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Microbiology Spectrum Apr 2014A brief outline of antibody structure is followed by highlights from several recently determined crystal structures of human, antiviral Fabs. These Fabs all have novel... (Review)
Review
A brief outline of antibody structure is followed by highlights from several recently determined crystal structures of human, antiviral Fabs. These Fabs all have novel structural features that allow them to potently and broadly neutralize their targets.
Topics: Animals; Antibodies; Humans; Immunoglobulin Fab Fragments; Models, Molecular; Protein Conformation
PubMed: 26105818
DOI: 10.1128/microbiolspec.AID-0012-2013 -
Rheumatology (Oxford, England) Nov 2021To evaluate the dose-response, efficacy and safety of dapirolizumab pegol (DZP) in patients with SLE. (Observational Study)
Observational Study Randomized Controlled Trial
OBJECTIVE
To evaluate the dose-response, efficacy and safety of dapirolizumab pegol (DZP) in patients with SLE.
METHODS
Adults with moderately to severely active SLE (SLEDAI-2K score ≥6 and ≥1 BILAG A or ≥2 BILAG B domain scores), receiving stable CS (≤40 mg/day prednisone-equivalent), antimalarial or immunosuppressant drugs were included. Patients with stable LN (proteinuria ≤2 g/day) not receiving high-dose CS or CYC were permitted entry. Randomized patients received placebo or i.v. DZP (6/24/45 mg/kg) and standard-of-care (SOC) treatment every 4 weeks to week 24, after which patients received only SOC to week 48. The primary objective was to establish a dose-response relationship based on week 24 BILAG-Based Composite Lupus Assessment (BICLA) responder rates.
RESULTS
All DZP groups exhibited improvements in clinical and immunological outcomes vs placebo at week 24; however, BICLA responder rates did not fit pre-specified dose-response models [best-fitting model (Emax): P = 0.07]. Incidences of serious treatment-emergent adverse events across DZP groups were low and similar to placebo. Following DZP withdrawal, SLEDAI-2K, physician's global assessment (PGA), BILAG, and Cutaneous Lupus Erythematosus Disease Area and Severity Index (CLASI) scores stabilized; BICLA and SLE Responder Index (SRI-4) responder rates declined (likely due to interventions with disallowed escape medications), BILAG flares increased, and immunologic parameters returned towards baseline.
CONCLUSIONS
Although the primary objective was not met, DZP appeared to be well tolerated, and patients exhibited improvements across multiple clinical and immunological measures of disease activity after 24 weeks relative to placebo. The potential clinical benefit of DZP warrants further investigation.
Topics: Adult; Dose-Response Relationship, Drug; Double-Blind Method; Female; Humans; Immunoglobulin Fab Fragments; Lupus Erythematosus, Systemic; Male; Middle Aged; Polyethylene Glycols; Treatment Outcome
PubMed: 33956056
DOI: 10.1093/rheumatology/keab381 -
Science (New York, N.Y.) Mar 2014Complement activation by antibodies bound to pathogens, tumors, and self antigens is a critical feature of natural immune defense, a number of disease processes, and...
Complement activation by antibodies bound to pathogens, tumors, and self antigens is a critical feature of natural immune defense, a number of disease processes, and immunotherapies. How antibodies activate the complement cascade, however, is poorly understood. We found that specific noncovalent interactions between Fc segments of immunoglobulin G (IgG) antibodies resulted in the formation of ordered antibody hexamers after antigen binding on cells. These hexamers recruited and activated C1, the first component of complement, thereby triggering the complement cascade. The interactions between neighboring Fc segments could be manipulated to block, reconstitute, and enhance complement activation and killing of target cells, using all four human IgG subclasses. We offer a general model for understanding antibody-mediated complement activation and the design of antibody therapeutics with enhanced efficacy.
Topics: Cell Membrane; Complement Activation; Complement C1; Humans; Immunoglobulin Fab Fragments; Immunoglobulin G; Liposomes; Protein Conformation; Protein Multimerization
PubMed: 24626930
DOI: 10.1126/science.1248943 -
Methods in Molecular Biology (Clifton,... 2021We studied the molecular details of the recognition of antigens by the variable domain of their cognate antibodies in as well as those elicited by the constant domains,...
We studied the molecular details of the recognition of antigens by the variable domain of their cognate antibodies in as well as those elicited by the constant domains, which do not directly interact with antigens. Such effects are difficult to study experimentally; however, molecular dynamics simulations and subsequent residue interaction network analysis provide insight into the allosteric communication between the antigen-binding CDR region and the constant domain. We performed MD simulations of the complex of Fab and prion-associated peptide in the apo and bound forms and follow the conformational changes in the antibody and cross-talk between its subunits and with antigens. These protocols could be generally applied for studies of other antigens-antibody recognition systems.
Topics: Allosteric Regulation; Allosteric Site; Animals; Binding Sites, Antibody; Crystallography, X-Ray; Humans; Immunoglobulin Fab Fragments; Models, Molecular; Molecular Dynamics Simulation; Prions; Protein Binding
PubMed: 33315224
DOI: 10.1007/978-1-0716-1154-8_11 -
Journal of Immunology (Baltimore, Md. :... Feb 2016Human IgG is the most abundant glycoprotein in serum and is crucial for protective immunity. In addition to conserved IgG Fc glycans, ∼15-25% of serum IgG contains... (Review)
Review
Human IgG is the most abundant glycoprotein in serum and is crucial for protective immunity. In addition to conserved IgG Fc glycans, ∼15-25% of serum IgG contains glycans within the variable domains. These so-called "Fab glycans" are primarily highly processed complex-type biantennary N-glycans linked to N-glycosylation sites that emerge during somatic hypermutation. Specific patterns of Fab glycosylation are concurrent with physiological and pathological conditions, such as pregnancy and rheumatoid arthritis. With respect to function, Fab glycosylation can significantly affect stability, half-life, and binding characteristics of Abs and BCRs. Moreover, Fab glycans are associated with the anti-inflammatory activity of IVIgs. Consequently, IgG Fab glycosylation appears to be an important, yet poorly understood, process that modulates immunity.
Topics: Arthritis, Rheumatoid; Female; Glycosylation; Humans; Immunoglobulin Fab Fragments; Immunoglobulin G; Polysaccharides; Pregnancy
PubMed: 26851295
DOI: 10.4049/jimmunol.1502136 -
Clinical and Experimental Immunology Dec 2014Although intravenous immunoglobulin (IVIg) is widely used for replacement therapy in immunodeficiencies and to treat autoimmune and inflammatory diseases, its mechanisms...
Although intravenous immunoglobulin (IVIg) is widely used for replacement therapy in immunodeficiencies and to treat autoimmune and inflammatory diseases, its mechanisms of action are not fully understood. Examination of immunoglobulin (Ig) receptors, including the Fc-gamma receptors (FCγRs) and the neonatal Fc receptor, have revealed genetic variations that are linked to autoimmune diseases and to the efficacy of IVIg treatment. However, the beneficial effect of IVIg encompasses multiple mechanisms of action. One of these is scavenging of activated complement fragments, such as C3a, C5a, C3b and C4b, by infused Ig molecules. This interaction prevents binding of complement fragments to their receptors on target cells, thus attenuating the immune damage. Additionally, anti-inflammatory effects may be facilitated by IgA via specific receptors and/or complement scavenging. Glycosylation of both the Fc- and Fab-fragments has also been implicated in the anti-inflammatory action of IVIg. Although there is evidence to support a role for sialylated IgG glycovariants in mediating the effect of IVIg, evidence from animal models of inflammatory disease suggest that sialylation may not be a critical factor. However, an increase in IgG glycosylation has been observed following IVIg treatment in Guillain-Barré syndrome patients, and this has been associated with improved clinical outcomes.
Topics: Anti-Inflammatory Agents; Autoimmune Diseases; Complement Activation; Complement System Proteins; Glycosylation; Humans; Immunoglobulin Fab Fragments; Immunoglobulin Fc Fragments; Immunoglobulin G; Immunoglobulins, Intravenous; Immunologic Deficiency Syndromes; Receptors, IgG
PubMed: 25546774
DOI: 10.1111/cei.12523 -
Nature Aug 2018The olfactory system must recognize and discriminate amongst an enormous variety of chemicals in the environment. To contend with such diversity, insects have evolved a...
The olfactory system must recognize and discriminate amongst an enormous variety of chemicals in the environment. To contend with such diversity, insects have evolved a family of odorant-gated ion channels comprised of a highly conserved co-receptor (Orco) and a divergent odorant receptor (OR) that confers chemical specificity. Here, we present the single-particle cryo-electron microscopy structure of an Orco homomer from the parasitic fig wasp Apocrypta bakeri at 3.5 Å resolution, providing structural insight into this receptor family. Orco possesses a novel channel architecture, with four subunits symmetrically arranged around a central pore that diverges into four lateral conduits that open to the cytosol. The Orco tetramer has few inter-subunit interactions within the membrane and is bound together by a small cytoplasmic anchor domain. The minimal sequence conservation among ORs maps largely to the pore and anchor domain, shedding light on how the architecture of this receptor family accommodates its remarkable sequence diversity and facilitates the evolution of odour tuning.
Topics: Amino Acid Motifs; Animals; Binding Sites; Conserved Sequence; Cryoelectron Microscopy; Hydrophobic and Hydrophilic Interactions; Immunoglobulin Fab Fragments; Insecta; Ion Channel Gating; Models, Molecular; Phylogeny; Protein Multimerization; Protein Structure, Quaternary; Receptors, Odorant; Sequence Alignment
PubMed: 30111839
DOI: 10.1038/s41586-018-0420-8 -
Acta Crystallographica. Section F,... Dec 2017Meditope, a cyclic 12-residue peptide, binds to a unique binding side between the light and heavy chains of the cetuximab Fab. In an effort to improve the affinity of...
Meditope, a cyclic 12-residue peptide, binds to a unique binding side between the light and heavy chains of the cetuximab Fab. In an effort to improve the affinity of the interaction, it was sought to extend the side chain of Arg8 in the meditope, a residue that is accessible from the other side of the meditope binding site, in order to increase the number of interactions. These modifications included an n-butyl and n-octyl extension as well as hydroxyl, amine and carboxyl substitutions. The atomic structures of the complexes and the binding kinetics for each modified meditope indicated that each extension threaded through the Fab `hole' and that the carboxyethylarginine substitution makes a favorable interaction with the Fab, increasing the half-life of the complex by threefold compared with the unmodified meditope. Taken together, these studies provide a basis for the design of additional modifications to enhance the overall affinity of this unique interaction.
Topics: Arginine; Binding Sites; Cetuximab; Crystallography, X-Ray; Half-Life; Hydrogen Bonding; Immunoglobulin Fab Fragments; Models, Molecular; Peptides, Cyclic; Protein Conformation; Static Electricity; Structure-Activity Relationship; Surface Plasmon Resonance
PubMed: 29199990
DOI: 10.1107/S2053230X17016272 -
MAbs 2023T-cell-engaging bispecific antibodies (T-bsAbs) are promising immunotherapies for cancer treatment due to their capability of redirecting T-cells toward destroying tumor...
T-cell-engaging bispecific antibodies (T-bsAbs) are promising immunotherapies for cancer treatment due to their capability of redirecting T-cells toward destroying tumor cells. Numerous T-bsAb formats have been developed, each with advantages and disadvantages in terms of developability, immunogenicity, effector functions, and pharmacokinetics. Here, we systematically compared T-bsAbs produced using eight different formats, evaluating the effect of molecular design of T-bsAbs on their manufacturability and functionality. These eight T-bsAb formats were constructed using antigen-binding fragments (Fabs) and single-chain variable fragments (scFvs) of antibodies linked to the crystallizable fragment (Fc) domain of immunoglobulin G. To ensure a fair comparison of growth and production data, we used recombinase-mediated cassette exchange technology to generate the T-bsAb-producing CHO cell lines. The produced T-bsAbs were assessed for their purification profile and recovery, binding capability, and biological activities. Our findings indicated that the manufacturability of bsAbs was adversely affected with increased number of scFv building blocks, while the functionality was affected by the combination of multiple factors, including the binding affinity and avidity of targeting moieties and the flexibility and geometry of formats. These results provide valuable insights into the impact of the format design on the optimal production and function of T-bsAbs.
Topics: Antibodies, Bispecific; T-Lymphocytes; Immunoglobulin Fab Fragments; Immunoglobulin G; Single-Chain Antibodies
PubMed: 37403264
DOI: 10.1080/19420862.2023.2231129 -
International Journal of Molecular... Sep 2020Recent years have shown a tremendous increase and diversification in antibody-based therapeutics with advances in production techniques and formats. The plethora of... (Review)
Review
Recent years have shown a tremendous increase and diversification in antibody-based therapeutics with advances in production techniques and formats. The plethora of currently investigated bi- to multi-specific antibody architectures can be harnessed to elicit a broad variety of specific modes of actions in oncology and immunology, spanning from enhanced selectivity to effector cell recruitment, all of which cannot be addressed by monospecific antibodies. Despite continuously growing efforts and methodologies, the identification of an optimal bispecific antibody as the best possible combination of two parental monospecific binders, however, remains challenging, due to tedious cloning and production, often resulting in undesired extended development times and increased expenses. Although automated high throughput screening approaches have matured for pharmaceutical small molecule development, it was only recently that protein bioconjugation technologies have been developed for the facile generation of bispecific antibodies in a 'plug and play' manner. In this review, we provide an overview of the most relevant methodologies for bispecific screening purposes-the DuoBody concept, paired light chain single cell production approaches, Sortase A and Transglutaminase, the SpyTag/SpyCatcher system, and inteins-and elaborate on the benefits as well as drawbacks of the different technologies.
Topics: Animals; Antibodies, Bispecific; High-Throughput Screening Assays; Humans; Immunoglobulin Fab Fragments; Immunoglobulin G; Protein Engineering
PubMed: 32911608
DOI: 10.3390/ijms21186551