A novel anti-TNF scFv constructed with human antibody frameworks and antagonistic peptides

A cell-based subtractive panning strategy for selection of conformation-specific single-chain variable-fragment (scFv) against dimerization domain of EGFR

BACKGROUND AND OBJECTIVE

Overexpression of EGFR, a member of the ErbB receptor family, has been observed in several cancers and causes resistance to therapeutic antibodies, such as Herceptin. In this study, we produced a recombinant single-chain variable fragment (scFv) antibody against the EGFR dimerization domain.

METHODS

The recombinant scFv was generated using a cell-based subtractive panning strategy. Subtractive panning was performed on a genetically engineered, VERO/EGFR, cells as well as a triple-negative breast cancer, MDA-MB-468, cells. Phage cell-ELISA was used to monitor the binding of the selected scFvs to the dimerization domain of EGFR. Inhibition of EGFR and HER2 dimerization by the produced scFvs were finally evaluated using the dimerization inhibition test and the expression of apoptosis-related genes were measured using the quantitative RT-PCR.

RESULTS

PCR fingerprinting results showed a uniform digestion pattern following the third round of panning that confirmed the success of subtractive panning. Moreover, cell-ELISA validated the reactivity of the produced scFvs to EGFR following stimulation with EGF. Dimerization inhibition test showed the capacity of the scFvs to inhibit EGFR and HER2 dimerization. Investigation of apoptosis-related genes showed that treatment with the scFv antibody caused increased Bax and decreased Bcl2 expression.

CONCLUSIONS

Directed HER2 targeting was shown to be effective enough to block the functional domain of the cell receptor and its intracellular signaling pathway. The subtractive panning strategy used in this study could control the process of directed selection of specific antibodies against the dimerization domain of EGFR. Selected antibodies might then be functionally tested for antitumor effects in both in vitro and in vivo studies.

A mechanistic perspective, clinical applications, and phage-display-assisted discovery of TNFα inhibitors

TNFα participates in a variety of physiological processes, but at supra-physiological concentrations it has been implicated in the pathology of inflammatory and autoimmune diseases. Therefore, much attention has been devoted to the development of strategies that overcome the effects of aberrant TNFα concentration. Promising strategies include drugs that destabilize the active (trimeric) form of TNFα and antagonists of TNFα receptor type I. Underpinning these strategies is the successful application of phage-display technology to identify anti-TNFα peptides and antibodies. Here, we review the development of inhibitors of the TNFα-TNF receptor system, with particular focus on the phage-display-assisted identification of molecules that interfere with this system by acting as inhibitors of TNFα or by sequestering TNFα away from its receptor.

Characterization of Novel Fragment Antibodies Against TNF-alpha Isolated Using Phage Display Technique

Tumor necrosis factor alpha (TNF-α) is an inflammatory cytokine which plays crucial roles in pathogenesis of inflammatory diseases. The current study aimed to investigate the binding abilities of I44 and I49 domain antibodies to TNF-α. The dAbs were expressed in bacterial expression system and purified by affinity chromatography using Ni-sepharose column. The expression and purity of the proteins were evaluated using western blotting and SDS-PAGE techniques, respectively. ELISA experiment showed that I44 and I49 dAbs bind to TNF-α with the binding constants (K_d) of 5.18 ± 1.41 and 2.42 ± 0.55 µM, respectively. The inhibitory effect of dAbs on TNF-α biological effect was determined in MTT assay in which I44 and I49 prevented TNF-α cell cytotoxicity with IC₅₀ values of 6.61 and 3.64 µM, respectively. The identified anti-TNF-α dAbs could bind to and inhibit TNF-α activity. The dAbs activities can be attributed to their ability to establish hydrogen bonds as well as hydrophobic contacts with TNF-α. The results of the current study can pave the way for further structural studies in order to introduce new more potent anti-TNF-α antibodies.

Designing antibody against highly conserved region of dengue envelope protein by in silico screening of scFv mutant library

Dengue being one of the deadliest diseases of tropical regions, enforces to put continuous efforts for the development of vaccine and effective therapeutics. Most of the antibodies generated during dengue infection are non-neutralizing and cause antibody dependent enhancement. Hence, making a potent neutralizing antibody against all four dengue serotypes could be very effective for the treatment. However, designing a single antibody for all serotypes is difficult due to variation in protein sequences. Therefore, the objective is to identify conserved region of dengue envelope protein and then develop an antibody against that conserved region. Before advancing to the development of such an antibody, it is desirable to validate the interactions between antibody and dengue envelope protein. In silico analysis of such interactions provides a good platform to find out a suitable region to design and construct an antibody against it by analyzing antigen-antibody interaction before synthesizing the antibody. In this study, two highly conserved regions of dengue envelope protein were identified and an scFv was constructed against it. Both scFv and FuBc proteins were expressed in bacterial expression system and binding efficiency was analyzed by SPR analysis with KD value 2.3 μM. In order to improve binding efficiency, an in silico scFv mutant library was created which was virtually screened for higher binding efficiency. Six mutants with high binding efficiency were selected for further analysis. The binding ability of these mutants were predicted using simulation analysis which shows these mutations were stabilizing scFv-FuBc complex.

Computer-aided design of short peptide ligands targeting tumor necrosis factor-alpha for adsorbent applications

A peptide ligand (T1: Ac-RKEM-NH₂) designed by a computer-aided method can enhance TNF-α adsorption from the plasma of rats with sepsis to PVA.