Antibodies Isolated from Rheumatoid Arthritis Patients against Lysine-Containing Proteus mirabilis O3 (S1959) Lipopolysaccharide May React with Collagen Type I

Most rheumatic diseases, including rheumatoid arthritis (RA), are characterized by immune disorders that affect antibody activity. In the present study, using Dot blot and ELISA assay, we showed that patients with rheumatic disease produced significantly more antibodies against lipopolysaccharide (LPS) P. mirabilis O3 compared to healthy donors (p < 0.05), and affinity purified antibodies against LPS O3 may cross-react with collagen type I. It was demonstrated that purified of antibodies isolated from RA patients sera, reacted stronger with the collagen than healthy donors (p = 0.015), and cross-reaction was correlated with level of anti-citrullinated peptide antibodies (r = 0.7, p = 0.003). Moreover, using six different lipopolysaccharides were demonstrated the significant correlations in sera reactivity among lysine-containing lipopolysaccharides observed in patients’ sera (p < 0.05). Using Attenuated Total Reflection Fourier Transform Infrared Spectroscopy (ATR-FTIR) it was shown that unique wavenumbers of sera spectra correlate with reactivity with lipopolysaccharides allowing distinguish patients from healthy blood donors. Antibodies adsorption by synthetic antigens shows that in patients’ group anti-LPS O3 antibodies can be adsorbed by both amides of galacturonic acid and lysine or threonine, which suggests less specificity of antibodies binding with non-carbohydrate LPS component. The observed correlations suggest that non-carbohydrate components of LPS may be an important epitope for less specific anti-LPS antibodies, which might lead to cross-reactions and affect disease development.

Engineering Antibodies with C-Terminal Sortase-Mediated Modification for Targeted Nanomedicine

The current advances in nanoengineered materials coupled with the precise targeting capability of recombinant antibodies can create nanoscale diagnostics and therapeutics which show enhanced accumulation and extended retention at a target tissue. Smaller antibodies such as single-chain variable fragments (scFv) preserve the selective and strong binding of their parent antibody to their antigen with the benefits of low immunogenicity, more efficient tissue penetration and easy introduction of functional residues suitable for site-specific conjugation. This is of high importance as nonspecific antibody modification often involves attachment to free cysteine or lysine amino acids which may reside in the active site, leading to reduced antigen binding.In this chapter, we outline a facile and versatile chemoenzymatic approach for production of targeted nanocarrier scFv conjugates using the bacterial trans-peptidase Sortase A (Srt A). Srt A efficiently mediates sequence-specific peptide ligation under mild conditions and has few undesirable side reactions. We first describe the production, purification and characterization of Srt A enzyme and a scFv construct which targets activated platelets, called scFv_{anti-GPIIb/IIIa}. Following this, our protocol illustrates the chemoenzymatic modification of the antibody at the C-terminus with an orthogonal click chemistry linker. This avoids any random attachment to the biologically active antigen binding site of the antibody. Finally, we describe the modification of a nanoparticle surface with scFv attachment via two methods: (1) direct Sortase-mediated conjugation; or (2) a two-step system which consists of scFv Sortase-mediated conjugation followed by strain promoted azide-alkyne cycloaddition. Finally, methodology is described to assess the successful assembly of targeted particles.

Lysine Bioconjugation on Native Albumin with a Sulfonyl Acrylate Reagent

This protocol details a novel bioconjugation strategy that uses a methanesulfonyl acrylate reagent that is directed to the most reactive lysine on human serum albumin, which enables the construction of chemically defined and stable bioconjugates. The reaction proceeds rapidly and a regioselective modification is achieved using a single molar equivalent of the reagent under biocompatible conditions (37 °C, pH 8.0). Importantly, the bioconjugate retains both the secondary structural content and function of the unmodified protein. During the reaction of the amino group of lysine and the sulfonyl acrylate reagent, methanesulfinic acid is released after the conjugate addition, which then generates an electrophilic acrylate moiety on the protein. This acrylate can be further used for site-specific protein labeling using a synthetic molecule bearing a reactive amine under biocompatible conditions (21 °C, pH 8.0).

Dietary Advanced Glycation Endproducts Induce an Inflammatory Response in Human Macrophages in Vitro

Advanced glycation endproducts (AGEs) can be found in protein- and sugar-rich food products processed at high temperatures, which make up a vast amount of the Western diet. The effect of AGE-rich food products on human health is not yet clear and controversy still exists due to possible contamination of samples with endotoxin and the use of endogenous formed AGEs. AGEs occur in food products, both as protein-bound and individual molecules. Which form exactly induces a pro-inflammatory effect is also unknown. In this study, we exposed human macrophage-like cells to dietary AGEs, both in a protein matrix and individual AGEs. It was ensured that all samples did not contain endotoxin concentrations > 0.06 EU/mL. The dietary AGEs induced TNF-alpha secretion of human macrophage-like cells. This effect was decreased by the addition of N(ε)-carboxymethyllysine (CML)-antibodies or a receptor for advanced glycation endproducts (RAGE) antagonist. None of the individual AGEs induce any TNF-alpha, indicating that AGEs should be bound to proteins to exert an inflammatory reaction. These findings show that dietary AGEs directly stimulate the inflammatory response of human innate immune cells and help us define the risk of regular consumption of AGE-rich food products on human health.

A novel monoclonal antibody targeting carboxymethyllysine, an advanced glycation end product in atherosclerosis and pancreatic cancer

Advanced glycation end products are formed by non-enzymatic reactions between proteins and carbohydrates, causing irreversible lysine and arginine alterations that severely affect protein structure and function. The resulting modifications induce inflammation by binding to scavenger receptors. An increase in advanced glycation end products is observed in a number of diseases e.g. atherosclerosis and cancer. Since advanced glycation end products also are present in healthy individuals, their detection and quantification are of great importance for usage as potential biomarkers. Current methods for advanced glycation end product detection are though limited and solely measure total glycation. This study describes a new epitope-mapped single chain variable fragment, D1-B2, against carboxymethyllysine, produced from a phage library that was constructed from mouse immunizations. The phage library was selected against advanced glycation end product targets using a phage display platform. Characterization of its binding pattern was performed using large synthetic glycated peptide and protein libraries displayed on microarray slides. D1-B2 showed a preference for an aspartic acid, three positions N-terminally from a carboxymethyllysine residue and also bound to a broad collection of glycated proteins. Positive immunohistochemical staining of mouse atherosclerotic plaques and of a tissue microarray of human pancreatic tumors confirmed the usability of the new scFv for advanced glycation end product detection in tissues. This study demonstrates a promising methodology for high-throughput generation of epitope-mapped monoclonal antibodies against AGE.

Biochemical Principles and Functional Aspects of Pipecolic Acid Biosynthesis in Plant Immunity

The nonprotein amino acid pipecolic acid (Pip) regulates plant systemic acquired resistance and basal immunity to bacterial pathogen infection. In Arabidopsis (Arabidopsis thaliana), the lysine (Lys) aminotransferase AGD2-LIKE DEFENSE RESPONSE PROTEIN1 (ALD1) mediates the pathogen-induced accumulation of Pip in inoculated and distal leaf tissue. Here, we show that ALD1 transfers the α-amino group of l-Lys to acceptor oxoacids. Combined mass spectrometric and infrared spectroscopic analyses of in vitro assays and plant extracts indicate that the final product of the ALD1-catalyzed reaction is enaminic 2,3-dehydropipecolic acid (DP), whose formation involves consecutive transamination, cyclization, and isomerization steps. Besides l-Lys, recombinant ALD1 transaminates l-methionine, l-leucine, diaminopimelate, and several other amino acids to generate oxoacids or derived products in vitro. However, detailed in planta analyses suggest that the biosynthesis of 2,3-DP from l-Lys is the major in vivo function of ALD1. Since ald1 mutant plants are able to convert exogenous 2,3-DP into Pip, their Pip deficiency relies on the inability to form the 2,3-DP intermediate. The Arabidopsis reductase ornithine cyclodeaminase/μ-crystallin, alias SYSTEMIC ACQUIRED RESISTANCE-DEFICIENT4 (SARD4), converts ALD1-generated 2,3-DP into Pip in vitro. SARD4 significantly contributes to the production of Pip in pathogen-inoculated leaves but is not the exclusive reducing enzyme involved in Pip biosynthesis. Functional SARD4 is required for proper basal immunity to the bacterial pathogen Pseudomonas syringae Although SARD4 knockout plants show greatly reduced accumulation of Pip in leaves distal to P. syringae inoculation, they display a considerable systemic acquired resistance response. This suggests a triggering function of locally accumulating Pip for systemic resistance induction.

Autoantibodies against mono- and tri-methylated lysine display similar but also distinctive characteristics

Autoantibodies can be either harmful or beneficial to the body. The beneficial autoantibodies play important roles in immunosurveillance, clearance of body waste and maintenance of immune homeostasis. Despite their importance, however, people’s knowledge on the protective autoantibodies is still very limited. In the current study, we examined two autoantibodies that recognized epitopes with only one amino acid. One was against mono-methylated lysine (Kme) and the other was against tri-methylated lysine (Kme3). We found that the antibodies were highly specific and not polyreactive. They did not cross-react each other. Although anti-Kme antibodies were IgM only, a large proportion of the anti-Kme3 antibodies were switched to the IgG isotype. Mass spectrometric analysis showed that both of the antibodies were mainly derived from IGHV 3–7 and/or IGHV3-74 germ line genes with conserved CDR2. De novo sequencing showed that there was a mutation at either of the SS positions on the CDR1 region, which changed one of the serine residues to a basic amino acid, i.e., arginine or lysine. We also found that neither of the antibodies was expressed at birth, and their earliest appearance was approximately 5 months after birth. All healthy human beings expressed the antibodies when they reached age two and maintained the expression thereafter throughout their life. Patients with systemic lupus erythematosus had lower levels of the IgM isotype antibodies. Serum levels of the two IgM antibodies were closely correlated, implying that they were produced by cells from the same B cell subset. We also found that both anti-Kme and anti-Kme3 antibodies could bind and might take part in the clearance of neutrophil extracellular traps released from activated cells. In conclusion, although anti-Kme and anti-Kme3 antibodies share many similarities in their origins, they are different antibodies and have different characteristics.

Structural Analysis and Optimization of Context-Independent Anti-Hypusine Antibodies

Context-independent anti-hypusine antibodies that bind to the post-translational modification (PTM), hypusine, with minimal dependence on flanking amino acid sequences, were identified. The antibodies bind to both hypusine and deoxyhypusine or selectively to hypusine but not to deoxyhypusine. Phage display was used to further enhance the affinity of the antibodies. Affinity maturation of these anti-hypusine antibodies improved their performance in affinity capture of the only currently known hypusinated protein, eukaryotic translation initiation factor 5A. These anti-hypusine antibodies may have utility in the identification of novel hypusinated proteins. Crystal structures of the corresponding Fab fragments were determined in complex with hypusine- or deoxyhypusine-containing peptides. The hypusine or deoxyhypusine moiety was found to reside in a deep pocket formed between VH and VL domains of the Fab fragments. Interaction between the antibodies and hypusine includes an extensive hydrogen bond network. These are, to our knowledge, the first reported structures of context-independent anti-PTM antibodies in complex with the corresponding PTM.

Effect of lysine to arginine mutagenesis in the V3 loop of HIV-1 gp120 on viral entry efficiency and neutralization

HIV-1 infection is characterized by an ongoing replication leading to T-lymphocyte decline which is paralleled by the switch from CCR5 to CXCR4 coreceptor usage. To predict coreceptor usage, several computer algorithms using gp120 V3 loop sequence data have been developed. In these algorithms an occupation of the V3 positions 11 and 25, by one of the amino acids lysine (K) or arginine (R), is an indicator for CXCR4 usage. Amino acids R and K dominate at these two positions, but can also be identified at positions 9 and 10. Generally, CXCR4-viruses possess V3 sequences, with an overall positive charge higher than the V3 sequences of R5-viruses. The net charge is calculated by subtracting the number of negatively charged amino acids (D, aspartic acid and E, glutamic acid) from the number of positively charged ones (K and R). In contrast to D and E, which are very similar in their polar and acidic properties, the characteristics of the R guanidinium group differ significantly from the K ammonium group. However, in coreceptor predictive computer algorithms R and K are both equally rated. The study was conducted to analyze differences in infectivity and coreceptor usage because of R-to-K mutations at the V3 positions 9, 10 and 11. V3 loop mutants with all possible RRR-to-KKK triplets were constructed and analyzed for coreceptor usage, infectivity and neutralization by SDF-1α and RANTES. Virus mutants R₉R₁₀R₁₁ showed the highest infectivity rates, and were inhibited more efficiently in contrast to the K₉K₁₀K₁₁ viruses. They also showed higher efficiency in a virus-gp120 paired infection assay. Especially V3 loop position 9 was relevant for a switch to higher infectivity when occupied by R. Thus, K-to-R exchanges play a role for enhanced viral entry efficiency and should therefore be considered when the viral phenotype is predicted based on V3 sequence data.

The Maillard reaction and food allergies: is there a link?

Food allergies are abnormal responses to a food triggered by the immune system. The majority of allergenic foods are often subjected to thermal processing before consumption. The Maillard reaction is a non-enzymatic reaction between reducing sugars and compounds with free amino groups such as amino acids and proteins, and takes place during thermal processing and storage of foods. Among many other effects the reaction leads to modification of proteins with various types of glycation structures such as Nε-(carboxymethyl-)lysine (CML), pentosidine, pyrraline and methylglyoxal-H1, which are collectively called advanced glycation end-products (AGEs). Notably, evidence has accumulated that some glycation structures of AGEs function as immune epitopes. Here we discuss the possible involvement of food allergen AGEs in the pathogenesis of food allergies.

The amide of galacturonic acid with lysine as an immunodominant component of the lipopolysaccharide core region from Proteus penneri 42 strain

Most Proteus lipopolysaccharides (LPSs) contain uronic acids or their amides with different amino acids, which together with other negatively charged components account for the acidic character of such LPS molecules. Previous studies have shown the significance of an amide of galacturonic acid with lysine [D-GalA(L-Lys)] for serological specificity of O-antigens from few P. mirabilis strains. In this work, the immunodominant role of GalALys was indicated for the P. penneri 42 LPS core region. The studies also showed the serological identity of core oligosaccharides from P. penneri 42 (O71), P. mirabilis 51/57 (O28) and R14/S1959 strains.

Characterization of nucleolin K88 acetylation defines a new pool of nucleolin colocalizing with pre-mRNA splicing factors

Nucleolin is a multifunctional protein that carries several post-translational modifications. We characterized nucleolin acetylation and developed antibodies specific to nucleolin K88 acetylation. Using this antibody we show that nucleolin is acetylated in vivo and is not localized in the nucleoli, but instead is distributed throughout the nucleoplasm. Immunofluorescence studies indicate that acetylated nucleolin is co-localized with the splicing factor SC35 and partially with Y12. Acetylated nucleolin is expressed in all tested proliferating cell types. Our findings show that acetylation defines a new pool of nucleolin which support a role for nucleolin in the regulation of mRNA maturation and transcription by RNA polymerase II.

Generation and characterization of pan-specific anti-acetyllysine antibody

Pan-specific anti-acetylated lysine antibody is a valuable tool to detect, validate, and quantify protein lysine acetylation. Compared to site-specific acetyllysine antibodies that are not readily available in most cases, polyclonal pan-specific acetyllysine antibodies can be generated with synthetic antigen of a carrier protein that has its lysine residues chemically acetylated. Here, we describe protocols of synthesizing acetylated ovalbumin (OVA), immunizing rabbits, and characterizing pan-specific polyclonal anti-acetylated lysine antibodies.

Autoacetylation of the Ralstonia solanacearum effector PopP2 targets a lysine residue essential for RRS1-R-mediated immunity in Arabidopsis

Type III effector proteins from bacterial pathogens manipulate components of host immunity to suppress defence responses and promote pathogen development. In plants, host proteins targeted by some effectors called avirulence proteins are surveyed by plant disease resistance proteins referred to as “guards”. The Ralstonia solanacearum effector protein PopP2 triggers immunity in Arabidopsis following its perception by the RRS1-R resistance protein. Here, we show that PopP2 interacts with RRS1-R in the nucleus of living plant cells. PopP2 belongs to the YopJ-like family of cysteine proteases, which share a conserved catalytic triad that includes a highly conserved cysteine residue. The catalytic cysteine mutant PopP2-C321A is impaired in its avirulence activity although it is still able to interact with RRS1-R. In addition, PopP2 prevents proteasomal degradation of RRS1-R, independent of the presence of an integral PopP2 catalytic core. A liquid chromatography/tandem mass spectrometry analysis showed that PopP2 displays acetyl-transferase activity leading to its autoacetylation on a particular lysine residue, which is well conserved among all members of the YopJ family. These data suggest that this lysine residue may correspond to a key binding site for acetyl-coenzyme A required for protein activity. Indeed, mutation of this lysine in PopP2 abolishes RRS1-R-mediated immunity. In agreement with the guard hypothesis, our results favour the idea that activation of the plant immune response by RRS1-R depends not only on the physical interaction between the two proteins but also on its perception of PopP2 enzymatic activity.

Plant and animal bacterial pathogens have evolved to produce virulence factors, called type III effectors, which are injected into host cells to suppress host defences and provide an environment beneficial for pathogen growth. Type III effectors from pathogenic bacteria display enzymatic activities, often mimicking an endogenous eukaryotic activity, to target host signalling pathways. Elucidation of strategies used by pathogens to manipulate host protein activities is a subject of fundamental interest in pathology. PopP2 is a YopJ-like effector from the soil borne root pathogen Ralstonia solanacearum. Here, in addition to demonstrating PopP2 ability to stabilize the expression of its cognate Arabidopsis RRS1-R resistance protein and physically interact with it, we investigated the enzymatic activity of PopP2. Bacterial YopJ-like effectors are predicted to act as acetyl-transferases on host components. However, only two YopJ-like proteins from animal pathogens have been shown to be active acetyl-transferases. We show that PopP2 displays autoacetyl-transferase activity targeting a lysine residue well-conserved among YopJ-like family members. This lysine is a critical residue since its mutation prevents autoacetylation of PopP2 and abolishes its recognition by the host. This study provides new clues on the multiple properties displayed by bacterial type III effectors that may be used to target defense-related host components.

Chemical and immunochemical identification of propanoyllysine derived from oxidized n-3 polyunsaturated fatty acid

It is known that n-3 polyunsaturated fatty acids (PUFAs), such as docosahexaenoic acid and eicosapentaenoic acid, are rapidly oxidized in vitro. Nvarepsilon-(propanoyl)lysine (propionyllysine, or PRL) is formed from the reaction of the oxidized products of n-3 PUFAs and lysine. To evaluate the oxidized n-3 PUFA-derived protein modifications in vivo, we have developed detection methods using a novel monoclonal antibody against PRL as well as liquid chromatography-mass spectrometry (LC/MS/MS). The antibody obtained specifically recognized PRL. A strong positive staining in atherosclerotic lesions of hypercholesterolemic rabbits was observed. We have also simultaneously identified and quantified both urinary PRL and urinary Nvarepsilon-(hexanoyl)lysine, using LC/MS/MS using isotope dilution methods. The level of urinary PRL (21.6+/-10.6 micromol/mol of creatinine) significantly correlated with the other oxidative stress markers, 8-oxo-deoxyguanosine, dityrosine, and isoprostanes. The increase in the excretion of amide adducts into the urine of diabetic patients was also confirmed compared to healthy subjects. These results suggest that PRL may be good marker for n-3 PUFA-derived oxidative stress in vivo.

Diagnosis of aspirin-induced asthma combining the bronchial and the oral challenge tests: a pilot study

BACKGROUND

We investigated the usefulness of the bronchial challenge (BC) with lysine-acetylsalicylate (L-ASA) in the diagnosis of aspirin-exacerbated respiratory disease (AERD) using a protocol that combined both the oral challenge (OC) and the BC tests.

METHODS

Adult asthmatic patients with suspected AERD who underwent BC with L-ASA were included in the study. If the BC result with L-ASA was negative, an OC was carried out to establish the diagnosis. AERD was ruled out if both the BC and the OC results were negative (nonresponders). Both responders and nonresponders were compared for age, gender, a personal or family history of atopy, underlying disease, current asthma treatment, and presence of nasal polyps. Six patients with asthma but no suggestive history of AERD were included as controls.

RESULTS

Twenty-two patients completed the study. Ten patients tested positive to the BC and/or OC (responders), whereas 12 did not (nonresponders). Seven out of the 10 responders had a positive BC result and 3 a positive OC result. After BC, 4 patients had an early asthmatic response, 1 had a dual response, and 2 had isolated late responses. No significant differences were observed in the aforementioned variables between responders and nonresponders. The results of both challenges were negative in the 6 controls.

CONCLUSIONS

The BC had a high positive predictive value, was safe, and when negative, the subsequent OC did not result in any severe adverse reactions. The BC elicited an isolated late asthmatic response that has not been previously described in the literature.

Peptide microarrays for profiling of modification state-specific antibodies

The reversible phosphorylation of serine, threonine, and tyrosine residues is one of the most important intracellular post-translational modifications regulating enzymatic activities and protein/protein interaction in eukaryotic cells. Tools for determining phosphorylation status of proteins and peptides play a prominent role in signal transduction research and proteomics. Pan-specific antibodies claimed to recognize modified amino acid residues independent on the nature of surrounding residues in peptides and proteins are widely used. We used high-content phosphopeptide microarrays and microarrays displaying acetyllysine-containing peptides for comprehensive characterization of commercially available generic anti-phosphopeptide and anti-acetyllysine antibodies. We were able to demonstrate distinct subsite specificity and cross-reactivity for such antibodies.

Toward Understanding the Cationicity of Defensins

Human defensins are a family of small antimicrobial proteins found predominantly in leukocytes and epithelial cells that play important roles in the innate and adaptive immune defense against microbial infection. The most distinct molecular feature of defensins is cationicity, manifested by abundant Arg and/or Lys residues in their sequences. Sequence analysis indicates that Arg is strongly selected over Lys in alpha-defensins but not in beta-defensins. To understand this Arg/Lys disparity in defensins, we chemically synthesized human alpha-defensin 1 (HNP1) and several HNP1 analogs where three Arg residues were replaced by each of the following six alpha-amino acids: Lys, ornithine (Orn), diaminobutyric acid (Dab), diaminopropionic acid (Dap), N,N-dimethyl-Lys ((diMe)Lys), and homo-Arg ((homo)Arg). In addition, we prepared human beta-defensin 1 (hBD1) and (Lys-->Arg)hBD1 in which all four Lys residues were substituted for Arg. Bactericidal activity assays revealed the following. 1) Arg-containing HNP1 and (Lys-->Arg)hBD1 are functionally better than Lys-HNP1 and hBD1, respectively; the difference between Arg and Lys is more evident in the alpha-defensin than in the beta-defensin and is more evident at low salt concentrations than at high salt concentrations. 2) For HNP1, the Arg/Lys disparity is much more pronounced with Staphylococcus aureus than with Escherichia coli, and the Arg-rich HNP1 kills bacteria faster than its Lys-rich analog. 3) Arg and Lys appear to have optimal chain lengths for bacterial killing as shortening Lys or lengthening Arg in HNP1 invariably becomes functionally deleterious. Our findings provide insights into the Arg/Lys disparity in defensins, and shed light on the cationicity of defensins with respect to their antimicrobial activity and specificity.

Urinary LTE4 is higher after nasal provocation test with L-ASA in bronchial than in only nasal responders

Aspirin induced asthma (AIA) is a syndrome characterised by intolerance to acetylsalycilic acid (ASA), nasal polyps and bronchial asthma, being the metabolic shift of arachidonic acid toward the lipoxygenase pathway and hyper-production of cysteinyl-leukotrienes (cys-LTs) the current pathogenetic hypothesis. The research for both sensitive indicators and safe diagnostic tests is still attracting. Aim of the study was to compare the levels of urinary LTE4 in baseline and after Nasal Provocation Test (NPT) with L-ASA from subjects affected by aspirinin-Intolerance and characterized by only a nasal response to ASA to those from subjects with both a nasal and a bronchial response to the same challenge.

METHODS

After their written consent, 74 subjects with mill to moderate AIA (16 male, mean age 45.3 years +/- 12.3 sd, mean basal FEV1 = 78.1% pred. +/- 6.2.4sd, FEV1 reversibility = 14.3% bsln +/- 2.1 ds after salbutamol 200 mcg) performed a NPT with L-ASA (total maximal dose 25 mg). Spirometry (FEV1), acoustic rinometry (nasal volume--VOL; nasal Resistance--Req; AR; TM Hood Lab., USA), and urinary LTE4 (Cayman Chemical, MI, USA, via Triturus System, Grifols, Spain) were checked in all subjects in basal conditions and 90' after NPT.

STATISTICS

t test between means +/- sd, assuming p < 0.05, and linear regression between all variables considered.

RESULTS

In 69 ASA-intolerant-asthmatics, mean FEV1 did not change significantly following NPT (78.7% pred. +/- 5.1 sd in baseline; 78.5% pred. +/- 4.1 sd after NPT, p = ns) even though in the presence of a significant decrease of VOL. (12.6 cm3 +/- 4.1 sd in baseline; 6.2 cm3 +/- 4.6 sd after NPT, p = 0.003); of a substantial increase in Req (0.9 cm H2O/l/min +/- 0.1 ds in baseline; 2.4 cmH2O/l/min +/- 0.2 after NPT, p = 0.04), and of urinary LTE4 excretion (333.0 pg/mg +/- 161.7 in bsln; 558.0 pg/mg +/- 171.690' after NPT with L-SA, p = 0.02). In only 5 subjects, the nasal response occurred concomitantly to a significant bronco-constriction after the NPT: mean FEV, changed from 77.9% pred. +/- 3.9 in bsln to 46.6% pred. +/- 4.3 after NPT (p < 0.001); mean VOL from 13.9 cm3 +/- 4.7 sd to 5.6 cm3 +/- 2.8 sd (p < 0.001); mean Req from 1.1 cmH2O/l/min +/- 0.2 in bsln to 2.5 cmH2O/l/min +/- 0.4 after NPT (p = 0.02) in these subjects. In ASA-intolerant bronchial responders, the severity of respiratory reactions proved related to the extent of urinary LTE4 response, which on the other hand, proved significantly higher than that observed in ASA-intolerant subjects with only nasal response and in ASA-tolerant subjects (LTE4 from 333.0 pg/mg +/- 161.7 in baseline up to 558.0 pg/mg +/- 171.6 90 min. following the NPT with L-ASA the nasal-responders, p = 0.04, but from 412.0 pg/mg +/- 102.8 in baseline up to 978.0 pg/mg +/- 108.7 after NPT in bronchial responders, p < 0.001 from baseline).

CONCLUSIONS

Nasal challenge with ASA affects significantly both nasal VOL and Req, and LTE4 excretion in all ASA-intolerant subjects. During the nasal challenge, severity of respiratory reactions proves associated with the highest basal LTE4 synthesis. This feature reflects a spectrum of respiratory tract reactions where cysteinil-LTs can play a specific diagnostic role.

Overproduction of N(epsilon)-(carboxymethyl)lysine-induced neovascularization in cultured choroidal explant of aged rat

N(epsilon)-(carboxymethyl)lysine (CML) adduct, a major structure of advanced glycation end product, facilitated production of immature microvessels from choroidal explant cultured in fibrin gel. The present study was investigated an action of endogenous CML adduct on neovascularization of cultured choroidal explants of aged Wistar rats with 9 months of age. The number of microvessels budded from explants was counted under optical microscope and used as an index of in vitro neovascularization. Aged choroidal explants increased the neovascularization in an age-dependent manner. Anti-CML antibody decreased age-facilitated neovascularization as well as CML-human serum albumin (HSA)-facilitated neovascularization. Both the aged explant and CML-HSA-treated explant significantly released vascular endothelial growth factor (VEGF), tumor necrosis factor (TNF) alpha and platelet-derived growth factor (PDGF)-B during the culture period. The release of TNF alpha and PDGF-B was earlier than that of VEGF from the aged explants. The antibodies against these factors decreased the CML-facilitated and age-facilitated neovascularization in the choroidal explants. The inhibitory capacity of anti-TNF alpha antibody was greater than those of anti-VEGF and anti-PDGF-B antibodies. In conclusion, endogenous CML adduct overproduced the neovascularization of the aged choroidal explant. The CML adduct releases TNF alpha which might induce the production and release of VEGF for the abnormal choroidal neovascularization in the patients of age-related macular degeneration.

Lys, Pro and Trp Are Critical Core Amino Acid Residues Recognized by FUM20, a Monoclonal Antibody against Serine Protease Pan-Fungal Allergens

BACKGROUND

Alkaline/vacuolar serine proteases comprise a major group of pan-fungal allergens from several prevalent airborne fungal species. It is of importance to characterize antigenic determinant(s) recognized by monoclonal antibodies against these major allergens.

METHODS

The antigenic determinant of fungal serine proteases recognized by a monoclonal antibody, FUM20, was analyzed by dot immunoassay of synthetic peptides immobilized on cellulose membrane. Results obtained were confirmed by wild-type recombinant protease and its mutants. The epitopes were mapped to the structure of serine proteases by molecular modeling.

RESULTS

A linear epitope encompassing 9 amino acids from Pen ch 18 ((6)EKNAPWGLA(14)) binds FUM20. The corresponding peptide ((5)AKGAPWGLA(13)) from Rho m 2 also binds FUM20. Substitution of K6, P9 or W10 with alanine in this peptide resulted in drastic loss of FUM20 binding. Rho m 2 mutants with single K6A, P9A, P9G, W10A or W10F substitute showed negative immunoblot reactivity against FUM20. However, the Rho m 2 K6R mutant can bind FUM20. Three-dimensional structural models of the FUM20 antigenic determinants on serine proteases were constructed. The lysine residue critical for FUM20 interaction is on the surface of the proteases and solvent accessible. The critical core residue proline is located at the beginning of an alpha-helix.

CONCLUSIONS

The lysine, proline and tryptophan residues located on the N-terminal region of fungal serine proteases are critical core amino acid residues recognized by FUM20, a monoclonal antibody against serine protease pan-fungal allergens. These findings advance our understanding of the antigenic structures responsible for the antigenicity of serine protease allergens.

Advanced glycation end product deposits in climatic droplet keratopathy

BACKGROUND

Climatic droplet keratopathy (CDK), known as spheroid degeneration of the cornea, is one of the most frequent degenerative corneal disorders affecting visual function. However, the histochemical nature of the deposits seen in CDK is still unclear.

AIM

To investigate the pathogenesis of CDK, we investigated the immunohistochemical localisation of advanced glycation end products (AGEs) in surgical specimens of CDK.

METHODS

Immunohistochemical localisation of N(epsilon)-(carboxymethyl)-l-lysine (CML), N(epsilon)-(carboxyethyl)-l-lysine (CEL), pyrraline, pentosidine and imidazolone was examined in three corneas with CDK, six corneas with bullous keratopathy and three corneas without any corneal diseases.

RESULTS

In all the specimens with CDK, immunoreactivity was strong in CML, moderate in pyrraline and pentosidine, and weak in imidazolone. Immunoreactivity was absent in CEL. In contrast, no immunoreactivity to CML, pyrraline, pentosidine, imidazolone or CEL was detected in corneas with bullous keratopathy, or in corneas without any corneal diseases.

CONCLUSIONS

CDK is caused by an aggregation of AGE-modified proteins. The result is consistent with etiological findings that ultraviolet irradiation and ageing, both of which are accelerators of AGE formation, are closely related to the development of CDK.

A Monoclonal Antibody to Hippuric Acid: An Improved Enzyme‐Linked Immunosorbent Assay for Biological Monitoring of Toluene Exposure

A novel monoclonal antibody (MAb) to hippuric acid (HA) was prepared using an HA analog, N-alpha-benzoyl-lysine, as an immunogen. An enzyme-linked immunosorbent assay (ELISA) for HA was established using the anti-HA MAb named HA01BL. When the specificity of the MAb was analyzed by the ELISA system, the MAb was revealed to be less reactive to methylhippuric acids and to be more specific to HA than previously reported polyclonal antibodies. The detection limit of HA by the ELISA was approximately 1 microg/mL. The urinary HA concentration determined by the ELISA system correlated well with that obtained by high performance liquid chromatography.

Lysine as a Critical Amino Acid for IgE Binding in Phl p 5b C Terminus

BACKGROUND

Allergens induce the formation of specific immunoglobulin (Ig)E and harbor at least two IgE-binding regions (epitopes) to facilitate crosslinking of basophilic or mast-cell-bound specific IgE antibodies. Studies mapping linear epitopes have shown that these regions often contain charged or hydrophobic amino acids. Nevertheless, these studies are hampered by limited significance due to the often conformational nature of IgE epitopes. This prompted us to study the role of lysines in the context of an intact 3-dimensional model.

METHODS

Major allergen Phl p 5b from timothy grass bears 12 lysines in its C-terminal half. Using site-directed mutagenesis, we substituted all 10 surface-exposed lysines by alanines.

RESULTS

Although structural integrity of the lysine-deficient mutant was not altered, IgE-binding capacity measured by ELISA inhibition tests and crosslinking activity in ex vivo basophil stimulation and in vivo skin prick tests were significantly diminished. Interestingly, binding of specific IgG antibodies was considerably less reduced by loss of lysines.

CONCLUSION

Lysine is an important amino acid for IgE binding in more than one epitope of major grass pollen allergen Phl p 5b C terminus. Allergenicity, but not IgG binding of the molecule, is substantially diminished by single amino acid substitutions without structural integrity being hampered.

Lysine methylation and ‘signaling memory’

A combination of various post-translational modifications regulates the formation of signaling networks in both the nucleus and the cytosol. Of these, lysine methylation provides a relatively stable marker on histones and contributes to the formation of a distinct pattern of histone-dependent gene regulation ('transcriptional memory'). Thus far, lysine methylation was considered to be nucleus specific; however, recent findings indicate that lysine methylation contributes to receptor-mediated signal transduction in the cytosol.

Formation of Nepsilon-(succinyl)lysine in vivo: a novel marker for docosahexaenoic acid-derived protein modification

Free radical-catalyzed peroxidation of docosahexaenoic acid (DHA, C22:6/omega-3) generates various lipid peroxidation products that covalently modify biomolecules such as proteins. Under a free radical-generating system, DHA significantly modified lysine residues in bovine serum albumin. Upon incubation of oxidized DHA with an amino-compound pyridoxamine or a lysine-containing peptide, N-propanoyl and N-succinyl adducts were determined to be the major modification products. The hydroperoxide levels in the oxidized DHA closely reflected the formation of the N(epsilon)-(succinyl)lysine (SUL) upon reaction with the peptide, indicating that the hydroperoxides of DHA represent a potential pathway for the formation of SUL. To detect the DHA-derived protein modification in vivo, we developed a monoclonal antibody (mAb2B12) specific to SUL and found that the antibody specifically reacts with the SUL moiety. The formation of SUL was then immunochemically demonstrated in the liver of mice fed with DHA followed by intraperitoneal injection of carbon tetrachloride (CCl(4)), a hepatic lipid peroxidation model. Immunoreactive materials with mAb2B12 were observed in the DHA + CCl(4) group, but were not significant in the control, DHA-alone, and CCl(4)-alone groups. These data suggest that the formation of DHA-derived adducts such as SUL may be implicated in the oxidative damage observed in DHA-enriched tissues.

Role of nitric oxide in hydroxyapatite-induced phagocytosis by murine macrophage cell line (RAW264.7)

The aim of this study was to determine the role of nitric oxide (NO) in hydroxyapatite (HA)-induced phagocytosis by a murine macrophage cell line (RAW264.7). The cells were incubated with HA particles at various incubation time and phagocytosis was assessed using phagocytic index (PI). NO production from the culture supernatants was determined by the Griess reagent. The inducible nitric oxide synthase (iNOS) expression was determined by Western blot. The particles were also incubated with cells pretreated with various concentrations of L-N(6)-(1-iminoethyl) lysine hydrochloride (L-NIL) or L-arginine. Latex beads were used as a control. Our results showed that macrophage phagocytosis induced by HA was higher than that induced by the beads. However, NO production by HA-stimulated cells was lower than that by bead-stimulated cells. iNOS expression in both bead- and HA-stimulated cells was observed expressed at 7, 15, 30, and 60 min. l-Arginine enhanced but l-NIL inhibited both phagocytosis and NO production by HA-stimulated cells. The results of the present study suggest that nitric oxide may play a crucial role in HA-induced phagocytosis by RAW264.7 cells.

Cytotoxicity of acetaldehyde-derived advanced glycation end-products (AA-AGE) in alcoholic-induced neuronal degeneration

BACKGROUND

The Maillard reaction that leads to the formation of advanced glycation end-products (AGEs) plays an important role in the pathogenesis of angiopathy in diabetic patients, in aging and in neurodegenerative processes. We hypothesize that acetaldehyde (AA), one of the main metabolites of alcohol, may be involved in alcohol-induced neurotoxicity in vivo by formation of AA-derived AGEs (AA-AGE) with brain proteins.

METHODS

AA-AGE-bovine serum albumin (BSA) and AA-AGE-rabbit serum albumin (RSA) were prepared as described previously. Antibody specific for AA-AGE was isolated from rabbit antiserum by affinity chromatography. Primary cortical neuronal cell cultures were prepared as described previously.

RESULTS

Incubation of cortical neurons with AA-AGE produced a dose-dependent increase in neuronal cell-death, and the neurotoxicity of AA-AGE was neutralized by the addition of an anti-AA-AGE specific antibody, but not by anti-N-ethyllysine (NEL) antibody. The AA-AGE epitope was detected in human brain of alcoholism.

CONCLUSIONS

We propose that the structural epitope AA-AGE is an important toxic moiety for neuronal cells in alcoholism.

Th-cytotoxic T-lymphocyte chimeric epitopes extended by Nepsilon-palmitoyl lysines induce herpes simplex virus type 1-specific effector CD8+ Tc1 responses and protect against ocular infection

Molecularly defined vaccine formulations capable of inducing antiviral CD8+ T-cell-specific immunity in a manner compatible with human delivery are limited. Few molecules achieve this target without the support of an appropriate immunological adjuvant. In this study, we investigate the potential of totally synthetic palmitoyl-tailed helper-cytotoxic-T-lymphocyte chimeric epitopes (Th-CTL chimeric lipopeptides) to induce herpes simplex virus type 1 (HSV-1)-specific CD8+ T-cell responses. As a model antigen, the HSV-1 glycoprotein B498-505 (gB498-505) CD8+ CTL epitope was synthesized in line with the Pan DR peptide (PADRE), a universal CD4+ Th epitope. The peptide backbone, composed solely of both epitopes, was extended by N-terminal attachment of one (PAM-Th-CTL), two [(PAM)2-Th-CTL], or three [(PAM)3-Th-CTL] palmitoyl lysines and delivered to H2b mice in adjuvant-free saline. Potent HSV-1 gB498-505-specific antiviral CD8+ T-cell effector type 1 responses were induced by each of the palmitoyl-tailed Th-CTL chimeric epitopes, irrespective of the number of lipid moieties. The palmitoyl-tailed Th-CTL chimeric epitopes provoked cell surface expression of major histocompatibility complex and costimulatory molecules and production of interleukin-12 and tumor necrosis factor alpha proinflammatory cytokines by immature dendritic cells. Following ocular HSV-1 challenge, palmitoyl-tailed Th-CTL-immunized mice exhibited a decrease of virus replication in the eye and in the local trigeminal ganglion and reduced herpetic blepharitis and corneal scarring. The rational of the molecularly defined vaccine approach presented in this study may be applied to ocular herpes and other viral infections in humans, providing steps are taken to include appropriate Th and CTL epitopes and lipid groups.

Mass Spectroscopic Characterization of Protein Modification by Malondialdehyde

Malondialdehyde (MDA), a naturally occurring dialdehyde produced in the membrane by lipid peroxidation, is a strong alkylating agent of primary amino groups. We recently raised a monoclonal antibody (mAb1F83) directed to the lipofuscin-like MDA--lysine adduct and demonstrated the presence of immunoreactivity to the antibody in the atherosclerotic lesions, in which intense positivity was associated primarily with macrophage-derived foam cells (Yamada et al., (2001) J. Lipid Res. 42, 1187-1196). To identify the structure of the epitope in the protein recognized by mAb1F83, in the present study, we exposed chain B from bovine insulin (insulin B chain) to MDA and characterized the MDA adducts by mass spectrometry. The MDA-modified insulin B chain was digested with V8 protease, and the resulting peptides were subjected to liquid chromatography--electrospray ionization--mass spectrometry (LC--ESI--MS/MS). The MS/MS analyses confirmed the formation of N-propenal- (+54 Da) and dihydropyridine-type (DHP, +134 Da) adducts in both Lys29 and the N-terminus of insulin B chain. The ELISA analysis of HPLC fractions of peptides, including the DHP adducts using mAb1F83, showed that the immunoreactivity of the DHP--lysine adduct was more significant than the DHP--N-terminus adduct. The results of this study chemically characterized that the MDA adducts such as DHP-type adducts generated in the epsilon-amino group of lysine and N-terminal amino acid residues in the protein and the structure of the epitope recognized by mAb1F83 were DHP--lysine adducts in protein.

Proteomic analysis of organ-specific post-translational lysine-acetylation and -methylation in mice by use of anti-acetyllysine and -methyllysine mouse monoclonal antibodies

Post-translational lysine-acetylation and -methylation are two major PTMs of lysine residues in proteins. Recently, we established pan-reactive anti-acetyllysine mouse mAbs, which can bind to Nepsilon-acetylated lysine residues in various contexts of amino acid sequences. In the present study, we established pan-reactive anti-methyllysine mouse mAbs comparable to the anti-acetyllysine ones. By using these anti-acetyllysine and -methyllysine antibodies, we found that the pattern of lysine-acetylated and -methylated proteins in mouse organs showed extreme variation from organ to organ. We selected brain and skeletal muscle as model cases to be further analyzed by 2-DE followed by Western blotting. In brain, alpha-tubulin at its basal level was found to be extremely acetylated; and alpha-enolase was shown to be a newly recognized possibly acetylated protein. NF-L protein, Hsc70, alpha-tubulin fragments, beta-actin, and brain-type creatine kinase were identified as putative lysine-methylated proteins in mouse brain. In skeletal muscle, lysine-methylation of alpha-actin and both lysine-acetylation and -methylation of muscle-type creatine kinase were found as novel putative lysine-modified proteins. The approach presented here might be useful to find novel disease markers and/or drug target molecules that would not be noticed by use of the traditional proteomic approach only.

Assessing acetylation of NF-kappaB

To achieve its full biological activity, NF-kappaB must undergo a variety of post-translational modifications, including acetylation. Acetylation plays a prominent role in regulating the nuclear action of NF-kappaB. The RelA subunit of NF-kappaB forms the major target of acetylation at several different sites. Acetylation of discrete lysine residues in RelA modulates distinct functions of NF-kappaB, including transcriptional activation, DNA binding, and assembly with its inhibitor IkappaBalpha. Here, we describe the experimental methods that have allowed the detection and functional analysis of acetylated forms of NF-kappaB. Acetylation of NF-kappaB can be studied both in vivo and in vitro. In vivo [3H]acetate labeling assays provides a useful, albeit rather insensitive, method for initial verification of acetylation of either over-expressed or endogenous subunits of NF-kappaB. A second valuable in vivo approach involves the use of anti-acetylated lysine antibodies for immunoblotting. However, the success of this approach varies with the specific antibody employed and the target protein studied. In vitro acetylation assays provide a rapid and sensitive method to validate the involvement of candidate histone acetyltransferases and to map the sites of acetylation. Anti-RelA antibodies that selectively react with site-specific acetylated forms of RelA are a singularly powerful tool for the study of NF-kappaB acetylation both in vivo and in vitro.

Histone H3 lysine 9 methylation and HP1gamma are associated with transcription elongation through mammalian chromatin

Methylation of histones modulates chromatin structure and function. Whereas methylation of histone H3 on lysines 4, 36, and 79 has been linked with gene activation, methylation of H3 on lysines 9 and 27 and histone H4 on lysine 20 is associated with heterochromatin and some repressed genes within euchromatin. Here, we show that H3K9 di- and trimethylation occur in the transcribed region of active genes in mammalian chromatin. This modification is dynamic, as it increases during activation of transcription and is rapidly removed upon gene repression. Heterochromatin Protein 1gamma (HP1gamma), a protein containing a chromo-domain that recognizes H3K9 methylation, is also present in the transcribed region of all active genes examined. Both the presence of HP1gamma and H3K9 methylation are dependent upon elongation by RNA polymerase II. These findings demonstrate novel roles for H3K9 methylation and HP1gamma in transcription activation.

Modeling the MHC class I pathway by combining predictions of proteasomal cleavage, TAP transport and MHC class I binding

Epitopes presented by major histocompatibility complex (MHC) class I molecules are selected by a multi-step process. Here we present the first computational prediction of this process based on in vitro experiments characterizing proteasomal cleavage, transport by the transporter associated with antigen processing (TAP) and MHC class I binding. Our novel prediction method for proteasomal cleavages outperforms existing methods when tested on in vitro cleavage data. The analysis of our predictions for a new dataset consisting of 390 endogenously processed MHC class I ligands from cells with known proteasome composition shows that the immunological advantage of switching from constitutive to immunoproteasomes is mainly to suppress the creation of peptides in the cytosol that TAP cannot transport. Furthermore, we show that proteasomes are unlikely to generate MHC class I ligands with a C-terminal lysine residue, suggesting processing of these ligands by a different protease that may be tripeptidyl-peptidase II (TPPII).

T-cell molecular mimicry in Chagas disease: identification and partial structural analysis of multiple cross-reactive epitopes between Trypanosoma cruzi B13 and cardiac myosin heavy chain

Chagas disease cardiomyopathy (CCC) is one of the few examples of post-infectious autoimmunity, where infectious episodes with an established pathogen, the protozoan parasite Trypanosoma cruzi, clearly triggers molecular mimicry-related target organ immune damage. CD4+ T-cell clones infiltrating hearts from CCC patients cross-reactively recognize human cardiac myosin, the major heart protein, and the immunodominant B13 protein from T. cruzi. Moreover, in vitro priming with B13 leads to the recovery of cardiac myosin cross-reactive T-cell clones. In order to identify cross-reactive epitopes between B13 protein and human cardiac myosin, we used B13 peptide S15.4, preferentially recognized by CCC patients, to establish a T-cell clone from an HLA-DQ7 individual. The B13 S15.4 peptide-specific CD4+ T-cell clone 3E5 was tested in proliferation assays against 15 Lys/His-substituted S15.4-derived peptides for TCR/HLA contact analysis. Together with previous HLA-binding data and molecular modeling of the HLA-DQ7-peptide S15.4 complex, Lys/His scanning analysis showed eight TCR/HLA contact positions. Clone 3E5 was also tested against 45 15-mer peptides from human beta-cardiac myosin heavy chain bearing the central HLA-DQ7 binding motif. Clone 3E5 recognized 13 peptides from cardiac myosin. The alignment of cross-reactive peptides in cardiac myosin showed very limited sharing of residues or side chains with similar chemical/structural features at aligned positions, indicative of a very degenerate TCR recognition pattern. The existence of degenerate intramolecular recognition, with multiple low-homology, cross-reactive epitopes in a single autoantigenic protein may have implications in increasing the magnitude of the autoimmune response in CCC and other autoimmune diseases.

Immunohistochemical localization of advanced glycation end products in pinguecula

BACKGROUND

Advanced glycation end products (AGEs) are known to be deposited in the target organ of ageing. In addition, the deposition of AGEs accelerate the process of ageing. We investigated the immunohistochemical localization of AGEs in pinguecula, one of the ocular changes related with ageing process.

METHODS

Surgical specimens of conjunctiva with or without pinguecula were prepared from nine patients, respectively. Immunohistochemical localization of AGEs was investigated using monoclonal antibodies to N(epsilon)-(carboxymethyl)lysine, pentosidine, imidazolone, and pyrraline.

RESULTS

Moderate to strong immunoreactivities to AGEs were detected in the subepithelial amorphous deposits of all the surgical specimens with pinguecula. In contrast, no or weak immunoreactivities to AGEs were detected in the surgical specimens without pinguecula.

CONCLUSIONS

Pinguecula is an aggregation of AGEs-modified proteins. The presence of pinguecula would be an index of local irradiation of ultraviolet rays and decreased antioxidant activities.

Conventional antibody against Nepsilon-(carboxymethyl)lysine (CML) shows cross-reaction to Nepsilon-(carboxyethyl)lysine (CEL): immunochemical quantification of CML with a specific antibody

Immunological strategies for the detection of N(epsilon)-(carboxymethyl)lysine (CML), one of the major antigenic structures of advanced glycation end products (AGE), are widely applied to demonstrate the contribution of CML to the pathogeneses of diabetic complications and atherosclerosis. Recent studies have indicated that methylglyoxal (MG), which is generated intracellularly through the Embden-Meyerhof and polyol pathways, reacts with proteins to form MG-derived AGE structures such as N(epsilon)-(carboxyethyl)lysine (CEL). In order to accurately measure the CML contents of the proteins by means of an immunochemical method, we prepared CML-specific antibodies since conventionally prepared polyclonal anti-CML antibody and monoclonal anti-CML antibody (6D12) cross-reacted with CEL. To prepare polyclonal CML-specific antibody, CML-keyhole limpet hemocyanin (CML-KLH) were immunized with rabbit and CEL-reactive antibody was removed by CEL-conjugated affinity chromatography. Monoclonal antibody specific for CML (CMS-10) was obtained by immunization with CML-KLH, followed by successive screening according to CML-bovine serum albumin (CML-BSA)-positive but CEL-BSA-negative criteria. Both polyclonal CML-specific antibody and CMS-10 significantly reacted with CML-proteins but not with CEL-proteins. It is likely therefore that these antibodies can recognize the difference of one methyl group between CML and CEL. Moreover, CMS-10 significantly reacted with BSA modified with several aldehydes and its reactivity was highly correlated with the CML content, which was determined by high performance liquid chromatography, whereas 6D12 showed a low correlation. These results indicate that CMS-10 can be used to determine the CML contents of modified proteins in a more specific way.

Development of capture assays for different modifications of human low-density lipoprotein

Antibodies to malondialdehyde (MDA)-modified low-density lipoprotein (LDL), copper-oxidized LDL (oxLDL), Nepsilon(carboxymethyl) lysine (CML)-modified LDL, and advanced glycosylation end product (AGE)-modified LDL were obtained by immunization of rabbits with in vitro-modified human LDL preparations. After absorption of apolipoprotein B (ApoB) antibodies, we obtained antibodies specific for each modified lipoprotein with unique patterns of reactivity. MDA-LDL antibodies reacted strongly with MDA-LDL and also with oxLDL. CML-LDL antibodies reacted strongly with CML-LDL and also AGE-LDL. oxLDL antibodies reacted with oxLDL but not with MDA-LDL, and AGE-LDL antibodies reacted with AGE-LDL but not with CML-LDL. Capture assays were set with each antiserum, and we tested their ability to capture ApoB-containing lipoproteins isolated from precipitated immune complexes (IC) and from the supernatants remaining after IC precipitation (free lipoproteins). All antibodies captured lipoproteins contained in IC more effectively than free lipoproteins. Analysis of lipoproteins in IC by gas chromatography-mass spectrometry showed that they contained MDA-LDL and CML-LDL in significantly higher concentrations than free lipoproteins. A significant correlation (r=0.706, P<0.019) was obtained between the MDA concentrations determined by chemical analysis and by the capture assay of lipoproteins present in IC. In conclusion, we have developed capture assays for different LDL modifications in human ApoB/E lipoprotein-rich fractions isolated from precipitated IC. This approach obviates the interference of IC in previously reported modified LDL assays and allows determination of the degree of modification of LDL with greater accuracy.

Reduction of Cerebral Infarction in Stroke-Prone Spontaneously Hypertensive Rats by Statins Associated With Amelioration of Oxidative Stress

Background and Purpose— This study aimed to clarify the effect of statins on spontaneous stroke and to examine the antioxidative effect in artificial transient middle cerebral artery occlusion (tMCAO).

Methods— Stroke-prone spontaneous hypertensive rats (SHR-SP) were treated with pitavastatin, atorvastatin, simvastatin, or vehicle for 4 weeks. Physiological parameters, serum lipids, and infarct volumes were examined. The markers for oxidative stresses on lipids and DNA were immunohistochemically detected in vehicle-treated or simvastatin-treated SHR-SP with tMCAO.

Results— Atorvastatin and simvastatin decreased infarct volumes, with simvastatin most effective. Simvastatin significantly reduced immunoreactivities for oxidative stress markers for lipids and DNA in neurons after tMCAO.

Conclusions— The results suggest that the antioxidative properties of statins may be implicated in their beneficial effects against neuronal damage in cerebral ischemia.

Development of a PAN-Specific, Affinity-Purified Anti-acetylated Lysine Antibody for Detection, Identification, Isolation, and Intracellular Localization of Acetylated Protein

Acetylation on the lysine residue is an important event of posttranslational modification of proteins. In this study, we developed a simple method to produce and to affinity purify the specific anti-acetylated lysine polyclonal antibody, which is useful for the detection, identification, isolation, and intracellular localization of acetylated proteins on the lysine residues. We utilized the chemically acetylated hemocyanin of keyhole limpets (KLH) as an immunogen to raise the immune serum and to isolate the population of the acetylated lysine specific antibody using the immobilized acetylated lysine as immunoaffinity-ligand. The isolated antibody was tested to be useful for ELISA, immunoblotting detection, immunofluorescent localization, and affinity isolation of the acetylated proteins.

Cellular antitumor immune response to a branched lysine multiple antigenic peptide containing epitopes of a common tumor-specific antigen in a rat glioma model

Human malignant gliomas contain epidermal growth factor receptor (EGFR) gene mutations that encode tumor-associated antigens (TAAs) that can be targeted using immunological techniques. One EGFR mutant gene (EGFRvIII) encodes a protein with an epitope that is not found in normal tissues. A number of studies have focused on this unique epitope as a potential target for tumor vaccines. In the present study, we examined the cellular immune effects of a peptide containing multiple copies of the unique EGFRvIII epitope linked together by way of a lysine bridge. Fischer rats were vaccinated with an EGFRvIII multiple antigenic peptide (MAP). While vaccination produced a humoral immune response, anti-MAP antibody production was not accompanied by expression of the Th2 response cytokine IL-4. In MAP/GM-CSF vaccinated animals, a cellular immune response was detected in association with the appearance of CD4+ and CD8+ T cells at the tumor site. Splenocytes and CD8+ T cells from vaccinated rats produced the Th1 cytokine IFN-gamma in vitro in response to stimulation by rat glioma cells expressing EGFRvIII, but not by those expressing wild-type EGFR. MAP vaccine also induced a specific lytic antitumor CTL immune response against F98 glioma cells expressing EGFRvIII, but not against F98 cells expressing either wild-type EGFR or no receptor. The in vivo growth of F98(EGFRvIII) cells was attenuated in vaccinated rats; whereas, growth of F98(EGFR) cells was not. The median survival of vaccinated rats was increased 72% over that of unvaccinated controls challenged with intracerebral F98(EGFRvIII) tumor implants. Therefore, MAP vaccination produced a predominantly cellular antitumor immune response directed against F98 gliomas expressing the EGFRvIII target antigen. The potent immunosuppressive effects of F98 glioma cells mimic the human disease and make this particular tumor model useful for studying immunotherapeutic approaches to malignant gliomas.

Two immunochemical assays to measure advanced glycation end-products in serum from dialysis patients

Advanced glycation end-products are uremic toxins that accumulate in the serum and tissues of patients with chronic renal failure. Here, we established two enzyme-linked immunosorbent assays (ELISAs) for N

Identification and quantification of N(epsilon)-(Hexanoyl)lysine in human urine by liquid chromatography/tandem mass spectrometry

The identification and quantification of N(epsilon)-(hexanoyl)lysine (N(epsilon)-HEL), which was found from the reactions between lipid hydroperoxide and lysine, from human urine was examined using liquid chromatography/tandem mass spectrometry (LC/MS/MS). The N(epsilon)-HEL in the partially purified urine fraction was identified using LC/MS/MS by several approaches including precursor/product ion scans. The peak found by the multiple-reaction monitoring (MRM) of the collision-induced fragmentation of N(epsilon)-HEL was clearly observed in urine, and the elution position coincided with the synthetic standard N(epsilon)-HEL. The product, estimated N(epsilon)-HEL, was absorbed by a specific antibody to N(epsilon)-HEL. Moreover, N(alpha)-HEL, one of the plausible hexanoyl adducts from the reaction between the N(alpha) moiety of L-lysine and the peroxidized lipid, was hardly detected in urine samples, suggesting that the origin of the N(epsilon)-HEL is the peroxidized lipid-modified proteins but not artificial hexanoylated L-lysine. Using the MRM technique, the amount of urinary N(epsilon)-HEL from the control subjects (observed healthy) was estimated to be 1.58 +/- 0.23 mumol/mol of creatinine. A comparative study of the urinary N(epsilon)-HEL with an oxidative stress marker, 8-oxo-7,8-dihydro-2'-deoxyguanosine, showed a high correlation (r = 0.844) between the two biomarkers. Furthermore, the quantification of N(epsilon)-HEL in the control and diabetic urines revealed that the urinary N(epsilon)-HEL from diabetic subjects (3.21 +/- 0.65 mumol/mol of creatinine) was significantly higher than that from the control subjects.

Differential dynamics of histone H3 methylation at positions K4 and K9 in the mouse zygote

Background

In the mouse zygote the paternal genome undergoes dramatic structural and epigenetic changes. Chromosomes are decondensed, protamines replaced by histones and DNA is rapidly and actively demethylated. The epigenetic asymmetry between parental genomes remains at least until the 2-cell stage suggesting functional differences between paternal and maternal genomes during early cleavage stages.

Results

Here we analyzed the timing of histone deposition on the paternal pronucleus and the dynamics of histone H3 methylation (H3/K4mono-, H3/K4tri- and H3/K9di-methylation) immediately after fertilization. Whereas maternal chromatin maintains all types of histone H3 methylation throughout the zygotic development, paternal chromosomes acquire new and unmodified histones shortly after fertilization. In the following hours we observe a gradual increase in H3/K4mono-methylation whereas H3/K4tri-methylation is not present before latest pronuclear stages. Histone H3/K9di-methylation is completely absent from the paternal pronucleus, including metaphase chromosomes of the first mitotic stage.

Conclusion

Parallel to the epigenetic asymmetry in DNA methylation, chromatin modifications are also different between both parental genomes in the very first hours post fertilization. Whereas methylation at H3/K4 gradually becomes similar between both genomes, H3/K9 methylation remains asymmetric.

Definition of the fine specificity of the monoclonal antibody 81D4: its reactivity with lysine and polyamine isopeptide cross-links

The 81D1C2 monoclonal antibody (Mab) directed against the Nepsilon-(gamma-L-glutamyl)-L-lysine isopeptide was found to cross-react on Enzyme Immuno Assay (EIA) with acylated lysines. Using a differential screening EIA procedure, a new Mab 81D4 was selected, which did not cross-react with acylated lysines but exhibited strong reactivity with Nepsilon-(gamma-L-glutamyl)-L-lysine formed by covalently coupling the gamma-carboxyl of NalphaCBZ OtBu glutamic acid to epsilon-NH2 derivatized microtiter plates. When Nepsilon-(gamma-L-glutamyl)-L-lysine isopeptides were generated on gamma-carboxyl derivatized plates, only lysine isopeptides with blocked alpha-amines were reactive, regardless of whether the bond formed by the amine blocking agent was a carbamate with carbobenzyloxychloride or an amide with acetic anhydride. The 81D4 Mab showed little or no affinity for free Nepsilon-(gamma-L-glutamyl)-L-lysine (IC50>5 mM), for N1 or N4 mono(gamma-Poly L-glutamyl)putrescine, and for N1 mono(gamma-Poly L-glutamyl)spermidine (IC50>5 mM). However, when these same isopeptides were synthesized as cross-links between two protein chains--Nepsilon-(gamma-L-glutamyl)-L-lysine between Poly L-glutamate and Poly L-lysine; N1N4 -bis(gamma-Poly L-glutamyl)putrescine, N1N8 -bis(gamma-Poly L-glutamyl)spermidine between Poly-L-glutamate chains--very good reactivity was observed (IC50 400 microM for lysine; 80 microM for putrescine and spermidine). In addition to the chemically synthesized isopeptide cross-links that were recognized by this Mab, the naturally occurring Nepsilon-(ã-L-glutamyl)-L-lysine isopeptide cross-links in D-dimer, which are formed by the action of plasma transglutaminase (Factor XIII) on fibrin, were also detected on immunoblots using 81D4 as the primary antibody.

Advanced glycoxidation end products in commonly consumed foods

OBJECTIVE

Advanced glycoxidation end products (AGEs), the derivatives of glucose-protein or glucose-lipid interactions, are implicated in the complications of diabetes and aging. The objective of this article was to determine the AGE content of commonly consumed foods and to evaluate the effects of various methods of food preparation on AGE production.

DESIGN

Two-hundred fifty foods were tested for their content in a common AGE marker (epsilon)N-carboxymethyllysine (CML), using an enzyme-linked immunosorbent assay based on an anti-CML monoclonal antibody. Lipid and protein AGEs were represented in units of AGEs per gram of food.

RESULTS

Foods of the fat group showed the highest amount of AGE content with a mean of 100+/-19 kU/g. High values were also observed for the meat and meat-substitute group, 43+/-7 kU/g. The carbohydrate group contained the lowest values of AGEs, 3.4+/-1.8 kU/g. The amount of AGEs present in all food categories was related to cooking temperature, length of cooking time, and presence of moisture. Broiling (225 degrees C) and frying (177 degrees C) resulted in the highest levels of AGEs, followed by roasting (177 degrees C) and boiling (100 degrees C).

CONCLUSIONS

The results indicate that diet can be a significant environmental source of AGEs, which may constitute a chronic risk factor for cardiovascular and kidney damage.

Increased accumulation of the glycoxidation product Nepsilon-(carboxymethyl)lysine in hearts of diabetic patients: generation and characterisation of a monoclonal anti-CML antibody

Heart failure is a condition closely linked to diabetes. Hyperglycaemia amplifies the generation of a major advanced glycation end product Nepsilon-(carboxymethyl)lysine (CML), which has been associated with the development of vascular and inflammatory complications. An increased accumulation of CML in hearts of diabetic patients may be one of the mechanisms related to the high risk of heart failure. Therefore, we investigated the localization of CML in diabetic hearts. To investigate the presence and accumulation of CML in tissues, a monoclonal anti-CML antibody was generated and characterised. With this novel monoclonal antibody against CML, the localization of CML was investigated by immunohistochemistry, in heart tissue of controls (n = 9) and heart tissue of diabetic patients (n = 8) without signs of inflammation or infarction. In addition, in the same subjects we studied the presence of CML in renal and lung tissues. CML staining was approximately sixfold higher in hearts from diabetic patients as compared to control hearts (2.0 +/- 0.3 and 0.3 +/- 0.2 A.U., respectively, P < 0.01). CML deposition was localized in the small intramyocardial arteries in endothelial cells and smooth muscle cells, but not in cardiomyocytes. These arteries did not show morphological abnormalities. The intensity of staining between arteries at the epicardial, midcardial and endocardial side did not vary significantly within patients. In renal tissues, CML staining was most prominent in tubules and in atherosclerotic vessels, without differences in intensity between controls and diabetic patients. In non-infected lungs, no CML was detected. In conclusion, CML adducts are abundantly present in small intramyocardial arteries in the heart tissue of diabetic patients. The accumulation of CML in diabetic hearts may contribute to the increased risk of heart failure in hyperglycaemia.

Autoantibodies AgainstN-Homocysteinylated Proteins in Humans

BACKGROUND AND PURPOSE

Homocysteine (Hcy)-thiolactone mediates protein N-homocysteinylation in humans. Protein N-linked Hcy comprises a major pool of Hcy in human blood, greater that the "total" Hcy pool. N-homocysteinylated proteins are structurally different, compared with native proteins, and are thus likely to be recognized as neoself antigens and induce an autoimmune response. This study was undertaken to provide evidence for anti-Nepsilon-Hcy-Lys-protein antibody and to examine associations between the antibody level, Hcy, and stroke in humans.

METHODS

ELISA was used to quantify anti-Nepsilon-Hcy-Lys-protein antibodies in human serum.

RESULTS

We found that autoantibodies that specifically recognize Nepsilon-Hcy-Lys epitope on Hcy-containing proteins occur in humans. Serum levels of anti-Nepsilon-Hcy-Lys-protein autoantibodies positively correlate with plasma total Hcy levels, but not with plasma cysteine or methionine levels. In a group of exclusively male patients with stroke, mean level of anti-Nepsilon-Hcy-Lys-protein autoantibodies was approximately 50% higher than in a group of healthy subjects.

CONCLUSIONS

These findings support a hypothesis that Nepsilon-Hcy-Lys-protein is a neoself antigen, which may contribute to immune activation, an important modulator of atherogenesis.

Three dimensional analysis of histone methylation patterns in normal and tumor cell nuclei

Histone modifications represent an important epigenetic mechanism for the organization of higher order chromatin structure and gene regulation. Methylation of position-specific lysine residues in the histone H3 and H4 amino termini has linked with the formation of constitutive and facultative heterochromatin as well as with specifically repressed single gene loci. Using an antibody, directed against dimethylated lysine 9 of histone H3 and several other lysine methylation sites, we visualized the nuclear distribution pattern of chromatin flagged by these methylated lysines in 3D preserved nuclei of normal and malignant cell types. Optical confocal serial sections were used for a quantitative evaluation. We demonstrate distinct differences of these histone methylation patterns among nuclei of different cell types after exit of the cell cycle. Changes in the pattern formation were also observed during the cell cycle. Our data suggest an important role of methylated histones in the reestablishment of higher order chromatin arrangements during telophase/early G1. Cell type specific histone methylation patterns are possibly casually involved in the formation of cell type specific heterochromatin compartments, composed of (peri)centromeric regions and chromosomal subregions from neighboring chromosomes territories, which contain silent genes.

Overproduction of N.EPSILON.-(Carboxymethyl)lysine-Induced Neovascularization in Cultured Choroidal Explant of Streptozotocin-Diabetic Rat

Action of N(epsilon)-(carboxymethyl)lysine (CML) adduct, an advanced glycation end product, was investigated on neovascularization of cultured choroidal explants in streptozotocin (STZ)-diabetic rat. The choroidal explants of early (4 weeks after an injection of 60 mg/kg STZ) and advanced (8 months after the STZ injection) diabetic rats, and age-matched normal rats were cultured in fibrin gel with Dulbecco's modified Eagle medium containing fetal bovine serum. The number of budded microvessel-like structures was counted and used as an index of in vitro neovascularization. Choroidal explants in the early diabetic stage released vascular endothelial growth factor (VEGF) and tended to increase tumor necrosis factor (TNF) alpha and platelet-derived growth factor (PDGF)-B, and concomitantly facilitated growth of sprout and buds, compared to the normal control. When choroidal explants were stimulated with CML-human serum albumin (HSA), its releasing effect was in the order VEGF>TNFalpha>PDGF-B. CML-HSA and CML-bovine serum albumin augmented the neovascularization in the cultured diabetic explant and their actions did not virtually differ. A monoclonal anti-CML antibody (6D12) inhibited the neovascularization in the advanced diabetes greater than that in the early diabetes. Inhibitory actions of anti-VEGF and anti-TNFalpha antibodies on the neovascularization were similar to that of the anti-CML antibody in the diabetes. In conclusion, CML adducts were accumulated and over-produced the actions of VEGF, TNFalpha and PDGF-B in the choroidal explant during diabetes in an age-dependent manner. TNFalpha and VEGF are likely to play a predominant role for the CML-induced choroidal neovascularization.