HUS and TTP in Children

Primary Thrombotic Microangiopathy in Pediatric Patients

Background. Primary thrombotic microangiopathy includes hemolytic uremic syndrome caused by Shiga toxin-producing Escherichia coli, atypical hemolytic uremic syndrome, and thrombotic thrombocytopenic purpura. Methodology. A retrospective study that included patients younger than 18 years diagnosed with primary thrombotic microangiopathy between 2011 and 2021. Results. Thirty patients were included, of which 63% corresponded to a hemolytic uremic syndrome caused by Shiga toxin-producing Escherichia coli, and 30% to the atypical hemolytic uremic syndrome. The median age was 2.8 years and female sex predominated at 57%. On admission to the emergency room, fever and fatigue were the most frequent symptoms (93%), followed by oliguria and anuria (80%). 48% of patients received hemodialysis during their care. Mortality was estimated at 13%. Conclusion. This study constitutes the largest series of primary thrombotic microangiopathy in the pediatric population of Latin America, where the etiological and clinical behavior of this condition is described.

Eculizumab in the Treatment of Gemcitabine-Induced Atypical Hemolytic Uremic Syndrome

Gemcitabine-induced hemolytic uremic syndrome is an often-missed condition. We present a case outlining the successful management of a patient with metastatic cholangiocarcinoma treated with gemcitabine who subsequently developed hemolytic uremic syndrome. Early recognition and stopping gemcitabine are essential in this patient population. Complement inhibitors have been used, and our patient improved on eculizumab therapy.

Coronavirus Disease 2019-Associated Thrombotic Microangiopathy: Literature Review

Coronavirus disease 2019 (COVID-19) can lead to clinically significant multisystem disorders that also affect the kidney. According to recent data, renal injury in the form of thrombotic microangiopathy (TMA) in native kidneys ranks third in frequency. Our review of global literature revealed 46 cases of TMA in association with COVID-19. Among identified cases, 18 patients presented as thrombotic thrombocytopenic purpura (TTP) and 28 cases presented as atypical hemolytic uremic syndrome (aHUS). Altogether, seven patients with aHUS had previously proven pathogenic or likely pathogenic genetic complement abnormalities. TMA occurred at the time of viremia or even after viral clearance. Infection with COVID-19 resulted in almost no or only mild respiratory symptoms in the majority of patients, while digestive symptoms occurred in almost one-third of patients. Regarding the clinical presentation of COVID-19-associated TMA, the cases showed no major deviations from the known presentation. Patients with TTP were treated with plasma exchange (88.9%) or fresh frozen plasma (11.1%), corticosteroids (88.9%), rituximab (38.9%), and caplacizumab (11.1%). Furthermore, 53.6% of patients with aHUS underwent plasma exchange with or without steroid as initial therapy, and 57.1% of patients received a C5 complement inhibitor. Mortality in the studied cohort was 16.7% for patients with TTP and 10.7% for patients with aHUS. The exact role of COVID-19 in the setting of COVID-19-associated TMA remains unclear. COVID-19 likely represents a second hit of aHUS or TTP that manifests in genetically predisposed individuals. Early identification of the TMA subtype and appropriate prompt and specific treatment could lead to good outcomes comparable to survival and recovery statistics for TMA of all causes.

An ADAMTS13 mutation that causes hereditary thrombotic thrombocytopenic purpura: a case report and literature review

Background

Mutations in the ADAMTS13 gene can lead to an ADAMTS13 enzyme deficiency, which is related to Upshaw–Schulman syndrome (USS). USS is a common type of thrombotic thrombocytopenic purpura (TTP). Here we present a very rare case of TTP caused by 2 mutations in the ADAMTS13 gene. Besides, we reviewed and summarized previous pathogenic ADAMTS13 gene mutations associated with the TTP.

Case presentation

A 10-year-old female was admitted to the Third Xiangya Hospital of Central South University after experiencing discontinuous thrombocytopenia for 8 years, abnormal renal function for more than 2 years, cough for more than 10 days, and weakness of the left limb for 3 days. Gene sequencing shows the patient’s ADAMTS13 gene contains compound heterozygous nucleotide variations: c.1335delC (p. Phe445LeufsTer52) is a frameshift variation inherited from her father and c.2130C > G (p. Cys710Trp) is a missense variation inherited from her mother. The final diagnosis was USS.

Conclusions

Our study reports a very rare genetic TTP case caused by two compound heterozygous variants in the ADAMTS13 gene. The effect of these two mutations on the secretion of ADAMTS13 requires further in vitro experiments to confirm.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12920-021-01099-3.

Pathophysiology of Vaccine-Induced Prothrombotic Immune Thrombocytopenia (VIPIT) and Vaccine-Induced Thrombocytopenic Thrombosis (VITT) and Their Diagnostic Approach in Emergency

SARS-CoV-2 induced a pandemic that is reported to have started in Asia and was then extended to other countries in the world. Main clinical aspects of this viral infection have been lung injuries with severe pneumonia requiring prolonged hospitalization and associated morbidities such as venous thromboembolism and/or superinfection by bacteria, fungus or other pests. Immediately there was a need to develop a sustainable therapeutic strategy, such as vaccination. Vaccines against Covid-19, in fact, exert a protective action for common people and reduce viral diffusion. Yet, vaccination of a large number of people raises the question of a well-known complication of several types of vaccines; this complication is immune thrombocytopenia, which is sometimes associated with thrombosis as well. In this short review, we summarized mechanisms involved in the pathogenesis of vaccine-induced prothrombotic immune thrombocytopenia and vaccine-induced thrombocytopenic thrombosis.

Systemic lupus erythematosus multiorgan flare with quiescent serologic markers

Systemic lupus erythematosus (SLE) can affect almost every organ with differing degrees of severity. Typically, SLE activity is associated with hypocomplimentaemia and elevated double-stranded DNA (dsDNA) levels. We describe a case of a severe multiorgan lupus flare including lupus cerebritis, autoimmune haemolytic anaemia, lupus nephritis and lupus myopericarditis with normal complement and dsDNA levels. This highlights the importance of understanding the heterogeneous nature of SLE flares.

Genomic investigation of inherited thrombotic microangiopathy-aHUS and TTP

Thrombotic microangiopathies (TMA) are a heterogeneous group of red cell fragmentation syndromes characterized by a tendency for thrombosis and pathognomonic red cell fragments in peripheral blood, which results in thrombosis in the microvasculature due to endothelial damage. Genomic investigations into inherited TMAs are of diagnostic, prognostic and therapeutic value. Here, we present two cases that capture the importance of performing genomic testing in rare disorders. Treatment options for these conditions, such as plasma exchange and monoclonal antibodies against complement factors, are intensive and expensive health care interventions. The results of genomic investigation into rare TMAs can better inform the clinicians and their patients of prognosis and suitable personalized treatment options.

Typical and Atypical Hemolytic Uremic Syndrome in the Critically Ill

Hemolytic uremic syndrome is characterized by microangiopathic hemolytic anemia, thrombocytopenia, and acute kidney injury. Disseminated intravascular coagulation, thrombotic thrombocytopenic purpura, and hemolytic uremic syndrome have a similar clinical presentation. Diagnostic needs to be prompt to decrease mortality, because identifying the different disorders can help to tailor specific, effective therapies. However, diagnosis is challenging and morbidity and mortality remain high, especially in the critically ill population. Development of clinical prediction scores and rapid diagnostic tests for hemolytic uremic syndrome based on mechanistic knowledge are needed to facilitate early diagnosis and assign timely specific treatments to patients with hemolytic uremic syndrome variants.

The General Pediatrician's Guide to Isolated Thrombocytopenia

Platelets are an essential component of the hemostatic pathway; therefore, it is important to identify and diagnose patients with low platelet counts. This can be challenging, however, because thrombocytopenia can be relatively common and the differential diagnosis can be broad. Furthermore, because platelets can be affected both in form and function in a variety of medical conditions, platelet abnormalities can be the principal driver in some disorders but only a consequence in others. Critical factors in identifying the etiology of the thrombocytopenia include the severity and acuity of the patient's initial presentation along with the history, physical examination, and laboratory findings, all of which can provide important clues. The accurate diagnosis of thrombocytopenia is crucial for determining the appropriate management. This review highlights the key diagnostic considerations and recommended treatment when isolated thrombocytopenia is encountered in clinical practice. [Pediatr Ann. 2020;49(1):e27-e35.].

Norovirus: a novel etiologic agent in hemolytic uremic syndrome in an infant

Background

Hemolytic uremic syndrome is a rare thrombotic microangiopathy usually seen in infants and children below the age of 5 years. It usually follows a bout of bloody diarrhea caused by Shiga toxin producing E coli and is characterized by microangiopathic hemolytic anemia, thrombocytopenia and acute kidney injury. We report the first case of hemolytic uremic syndrome in an infant following Norovirus gastroenteritis.

Case presentation

A nine-month-old male infant, was admitted with an 8-day history of watery, non-bloody diarrhea, vomiting and decreased oral intake. Physical exam revealed normal blood pressure, pallor and generalized edema. Laboratory findings were significant for microangiopathic hemolytic anemia, thrombocytopenia and azotemia. Stool studies with Multiplex Qualitative reverse transcriptase PCR were positive for Norovirus GI/G II. His clinical course was unusually severe, complicated by oligoanuria and worsening uremia requiring peritoneal dialysis but with eventual complete recovery.

Conclusions

To our knowledge this is the first case of Norovirus associated HUS in an infant. Given the ubiquity of this virus as a major cause of diarrhea, together with the increased availability of Multiplex Qualitative PCR in reference laboratories, it is quite possible that we shall be seeing more such cases in the future.

Acquired thrombotic thrombocytopenia purpura associated with severe ADAMTS13 deficiency in a 3-year-old boy: a case report and review of the literature

Background

Acquired thrombotic thrombocytopenia purpura is very rarely encountered in children. It is often misdiagnosed initially when the condition is not inherited.

Case presentation

We describe a 3-year-old Malay boy who presented with simple febrile seizure and had no neurological deficit, however, he was found to have microangiopathic hemolytic anemia, thrombocytopenia, and elevated serum lactate dehydrogenase. An ADAMTS13 assay results showed zero activities (0%), and markedly high level of ADAMTS13 inhibitor (93.15 U/mL) confirming the diagnosis of secondary thrombotic thrombocytopenia purpura. He received fresh frozen plasma infusions for 3 days and subsequently his platelet levels normalized. Serial ADAMTS13 assay results showed improvement. He was also given a short course of prednisolone after which the ADAMTS13 activity normalized (> 114%) at the end of prednisolone course.

Conclusions

At presentation, acquired thrombotic thrombocytopenia purpura in a very young child is commonly misdiagnosed as other conditions like idiopathic thrombocytopenic purpura, Evans syndrome, atypical hemolytic-uremic syndrome, or malignancy. ADAMTS13 assay should be performed early when thrombotic thrombocytopenia purpura is suspected as this condition is associated with dire consequences.

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

Background

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

Methods

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

Results

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

Conclusions

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

Diarrhea, Urosepsis and Hemolytic Uremic Syndrome Caused by the Same Heteropathogenic Escherichia coli Strain

We describe an 8-month-old girl with diarrhea, urosepsis and hemolytic uremic syndrome caused by Escherichia coli. Typing of cultured E. coli strains from urine and blood revealed the presence of virulence factors from multiple pathotypes of E. coli. This case exemplifies the genome plasticity of E. coli and the resulting heteropathogenic strains.

Thrombocytopenia-associated multiorgan failure occurring in an infant at the onset of type 1 diabetes successfully treated with fresh frozen plasma

TAMOF is a devastating microangiopathy that can occur in association with the new onset of T1DM, and should be considered with the onset of thrombocytopenia, renal failure, and raised LDH. Treatment with fresh frozen plasma should be considered as a first‐line option in such cases prior to plasma exchange.

Enterohaemorrhagic E. coli modulates an ARF6:Rab35 signaling axis to prevent recycling endosome maturation during infection

Enteropathogenic and enterohaemorrhagic Escherichia coli (EPEC/EHEC) manipulate a plethora of host cell processes to establish infection of the gut mucosa. This manipulation is achieved via the injection of bacterial effector proteins into host cells using a Type III secretion system. We have previously reported that the conserved EHEC and EPEC effector EspG disrupts recycling endosome function, reducing cell surface levels of host receptors through accumulation of recycling cargo within the host cell. Here we report that EspG interacts specifically with the small GTPases ARF6 and Rab35 during infection. These interactions target EspG to endosomes and prevent Rab35-mediated recycling of cargo to the host cell surface. Furthermore, we show that EspG has no effect on Rab35-mediated uncoating of newly formed endosomes, and instead leads to the formation of enlarged EspG/TfR/Rab11 positive, EEA1/Clathrin negative stalled recycling structures. Thus, this paper provides a molecular framework to explain how EspG disrupts recycling whilst also reporting the first known simultaneous targeting of ARF6 and Rab35 by a bacterial pathogen.

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EHEC delivers effector proteins into host cells to establish infection in the gut

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The effector EspG interacts with GTP-ARF6 confining EspG to recycling endosomes

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During infection EspG interacts preferentially with Rab35, not Rab1

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Spatial restriction of bacterial effectors during infection determines their function

CFH gene mutation in a case of Shiga toxin-associated hemolytic uremic syndrome (STEC-HUS)

BACKGROUND

We report the case of a patient with Shiga toxin (Stx)-associated hemolytic-uremic syndrome (HUS) (STEC-HUS) with a concomitant heterozygous mutation of the gene coding for complement Factor H (CFH).

CASE DIAGNOSIS/TREATMENT

An 18-month-old patient presented with hemolytic anemia and thrombotic microangiopathy in the context of acute gastroenteritis. While the patient did not show kidney or other organ failure, he had persistent hemolysis and complement 3 activation (low C3), leading to the decision to commence immunotherapy with eculizumab (Soliris®) together with transient antibiotic coverage and meningococcal vaccination. Patient outcome was favorable. Diagnostic work-up identified Escherichia coli-associated Type 2 Shiga toxin. Complement analysis showed a heterozygous mutation of the CFH gene (c.2103 G>A, p. Trp701X) resulting in a quantitative CFH defect.

CONCLUSIONS

We report a case of STEC-HUS with a quantitative CFH defect caused by a mutation of the CFH gene. To the best of our knowledge, very few cases of STEC-HUS with complement gene mutation have been reported, but none to date with a CFH mutation. We therefore suggest that complement analyses be performed in patients diagnosed with STEC-HUS in association with low C3 levels, especially in patients presenting with severe or unexpected clinical symptoms.

Hemolytic uremic syndrome: toxins, vessels, and inflammation

Hemolytic uremic syndrome (HUS) is characterized by thrombotic microangiopathy of the glomerular microcirculation and other vascular beds. Its defining clinical phenotype is acute kidney injury (AKI), microangiopathic anemia, and thrombocytopenia. There are many etiologies of HUS including infection by Shiga toxin-producing bacterial strains, medications, viral infections, malignancy, and mutations of genes coding for proteins involved in the alternative pathway of complement. In the aggregate, although HUS is a rare disease, it is one of the most common causes of AKI in previously healthy children and accounts for a sizable number of pediatric and adult patients who progress to end stage kidney disease. There has been great progress over the past 20 years in understanding the pathophysiology of HUS and its related disorders. There has been intense focus on vascular injury in HUS as the major mechanism of disease and target for effective therapies for this acute illness. In all forms of HUS, there is evidence of both systemic and intra-glomerular inflammation and perturbations in the immune system. Renewed investigation into these aspects of HUS may prove helpful in developing new interventions that can attenuate glomerular and tubular injury and improve clinical outcomes in patients with HUS.