Progress on diagnosis and treatment of kidney transplantation-associated thrombotic microangiopathy / 器官移植

Thrombotic microangiopathy (TMA) is a severe complication after kidney transplantation, mainly characterized by thrombocytopenia, microvascular hemolytic anemia and acute kidney injury, which may lead to kidney allograft failure or even death of the recipients. With the increasing quantity of solid organ transplantation in China and deeper understanding of TMA, relevant in-depth studies have been gradually carried out. Kidney transplantation-associated TMA is characterized with different causes and clinical manifestations. Non-invasive specific detection approach is still lacking. The diagnosis of TMA mainly depends on renal biopsy. However, most TMA patients are complicated with significant thrombocytopenia. Hence, renal puncture is a risky procedure. It is difficult to make a definite diagnosis. For kidney transplantation-associated TMA, plasma exchange, intravenous immunoglobulin and withdrawal of potential risk drugs are commonly employed. Nevertheless, the overall prognosis is poor. In this article, the classification of TMA after kidney transplantation, diagnosis and treatment of kidney transplantation-associated TMA were reviewed, aiming to provide reference for clinical diagnosis and treatment of kidney transplantation-associated TMA.

Clinical characteristics and prognosis of anti-factor H antibody associated-atypical hemolytic uremic syndrome in children / 中华实用儿科临床杂志

Objective:To summarize the clinical data of anti-factor H antibody-associated atypical hemolytic uremic syndrome (aHUS) in children, and analyze the risk factors for disease recurrence and poor prognosis.Methods:A prospective cohort study was conducted on 52 children with anti-factor H antibody-associated aHUS in Beijing Children′s Hospital, Capital Medical University from November 2011 to November 2021.Patient information about the genetic background, clinical and renal pathological characteristics, treatment, and prognosis were collected.Then, the disease recurrence and prognosis were analyzed using the survival curve and Cox regression model. Results:In 52 children, there were 33 males and 19 females.The average age of onset for aHUS was 2.4-12.8 years, and 92.3%(48/52) of the children developed symptoms at the age of 4-12 years.The copy numbers of complement factor-H-related 1 (CFHR1) and complement factor-H-related 3 (CFHR3) genes were calculated in 42 children.Among the 42 cases, 18 cases (42.9%) had CFHR1 homozygous deletion, and 83.3% (15/18) of them also had CFHR3 homozygous deletion.All the patients were given plasma therapy.Besides, 76.9% (40/52) of the children were treated with immunosuppressive therapy (steroid and/or immunosuppressant) at the first onset of the disease.About 86.5%(45/52 cases) of the patients received immunosuppressive therapy in the course of disease, and the immunosuppressive treatment lasted for 6-20 months in total.The median follow-up time was 58 (28, 91) months.Among 52 patients, only 12 patients (23.1%) suffered disease recurrence.The relapse-free survival rate in children with CFHR1 homozygous deletion was significantly lower than that in children with non-homozygous deletion ( χ2=4.700, P=0.030). The relapse-free survival rate in children with CFHR1 and CFHR3 homozygous deletions was also significantly lower than that in other children ( χ2=4.181, P=0.041). At the end of the follow-up, 73.1%(38/52) of the children had normal renal function and no persistent proteinuria or hypertension.23.1%(12/52 cases) of the children had persistent proteinuria and/or hypertension.One child had Stage 3-4 chronic kidney disease, and 1 child was dialysis dependent. Conclusions:Anti-factor H antibody-associated aHUS is prone to occur in children aged between 4-12 years old, who respond well to plasma therapy and immunosuppressive therapy.Children with anti-factor H antibody-associated aHUS and CFHR1 and CFHR3 homozygous deletions have a high recurrence rate.Treatment with immunosuppressive therapy and assessment of the copy number of CFHR1 and CFHR3 genes in the early stage of the disease are important for preventing disease recurrence and improving prognosis.

Research progress on anti-factor H antibody associated atypical hemolytic uremic syndrome / 中华实用儿科临床杂志

Atypical hemolytic uremic syndrome (aHUS) is a rare acute and critical disease in childhood, which is easy to lead to acute kidney injury, and has a high mortality rate and chronic kidney disease incidence if not diagnosed and treated in time.According to the etiology, aHUS can be classified into hereditary and acquired.Anti-factor H antibody associated aHUS is acquired and mainly occurs in children aged 5 to 15 years.Anti-factor H antibody associated aHUS is strongly associated with homozygous deletion of the complement H related protein 1/3 (CFRH1/3) gene.In recent years, there have been significant advances in the etiology, genetics, and immunology of aHUS, especially the treatment of Eculizumab, which has greatly improved the prognosis of the disease.However, at present, there are still problems that need to be solved in the pathogenesis, diagnosis, treatment and prognosis of antibody-related aHUS, and this article will discuss the above content and put forward corresponding prospects to provide reference for clinical and scientific research.

Manifestaciones hepatopancreáticas en síndrome hemolítico urémico atípico

Introducción: el síndrome hemolítico urémico atípico es una enfermedad severa y huérfana, la cual en su variedad atípica se presenta con manifestaciones clínicas extrarrenales y sistémicas. La presencia de afectación gastrointestinal es infrecuente, pero en los pacientes en los que se manifiesta el pronóstico desfavorable, dado que estos cursan con más recaídas y mayor mortalidad, por lo cual se hace indispensable que el personal de salud esté entrenado en detectar y reconocer las manifestaciones menos frecuentes de esta patología, para así impactar positivamente en el desenlace de estos pacientes. Objetivo: se busca ilustrar un caso singular en cuanto a la sintomatología presentada infrecuente por el paciente y sobre una etiología no descrita previamente en la literatura. Presentación del caso: se reporta el caso de un escolar masculino de 8 años que presentó fiebre, ictericia, dolor abdominal y lumbar, diarrea, hematemesis y hematuria, al cual se le diagnosticó síndrome hemolítico urémico atípico. El paciente presentó un rápido deterioro clínico con compromiso multiorgánico, documentándose hipertensión arterial y lesión renal aguda, que recibió manejo con cristaloides y diurético de asa sin mejoría, por lo que requirió inicio de terapia de reemplazo renal e incluso múltiple soporte transfusional; sin embargo, continuó sin mejoría clínica, por lo que se indicó inicio de anticuerpo monoclonal IgG humanizado recombinante con buenos resultados. Discusión y conclusión: este caso es un claro ejemplo de que la afectación extrarrenal y multiorgánica puede ser la manifestación principal de esta enfermedad, por lo que es importante que el clínico se encuentre sensibilizado y conozca los signos y los síntomas de la presentación atípica de esta patología, con el fin de evitar retrasos diagnósticos y terapéuticos. Asimismo, el abordaje etiológico es de suma importancia para brindar un pronóstico más preciso al paciente y su familia.

Introduction: Atypical hemolytic uremic syndrome is a severe and orphan disease, in its atypical variety courses with extrarenal clinical manifestations. The presence of gastrointestinal compromise is infrequent, but the prognosis is unfavorable, since they have more relapses and higher mortality. Therefore, it is important that physicians are trained in recognizing the rare manifestations of this pathology, in order to improve the outcome in these patients. Purpose: This case illustrates a unique case in terms of symptoms and etiology not previously described. Case presentation: We report the case of an 8-year-old male who presented with fever, jaundice, abdominal and lumbar pain, diarrhea, hematemesis, and hematuria. Atypical hemolytic uremic syndrome was diagnosed. He presented clinical deterioration with multiple organ involvement, documenting high blood pressure and acute kidney injury, who received management with crystalloids and diuretics without improvement, requiring renal replacement therapy and multiple transfusional support. However, there was still no clinical improvement, so the start of recombinant humanized IgG monoclonal antibody was indicated, with satisfactory outcomes. Discussion and conclusions: This case is a clear example that extrarenal and multi-organ involvement can be the main manifestation of this disease, so it is important that clinicians are aware of the clinical course that may develop a patient with atypical presentations, in order to avoid diagnostic and therapeutic delays. Likewise, the etiological approach is important in order to provide an accurate prognosis to the patient and his family.

Complement Inhibitors in Rare Diseases / 罕见病研究

The complement system is a self-protection mechanism of the human body. The abnormal activation of the complement system is involved in the occurrence and development of various diseases. The application of complement inhibitors in many rare diseases was a milestone in leading to the progress of such disease as paroxysmal nocturnal hemoglobinuria (PNH), atypical hemolytic uremic syndrome (aHUS), and others. Recently, the application of complement inhibitors has gradually expanded to other complement-related diseases. This review summarizes the literature on the current application of complement inhibitors in rare diseases and looks into the prospects of the application in the rare diseases.

Anuria, Sudden Blindless, Confusion: A Case of Unusual "Adult Still Disease" / 罕见病研究

A young female patient presented with fever, arthralgia, and rash was diagnosed with adults still's disease. When treated with glucocorticoid steroid, the above patient progressed to anuria, sudden, and confusion. After a teamwork involving different departments, the patient was finally diagnosed with atypical hemolytic uremic syndrome (aHUS) and treated with good outcome. aHUS is a rare disease, while Eculizumab is an orphan drug. The diagnosis and treatment of the patient reveals the importance of multidisciplinary team on the diagnosis and treatment of rare and difficult diseases.

Nephrotic syndrome associated with primary atypical hemolytic uremic syndrome / Síndrome nefrótica associada à síndrome hemolítico-urêmica atípica primária

Abstract Primary atypical hemolytic-uremic syndrome is a rare disease characterized by non-immune microangiopathic hemolytic anemia, thrombocytopenia, and renal dysfunction; it is related to alterations in the regulation of the alternative pathway of complement due to genetic mutations. The association with nephrotic syndrome is unusual. We present here a pediatric patient diagnosed with primary atypical hemolytic-uremic syndrome associated with nephrotic syndrome who responded to eculizumab treatment.

Resumo A síndrome hemolítico-urêmica atípica primária é uma doença rara, caracterizada por anemia hemolítica microangiopática não-imune, trombocitopenia e disfunção renal; está relacionado a alterações na regulação da via alternativa do complemento devido a mutações genéticas. A associação com a síndrome nefrótica é incomum. Apresentamos aqui um paciente pediátrico com diagnóstico de síndrome hemolítico-urêmica atípica primária associada à síndrome nefrótica que respondeu ao tratamento com eculizumab.

Genetic atypical hemolytic uremic syndrome in children: a 20-year experience from a tertiary center / Síndrome hemolítica urêmica atípica genética em crianças: uma experiência de 20 anos a partir de um centro terciário

Abstract Introduction: Atypical hemolytic uremic syndrome (aHUS) is a rare disorder characterized by the triad of microangiopathic hemolytic anemia, thrombocytopenia, and acute kidney injury, which primarily affects preschool-aged children. This study's aim was to describe the clinical profile, management, and long-term outcome of the genetic aHUS patients admitted to a tertiary care pediatric nephrology center during 20 years. Methods: We performed a retrospective analysis of the clinical records of all aHUS patients younger than 18 years with identified genetic mutations. Data on clinical features, genetic study, therapeutic interventions, and long-term outcomes were reviewed. Results: Five cases of aHUS with an identified genetic mutation were included; all were inaugural cases with the youngest being 4 months old. Complement factor H gene mutation was identified in four patients. Therapeutic plasma exchange was performed for acute management in 4 patients, one of whom also needed acute renal replacement therapy (peritoneal dialysis). All patients went on complete remission, 2 had more than one relapse but only 1 of these progressed to chronic kidney disease during the follow-up period (median (25th-75th percentile), 136 (43.5-200.5) months). Conclusion: In children, the prognosis of renal function seems to be strongly dependent on the genetic background, thus being crucial to perform genetic study in all aHUS cases. In our cohort, 2 patients presented genetic mutations not previously described. Recent innovations on the genetic field leading to the identification of new mutations has lead to a better understanding of aHUS pathogenesis, but further studies, focusing on the genotype-phenotype correlation, with longer follow-up periods, are needed.

Resumo Introdução: A síndrome hemolítica urêmica atípica (SHUa) é um distúrbio raro caracterizado pela tríade de anemia hemolítica microangiopática, trombocitopenia e lesão renal aguda, afetando principalmente crianças em idade pré-escolar. O objetivo deste estudo foi descrever perfil clínico, manejo e desfecho em longo prazo dos pacientes com SHUa genética admitidos em um centro terciário de nefrologia pediátrica durante 20 anos. Métodos: Realizamos análise retrospectiva dos registros clínicos de todos os pacientes com SHUa menores de 18 anos com mutações genéticas identificadas. Revisaram-se dados sobre características clínicas, estudo genético, intervenções terapêuticas e desfechos em longo prazo. Resultados: Incluíram-se cinco casos de SHUa com uma mutação genética identificada; sendo todos casos inaugurais, o mais jovem tendo 4 meses de idade. A mutação no gene do fator H do complemento foi identificada em quatro pacientes. Plasmaférese terapêutica foi realizada para tratamento agudo em 4 pacientes, um dos quais também necessitou terapia renal substitutiva aguda (diálise peritoneal). Todos os pacientes tiveram remissão completa, 2 mais de uma recidiva, mas apenas 1 evoluiu para doença renal crônica durante acompanhamento (mediana (percentil 25°-75°), 136 (43,5-200,5) meses). Conclusão: Em crianças, o prognóstico da função renal parece ser fortemente dependente do histórico genético, sendo crucial realizar estudo genético em todos os casos de SHUa. Em nossa coorte, 2 pacientes apresentaram mutações genéticas não descritas anteriormente. Inovações recentes no campo genético que levaram à identificação de novas mutações conduziram a um melhor entendimento da patogênese SHUa, mas são necessários mais estudos, focando na correlação genótipo-fenótipo, com períodos de acompanhamento mais longos.

Microangiopatías trombóticas primarias: una revisión narrativa / Primary thrombotic microangiopathies: a narrative review

La microangiopatía trombótica (MAT) es un síndrome donde hay formación de microtrombos en la circulación que llevan a anemia hemolítica microangiopática (AHMA) y trombocitopenia con falla multiorgánica, debido a la isquemia de los tejidos. Las MAT pueden ser primarias sin causa subyacente asociada, como la púrpura trombocitopénica trombótica debida a deficiencia de la enzima ADAMTS13, el síndrome hemolítico urémico debido a la toxina Shiga de Escherichia coli enterohemorrágica, y la MAT producida por alteraciones en la regulación del complemento. Adicionalmente, pueden ser secundarias a enfermedades malignas, infecciosas, metabólicas, autoinmunes o inducidas por el embarazo. Estas patologías requieren diagnóstico y tratamiento oportunos debido a que tienen alta morbimortalidad y se asocian a complicaciones que incluyen enfermedad renal, alteraciones neurológicas como convulsiones, accidente cerebrovascular, coma y muerte. El tratamiento es multidisciplinario y se enfoca en el soporte hemodinámico, transfusional y en el manejo de la etiología cuando esta es identificada. La siguiente revisión pretende explicar de forma clara y precisa los aspectos generales de las MAT primarias

Thrombotic microangiopathy (TMA) is a syndrome characterized by the formation of microthrombi in the circulation leading to microangiopathic hemolytic anemia (MAHA) and thrombocytopenia, with multiorgan failure due to tissue ischemia. TMA can be primary with no associated underlying cause, such as thrombotic thrombocytopenic purpura due to ADAMTS13 deficiency, hemolytic uremic syndrome due to the Shiga toxin from enterohemorrhagic Escherichia coli, or due to complement dysregulation. Furthermore, TMA can be secondary to malignant, infectious, metabolic or autoimmune diseases, or induced by pregnancy. These conditions require a timely diagnosis and treatment due to their associated high morbidity and mortality, and complications like renal disease, neurological disorders such as seizures, stroke, coma and death. Treatment is multidisciplinary and focuses on hemodynamic and transfusion support, and on the management of the etiology when it is identified (daily plasma exchange, eculizumab or management of underlying disease). This review aims to discuss the general aspects of primary thrombotic microangiopathies

Biomarcadores y blancos moleculares del complemento en el diagnóstico de las microangiopatías trombóticas / Complement biomarkers and molecular targets in the diagnosis of thrombotic microangiopathies / Biomarcadores e alvos moleculares do complemento no diagnóstico das microangiopatias trombóticas

Resumen El sistema del complemento juega un papel central en la inmunidad innata, es una línea de defensa contra patógenos y participa en la homeostasis. La activación anormal del complemento contribuye al desarrollo de patologías de variable severidad, tanto inmunológicas y hematológicas como renales. Entre ellas, las microangiopatías trombóticas (MAT) representan un grupo de enfermedades raras con manifestaciones clínicas comunes caracterizadas por anemia hemolítica no inmune, trombocitopenia y daño de órgano(s) blanco. Si bien la clasificación de las MAT sigue siendo desafiante y no ha sido internacionalmente estandarizada, la descripción de entidades asociadas a anomalías del complemento fue comprobada con la eficiencia de la terapia anticomplemento en los pacientes. Las herramientas de diagnóstico desarrolladas en las últimas décadas son esenciales actualmente para diferenciar las MAT más características del grupo; esto es, la púrpura trombótica trombocitopénica (PTT) y el síndrome urémico hemolítico (SUH). En el presente trabajo se presenta una revisión del funcionamiento del sistema del complemento en condiciones fisiológicas, para poder explicar luego cuáles son las alteraciones del sistema implicadas en el desarrollo de las MAT y describir las herramientas disponibles para detectarlas en el laboratorio.

Abstract The complement system plays a crucial role in the innate immune response, being the first-line defense against pathogens and regulating homeostasis. Uncontrolled complement activation can cause immunologic, hematologic as well as renal syndromes of variable severity. Among them, thrombotic microangiopathies (TMA) represent a group of rare diseases characterised by similar clinical manifestations such as microangiopathic hemolytic anemia (MAHA), peripheral thrombocytopenia and organ injury. Although TMA classification is still challenging and no international consensus has been reached, complement-associated disorders have been described thanks to the efficiency of anti-complement therapy in patients. Diagnostic tools developed in the last decades are essential to differentiate the two most well characterized TMA: thrombotic thrombocytopenic purpura (TTP) and hemolytic uremic syndrome (HUS). This review will describe how the complement system works in physiological conditions in order to explain how complement abnormalities are involved in TMA, and finally how to detect those anomalies using laboratory tests.

Resumo O sistema do complemento desempenha um papel central na imunidade inata, sendo uma linha de defesa contra patógenos e participando da homeostase. A ativação anormal do complemento contribui para o desenvolvimento de patologias de gravidade variável, como imunológicas, hematológicas e renais. Entre elas, as microangiopatias trombóticas (MAT) representam um grupo de doenças raras com manifestações clínicas comuns caracterizadas por anemia hemolítica não imune, trombocitopenia e lesão de órgão(s) alvo. Embora a classificação das MAT continue sendo desafiadora e não tenha sido padronizada internacionalmente, a descrição de entidades associadas a anomalias do complemento foi comprovada com a eficiência da terapia anticomplemento nos pacientes. As ferramentas de diagnóstico desenvolvidas nas últimas décadas são atualmente essenciais para diferenciar as MAT mais características do grupo, que são a púrpura trombocitopênica trombótica (PTT) e a síndrome hemolítica urêmica atípica (SHU). Neste trabalho, é apresentada uma revisão do funcionamento do sistema de complemento em condições fisiológicas, a fim de explicar posteriormente quais são as alterações do sistema compreendidas no desenvolvimento das MAT, e descrever as ferramentas disponíveis para detectá-las em laboratório.

Microangiopatía trombótica sistémica asociada a mutaciones del complemento en trasplante renal donante vivo. reporte de caso / Systemic thrombotic microangiopathy associated with complement pathway mutations in living donor kidney transplant. case report

RESUMEN El síndrome urémico hemolítico (SUH) se caracteriza por la presencia de anemia hemolítica, plaquetopenia e insuficiencia renal aguda. Si bien se distingue clásicamente en típico o infeccioso y atípico, es menester reconocer situaciones clínicas en las que se pone de manifiesto, como por ejemplo, embarazo, puerperio inmediato, tumores, trasplante, drogas, etc., condiciones clínicas que han sido denominadas amplificadoras del complemento. La recurrencia postrasplante delsíndrome urémico hemolítico atípico (SUHa) ha sido descrita en porcentajes variables en pacientes con mutaciones del factor H, factor B, factor I y C3, y gen de la trombomodulina, en reportes de casos aislados. Se presenta el caso de una paciente con enfermedad renal crónica (ERC) secundaria a agenesia renal, receptora preemptive de un riñón de donante vivo relacionado que presentó disfunción del injerto renal secundaria a microangiopatía trombótica, asociado a complicación neurológica, hemorragias, disfunción orgánica múltiple y óbito. Se describen los hallazgos del estudio genético y anatomopatológico de necropsia.

ABSTRACT Hemolytic uremic syndrome (HUS) is characterized by the presence of hemolytic anemia, thrombocytopenia and acute kidney injury. Although it is usually distinguished as typical or infectious and atypical, it is necessary to recognize clinical situations in which it is revealed, such as pregnancy, immediate postpartum period, tumors, transplantation, drugs, etc., i.e. clinical conditions that have been called complement-amplifying conditions. Post-transplantation recurrence of atypical hemolytic uremic syndrome (aHUS) has been described in variable percentages in patients with mutations of factor H, factor B, factor I and C3, and thrombomodulin gene, in reports of isolated cases. We present the case of a patient with chronic kidney disease (CKD) secondary to renal agenesis, a preemptive recipient of a related living donor kidney, which presented renal graft dysfunction secondary to thrombotic microangiopathy, associated with neurological complications, hemorrhages, multiple organ dysfunction and death. The findings of the genetic and pathological autopsy study are described.

Atypical hemolytic-uremic syndrome (aHUS) / Síndrome hemolítico urémico atípico (SHUa)

Abstract Atypical hemolytic-uremic syndrome (aHUS) is a diagnosis of exclusion which should be proposed in cases where there is microangiopathic hemolytic anemia, thrombocytopenia and acute kidney injury. It is associated with mutations which cause dysregulation of the complement system and implies an adverse prognosis and a high risk of progression to chronic kidney disease. Following, we present the case of a patient with aHUS, highlighting the effect and importance of biologic therapy with the monoclonal antibody eculizumab. (Acta Med Colomb 2019; 44. DOI:https://doi.org/10.36104/amc.2019.1301).

Resumen El síndrome hemolítico urémico atípico (SHUa) constituye un diagnóstico de exclusión que debe plantearse ante la presencia de anemia hemolítica microangiopática, trombocitopenia y lesión renal aguda. Está asociado con mutaciones que provocan una disregulación del sistema del complemento e implica un pronóstico adverso y alto riesgo de progresión a enfermedad renal crónica. A continuación, presentamos el caso de un paciente con SHUa resaltando el efecto e importancia de la terapia biológica con el anticuerpo monoclonal eculizumab. (Acta Med Colomb 2019; 44. DOI:https://doi.org/10.36104/amc.2019.1301).

Atypical Hemolytic Uremic Syndrome in a 13-year-old Lao Girl: A Case Report

Atypical hemolytic uremic syndrome (aHUS), a rare form of thrombotic microangiopathy, is distinguished from the typical form by the absence of a preceding verotoxin-producing Escherichia coli infection. Notably, aHUS occurs in association with genetic or acquired disorders causing dysregulation of the alternative complement pathway. Patients with aHUS may show the presence of anti-complement factor H (CFH) autoantibodies. This acquired form of aHUS (anti-CFH-aHUS) primarily affects children aged 9–13 years. We report a case of a 13-year-old Lao girl with clinical features of aHUS (most likely anti-CFH-aHUS). The initial presentation of the patient met the classical clinical triad of thrombotic microangiopathy (microangiopathic hemolytic anemia, thrombocytopenia, and acute kidney injury) without preceding diarrheal illness. Low serum levels of complement 3 and normal levels of complement 4 indicated abnormal activation of the alternative complement pathway. Plasma infusion and high-dose corticosteroid therapy resulted in improvement of the renal function and hematological profile, although the patient subsequently died of infectious complications. This is the first case report that describes aHUS (possibly anti-CFH-aHUS) in Laos.

Prognostic utility of ADAMTS13 activity for the atypical hemolytic uremic syndrome (aHUS) and comparison of complement serology between aHUS and thrombotic thrombocytopenic purpura

BACKGROUND: Atypical hemolytic uremic syndrome (aHUS) involves dysregulation of the complement system, but whether this also occurs in thrombotic thrombocytopenic purpura (TTP) remains unclear. Although these conditions are difficult to differentiate clinically, TTP can be distinguished by low (<10%) ADAMTS13 activity. The aim was to identify the differences in complement activation products between TTP and aHUS and investigate ADAMTS13 activity as a prognostic factor in aHUS. METHODS: We analyzed patients with thrombotic microangiopathy diagnosed as TTP (N=48) or aHUS (N=50), selected from a Korean registry (N=551). Complement activation products in the plasma samples collected from the patients prior to treatment and in 40 healthy controls were measured by ELISA. RESULTS: The levels of generalized (C3a), alternate (factor Bb), and terminal (C5a and C5b-9) markers were significantly higher (all P<0.01) in the patients than in the healthy controls. Only the factor Bb levels significantly differed (P=0.008) between the two disease groups. In aHUS patients, high normal ADAMTS13 activity (≥77%) was associated with improved treatment response (OR, 6.769; 95% CI, 1.605–28.542; P=0.005), remission (OR, 6.000; 95% CI, 1.693–21.262; P=0.004), exacerbation (OR, 0.242; 95% CI, 0.064–0.916; P=0.031), and disease-associated mortality rates (OR, 0.155; 95% CI, 0.029–0.813; P=0.017). CONCLUSION: These data suggest that complement biomarkers, except factor Bb, are similarly activated in TTP and aHUS patients, and ADAMTS13 activity can predict the treatment response and outcome in aHUS patients.

Síndrome hemolítico urémico atípico / Atypical hemolytic uremic syndrome

Atypical hemolytic uremic syndrome (aHUS) is a rare thrombotic microangiopathy, characterized by microangiopathic hemolytic anemia, thrombocytopenia and renal involvement. It causes end stage renal disease requiring dialysis in most affected patients. It mainly affects young adults (contrary to what was thought years ago). When aHUS is primary, the cause is a genetic mutation in the alternative complement pathway. Instead, secondary aHUS is caused by external factors that trigger the disease by themselves or in combination with a genetic vulnerability. The type of mutation determines the severity of the disease, prognosis, response to therapy and renal transplantation. Advances in the understanding of renal diseases associated with complement defects and the development of specific biologic therapies changed the course of this disease. Eculizumab is internationally approved for the treatment of primary aHUS. Its inhibitory action on the complement cascade leads to hematologic remission and restoration of renal function. We present a review of aHUS detailing its etiology, pathogenesis, clinical presentation, diagnosis and treatment.

Síndrome hemolítico urémico atípico: papel del perfil genético / Atypical hemolytic uremic syndrome: role of the genetic profile

Resumen: El síndrome hemolítico urémico es una microangiopatía trombótica caracterizada por anemia hemolítica microangiopática, trombocitopenia y daño renal agudo. El síndrome hemolítico urémico típico (el más común) es ocasionado por bacterias productoras de la toxina Shiga, típicamente por cepas de Escherichia coli. El término síndrome hemolítico urémico atípico se usa para referirse a los pacientes que padecen este cuadro por causas diferentes. Las manifestaciones clínicas y paraclínicas no son suficientes para diferenciar el síndrome hemolítico urémico atípico de otras microangiopatías trombóticas, por lo que la determinación de la actividad de ADAMTS13 y la prueba de la toxina Shiga resultan esenciales para establecer el diagnóstico preciso. Aunque en la actualidad el diagnóstico definitivo requiere confirmación genética, las pruebas genéticas son costosas y poco útiles para el diagnóstico inicial; sin embargo, más que importancia diagnóstica, tiene gran valor pronóstico, permite prescribir el tratamiento adecuado disminuyendo significativamente la morbilidad y mortalidad atribuibles a esta enfermedad.

Abstract: The haemolytic uraemic syndrome is a thrombotic microangiopathy (TMA) characterized by microangiopathic hemolytic anemia, thrombocytopenia and acute renal injury. The typical haemolytic uraemic syndrome (tHUS, the most common) is caused by bacteria that produce Shiga toxin, typically strains of Escherichia coli. On the other hand, the term atypical haemolytic uraemic syndrome (aHUS) is used to refer to those patients who develop this condition due to different etiologies. The clinical and paraclinical manifestations are not enough to differentiate the aHUS from other thrombotic microangiopathies, so the determination of the activity of ADAMTS13 and the Shiga toxin test are essential to establish the precise diagnosis. Although currently the diagnosis requires genetic confirmation, the genetic tests are expensive and not very useful for the initial diagnosis; however, more than diagnostic importance, it has a great prognostic value allowing establishing an adequate management and significantly reducing the morbidity and mortality attributable to this condition.

Síndrome urémico hemolítico atípico recurrente post-trasplante renal: tratamiento con eculizumab / Recurrent atypical hemolytic uremic syndrome after renal transplantation: treatment with eculizumab

El síndrome urémico hemolítico atípico (SUHa) es una entidad rara que se presenta como una microangiopatía trombótica (anemia hemolítica no inmune, trombocitopenia e insuficiencia renal aguda), cuyas lesiones anatomopatológicas típicas son el engrosamiento de las paredes de capilares y arteriolas con trombosis obstructiva del lumen vascular. Se produce por desregulación de la vía alterna del complemento en la superficie celular, debido a causas genéticas o adquiridas, con una alta tasa de mortalidad, enfermedad renal crónica terminal y recurrencia post-trasplante renal. Las mutaciones de peor pronóstico son las asociadas a factor H, factor B y fracción C3 del complemento. La terapia plasmática resulta útil solo en algunos casos, mientras que el uso de eculizumab es altamente eficaz tanto para el tratamiento agudo como para prevenir las recurrencias en el post-trasplante. Comunicamos el caso de una mujer adulta con diagnóstico de SUHa congénito (mutación de C3) en tratamiento preventivo con eculizumab posterior al trasplante renal, sin recurrencia de la enfermedad, ni efectos adversos relacionados al medicamento a los 36 meses de seguimiento post-trasplante.

Atypical hemolytic uremic syndrome (aHUS) is a rare entity. It is characterized by a thrombotic microangiopathy (nonimmune hemolytic anemia, thrombocytopenia, and acute renal failure), with a typical histopathology of thickening of capillary and arteriolar walls and an obstructive thrombosis of the vascular lumen. The syndrome is produced by a genetic or acquired deregulation of the alternative pathway of the complement system, with high rates of end stage renal disease, post-transplant recurrence, and high mortality. Mutations associated with factor H, factor B and complement C3 show the worst prognosis. Even though plasma therapy is occasionally useful, eculizumab is effective both for treatment and prevention of post-transplant recurrence. We describe here an adult case of congenital aHUS (C3 mutation) under preventive treatment with eculizumab after renal transplantation, with neither disease recurrence nor drug-related adverse events after a 36-months follow-up.

Síndrome hemolítico urémico atípico en tratamiento con eculizumab: casos clínicos / Atypical hemolytic uremic syndrome: report of two cases treated with Eculizumab

Hemolytic uremic syndrome (HUS) is a type of thrombotic microangiopathy where organic damage predominates in the kidney. Atypical HUS (aHUS) is a rare disease that affects young adults and causes terminal chronic renal failure ending in dialysis, in most cases. It also recurs after kidney transplantation. aHUS is associated with genetic defects of the alternative complement pathway or its activation by other factors such as drugs, autoimmune diseases, infections, malignant hypertension and ischemia-reperfusion. We report two women aged 17 and 25 years old with catastrophic aHUS. In both cases, complement amplifying factors (drugs and infections) were added and acted on a genetic vulnerability to precipitate complement activation and produce aHUS. Both patients developed terminal renal failure and had to undergo hemodialysis. Fortunately, after a broad etiological study, it was possible to make the diagnosis of aHUS and start treatment with Eculizumab, a monoclonal antibody that changed the natural history of aHUS. It inhibits complement activity controlling microangiopathy and preventing the development of end-stage renal disease. It also improves the success rate in kidney transplantation. In the case of our patients, both discontinued dialysis after chronic treatment with Eculizumab.

Kidney Transplantation in Patients with Atypical Hemolytic Uremic Syndrome due to Complement Factor H Deficiency: Impact of Liver Transplantation

BACKGROUND: Atypical hemolytic uremic syndrome (aHUS) is a rare disease that is often associated with genetic defects. Mutations of complement factor H (CFH) are the most common genetic defects that cause aHUS and often result in end-stage renal disease. Since CFH is mainly produced in the liver, liver transplantation (LT) has been performed in patients with defective CFH. METHODS: The clinical courses of four kidney allograft recipients who lost their native kidney functions due to aHUS associated with a CFH mutation were reviewed. RESULTS: Subject A underwent kidney transplantation (KT) twice, aHUS recurred and the allograft kidney failed within a few years. Subject B received a KT and soon experienced a recurrence of aHUS coinciding with infection. Her allograft kidney function has worsened, and she remains on plasma infusion therapy. Subject C underwent LT followed by KT. She is doing well without plasma infusion therapy after combined LT-KT for 3 years. Subject D received KT following LT and is now recurrence-free from aHUS. CONCLUSION: In patients with aHUS associated with a CFH mutation, KT without LT was complicated with a recurrence of aHUS, which might lead to allograft loss. Conversely, LT was successful in preventing the recurrence of aHUS and thus might be another option for a recurrence-free life for aHUS patients associated with CFH mutation.

Atypical hemolytic uremic syndrome and eculizumab therapy in children / 소아과

Hemolytic uremic syndrome (HUS) is often encountered in children with acute kidney injury. Besides the well-known shiga toxin-producing Escherichia coli-associated HUS, atypical HUS (aHUS) caused by genetic complement dysregulation has been studied recently. aHUS is a rare, chronic, and devastating disorder that progressively damages systemic organs, resulting in stroke, end-stage renal disease, and death. The traditional treatment for aHUS is mainly plasmapheresis or plasma infusion; however, many children with aHUS will progress to chronic kidney disease despite plasma therapy. Eculizumab is a newly developed biologic that blocks the terminal complement pathway and has been successfully used in the treatment of aHUS. Currently, several guidelines for aHUS, including the Korean guideline, recommend eculizumab as the first-line therapy in children with aHUS. Moreover, life-long eculizumab therapy is generally recommended. Further studies on discontinuation of eculizumab are needed.