In situ Visualization of C3/C5 Convertases to Differentiate Complement Activation

Person, Fermín; Petschull, Tim; Wulf, Sonia; Büscheck, Franziska; Biniaminov, Sergey; Fehrle, Wilfrid; Oh, Jun; Skerka, Christine; Zipfel, Peter F.; Wiech, Thorsten

doi:10.1016/j.ekir.2020.03.009

Cited by 9 publications

(10 citation statements)

References 8 publications

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“…With that tool, we found a reduction of both cell types, indicating functional relevance of reduced C5a and C5b-9 deposits. As previously described, we are also able to visualize the alternative and classical C3 convertase using proximity ligation assay (PLA) (Figure 3C) (9). Both were unaffected by the C5 blockade, assumably since Eculizumab blocks downstream of the C3 convertases.…”

Section: Case Analysismentioning

confidence: 54%

An Interdisciplinary Diagnostic Approach to Guide Therapy in C3 Glomerulopathy

et al. 2022

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Since the re-classification of membranoproliferative glomerulonephritis the new disease entity C3 glomerulopathy is diagnosed if C3 deposition is clearly dominant over immunoglobulins in immunohistochemistry or immunofluorescence. Although this new definition is more orientated at the pathophysiology as mediated by activity of the alternative complement pathway C3 glomerulopathy remains a heterogenous group of disorders. Genetic or autoimmune causes are associated in several but not in all patients with this disease. However, prognosis is poorly predictable, and clinicians cannot directly identify patients that might benefit from therapy. Moreover, therapy may range from supportive care alone, unspecific immune suppression, plasma treatment, or plasma exchange to complement inhibition. The current biopsy based diagnostic approaches sometimes combined with complement profiling are not sufficient to guide clinicians neither (i) whether to treat an individual patient, nor (ii) to choose the best therapy. With this perspective, we propose an interdisciplinary diagnostic approach, including detailed analysis of the kidney biopsy for morphological alterations and immunohistochemical staining, for genetic analyses of complement genes, complement activation patterning in plasma, and furthermore for applying novel approaches for convertase typing and complement profiling directly in renal tissue. Such a combined diagnostic approach was used here for a 42-year-old female patient with a novel mutation in the Factor H gene, C3 glomerulopathy and signs of chronic endothelial damage. We present here an approach that might in future help to guide therapy of renal diseases with relevant complement activation, especially since diverse new anti-complement agents are under clinical investigation.

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Section: Case Analysismentioning

confidence: 54%

An Interdisciplinary Diagnostic Approach to Guide Therapy in C3 Glomerulopathy

et al. 2022

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“…In total, 20,350 manually annotated and reviewed proteins of Homo sapiens sapiens were collected with the analysis software HSA KIT (HS Analysis GmbH) [ 22 ] using the Swiss-Prot section of the UniProt database [ 23 ] (access date 27 March 2020). The protein sequences were preprocessed to replace all 37 selenocysteines (U) with cysteines (C).…”

Section: Resultsmentioning

confidence: 99%

Resemblance-Ranking Peptide Library to Screen for Binders to Antibodies on a Peptidomic Scale

Jenne

Biniaminov²,

Biniaminov³

et al. 2022

IJMS

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A novel resemblance-ranking peptide library with 160,000 10-meric peptides was designed to search for selective binders to antibodies. The resemblance-ranking principle enabled the selection of sequences that are most similar to the human peptidome. The library was synthesized with ultra-high-density peptide arrays. As proof of principle, screens for selective binders were performed for the therapeutic anti-CD20 antibody rituximab. Several features in the amino acid composition of antibody-binding peptides were identified. The selective affinity of rituximab increased with an increase in the number of hydrophobic amino acids in a peptide, mainly tryptophan and phenylalanine, while a total charge of the peptide remained relatively small. Peptides with a higher affinity exhibited a lower sum helix propensity. For the 30 strongest peptide binders, a substitutional analysis was performed to determine dissociation constants and the invariant amino acids for binding to rituximab. The strongest selective peptides had a dissociation constant in the hundreds of the nano-molar range. The substitutional analysis revealed a specific hydrophobic epitope for rituximab. To show that conformational binders can, in principle, be detected in array format, cyclic peptide substitutions that are similar to the target of rituximab were investigated. Since the specific binders selected via the resemblance-ranking peptide library were based on the hydrophobic interactions that are widespread in the world of biomolecules, the library can be used to screen for potential linear epitopes that may provide information about the cross-reactivity of antibodies.

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“…In order to provide novel precision tools to measure local complement activity in biopsies, we developed a methodological workflow to detect assembled—and therefore likely active—C3/C5 complement convertases in tissue (Person et al 2020 ). We use brightfield proximity ligation assays for the detection of assembled C3b with the fragment Bb attached, the alternative convertase, and for C2b with C4b, the convertase of the classical/lectin pathway.…”

Section: Novel Diagnostic Tools For Precision Complement Monitoringmentioning

confidence: 99%

“…Such understanding is important to describe the exact pathophysiology, to improve diagnostics and is also relevant for precision therapy. Mapping the defective steps within the complement landscape likely will in future help to select the appropriate complement inhibitor(s) (Person et al 2020 ). Furthermore, a detailed knowledge of the affected parameters allows to monitor the response of individual patients to the complement inhibitors, autoantibody therapy, and upon kidney transplantation.…”

Section: Introductionmentioning

confidence: 99%

Complement catalyzing glomerular diseases

et al. 2021

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Complement is an evolutionarily conserved system which is important in the defense against microorganisms and also in the elimination of modified or necrotic elements of the body. Complement is activated in a cascade type manner and activation and all steps of cascade progression are tightly controlled and regulatory interleaved with many processes of inflammatory machinery. Overshooting of the complement system due to dysregulation can result in the two prototypes of primary complement mediated renal diseases: C3 glomerulopathy and thrombotic microangiopathy. Apart from these, complement also is highly activated in many other inflammatory native kidney diseases, such as membranous nephropathy, ANCA-associated necrotizing glomerulonephritis, and IgA nephropathy. Moreover, it likely plays an important role also in the transplant setting, such as in antibody-mediated rejection or in hematopoietic stem cell transplant associated thrombotic microangiopathy. In this review, these glomerular disorders are discussed with regard to the role of complement in their pathogenesis. The consequential, respective clinical trials for complement inhibitory therapy strategies for these diseases are described.

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In situ Visualization of C3/C5 Convertases to Differentiate Complement Activation

Cited by 9 publications

References 8 publications

An Interdisciplinary Diagnostic Approach to Guide Therapy in C3 Glomerulopathy

An Interdisciplinary Diagnostic Approach to Guide Therapy in C3 Glomerulopathy

Resemblance-Ranking Peptide Library to Screen for Binders to Antibodies on a Peptidomic Scale

Complement catalyzing glomerular diseases

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