sirolimus and Antiphospholipid-Syndrome

Antiphospholipid antibodies are a heterogeneous group of autoantibodies that have clear associations with thrombosis and pregnancy morbidity, and which together constitute the 'antiphospholipid syndrome' (APS). However, the pathophysiology of these complications is not well understood and their heterogeneity suggests that more than one pathogenic process may be involved. Diagnosis remains a combination of laboratory analysis and clinical observation but there have been significant advances in identifying specific pathogenic features, such as domain I-specific anti-β2-glycoprotein-I antibodies. This in turn has pointed to endothelial and complement activation as important factors in the pathogenesis of APS. Consequently, although anticoagulation remains the standard treatment for thrombotic APS and during pregnancy, the realisation that these additional pathways are involved in the pathogenesis of APS has significant implications for treatment: agents acting outside the coagulation system, such as hydroxychloroquine for pregnancy complications and sirolimus as an inhibitor of the mammalian target of rapamycin (mTOR) pathway, are now under evaluation and represent a radical change in thinking for haematologists. Conventional anticoagulation is also under challenge from new, direct acting anticoagulants. This review will provide a comprehensive overview of the evolving understanding of APS pathogenesis and how this and novel therapeutics will alter diagnosis and management.

Topics: Anticoagulants; Antiphospholipid Syndrome; Autoantibodies; beta 2-Glycoprotein I; Complement Inactivator Proteins; Enzyme Inhibitors; Female; Forecasting; Humans; Hydroxychloroquine; Hydroxymethylglutaryl-CoA Reductase Inhibitors; Immunosuppressive Agents; Pregnancy; Pregnancy Complications; Rituximab; Sirolimus; Thrombosis

Catastrophic antiphospholipid syndrome (CAPS) is a potentially lethal disease that presents with rapidly progressive multiple organ thromboses. Anticoagulation, corticosteroids, intravenous immunoglobulin, and plasma exchange are the most commonly used treatments for CAPS patients. However, the high mortality despite these medications necessitates new treatment strategies. Following a brief review of current diagnostic and management strategies, we discuss the candidate therapies, i.e., hydroxychloroquine, rituximab, eculizumab, sirolimus, and defibrotide, that can be considered in CAPS patients refractory to traditional treatment.

Topics: Antibodies, Monoclonal, Humanized; Antiphospholipid Syndrome; Antirheumatic Agents; Catastrophic Illness; Humans; Hydroxychloroquine; Immunosuppressive Agents; Patient Care Team; Plasma Exchange; Platelet Aggregation Inhibitors; Polydeoxyribonucleotides; Rituximab; Sirolimus

This article summarizes the recent developments in the recognition and management of antiphospholipid syndrome (APS).. Five Task Forces, created as part of the 14th International Congress on antiphospholipid antibodies (aPL), published their systematic reviews. 'For the recognition of APS': the assessment of aPL profile is crucial for risk stratification; lupus anticoagulant positivity, especially in the context of 'triple aPL positivity' displays the highest risk; a panel of criteria and noncriteria aPL tests may help better risk-stratify the aPL-positive in the future. 'For the management of APS': direct oral anticoagulants are not currently recommended; statins ameliorate the proinflammator/thrombotic markers, whereas hydroxychloroquine reduces the risk of thrombosis in experimental models and lupus patients, which justify their use as an adjunctive treatment in refractory cases; B-cell inhibition may have a role in difficult-to-treat patients with hematologic and microthrombotic/angiopathic manifestations; and complement and mammalian targets of rapamycin complex pathway inhibition are promising targets in APS.. Warfarin, heparin, and/or antiplatelet drugs are the standard of care for aPL-positive patients. Recent studies suggest novel approaches that target new coagulation and immunomodulatory pathways; mechanistic and/or controlled clinical studies are needed to determine the effectiveness of these novel approaches.

Topics: Anti-Inflammatory Agents; Antibodies, Monoclonal; Antibodies, Monoclonal, Humanized; Anticoagulants; Antiphospholipid Syndrome; Humans; Hydrochlorothiazide; Hydroxymethylglutaryl-CoA Reductase Inhibitors; Platelet Aggregation Inhibitors; Rituximab; Sirolimus; Thrombosis

In antiphospholipid antibody (aPL) nephropathy, activation of the mammalian target of rapamycin (mTOR) contributes to endothelial cell proliferation, a key finding of aPL microvascular disease. Here, we examined mTOR activation in the skin of aPL-positive patients with livedo.. Three patient groups with livedo were studied: (1) persistently aPL-positive with systemic lupus erythematosus (SLE); (2) persistently aPL-positive without SLE; and (3) aPL-negative SLE (control). After collecting aPL-related medical history, two 5-mm skin biopsies of livedo were performed on each patient: (1) peripheral (erythematous-violaceous lesion); and (2) central (nonviolaceous area). We stained specimens for phosphorylated protein kinase B (p-AKT) and phosphorylated S6 ribosomal protein (p-S6RP) as mTOR activity markers, CD31 to identify endothelial cells, and Ki-67 to show cellular proliferation. We counted cells in the epidermis and compared mTOR-positive cell counts between peripheral and central samples, and between patient groups, using Freidman test and Wilcoxon signed-rank test.. Ten patients with livedo reticularis were enrolled: 4 aPL-positive without SLE (antiphospholipid syndrome [APS] classification met, n = 3), 4 aPL-positive SLE (APS classification met, n = 3), and 2 aPL-negative SLE (control). In all aPL-positive patients, epidermal p-AKT and p-S6RP staining were significantly increased in both peripheral and central skin samples when compared to aPL-negative SLE controls; both were more pronounced in the lower basal layers of epidermis.. Our study demonstrates increased mTOR activity in livedoid lesions of aPL-positive patients with or without SLE compared to aPL-negative patients with SLE, with more prominent activity in the lower basal layers of the epidermis. These findings may serve as a basis for further investigating the mTOR pathway in aPL-positive patients.

Topics: Antibodies, Antiphospholipid; Antiphospholipid Syndrome; Endothelial Cells; Humans; Ki-67 Antigen; Livedo Reticularis; Lupus Erythematosus, Systemic; Proto-Oncogene Proteins c-akt; Ribosomal Proteins; Sirolimus; TOR Serine-Threonine Kinases

Despite optimal anticoagulation and blood pressure control, patients with antiphospholipid syndrome (APS) nephropathy frequently progress to kidney failure, and recurrence after transplantation is common. The mTORC (mechanistic target of rapamycin complex) pathway was recently identified as a potential intermediate and a therapeutic target in vascular lesions associated with APS nephropathy. However, these results were derived from the retrospective analysis of a small cohort of patients receiving sirolimus after kidney transplantation. Therefore, they warranted external validation and the demonstration of the potential benefit of sirolimus in native kidney APS nephropathy. We report a patient with active APS nephropathy lesions occurring on native kidneys, in which endothelial mTORC activation was substantiated at the molecular level. Treatment with sirolimus was shown on a repeat kidney biopsy to successfully inhibit the AKT/mTORC pathway and was associated with significant improvement in kidney function and lesions of vasculopathy. Drug tolerance was excellent during the entire follow-up. This case validates and extends previous observations in kidney transplant recipients and demonstrates that endothelial activation of the AKT/mTORC pathway occurs in the damaged renal vasculature of native kidneys in APS nephropathy. These findings further support the potential of precision medicine and the use of mTORC activation as a biomarker of disease activity and as therapeutic target in patients with APS nephropathy.

Topics: Adult; Angiotensin-Converting Enzyme Inhibitors; Anticoagulants; Antiphospholipid Syndrome; Female; Humans; Immunosuppressive Agents; Mechanistic Target of Rapamycin Complex 1; Mechanistic Target of Rapamycin Complex 2; Microscopy, Confocal; Proto-Oncogene Proteins c-akt; Ramipril; Renal Insufficiency, Chronic; Ribosomal Protein S6; Signal Transduction; Sirolimus; Thrombotic Microangiopathies; TOR Serine-Threonine Kinases; Treatment Outcome

RapaLink-1 is a third generation mammalian target of rapamycin (mTOR) inhibitor and displays superior inhibitory effect on mTOR complex 1 (mTORC1). mTOR pathway is known to block autophagy and inhibition of it can protect thrombosis-related diseases including atherosclerosis, antiphospholipid syndrome (APS) and stroke. The objective of this study was to investigate whether RapaLink-1 could exert anti-thrombotic effects on APS via improving autophagy.. BALB/c mice were injected with monoclonal anti-beta-2-GPI (β2GPI) antibodies to induce APS in vivo, and anti-β2GPI antibodies together with anticardiolipin (aCL) antibodies in mice serum were assessed. The aortas of mice were isolated, and oil red and haematoxylin and eosin (HE) staining were used for thrombus morphology. The levels of LC3B and CD68 were quantified. Human monocyte cell line THP-1 was stimulated with oxidized low-density lipoprotein (ox-LDL) and treated with RapaLink-1 in vitro. The cell viability, LDH activity, apoptosis rate and rate of fate-positive cells were detected. LC3 expression was quantified by immunofluorescence. Western blot was utilized to assess the protein expression of LC3-І, LC3-П, Beclin-1 and p62.. The size of arterial thrombus plaque together with the level of anti-β2GPI antibodies and aCL was reduced by RapaLink-1. Immunostaining protocols confirmed that the application of RapaLink-1 inhibited plaque initiation and progression while decreased the extent of macrophage infiltration and enhanced the autophagy process. In vitro cultured THP-1 macrophages exposed to ox-LDL study showed that RapaLink-1 prevented cell apoptosis and enhanced autophagy of macrophages, indicated by the increasing expression of autophagy-related protein and morphological character under electron microscopy.. Our results revealed that Rapalink-1 has a potential to inhibit the formation of thrombus plaque in APS and these effects were dependent on facilitating cell autophagy both in vivo and in vitro.

Topics: Animals; Antiphospholipid Syndrome; Autophagy; Cell Line; Humans; Macrophages; Male; Mice, Inbred BALB C; Protein Kinase Inhibitors; Sirolimus; Thrombosis; TOR Serine-Threonine Kinases

Topics: Adult; Antiphospholipid Syndrome; Coronary Disease; Humans; Male; Microcirculation; Signal Transduction; Sirolimus; TOR Serine-Threonine Kinases

Antiphospholipid antibodies (aPL) have been reported to activate platelets. This is considered to be one of the pathogenic properties of aPL. Even though aPL heterogeneity is quite well established, little is known, if the ability to activate platelets is common to all aPL or depends on antigen specificity. To further study this issue, we analyzed the ability of three human monoclonal aPL with distinctly different antigenic specificities to activate platelets in vitro. The results obtained with human monoclonal aPL were validated with immunoglobulin G (IgG) fractions obtained from patients with antiphospholipid syndrome (APS). A co-factor-independent human monoclonal anticardiolipin aPL had no discernible effect on human platelets. Two monoclonal aPL reactive against β2 glycoprotein I (β2GPI) induced platelet aggregation, integrin αIIbβ3 activation and P-selectin surface expression. These data could be confirmed with patient IgG fractions which could only induce aggregation, if they had anti-β2GPI activity. Anti-β2GPI aPL-induced platelet activation depended on interaction of aPL with the low affinity Fcγ-receptor IIa on the platelet surface. It was completely abolished by pretreatment of platelet-rich plasma with the mechanistic target of rapamycin (mTOR) inhibitors rapamycin or everolimus. This extends previous data showing that mTOR is involved in signaling of anti-β2GPI in monocytes and endothelial cells. In conclusion, anti-β2GPI aPL activate platelets while co-factor-independent anticardiolipin aPL have no effect. mTOR is involved in this signaling process which has implications beyond APS, because so far the role of mTOR signaling in platelets is incompletely explored and requires further study.

Topics: Antibodies, Antiphospholipid; Antiphospholipid Syndrome; Autoantibodies; beta 2-Glycoprotein I; Blood Platelets; Cells, Cultured; Epitopes; Epitopes, B-Lymphocyte; Everolimus; Humans; Platelet Aggregation; Platelet Glycoprotein GPIIb-IIIa Complex; Signal Transduction; Sirolimus; TOR Serine-Threonine Kinases

Topics: Angioplasty, Balloon, Coronary; Antiphospholipid Syndrome; Coronary Angiography; Coronary Restenosis; Coronary Vessels; Drug-Eluting Stents; Female; Humans; Immunosuppressive Agents; Middle Aged; Myocardial Infarction; Reoperation; Sirolimus; TOR Serine-Threonine Kinases; Treatment Outcome

Although thrombosis is considered the cardinal feature of the antiphospholipid syndrome, chronic vascular lesions are common, particularly in patients with life-threatening complications. In patients who require transplantation, vascular lesions often recur. The molecular pathways involved in the vasculopathy of the antiphospholipid syndrome are unknown, and adequate therapies are lacking.. We used double immunostaining to evaluate pathway activation in the mammalian target of rapamycin complex (mTORC) and the nature of cell proliferation in the vessels of patients with primary or secondary antiphospholipid syndrome nephropathy. We also evaluated autopsy specimens from persons who had catastrophic antiphospholipid syndrome. The molecular pathways through which antiphospholipid antibodies modulate the mTORC pathway were evaluated in vitro, and potential pharmacologic inhibitors were also tested in vitro. Finally, we studied the effect of sirolimus in kidney-transplant recipients with the antiphospholipid syndrome.. The vascular endothelium of proliferating intrarenal vessels from patients with antiphospholipid syndrome nephropathy showed indications of activation of the mTORC pathway. In cultured vascular endothelial cells, IgG antibodies from patients with the antiphospholipid syndrome stimulated mTORC through the phosphatidylinositol 3-kinase (PI3K)-AKT pathway. Patients with antiphospholipid syndrome nephropathy who required transplantation and were receiving sirolimus had no recurrence of vascular lesions and had decreased vascular proliferation on biopsy as compared with patients with antiphospholipid antibodies who were not receiving sirolimus. Among 10 patients treated with sirolimus, 7 (70%) had a functioning renal allograft 144 months after transplantation versus 3 of 27 untreated patients (11%). Activation of mTORC was also found in the vessels of autopsy specimens from patients with catastrophic antiphospholipid syndrome.. Our results suggest that the mTORC pathway is involved in the vascular lesions associated with the antiphospholipid syndrome. (Funded by INSERM and others.).

Topics: Adult; Analysis of Variance; Antibodies, Antiphospholipid; Antiphospholipid Syndrome; Autopsy; Cell Proliferation; Endothelium, Vascular; Female; Humans; Immunoglobulin G; Immunosuppressive Agents; Kidney; Kidney Diseases; Kidney Transplantation; Male; Metabolic Networks and Pathways; Middle Aged; Sirolimus; TOR Serine-Threonine Kinases

Topics: Antibodies, Antiphospholipid; Antiphospholipid Syndrome; Endothelium, Vascular; Female; Humans; Immunosuppressive Agents; Male; Sirolimus; TOR Serine-Threonine Kinases

Topics: Antibodies, Antiphospholipid; Antiphospholipid Syndrome; Endothelium, Vascular; Female; Humans; Immunosuppressive Agents; Male; Sirolimus; TOR Serine-Threonine Kinases

Topics: Antibodies, Antiphospholipid; Antiphospholipid Syndrome; Endothelium, Vascular; Female; Humans; Immunosuppressive Agents; Male; Sirolimus; TOR Serine-Threonine Kinases

Topics: Antibodies, Antiphospholipid; Antiphospholipid Syndrome; Endothelium, Vascular; Female; Humans; Immunosuppressive Agents; Male; Sirolimus; TOR Serine-Threonine Kinases

Topics: Antibodies, Antiphospholipid; Antiphospholipid Syndrome; Endothelium, Vascular; Female; Humans; Immunosuppressive Agents; Male; Sirolimus; TOR Serine-Threonine Kinases

Topics: Antibodies, Antiphospholipid; Antiphospholipid Syndrome; Endothelium, Vascular; Female; Humans; Immunosuppressive Agents; Male; Sirolimus; TOR Serine-Threonine Kinases

Topics: Antibodies, Antiphospholipid; Antiphospholipid Syndrome; Endothelium, Vascular; Female; Humans; Immunosuppressive Agents; Male; Sirolimus; TOR Serine-Threonine Kinases