Role of Lipid Rafts on LRP8 Signaling Triggered by Anti-β2-GPI Antibodies in Endothelial Cells

S-hydroxychloroquine prevents the antiphospholipid thrombogenic complexes for antiphospholipid syndrome treatment

Clinically used in systemic lupus erythematosus (SLE), Hydroxychloroquine (HCQ) exerts antithrombotic effects by inhibiting anti-β2-glycoprotein I (anti-β2GPI) antibody binding to phospholipid bilayers. However, HCQ is a racemic mixture, with only one enantiomer offering therapeutic benefits, while the other may contribute to toxicity. The current study evaluated the thromboprophylactic efficacy of R-enantiomer Hydroxychloroquine (R-HCQ), S-enantiomer Hydroxychloroquine (S-HCQ), and racemic HCQ (Rac-HCQ), with a focus on their impact on APS-associated markers. Both in vitro and in vivo models were employed, with human umbilical vein endothelial cells (HUVECs) and mice immunized with human β2-glycoprotein I antibodies used to evaluate the formation of antiphospholipid thrombotic complexes and their modulation by HCQ enantiomers. S-HCQ significantly reduced β2GPI complex binding and restored the AnxA5 anticoagulant shield in vitro, demonstrating superior efficacy over R-HCQ in disrupting β2GPI/anti-β2GPI interactions and preventing endothelial dysfunction in APS models. Pretreatment of HUVECs with S-HCQ significantly attenuated the expression of proinflammatory cytokines (tumor necrosis factor-alpha, interleukin-6, interleukin-1 beta, and C-C motif ligand 2) and endothelial activation markers (intercellular adhesion molecule 1, vascular cell adhesion molecule 1, and E-selectin). S-HCQ alleviates endothelial dysfunction by reducing proinflammatory cytokines, endothelial activation markers, and NO production while downregulating iNOS expression, highlighting its potential to mitigate oxidative stress and thrombogenic activity in APS-related endothelial damage. In vivo, S-HCQ effectively reduced clot formation in the femoral veins of APS mouse models. Among the HCQ enantiomers tested, S-HCQ demonstrated superior efficacy in modulating inflammatory and angiogenic pathways, influencing the formation of antiphospholipid thrombotic complexes and mitigating thrombosis. These findings underscore the potential of S-HCQ as a therapeutic alternative for APS management.

Mechanism of antiphospholipid antibody-mediated thrombosis in antiphospholipid syndrome

Antiphospholipid syndrome (APS) is an autoimmune disease characterized by the occurrence of thrombotic or obstetrical events in patients with persistent antiphospholipid antibodies (aPL). Thrombotic events, the primary pathological hallmarks and clinical manifestations, are among the leading causes of mortality in APS. Our understanding of the mechanism underlying APS-related thrombosis has significantly advanced in recent years. The presence of aPL, particularly anti-β2-glycoprotein I (anti-β2GPI) antibodies, is a major driver of thrombosis. The proposed pathophysiological mechanisms of aPL-mediated pro-thrombotic events can be broadly categorized into three types: disruption of anticoagulant reactions and fibrinolysis, interference with coagulation cascade cells, and complement activation. A triggering 'second hit' is typically necessary to initiate thrombosis. The development of animal models of APS has further refined our understanding of the role of aPL in thrombosis. In this review, we focused on the role of β2GPI-dependent aPL in thrombosis of thrombotic APS.

Impact of statin therapy on CD40:CD40L signaling: mechanistic insights and therapeutic opportunities

Statins are widely utilized to reduce cholesterol levels, particularly in cardiovascular diseases. They interface with cholesterol synthesis by inhibiting the 3-hydroxy-3-methylglutaryl coenzyme-A (HMG-CoA) reductase enzyme. Besides their primary effect, statins demonstrate anti-inflammatory and immune-modulating properties in various diseases, highlighting the pleiotropic effect of these drugs. The CD40:CD40L signaling pathway is considered a prominent inflammatory pathway in multiple diseases, including autoimmune, inflammatory, and cardiovascular diseases. The findings from clinical trials and in vitro and in vivo studies suggest the potential anti-inflammatory effect of statins in modulating the CD40 signaling pathway and downstream inflammatory mediator. Accordingly, as its classic ligand, statins can suppress immune responses in autoimmune diseases by inhibiting CD40 expression and blocking its interaction with CD40L. Additionally, statins affect intracellular signaling and inhibit inflammatory mediator secretion in chronic inflammatory diseases like asthma and autoimmune disorders such as myasthenia gravis, multiple sclerosis, systemic lupus erymanthus, and cardiovascular diseases like atherosclerosis. However, it is essential to note that the anti-inflammatory effect of statins may vary depending on the specific type of statin used. In this study, we aim to explore the potential anti-inflammatory effects of statins in treating inflammatory diseases by examining their role in regulating immune responses, particularly their impact on the CD40:CD40L signaling pathway, through a comprehensive review of existing literature.

Identification of quality markers and mechanisms of Anzi Tiaochong Fang in the treatment of antiphospholipid syndrome-related recurrent pregnancy loss: chemical analysis, network pharmacology, and in vitro approaches

INTRODUCTION

Anzi Tiaochong Fang (ATF) is a traditional Chinese medicine (TCM) Fangji widely used to treat antiphospholipid syndrome-related recurrent pregnancy loss (APS-RPL). This study aimed to identify the quality markers and elucidate the mechanisms of ATF in treating APS-RPL.

METHODS

Chemical, network pharmacology, and in vitro verification were employed to identify quality markers and mechanisms of ATF. HPLC-MS/MS was used to identify and quantify ATF compounds. APS-RPL targets were identified using databases such as HERB, similarity ensemble approach, PharmMapper, Swiss Target Prediction, Gene Expression Omnibus, Genecards, and DisGeNET. GO and Reactome analyses were conducted using KOBAS-i. In vitro verification was performed using CCK-8, FDA staining, and ELISA.

RESULTS

This study identified 23 compounds and 942 targets, including 132 APS-RPL targets and 42 targets between ATF and APS-RPL. GO analysis demonstrated significant enrichment in cytokine-mediated signaling pathway, positive regulation of angiogenesis, response to hypoxia, inflammatory response, and platelet degranulation. Reactome analysis indicated significant enrichment in Immune System, Cytokine Signaling in the Immune system, Signaling by Interleukins, Platelet activation, signaling and aggregation, and Signaling by VEGF. Core targets identified included VEGFA, ALB, TNF, IL-6, and STAT3, with liquiritigenin, nobiletin, ginsenoside Rb1, and astragalin identified as quality markers. In vitro experiments demonstrated that ATF promoted HTR-8/SVneo cell viability, significantly reduced TNF-α and IL-1β levels, and upregulated IL-6.

CONCLUSIONS

These findings contribute to the identification and quantification of potential quality markers and elucidate the molecular mechanisms of ATF, thereby supporting its therapeutic potential in the treatment of APS-RPL.

A Microflow Chip Technique for Monitoring Platelets in Late Pregnancy: A Possible Risk Factor for Thrombosis

Purpose

To study the platelet adhesion and aggregation behaviour of late pregnancy women under arterial shear rate using microfluidic chip technology and evaluate the risk of thrombosis in late pregnancy.

Methods

We included pregnant women who were registered in the obstetrics department of our hospital between January 2021 and October 2022 and underwent regular prenatal examinations. Blood samples were collected at 32-35 weeks of gestation for routine blood tests and progesterone, oestradiol, and platelet aggregation function. A microfluidic chip was used to construct an in vitro stenosis vascular model to explore the platelet reactivity at shear rates of 1000s-1, 1500s-1 and 4000s-1. Flow cytometry was used to analyse the effect of shear rate induction on the expression of platelet membrane surface fibrin receptor (PAC-1) and P-selectin (CD62P) in pregnant women.

Results

Compared to the non-pregnant healthy control group, the white blood cell count increased and platelet count decreased significantly in late pregnant women (P < 0.05), and platelet reactivity to agonists increased under non-flow conditions (adhesion and aggregation rates, P < 0.05). Microfluidic chip technology showed that platelet aggregation in late pregnant women increased significantly (P < 0.05) in the shear-rate environment and was positively correlated with the shear rate. The degree of aggregation at 4000s-1 was more evident, but the stability of platelet aggregates was low. Shear rate increased PAC-1 and CD62P expression.

Conclusion

Microfluidic chip technology was used to analyse the platelet aggregation function under arterial shear rate combined with flow cytometry to detect platelet activation, which was consistent with the traditional non-flow conditions used to evaluate platelet function. However, microfluidic technology can simulate a more realistic in vivo shear rate environment, providing more effective clinical application data and a theoretical basis for the diagnosis and prevention of platelet dysfunction and thrombotic diseases during pregnancy.

Beneficial effects of rapamycin on endothelial function in systemic lupus erythematosus

Introduction

Endothelial function is significantly impaired in patients with SLE compared to healthy controls. Elevated activation of the mammalian target of rapamycin complex 1 (mTORC1) is reported in humans and mice with SLE. However, it is unclear if elevated mTORC1 in SLE contributes to impaired mitophagy and endothelial dysfunction. Therefore, we tested the hypothesis that inhibiting mTORC1 with rapamycin would increase mitophagy and attenuate endothelial dysfunction and inflammatory responses in SLE.

Methods

Nine-week-old female lupus-prone (MRL/lpr) and healthy control (MRL/MpJ) mice were randomly assigned into rapamycin treatment (lpr_Rapamycin and MpJ_Rapamycin) or control (lpr_Control and MpJ_Control) groups. Rapamycin was injected i.p. 3 days per week for 8 weeks. After 8 weeks, endothelium-dependent vasorelaxation to acetylcholine (ACh) and endothelium-independent vasorelaxation to sodium nitroprusside (SNP) were measured in thoracic aortas using a wire myograph.

Results

MTORC1 activity was increased in aorta from lpr mice as demonstrated by increased phosphorylation of s6rp and p70s6k and significantly inhibited by rapamycin (s6rp, p < 0.0001, p70s6k, p = 0.04, respectively). Maximal responses to Ach were significantly impaired in lpr_Control (51.7% ± 6.6%) compared to MpJ_Control (86.7% ± 3.6%) (p < 0.0001). Rapamycin prevented endothelial dysfunction in the thoracic aorta from lupus mice (lpr_Rapamycin) (79.6% ± 4.2%) compared to lpr_Control (p = 0.002). Maximal responses to SNP were not different across groups. Phosphorylation of endothelial nitric oxide synthase also was 42% lower in lpr_Control than MpJ_Control and 46% higher in lpr_Rapamycin than lpr_Control. The inflammatory marker, vascular cell adhesion protein 1 (Vcam 1), was elevated in aorta from lupus mice compared with healthy mice (p = 0.001), and significantly reduced with Rapamycin treatment (p = 0.0021). Mitophagy markers were higher in lupus mice and reduced by rapamycin treatment, suggesting altered mitophagy in lpr mice.

Conclusion

Collectively, these results demonstrate the beneficial effects of inhibiting mTORC1 on endothelial function in SLE mice and suggest inflammation and altered mitophagy contribute to endothelial dysfunction in SLE.

Interaction of antiphospholipid antibodies with endothelial cells in antiphospholipid syndrome

Antiphospholipid syndrome (APS) is an autoimmune disease with arteriovenous thrombosis and recurrent miscarriages as the main clinical manifestations. Due to the complexity of its mechanisms and the diversity of its manifestations, its diagnosis and treatment remain challenging issues. Antiphospholipid antibodies (aPL) not only serve as crucial "biomarkers" in diagnosing APS but also act as the "culprits" of the disease. Endothelial cells (ECs), as one of the core target cells of aPL, bridge the gap between the molecular level of these antibodies and the tissue and organ level of pathological changes. A more in-depth exploration of the relationship between ECs and the pathogenesis of APS holds the potential for significant advancements in the precise diagnosis, classification, and therapy of APS. Many researchers have highlighted the vital involvement of ECs in APS and the underlying mechanisms governing their functionality. Through extensive in vitro and in vivo experiments, they have identified multiple aPL receptors on the EC membrane and various intracellular pathways. This article furnishes a comprehensive overview and summary of these receptors and signaling pathways, offering prospective targets for APS therapy.

Safety of Anti-Reelin Therapeutic Approaches for Chronic Inflammatory Diseases

Reelin, a large extracellular glycoprotein, plays critical roles in neuronal development and synaptic plasticity in the central nervous system (CNS). Recent studies have revealed non-neuronal functions of plasma Reelin in inflammation by promoting endothelial-leukocyte adhesion through its canonical pathway in endothelial cells (via ApoER2 acting on NF-κB), as well as in vascular tone regulation and thrombosis. In this study, we have investigated the safety and efficacy of selectively depleting plasma Reelin as a potential therapeutic strategy for chronic inflammatory diseases. We found that Reelin expression remains stable throughout adulthood and that peripheral anti-Reelin antibody treatment with CR-50 efficiently depletes plasma Reelin without affecting its levels or functionality within the CNS. Notably, this approach preserves essential neuronal functions and synaptic plasticity. Furthermore, in mice induced with experimental autoimmune encephalomyelitis (EAE), selective modulation of endothelial responses by anti-Reelin antibodies reduces pathological leukocyte infiltration without completely abolishing diapedesis. Finally, long-term Reelin depletion under metabolic stress induced by a Western diet did not negatively impact the heart, kidney, or liver, suggesting a favorable safety profile. These findings underscore the promising role of peripheral anti-Reelin therapeutic strategies for autoimmune diseases and conditions where endothelial function is compromised, offering a novel approach that may avoid the immunosuppressive side effects associated with conventional anti-inflammatory therapies.