scholarly journals Fibrin-VLDL Receptor-Dependent Pathway Promotes Leukocyte Transmigration by Inhibiting Src Kinase Fyn and is a Target for Fibrin β15-42 Peptide

2019 ◽  
Vol 119 (11) ◽  
pp. 1816-1826 ◽  
Author(s):  
Sergiy Yakovlev ◽  
Chunzhang Cao ◽  
Rebeca Galisteo ◽  
Li Zhang ◽  
Dudley K. Strickland ◽  
...  

AbstractAccording to the current view, binding of fibrin degradation product E1 fragment to endothelial VE-cadherin promotes transendothelial migration of leukocytes and thereby inflammation, and fibrin-derived β15–42 peptide reduces leukocyte transmigration by competing with E1 for binding to VE-cadherin and, in addition, by signaling through Src kinase Fyn. However, the very low affinity of β15–42 to VE-cadherin raised a question about its ability to inhibit E1–VE-cadherin interaction. Further, our previous study revealed that fibrin promotes leukocyte transmigration through the very-low-density lipoprotein (VLDL) receptor (VLDLR)-dependent pathway and suggested a possible link between the inhibitory properties of β15–42 and this pathway. To test such a link and the proposed inhibitory mechanisms for β15–42, we performed in vitro experiments using surface plasmon resonance, enzyme-linked immunosorbent assay, and leukocyte transendothelial migration assay, and in vivo studies with wild-type and VLDLR-deficient mice using mouse model of peritonitis. The experiments revealed that β15–42 cannot inhibit E1–VE-cadherin interaction at the concentrations used in the previous in vivo studies leaving the proposed Fyn-dependent signaling mechanism as a viable explanation for the inhibitory effect of β15–42. While testing this mechanism, we confirmed that Fyn plays a critical role in controlling fibrin-induced transendothelial migration of leukocytes and found that signaling through the VLDLR-dependent pathway results in inhibition of Fyn, thereby increasing leukocyte transmigration. Furthermore, our in vivo experiments revealed that β15–42 inhibits this pathway, thereby preventing inhibition of Fyn and reducing leukocyte transmigration. Thus, this study clarifies the molecular mechanism underlying the VLDLR-dependent pathway of leukocyte transmigration and reveals that this pathway is a target for β15–42.

Thorax ◽  
2021 ◽  
pp. thoraxjnl-2020-216469
Author(s):  
Alison W Ha ◽  
Tao Bai ◽  
David L Ebenezer ◽  
Tanvi Sethi ◽  
Tara Sudhadevi ◽  
...  

IntroductionNeonatal lung injury as a consequence of hyperoxia (HO) therapy and ventilator care contribute to the development of bronchopulmonary dysplasia (BPD). Increased expression and activity of lysyl oxidase (LOX), a key enzyme that cross-links collagen, was associated with increased sphingosine kinase 1 (SPHK1) in human BPD. We, therefore, examined closely the link between LOX and SPHK1 in BPD.MethodThe enzyme expression of SPHK1 and LOX were assessed in lung tissues of human BPD using immunohistochemistry and quantified (Halo). In vivo studies were based on Sphk1−/− and matched wild type (WT) neonatal mice exposed to HO while treated with PF543, an inhibitor of SPHK1. In vitro mechanistic studies used human lung microvascular endothelial cells (HLMVECs).ResultsBoth SPHK1 and LOX expressions were increased in lungs of patients with BPD. Tracheal aspirates from patients with BPD had increased LOX, correlating with sphingosine-1-phosphate (S1P) levels. HO-induced increase of LOX in lungs were attenuated in both Sphk1−/− and PF543-treated WT mice, accompanied by reduced collagen staining (sirius red). PF543 reduced LOX activity in both bronchoalveolar lavage fluid and supernatant of HLMVECs following HO. In silico analysis revealed STAT3 as a potential transcriptional regulator of LOX. In HLMVECs, following HO, ChIP assay confirmed increased STAT3 binding to LOX promoter. SPHK1 inhibition reduced phosphorylation of STAT3. Antibody to S1P and siRNA against SPNS2, S1P receptor 1 (S1P1) and STAT3 reduced LOX expression.ConclusionHO-induced SPHK1/S1P signalling axis plays a critical role in transcriptional regulation of LOX expression via SPNS2, S1P1 and STAT3 in lung endothelium.


2000 ◽  
Vol 148 (1) ◽  
pp. 203-216 ◽  
Author(s):  
Jennifer R. Allport ◽  
William A. Muller ◽  
Francis W. Luscinskas

The vascular endothelial cell cadherin complex (VE-cadherin, α-, β-, and γ-catenin, and p120/p100) localizes to adherens junctions surrounding vascular endothelial cells and may play a critical role in the transendothelial migration of circulating blood leukocytes. Previously, we have reported that neutrophil adhesion to human umbilical vein endothelial cell (HUVEC) monolayers, under static conditions, results in a dramatic loss of the VE-cadherin complex. Subsequent studies by us and others (Moll, T., E. Dejana, and D. Vestweber. 1998. J. Cell Biol. 140:403–407) suggested that this phenomenon might reflect degradation by neutrophil proteases released during specimen preparation. We postulated that some form of disruption of the VE-cadherin complex might, nonetheless, be a physiological process during leukocyte transmigration. In the present study, the findings demonstrate a specific, localized effect of migrating leukocytes on the VE-cadherin complex in cytokine-activated HUVEC monolayers. Monocytes and in vitro differentiated U937 cells induce focal loss in the staining of VE-cadherin, α-catenin, β-catenin, and plakoglobin during transendothelial migration under physiological flow conditions. These events are inhibited by antibodies that prevent transendothelial migration and are reversed following transmigration. Together, these data suggest that an endothelial-dependent step of transient and focal disruption of the VE-cadherin complex occurs during leukocyte transmigration.


Antioxidants ◽  
2021 ◽  
Vol 11 (1) ◽  
pp. 62
Author(s):  
Daniela Valenti ◽  
Fiorenza Stagni ◽  
Marco Emili ◽  
Sandra Guidi ◽  
Renata Bartesaghi ◽  
...  

Down syndrome (DS), a major genetic cause of intellectual disability, is characterized by numerous neurodevelopmental defects. Previous in vitro studies highlighted a relationship between bioenergetic dysfunction and reduced neurogenesis in progenitor cells from the Ts65Dn mouse model of DS, suggesting a critical role of mitochondrial dysfunction in neurodevelopmental alterations in DS. Recent in vivo studies in Ts65Dn mice showed that neonatal supplementation (Days P3–P15) with the polyphenol 7,8-dihydroxyflavone (7,8-DHF) fully restored hippocampal neurogenesis. The current study was aimed to establish whether brain mitochondrial bioenergetic defects are already present in Ts65Dn pups and whether early treatment with 7,8-DHF positively impacts on mitochondrial function. In the brain and cerebellum of P3 and P15 Ts65Dn pups we found a strong impairment in the oxidative phosphorylation apparatus, resulting in a deficit in mitochondrial ATP production and ATP content. Administration of 7,8-DHF (dose: 5 mg/kg/day) during Days P3–P15 fully restored bioenergetic dysfunction in Ts65Dn mice, reduced the levels of oxygen radicals and reinstated the hippocampal levels of PGC-1α. No pharmacotherapy is available for DS. From current findings, 7,8-DHF emerges as a treatment with a good translational potential for improving mitochondrial bioenergetics and, thus, mitochondria-linked neurodevelopmental alterations in DS.


Blood ◽  
2004 ◽  
Vol 104 (11) ◽  
pp. 2624-2624
Author(s):  
Joaquin J. Jimenez ◽  
Wenche Jy ◽  
Lucia M. Mauro ◽  
Michael N. Markou ◽  
George W. Burke ◽  
...  

Abstract Injured endothelial cells (EC) are believed to play a critical role in the pathophysiology of TTP. Soluble markers of endothelial disturbance measured by enzyme-linked immunoassay (ELISA) have been found elevated in TTP. We have recently demonstrated an increase in the release of CD31/42b- EMP, and CD62E+ EMP. Moreover, we have observed that CD62E+ EMP also express vWF. The aim of this study was to quantitate soluble (s) vs. EMP-bound CD62E (bCD62E) in vitro and in vivo, in relation to the functional activity of vWF+ EMP. METHODS: Brain and renal microvascular endothelial cells (MVEC) were cultured and treated with 10ng/mL TNF-α to induce activation, or deprived of serum and growth factors (GFD) to induce apoptosis. Culture supernatants were collected and evaluated in a time-dependent manner. For in vivo studies, platelet-poor plasma was obtained from 4 TTP patients during the acute phase and upon remission. Filtration through 0.1μm, which retains most EMP, was employed to discriminate between (s) and bCD62E. sCD62E was measured by ELISA post-filtration and bCD62E by ELISA pre-filtration. Additionally, CD62E+ and CD62E+/vWF+ EMP were measured by flow cytometry. To assess pro-aggregatory function, EMP were added to washed platelets in the presence of 1 mg/mL ristocetin and aggregates were measured by flow cytometry. RESULTS: In vitro: Activation did not induce release of sCD62E at 3 hours, although bCD62E was present (1.5±0.5X106 EMP/mL). At 6 hours, some sCD62E was detected in the filtrate (0.09±0.02 ng/mL), but most was present in the unfiltered medium (3.5±0.85 ng/mL), signifying that the majority was bCD62E, confirmed by a doubling of CD62E+ EMP (3.0±0.6X106/mL). Subsequently, sCD62E levels were 1.0±0.2 ng/mL at 12 hr, 3.5±0.7 ng/mL at 18 hr, and 5±0.9 ng/mL at 24 hr. In contrast, EMP counts at 12, 18 and 24 hours were 4.6±1, 7±1.3 and 9±1.8 X106/mL (p=0.01, p=0.01, p=0.02, respectively). For all time periods, 40-60% of CD62E were positive for vWF. In control or GFD cultures, there was not a significant increase in sCD62E or CD62E+ EMP at any time period. MVEC from renal gave similar results. In acute TTP plasma samples, CD62E measured by ELISA was significantly increased (65±22 ng/mL) vs. remission (30±6 ng/mL). bCD62E accounted for 50% in acute and 15% in remission. CD62E+/vWF+ EMP were significantly elevated in plasma from acute TTP patients vs. remission (15±4.5 vs. 3±0.5, p=0.01). Sample filtration resulted in a decrease of >95% EMP in both acute and remission TTP plasma. MVEC-derived CD62E+/vWF+ EMP resulted in a dose-dependent increase in platelet aggregation. Additionally, plasma from 4 TTP patients with elevated CD62E+/vWF+ EMP obtained during the acute phase enhanced the formation of platelet aggregates by 48±12% (p=0.02) above remission plasma with low EMP counts. CONCLUSIONS: The results demonstrate that CD62E heretofore regarded as a soluble marker of endothelial dysfunction, in reality exists in both a soluble and EMP-bound form. Indeed, this distinction is highly relevant because CD62E+ EMP also express vWF and are pro-aggregatory to platelets. These EMP have been shown to be elevated during the acute phase of TTP and decrease upon remission. Thus, CD62E+/vWF+ EMP may be active participants in the formation of platelet-rich thrombi in TTP.


Blood ◽  
2009 ◽  
Vol 114 (22) ◽  
pp. SCI-20-SCI-20
Author(s):  
Rodney M. Camire ◽  
Matthew Bunce ◽  
Lacramioara Ivanciu ◽  
Raffaella Toso ◽  
Harre D. Downey ◽  
...  

Abstract Abstract SCI-20 Blood coagulation factors VIII and IX are part of the intrinsic pathway and play a critical role in maintaining normal hemostasis by activating factor X. Deficiency of either of these proteins caused by mutations in the genes encoding FVIII or FIX leads to hemophilia A or B (HA and HB), respectively. In each disease, there is impairment of the intrinsic pathway with inadequate thrombin (IIa) generation and defective hemostasis. Unfortunately, ∼20-30% of patients with FVIII deficiency and ∼3-5% of patients with FIX deficiency develop inhibitory antibodies to infused factor replacement products. This has prompted the research community to develop so-called “bypass strategies” which use other coagulation factors to provide hemostasis in these patients. In principle, infusion of FXa should bypass deficiencies in the intrinsic pathway; however it is generally thought that it has limited utility since the infused FXa could cause excessive activation of coagulation and/or more importantly, FXa is rapidly inactivated by plasma inhibitors resulting in a very short half-life (<2 min). We recently characterized variants of FXa (FXa-I16L and FXa-V17a) which have “zymogen-like” properties that could circumvent these associated problems (JBC 2008; 283: 18627). For example we have found that i) these proteins have an incompletely formed active site, making them resistant to plasma protease inhibitors; ii) in the absence of FVa, the FXa variants are, in general, refractory to active site functions and thus do not activate FVII, FV, FVIII, and prothrombin very well; and iii) the variants are thermodynamically rescued by FVa; thus at the site of injury on the activated platelet surface, where FVa is present, prothrombinase rapidly forms generating a burst of thrombin. We have begun to exploit these unique properties and evaluate whether these FXa variants could be effective and safe in bypassing the hemophilic phenotype both in vitro and in vivo. Clotting and IIa generation assays in human HA, HB and inhibitor plasma revealed that FXa-I16L could completely restore IIa generation in a FVa-dependent fashion. Furthermore, the zymogen-like conformation protects FXa-I16L in human plasma as it has a prolonged half-life (∼2 hr) versus wt-FXa (<2 min). In vivo studies using HB mice revealed that administration of FXa-I16L via tail vein almost completely corrected the prolonged aPTT. The aPTT was shortened for more than 2 hours and returned close to the starting value after 24 hr. In these experiments, infusion of the protein was well tolerated as platelet levels were unaffected over the course of the experiment with little or no change in the values for TAT, D-dimer, and fibrinogen. Next we tested whether the improvement of the clotting times was associated with in vivo hemostatic performance. Using three separate injury models (tail clip assay, FeCl2 carotid artery injury model, and cremaster muscle laser injury model) infusion FXa-I16L provided effective hemostasis. This was in contrast to the infusion of wild-type FXa which was ineffective. Taken together our data show that FXa-I16L is highly effective in correcting the hemostatic defect in human hemophilic plasma. Furthermore it improves the hemophilic phenotype in HB mice following a series of hemostatic challenges and can restore thrombus formation upon injury at both micro and macrocirculation levels. Thus zymogen-like variants of FXa have properties that indicate their ability to serve as superior therapeutic procoagulants for bypassing deficiencies upstream of the common pathway. Disclosures Camire: Wyeth: Patents & Royalties, Research Funding. Bunce:Wyeth: Research Funding. Ivanciu:Wyeth: Research Funding. Downey:Wyeth: Research Funding.


2005 ◽  
Vol 12 (12) ◽  
pp. 1437-1441 ◽  
Author(s):  
R. Sghiri ◽  
J. Feinberg ◽  
F. Thabet ◽  
K. Dellagi ◽  
J. Boukadida ◽  
...  

ABSTRACT Previous studies have indicated that neopterin is synthesized in vitro by human monocyte-derived macrophages and dendritic cells upon stimulation with gamma interferon (IFN-γ). Neopterin production under specific conditions in vitro has also been obtained upon stimulation with IFN-α and/or IFN-β. However, it is unknown if any IFN-γ-independent neopterin synthesis is possible in vivo. In the present study we investigated the serum neopterin concentrations in patients affected by the syndrome of Mendelian susceptibility to mycobacterial disease (MSMD). Indeed, this syndrome is characterized by deeply impaired or absent IFN-γ production or function due to severe mutations in molecules involved in IFN-γ/interleukin-12 (IL-12)/IL-23-dependent pathway. Serum neopterin levels were measured by an enzyme-linked immunosorbent assay in 27 patients with MSMD. We found that serum neopterin levels are elevated in the complete absence of IFN-γ activity due either to a complete deficiency of its receptor or to deleterious mutations of IL-12 or its receptor. These data clearly indicate that, as reported from in vitro studies, other stimuli are able to induce neopterin synthesis in vivo. Consequently, neopterin cannot be used as means of diagnosis of MSMD due to IFN-γ-, IL-12-, and IL-23-dependent pathway defects.


Blood ◽  
2003 ◽  
Vol 102 (4) ◽  
pp. 1389-1396 ◽  
Author(s):  
Helmut Rainer Salih ◽  
Holger Antropius ◽  
Friederike Gieseke ◽  
Stefan Zoltan Lutz ◽  
Lothar Kanz ◽  
...  

Abstract NKG2D ligands (NKG2DLs) mark malignant cells for recognition by natural killer (NK) cells and cytotoxic T lymphocytes via the activating immunoreceptor NKG2D. This led to the hypothesis that NKG2DLs play a critical role in tumor immune surveillance. The human NKG2DLs MICA and MICB are expressed on tumors of epithelial origin in vivo. For the other recently described set of human NKG2DLs, the UL16-binding proteins (ULBPs), expression in vivo is as yet undefined. In this study we investigated expression and function of NKG2DLs in leukemia using a panel of newly generated NKG2DL-specific monoclonal antibodies. We report that leukemia cells from patients variously express MIC and ULBP molecules on the cell surface with MICA most frequently detected. Patient leukemia cells expressing MICA were lysed by NK cells in an NKG2D-dependent fashion. Sera of patients, but not of healthy donors, contained elevated levels of soluble MICA (sMICA). We also detected increased sMICB levels in patient sera using a newly established MICB-specific enzyme-linked immunosorbent assay. Reduction of leukemia MIC surface expression by shedding may impair NKG2D-mediated immune surveillance of leukemias. In addition, determination of sMICA and sMICB levels may be implemented as a prognostic parameter in patients with hematopoietic malignancies.


2021 ◽  
Vol 12 ◽  
Author(s):  
Jia Li ◽  
Md Ashik Ullah ◽  
Hongping Jin ◽  
Yuting Liang ◽  
Lihui Lin ◽  
...  

Antigen (Ag)-mediated mast cell activation plays a critical role in the immunopathology of IgE-dependent allergic diseases. Restraining the signaling cascade that regulates the release of mast cell-derived inflammatory mediators is an attractive therapeutic strategy to treat allergic diseases. Orosomucoid-like-3 (ORMDL3) regulates the endoplasmic reticulum stress (ERS)-induced unfolded protein response (UPR) and autophagy. Although ERS/UPR/autophagy pathway is crucial in Ag-induced mast cell activation, it is unknown whether ORMDL3 regulates the ERS/UPR/autophagy pathway during mast cell activation. In this study, we found that ORMDL3 expression was downregulated in Ag-activated MC/9 cells. Overexpression of ORMDL3 significantly inhibited degranulation, and cytokine/chemokine production, while the opposite effect was observed with ORMDL3 knockdown in MC/9 cells. Importantly, ORMDL3 overexpression upregulated mediators of ERS-UPR (SERCA2b, ATF6) and autophagy (Beclin 1 and LC3BII). Knockdown of ATF6 and/or inhibition of autophagy reversed the decreased degranulation and cytokine/chemokine expression caused by ORMDL3 overexpression. Moreover, in vivo knockdown of ORMDL3 and/or ATF6 enhanced passive cutaneous anaphylaxis (PCA) reactions in mouse ears. These data indicate that ORMDL3 suppresses Ag-mediated mast cell activation via an ATF6 UPR-autophagy dependent pathway and thus, attenuates anaphylactic reaction. This highlights a potential mechanism to intervene in mast cell mediated diseases.


Author(s):  
OLUWASEUN TAOFEEK

The novel severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) responsible for the 2019 coronavirus disease (COVID-19) has caused a global health challenge. The SARS-COV-2 main protease, 3CLpro/Mpro plays a critical role in the viral gene expression and replication and has been a major target for inhibiting viral maturation and enhancing host innate immune responses against COVID-19. In this study, we screened a library of 38 phytochemicals from Nigella sativa (blackseed), Trigonella foenum-graecum (Fenugreek) and Anona muricata (Soursop) potent medicinal plants with reported antiviral properties - in a molecular docking protocol on 3CLpro using Autodock4.0 tool implanted in PyRx followed by docking validation and insilico absorption, distribution, metabolism, excretion, and toxicology (ADMET) evaluations. The docking results were visualized using Accelrys Discovery Studio and Pymol software. Among the 38 ligands screened, 19 showed significant interaction through non-covalent hydrogen bonding, hydrophobic, and electrostatic interactions with binding affinities from -5.3kcal/mol to -8.1kcal/mol indicating significant binding interactions at the active site binding pocket. Another important interaction observed in the study which mostly involve the transfer of charges was pi-interactions such as Pi-Pi interaction, Pi-Alkyl interaction, Pi-Sulfur interaction, Pi- Sigma, and Pi-Pi stacking. The docking results revealed that phytochemicals from T. foenum-graecum showed more 3CLpro inhibitory potential compared to those from N. sativa and A. muricata. Insilico ADMET evaluations for drug-like and lead-like characteristics however demonstrated that only 8 ligands - apigenin, kaempferol, luteolin, dithymoquinone, naringenine, nornuciferine, quercetin and nigellidine were actually drug-like; showed best activities against 3CLpro, and lack hepatotoxicity effects while none was lead-like. Insilico results of this study further suggested that drug repurposing candidates, remdesivir, indinavir,hydroxychloroquine, chloroquine and ritonavir,exhibited various interactions with 3CLpro. Hence, further in vitro and in vivo studies are proposed.


Author(s):  
Elize Wolmarans ◽  
Thandi Mqoco ◽  
Andre Stander ◽  
Sandra Nkandeu ◽  
Katherine Sippel ◽  
...  

AbstractCancer is the second leading cause of death in South Africa. The critical role that microtubules play in cell division makes them an ideal target for the development of chemotherapeutic drugs that prevent the hyperproliferation of cancer cells. The new in silico-designed estradiol analogue 2-ethyl-3-O-sulfamoylestra-1,3,5(10)16-tetraene (ESE-16) was investigated in terms of its in vitro antiproliferative effects on the esophageal carcinoma SNO cell line at a concentration of 0.18 μM and an exposure time of 24 h. Polarization-optical differential interference contrast and triple fluorescent staining (propidium iodide, Hoechst 33342 and acridine orange) revealed a decrease in cell density, metaphase arrest, and the occurrence of apoptotic bodies in the ESE-16-treated cells when compared to relevant controls. Treated cells also showed an increase in the presence of acidic vacuoles and lysosomes, suggesting the occurrence of autophagic processes. Cell death via autophagy was confirmed using the Cyto-ID autophagy detection kit and the aggresome detection assay. Results showed an increase in autophagic vacuole and aggresome formation in ESE-16 treated cells, confirming the induction of cell death via autophagy. Cell cycle progression demonstrated an increase in the sub-G1 fraction (indicative of the presence of apoptosis). In addition, a reduction in mitochondrial membrane potential was also observed, which suggests the involvement of apoptotic cell death induced by ESE-16 via the intrinsic apoptotic pathway. In this study, it was demonstrated that ESE-16 induces cell death via both autophagy and apoptosis in esophageal carcinoma cells. This study paves the way for future investigation into the role of ESE-16 in ex vivo and in vivo studies as a possible anticancer agent.


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