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A proteomic map of thromboinflammatory signatures in antiphospholipid syndrome: results from antiphospholipid syndrome alliance for clinical trials and international networking (APS ACTION) registry.

INTRODUCTION: Antiphospholipid syndrome (APS) is an autoimmune disease with thromboembolic and obstetric morbidity arising via a model of immunothrombosis. Individuals with APS may present with thrombotic (TAPS), obstetric (OAPS), or microvascular (MAPS) disease, while many have circulating antiphospholipid antibodies (aPL) without APS classification (NoAPS). Multiple pathophysiologic mechanisms have been proposed in APS, including activation by aPL of platelets, endothelial and immune cells, as well as complement and coagulation pathways; however, the pathophysiology of APS, particularly transition of clinical APS from aPL remains unclear. METHODS: Seeking to define the inflammatory signature of APS, we carried out an unbiased proteomic screen of persistently aPL-positive patients with different clinical phenotypes from the international APS Alliance for Clinical Trials and International Networking (ACTION) Registry and compared them to 10 healthy controls. 6398 unique proteins were estimated using an DNA aptamer-based assay. Subsequently, we validated our findings in 34 additional patients. RESULTS: Our data show that the mere presence of aPL confers a distinct thromboinflammatory signature characterized by the activation of coagulation, complement, innate and adaptive immune response pathways shared by all APS subtypes. Pathway enrichment analysis revealed increasing enrichment with rising statistical significance of thrombosis, complement, neutrophil and other innate and adaptive immune activation, as well as extracellular matrix (ECM) organization with increasing clinical severity, suggesting a model of progressive thromboinflammation in evolution of APS from NoAPS to TAPS and MAPS. CONCLUSIONS: Our findings provide novel insights into the pathogenesis of APS and identify potential novel targets for diagnostic and therapeutic intervention in APS across its entire spectrum.

Humans

Neutrophil extracellular traps induced by a monoclonal anti-phosphatidylserine/prothrombin antibody activate platelets in vitro.

Antiphospholipid syndrome (APS) is an autoimmune thrombotic disorder characterized by the presence of antiphospholipid antibodies, including anti-phosphatidylserine/prothrombin antibodies (aPS/PT). While neutrophil extracellular traps (NETs) are implicated in the pathogenesis of APS, the role of aPS/PT in NET induction and its contribution to thrombosis remain unclear. This study aimed to clarify the effects of NETs induced by a monoclonal aPS/PT antibody on platelet activation and their potential contribution to thrombo-inflammatory responses. NETs were induced by stimulating peripheral blood neutrophils from healthy donors with aPS/PT. Their morphology and platelet-activating capacity were compared with NETs induced by anti-neutrophil cytoplasmic antibodies (ANCAs). Proteomic analyses were conducted to comprehensively compare protein compositions of these NETs, and candidate proteins associated with platelet activation in aPS/PT-induced NETs were identified. Functional inhibition assays were then conducted to assess whether blocking these candidates would suppress aPS/PT-induced NET-mediated platelet activation. We found that binding of aPS/PT to neutrophils induced NET formation, with a larger and more fibrous morphology compared to ANCA-induced NETs. Platelets trapped in aPS/PT-induced NETs showed significantly higher activation compared to those trapped in ANCA-induced NETs. Proteomic analyses identified histone H3 as a potential mediator of platelet activation in aPS/PT-induced NETs. Correspondingly, plasma concentrations of H3.1 nucleosome were significantly higher in patients with APS than in healthy controls. Blockade of histone H3 using a neutralizing antibody significantly suppressed platelet activation mediated by aPS/PT-induced NETs. These findings suggest that aPS/PT-induced NETs contribute to platelet activation and may promote thrombo-inflammatory responses in APS. Targeting histone H3 within aPS/PT-induced NETs may provide a potential therapeutic strategy for thrombo-inflammatory processes in APS.

Humans

Autophagy in the Regulation of Placental Development: From Trophoblast Differentiation to Metabolic Stress Adaptation.

Successful pregnancy depends on precise placental development, where trophoblast differentiation, syncytialization, invasion, and adaptation to metabolic stress are critical. Autophagy, a lysosome-mediated degradation pathway, has emerged as an important regulator of cellular homeostasis, yet its integrated role in trophoblast fate and functions has not been comprehensively summarised. This review synthesises current evidence on autophagy's functions throughout placentation, from trophoblast differentiation to syncytialization and extravillous trophoblast invasion. We examine how autophagy enables cellular remodelling during differentiation, supports metabolic adaptation under hypoxia and nutrient stress, and maintains mitochondrial quality control through selective mitophagy. Autophagy is essential for syncytiotrophoblast formation via endoplasmic reticulum stress-coordinated activation and p53 downregulation. However, its effects on trophoblast invasion are context-dependent, influenced by oxygen tension, autophagic flux completeness, and differentiation state, which can potentially be shaped by parent-offspring genetic conflicts through genomic imprinting. Both excessive and insufficient autophagy contribute to pregnancy complications, including pre-eclampsia, foetal growth restriction, gestational diabetes mellitus, preterm birth, recurrent spontaneous abortion and obstetric antiphospholipid syndrome through distinct molecular mechanisms. Autophagy functions as a dynamically tuned homeostatic mechanism in placental development. Understanding condition-specific autophagy dysregulation is thereby crucial for improving pregnancy outcomes.

Autophagy

Ras-MAPK pathway in patients with lupus nephritis.

BACKGROUND: Pathogenic mutations in genes encoding components of the Ras/mitogen-activated protein kinase (Ras-MAPK) pathway cause RASopathy. Here, we describe five unrelated patients with SLE carrying mutations associated with RASopathy and investigate the activity of the Ras-MAPK pathway. METHODS: Pathogenic variants were identified by whole-exome/whole-genome sequencing. The activity of the Ras-MAPK pathway in peripheral blood mononuclear cells (PBMC) and kidneys was evaluated using RNA sequencing and datasets from the nephroseq database, respectively. RESULTS: Five (likely) pathogenic variants in four Ras-MAPK genes were identified, including NRAS: c.G38A: p.G13D; ARAF: c.C1435T: p.R479C; KRAS: c.T341C: p.V114A; PTPN11: c.G455A: p.R152H and NRAS: c.G34A: p.G12S. Kidney injury is the main feature, presenting with nephrotic syndrome (2/5), proteinuria and haematuria (2/5). Acute kidney injury and rapidly progressive nephritic syndrome were noted in one patient each. Other clinical features included mucocutaneous lesions (5/5), cardiac involvement (4/5) and arthralgia (3/5). Laboratory abnormalities included hypocomplementaemia (5/5), presence of antiphospholipid antibodies (4/5), decreased regulatory T cells (3/3), pancytopenia (3/5) and persistent monocytosis (2/5). Kidney biopsy revealed lupus nephritis. Most patients responded well to standard therapy, with the exception of the patient with the NRAS p.G13D mutation who died. The Ras-MAPK pathway was activated in both PBMC and kidney of patients with LN as indicated by increased expression of NRAS, KRAS, RIT1, MRAS, PPP1CB, SHOC2, SOS2 and MAP2K1, as well as decreased expression of negative regulators of the Ras-MAPK pathway, CBL, LZTR1 and NF1. CONCLUSION: Kidney involvement may be the main feature of the clinical spectrum of RASopathy. Genetic screening should be considered for patients with early onset lupus.

Humans