Solution‐Based Determination of Dissociation Constants for the Binding of Aβ42 to Antibodies

Zhang, Tao; Nagel-Steger, Luitgard; Willbold, Dieter

doi:10.1002/open.201900167

Cited by 7 publications

(3 citation statements)

References 38 publications

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“…27,28 The fitted BLI sensorgrams are shown in Supplemental Figures S3 and S4. The affinity constant (dissociation equilibrium constant) K D of the binding pair of anti-Aβ Ab and Aβ 1−40 was 6.6 × 10 −8 M, and that of anti-Tf Ab and Tf was 3.9 × 10 −9 M. The affinity constants were consistent with the previous report of K D of the anti-Aβ Ab, 29 as well as the knowledge that mouse monoclonal antibodies typically have nanomolar-level affinity to protein antigens. 30 It should be noted that MPIE-ESI-MS is not an ideal tool for quantitative analysis.…”

Section: ■ Results and Discussionsupporting

confidence: 90%

Microprobe-Capture In-Emitter Elution: An Affinity Capture Technique to Directly Couple a Label-Free Optical Sensing Technology with Mass Spectrometry for Protein Analysis

Luo

Yang

2023

Anal. Chem.

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Affinity capture of an analyte by a capture agent is one of the most effective sample preparation approaches in mass spectrometry (MS), especially top-down MS. We describe a new affinity capture technique for protein targets, called microprobe-capture in-emitter elution (MPIE), which can directly couple a label-free optical sensing technology (next-generation biolayer interferometry, BLI) with MS. To implement MPIE, an analyte is first captured on the surface of a microprobe and subsequently eluted from the microprobe inside an electrospray emitter. The capture process is monitored in real-time via BLI. When electrospray is established from the emitter to a mass spectrometer, the analyte is immediately ionized via electrospray ionization (ESI) for MS analysis. By this means, BLI and MS are directly coupled in the form of MPIE-ESI-MS. The performance of MPIE-ESI-MS was demonstrated by the analysis of β-amyloid 1–40 and transferrin using both standard samples and human specimens. In comparison to conventional affinity capture techniques such as bead-based immunoprecipitation, MPIE innovates the affinity capture methodology by introducing real-time process monitoring and providing binding characteristics of analytes, offering more information-rich experiment results. Thus, MPIE is a valuable addition to the top-down MS sample preparation toolbox, and MPIE-ESI-MS can be useful for identification and characterization of targets of interest.

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Section: ■ Results and Discussionsupporting

confidence: 90%

Microprobe-Capture In-Emitter Elution: An Affinity Capture Technique to Directly Couple a Label-Free Optical Sensing Technology with Mass Spectrometry for Protein Analysis

Luo

Yang

2023

Anal. Chem.

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“…As an alternative approach to detect possible binding sites of SARS-CoV-2, biotin-labelled recombinant viral S protein binding to ACE2 may be used for staining. The affinity of S protein binding to ACE2 (K d = 1.2 nM) 8 is in the same range as that of antibodies binding to their substrates 26 , 27 . Therefore, a histochemical staining within the same intensity range as is known from antibody staining can be expected.…”

Section: Discussionmentioning

confidence: 83%

Viral S protein histochemistry reveals few potential SARS-CoV-2 entry sites in human ocular tissues

Martin

Wolf

Lapp

et al. 2021

Sci Rep

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Despite the reported low expression of the primary SARS-CoV-2 receptor ACE2 in distinct ocular tissues, some clinical evidence suggests that SARS-CoV-2 can infect the eye. In this study, we explored potential entry sites for SARS-CoV-2 by viral S protein histochemistry on various ocular tissues and compared the staining patterns with RNA and protein expression of TMPRSS2 and ACE2. Potential viral entry sites were investigated by histochemistry using tagged recombinant viral S protein on 52 ocular tissue samples including specimens of the cornea, conjunctiva, lid margin, lacrimal gland tissue, retina, choroid, and RPE. In addition, ACE2 and TMPRSS2 immunohistochemistry were performed on the same ocular tissue, each with distinct antibodies binding to different epitopes. Lung tissue samples were used as positive controls. Finally, bulk RNA sequencing (RNA-Seq) was used to determine the expression of ACE2 and its auxiliary factors in the tissues mentioned above. S protein histochemistry revealed a positive staining in lung tissue but absent staining in the cornea, the conjunctiva, eye lid samples, the lacrimal glands, the retina and the optic nerve which was supported by hardly any immunoreactivity for ACE2 and TMPRSS2 and scarce ACE2 and TMPRSS2 RNA expression. Negligible staining with antibodies targeting ACE2 or TMPRSS2 was seen in the main and accessory lacrimal glands. In contrast, ocular staining (S protein, ACE2, TMPRSS2) was distinctly present in pigmented cells of the RPE and choroid, as well as in the ciliary body and the iris stroma. S protein histochemistry revealed hardly any SARS-CoV-2 entry sites in all ocular tissues examined. Similarly, no significant ACE2 or TMPRSS2 expression was found in extra- and intraocular tissue. While this study suggest a rather low risk of ocular infection with SARS-CoV-2, it should be noted, that potential viral entry sites may increase in response to inflammation or in certain disease states.

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“…A major concern is the determination of the affinities of the antibodies for the different Aβ subspecies. 38 They are not always easy to measure accurately and are clear drivers of the biomarker responses. Here we applied the binding affinities as summarized in the QSP paper.…”

Section: Discussionmentioning

confidence: 99%

Quantitative systems pharmacology‐based exploration of relevant anti‐amyloid therapy challenges in clinical practice

Geerts,

Bergeler,

Walker

et al. 2024

A&D Transl Res & Clin Interv

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INTRODUCTIONAddressing practical challenges in clinical practice after the recent approvals of amyloid antibodies in Alzheimer's disease (AD) will benefit more patients. However, generating these answers using clinical trials or real‐world evidence is not practical, nor feasible.METHODSHere we use a Quantitative Systems Pharmacology (QSP) computational model of amyloid aggregation dynamics, well validated with clinical data on biomarkers and amyloid‐related imaging abnormality–edema (ARIA‐E) liability of six amyloid antibodies in clinical trials to explore various clinical practice challenges.RESULTSTreatment duration to reach amyloid negativity ranges from 12 to 44, 16 to 40, and 6 to 20 months for lecanemab, aducanumab, and donanemab, respectively, for baseline central amyloid values between 50 and 200 Centiloids (CL). Changes in plasma cerebrospinal fluid Aβ42 and the plasma Aβ42/ Aβ40 ratio—fluid biomarkers to detect central amyloid negativity—is greater for lecanemab than for aducanumab and donanemab, indicating that these fluid amyloid biomarkers are only suitable for lecanemab. After reaching amyloid negativity an optimal maintenance schedule consists of a 24‐month, 48‐month and 64‐month interval for 10 mg/kg (mpk) lecanemab, 10 mpk aducanumab, and 20 mpk donanemab, respectively, to keep central amyloid negative for 10 years. Cumulative ARIA‐E liability could be reduced to almost half by introducing a drug holiday in the first months. For patients experiencing ARIA‐E, restarting treatment with a conservative titration strategy resulted in an additional delay ranging between 3 and 4 months (donanemab), 5 months (lecanemab), and up to 7 months (aducanumab) for reaching amyloid negativity, depending upon the timing of the incident. Clinical trial designs for Down syndrome patients suggested the same rank order for central amyloid reduction, but higher ARIA‐E liability especially for donanemab, which can be significantly mitigated by adopting a longer titration period.DISCUSSIONThis QSP platform could support clinical practice challenges to optimize real‐world treatment paradigms for new and existing amyloid drugs.

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Solution‐Based Determination of Dissociation Constants for the Binding of Aβ42 to Antibodies

Cited by 7 publications

References 38 publications

Microprobe-Capture In-Emitter Elution: An Affinity Capture Technique to Directly Couple a Label-Free Optical Sensing Technology with Mass Spectrometry for Protein Analysis

Microprobe-Capture In-Emitter Elution: An Affinity Capture Technique to Directly Couple a Label-Free Optical Sensing Technology with Mass Spectrometry for Protein Analysis

Viral S protein histochemistry reveals few potential SARS-CoV-2 entry sites in human ocular tissues

Quantitative systems pharmacology‐based exploration of relevant anti‐amyloid therapy challenges in clinical practice

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