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Bai Z, Wang J, Li J, Yuan H, Wang P, Zhang M, Feng Y, Cao X, Cao X, Kang G, de Marco A, Huang H. Design of nanobody-based bispecific constructs by in silico affinity maturation and umbrella sampling simulations. Comput Struct Biotechnol J 2022; 21:601-613. [PMID: 36659922 PMCID: PMC9822835 DOI: 10.1016/j.csbj.2022.12.021] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2022] [Revised: 12/14/2022] [Accepted: 12/14/2022] [Indexed: 12/23/2022] Open
Abstract
Random mutagenesis is the natural opportunity for proteins to evolve and biotechnologically it has been exploited to create diversity and identify variants with improved characteristics in the mutant pools. Rational mutagenesis based on biophysical assumptions and supported by computational power has been proposed as a faster and more predictable strategy to reach the same aim. In this work we confirm that substantial improvements in terms of both affinity and stability of nanobodies can be obtained by using combinations of algorithms, even for binders with already high affinity and elevated thermal stability. Furthermore, in silico approaches allowed the development of an optimized bispecific construct able to bind simultaneously the two clinically relevant antigens TNF-α and IL-23 and, by means of its enhanced avidity, to inhibit effectively the apoptosis of TNF-α-sensitive L929 cells. The results revealed that salt bridges, hydrogen bonds, aromatic-aromatic and cation-pi interactions had a critical role in increasing affinity. We provided a platform for the construction of high-affinity bispecific constructs based on nanobodies that can have relevant applications for the control of all those biological mechanisms in which more than a single antigen must be targeted to increase the treatment effectiveness and avoid resistance mechanisms.
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Affiliation(s)
- Zixuan Bai
- Department of Biochemical Engineering, School of Chemical Engineering and Technology, Tianjin University, Tianjin 300350, China,Frontiers Science Center for Synthetic Biology and Key Laboratory of Systems Bioengineering (Ministry of Education), Tianjin University, Tianjin 300072, China
| | - Jiewen Wang
- Department of Biochemical Engineering, School of Chemical Engineering and Technology, Tianjin University, Tianjin 300350, China,Frontiers Science Center for Synthetic Biology and Key Laboratory of Systems Bioengineering (Ministry of Education), Tianjin University, Tianjin 300072, China,Institute of Shaoxing, Tianjin University, Zhejiang 312300, China
| | - Jiaqi Li
- Department of Biochemical Engineering, School of Chemical Engineering and Technology, Tianjin University, Tianjin 300350, China,Frontiers Science Center for Synthetic Biology and Key Laboratory of Systems Bioengineering (Ministry of Education), Tianjin University, Tianjin 300072, China,Institute of Shaoxing, Tianjin University, Zhejiang 312300, China
| | - Haibin Yuan
- Department of Biochemical Engineering, School of Chemical Engineering and Technology, Tianjin University, Tianjin 300350, China,Frontiers Science Center for Synthetic Biology and Key Laboratory of Systems Bioengineering (Ministry of Education), Tianjin University, Tianjin 300072, China
| | - Ping Wang
- Tianjin Modern Innovative TCM Technology Co. Ltd., Tianjin, China
| | - Miao Zhang
- Department of Biochemical Engineering, School of Chemical Engineering and Technology, Tianjin University, Tianjin 300350, China,Frontiers Science Center for Synthetic Biology and Key Laboratory of Systems Bioengineering (Ministry of Education), Tianjin University, Tianjin 300072, China,China Resources Biopharmaceutical Company Limited, Beijing, China
| | - Yuanhang Feng
- Department of Biochemical Engineering, School of Chemical Engineering and Technology, Tianjin University, Tianjin 300350, China,Frontiers Science Center for Synthetic Biology and Key Laboratory of Systems Bioengineering (Ministry of Education), Tianjin University, Tianjin 300072, China
| | - Xiangtong Cao
- Frontiers Science Center for Synthetic Biology and Key Laboratory of Systems Bioengineering (Ministry of Education), Tianjin University, Tianjin 300072, China
| | - Xiangan Cao
- Frontiers Science Center for Synthetic Biology and Key Laboratory of Systems Bioengineering (Ministry of Education), Tianjin University, Tianjin 300072, China
| | - Guangbo Kang
- Department of Biochemical Engineering, School of Chemical Engineering and Technology, Tianjin University, Tianjin 300350, China,Frontiers Science Center for Synthetic Biology and Key Laboratory of Systems Bioengineering (Ministry of Education), Tianjin University, Tianjin 300072, China,Institute of Shaoxing, Tianjin University, Zhejiang 312300, China,Corresponding authors at: Department of Biochemical Engineering, School of Chemical Engineering and Technology, Tianjin University, Tianjin 300350, China.
| | - Ario de Marco
- Laboratory for Environmental and Life Sciences, University of Nova Gorica, Nova Gorica, Slovenia,Corresponding author.
| | - He Huang
- Department of Biochemical Engineering, School of Chemical Engineering and Technology, Tianjin University, Tianjin 300350, China,Frontiers Science Center for Synthetic Biology and Key Laboratory of Systems Bioengineering (Ministry of Education), Tianjin University, Tianjin 300072, China,Institute of Shaoxing, Tianjin University, Zhejiang 312300, China,Corresponding authors at: Department of Biochemical Engineering, School of Chemical Engineering and Technology, Tianjin University, Tianjin 300350, China.
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TLR4- and TRIF-dependent stimulation of B lymphocytes by peptide liposomes enables T cell-independent isotype switch in mice. Blood 2012; 121:85-94. [PMID: 23144170 DOI: 10.1182/blood-2012-02-413831] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Immunoglobulin class switching from IgM to IgG in response to peptides is generally T cell-dependent and vaccination in T cell-deficient individuals is inefficient. We show that a vaccine consisting of a dense array of peptides on liposomes induced peptide-specific IgG responses totally independent of T-cell help. Independency was confirmed in mice lacking T cells and in mice deficient for MHC class II, CD40L, and CD28. The IgG titers were high, long-lived, and comparable with titers obtained in wild-type animals, and the antibody response was associated with germinal center formation, expression of activation-induced cytidine deaminase, and affinity maturation. The T cell-independent (TI) IgG response was strictly dependent on ligation of TLR4 receptors on B cells, and concomitant TLR4 and cognate B-cell receptor stimulation was required on a single-cell level. Surprisingly, the IgG class switch was mediated by TIR-domain-containing adapter inducing interferon-β (TRIF), but not by MyD88. This study demonstrates that peptides can induce TI isotype switching when antigen and TLR ligand are assembled and appropriately presented directly to B lymphocytes. A TI vaccine could enable efficient prophylactic and therapeutic vaccination of patients with T-cell deficiencies and find application in diseases where induction of T-cell responses contraindicates vaccination, for example, in Alzheimer disease.
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Stevens FJ, Bobrovnik SA. Deconvolution of antibody affinities and concentrations by non-linear regression analysis of competitive ELISA data. J Immunol Methods 2007; 328:53-8. [PMID: 17884083 DOI: 10.1016/j.jim.2007.08.007] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2007] [Revised: 07/26/2007] [Accepted: 08/02/2007] [Indexed: 10/22/2022]
Abstract
Physiological responses of the adaptive immune system are polyclonal in nature whether induced by a naturally occurring infection, by vaccination to prevent infection or, in the case of animals, by challenge with antigen to generate reagents of research or commercial significance. The composition of the polyclonal responses is distinct to each individual or animal and changes over time. Differences exist in the affinities of the constituents and their relative proportion of the responsive population. In addition, some of the antibodies bind to different sites on the antigen, whereas other pairs of antibodies are sterically restricted from concurrent interaction with the antigen. Even if generation of a monoclonal antibody is the ultimate goal of a project, the quality of the resulting reagent is ultimately related to the characteristics of the initial immune response. It is probably impossible to quantitatively parse the composition of a polyclonal response to antigen. However, molecular regression allows further parameterization of a polyclonal antiserum in the context of certain simplifying assumptions. The antiserum is described as consisting of two competing populations of high- and low-affinity and unknown relative proportions. This simple model allows the quantitative determination of representative affinities and proportions. These parameters may be of use in evaluating responses to vaccines, to evaluating continuity of antibody production whether in vaccine recipients or animals used for the production of antisera, or in optimizing selection of donors for the production of monoclonal antibodies.
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Affiliation(s)
- F J Stevens
- Biosciences Division, Argonne National Laboratory, Argonne, IL 60439, USA.
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