Plasma therapy for atypical haemolytic uraemic syndrome associated with heterozygous factor H mutations

Retrospective evaluation of therapeutic plasma exchange treatment in a pediatric intensive care unit: Single-center experience

BACKGROUND

The aim of this study is to characterize the clinical indications, outcomes, and complications of therapeutic plasma exchange (TPE) in pediatric intensive care unit.

METHODS

A retrospective study was conducted on critically ill patients who received TPE. A dataset of 672 treatments administered to 102 patients was analyzed.

RESULTS

The most common indication for TPE was COVID-19-related clinical conditions, followed by sepsis (24.5%), neurological diseases (9.8%) and renal diseases (6.9%). None of our patients died due to TPE-related complications, and the most common complication during and after the TPE was hypotension (21.7%).

CONCLUSION

Although TPE is riskier to provide to critically ill children, our experience indicates that it can be performed relatively safely in critically ill children with appropriate treatment indications. In particular, indications, onset time, number of sessions and other procedures should be standardized for the pediatric age group.

Successful treatment with eculizumab in a patient with pregnancy-associated atypical hemolytic uremic syndrome

Pregnancy-associated atypical haemolytic uraemic syndrome is a rare and potentially lethal complement-mediated disorder. It can mimic preeclampsia, gestational hypertension, thrombotic thrombocytopenic purpura and hemolysis, elevated liver enzymes and low platelets syndrome. Thus, it can be hard to distinguish pregnancy-associated atypical haemolytic uraemic syndrome from other causes in peri/post-partum women presenting with features of microangiopathic haemolytic anemia, thrombocytopenia and acute kidney injury. We present a case of a 35-year-old woman in her third pregnancy at 32 weeks' gestation who underwent caesarean section due to fetal distress. She developed severe renal impairment, thrombocytopenia and neurologic symptoms within 24 hours after delivery. A diagnosis of pregnancy-associated atypical haemolytic uraemic syndrome was provided, and treatment with plasma therapy followed by eculizumab was initiated. A rapid improvement of both clinical and laboratory parameters was observed. This case demonstrates the significance of early initiation of anti-complement therapy to prevent irreversible renal damage and possible death in women with pregnancy-associated atypical haemolytic uraemic syndrome.

Therapeutic plasma exchange in the pediatric intensive care unit: A single-center 5-Year experience

The objective of this study is to characterize clinical indications, safety and outcome with the use of TPE in critically ill children. All TPE procedures performed in a tertiary pediatric intensive care unit (PICU) during a 5-year period were retrospectively evaluated. A total of 75 patients underwent 249 sessions of TPE. Sepsis-induced multiple organ dysfunction syndrome (MODS) was the most common indication with 29.3 %. American Society for Apheresis classifications were as follows: Category I: 24 %, Category II: 16 %, Category III: 45.3 % and Category IV: 4%, while 10.7 % of the patients could not be classified. TPE was performed without any adjunct procedures in 188 sessions (75.5 %), while it was combined with continuous renal replacement therapy (CRRT) in 49 sessions (19.7 %) and with CRRT and extracorporeal membrane oxygenation (ECMO) in 12 (4.8 %) sessions. Overall survival rate was 73.3 %. The survival rate in patients requiring only TPE was 86.5 %, while the survival rates of patients who had CRRT and ECMO were 45 % and 33.3 %, respectively. Complications associated with the procedure occurred in 48 (19.2 %) TPE sessions. The lowest survival rate (31.9 %) was in patients with sepsis-induced MODS. Finally, we also found significantly higher organ failure rate, mechanical ventilation requirement, and PRISM III score at PICU admission in non-survivors. Our experience indicates that TPE can be performed relatively safely in critically ill children with appropriate treatment indications. Survival rate may vary depending on the underlying disease; however, it must be noted that survival rate is very high in children requiring TPE only.

Therapeutic plasma exchange in pediatric intensive care: Indications, results and complications

Therapeutic plasma exchange (TPE) is an effective treatment method in selective indications. Secondary to access and technical features, it is more difficult to apply in pediatric population than adults. The aim of this study is investigate safety, clinical indications, and results of this method in critically ill pediatric patients who need TPE treatment. All of the TPE procedures performed in a pediatric intensive care unit providing tertiary care during 4 years (2015-2019) were evaluated retrospectively. TPE procedures (635) were performed for 135 patients. Median age was 34 months (10-108). Ninety-seven patients had mechanical ventilation support. Sepsis with multiple organ failure was the most frequent indication and accounted for 44.4% (n = 60) of the indications followed by hematological and neurological diseases (19.2% and 9.6% respectively). TPE was performed alone in 469 cases (73.9%), in combination with continuous renal replacement therapy in 154 cases (24.2%), and additional to extracorporeal membrane oxygenation in 12 cases (1.9%). Hematological disease and sepsis subgroups had the highest intubation rate, mechanical ventilation period, PRISM score, organ failure count, and mortality. Fresh frozen plasma (FFP) was the most frequently used replacement fluid in 90.4% of the procedures. The most frequent anticoagulant used in TPE was acid citrate dextrose solution (79.3%). Procedural complications were detected in 104 cases (16.3%) and occurred during TPE sessions. Overall survival rate was 78.5%. We found that the non-survivor group had significantly higher rates of organ failures (P = 0.0001), higher PRISM scores on admission (P = 0.0001), and higher rates of invasive ventilation support needed (P = 0.012). TPE is a treatment method which can be safely provided in healthcare facilities with necessary medical and technical requirements. Although it is riskier to provide such treatment to critically ill children, complications can be minimized in experienced healthcare facilities. Overall results are good and can vary depending on indication.

A case of thrombotic microangiopathy of unknown aetiology, clinically presenting as an acute surgical abdomen

A 48-year-old woman presented with severe abdominal pain, bilious vomiting and bloody diarrhoea for 1 day. On examination, she was haemodynamically unstable, febrile and clinically had an acute surgical abdomen. She had markedly raised inflammatory markers, neutrophils and deranged renal function. A CT abdominal scan revealed severe colitis and thickening throughout the length of the colon. The patient was stabilised and underwent emergency laparotomy resulting in total colectomy and end ileostomy formation. Postoperatively, she required several units of human albumin solution, red blood cell transfusions and octaplex (prothrombin complex) to prevent further bleeding. An inpatient haematology review revealed a hypocomplementaemia (C3/C4), low immunoglobulin (IgG, IgM, IgA) and peripheral blood films revealed schistocytosis indicating microangiopathic haemolytic anaemia. Bowel histology supported this, demonstrating circumferential lymphocytic phlebitis with thrombi and mucosal haemorrhage, necrosis and ulceration. The patient went on to suffer multiple ischaemic strokes before undergoing plasmapheresis, subsequent rehabilitation and making a successful recovery.

The role of plasma exchange in the management of autoimmune disorders

Therapeutic plasma exchange (TPE) has been mainly used in the treatment of autoimmune diseases. The main mechanisms of action of TPE include the removal of circulating autoantibodies, immune complexes, complement components, cytokines and adhesion molecules, along with sensitization of antibody-producing cells to immunosuppressant agents. TPE is useful in autoimmune haematological, renal, rheumatic and neurological diseases, and is recommended for acute disorders, together with relapsed or worsened chronic diseases that are often unresponsive to conventional treatments. The American Society for Apheresis and the British Society of Haematology have published guidelines on the clinical use of apheresis procedures, indicating the different levels of efficacy of TPE. Based on the evidence from current literature and our personal experience, this review discusses the indications and the suggested regimens for TPE in autoimmune haematological and non-haematological disorders.

Therapeutic Plasma Exchange in Pediatric Renal Transplantation Experience of One Decade and 389 Sessions

OBJECTIVE

There are no specific recommendations for therapeutic plasma exchange (TPE) in children after renal transplantation. The purpose of this study was to report the experience with TPE in a pediatric transplant setting.

MATERIALS AND METHODS

59 patients (mean age 12.5 ± 4.5 years) undergoing renal transplantation. Indications for TPE included the recurrence of nephrotic syndrome (NS; n = 30) and atypical hemolytic uremic syndrome (n = 6), chronic antibody-mediated rejection (cAMR; n = 20), sensitization (n = 2), and immune thrombocytopenia (n = 1). The single-filtration TPE was performed in all cases. In 74.7% of patients, fresh frozen plasma was used as a replacement fluid. In 25.3% of patients, 4% albumin solution was used as a replacement fluid. Criteria for TPE efficacy included a decrease of proteinuria and normalization of renal function in NS; a normalization of platelet count, C3, and hemoglobin concentration in aHUS; improvement in renal function; and reduction of donor-specific antibodies in cAMR; and removal of antiplatelet antibodies in immune thrombocytopenia.

RESULTS

Efficacy results for patients with NS: 59.3% achieved remission, 25.9% achieved partial remission, and 14.8% achieved no remission, respectively. For patients with atypical hemolytic uremic syndrome there was remission in 66.6% and no remission in 33.4%. For patients with cAMR there was remission in 75% and no remission in 25%. Antiplatelet antibodies disappeared after TPE in 1 patient. In 9% of TPE procedures, minor complications were noted. All patients were on posttransplant maintenance immunosuppression and several children received additional treatment (intravenous immunoglobulin therapy or rituximab) during TPE therapy.

CONCLUSION

TPE therapy (combined with immunosuppression) was an effective tool in most pediatric cases after renal transplantation with low incidence of minor adverse events.

Treatment of thrombotic microangiopathy with a focus on new treatment options

The thrombotic microangiopathies (TMA) are a heterogeneous group of disorders, characterized by microangiopathic haemolytic anaemia with red cell fragmentation, thrombocytopenia and signs of organ dysfunction due to disturbed microcirculation. Current laboratory methods can be used to better distinguish some of these entities. Organ dysfunction can be severe and life-threatening, and immediate start of sufficient therapy is necessary to avoid permanent damage or death. The therapeutic options, however, are often limited to symptomatic measures, and are not standardized or based on high scientific evidence. During the preceding years, not only considerable progress has been made in better diagnosis of TMA, but also new therapeutic strategies have been established. Initial treatment still is based on plasma exchange and symptomatic measures to protect organ function. New concepts (immunosuppression, targeted anti-von Willebrand factor or anti-complement therapy, replacement with recombinant enzymes) are discussed in this article.

Pathophysiology of Pediatric Multiple Organ Dysfunction Syndrome

OBJECTIVE

To describe the pathophysiology associated with multiple organ dysfunction syndrome in children.

DATA SOURCES

Literature review, research data, and expert opinion.

STUDY SELECTION

Not applicable.

DATA EXTRACTION

Moderated by an experienced expert from the field, pathophysiologic processes associated with multiple organ dysfunction syndrome in children were described, discussed, and debated with a focus on identifying knowledge gaps and research priorities.

DATA SYNTHESIS

Summary of presentations and discussion supported and supplemented by relevant literature.

CONCLUSIONS

Experiment modeling suggests that persistent macrophage activation may be a pathophysiologic basis for multiple organ dysfunction syndrome. Children with multiple organ dysfunction syndrome have 1) reduced cytochrome P450 metabolism inversely proportional to inflammation; 2) increased circulating damage-associated molecular pattern molecules from injured tissues; 3) increased circulating pathogen-associated molecular pattern molecules from infection or endogenous microbiome; and 4) cytokine-driven epithelial, endothelial, mitochondrial, and immune cell dysfunction. Cytochrome P450s metabolize endogenous compounds and xenobiotics, many of which ameliorate inflammation, whereas damage-associated molecular pattern molecules and pathogen-associated molecular pattern molecules alone and together amplify the cytokine production leading to the inflammatory multiple organ dysfunction syndrome response. Genetic and environmental factors can impede inflammation resolution in children with a spectrum of multiple organ dysfunction syndrome pathobiology phenotypes. Thrombocytopenia-associated multiple organ dysfunction syndrome patients have extensive endothelial activation and thrombotic microangiopathy with associated oligogenic deficiencies in inhibitory complement and a disintegrin and metalloproteinase with a thrombospondin type 1 motif, member 13. Sequential multiple organ dysfunction syndrome patients have soluble Fas ligand-Fas-mediated hepatic failure with associated oligogenic deficiencies in perforin and granzyme signaling. Immunoparalysis-associated multiple organ dysfunction syndrome patients have impaired ability to resolve infection and have associated environmental causes of lymphocyte apoptosis. These inflammation phenotypes can lead to macrophage activation syndrome. Resolution of multiple organ dysfunction syndrome requires elimination of the source of inflammation. Full recovery of organ functions is noted 6-18 weeks later when epithelial, endothelial, mitochondrial, and immune cell regeneration and reprogramming is completed.

Current evidence for the role of complement in the pathogenesis of Shiga toxin haemolytic uraemic syndrome

Shiga toxin-associated haemolytic uraemic syndrome (Stx HUS) is the leading cause of paediatric acute kidney injury. This toxin-mediated disease carries a significant morbidity and mortality but has no direct treatments. Rare familial atypical HUS (aHUS) is now understood to result from over-activation of the alternative complement pathway causing glomerular endothelial damage. By understanding the pathogenic mechanisms of this disease, the monoclonal antibody eculizumab, which blocks the final common pathway of complement, is now being used to treat aHUS. For this reason, clinicians and scientists are studying the role of the alternative complement pathway in Stx HUS with the aim of targeting treatment in a similar way. There is some evidence suggesting that complement plays a role in the pathogenesis of Stx HUS, but other mechanisms may also be important. Clinically, modulating the complement system using plasma exchange provides no proven benefit in Stx HUS, and the use of eculizumab has provided conflicting results. Understanding the local effect of Stx on the glomerulus, in particular regulation of the complement and coagulation systems, may lead to advances in defining the precise pathogenesis of this disease. Then, targeted treatment strategies could be devised and clinical trials undertaken.

Current treatment of atypical hemolytic uremic syndrome

Tremendous advances have been made in understanding the pathogenesis of atypical Hemolytic Uremic Syndrome (aHUS), an extremely rare disease. Insights into the molecular biology of aHUS resulted in rapid advances in treatment with eculizumab (Soliris(®), Alexion Pharmaceuticals Inc.). Historically, aHUS was associated with very high rates of mortality and morbidity. Prior therapies included plasma therapy and/or liver transplantation. Although often life saving, these were imperfect and had many complications. We review the conditions included under the rubric of aHUS: S. pneumoniae HUS (SpHUS), inborn errors of metabolism, and disorders of complement regulation, emphasizing their differences and similarities. We focus on the clinical features, diagnosis, and pathogenesis, and treatment of aHUS that results from mutations in genes encoding alternative complement regulators, SpHUS and HUS associated with inborn errors of metabolism. Mutations in complement genes, or antibodies to their protein products, result in unregulated activity of the alternate complement pathway, endothelial injury, and thrombotic microangiopathy (TMA). Eculizumab is a humanized monoclonal antibody that inhibits the production of the terminal complement components C5a and the membrane attack complex (C5b-9) by binding to complement protein C5a. This blocks the proinflammatory and cytolytic effects of terminal complement activation. Eculizumab use has been reported in many case reports, and retrospective and prospective clinical trials in aHUS. There have been few serious side effects and no reports of tachphylaxis or drug resistance. The results are very encouraging and eculizumab is now recognized as the treatment of choice for aHUS.

Therapeutic plasma exchange for the treatment of pediatric renal diseases in 2013

Therapeutic plasma exchange is an extracorporeal treatment modality that removes systemic circulating pathologic factors or replaces absent plasma components and plays a role in many nephrologic conditions. It presents a number of technical challenges in the pediatric population but has become an increasingly common practice in pediatric nephrology over the past several decades. While prospective evidence is often lacking, our increased understanding of the molecular pathogenesis underlying many pediatric renal diseases provides sound reasoning for the use of plasma exchange in treating these conditions. This review will present the currently accepted indications for plasma exchange in children, the technical aspects of the procedure and its potential complications.

Shigatoxin-associated hemolytic uremic syndrome: current molecular mechanisms and future therapies

Hemolytic uremic syndrome is the leading cause of acute kidney injury in childhood. Ninety percent of cases are secondary to gastrointestinal infection with shigatoxin-producing bacteria. In this review, we discuss the molecular mechanisms of shigatoxin leading to hemolytic uremic syndrome and the emerging role of the complement system and vascular endothelial growth factor in its pathogenesis. We also review the evidence for treatment options to date, in particular antibiotics, plasma exchange, and immunoadsorption, and link this to the molecular pathology. Finally, we discuss future avenues of treatment, including shigatoxin-binding agents and complement inhibitors, such as eculizumab.

Does early initiation of therapeutic plasma exchange improve outcome in pediatric stem cell transplant-associated thrombotic microangiopathy?

BACKGROUND

The use of therapeutic plasma exchange (TPE) in hematopoietic stem cell transplant-associated thrombotic microangiopathy (TA-TMA) is controversial because the exact mechanism of injury in TA-TMA is not yet understood.

STUDY DESIGN AND METHODS

The study objective was to retrospectively review the outcome of children receiving TPE for TA-TMA at our institution. We hypothesized that patients initiating TPE earlier in their disease course would receive a greater benefit than those starting later, regardless of the therapeutic mechanism.

RESULTS

We identified 10 consecutive pediatric patients with TA-TMA treated with TPE. Nine of these patients showed normalization of the laboratory variables associated with microangiopathy during their TPE course, but only five patients recovered renal function and survived TA-TMA. The five survivors started TPE a median of 17 days (range, 4-25 days) after TA-TMA diagnosis while the five patients who died started TPE a median of 32 days (range, 17-73 days) after TA-TMA was diagnosed. Three of the five survivors had multiorgan failure at TA-TMA diagnosis and completely recovered with early institution of TPE. These three survivors were able to discontinue renal replacement therapy, and all achieved a normal posttreatment creatinine. The five patients with later institution of TPE progressed to end-stage renal disease and all died. There were no serious TPE-related complications in either group.

CONCLUSION

This is the first report evaluating TPE response in regard to procedure initiation time after TA-TMA diagnosis. Our data suggests that early initiation of TPE might be beneficial even in patients with multiorgan failure due to TA-TMA.

Eculizumab in atypical haemolytic-uraemic syndrome allows cessation of plasma exchange and dialysis

Disorders in complement regulation are a major cause of atypical haemolytic-uraemic syndrome (aHUS). Eculizumab, a monoclonal antibody targeting complement C5 and blocking the terminal complement cascade, should theoretically be useful in this disease, particularly when associated with specific complement pathway anomalies such as Factor H deficiency. Eculizumab is emerging as an effective treatment for post-transplant aHUS recurrence and may have a role in treating de novo aHUS, halting the haemolytic process. In this case report, we describe the fourth case of aHUS treated with eculizumab. In our patient, with a known complement Factor H mutation, not only has the disease process become quiescent but also this therapy has led to significantly improved renal function so that dialysis is no longer necessary.