Complement activation in atypical hemolytic uremic syndrome and scleroderma renal crisis: a critical analysis of pathophysiology

Targeting complement dysregulation: eculizumab in scleroderma renal crisis management-a case-based review

Systemic sclerosis (SSc) poses significant challenges in clinical management, especially when complicated by scleroderma renal crisis (SRC), a rare but life-threatening manifestation. Here, we report a 41-year-old female patient with SSc who presented with SRC and concurrent thrombotic microangiopathy. Her condition persisted despite conventional treatments such as plasma exchange and renin-angiotensin-aldosterone system blockade. In particular, treatment with eculizumab, a C5 complement inhibitor, led to a rapid improvement in platelet count, reduction in lactate dehydrogenase levels, and complete recovery of renal function. Genetic testing revealed a variant of unknown significance in the thrombomodulin (THBD) gene, which is associated with the complement system. This case highlights the complex interplay between complement dysregulation and SRC, and highlights the promising role of eculizumab in refractory cases. Further investigation of complement involvement and the efficacy of eculizumab in SRC warrants attention to improving therapeutic outcomes in this challenging condition.

Studying the Role of C5-Inhibition Therapy in Scleroderma Renal Crisis-Induced Thrombotic Microangiopathy - A Review of Literature

BACKGROUND

The pathogenesis of scleroderma renal crisis (SRC) remains poorly understood but a growing body of evidence suggests that activation of the complement system may be involved in the disease. Recent studies have shown that Eculizumab (monoclonal antibody directed against the complement component C5) is effective in treating patients with SRC who present with symptoms of thrombotic microangiopathy (SRC-TMA).

OBJECTIVES

In this study, we conducted a systematic review to characterize the published experience of the presentation and outcome of patients with SRC who were treated with C5 inhibitor, Eculizumab.

METHODS

A literature search was conducted from inception to December 2022 using Medical Subject Headings (MeSH) terms for 'scleroderma', 'scleroderma renal crisis, and 'Eculizumab'. We included case reports, case series, and observational studies which reported the use of Eculizumab with or without Angiotensin-converting enzyme inhibitors (ACE-I) for the treatment of scleroderma renal crisis (SRC) in patients with systemic sclerosis.

RESULTS

The study included 17 patients, all of whom were treated with Eculizumab. Additionally, the use of ACE-I was reported in 11/17 (64.7%) patients. Further, plasmapheresis was used in 9/17 (52.9%), steroids in 5/17 (29.4%), cyclophosphamide in 3/17 (17.6%), calcium channel blockers in 3/17 (17.6%), and Rituximab in 3/17 (17.6%) patients. Renal replacement therapy was required in 11/17 (64.7%) patients. 14/17 patients (82.3%) were reported to have clinical (renal or hematologic) improvement with Eculizumab therapy (Table 1).

CONCLUSION

These findings should prompt testing on a larger cohort of SRC-TMA patients. This would help us determine whether aggressive treatment combining ACE-I and Eculizumab can target the various underlying endothelial, inflammatory, and immunologic mechanisms involved in SRC-TMA, and improve patient outcomes.

Atypical hemolytic uremic syndrome in the Colombian Caribbean: its particular characteristics

Introduction

Atypical hemolytic uremic syndrome (aHUS) is a rare and genetically mediated systemic disease most often caused by uncontrolled and chronic complement activation that leads to systemic thrombotic microangiopathy, renal and extra-renal damage.

Materials and methods

This is descriptive, retrospective and multicenter study, which reports demographic, clinical, laboratory, and genetic characteristics, as well as their treatment response and outcome of 20 aHUS patients diagnosed between 2014 and 2018.

Results

Most patients were female adults (75%) and 30% were associated to pregnancy/postpartum, 15% to autoimmune disease, and 65% to infections. Gastrointestinal involvement (75%) was the most frequent extra-renal organ damage. Antenatal mortality and mortality rate were 5% and 10%, respectively. 25% of the patients progressed to end-stage renal disease. In 4/8 of patients treated within 1 week of presentation, eculizumab treatment restored multi-organ function after 4 weeks of treatment. CFH (37%) and CFI (25%) mutations were the most frequent.

Conclusion

This is the first series of aHUS cases of Colombian Caribbean region which reports the clinical and epidemiological characteristics of this condition in this region.

Refractory scleroderma renal crisis precipitated after high-dose oral corticosteroids and concurrent intravitreal injection of bevacizumab

Scleroderma renal crisis is a serious complication that can develop in certain patients with systemic sclerosis. Some risks have been identified as potential triggers of scleroderma renal crisis, including the high-dose oral corticosteroids. Here, we present a patient who developed clinically severe systemic sclerosis and scleroderma renal crisis after exposure to oral corticosteroids and intravitreal vascular endothelial growth factor blockade with bevacizumab for cotton wool spots. The patient's scleroderma renal crisis was severe, progressive, and refractory to the standard of care therapy: oral captopril. Biopsy showed a diffuse thrombotic microangiopathy and findings consistent with scleroderma renal crisis. We hypothesize that depletion of systemic vascular endothelial growth factor with intravitreal anti-vascular endothelial growth factor injections likely contributed to the particularly severe presentation seen in this case. Though the finding of a monoclonal gammopathy of undetermined significance is another complicating factor, this case suggests that vascular endothelial growth factor inhibition may be a newly recognized trigger of scleroderma renal crisis.