Dynamics of complement activation in aHUS and how to monitor eculizumab therapy

Noris, Marina; Galbusera, Miriam; Gastoldi, Sara; Macor, Paolo; Banterla, Federica; Bresin, Elena; Tripodo, Claudio; Bettoni, Serena; Donadelli, Roberta; Valoti, Elisabetta; Tedesco, Francesco; Amore, Alessandro; Coppo, Rosanna; Ruggenenti, Piero; Gotti, Eliana; Remuzzi, Giuseppe

doi:10.1182/blood-2014-02-558296

Cited by 298 publications

(330 citation statements)

References 34 publications

Supporting

Mentioning

303

Contrasting

Unclassified

Order By: Relevance

“…HUVECs were filled with calcein, and complement activation on cells was initiated with an anti-CD59 antibody that simultaneously activates the complement system and blocks function of the membraneassociated complement regulator CD59. 28,31 Increasing anti-CD59 concentration was observed to increase calcein levels in supernatants ( Figure 6A), indicating escape of the very small compound calcein (1 kDa) from the cells through complement membrane attack complex pores (C5b-9). Because the larger LDH (140 kDa) was not released (Figure 6A), the cells were not lysed.…”

Section: Sialic Acid Is Important For Complement Regulation On Endothmentioning

confidence: 99%

Disturbed sialic acid recognition on endothelial cells and platelets in complement attack causes atypical hemolytic uremic syndrome

Hyvärinen

Meri

Jokiranta

2016

Blood

View full text Add to dashboard Cite

Key Points• Sialic acids are critical for factor H-mediated complement regulation on endothelial cells, erythrocytes, and platelets. • Impaired ability of factor H mutants to simultaneously bind sialic acid and C3b on cells explains their association with aHUS.Uncontrolled activation of the complement system against endothelial and blood cells is central to the pathogenesis of atypical hemolytic uremic syndrome (aHUS). aHUS patients frequently carry mutations in the inhibitory complement regulator factor H (FH). Mutations cluster in domains [19][20], which are critical for recognizing self surfaces. On endothelial cells, binding of FH is generally attributed to heparan sulfate. This theory, however, is questioned by the puzzling observation that some aHUSassociated mutations markedly enhance FH binding to heparin and endothelial cells. In this article, we show that, instead of disturbed heparin interactions, the impaired ability of C-terminal mutant FH molecules to recognize sialic acid in the context of surface-bound C3b explains their pathogenicity. By using recombinant FH19-20 as a competitor for FH and measuring erythrocyte lysis and deposition of complement C3b and C5b-9 on endothelial cells and platelets, we now show that several aHUS-associated mutations, which have been predicted to impair FH19-20 binding to sialic acid, prevent FH19-20 from antagonizing FH function on cells. When sialic acid was removed, the wild-type FH19-20 also lost its ability to interfere with FH function on cells. These results indicate that sialic acid is critical for FH-mediated complement regulation on erythrocytes, endothelial cells, and platelets. The inability of C-terminal mutant FH molecules to simultaneously bind sialic acid and C3b on cells provides a unifying explanation for their association with aHUS. Proper formation of FH-sialic acid-C3b complexes on surfaces exposed to plasma is essential for preventing cell damage and thrombogenesis characteristic of aHUS.

show abstract

Section: Sialic Acid Is Important For Complement Regulation On Endothmentioning

confidence: 99%

Disturbed sialic acid recognition on endothelial cells and platelets in complement attack causes atypical hemolytic uremic syndrome

Hyvärinen

Meri

Jokiranta

2016

Blood

View full text Add to dashboard Cite

show abstract

“…ADP-activated HMEC-1 cells are a good ex vivo aHUS model; they overexpress P-selectin, which works as a receptor for C3b capable of initiating complement activation (35). When these activated cells are exposed to serum from aHUS patients carrying mutations in soluble complement components that impair complement regulation, the surface of these cells becomes covered by C3 fragments and C5b-9 deposits; NHS has no such effect (36,37). We have used this experimental setting to evaluate the capacity of the FB28.4.2 Ab to prevent complement-mediated endothelial cell damage.…”

Section: Fb2842 Blocks C3mentioning

confidence: 99%

A Novel Antibody against Human Factor B that Blocks Formation of the C3bB Proconvertase and Inhibits Complement Activation in Disease Models

Subias

Tortajada

Gastoldi

et al. 2014

The Journal of Immunology

Self Cite

View full text Add to dashboard Cite

The alternative pathway (AP) is critical for the efficient activation of complement regardless of the trigger. It is also a major player in pathogenesis, as illustrated by the long list of diseases in which AP activation contributes to pathology. Its relevance to human disease is further emphasized by the high prevalence of pathogenic inherited defects and acquired autoantibodies disrupting components and regulators of the AP C3-convertase. Because pharmacological downmodulation of the AP emerges as a broad-spectrum treatment alternative, there is a powerful interest in developing new molecules to block formation and/or activity of the AP C3-convertase. In this paper, we describe the generation of a novel mAb targeting human factor B (FB). mAb FB48.4.2, recognizing with high affinity an evolutionary-conserved epitope in the Ba fragment of FB, very efficiently inhibited formation of the AP C3-proconvertase by blocking the interaction between FB and C3b. In vitro assays using rabbit and sheep erythrocytes demonstrated that FB28.4.2 was a potent AP inhibitor that blocked complement-mediated hemolysis in several species. Using ex vivo models of disease we demonstrated that FB28.4.2 protected paroxysmal nocturnal hemoglobinuria erythrocytes from complement-mediated hemolysis and inhibited both C3 fragment and C5b-9 deposition on ADP-activated HMEC-1 cells, an experimental model for atypical hemolytic uremic syndrome. Moreover, i.v. injection of FB28.4.2 in rats blocked complement activation in rat serum and prevented the passive induction of experimental autoimmune Myasthenia gravis. As a whole, these data demonstrate the potential value of FB28.4.2 for the treatment of disorders associated with AP complement dysregulation in man and animal models.

show abstract

“…It is important to mention that the measurement of plasma biomarkers of C5a and C5b-9 are surrogates for the formation of the membrane attack complex that is a cellular event. Therefore, the markers of terminal activation may not be sufficiently sensitive in all patients with terminal complement activation as reported by Noris et al 17 For this reason, complement biomarkers should be viewed as one additional piece of data to diagnose patients with a complement-mediated TMA, and not be used alone to exclude the diagnosis of a HCT-TMA.…”

mentioning

confidence: 99%

Eculizumab therapy in adults with allogeneic hematopoietic cell transplant-associated thrombotic microangiopathy

Vasu

Satoskar

et al. 2016

Bone Marrow Transplant

View full text Add to dashboard Cite

Dynamics of complement activation in aHUS and how to monitor eculizumab therapy

Cited by 298 publications

References 34 publications

Disturbed sialic acid recognition on endothelial cells and platelets in complement attack causes atypical hemolytic uremic syndrome

Disturbed sialic acid recognition on endothelial cells and platelets in complement attack causes atypical hemolytic uremic syndrome

A Novel Antibody against Human Factor B that Blocks Formation of the C3bB Proconvertase and Inhibits Complement Activation in Disease Models

Eculizumab therapy in adults with allogeneic hematopoietic cell transplant-associated thrombotic microangiopathy

Contact Info

Product

Resources

About