Hemolytic Uremic Syndrome Research Articles

Typical! Atypical Hemolytic Uremic Syndrome (aHUS) Overlooked in Malignant Hypertension and Thrombotic Microangiopathy: Case Reports and Clinical Implications

Typical! Atypical Hemolytic Uremic Syndrome (aHUS) Overlooked in Malignant Hypertension and Thrombotic Microangiopathy: Case Reports and Clinical Implications

Successful Use of Eculizumab for Prevention of Atypical Hemolytic Uremic Syndrome Recurrence in a Pregnant Kidney Transplant Recipient with CFH Gene Mutation: A Case Report and Literature Review

Successful Use of Eculizumab for Prevention of Atypical Hemolytic Uremic Syndrome Recurrence in a Pregnant Kidney Transplant Recipient with CFH Gene Mutation: A Case Report and Literature Review

Thrombotic Microangiopathy in the Postpartum Period (Literature Review, Clinical Case Report)

Introduction. Thrombotic microangiopathy (TMA) is a heterogeneous group of diseases that, in the presence of endothelial damage, can lead to microvascular thrombosis, secondary platelet consumption, mechanical hemolysis and ischemic end-organs damage. Such triad of symptoms as acute kidney injury (AKI), microangiopathic hemolysis and thrombocytopenia may also accompany some pregnancy-specific conditions (severe preeclampsia/HELLP syndrome (hemolysis, elevated liver enzymes, and low platelet count), acute fatty liver disease of pregnancy (AFLP), and conditions not related to pregnancy, but triggered by it (catastrophic antiphospholipid syndrome (CAPS), lupus flare. The aim of the study. To review the current literature devoted to the problem of thrombotic microangiopathy, to demonstrate on a clinical case a step-by-step differentiated approach to the diagnosis of the type of thrombotic microangiopathy causing acute kidney injury in the postpartum period, and to describe modern methods of treatment of these diseases. Results. The classical types of TMA are thrombotic thrombocytopenic purpura (TTP) and typical hemolytic uremic syndrome (HUS), also known as enterohemorrhagic Shiga toxin-producing Escherichia coli (STEC)-associated HUS (STEC-HUS). Pathophysiologically, all forms of TMA involve complement-mediated endothelial cell damage, which mainly affects the capillary zone of the kidney. Pregnancy can trigger atypical HUS (aHUS) or TTP. The article describes the clinical case of a 37-year-old woman who developed AKI following a complicated delivery. A turn-based differential diagnosis of aHUS was performed. Unwarranted discontinuation of the targeted therapy with Eculisumab led to the development of chronic renal failure Conclusions. Thrombotics microangiopathy are the life-threatening conditions rarely seen in pregnancy making its early recognition difficult. As thrombotics microangiopathy require urgent treatment, plasmapheresis should be started as soon as they are suspected, followed by targeted therapy (Eculisumab, Rituximab) after the confirmation of the diagnosis. This may contribute to reducing maternal morbidity and mortality rates.

Shiga toxin-producing Escherichia coli infection as a precipitating factor for atypical hemolytic-uremic syndrome.

Hemolytic uremic syndrome (HUS) is a thrombotic microangiopathy characterized by intravascular hemolysis. It can be classified as either typical, primarily caused by Shiga toxin-producing Escherichia coli (STEC) infection, or as atypical HUS (aHUS), which results from uncontrolled complement activation. We report the case of a 9-year-old boy with aHUS due to compound heterozygous complement factor H-related genes (CFHR) 1/3 and CFHR1-CFHR4 deletions, leading to the development of anti-complement factor H (CFH) autoantibodies. The patient presented nephrological and neurological thrombotic microangiopathy with STEC positivity. Additionally, we provide an extensive literature review of aHUS cases initially classified as typical. A total of 11 patients were included, 73% of whom were pediatric. Kidney replacement therapy was required in 73% of patients. The recurrence rate was 55%. All cases were found positive for pathological variants of the complement system genes. The most commonly implicated gene was CFH, while the CFHR genes were involved in 36% of cases, although none exhibited anti-CFH autoantibodies. Anti-complement therapy was administered in 54% of cases, and none of the patients who received it early progressed to kidney failure. STEC infection does not exclude aHUS diagnosis, and early use of anti-complement therapy might be reasonable in life-threatening conditions. Genetic testing can be helpful in patients with atypical presentations and can confirm the necessity of prolonged anti-complement therapy.

Meningococcal Carriage in Children with Atypical Hemolytic Uremic Syndrome Receiving Eculizumab Therapy.

Eculizumab is a first-line treatment for atypical hemolytic uremic syndrome (aHUS), and patients undergoing eculizumab therapy may become more susceptible to infection caused by Neisseria meningitidis (Nm). While meningococcal vaccination is required for patients undergoing eculizumab therapy, there is limited knowledge about meningococcal carriage in children with aHUS. We aimed to evaluate (1) the prevalence of Nm carriage, (2) serogroup distribution, and (3) the immunization status of children undergoing eculizumab treatment for aHUS. The Meningo-aHUS study is a prospective, multi-center study evaluating meningococcal carriage in children and adolescents in Türkiye receiving eculizumab for aHUS. We noted the age, gender, daycare, school, or university attendance, passive smoking status, previous infection and antibiotic use, and previous immunization history, including meningococcal vaccines, from the medical records of those children with aHUS. We collected nasopharyngeal samples, tested them for Nm using real-time polymerase chain reaction, and performed a serogroup analysis on the positive samples. We collected nasopharyngeal samples from 62 children with aHUS. Out of 62 children, 61 (98.4%) had received at least one dose of the meningococcal vaccine. The median time since the last meningococcal vaccine dose was 15 months (1-59 months). We detected meningococcal carriage in three (4.8%, 95% CI 1.0-13.5) children, and all three strains were non-groupable (NG). No other serogroups were detected. Almost all the children received their risk-group meningococcal immunization, including booster doses. A 4.8% of children with aHUS carried NG meningococci and, no vaccine serogroups were detected. Patients treated with eculizumab remain profoundly susceptible to IMD due to these NG meningococcal strains. The occurrence of breakthrough cases and carriage of Nm, especially NG strains, highlights the significance of maintaining a state of constant alertness, promptly seeking medical attention, and swiftly treating any symptoms that align with IMD, regardless of their vaccination status or antibiotic prophylaxis.

Hypogammaglobulinemia in a child with atypical hemolytic-uremic syndrome

We present a unique clinical case of an atypical hemolytic-uremic syndrome in a child. The mutation in exon 6 of the CD46 gene (chr1:207940532G>C) leads to a homozygous or hemizygous missense substitution. An 8-year-old girl was urgently hospitalized with symptoms of hemorrhagic syndrome and acute kidney injury. The child from the second pregnancy with an aggravated obstetric anamnesis, the first operative labor at the 38th week, who has an aggravated genealogical anamnesis. Initially, the disease developed in the guise of gastroenterological pathology: the girl had dyspeptic disorders, most likely associated with pathology of carbohydrate metabolism, also frequent infectious diseases and a lag in physical development. From the age of 4 years, the girl suffered from persistent hypoalbuminemia, hypoproteinemia and hypogammaglobulinemia, requiring replacement therapy with intravenous immunoglobulins. She was repeatedly examined in gastroenterological departments in Yekaterinburg and Moscow in 2021-2023, but no data concerning protein-losing enteropathies or primary immunodeficiency was obtained. Also, the whole-exome sequencing with result validation hasn’t confirmed an inherited etiology of the presumed congenital immune error. However, a CD46 gene mutation, associated with the development of hemolytic-uremic syndrome in some publications, was identified in the study. The signs of thrombotic microangiopathy were preceded by fever of unspecified etiology: microangiopathic hemolysis, thrombocytopenia, hyperazotemia, C3 consumption, proteinuria, and macrohematuria; hypercholesterolemia, protein metabolism disorder, increased transaminases, ferritin were also noted. According to the ultrasound of the kidneys there were diffuse changes in the parenchyma, decreased velocity indices of blood flow in both renal arteries at all levels. Differential diagnosis was carried out with thrombotic thrombocytopenic purpura, autoimmune hemolytic anemia, antinuclear form of atypical hemolytic-uremic syndrome, viral and bacterial infections, systemic pathology, antiphospholipid syndrome, and hemoblastosis. The girl didn’t need a renal replacement therapy. When complement-blocking therapy with eculizumab was initiated on vital indications, the signs of the disease were gradually eliminated. The prolonged absence of nephropathy in the child may indicate the diversity of the CD46 gene’s functions and different phenotypic manifestation of its mutations. Analysis of literature sources and detection of CD46 “environment” genes (CYBA, LYST, ARPCIB) by full-exome sequencing suggest ambiguity and polymorphism of phenotypic manifestations of complement-mediated mutation.

The Role of the N-Terminal Domain of Thrombomodulin and the Potential of Recombinant Human Thrombomodulin as a Therapeutic Intervention for Shiga Toxin-Induced Hemolytic-Uremic Syndrome.

Hemolytic-uremic syndrome (HUS) is a rare complication of an infection with Shiga toxin (Stx)-producing Escherichia coli (STEC-HUS), characterized by severe acute kidney injury, thrombocytopenia and microangiopathic hemolytic anemia, and specific therapy is still lacking. Thrombomodulin (TM) is a multi-domain transmembrane endothelial cell protein and its N-terminal domain has been implicated in the pathophysiology of some cases of HUS. Indeed, the administration of recombinant human TM (rhTM) may have efficacy in HUS. We used a Stx-based murine model of HUS to characterize the role of the N-terminal domain of TM. We show that mice lacking that domain (TMLed (-/-)) are more sensitive to Stx, with enhanced HUS progression seen at 4 days and increased mortality at 7 days post-HUS induction. In spite of these changes, renal function was less affected in surviving Stx-challenged TMLed (-/-) mice compared to their wild-type counterparts TMLed (+/+) at 7 days. Contrary to few clinical case reports from Japan, the administration of rhTM (0.06 mg/kg) to wild-type mice (C57BL/6J) with HUS did not protect against disease progression. This overall promising, but also contradictory body of evidence, requires further systematic preclinical and clinical investigations to clarify the role of TM in HUS as a potential therapeutic strategy.

Streptococcus pneumoniae-associated hemolytic uremic syndrome Canadian Immunization Monitoring Program ACTive National Pediatric Surveillance (1991 to 2019)

Streptococcus pneumoniae-associated hemolytic uremic syndrome Canadian Immunization Monitoring Program ACTive National Pediatric Surveillance (1991 to 2019)

Atypical haemolytic uremic syndrome

Atypical haemolytic uremic syndrome

Haemolytic-uremic syndrome associated with infection

Haemolytic-uremic syndrome associated with infection

Severe Invasive Pneumococcal Disease Caused by Serotype 19A in Children Under Five Years in Tāmaki Makaurau Auckland, Aotearoa New Zealand.

Increases in childhood invasive pneumococcal disease (IPD) have been reported in several countries following the easing of COVID-19 pandemic mitigations. In Aotearoa New Zealand (AoNZ), a surge in IPD is occurring in young children concurrent with changes in pneumococcal vaccines and declining immunization coverage. We sought to examine epidemiologic and clinical features of IPD among children under 5 years in a large urban region of AoNZ in the 3 years post-COVID-19. Demographic, clinical and laboratory data were collated from children under 5 years with Streptococcus pneumoniae identified from normally sterile sites between January 1, 2021, and December 31, 2023, in Tāmaki Makaurau Auckland, AoNZ. We identified 93 episodes of IPD (annual incidence of 18-40 cases per 100,000 population per year). Serotype was identified in 68 episodes and 46 (68%) were serotype 19A. Incidence was higher in Pacific children compared with non-Māori, non-Pacific children (incidence rate ratio: 2.3; 95% confidence interval: 1.4-3.7). Bacteremia occurred in 65 (70%) episodes, empyema in 47 (51%), meningitis in 11 (12%) and hemolytic uremic syndrome in 7 (7.5%). All cases of hemolytic uremic syndrome and empyema were only among children with serotype 19A. Two children died, both had serotype 19A, and 13/91 survivors (14%) experienced serious sequelae. The use of the pneumococcal conjugate vaccine with lower valency and easing of COVID-19 containment measures each may have contributed to an increase in IPD in AoNZ. Serotype 19A is associated with empyema and causes severe disease in young children. Urgent efforts are required to improve PCV13 coverage in AoNZ.

Continued Anticomplement Therapy: A Lifeline for Post-Renal-Transplant Patients with Complement-Mediated Hemolytic Uremic Syndrome

Continued Anticomplement Therapy: A Lifeline for Post-Renal-Transplant Patients with Complement-Mediated Hemolytic Uremic Syndrome

Exocrine pancreatic insufficiency in a child with STEC-HUS: a forgotten complication.

Exocrine pancreatic insufficiency (EPI) is an extremely rare complication of hemolytic uremic syndrome related to Shiga toxin-producing Escherichia coli (STEC-HUS) and, to our knowledge, only one patient has been reported to have received pancreatic enzyme replacement therapy (PERT). Furthermore, STEC-HUS is not usually included among EPI causes. We report a 4-year-old girl with STEC-HUS who required dialysis and 4days after admission developed acute pancreatitis (ACPAN) and diabetes mellitus (DM). Amylase and lipase normalized 15days later but on the 73rd day of admission, she presented abdominal discomfort, bloating, and bulky and malodorous stools with a low fecal elastase-1 level (FE-1) of 15.74µg/g confirming EPI diagnosis. She received 3months of PERT until normalization of FE-1 levels. In children with STEC-HUS with ACPAN or DM, a high index of suspicion for EPI is required, since its symptoms are often mild, nonspecific, or delayed. In addition, STEC-HUS should be further recognized as a cause of secondary EPI.

Genetic Diversity and Zoonotic Potential of Shiga Toxin-Producing E. coli (STEC) in Cattle and Buffaloes from Islamabad, Pakistan

Shiga toxin-producing E. coli (STEC) are considered important zoonotic pathogens of great economic significance, associated with diarrhea, hemolytic uremic syndrome (HUS), hemorrhagic colitis (HC), and death in humans. This study aimed to investigate the distribution of various STEC virulence gene markers and antimicrobial susceptibility (AST) profiles associated within E. coli isolates from the recto-anal mucosal swabs (RAMSs) of slaughtered cattle and buffaloes in Islamabad, Pakistan. The RAMSs (n = 200) were analyzed using multiplex PCR for the presence of stx1, stx2, eae, and ehxA genes. Samples that were positive for one or more of the virulence genes were inoculated with Sorbitol MacConkey agar (SMAC) for isolation of STEC. The isolates were further analyzed for the presence of virulence genes using multiplex PCR. Of the 200 RAMS, 118 (59%) were positive for one or more virulence genes. E. coli isolates (n = 18) with one or more virulence genes were recovered from the 118 positive samples. The DNA of the isolates positive for one or more virulent genes was extracted and subjected to whole genome sequencing using Illumina. Analysis of the WGS data indicated that the E. coli isolates could be differentiated into 11 serotypes. Most E. coli isolates (13/18; 72.2%) carried five genes (stx1, stx2, Iha, iss, and IpfA) in various combinations. In addition to these five genes, other virulence genes identified in these isolates were espI, ireA, espP, exhA, epeA, mcmA, mch, ast, celB, eilA, katP, and capU. The AST was performed using the Kirby–Bauer disk diffusion test. The study indicated that all the isolates were resistant to rifampicin and a significant proportion of the isolates were MDR. A wide range of antimicrobial resistance genes (ARGs) were detected among the isolates, reflecting the complex nature of resistance mechanisms. The study results indicate that cattle and buffaloes slaughtered in Islamabad might be the carriers of antimicrobial resistant STEC of zoonotic significance, thus representing a source of human infection.

In situ deposition of nanobodies by an engineered commensal microbe promotes survival in a mouse model of enterohemorrhagic E. coli.

Engineered smart microbes that deliver therapeutic payloads are emerging as treatment modalities, particularly for diseases with links to the gastrointestinal tract. Enterohemorrhagic Escherichia coli (EHEC) is a causative agent of potentially lethal hemolytic uremic syndrome. Given concerns that antibiotic treatment increases EHEC production of Shiga toxin (Stx), which is responsible for systemic disease, novel remedies are needed. EHEC encodes a type III secretion system (T3SS) that injects Tir into enterocytes. Tir inserts into the host cell membrane, exposing an extracellular domain that subsequently binds intimin, one of its outer membrane proteins, triggering the formation of attaching and effacing (A/E) lesions that promote EHEC mucosal colonization. Citrobacter rodentium (Cr), a natural A/E mouse pathogen, similarly requires Tir and intimin for its pathogenesis. Mice infected with Cr(ΦStx2dact), a variant lysogenized with an EHEC-derived phage that produces Stx2dact, develop intestinal A/E lesions and toxin-dependent disease. Stx2a is more closely associated with human disease. By developing an efficient approach to seamlessly modify the C. rodentium genome, we generated Cr_Tir-MEHEC(ΦStx2a), a variant that expresses Stx2a and the EHEC extracellular Tir domain. We found that mouse precolonization with HS-PROT3EcT-TD4, a human commensal E. coli strain (E. coli HS) engineered to efficiently secrete an anti-EHEC Tir nanobody, delayed bacterial colonization and improved survival after challenge with Cr_Tir-MEHEC(ΦStx2a). This study suggests that commensal E. coli engineered to deliver payloads that block essential virulence determinants can be developed as a new means to prevent and potentially treat infections including those due to antibiotic resistant microbes.

An expert discussion on the atypical hemolytic uremic syndrome nomenclature—identifying a road map to precision: a report of a National Kidney Foundation Working Group

The term atypical hemolytic uremic syndrome has been in use since the mid-1970s. It was initially used to describe the familial or sporadic form of hemolytic uremic syndrome as opposed to the epidemic, typical form of the disease. Over time, the atypical hemolytic uremic syndrome term has evolved into being used to refer to anything that is not Shiga toxin-associated hemolytic uremic syndrome. The term describes a heterogeneous group of diseases of disparate causes, a circumstance that makes defining disease-specific natural history and/or targeted treatment approaches challenging. A working group of specialty-specific experts in the thrombotic microangiopathies was convened to review the validity of this broad term in an era of swiftly advancing science and targeted therapeutics. A Delphi approach was used to define and interrogate some of the key issues related to the atypical hemolytic uremic syndrome nomenclature.

Severe complicated malaria caused by Plasmodium falciparum in a female traveler returning from Zanzibar

A 25-year-old female outpatient presenting with fever and micro-hematuria was treated for urinary tract infection. Her condition worsened over 3 days at home. After experiencing multiple falls caused by leg weakness and mental confusion, she was admitted to a hospital with high fever. Initial laboratory findings showed hemolytic anemia, pancytopenia, and acute kidney injury, suggesting hemolytic uremic syndrome. However, a detailed fever evaluation revealed her recent return from Afrika. This prompted amalaria test, which confirmed Plasmodium falciparum infection with 80 % parasitemia. Despite the quick reduction of parasitemia following treatment with intravenous administered artesunate and oral Artemether-Lumefantrine, her condition worsened, leading to a septic shock. This required renal replacement and kinetic ventilation therapy, as well as blood transfusions due to persistent hemolysis until the laboratory values normalized after 48 days post-admission. The evaluation of fever is often challenging, but most often a detailed patient history is key to early diagnosis and treatment preventing deathly outcomes in severe cases.

The utility of the normal thin section skin biopsy in the assessment of systemic/extracutaneous disease and small fiber neuropathy

Diseases reflective of multiorgan vascular injury of diverse etiology, peripheral nerve disease, dysautonomia syndromes, and intravascular lymphoma may exhibit abnormalities on a normal skin biopsy that may be instrumental in establishing a diagnosis. A retrospective review of our database was conducted to uncover cases where a normal skin biopsy was performed to rule in or out such systemic diseases as complement-driven thrombotic microvascular disease (including atypical hemolytic uremic syndrome, posttransplant thrombotic microangiopathy, and severe or critical COVID-19), systemic capillary leak syndrome, cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL) intravascular B cell lymphoma, small fiber neuropathy, dysautonomia syndromes, and mast cell activation syndrome. Among the special studies were immunohistochemical staining to detect C5b-9, CD56, and myxovirus resistance protein A, as well as mast cell, B and T cell markers. Characteristic patterns were critical in establishing diagnoses such as : increased C5b-9 microvascular deposition in the deltoid area (atypical hemolytic uremic syndrome, posttransplant thrombotic microangiopathy, catastrophic antiphospholipid antibody syndrome, and severe or critical COVID-19); enhanced type I interferon signaling (systemic capillary leak syndrome); ultrastructural arteriopathic changes (CADASIL); reduced cutaneous autonomic innervation in the lower extremities (small fiber neuropathy and postural orthostatic tachycardia syndrome); presence of intravascular lymphocytes on biopsy of abdominal, thigh, and buttock skin (intravascular B cell lymphoma); and a higher than normal density of mast cells in the absence of other inflammatory cell types (mast cell activation syndrome). The skin is clearly a critical window for understanding extracutaneous disease, a concept well exemplified by the myriad of diseases suggested by the microscopic and/or ultrastructural examination of clinically normal skin and therefore establishing the normal skin biopsy as an important tool for understanding certain extracutaneous reactive, neoplastic and paraneoplastic syndromes as well as small fiber neuropathy.

Eculizumab as Salvage Treatment for Thrombotic Microangiopathy After Lung Transplantation.

Thrombotic microangiopathy (TMA) is a rare complication after lung transplantation (LT) that has seldom been characterized in detail. Recent evidence has linked TMA other than primary atypical hemolytic uremic syndrome (aHUS) with hyperactivation of the complement alternative pathway. The focus of this investigation was to analyze the treatment response with eculizumab in TMA after LT. Case series where we have studied 11 patients with TMA after LT from 2 Spanish tertiary healthcare centers. Clinical data and response rates to eculizumab are provided. The main indication for lung transplant was chronic obstructive pulmonary disease (COPD) (36%) and most cases (82%) received bilateral LT. The median time to TMA diagnosis was 11.6 months (4.7-28.9) and the TMA trigger in the majority of cases (73%) was immunosuppressive drugs. Platelet and hemoglobin nadir were 58×103/µL (24-108) and 7.7g/dL (7.1-7.9), respectively. All cases presented acute kidney injury (AKI) with a median creatinine of 4mg/dL (3.2-4.8) and 54.5% required acute dialysis. Eculizumab was started after a median time of 8 days (6-14) with a median duration of 3 weeks (2-8). Complete TMA response was observed in 7 (63.6%) cases and hematologic response in 10 (90.9%). The time to hematologic and renal response was 23 days (13-29) and 28 days (14-46), respectively. TMA after LT is infrequent but potentially devastating. Our findings suggest that short cycles of eculizumab may be effective for severe TMA after LT.

Immunodeficiency: Complement disorders.

The complement system is an important component of innate and adaptive immunity that consists of three activation pathways. The classic complement pathway plays a role in humoral immunity, whereas the alternative and lectin pathways augment the innate response. Impairment, deficiency, or overactivation of any of the known 50 complement proteins may lead to increased susceptibility to infection with encapsulated organisms, autoimmunity, hereditary angioedema, or thrombosis, depending on the affected protein. Classic pathway defects result from deficiencies of complement proteins C1q, C1r, C1s, C2, and C4, and typically manifest with features of systemic lupus erythematosus and infections with encapsulated organisms. Alternative pathway defects due to deficiencies of factor B, factor D, and properdin may present with increased susceptibility to Neisseria infections. Lectin pathway defects, including Mannose-binding protein-associated serine protease 2 (MASP2) and ficolin 3, may be asymptomatic or lead to pyogenic infections and autoimmunity. Complement protein C3 is common to all pathways, deficiency of which predisposes patients to severe frequent infections and glomerulonephritis. Deficiencies in factor H and factor I, which regulate the alternative pathway, may lead to hemolytic uremic syndrome. Disseminated Neisseria infections result from terminal pathway defects (i.e., C5, C6, C7, C8, and C9). Diagnosis of complement deficiencies involves screening with functional assays (i.e., total complement activity [CH50], alternative complement pathway activity [AH50], enzyme-linked immunosorbent assay [ELISA]) followed by measurement of individual complement factors by immunoassay. Management of complement deficiencies requires a comprehensive and individualized approach with special attention to vaccination against encapsulated bacteria, consideration of prophylactic antibiotics, treatment of comorbid autoimmunity, and close surveillance.