CD47 Activation by Thrombospondin-1 in Lymphatic Endothelial Cells Suppresses Lymphangiogenesis and Promotes Atherosclerosis.

BACKGROUND: TSP1 (thrombospondin-1)-a well-known angiogenesis inhibitor-mediates differential effects via interacting with cell surface receptors including CD36 (cluster of differentiation) and CD47. However, the role of TSP1 in regulating lymphangiogenesis is not clear. Our previous study suggested the importance of cell-specific CD47 blockade in limiting atherosclerosis. Further, our experiments revealed CD47 as a dominant TSP1 receptor in lymphatic endothelial cells (LECs). As the lymphatic vasculature is functionally linked to atherosclerosis, we aimed to investigate the effects of LEC TSP1-CD47 signaling inhibition on lymphangiogenesis and atherosclerosis. METHODS: Murine atherosclerotic and nonatherosclerotic arteries were utilized to investigate TSP1 expression using Western blotting and immunostaining. LEC-specific knockout mice were used to determine the in vivo role of LEC Cd47 in lymphangiogenesis and atherosclerosis. Various in vitro cell-based assays, in vivo Matrigel plug implantation, molecular biological techniques, and immunohistological approaches were used to evaluate the underlying signaling mechanisms. RESULTS: Elevated TSP1 expression was observed in mouse atherosclerotic aortic tissue compared with nonatherosclerotic control tissue. TSP1 at pathological concentrations suppressed both in vitro and in vivo lymphangiogenesis. Mechanistically, TSP1 inhibited VEGF (vascular endothelial growth factor)-C-induced AKT and eNOS activation in LEC and attenuated NO (nitric oxide) production. Further, CD47 silencing in LEC prevented the effects of TSP1 on lymphangiogenic AKT-eNOS signaling and lymphangiogenesis. Atheroprone AAV (adeno-associated virus) 8-PCSK9-injected LEC-specific Cd47 knockout mice (Cd47ΔLEC) had reduced atherosclerosis in both aorta and aortic root compared with control mice (Cd47ΔWT). However, no differences in metabolic parameters including body weight, plasma total cholesterol levels, and fasting blood glucose were observed. Additional immunostaining experiments performed on aortic root cross-sections indicated higher lymphatic vessel density in Cd47ΔLEC mice in comparison to controls. CONCLUSIONS: These findings demonstrate that TSP1 inhibits lymphangiogenesis via activation of CD47 in LEC, and loss of LEC Cd47 attenuates atherosclerotic lesion formation. Collectively, these results identify LEC CD47 as a potential therapeutic target in atherosclerosis.

A pilot study on impact of use of medium molecular weight hydroxyethyl starch in granulocyte apheresis using Spectra Optia.

INTRODUCTION: Granulocyte transfusion (GT) is a therapeutic option for prolonged neutropenic patients with severe bacterial or fungal infections. Efficient apheresis based granulocyte collection may be better achieved by infusion of high-molecular-weight (HMW) hydroxyethyl starch (HES). But multiple adverse incidents have been reported with HMW-HES. Due to availability issues and adverse incidents related to it, use of HMW-HES has become limited. Few studies have mentioned about medium molecular weight HES (MMW-HES) (130 kDa) as efficient for this purpose with minimal adverse incidents. So, the aim was to assess the impact of the use of MMW-HES in granulocyte apheresis when using Spectra Optia. METHODOLOGY: In this observational study, donors who received MMW-HES during granulocyte harvest were included in HES group and another group who did not receive HES were grouped as non-HES. Injection G-CSF 10 microgram/kg and tablet dexamethasone 8 mg given 12 h before for non-HES group and 6 - 8 h in case of HES group blood donors. Number of adverse incidents observed were noted. Donor/procedure parameters were compared using Mann-Whitney U test / unpaired t test. RESULTS: Granulocyte yield was significantly higher in the HES group (2.5 × 1010 vs. 1.75 × 1010, p < 0.01) and was attributed to the difference in collection efficiency (22.61% vs. 10.15%, p < 0.01). There were no significant differences in occurrence of adverse events between HES and non-HES groups. CONCLUSION: Our results clearly indicate that sufficient number of granulocytes can be harvested by using MMW-HES in Spectra Optia apheresis system even after short interval between mobilization to harvest.

Matricellular proteins in atherosclerosis development.

The extracellular matrix (ECM) is an intricate network composed of various multi-domain macromolecules like collagen, proteoglycans, and fibronectin, etc., that form a structurally stable composite, contributing to the mechanical properties of tissue. However, matricellular proteins are non-structural, secretory extracellular matrix proteins, which modulate various cellular functions via interacting with cell surface receptors, proteases, hormones, and cell-matrix. They play essential roles in maintaining tissue homeostasis by regulating cell differentiation, proliferation, adhesion, migration, and several signal transduction pathways. Matricellular proteins display a broad functionality regulated by their multiple structural domains and their ability to interact with different extracellular substrates and/or cell surface receptors. The expression of these proteins is low in adults, however, gets upregulated following injuries, inflammation, and during tumor growth. The marked elevation in the expression of these proteins during atherosclerosis suggests a positive association between their expression and atherosclerotic lesion formation. The role of matricellular proteins in atherosclerosis development has remained an area of research interest in the last two decades and studies revealed these proteins as important players in governing vascular function, remodeling, and plaque formation. Despite extensive research, many aspects of the matrix protein biology in atherosclerosis are still unknown and future studies are required to investigate whether targeting pathways stimulated by these proteins represent viable therapeutic approaches for patients with atherosclerotic vascular diseases. This review summarizes the characteristics of distinct matricellular proteins, discusses the available literature on the involvement of matrix proteins in the pathogenesis of atherosclerosis and suggests new avenues for future research.

Hydrogen sulfide donor activates AKT-eNOS signaling and promotes lymphatic vessel formation.

The lymphatic network is pivotal for various physiological functions in the human body. Accumulated evidence supports the role of therapeutic lymphangiogenesis in the treatment of several pathologies. Endogenous gasotransmitter, hydrogen sulfide (H2S) has been extensively studied for its potential as a pro-angiogenic factor and vascular function modulator. However, the role of H2S in governing lymphatic vessel formation, and underlying molecular mechanisms are understudied. The present study was designed to investigate the effects of H2S donor sodium hydrogen sulfide (NaHS) on lymphatic vascularization and pro-angiogenic signaling pathways using both in vitro and in vivo approaches. In vitro dose-response experiments showed increased proliferation and tube formation by NaHS-treated human lymphatic endothelial cells (LECs) compared with control cells. Immunoblotting performed with LEC lysates prepared after time-course NaHS treatment demonstrated increased activation of ERK1/2, AKT and eNOS after 20 min of NaHS stimulation. Further, NaHS treatment induced nitric oxide production, reduced reactive oxygen species generation, and promoted cell cycle in LECs. Additional cell cycle analysis showed that NaHS treatment abrogates oxidized LDL-induced cell cycle arrest in LECs. The results of in vivo Matrigel plug assay revealed increased lymphatic vessel density in Matrigel plugs containing NaHS compared with control plugs, however, no significant differences in angiogenesis and immune cell infiltration were observed. Collectively, these findings suggest that H2S donor NaHS promotes lymphatic vessel formation both in vitro and in vivo and may be utilized to promote reparative lymphangiogenesis to alleviate lymphatic dysfunction-related disorders.

An audit to estimate the quality of practices followed during bedside blood transfusion in a tertiary care hospital and role of continuous medical education in it.

Blood transfusion is an integral component of the health Service system and it becomes imperative that its benefits, risks as well as prospective and viable alternatives of this common medical intervention are explained explicitly to the patients. Appropriate compliance to bedside blood transfusion practices can also help in avoiding adverse transfusion outcomes. At the same time, it is also crucial to document a patient's valid consent based on their decision after evaluation of the risk to benefit ratio. This audit aims to assess the compliance and adherence to bedside blood transfusion practices in a tertiary care hospital and role of Continuous Medical education (CME) on it. The study involved collection of data for blood transfusion services and practices in two periods, for adults and children, who received transfusion from the month of June 2021 to October 2021 and a re-audit beginning from November 2021 to February 2022 following few CMEs in between involving doctors and nurses. A total of 3240 transfusion procedures were assessed in this duration. In them 1500 (46.3%) took place before CME and remaining 1740 (53.7%) procedures took place after CME. There were statistically significant differences between pre-CME and post-CME bedside transfusion practices. During CME/training session, pre-training and post training knowledge has been evaluated by test which also showed statistically significant difference in knowledge of transfusion medicine & bedside transfusion practices. Our study recommends that there is a need of frequent audit on bedside transfusion practices to check the quality and standards associated with it and also points out the need of continuous medical education on this issue.