scholarly journals Leishmania Donovani. Hamster macrophage interactions in vitro: cell entry, intracellular survival, and multiplication of amastigotes

1978 ◽  
Vol 147 (2) ◽  
pp. 515-530 ◽  
Author(s):  
K-P Chang ◽  
DM Dwyer
Keyword(s):  
Leishmania Donovani ◽  
Peritoneal Macrophages ◽  
Host Cells ◽  
Cellular Interactions ◽  
Predominant Type ◽  
Macrophage Subpopulations ◽  
Host Parasite ◽  
Vacuolar System

An in vitro system was developed for studying host-parasite cellular interactions in visceral leishmaniasis with amastigotes isolated from infected spleens of hamsters and their peritoneal macrophages maintained by an improved method. The culture system supports the growth of Leishmania donovani amastigotes with different parasite/macrophage ratios for up to 2 wk, yielding results more consistent and reproducible than previously possible. Results indicated that the forms of the amastigotes (with or without adherent host membranes) and the state of the macrophages (with or without stimulation in vivo by thioglycollate or in vitro by aging) had no effect on the growth rate of the parasites, which, however, seems to vary with the macrophage subpopulations. An electron microscope study suggests that amastigotes are ingested through phagocytosis by the macrophages and become lodged in loose phagosomes. Additional evidence with quantitative data is presented to support the earlier findings that phagosome-lysosome fusion occurs after the interiorization of the parasites and that they not only survive but multiply in these vacuoles. During the postinfection periods, reorientation of amastigotes in vacuolar space results in the appearance of three types of parasitophorous vacuoles (parasites in loose vacuoles, in tight-fitting vacuoles or abutting in part against the inner lining of vacuoles). The last category may be the predominant type giving rise to the variations observed. Exogenously introduced dense marker accumulated in these parasitophorous vacuoles of the macrophages infected for several days indicating a continuous accessibility of amastigotes to the ambient mestruum via phagosome-lysosome vacuolar system of the host cells. This finding may have significant implications in parasite nutrition, host immunity, and chemotherapy of leishmaniasis.

scholarly journals In Vitro and In Vivo Activities of a Triterpenoid Saponin Extract (PX-6518) from the Plant Maesa balansae against Visceral Leishmania Species

2004 ◽  
Vol 48 (1) ◽  
pp. 130-136 ◽  
Author(s):  
Louis Maes ◽  
Dirk Vanden Berghe ◽  
Nils Germonprez ◽  
Ludo Quirijnen ◽  
Paul Cos ◽  
...  
Keyword(s):  
Leishmania Donovani ◽  
Human Fibroblasts ◽  
Subcutaneous Administration ◽  
Leishmania Species ◽  
Host Cells ◽  
Triterpenoid Saponin ◽  
Sodium Stibogluconate ◽  
Triterpenoid Saponins

ABSTRACT The in vitro and in vivo activities of a mixture of six oleane triterpene saponins, recovered from the methanolic extract of the leaves of the Vietnamese plant Maesa balansae (PX-6518), were evaluated against drug-sensitive visceral Leishmania strains. The in vitro 50% inhibitory concentration (IC50) against intracellular Leishmania infantum amastigotes was 0.04 μg/ml. The cytotoxic concentrations causing 50% cell death (CC50s) were about 1 μg/ml in murine macrophage host cells and >32 μg/ml in human fibroblasts (MRC-5 cell line). Evaluation in the Leishmania donovani BALB/c mouse model indicated that a single subcutaneous administration of 0.4 mg/kg at 1 day after infection reduced liver amastigote burdens by about 95% in all treated animals. If treatment was delayed until 14 days after infection, a dose of 1.6 mg/kg of body weight was required to maintain the same level of activity. Single 250-mg/kg doses of sodium stibogluconate (Pentostam) 1 and 14 days after infection produced comparable efficacies. A single dose of PX-6518 at 2.5 mg/kg administered 5 days before infection was still 100% effective in preventing liver infection, suggesting a particularly long residual action. Spleen and bone marrow could not be cleared by PX-6518 nor sodium stibogluconate. PX-6518 did not show activity after oral dosing at up to 200 mg/kg for 5 days. This study concludes that triterpenoid saponins from M. balansae show promising in vitro and in vivo antileishmanial potential and can be considered as new lead structures in the search for novel antileishmanial drugs.

scholarly journals Elucidating the role of leptin in systemic inflammation: a study targeting physiological leptin levels in rats and their macrophages

2017 ◽  
Vol 313 (5) ◽  
pp. R572-R582 ◽  
Author(s):  
Elizabeth A. Flatow ◽  
Evilin N. Komegae ◽  
Monique T. Fonseca ◽  
Camila F. Brito ◽  
Florin M. Musteata ◽  
...  
Keyword(s):  
Food Deprivation ◽  
Systemic Inflammation ◽  
Peritoneal Macrophages ◽  
Tnf Α ◽  
Macrophage Subpopulations ◽  
Limited Food ◽  
The Brain

To elucidate the role of leptin in acute systemic inflammation, we investigated how its infusion at low, physiologically relevant doses affects the responses to bacterial lipopolysaccharide (LPS) in rats subjected to 24 h of food deprivation. Leptin was infused subcutaneously (0–20 μg·kg−1·h−1) or intracerebroventricularly (0–1 μg·kg−1·h−1). Using hypothermia and hypotension as biomarkers of systemic inflammation, we identified the phase extending from 90 to 240 min post-LPS as the most susceptible to modulation by leptin. In this phase, leptin suppressed the rise in plasma TNF-α and accelerated the recoveries from hypothermia and hypotension. Suppression of TNF-α was not accompanied by changes in other cytokines or prostaglandins. Leptin suppressed TNF-α when infused peripherally but not when infused into the brain. Importantly, the leptin dose that suppressed TNF-α corresponded to the lowest dose that limited food consumption; this dose elevated plasma leptin within the physiological range (to 5.9 ng/ml). We then conducted in vitro experiments to investigate whether an action of leptin on macrophages could parallel our in vivo observations. The results revealed that, when sensitized by food deprivation, LPS-stimulated peritoneal macrophages can be inhibited by leptin at concentrations that are lower than those reported to promote cytokine release. It is concluded that physiological levels of leptin do not exert a proinflammatory effect but rather an anti-inflammatory effect involving selective suppression of TNF-α via an action outside the brain. The mechanism of this effect might involve a previously unrecognized, suppressive action of leptin on macrophage subpopulations sensitized by food deprivation, but future studies are warranted.

scholarly journals Efficacy of a Binuclear Cyclopalladated Compound Therapy for Cutaneous Leishmaniasis in the Murine Model of Infection with Leishmania amazonensis and Its Inhibitory Effect on Topoisomerase 1B

2017 ◽  
Vol 61 (8) ◽  
Author(s):  
Angela Maria Arenas Velásquez ◽  
Willian Campos Ribeiro ◽  
Vutey Venn ◽  
Silvia Castelli ◽  
Mariana Santoro de Camargo ◽  
...  
Keyword(s):  
Leishmania Donovani ◽  
Parasite Load ◽  
Inhibitory Effect ◽  
Peritoneal Macrophages ◽  
Leishmania Amazonensis ◽  
Content Type ◽  
Intracellular Amastigotes ◽  
Therapeutic Alternatives

ABSTRACT Leishmaniasis is a disease found throughout the (sub)tropical parts of the world caused by protozoan parasites of the Leishmania genus. Despite the numerous problems associated with existing treatments, pharmaceutical companies continue to neglect the development of better ones. The high toxicity of current drugs combined with emerging resistance makes the discovery of new therapeutic alternatives urgent. We report here the evaluation of a binuclear cyclopalladated complex containing Pd(II) and N,N′-dimethylbenzylamine (Hdmba) against Leishmania amazonensis. The compound [Pd(dmba)(μ-N3)]2 (CP2) inhibits promastigote growth (50% inhibitory concentration [IC50] = 13.2 ± 0.7 μM) and decreases the proliferation of intracellular amastigotes in in vitro incubated macrophages (IC50 = 10.2 ± 2.2 μM) without a cytotoxic effect when tested against peritoneal macrophages (50% cytotoxic concentration = 506.0 ± 10.7 μM). In addition, CP2 was also active against T. cruzi intracellular amastigotes (IC50 = 2.3 ± 0.5 μM, selective index = 225), an indication of its potential for use in Chagas disease therapy. In vivo assays using L. amazonensis-infected BALB/c showed an 80% reduction in parasite load compared to infected and nontreated animals. Also, compared to amphotericin B treatment, CP2 did not show any side effects, which was corroborated by the analysis of plasma levels of different hepatic and renal biomarkers. Furthermore, CP2 was able to inhibit Leishmania donovani topoisomerase 1B (Ldtopo1B), a potentially important target in this parasite. (This study has been registered at ClinicalTrials.gov under identifier NCT02169141.)

scholarly journals Establishment of a Patient-Derived, Magnetic Levitation-Based, 3D Spheroid Granuloma Model for Human Tuberculosis.

2021 ◽  
Author(s):  
Leigh Ann Kotze ◽  
Caroline G.G. Beltran ◽  
Dirk Lang ◽  
Andre G Loxton ◽  
Susan Cooper ◽  
...  
Keyword(s):  
Immune Cell ◽  
Magnetic Levitation ◽  
Cell Types ◽  
Host Cells ◽  
Cellular Interactions ◽  
Cell Recruitment ◽  
Metabolic Heterogeneity ◽  
Histological Architecture

Tuberculous granulomas that develop in response to Mycobacterium tuberculosis (M.tb) infection are highly dynamic entities shaped by the host immune response and disease kinetics. Within this microenvironment, immune cell recruitment, polarization and activation is driven not only by co-existing cell types and multi-cellular interactions, but also by M.tb-mediated changes involving metabolic heterogeneity, epigenetic reprogramming and rewiring of the transcriptional landscape of host cells. There is an increased appreciation of the in vivo complexity, versatility and heterogeneity of the cellular compartment that constitutes the tuberculosis (TB) granuloma, and the difficulty in translating findings from animal models to human disease. Here we describe a novel biomimetic in vitro 3-dimentional (3D) human lung granuloma model, resembling early innate and adaptive stages of the TB granuloma spectrum, and present results of histological architecture, host transcriptional characterization, mycobacteriological features, cytokine profiles and spatial distribution of key immune cells. A range of manipulations of immune cell populations in these granulomas will allow the study of host/pathogen pathways involved in the outcome of infection, as well as pharmacological interventions.

scholarly journals Differences betweenMycobacterium-Host Cell Relationships in Latent Tuberculous Infection of MiceEx Vivoand Mycobacterial Infection of Mouse CellsIn Vitro

2016 ◽  
Vol 2016 ◽  
pp. 1-21 ◽  
Author(s):  
Elena Ufimtseva
Keyword(s):  
Bone Marrow ◽  
Ex Vivo ◽  
Mouse Cell ◽  
Peritoneal Macrophages ◽  
Host Cells ◽  
Tuberculous Infection ◽  
Mouse Bone Marrow ◽  
Activation Markers

The search for factors that account for the reproduction and survival of mycobacteria, including vaccine strains, in host cells is the priority for studies on tuberculosis. A comparison of BCG-mycobacterial loads in granuloma cells obtained from bone marrow and spleens of mice with latent tuberculous infection and cells from mouse bone marrow and peritoneal macrophage cultures infected with the BCG vaccinein vitrohas demonstrated that granuloma macrophages each normally contained a single BCG-Mycobacterium, while those acutely infectedin vitrohad increased mycobacterial loads and death rates. Mouse granuloma cells were observed to produce the IFNγ, IL-1α, GM-CSF, CD1d, CD25, CD31, СD35, and S100 proteins. None of these activation markers were found in mouse cell cultures infectedin vitroor in intact macrophages. Lack of colocalization of lipoarabinomannan-labeled BCG-mycobacteria with the lysosomotropic LysoTracker dye in activated granuloma macrophages suggests that these macrophages were unable to destroy BCG-mycobacteria. However, activated mouse granuloma macrophages could control mycobacterial reproduction in cells bothin vivoand inex vivoculture. By contrast, a considerable increase in the number of BCG-mycobacteria was observed in mouse bone marrow and peritoneal macrophages after BCG infectionin vitro, when no expression of the activation-related molecules was detected in these cells.

ACIS, A Novel KepTide™, Binds to ACE-2 Receptor and Inhibits the Infection of SARS-CoV2 Virus in vitro in Primate Kidney Cells: Therapeutic Implications for COVID-19 (Preprint)

2020 ◽  
Author(s):  
Avik Sotira Scientific
Keyword(s):  
Social Life ◽  
Plaque Assay ◽  
Host Cells ◽  
Surface Glycoprotein ◽  
Crystallographic Structure ◽  
Therapeutic Implications ◽  
Biochemical Assays ◽  
Targeted Medicine

UNSTRUCTURED Coronavirus disease 2019 (COVID-19) is a severe acute respiratory syndrome (SARS) caused by a virus known as SARS-Coronavirus 2 (SARS-CoV2). Without a targeted-medicine, this disease has been causing a massive humanitarian crisis not only in terms of mortality, but also imposing a lasting damage to social life and economic progress of humankind. Therefore, an immediate therapeutic strategy needs to be intervened to mitigate this global crisis. Here, we report a novel KepTide™ (Knock-End Peptide) therapy that nullifies SARS-CoV2 infection. SARS-CoV2 employs its surface glycoprotein “spike” (S-glycoprotein) to interact with angiotensin converting enzyme-2 (ACE-2) receptor for its infection in host cells. Based on our in-silico-based homology modeling study validated with a recent X-ray crystallographic structure (PDB ID:6M0J), we have identified that a conserved motif of S-glycoprotein that intimately engages multiple hydrogen-bond (H-bond) interactions with ACE-2 enzyme. Accordingly, we designed a peptide, termed as ACIS (ACE-2 Inhibitory motif of Spike), that displayed significant affinity towards ACE-2 enzyme as confirmed by biochemical assays such as BLItz and fluorescence polarization assays. Interestingly, more than one biochemical modifications were adopted in ACIS in order to enhance the inhibitory action of ACIS and hence called as KEpTide™. Consequently, a monolayer invasion assay, plaque assay and dual immunofluorescence analysis further revealed that KEpTide™ efficiently mitigated the infection of SARS-CoV2 in vitro in VERO E6 cells. Finally, evaluating the relative abundance of ACIS in lungs and the potential side-effects in vivo in mice, our current study discovers a novel KepTide™ therapy that is safe, stable, and robust to attenuate the infection of SARS-CoV2 virus if administered intranasally. INTERNATIONAL REGISTERED REPORT RR2-https://doi.org/10.1101/2020.10.13.337584

scholarly journals Effective decellularisation of human saphenous veins for biocompatible arterial tissue engineering applications: Bench optimisation and feasibility in vivo testing

2021 ◽  
Vol 12 ◽  
pp. 204173142098752
Author(s):  
Nadiah S Sulaiman ◽  
Andrew R Bond ◽  
Vito D Bruno ◽  
John Joseph ◽  
Jason L Johnson ◽  
...  
Keyword(s):  
Tissue Engineering ◽  
Mechanical Strength ◽  
Vascular Tissue ◽  
Sodium Dodecyl ◽  
Host Cells ◽  
Replacement Model ◽  
In Vivo Testing ◽  
Vascular Scaffolds

Human saphenous vein (hSV) and synthetic grafts are commonly used conduits in vascular grafting, despite high failure rates. Decellularising hSVs (D-hSVs) to produce vascular scaffolds might be an effective alternative. We assessed the effectiveness of a detergent-based method using 0% to 1% sodium dodecyl sulphate (SDS) to decellularise hSV. Decellularisation effectiveness was measured in vitro by nuclear counting, DNA content, residual cell viability, extracellular matrix integrity and mechanical strength. Cytotoxicity was assessed on human and porcine cells. The most effective SDS concentration was used to prepare D-hSV grafts that underwent preliminary in vivo testing using a porcine carotid artery replacement model. Effective decellularisation was achieved with 0.01% SDS, and D-hSVs were biocompatible after seeding. In vivo xeno-transplantation confirmed excellent mechanical strength and biocompatibility with recruitment of host cells without mechanical failure, and a 50% patency rate at 4-weeks. We have developed a simple biocompatible methodology to effectively decellularise hSVs. This could enhance vascular tissue engineering toward future clinical applications.

scholarly journals Lipoproteins Are Responsible for the Pro-Inflammatory Property of Staphylococcus aureus Extracellular Vesicles

2021 ◽  
Vol 22 (13) ◽  
pp. 7099
Author(s):  
Pradeep Kumar Kopparapu ◽  
Meghshree Deshmukh ◽  
Zhicheng Hu ◽  
Majd Mohammad ◽  
Marco Maugeri ◽  
...  
Keyword(s):  
Extracellular Vesicles ◽  
Inflammatory Responses ◽  
Surface Proteins ◽  
Host Cells ◽  
Immune Stimulation ◽  
Domains Of Life ◽  
Major Surface ◽  
Staphylococcal Aureus

Staphylococcal aureus (S. aureus), a Gram-positive bacteria, is known to cause various infections. Extracellular vesicles (EVs) are a heterogeneous array of membranous structures secreted by cells from all three domains of life, i.e., eukaryotes, bacteria, and archaea. Bacterial EVs are implied to be involved in both bacteria–bacteria and bacteria–host interactions during infections. It is still unclear how S. aureus EVs interact with host cells and induce inflammatory responses. In this study, EVs were isolated from S. aureus and mutant strains deficient in either prelipoprotein lipidation (Δlgt) or major surface proteins (ΔsrtAB). Their immunostimulatory capacities were assessed both in vitro and in vivo. We found that S. aureus EVs induced pro-inflammatory responses both in vitro and in vivo. However, this activity was dependent on lipidated lipoproteins (Lpp), since EVs isolated from the Δlgt showed no stimulation. On the other hand, EVs isolated from the ΔsrtAB mutant showed full immune stimulation, indicating the cell wall anchoring of surface proteins did not play a role in immune stimulation. The immune stimulation of S. aureus EVs was mediated mainly by monocytes/macrophages and was TLR2 dependent. In this study, we demonstrated that not only free Lpp but also EV-imbedded Lpp had high pro-inflammatory activity.

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