Effect of glucocorticoids on the function of microvascular endothelial cells in the human femoral head bone

Integration of systematic review, lipidomics with experiment verification reveals abnormal sphingolipids facilitate diabetic retinopathy by inducing oxidative stress on RMECs

OBJECTIVE

This study aims to explore the potential biomarkers in the development of diabetes mellitus (DM) into diabetic retinopathy (DR).

METHODS

Systematic review of diabetic metabolomics was used to screen the differential metabolites and related pathways during the development of DM. Non-targeted lipidomics of rat plasma was performed to explore the differential metabolites in the development of DM into DR in vivo. To verify the effects of differential metabolites in inducing retinal microvascular endothelial cells (RMECs) injury by increasing oxidative stress, high glucose medium containing differential metabolites was used to induce rat RMECs injury and cell viability, malondialdehyde (MDA) contents, superoxide dismutase (SOD) activities, reactive oxygen species (ROS) levels and mitochondrial membrane potential (MMP) were evaluated in vitro. Network pharmacology was performed to explore the potential mechanism of differential metabolites in inducing DR.

RESULTS

Through the systematic review, 148 differential metabolites were obtained and the sphingolipid metabolic pathway attracted our attention. Plasma non-targeted lipidomics found that sphingolipids were accompanied by the development of DM into DR. In vitro experiments showed sphinganine and sphingosine-1-phosphate aggravated rat RMECs injury induced by high glucose, further increased MDA and ROS levels, and further decreased SOD activities and MMP. Network pharmacology revealed sphinganine and sphingosine-1-phosphate may induce DR by regulating the AGE-RAGE and HIF-1 signaling pathways.

CONCLUSIONS

Integrated systematic review, lipidomics and experiment verification reveal that abnormal sphingolipid metabolism facilitates DR by inducing oxidative stress on RMECs. Our study could provide the experimental basis for finding potential biomarkers for the diagnosis and treatment of DR.

Polarization Behavior of Bone Macrophage as Well as Associated Osteoimmunity in Glucocorticoid-Induced Osteonecrosis of the Femoral Head

Glucocorticoid-induced osteonecrosis of the femoral head (GIONFH) is a disabling disease with high mortality in China but the detailed molecular and cellular mechanisms remain to be investigated. Macrophages are considered the key cells in osteoimmunology, and the cross-talk between bone macrophages and other cells in the microenvironment is involved in maintaining bone homeostasis. M1 polarized macrophages launch a chronic inflammatory response and secrete a broad spectrum of cytokines (eg, TNF-α, IL-6 and IL-1β) and chemokines to initiate a chronic inflammatory state in GIONFH. M2 macrophage is the alternatively activated anti-inflammatory type distributed mainly in the perivascular area of the necrotic femoral head. In the development of GIONFH, injured bone vascular endothelial cells and necrotic bone activate the TLR4/NF-κB signal pathway, promote dimerization of PKM2 and subsequently enhance the production of HIF-1, inducing metabolic transformation of macrophage to the M1 phenotype. Considering these findings, putative interventions by local chemokine regulation to correct the imbalance between M1/M2 polarized macrophages by switching macrophages to an M2 phenotype, or inhibiting the adoption of an M1 phenotype appear to be plausible regimens for preventing or intervening GIONFH in the early stage. However, these results were mainly obtained by in vitro tissue or experimental animal model. Further studies to completely elucidate the alterations of the M1/M2 macrophage polarization and functions of macrophages in glucocorticoid-induced osteonecrosis of the femoral head are imperative.

The Plasminogen Activator System, Glucocorticoid, and Mineralocorticoid Receptors in the Primate Endometrium During Artificial Menstrual Cycles

As a key mechanism in fibrinolysis and tissue remodeling, the plasminogen activator system has been suggested in the process of endometrial shedding and tissue remodeling. Previous studies have explored the role of estrogen, progesterone, and androgen receptors as well as elements of the renin-angiotensin-aldosterone system in shaping the morphology of the endometrium. This study investigates the distribution and concentrations of the mineralocorticoid receptor, glucocorticoid receptor, tissue plasminogen activator, urokinase plasminogen activator, and plasminogen activator inhibitor-1 within the endometrial stroma, glandular, and endothelial cells of the primate endometrium during artificial menstrual cycles. Our immunohistochemistry quantification shows mineralocorticoid and glucocorticoid receptors are ubiquitously distributed within the macaque endometrium with their patterns of expression following similar fluctuations to urokinase and tissue plasminogen activators particularly within the endometrial vasculature. These proteins are present in endometrial vasculature in high levels during the proliferative phase, decreasing levels during the secretory phase followed by rising levels in the menstrual phase. These similarities could suggest overlapping pathways and interactions between the plasminogen activator system and the steroid receptors within the endometrium. Given the anti-inflammatory properties of glucocorticoids and the role of plasminogen activators in endometrial breakdown, the glucocorticoid receptor may be contributing to stabilizing the endometrium by regulating plasminogen activators during the proliferative phase and menstruation. Furthermore, given the anti-mineralocorticoid properties of certain anti-androgenic progestins and their reduced unscheduled uterine bleeding patterns, the mineralocorticoid receptor may be involved in unscheduled endometrial bleeding.

Steroid-Induced Osteonecrosis of the Femoral Head: Novel Insight Into the Roles of Bone Endothelial Cells in Pathogenesis and Treatment

Steroid-induced osteonecrosis of the femoral head (SONFH) is a disease characterized by the collapse of the femoral head. SONFH occurs due to the overuse of glucocorticoids (GCs) in patients with immune-related diseases. Among various pathogenesis proposed, the mechanism related to impaired blood vessels is gradually becoming the most convincing hypothesis. Bone endothelial cells including bone microvascular endothelial cells (BMECs) and endothelial progenitor cells (EPCs) play a crucial role in the maintenance of vascular homeostasis. Therefore, bone endothelial cells are key regulators in the occurrence and progression of SONFH. Impaired angiogenesis, abnormal apoptosis, thrombosis and fat embolism caused by the dysfunctions of bone endothelial cells are considered to be the pathogenesis of SONFH. In addition, even with high disability rates, SONFH lacks effective therapeutic approach. Icariin (ICA, a flavonoid extracted from Epimedii Herba), pravastatin, and VO-OHpic (a potent inhibitor of PTEN) are candidate reagents to prevent and treat SONFH through improving above pathological processes. However, these reagents are still in the preclinical stage and will not be widely used temporarily. In this case, bone tissue engineering represented by co-transplantation of bone endothelial cells and bone marrow mesenchymal stem cells (BMSCs) may be another feasible therapeutic strategy.

Role of Endothelial Glucocorticoid Receptor in the Pathogenesis of Kidney Diseases

Glucocorticoids, as multifunctional hormones, are widely used in the treatment of various diseases including nephrological disorders. They are known to affect immunological cells, effectively treating many autoimmune and inflammatory processes. Furthermore, there is a growing body of evidence demonstrating the potent role of glucocorticoids in non-immune cells such as podocytes. Moreover, novel data show additional pathways and processes affected by glucocorticoids, such as the Wnt pathway or autophagy. The endothelium is currently considered as a key organ in the regulation of numerous kidney functions such as glomerular filtration, vascular tone and the regulation of inflammation and coagulation. In this review, we analyse the literature concerning the effects of endothelial glucocorticoid receptor signalling on kidney function in health and disease, with special focus on hypertension, diabetic kidney disease, glomerulopathies and chronic kidney disease. Recent studies demonstrate the potential role of endothelial GR in the prevention of fibrosis of kidney tissue and cell metabolism through Wnt pathways, which could have a protective effect against disease progression. Another important aspect covered in this review is blood pressure regulation though GR and eNOS. We also briefly cover potential therapies that might affect the endothelial glucocorticoid receptor and its possible clinical implications, with special interest in selective or local GR stimulation and potential mitigation of GC treatment side effects.

Osteonecrosis in systemic lupus erythematosus: Systematic insight from the epidemiology, pathogenesis, diagnosis and management

Osteonecrosis (ON) is one of the serious and well recognized complicationscausing severe pain and disability in patients with systemic lupus erythematosus (SLE), and its manifestation and pathogenesis are only partially understood. This review provide an update of the recent progress in etiology, pathogenesis, diagnosis, and treatment of systemic lupus erythematosus related osteonecrosis (SLE-ON). Despite the concomitant use of corticosteroids, alcohol and obesity, the dysregulated immune micro-environment and the complex pathogenesis of SLE synergistically play important roles in the development of ON. Osteonecrosis of femoral head (ONFH) is the most often involved joint in SLE. The current classification and staging system of ONFH is based on imaging techniques, particularly relating to MRI and CT, for the identification and quantification of necrotic lesions. For SLE-ONFH patients, both SLE specific clinical symptoms and ONFH imaging findings should be comprehensively evaluated. Even though advances concerning bone grafting and arthroplasty procedures have resulted in improved clinical outcomes, early pharmacological treatment at the pre-collapse stage may prevent joint collapse and reduce the joint arthroplasty rate, and this needs to be accounted. Although some progress has been made, considerably more research is needed before we fully understand SLE-ONFH. Future treatments of SLE-ONFH may involve genetic or cell-based therapies that target potential biomarkers, and this will lead to effective measures for saving thefunction of hip joint and preventing osteonecrosis.

[Spontaneous fibrinolysis and possibilities of its acceleration in pulmonary embolism]

This review contains the data concerning the mechanisms of spontaneous fibrinolysis in pulmonary vessels and possibilities of its acceleration in pulmonary embolism. The spontaneous fibrinolysis system is known to be sequential and multifactorial, with the interaction of accelerators (t-PA and u-PA) and inhibitors (alpha-2-antiplasmin, PAI-1, TAFI). The fibrinolytic processes take place in case of prevailing reactions of accelerating factors over inhibiting ones. The endothelium of pulmonary vessels possesses pronounced antithrombogenic and profibrinolytic properties, therefore, the processes of fibrinolysis in the pulmonary vascular bed normally occur more intensively than in the vessels of the systemic circulation. The membrane proteins of the endothelium annexins A2 activate plasminogen, whereas thrombomodulin inhibits the activity of PAI-1. The main approaches to increase the fibrinolysis intensity in conditions of pulmonary embolism may be aimed at elevating the activity of fibrinolytic enzymes (enhancing the synthesis of annexins A2, the use of NMDA-receptor antagonists) and suppressing its inhibitors (the use of monoclonal antibodies to alpha-2-antiplasmin, as well as plasminogen activator inhibitor-1 (PAI-1) and thrombin-activatable fibrinolysis inhibitor (TAFI). Promising directions for future research can be the synthesis of a new generation of tissue-type plasminogen activators, and investigations of the possibility of clinical application of antithrombin and thrombomodulin, angiotensin converting enzyme inhibitors and cortisol antagonists. To meet these challenges, it is necessary to develop new models of venous thrombosis and acute pulmonary embolism in different animal species, with the assessment of the changes in the venous haemodynamics and pulmonary microcirculation on the background of administration of a new class of fibrinolytic agents.