL mutations were found, respectively. In addition, no V617F JAK-2 mutation was found in the EPC-derived colonies of 8 PV/ET patients who carried the mutation in their granulocytes. Taken together, our data show that patients with MF have an increased frequency of EPC in their PB compared to healthy subjects and that these mobilized EPC are not clonally-related to the JAK-2 or MPL mutated clone. Whether or not circulating EPC derive from an earlier progenitor cell compared to the one in which the JAK-2/MPL mutations arise remains to be determined.

β2-Glycoprotein I as a ‘Cofactor’ for anti-phospholipid reactivity with endothelial cells

Lupus ◽  
1998 ◽  
Vol 7 (2_suppl) ◽  
pp. 44-47 ◽  
Author(s):  
PL Meroni ◽  
N Del Papa ◽  
E Raschi ◽  
P Panzeri ◽  
MO Borghi ◽  
...  
Keyword(s):  
Endothelial Cells ◽  
Binding Site ◽  
Synthetic Peptide ◽  
Cell Activation ◽  
Heparan Sulphate ◽  
Membrane Structures ◽  
Glycoprotein I ◽  
Endothelial Growth Factor

β2-glycoprotein I (β2GPI) is a cofactor for anti-phospholipid (aPL) binding to cardiolipin (CL)-coated plates. β2GPI is also able to bind to endothelial cell (EC) membranes as supported by in-vivo as well as by in-vitro studies. The PL-binding site in the fifth domain of the molecule is involved in the adhesion to endothelium. Actually, specific mutations in this molecular portion abolish endothelium binding and a synthetic peptide spanning the sequence Glu274 –Cys288 of the CL-binding site displays comparable adhesion to EC monolayers. Heparan sulphate appears to be one of the anionic EC membrane structures with which cationic β2GPI interacts, as supported by studies with heparitinase-treated EC. β2GPI binding to EC might be related to its activity as endothelial growth factor or as a lipid-carrying glycoprotein. Adhesion of β2GPI to endothelial membranes offers suitable epitopes for circulating aPL that, once bound, can induce cell activation

scholarly journals Efficient Ex Vivo Expansion of Highly Purified Human Umbilical Cord Blood-Derived Very Small CD34+lin-CD45- Stem Cells into Functional Endothelial Cells in Vitro in Chemically Identified, Feeder Layer-Free Medium Supplemented with Nicotinamide

Blood ◽  
2019 ◽  
Vol 134 (Supplement_1) ◽  
pp. 4882-4882
Author(s):  
Alison Domingues ◽  
Kamila Bujko ◽  
Magdalena Kucia ◽  
Janina Ratajczak ◽  
Mariusz Z Ratajczak
Keyword(s):  
Stem Cells ◽  
Endothelial Cells ◽  
Cell Therapy ◽  
Progenitor Cells ◽  
Umbilical Cord Blood ◽  
Ex Vivo ◽  
Germ Layer ◽  
Differentiation Factors

Background . There is an ongoing search for multipotent stem cells from umbilical cord blood (UCB) with trans-germ layer differentiation potential that can be employed in repairing damaged organs and also expanded into transplantable hematopoietic stem cells (HSCs) and endothelial progenitor cells (EPCs). The existence of such cells in postnatal life could also revive the concept of hemangioblasts or hemangioblast-like cells in adult hematopoietic organs. Our group was the first to isolate a population of small CD34+CD133+lin-CD45- early-development stem cells from human hematopoietic tissues, including UCB. Based on the validated expression of early-development markers, these cells were named "very small embryonic-like stem cells" (VSELs, Circulation Res 2019; 124:208-210). Currently, more than 25 independent groups worldwide who have carefully followed the multicolor-staining cell-sorting strategy described by us (Current Protocols in Cytometry 2010, 9.29.1-9.29.15) have successfully isolated these cells and demonstrated their in vivo contribution to all three germ layer lineages. Thus, VSELs could be very useful in regenerative medicine in the field of angiogenesis, and UCB is an attractive source, with easy accessibility and tolerance to allogenic grafts. However, the low number of these cells in UCB and their quiescence are limiting factors. Therefore, in vitro differentiation of VSELs into endothelial progenitor cells (EPCs) would allow improvement in the ability to expand endothelial cells and could represent a clinically relevant alternative to embryonic stem cells (ESCs) and induced pluripotent stem cells (iPS) for cell therapy without ethical problems and undesirable side effects. Hypothesis. We hypothesized that UCB-purified, very small, early-developmentCD34+lin-CD45-stem cells can be ex vivo expanded into functional EPCs. Materials and Methods. VSELs highly purified by FACS were expanded into EPCs in pro-angiogenic medium supplemented with mesodermic differentiation factors and then endothelial differentiation factors in the presence of nicotinamide and UM171. In parallel, we expanded EPCs from MNCs isolated from the same UCB units by employing a classical protocol (Methods in Enzymology 2008, 445:303-29). The EPC nature of the expanded VSEL-derived cells was confirmed by the expression of typical EPC markers as well as by in vitro angiogenic assays. Results. Our differentiation cocktail allowed us to differentiate and expand VSELs into EPCs. In our expansion medium (Figure 1), the very small, round VSELs smaller than 6 mm in diameter proliferated and differentaited over time into larger and extended cells with a cobblestone morphology similar to the EPC control cells, and we confirmed their endothelial characteristics by cytometry analysis. Like EPCs, VSEL-derived EPCs were positive for CD31, CD144, KDR, and CD105 and negative for mesenchymal surface markers, such as CD90. They also performed similarly to EPCs in classical vasculogenic tests, including adhesion, proliferation, migration, and tubulogenesis assays. Conclusions. This work shows, for the first time, efficient VSEL differentiation into functional endothelial cells with vasculogenic properties without the help of co-culture over feeder-layers or viral vectors in medium supplemented with nicotinamide and UM171. These findings allow us to propose these cells as an interesting cell therapy product. These results also reopen the question of the existence of hemangioblast-like cells in postnatal tissues. We are currently testing these cells in vivo in model of hind limb ischemia. Figure 1 Disclosures No relevant conflicts of interest to declare.

scholarly journals RIPK1 Expression Associates with Inflammation in Early Atherosclerosis in Humans and Can be Therapeutically Silenced to Reduce NF-κB Activation and Atherogenesis in Mice

Circulation ◽  
2020 ◽  
Author(s):  
Denuja Karunakaran ◽  
My-Anh Nguyen ◽  
Michele Geoffrion ◽  
Dianne Vreeken ◽  
Zachary Lister ◽  
...  
Keyword(s):  
Endothelial Cells ◽  
Cell Activation ◽  
Inflammatory Responses ◽  
Early Stage ◽  
Oxidized Ldl ◽  
Loss Of Function ◽  
Aortic Sinus ◽  
Atherosclerotic Lesions

Background: Chronic activation of the innate immune system drives inflammation and contributes directly to atherosclerosis. Previously, we showed that macrophages in the atherogenic plaque undergo RIPK3-MLKL-dependent programmed necroptosis in response to sterile ligands such as oxidized LDL and damage-associated patterns (DAMPs) and necroptosis is active in advanced atherosclerotic plaques. Upstream of the RIPK3-MLKL necroptotic machinery lies RIPK1, which acts as a master switch that controls whether the cell undergoes NFκB-dependent inflammation, caspase-dependent apoptosis or necroptosis in response to extracellular stimuli. We therefore set out to investigate the role of RIPK1 in the development of atherosclerosis, which is largely driven by NFκB-dependent inflammation at early stages. We hypothesize that, unlike RIPK3 and MLKL, RIPK1 primarily drives NFκB-dependent inflammation in early atherogenic lesions and knocking down RIPK1 will reduce inflammatory cell activation and protect against the progression of atherosclerosis. Methods: We examined expression of RIPK1 protein and mRNA in both human and mouse atherosclerotic lesions, and using loss-of-function approaches in vitro in macrophages and endothelial cells to measure inflammatory responses. We administered weekly injections of RIPK1 anti-sense oligonucleotides (ASO) to Apoe -/- mice fed a cholesterol-rich (Western) diet for 8 weeks. Results: We find RIPK1 expression is abundant in early-stage atherosclerotic lesions in both humans and mice. Treatment with RIPK1 ASOs led to a reduction in aortic sinus and en face lesion areas (47.2% or 58.8% decrease relative to control, p<0.01) and plasma inflammatory cytokines (IL-1α, IL-17A, p<0.05) compared to controls. RIPK1 knockdown in macrophages decreased inflammatory genes (NFκB, TNFα, IL-1α) and in vivo LPS- and atherogenic diet-induced NF-κB activation. In endothelial cells, knockdown of RIPK1 prevented NF-κB translocation to the nucleus in response to TNFα, where accordingly there was a reduction in gene expression of IL1B, E-selectin and monocyte attachment. Conclusions: We have identified RIPK1 as a central driver of inflammation in atherosclerosis by its ability to activate the NF-κB pathway and promote inflammatory cytokine release. Given the high levels of RIPK1 expression in human atherosclerotic lesions, our study suggests RIPK1 as a future therapeutic target to reduce residual inflammation in patients at high risk of coronary artery disease.

Abstract 894: Leptin Potentiates the Angiogenic Properties of Endothelial Progenitor Cells In Vitro and In Vivo

Circulation ◽  
2007 ◽  
Vol 116 (suppl_16) ◽  
Author(s):  
Nana-Maria Heida ◽  
Marco R Schroeter ◽  
I-Fen Cheng ◽  
Elena I Deryugina ◽  
Thomas Korff ◽  
...  
Keyword(s):  
Endothelial Cells ◽  
Endothelial Cell ◽  
Progenitor Cells ◽  
Endothelial Progenitor Cells ◽  
Tube Length ◽  
Endothelial Progenitor ◽  
Signal Transduction Inhibitors ◽  
Stimulation Of

Endothelial progenitor cells (EPC) have been reported to contribute to neovascularization. We have previously shown that the adipocytokine leptin may enhance the adhesive properties of EPC by upregulating specific integrins. To investigate whether the angiogenic effects of leptin may be mediated by modulation of EPC function, mononuclear cells were isolated from healthy human volunteers and cultivated under endothelial cell conditions for 7 days. In the matrigel assay, pretreatment of EPC with recombinant leptin for 24 hours dose-dependently enhanced their incorporation into tubular structures provided by mature endothelial cells. For example, 138.3 ± 7.6% (P = 0.001) and 145.3 ± 5.5% (P = 0.0001) CM-DiI-labeled EPC were detected after stimulation with 10 and 100 ng/mL leptin, respectively (control-treated EPC defined as 100%). Furthermore, in the spheroid angiogenesis assay, stimulation of EPC with 10 ng/mL leptin increased the number of sprouts (P < 0.0001) and tube length (P < 0.0001) of coincubated mature endothelial cells, and the outgrowth of EPC (P < 0.0001). Addition of 100-fold excess of leptin-neutralizing or leptin-receptor-binding antibodies completely reversed these effects. Moreover, EPC adhesion onto endothelial cell tubules could be reduced by addition of RGD peptides (from 159 ± 13.7% to 101.8 ± 14.6%; P = 0.02), or of neutralizing antibodies against αvβ3 (from 165.3 ± 11.8% to 103.8 ± 13.3%; P = 0.006) or αvβ5 (to 93.5 ± 15.8%; P = 0.005). Further experiments using specific signal transduction inhibitors (10 μM of LY294002, PD98059, or SB203580), as well as Western blot analysis, revealed that leptin signaling in EPC involves phosphoinositide-3 kinase and p42/44, but not by p38 MAP kinase. The effects of leptin could also be confirmed under in vivo conditions. Stimulation of EPC with 100 ng/mL leptin potentiated the insprout of newly formed avian vessels into collagen onplants placed on the chorion allantoic membrane of chicken embryos (angiogenic index, 0.58 ± 0.24) compared to control-treated EPC (0.44 ± 0.27; P = 0.07) and endothelial basal medium alone (0.31 ± 0.26; P = 0.0007). Thus, our in vitro and in vivo results suggest that the angiogenic effects of leptin may partly depend on its specific interaction with endothelial progenitor cells.

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