Miriam Galbusera1, Marina Noris2, Sara Gastoldi1, Elena Bresin1, Caterina Mele1, Matteo Breno1, Paola Cuccarolo1, Marta Alberti1, Elisabetta Valoti1, Rossella Piras1, Roberta Donadelli1, Marina Vivarelli3, Luisa Murer4, Carmine Pecoraro5, Elisa Ferrari1, Annalisa Perna1, Ariela Benigni1, Valentina Portalupi6, Giuseppe Remuzzi7. 1. Istituto di Ricerche Farmacologiche Mario Negri IRCCS, Clinical Research Center for Rare Diseases Aldo e Cele Daccò and Centro Anna Maria Astori, Science and Technology Park Kilometro Rosso, Bergamo, Italy. 2. Istituto di Ricerche Farmacologiche Mario Negri IRCCS, Clinical Research Center for Rare Diseases Aldo e Cele Daccò and Centro Anna Maria Astori, Science and Technology Park Kilometro Rosso, Bergamo, Italy. Electronic address: marina.noris@marionegri.it. 3. Division of Nephrology and Dialysis, Children's Hospital Bambino Gesù, IRCCS, Rome, Italy. 4. Unit of Pediatric Nephrology, Dialysis and Transplantation, Azienda Ospedaliera di Padova, Padua, Italy. 5. Pediatric Nephrology Unit, Santobono-Pausilipon Hospital, Naples, Italy. 6. Unit of Nephrology and Dialysis, Azienda Socio-Sanitaria Territoriale Papa Giovanni XXIII, Bergamo, Italy. 7. Istituto di Ricerche Farmacologiche Mario Negri IRCCS, Clinical Research Center for Rare Diseases Aldo e Cele Daccò and Centro Anna Maria Astori, Science and Technology Park Kilometro Rosso, Bergamo, Italy; Unit of Nephrology and Dialysis, Azienda Socio-Sanitaria Territoriale Papa Giovanni XXIII, Bergamo, Italy; L. Sacco Department of Biomedical and Clinical Sciences, University of Milan, Milan, Italy.
Abstract
RATIONALE & OBJECTIVE: Although primary atypical hemolytic uremic syndrome (aHUS) is associated with abnormalities in complement genes and antibodies to complement factor H, the role of complement in secondary aHUS remains debatable. We evaluated the usefulness of an ex vivo test to: (1) detect complement activation within the endothelium in primary and secondary aHUS, (2) differentiate active disease from remission, (3) monitor the effectiveness of eculizumab therapy, and (4) identify relapses during eculizumab dosage tapering and after discontinuation of treatment. STUDY DESIGN: Case series. SETTING & PARTICIPANTS: 121 patients with primary aHUS and 28 with secondary aHUS. Serum samples were collected during acute episodes, following remission, and during eculizumab treatment and were assessed using a serum-induced ex vivo C5b-9 endothelial deposition test. RESULTS: Serum-induced C5b-9 deposition on cultured microvascular endothelium was quantified by calculating the endothelial area covered by C5b-9 staining; values were expressed as percentage of C5b-9 deposits induced by a serum pool from healthy controls. Testing with adenosine diphosphate-activated endothelium demonstrated elevated C5b-9 deposits for all untreated patients with aHUS independent of disease activity, while testing with unstimulated endothelium demonstrated deposits only in active disease. Similar findings were observed in secondary aHUS. Serum-induced C5b-9 deposits on activated and unstimulated endothelium normalized during eculizumab treatment. 96% (22/23) of patients receiving eculizumab at extended 3- or 4-week dosing intervals demonstrated normal C5b-9 deposits on activated endothelium, despite most patients having CH50Eq (serum complement activity) > 20 UEq/mL, indicating that adequate complement control was achieved even with incomplete blockade of circulating C5. During eculizumab dosage tapering or after treatment discontinuation, all patients experiencing relapses versus only 6% (1/17) of those in stable remission had elevated C5b-9 deposits on unstimulated endothelium. LIMITATIONS: The C5b-9 endothelial deposition test can be performed in only specialized laboratories. Findings on eculizumab dosage tapering need to be confirmed with longitudinal monitoring of C5b-9 deposition. CONCLUSIONS: The C5b-9 endothelial deposition assay may represent an advance in our ability to monitor aHUS activity and individualize therapy.
RATIONALE & OBJECTIVE: Although primary atypical hemolytic uremic syndrome (aHUS) is associated with abnormalities in complement genes and antibodies to complement factor H, the role of complement in secondary aHUS remains debatable. We evaluated the usefulness of an ex vivo test to: (1) detect complement activation within the endothelium in primary and secondary aHUS, (2) differentiate active disease from remission, (3) monitor the effectiveness of eculizumab therapy, and (4) identify relapses during eculizumab dosage tapering and after discontinuation of treatment. STUDY DESIGN: Case series. SETTING & PARTICIPANTS: 121 patients with primary aHUS and 28 with secondary aHUS. Serum samples were collected during acute episodes, following remission, and during eculizumab treatment and were assessed using a serum-induced ex vivo C5b-9 endothelial deposition test. RESULTS: Serum-induced C5b-9 deposition on cultured microvascular endothelium was quantified by calculating the endothelial area covered by C5b-9 staining; values were expressed as percentage of C5b-9 deposits induced by a serum pool from healthy controls. Testing with adenosine diphosphate-activated endothelium demonstrated elevated C5b-9 deposits for all untreated patients with aHUS independent of disease activity, while testing with unstimulated endothelium demonstrated deposits only in active disease. Similar findings were observed in secondary aHUS. Serum-induced C5b-9 deposits on activated and unstimulated endothelium normalized during eculizumab treatment. 96% (22/23) of patients receiving eculizumab at extended 3- or 4-week dosing intervals demonstrated normal C5b-9 deposits on activated endothelium, despite most patients having CH50Eq (serum complement activity) > 20 UEq/mL, indicating that adequate complement control was achieved even with incomplete blockade of circulating C5. During eculizumab dosage tapering or after treatment discontinuation, all patients experiencing relapses versus only 6% (1/17) of those in stable remission had elevated C5b-9 deposits on unstimulated endothelium. LIMITATIONS: The C5b-9 endothelial deposition test can be performed in only specialized laboratories. Findings on eculizumab dosage tapering need to be confirmed with longitudinal monitoring of C5b-9 deposition. CONCLUSIONS: The C5b-9 endothelial deposition assay may represent an advance in our ability to monitor aHUS activity and individualize therapy.
Authors: Marta Palomo; Miquel Blasco; Patricia Molina; Miquel Lozano; Manuel Praga; Sergi Torramade-Moix; Julia Martinez-Sanchez; Joan Cid; Gines Escolar; Enric Carreras; Cristina Paules; Fatima Crispi; Luis F Quintana; Esteban Poch; Lida Rodas; Emma Goma; Johann Morelle; Mario Espinosa; Enrique Morales; Ana Avila; Virginia Cabello; Gema Ariceta; Sara Chocron; Joaquin Manrique; Xoana Barros; Nadia Martin; Ana Huerta; Gloria M Fraga-Rodriguez; Mercedes Cao; Marisa Martin; Ana Maria Romera; Francesc Moreso; Anna Manonelles; Eduard Gratacos; Arturo Pereira; Josep M Campistol; Maribel Diaz-Ricart Journal: Clin J Am Soc Nephrol Date: 2019-11-06 Impact factor: 8.237
Authors: Lara Kollbrunner; Patricia Hirt-Minkowski; Javier Sanz; Elena Bresin; Thomas J Neuhaus; Helmut Hopfer; Andreas W Jehle Journal: Front Med (Lausanne) Date: 2021-06-02