Clinical characteristics and outcomes of a patient population with atypical hemolytic uremic syndrome and malignant hypertension: analysis from the Global aHUS registry

Haemolytic uremic syndrome as a cause of chronic kidney disease stage 5 in children is in retreat: results from the Polish Registry of Kidney Replacement Therapy in children (2000-2023)

BACKGROUND

Haemolytic uremic syndrome (HUS) is a life-threatening disease with a historically poor prognosis in children receiving maintenance kidney replacement therapy (KRT). This study aimed to analyse the incidence and outcome of chronic kidney disease stage 5 (CKD5) due to Escherichia coli-HUS (STEC-HUS) and complement-mediated HUS (CM-HUS) in children, compared with controls with non-HUS CKD5 over the last 24 years.

METHODS

The study included 1488 children undergoing KRT in Poland between 2000 and 2023. Thirty-nine patients with CM-HUS and 18 with STEC-HUS were identified and analysed for incidence, KRT modality and survival.

RESULTS

The incidence rate of CKD5 was 0.09 cases/million age-related population (marp) for STEC-HUS and 0.23/marp for CM-HUS, while no new cases have been observed in recent years. CKD5 due to CM-HUS developed significantly earlier from initial HUS manifestation than in STEC-HUS (median 0.2 vs. 9.8 years). CM-HUS was associated with younger age at initiation of KRT compared to STEC-HUS and non-HUS controls (median 6.0 years vs. 10.9 and 10.9 years), with higher risk of death (Hazard Ratio 1.92, 95% confidence interval 0.9-4.13) and worse 5-year kidney graft survival at 77%, 93% and 90%, respectively (p < 0.001).

CONCLUSIONS

In recent years, both CM-HUS and STEC-HUS have become increasingly rare causes of CKD5 in children. CKD5 due to CM-HUS in the eculizumab era and due to STEC-HUS after improving supportive treatment is exceptional. Children on KRT due to STEC-HUS had a significantly better survival, shorter waiting time for kidney transplantation and better kidney graft survival compared to the CM-HUS group.

Kidney outcomes of malignant hypertension-associated thrombotic microangiopathy in patients with and without IgA nephropathy: a propensity score-matched analysis

Background

IgA nephropathy (IgAN) can cause hypertension, and severe hypertension can exacerbate the progression of IgAN. However, the long-term kidney outcome of malignant hypertension (mHTN)-associated thrombotic microangiopathy (TMA) with IgAN is not well defined.

Methods

A total of 292 individuals with mHTN-associated TMA confirmed by kidney biopsy were included. Propensity score matching (PSM) analysis was performed to adjust for clinical characteristics in the comparison between cases with and without IgAN. Cox regression analysis was utilized to identify risk factors associated with long-term kidney outcome.

Results

A total of 86 mHTN-associated TMA with IgAN patients were compared with 206 mHTN-associated TMA with non-IgAN patients. After PSM, 61 pairs of patients with mHTN-associated TMA were matched. The mHTN-associated TMA with IgAN patients exhibited significantly lower serum albumin, higher 24-hour proteinuria, and a higher ratio of global sclerosis than those with non-IgAN. mHTN-associated TMA with IgAN was independently associated with impaired kidney function recovery [hazard ratio (HR), 0.48; 95% confidence interval (CI), 0.24-0.96, P = .038] compared with non-IgAN. This association remained significant after PSM (HR, 0.41; 95% CI, 0.17-0.99, P = .047). In addition, mHTN-associated TMA with IgAN was independently associated with kidney replacement therapy (KRT) compared with non-IgAN (HR, 2.31; 95% CI, 1.38-3.88; P = .002). This difference remained significant after PSM comparison (HR, 2.38; 95%CI, 1.14-4.99; P = .021). In addition, mHTN-associated TMA with IgAN patients had a higher incidence of receiving KRT and a lower incidence of kidney function recovery with a 25% reduction in creatinine levels than in non-IgAN patients, regardless of intensive blood pressure control.

Conclusions

The long-term kidney outcomes for mHTN-associated TMA patients with concomitant IgAN are significantly poorer than that of patients with non-IgAN. Monitoring kidney pathological characteristics will aid management and risk assessment at an early stage.

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.

Glomerular Hematuria as a Predictor of Renal Prognosis in Malignant Hypertension Patients with Thrombotic Microangiopathy: A Propensity Score-Matched Analysis of a Biopsy-Based Cohort Study

Introduction

Malignant hypertension (mHTN) is a hypertensive emergency. Thrombotic microangiopathy (TMA) is a widespread complication of mHTN. Few studies have evaluated whether glomerular hematuria provides prognostic information for renal dysfunction in patients with mHTN-associated TMA.

Methods

This observational cohort study included 292 patients with mHTN-associated TMA based on renal biopsy. Propensity-score matching (PSM) analysis was conducted to adjust for clinical characteristics in a comparison between with and without glomerular hematuria. Cox regression was employed to identify risk factors for renal prognosis.

Results

A total of 70 patients with glomerular hematuria were compared to 222 patients with non-glomerular hematuria. After PSM, 67 pairs of patients with mHTN-associated TMA were matched. Patients with glomerular hematuria exhibited lower serum albumin levels, higher 24-h proteinuria, and a higher prevalence of glomerular sclerosis than those with non-glomerular hematuria. Glomerular hematuria was independently associated with deteriorated renal function compared with non-glomerular hematuria (HR: 0.51; 95% CI: 0.29-0.89, p = 0.019). This association remained significant after PSM (HR: 0.51; 95% CI: 0.28-0.91, p = 0.022). Additionally, glomerular hematuria was independently associated with renal replacement therapy (RRT) (HR: 3.14; 95% CI: 2.06-5.66, p < 0.001). This difference remained significant after PSM comparison (HR: 2.41; 95% CI: 1.34-4.33, p = 0.003). Furthermore, despite intensive blood pressure control, patients with glomerular hematuria experienced a higher incidence of RRT and a poorer recovery in renal function, specifically a 25% reduction of creatinine levels, compared to patients with non-glomerular hematuria.

Conclusion

Glomerular hematuria is significantly associated with an increased risk of adverse renal outcomes in patients with mHTN-associated TMA.

Eculizumab for adult patients with atypical haemolytic-uraemic syndrome: full dataset analysis of Japanese post-marketing surveillance

BACKGROUND

Eculizumab has been approved for atypical haemolytic-uraemic syndrome (aHUS) in Japan since 2013. Post-marketing surveillance enrolled patients with aHUS who received ≥ 1 dose of eculizumab to assess eculizumab safety and effectiveness.

METHODS

We evaluated serious adverse events and effectiveness endpoints, i.e., haematologic normalization, a decrease of ≥ 25% in serum creatinine (sCr) levels, and complete thrombotic microangiopathy (TMA) response in adult patients with aHUS without other underlying diseases. In addition, the difference of baseline characteristics between patients who did and did not meet effectiveness endpoints was examined.

RESULTS

In this safety and effectiveness analysis, 79 adult patients were included; median age was 54.0 years, median treatment duration was 30 weeks. Total exposure time of eculizumab was 75.51 patient-years, and 94 serious adverse events were reported in 39 patients. No unexpected safety signals were identified in this population. Mean platelet count, lactate dehydrogenase and estimated glomerular filtration rate significantly improved after 7 days of treatment. Complete TMA response, haematologic normalization and the improvement of sCr levels were met by 35.3%, 40.4% and 51.3% of patients, respectively. Median treatment duration was shorter in patients who did not achieve complete TMA response (6 weeks) than in patients who did (114 weeks). Multivariate analysis suggested that the time from the most recent TMA episode to start of eculizumab treatment was negatively associated with kidney function improvement.

CONCLUSIONS

No unexpected safety signals of eculizumab were identified in Japanese patients with aHUS in a real-world setting. Renal outcomes were negatively associated with the time from the most recent TMA episode to the initiation of eculizumab treatment.

Association of Atypical Hemolytic Uremic Syndrome With Wilms' Tumor 1 Gene Mutations: A Case Series and Literature Review

Atypical hemolytic uremic syndrome (aHUS) is a life‑threatening condition characterized by microangiopathic hemolytic anemia, thrombocytopenia, as well as acute kidney injury (AKI). It can occur primarily due to complement gene mutations or secondary to another underlying condition. Several cases with Wilms' tumor gene 1 (WT1) mutations that presented with aHUS have been reported. Here, we report four cases of children diagnosed with WT1 mutations and presented initially with aHUS. There are two boys and two girls who presented with thrombotic microangiopathy (TMA), high lactate dehydrogenase, fragmented red blood cell (RBCs), and severe hypertension. All of them were anuric from the first presentation. Therapy with C5 inhibitors was initiated immediately and was associated with hematological remission without renal recovery. Renal replacement therapy (RRT) was started for all of the patients. A renal biopsy was conducted on two patients and showed global glomerulosclerosis. A genetic study identified pathogenic mutations in the WT1 gene. Two of the patients became dialysis dependent, and two patients underwent renal transplantation without the recurrence of aHUS. Our case series emphasizes that a diagnosis of WT1 mutation can be considered in children with aHUS with severe renal manifestations without a response to C5 inhibitors and with global glomerulosclerosis on renal biopsy. To our knowledge, this is the first report of a series of cases of WT1 mutations in pediatric patients presenting with clinical manifestation manifestations of aHUS. This unique finding highlights an association between HUS and WT1 mutation.

Characterization of patients with aHUS and associated triggers or clinical conditions: A Global aHUS Registry analysis

INTRODUCTION

Atypical haemolytic uremic syndrome (aHUS) is a rare form of thrombotic microangiopathy (TMA) associated with complement dysregulation; aHUS may be associated with other 'triggers' or 'clinical conditions'. This study aimed to characterize this patient population using data from the Global aHUS Registry, the largest collection of real-world data on patients with aHUS.

METHODS

Patients enrolled in the Global aHUS Registry between April 2012 and June 2021 and with recorded aHUS-associated triggers or clinical conditions prior/up to aHUS onset were analysed. aHUS was diagnosed by the treating physician. Data were classified by age at onset of aHUS (< or ≥18 years) and additionally by the presence/absence of identified pathogenic complement genetic variant(s) and/or anti-complement factor H (CFH) antibodies. Genetically/immunologically untested patients were excluded.

RESULTS

1947 patients were enrolled in the Global aHUS Registry by June 2021, and 349 (17.9%) met inclusion criteria. 307/349 patients (88.0%) had a single associated trigger or clinical condition and were included in the primary analysis. Malignancy was most common (58/307, 18.9%), followed by pregnancy and acute infections (both 53/307, 17.3%). Patients with an associated trigger or clinical condition were generally more likely to be adults at aHUS onset.

CONCLUSION

Our analysis suggests that aHUS-associated triggers or clinical conditions may be organized into clinically relevant categories, and their presence does not exclude the concurrent presence of pathogenic complement genetic variants and/or anti-CFH antibodies. Considering a diagnosis of aHUS with associated triggers or clinical conditions in patients presenting with TMA may allow faster and more appropriate treatment.

Clinical presentation and management of atypical hemolytic uremic syndrome in Latin America: a narrative review of the literature

INTRODUCTION

Comprehensive information about atypical hemolytic uremic syndrome (aHUS) is relatively scarce outside of Europe and North America. This narrative review assembles available published data about the clinical presentation and management of aHUS in Latin America.

AREAS COVERED

A search conducted in February 2023 of the MEDLINE (from inception), Embase (from inception), and LILACS/IBECS (1950 to 2023) databases using search terms 'atypical hemolytic uremic syndrome' and 'Latin America' and their variations retrieved 51 records (full papers and conference abstracts) published in English, Spanish, or Portuguese. After de-duplication, manual screening of titles/abstracts and addition of author-known articles, 25 articles were included of which 17 (68%) are full papers. All articles were published during the years 2013-2022. Articles include cohort studies, a registry analysis, and case reports from Argentina, Brazil, Chile and Columbia. Overall, Latin American patients with aHUS present the classic epidemiological, clinical, and genetic characteristics associated with this condition as described in other world regions. Depending on the country and time of reporting, aHUS in Latin America was treated mainly with plasma therapy and/or eculizumab. Where reported, eculizumab substantially improved aHUS-related outcomes in almost all adult and pediatric patients.

EXPERT OPINION

Eculizumab has dramatically altered the natural course of aHUS, improving prognosis and patient outcomes. Addressing economic challenges and investing in healthcare infrastructure will be essential to implement strategies for timely detection and early treatment of aHUS in Latin America.

Assessment of epidemiology and outcomes of adult patients with kidney-limited thrombotic microangiopathies

Thrombotic microangiopathies (TMA) are usually associated with hematological features (RH-TMA). The epidemiology of TMA limited to kidneys (RL-TMA) is unclear Therefore, patients with TMA and native kidney biopsies were identified during 2009-2022 in 20 French hospitals and results evaluated. RL-TMA was present in 341/757 (45%) patients and associated with lower creatinine levels (median 184 vs 346 μmol/L) than RH-TMA. RL-TMA resulted from virtually all identified causes, more frequently from anti-VEGF treatment and hematological malignancies but less frequently from shigatoxin-associated hemolytic uremic syndrome (HUS), systemic sclerosis, gemcitabine and bacterial infection, and even less frequently when three or more causes/triggers were combined (RL-TMA: 5%; RH-TMA: 12%). RL-TMA was associated with significantly lower major cardiovascular events (10% vs 20%), kidney replacement therapy (23% vs 43%) and death (12% vs 20%) than RH-TMA during follow-up (median 28 months). Atypical HUS (aHUS) was found in 326 patients (RL-TMA: 43%, RH-TMA: 44%). Among the 69 patients with proven complement-mediated aHUS, eculizumab (anti-C5 therapy) was used in 43 (62%) (RL-TMA: 35%; RH-TMA: 71%). Among the 257 other patients with aHUS, including 51% with RL-TMA, eculizumab was used in 29 but with unclear effects of this treatment. Thus, RL-TMA represents a very high proportion of patients with TMA and results from virtually all known causes of TMA and includes 25% of patients with complement-mediated aHUS. Adverse outcomes of RL-TMA are lower compared to RH-TMA but remain significant. Anti-C5 therapy was rarely used in RL-TMA, even in proven complement-mediated aHUS, and its effects remain to be assessed.

Thrombotic microangiopathies after kidney transplantation in modern era: nosology based on chronology

BACKGROUND

Thrombotic microangiopathies (TMAs) are rare but can be severe in kidney transplant. recipients (KTR).

METHODS

We analysed the epidemiology of adjudicated TMA in consecutive KTR during the. 2009-2021 period.

RESULTS

TMA was found in 77/1644 (4.7%) KTR. Early TMA (n = 24/77 (31.2%); 1.5% of all KTR) occurred during the first two weeks ((median, IQR) 3 [1-8] days). Triggers included acute antibody-mediated rejection (ABMR, n = 4) and bacterial infections (n = 6). Graft survival (GS) was 100% and recurrence rate (RR) was 8%. Unexpected TMA (n = 31/77 (40.2%); 1.5/1000 patient-years) occurred anytime during follow-up (3.0 (0.5-6.2) years). Triggers included infections (EBV/CMV: n = 10; bacterial: n = 6) and chronic active ABMR (n = 5). GS was 81% and RR was 16%. Graft-failure associated TMA (n = 22/77 (28.6%); 2.2% of graft losses) occurred after 8.8 (4.9-15.5) years). Triggers included acute (n = 4) or chronic active (n = 14) ABMR, infections (viral: n = 6; bacterial: n = 5) and cancer (n = 6). 15 patients underwent transplantectomy. RR was 27%. Atypical (n = 6) and typical (n = 2) haemolytic and uremic syndrome, and isolated CNI toxicity (n = 4) were rare. Two-third of biopsies presented TMA features.

CONCLUSIONS

TMA are mostly due to ABMR and infections; causes of TMA are frequently combined. Management often is heterogenous. Our nosology based on TMA timing identifies situations with distinct incidence, causes and prognosis.

Propensity score-matched analysis of long-term outcomes for living kidney donation in alternative complement pathway diseases: a pilot study

BACKGROUND

Atypical hemolytic syndrome (aHUS) and C3 glomerulopathy (C3G) are complement-mediated rare diseases with excessive activation of the alternative pathway. Data to guide the evaluation of living-donor candidates for aHUS and C3G are very limited. The outcomes of living donors to recipients with aHUS and C3G (Complement disease-living donor group) were compared with a control group to improve our understanding of the clinical course and outcomes of living donation in this context.

METHODS

Complement disease-living donor group [n = 28; aHUS(53.6%), C3G(46.4%)] and propensity score-matched control-living donor group (n = 28) were retrospectively identified from 4 centers (2003-2021) and followed for major cardiac events (MACE), de novo hypertension, thrombotic microangiopathy (TMA), cancer, death, estimated glomerular filtration rate (eGFR) and proteinuria after donation.

RESULTS

None of the donors for recipients with complement-related kidney diseases experienced MACE or TMA whereas two donors in the control group developed MACE (7.1%) after 8 (IQR, 2.6-12.8) years (p = 0.15). New-onset hypertension was similar between complement disease and control donor groups (21.4% vs 25%, respectively, p = 0.75). There were no differences between study groups regarding last eGFR and proteinuria levels (p = 0.11 and p = 0.70, respectively). One related donor for a recipient with complement-related kidney disease developed gastric cancer and another related donor developed a brain tumor and died in the 4th year after donation (2, 7.1% vs none, p = 0.15). No recipient had donor-specific human leukocyte antigen antibodies at the time of transplantation. Median follow-up period of transplant recipients was 5 years (IQR, 3-7). Eleven (39.3%) recipients [aHUS (n = 3) and C3G (n = 8)] lost their allografts during the follow-up period. Causes of allograft loss were chronic antibody-mediated rejection in 6 recipients and recurrence of C3G in 5. Last serum creatinine and last eGFR of the remaining patients on follow up were 1.03 ± 038 mg/dL and 73.2 ± 19.9 m/min/1.73 m2 for aHUS patients and 1.30 ± 0.23 mg/dL and 56.4 ± 5.5 m/min/1.73 m2 for C3G patients.

CONCLUSION

The present study highlights the importance and complexity of living related-donor kidney transplant for patients with complement-related kidney disorders and motivates the need for further research to determine the optimal risk-assessment for living donor candidates to recipients with aHUS and C3G.