Fluorescent probe-labeled lipid microsphere uptake by human endothelial cells: a flow cytometric study

Short Review of Liposteroid: A Novel Targeted Glucocorticoid Preparation for Treatment of Autoimmune and Inflammatory Diseases

This paper briefly reviews the safety and efficacy of liposteroid in different inflammatory and non-inflammatory diseases. Corticosteroids (CS) are the first-line therapy in many inflammatory and autoimmune disorders. Although highly efficacious, long-term use of CS is limited due to the occurrence of significant side effects. Liposteroid, which is a liposomal formulation of dexamethasone palmitate, possess more potent anti-inflammatory and immunosuppressive properties compared to dexamethasone sodium phosphate. These two formulations have markedly different lipid solubility, resulting in different pharmacokinetic and pharmacodynamic properties. Liposteroid has been used with success in patients with rheumatoid arthritis, macrophage activation syndrome, and idiopathic pulmonary hemosiderosis. In addition, liposteroid has been used in some non-inflammatory diseases. Moreover, we conceive that liposteroid may have a beneficial effect in patients, who are critically ill due to COVID-19, and suffer from the macrophage activation syndrome.

A Near-Infrared Organic Fluorescent Probe for Broad Applications for Blood Vessels Imaging by High-Throughput Screening via 3D-Blood Vessel Models

Blood vessels are present in all of the organs, reflecting their importance for oxygen and nutrient delivery to the cells. Until now, no organic fluorophore has been reported for the live imaging of endothelium although the layer is the key to blood vessel functions. Here, the discovery of a blood vessel organic probe at near-infrared (NIR) wavelength range (BV-NIR) through an engineered blood capillary-based screening system, which is a more physiological model than a conventional cell culture condition, is reported. This selected Cy5 based probe shows the highest specific adsorption property out of 240 candidates on the endothelium and is equivalent to an anti-CD31 antibody in terms of intensity. The BV-NIR probe indicating strong and stable in vitro, ex vivo, and in vivo imaging of the endothelium even after histological immunostaining processes shows potential as a convenient tool for live imaging as well as for covisualization with a specific antibody.

The Comparison Study of Lipo PGE1 Preparations

The comparison study was performed with 3 kinds of Lipo PGE(1) (5 microg/ml) preparations (Formulation A, B, and C), which are now used in clinical. Under alkali condition, Lipo PGE(1) (5 microg/ml) preparations in combination with physiological solution containing calcium ion were susceptible to stop dropping because of the formation of aggregates. There was a difference of feasibility to form aggregates among these preparations. The percentage of PGE(1) in the LM (lipid microspheres) was 68.8% (Formulation A) when determined by filtration with the pore size of 0.1 microm, and the respective value (%) of Formulation B and Formulation C was 43.0% and 13.9%. This indicates that the latter formulations were significantly susceptible to leak from the LM. PGE(1) can induce an extensive irritation. The potency of irritation was the most in Formulation C. This seems similar with the result of LM retention of PGE(1). PGE(1) increased the blood flow. Formulation A reached the peak by 2.27 fold, which was significantly higher than Formulation C and PGE(1) alone (PGE(1)-cyclodextrin, PGE(1)-CD). The peak was also significantly higher in Formulation B than that of PGE(1)-CD. The AUC value of blood flow rate showed a significant increase in Formulation A and Formulation B as compared to that of PGE(1)-CD. Drug retention in the LM can be a determinant factor for drug distribution and pharmacological effect. This study indicates that there can be some differences among Lipo PGE(1) preparations, which have the same drug dose.

Successful treatment with liposteroid followed by reduced intensity stem cell transplantation in an infant with perforin deficiency presenting with hemophagocytic lymphohistiocytosis

Perforin deficiency characterized by markedly reduced cytotoxic T and natural killer cell activities is one type of familial hemophagocytic lymphohistiocytosis (FHL). FHL is a fatal inherited disease, and treatment with stem cell transplantation has resulted in a normal activity of killer cells. We herein report a case of FHL with perforin deficiency that was primarily treated by the administration of liposteroid to reduce hypercytokinemia. Thereafter, allogenic bone marrow transplantation with nonmyeloablative conditioning was successfully performed without any adverse effects on the patient's physical or developmental status. These observations suggest that this treatment strategy might thus be recommended in infants with FHL to reduce treatment-related complications, especially in patients with relatively mild clinical courses.

Effects of liposteroid on the hemophagocytic syndrome in systemic lupus erythematosus

Hemophagocytic syndrome (HPS) is a life-threatening disorder characterized by pancytopenia and activation of macrophages. Recently, corticosteroid incorporated in lipid microspheres (liposteroid) has been reported to be taken up by macrophages and to suppress their functions. Here we present a case of systemic lupus erythematosus complicated by HPS that was successfully treated with liposteroid in addition to an oral corticosteroid and intravenous high-dose cyclophosphamide therapy. The serum levels of tumor necrosis factor-alpha and ferritin that have been reported to be associated with activity of macrophages remarkably reduced after liposteroid administration. This case suggests that liposteroid is useful for the treatment of HPS.

Lipid microspheres incorporated by U937 cells via their specific receptors

Lipid microspheres (LM), currently in clinical use as drug carriers, mainly consist of soybean oil as a core and lecithin as a surfactant. The purpose of our study wass to determine whether or not LM incorporation is receptor-mediated. U937 cells resuspended in a serum-free medium abundantly took up unmodulated LM. A binding study showed that U937 cells had a single binding site for LM (410 sites/cell at 24°C; 100 sites/cell at 4°C). Inhibition assays revealed that lecithin liposome, lysophosphatidylcholines, activated α2-macroglobulin, and HDL did not affect the binding of LM to U937 cells. VLDL strongly, and LDL and AcLDL moderately, inhibited the binding of LM to U937 cells. Ligand blotting analysis revealed that unmodulated LM in an apoprotein-free buffer directly bound to a 40 kDa protein in the cell membrane fraction. These results suggest that LM that is not modulated by any protein is incorporated by specific cells via receptor-mediated processes.Key words: lipid emulsion, drug delivery system, monocyte, free fatty acids.

Hepatic stellate cell contraction is inhibited by lipo-prostaglandin E1 in vitro

Prostaglandin E₁ (PGE₁ ) has been reported to have, experimentally and clinically, a protective effect against liver damage. This effect may result from the relaxation of hepatic stellate cells, whose contraction induces vasoconstriction of hepatic sinusoids. However, prostaglandins are unstable and a new drug delivery system is necessary to administer a sufficient amount of prostaglandin to achieve a protective effect in the liver. The aim of the study is to investigate the effects of lipo-prostaglandin E₁ (lipo-PGE₁ ) which has a novel drug delivery system on the stellate cell contraction induced by endothelin-1 in vitro. Lipo-PGE₁ inhibited endothelin-1-induced stellate cell contraction in concentrations of 10, 30 and 50 ng/mL. Therefore, lipo-PGE₁ may show a cytoprotective effect in the liver through the relaxation of stellate cells and an increase in the hepatic sinusoidal blood flow.

Characterization of tissue factor expression on the human endothelial cell line ECV304

The endothelial cell line ECV304 is a spontaneously transformed cell line established from human umbilical vein. The characterization of tissue factor (TF) expression by ECV304 cells has been accomplished in this study. ECV304 cells expressed both TF mRNA and antigen (TFag) constitutively. In ECV304 cell lysates, the levels of TFag (1.4+/-0.3 ng of TFag/10[6] cells) were considerably higher than in THP-1 monocytoid cells (0.07+/-0.03 ng of TFag/10[6] cells). TFag was also detected on the ECV304 cell surface by flow cytometric studies. In binding analyses, 3.5+/-0.7 x 10(4) molecules of TF per cell were estimated, similar to the amounts found in ECV304 cell lysates (2.9+/-0.6 x 10(4) molecules/cell), suggesting that all TFag was translocated to the cell surface. Phorbol myristate acetate (PMA) stimulation of ECV304 cells resulted in an increase of TF mRNA levels, which was abrogated when gene transcription was impaired, suggesting a transcriptional regulation of the TF gene by PMA. In contrast, TFag was not elevated by PMA-stimulation, indicating the existence of additional posttranscriptional mechanisms. Thus, ECV304 cells constitute a singular endothelial cell model for exploring the regulation of TF expression.

Blood-brain-barrier transport of lipid microspheres containing clinprost, a prostaglandin I2 analogue

Because the permeability of the blood-brain barrier to lipid microspheres (LMs) has not hitherto been demonstrated, blood-brain-barrier permeability to LM containing the prostaglandin I2 analogue clinprost has been evaluated for an in-vitro system of primary cultured monolayers of bovine brain capillary endothelial cells (BCECs), by a capillary depletion study in rats and by an in-situ brain perfusion study in normal and 4-vessel-occluded fore brain ischaemic rats. Although energy-dependency was not observed in [3H]clinprost uptake by BCECs, in accordance with results for simple diffusional transport, uptake of [3H]clinprost contained in lipid microspheres (denoted [3H]clinprost(LM)) was significantly inhibited by the endocytosis inhibitor, dansylcadaverine. The transport of LM into BCECs by endocytosis was also confirmed by fluorescence microscopy and flow-cytometric analysis using LM labelled with a fluorescent probe, 1,1'-dioctadecyl-3,3,3',3'-tetramethylindocarbocyanine perchlorate (Dil). The absolute uptake of Dil(LM) by BCECs, measured by HPLC, was, however, almost 1/10 that of [3H]clinprost(LM), results which suggest the superiority of simple diffusion of clinprost over endocytosis of its LM form in the uptake of clinprost(LM) by BCECs. In the capillary-depletion study with rat-brain-perfused [3H]clinprost(LM) from the internal carotid artery, the parenchyma apparent distribution volume was about 45 times larger than that of the capillary, showing that [3H]clinprost(LM) was transported through the blood-brain barrier into the brain. The permeability coefficients of [3H]clinprost and [3H]clinprost(LM) determined by insitu brain perfusion in normal rats were considerably higher than those of the active metabolite [3H]isocarbacyclin and its LM form. In addition, the Blood-brain-barrier permeabilities to [3H]clinprost, [3H]isocarbacyclin and their LM forms in ischaemic rats were almost identical to those in normal rats. It was concluded that clinprost(LM) was transported through the blood-brain barrier by endocytosis of LM, simple diffusion of clinprost released from LM, and transport of isocarbacyclin generated by hydrolysis of clinprost. The blood-brain-barrier permeability of clinprost(LM) is not reduced in ischaemic conditions, because the simple diffusion of clinprost released from LM contributed mainly to clinprost(LM) transport.

Effects of lipo-prostaglandin E1 on random pattern flaps in rabbits

The effects of lipo-prostaglandin (PG) E1, which are lipid microspheres containing PGE1, were examined using 2 x 12 cm random pattern skin flaps on the backs of five rabbits. Five rabbits acted as controls. Both surviving length (8.5 (3.1) compared with 4.9 (1.8) cm) and surviving area (22.1 (9.3) compared with 11.5 (6.1) cm2) of the skin flap were significantly increased (p < 0.03 in each case). In three additional rabbits the blood flow on the distal side of the skin flap, where it was poor, was measured using a laser image blood flowmeter. Blood flow was improved five to 15 minutes after injection of lipo-PGE1 and was maintained for at least 60 minutes. In conclusion, lipo-PGE1 increased the blood flow of the random skin flaps, resulting in significant enlargement of the surviving area of skin flaps.

Activated CD4+ T cells preferentially take up lipid microspheres, but resting cells do not

Lipid microspheres (LM) used as drug carriers increase the effectiveness and reduce the toxicity of incorporated drugs. The present study is designed to determine whether or not activated T lymphocytes, which were the cells chosen first from the 'inflammatory cells', can take up LM in vitro. LM were labelled with a fluorescent probe, DiI (DiI-LM), to examine the kinetics. Flow cytometric analysis demonstrated that in freshly isolated peripheral blood mononuclear cells (PBMC), monocytes principally took up DiI-LM, while lymphocytes and granulocytes did not. When PBMC were stimulated with immobilized anti-CD3 MoAb and IL-2, cells expressing CD3, CD4, CD8 and CD16 incorporated DiI-LM. Purified CD4+ T cells, obtained by positive panning selection, were stimulated with this system. They were CD25, CD71, LFA-1-positive, and also showed an ability to take up DiI-LM, which resting cells did not. The findings were confirmed by flow cytometry and quantitative analysis of DiI. Confocal micrographs showed fluorescent granules from the probe in the cytoplasm of stimulated CD4+ T cells after incubation with DiI-LM. These results suggest that immunomodulatory agents incorporated into LM might selectively regulate the function of CD4+ or CD8+ T cells when these are activated.