Clinical significance of antiphospholipid syndrome nephropathy (APSN) in patients with systemic lupus erythematosus (SLE)

Antiphospholipid syndrome nephropathy: Current knowledge and unanswered questions

The definition of acute and chronic antiphospholipid syndrome (APS) nephropathy was recently updated using a multiphase methodology in the context of the development of the new APS classification criteria. Currently, there is no consensus for the treatment of APS nephropathy, which mainly relies on the general recommendations for the management of APS. Based on evidence from experimental studies and a few clinical studies and case series, targeted treatments such as B-cell depletion, anti-B-cell activating factor antibody, complement inhibition, mammalian target of rapamycin inhibition, and neutrophil extracellular traps or interferon targeting may show promise for the treatment of microvascular manifestations in APS, including APS nephropathy. Validation of the new APS nephropathy definition and/or efforts for improvement in proposed terminology, along with the assessment of the safety and efficacy of potential targeted treatments in randomized controlled trials, are major future research directions. In this review, we summarize the current knowledge of APS nephropathy and discuss unanswered questions.

Increased risk of acute and chronic microvascular renal lesions associated with antiphospholipid antibodies in patients with systemic lupus erythematosus: A systematic review and meta-analysis

BACKGROUND

Microvascular renal lesions have been described in patients with antiphospholipid antibodies (aPL), however their association with aPL is inconsistent among studies. Therefore, our objective was to investigate associations between microvascular renal lesions and aPL among systemic lupus erythematosus (SLE) patients.

METHODS

Studies were selected if they included SLE patients with and without aPL positivity with a description of kidney biopsy identifying acute and/or chronic microvascular renal lesions as well as lupus nephritis. Data sources were Pubmed, Embase, Cochrane Library, hand search, congress abstracts, and reference lists of studies, without language restrictions. Risk estimates were independently extracted by 2 investigators. Pooled effect estimates were obtained by using the Mantel-Haenszel method (random effects).

RESULTS

Of 1860 identified records obtained between 1991 and 2021, 35 published studies (10 cohorts, 7 case-control, 18 cross-sectional) met inclusion criteria, including 3035 SLE patients according to American College of Rheumatology criteria and 454 cases of microvascular renal lesions. Frequency of microvascular renal lesions in aPL-positive vs. aPL-negative SLE patients was 31.3% vs. 10.4%, respectively. The overall pooled odds ratios (OR) for microvascular renal lesions in aPL-positive vs. aPL-negative SLE patients was 3.03 (95% confidence interval [CI], 2.25-4.09). The risk of microvascular renal lesions was the highest for lupus anticoagulant (OR = 4.84 [95% CI, 2.93 to 8.02]) and IgG anticardiolipin antibodies (OR = 3.12 [95% CI,1.08-9.02]) while the association with anti-β₂-glycoprotein I antibodies (OR = 1.88 [95% CI, 0.25-14.14]) did not reach statistical significance. Furthermore, aPL were not associated with any classes of lupus nephritis.

CONCLUSION

In SLE patients, aPL-positivity is associated with a significant 3- to 5-fold increased risk for specific microvascular renal lesions. This risk is mainly driven by lupus anticoagulant and IgG anticardiolipin antibodies. Our results support the inclusion of microvascular renal lesions as new criteria for definite antiphospholipid syndrome.

Autoimmune-mediated renal disease and hypertension

Hypertension is a major risk factor for cardiovascular disease, chronic kidney disease (CKD), and mortality. Troublingly, hypertension is highly prevalent in patients with autoimmune renal disease and hastens renal functional decline. Although progress has been made over the past two decades in understanding the inflammatory contributions to essential hypertension more broadly, the mechanisms active in autoimmune-mediated renal diseases remain grossly understudied. This Review provides an overview of the pathogenesis of each of the major autoimmune diseases affecting the kidney that are associated with hypertension, and describes the current state of knowledge regarding hypertension in these diseases and their management. Specifically, discussion focuses on Systemic Lupus Erythematosus (SLE) and Lupus Nephritis (LN), Immunoglobulin A (IgA) Nephropathy, Idiopathic Membranous Nephropathy (IMN), Anti-Neutrophil Cytoplasmic Antibody (ANCA)-associated glomerulonephritis, and Thrombotic Thrombocytopenic Purpura (TTP). A summary of disease-specific animal models found to exhibit hypertension is also included to highlight opportunities for much needed further investigation of underlying mechanisms and novel therapeutic approaches.

Management of Non-criteria Manifestations in Antiphospholipid Syndrome

PURPOSE OF THE REVIEW

To review the available evidence on the management of a variety of non-criteria manifestations in antiphospholipid syndrome (APS), including valvular disease, alveolar hemorrhage, thrombocytopenia, hemolytic anemia, APS nephropathy, skin ulcers, livedo reticularis, cognitive dysfunction, and epilepsy.

RECENT FINDINGS

Current treatment relies on low-level evidence and mainly on expert consensus due to the rarity and the heterogeneity of non-criteria APS manifestations and the diversity in management approaches. Conventional anticoagulation and/or antiplatelet APS treatment do not adequately control most of non-criteria manifestations. Increasing knowledge about the contribution of inflammatory in addition to, or independently of, thrombotic mechanisms in non-criteria APS manifestations provides insight into the potential effect of novel therapies targeting B-cells, mammalian target of rapamycin, neutrophil, and complement or interferon pathways. Existing evidence is limited by lack of high-quality studies. Better understanding of the pathophysiology and clinical phenotypes of APS and well-designed prospective studies of homogenous populations are needed to provide evidence-based recommendations for the management of non-criteria APS manifestations.

The antiphospholipid syndrome - often overlooked cause of vascular occlusions?

The antiphospholipid syndrome (APS) was fully recognized as a clinical entity in the early 1980s. Still, more than 30 years later, the epidemiology of APS is not well described, and furthermore, APS remains a challenge in terms of both diagnostic issues and clinical praxis involving a wide range of specialties. To date, there are no diagnostic criteria for APS. The present classification criteria rely on a combination of clinical manifestations and persistently positive tests for antiphospholipid antibodies (aPL). Clinical symptoms comprise vascular thrombosis, which can affect any vascular bed, including venous, microvascular and arterial vessels, and a set of pregnancy morbidities including early and late miscarriages, foetal death and preeclampsia. APS is more frequent among patients with other autoimmune diseases, and it is especially common in systemic lupus erythematosus (SLE). Importantly, APS symptoms can present in almost any medical specialty, but general knowledge and most previous clinical studies have essentially been confined to haematology, rheumatology and obstetrics/gynaecology. However, recent data demonstrate a relatively high prevalence of aPL also in patients from the general population who suffer from vascular occlusions or pregnancy complications. It is important that these patients are recognized by the general health care since APS is a treatable condition. This review aims to summarize the present knowledge on the history, pathogenesis, clinical manifestations and treatment of APS in order to urge a wide range of clinicians to consider comprehensive assessment of all patients where the diagnosis APS may be conceivable.

Thrombotic Microangiopathies with Rheumatologic Involvement

Thrombotic microangiopathies are heterogeneous disorders characterized by microangiopathic hemolytic anemia with thrombocytopenia and renal injury. There are a variety of causes, including metabolic disorders, infections, medications, complement disorders, pregnancy, malignancy, and autoimmune disorders. This review focuses on renal thrombotic microangiopathy in the setting of rheumatologic diseases. Systemic lupus erythematosus is the most common autoimmune disease associated with thrombotic microangiopathy. Other etiologies include scleroderma renal crisis and antiphospholipid antibody syndrome, which can be primary or secondary to autoimmune diseases including systemic lupus erythematosus. There have also been case reports of thrombotic microangiopathy in the setting of rheumatoid arthritis and dermatomyositis.

Antiphospholipid Syndrome Nephropathy: From Pathogenesis to Treatment

Kidney damage is a well-recognized complication of the antiphospholipid syndrome (APS), either primary or systemic lupus erythematosus (SLE)-associated APS. Kidney involvement in APS involves a variety of manifestations, such as renal artery thrombosis or stenosis, renal vein thrombosis, allograft loss due to thrombosis after kidney transplantation, and injury to the renal microvasculature, also known as APS nephropathy. Biopsy in patients with APS nephropathy includes acute thrombotic microangiopathy lesions and chronic intrarenal vascular lesions such as interlobular fibrous intimal hyperplasia, arterial and arteriolar recanalizing thrombosis, fibrous arterial occlusion, and focal cortical atrophy. The most frequent clinical features are hypertension, microscopic hematuria, proteinuria (ranging from mild to nephritic levels), and renal insufficiency. It is uncertain whether antiphospholipid antibodies or other factors are implicated in the development of APS nephropathy, and whether it is driven mainly by thrombotic or by inflammatory processes. Experimental models and clinical studies of thrombotic microangiopathy lesions implicate activation of the complement cascade, tissue factor, and the mTORC pathway. Currently, the management of APS nephropathy relies on expert opinion, and consensus is lacking. There is limited evidence about the effect of anticoagulants, and their use remains controversial. Treatment approaches in patients with APS nephropathy lesions may include the use of heparin based on its role on complement activation pathway inhibition or the use of intravenous immunoglobulin and/or plasma exchange. Targeted therapies may also be considered based on potential APS nephropathy pathogenetic mechanisms such as B-cell directed therapies, complement inhibition, tissue factor inhibition, mTOR pathway inhibition, or anti-interferon antibodies, but prospective multicenter studies are needed to address their role.

Renal Involvement in Antiphospholipid Syndrome

Antiphospholipid syndrome is a complex autoimmune disease, characterized by the presence of vascular thrombosis, obstetric, hematologic, cutaneous, and cardiac manifestations. Renal disease in patients with antiphospholipid syndrome was not recognized in the first descriptions of the disease, but later on, the renal manifestations of the syndrome have been investigated widely. Renal manifestations of antiphospholipid syndrome conform a wide spectrum of diverse renal syndromes. Hypertension is one of the most frequent, but less commonly recognized renal alteration. It can be difficult to control as its origin is renovascular. Renal vascular thrombosis can be arterial or venous. Other alterations are renal infarction and vascular thrombosis in arterial territories. Venous thrombosis can be present in primary and secondary antiphospholipid syndrome; it presents with worsening of previous proteinuria or de novo nephrotic syndrome, hypertension and renal failure. Antiphospholipid syndrome nephropathy is a vascular disease that affects glomerular tuft, interstitial vessels, and peritubular vessels; histopathology characterizes the renal lesions as acute or chronic, the classic finding is thrombotic microangiopathy, that leads to fibrosis, tubule thyroidization, focal cortical atrophy, and glomerular sclerosis. Antiphospholipid syndrome nephropathy can also complicate patients with systemic lupus erythematosus, and there is vast information supporting the worse renal prognosis in this group of patients with the classic histopathologic lesions. Treatment consists of anticoagulation, as for other thrombotic manifestations of antiphospholipid syndrome. There is some evidence of glomerulonephritis as an isolated lesion in patients with antiphospholipid syndrome. The most frequently reported glomerulonephritis is membranous; with some reports suggesting that immunosuppressive treatment may be effective. Patients with end stage renal disease commonly are positive for antiphospholipid antibodies, but it is not clear what is the role of aPL in this setting. Patients with vascular access may have complications in the presence of antibodies so that anticoagulation is recommended. Patients ongoing renal transplant with persistent antiphospholipid antibody positivity may have early and late graft failure.

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.

Beta2-glycoprotein I Expression in Lupus Nephritis Patients with Antiphospholipid-associated Nephropathy

OBJECTIVE

Antiphospholipid-associated nephropathy (aPLN) is a severe condition in patients with lupus nephritis (LN). aPLN should be distinguished from other reasons for renal ischemia. The most important cofactor of antiphospholipid antibodies (aPL), β2-glycoprotein I (β2GPI), was shown in vitro to bind endothelial cells and to induce a procoagulant phenotype. The objectives of this study were to investigate whether β2GPI expression was involved in patients with LN with aPLN and to determine its specificity.

METHODS

We retrospectively investigated β2GPI expression in 231 renal biopsy specimens of patients with LN. Data from biopsy reports and clinical information were collected. Immunohistochemical staining for β2GPI expression was performed.

RESULTS

Histological aPLN was detected in 88 patients with LN (38.1%). The LN with aPLN consisted of 43 patients (18.6%). Expression of β2GPI was detected in endothelial cells in 14 (32.6%) in renal arteries or arterioles, 11 (25.6%) in glomerular or peritubular capillaries, and a total of 15 (34.9%) of the 43 patients with LN with aPLN. It was mainly expressed in the endothelial cells in patients with LN with aPLN (p < 0.05). The specificity of β2GPI expression in patients with LN with aPLN was 97.5%.

CONCLUSION

Expression of β2GPI may be involved in the formation of aPLN in patients with LN. This expression in endothelial cells in kidney tissue may be considered a useful marker for aPLN.

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.

The Revisited Classification of GN in SLE at 10 Years: Time to Re-Evaluate Histopathologic Lesions

Over 10 years have passed since the latest revision of the histopathologic classification of lupus nephritis. This revision was a significant improvement compared with the previous version, mainly because of clearer and more concise definitions and the elimination of mixed subclasses. Despite these improvements, there are still some difficulties in the classification for lupus nephritis, many of which are in the definitions provided. In this review, we focus on the difficulties surrounding the evaluation of classes III and IV lesions, particularly the definitions of endocapillary and extracapillary proliferation, the use of the terms endocapillary proliferation and hypercellularity, the clinical relevance of segmental and global subdivision in class IV, and the value of distinguishing lesions that indicate activity and chronicity. Vascular and tubulointerstitial lesions are also discussed. Furthermore, we give an overview of the history of the classification to provide background on the origin and development of the definitions in lupus nephritis. The issues raised in this review as well as the suggestions for improvements may assist with a revision of the lupus nephritis classification in the near future.

Prognostic factors for treatment response in patients with lupus nephritis

OBJECTIVE

To identify prognostic factors associated with response to induction therapy in lupus nephritis (LN) according to the stage of treatment.

MATERIAL AND METHODS

We analyzed a retrospective cohort of patients of systemic lupus erythematosus (SLE) with biopsy-proven LN from January 2001 to December 2008. LN was classified according to WHO. All patients received induction therapy and had a minimum follow-up period of two years. We analyzed 18 clinical and laboratory variables that potentially have predictive value for response to therapy. We identified predictors of therapeutic response at 6, 12 and 24 months by univariate and multivariate analysis; odds ratios (OR) with confidence intervals (CI) 95% were also calculated.

RESULTS

We reviewed the clinical records of 168 patients, 141 female (84%). The response rate was 69% at 6 months, 86.9% at 12 months and 79.7% at 24 months. Multivariate analysis found that > 25 years of age at diagnosis of LN and the presence of microhematuria were factors associated with good response to induction treatment. At 12 months, baseline creatinine clearance < 30ml/min was associated with a poor response to treatment. Finally at 24 months, delay in treatment was a predictor of poor response to treatment and the presence of a histological proliferative NL and low C3 were associated with good response to treatment.

CONCLUSIONS

There are treatment-modifiable factors that can alter aberrant immunologic activity of NF. Therefore, intensive early treatment of lupus nephritis is associated with favorable response to two years.

Nephropathy associated with antiphospholipid antibodies in patients with systemic lupus erythematosus

BACKGROUND

Nephropathy associated with antiphospholipid antibodies (aPL) has been proposed as a risk factor of worse renal prognosis in patients with systemic lupus erythematosus (SLE). The purpose of the current study was to evaluate the prevalence of aPL-associated nephropathy (aPLN) among patients with lupus nephritis and to describe their functional renal outcome.

METHODS

A total of 79 renal biopsies from 77 patients followed at the Hospital Clinic, Spain were analysed. Each renal biopsy was evaluated by a pathologist who was blinded to the aPL status. Thrombotic microangiopathy (TMA), fibrous intimal hyperplasia (FIH), fibrocellular arterial occlusion (FAO), focal cortical atrophy (FCA), and tubular thyroidization as lesions suggestive of aPLN were identified.

RESULTS

aPLN was found in nine (11.4%) biopsies. TMA was found in three (33.3%) cases whereas chronic aPLN, represented by FIH and FCA, was found in four (44.4%) and three (33.3%) cases, respectively. A significant association between the presence of aPL and aPLN was found (p = 0.003). Patients with lupus anticoagulant (LA) plus IgG anticardiolipin antibodies (aCL) showed an increased prevalence of aPLN (OR: 3.61, 95% CI 1.28-5.14; p = 0.002). Creatinine levels were significantly increased in patients with aPLN compared with those with aPL without aPLN (p = 0.038). However, no significant difference in complete remission, partial remission, not response, and established renal damage between groups was observed at the end of follow-up.

CONCLUSIONS

The aPL have an important role in the pathogenesis of renal lesions in SLE patients. Prospective studies are needed to address the role of aPLN in the long-term outcome of SLE patients with positive aPL.