Eculizumab in Typical Hemolytic Uremic Syndrome (HUS) With Neurological Involvement

Complement inhibitors in pediatric kidney diseases: new therapeutic opportunities

Historically, the complement system (classical, lectin, alternative, and terminal pathways) is known to play a crucial role in the etiopathogenesis of many kidney diseases. Direct or indirect activation in these settings is revealed by consumption of complement proteins at the serum level and kidney tissue deposition seen by immunofluorescence and electron microscopy. The advent of eculizumab has shown that complement inhibitors may improve the natural history of certain kidney diseases. Since then, the number of available therapeutic molecules and experimental studies on complement inhibition has increased exponentially. In our narrative review, we give a summary of the main complement inhibitors that have completed phase II and phase III studies or are currently used in adult and pediatric nephrology. The relevant full-text works, abstracts, and ongoing trials (clinicaltrials.gov site) are discussed. Data and key clinical features are reported for eculizumab, ravulizumab, crovalimab, avacopan, danicopan, iptacopan, pegcetacoplan, and narsoplimab. Many of these molecules have been shown to be effective in reducing proteinuria and stabilizing kidney function in different complement-mediated kidney diseases. Thanks to their efficacy and target specificity, these novel drugs may radically improve the outcome of complement-mediated kidney diseases, contributing to an improvement in our understanding of their underlying pathophysiology.

Eculizumab in Shiga toxin-producing Escherichia coli hemolytic uremic syndrome: a systematic review

BACKGROUND

Infection-associated hemolytic uremic syndrome (IA-HUS), most often due to infection with Shiga toxin-producing bacteria, mainly affects young children. It can be acutely life-threatening, as well as cause long-term kidney and neurological morbidity. Specific treatment with proven efficacy is lacking. Since activation of the alternative complement pathway occurs in HUS, the monoclonal C5 antibody eculizumab is often used off-label once complications, e.g., seizures, occur. Eculizumab is prohibitively expensive and carries risk of infection. Its utility in IA-HUS has not been systematically studied. This systematic review aims to present, summarize, and evaluate all currently available data regarding the effect of eculizumab administration on medium- to long-term outcomes (i.e., outcomes after the acute phase, with a permanent character) in IA-HUS.

METHODS

PubMed, Embase, and Web of Science were systematically searched for studies reporting the impact of eculizumab on medium- to long-term outcomes in IA-HUS. The final search occurred on March 2, 2022. Studies providing original data regarding medium- to long-term outcomes in at least 5 patients with IA-HUS, treated with at least one dose of eculizumab during the acute illness, were included. No other restrictions were imposed regarding patient population. Studies were excluded if data overlapped substantially with other studies, or if outcomes of IA-HUS patients were not reported separately. Study quality was assessed using the ROBINS-I tool for risk of bias in non-randomized studies of interventions. Data were analyzed descriptively.

RESULTS

A total of 2944 studies were identified. Of these, 14 studies including 386 eculizumab-treated patients met inclusion criteria. All studies were observational. Shiga toxin-producing E. coli (STEC) was identified as the infectious agent in 381 of 386 patients (98.7%), effectively limiting the interpretation of the data to STEC-HUS patients. Pooling of data across studies was not possible. No study reported a statistically significant positive effect of eculizumab on any medium- to long-term outcome. Most studies were, however, subject to critical risk of bias due to confounding, as more severely ill patients received eculizumab. Three studies attempted to control for confounding through patient matching, although residual bias persisted due to matching limitations.

DISCUSSION

Current observational evidence does not permit any conclusion regarding the impact of eculizumab in IA-HUS given critical risk of bias. Results of randomized clinical trials are eagerly awaited, as new therapeutic strategies are urgently needed to prevent long-term morbidity in these severely ill patients.

SYSTEMATIC REVIEW REGISTRATION NUMBER

OSF Registries, MSZY4, Registration DOI https://doi.org/10.17605/OSF.IO/MSZY4 .

Eculizumab in STEC-HUS: a paradigm shift in the management of pediatric patients with neurological involvement

BACKGROUND

Eculizumab for the treatment of atypical hemolytic uremic syndrome (HUS) is a standard of care. Central nervous system (CNS) involvement in Shiga toxin-producing Escherichia coli (STEC)-HUS is associated with increased morbidity and mortality. There is no consensus on the use of plasma exchange and/or eculizumab. We report a series (n = 4) of children with CNS involvement in STEC-HUS with excellent outcomes after treatment with eculizumab only and supportive therapies.

METHODS

A retrospective chart review of patients with CNS involvement in STEC-HUS is managed with supportive therapies and eculizumab only.

RESULTS

Four patients (75% female) with a median age of 5 years and 11 months (IQR: 23.5-105.5 months) were admitted to a tertiary pediatric nephrology center with CNS involvement in STEC-HUS. Neurological symptoms presented between days 2 and 7 of illness and included ataxia, altered mental status, visual symptoms, and seizures. All had an abnormal MRI brain. All received two doses of eculizumab, 1 week apart (dosing according to weight). Resolution of neurological symptoms was evident at a mean of 60 h post-administration (range: 24-72 h). All patients have complete kidney and neurological recovery at 12-month follow-up.

CONCLUSION

We present a case series of four children with STEC-HUS and CNS involvement, managed with eculizumab only, in lieu of plasma exchange (as per our previous policy). The marked improvement in symptoms in our cohort supports the use of eculizumab, rather than plasma exchange in the CNS involvement of STEC-HUS.

Cerebral microstructural changes in children suffering from hemolytic uremic syndrome

To evaluate microstructural cerebral changes in children suffering from typical hemolytic uremic syndrome (HUS) based on apparent diffusion coefficient (ADC) maps. For 12 pediatric HUS patients (0.8 - 14.6 years of age) conventional magnetic resonance imaging (cMRI) at 1.5 T was retrospectively analyzed. ADC values were measured in 35 different brain regions and compared with age-related, previously published ADC reference values from a healthy pediatric control group. The HUS cohort was divided into 2 subgroups depending on clinical outcome. Subgroup A showed poor neurological outcome whereas subgroup B demonstrated improvement without lasting neurological deficits. Qualitative analysis revealed lesions by diffusion-weighted imaging (DWI) with hypointense correlate on the ADC map in basal ganglia and/or thalami and corresponding T2 hyperintensities in the majority of patients in Subgroup A (80%). Those in Subgroup B did not show qualitative DWI alterations with ADC correlate even when T2 hyperintense lesions were detected in basal ganglia and/or thalami. Quantitative analysis demonstrated abnormal ADC values in all HUS patients with a trend to a greater number of affected regions in Subgroup A compared to Subgroup B (16 versus 11 median number of regions respectively, p = 0.56).   Conclusion: Using DWI qualitative and quantitative differences were found between HUS patients showing poor neurological outcome and those without neurological deficits at discharge. While ADC values indicated more extensive cerebral changes than conventional qualitative findings, both may provide early prognostic indicators for neurological outcome in pediatric HUS patients. What is Known: • In patients with STEC-HUS and neurological symptoms, MRI may show hyperintense signals on T2 and altered diffusivity mostly affecting basal ganglia, thalami and periventricular white matter. What is New: • In such patients, early MRI including quantitative ADC measurements over different brain regions may allow for detection of signal alterations possibly reflecting microstructural changes in such patients.

HUS with mutations in CFH and STEC infection treated with eculizumab in a 4-year-old girl

BACKGROUND

Hemolytic uremic syndrome secondary to Shiga-toxin-producing Escherichia coli infection (STEC-HUS) generally shows a favorable outcome. Few cases develop extra-renal complications, since neurological involvement is an important cause of morbidity and mortality. The role of complement in STEC-HUS has been recently highlighted, and the use of eculizumab in severe cases has been communicated. HUS results from environmental and genetic factors, but the simultaneous occurrence of STEC and complement mutations remains undetermined.

METHODS

A pediatric case with severe STEC-HUS carrying CFH mutations, with favorable response to eculizumab is analyzed.

RESULTS

STEC-HUS was diagnosed in a 4-year-old girl with classic HUS, including low C3. Peritoneal dialysis was started due to hypertension, oligoanuria, and pleural effusion. She evolved with generalized tonic-clonic seizures and required mechanical ventilation. MRI reported multiple supra- and infratentorial ischemic lesions with laminar/striatal cortical necrosis and leukoencephalopathy. After two eculizumab doses, a significative stabilization in diuresis, blood pressure, creatinine, and C3 was achieved. At the third week, episodes of massive digestive bleeding and a life-threatening condition required a colectomy thus preserving the ileocecal valve. Due to atypical evolution, a genetic study was considered, identifying two heterozygous variants (CFH S1191L/V1197A).

CONCLUSION

STEC-HUS in patients with a genetic predisposition has been previously reported, but the low frequency of occurrence makes it a rare disease. As in the present case, patients with atypical course might benefit from genetic analysis to evaluate early eculizumab initiation and to better understand its phenotype. A higher resolution version of the Graphical abstract is available as Supplementary information.

Diarrhoea-associated haemolytic uraemic syndrome and Shiga toxin-producing Escherichia coli infections in New Zealand children: Clinical features and short-term complications from a 23-year cohort study

BACKGROUND

Diarrhoea-associated haemolytic uraemic syndrome (D+HUS) is an important cause of acute kidney injury (AKI) in young children and it is most commonly associated with Shiga toxin-producing Escherichia coli (STEC). Gastrointestinal infections caused by STEC have been increasing in New Zealand over the past two decades, but little is known regarding the acute and short-term outcomes of New Zealand children who develop D+HUS.

AIM

To describe the clinical characteristics, complications and short-term outcomes of New Zealand children with D+HUS identified between 1 January 1998 and 31 December 2020.

METHODS

The New Zealand Paediatric Surveillance Unit sends out a monthly survey to all practising paediatricians regarding conditions under active surveillance. Paediatricians caring for a child aged 0-15 years of age with D+HUS over the prior month were requested to report their patient. Reporting clinicians were then contacted by the principal investigator and sent a questionnaire requesting patient clinical and laboratory information.

RESULTS

Two hundred and twenty-six children had D+HUS; median age 2.8 years (interquartile range 1.7-4.9). Acute dialysis was required in 128/226 (56.2%) of children for a median of 9 days (range 1-38). Children with shorter diarrhoeal prodrome, higher neutrophil count and haemoglobin had a longer duration of dialysis. Seizures occurred in 31/226 (13.7%) and were not associated with a greater HUS severity score. Acute mortality was 1.3%, all resulting from thrombotic microangiopathic cerebral injury.

CONCLUSION

D+HUS is a major cause of AKI in previously healthy young children. Earlier recognition of STEC infections in young children may reduce the need for dialysis and other extra-renal complications. The New Zealand incidence of acute dialysis, other major complications and mortality are consistent with other reported studies.

Extracorporeal Membrane Oxygenation and Hemolytic Uremic Syndrome in Children: Outcome Review of a Multicenter National Database

Hemolytic uremic syndrome (HUS) is a triad of hemolytic anemia, thrombocytopenia, and acute renal failure. In critically ill children with HUS, extrarenal manifestations may require intensive care unit admission and extracorporeal membrane oxygenation (ECMO) support. Outcomes specific to HUS and ECMO in children have not been well investigated. The primary aim of this project was to query a multicenter database to identify risk factors associated with mortality in HUS patients supported on ECMO. A secondary aim was to identify factors associated with ECMO utilization in children with HUS. Utilizing the Pediatric Health Information System database (January 2004 and September 2018), this retrospective, multicenter cohort study identified the index HUS hospitalization among children aged 0 to 18 years. Univariate analysis was used to compare demographics, clinical characteristics, and procedures to identify risk factors associated with adverse outcomes. Among 4,144 subjects, 37 were supported on ECMO. Survival for those on ECMO support was 54%. Among nonsurvivors, 59% of deaths occurred within 14 days of hospitalization. The mean hospital LOS was 15.9 days in nonsurvivors versus 53.9 days for survivors (p < 0.001). When comparing subjects supported on ECMO to those who were not, patients with ECMO support had statistically longer hospital LOS and higher rates of extrarenal involvement (p < 0.001). This study found a mortality rate of 46% among HUS patients requiring ECMO. The investigated clinical risk factors were not associated with mortality among the ECMO population. The study identifies risk factors associated with ECMO utilization in children with HUS.

Severe Neurological Involvement in an Adult with Shiga Toxin-Producing Escherichia coli-Hemolytic Uremic Syndrome Treated with Eculizumab

A 68-year-old man with a medical history of hypertension was admitted to the emergency department for diffuse abdominal pain preceded by bloody diarrhea. Upon admission, neurological examination was normal, but he suddenly developed a left-sided hemiparesis. After a normal brain computed tomography, intravenous thrombolysis was administered for a suspicion of ischemic stroke. In the first laboratory investigations, hemoglobin was 16.9 g/dL, platelets 121 × 109/L (150-450), and serum creatinine 1.17 mg/dL. By the second hospital day, the platelet level dropped to 79 × 109/L, with haptoglobin at 0.12 g/L, 3% schistocytes, and normal ADAMTS13 activity (57%). Serum creatinine increased to 1.84 mg/dL with oliguria. The suspicion of thrombotic microangiopathy was supported by the identification of Shiga toxin genes stx1 and stx2 on a rectal swab and the isolation of an eaeA-negative Shiga toxin-producing E. coli O113:H4. The patient presented a generalized tonic-clonic seizure, and orotracheal intubation was required for decreased consciousness. Plasma exchange therapy was started, and eculizumab was given 6 days after symptoms onset. Brain magnetic resonance imaging (MRI) on day 13 showed symmetric hyperintensities within basal ganglia that disappeared on a second MRI on day 37. At 2-month follow-up, the patient had made a complete neurological and renal recovery and eculizumab therapy was stopped.

Cerebral vascular injury in transplant-associated thrombotic microangiopathy

Transplant-associated thrombotic microangiopathy (TA-TMA) and atypical hemolytic uremic syndrome (aHUS) are complement-mediated TMAs. The central nervous system (CNS) is the most common extrarenal organ affected by aHUS, and, despite mechanistic overlap between aHUS and TA-TMA, CNS involvement is rarely reported in TA-TMA, suggesting that CNS involvement in TA-TMA may be underdiagnosed and that these patients may benefit from complement blockers. In addition, there are no widely used histologic or radiologic criteria for the diagnosis of TMA in the brain. Thirteen recipients of pediatric hematopoietic cell transplants (HCTs) who had TA-TMA and who underwent autopsy were studied. Seven of 13 brains had vascular injury, and 2 had severe vascular injury. Neurologic symptoms correlated with severe vascular injury. Classic TMA histology was present and most often observed in the cerebellum, brainstem, and cerebral white matter. Abnormalities in similar anatomic regions were seen on imaging. Brain imaging findings related to TMA included hemorrhages, siderosis, and posterior reversible encephalopathy syndrome. We then studied 100 consecutive HCT recipients to identify differences in neurologic complications between patients with and those without TA-TMA. Patients with TA-TMA were significantly more likely to have a clinical concern for seizure, have an electroencephalogram performed, and develop altered mental status. In summary, our study confirms that TA-TMA involves the brains of recipients of HCT and is associated with an increased incidence of neurologic symptoms. Based on these findings, we propose that patients with low- or moderate-risk TA-TMA who develop neurologic complications should be considered for TA-TMA-directed therapy.

Enterohemorrhagic Escherichia coli and a Fresh View on Shiga Toxin-Binding Glycosphingolipids of Primary Human Kidney and Colon Epithelial Cells and Their Toxin Susceptibility

Enterohemorrhagic Escherichia coli (EHEC) are the human pathogenic subset of Shiga toxin (Stx)-producing E. coli (STEC). EHEC are responsible for severe colon infections associated with life-threatening extraintestinal complications such as the hemolytic-uremic syndrome (HUS) and neurological disturbances. Endothelial cells in various human organs are renowned targets of Stx, whereas the role of epithelial cells of colon and kidneys in the infection process has been and is still a matter of debate. This review shortly addresses the clinical impact of EHEC infections, novel aspects of vesicular package of Stx in the intestine and the blood stream as well as Stx-mediated extraintestinal complications and therapeutic options. Here follows a compilation of the Stx-binding glycosphingolipids (GSLs), globotriaosylceramide (Gb3Cer) and globotetraosylceramide (Gb4Cer) and their various lipoforms present in primary human kidney and colon epithelial cells and their distribution in lipid raft-analog membrane preparations. The last issues are the high and extremely low susceptibility of primary renal and colonic epithelial cells, respectively, suggesting a large resilience of the intestinal epithelium against the human-pathogenic Stx1a- and Stx2a-subtypes due to the low content of the high-affinity Stx-receptor Gb3Cer in colon epithelial cells. The review closes with a brief outlook on future challenges of Stx research.

Shiga Toxin 2 Triggers C3a-Dependent Glomerular and Tubular Injury through Mitochondrial Dysfunction in Hemolytic Uremic Syndrome

Shiga toxin (Stx)-producing Escherichia coli is the predominant offending agent of post-diarrheal hemolytic uremic syndrome (HUS), a rare disorder of microvascular thrombosis and acute kidney injury possibly leading to long-term renal sequelae. We previously showed that C3a has a critical role in the development of glomerular damage in experimental HUS. Based on the evidence that activation of C3a/C3a receptor (C3aR) signaling induces mitochondrial dysregulation and cell injury, here we investigated whether C3a caused podocyte and tubular injury through induction of mitochondrial dysfunction in a mouse model of HUS. Mice coinjected with Stx2/LPS exhibited glomerular podocyte and tubular C3 deposits and C3aR overexpression associated with cell damage, which were limited by C3aR antagonist treatment. C3a promoted renal injury by affecting mitochondrial wellness as demonstrated by data showing that C3aR blockade reduced mitochondrial ultrastructural abnormalities and preserved mitochondrial mass and energy production. In cultured podocytes and tubular cells, C3a caused altered mitochondrial fragmentation and distribution, and reduced anti-oxidant SOD2 activity. Stx2 potentiated the responsiveness of renal cells to the detrimental effects of C3a through increased C3aR protein expression. These results indicate that C3aR may represent a novel target in Stx-associated HUS for the preservation of renal cell integrity through the maintenance of mitochondrial function.

Hemolytic-uremic syndrome: 24 years' experience of a pediatric nephrology unit

INTRODUCTION

A better understanding of hemolytic-uremic syndrome (HUS) pathophysiology significantly changed its treatment and prognosis. The aim of this study is to characterize the clinical features, severity, management, and outcomes of HUS patients.

MATERIALS AND METHODS

Retrospective study of HUS patients admitted to a Pediatric Nephrology Unit between 1996 and 2020. Demographic and clinical data regarding etiology, severity, treatment strategies, and patient outcome were collected.

RESULTS

Twenty-nine patients with HUS were admitted to our unit, but four were excluded. Median age at diagnosis was two years (2 months - 17 years). Clinical manifestations included diarrhea, vomiting, oliguria, hypertension, and fever. During the acute phase, 14 patients (56%) required renal replacement therapy. Infectious etiology was identified in seven patients (five Escherichia coli and two Streptococcus pneumoniae). Since 2015, 2/7 patients were diagnosed with complement pathway dysregulation HUS and there were no cases of infectious etiology detected. Six of these patients received eculizumab. The global median follow-up was 6.5 years [3 months-19.8 years]. One patient died, seven had chronic kidney disease, four of whom underwent kidney transplantation, one relapsed, and seven had no sequelae.

CONCLUSION

These results reflect the lack of infectious outbreaks in Portugal and the improvement on etiological identification since genetic testing was introduced. The majority of patients developed sequels and mortality was similar to that of other countries. HUS patients should be managed in centers with intensive care and pediatric nephrology with capacity for diagnosis, etiological investigation, and adequate treatment. Long-term follow-up is essential.

Eculizumab Use in a Temporarily Dialysis-Dependent Patient With Shiga Toxin-Producing Escherichia Coli Hemolytic Uremic Syndrome With Neurological Complications

Shiga toxin-producing Escherichia coli hemolytic uremic syndrome (STEC-HUS) is the most common cause of acute renal failure in children, and it is associated with thrombocytopenia and hemolytic anemia. Although this disease primarily affects the kidney, it can also contribute to cellular damage in other organ systems, such as the CNS. Eculizumab is a monoclonal antibody that binds to complement proteins to prevent complement-mediated intravascular hemolysis in atypical HUS. In STEC-HUS, complement activation also occurs by Shiga toxin, and previous cases of eculizumab use in the setting of neurological involvement have been shown to be successful. We report the successful use of eculizumab in the setting of typical STEC-HUS-induced neurological symptoms including seizure, altered mental status, and left arm weakness. The patient also experienced concomitant renal failure requiring dose adjustment for hemodialysis. Following 2 doses of eculizumab, our patient was discharged to an inpatient rehabilitation facility with resolution of her renal injury, seizures, and altered mentation without adverse effects from eculizumab throughout the admission. Based on our case study, it appears that eculizumab may be given during or between hemodialysis without dose adjustment.

Neurological involvement in children with hemolytic uremic syndrome

Our objective was to establish the rate of neurological involvement in Shiga toxin-producing Escherichia coli-hemolytic uremic syndrome (STEC-HUS) and describe the clinical presentation, management and outcome. A retrospective chart review of children aged ≤ 16 years with STEC-HUS in Children's Health Ireland from 2005 to 2018 was conducted. Laboratory confirmation of STEC infection was required for inclusion. Neurological involvement was defined as encephalopathy, focal neurological deficit, and/or seizure activity. Data on clinical presentation, management, and outcome were collected. We identified 240 children with HUS; 202 had confirmed STEC infection. Neurological involvement occurred in 22 (11%). The most common presentation was seizures (73%). In the neurological group, 19 (86%) were treated with plasma exchange and/or eculizumab. Of the 21 surviving children with neurological involvement, 19 (91%) achieved a complete neurological recovery. A higher proportion of children in the neurological group had renal sequelae (27% vs. 12%, P = .031). One patient died from multi-organ failure.Conclusion: We have identified the rate of neurological involvement in a large cohort of children with STEC-HUS as 11%. Neurological involvement in STEC-HUS is associated with good long-term outcome (complete neurological recovery in 91%) and a low case-fatality rate (4.5%) in our cohort. What is Known: • HUS is associated with neurological involvement in up to 30% of cases. • Neurological involvement has been reported as predictor of poor outcome, with associated increased morbidity and mortality. What is New: • The incidence of neurological involvement in STEC-HUS is 11%. • Neurological involvement is associated with predominantly good long-term outcome (90%) and a reduced case-fatality rate (4.5%) compared to older reports.

Treatment of Shiga-Toxin Hus with Severe Neurologic Features with Eculizumab

Hemolytic Uremic Syndrome (HUS) is a constellation of microangiopathic hemolytic anemia, thrombocytopenia, and acute renal failure. Shiga toxin-producing Escherichia coli- (STEC-) mediated HUS is a common cause of acute renal failure in children and can rarely result in severe neurological complications such as encephalopathy, seizures, cerebrovascular accidents, and coma. Current literature supports use of eculizumab, a monoclonal antibody that blocks complement activation, in atypical HUS (aHUS). However, those with neurologic complications from STEC-HUS have complement activation and deposition of aggregates in microvasculature and may be treated with eculizumab. In this case report, we describe a 3-year-old boy with diarrhea-positive STEC-HUS who developed severe neurologic involvement in addition to acute renal failure requiring renal replacement therapy. He was initiated on eculizumab therapy, with clinical improvement and organ recovery. This case highlights systemic complications of STEC-HUS in a pediatric patient. The current literature is limited but has suggested a role for complement mediation in cases with severe complications. We review the importance of early recognition of complications, use of eculizumab, and current data available.

Peripheral nervous system manifestations of Shiga toxin-producing E. coli-induced haemolytic uremic syndrome in children

Background

The Neurological involvement is the most common extra-renal complication of Shiga toxin-producing E. coli-hemolytic uremic syndrome (HUS) or typical HUS. On brain magnetic resonance examination, main neurological signs encompass acute lesions of the basal ganglia and the white matter, which could usually regress after Eculizumab infusion. In contrast, peripheral nervous system (PNS) manifestations in typical HUS are very rare and, when occurring, they require a careful management of neurological sequelae and an intensive multidisciplinary neuro-rehabilitation program.

Case presentation

Here, we present two pediatric cases of severe and complicated typical HUS with PNS manifestations who required therapeutic treatment and an intensive multidisciplinary neuro-rehabilitation program.

In both cases, PNS manifestations were followed by the recovery from typical HUS-related severe central neurological damage and manifested mainly with marked bilateral motor deficit and hyporeflexia/areflexia in the lower limbs. The peripheral polyneuropathy was treated with immunosuppressive therapy (methylprednisolone boluses, i.v. immunoglobulins, plasma exchange), followed by a prolonged intensive neuro-rehabilitation program. After 8 months of rehabilitation, both patients gained complete functional recovery.

Conclusions

PNS manifestations during typical HUS are a rare event and potentially leading to severe disability. A timely clinical assessment is mandatory to set up a prompt therapeutic and rehabilitation program and to obtain a complete clinical and functional recovery.

Eculizumab exposure in children and young adults: indications, practice patterns, and outcomes-a Pediatric Nephrology Research Consortium study

BACKGROUND

Eculizumab is approved for the treatment of atypical hemolytic uremic syndrome (aHUS). Its use off-label is frequently reported. The aim of this study was to describe the broader use and outcomes of a cohort of pediatric patients exposed to eculizumab.

METHODS

A retrospective, cohort analysis was performed on the clinical and biomarker characteristics of eculizumab-exposed patients < 25 years of age seen across 21 centers of the Pediatric Nephrology Research Consortium. Patients were included if they received at least one dose of eculizumab between 2008 and 2015. Traditional summary statistics were applied to demographic and clinical data.

RESULTS

A total of 152 patients were identified, mean age 9.1 (+/-6.8) years. Eculizumab was used "off-label" in 44% of cases. The most common diagnoses were aHUS (47.4%), Shiga toxin-producing Escherichia coli HUS (12%), unspecified thrombotic microangiopathies (9%), and glomerulonephritis (9%). Genetic testing was available for 60% of patients; 20% had gene variants. Dosing regimens were variable. Kidney outcomes tended to vary according to diagnosis. Infectious adverse events were the most common adverse event (33.5%). No cases of meningitis were reported. Nine patients died of noninfectious causes while on therapy.

CONCLUSIONS

This multi-center retrospective cohort analysis indicates that a significant number of children and young adults are being exposed to C5 blockade for off-label indications. Dosing schedules were highly variable, limiting outcome conclusions. Attributable adverse events appeared to be low. Cohort mortality (6.6%) was not insignificant. Prospective studies in homogenous disease cohorts are needed to support the role of C5 blockade in kidney outcomes.

Shiga Toxin-Associated Hemolytic Uremic Syndrome: Specificities of Adult Patients and Implications for Critical Care Management

Shiga toxin-producing Escherichia coli-associated hemolytic uremic syndrome (STEC-HUS) is a form of thrombotic microangiopathy secondary to an infection by an enterohemorrhagic E. coli. Historically considered a pediatric disease, its presentation has been described as typical, with bloody diarrhea at the forefront. However, in adults, the clinical presentation is more diverse and makes the early diagnosis hazardous. In this review, we review the epidemiology, most important outbreaks, physiopathology, clinical presentation and prognosis of STEC-HUS, focusing on the differential features between pediatric and adult disease. We show that the clinical presentation of STEC-HUS in adults is far from typical and marked by the prevalence of neurological symptoms and a poorer prognosis. Of note, we highlight knowledge gaps and the need for studies dedicated to adult patients. The differences between pediatric and adult patients have implications for the treatment of this disease, which remains a public health threat and lack a specific treatment.

Making the Correct Diagnosis in Thrombotic Microangiopathy: A Narrative Review

Purpose of review:

Thrombotic microangiopathy (TMA) is suspected in patients presenting with thrombocytopenia and evidence of a microangiopathic hemolytic anemia. Patients with TMA can be critically ill, so rapid and accurate identification of the underlying etiology is essential. Due to better insights into pathophysiology and causes of TMA, we can now categorize TMAs as thrombotic thrombocytopenic purpura, postinfectious (mainly Shiga toxin-producing Escherichia coli–induced) hemolytic uremic syndrome (HUS), TMA associated with a coexisting condition, or atypical HUS (aHUS). We recognized an unmet need in the medical community to guide the timely and accurate identification of TMA, the selection of tests to clarify its etiology, and the sequence of steps to initiate treatment.

Sources of information:

Key published studies relevant to the identification, classification, and treatment of TMAs in children or adults. These studies were obtained through literature searches conducted with PubMed or based on the prior knowledge of the authors.

Methods:

This review is the result of a consultation process that reflects the consensus of experts from Canada, the United States, and the United Arab Emirates. The members represent individuals who are clinicians, researchers, and teachers in pediatric and adult medicine from the fields of hematology, nephrology, and laboratory medicine. Authors, through an iterative review process identified and synthesized information from relevant published studies.

Key findings:

Thrombotic thrombocytopenic purpura occurs in the setting of insufficient activity of the von Willebrand factor protease known as ADAMTS13. Shiga toxin-producing Escherichia coli–induced hemolytic uremic syndrome, also known as “typical” HUS, is caused by gastrointestinal infections with bacteria that produce Shiga toxin (initially called verocytotoxin). A variety of clinical conditions or drug exposures can trigger TMA. Finally, aHUS occurs in the setting of inherited or acquired abnormalities in the alternative complement pathway leading to dysregulated complement activation, often following a triggering event such as an infection. It is possible to break the process of etiological diagnosis of TMA into 2 distinct steps. The first covers the initial presentation and diagnostic workup, including the processes of identifying the presence of TMA, appropriate initial tests and referrals, and empiric treatments when appropriate. The second step involves confirming the etiological diagnosis and moving to definitive treatment. For many forms of TMA, the ultimate response to therapies and the outcome of the patient depends on the rapid and accurate identification of the presence of TMA and then a standardized approach to seeking the etiological diagnosis. We present a structured approach to identifying the presence of TMA and steps to identifying the etiology including standardized lab panels. We emphasize the importance of early consultation with appropriate specialists in hematology and nephrology, as well as identification of whether the patient requires plasma exchange. Clinicians should consider appropriate empiric therapies while following the steps we have recommended toward definitive etiologic diagnosis and management of the TMA.

Limitations:

The evidence base for our recommendations consists of small clinical studies, case reports, and case series. They are generally not controlled or randomized and do not lend themselves to a stricter guideline-based methodology or a Grading of Recommendations Assessment, Development and Evaluation (GRADE)-based approach.

Outcome of children with Shiga toxin-associated haemolytic uraemic syndrome treated with eculizumab: a matched cohort study

BACKGROUND

Treatment with eculizumab in Shiga toxin-associated haemolytic and uraemic syndrome (STEC-HUS) remains controversial despite its increasing utilization. The aim of our study was to evaluate the outcomes of children treated with eculizumab for STEC-HUS in a single-centre matched cohort study.

METHODS

Data were retrospectively collected from medical records of children diagnosed with STEC-HUS. The outcomes of patients treated with eculizumab for STEC-HUS were compared with those of a control group of untreated patients matched for age, sex and severity of acute kidney injury with a 1:2 matching scheme.

RESULTS

Eighteen children (median age 40.6 months) with STEC-HUS treated with eculizumab were compared with 36 matched control patients (median age 36.4 months) who did not receive eculizumab. All patients survived in the two groups. Within 1 month of HUS onset, the evolution of haematological and renal parameters did not differ between the two groups. At 12 months of follow-up, renal outcome was not significantly different between the two groups. At the last follow-up, the prevalence of decreased glomerular filtration rate in the eculizumab group (27%) was not statistically different from that in controls (38%), as was the prevalence of proteinuria and high blood pressure. Children who received eculizumab more often had extrarenal sequelae during follow-up. Eculizumab treatment appeared to be safe in children with STEC-HUS.

CONCLUSION

The benefit of eculizumab on renal and extrarenal outcomes in STEC-HUS could not be established based on our findings. However, efficacy and safety are not best assessed by the observational design and small sample size of our study. Randomized controlled trials are thus required to determine the efficacy of eculizumab in this indication.

Therapeutic Strategies to Protect the Central Nervous System against Shiga Toxin from Enterohemorrhagic Escherichia coli

Infection with Shiga toxin-producing Escherichia coli (STEC) may cause hemorrhagic colitis, hemolytic uremic syndrome (HUS) and encephalopathy. The mortality rate derived from HUS adds up to 5% of the cases, and up to 40% when the central nervous system (CNS) is involved. In addition to the well-known deleterious effect of Stx, the gram-negative STEC releases lipopolysaccharides (LPS) and may induce a variety of inflammatory responses when released in the gut. Common clinical signs of severe CNS injury include sensorimotor, cognitive, emotional and/or autonomic alterations. In the last few years, a number of drugs have been experimentally employed to establish the pathogenesis of, prevent or treat CNS injury by STEC. The strategies in these approaches focus on: 1) inhibition of Stx production and release by STEC, 2) inhibition of Stx bloodstream transport, 3) inhibition of Stx entry into the CNS parenchyma, 4) blockade of deleterious Stx action in neural cells, and 5) inhibition of immune system activation and CNS inflammation. Fast diagnosis of STEC infection, as well as the establishment of early CNS biomarkers of damage, may be determinants of adequate neuropharmacological treatment in time.

Utilization Pattern for Eculizumab Among Children With Hemolytic Uremic Syndrome

Background: Hemolytic uremic syndrome (HUS) is a complex disease with multi-organ involvement. Eculizumab therapy is recommended for treatment of complement mediated hemolytic uremic syndrome (cHUS). However, there are few studies evaluating eculizumab therapy among children with HUS. The primary objectives of the study were to describe and identify factors associated with eculizumab therapy in children with HUS. Design/Methods: This large, retrospective, multi-center, cohort study used the Pediatric Health Information System (PHIS) database to identify the index HUS-related hospitalization among patients ≤18 years of age from September 23, 2011 (Food and Drug Administration approval date of eculizumab) through December 31, 2018. Multivariate analysis was used to identify independent factors associated with eculizumab therapy during or after the index hospitalization. Results: Among 1,885 children included in the study, eculizumab therapy was noted in 167 children with a median age of 3.99 years (SD ± 4.7 years). Eculizumab therapy was administered early (within the first 7 days of hospitalization) among 65% of children who received the drug. Mortality during the index hospitalization among children with eculizumab therapy was 4.2 vs. 3.0% without eculizumab therapy (p = 0.309). Clinical factors independently associated with eculizumab therapy were encephalopathy [odds ratio (OR) = 3.09; p ≤ 0.001], seizure disorder (OR = 2.37; p = 0.006), and cardiac involvement (OR = 6.36, p < 0.001). Conclusion(s): Only 8.9% of children received eculizumab therapy. Children who presented with neurological and cardiac involvement with severe disease were more likely to receive eculizumab therapy, and children who received therapy received it early during their index hospitalization. Further prospective studies are suggested to confirm these findings.

Immunotherapy and vaccination against infectious diseases

Due to the overuse of antibiotics, infections, in particular those caused by multidrug-resistant bacteria, are becoming more and more frequent. Despite the worldwide introduction of antibiotic therapy, vaccines and constant improvements in hygiene, the burden of multidrug-resistant bacterial infections is increasing and is expected to rise in the future. The development of monoclonal therapeutic antibodies and specific immunomodulatory drugs represent new treatment options in the fight against infectious diseases. This article provides a brief overview of recent advances in immunomodulatory therapy and other strategies in the treatment of infectious disease.

Rasburicase improves the outcome of acute kidney injury from typical hemolytic uremic syndrome

BACKGROUND

Typical hemolytic uremic syndrome (HUS) causes acute kidney injury (AKI) and serious sequelae of chronic kidney disease (CKD) in some. Hyperuricemia is a common finding in typical HUS that may contribute to kidney damage. We explored whether aggressive management of hyperuricemia with rasburicase could improve outcomes in AKI patients with typical HUS.

METHODS

We retrospectively analyzed medical records of children with typical HUS admitted to a tertiary center between 2005 and 2017. We compared clinical outcomes of hospitalization and 1-year post-discharge between those with rasburicase treatment (n = 13) and those without (controls, n = 29).

RESULTS

With rasburicase treatment, hyperuricemia corrected more rapidly (median 36 vs. 120 h, p < 0.001), and hospital stays were shorter (median 9 vs. 12 days, p = 0.003) than in the controls. There was no difference in dialysis requirement. At 1-year post-discharge, the proportion of patients with impaired kidney function (estimated glomerular filtration rate < 90 mL/min/1.73 m²) was lower in the rasburicase group (7.7% vs. 41.4%, p = 0.036) than in the controls. Hypertension and proteinuria tended to be more common in the controls than in the rasburicase group. Collectively, long-term renal sequelae of impaired kidney function, proteinuria, or hypertension at a 1-year follow-up was less common in the rasburicase group than in the controls (7.7% vs. 62.1%; p = 0.001).

CONCLUSIONS

Children with typical HUS treated with rasburicase had shorter hospital stays and less long-term sequelae at 1-year post-discharge than those who were not treated with rasburicase. These results support the use of rasburicase to prevent CKD in pediatric patients with typical HUS-associated AKI. Graphical Abstract.

Emerging evidence of a COVID-19 thrombotic syndrome has treatment implications

Reports of widespread thromboses and disseminated intravascular coagulation (DIC) in patients with coronavirus disease 19 (COVID-19) have been rapidly increasing in number. Key features of this disorder include a lack of bleeding risk, only mildly low platelet counts, elevated plasma fibrinogen levels, and detection of both severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and complement components in regions of thrombotic microangiopathy (TMA). This disorder is not typical DIC. Rather, it might be more similar to complement-mediated TMA syndromes, which are well known to rheumatologists who care for patients with severe systemic lupus erythematosus or catastrophic antiphospholipid syndrome. This perspective has critical implications for treatment. Anticoagulation and antiviral agents are standard treatments for DIC but are gravely insufficient for any of the TMA disorders that involve disorders of complement. Mediators of TMA syndromes overlap with those released in cytokine storm, suggesting close connections between ineffective immune responses to SARS-CoV-2, severe pneumonia and life-threatening microangiopathy.

Nephrotic-range proteinuria and central nervous involvement in typical hemolytic uremic syndrome: a case report

Background

Hemolytic uremic syndrome (HUS), a common subtype of thrombotic microangiopathy (TMA), is characterized by microangiopathic hemolytic anemia, thrombocytopenia, and acute kidney injury. Shiga toxin-producing Escherichia coli infection is the most common cause of post-diarrheal HUS. Kidney and central nervous system are the primary target organs.

Case presentation

A 64-year-old male presented with HUS following bloody diarrhea. Nephrotic-range proteinuria and hypoalbuminemia were present at the acute stage and renal histology revealed common TMA features. Neurological involvement presented as confusion and impaired cognitive function. Cranial magnetic resonance imaging demonstrated bilateral T2 hyperintensities in the brainstem and insula. The patient received plasma exchange and supportive care. Both the renal and neurological impairments were completely recovered 3 months after the onset.

Conclusion

We report an adult patient presenting with nephrotic-range proteinuria and central nervous system involvement at the acute phase of post-diarrheal HUS. The reversibility of the organ damages might predict a favorable outcome.

Valid Presumption of Shiga Toxin-Mediated Damage of Developing Erythrocytes in EHEC-Associated Hemolytic Uremic Syndrome

The global emergence of clinical diseases caused by enterohemorrhagic Escherichia coli (EHEC) is an issue of great concern. EHEC release Shiga toxins (Stxs) as their key virulence factors, and investigations on the cell-damaging mechanisms toward target cells are inevitable for the development of novel mitigation strategies. Stx-mediated hemolytic uremic syndrome (HUS), characterized by the triad of microangiopathic hemolytic anemia, thrombocytopenia, and acute renal injury, is the most severe outcome of an EHEC infection. Hemolytic anemia during HUS is defined as the loss of erythrocytes by mechanical disruption when passing through narrowed microvessels. The formation of thrombi in the microvasculature is considered an indirect effect of Stx-mediated injury mainly of the renal microvascular endothelial cells, resulting in obstructions of vessels. In this review, we summarize and discuss recent data providing evidence that HUS-associated hemolytic anemia may arise not only from intravascular rupture of erythrocytes, but also from the extravascular impairment of erythropoiesis, the development of red blood cells in the bone marrow, via direct Stx-mediated damage of maturing erythrocytes, leading to “non-hemolytic” anemia.

Treatment Strategies for Infections With Shiga Toxin-Producing Escherichia coli

Infections with Shiga toxin-producing Escherichia coli (STEC) cause outbreaks of severe diarrheal disease in children and the elderly around the world. The severe complications associated with toxin production and release range from bloody diarrhea and hemorrhagic colitis to hemolytic-uremic syndrome, kidney failure, and neurological issues. As the use of antibiotics for treatment of the infection has long been controversial due to reports that antibiotics may increase the production of Shiga toxin, the recommended therapy today is mainly supportive. In recent years, a variety of alternative treatment approaches such as monoclonal antibodies or antisera directed against Shiga toxin, toxin receptor analogs, and several vaccination strategies have been developed and evaluated in vitro and in animal models. A few strategies have progressed to the clinical trial phase. Here, we review the current understanding of and the progress made in the development of treatment options against STEC infections and discuss their potential.

Extra-corporeal membrane oxygenation and Eculizumab: Atypical treatments for typical haemolytic uraemic syndrome

A 19-year-old female with no medical history presented with bloody diarrhoea. Investigations revealed an acute kidney injury, thrombocytopenia and microangiopathic haemolysis. A diagnosis of haemolytic uraemic syndrome secondary to Shiga toxin-producing Escherichia coli 055 was confirmed and supportive therapy commenced in the intensive therapy unit. On day 11 of her admission, she rapidly deteriorated with evidence of refractory cardiogenic shock and neurological involvement, both features associated with a poor prognosis. Cross-specialty collaboration prompted a trial of veno-arterial extra-corporeal membrane oxygenation and Eculizumab, a complement inhibitor normally reserved for atypical haemolytic uraemic syndrome, as a bridge to organ recovery. To our knowledge, herein we present the first adult patient with haemolytic uraemic syndrome induced cardiogenic shock successfully supported to cardiac recovery with extra-corporeal membrane oxygenation. The potential role for Eculizumab in Shiga toxin-producing Escherichia coli/typical haemolytic uraemic syndrome is also discussed.

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.

Shiga Toxin-Associated Hemolytic Uremic Syndrome: A Narrative Review

The severity of human infection by one of the many Shiga toxin-producing Escherichia coli (STEC) is determined by a number of factors: the bacterial genome, the capacity of human societies to prevent foodborne epidemics, the medical condition of infected patients (in particular their hydration status, often compromised by severe diarrhea), and by our capacity to devise new therapeutic approaches, most specifically to combat the bacterial virulence factors, as opposed to our current strategies that essentially aim to palliate organ deficiencies. The last major outbreak in 2011 in Germany, which killed more than 50 people in Europe, was evidence that an effective treatment was still lacking. Herein, we review the current knowledge of STEC virulence, how societies organize the prevention of human disease, and how physicians treat (and, hopefully, will treat) its potentially fatal complications. In particular, we focus on STEC-induced hemolytic and uremic syndrome (HUS), where the intrusion of toxins inside endothelial cells results in massive cell death, activation of the coagulation within capillaries, and eventually organ failure.

Shiga-Toxin E. coli Hemolytic Uremic Syndrome: Review of Management and Long-term Outcome

Purpose of Review

We review the pathophysiology of Shiga-Toxin Enteropathogenic–Hemolytic Uremic Syndrome (STEC-HUS), strategies to ameliorate or prevent evolution of STEC-HUS, management and the improved recognition of long-term adverse outcomes.

Recent Findings

Following on from the preclinical evidence of a role for the complement system in STEC-HUS, the use of complement blocking agents has been the major focus of most recent clinical research. Novel therapies to prevent or lessen HUS have yet to enter the clinical arena. The long-term outcomes of STEC-HUS, similarly to other causes of AKI, are not as benign as previously thought.

Summary

Optimizing supportive care in STEC-HUS is the only current recommended treatment. The administration of early isotonic fluids may reduce the severity and duration of STEC-HUS. The role of complement blockade in the management of STEC-HUS remains unclear. The long-term sequelae from STEC-HUS are significant and patients with apparent full renal recovery remain at risk.

Use of complement monoclonal antibody eculizumab in Shiga toxin producing Escherichia coli associated hemolytic uremic syndrome: A review of current evidence

Complement activation plays an important role in the pathogenesis of atypical hemolytic uremic syndrome. Eculizumab is a monoclonal antibody that blocks complement activity and has been approved for use in the treatment of atypical hemolytic uremic syndrome (HUS). Less well appreciated is the role of complement in Shiga toxin-induced HUS (Shiga toxin producing Escherichia coli [STEC]-HUS). To a limited extent, eculizumab has been used off label in patients with severe STEC-HUS with neurological involvement. Through a systematic search of available databases, we identified 16 reports describing the use of eculizumab in STEC-HUS (eight case reports/series, seven retrospective studies, and one prospective cohort study). All studies described its use in severe STEC-HUS with neurological or multiorgan dysfunction; none were randomized or blinded. Four studies used the control groups. Although the overall quality of evidence is low, some published studies showed positive clinical improvement after treatment with eculizumab in severe STEC-HUS with progressive neurological involvement.

Haemolytic uremic syndrome: diagnosis and management

The thrombotic microangiopathies (TMAs) are a group of diseases characterised by microangiopathic haemolysis, thrombocytopenia, and thrombus formation leading to tissue injury. Traditionally, TMAs have been classified as either thrombotic thrombocytopenic purpura (TTP) or haemolytic uremic syndrome (HUS) based on the clinical presentation, with neurological involvement predominating in the former and acute kidney injury in the latter. However, as our understanding of the pathogenesis of these conditions has increased, it has become clear that this is an over-simplification; there is significant overlap in the clinical presentation of TTP and HUS, there are different forms of HUS, and TMAs can occur in other, diverse clinical scenarios. This review will discuss recent developments in the diagnosis of HUS, focusing on the different forms of HUS and how to diagnose and manage these potentially life-threatening diseases.

Haemolytic uraemic syndrome - a rare case report of bloody diarrhoea in adults

BACKGROUND

Haemolytic uraemic syndrome is a rarely seen in adults often leading to critical illness. This case highlights how difficult it can be to establish a diagnosis and treat when a patient presents with bloody diarrhoea.

CASE PRESENTATION

A 17-year-old Iraqi man presented to the emergency department with abdominal pain and bloody diarrhoea. He was initially treated as acute appendicitis, undergoing an appendectomy but following a recurrence in his symptoms a colonoscopy was performed. A diagnosis of shiga toxin-producing Escherichia coli leading to HUS was suspected following histology obtained at colonoscopy and this was confirmed on antibody testing. Despite intravenous fluids and supportive therapy the patient's symptoms and condition deteriorated. He developed seizures and acute renal failure requiring intubation and plasma exchange in the intensive care setting. He eventually required treatment with ecluzimab therapy; a monoclonal antibody and subsequently made a full recovery.

CONCLUSIONS

Haemolytic uraemic syndrome is a triad of progressive renal failure, thrombocytopenia and haemolytic anaemia which is a condition rarely seen in adults. It is usually associated with an E. coli infection and supportive therapy remains the mainstay of treatment.

Hemolytic uremic syndrome in a developing country: Consensus guidelines

BACKGROUND

Hemolytic uremic syndrome (HUS) is a leading cause of acute kidney injury in children. Although international guidelines emphasize comprehensive evaluation and treatment with eculizumab, access to diagnostic and therapeutic facilities is limited in most developing countries. The burden of Shiga toxin-associated HUS in India is unclear; school-going children show high prevalence of anti-factor H (FH) antibodies. The aim of the consensus meeting was to formulate guidelines for the diagnosis and management of HUS in children, specific to the needs of the country.

METHODS

Four workgroups performed literature review and graded research studies addressing (i) investigations, biopsy, genetics, and differential diagnosis; (ii) Shiga toxin, pneumococcal, and infection-associated HUS; (iii) atypical HUS; and (iv) complement blockade. Consensus statements developed by the workgroups were discussed during a consensus meeting in March 2017.

RESULTS

An algorithm for classification and evaluation was developed. The management of Shiga toxin-associated HUS is supportive; prompt plasma exchanges (PEX) is the chief therapy in patients with atypical HUS. Experts recommend that patients with anti-FH-associated HUS be managed with a combination of PEX and immunosuppressive medications. Indications for eculizumab include incomplete remission with plasma therapy, life-threatening features, complications of PEX or vascular access, inherited defects in complement regulation, and recurrence of HUS in allografts. Priorities for capacity building in regional and national laboratories are highlighted.

CONCLUSIONS

Limited diagnostic capabilities and lack of access to eculizumab prevent the implementation of international guidelines for HUS in most developing countries. We propose practice guidelines for India, which will perhaps be applicable to other developing countries.

Genetic Susceptibility to Postdiarrheal Hemolytic-Uremic Syndrome After Shiga Toxin-Producing Escherichia coli Infection: A Centers for Disease Control and Prevention FoodNet Study

Background

Postdiarrheal hemolytic-uremic syndrome (D+HUS) following Shiga toxin-producing Escherichia coli (STEC) infection is a serious condition lacking specific treatment. Host immune dysregulation and genetic susceptibility to complement hyperactivation are implicated in non-STEC-related HUS. However, genetic susceptibility to D+HUS remains largely uncharacterized.

Methods

Patients with culture-confirmed STEC diarrhea, identified through the Centers for Disease Control and Prevention FoodNet surveillance system (2007-2012), were serotyped and classified by laboratory and/or clinical criteria as having suspected, probable, or confirmed D+HUS or as controls and underwent genotyping at 200 loci linked to nondiarrheal HUS or similar pathologies. Genetic associations with D+HUS were explored by multivariable regression, with adjustment for known risk factors.

Results

Of 641 enrollees with STEC O157:H7, 80 had suspected D+HUS (41 with probable and 32 with confirmed D+HUS). Twelve genes related to cytokine signaling, complement pathways, platelet function, pathogen recognition, iron transport, and endothelial function were associated with D+HUS in multivariable-adjusted analyses (P ≤ .05). Of 12 significant single-nucleotide polymorphisms (SNPs), 5 were associated with all levels of D+HUS (intergenic SNP rs10874639, TFRC rs3804141, EDN1 rs5370, GP1BA rs121908064, and B2M rs16966334), and 7 SNPs (6 non-complement related) were associated with confirmed D+HUS (all P < .05).

Conclusions

Polymorphisms in many non-complement-related genes may contribute to D+HUS susceptibility. These results require replication, but they suggest novel therapeutic targets in patients with D+HUS.

Hemolytic Uremic Syndrome With Severe Neurologic Complications in an Adult

The case of a female presenting with Shiga toxin-producing Escherichia coli and hemolytic uremic syndrome highlights a severe neurologic complication that can be associated with these conditions.

Shiga toxin triggers endothelial and podocyte injury: the role of complement activation

Shiga toxin (Stx)-producing Escherichia coli (STEC) is the offending agent in post-diarrhea-associated hemolytic uremic syndrome (HUS), a disorder characterized by thrombocytopenia, microangiopathic hemolytic anemia, and acute kidney failure, with thrombi occluding the renal microvasculature. Endothelial dysfunction has been recognized as the trigger event in the development of microangiopathic processes. Glomerular endothelial cells are susceptible to the toxic effects of Stxs that, via nuclear factor kappa B (NF-κB) activation, induce the expression of genes encoding for adhesion molecules and chemokines, culminating in leukocyte adhesion and platelet thrombus formation on the activated endothelium. Complement activation via the alternative pathway has been seen in patients during the acute phase of STEC-associated HUS. Experimental evidence has highlighted the role of complement proteins in driving glomerular endothelium toward a thrombogenic phenotype. At the glomerular level, podocytes are also an important target of Stx-induced complement activation. Glomerular injury as a consequence of podocyte dysfunction and loss is thus a mechanism that might affect long-term renal outcomes in the disease. New approaches to targeting the complement system may be useful therapeutic options for patients with STEC-HUS.

A pediatric neurologic assessment score may drive the eculizumab-based treatment of Escherichia coli-related hemolytic uremic syndrome with neurological involvement

BACKGROUND

Thrombotic microangiopathy (TMA) is a clinical syndrome encompassing a large group of rare but severe disorders including thrombotic thrombocytopenic purpura (TTP) and both typical and atypical forms of hemolytic uremic syndrome (HUS). The key role of the complement system is well known in TTP and atypical HUS, but recent reports describe its involvement in the pathogenesis of HUS secondary to gastrointestinal infections due to Shiga toxin-producing Escherichia coli (STEC).

METHODS

TMA mainly affects the kidney, but extra-renal complications are frequently described. The involvement of the central nervous system (CNS) represents often a life-threatening condition and it can result in serious long-term disability in HUS patients who overcome the acute phase of illness. In the present study, we retrospectively analyzed a pediatric cohort of a single tertiary pediatric hospital in Southern Italy, in which this complication occurred in 12/54 children (22% of cases), of whom five with severe neurological involvement had been successfully treated with eculizumab.

RESULTS

The great clinical variability of brain injury in our cohort has led us to retrospectively build a "neurological score" useful to assess the clinical severity of neurologic involvement. Subjects with higher neurologic score due to the most severe CNS involvement resulted in the group of patients early treated with eculizumab, obtaining a good clinical response (four out five patients). In conclusion, the early treatment with eculizumab in children with severe neurological involvement during STEC-HUS was associated with complete regression of both acute kidney injury (AKI) and neurological lesions observed at magnetic resonance imaging (MRI).

CONCLUSIONS

A "neurological score" may be a useful tool to drive the early treatment of CNS complications in STEC-HUS with eculizumab, although future perspective controlled studies are urgently needed to validate this therapeutic approach.

Eculizumab in the treatment of Shiga toxin haemolytic uraemic syndrome

Haemolytic uraemic syndrome (HUS) remains a leading cause of paediatric acute kidney injury (AKI). Haemolytic uraemic syndrome is characterised by the triad of microangiopathic haemolytic anaemia, thrombocytopenia and AKI. In ~ 90% of cases, HUS is a consequence of infection with Shiga toxin-producing E. coli (STEC), most commonly serotype O157:H7. Acute mortality from STEC-HUS is now less than 5%; however, there is significant long-term renal morbidity in one third of survivors. Currently, no specific treatment exists for STEC-HUS. There is growing interest in the role of complement in the pathogenesis of STEC-HUS due to the discovery of inherited and acquired dysregulation of the alternative complement system in the closely related disorder, atypical HUS (aHUS). The treatment of aHUS has been revolutionised by the introduction of the anti-C5 monoclonal antibody, eculizumab. However, the role of complement and anti-complement therapy in STEC-HUS remains unclear. Herein, we review the current evidence of the role of complement in STEC-HUS focusing on the use of eculizumab in this disease.

Outbreak of Shiga toxin-producing Escherichia-coli-associated hemolytic uremic syndrome in Istanbul in 2015: outcome and experience with eculizumab

BACKGROUND

This study aims to identify epidemiological and clinical characteristics of patients and report our experience with eculizumab treatment during an outbreak of hemolytic uremic syndrome (HUS) caused by Shiga toxin-producing Escherichia coli (STEC) in Istanbul in 2015.

METHODS

Thirty-two children (21 females, median age 3.25 years) were included in this study. Demographic, clinical and laboratory data, and treatment details were retrospectively collected. Renal outcomes were assessed at last follow-up visit. To assess the effect of eculizumab on prognosis of STEC-HUS, subgroup analysis was performed on patients who required dialysis.

RESULTS

A high number of cases occurred within a certain region of Istanbul. Stool samples were cultured from 21 patients (65%), and enteroaggregative E. coli (EAEC; n = 7) and enterohemorrhagic E. coli (EHEC; n = 3) strains were detected. Rates of dialysis treatment, neurological manifestations, and death were 59%, 25%, and 3%, respectively. Mean follow-up duration was 8.6 ± 2.6 months (range 3-12 months). None of the patients (n = 25) was on dialysis at the final visit. The complete renal recovery rate was 54%. Nine patients were treated with eculizumab. At final follow-up visit, no differences in estimated glomerular filtration rate, proteinuria level, or hypertension incidence were observed between patients treated with eculizumab and those not treated with eculizumab.

CONCLUSIONS

An outbreak of EAEC occurred in a specific region of Istanbul. Livestock markets were suspected as the source. Evidence for beneficial effects of eculizumab on renal outcome was not clear in this cohort.

Complement activation is associated with more severe course of diarrhea-associated hemolytic uremic syndrome, a preliminary study

Diarrhea-associated hemolytic uremic syndrome is characterized by hemolytic anemia, thrombocytopenia, and acute kidney injury secondary to enteric infection, typically Shiga toxin-producing Escherichia coli. Shiga toxin 2 is able to activate alternative complement pathways; therefore, the aim of the study was to analyze C3 as a predictor of clinical courses in patients with diarrhea-associated hemolytic uremic syndrome. We hypothesized that the patients with increased complement activation at admission suffered from a more severe course. We retrospectively analyzed data of 33 pediatric patients between 1999 and 2015 in the Czech Republic. We tested the association of a C3 concentration with biochemical parameters and the clinical data reflecting the severity of the disease. We found significant correlation between the initial C3 and the duration of renal replacement therapy (r = - 0.62, p = 0.0001) and the initial glomerular filtration rate (r = 0.36, p = 0.026). Patients with C3 < 0.825 g/L needed renal replacement therapy and also had significantly more renal complications (p = 0.015).Conclusion: Based on our study, decreased C3 concentrations can be used as one of the risk factors that can help predict the need for acute dialysis and a more severe course of disease in children with diarrhea-associated hemolytic uremic syndrome. What is Known: • Shiga toxin modulates the function of complement regulatory proteins and thus contributes to complement activation in patients with diarrhea-associated hemolytic uremic syndrome. • Risk factors that can predict the need for acute renal replacement therapy and poor outcome in patients with diarrhea-associated hemolytic uremic syndrome are mainly the combination of oligoanuria, dehydration, leukocytosis, high hematocrit > 23%, and neurological involvement. What is New: • A lowered concentration of C3 at the time of initial presentation of diarrhea-associated hemolytic uremic syndrome was associated with more severe renal failure and the need for renal replacement therapy along with the development of more extra renal complications. • Decreased C3 at admission can predict complicated course of diarrhea-associated hemolytic uremic syndrome.

Pathogenic role of inflammatory response during Shiga toxin-associated hemolytic uremic syndrome (HUS)

Hemolytic uremic syndrome (HUS) is defined as a triad of noninmune microangiopathic hemolytic anemia, thrombocytopenia, and acute kidney injury. The most frequent presentation is secondary to Shiga toxin (Stx)-producing Escherichia coli (STEC) infections, which is termed postdiarrheal, epidemiologic or Stx-HUS, considering that Stx is the necessary etiological factor. After ingestion, STEC colonize the intestine and produce Stx, which translocates across the intestinal epithelium. Once Stx enters the bloodstream, it interacts with renal endothelial and epithelial cells, and leukocytes. This review summarizes the current evidence about the involvement of inflammatory components as central pathogenic factors that could determine outcome of STEC infections. Intestinal inflammation may favor epithelial leakage and subsequent passage of Stx to the systemic circulation. Vascular damage triggered by Stx promotes not only release of thrombin and increased fibrin concentration but also production of cytokines and chemokines by endothelial cells. Recent evidence from animal models and patients strongly indicate that several immune cells types may participate in HUS physiopathology: neutrophils, through release of proteases and reactive oxygen species (ROS); monocytes/macrophages through secretion of cytokines and chemokines. In addition, high levels of Bb factor and soluble C5b-9 (sC5b-9) in plasma as well as complement factors adhered to platelet-leukocyte complexes, microparticles and microvesicles, suggest activation of the alternative pathway of complement. Thus, acute immune response secondary to STEC infection, the Stx stimulatory effect on different immune cells, and inflammatory stimulus secondary to endothelial damage all together converge to define a strong inflammatory status that worsens Stx toxicity and disease.

Eculizumab in STEC-HUS: need for a proper randomized controlled trial

Hemolytic uremic syndrome caused by Shiga toxin-producing E. coli (STEC-HUS) is often associated with a severe morbidity including neurological involvement and a mortality of 1-5%. Although STEC-HUS is often self-limited, improvement of treatment strategies is needed for cases with complications and, among others, plasma exchange/plasmapheresis and use of antibiotics have been advocated. With the availability of the complement blocker eculizumab, now a standard treatment of atypical HUS, several series have addressed its use in STEC-HUS, with variable response; randomized controlled trials are lacking.In this issue of Pediatric Nephrology, Pecheron et al. present a cohort of 33 pediatric patients with severe HUS treated with eculizumab. Neurological involvement was observed in 85% of the patients and 94% required dialysis. Most patients (55%) did not benefit from eculizumab and renal dysfunction as well as neurological sequelae did not resolve. In a subgroup of patients, however, rapid neurological improvement was described. In the post-hoc-defined group of patients with favorable outcome, there was a trend towards more sustained complement inhibition, although this finding was not significant compared to patients with an unfavorable outcome.Because multiple interventions were used and the study did not include any control group, future controlled studies are urgently needed to resolve the debate as to whether eculizumab can be an effective treatment for both prevention and treatment of complications in STEC-HUS.

Eculizumab treatment in severe pediatric STEC-HUS: a multicenter retrospective study

BACKGROUND

Hemolytic uremic syndrome related to Shiga-toxin-secreting Escherichia coli infection (STEC-HUS) remains a common cause of acute kidney injury in young children. No specific treatment has been validated for this severe disease. Recently, experimental studies highlight the potential role of complement in STEC-HUS pathophysiology. Eculizumab (EC), a monoclonal antibody against terminal complement complex, has been used in severe STEC-HUS patients, mostly during the 2011 German outbreak, with conflicting results.

METHODS

On behalf of the French Society of Pediatric Nephrology, we retrospectively studied 33 children from 15 centers treated with EC for severe STEC-HUS. Indication for EC was neurologic involvement in 20 patients, cardiac and neurologic involvement in 8, cardiac involvement in 2, and digestive involvement in 3. Based on medical status at last follow-up, patients were divided into two groups: favorable (n = 15) and unfavorable outcomes (n = 18).

RESULTS

Among patients with favorable outcome, 11/14 patients (79%) displayed persistent blockade of complement activity before each EC reinjection. Conversely, in patients with unfavorable outcome, only 9/15 (53%) had persistent blockade (p = n.s.). Among 28 patients presenting neurological symptoms, 19 had favorable neurological outcome including 17 with prompt recovery following first EC injection. Only two adverse effects potentially related to EC treatment were reported.

CONCLUSIONS

Taken together, these results may support EC use in severe STEC-HUS patients, especially those presenting severe neurological symptoms. The study, however, is limited by absence of a control group and use of multiple therapeutic interventions in treatment groups. Thus, prospective, controlled trials should be undertaken.

Shiga Toxin as a Potential Trigger of CFHR1 Deletion-Associated Thrombotic Microangiopathy

Thrombotic microangiopathy (TMA) may result from a variety of clinical conditions, including thrombotic thrombocytopenic purpura, Shiga toxin-producing Escherichia coli-associated hemolytic uremic syndrome and complement-mediated hemolytic uremic syndrome. Thrombocytopenic purpura is diagnosed when ADAMTS13 is <10%, while a diagnosis of Shiga toxin-producing Escherichia coli-associated hemolytic uremic syndrome is made with the evidence of infection by Shiga toxin-producing Escherichia coli. Diagnosis of complement-mediated hemolytic uremic syndrome is not dependent on a specific laboratory test and is a diagnosis of exclusion. TMA is a rare disease and finding individuals that have more than 1 concurrent etiology leading to TMA is even more rare. Here we describe the presentation and management of an individual with CFHR1 deletion-associated TMA also found to have a positive stool Shiga toxin. We discuss the significance of Shiga toxin in serving as a trigger for development of TMA in an individual predisposed to development of TMA due to presence of a homozygous deletion in CFHR1.