Red blood cell-derived arginase release in hemolytic uremic syndrome.

BACKGROUND: Hemolysis is a cardinal feature of hemolytic uremic syndrome (HUS) and during hemolysis excess arginase 1 is released from red blood cells. Increased arginase activity leads to reduced L-arginine, as it is converted to urea and L-ornithine, and thereby reduced nitric oxide bioavailability, with secondary vascular injury. The objective of this study was to investigate arginase release in HUS patients and laboratory models and correlate arginase levels to hemolysis and kidney injury. METHODS: Two separate cohorts of patients (n = 47 in total) with HUS associated with Shiga toxin-producing enterohemorrhagic E. coli (EHEC) and pediatric controls (n = 35) were investigated. Two mouse models were used, in which mice were either challenged intragastrically with E. coli O157:H7 or injected intraperitoneally with Shiga toxin 2. An in vitro model of thrombotic microangiopathy was developed in which Shiga toxin 2- and E. coli O157 lipopolysaccharide-stimulated human blood cells combined with ADAMTS13-deficient plasma were perfused over glomerular endothelial cells. Two group statistical comparisons were performed using the Mann-Whitney test, multiple groups were compared using the Kruskal-Wallis test followed by Dunn's procedure, the Wilcoxon signed rank test was used for paired data, or linear regression for continuous variables. RESULTS: HUS patients had excessively high plasma arginase 1 levels and activity (conversion of L-arginine to urea and L-ornithine) during the acute phase, compared to remission and controls. Arginase 1 levels correlated with lactate dehydrogenase activity, indicating hemolysis, as well as the need for dialysis treatment. Patients also exhibited high levels of plasma alpha-1-microglobulin, a heme scavenger. Both mouse models exhibited significantly elevated plasma arginase 1 levels and activity. Plasma arginase 1 levels correlated with lactate dehydrogenase activity, alpha-1-microglobulin and urea levels, the latter indicative of kidney dysfunction. In the in vitro model of thrombotic microangiopathy, bioactive arginase 1 was released and levels correlated to the degree of hemolysis. CONCLUSIONS: Elevated red blood cell-derived arginase was demonstrated in HUS patients and in relevant in vivo and in vitro models. The excessively high arginase levels correlated to the degree of hemolysis and kidney dysfunction. Thus, arginase inhibition should be investigated in HUS.

[When hemorrhagic enterititis can cause anemia and thrombocytopenia without significant kidney damage.] / Quando l'enterite emorragica può determinare anemia e piastrinopenia senza un rilevante danno renale.

A healthy 9-years-old boy was brought to the Emergency Department for widespread abdominal pain associated with bloody diarrhoea and significant tenesmus, in the absence of fever. Blood tests were compatible with an acute gastroenteritis, even though microbiological tests on stools resulted negative. Given the haemorrhagic dysentery, the boy was hospitalized to start empiric antibiotic therapy and intravenous rehydration. Abdominal ultrasound showed a thickening of colonic walls, mimicking an inflammatory intestinal disease at the onset (subsequently denied by gastro-colonoscopy). Seven days after the onset of symptoms, blood tests revealed microangiopathic anaemia with negative Coombs test, associated with thrombocytopenia. Urine dipstick revealed haematuria and proteinuria in nephritic range. No contraction of diuresis or alteration of renal function were observed (being creatinine values always within the normal range). Laboratory tests were consistent with the diagnosis of Haemolytic Uremic Syndrome (Hus) at the onset. Approximately 1% of paediatric patients with bloody diarrhoea can develop Hus. Positivity for Escherichia coli is not always evident in the stools. Thus, the triad of haemolytic anaemia, thrombocytopenia and renal failure could be present in only 60% of Hus at the onset. The finding of haematuria and/or proteinuria on the urine dipstick may be indicative of early kidney damage, allowing for careful monitoring and a rehydration program that can prevent progression of kidney damage and extrarenal complications.

Hemolytic Uremic Syndrome-Induced Acute Kidney Injury Treated via Immunomodulation with the Selective Cytopheretic Device.

INTRODUCTION: Shiga-toxin associated-hemolytic uremic syndrome (STEC-HUS) is a severe cause of acute kidney injury (AKI) in children. Although most children recover, about 5% die and 30% develop chronic renal morbidity. HUS pathophysiology includes activated neutrophils damaging vascular endothelial cells. Therapeutic immunomodulation of activated neutrophils may alter the progression of disease. We present 3 pediatric patients treated with the selective cytopheretic device (SCD). METHODS: We describe a 12 y.o. (patient 1) and two 2 y.o. twins (patients 2 and 3) with STEC-HUS requiring continuous renal replacement therapy (CRRT) who were enrolled in two separate studies of the SCD. RESULTS: Patient 1 presented with STEC-HUS causing AKI and multisystem organ failure and received 7 days of SCD and CRRT treatment. After SCD initiation, the patient had gradual recovery of multi-organ dysfunction, with normal kidney and hematologic parameters at 60-day follow-up. Patients 2 and 3 presented with STEC-HUS with AKI requiring dialysis. Each received 24 h of SCD therapy. Thereafter, both gradually improved, with normalization (patient 2) and near-normalization (patient 3) of kidney function at 60-day follow-up. CONCLUSION: Immunomodulatory treatment with the SCD was associated with improvements in multisystem stigmata of STEC-HUS-induced AKI and was well-tolerated without any device-related adverse events.

Hyperhydration to Improve Kidney Outcomes in Children with Shiga Toxin-Producing E. coli Infection: a multinational embedded cluster crossover randomized trial (the HIKO STEC trial).

BACKGROUND: Shiga toxin-producing E. coli (STEC) infections affect children and adults worldwide, and treatment remain solely supportive. Up to 15-20% of children infected by high-risk STEC (i.e., E. coli that produce Shiga toxin 2) develop hemolytic anemia, thrombocytopenia, and kidney failure (i.e., hemolytic uremic syndrome (HUS)), over half of whom require acute dialysis and 3% die. Although no therapy is widely accepted as being able to prevent the development of HUS and its complications, several observational studies suggest that intravascular volume expansion (hyperhydration) may prevent end organ damage. A randomized trial is needed to confirm or refute this hypothesis. METHODS: We will conduct a pragmatic, embedded, cluster-randomized, crossover trial in 26 pediatric institutions to determine if hyperhydration, compared to conservative fluid management, improves outcomes in 1040 children with high-risk STEC infections. The primary outcome is major adverse kidney events within 30 days (MAKE30), a composite measure that includes death, initiation of new renal replacement therapy, or persistent kidney dysfunction. Secondary outcomes include life-threatening, extrarenal complications, and development of HUS. Pathway eligible children will be treated per institutional allocation to each pathway. In the hyperhydration pathway, all eligible children are hospitalized and administered 200% maintenance balanced crystalloid fluids up to targets of 10% weight gain and 20% reduction in hematocrit. Sites in the conservative fluid management pathway manage children as in- or outpatients, based on clinician preference, with the pathway focused on close laboratory monitoring, and maintenance of euvolemia. Based on historical data, we estimate that 10% of children in our conservative fluid management pathway will experience the primary outcome. With 26 clusters enrolling a mean of 40 patients each with an intraclass correlation coefficient of 0.11, we will have 90% power to detect a 5% absolute risk reduction. DISCUSSION: HUS is a devastating illness with no treatment options. This pragmatic study will determine if hyperhydration can reduce morbidity associated with HUS in children with high-risk STEC infection. TRIAL REGISTRATION: ClinicalTrials.gov NCT05219110 . Registered on February 1, 2022.

Complement Inhibitors in the Management of Complement-Mediated Hemolytic Uremic Syndrome and Paroxysmal Nocturnal Hemoglobinuria.

BACKGROUND: Complement-mediated HUS (CM-HUS) and paroxysmal nocturnal hemoglobinuria (PNH) are rare hematologic disorders that cause dysregulation and hyperactivation of the complement system. Historically, treatment of CM-HUS involved plasma exchange (PLEX), often with limited benefit and variable tolerance. Conversely, PNH was treated with supportive care or hemopoietic stem cell transplant. Within the last decade, monoclonal antibody therapies that block terminal complement pathway activation, have emerged as less invasive and more efficacious options for management of both disorders. This manuscript seeks to discuss a relevant clinical case of CM-HUS and the evolving landscape of complement inhibitor therapies for CM-HUS and PNH. AREAS OF UNCERTAINTY: Eculizumab, the first humanized anti-C5 monoclonal antibody, has been the standard of care in treating CM-HUS and PNH for over a decade. Although eculizumab has remained an effective agent, the variability in ease and frequency of administration has remained an obstacle for patients. The development of novel complement inhibitor therapies with longer half-lives, has allowed for changes in frequency and route of administration, thus improving patient QOL. However, there are limited prospective clinical trial data given disease rarity, and limited information on variable infusion frequency and length of treatment. THERAPEUTIC ADVANCES: Recently, there has been a push to formulate complement inhibitors that improve QOL while maintaining efficacy. Ravulizumab, a derivative of eculizumab, was developed to allow for less frequent administration, while remaining efficacious. In addition, the novel oral and subcutaneous therapies, danicopan and crovalimab, respectively, along with pegcetacoplan are currently undergoing active clinical trials, and poised to further reduce treatment burden. CONCLUSION: Complement inhibitor therapies have changed the treatment landscape for CM-HUS and PNH. With a significant emphasis on patient QOL, novel therapies continue to emerge and require an in-depth review of their appropriate use and efficacy in these rare disorders. CLINICAL CASE: A 47-year-old woman with hypertension and hyperlipidemia presented with shortness of breath and was found to have hypertensive emergency in the setting of acute renal failure. Her serum creatinine was 13.9 mg/dL; elevated from 1.43 mg/dL 2 years before. The differential diagnosis for her acute kidney injury (AKI) included infectious, autoimmune, and hematologic processes. Infectious work-up was negative. ADAMTS13 activity level was not low at 72.9%, ruling out thrombotic thrombocytopenic purpura (TTP). Patient underwent a renal biopsy, which revealed acute on chronic thrombotic microangiopathy (TMA). A trial of eculizumab was initiated with concurrent hemodialysis. The diagnosis of CM-HUS was later confirmed by a heterozygous mutation in complement factor I (CFI), resulting in increased membrane attack complex (MAC) cascade activation. The patient was maintained on biweekly eculizumab and was eventually transitioned to ravulizumab infusions as an outpatient. Her renal failure did not recover, and the patient remains on hemodialysis while awaiting kidney transplantation.

Prognostic factors among patients with Shiga toxin-producing Escherichia coli hemolytic uremic syndrome: A retrospective cohort study using a nationwide inpatient database in Japan.

INTRODUCTION: Shiga toxin-producing Escherichia coli (STEC) causes hemorrhagic colitis and hemolytic uremic syndrome (STEC-HUS). Understanding its prognostic factors is essential for immediate interventions. We examined early-phase unfavorable prognostic factors among patients with STEC-HUS using a nationwide database. MATERIAL AND METHODS: This is a retrospective cohort study to analyze practice patterns and identify prognostic factors among patients with STEC-HUS. We used the Diagnosis Procedure Combination Database, which includes approximately half of the acute-care hospitalized patients in Japan. We enrolled patients who were hospitalized for STEC-HUS from July 2010 to March 2020. The composite unfavorable outcome included in-hospital death, mechanical ventilation, dialysis, and rehabilitation at discharge. Unfavorable prognostic factors were assessed using a multivariable logistic regression model. RESULTS: We included 615 patients with STEC-HUS (median age, 7 years). Of them, 30 (4.9%) patients had acute encephalopathy and 24 (3.9%) died within 3 months of admission. Unfavorable composite outcome was observed in 124 (20.2%) patients. Significant unfavorable prognostic factors were age of 18 years or older, methylprednisolone pulse therapy, antiepileptic drug administration, and respiratory support within 2 days of admission. DISCUSSION: Patients requiring early steroid pulse therapy, antiepileptic drugs, and respiratory support were considered to be in poor general condition; such patients should receive aggressive intervention to avoid worse outcomes.

Síndrome urémico hemolítico del adulto / Adult hemolytic uremic syndrome

El síndrome urémico hemolítico (SUH), descripto en 1955, se caracteriza por la tríada de anemia hemolítica no inmunomediada, trombocitopenia y lesión renal aguda. En su patogenia interviene la toxina Shiga, producida con mayor frecuencia por E. coli O157:H. Puede manifestarse a cualquier edad, aunque es infrecuente en adultos, y se desarrolla en forma esporádica o en brote. Se presenta con un cuadro de dolor abdominal, diarrea, fiebre y vómitos. Puede afectar el sistema nervioso central, pulmones, páncreas y corazón. En adultos, el síndrome evoluciona tras un período de incubación de 1 semana posterior a la diarrea y tiene alta morbimortalidad, a diferencia de los casos pediátricos. Presentamos el caso de una paciente adulta, que cursó internación por síndrome urémico hemolítico. (AU)

Hemolytic uremic syndrome (HUS), described in 1955, is characterized by the triad of non-immune mediated hemolytic anemia, thrombocytopenia, and acute kidney injury. Shiga toxin, produced most frequently by E coli O157:H, is involved in its pathogenesis. Hus can manifest at any age, although it is rare in adults and develops sporadically or in outbreaks. HUS presents with a picture of abdominal pain, diarrhea, fever and vomiting. It can affect the central nervous system, lungs, pancreas, and heart.In adults, the syndrome evolves after an incubation period of 1 week after diarrhea, with high morbidity and mortality, unlike pediatric cases.We present the case of an adult patient who was hospitalized for hemolytic uremic syndrome. (AU)

Long-term kidney outcomes in non-dialyzed children with Shiga-toxin Escherichia coli associated hemolytic uremic syndrome.

BACKGROUND: Long-term kidney outcomes of non-dialyzed children with Shiga-toxin Escherichia Coli hemolytic uremic syndrome (STEC-HUS) have been scantily studied. Therefore, we aimed to evaluate kidney outcomes and prognostic markers in these patients. METHODS: Non-dialyzed STEC-HUS patients followed for at least 5 years were included. They were grouped and compared according to kidney status at last visit: complete recovery (CR) or chronic kidney disease (CKD). Predictors of CKD evaluated at diagnosis were sex, age, leukocytes, hematocrit, hemoglobin (Hb), and serum creatinine (sCr). Peak sCr and time of follow-up were also analyzed. RESULTS: A total of 122 patients (62 female, median age at diagnosis 1.6 years) with a median follow-up of 11.3 years were included. At last visit, 82 (67%) had CR, 36 (30%) had CKD stage 1, and 4 (3%) had stage 2. No patient developed CKD stage 3-5. Median time to CKD was 5 years (IQR 3.1-8.76 years). Of the 122 patients, 18% evolved to CKD in the first 5 years, increasing to 28% at 10 and 33% at 20 years of follow-up. Serum Cr at diagnosis and peak sCr were significantly higher in patients with CKD than in those with CR. CONCLUSIONS: One third of non-dialyzed STEC-HUS patients evolved to CKD after a median time of 5 years. However, CKD may appear even after 15 years of CR. Serum Cr was significantly higher among patients who evolved to CKD. These data reinforce that all non-dialyzed patients should be followed until adulthood. A higher resolution version of the Graphical abstract is available as Supplementary information.

[Thrombotic microangiopathy]. / Thrombotische Mikroangiopathien.

In the emergency room, patients with anemia and thrombocytopenia are common. Although these findings can often be explained by the medical situation, thrombotic microangiopathy is an important differential diagnosis. In this case, occlusion of the smallest vessels consequently leads to functional impairment of the affected organs. Patients generally present with symptoms of organ dysfunction, e.g., in the kidney or brain. Characteristically, Coombs-negative fragmentation of erythrocytes with hemolysis occurs in the area of the occluded vessels. Lactate dehydrogenase levels are elevated, and platelets and haptoglobin are reduced. Differential diagnoses beyond thrombotic microangiopathy that should be considered are numerous and diverse in their pathophysiology. Rapid workup is needed, because sometimes a specific treatment must be initiated rapidly. For example, thrombotic thrombocytopenic purpura leads to death in about 90% of patients if left untreated. However, by reconstitution of the underlying deficiency of the so-called ADAMTS13 (a disintegrin and metalloproteinase with a thrombospondin type 1 motif, member 13) by plasma separation, survival can be ensured in most cases. Complement-mediated hemolytic uremic syndrome should also be considered and, if suspected, treated with complement inhibition. In many cases, however, thrombotic microangiopathy reflects a disorder elsewhere and may be a manifestation of severe hypertension or a coagulation disorder, such as disseminated intravascular coagulation or antiphospholipid syndrome. It can also be observed as a consequence of drug therapies or metabolic derangement. Systemic workup is therefore necessary for rapid clarification of differential diagnoses.

Minor Cross-Matching in the Diagnosis of Pneumococcal Hemolytic Uremic Syndrome in an 18-Month-Old Boy.

In developing nations, limitations in diagnostic facilities act as a barrier for differentiation of hemolytic uremic syndrome (HUS) based on the etiology. A sick-looking 18-month-old boy presented to our hospital in Bhubaneswar, India, with clinical signs and symptoms of left lobar pneumonia, abnormal hematological and renal parameters, no growth in blood culture, a negative direct antiglobulin test (DAT) result, and low complement levels. A rapid deterioration in his clinical condition necessitated intensive care support, blood transfusion, and renal replacement therapy (peritoneal dialysis and hemodialysis). Because his health care team suspected atypical HUS, therapeutic plasma exchange (TPE) was initiated as soon as possible. In the absence of a lectin panel, minor cross-matching confirmed T-antigen exposure. With a diagnosis of HUS induced by Streptococcus pneumoniae (sp-HUS), TPE was stopped immediately, and washed blood components were administered. Despite the aforementioned measures, the boy died of HUS on day 20 after presentation. This case emphasized the role of minor cross-matching in the detecting of polyagglutination in resolving the diagnostic dilemma of sp-HUS.

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.

Síndrome urémico hemolítico: reporte de dos casos pediátricos con nexo epidemiológico / Hemolytic uremic syndrome: report of two pediatric clinical cases with epidemiologic link / Síndrome urémico hemolítico: reporte de casos pediátricos con nexo epidemiológico

Introducción: el síndrome hemolítico urémico (SHU) es en muchos países, de las causas más frecuentes de insuficiencia renal aguda. La mayoría de los casos ocurre luego de un episodio de gastroenteritis aguda (GEA) por Escherichia coli productora de toxina Shiga (STEC). En Uruguay a pesar de ser una enfermedad de notificación obligatoria, existe subregistro. Objetivo: describir dos casos clínicos de SHU asociados a GEA con nexo epidemiológico. Casos clínicos: se trata de dos varones de 4 y 5 años, sanos. En los días previos, ingesta de carne en el mismo local comercial. Consultaron por dolor abdominal, deposiciones líquidas y vómitos reiterados. El niño de 4 años presentaba fiebre y deposiciones líquidas con sangre. El niño de 5 años dolor abdominal. El estado de hidratación y las constantes vitales eran normales en ambos. Fueron admitidos a cuidados moderados. A las 48 horas y a los 5 días, respectivamente, agregan palidez cutáneo-mucosa intensa, edemas y oliguria. Estudios complementarios: anemia, plaquetopenia e insuficiencia renal. Ingresaron a cuidados intensivos y se realizó diálisis peritoneal. La investigación de STEC fue negativa y la evolución favorable. Conclusiones: en menores de 5 años el SHU asociado a GEA es la forma de enfermedad más frecuente. En Uruguay predominan las cepas STEC no-O157. En estos casos no se pudo identificar el agente. La existencia de un nexo epidemiológico alerta sobre la necesidad de extremar los cuidados en la preparación y cocción de la carne. Debido a la asociación con una enfermedad prevalente, es necesario tener presente esta complicación para poder sospecharla e iniciar el tratamiento en forma precoz y oportuna.

Introduction: hemolytic uremic syndrome (HUS) is one of the most frequent causes of acute renal failure in many countries. Most cases occur after an episode of acute gastroenteritis (GEA) due to the Shiga toxin producing Escherichia Soli (STEC). In Uruguay, despite being a disease that requires mandatory notification, it is under reported. Objective: to describe two clinical cases of HUS associated with GEA with an epidemiological link. Clinical cases: these are two healthy boys aged 4 and 5 years. In the previous days, they reported meat intake in the same commercial premises. They consulted for abdominal pain, liquid stools and repeated vomiting. The 4 year old boy had a fever and bloody stools. The 5 year old boy had abdominal pain. They both showed normal hydration levels and vital signs. They were admitted to moderate care. At 48 hours and 5 days, respectively, they showed intense skin and mucosal paleness, edema and oliguria. Complementary studies: anemia, thrombocytopenia and renal failure. They were admitted to intensive care and peritoneal dialysis was performed. The STEC's investigation was negative and the evolution favorable. Conclusions: in children under 5 years of age, HUS associated with GEA is the most frequent form of the disease. In Uruguay, non-O157 STEC strains predominate. In these cases, the agent could not be identified. The existence of an epidemiological link warns us about the need for extreme care in the preparation and cooking of meat. Due to the association with a prevalent disease, it is necessary to keep this complication in mind in order to suspect it and initiate early and timely treatment.

Introdução: a síndrome hemolítico urêmica (SHU) é uma das causas mais frequentes de insuficiência renal aguda em muitos países. A maioria dos casos ocorre após um episódio de gastroenterite aguda (GEA) devido à Escherichia Coli, a toxina produtora de Shiga (STEC). No Uruguai, apesar de ser uma doença de notificação compulsória, há subnotificação. Objetivo: descrever dois casos clínicos de SHU associada à AGE com vínculo epidemiológico. Casos clínicos: dois meninos saudáveis com idades entre 4 e 5 anos. Nos dias anteriores, eles reportaram consumo de carne nos mesmos estabe- lecimentos comerciais. Eles consultaram para dor abdominal, fezes líquidas e vômitos repetidos. O menino de 4 anos teve febre e fezes com sangue. O menino de 5 anos teve dores abdominais. O estado de hidratação e os sinais vitais foram normais em ambos meninos. Foram internados em cuidados moderados. Às 48 horas e 5 dias, respectivamente, apresentaram aliás palidez intensa da pele e mucosas, edema e oligúria. Realizaramse estudos complementares: anemia, trombocitopenia e insuficiência renal. Eles foram internados em terapia intensiva e realizouse diálise peritoneal. A investigação do STEC foi negativa e a evolução favorável. Conclusões: em crianças menores de 5 anos, a SHU associada à GEA é a forma mais frequente da doença. No Uruguai, predominam cepas STEC não-O157. Nesses casos, o agente não pôde ser identificado. A existência de um nexo epidemiológico alerta para a necessidade de extremo cuidado no preparo e cozimento da carne. Devido à associação com doença prevalente, é necessário considerar essa complicação para suspeitar e iniciar o tratamento precoce e oportunamente.

Haemolytic uraemic syndrome.

Haemolytic uraemic syndrome (HUS) is a heterogeneous group of diseases that result in a common pathology, thrombotic microangiopathy, which is classically characterised by the triad of non-immune microangiopathic haemolytic anaemia, thrombocytopenia, and acute kidney injury. In this Seminar, different causes of HUS are discussed, the most common being Shiga toxin-producing Escherichia coli HUS. Identifying the underlying thrombotic microangiopathy trigger can be challenging but is imperative if patients are to receive personalised disease-specific treatment. The quintessential example is complement-mediated HUS, which once carried an extremely high mortality but is now treated with anti-complement therapies with excellent long-term outcomes. Unfortunately, the high cost of anti-complement therapies all but precludes their use in low-income countries. For many other forms of HUS, targeted therapies are yet to be identified.

Thrombotic Thrombocytopenic Purpura: From 1972 to 2022 and Beyond.

This review tells the story of my personal experience with thrombotic thrombocytopenic purpura (TTP). It begins with my first encounter with TTP 50 years ago when 2 sisters presented 2 years apart, both pregnant and both died. At that time, I knew nothing about hereditary TTP (hTTP), the risks of pregnancy, or effective treatments. In 1991, a year after I moved to Oklahoma, therapeutic plasma exchange (TPE) was established as an effective treatment. With the availability of effective treatment, the number of patients presenting with suspected TTP soared. The diagnosis of TTP was imprecise. I worked with the Oklahoma Blood Institute (OBI) to understand the management of TTP. Because the OBI provided all TPE procedures for most of Oklahoma, we saw all consecutive patients within a defined geographic area who were identified at a uniform time early in the course of their TTP, without selection or referral bias. It was an inception cohort; this became the Oklahoma TTP Registry. In 2001, we began a very successful collaboration with the University of Bern, Switzerland, to measure ADAMTS13 activity in all of our patients. From our patients, we learned that acquired, autoimmune TTP (iTTP) is a chronic disease with risks for cognitive impairment and depression. Recognition in 2012 of three sisters with hTTP was reminiscent of the beginning of my story. hTTP has risks for multiple severe morbidities, beginning at birth and especially during pregnancy. Future management of both iTTP and hTTP will be more effective and more convenient.

Recurrent microangiopathic hemolysis after recovery from complement-mediated hemolytic uremia syndrome during chemotherapy for a CFH-mutated patient with T-lymphoblastic lymphoma.

Complement-mediated hemolytic uremic syndrome (CM-HUS) following chemotherapy for pediatric acute lymphoid neoplasms has rarely been reported. We report the case of an 8-year-old boy with T-lymphoblastic lymphoma (T-LBL) who developed CM-HUS with complement factor H (CFH) mutations (S1191L, V1197A) during induction therapy. Safe administration of chemotherapy after CM-HUS recovery was challenging. By closely monitoring hemolytic and renal parameters during the 2-year treatment period, we observed four episodes of microangiopathic hemolytic anemia (MAHA) with hypocomplementemia and low haptoglobin but no renal dysfunction or thrombocytopenia. Here, we describe the MAHA and CM-HUS episodes in the hopes of elucidating the complex pathophysiology of disorders associated with CFH mutation.

Development and pilot implementation of Iranian Hemolytic Uremic Syndrome Registry.

BACKGROUND: Patients with Hemolytic Uremic Syndrome (HUS) face late diagnosis and lack of appropriate treatment because of a lack of knowledge and experience in this field. A prerequisite for such knowledge is the development of research infrastructures such as a registry system. Therefore, this study aimed to develop and describe the HUS registry in accordance with the Iranian health system and implement its software system. METHODS: We first interviewed 10 pediatric nephrologists and after analyzing the interviews, we identified the features and requirements and the data related to HUS. Then, during two rounds of the Delphi technique (the first round with 23 participants and the second round with 18 participants), the model of this registry was finalized based on the agreement of at least 75% of specialists. At the next step, based on the agreed requirements, IRI.HUS.Reg (Iranian Hemolytic Uremic Syndrome Registry) software was developed and implemented in a pediatric hospital. RESULTS: We classified 369 meaning units of interviews in 41 codes and 7 final themes including purposes of the registry (10 codes), inclusion criteria (7 codes), data collection method (4 codes), data quality control (6 codes), data sources (4 codes), data analysis (3 codes) and software features (7 codes). These 7 feature groups (67 subgroups) and 12 data classes (138 data elements) include demographic data, referrals, examinations, clinical signs, causes, laboratory tests, medical histories, paraclinical measures, treatments, outcomes, patient's status at discharge, and follow-up data were reviewed by the Delphi panelists, and finally, 64 features and 131 data elements were accepted by at least 78% agreement. Then, we developed and implemented a registry software system in a hospital. CONCLUSION: We implemented IRI.HUS.Reg based on related features, 12 data classes agreed by specialists, literature review, and comparison with other existing registries. Therefore, the data collected in this registry can be compared with other data from existing registries in other countries.

Clinical features of children with anti-CFH autoantibody-associated hemolytic uremic syndrome: a report of 8 cases.

OBJECTIVE: To explore the clinical characteristics, treatment protocol and prognosis of children with anti-complement factor H (CFH) autoantibody (Ab)-associated hemolytic uremic syndrome (HUS). METHODS: Clinical data of 8 patients with anti-CFH Ab-associated HUS who were admitted to Shandong Provincial Hospital from January 2011 to December 2020 were collected retrospectively. RESULTS: The age at disease onset ranged between 5.83 and 13.5 years, with a male: female ratio of 1.67:1. The time of onset was distributed from May to June and November to December. Digestive and upper respiratory tract infections were common prodromal infections. Positivity for anti-CFH Ab and reduced C3 levels were observed among all patients. Heterozygous mutation of the CHFR5 gene (c.669del A) and homozygous loss of the CFHR1 gene [loss2(EXON:2-6)] were found in two patients. All patients received early treatment with plasma exchange and corticosteroid therapy. Six patients were given immunosuppressive agents (cyclophosphamide and/or mycophenolate mofetil) for persistent proteinuria. The follow-up period was 12-114 months. Four of 8 patients achieved complete remission, 3 achieved partial remission, and 1 died. Relapse occurred in two patients. CONCLUSION: Children with anti-CFH Ab-associated HUS were mainly school-aged and predominantly male, with onset times of summer and winter. Digestive and upper respiratory tract infections were common prodromal infections. Plasma exchange combined with methylprednisolone pulse therapy in the acute phase and cyclophosphamide or mycophenolate mofetil treatment for maintenance can be utilized in children with anti-CFH Ab-associated HUS if eculizumab is not available.