Eculizumab improves posttransplant thrombotic microangiopathy due to antiphospholipid syndrome recurrence but fails to prevent chronic vascular changes

Management of Cardiovascular Complications in Antiphospholipid Syndrome: A Narrative Review with a Focus on Older Adults

Antiphospholipid syndrome (APS), also known as Hughes syndrome, is an acquired autoimmune and procoagulant condition that predisposes individuals to recurrent thrombotic events and obstetric complications. Central is the role of three types of antiphospholipid antibodies that target phospholipid-binding proteins: lupus anticoagulant (LAC), anti-β2-glycoprotein I (β2-GPI-Ab), and anti-cardiolipin (aCL). Together with clinical data, these antibodies are the diagnostic standard. However, the diagnosis of APS in older adults may be challenging and, in the diagnostic workup of thromboembolic complications, it is an underestimated etiology. The therapeutic management of APS requires distinguishing two groups with differential risks of thromboembolic complications. The standard therapy is based on low-dose aspirin in the low-risk group and vitamin K antagonists in the high-risk group. The value of direct oral anticoagulants is currently controversial. The potential role of monoclonal antibodies is investigated. For example, rituximab is currently recommended in catastrophic antiphospholipid antibody syndrome. Research is ongoing on other monoclonal antibodies, such as daratumumab and obinutuzumab. This narrative review illustrates the pathophysiological mechanisms of APS, with a particular emphasis on cardiovascular complications and their impact in older adults. This article also highlights advancements in the diagnosis, risk stratification, and management of APS.

Rational use of eculizumab in secondary atypical hemolytic uremic syndrome

Background

Secondary atypical hemolytic uremic syndrome (secondary aHUS) is a heterogeneous group of thrombotic microangiopathies (TMA) associated with various underlying conditions. Unlike primary aHUS, there is still no hard evidence on the efficacy of complement blockade in secondary aHUS, since the two main series that investigated this subject showed discrepant results. Our work aims to reassess the efficacy of eculizumab in treating secondary aHUS.

Methods

Observational, retrospective, single-center study, in which we analyzed the hematological and renal evolution of 23 patients diagnosed with secondary aHUS who received treatment with eculizumab and compared them with a control cohort of 14 patients. Complete renal response was defined as the recovery of renal function before the event, partial renal response as a recovery of 50% of lost glomerular filtration rate, and hematological response as normalization of hemoglobin and platelets.

Results

We found no statistically significant differences in baseline characteristics or disease severity between both groups. After a median of 5 doses of eculizumab, the group of patients who received complement blockade presented a significant difference in renal response (complete in 52.3% of patients and partial in 23.8%) compared to the control cohort (complete response 14.3% and partial of 14.3%). Rates of hematological remission were similar in both groups (90.9% in the eculizumab cohort and 85.7% in the control cohort).

Conclusion

Early and short-term use of eculizumab in patients with secondary aHUS could be an effective and safe therapeutic option, assuring better renal recovery compared to patients who do not receive complement blockade.

Antiphospholipid Syndrome and Kidney Involvement

BACKGROUND

Antiphospholipid syndrome (APS) is an autoimmune disease characterized by the development of autoantibodies and the impairment of the coagulation system. Knowledge about this syndrome is increasing over time, but kidney involvement, especially APS nephropathy, still represents a challenge for physicians.

SUMMARY

A "two hit" model has been hypothesized to explain APS pathophysiology, and the role played by some factors, such as the complement system, is becoming more and more clear. From a clinical point of view, along with thrombosis in any site and/or obstetric morbidities, that are the hallmarks of APS, a constellation of several other clinical symptoms is related to APS. These symptoms alone are not sufficient to fulfill Sydney criteria for APS and this could potentially lead to omitting some diagnoses. The mainstay of management of APS is antithrombotic therapy, but there are expectations for new drugs that regulate the immune system. APS could affect the kidneys in many ways and among them, APS nephropathy is an intriguing entity that has been overlooked in recent years. Novel studies on APS nephropathy are lacking.

KEY MESSAGES

In this review, we discuss what we currently know about APS and its relationship with the kidney, with an eye toward the future perspectives. Multicenter studies on APS nephropathy are necessary in order to develop targeted therapies.

An update on the biologics for the treatment of antiphospholipid syndrome

Antiphospholipid syndrome (APS) is a systemic autoimmune disease characterized by thrombosis and pregnancy morbidity with the persistent presence of antiphospholipid antibodies (aPLs). Although anticoagulation is the primary treatment for APS, it fails in approximately 20-30% of obstetric APS cases and more than 30% of thrombotic APS cases. Therefore, there is a need for new, targeted treatments beyond anticoagulants. Biologics, such as rituximab and eculizumab, have been recommended for refractory catastrophic APS. This review focuses on the recent advancements in the pathogenesis of APS and explores the potential of targeted treatments, including eculizumab, rituximab, belimumab, daratumumab, obinutuzumab, and anti-TNF-α antibodies, for APS management.

Renal and vascular outcomes in patients with isolated antiphospholipid syndrome nephropathy

BACKGROUND

Antiphospholipid syndrome (APS) nephropathy (APSN) is a rare pattern with specific features resulting from microvascular lesions. The prognosis of APSN, outside of lupus nephritis, is unknown. The aim of this study was to describe the renal, vascular and overall outcomes of patients with APSN.

METHODS

Retrospective multicenter study of patients with antiphospholipid antibodies (aPL) associated with histological APSN lesions and no other nephropathy, identified through a national call for medical records. End-stage renal disease (ESRD)-free survival, thrombosis recurrence-free survival and overall survival were assessed.

RESULTS

Thirty patients were included (19 women) with a median age of 40 years (34-52 years). Fifteen patients had APS, 26/28 had lupus anticoagulant, and 15/26 had triple positivity for aPL. Median eGFR was 50 (31-60) mL/min/1.73 m². Glomerular thrombotic microangiopathy was found in 12/24 cases, fibrous intimal hyperplasia in 12/22 cases and focal cortical atrophy in 17/29 cases. Nineteen patients had moderate to severe interstitial fibrosis (>25%). Six patients developed ESRD at a median follow-up of 6.2 (1.8-9.1) years. The ESRD-free survival rates at 5 and 10 years were 80.0% (95% CI 57.6%-91.4%) and 72.7% (95% CI, 46.9%-87.4%) respectively. None of the histological factors considered was significantly associated with a decrease in eGFR at 12 months. Thrombosis recurrence-free survival was 77.8% (95% CI 48.2%-91.6%) at 10 years. Overall survival was 94% at 10 years (95% CI 65.0%-99.2%).

CONCLUSIONS

The renal prognosis of isolated APSN is poor. The severe fibrotic lesions observed are suggestive of late diagnosis.

Successful Treatment of Catastrophic Antiphospholipid Syndrome Using Rituximab: Case Report and Review of the Literature

BACKGROUND

Kidney involvement is a frequent complication of systemic lupus erythematosus (SLE) and kidney biopsy is essential in differentiating lupus nephritis (LN) from thrombotic microangiopathy (TMA) secondary to antiphospholipid autoantibodies (aPL). Association between antiphospholipid syndrome (APS) and acquired hemophilia due to inhibitors was very rarely described in SLE patients.

CASE PRESENTATION

We present the case of a 61-year-old male diagnosed with SLE who acquired deficiency of clotting factor VIII due to circulating inhibitors, admitted for acute kidney injury (AKI), microangiopathic hemolytic anemia, thrombocytopenia, and diplopia. Kidney biopsy showed TMA due to APS, but no signs of LN. Head computed tomography identified low dense areas in the white matter, suggesting small blood vessels' involvement. A diagnosis of probable catastrophic antiphospholipid syndrome (CAPS) was established and treatment with low molecular weight heparin, intravenous methylprednisolone, plasmapheresis, and rituximab was initiated, followed by resolution of AKI, diplopia, and TMA with complete depletion of CD19+B-lymphocytes (CD19+B-Ly) after one month. We further review the current knowledge regarding pathogenesis and management of CAPS in SLE patients.

CONCLUSIONS

Targeted therapy was possible after kidney biopsy, improving renal and general prognosis. CD19+B-Ly repopulation preceded biological relapse, so monitoring of CD19+B-Ly may serve as a tool to predict relapses and guide rituximab therapy.

Current concepts in the diagnosis and management of antiphospholipid syndrome and ocular manifestations

Antiphospholipid syndrome (APS) is an autoimmune disorder associated with obstetrical complications, thrombotic complications involving both arteries and veins, and non-thrombotic manifestations affecting multiple other systems presenting in various clinical forms. Diagnosis requires the presence of antiphospholipid antibodies. The exact pathogenesis of APS is not fully known. However, it has recently been shown that activation of different types of cells by antiphospholipid antibodies plays an important role in thrombosis formation. Ocular involvement is one of the important clinical manifestations of APS and can vary in presentations. Therefore, as an ophthalmologist, it is crucial to be familiar with the ocular findings of APS to prevent further complications that can develop. Furthermore, the ongoing identification of new and specific factors contributing to the pathogenesis of APS may provide new therapeutic options in the management of the disease in the future.

Thrombotic Microangiopathy After Kidney Transplantation: An Underdiagnosed and Potentially Reversible Entity

Thrombotic microangiopathy is a rare but serious complication that affects kidney transplant recipients. It appears in 0.8–14% of transplanted patients and negatively affects graft and patient survival. It can appear in a systemic form, with hemolytic microangiopathic anemia, thrombocytopenia, and renal failure, or in a localized form, with progressive renal failure, proteinuria, or arterial hypertension. Post-transplant thrombotic microangiopathy is classified as recurrent atypical hemolytic uremic syndrome or de novo thrombotic microangiopathy. De novo thrombotic microangiopathy accounts for the majority of cases. Distinguishing between the 2 conditions can be difficult, given there is an overlap between them. Complement overactivation is the cornerstone of all post-transplant thrombotic microangiopathies, and has been demonstrated in the context of organ procurement, ischemia-reperfusion phenomena, immunosuppressive drugs, antibody-mediated rejection, viral infections, and post-transplant relapse of antiphospholipid antibody syndrome. Although treatment of the causative agents is usually the first line of treatment, this approach might not be sufficient. Plasma exchange typically resolves hematologic abnormalities but does not improve renal function. Complement blockade with eculizumab has been shown to be an effective therapy in post-transplant thrombotic microangiopathy, but it is necessary to define which patients can benefit from this therapy and when and how eculizumab should be used.

Immunosuppressive Treatment in Antiphospholipid Syndrome: Is It Worth It?

The antiphospholipid syndrome (APS) is characterized by the development of venous and/or arterial thrombosis and pregnancy morbidity in patients with persistent antiphospholipid antibodies (aPL). Catastrophic antiphospholipid syndrome (CAPS) is a life-threatening form of APS occurring in about 1% of cases. Lifelong anticoagulation with vitamin K antagonists remains the cornerstone of the therapy for thrombotic APS, but frequently the use of anticoagulation may be problematic due to the increased risk of bleeding, drug interactions, or comorbidities. Immunosuppressant drugs are widely used to treat several autoimmune conditions, in which their safety and effectiveness have been largely demonstrated. Similar evidence in the treatment of primary APS is limited to case reports or case series, and studies on a large scale lack. Immunomodulatory drugs may be an emerging tool in managing such particular situations, like refractory obstetrical complications, CAPS, or so-called APS non-criteria manifestations. In addition, immunomodulatory drugs may be useful in patients experiencing recurrent thromboembolic events despite optimized anticoagulant therapy. We did a comprehensive review of literature analyzing the possible role of immunomodulation in primary APS to provide a broad overview of potentially safe and effective target treatments for managing this devastating disease.

Treatment of thrombotic antiphospholipid syndrome in adults and children

PURPOSE OF REVIEW

Antiphospholipid syndrome (APS), more common than once believed, is an autoimmune disease best known for its high risk of incident and recurrent thrombotic events. The approach to treatment potentially differs from treatment of thrombosis in the general population, and this article endeavors to review the latest updates on this topic.

RECENT FINDINGS

The epidemiology of APS is being increasingly elucidated by large population-based studies, with APS perhaps affecting as many as 1 in 2000 individuals. Vitamin K antagonists, aspirin, and heparinoids continue to have obvious roles in the management of patients with APS. There has recently been intensive study of direct oral anticoagulants in APS, with the most recent randomized studies raising concerns about their inferiority to vitamin K antagonists, at least in some subgroups. Other approaches to treating APS beyond anticoagulants and antiaggregants are also receiving increased attention in mechanistic and preclinical studies with an eye toward future roles in patients with refractory and/or microvascular disease. Pediatric APS is identified as an area in desperate need of additional prospective research.

SUMMARY

Progress continues to be made in pursuit of improving the lives of individuals afflicted with APS. The most important future directions would seem to involve leveraging modern molecular technologies in order to improve subphenotyping of antiphospholipid antibody-positive individuals. This will help personalize risk profiles and ideally define the optimal approach to therapy based on future risk, rather than past morbid events.

16th International Congress on Antiphospholipid Antibodies Task Force Report on Antiphospholipid Syndrome Treatment Trends

Antiphospholipid syndrome (APS), an acquired autoimmune thrombophilia, is characterised by thrombosis and/or pregnancy morbidity in association with persistent antiphospholipid antibodies. The 16th International Congress on Antiphospholipid Antibodies Task Force on APS Treatment Trends reviewed the current status with regard to existing and novel treatment trends for APS, which is the focus of this Task Force report. The report addresses current treatments and developments since the last report, on the use of direct oral anticoagulants in patients with APS, antiplatelet agents, adjunctive therapies (hydroxychloroquine, statins and vitamin D), targeted treatment including rituximab, belimumab, and anti-TNF agents, complement inhibition and drugs based on peptides of beta-2-glycoprotein I. In addition, the report summarises potential new players, including coenzyme Q10, adenosine receptor agonists and adenosine potentiation. In each case, the report provides recommendations for clinicians, based on the current state of the art, and suggests a clinical research agenda. The initiation and development of appropriate clinical studies requires a focus on devising suitable outcome measures, including a disease activity index, an optimal damage index, and a specific quality of life index.

[Thrombotic microangiopathy in rheumatology: a link between thrombosis and autoimmunity]

Uncontrolled hypercoagulation and inflammation (thromboinflammation), which are both independent and closely related and amplifying each other pathological processes, form the basis for pathogenesis of a wide range of diseases and complications, including immuno-inflammatory (autoimmune) rheumatic diseases, with the development of potentially fatal injuries of internal organs. Thrombotic microangiopathy is one of the most prominent prototypes of thromboinflammatory pathological conditions. The close link between environmental factors, hemostasis genetic defects and the complement system, inflammation and autoimmunity as pathogenetic mechanisms of microthrombosis draws particular attention to studying thrombotic microangiopathy in immuno-inflammatory rheumatic diseases, primarily systemic lupus erythematosus, antiphospholipid syndrome and scleroderma renal crisis. In future, these studies may be important for expanding the idea of the role of autoimmune mechanisms in pathogenesis of critical hemostasis disorders in human diseases, and for developing new approaches to therapy. Recently, special attention has been paid to the treatment of systemic lupus erythematosus and antiphospholipid syndrome with eculizumab, which is humanized monoclonal IgG2/4k antibody that blocks the complement component C5a and the membrane attack complex (C5b-9) formation, and which is registered for the treatment of atypical hemolytic uremic syndrome, paroxysmal nocturnal hemoglobinuria, as well as severe forms of myasthenia gravis and neuromyelitis optica. Further studies in this direction will create prerequisites for improving the prognosis not only in patients with orphan disorders, but also for widespread human diseases.

Atypical hemolytic uremic syndrome and complement blockade: established and emerging uses of complement inhibition

PURPOSE OF REVIEW

Atypical hemolytic uremic syndrome (aHUS) is a diagnosis that has captured the interest of specialists across multiple fields. The hallmark features of aHUS are microangiopathic hemolysis and thrombocytopenia, which creates a diagnostic dilemma because of the occurrence of these findings in a wide variety of clinical disorders.

RECENT FINDINGS

In most of the instances, aHUS is a diagnosis of exclusion after ruling out causes such as Shigella toxin, acquired or genetic a disintegrin and metalloproteinase thrombospondin motif 13 deficiency (thrombotic thrombocytopenic purpura), and vitamin B12 deficiency. In the purest sense, aHUS is a genetic condition that is activated (or unmasked) by an environmental exposure. However, it is now evident that complement activation is a feature of many diseases. Variants in complement regulatory genes predispose to microangiopathic hemolysis in many rheumatologic, oncologic, and drug-induced vascular, obstetric, peritransplant, and infectious syndromes.

SUMMARY

Many 'hemolysis syndromes' overlap clinically with aHUS, and we review the literature on the treatment of these conditions with complement inhibition. New reports on the treatment of C3 glomerulopathy, Shiga toxin-related classic hemolytic uremic syndrome, and medication-related thrombotic microangiopathy will be reviewed as well.

Targeted therapies in systemic sclerosis, myositis, antiphospholipid syndrome, and Sjögren's syndrome

Targeted therapies using biological disease-modifying antirheumatic drugs (bDMARDs) and small molecule synthetic drugs have revolutionized rheumatological practice. Initially developed for the treatment of immune arthritis (rheumatoid arthritis, psoriatic arthritis, and spondylarthritis), both bDMARDs and small molecule synthetic drugs are now increasingly entering the space of connective tissue disease (CTD) treatment. Recent clinical trial data in systemic sclerosis (SSc) have been particularly encouraging with positive effects on outcomes having been observed with nintedanib preventing the decline of lung function in patients with SSc-related interstitial lung disease. Randomized trials targeting B-cells by rituximab in primary Sjogren's syndrome have led to mixed results. Novel strategies to target B-cells in primary Sjögren's syndrome including ianalumab and belimumab are underway and will hopefully result in clear treatment effects. Inflammatory idiopathic myositis (polymyositis (PM) and dermatomyositis (DM)) and antiphospholid syndrome are proving to be more difficult to tackle but are nonetheless the subject of ongoing studies. To what extent new compounds can replace more traditional immunosuppressive drugs remains to be determined, but if the experience in immune arthritis has taught us anything it is that combination therapy may be the way to go.

Atypical hemolytic uremic syndrome: a syndrome in need of clarity

Atypical hemolytic uremic syndrome (aHUS) is a thrombotic microangiopathy (TMA) originally understood to be limited to renal and hematopoietic involvement. Whereas aberrations in complement regulatory proteins (CRPs), C3 or complement factor B (CFB) are detected in ∼60% of patients, a complement-derived pathogenesis that reflects dysregulation of the alternative pathway (AP) of complement activation is present in ∼90% of patients. aHUS remains a diagnosis of exclusion. The discovery of a disintegrin and metalloproteinase with a thrombospondin type 1 motif, member 13 (ADAMTS13) and its utility in the diagnosis of thrombotic thrombocytopenic purpura (TTP) has resulted in the appreciation that cases of aHUS have been inappropriately diagnosed as TTP. Thus there has been an evolving appreciation of clinical manifestations of aHUS that renders the appellation aHUS misleading. This article will review the pathogenesis and the evolving clinical presentations of aHUS, present a hypothesis that there can be a phenotypic expression of aHUS due to a complement storm in a disorder where direct endothelial damage occurs and discuss future areas of research to more clearly define the clinical spectrum and management of aHUS.

Secondary thrombotic microangiopathy in systemic lupus erythematosus and antiphospholipid syndrome, the role of complement and use of eculizumab: Case series and review of literature

INTRODUCTION

Thrombotic microangiopathy (TMA) is a life-threatening, albeit infrequent, complication of systemic lupus erythematosus (SLE) and anti-phospholipid syndrome (APS). Recommendations for the treatment of SLE- and APS-related secondary TMA are currently based solely on case reports and expert opinion. Unfortunately, interventions may not yield timely results or effectively halt the progression of TMA. Since complement activation plays a key role in the pathogenesis of secondary TMA due to SLE, APS, a therapy that targets the complement pathway is an attractive intervention. Eculizumab, a recombinant, fully humanized IgG2/IgG4 monoclonal antibody inhibits C5 activation and is FDA-approved for PNH and atypical HUS (aHUS). However, limited case reports are available on its use in treatment of secondary TMA.

CASE PRESENTATION AND RESULTS

We present the largest case series to date that includes 9 patients with SLE and/or APS who were successfully treated with eculizumab for refractory secondary TMA. In this case series, we report significant responses in hematology values, renal function and other organs following treatment with eculizumab. At 4 weeks, 75% improvement in platelet counts was observed in 78% of patients. Two-thirds of patients demonstrated >75% improvement of haptoglobin and LDH at four weeks. At 4 weeks, eGFR improved by 25% in half of the patients, and 43% had reductions in proteinuria. Two of 3 patients that required hemodialysis were able to be taken off hemodialysis.

CONCLUSION

Based on these observations, we suggest that eculizumab may be a potential treatment option for acutely ill patients with secondary TMA due to SLE and/or APS who have failed standard of care. A collective approach is needed to better elucidate the role and optimal timing of eculizumab use in the management of TMA complicating SLE and/or APS.

Antiphospholipid Syndrome and the Neurologist: From Pathogenesis to Therapy

Antiphospholipid syndrome (APS) is an autoimmune antibody-mediated condition characterized by thrombotic events and/or pregnancy morbidity in association with persistent positivity to antiphospholipid antibodies (aPL). The nervous system is frequently affected, as intracranial vessels are the most frequent site of arterial pathology. Over the course of years, many other neurological conditions not included in the diagnostic criteria, have been associated with APS. The pathogenic mechanisms behind the syndrome are complex and not fully elucidated. aPL enhance thrombosis, interfering with different pathways. Nevertheless, ischemic injury is not always sufficient to explain clinical features of the syndrome and immune-mediated damage has been advocated. This may be particularly relevant in the context of neurological complications. The reason why only a subgroup of patients develop non-criteria nervous system disorders and what determines the clinical phenotype are questions that remain open. The double nature, thrombotic and immunologic, of APS is also reflected by therapeutic strategies. In this review we summarize known neurological manifestations of APS, revisiting pathogenesis and current treatment options.

Antiphospholipid syndrome – an update

Abstract. Antiphospholipid syndrome (APS) is an autoantibody-mediated acquired thrombophilia. It is characterized by the presence of antiphospholipid antibodies (APL) that are directed against phospholipid-binding plasma proteins, such as beta-2-glycoprotein I (b2GPI). Its main manifestations are recurrent vascular thromboses (so-called “thrombotic APS”) and pregnancy complications (“obstetric APS”). According to the current consensus criteria, a persistently positive functional lupus anticoagulant (LA) assay and/or the presence of anti-b2GPI and/or anti-cardiolipin antibodies, together with clinical symptoms, is mandatory for the diagnosis of APS. Other clinical features, such as thrombocytopenia, Coombs-positive haemolytic anaemia, heart valve disease, renal microangiopathy and neurologic disorders are also common in APL-positive patients. APS can be associated with other autoimmune disorders, such as systemic lupus erythematosus. In rare cases, catastrophic APS (CAPS) occurs, with the development of excessive thrombosis at multiple sites, usually affecting small vessels and leading to multi-organ dysfunction and organ failure. Treatment usually comprises antithrombotic therapy using antiplatelet and anticoagulant agents. However, there is no consensus concerning the intensity or duration of therapy. Despite apparently adequate anticoagulation, the risk of recurrent thrombosis remains high. For patients with CAPS, a combined therapeutic approach that includes anticoagulation, glucocorticoids, plasma exchange and/or intravenous immunoglobulin seems to be the best treatment option.

Keywords: Antiphospholipid syndrome, lupus anticoagulants, anti-cardiolipin, anti-beta-2-glycoprotein I, vascular thrombosis, pregnancy complication

Thrombotic microangiopathy after renal transplantation: Current insights in de novo and recurrent disease

Thrombotic microangiopathy (TMA) is one of the most devastating sequalae of kidney transplantation. A number of published articles have covered either de novo or recurrent TMA in an isolated manner. We have, hereby, in this article endeavored to address both types of TMA in a comparative mode. We appreciate that de novo TMA is more common and its prognosis is poorer than recurrent TMA; the latter has a genetic background, with mutations that impact disease behavior and, consequently, allograft and patient survival. Post-transplant TMA can occur as a recurrence of the disease involving the native kidney or as de novo disease with no evidence of previous involvement before transplant. While atypical hemolytic uremic syndrome is a rare disease that results from complement dysregulation with alternative pathway overactivity, de novo TMA is a heterogenous set of various etiologies and constitutes the vast majority of post-transplant TMA cases. Management of both diseases varies from simple maneuvers, e.g., plasmapheresis, drug withdrawal or dose modification, to lifelong complement blockade, which is rather costly. Careful donor selection and proper recipient preparation, including complete genetic screening, would be a pragmatic approach. Novel therapies, e.g., purified products of the deficient genes, though promising in theory, are not yet of proven value.

Thrombotic microangiopathy associated with anticardiolipin antibody in a kidney transplant recipient with polycythemia

Thrombotic microangiopathy (TMA) develops from various etiologies, and it is often difficult to distinguish the etiology of TMA in kidney transplantation. Antiphospholipid syndrome (APS) is one of the differential diagnoses for TMA that may cause acute loss of graft function or fatal thrombotic complications. This report details a 66-year-old male patient with polycythemia after ABO-incompatible kidney transplantation. Antibody screening tests were negative before transplant. Despite administration of an adequate desensitization therapy including plasmapheresis and rituximab, he developed acute graft dysfunction on postoperative day 112 and graft biopsy revealed prominent microvascular inflammation in the glomerular capillaries without immunoglobulin deposits. Flow cytometric panel-reactive antibody screening failed to detect donor-specific antibodies at both pre-transplant and episode biopsies. Anticardiolipin antibody was repeatedly positive, but neither thrombosis nor previous thrombotic episodes were detected. After excluding several differential diagnoses, the graft dysfunction with unexplained TMA was treated with steroid pulse, plasmapheresis and rituximab re-induction. Anticardiolipin antibody disappeared after this intensive treatment and graft function recovered gradually and stabilized for 52 months. This report suggests that asymptomatic anticardiolipin antibody may be associated with acute graft dysfunction. Even if thrombotic episodes are not observed, an exist of anticardiolipin antibody may be one of the risk factors of renal TMA after kidney transplantation.

Secondary thrombotic microangiopathy and eculizumab: A reasonable therapeutic option

Understanding the role of the complement system in the pathogenesis of atypical haemolytic uraemic syndrome and other thrombotic microangiopathies (TMA) has led to the use of anti-complement therapy with eculizumab in these diseases, in addition to its original use in patients with paroxysmal nocturnal haemoglobinuria andatypical haemolytic uraemic syndrome. Scientific evidence shows that both primary and secondary TMAs with underlying complement activation are closely related. For this reasons, control over the complement system is a therapeutic target. There are 2scenarios in which eculizumab is used in patients with TMA: primary or secondary TMA that is difficult to differentiate (including incomplete clinical presentations) and complement-mediated damage in various processes in which eculizumab proves to be efficacious. This review summarises the evidence on the role of the complement activation in the pathophysiology of secondary TMAs and the efficacy of anti-complement therapy in TMAs secondary to pregnancy, drugs, transplant, humoral rejection, systemic diseases and glomerulonephritis. Although experience is scarce, a good response to eculizumab has been reported in patients with severe secondary TMAs refractory to conventional treatment. Thus, the role of the anti-complement therapy as a new treatment option in these patients should be investigated.

Renal involvement in antiphospholipid syndrome

This is a review of scientific publications on renal involvement in antiphospholipid syndrome (APS), with focus on clinical and histopathological findings and treatment. A search for English-language articles on renal involvement in APS covering the period 1980-2017 was conducted in Medline/PubMed and Scopus databases using the MeSH terms "antiphospholipid syndrome", "antiphospholipid antibodies", "glomerulonephritis" and "thrombotic microangiopathy" (TMA). APS nephropathy is primarily the result of thromboses in renal arteries or veins, intraparenchymatous arteries and glomerular capillaries. On histology, APS nephropathy is characterized by TMA, but chronic vaso-occlusive lesions are also commonly observed (fibrous intimal hyperplasia, focal cortical atrophy, fibrous occlusions of arteries). Anticardiolipin and lupus anticoagulant are the most prevalent antibodies in patients with APS nephropathy. The spectrum of renal manifestations includes renal vein thrombosis, renal artery thrombosis/stenosis, TMA, increased allograft vascular thrombosis and malignant hypertension. Anticoagulation is the standard treatment of thrombotic events. In systemic lupus erythematosus (SLE) patients with antiphospholipid antibodies (aPL), kidney failure due to SLE nephritis (immune-complex disease) should be clearly distinguished from kidney failure due to APS-related TMA. In such cases, renal biopsy is mandatory. SLE nephritis requires immunosuppressive therapy, whereas APS nephropathy is usually treated with anticoagulants. Recently, eculizumab and sirolimus have been proposed as a rescue therapy. Based on our review, APS nephropathy appears to be a distinct clinical condition. TMA is a characteristic histopathological finding in APS and is strongly associated with the presence of aPL. This has important therapeutic implications and allows distinguishing APS nephropathy from lupus nephritis.

[Current insights about recurrence of glomerular diseases after renal transplantation]

Recurrence of glomerular disease after renal transplantation is a frequent cause of graft loss. Incidence, risk factors and outcome of recurrence are widely due to the underlying glomerular disease. Graft biopsy analysis is required to confirm the definitive diagnosis of recurrence and to start an appropriate therapy that, in some cases, remains challenging to prevent graft failure. Increased use of protocol biopsy and recent advances in our understanding of the pathogenesis of some glomerular diseases with the identification of some relevant biomarkers provide a unique opportunity to initiate kidney-protective therapy at early stages of recurrence on the graft. This review summarizes our current knowledge on the management of many recurrent primary and secondary glomerulonephritis after kidney transplantation.

Treatment of antiphospholipid syndrome beyond anticoagulation

Antiphospholipid syndrome (APS) is a systemic autoimmune disorder marked by thrombosis and/or pregnancy morbidity in the presence of antiphospholipid antibodies (aPL). At the present time, treatment is primarily focused on anticoagulation. However, there is increasing awareness of the mechanisms involved in APS pathogenesis, which has led to the trial of novel therapies targeting those mechanisms. Following a brief review of the etiopathogenesis of and current management strategies in APS, this paper focuses on the evidence for these potential, targeted APS treatments, e.g., hydroxychloroquine, statins, rituximab, belimumab, eculizumab, defibrotide, sirolimus, and peptide therapy.

Transplant glomerulopathy

In the renal allograft, transplant glomerulopathy represents a morphologic lesion and not a specific diagnosis. The hallmark pathologic feature is glomerular basement membrane reduplication by light microscopy or electron microscopy in the absence of immune complex deposits. Transplant glomerulopathy results from chronic, recurring endothelial cell injury that can be mediated by HLA alloantibodies (donor-specific antibodies), various autoantibodies, cell-mediated immune injury, thrombotic microangiopathy, or chronic hepatitis C. Clinically, transplant glomerulopathy may be silent, detectable on protocol biopsy, or present with overt manifestations, including up to nephrotic range proteinuria, hypertension, and declining glomerular filtration rate. In either case, transplant glomerulopathy is associated with reduced graft survival. This review details the morphologic features of transplant glomerulopathy found on light microscopy, immunofluorescence microscopy, and electron microscopy. The pathophysiology of the causes and risk factors are discussed. Clinical manifestations are emphasized and potential therapeutic modalities are examined.

Catastrophic antiphospholipid syndrome and pregnancy

Catastrophic antiphospholipid syndrome (CAPS) is a rare but life-threatening condition that may be precipitated by pregnancy. The condition can be hard to diagnose since it mimics other thrombotic microangiopathies that are associated with pregnancy. Accurate and timely diagnosis is critical for effective treatment. In this review, we highlight pertinent clinical features of CAPS so that obstetricians will be able to recognize and treat the condition.

Infections associated with the use of eculizumab: recommendations for prevention and prophylaxis

PURPOSE OF REVIEW

Eculizumab inhibits complement effector functions and has significantly impacted the treatment of paroxysmal nocturnal hemoglobinuria and atypical hemolytic uremic syndrome. However, the risks of potentially life-threatening infections, notably with Neisseria spp. in addition to its cost, are major challenges in clinical practice. In this review, we characterize and summarize the infectious complications reported with the use of eculizumab in the context of its typical and expanding indications.

RECENT FINDINGS

Use of eculizumab is rapidly extending to the fields of transplantation and neurology. Eculizumab has been primarily associated with an increased risk of meningococcal infections. Immunization against its commonest serotypes (ABCWY) is now possible with the advent of the meningococcal B vaccine. A combined ABCWY vaccine is underway. Preventive strategies against breakthrough Neisseria infections should also include chemoprophylaxis. Less is known about the association of eculizumab with other infections as recently reported. Surrogate markers of complement blockade, notably CH50, and eculizumab efficacy may help in the risk assessment of infection.

SUMMARY

Eculizumab has opened new horizons in the treatment of complement-mediated disorders. Prophylactic and immunization strategies against the risk of Nesseria spp. infections are sound and feasible. The use of eculizumab is expanding beyond complement-mediated diseases to transplantation and neurological disorders. Further research is needed to better define and stratify the risk of infection and prevention strategies in patients with the latter indications.

Catastrophic Antiphospholipid Syndrome: Candidate Therapies for a Potentially Lethal Disease

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.

The role of complement inhibition in kidney transplantation

INTRODUCTION AND BACKGROUND

The complement system which belongs to the innate immune system acts both as a first line of defence against various pathogens and as a guardian of host homeostasis. The role of complement has been recently highlighted in several aspects of kidney transplantation: ischaemia-reperfusion, antibody-mediated rejection and native kidney disease recurrence.

SOURCES OF DATA

Experimental data, availability of complement-blocking molecules (mainly the anti-C5 monoclonal antibody, eculizumab) and several trials in human kidney transplant recipients has led to some areas of agreement and some disappointment.

AREAS OF AGREEMENT AND CONTROVERSIES

So far, eculizumab has shown great efficacy in treatment and prevention of atypical haemolytic and uraemic syndrome, some efficacy in the prevention of antibody-mediated and so far no efficacy in the prevention of delayed graft function.

GROWING POINTS

Among the numerous potentially available drugs potentially interfering with complement, recent focus has been made on C1 blockers in the setting of antibody-mediated rejection with promising results.

AREAS TIMELY FOR DEVELOPING RESEARCH

Complement is now recognized as a major player in transplant immunology, several targets are going to be tested to define precisely which ones may be potentially useful in clinical practice.

De novo thrombotic microangiopathy after kidney transplantation

Thrombotic microangiopathy (TMA) is a serious complication of transplantation that adversely affects kidney transplant recipient and allograft survival. Post-transplant TMA is usually classified into two categories: 1) recurrent TMA and 2) de novo TMA. Atypical hemolytic uremic syndrome (aHUS) resulting from dysregulation and over-activation of the alternate complement pathway is a rare disease but the most common diagnosis associated with recurrence in the allografts. De novo TMA, on the other hand, represents an overwhelming majority of the cases of post-transplant TMA and is a substantially more heterogeneous entity than recurrent aHUS. Here, we review the etio-pathogenesis, diagnosis and treatment options for de novo post-transplant TMA. It is usually in the setting of calcineurin inhibitor use, mammalian target of rapamycin inhibitor use, or antibody mediated rejection; recently genetic mutations in complement regulatory genes for Factor H and Factor I similar to those described in aHUS have been reported in up to a third of these patients. Systemic signs of TMA are frequently absent, and a renal allograft biopsy is often needed to establish the diagnosis. Although withdrawal of the offending agents is usually the first line of treatment and resolution of laboratory abnormalities has been documented with this approach in several case reports and case series, available retrospective data demonstrate lack of benefit in long-term graft outcomes. Co-stimulation blockage with belatacept provides an effective alternate immunosuppressive strategy for these patients. Anti-complement therapy with eculizumab is effective in some cases; further work is required to define which patients with TMA (with and without concomitant antibody-mediated rejection) would benefit from receiving this treatment, and what biomarkers can be used to identify them.

Eculizumab in secondary atypical haemolytic uraemic syndrome

Background. Complement dysregulation occurs in thrombotic microangiopathies (TMAs) other than primary atypical haemolytic uraemic syndrome (aHUS). A few of these patients have been reported previously to be successfully treated with eculizumab.

Methods. We identified 29 patients with so-called secondary aHUS who had received eculizumab at 11 Spanish nephrology centres. Primary outcome was TMA resolution, defined by a normalization of platelet count (>150 × 10⁹/L) and haemoglobin, disappearance of all the markers of microangiopathic haemolytic anaemia (MAHA), and improvement of renal function, with a ≥25% reduction of serum creatinine from the onset of eculizumab administration.

Results. Twenty-nine patients with secondary aHUS (15 drug-induced, 8 associated with systemic diseases, 2 with postpartum, 2 with cancer-related, 1 associated with acute humoral rejection and 1 with intestinal lymphangiectasia) were included in this study. The reason to initiate eculizumab treatment was worsening of renal function and persistence of TMA despite treatment of the TMA cause and plasmapheresis. All patients showed severe MAHA and renal function impairment (14 requiring dialysis) prior to eculizumab treatment and 11 presented severe extrarenal manifestations. A rapid resolution of the TMA was observed in 20 patients (68%), 15 of them showing a ≥50% serum creatinine reduction at the last follow-up. Comprehensive genetic and molecular studies in 22 patients identified complement pathogenic variants in only 2 patients. With these two exceptions, eculizumab was discontinued, after a median of 8 weeks of treatment, without the occurrence of aHUS relapses.

Conclusion. Short treatment with eculizumab can result in a rapid improvement of patients with secondary aHUS in whom TMA has persisted and renal function worsened despite treatment of the TMA-inducing condition.

Complement C5-inhibiting therapy for the thrombotic microangiopathies: accumulating evidence, but not a panacea

Thrombotic microangiopathy (TMA), characterized by organ injury occurring consequent to severe endothelial damage, can manifest in a diverse range of diseases. In complement-mediated atypical haemolytic uraemic syndrome (aHUS) a primary defect in complement, such as a mutation or autoantibody leading to over activation of the alternative pathway, predisposes to the development of disease, usually following exposure to an environmental trigger. The elucidation of the pathogenesis of aHUS resulted in the successful introduction of the complement inhibitor eculizumab into clinical practice. In other TMAs, although complement activation may be seen, its role in the pathogenesis remains to be confirmed by an interventional trial. Although many case reports in TMAs other than complement-mediated aHUS hint at efficacy, publication bias, concurrent therapies and in some cases the self-limiting nature of disease make broader interpretation difficult. In this article, we will review the evidence for the role of complement inhibition in complement-mediated aHUS and other TMAs.

Use of eculizumab in a systemic lupus erythemathosus patient presenting thrombotic microangiopathy and heterozygous deletion in CFHR1-CFHR3. A case report and systematic review

The association of thrombotic microangiopathy (TMA) with systemic lupus erythematosus (SLE) has been described in 0.5 to 10% of cases, and patients present worse outcome. TMA is described as the association of microangiopathic hemolytic anemia, thrombocytopenia, and an organ injury, frequently the kidney. This study describes a successful case of use of eculizumab in a patient with SLE and TMA refractory to standard therapy, and provides a literature review. Case description and search in PubMed and MEDLINE using systemic lupus erythemathous and/or antiphospholipid syndrome (APS) and eculizumab retrieved 15 case reports. Eighteen-year-old female presented acute renal failure and TMA and was diagnosed with SLE. Steroids and IV cyclophosphamide were started together with plasma exchange. After 55 days, she still persisted with microangiopathic anemia, thrombocytopenia, and anuria, and eculizumab was introduced. She had rapid improvement in hematological parameters, and dialysis was discontinued 25 days after the first dose. Genetic analysis showed large heterozygous deletion encompassing the entire CFHR1 and CFHR3, a finding previously associated with patients presenting atypical hemolytic-uremic syndrome (aHUS). Twenty patients who received eculizumab with SLE and/or APS have been published to date: 11 were female and mean age at presentation was 31 years. Seven out of the 20 patients presented only SLE, 5 patients only APS and 8 patients both SLE and APS. Eighteen patients underwent plasma exchange, with a mean of 20 (4-120) sessions per patient. Thirteen patients received rituximab. Hematological response was evident in 100% and kidney recovery in 85% of patients. The terminal complement blockade with eculizumab is an optional treatment for patients with SLE and/or APS presenting TMA and refractory to current immunosuppression therapies. Genetic testing may help recognize patients with aHUS and SLE/APS and therefore help to determine length of treatment with eculizumab.

Vascular Manifestations in Antiphospholipid Syndrome (APS): Is APS a Thrombophilia or a Vasculopathy?

PURPOSE OF REVIEW

Antiphospholipid antibody syndrome (APS) is characterized primarily by thrombosis and pregnancy morbidity. Chronic vascular lesions can also occur. While the underlying mechanisms of these vascular lesions are not entirely known, there have been multiple theories describing the potential process of vasculopathy in APS and the various clinical manifestations associated with it.

RECENT FINDINGS

Recently, it has been demonstrated that endothelial proliferation in kidneys can be explained by the activation of the mammalian target of rapamycin complex (mTORC) pathway by antiphospholipid antibodies (aPL). These data support the existence of an APS-related vasculopathy in different locations which can explain-in part-the different manifestations of APS. This review focuses on the various manifestations of APS as a result of APS-related vasculopathy, as well as pathophysiology, current screening, and treatment options for clinicians to be aware of.

Diagnosing antiphospholipid syndrome: 'extra-criteria' manifestations and technical advances

First described in the early 1980s, antiphospholipid syndrome (APS) is a unique form of acquired autoimmune thrombophilia in which patients present with clinical features of recurrent thrombosis and pregnancy morbidity and persistently test positive for the presence of antiphospholipid antibodies (aPL). At least one clinical (vascular thrombosis or pregnancy morbidity) and one lab-based (positive test result for lupus anticoagulant, anticardiolipin antibodies and/or anti-β2-glycoprotein 1 antibodies) criterion have to be met for a patient to be classified as having APS. However, the clinical spectrum of APS encompasses additional manifestations that can affect many organs and cannot be explained exclusively by patients being in a prothrombotic state; clinical manifestations not listed in the classification criteria (known as extra-criteria manifestations) include neurologic manifestations (chorea, myelitis and migraine), haematologic manifestations (thrombocytopenia and haemolytic anaemia), livedo reticularis, nephropathy and valvular heart disease. Increasingly, research interest has focused on the development of novel assays that might be more specific for APS than the current aPL tests. This Review focuses on the current classification criteria for APS, presenting the role of extra-criteria manifestations and lab-based tests. Diagnostic approaches to difficult cases, including so-called seronegative APS, are also discussed.

Endothelial cells: source, barrier, and target of defensive mediators

Endothelium is strategically located at the interface between blood and interstitial tissues, placing thus endothelial cell as a key player in vascular homeostasis. Endothelial cells are in a dynamic equilibrium with their environment and constitute concomitantly a source, a barrier, and a target of defensive mediators. This review will discuss the recent advances in our understanding of the complex crosstalk between the endothelium, the complement system and the hemostasis in health and in disease. The first part will provide a general introduction on endothelial cells heterogeneity and on the physiologic role of the complement and hemostatic systems. The second part will analyze the interplay between complement, hemostasis and endothelial cells in physiological conditions and their alterations in diseases. Particular focus will be made on the prototypes of thrombotic microangiopathic disorders, resulting from complement or hemostasis dysregulation-mediated endothelial damage: atypical hemolytic uremic syndrome and thrombotic thrombocytopenic purpura. Novel aspects of the pathophysiology of the thrombotic microangiopathies will be discussed.

Antiphospholipid Syndrome: Role of Vascular Endothelial Cells and Implications for Risk Stratification and Targeted Therapeutics

Antiphospholipid syndrome (APS) is an autoimmune disease characterized by venous thromboembolism, arterial thrombosis, and obstetric morbidities in the setting of persistently positive levels of antiphospholipid antibodies measured on 2 different occasions 12 weeks apart. Patients with APS are at increased risk for accelerated atherosclerosis, myocardial infarction, stroke, and valvular heart disease. Vascular endothelial cell dysfunction mediated by antiphospholipid antibodies and subsequent complement system activation play a cardinal role in APS pathogenesis. Improved understanding of their pathogenic function could help in the risk stratification of patients with APS and provide new molecular therapeutic targets.

A novel 2-stage approach that detects complement activation in patients with antiphospholipid antibody syndrome

INTRODUCTION

The antiphospholipid syndrome (APS) is marked by autoantibodies that recognize anionic phospholipids in a cofactor-dependent manner. A role for complement has been implicated in the pathophysiology, however, elevations of complement activation markers have not been consistently demonstrated in clinical studies. We therefore designed a proof-of-principle study to determine whether complement activation might be detectable in APS by first exposing plasmas to phospholipid vesicles.

METHODS

We examined complement activation markers in patients with APS, non-APS thrombosis, systemic lupus erythematosus, cancer, patients with antiphospholipid antibodies without thrombosis (APL) and healthy controls. Direct measurements of plasma C5a and sC5b-9 levels were compared to levels that were generated in normal serum by phospholipid vesicles that had been pre-incubated with the same plasmas. We then determined the effects of the C5 inhibitor, eculizumab, examined the complement pathways involved, and determined whether the effects could be reproduced with purified IgGs and β2-glycoprotein I (β2GPI).

RESULTS

Plasma levels of C5a and sC5b-9 were higher, but not significantly increased in APS patients compared to healthy controls. In contrast, phospholipid vesicles pre-incubated with APS plasmas generated significantly higher levels than healthy controls and the other groups, except for APL patients. Complement activation was abrogated by addition of eculizumab. The results with substrate sera indicated that the alternative and classical/lectin pathways were involved. The results were reproducible with purified IgGs and β2GPI.

CONCLUSION

This proof-of-principle study confirms a role for complement in APS and opens the possibility of monitoring complement activation by including phospholipid vesicles in assay systems.

The Role of Complement Inhibition in Thrombotic Angiopathies and Antiphospholipid Syndrome

Antiphospholipid syndrome (APS) is characterized by thrombosis (arterial, venous, small vessel) and/or pregnancy morbidity occurring in patients with persistently positive antiphospholipid antibodies (aPL). Catastrophic APS is the most severe form of the disease, characterized by multiple organ thromboses occurring in a short period and commonly associated with thrombotic microangiopathy (TMA). Similar to patients with complement regulatory gene mutations developing TMA, increased complement activation on endothelial cells plays a role in hypercoagulability in aPL-positive patients. In mouse models of APS, activation of the complement is required and interaction of complement (C) 5a with its receptor C5aR leads to aPL-induced inflammation, placental insufficiency, and thrombosis. Anti-C5 antibody and C5aR antagonist peptides prevent aPL-mediated pregnancy loss and thrombosis in these experimental models. Clinical studies of anti-C5 monoclonal antibody in aPL-positive patients are limited to a small number of case reports. Ongoing and future clinical studies of complement inhibitors will help determine the role of complement inhibition in the management of aPL-positive patients.

[Obstetrical APS: Is there a place for additional treatment to aspirin-heparin combination?]

Obstetrical APS is defined by thrombosis and/or obstetrical morbidity associated with persistent antiphospholipid antibodies. The aspirin and low molecular weighted heparin combination dramatically improved obstetrical outcome in APS patients. Several factors could be associated with obstetrical prognosis, as previous history of thrombosis, associated SLE, the presence of lupus anticoagulant and triple positivity of antiphospholipid antibodies. Obstetrical APS with isolated recurrent miscarriages is mostly associated with isolated anticardiolipids antibodies and have better obstetrical outcome. The pregnancy loss despite aspirin and heparin combination define the refractory obstetrical APS, and the prevalence could be estimated to 20-39%. Several other treatments have been used in small and open labeled studies, as steroids, intravenous immunoglobulins, plasma exchanges and hydroxychloroquine to improve the obstetrical outcome. Some other drugs as eculizumab and statins could also have physiopathological rational, but studies are necessary to define the place of these various drugs.

Emerging Therapies in Antiphospholipid Syndrome

Antiphospholipid syndrome (APS) is a hypercoagulable state characterized by arterial and venous thromboses and pregnancy morbidity in the presence of antiphospholipid antibodies. Although warfarin remains the main therapeutic choice in APS, there is still concern about its efficacy, safety, and patient compliance. Patients with refractory APS to conventional therapy as well as patients with non-classical manifestations of APS may have alternative treatment approaches. APS pathogenesis has been further elucidated over the past years identifying new molecules as potential new treatment targets. This review summarizes available data from in vitro and animal models and clinical studies on the role of new potential treatment approaches including new oral anticoagulants and immunoregulatory agents: direct thrombin or factor Xa inhibitors, hydroxychloroquine, statins, B cell inhibition, complement inhibition, peptide therapy, nuclear factor κB and p38 mitogen-activated kinase inhibitors, defibrotide, abciximab, mTOR inhibitor, and other potential targets. Large multicenter prospective studies of well-characterized APS patients are needed to assess the efficacy and safety profile of these potential treatment alternatives.

Antiphospholipid syndrome and kidney disease

The antiphospholipid syndrome is a common autoimmune disease caused by pathogenic antiphospholipid antibodies, leading to recurrent thrombosis and/or obstetrical complications. Importantly for nephrologists, antiphospholipid antibodies are associated with various renal manifestations including large renal vessel thrombosis, renal artery stenosis, and a constellation of intrarenal lesions that has been termed antiphospholipid nephropathy. This last condition associates various degrees of acute thrombotic microangiopathy, proliferative and fibrotic lesions of the intrarenal vessels, and ischemic modifications of the renal parenchyma. The course of the disease can range from indolent nephropathy to devastating acute renal failure. The pejorative impact of antiphospholipid antibody-related renal complication is well established in the context of systemic lupus erythematous or after renal transplantation. In contrast, the exact significance of isolated antiphospholipid nephropathy remains uncertain. The evidence to guide management of the renal complications of antiphospholipid syndrome is limited. However, the recent recognition of the heterogeneous molecular mechanisms underlying the progression of intrarenal vascular lesions in antiphospholipid syndrome have opened promising tracks for patient monitoring and targeted therapeutic intervention.

Thrombotic Microangiopathy in the Setting of HIV Infection: A Case Report and Review of the Differential Diagnosis and Therapy

Before the modern era of HIV/AIDS therapeutics, which enabled a cascade of early recognition of infection, prompt initiation of effective antiretroviral therapies, and close follow-up, severe forms of microvascular clotting disorders known as thrombotic microangiopathies (TMAs) were frequent in the setting of advanced HIV disease. Their incidence was as high as 7% in the period 1984-1999, but fell dramatically, to <0.5%, by 2002. This profound change was predicated on one critical development: availability of new classes of anti-HIV drugs, enabling reduction and maintenance of HIV viral loads to undetectable levels. Another development in the period 1999-2002 related to TMA therapy: with recognition of autoantibodies against the von Willebrand factor cleaving protease ADAMTS13 as the etiology of most cases of one major form of TMA, thrombotic thrombocytopenic purpura, it permitted appropriate use of life-saving interventions based on plasma exchange and immune suppression. A more recent factor in TMA therapeutics was the 2011 approval by the US FDA and European EMA of eculizumab, a humanized monoclonal antibody against complement component C5, for the treatment of atypical hemolytic uremic syndrome, another major form of TMA. Despite these milestones, life- and organ-threatening TMAs still occur in untreated HIV disease and, to a much lesser extent, in those patients with suppressed viral loads. Confusion in terms of the differential diagnosis of these TMAs also impedes use of directed treatments. This report utilizes a case study of a young woman with advanced AIDS who presented with a severe TMA, characterized by coma and renal failure, to highlight the diagnostic and therapeutic challenges raised by complex hematologic conditions occurring in the setting of HIV.

Eculizumab in Transplant-Associated Thrombotic Microangiopathy

Introduction:

Transplant-associated thrombotic microangiopathy (TA-TMA) is a rare entity with no standard of care and high mortality, despite the use of plasma exchange.

Methods:

Using specific search terms, all cases having TA-TMA treated with eculizumab and indexed in MEDLINE (English language only) by November 2014 were reviewed.

Results:

A total of 26 cases, 53% men, had a median age of 33 years (range 2-61). Transplant-associated thrombotic microangiopathy occurred after stem-cell transplant (35%) or solid-organ transplant (65%), frequently associated with the use of cyclosporine or tacrolimus (96%). A disintegrin and metalloproteinase with a thrombospondin type 1 motif, member 13 (ADAMTS 13) level was always >10%. After TA-TMA diagnosis, the following drug adjustments were made: discontinuation of cyclosporine or tacrolimus in 45%, dose reduction in another 27%, continuation of the drugs in 23%, and switch from cyclosporine to tacrolimus in remaining 5%. Plasma exchange was performed in ∼43%. The median interval between transplant and initiation of eculizumab was 63 days (range 11-512). A median of 5.5 doses (range 2-21) of eculizumab was utilized with 92% response occurring after a median of 2 doses (range 1-18). At a median follow-up of 52 weeks (range 3-113), the survivors (92%) were doing well.

Conclusion:

Within the limits of this retrospective analysis, our study demonstrates that eculizumab use may result in high response rate and 1-year survival in patients with TA-TMA refractory to discontinuation of calcineurin inhibitor and plasma exchange.

Eculizumab Induces Sustained Remission in a Patient With Refractory Primary Catastrophic Antiphospholipid Syndrome

Catastrophic antiphospholipid syndrome (CAPS) is fatal in approximately 44% of patients in whom the diagnosis is made, thus demonstrating the inadequacy of current medical therapy. In this report, we discuss a 47-year-old man with a known history of primary antiphospholipid syndrome, who presented with CAPS after undergoing cholecystectomy and a treatment-refractory early relapse after development of colitis. Given the potential therapeutic efficacy of complement inhibition in antiphospholipid syndrome, the patient was administered eculizumab, a terminal complement inhibitor. Progressive clinical improvement and laboratory improvement were observed upon initiation of eculizumab. He has remained in remission for over 16 months of follow-up while on eculizumab. In conclusion, this case represents successful use of eculizumab for the treatment of primary CAPS.

The alternative pathway of complement and the thrombotic microangiopathies

Thrombotic microangiopathies (TMA) are disorders defined by microangiopathic hemolytic anemia, non-immune thrombocytopenia and have multi-organ involvement including the kidneys, brain, gastrointestinal, respiratory tract and skin. Emerging evidence points to the central role of complement dysregulation in leading to microvascular endothelial injury which is crucial for the development of TMAs. This key insight has led to the development of complement-targeted therapy. Eculizumab is an anti-C5 monoclonal antibody, which has revolutionized the treatment of atypical hemolytic uremic syndrome. Several other anti-complement therapeutic agents are currently in development, offering a potential armamentarium of therapies available to treat complement-mediated TMAs. The development of sensitive, reliable and easy to perform assays to monitor complement activity and therapeutic efficacy will be key to devising an individualized treatment regime with the potential of safely weaning or discontinuing treatment in the appropriate clinical setting.