Thrombotic microangiopathy and the antiphospholipid syndrome

Pregnancy as a susceptible state for thrombotic microangiopathies

Pregnancy and the postpartum period represent phases of heightened vulnerability to thrombotic microangiopathies (TMAs), as evidenced by distinct patterns of pregnancy-specific TMAs (e.g., preeclampsia, HELLP syndrome), as well as a higher incidence of nonspecific TMAs, such as thrombotic thrombocytopenic purpura or hemolytic uremic syndrome, during pregnancy. Significant strides have been taken in understanding the underlying mechanisms of these disorders in the past 40 years. This progress has involved the identification of pivotal factors contributing to TMAs, such as the complement system, ADAMTS13, and the soluble VEGF receptor Flt1. Regardless of the specific causal factor (which is not generally unique in relation to the usual multifactorial origin of TMAs), the endothelial cell stands as a central player in the pathophysiology of TMAs. Pregnancy has a major impact on the physiology of the endothelium. Besides to the development of placenta and its vascular consequences, pregnancy modifies the characteristics of the women's microvascular endothelium and tends to render it more prone to thrombosis. This review aims to delineate the distinct features of pregnancy-related TMAs and explore the contributing mechanisms that lead to this increased susceptibility, particularly influenced by the "gravid endothelium." Furthermore, we will discuss the potential contribution of histopathological studies in facilitating the etiological diagnosis of pregnancy-related TMAs.

Characteristics and risk factors of retinal vasculopathy in antiphospholipid syndrome

BACKGROUND

Retinal vasculopathy including retinal artery occlusion (RAO) or retinal vein occlusion (RVO) was recently found to occur more frequently in antiphospholipid syndrome (APS) patients than non-APS patients. This study aims to investigate the clinical manifestation and risk factors of retinal vasculopathy among APS patients.

METHODS

In this single-center prospective cohort study, we evaluated APS patients with or without retinal vasculopathy during 2018-2020 at Peking Union Medical College Hospital. Clinical variables were compared, and a logistical regression model was built to explore risk factors. Hierarchical cluster analysis using Euclidean distances was applied to identify clusters of variables.

RESULTS

A total of 310 APS patients (67.4% female, mean age 38.1 years) were included, of whom 18 (5.8%) were diagnosed with retinal vasculopathy (9 with RVO and 9 with RAO). No significant differences were found among most demographic characteristics, clinical manifestations, or antibody profiles. APS-related heart valve disease (odds ratio OR 13.66, 95% confidence interval CI 4.55-40.98), APS nephropathy (OR 12.77, 95% CI 4.04-40.35), and thrombocytopenia (OR 2.63, 95% CI 1.01-6.89) were predictive of retinal vasculopathy. APS-related heart valve disease and nephropathy were also found to be statistically significant predictors in multivariate logistical regression analysis. Non-criteria manifestations were aggregated with retinal vasculopathy from a cluster analysis of variables.

CONCLUSION

Patients with APS-related heart valve disease and nephropathy suffered a higher risk of retinal vasculopathy. The underlying mechanisms of aPL-associated retinal vasculopathy may involve thrombotic microangiopathy, leading to poor prognosis and therapeutic changes.

TAFRO Syndrome with Renal Thrombotic Microangiopathy: Insights into the Molecular Mechanism and Treatment Opportunities

TAFRO syndrome is an extremely rare form of idiopathic MCD, characterized by thrombocytopenia, anasarca, fever, reticulin fibrosis on bone marrow biopsy, and organomegaly. Like idiopathic MCD, renal involvement is also a common presentation in patients with TAFRO syndrome. Furthermore, membranoproliferative glomerulonephritis (MPGN)-like injury and thrombotic microangiopathy (TMA) are the most reported histopathologic findings of renal biopsy. Several molecular mechanisms have been previously postulated in order to explain the TAFRO syndrome symptoms, including abnormal production of interleukin-6 (IL-6), vascular endothelial growth factor (VEGF), etc. The role of these cytokines in renal injury, however, is not well understood. The aim of this review article is to summarize the latest knowledge of molecular mechanisms behind the TAFRO syndrome and their potential role in renal damage.

A Very Rare Case of Mass-Like Mesenteric Fat Necrosis in a Patient with Antiphospholipid Syndrome

Introduction

Intra-abdominal fat is a metabolically active tissue that can undergo necrosis due to torsion, infarction, or trauma. Despite being asymptomatic in most cases, fat necrosis or steatonecrosis can cause abdominal pain. Case.

Presentation

This article describes the case of a male patient admitted to the emergency department with diffuse abdominal pain for the past month. The patient had a past medical history of antiphospholipid syndrome with multiple venous thromboembolic events and one episode of lower limb vasculitis, currently under anticoagulation treatment. Imaging studies with computed tomography and magnetic resonance revealed a mesenteric mass-like lesion adjacent to the ileal bowel loops. The patient underwent surgical resection, and the microscopic analysis revealed extensive organizing fat necrosis with reactive panniculitis and hemorrhage.

Discussion and Conclusion

This article describes a rare case of a mesenteric mass-like encapsulated fat necrosis in a patient with antiphospholipid syndrome, with very atypical location and imaging features.

Update on the pathogenesis of central nervous system lupus

PROPOSE OF REVIEW

Neuropsychiatric systemic lupus erythematosus (NPSLE) is an emerging frontier in lupus care encompassing a wide spectrum of clinical manifestations. Its pathogenesis remains poorly understood because of the complexity of pathophysiologic mechanisms involved and limited access to tissue. We highlight recent advances in the pathophysiology of neuropsychiatric lupus.

RECENT FINDINGS

Disruption of blood-brain barrier (BBB) facilitating entrance of neurotoxic antibodies into the central nervous system (CNS), neuroinflammation and cerebral ischemia are the key mechanisms. Disruption of the BBB may occur not only at the traditional BBB, but also at the blood-cerebrospinal fluid barrier. Certain autoantibodies, such as anti-N-methyl-D-aspartate receptors, antiribosomal P and antiphospholipid antibodies may cause injury in subsets of patients with diffuse neuropsychiatric disease. Activation of microglia via autoantibodies, interferon-a or other immune reactants, may amplify the inflammatory response and promote neuronal damage. New inflammatory pathways, such as TWEAK/Fn14, Bruton's tyrosine kinase, Nogo-a and ACE may represent additional potential targets of therapy. Novel neuroimaging techniques suggest alterations in brain perfusion and metabolism, increased concentration of neurometabolites, indicative of glial activation, vasculopathy and neuronal impairment.

SUMMARY

NPSLE encompasses a diverse phenotype with distinct pathogenic mechanisms, which could be targeted by novel therapies or repositioning of existing drugs.

Approaches to Microthrombotic Wounds: A Review of Pathogenesis and Clinical Features

GENERAL PURPOSE

To discuss the pathogenesis and clinical features of wounds caused by microthrombi formation under the following categories of systemic diseases: cold-related and immune-complex deposition diseases, coagulopathies, abnormalities in red blood cell structure, emboli, and vasospasm.

TARGET AUDIENCE

This continuing education activity is intended for physicians, physician assistants, nurse practitioners, and nurses with an interest in skin and wound care.

LEARNING OBJECTIVES/OUTCOMES

After participating in this educational activity, the participant should be better able to:1. Recall the etiology, risk factors, and pathophysiology of the various types of microthrombotic wounds.2. Describe the clinical manifestations and treatment of the various types of microthrombotic wounds.

ABSTRACT

Typical wounds such as diabetic foot ulcers, venous leg ulcers, pressure ulcers, and arterial ulcers are responsible for more than 70% of chronic wounds. Atypical wounds have broad differential diagnoses and can sometimes develop as a combination of different conditions. Regardless of the etiology, impaired blood circulation is characteristic of all chronic and acute wounds. Chronic wounds associated with microthrombi formation are an important group of atypical wounds commonly linked to an underlying systemic disease. In this perspective article, the pathogenesis and clinical features of wounds caused by microthrombi formation are discussed under the following categories of systemic diseases: cold-related and immune-complex deposition diseases, coagulopathies, abnormalities in red blood cell structure, emboli, and vasospasm.

Clinical characteristics and risk factors of microvascular involvement in primary antiphospholipid syndrome: a longitudinal single-center study in China

OBJECTIVES

The objective of this study was to investigate risk factors of microvascular involvement and survival in Chinese patients with primary antiphospholipid syndrome.

METHODS

In this single-center, retrospective study, we enrolled 112 patients with a confirmed diagnosis of primary antiphospholipid syndrome who were admitted to Peking Union Medical College Hospital from January 2004 to December 2016. Demographic data, clinical characteristics, laboratory results, and follow-up records were collected.

RESULTS

A total of 112 patients with primary antiphospholipid syndrome were studied. Microvascular involvement was identified in 21 patients (18.75%). Patients with microvascular involvement experienced fewer episodes of arterial or venous thrombosis (28.6% vs. 84.6%) and a higher incidence of thrombocytopenia (85.7% vs. 54.9%), respectively. Low complement and elevated high-sensitivity CRP levels were observed more frequently in the microvascular group compared with the non-microvascular group (complement 38.1% vs. 18.7%; high-sensitivity CRP 71.4% vs. 31.9%, respectively). Anti-β2-glycoprotein I antibodies were more prevalent in patients with microvascular involvement than in patients without (66.7% vs. 33.0%, respectively). Multivariate logistic regression analysis revealed that thrombocytopenia (odds ratio = 4.523, 95% confidence interval 1.139-17.962), elevated high-sensitivity CRP levels (odds ratio = 6.385, 95% confidence interval 1.969-20.704), and anti-β2-glycoprotein I antibody positivity (odds ratio = 5.042, 95% confidence interval 1.555-16.352) were independent risk factors for microvascular involvement. A Kaplan-Meier analysis revealed that survival was significantly poorer in patients with microvascular involvement compared with patients without (p = 0.0278).

CONCLUSIONS

In addition to arterial and venous thrombosis, antiphospholipid syndrome can affect the microvasculature of select organs. It is thus important for clinicians to be aware that antiphospholipid syndrome-associated microvascular involvement has a unique pathogenesis and can be a life-threatening condition.

Alternative pathway activation due to low level of complement factor H in primary antiphospholipid syndrome

INTRODUCTION

Although complement activation has been proposed as a possible thrombophilic mechanism in antiphospholipid syndrome (APS), the origin of complement activation in APS remains unclear. Here, we focused on complement regulatory factors (CRF), which control the complement system to prevent damage to host tissue. We evaluated the function of two major CRF, membrane cofactor protein (MCP) and factor H (FH), in APS patients.

MATERIALS AND METHODS

In this study, we analyzed preserved serum samples from 27 patients with primary APS (PAPS), 20 with APS complicated with SLE (APS + SLE), 24 with SLE (SLE), and 25 with other connective tissue diseases (Other CTD). Serum MCP and FH levels were tested by ELISA. Autoantibodies against FH were determined by both ELISA and western-blotting.

RESULTS

Serum complement levels of PAPS were lower than those of other CTD (median C3: 82 vs 112 mg/dL, p < 0.01, C4: 15 vs 22 mg/dL, p < 0.05). Serum MCP levels did not significantly differ among the groups. Serum FH levels were significantly lower in PAPS patients compared with SLE or other CTD (median 204, 1275, and 1220 μg/mL, respectively, p < 0.01). In PAPS patients, serum FH levels were positively correlated with serum C3 levels (p < 0.01, R = 0.55), but no correlation was found with serum C4 levels (p = 0.22, R = 0.33). Autoantibodies against FH were not detected in any of our patients.

CONCLUSIONS

Activation of the alternative complement pathway due to low level of FH is one of the possible thrombophilic mechanisms in PAPS.

Thrombocytopenia in pregnancy

Thrombocytopenia develops in 5% to 10% of women during pregnancy or in the immediate postpartum period. A low platelet count is often an incidental feature, but it might also provide a biomarker of a coexisting systemic or gestational disorder and a potential reason for a maternal intervention or treatment that might pose harm to the fetus. This chapter reflects our approach to these issues with an emphasis on advances made over the past 5 to 10 years in understanding and managing the more common causes of thrombocytopenia in pregnancy. Recent trends in the management of immune thrombocytopenia translate into more women contemplating pregnancy while on treatment with thrombopoietin receptor agonists, rituximab, or mycophenylate, which pose known or unknown risks to the fetus. New criteria to diagnose preeclampsia, judicious reliance on measurement of ADAMTS13 to make management decisions in suspected thrombotic thrombocytopenic purpura, new evidence supporting the efficacy and safety of anticomplement therapy for atypical hemolytic uremic syndrome during pregnancy, and implications of thrombotic microangiopathies for subsequent pregnancies are evolving rapidly. The goals of the chapter are to help the hematology consultant work through the differential diagnosis of thrombocytopenia in pregnancy based on trimester of presentation, severity of thrombocytopenia, and coincident clinical and laboratory manifestations, and to provide guidance for dealing with some of the more common and difficult diagnostic and management decisions.

Thrombocytopenia in pregnancy

Thrombocytopenia develops in 5% to 10% of women during pregnancy or in the immediate postpartum period. A low platelet count is often an incidental feature, but it might also provide a biomarker of a coexisting systemic or gestational disorder and a potential reason for a maternal intervention or treatment that might pose harm to the fetus. This chapter reflects our approach to these issues with an emphasis on advances made over the past 5 to 10 years in understanding and managing the more common causes of thrombocytopenia in pregnancy. Recent trends in the management of immune thrombocytopenia translate into more women contemplating pregnancy while on treatment with thrombopoietin receptor agonists, rituximab, or mycophenylate, which pose known or unknown risks to the fetus. New criteria to diagnose preeclampsia, judicious reliance on measurement of ADAMTS13 to make management decisions in suspected thrombotic thrombocytopenic purpura, new evidence supporting the efficacy and safety of anticomplement therapy for atypical hemolytic uremic syndrome during pregnancy, and implications of thrombotic microangiopathies for subsequent pregnancies are evolving rapidly. The goals of the chapter are to help the hematology consultant work through the differential diagnosis of thrombocytopenia in pregnancy based on trimester of presentation, severity of thrombocytopenia, and coincident clinical and laboratory manifestations, and to provide guidance for dealing with some of the more common and difficult diagnostic and management decisions.

A 3-year follow-up of a patient with acute renal failure caused by thrombotic microangiopathy related to antiphospholipid syndrome: case report

Background Microvascular manifestations of antiphospholipid antibody syndrome in the kidneys include acute renal failure, thrombotic microangiopathy and hypertension. Therapy has been largely empiric. Case report A 49-year-old Chinese man presented with anuric acute renal failure without abundant proteinuria and heavy haematuria, but markedly low levels of urinary sodium, potassium and chlorine upon admission. On day 1 of hospitalization, his thrombocytopenia, anaemia and renal failure showed rapid progression. The presence of lupus anticoagulant and vascular ischaemia of the small vessels in renal arteriography were also observed. Anticoagulants, continuous renal replacement therapy, glucocorticoids and six sessions of plasma exchange were started. After the fourth plasma exchange (on day 20), his urine output increased and began to normalize. On day 25, haemodialysis was stopped and his general condition gradually improved. A renal biopsy was subsequently performed, and the histopathological diagnosis was thrombotic microangiopathy due to antiphospholipid antibody syndrome. A further 3-year follow-up showed that his haemoglobin level, platelet count and serum creatinine were within the normal range, with stable blood pressure. Conclusion Treatment modalities such as anticoagulation, immunosuppression and plasma exchange are likely to be necessary when severe acute renal failure combined with thrombotic microangiopathy present in nephropathy of antiphospholipid antibody syndrome.

Liver transplantation in a patient with primary antiphospholipid syndrome and Budd-Chiari syndrome

The antiphospholipid syndrome (APS) is an acquired thrombophilic disorder in which autoantibodies are produced to a variety of phospholipids determinants of cell membranes or phospholipid binding proteins. There are few reports about association between antiphospholipid antibodies and development of Budd-Chiari syndrome (BCS). We report the case of BCS development in young Russian male with primary APS. The patient underwent orthotopic liver transplantation on August 26, 2012. At present time his state is good, the blood flow in the liver restored and its function is not impaired. We report about the first time the successful use of dabigatran etexilate for prolonged anticoagulation therapy in APS patient with BCS. In addition patient is managed with immunosuppressive drugs.

Secondary hypertrophic pachymeningitis in antiphospholipid syndrome

This report describes a rare case of hypertrophic pachymeningitis secondary to antiphospholipid syndrome in a 37-year-old woman. The patient had a history of antiphospholipid syndrome and developed hypertrophic pachymeningitis subsequently. Pathological examination of the dura mater showed not only fibrous thickening, the typical finding of hypertrophic pachymeningitis, but also thrombosis in the dural microvessels and T cell infiltration without B cell or plasma cell infiltration, suggesting cell-mediated immunity. The dural thickening spontaneously improved and did not deteriorate during corticosteroid therapy. The histological findings and spontaneous remission observed in this case might be characteristic of secondary hypertrophic pachymeningitis with antiphospholipid syndrome. Further investigations are necessary to elucidate the pathophysiology of this novel type of hypertrophic pachymeningitis.