Systemic autoimmune disorders associated with thrombotic microangiopathy: A cross-sectional analysis from the French National TMA registry: Systemic autoimmune disease-associated TMA

Outcome of proliferative lupus nephritis with thrombotic microangiopathy; An ambispective observational single-center study

BACKGROUND

Thrombotic microangiopathy (TMA) represents a broad spectrum of diseases. The combination of TMA with lupus nephritis (LN) is associated with worse renal outcomes and a higher mortality rate. To date, there is no agreement on the therapeutic strategies that should be offered to TMA-LN patients.

OBJECTIVE

In this study, we compared the long-term outcomes of plasma exchange (PLEX) and cyclophosphamide (CYC) in a TMA-LN cohort.

METHODS

100 TMA-LN patients who received an induction of steroids and either PLEX or CYC less than 3 months from the start of the study, were selected from the medical records of Kasr Alainy hospitals, Cairo University. The patients were monitored for hematological and renal response at 3, 6, and 12 months.

FINDINGS

In PLEX arm, the mean creatinine level was 1.4 ± 0.7 mg/dl at baseline, decreased to 1.1 ± 0.5 mg/dl after 3 months, and returned to 1.4 ± 1.4 mg/dl at 6 and 12 months (p = 0.748). Proteinuria levels significantly decreased from 2.9 ± 0.7 9 gm/24 hrs at baseline to 0.4 ± 0.5 9 gm/24 hrs after 12 months (p < 0.001). PLT significantly increased over time with a mean of 65.6 ± 19.0 (x10₃)/L at baseline, increasing to 235.9 ± 54.3 (x10₃)/L after 12 months (p < 0.001). In CYC arm, the mean creatinine level of 1.2 ± 0.6 mg/dl was maintained from baseline through 6 months but significantly increased at 12 months with a mean of 1.9 ± 2.2 mg/dl (p = 0.005). Proteinuria levels significantly decreased with means of 3.3 ± 0.6 gm/24 hrs at baseline to 0.7 ± 0.9 gm/24 hrs after 12 months (p < 0.001). The PLT increased from 49.5 ± 19.0 (x10₃)/L to 198.9 ± 71.5 (x10₃)/L after 12 months (p < 0.001). At 3- and 12-month intervals, PLEX achieved sustained lower proteinuria (p < 0.001 and p = 0.047, respectively), higher PLT (p < 0.001 and p = 0.005, respectively), and higher complement 4 (p = 0.001 and p < 0.001, respectively), compared to CYC.

CONCLUSION

Both groups demonstrated significant improvements in renal and hematological outcomes with better long-term renal outcomes in the PLEX arm and comparable improvements in the hematological measures in both groups.

Vascular injury in glomerulopathies: the role of the endothelium

In glomerulopathies, endothelial dysfunction and the presence of histological vascular lesions such as thrombotic microangiopathy, arteriolar hyalinosis, and arteriosclerosis are related to a severe clinical course and worse renal prognosis. The endothelial cell, which naturally has anti-inflammatory and anti-thrombotic regulatory mechanisms, is particularly susceptible to damage caused by various etiologies and can become dysfunctional due to direct/indirect injury or a deficiency of protective factors. In addition, endothelial regulation and protection involve participation of the complement system, factors related to angiogenesis, the renin-angiotensin system (RAS), endothelin, the glycocalyx, the coagulation cascade, interaction between these pathways, interactions between glomerular structures (the endothelium, mesangium, podocyte, and basement membrane) and interstitial structures (tubules, arterioles and small vessels). Dysregulation of those components is also associated with the progression of renal fibrosis, since endothelial cell damage promotes endothelial-to-mesenchymal transition. Although the potential mechanisms of vascular injury have been widely described in diabetic kidney disease, hypertensive nephrosclerosis, and hemolytic uremic syndrome, they require further elucidation in other glomerulopathies. A better understanding of the pathogenesis of vascular injury in patients with glomerular diseases could contribute to the development of specific treatments for such injury.

Thrombotic Microangiopathies and the Kidney

Thrombotic microangiopathy (TMA) is a pathological lesion that occurs due to endothelial injury. It can be seen in a heterogenous group of disorders, typically characterized by microangiopathic hemolytic anemia, thrombocytopenia, and end-organ ischemia. TMA can also be renal limited with no systemic manifestations. There are multiple etiologies of a TMA with complement activation being a core underlying mechanism, although the nature and extent of complement involvement can vary. A further complicated factor is the cross talk between complement, neutrophils, and coagulation pathways in the pathophysiology of TMAs. Therefore, a thorough and systematic clinical history and laboratory evaluation are critical to establish the cause and pathophysiology of a TMA. Furthermore, TMAs are associated with significant morbidity and mortality, and timely diagnosis is key for appropriate management and to prevent end-stage kidney disease and other associated complications. In this review, we focus on the pathology, mechanisms, diagnostic work up and treatment of TMAs associated with various etiologies. We also define the complement evaluations that should be conducted in these patients and further highlight the currently approved complement therapies as well as others in the pipeline.

Under the dual effect of inflammation and pulmonary fibrosis, CTD-ILD patients possess a greater susceptibility to VTE

As an autoimmune disease, the persistent systemic inflammatory response associated with connective tissue disease (CTD) is involved in the development of venous thromboembolism (VTE). However, clinical data showed that the risk of VTE in patients differed between subtypes of CTD, suggesting that different subtypes may have independent mechanisms to promote the development of VTE, but the specific mechanism lacks sufficient research at present. The development of pulmonary fibrosis also contributes to the development of VTE, and therefore, patients with CTD-associated interstitial lung disease (CTD-ILD) may be at higher risk of VTE than patients with CTD alone or patients with ILD alone. In addition, the activation of the coagulation cascade response will drive further progression of the patient's pre-existing pulmonary fibrosis, which will continue to increase the patient's risk of VTE and adversely affect prognosis. Currently, the treatment for CTD-ILD is mainly immunosuppressive and antirheumatic therapy, such as the use of glucocorticoids and janus kinase-inhibitors (JAKis), but, paradoxically, these drugs are also involved in the formation of patients' coagulation tendency, making the clinical treatment of CTD-ILD patients with a higher risk of developing VTE challenging. In this article, we review the potential risk factors and related mechanisms for the development of VTE in CTD-ILD patients to provide a reference for clinical treatment and prevention.

Four clinical and biological phenotypes in antiphospholipid syndrome: a cluster analysis of 174 patients with antinuclear antibody tests

Introduction

Antiphospholipid syndrome (APS) is an autoimmune thrombotic disease with various systemic presentations. This study aimed to identify homogeneous groups of patients based on a non-supervised hierarchical cluster analysis and assess the rate of relapse associated with antinuclear antibodies (ANA).

Methods

This retrospective observational study enrolled patients, over a 90-month period, who had APS as defined by the 2006 Sydney classification criteria, and for whom ANA workup was performed. Agglomerative unsupervised hierarchical clustering was conducted to classify patients into subgroups using 24 variables reflecting a range of clinical and biological baseline features associated with APS.

Results

Hundred and seventy-four patients were included and were categorized into four phenotypes. Cluster 1 (n=73) associated mostly middle-aged men with risk factors for cardiovascular disease. Obstetrical APS with low-risk thrombosis made up cluster 2 (n=25). Patients with venous thromboembolism (VTE), microvascular findings and double/triple positive APL antibodies (50%) were represented in cluster 3 (n=33). Whereas cluster 4 (n=43) characterized a predominantly female subpopulation with positive ANA and systemic lupus (n=23) that exhibited a high thrombotic risk and more frequent relapses (n=38) (p<0.001).

Conclusions

This study identified four homogenous groups of patients with APS listed as: i) cardiovascular and arterial risk, ii) obstetrical, iii) VTE and microvascular, and iv) ANA-positive APS. We found that ANA-positivity was associated with higher rates of relapse. Applying ANA status to classification criteria could constitute a novel approach to tailoring management for APS, based on phenotypic patterns and risk assessment.

The estimated prevalence of antiphospholipid antibodies and criteria-antiphospholipid syndrome in subjects with renal thrombotic microangiopathy

BACKGROUND

While the prevalence of antiphospholipid antibodies (aPL) in venous and arterial thrombotic events had already been estimated by previous studies, the prevalence of aPL in subjects with Thrombotic Microangiopathy (TMA) is still not fully elucidated. Thus, we conducted a systematic review to estimate the frequency of aPL in subjects with biopsy-proven renal TMA.

METHODS

We conducted in the PubMed database a search for English-language studies investigating the presence of aPL in subjects with biopsy-proven renal TMA from January 1985 to December 2022. Keywords used in the search included: 'antiphospholipid syndrome', 'antiphospholipid antibodies' and 'thrombotic microangiopathy'. Cohorts of HUS patients were excluded due to the risk of over-estimating the prevalence of aPL in these populations. The median frequency for positive aPL including anticardiolipin antibodies (aCL), antibodies against β2-glycoprotein-I (anti-β2GPI) and lupus anticoagulant (LA) was then calculated.

RESULTS

522 articles were identified through the literature search. Six studies, assessing the prevalence of aPL in 211 subjects with renal TMA, were retrieved. The overall aPL prevalence was estimated as 24.4% (range 22-56). The estimated prevalence of aCL (IgG/IgM), anti-β2GPI, (IgG/IgM) and LA was 4.0% (range 3-27), 4.0% (range 3-16) and 18.9% (range 13-25), respectively. APS was diagnosed in 16.3% (range 11-29) of the patients. Of note, a high level of heterogeneity was observed when comparing the reported aPL profiles for each study.

CONCLUSIONS

This comprehensive systematic analysis of studies investigating the prevalence of aPL in renal TMA showed that, despite the high heterogeneity of the included studies, aPL are present in about one case out of four renal-TMA cases.

Unusual Presentations of Systemic Lupus Erythematosus: A Narrative Review

Systemic lupus erythematosus (SLE) is a chronic systemic autoimmune disease characterized by an almost 10:1 female predominance, the presence of deleterious nuclear autoantibodies, a tendency for flare, and striking protean manifestations. Early diagnosis is associated with less damage accrual, lower costs, and improved quality of life due to timely treatment. However, early disease may not uncommonly show nonspecific presentation, a single classification criterion, or an unusual organ involvement contributing to frequent, often substantial diagnostic delays. We reviewed the literature (1982-2022) to accumulate and classify all reports of rare, atypical, and unusual presentations. These can involve almost every organ and system, and thus, present to physicians in every discipline and setting. Increasing physicians' awareness of the potential of occult SLE to appear in varied, diverse, and unexpected presentations, may encourage the inclusion of SLE in the differential. Informed history and examination focusing on systemic and joint symptoms and mucocutaneous involvement, and basic tests (focusing on leukopenia, thrombocytopenia, and proteinuria; followed by antinuclear antibodies and complement levels) will correctly diagnose most patients on presentation or within the following months and enable timely treatment.