Development of a recombinant camelid specific diabody against the heminecrolysin fraction of Hemiscorpius lepturus scorpion

Use of Albumin for Drug Delivery as a Diagnostic and Therapeutic Tool

Drug delivery is an important topic that has attracted the attention of researchers in recent years. Albumin nanoparticles play a significant role in drug delivery as a carrier due to their unique characteristics. Albumin is non-toxic, biocompatible, and biodegradable. Its structure is such that it can interact with different drugs, which makes the treatment of the disease faster and also reduces the side effects of the drug. Albumin nanoparticles can be used in the diagnosis and treatment of many diseases, including cancer, diabetes, Alzheimer's, etc. These nanoparticles can connect to some compounds, such as metal nanoparticles, antibodies, folate, etc. and create a powerful nanostructure for drug delivery. In this paper, we aim to investigate albumin nanoparticles in carrier format for drug delivery application. In the beginning, different types of albumin and their preparation methods were discussed, and then albumin nanoparticles were discussed in detail in diagnosing and treating various diseases.

Targeting of human fibroblast growth factor receptor 2 by a novel specific nanobody

Inhibition of FGFR2 signaling is promising in targeted therapy of FGFR2-related tumors. In this study, anti-FGFR2 nanobodies (Nbs) were isolated through screening of an immune camelid phage display library. Four rounds of biopanning were carried out with commercial human FGFR2 antigen and enrichment was assessed by ELISA and phage titration. The gene of Nb was sub-cloned into the expression vector, and the recombinant vector was transformed into Escherichia coli WK6 cells. The recombinant protein was purified using Ni-NTA affinity chromatography. The anti-FGFR2 Nb (C13) was characterized by SDS-PAGE, western blotting, competitive inhibition ELISA, flow cytometry, MTT, and migration assay. C13 Nb recognized FGFR2 with high specificity and no cross-reactivity was observed with other tested antigens. The affinity of C13 Nb was calculated to be 1.5 × 10-9 M. Results of cytotoxicity showed that C13 Nb (10 µg/ml) inhibited 85% of the proliferation of T-47D cells (p < 0.001). In addition, C13 inhibited the migration of 68% of T-47D toward the source of the growth factor (p < 0.01). The flow cytometry showed that C13 Nb bound to the surface of FGFR2+ cells, T-47D cell line (96%). Results indicate the potential of anti-FGFR2 Nb for targeted therapy of FGFR2-overexpressing tumors after complementary investigations.

A Novel Immunotoxin Targeting Epithelial Cell Adhesion Molecule Using Single Domain Antibody Fused to Diphtheria Toxin

Epithelial Cell Adhesion Molecule (EpCAM) is overexpressed in a variety of cancers such as colon, stomach, pancreas, and prostate adenocarcinomas. Inhibition of EpCAM is considered as a potential target for cancer therapy. In current study, anti-EpCAM immunotoxin (α-EpCAM IT) was developed using genetic fusion of α-EpCAM single domain antibody (nanobody) (α-EpCAM Nb) to truncated form of diphtheria toxin. The expression of recombinant α-EpCAM IT was induced by Isopropyl β-d-1-thiogalactopyranoside (IPTG) and confirmed by SDS-PAGE and western blot. Recombinant α-EpCAM IT was purified from the inclusion bodies and refolded using urea gradient procedure. The cytotoxicity and apoptosis activity of α-EpCAM IT on EpCAM over-expressing (MCF7), low-expressing (HEK293), and no-expressing (HUVEC) cells were evaluated by 3-4,5-Dimethylthiazol-2-yl (MTT) assay and annexin V-FITC-PI assay as well. In addition, anti-tumor activity of α-EpCAM IT was evaluated on nude mice bearing MCF7 tumor cells. Results showed success expression and purification of α-EpCAM IT. The α-EpCAM IT showed time and dose-dependent anti-proliferative activity on MCF-7 cells. However, α-EpCAM IT did not show any anti-proliferative activity on HEK293 and HUVEC cells as well. In addition, the annexin V-FITC-PI assay results showed that α-EpCAM IT significantly increased apoptotic rate in MCF-7 cells with no effect on HEK293 and HUVEC as well. Moreover, α-EpCAM IT significantly reduced tumor size in vivo study. The achieved results indicate the potential of designing α-EpCAM IT as a novel therapeutic for cancer therapy.

Investigation of the therapeutic potential of recombinant bispecific bivalent anti-PD-L1/VEGF nanobody in inhibition of angiogenesis

Immunotherapy's using monoclonal antibodies targeting programmed death ligand-1 (PD-L1) on cancer cells as a biomarker of escape from response to immune checkpoint has demonstrated efficacy in treating many solid tumors. In addition, some of the signals, such as vascular endothelial growth factor (VEGF), bind to receptors on the surface of normal endothelial cells and encourage angiogenesis, or the formation and survival of new blood vessels. Due to the special features of nanobodies with high specificity and affinity as a powerful new tool in cancer therapy, here, a recombinant bispecific bivalent anti-PD-L1/VEGF nanobody was constructed and its functionality in inhibition of angiogenesis in vitro was investigated. Results demonstrated that bivalent anti-PD-L1/VEGF nanobody efficiently inhibited HUVEC and A431 cells proliferation and tube formation. In addition, bivalent anti-PD-L1/VEGF nanobody efficiently inhibited angiogenesis in an ex ovo Chick Chorioallantoic Membrane assay. The results indicate for the potential of bivalent anti-PD-L1/VEGF nanobody as a novel promising tool for cancer therapy.

Effective blocking of neuropilin-1activity using oligoclonal nanobodies targeting different epitopes

Neuropilin-1 (NRP-1) is a non-tyrosine kinase receptor and when overexpressed, leads to angiogenesis. High expression of NRP-1 has been observed in various cancers. Unique characteristic of nanobodies (small size, high affinity and stability, and ease production) make them potential therapeutic tools. Oligoclonal nanobodies which detect multiple functional epitopes on the target antigen could be potential tools for inhibition of cancer resistance problems due to escape variant of tumor cells. In this study, oligoclonal anti-NRP-1 nanobodies were selected from camel immune library and their binding activities as well as in vitro functionality were evaluated. Anti-NRP-1 nanobodies were expressed in an Escherichia coli host, and purified using nickel affinity chromatography. The effect of each individual and oligoclonal nanobodies on human endothelial cells were evaluated by MTT, Tube formation, and migration assay as well. Results showed that oligoclonal anti-NRP-1 nanobodies detected different epitopes of NRP-1 antigen and inhibited in vitro angiogenesis of human endothelial cells better than each individual nanobody. Results indicate promising oligoclonal anti-NRP-1 nanobodies for inhibition of angiogenesis.

Targeted therapy of angiogenesis using anti-VEGFR2 and anti-NRP-1 nanobodies

PURPOSE

Targeted therapy in cancer researches is a promising approach that can resolve drawbacks of systematic therapeutics. Nanobodies are potent therapeutics due to their high specificity and affinity to the target.

METHODS

In this study, we evaluated the effect of the combination of anti-vascular endothelial growth factor receptor 2 (anti-VEGFR2) and anti-neuropilin-1 (anti-NRP1) nanobodies both in vitro (MTT, and tube formation assay) and in vivo (chick chorioallantoic membrane (CAM), and Nude mice treatment assay).

RESULTS

Our results showed that the combination of two nanobodies (anti-VEGFR2/NRP-1 nanobodies) significantly inhibited proliferation as well as tube formation of human endothelial cells effective than a single nanobody. In addition, the mixture of both nanobodies inhibited vascularization of chick chorioallantoic membrane ex ovo CAM assay as compared to a single nanobody. Moreover, the mixture of both nanobodies significantly inhibited tumor growth of the mice (tumor volume and weight) higher than individual nanobodies (P < 0.05).

CONCLUSION

Our results offer a promising role of combination therapies in cancer therapy as well as angiogenesis.

Inhibition of neovascularisation in human endothelial cells using anti NRP-1 nanobody fused to truncated form of diphtheria toxin as a novel immunotoxin

Neuropilin-1 (NRP-1) regulates a range of physiological and pathological processes, including angiogenesis. Targeting of NRP1 is considered a significant approach in cancer therapy. In the present study, a novel antiNRP1 immunotoxin (αNRP1 IT) was developed by genetic fusion of a single domain (VHH) anti-NRP-1 antibody fragment to a truncated diphtheria toxin. The αNRP1 IT was expressed into bacterial cells as an inclusion body (IB). Expression of αNRP1 IT was confirmed by SDS-PAGE and western blotting. Recombinant αNRP1 IT was purified using nickel affinity chromatography. Toxicity and antiangiogenesis effect of αNRP1 IT was investigated both in vitro and in vivo. Results showed that αNRP1 IT significantly reduced the viability of human umbilical vein endothelial cell line (HUVEC) (p < .05). The αNRP1 IT significantly inhibited tube formation of HUVEC cells (p < .001). Furthermore, αNRP1 IT inhibited angiogenesis in Chick Chorioallantoic Membrane (CAM) Assay. These data suggest the potential of αNRP1 IT as a novel therapeutic in targeted cancer therapy.

Nanobodies: The "Magic Bullets" in therapeutics, drug delivery and diagnostics

Antibodies represent a well-established class of clinical diagnostics for medical applications as well as essential research and biotechnological tools. Although both polyclonal and monoclonal antibodies are indispensable reagents in basic research and diagnostics but both of them have their limitations. Hence, there is urgent need to develop strategies aimed at production of alternative scaffolds and recombinant antibodies of smaller dimensions that could be easily produced, selected and manipulated. Unlike conventional antibodies, members of Camelidae and sharks produce antibodies composed only of heavy chains with small size, high solubility, thermal stability, refolding capacity and good tissue penetration in vivo. The discovery of these naturally occurring antibodies having only heavy-chain in Camelidae family and their further development into small recombinant nanobodies represents an attractive alternative in drug delivery, diagnostics and imaging. Nanobody derivatives are soluble, stable, versatile, have unique refolding capacities, reduced aggregation tendencies and high-target binding capabilities. They can be genetically customized to target enzymes, transmembrane proteins or molecular interactions. Their ability to recognize recessed antigenic sites has been attributed to their smaller size and the ability of the extended CDR3 loop to quickly penetrate into such epitopes. With the advent of molecular engineering and phage display technology, they can be of potential use in molecular imaging, drug delivery and therapeutics for several major diseases. In this review we present the recent advances in nanobodies for modulating immune functions, for targeting cancers, viruses, toxins and microbes as well as their utility as diagnostic and biosensor tools.

Isolation and characterization of nanobodies against epithelial cell adhesion molecule as novel theranostic agents for cancer therapy

Epithelial cell adhesion molecule (EpCAM) plays an important role in tumorigenesis. Camelids produce functional antibodies composed of heavy chains only that bind to their antigens via a single domain variable fragment known as nanobody. Nanobodies show multiple advantages over traditional monoclonal antibodies. Isolation of functional anti-EpCAM nanobodies (Nbs) was the main aim of this study. An immune nanobody library containing 10⁸ members was constructed previously. Anti -EpCAM nanobodies were isolated from camel immune library using phage display. Four consecutive rounds of biopanning were performed on immobilized EpCAM. Four nanobodies (Nb4, Nb5, Nb22, and Nb23) with highest signal intensity in monoclonal phage ELISA were selected. Affinity of these selected nanobodies for EpCAM was in the nanomolar range. Selected nanobodies significantly inhibited proliferation of MCF-7 cells. The in vivo study revealed that a significant reduction in tumor size occurred when treated with nanobodies Nb4 and Nb5, after 14 days monitoring. Our data revealed that nanobodies Nb4 and Nb5 could be considered as attractive theranostic agents for EpCAM overexpressing cancers.

Development of a mono-specific anti-VEGF bivalent nanobody with extended plasma half-life for treatment of pathologic neovascularization

Vascular endothelial growth factor (VEGF) plays a crucial role in angiogenesis within solid cancers. Thus, targeting VEGF might be part of a feasible therapy for treating pathological neovascularization, and nanobodies - derived from heavy chain-only antibodies occurring within Camelidae - are a novel class of nanometer-sized antibodies possessing unique properties that could be developed into a promising therapeutic. However, nanobodies have a very short half-life in vivo due to their small size. Development of a bivalent nanobody is one way to remediate the half-life problem of nanobodies. Two identical anti-VEGF nanobodies were connected using the hinge region of llama IgG2c. The recombinant plasmid (pHEN6c-bivalent nanobody) was transformed into E.coli WK6 cells and expression of the bivalent nanobody construct was induced with 1mM Isopropyl β-D-1-thiogalactopyranoside (IPTG). Recombinant bivalent nanobody was purified using nickel affinity chromatography and its activity on human endothelial cells was assessed using 3-(4,5-Dimethylthiazol-2-yr)-2,5-diphenyltetrazolium bromide (MTT), tube formation, and cell migration assays. The pharmacokinetic study was performed after intravenous (i.v.) injection of recombinant bivalent nanobody into six-week-old C57BL/6 mice. Recombinant bivalent nanobody performed significantly better than monovalent nanobody in inhibiting proliferation, tube formation, and migration of human endothelial cells. Pharmacokinetic results showed a 1.8-fold longer half-life of bivalent nanobody in comparison with the monovalent nanobody. These results underscore the potential of recombinant anti-VEGF bivalent nanobody as a promising tool for development of a novel therapeutic with an extended plasma half-life for VEGF-related diseases.

Serotherapy against Voltage-Gated Sodium Channel-Targeting αToxins from Androctonus Scorpion Venom

Because of their venom lethality towards mammals, scorpions of the Androctonus genus are considered a critical threat to human health in North Africa. Several decades of exploration have led to a comprehensive inventory of their venom components at chemical, pharmacological, and immunological levels. Typically, these venoms contain selective and high affinity ligands for the voltage-gated sodium (Na_v) and potassium (K_v) channels that dictate cellular excitability. In the well-studied Androctonus australis and Androctonus mauretanicus venoms, almost all the lethality in mammals is due to the so-called α-toxins. These peptides commonly delay the fast inactivation process of Na_v channels, which leads to increased sodium entry and a subsequent cell membrane depolarization. Markedly, their neutralization by specific antisera has been shown to completely inhibit the venom’s lethal activity, because they are not only the most abundant venom peptide but also the most fatal. However, the structural and antigenic polymorphisms in the α-toxin family pose challenges to the design of efficient serotherapies. In this review, we discuss past and present accomplishments to improve serotherapy against Androctonus scorpion stings.

Nanobodies as novel therapeutic agents in envenomation

BACKGROUND

An effective therapy against envenoming should be a priority in view of the high number scorpion stings and snakebites. Serum therapy is still widely applied to treat the envenomation victims; however this approach suffers from several shortcomings. The employment of monoclonal antibodies might be an outcome as these molecules are at the core of a variety of applications from protein structure determination to cancer treatment. The progress of activities in the twilight zone between genetic and antibody engineering have led to the development of a unique class of antibody fragments. These molecules possess several benefits and lack many possible disadvantages over classical antibodies. Within recombinant antibody formats, nanobodies or single domain antigen binding fragments derived from heavy chain only antibodies in camelids occupy a privileged position.

SCOPE OF REVIEW

In this paper we will briefly review the common methods of envenomation treatment and focus on details of various in vivo research activities that investigate the performance of recombinant, monoclonal nanobodies in venom neutralization.

MAJOR CONCLUSIONS

Nanobodies bind to their cognate target with high specificity and affinity, they can be produced in large quantities from microbial expression systems and are very robust even when challenged with harsh environmental conditions. Upon administering, they rapidly distribute throughout the body and seem to be well tolerated in humans posing low immunogenicity.

GENERAL SIGNIFICANCE

Scorpion and snake envenomation is a major issue in developing countries and nanobodies as a venom-neutralizing agent can be considered as a valuable and promising candidate in envenomation therapy.