Making cell-permeable antibodies (Transbody) through fusion of protein transduction domains (PTD) with single chain variable fragment (scFv) antibodies: potential advantages over antibodies expressed within the intracellular environment (Intrabody)

Selection of Functional Intracellular Nanobodies

Camelid-derived nanobodies are versatile tools for research, diagnostics, and therapeutics. Certain nanobodies can function as intrabodies and bind antigens within the eukaryotic cytosol. This capability is valuable for the development of intracellular probes and targeted gene therapies. Consequently, many attempts have been made to produce nanobodies that are intracellularly stable and resistant to aggregation. Pursuit of these intrabodies generally focuses on library design or nanobody selection method. Recent variations of library design have yielded diverse libraries capable of producing nanobodies against a wide variety of antigens. Novel screening methods have also been developed, yielding nanobodies with high affinity for intracellular antigens. These screening techniques can have advantages over phage display methods when nanobodies against intracellular antigens must be rapidly produced. Some intracellular screening methods convey the additional advantage of selecting for other desired intrabody characteristics, such as antiviral action or conditional stability. This review summarizes the recent developments in both library design and selection methods aimed at producing intrabodies.

Antibody Delivery for Intracellular Targets: Emergent Therapeutic Potential

Proteins have sparked fast growing interest as biological therapeutic agents for several diseases. Antibodies, in particular, carry an enormous potential as drugs owing to their remarkable target specificity and low immunogenicity. Although the market has numerous antibodies directed toward extracellular targets, their use in targeting therapeutically important intracellular targets is limited by their inability to cross cellular membrane. Realizing the potential for antibody therapy in disease treatment, progress has been made in the development of methods to deliver antibodies intracellularly. In this review, we address various platforms for delivery of antibodies and their merits and drawbacks.

Pharmacologic Characterization of ALD1910, a Potent Humanized Monoclonal Antibody against the Pituitary Adenylate Cyclase-Activating Peptide

Migraine is a debilitating disease that affects almost 15% of the population worldwide and is the first cause of disability in people under 50 years of age, yet its etiology and pathophysiology remain incompletely understood. Recently, small molecules and therapeutic antibodies that block the calcitonin gene-related peptide (CGRP) signaling pathway have reduced migraine occurrence and aborted acute attacks of migraine in clinical trials and provided prevention in patients with episodic and chronic migraine. Heterogeneity is present within each diagnosis and patient's response to treatment, suggesting migraine as a final common pathway potentially activated by multiple mechanisms, e.g., not all migraine attacks respond to or are prevented by anti-CGRP pharmacological interventions. Consequently, other unique mechanisms central to migraine pathogenesis may present new targets for drug development. Pituitary adenylate cyclase-activating peptide (PACAP) is an attractive novel target for treatment of migraines. We generated a specific, high-affinity, neutralizing monoclonal antibody (ALD1910) with reactivity to both PACAP38 and PACAP27. In vitro, ALD1910 effectively antagonizes PACAP38 signaling through the pituitary adenylate cyclase-activating peptide type I receptor, vasoactive intestinal peptide receptor 1, and vasoactive intestinal peptide receptor 2. ALD1910 recognizes a nonlinear epitope within PACAP and blocks its binding to the cell surface. To test ALD1910 antagonistic properties directed against endogenous PACAP, we developed an umbellulone-induced rat model of neurogenic vasodilation and parasympathetic lacrimation. In vivo, this model demonstrates that the antagonistic activity of ALD1910 is dose-dependent, retaining efficacy at doses as low as 0.3 mg/kg. These results indicate that ALD1910 represents a potential therapeutic antibody to address PACAP-mediated migraine.

Transbody against virus core protein potently inhibits hepadnavirus replication in vivo: evidence from a duck model of hepatitis B virus

BACKGROUND AND PURPOSE

The therapeutic management of hepatitis B virus (HBV) infections remains challenging, and novel antiviral strategies are urgently required. The HBV transbody, a monoclonal antibody (MAb) against human HBcAg coupled with the trans-activator of transcription protein transduction domain (TAT PTD), was previously shown to possess cell-penetrating ability and potent antiviral activity in vitro. The purpose of the present study was to evaluate the antiviral activity of the HBcMAb-TAT PTD conjugate in vivo in a duck model of HBV.

EXPERIMENTAL APPROACH

Female Peking ducks were injected i.p. with 0.03-0.3 mg·kg^-1 ·day^-1 of the DHBV transbody (DHBcMAb-TAT PTD conjugate) for 30 days. Serum DHBV DNA levels and liver DHBV DNA and covalently closed circular DNA (cccDNA) loads were determined at scheduled time points. Immunohistological examination of DHBcAg in the duck liver was also performed.

KEY RESULTS

The DHBV transbody significantly reduced the serum and liver DHBV DNA levels at doses of 0.1 and 0.3 mg·kg^-1 ·day^-1 and liver cccDNA levels at a dose of 0.3 mg·kg^-1 ·day^-1 after 30 days of treatment. The suppressive effects of the DHBV transbody at 0.3 mg·kg^-1 ·day^-1 on the serum and liver DHBV DNA and liver cccDNA levels remained significant, even at 15 days after treatment cessation. Similarly, immunohistochemistry of liver sections revealed decreased DHBcAg levels within hepatocytes 15 days after treatment termination.

CONCLUSIONS AND IMPLICATIONS

The DHBV transbody inhibits DHBV replication and possesses potent anti-DHBV activities in vivo. The cell-permeable antibody against the virus core antigen may be developed as a novel treatment for patients with hepadnavirus infections.

Small Molecules for Active Targeting in Cancer

For the purpose of this review, active targeting in cancer research encompasses strategies wherein a ligand for a cell surface receptor expressed on tumor cells is used to deliver a cytotoxic or imaging cargo. This area of research is more than two decades old, but in those 20 and more years, how many receptors have been studied extensively? What kinds of the ligands are used for active targeting? Are they mostly naturally occurring molecules such as folic acid, or synthetic substances developed in campaigns for medicinal chemistry efforts? This review outlines the most important receptor or ligand combinations that have been used in active targeting to answer these questions, and therefore to address the most important one of all: is research in active targeting affording diminishing returns, or is this an area for which the potential far exceeds progress made so far?

Photosensitizer and polycationic peptide-labeled streptavidin as a nano-carrier for light-controlled protein transduction

Transductions of exogenous proteins into cells enable the precise study of the effect of the transduced proteins on cellular functions. Accordingly, the protein transduction technique, which can control the release of proteins into the cytosol with certainty and high-throughput, is highly desired in various research fields. In this study, streptavidin (SA) labeled with a photosensitizer and cell-permeable peptides (CPP) was proposed as a nano-carrier for light-controlled protein transduction. SA was modified with biotinylated oligo-arginine peptides (Rpep), which were functionalized with Alexa Fluor 546 (AF546), to achieve cell penetrating and endosomal escape functionalities. The SA-Rpep complex was efficiently internalized into living HeLa cells corresponding to the length and the modification number of Rpep. SA conjugated with more than three equimolar AF546-modified Rpep consisting of fifteen arginine residues was achieved to diffuse throughout the cytosol without cytotoxicity by irradiation of the excitation light for AF546. The optimized nano-carrier was confirmed to transduce a biotinylated model cargo protein, enhanced green fluorescent protein fused with thioredoxin (tEGFP) into the cytosol at the light-irradiated area. The results provided proof-of-principle that SA possessing multiple AF546-modified Rpep has the potential to be a versatile and facile carrier for light-controlled protein transduction into the cytosol of mammalian cells.

Cell-penetrating peptides and their analogues as novel nanocarriers for drug delivery

INTRODUCTION

The impermeability of biological membranes is a major obstacle in drug delivery; however, some peptides have transition capabilities of biomembranes. In recent decades, cell-penetrating peptides (CPPs) have been introduced as novel biocarriers that are able to translocate into the cells. CPPs are biologically potent tools for non-invasive cellular internalization of cargo molecules. Nevertheless, the non-specificity of these peptides presents a restriction for targeting drug delivery; therefore, a peptidic nanocarrier sensitive to matrix metalloproteinase (MMP) has been prepared, called activatable cell-penetrating peptide (ACPP). In addition to the cell-penetrating peptide dendrimer (DCPP), other analogues of CPPs have been synthesized.

METHODS

In this study, the most recent literature in the field of biomedical application of CPPs and their analogues, ACPP and DCCP, were reviewed.

RESULTS

This review focuses on CPP and its analogues, ACPP and DCPP, as novel nanocarriers for drug delivery. In addition, nanoconjugates and bioconjugates of these peptide sequences are discussed.

CONCLUSION

DCCP, branched CPPs, compared to linear peptides have advantages such as resistance to rapid biodegradation, high loading capacities and large-scale production capability.

Transbody against hepatitis B virus core protein inhibits hepatitis B virus replication in vitro

Hepatitis B virus (HBV) infection is one of the major causes of chronic liver diseases. The current therapeutics show limited efficacy. In the HBV life cycle, virus core antigen (HBcAg) plays important multiple roles. Blocking the pleiotropic functions of HBcAg may thus represent a promising strategy for anti-HBV replication. In this study, monoclonal antibody (MAb) against core antigen of human HBV was coupled with TAT protein transduction domain (TAT PTD) to form transbody, and the effect on virus replication was evaluated in vitro. The HBV transbody, HBcMAb-TAT PTD conjugate, recognized HBcAg and retained cell-penetrating activity in living cells. In HBV-transfected liver cell line HepG2.2.15, HBV transbody suppressed not only the extracellular HBsAg, HBeAg and HBV DNA, but also the intracellular HBsAg, HBeAg, HBcAg and HBV DNA in a dose-dependent manner. These results indicate that the transbody prepared possesses readily cell-penetrating ability and potent antiviral activity, providing a novel approach, a cell-permeable antibody against HBcAg, for the treatment of HBV infection.

Single domain intrabodies against WASP inhibit TCR-induced immune responses in transgenic mice T cells

Intrabody technology provides a novel approach to decipher the molecular mechanisms of protein function in cells. Single domains composed of only the variable regions (V_H or V_L) of antibodies are the smallest recombinant antibody fragments to be constructed thus far. In this study, we developed transgenic (Tg) mice expressing the V_H or V_L single domains derived from a monoclonal antibody raised against the N-terminal domain of Wiskott–Aldrich syndrome protein (WASP), which is an adaptor molecule in immune cells. In T cells from anti-WASP V_H and V_L single domain Tg mice, interleukin-2 production induced by T cell receptor (TCR) stimulation were impaired, and specific interaction between the WASP N-terminal domain and the Fyn SH3 domain was strongly inhibited by masking the binding sites in WASP. These results strongly suggest that the V_H/V_L single domain intrabodies are sufficient to knockdown the domain function of target proteins in the cytosol.

Immunotherapy for neurodegenerative diseases: focus on α-synucleinopathies

Immunotherapy is currently being intensively explored as much-needed disease-modifying treatment for neurodegenerative diseases. While Alzheimer's disease (AD) has been the focus of numerous immunotherapeutic studies, less attention has been paid to Parkinson's disease (PD) and other neurodegenerative disorders. The reason for this difference is that the amyloid beta (Aβ) protein in AD is a secreted molecule that circulates in the blood and is readably recognized by antibodies. In contrast, α-synuclein (α-syn), tau, huntingtin and other proteins involved in neurodegenerative diseases have been considered to be exclusively of intracellular nature. However, the recent discovery that toxic oligomeric versions of α-syn and tau accumulate in the membrane and can be excreted to the extracellular environment has provided a rationale for the development of immunotherapeutic approaches for PD, dementia with Lewy bodies, frontotemporal dementia, and other neurodegenerative disorders characterized by the abnormal accumulation of these proteins. Active immunization, passive immunization, and T cell-mediated cellular immunotherapeutic approaches have been developed targeting Aβ, α-syn and tau. Most advanced studies, including results from phase III clinical trials for passive immunization in AD, have been recently reported. Results suggest that immunotherapy might be a promising therapeutic approach for neurodegenerative diseases that progress with the accumulation and propagation of toxic protein aggregates. In this manuscript we provide an overview on immunotherapeutic advances for neurodegenerative disorders, with special emphasis on α-synucleinopathies.

Isolation of a nanomolar scFv inhibiting the endopeptidase activity of botulinum toxin A, by single-round panning of an immune phage-displayed library of macaque origin

Background

Botulinum neurotoxin A (BoNT/A), mainly represented by subtype A1, is the most toxic substance known. It causes naturally-occurring food poisoning, and is among the biological agents at the highest risk of being weaponized. Several antibodies neutralizing BoNT/A by targeting its heavy chain (BoNT/A-H) have been isolated in the past. For the first time however, an IgG (4LCA) recently isolated by hybridoma technology and targeting the BoNT/A light chain (BoNT/A-L), was shown to inhibit BoNT/A endopeptidase activity and protect in vivo against BoNT/A. In the present study, a phage-displayed library was constructed from a macaque (Macaca fascicularis) hyper-immunized with BoNTA/L in order to isolate scFvs inhibiting BoNT/A endopeptidase activity for clinical use.

Results

Diversity of the scFvs constituting the library was limited due to the frequent presence, within the genes intended to be part of the library, of restriction sites utilized for its construction. After screening with several rounds of increasing stringency, as is usual with phage technology, the library got overwhelmed by phagemids encoding incomplete scFvs. The screening was successfully re-performed with a single round of high stringency. In particular, one of the isolated scFvs, 2H8, bound BoNT/A1 with a 3.3 nM affinity and effectively inhibited BoNT/A1 endopeptidase activity. The sequence encoding 2H8 was 88% identical to human germline genes and its average G-score was -0.72, quantifying the high human-like quality of 2H8.

Conclusions

The presence of restrictions sites within many of the sequences that were to be part of the library did not prevent the isolation of an scFv, 2H8, by an adapted panning strategy. ScFv 2H8 inhibited toxin endopeptidase activity in vitro and possessed human-like quality required for clinical development. More generally, the construction and screening of phage-displayed libraries built from hyper-immunized non-human primates is an efficient solution to isolate antibody fragments with therapeutic potential.

Targeting antibodies to the cytoplasm

A growing number of research consortia are now focused on generating antibodies and recombinant antibody fragments that target the human proteome. A particularly valuable application for these binding molecules would be their use inside a living cell, e.g., for imaging or functional intervention. Animal-derived antibodies must be brought into the cell through the membrane, whereas the availability of the antibody genes from phage display systems allows intracellular expression. Here, the various technologies to target intracellular proteins with antibodies are reviewed.

Gene silencing by cell-penetrating, sequence-selective and nucleic-acid hydrolyzing antibodies

Targeting particular mRNAs for degradation is a fascinating approach to achieve gene silencing. Here we describe a new gene silencing tool exploiting a cell-penetrating, nucleic-acid hydrolyzing, single-domain antibody of the light-chain variable domain, 3D8 VL. We generated a synthetic library of 3D8 VL on the yeast surface by randomizing residues located in one of two β-sheets. Using 18-bp single-stranded nucleic acids as target substrates, including the human Her2/neu-targeting sequence, we selected 3D8 VL variants that had ∼100–1000-fold higher affinity and ∼2–5-fold greater selective hydrolyzing activity for target substrates than for off targets. 3D8 VL variants efficiently penetrated into living cells to be accumulated in the cytosol and selectively decreased the amount of target sequence-carrying mRNAs as well as the proteins encoded by these mRNAs with minimal effects on off-target genes. In particular, one 3D8 VL variant targeting the Her2 sequence showed more efficient downregulation of Her2 expression than a small-interfering RNA targeting the same Her2 sequence, resulting in apoptotic cell death of Her2-overexpressing breast cancer cells. Our results demonstrate that cell-penetrating 3D8 VL variants with sequence-selective, nucleic-acid-hydrolyzing activity can selectively degrade target mRNAs in the cytosol, providing a new gene silencing tool mediated by antibody.

Efficient isolation of soluble intracellular single-chain antibodies using the twin-arginine translocation machinery

One of the most commonly used recombinant antibody formats is the single-chain variable fragment (scFv) that consists of the antibody variable heavy chain connected to the variable light chain by a flexible linker. Since disulfide bonds are often necessary for scFv folding, it can be challenging to express scFvs in the reducing environment of the cytosol. Thus, we sought to develop a method for antigen-independent selection of scFvs that are stable in the reducing cytosol of bacteria. To this end, we applied a recently developed genetic selection for protein folding and solubility based on the quality control feature of the Escherichia coli twin-arginine translocation (Tat) pathway. This selection employs a tripartite sandwich fusion of a protein-of-interest with an N-terminal Tat-specific signal peptide and C-terminal TEM1 beta-lactamase, thereby coupling antibiotic resistance with Tat pathway export. Here, we adapted this assay to develop intrabody selection after Tat export (ISELATE), a high-throughput selection strategy for the identification of solubility-enhanced scFv sequences. Using ISELATE for three rounds of laboratory evolution, it was possible to evolve a soluble scFv from an insoluble parental sequence. We show also that ISELATE enables focusing of an scFv library in soluble sequence space before functional screening and thus can be used to increase the likelihood of finding functional intrabodies. Finally, the technique was used to screen a large repertoire of naïve scFvs for clones that conferred significant levels of soluble accumulation. Our results reveal that the Tat quality control mechanism can be harnessed for molecular evolution of scFvs that are soluble in the reducing cytoplasm of E. coli.

Cellular uptake mechanisms and potential therapeutic utility of peptidic cell delivery vectors: progress 2001-2006

Cell delivery vectors (CDVs) are short amphipathic and cationic peptides and peptide derivatives, usually containing multiple lysine and arginine residues. They possess inherent membrane activity and can be conjugated or complexed with large impermeable macromolecules and even microscopic particles to facilitate cell entry. Various mechanisms have been proposed but it is now becoming clear that the main port of entry into cells of such CDV constructs involves adsorptive-mediated endocytosis rather than direct penetration of the plasma membrane. It is still unclear, however, how and to what extent CDV constructs are capable of exiting endosomal compartments and reaching their intended cellular site of action, usually the cytosol or the nucleus. Furthermore, although many CDVs can mediate cellular uptake of their cargo and appear comparatively non-toxic to cells in tissue culture, the utility of CDVs for in vivo applications remains poorly understood. Whatever the mechanisms of cell entry and disposition, the overriding question as far as potential pharmacological application of CDV conjugates is concerned is whether or not a therapeutic margin can be achieved by their administration. Such a margin will only result if the intracellular concentration in the target tissues necessary to elicit the biological effect of the CDV cargo can be achieved at systemic CDV exposure levels that are non-toxic to both target and bystander cells. It is proposed that the focus of CDV research now be shifted from mechanistic in vitro studies with labeled but otherwise unconjugated CDVs to in vivo pharmacological and toxicological studies using CDV-derivatized and other cationized forms of inherently non-permeable macromolecules of true therapeutic interest.

Generation of functional scFv intrabody to abate the expression of CD147 surface molecule of 293A cells

BACKGROUND

Expression of intracellular antibodies (intrabodies) has become a broadly applicable technology for generation of phenotypic knockouts in vivo. The method uses surface depletion of cellular membrane proteins to examine their biological function. In this study, we used this strategy to block the transport of cell surface molecule CD147 to the cell membrane. Phage display technology was introduced to generate the functional antibody fragment to CD147, and we subsequently constructed a CD147-specific scFv that was expressed intracellularly and retained in the endoplasmic reticulum by adenoviral gene transfer.

RESULTS

The recombinant antibody fragments, Fab and scFv, of the murine monoclonal antibody (clone M6-1B9) reacted specifically to CD147 by indirect enzyme-linked immunosorbent assays (ELISA) using a recombinant CD147-BCCP as a target. This indicated that the Fab- and scFv-M6-1B9 displaying on phage surfaces were correctly folded and functionally active. We subsequently constructed a CD147-specific scFv, scFv-M6-1B9-intrabody, in 293A cells. The expression of CD147 on 293A cell surface was monitored at 36 h after transduction by flow cytometry and demonstrated remarkable reduction. Colocalization of scFv-M6-1B9 intrabody with CD147 in the ER network was depicted using a 3D deconvolution microscopy system.

CONCLUSION

The results suggest that our approach can generate antibody fragments suitable for decreasing the expression of CD147 on 293A cells. This study represents a step toward understanding the role of the cell surface protein, CD147.

Intracellular antibodies (intrabodies) and their therapeutic potential

Combining exquisite specificity and high antigen-binding affinity, intrabodies have been used as a biotechnological tool to interrupt, modulate, or define the functions of a wide range of target antigens at the posttranslational level. An intrabody is an antibody that has been designed to be expressed intracellularly and can be directed to a specific target antigen present in various subcellular locations including the cytosol, nucleus, endoplasmic reticulum (ER), mitochondria, peroxisomes, plasma membrane and trans-Golgi network (TGN) through in frame fusion with intracellular trafficking/localization peptide sequences. Although intrabodies can be expressed in different forms, the most commonly used format is a singlechain antibody (scFv Ab) created by joining the antigen-binding variable domains of heavy and light chain with an interchain linker (ICL), most often the 15 amino acid linker (GGGGS)(3) between the variable heavy (VH) and variable light (VL) chains. Intrabodies have been used in research of cancer, HIV, autoimmune disease, neurodegenerative disease, and transplantation. Clinical application of intrabodies has mainly been hindered by the availability of robust gene delivery system(s) including target cell directed gene delivery. This review will discuss several methods of intrabody selection, different strategies of cellular targeting, and recent successful examples of intrabody applications. Taking advantage of the high specificity and affinity of an antibody for its antigen, and of the virtually unlimited diversity of antigen-binding variable domains available for molecular targeting, intrabody techniques are emerging as promising tools to generate phenotypic knockouts, to manipulate biological processes, and to obtain a more thorough understanding of functional genomics.

Internalization via Antennapedia protein transduction domain of an scFv antibody toward c-Myc protein

We constructed a single-chain variable fragment miniantibody (G11-scFv) directed toward the transactivation domain of c-Myc, which is fused with the internalization domain Int of Antennapedia at its carboxyl terminus (a cargo-carrier construct). In ELISA experiments, an EC(50) for binding saturation was achieved at concentrations of G11-scFv-Int(-) of approximately 10(-8) M. Internalization of a fluoresceinated Fl-G11-scFv-Int(+) construct was observed in intact human cultured cells with confocal microscopy. After 5 h of incubation in medium containing 1 microM Fl-G11-scFv-Int(+) or Fl-G11-scFv-Int(-), fluorescence intensity was determined in individual cells, both for cytoplasmic and nuclear compartments: concentration levels of Fl-G11-scFv-Int(+), relative to the extracellular culture medium concentration, were 4-5 times higher in the cytoplasm, 7-8 times higher in the nucleus, and 10 times higher in the nucleoli. In the same experimental conditions, the Fl-G11-scFv-Int(-) construct was 3-4 times more concentrated outside of the cells than inside. Cell membranes kept their integrity after 5 h of incubation. The antiproliferative activity of our miniantibody was studied on HCT116 cells. Incubation with 4 microM G11-scFv-Int(+) for 4 days induced very significant statistical and biological growth inhibition, whereas Int alone was completely inactive. Miniantibodies capable of penetrating cell membranes dramatically broaden the potential for innovative therapeutic agents and attack of new targets.

Antibody-based Proteomics: From bench to bedside

Over the past 75 years, antibodies have gone from being recognized as disease biomarkers to being used as very powerful therapeutic tools. This evolution has been accelerated by the identification of mAb and the extensive use of immunological tools both at fundamental and clinical levels. In this review, we evaluate how antibodies can be used to assess the proteome of cells or tissues and their relevance for clinical applications. These antibody-based proteomics approaches also require analytical and technological pipelines as well as specific enabling tools which are described. Our first objective was to establish how large-scale datasets (provided by high-throughput studies such as proteomics and transcriptomics) can be integrated with literature searches and clinical data to identify potentially relevant markers against which antibodies should be raised. Then based on an extensive literature review and our experience, we compare the methodologies developed to produce specific antibodies either in vivo or in vitro. This is followed by the description of the validation tools currently available and it also includes the use of antibody-based approaches in the establishment of molecular signatures utilized at the bench and soon available for bedside use.

Transfection with anti-p65 intrabody suppresses invasion and angiogenesis in glioma cells by blocking nuclear factor-kappaB transcriptional activity

PURPOSE

The strategy of intracellular antibodies to neutralize the function of target proteins has been widely developed for cancer research. This study used an intrabody against p65 subunit to prevent nuclear factor kappaB (NF-kappaB) transcriptional activity in glioma cells and to inhibit the expression of its target genes involved in the invasion and angiogenesis of human gliomas.

EXPERIMENTAL DESIGN

A single-chain fragment of antibody variable region (scFv) against p65 was prepared using phage display technique. We then prepared an anti-p65 intrabody construct (pFv/nu) by cloning the scFv-encoding sequence into the mammalian nuclear-targeting vector, pCMV/myc/nuc.

RESULTS

p65 expression in human glioma cells (U251 and] U87) transfected with pFv/nu was significantly decreased. We showed that NF-kappaB nuclear translocation and its DNA binding activity were blocked via intrabody transfection in electrophoretic mobility shift assays and the inhibition of NF-kappaB activity in nucleus resulted in the decreasing expression and bioactivity of matrix metalloproteinase-9, urokinase-type plasminogen activator receptor, urokinase-type plasminogen activator, and vascular endothelial growth factor. The intrabody transfected glioma cells showed a markedly lower level of invasion in Matrigel invasion assay. The capillary-like structure formation of endothelial cells was also repressed by coculture with the intrabody transfected glioma cells or exposure to their conditional medium. Intrabody transfection neither induced apoptosis nor altered cell proliferation in U251 and U87 cells as compared with the control vector pCMV/nu. After the injection of pFv/nu-transfected glioma cells, preestablished tumors were almost completely regressed when compared with mock, pCMV/nu, and pGFP/nu.

CONCLUSION

Blocking NF-kappaB activity via the nuclear intrabody expression might be a potential approach for cancer therapy.

Anti-p19 antibody treatment exacerbates lyme arthritis and enhances borreliacidal activity

Considerable effort has been made to elucidate the mechanism of Lyme arthritis. We focused on p19, a cell cycle-regulating molecule, because it is known to inhibit cell cycle division of T lymphocytes which may be responsible for the induction of arthritis. We show that anti-p19 antibody treatment enhances the inflammatory response normally detected at the tibiotarsal joints of Borrelia burgdorferi-vaccinated and Borrelia bissettii-challenged mice. Specifically, anti-p19 antibody treatment augmented the severity of inflammation within the synovial and subsynovial tissue. Moreover, treatment with anti-p19 antibody caused severe erosion of cartilage and bone with ankle joint destruction. In addition, anti-p19 antibody treatment of Borrelia-vaccinated and -challenged mice enhanced the borreliacidal antibody response, especially against the vaccine isolate. The novel activities of anti-p19 antibody show that p19 may be an important therapeutic site for the treatment of Lyme arthritis.

Inactivation and modification of superoxide dismutase by glyoxal: Prevention by antibodies

Glyoxal is an endogenous compound, the levels of which are increased in various pathologies associated with hyperglycaemia and other related disorders. It has been reported to inactivate critical cellular enzymes by promoting their cross-linking and perpetuates advanced glycation end-product (AGE) formation. In this study, we used superoxide dismutase (SOD) as a model to investigate the ability of specific anti-enzyme antibodies and monomer Fab fragments to protect against glyoxal-induced deactivation and aggregate formation. We found that glyoxal deactivated SOD, in a concentration and time-dependent fashion. The enzymatic activity was monitored spectrophotometrically and it was found that enzyme lost approximately 95% of its original activity, when exposed to 10 mM glyoxal for 120 h. SDS-polyacrylamide gel electrophoresis demonstrated the formation of high molecular weight aggregates in SOD samples exposed to glyoxal. Surface-enhanced laser desorption/ionization time of flight mass spectrometry (SELDI-TOF-MS) showed increase in relative molecular mass (M(r)), upon exposure to glyoxal. Specific anti-enzyme antibodies and monomer Fab fragments markedly inhibited SOD deactivation caused by glyoxal and decreased the extent of cross-linking or formation of aggregates. This protection by the antibodies or Fab fragments was specific since, other non-specific antibodies were not able to protect SOD. Previously, antibodies have been used to prevent aggregation of beta-amyloid peptides in Alzheimer and prion-protein disease. Our findings provide a new perspective, for use of antibodies to prevent the biomolecules against glycation-induced deactivation and alteration.

Conditional mutagenesis by cell-permeable proteins: potential, limitations and prospects

The combination of two powerful technologies, the Cre/loxP recombination system and the protein transduction technique, holds great promise for the advancement of biomedical and genome research by enabling precise and rapid control over mutation events. Protein transduction is a recently developed technology to deliver biologically active proteins directly into mammalian cells. It involves the generation of fusion proteins consisting of the cargo molecule to be delivered and a so-called protein transduction domain. Recently, the derivation of cell permeable variants of the DNA recombinase Cre has been reported. Cre is a site-specific recombinase that recognizes 34 base pair loxP sites and has been widely used to genetically engineer mammalian cells in vitro and in vivo. Recombinant cell-permeable Cre recombinase was found to efficiently induce recombination of loxP-modified alleles in various mammalian cell lines. Here we review recent advances in conditional expression and mutagenesis employing cell-permeable Cre proteins. Moreover, this review summarizes recent findings of studies aimed at deciphering the molecular mechanism of the cellular uptake of cell-permeable fusion proteins.