scholarly journals The alpha 4-integrin supports leukocyte rolling and adhesion in chronically inflamed postcapillary venules in vivo.

1996 ◽  
Vol 183 (5) ◽  
pp. 1995-2006 ◽  
Author(s):  
B Johnston ◽  
T B Issekutz ◽  
P Kubes
Keyword(s):  
Polymorphonuclear Leukocytes ◽  
Mononuclear Cells ◽  
Leukocyte Adhesion ◽  
Systemic Vasculitis ◽  
Significant Proportion ◽  
Leukocyte Rolling ◽  
Peripheral Blood Mononuclear ◽  
Beta 2 ◽  
Adhesive Interactions

A role for the alpha 4-integrin (alpha 4 beta 1 or alpha 4 beta 7), has been implicated in the recruitment of peripheral blood mononuclear cells (PBMCs) to sites of inflammation. However, the adhesive interactions (i.e., tethering, rolling, and adhesion) mediated by the alpha 4-integrin have not been characterized in vivo. The objective of this study was to establish a model wherein postcapillary venules were chronically inflamed, and then use intravital microscopy to identify the adhesive interactions mediated by the alpha 4-integrin in vivo. Between 4 and 20 d after immunization with Mycobacterium butyricum, animals developed a systemic vasculitis characterized by large increases in the numbers of rolling and adhering leukocytes within mesenteric venules. The selectins could only account for approximately 50% of the leukocyte rolling whereas the remaining cells rolled exclusively via the alpha 4-integrin. Anti-alpha 4 therapy also eliminated the increase in leukocyte adhesion observed in this model, whereas selectin therapies and an anti-CD18 (beta 2-integrin) monoclonal antibody (mAb) did not reduce adhesion. A serum against polymorphonuclear leukocytes (PMNs) was used to confirm that a significant proportion of rolling cells, and most of the adhering cells were PBMCs. Sequential treatment with anti-PMN serum and the anti-alpha 4 mAb demonstrated that alpha 4-dependent rolling was distinct from PMN rolling populations. Initial leukocyte tethering via the alpha 4-integrin could not be demonstrated in this model, whereas L-selectin did support leukocyte tethering. These data suggest that the alpha 4-integrin can mediate both rolling and adhesion in the multistep recruitment of PMBCs in vivo, and these interactions occur independently of the selectins and beta 2-integrins.

scholarly journals Human Leukocytes KillAspergillus nidulansby Reactive Oxygen Species-Independent Mechanisms

2010 ◽  
Vol 79 (2) ◽  
pp. 767-773 ◽  
Author(s):  
Stefanie S. V. Henriet ◽  
Peter W. M. Hermans ◽  
Paul E. Verweij ◽  
Elles Simonetti ◽  
Steven M. Holland ◽  
...  
Keyword(s):  
Reactive Oxygen Species ◽  
Nadph Oxidase ◽  
Polymorphonuclear Leukocytes ◽  
Mononuclear Cells ◽  
Reactive Oxygen ◽  
Healthy Controls ◽  
Oxygen Species ◽  
Peripheral Blood Mononuclear ◽  
Antifungal Effects

ABSTRACTInvasive aspergillosis is a major threat for patients suffering from chronic granulomatous disease (CGD). AlthoughAspergillus fumigatusis the most commonly encounteredAspergillusspecies, the presence ofA. nidulansappears to be disproportionately high in CGD patients. The purpose of this study was to investigate the involvement of the NADPH oxidase and the resulting reactive oxygen species (ROS) in host defense against fungi and to clarify their relationship towardA. nidulans. Murine CGD alveolar macrophages (AM) and polymorphonuclear leukocytes (PMN) and peripheral blood mononuclear cells (PBMC) from healthy controls and CGD patients were challenged with eitherA. fumigatusorA. nidulans. Analysis of the antifungal effects of ROS revealed thatA. nidulans, in contrast toA. fumigatus, is not susceptible to ROS. In addition, infection with liveA. nidulansdid not result in any measurable ROS release. Remarkably, human CGD PMN and PBMC and murine CGD AM were at least equipotent at arresting conidial germination compared to healthy controls. Blocking of the NADPH oxidase resulted in significantly reduced damage ofA. fumigatusbut did not affectA. nidulanshyphae. Furthermore, the microbicidal activity of CGD PMN was maintained towardA. nidulansbut notA. fumigatus. In summary, antifungal resistance toA. nidulansis not directly ROS related. The etiology ofA. nidulansinfections in CGD cannot be explained by the simple absence of the direct microbicidal effect of ROS.In vivo, the NADPH oxidase is a critical regulator of innate immunity whose unraveling will improve our understanding of fungal pathogenesis in CGD.

scholarly journals The Liver Is a Major Organ for Clearing Simian Immunodeficiency Virus in Rhesus Monkeys

2002 ◽  
Vol 76 (10) ◽  
pp. 5271-5273 ◽  
Author(s):  
Linqi Zhang ◽  
Peter J. Dailey ◽  
Agegnehu Gettie ◽  
Jim Blanchard ◽  
David D. Ho
Keyword(s):  
Simian Immunodeficiency Virus ◽  
Viral Vectors ◽  
Mononuclear Cells ◽  
Significant Proportion ◽  
Viral Clearance ◽  
High Rate ◽  
Peripheral Blood Mononuclear ◽  
Immunodeficiency Virus ◽  
Rapid Clearance

ABSTRACT Infection with human or simian immunodeficiency virus (SIV) is characterized by the rapid turnover of both viral particles and productively infected cells. It has recently been reported that the clearance of SIV in vivo is exceedingly fast, with half-lives on the order of minutes. The underlying mechanism or site responsible for this rapid clearance, however, remains unknown. To investigate this issue, we chose to infuse infectious SIVmac239 grown from autologous peripheral blood mononuclear cells that were radioactively labeled by [35S]methionine and [35S]cysteine. This approach eliminates from the viral membrane alloantigens that may have a significant impact on viral clearance. In addition, this approach also permits identification of the sites of viral clearance by measuring the radioactive intensity, even if degradation of SIV RNA occurs in tissues. We now report that the half-life of infused SIV in blood is extremely close to estimates from a previous study, in which unlabeled SIV grown in a heterologous cell line was used. The allogeneic effect due to the presence of human antigens on the surfaces of virions may, therefore, play a minimal role in the high rate of virion clearance. Moreover, close to 30% of infused radioactivity was found in the liver and measureable amounts were detected in the lungs (5.4%), lymph nodes (3.0%), and spleen (0.4%). The detection of a significant proportion of infused virus in the liver suggests that viral clearance from circulation is mediated by a common, nonspecific mechanism, such as the phagocytic functions of the reticuloendothelial system. The rapid clearance and degradation of exogenously infused virions may pose a major obstacle for gene therapy with viral vectors, unless strategies to overcome the rapid in vivo elimination of these particles are developed.

Immunoblockade of PSGL-1 attenuates established experimental murine colitis by reduction of leukocyte rolling

2004 ◽  
Vol 287 (1) ◽  
pp. G115-G124 ◽  
Author(s):  
Emile M. Rijcken ◽  
Mike G. Laukoetter ◽  
Christoph Anthoni ◽  
Stephanie Meier ◽  
Rudolf Mennigen ◽  
...  
Keyword(s):  
Intestinal Inflammation ◽  
Activity Index ◽  
Leukocyte Adhesion ◽  
Combined Treatment ◽  
Disease Activity Index ◽  
Leukocyte Recruitment ◽  
Leukocyte Rolling ◽  
Chronic Colitis ◽  
Adhesive Interactions

Recruitment of circulating leukocytes into the colonic tissue is a key feature of intestinal inflammation. P-selectin glycoprotein ligand-1 (PSGL-1) and very late antigen-4 (VLA-4) are expressed on leukocytes and play an important role in leukocyte-endothelial cell adhesive interactions. We examined the effects of immunoneutralization of PSGL-1 and VLA-4 on leukocyte recruitment in vivo in the development and treatment of experimental colitis. Chronic colitis was induced in balb/c mice by oral administration of dextran sodium sulfate (DSS). Monoclonal antibodies 2PH1 (anti-PSGL-1) and PS/2 (anti-VLA-4) or the combination of both were injected intravenously, and leukocyte adhesion was observed for 60 min in colonic submucosal venules by intravital microscopy (IVM) under isoflurane/N2O anesthesia. In addition, mice with established colitis were treated by daily intraperitoneal injections of 2PH1, PS/2, or the combination of both over 5 days. Disease activity index (DAI), histology, and myeloperoxidase (MPO) levels were compared with sham-treated DSS controls. We found that 2PH1 reduced the number of rolling leukocytes (148.7 ± 29.8 vs. 36.9 ± 8.7/0.01 mm2/30 s, P < 0.05), whereas leukocyte velocity was increased (24.0 ± 3.6 vs. 127.8 ± 11.7 μm/s, P < 0.05). PS/2 reduced leukocyte rolling to a lesser extent. Leukocyte firm adhesion was not influenced by 2PH1 but was strongly reduced by PS/2 (24.1 ± 2 vs. 4.4 ± 0.9/0.01 mm2/30 s, P < 0.05). Combined application did not cause additional effects on leukocyte adhesion. Treatment of chronic colitis with 2PH1 or PS/2 reduced DAI, mucosal injury, and MPO levels significantly. Combined treatment led to a significantly better reduction of DAI (0.4 ± 0.1 vs. 2.1 ± 0.2 points) and histology (9.7 ± 0.9 vs. 21.4 ± 4.6 points). In conclusion, PSGL-1 and VLA-4 play an important role for leukocyte recruitment during intestinal inflammation. Therapeutic strategies designed to disrupt interactions mediated by PSGL-1 and/or VLA-4 may prove beneficial in treatment of chronic colitis.

scholarly journals Positive allosteric modulation of indoleamine 2,3-dioxygenase 1 restrains neuroinflammation

2020 ◽  
Vol 117 (7) ◽  
pp. 3848-3857 ◽  
Author(s):  
Giada Mondanelli ◽  
Alice Coletti ◽  
Francesco Antonio Greco ◽  
Maria Teresa Pallotta ◽  
Ciriana Orabona ◽  
...  
Keyword(s):  
Mode Of Action ◽  
Mononuclear Cells ◽  
Significant Proportion ◽  
Kynurenine Pathway ◽  
Neuroprotective Effects ◽  
Peripheral Blood Mononuclear ◽  
Indoleamine 2,3 Dioxygenase ◽  
Aryl Hydrocarbon

l-tryptophan (Trp), an essential amino acid for mammals, is the precursor of a wide array of immunomodulatory metabolites produced by the kynurenine and serotonin pathways. The kynurenine pathway is a paramount source of several immunoregulatory metabolites, including l-kynurenine (Kyn), the main product of indoleamine 2,3-dioxygenase 1 (IDO1) that catalyzes the rate-limiting step of the pathway. In the serotonin pathway, the metabolite N-acetylserotonin (NAS) has been shown to possess antioxidant, antiinflammatory, and neuroprotective properties in experimental autoimmune encephalomyelitis (EAE), an animal model of multiple sclerosis (MS). However, little is known about the exact mode of action of the serotonin metabolite and the possible interplay between the 2 Trp metabolic pathways. Prompted by the discovery that NAS neuroprotective effects in EAE are abrogated in mice lacking IDO1 expression, we investigated the NAS mode of action in neuroinflammation. We found that NAS directly binds IDO1 and acts as a positive allosteric modulator (PAM) of the IDO1 enzyme in vitro and in vivo. As a result, increased Kyn will activate the ligand-activated transcription factor aryl hydrocarbon receptor and, consequently, antiinflammatory and immunoregulatory effects. Because NAS also increased IDO1 activity in peripheral blood mononuclear cells of a significant proportion of MS patients, our data may set the basis for the development of IDO1 PAMs as first-in-class drugs in autoimmune/neuroinflammatory diseases.

scholarly journals Sickle red cells induce adhesion of lymphocytes and monocytes to endothelium

Blood ◽  
2008 ◽  
Vol 112 (8) ◽  
pp. 3474-3483 ◽  
Author(s):  
Rahima Zennadi ◽  
Ai Chien ◽  
Ke Xu ◽  
Milena Batchvarova ◽  
Marilyn J. Telen
Keyword(s):  
Molecular Mechanisms ◽  
Mononuclear Cells ◽  
Leukocyte Adhesion ◽  
Human Peripheral Blood ◽  
Cell Disease ◽  
Peripheral Blood Mononuclear ◽  
Sickle Erythrocytes ◽  
Β2 Integrins

Abstract Infusion of epinephrine-activated human sickle erythrocytes (SS RBCs) into nude mice promotes both SS RBC and murine leukocyte adhesion to vascular endothelium in vivo. We hypothesized that interaction of epinephrine-stimulated SS RBCs with leukocytes leads to activation of leukocytes, which then adhere to endothelial cells (ECs). In exploring the underlying molecular mechanisms, we have found that coincubation in vitro of epinephrine-treated SS RBCs with human peripheral blood mononuclear cells (PBMCs) results in robust adhesion of PBMCs to ECs. Sham-treated SS RBCs had a similar but less pronounced effect, whereas neither sham- nor epinephrine-treated normal RBCs activated PBMC adhesion. PBMC activation was induced via at least 2 RBC adhesion receptors, LW and CD44. In response to SS RBCs, leukocyte CD44 and β2 integrins mediated PBMC adhesion to ECs, a process that involved endothelial E-selectin and fibronectin. SS RBCs activated adhesion of both PBMC populations, lymphocytes and monocytes. Thus, our findings reveal a novel mechanism that may contribute to the pathogenesis of vaso-occlusion in sickle cell disease, in which SS RBCs act via LW and CD44 to stimulate leukocyte adhesion to endothelium, and suggest that RBC LW and CD44 may serve as potential targets for antiadhesive therapy designed to prevent vaso-occlusion.

Preliminary Report of In vitro and In vivo Effectiveness of Dornase Alfa on SARS-CoV-2 Infection (Preprint)

2020 ◽  
Author(s):  
Hacer Kuzu Okur ◽  
Koray Yalcin ◽  
Cihan Tastan ◽  
Sevda Demir ◽  
Bulut Yurtsever ◽  
...  
Keyword(s):  
Cystic Fibrosis ◽  
Respiratory Tract ◽  
Mononuclear Cells ◽  
Multiple Organ ◽  
Peripheral Blood Mononuclear ◽  
Dornase Alfa ◽  
Tract Infections ◽  
Adult Peripheral Blood

UNSTRUCTURED Dornase alfa, the recombinant form of the human DNase I enzyme, breaks down neutrophil extracellular traps (NET) that include a vast amount of DNA fragments, histones, microbicidal proteins and oxidant enzymes released from necrotic neutrophils in the highly viscous mucus of cystic fibrosis patients. Dornase alfa has been used for decades in patients with cystic fibrosis to reduce the viscoelasticity of respiratory tract secretions, to decrease the severity of respiratory tract infections, and to improve lung function. Previous studies have linked abnormal NET formations to lung diseases, especially to acute respiratory distress syndrome (ARDS). Coronavirus disease 2019 (COVID-19) pandemic affected more than two million people over the world, resulting in unprecedented health, social and economic crises. The COVID-19, viral pneumonia that progresses to ARDS and even multiple organ failure, is caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). High blood neutrophil levels are an early indicator of SARS-CoV-2 infection and predict severe respiratory diseases. A similar mucus structure is detected in COVID-19 patients due to the accumulation of excessive NET in the lungs. Here, we show our preliminary results with dornase alfa that may have an in-vitro anti-viral effect against SARS-CoV-2 infection in a bovine kidney cell line, MDBK without drug toxicity on healthy adult peripheral blood mononuclear cells. In this preliminary study, we also showed that dornase alfa can promote clearance of NET formation in both an in-vitro and three COVID-19 cases who showed clinical improvement in radiological analysis (2-of-3 cases), oxygen saturation (SpO2), respiratory rate, disappearing of dyspnea and coughing.

scholarly journals A non-human primate in vitro functional assay for the early evaluation of TB vaccine candidates

npj Vaccines ◽  
2021 ◽  
Vol 6 (1) ◽  
Author(s):  
Rachel Tanner ◽  
Andrew D. White ◽  
Charelle Boot ◽  
Claudia C. Sombroek ◽  
Matthew K. O’Shea ◽  
...  
Keyword(s):  
Growth Inhibition ◽  
Mononuclear Cells ◽  
Functional Assay ◽  
Intermediate Precision ◽  
Peripheral Blood Mononuclear ◽  
Growth Inhibition Assay ◽  
Early Evaluation ◽  
Human Primate

AbstractWe present a non-human primate mycobacterial growth inhibition assay (MGIA) using in vitro blood or cell co-culture with the aim of refining and expediting early tuberculosis vaccine testing. We have taken steps to optimise the assay using cryopreserved peripheral blood mononuclear cells, transfer it to end-user institutes, and assess technical and biological validity. Increasing cell concentration or mycobacterial input and co-culturing in static 48-well plates compared with rotating tubes improved intra-assay repeatability and sensitivity. Standardisation and harmonisation efforts resulted in high consistency agreements, with repeatability and intermediate precision <10% coefficient of variation (CV) and inter-site reproducibility <20% CV; although some systematic differences were observed. As proof-of-concept, we demonstrated ability to detect a BCG vaccine-induced improvement in growth inhibition in macaque samples, and a correlation between MGIA outcome and measures of protection from in vivo disease development following challenge with either intradermal BCG or aerosol/endobronchial Mycobacterium tuberculosis (M.tb) at a group and individual animal level.

Cortisol-induced CXCR4 augmentation mobilizes T lymphocytes after acute physical stress

2005 ◽  
Vol 288 (3) ◽  
pp. R591-R599 ◽  
Author(s):  
Mitsuharu Okutsu ◽  
Kenji Ishii ◽  
Kai Jun Niu ◽  
Ryoichi Nagatomi
Keyword(s):  
T Lymphocytes ◽  
Mononuclear Cells ◽  
Cxcr4 Expression ◽  
Peripheral Blood Mononuclear ◽  
Cycling Exercise ◽  
Ru 486 ◽  
Before And After ◽  
Stromal Cell Derived Factor ◽  
Chemokine Receptor 4

The aim of this study was to elucidate the mechanism responsible for lymphopenia after exercise. Seven young healthy men volunteered for this study. Peripheral blood mononuclear cells (PBMC) were cultured with cortisol and analyzed for C-X-C motif chemokine receptor 4 (CXCR4) expression by flow cytometry. To determine the effects of exercise, subjects performed exhaustive cycling exercise. PBMC were cultured with plasma obtained before and after the cycling exercise. Alternatively, PBMC obtained before and after exercise were cultured without plasma or glucocorticoid to examine whether PBMC were primed in vivo for CXCR4 expression. We analyzed cortisol- or plasma-treated PBMC to determine their ability to migrate through membrane filters in response to stromal cell-derived factor 1α/CXCL12. Cortisol dose- and time-dependently augmented CXCR4 expression on T lymphocytes, with <6 h of treatment sufficient to augment CXCR4 on T lymphocytes. Postexercise plasma also augmented CXCR4 expression. Cortisol or postexercise plasma treatment markedly enhanced migration of T lymphocytes toward CXCL12. Augmentation of CXCR4 on T lymphocytes by cortisol or plasma was effectively blocked by the glucocorticoid receptor antagonist RU-486. Thus exercise-elicited endogenous cortisol effectively augments CXCR4 expression on T lymphocytes, which may account for lymphopenia after exercise.

scholarly journals Monocyte tissue factor induction by lipopolysaccharide (LPS): dependence on LPS-binding protein and CD14, and inhibition by a recombinant fragment of bactericidal/permeability-increasing protein

Blood ◽  
1994 ◽  
Vol 83 (9) ◽  
pp. 2516-2525 ◽  
Author(s):  
K Meszaros ◽  
S Aberle ◽  
R Dedrick ◽  
R Machovich ◽  
A Horwitz ◽  
...  
Keyword(s):  
Tissue Factor ◽  
Mononuclear Cells ◽  
Human Peripheral Blood ◽  
Binding Protein ◽  
Mononuclear Phagocytes ◽  
Factor Vii ◽  
Peripheral Blood Mononuclear ◽  
Recombinant Fragment

Abstract Mononuclear phagocytes, stimulated by bacterial lipopolysaccharide (LPS), have been implicated in the activation of coagulation in sepsis and endotoxemia. In monocytes LPS induces the synthesis of tissue factor (TF) which, assembled with factor VII, initiates the blood coagulation cascades. In this study we investigated the mechanism of LPS recognition by monocytes, and the consequent expression of TF mRNA and TF activity. We also studied the inhibition of these effects of LPS by rBPI23, a 23-kD recombinant fragment of bactericidal/permeability increasing protein, which has been shown to antagonize LPS in vitro and in vivo. Human peripheral blood mononuclear cells, or monocytes isolated by adherence, were stimulated with Escherichia coli O113 LPS at physiologically relevant concentrations (&gt; or = 10 pg/mL). The effect of LPS was dependent on the presence of the serum protein LBP (lipopolysaccharide-binding protein), as shown by the potentiating effect of human recombinant LBP or serum. Furthermore, recognition of low amounts of LPS by monocytes was also dependent on CD14 receptors, because monoclonal antibodies against CD14 greatly reduced the LPS sensitivity of monocytes in the presence of serum or rLBP. Induction of TF activity and mRNA expression by LPS were inhibited by rBPI23. The expression of tumor necrosis factor showed qualitatively similar changes. Considering the involvement of LPS-induced TF in the potentially lethal intravascular coagulation in sepsis, inhibition of TF induction by rBPI23 may be of therapeutic benefit.

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