Hemolytic uremic syndrome: new developments in pathogenesis and treatment

Antimicrobial Effects of Plant-Based Supplements on Gut Microbial Diversity in Small Ruminants

Every year in the United States, approximately 48 million people are affected by bacterial illnesses that are transmitted through food, leading to 3000 fatalities. These illnesses typically stem from food animals and their by-products, which may harbor dangerous pathogens like Salmonella enterica, Listeria monocytogenes, enterohemorrhagic Escherichia coli O157:H7, and Campylobacter jejuni. Factors that contribute to contamination include manure used as a soil amendment, exposure to polluted irrigation water, and contact with animals. To improve food safety, researchers are studying pre-slaughter intervention methods to eliminate bacterial contamination in live animals. While small ruminants are vital to global agriculture and income generation for small farms, traditional feeding practices involve supplements and antibiotics to boost performance, which contributes to antibiotic resistance. Hence, researchers are looking for friendly bacterial strains that enhance both animal and human health without impacting livestock productivity. The global trend is to minimize the use of antibiotics as feed supplements, with many countries prohibiting or limiting their use. The aim of this review is to provide a comprehensive insight on the antioxidant capabilities, therapeutic attributes, and applications of bioactive compounds derived from sweet potato tops (SPTs), rice bran (RB) and radish tops (RTs). This overview provides an insight on plant parts that are abundant in antioxidant and prebiotic effects and could be used as value-added products in animal feed and pharmaceutical applications. This review was based on previous findings that supplementation of basal diets with natural supplements represents a multifaceted intervention that will become highly important over time. By remarkably reducing the burden of foodborne pathogens, they apply to multiple species, are cheap, do not require withdrawal periods, and can be applied at any time in food animal production.

Cerebral microstructural changes in children suffering from hemolytic uremic syndrome

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

Genomic Characterization of Fecal Escherichia coli Isolates with Reduced Susceptibility to Beta-Lactam Antimicrobials from Wild Hogs and Coyotes

This study was carried out to determine the antimicrobial resistance (AMR) genes and mobile genetic elements of 16 Escherichia coli isolates-with reduced susceptibility to ceftazidime and imipenem-that were recovered from the fecal samples of coyotes and wild hogs from West Texas, USA. Whole-genome sequencing data analyses revealed distinct isolates with a unique sequence type and serotype designation. Among 16 isolates, 4 isolates were multidrug resistant, and 5 isolates harbored at least 1 beta-lactamase gene (bla_CMY-2, bla_CTX-M-55, or bla_CTX-M-27) that confers resistance to beta-lactam antimicrobials. Several isolates carried genes conferring resistance to tetracyclines (tet(A), tet(B), and tet(C)), aminoglycosides (aac(3)-IId, ant(3″)-Ia, aph(3')-Ia, aph(3″)-lb, aadA5, and aph(6)-ld), sulfonamides (sul1, sul2, and sul3), amphenicol (floR), trimethoprim (dfrA1 and dfrA17), and macrolide, lincosamide, and streptogramin B (MLSB) agents (Inu(F), erm(B), and mph(A)). Nine isolates showed chromosomal mutations in the promoter region G of ampC beta-lactamase gene, while three isolates showed mutations in gyrA, parC, and parE quinolone resistance-determining regions, which confer resistance to quinolones. We also detected seven incompatibility plasmid groups, with incF being the most common. Different types of virulence genes were detected, including those that enhance bacterial fitness and pathogenicity. One bla_CMY-2 positive isolate (O8:H28) from a wild hog was also a Shiga toxin-producing E. coli and was a carrier of the stx2A virulence toxin subtype. We report the detection of bla_CMY-2, bla_CTX-M-55, and bla_CTX-M-27 beta-lactamase genes in E. coli from coyotes for the first time. This study demonstrates the importance of wildlife as reservoirs of important multi-drug-resistant bacteria and provides information for future comparative genomic analysis with the limited literature on antimicrobial resistance dynamics in wildlife such as coyotes.

Enteric Escherichia coli O157:H7 in Cattle, and the Use of Mice as a Model to Elucidate Key Aspects of the Host-Pathogen-Microbiota Interaction: A Review

Enterohemorrhagic Escherichia coli (EHEC) serotype O157:H7 is responsible for foodborne disease outbreaks, typically associated with the consumption of undercooked foods contaminated with cattle manure containing the bacterium. At present, effective mitigations do not exist. Many of the factors regulating enteric colonization by E. coli O157:H7 in cattle, and how cattle respond to the bacterium are unknown. In this regard, intestinal colonization locations, shedding patterns, interactions with the enteric microbiota, and host immune responses to infection are current knowledge gaps. As disturbances to host homeostasis are believed to play an important role in the enteric survival of the bacterium, it is important to consider the potential importance of stress during cattle production. Husbandry logistics, cost, and the high genetic, physiological, and microbial heterogeneity in cattle has greatly hampered the ability of researchers to elucidate key aspects of the host-pathogen-microbiota interaction. Although mice have not been extensively used as a cattle model, the utilization of murine models has the potential to identify mechanisms to facilitate hypothesis formulation and efficacy testing in cattle. Murine models have been effectively used to mechanistically examine colonization of the intestine, host responses to infection, and to interactively ascertain how host physiological status (e.g., due to physiological stress) and the enteric microbiota influences colonization and disease. In addition to reviewing the relevant literature on intestinal colonization and pathogenesis, including existing knowledge gaps, the review provides information on how murine models can be used to elucidate mechanisms toward the development of rationale-based mitigations for E. coli O157:H7 in cattle.

Rapid Detection of Pathogenic Bacteria by the Naked Eye

Escherichia coli O157:H7 and Staphylococcus aureus are common pathogens. Gram-negative bacteria, such as E. coli, contain high concentrations of endogenous peroxidases, whereas Gram-positive bacteria, such as S. aureus, possess abundant endogenous catalases. Colorless 3,5,3',5'-tetramethyl benzidine (TMB) changes to blue oxidized TMB in the presence of E. coli and a low concentration of H2O2 (e.g., ~11 mM) at pH of 3. Moreover, visible air bubbles containing oxygen are generated after S. aureus reacts with H2O2 at a high concentration (e.g., 180 mM) at pH of 3. A novel method for rapidly detecting the presence of bacteria on the surfaces of samples, on the basis of these two endogenous enzymatic reactions, was explored. Briefly, a cotton swab was used for collecting bacteria from the surfaces of samples, such as tomatoes and door handles, then two-step endogenous enzymatic reactions were carried out. In the first step, a cotton swab containing bacteria was immersed in a reagent comprising H2O2 (11.2 mM) and TMB for 25 min. In the second step, the swab was dipped further in H2O2 (180 mM) at pH 3 for 5 min. Results showed that the presence of Gram-negative bacteria, such as E. coli with a cell number of ≥ ~105, and Gram-positive bacteria, such as S. aureus with a cell number of ≥ ~106, can be visually confirmed according to the appearance of the blue color in the swab and the formation of air bubbles in the reagent solution, respectively, within ~30 min. To improve visual sensitivity, we dipped the swab carrying the bacteria in a vial containing a growth broth, incubated it for ~4 h, and carried out the two-stage reaction steps. Results showed that bluish swabs resulting from the presence of E. coli O157: H7 with initial cell numbers of ≥ ~34 were obtained, whereas air bubbles were visible in the samples containing S. aureus with initial cell numbers of ≥ ~8.5 × 103.

Atypical haemolytic uraemic syndrome: a case of rare genetic mutation

Complement-mediated kidney disease has been an evolving area in the field of nephrology. Atypical haemolytic uraemic syndrome (aHUS) is a rare thrombotic microangiopathy that affects multiple organs, particularly kidneys. The disease is characterised by a triad of haemolytic anaemia, thrombocytopenia and acute kidney injury (AKI). aHUS is most commonly caused by dysregulation of alternative complement pathway. In contrast to shiga toxin-associated haemolytic uraemic syndrome, diarrheal prodrome is usually absent in children with aHUS. We report a 2-year, 9-month-old boy who presented with acute dysentery and AKI. He had an unusual prolonged course of illness with hypocomplementaemia; hence, genetic testing was performed. He had a storming course in the hospital and succumbed to complications of the disease. Genetic study revealed digenic mutation in Complement Factor I and C3 Therefore, it is important to differentiate aHUS from other thrombotic microangiopathies to improve the outcome.

Verotoxin-1-Induced ER Stress Triggers Apoptotic or Survival Pathways in Burkitt Lymphoma Cells

Shiga toxins (Stxs) expressed by the enterohaemorrhagic Escherichia coli and enteric Shigella dysenteriae 1 pathogens are protein synthesis inhibitors. Stxs have been shown to induce apoptosis via the activation of extrinsic and intrinsic pathways in many cell types (epithelial, endothelial, and B cells) but the link between the protein synthesis inhibition and caspase activation is still unclear. Endoplasmic reticulum (ER) stress induced by the inhibition of protein synthesis may be this missing link. Here, we show that the treatment of Burkitt lymphoma (BL) cells with verotoxin-1 (VT-1 or Stx1) consistently induced the ER stress response by activation of IRE1 and ATF6-two ER stress sensors-followed by increased expression of the transcription factor C/REB homologous protein (CHOP). However, our data suggest that, although ER stress is systematically induced by VT-1 in BL cells, its role in cell death appears to be cell specific and can be the opposite: ER stress may enhance VT-1-induced apoptosis through CHOP or play a protective role through ER-phagy, depending on the cell line. Several engineered Stxs are currently under investigation as potential anti-cancer agents. Our results suggest that a better understanding of the signaling pathways induced by Stxs is needed before using them in the clinic.

Hemolytic Uremic Syndrome Associated With Escherichia coli O157 Infection in an Allogenic Stem Cell Transplant Recipient

We report the development of a Shiga toxin-producing Escherichia coli O157 gastrointestinal infection associated with hemolytic uremic syndrome in an allogenic stem cell transplant recipient with a history of gastrointestinal graft-vs-host disease receiving long-term immunosuppression.

Postdiarrheal hemolytic and uremic syndrome with severe multiorgan involvement and associated early risk factors

AIM

Identifying early clinical and biological factors associated with severe forms of postdiarrheal hemolytic uremic syndrome (D+HUS) that may help practitioners determine appropriate treatment.

METHODS

This retrospective study was conducted in 49 children with D+HUS between 2001 and 2011. Severe forms were defined as occurrence of one of the following conditions: death, major neurological involvement, cardiovascular involvement, and/or the presence of sequelae (neurological, cardiovascular, pancreatic, or renal).

RESULTS

During the acute phase, 35 children exhibited at least one type of extrarenal involvement including 13 severe forms with a median delayed occurrence after admission of 4.5 days (range: 1-8) for comatose children and 5 days (range: 2-6) for cardiovascular involvement; 32 children required dialysis and three died. In multivariate analysis, (i) major neurological involvement (n=13), (ii) dialysis (n=32), and (iii) sequelae (n=12) were associated with (i) fever during the prodromal phase requiring dialysis at admission, (ii) C-reactive protein level (CRP) >22mg/L at admission, and (iii) major neurological involvement and a white blood cell count (WBC)>20×10³/mm³ during the acute stage, respectively.

CONCLUSIONS

D+HUS is a multiorgan disease with a delayed occurrence of life-threatening extrarenal organ involvement. Severe forms appear to be associated with early biological and clinical inflammatory parameters.

Short- and Long-Term Renal Outcome of Hemolytic-Uremic Syndrome in Childhood

Introduction: Hemolytic-uremic syndrome (HUS) is a common cause for intrarenal acute kidney injury in childhood. More than 90% of HUS cases are associated with an infection by Shigatoxin-producing Escherichia coli (STEC) whereas the reminder comprises a heterogeneous group (here classified as Non-STEC-HUS). Renal impairment can persist in patients with HUS. This study presents data from four decades investigating the short- and long-term outcome of HUS in childhood. Materials and Methods: In a retrospective single-center-study clinical and laboratory data of the acute phase and of 1- to 10-year follow-up visits of children with HUS were analyzed. Results: 92 HUS-patients were identified from 1996 to 2014 (STEC-HUS-group: n = 76; Non-STEC-HUS-group: n = 16) and 220 HUS-patients between 1976 and 1995. STEC-HUS was increasingly caused by Non-O157 strains and mortality rate declined over the past decades (1.3 vs. 9.5%). Renal sequelae persisted more often in the group 1976-1995 (39.3%) than in the group 1996-2014 (28.3%), but more than 50% of all patients were lost to follow-up. Conclusion: Although renal outcome has improved over the investigated last decades, patients with HUS still face a high risk of permanent renal damage. These findings underline the importance of a consequent long-term follow-up in HUS-patients.

Syndromes of Thrombotic Microangiopathy

Thrombotic thrombocytopenia purpura (TTP) and the hemolytic uremic syndrome (HUS) are rare thrombotic microangiopathies that can be rapidly fatal. Although the acquired versions of TTP and HUS are generally highest on this broad differential, multiple rarer entities can produce a clinical picture similar to TTP/HUS, including microangiopathic hemolysis, renal failure, and neurologic compromise. More recent analysis has discovered a host of genetic factors that can produce microangiopathic hemolytic syndromes. This article discusses the current understanding of thrombotic microangiopathy and outlines the pathophysiology and causative agents associated with each distinct syndrome as well as the most accepted treatments.

Early erythropoietin in post-diarrheal hemolytic uremic syndrome: a case-control study

BACKGROUND

Although erythropoietin (EPO) deficiency has been reported in children with post-diarrheal hemolytic uremic syndrome (D + HUS), very limited clinical data on EPO use in this disease are currently available. In this case-control study we examined whether EPO administration would reduce the number of red blood cell (RBC) transfusions in D + HUS patients under our care.

METHODS

Data from children treated exclusively with RBC transfusions (controls; n = 21) were retrospectively compared with data on those who also received EPO for the treatment of anemia (cases; n = 21).

RESULTS

Both patient groups were similar in age (p = 0.9), gender (p = 0.12), weight (p = 1.00) and height (p = 0.66). Acute phase severity was also comparable, as inferred by the need for dialysis (p = 0.74), the duration of dialysis (p = 0.3), length of hospitalization (p = 0.81), presence of severe bowel (p = 1.00) or neurological injury (p = 0.69), arterial hypertension (p = 1.00) and death (p = 1.00). No differences in the hemoglobin level at admission (p = 0.51) and discharge (p = 0.28) were noted. Three children treated with EPO and two controls did not require any RBC transfusion (p = 1.00). Median number of RBC transfusions needed by cases and controls was 2 (p = 0.52).

CONCLUSION

Treatment with EPO did not reduce the number of RBC transfusions in D + HUS children. Assessment of EPO efficacy in D + HUS merits further studies.

Consequences of hemolytic uremic syndrome among hemodialysis patients

Background

Hemolytic uremic syndrome (HUS) is characterized by hemolytic anemia, low platelets, and renal impairment and is mediated by thrombotic microangiopathy (TMA). A common perception is that HUS becomes dormant in dialysis patients with end-stage renal disease (ESRD). We analyzed patients in a large dialysis organization to understand the potential consequences and burden of HUS.

Methods

We identified patients with ESRD ascribed to HUS and those with ESRD ascribed to another cause (control patients) who received hemodialysis or peritoneal dialysis from 01 January 2007 to 31 December 2012. Outcomes were survival, hospitalization, and longitudinal laboratory values associated with TMA, including lactate dehydrogenase, red cell distribution width (RDW), platelets, and hemoglobin.

Results

HUS patients (n = 217) were propensity-score matched 1:5 to control patients (n = 1,085) for age, gender, race, dry weight, insurance, access, comorbidities, and Charlson comorbidity index. Compared to control patients, HUS patients had significantly greater risk for hospitalizations overall (RR = 2.3, p = 0.004) and hospitalization for hematologic (RR = 5.6, p = 0.001), cardiovascular (RR = 2.1, p = 0.02), and pancreatic (RR = 7.9, p = 0.04) causes. HUS patients also had evidence of ongoing TMA: higher lactate dehydrogenase and RDW, lower platelets and hemoglobin, and more frequent lactate dehydrogenase spikes.

Conclusions

Dialysis patients with HUS were at significantly higher risk than matched control patients for hospitalizations due to cardiovascular, hematologic, and pancreatic disease, which were associated with ongoing TMA. Additional studies are needed to determine whether targeted therapy for HUS reduces hospitalizations.

High frequency of acquired ADAMTS13 deficiency after hemolysis in Hemiscorpius Lepturus (scorpion) stung children

OBJECTIVE

To estimate the frequency of acquired ADAMTS13 deficiency in severe cases of Hemiscorpius lepturus stung patients and the frequency of acute kidney injury (AKI) in these patients.

METHODS

Sixty scorpion stung children who were referred with severe hemolysis and hemoglobinuria were studied. None of them had received blood products and no one had a past medical history of renal failure.

RESULTS

Plasma levels of ADAMTS13 and ADAMTS13 antibody (IgG) were measured using ELISA. ADAMTS13 was decreased in 91.7 % of patients and the anti-ADAMTS13 antibody (Ab) was increased in 98.3 %. ADAMTS13 decreased in all of the patients with acute kidney injury and none of those with normal levels of ADAMTS13 developed renal failure; all patients with AKI had also increased levels of ADAMTS13Ab. Acute kidney injury was found in 23.3 % and had significant association with severe anemia, thrombocytopenia, pyuria, hematuria and considerable proteinuria (p < 0.001). Disseminated intravascular coagulation (DIC) and Hemolytic uremic syndrome (HUS) developed in 6.7 % and 10 % respectively.

CONCLUSIONS

The index findings demonstrate that Hemiscorpius lepturus sting is usually associated with ADAMTS13 deficiency, and increased ADAMTS13 autoantibody. These combined mechanisms may contribute to scorpion sting-induced coagulopathies and may predispose patients to develop DIC and HUS.

Plasma Exchange in Haemolytic-Uraemic Syndrome Secondary to E. Coli

A 12-year-old previously healthy girl presented with seizures, bloody diarrhoea and abdominal pain. A diagnosis of haemolytic-uraemic syndrome was made on the basis of the presence of haemolysis, thrombocytopenia and acute renal failure. This case report reviews clinical aspects of the syndrome. Plasma exchange has been used to treat cerebral symptoms in these patients and the dilemma surrounding its use is presented.

Prevalence in the General Population of a CFH Sequence Variant Associated with Atypical Haemolytic Uraemic Syndrome in an Extensive Family from Southwest England

BACKGROUND/AIMS

Twenty-five members of a family from the county of Devon in England have been affected by atypical haemolytic uraemic syndrome (aHUS) associated with a CFH mutation (c.3643C>G; p.Arg1215Gly). A 65-year-old male was diagnosed with aHUS after losing a renal transplant to a thrombotic microangiopathy. Subsequent mutation screening revealed the same CFH mutation without him being knowingly related to the local kindred. We designed a study to investigate the prevalence of this mutation in the local area. In addition, we examined the diagnoses of pre-existing haemodialysis patients to determine whether other patients might unknowingly be at risk of carrying the same CFH mutation.

METHODS

The Exeter Ten Thousand (EXTEND) study aims to recruit 10,000 healthy volunteers over the age of 18 years living within 25 miles of Exeter in Devon. We genotyped DNA from 4,000 EXTEND subjects for CFH c.3643C>G; p.Arg1215Gly. We reviewed the diagnoses of 294 haemodialysis patients in the Devon area and genotyped 7 patients with either end-stage renal disease of unknown aetiology, malignant hypertension or renovascular disease.

RESULTS

CFH c.3643C>G; p.Arg1215Gly was not detected in any of the 7 haemodialysis patients or the 4,000 individuals within the EXTEND study.

CONCLUSIONS

We conclude that CFH c.3643C>G; p.Arg1215Gly is not endemic in Devon. This reinforces our existing practice of genotyping only patients with kidney disease and evidence of a thrombotic microangiopathy for this mutation. This is the first study looking at the prevalence of CFH mutations in the general population.

Brain magnetic resonance imaging pattern and outcome in children with haemolytic-uraemic syndrome and neurological impairment treated with eculizumab

AIM

The aim of this study was to describe the magnetic resonance imaging (MRI) findings and the neurological and neuropsychological outcomes in paediatric, diarrhoea-associated haemolytic-uraemic syndrome (D+HUS) with central nervous system impairment treated with eculizumab, a monoclonal antibody.

METHOD

The 14-month single-centre prospective study included seven children (three males, four females; age range 16 mo-7 y 8 mo; median age 3 y 7 mo) with typical D+HUS and acute neurological impairment. In the acute phase of the disease, neurological assessment and brain magnetic resonance imaging (MRI), including measurement of the apparent diffusion coefficient (ADC), were performed, and neuropsychological evaluation and brain MRI were also carried out 6 months after disease onset.

RESULTS

In the acute phase, basal ganglia and white matter abnormalities with ADC restriction were a common and reversible MRI finding. In all the surviving patients (5/7), follow-up MRI after 6 months was normal, indicating reversible lesions. Clinical and neuropsychological evaluations after 6 months were also normal.

INTERPRETATION

This specific brain MRI pattern consisting of an ADC decrease in basal ganglia and white matter without major T2/fluid-attenuated inversion recovery (FLAIR) injury may be a key finding in the acute phase of the disease in favour of a vasculitis hypothesis. These reversible lesions were associated with a good neurological outcome. These results call for further evaluation of the potential role of eculizumab in the choice of treatment for severe D+HUS, particularly in the case of early neurological signs.

Ouabain protects against Shiga toxin-triggered apoptosis by reversing the imbalance between Bax and Bcl-xL

Hemolytic uremic syndrome, a life-threatening disease often accompanied by acute renal failure, usually occurs after gastrointestinal infection with Shiga toxin 2 (Stx2)-producing Escherichia coli. Stx2 binds to the glycosphingolipid globotriaosylceramide receptor, expressed by renal epithelial cells, and triggers apoptosis by activating the apoptotic factor Bax. Signaling via the ouabain/Na,K-ATPase/IP3R/NF-κB pathway increases expression of Bcl-xL, an inhibitor of Bax, suggesting that ouabain might protect renal cells from Stx2-triggered apoptosis. Here, exposing rat proximal tubular cells to Stx2 in vitro resulted in massive apoptosis, upregulation of the apoptotic factor Bax, increased cleaved caspase-3, and downregulation of the survival factor Bcl-xL; co-incubation with ouabain prevented all of these effects. Ouabain activated the NF-κB antiapoptotic subunit p65, and the inhibition of p65 DNA binding abolished the antiapoptotic effect of ouabain in Stx2-exposed tubular cells. Furthermore, in vivo, administration of ouabain reversed the imbalance between Bax and Bcl-xL in Stx2-treated mice. Taken together, these results suggest that ouabain can protect the kidney from the apoptotic effects of Stx2.

Shiga toxin 2 reduces complement inhibitor CD59 expression on human renal tubular epithelial and glomerular endothelial cells

Infections with enterohemorrhagic Escherichia coli (EHEC) are a primary cause of hemolytic-uremic syndrome (HUS). Recently, Shiga toxin 2 (Stx2), the major virulence factor of EHEC, was reported to interact with complement, implying that the latter is involved in the pathogenesis of EHEC-induced HUS. The aim of the present study was to investigate the effect of Stx2 on the expression of membrane-bound complement regulators CD46, CD55, and CD59 on proximal tubular epithelial (HK-2) and glomerular endothelial (GEnC) cells derived from human kidney cells that are involved in HUS. Incubation with Stx2 did not influence the amount of CD46 or CD55 on the surface of HK-2 and GEnC cells, as determined by fluorescence-activated cell sorter analysis. In contrast, CD59 was significantly reduced by half on GEnC cells, but the reduction on HK-2 cells was less pronounced. With increasing amounts of Stx2, reduction of CD59 also reached significance in HK-2 cells. Enzyme-linked immunosorbent assay analyses showed that CD59 was not present in the supernatant of Stx2-treated cells, implying that CD59 reduction was not caused by cleavage from the cell surface. In fact, reverse transcription-quantitative PCR analyses showed downregulation of CD59 mRNA as the likely reason for CD59 cell surface reduction. In addition, a significant increase in terminal complement complex deposition on HK-2 cells was observed after treatment with Stx2, as a possible consequence of CD59 downregulation. In summary, Stx2 downregulates CD59 mRNA and protein levels on tubular epithelial and glomerular endothelial cells, and this downregulation likely contributes to complement activation and kidney destruction in EHEC-associated HUS.

[Escherichia coli associated hemolytic and uremic syndrome: what lessons can be learned after the European epidemic of 2011?]

Hemolytic and uremic syndrome (HUS) is the most feared complication of infections with enterohemorrhagic Escherichia coli. During summer 2011, Europe was the scene of a large outbreak of shiga-toxin producing E. coli gastroenteritis, occasioning more than 800 cases of HUS, highlighting this public health problem. Last years, many advances have occurred, on the physiopathology, microbiology or therapeutics. We review here these different aspects, from molecular identification of the German bacteria, to the use of targeted therapies as eculizumab in severe forms, or even the major role of complement activation in the physiopathology of HUS.

Eculizumab therapy in a child with hemolytic uremic syndrome and CFI mutation

BACKGROUND

Hemolytic uremic syndrome (HUS) is the most common cause of acute renal failure in childhood. It usually occurs after a prodromal episode of diarrhea and it leads to significant morbidity and mortality during the acute phase. However, cases that start as diarrhea-positive HUS whose renal function fail to recover should be screened for genetic disorders of the complement system, which is called atypical HUS (aHUS).

CASE-DIAGNOSIS/TREATMENT

We herein report a 10-year-old girl, who initially came with bloody diarrhea and had features of HUS with delayed renal and hematological recovery despite plasma therapy. Eculizumab (600 mg/week) was initiated on day 15 for atypical presentation and later a complement factor I (CFI) mutation was detected. The girl recovered diuresis within 24 h and after the third eculizumab infusion, hemoglobin, platelet, and C3 levels normalized; renal function improved; and proteinuria completely disappeared in 2 weeks.

CONCLUSION

It is our belief that eculizumab can be the treatment of choice in children who have plasma exchange-refractory HUS with defective regulation of the alternative complement pathway.

Shiga toxin-associated hemolytic uremic syndrome: advances in pathogenesis and therapeutics

PURPOSE OF REVIEW

Diarrhea-associated hemolytic uremic syndrome (HUS) caused by Shiga toxin-producing Escherichia coli (STEC) continues to be an important public health threat worldwide. Specific therapies are lacking and patient care remains largely supportive. This review discusses the lessons learned from recent events and summarizes key advances made toward understanding the basic mechanisms involved in the pathogenesis of typical HUS.

RECENT FINDINGS

The recent German outbreak of a hybrid organism resulted in an unprecedented number of HUS cases and drastically changed the face of typical (diarrhea-associated) HUS. New findings on the roles of complement and the CXCR4/SDF-1 pathway in HUS pathogenesis are summarized and novel therapeutic strategies are highlighted.

SUMMARY

A better understanding of STEC-mediated HUS underlies improved therapeutic approaches. New studies of the mechanistic basis of the disease, together with patient-based studies, have led to key findings with important clinical implications.

Emergency management of hypertension in children

Systemic arterial hypertension in children has traditionally been thought to be secondary in origin. Increased incidence of risk factors like obesity, sedentary life-styles, and faulty dietary habits has led to increased prevalence of the primary arterial hypertension (PAH), particularly in adolescent age children. PAH has become a global epidemic worldwide imposing huge economic constraint on health care. Sudden acute increase in systolic and diastolic blood pressure can lead to hypertensive crisis. While it generally pertains to secondary hypertension, occurrence of hypertensive crisis in PAH is however rare in children. Hypertensive crisis has been further subclassified depending on presence or absence of end-organ damage into hypertensive emergency or urgency. Both hypertensive emergencies and urgencies are known to cause significant morbidity and mortality. Increasing awareness among the physicians, targeted at investigation of the pathophysiology of hypertension and its complications, better screening methods, generation, and implementation of novel treatment modalities will impact overall outcomes. In this paper, we discuss the etiology, pathogenesis, and management of hypertensive crisis in children. An extensive database search using keywords was done to obtain the information.