Immunoglobulin A antibodies to oxidized collagen type II as a potential biomarker for the stratification of spondyloarthritis from rheumatoid arthritis.

OBJECTIVES: The discovery of diseased tissue-specific neoantigens offers the opportunity to develop important disease tissue-specific biomarkers that can help in the prediction, diagnosis, and stratification of diseases. This opportunity is specifically significant for autoimmune diseases where diagnostic biomarkers are not available. Inflammatory autoimmune diseases are commonly associated with local generation of large amounts of reactive oxidants. We have previously identified oxidative post-translationally modified (oxPTM) tissue-specific neoantigens in rheumatoid arthritis (RA) and type 1 diabetes that elicit an immune response. In the current study, we studied the presence and clinical significance of antibodies to oxPTM collagen type II (CII) in patients with spondyloarthritis (SpA). METHOD: Levels of antibodies specific to native CII and oxPTM-CII were assessed by enzyme-linked immunosorbent assay. RESULTS: Immunoglobulin G (IgG) binding to oxPTM-CII was observed in 52%, 83%, and 28% of serum samples from patients with axial spondyloarthritis (axSpA), RA, and psoriatic arthritis (PsA), respectively. Importantly, while strong IgA anti-oxPTM-CII responses were detected in axSpA and PsA patients, with 47% and 84% respective binders, no IgA anti-oxPTM-CII was detected in RA patients. IgA anti-oxPTM-CII reactivity in axSpA patients treated with biologics was higher and more frequent, with 85% binders compared to 9% binders in patients treated with synthetic disease-modifying anti-rheumatic drugs. CONCLUSION: Our data imply that SpA and PsA are associated with the presence of antibodies to oxPTM-CII, suggesting that there may be a humoral component that may distinguish patients with SpA from RA. Our approach could be adapted to other diseases, particularly to inflammatory autoimmune diseases.

Graphene Oxide Sheets Combine into Conductive Coatings by Direct Oxidative Electropolymerization.

New coatings are obtained when graphene oxide is further oxidized at moderate anodic potentials (≤~1.3 V vs. Ag/AgCl). Based on a variety of spectroscopic and electrochemical observations, the coatings are attributed to the direct electropolymerization of graphene oxide sheets via oxidation of the phenol edge groups on graphene. Depending on the applied potential, ether or carboxylic groups are formed. The coatings obtained via further oxidation are characterized by a lower O/C ratio due to decarboxylation and a higher content of C=C bonds. These bonds extend aromatic conjugation into the combined graphene oxide sheets and are responsible for the highly conductive nature of these coatings.

HLA-dependent autoantibodies against post-translationally modified collagen type II in type 1 diabetes mellitus.

AIMS/HYPOTHESIS: In this study the involvement of oxidative stress in type 1 diabetes mellitus autoimmunity and the possible association with rheumatoid arthritis (RA) was investigated. We tested the hypothesis that oxidative stress induced by chronic hyperglycaemia triggers post-translational modifications and thus the formation of neo-antigens in type 1 diabetes, similar to the ones found in RA. METHODS: Collagen type II (CII), a known autoantigen in RA, was treated with ribose and various reactive oxygen species (ROS). Levels of antibodies specific to native and ROS-modified CII (ROS-CII) were compared in type 1 diabetes, type 2 diabetes and healthy controls, and related to the HLA genotype. RESULTS: Significantly higher binding to ROS-CII vs native CII was observed in type 1 diabetic patients possessing the HLA-DRB1*04 allele irrespective of variables of glucose control (blood glucose or HbA(1c)). Type 1 diabetic patients carrying a DRB1*04 allele with the shared epitope showed the highest risk for ROS-CII autoimmunity, while the DRB1*0301 allele was protective. Conversely, native CII autoimmunity was not associated with any specific DRB1 allele. Positive and inverse seroconversion rates of response to ROS-CII were high in DRB1*04-positive type 1 diabetic patients. CONCLUSION: Hyperglycaemia and oxidative stress may trigger genetically controlled autoimmunity to ROS-CII and may explain the association between type 1 diabetes mellitus and RA.

Involvement of autoimmunity in the pathogenesis of aggressive periodontitis.

The aim of this study was to investigate the involvement of autoimmune reactions to native and post-translationally modified extracellular matrix components in the pathogenesis of periodontitis. Sera from individuals with aggressive periodontitis (AgP, n = 25), chronic periodontitis (CP, n = 14), and gingivitis (G, n = 18) were tested for the presence of autoantibodies against: (a) native collagen type I (CI) and collagen type III (CIII); (b) CI and CIII post-translationally modified by reactive oxygen species (ROS) of the type present during inflammation; and (c) citrullinated filaggrin-derived peptides (CCP). Autoantibodies to native and ROS-modified CI and CIII as well as autoantibodies to CCP were observed exclusively in patients with AgP and not in those with CP or G. In conclusion, autoimmune reactions to native and post-translationally modified self-antigens may play a role specifically in the pathogenesis of AgP.

Historical development of monoclonal antibody therapeutics.

Since the first publication by Kohler and Milstein on the production of mouse monoclonal antibodies (mAbs) by hybridoma technology, mAbs have had a profound impact on medicine by providing an almost limitless source of therapeutic and diagnostic reagents. Therapeutic use of mAbs has become a major part of treatments in various diseases including transplantation, oncology, autoimmune, cardiovascular, and infectious diseases. The limitation of murine mAbs due to immunogenicity was overcome by replacement of the murine sequences with their human counterpart leading to the development of chimeric, humanized, and human therapeutic antibodies. Remarkable progress has also been made following the development of the display technologies, enabling of engineering antibodies with modified properties such as molecular size, affinity, specificity, and valency. Moreover, antibody engineering technologies are constantly advancing to enable further tuning of the effector function and serum half life. Optimal delivery to the target tissue still remains to be addressed to avoid unwanted side effects as a result of systemic treatment while achieving meaningful therapeutic effect.

Antibody fragments selected by phage display against the nuclear localization signal of the HIV-1 Vpr protein inhibit nuclear import in permeabilized and intact cultured cells.

The HIV-1 Vpr protein harbors a nuclear localization signal in its N-terminal domain. A peptide bearing this domain and which is designated VprN has been used as a target to screen a phage display single chain Fv (scFv) library. Here we report the isolation of anti-VprN scFv fragments from this library. The purified scFv fragments were able to bind the VprN peptide in an ELISA-based system and to inhibit VprN-mediated nuclear import in permeabilized as well as in intact microinjected cells. Furthermore, the anti-VprN scFv fragments recognized the full-length recombinant Vpr protein and inhibited its nuclear import. The same scFv fragments did not inhibit nuclear import mediated by the nuclear localization signal of the SV40 large T-antigen demonstrating a specific effect. The use of the described inhibitory anti-VprN scFv fragments to study nuclear import of viral karyophilic proteins and their therapeutic potential is discussed.

Development of human antibody fragments directed towards synaptic acetylcholinesterase using a semi-synthetic phage display library.

Current Alzheimer's disease therapies suppress acetylcholine hydrolysis by inhibiting acetylcholinesterase (AChE) at cholinergic synapses. However, anticholinesterases promote alternative splicing changing the composition of brain AChE variants. To study this phenomenon we developed monoclonal antibodies to acetylcholinesterase synaptic peptide (ASP), a synthetic peptide with the C-terminal sequence unique to the human synaptic variant AChE-S. Screening of a phage display human antibody library allowed the isolation of single-chain Fv (scFv) antibodies that were highly specific for ASP, and displayed closely related third complementarity determining regions of the variable heavy chain domain (V(H)-CDR3). BIAcore analysis demonstrated dissociation constants at the micromolar range: 1.6 x 10(-6) and 2.0 x 10(-6) M for ASP and the complete AChE-S protein, respectively. The anti-ASP antibodies provide a novel tool for studying the synaptic AChE-S variant, the expression of which is altered in ageing and dementia.

Inhibition of antibody-dependent stimulation of lipoteichoic acid-treated human monocytes and macrophages by polyglycerolphosphate-reactive peptides.

By itself, lipoteichoic acid (LTA) obtained from S. pyogenes, S. aureus, or E. hirae poorly stimulated cytokine production by macrophages, whereas in the presence of anti-polyglycerol phosphate (PGP), the cells secreted significant amounts of IL-6. Two peptides constructed from the deduced sequence of the selected anti-PGP phage-antibody's complementary-determining region 3 of the variable heavy chain (V(H)-CDR3) reacted specifically with PGP. The monomeric form of the peptides markedly inhibited cytokine production by macrophages pretreated with LTA and anti-LTA. In contrast, the polyvalent form of biotinylated peptides complex with streptavidin-induced cytokine production by the LTA-treated macrophages. The data taken together support the concept that cross-linking of macrophage-bound LTA by anti-PGP is required for cytokine release by these cells. Importantly, these studies identified small, PGP-reactive peptides as potential tools in reducing this proinflammatory process.

Generation and epitope mapping of high-affinity scFv to eukaryotic elongation factor 1A by dual application of phage display.

To generate specific tools for, in particular, localization studies of the eukaryotic elongation factor 1A (eEF1A), we have applied phage display in various formats to affinity-improve and map epitopes of two previously isolated, low-affinity single-chain Fv (scFv) G3 and D1. The scFv differ in their reactivity toward the eEF1A isoforms, eEF1A-1 and eEF1A-2. By PCR-based randomization of six residues within the variable light chain CDR3 (LCDR3), and subsequent phage-based affinity-selection, two 'families' of affinity-improved scFv were obtained. The scFv of highest affinity, A8, has a Kd of 9 nM to eEF1A-1. Interestingly, two affinity-improved scFvs have abnormally short LCDR3 consisting of two and four residues compared to 11 in the parental scFv. Hence, the LCDR3 of the parental clones may play a modulating rather than a direct role in antigen-binding. Despite different preferences for the eEF1A isoforms, both families of scFv recognize antigenic determinant(s), which was mapped to residues 413-450 of eEF1A-1/2 by Western blot analysis of recombinant human eEF1A (hEF1A) fragments. Prior to the Western blotting analysis, the epitope location had been suggested using a novel approach where phage-antibody repertoire derived scFv were used to select phage-displayed peptides. Hereby, peptides containing a SFXD motif, matching the SFSD(414-418) sequence found in hEF1A-1 were isolated. The structure of eukaryotic EF1A from yeast indicates a discontinuous nature of the epitope with distal functional elements juxtaposed by the protein fold. Finally, the scFv A8 was applied for immunofluorescence studies of transformed human amnion cells and MCF-7 fibroblasts. In both cases a perinuclear localization of hEF1A was observed. No evidence for the reported nuclear localization of hEF1A was obtained.

Specific inhibition of the reaction between a tumor-inhibitory antibody and the ErbB-2 receptor by a mimotope derived from a phage display library.

Overexpression of ErbB-2, a coreceptor for stroma-derived growth factors, is involved in malignancies of epithelial tissues, and a humanized antibody to ErbB-2 was shown to be therapeutic in a clinical setting. In an effort to understand and enhance immunotherapy, the laboratory has raised several tumor inhibitory monoclonal antibodies (mAb), including mAb L26 that blocks inter-receptor interactions. Here the application of the phage display methodology for the isolation of a phage clone that specifically recognizes mAb L26 is described. The isolated mimetic peptide (mimotope) specifically inhibited the binding of mAb L26 to ErbB-2 overexpressing cells. No sequence homology was found between the mimotope and ErbB-2. implying that it mimics a conformational structure of the receptor. Preliminary studies showed that the lead peptide can be truncated by removal of two to three amino acids from either the N- or C-terminal end without drastically affecting the inhibitory properties of the mimotope. A tryptophan'glycine residue at the C-terminus and a lysine at the N-terminus of the peptide seemed to play a role in its ability to compete with L26 antibody for binding to ErbB-2 overexpressing cells. These results highlight the potential of active immunization with conformation mimicking peptides in ErbB-2 overexpressing tumors.

Targeting by affinity-matured recombinant antibody fragments of an angiogenesis associated fibronectin isoform.

The oncofetal fibronectin (B-FN) isoform is present in vessels of neoplastic tissues during angiogenesis but not in mature vessels. B-FN could therefore provide a target for diagnostic imaging and therapy of cancer. Phage display libraries have been used to isolate human antibody fragments with pan-species recognition of this isoform. We describe the use of these fragments in nude mice to target an aggressive tumor (grafted F9 murine teratocarcinoma). Imaging in real time was done by infrared photodetection of a chemically coupled fluorophore. The targeting was improved by use of affinity-matured fragments with low kinetic dissociation rates (koff = 1.5 x 10(-4) s-1) and also by engineering dimeric fragments via a C-terminal amphipathic helix.

Improvement of Aconitum napellus micropropagation by liquid culture on floating membrane rafts.

An efficient method was developed using floating membrane rafts (Liferaft(™)) for the micropropagation of Aconitum napellus (Ranunculaceae), a cut flower crop with a low natural propagation rate. This was achieved by introducing shoot tips into culture on Murashige and Skoog's (1962) solid medium, or liquid medium-supported rafts, supplemented by different levels of benzyl adenine (BA). Optimum shoot proliferation on solid medium required 4mg/l BA, whereas for expiants supported on rafts optimal proliferation was achieved at 0.25mg/l BA. Maximum shoot proliferation was found using the floating rafts (propagation ratio of 4.2 per month), 45% higher than the maximum value on solid medium. A similar value could be obtained on solid medium after a period of 2 months. The optimal response to BA was similar for fresh weight gain and shoot length. Growth in a shallow layer of liquid in shake flasks gives a similar shoot multiplication rate to that on floating rafts; however, submerged leaves brown and die.

Antibody fragments from a 'single pot' phage display library as immunochemical reagents.

The display of repertoires of antibody fragments on the surface of filamentous bacteriophage offers a new way of making antibodies with predefined binding specificities. Here we explored the use of this technology to make immunochemical reagents to a range of antigens by selection from a repertoire of > 10(8) clones made in vitro from human V gene segments. From the same 'single pot' repertoire, phage were isolated with binding activities to each of 18 antigens, including the intracellular proteins p53, elongation factor EF-1 alpha, immunoglobulin binding protein, rhombotin-2 oncogene protein and sex determining region Y protein. Both phage and scFv fragments secreted from infected bacteria were used as monoclonal and polyclonal reagents in Western blots. Furthermore the monoclonal reagents were used for epitope mapping (a new epitope of p53 was identified) and for staining of cells. This shows that antibody reagents for research can be readily derived from 'single pot' phage display libraries.

Fine specificity of the IgE interaction with the low and high affinity Fc receptor.

The characterization of the site(s) on the IgE molecule that accommodate the high (Fc epsilon RI) and low (Fc epsilon RII) affinity receptors for IgE should allow the design of IgE analogues that can be used to block the onset of the allergic response or to regulate IgE production. To identify the IgE domain responsible for receptor binding, we generated a series of chimeric IgE antibodies in which constant region domains were interchanged between the human and mouse molecules. Binding studies with these chimeras revealed that both the high and low affinity receptor binding-sites reside primarily in the third constant domain of IgE (C epsilon 3). Additional chimeric IgE molecules were generated in which different parts of the human C epsilon 3 domain were exchanged with their murine homologues. Binding experiments with these chimeras suggest that not only the sequence of a particular C epsilon 3 fragment, but the entire C epsilon 3 domain in its native configuration is essential for binding to the Fc epsilon RI. The amino acid residues determining the species specificity of the Fc epsilon RII are not contained in the first 16 amino acids of the C epsilon 3 domain.

The human mast cell receptor binding site maps to the third constant domain of immunoglobulin E.

The characterization of the site on the IgE molecule which accommodates the high affinity receptor for IgE (Fc epsilon RI) should allow the design of IgE analogues which can be utilized to block allergic responses. Using chimeric human IgE molecules in which different constant region domains were exchanged with their murine homologues, we demonstrate here that the C epsilon 3 in its native configuration is essential for the binding to the alpha subunit of the human Fc epsilon RI. Deletion of the human C epsilon 2 from such chimeric molecules did not impair their ability to interact with the Fc epsilon RI, indicating that C epsilon 2 is not directly involved in the human Fc epsilon RI binding site and that C epsilon 3 alone is necessary and sufficient to account for most of the human Fc epsilon RI-binding capacity.

The murine 2-5A synthetase locus: three distinct transcripts from two linked genes.

The cloning of cDNAs encoding murine 2-5A synthetase has identified three related transcripts, represented by a previously described cDNA clone, L3 and two novel cDNAs, L1 and L2. L1 contains an open reading frame coding for a protein that shows 70% conservation at the amino acid level when compared to the protein predicted to be encoded by L3. L2 recognizes an IFN-induced transcript 600-bp larger than the L3 transcript. These three cDNAs map to a cosmid, cII, containing two murine 2-5A synthetase genes, ME12 and ME5/ME8, situated in a head-to-tail orientation separated by approximately 8 kb. Southern analyses of ME12 and ME5/ME8 using L3, L1-specific and L2-specific probes indicate that these genes have a similar organization. cII was transiently and stably transfected into CV-1 cells. When treated with interferon, the transfected cells produced mature, murine 2-5A synthetase transcripts identified using L3 and L2-specific probes. Thus all transcripts present in IFN-treated mouse cells which are recognized by the available murine 2-5A synthetase cDNA probes map to an approximately 40 kb region of the mouse genome containing two 2-5A synthetase genes.

Mapping of the high affinity Fc epsilon receptor binding site to the third constant region domain of IgE.

Identification of the precise region(s) on the IgE molecule that take part in the binding of IgE to its high affinity receptor (Fc epsilon RI) may lead to the design of IgE analogues able to block the allergic response. To localize the Fc epsilon RI-binding domain of mouse IgE, we attempted to confer on human IgE, which normally does not bind to the rodent receptor, the ability to bind to the rat Fc epsilon RI. Employing exon shuffling, we have expressed chimeric epsilon-heavy chain genes composed of a mouse (4-hydroxy-3-nitrophenyl)acetic acid (NP)-binding VH domain, and human C epsilon in which various domains were replaced by their murine counterparts. This has enabled us to test the Fc epsilon RI-binding of each mouse IgE domain while maintaining the overall conformation of the molecule. All of the chimeric IgE molecules which contain the murine C epsilon 3, bound equally to both the rodent and human receptor, as well as to monoclonal antibodies recognizing a site on IgE which is identical or very close to the Fc epsilon RI binding site. Deletion of the second constant region domain did not impair either the binding capacity of the mutated IgE or its ability to mediate mast cell degradation. These results assign the third epsilon domain of IgE as the principal region involved in the interaction with the Fc epsilon RI.