Limited T-cell receptor beta-chain heterogeneity among interleukin 2 receptor-positive synovial T cells suggests a role for superantigen in rheumatoid arthritis

Molecular characterization of enterotoxin genes in methicillin-resistant S. aureus isolated from food poisoning outbreaks in Egypt

BACKGROUND

Staphylococcus aureus (S. aureus), especially methicillin-resistant S. aureus (MRSA), is a known disease-causing bacteria with many associated health hazards. Staphylococcal food poisoning can result from staphylococcal enterotoxins (SEs).

METHODS

In this study, 50 S. aureus isolates were isolated from the gastrointestinal tract (GIT) clinical samples of patients with food poisoning in clinical laboratories at Mansoura University Hospital, Egypt. For determination their antibiogram, these isolates were tested for antimicrobial sensitivity against 12 antimicrobial agents using the agar disk diffusion test. After DNA extraction from the isolates, conventional polymerase chain reaction (PCR) was used to detect mecA and SEs genes.

RESULTS

As a result, all isolates were ampicillin and cefoxitin-resistant, while 86% (43 of 50) of the tested isolates exhibited multidrug resistance (MDR). In contrast, the highest sensitivity was confirmed against vancomycin, linezolid and quinolones, namely ciprofloxacin and norfloxacin. Although 100% of the isolates were mecA positive, staphylococcal enterotoxin genes set-A, set-B, set-C, set-G, set-M, and set-O genes were detected in 56%, 20%, 8%, 32%, 16%, and 24%, of the tested isolates, respectively. Finally, isolates encompassing SEs genes were used to validate a microarray chip, indicating its potential for a better methodological approach for detecting and identifying SEs in human samples.

CONCLUSION

The genotypic findings of this study may help explain the enterotoxigenic patterns in S. aureus among Egyptian patients with food poisoning.

Application of T-cell receptor repertoire as a novel monitor in dynamic tracking and assessment: A cohort-study based on RA patients

T-cell receptor repertoire (TCRR) sequencing has been widely applied in many fields as a novel tool. This study explored characteristics of TCRR in detail with a cohort of 598 rheumatoid arthritis (RA) patients before and after anti-rheumatic treatments. We highlighted the abnormal TCRR distribution in RA characterized by decreased diversity and increased proportion of hyperexpanded clones (HECs), which was potentially attributed to skewed usage of global V/J segments but not a few certain ones. Enriched motifs analysis in RA community demonstrated the huge heterogeneity of CDR3 sequences, so that individual factors are strongly recommended to be taken into consideration when it comes to clinical application of TCRR. Disease-modifying antirheumatic drugs (DMARDs) can regulate immune system through recovery of TCRR richness to relieve symptoms. Remarkably, sensitive gene profile and advantageous gene profile were identified in this study as new biomarkers for different DMARDs regimens.

Examining pathogenic concepts of autoimmune hepatitis for cues to future investigations and interventions

BACKGROUND

Multiple pathogenic mechanisms have been implicated in autoimmune hepatitis, but they have not fully explained susceptibility, triggering events, and maintenance or escalation of the disease. Furthermore, they have not identified a critical defect that can be targeted. The goals of this review are to examine the diverse pathogenic mechanisms that have been considered in autoimmune hepatitis, indicate investigational opportunities to validate their contribution, and suggest interventions that might evolve to modify their impact. English abstracts were identified in PubMed by multiple search terms. Full length articles were selected for review, and secondary and tertiary bibliographies were developed. Genetic and epigenetic factors can affect susceptibility by influencing the expression of immune regulatory genes. Thymic dysfunction, possibly related to deficient production of programmed cell death protein-1, can allow autoreactive T cells to escape deletion, and alterations in the intestinal microbiome may help overcome immune tolerance and affect gender bias. Environmental factors may trigger the disease or induce epigenetic changes in gene function. Molecular mimicry, epitope spread, bystander activation, neo-antigen production, lymphocytic polyspecificity, and disturbances in immune inhibitory mechanisms may maintain or escalate the disease. Interventions that modify epigenetic effects on gene expression, alter intestinal dysbiosis, eliminate deleterious environmental factors, and target critical pathogenic mechanisms are therapeutic possibilities that might reduce risk, individualize management, and improve outcome. In conclusion, diverse pathogenic mechanisms have been implicated in autoimmune hepatitis, and they may identify a critical factor or sequence that can be validated and used to direct future management and preventive strategies.

An ELISA Lab-on-a-Chip (ELISA-LOC)

Laminated object manufacturing (LOM) technology using polymer sheets is an easy and affordable method for rapid prototyping of Lab-on-a-Chip (LOC) systems. It has recently been used to fabricate a miniature 96 sample ELISA lab-on-a-chip (ELISA-LOC) by integrating the washing step directly into an ELISA plate. LOM has been shown to be capable of creating complex 3D microfluidics through the assembly of a stack of polymer sheets with features generated by laser micromachining and by bonding the sheets together with adhesive. A six layer ELISA-LOC was fabricated with an acrylic (poly(methyl methacrylate) (PMMA)) core and five polycarbonate layers micromachined by a CO(2) laser with simple microfluidic features including a miniature 96-well sample plate. Immunological assays can be carried out in several configurations (1 × 96 wells, 2 × 48 wells, or 4 × 24 wells). The system includes three main functional elements: (1) a reagent loading fluidics module, (2) an assay and detection wells plate, and (3) a reagent removal fluidics module. The ELISA-LOC system combines several biosensing elements: (1) carbon nanotube (CNT) technology to enhance primary antibody immobilization, (2) sensitive ECL (electrochemiluminescence) detection, and (3) a charge-coupled device (CCD) detector for measuring the light signal generated by ECL. Using a sandwich ELISA assay, the system detected Staphylococcal enterotoxin B (SEB) at concentrations as low as 0.1 ng/ml, a detection level similar to that reported for conventional ELISA. ELISA-LOC can be operated by a syringe and does not require power for operation. This simple point-of-care (POC) system is useful for carrying out various immunological assays and other complex medical assays without the laboratory required for conventional ELISA, and therefore may be more useful for global healthcare delivery.

Microbial Infection and Rheumatoid Arthritis

Rheumatoid arthritis (RA) is a complex autoimmune disease affecting 1–2% of general worldwide population. The etiopathogenesis of RA involves the interplay of multiple genetic risk factors and environmental triggers. Microbial infections are believed to play an important role in the initiation and perpetuation of RA. Recent clinical studies have shown the association of microbial infections with RA. Accumulated studies using animal models have also found that microbial infections can induce and/or exaggerate the symptoms of experimental arthritis. In this review, we have identified the most common microbial infections associated with RA in the literature and summarized the current evidence supporting their pathogenic role in RA. We also discussed the potential mechanisms whereby infection may promote the development of RA, such as generation of neo-autoantigens, induction of loss of tolerance by molecular mimicry, and bystander activation of the immune system.

An automated point-of-care system for immunodetection of staphylococcal enterotoxin B

An automated point-of-care (POC) immunodetection system for immunological detection of staphylococcal enterotoxin B (SEB) was designed, fabricated, and tested. The system combines several elements: (i) enzyme-linked immunosorbent assay-lab-on-a-chip (ELISA-LOC) with fluidics, (ii) a charge-coupled device (CCD) camera detector, (iii) pumps and valves for fluid delivery to the ELISA-LOC, (iv) a computer interface board, and (v) a computer for controlling the fluidics, logging, and data analysis of the CCD data. The ELISA-LOC integrates a simple microfluidic system into a miniature 96-well sample plate, allowing the user to carry out immunological assays without a laboratory. The analyte is measured in a sandwich ELISA assay format combined with a sensitive electrochemiluminescence (ECL) detection method. Using the POC system, SEB, a major foodborne toxin, was detected at concentrations as low as 0.1 ng/ml. This is similar to the reported sensitivity of conventional ELISA. The open platform with simple modular fluid delivery automation design described here is interchangeable between detection systems, and because of its versatility it can also be used to automate many other LOC systems, simplifying LOC development. This new POC system is useful for carrying out various immunological and other complex medical assays without a laboratory and can easily be adapted for high-throughput biological screening in remote and resource-poor areas.

Lab-on-a-chip for label free biological semiconductor analysis of staphylococcal enterotoxin B

We describe a new lab-on-a-chip (LOC) which utilizes a biological semiconductor (BSC) transducer for label free analysis of Staphylococcal Enterotoxin B (SEB) (or other biological interactions) directly and electronically. BSCs are new transducers based on electrical percolation through a multi-layer carbon nanotube-antibody network. In BSCs the passage of current through the conductive network is dependent upon the continuity of the network. Molecular interactions within the network, such as binding of antigens to the antibodies, disrupt the network continuity causing increased resistance of the network. For the fabrication of a BSC based detector, we combined several elements: (1) BSC transducers for direct detection, (2) LOC for flow through continuous measurements, (3) a digital multimeter with computer connection for data logging, (4) pumps and valves for fluid delivery, and (5) a computer for fluid delivery control and data analysis. Polymer lamination technology was used for the fabrication of a four layer LOC for BSC detection, the BSC on the chip is fabricated by immobilizing pre-functionalized single-walled carbon nanotubes (SWNTs)-antibody complex directly on the PMMA surface of the LOC. SEB samples were loaded into the device using a peristaltic pump and the change in resistance resulting from antibody-antigen interactions was continuously monitored and recorded. Binding of SEB rapidly increases the BSC electrical resistance. SEB in buffer was assayed with limit of detection (LOD) of 5 ng mL(-1) at a signal to baseline (S/B) ratio of 2. A secondary antibody was used to verify the presence of the SEB captured on the surface of the BSC and for signal amplification. The new LOC system permits rapid detection and semi-automated operation of BSCs. Such an approach may enable the development of multiple biological elements "Biological Central Processing Units (CPUs)" for parallel processing and sorting out automatically information on multiple analytes simultaneously. Such an approach has potential use for point-of-care medical and environmental testing.

Simultaneous detection of seven staphylococcal enterotoxins: development of hydrogel biochips for analytical and practical application

A method of simultaneous analysis of staphylococcal enterotoxins using hydrogel-based microarrays (biochips) has been developed. The method allows simultaneous quantitative detection of seven enterotoxins: A, B, C1, D, E, G, and I in a single sample. The development of the method included expression and purification of recombinant toxins, production of panels of monoclonal antibodies (mAbs) against the toxins, and design and manufacturing of an experimental biochip for the screening of mAbs and selection of optimal pairs of primary and secondary antibodies for each toxin. The selected mAbs have high affinity toward their targets and no cross-reactivity with unrelated enterotoxins. Finally, a diagnostic biochip was designed for quantitative analysis of the toxins, and the analytical protocols were optimized. The sensitivity of the detection reached 0.1-0.5 ng/mL, depending on the type of enterotoxin. The evaluation of the resulting biochip using spiked food samples demonstrated that the sensitivity, specificity, and reproducibility of the proposed test system fully satisfy the requirements for traditional immunoanalytical systems. The diagnostic biochips manufactured on reflecting metal-coated surfaces shortened the time of analysis from 17 to 2 h without loss of sensitivity. The method was successfully tested on samples of food and biological media.

Nanoliter multiplex PCR arrays on a SlipChip

The SlipChip platform was tested to perform high-throughput nanoliter multiplex PCR. The advantages of using the SlipChip platform for multiplex PCR include the ability to preload arrays of dry primers, instrument-free sample manipulation, small sample volume, and high-throughput capacity. The SlipChip was designed to preload one primer pair per reaction compartment and to screen up to 384 different primer pairs with less than 30 nanoliters of sample per reaction compartment. Both a 40-well and a 384-well design of the SlipChip were tested for multiplex PCR. In the geometries used here, the sample fluid was spontaneously compartmentalized into discrete volumes even before slipping of the two plates of the SlipChip, but slipping introduced additional capabilities that made devices more robust and versatile. The wells of this SlipChip were designed to overcome potential problems associated with thermal expansion. By using circular wells filled with oil and overlapping them with square wells filled with the aqueous PCR mixture, a droplet of aqueous PCR mixture was always surrounded by the lubricating fluid. In this design, during heating and thermal expansion, only oil was expelled from the compartment and leaking of the aqueous solution was prevented. Both 40-well and 384-well devices were found to be free from cross-contamination, and end point fluorescence detection provided reliable readout. Multiple samples could also be screened on the same SlipChip simultaneously. Multiplex PCR was validated on the 384-well SlipChip with 20 different primer pairs to identify 16 bacterial and fungal species commonly presented in blood infections. The SlipChip correctly identified five different bacterial or fungal species in separate experiments. In addition, the presence of the resistance gene mecA in methicillin resistant Staphylococcus aureus (MRSA) was identified. The SlipChip will be useful for applications involving PCR arrays and lays the foundation for new strategies for diagnostics, point-of-care devices, and immobilization-based arrays.

Biological semiconductor based on electrical percolation

We have developed a novel biological semiconductor (BSC) based on electrical percolation through a multilayer three-dimensional carbon nanotube-antibody bionanocomposite network, which can measure biological interactions directly and electronically. In electrical percolation, the passage of current through the conductive network is dependent upon the continuity of the network. Molecular interactions, such as binding of antigens to the antibodies, disrupt the network continuity causing increased resistance of the network. A BSC is fabricated by immobilizing a prefunctionalized single-walled carbon nanotubes (SWNTs)-antibody bionanocomposite directly on a poly(methyl methacrylate) (PMMA) surface (also known as plexiglass or acrylic). We used the BSC for direct (label-free) electronic measurements of antibody-antigen binding, showing that, at slightly above the electrical percolation threshold of the network, binding of a specific antigen dramatically increases the electrical resistance. Using anti-staphylococcal enterotoxin B (SEB) IgG as a "gate" and SEB as an "actuator", we demonstrated that the BSC was able to detect SEB at concentrations of 1 ng/mL. The new BSCs may permit assembly of multiple sensors on the same chip to create "biological central processing units (CPUs)" with multiple BSC elements, capable of processing and sorting out information on multiple analytes simultaneously.

Electrical percolation-based biosensor for real-time direct detection of staphylococcal enterotoxin B (SEB)

Electrical percolation-based biosensing is a new technology. This is the first report of an electrical percolation-based biosensor for real-time detection. The label-free biosensor is based on electrical percolation through a single-walled carbon nanotubes (SWNTs)-antibody complex that forms a network functioning as a "Biological Semiconductor" (BSC). The conductivity of a BSC is directly related to the number of contacts facilitated by the antibody-antigen "connectors" within the SWNT network. BSCs are fabricated by immobilizing a pre-functionalized SWNTs-antibody complex directly on a poly(methyl methacrylate) (PMMA) and polycarbonate (PC) surface. Each BSC is connected via silver electrodes to a computerized ohmmeter, thereby enabling a continuous electronic measurement of molecular interactions (e.g. antibody-antigen binding) via the change in resistance. Using anti-staphylococcal enterotoxin B (SEB) IgG to functionalize the BSC, we demonstrate that the biosensor was able to detect SEB at concentrations as low as 5 ng/mL at a signal to baseline (S/B) ratio of 2. Such measurements were performed on the chip in wet conditions. The actuation of the chip by SEB is immediate, permitting real-time signal measurements. In addition to this "direct" label-free detection mode, a secondary antibody can be used to "label" the target molecule bound to the BSC in a manner analogous to an immunological sandwich "indirect" detection-type assay. Although a secondary antibody is not needed for direct detection, the indirect mode of detection may be useful as an additional measurement to verify or amplify signals from direct detection in clinical, food safety and other critical assays. The BSC was used to measure SEB both in buffer and in milk, a complex matrix, demonstrating the potential of electrical percolation-based biosensors for real-time label-free multi-analyte detection in clinical and complex samples. Assembly of BSCs is simple enough that multiple sensors can be fabricated on the same chip, thereby creating "Biological Central Processing Units (BCPUs)" capable of parallel processing and sorting out information on multiple analytes simultaneously which may be used for complex analysis and for point of care diagnostics.

Gold nanoparticle-based enhanced chemiluminescence immunosensor for detection of Staphylococcal Enterotoxin B (SEB) in food

Staphylococcal enterotoxins (SEs) are major cause of foodborne diseases, so sensitive detection (<1 ng/ml) methods are needed for SE detection in food. The surface area, geometric and physical properties of gold nanoparticles make them well-suited for enhancing interactions with biological molecules in assays. To take advantage of the properties of gold nanoparticles for immunodetection, we have developed a gold nanoparticle-based enhanced chemiluminescence (ECL) immunosensor for detection of Staphylococcal Enterotoxin B (SEB) in food. Anti-SEB primary antibodies were immobilized onto a gold nanoparticle surface through physical adsorption and then the antibody-gold nanoparticle mixture was immobilized onto a polycarbonate surface. SEB was detected by a "sandwich-type" ELISA assay on the polycarbonate surface with a secondary antibody and ECL detection. The signal from ECL was read using a point-of-care detector based on a cooled charge-coupled device (CCD) sensor or a plate reader. The system was used to test for SEB in buffer and various foods (mushrooms, tomatoes, and baby food meat). The limit of detection was found to be approximately 0.01 ng/mL, which is approximately 10 times more sensitive than traditional ELISA. The gold nanoparticles were relatively easy to use for antibody immobilization because of their physical adsorption mechanism; no other reagents were required for immobilization. The use of our simple and inexpensive detector combined with the gold nanoparticle-based ECL method described here is adaptable to simplify and increase sensitivity of any immunological assay and for point-of-care diagnostics.

In vitro cell-based assay for activity analysis of staphylococcal enterotoxin A in food

Staphylococcal enterotoxins (SEs) are a leading cause of food poisoning and have two separate biological activities; it causes gastroenteritis and functions as a superantigen that activates large numbers of T cells. In vivo monkey or kitten bioassays were developed for analysis of SEs emetic activity. To overcome the inherent limitations of such bioassays, this study describes an in vitro splenocyte proliferation assay based on SEs superantigen activity as an alternative method for measuring the activity of staphylococcal enterotoxin A (SEA). After incubation of splenocytes with SEA, cell proliferation was measured by labeling the proliferating cells' DNA with bromodeoxyuridine (5-bromo-2-deoxyuridine, BrdU) and quantifying the incorporated BrdU by immunohistochemistry. BrdU labeling is shown to be highly correlated with SEA concentration (R(2)=0.99) and can detect 20 pg mL(-1) of SEA, which is far more sensitive than most enzyme-linked immunosorbent assays. Our assay can also distinguish between active toxin and inactive forms of the toxin in milk. By applying immunomagnetic beads that capture and concentrate the toxin, our assay was able to overcome matrix interference. These results suggest that our in vitro cell-based assay is an advantageous practical alternative to the in vivo monkey or kitten bioassays for measuring SEA and possibly other SEs activity in food.

Association of Mycoplasma arthritidis mitogen with lethal toxicity but not with arthritis in mice

Mycoplasma arthritidis induces an acute to chronic arthritis in rodents. Arthritis induced in mice histologically resembles human rheumatoid arthritis and can be associated with lethal toxicity following systemic injection. The M. arthritidis mitogen (MAM) superantigen has long been implicated as having a role in pathogenesis, but its significance with respect to toxicity and arthritogenicity in mycoplasma-induced disease is unclear. To study the pathogenic significance of MAM, M. arthritidis mutants that overproduced or failed to produce MAM were developed. MAM overproduction and knockout mutants were more and less mitogenic, respectively, than the wild-type strain. The degree of mitogenic activity correlated with lethal toxicity in DBA/2J mice. In contrast, histopathological studies detected no correlation between MAM production and the severity of arthritis induced in DBA/2J and CBA/J mice.

Pristane, a non-antigenic adjuvant, induces MHC class II-restricted, arthritogenic T cells in the rat

Pristane-induced arthritis (PIA) in rats, a model for rheumatoid arthritis (RA), is a T cell-dependent disease. However, pristane itself is a lipid and unable to form a stable complex with a MHC class II molecule. Therefore, the specificity and function of the T cells in PIA are as unclear as in rheumatoid arthritis. In this study, we show that activated CD4+ alphabetaT cells, which target peripheral joints, transfer PIA. The pristane-primed T cells are of oligo or polyclonal origin as determined by their arthritogenicity after stimulation with several mitogenic anti-TCRVbeta and anti-TCRValpha mAbs. Arthritogenic cells secreted IFN-gamma and TNF-alpha (but not IL-4) when stimulated with Con A in vitro, and pretreatments of recipient rats with either anti-IFN-gamma or a recombinant TNF-alpha receptor before transfer ameliorated arthritis development. Most importantly, we show that these T cells are MHC class II restricted, because treatment with Abs against either DQ or DR molecules ameliorates arthritis development. The MHC class II restriction was confirmed by transferring donor T cells to irradiated recipients that were syngenic, semiallogenic, or allogenic to MHC class II molecules, in which only syngenic and semiallogenic recipients developed arthritis. These data suggest that the in vivo administration of a non-antigenic adjuvant, like pristane, activates CD4+ alphabetaT cells that are MHC class II restricted and arthritogenic.

Crystal structures of T cell receptor (beta) chains related to rheumatoid arthritis

The crystal structures of the Vbeta17+ beta chains of two human T cell receptors (TCRs), originally derived from the synovial fluid (SF4) and tissue (C5-1) of a patient with rheumatoid arthritis (RA), have been determined in native (SF4) and mutant (C5-1(F104-->Y/C187-->S)) forms, respectively. These TCR beta chains form homo-dimers in solution and in crystals. Structural comparison reveals that the main-chain conformations in the CDR regions of the C5-1 and SF4 Vbeta17 closely resemble those of a Vbeta17 JM22 in a bound form; however, the CDR3 region shows different conformations among these three Vbeta17 structures. At the side-chain level, conformational differences were observed at the CDR2 regions between our two ligand-free forms and the bound JM22 form. Other significant differences were observed at the Vbeta regions 8-12, 40-44, and 82-88 between C5-1/SF4 and JM22 Vbeta17, implying that there is considerable variability in the structures of very similar beta chains. Structural alignments also reveal a considerable variation in the Vbeta-Cbeta associations, and this may affect ligand recognition. The crystal structures also provide insights into the structure basis of T cell recognition of Mycoplasma arthritidis mitogen (MAM), a superantigen that may be implicated in the development of human RA. Structural comparisons of the Vbeta domains of known TCR structures indicate that there are significant similarities among Vbeta regions that are MAM-reactive, whereas there appear to be significant structural differences among those Vbeta regions that lack MAM-reactivity. It further reveals that CDR2 and framework region (FR) 3 are likely to account for the binding of TCR to MAM.

Substantial proportions of identical β-chain T-cell receptor transcripts are present in epithelial ovarian carcinoma tumors

To determine whether clonally expanded T cells are present in tumor specimens from patients with epithelial ovarian carcinoma (EOC) we amplified by the non-palindromic adaptor PCR (NPA-PCR) or by Vbeta-specific PCR beta-chain T-cell receptor (TCR) transcripts from these tumor specimens. The amplified transcripts were cloned and sequenced. Sequence analysis revealed the presence of substantial proportions of multiple identical copies of beta-chain TCR transcripts, suggesting the presence of clonal expansions of T cells in these patients, which were statistically significant by the binomial distribution in seven of nine patients. Independent amplification in separate experiments of beta-chain TCR transcripts from one patient by either NPA-PCR or by Vbeta-specific PCR, followed by cloning and sequencing, revealed identical clonal expansions irrespectively of the amplification method used. Multiple identical copies of beta-chain TCR transcripts can be derived only by specific antigen-driven proliferation and clonal expansion of the T-cell clones which recognize these antigens. Because of the very large size of the TCR repertoire, the probability of finding by chance multiple identical copies of these transcripts within an independent sample of T cells is negligible. These results demonstrate that T cells infiltrating solid tumor specimens or malignant ascites of patients with EOC contain monoclonal/oligoclonal populations of T cells.

New prospects for the treatment of rheumatoid arthritis

Rheumatoid arthritis (RA) is a common inflammatory and destructive arthropathy. Current therapies fail to stop joint damage and reduce long-term disability. Greater understanding of disease pathogenesis has identified many inflammatory mediators as possible therapeutic targets. Novel therapeutic agents, such as monoclonal antibodies (mAbs), cytokine receptor-human immunoglobulin constructs, recombinant human proteins and antisense oligodeoxynucleotides targeting these inflammatory mediators have been tested in rheumatoid arthritis with some success. In particular, inflammation can be effectively suppressed using anticytokine therapies. However, the ideal treatment for RA, one that is immunomodulatory and induces prolonged disease remission after a single course of therapy, still eludes us. Strategies aiming to achieve this include TCR peptide vaccination and anti-CD4 mAbs, currently in clinical trials in RA.

Simultaneous analysis of multiple staphylococcal enterotoxin genes by an oligonucleotide microarray assay

Staphylococcal enterotoxins (SEs) are a family of 17 major serological types of heat-stable enterotoxins that are one of the leading causes of gastroenteritis resulting from consumption of contaminated food. SEs are considered potential bioweapons. Many Staphylococcus aureus isolates contain multiple SEs. Because of the large number of SEs, serological typing and PCR typing are laborious and time-consuming. Furthermore, serological typing may not always be practical because of antigenic similarities among enterotoxins. We report on a microarray-based one-tube assay for the simultaneous detection and identification (genetic typing) of multiple enterotoxin (ent) genes. The proposed typing method is based on PCR amplification of the target region of the ent genes with degenerate primers, followed by characterization of the PCR products by microchip hybridization with oligonucleotide probes specific for each ent gene. We verified the performance of this method by using several other techniques, including PCR amplification with gene-specific primers, followed by gel electrophoresis or microarray hybridization, and sequencing of the enterotoxin genes. The assay was evaluated by analysis of previously characterized staphylococcal isolates containing 16 ent genes. The microarray assay revealed that some of these isolates contained additional previously undetected ent genes. The use of degenerate primers allows the simultaneous amplification and identification of as many as nine different ent genes in one S. aureus strain. The results of this study demonstrate the usefulness of the oligonucleotide microarray assay for the analysis of multitoxigenic strains, which are common among S. aureus strains, and for the analysis of microbial pathogens in general.

Analysis of T-cell receptor Vbeta gene from infiltrating T cells in insulitis and myocarditis in encephalomyocarditis virus-infected BALB/C mice

Encephalomyocarditis (EMC) virus induces insulin-dependent diabetes and myocarditis in several strains of mice. The T-cell receptor (TCR) Vbeta genes of infiltrating T cells in the pancreas and myocardium of BALB/C mice infected with EMC virus D-variant (EMC-D virus) were analyzed. Using a nested two-step polymerase chain reaction (PCR), TCR Vbeta cDNAs were cloned and sequenced. Two and four kinds of TCR Vbeta clones were obtained from T cells infiltrating into the pancreas and myocardium of BALB/C mice infected with EMC-D virus, respectively. The infiltrating lymphocytes in the diabetic mice expressed Vbeta 8.1, 8.2, and 8.3 genes predominantly. Previously, the use of Vbeta 8.2 has been reported in autoimmune diseases such as murine experimental allergic encephalomyelitis (EAE) and non-obese diabetic (NOD) mouse. This study suggests that mice infected with EMC virus are a useful animal model for autoimmune diseases such as insulin-dependent diabetes.

Analysis of two T-cell receptor BV gene segment polymorphisms in caucasoid Brazilian patients with rheumatoid arthritis

Considering the role of T-lymphocytes in rheumatoid arthritis (RA) and a possible involvement of the TCR in the pathology of this disease we analyzed allelic and genotypic frequencies of variants of two TCRBV gene segments (TCRBV3S1 and TCRBV18) in RA. A total of 95 caucasoid South Brazilian RA patients were genotyped for both TCRBV gene segment variants by restriction fragment length polymorphism preceded by PCR (PCR-RFLP) and the obtained frequencies were compared to those from healthy individuals. Allelic frequencies for the TCRBV3S1 gene segment were, respectively, for RA patients and controls, 0.447 and 0.545 (allele 1) and 0.553 and 0.455 (allele 2). Allelic frequencies for the TCRBV18 gene segment were, respectively, for RA patients and controls, 0.824 and 0.806 (allele 1) and 0.176 and 0.194 (allele 2). Neither allelic frequencies nor genotypic frequencies differ among RA and healthy individuals, suggesting that there is not a direct association among the TCRBV allelic variants studied and the development of RA and thus excluding the possibility of use of these gene segment polymorphisms as RA susceptibility markers.

In vitro and in vivo T cell oligoclonality following chronic stimulation with staphylococcal superantigens

Microbial superantigens (SAg), including SEB and TSST-1, polyclonally activate T cells belonging to specific TCR BV families. A pathogenic role for SAg in various human diseases has been suggested, but enthusiasm for this view has been tempered by the T cell oligoclonality in these disorders. To assess whether T cell oligoclonality can emerge following protracted SAg stimulation, human PBMC were stimulated with SEB, TSST-1, or anti-CD3 mAb and maintained in culture with exogenous IL-2. Oligoclonality was appreciated by day 14 among CD4(+) and CD8(+) T cells. In addition, mice transgenic for human DR2 and DQ8 were injected weekly with SEB, and splenic CD4(+) and CD8(+) T cells were analyzed for oligoclonality. In mice that received one or three such injections, little-to-no oligoclonality was detected. In contrast, considerable oligoclonality was detected in mice that received eight weekly SEB injections. Many of these T cell oligoclones were identical to "spontaneously" arising oligoclones detected in SEB-naive mice. Thus, T cell oligoclonality can emerge following chronic SAg stimulation. In hosts who have lost tolerance to self Ag, chronic exposure to SAg may preferentially promote expansion of autoreactive T cells and facilitate development of clinical disease.

A DNA Spiegelmer to staphylococcal enterotoxin B

Bacterial staphylococcal enterotoxin B is involved in several severe disease patterns and it was therefore used as a target for the generation of biologically stable mirror-image oligonucleotide ligands, so called Spiegelmers. The toxin is a 28 kDa protein consisting of 239 amino acids. Since the full-length protein is not accessible to chemical peptide synthesis, a stable domain of 25 amino acids was identified as a suitable selection target. DNA in vitro selection experiments were carried out against the equivalent mirror-image D-peptide domain resulting in high affinity D-DNA aptamers. As expected, the corresponding enantiomeric L-DNA Spiegelmer showed comparable binding characteristics to the L-peptide domain. Moreover, the Spiegelmer bound the whole protein target with only slightly reduced affinity. Dissociation constants of both peptide-oligonucleotide complexes were measured in the range of 200 nM, whereas the Spiegelmer binding to the full-length protein was determined at approximately 420 nM. These data demonstrate the possibility to identify Spiegelmers against large protein targets by a domain approach.

Mycoplasma arthritidis superantigen (MAM)-induced macrophage nitric oxide release is MHC class II restricted, interferongamma dependent, and toll-like receptor 4 independent

Mycoplasma arthritidis causes arthritis in rodents that resembles human rheumatoid arthritis. It produces a superantigen (MAM) that stimulates production of cytokines by making a bridge between lymphocyte T-cell receptor with the appropriate Vbeta chain, and H-2 1-Ealpha MHC class II molecules. Here we studied MAM-induced nitric oxide (NO) production in mouse peritoneal macrophages and found that it was: (1) time and concentration dependent, (2) possibly derived from inducible NOS synthase since it was reduced significantly by amino guanidine pretreatment, (3) restricted to H-2(K) (C3H/HePas and C3H/HeJ) and H-2(d) strains (BALB/c), (4) independent of TLR4 signaling since the coisogenic strains C3H/HePas and C3H/HeJ (TLR4 deficient) produced similar levels of NO following MAM stimulation, (5) potentiated by lipopolysaccharide, and (6) dependent on the presence of nonadherent peritoneal cells. Neutralization of interferon-gamma (IFNgamma in the peritoneal cell cultures with monoclonal antibodies abolished MAM-induced NO production. Addition of rIFNgamma to the adherent cells substituted the nonadherent cells for MAM-induced NO production. A macrophage cell line, J774A.1 (H-2(d)), also produced NO upon MAM stimulation but only when BALB/c spleen lymphocytes were added. Thus, in murine macrophages, MAM induces NO production that is dependent on signaling through MHC class II molecules and IFNgamma but independent of TLR4 expression.

T cell receptor Beta chain gene usage in endemic pemphigus foliaceus (fogo selvagem)

The trimolecular complex comprised of the major histocompatibility complex, peptide antigen, and the T cell receptor is a requisite for T cell activation in normal and autoimmune responses. T cell receptor analysis is critical to further our understanding regarding mechanisms of T cell epitope selection and autoimmune initiation and progression and may help to identify targets for immunotherapy. Pemphigus foliaceus is an autoimmune blistering skin disease characterized by intraepidermal blisters and circulating autoantibodies directed against desmoglein 1, a 160 kDa transmembrane desmosomal molecule expressed in keratinocytes. As tissue damage is mediated by anti-desmoglein 1 antibodies, an initial T cell response is a likely requirement for autoantibody generation in this disease. To elucidate the role of pathogenic T cells in autoimmunity further, we have directly characterized the T cell receptor of T cells derived from pemphigus foliaceus patients. Complementary DNA was isolated from 17 desmoglein 1 specific T cell clones generated from pemphigus foliaceus patients by clonal expansion in vitro. To analyze the T cell repertoire, a panel of primers, collectively specific for the known human T cell receptor beta variable region (TCRBV) families were paired with a constant region primer to polymerase chain reaction to amplify one distinct T cell receptor beta variable region allele for each T cell clone studied. Polymerase chain reaction products were sequenced to determine exact beta chain gene usage. In the 17 clones tested, 10 distinct T cell receptor beta variable region usages and nine T cell receptor beta joining gene segment usages were identified. Furthermore, T cell receptor beta variable region and beta joining usage did not appear to be random, but oligoclonal in nature, with some preference shown for T cell receptor beta variable region 5S1 and T cell receptor BJ2S5.

Simultaneous analysis of T cell clonality and cytokine production in rheumatoid arthritis using three-colour flow cytometry

In this study we examined the cytokine production by T cells and TCRVbeta subsets in peripheral blood (PB) and synovial fluid (SF) from six RA patients and PB from 10 normal subjects, using three-colour flow cytometry. In two RA subjects we assessed T cell clonality by RT PCR using TCRBV family-specific primers and analysed the CDR3 (complementarity determining region 3) length by GeneScan analysis. A high percentage of IFN-gamma- and IL-2- producing cells was observed among the PB T cells in both the RA patients and normal controls and among the SF T cells in RA patients. In contrast, the percentage of T cells producing IL-4 and IL-5 was small among PB T cells in both RA patients and normal controls and among SF T cells in RA patients. There was no significant difference in the production of IFN-gamma, IL-2 and IL-5 between the two compartments (PB and SF); however, there were significantly more IL-4-producing cells in SF. Molecular analysis revealed clonal expansions of four TCRBV families in SF of two of the RA patients studied: TCRBV6.7, TCRBV13.1 and TCRBV22 in one and TCRBV6.7, TCRBV21.3 and TCRBV22 in the second. These expansions demonstrated cytokine expression profiles that differed from total CD3+ cells, implying that T cell subsets bearing various TCR-Vbeta families may have the potential to modulate the immune response in RA patients.

Vbeta18.1(+) and V(alpha)2.3(+) T-cell subsets are associated with house dust mite allergy in human subjects

BACKGROUND

The recognition of allergenic peptides by T cells through their T-cell receptor (TCR) represents a crucial step in the initiation of an allergen-specific immune response. In parallel to the superantigen-driven restricted expansion of Vbeta subsets in autoimmune and infectious diseases, reports in animals and human subjects have shown a similar capacity of classical antigens.

OBJECTIVE

The study was performed to analyze the V(alpha)/Vbeta expression in house dust mite (HDM) allergy.

METHODS

The TCR repertoire of 15 subjects with HDM allergy, 22 atopic subjects without HDM allergy, and 19 nonatopic individuals, members of 2 extended and 4 nuclear families, was determined. By using flow cytometry, the expression of 22 Vbeta and 3 V(alpha) elements was analyzed in vivo and after in vitro allergen stimulation.

RESULTS

In comparison with nonatopic and atopic individuals without HDM allergy, freshly isolated PBMCs of individuals with HDM allergy showed a significantly higher frequency of Vbeta18(+) and V(alpha)2.3(+) T cells. Although members of all 3 groups had a similar lymphocyte proliferation response after in vitro stimulation with Der p 1 or Der p 1 peptide(101-131), a significant expansion of Vbeta18(+) and V(alpha)2.3(+) T cells in vitro occurred only in individuals with HDM allergy. Moreover, the degree of expansion correlated with the levels of allergen-specific IgE antibodies. No expansion of Vbeta18(+) and V(alpha)2.3(+) was observed after mitogen stimulation with PHA, indicating allergen specificity of the response.

CONCLUSION

Our results strongly suggest restricted TCR V(alpha)/Vbeta gene use in HDM allergy and might be a step toward TCR-based immunotherapy.

The autoimmune pathogenesis of rheumatoid arthritis: role of autoreactive T cells and new immunotherapies

OBJECTIVES

To review the role of T lymphocytes in the pathogenesis of rheumatoid arthritis (RA) and discuss the relevance of the components of the trimolecular complex (synovial T cells, autoantigens, and antigen presenting cells) in the pathogenic autoimmune response in RA.

METHODS

Currently available experimental data are combined into a hypothetical pathway that may explain some of the events in the RA process. The literature regarding the potential therapeutic strategies that interfere with specific components of the trimolecular complex and other mediators are discussed briefly.

RESULTS

T cells are activated in the peripheral blood, cross the endothelial cell wall, and migrate into the joints. Once in the synovial joints, T cells are reactivated by cross-reactive antigens and clonally expand. Clonally expanded T cells accumulate in the diseased joint and secrete proinflammatory cytokines that attract and activate other cells, such as monocytes and macrophages. Treatment with anti-CD4 monoclonal antibodies or anticytokine agents that prevents antigen presentation and/or T-cell activation were effective in RA. Other therapies, such as T-cell vaccination and T-cell receptor peptide vaccination targeting autoreactive T cells, showed clinical improvement, suggesting a pathogenic role of these lymphocytes in disease progression.

CONCLUSION

T cells appear to be actively involved in the pathogenesis of RA, but several parts of the pathway are hypothetical and further research is needed.

TCR peptide therapy in human autoimmune diseases

Inflammatory Th1 cells reacting to tissue/myelin derived antigens likely contribute to the pathogenesis of diseases such as multiple sclerosis (MS), rheumatoid arthritis (RA), and psoriasis. One regulatory mechanism that may be useful for treating autoimmune diseases involves an innate second set of Th2 cells specific for portions of the T cell receptor of clonally expanded pathogenic Th1 cells. These Th2 cells are programmed to respond to internally modified V region peptides from the T cell receptor (TCR) that are expressed on the Th1 cell surface in association with major histocompatibility molecules. Once the regulatory Th2 cells are specifically activated, they may inhibit inflammatory Th1 cells through a non-specific bystander mechanism. A variety of strategies have been used by us to identify candidate disease-associated TCR V genes present on pathogenic Th1 cells, including BV5S2, BV6S5, and BV13SI in MS, BV3, BV14, and BV17 in RA, and BV3 and BV13S1 in psoriasis. TCR peptides corresponding to the mid region of these BV genes were found to be consistently immunogenic in vivo when administered either i.d. in saline or i.m. in incomplete Freund's adjuvant (IFA). In MS patients, repeated injection of low doses of peptides (100-300 microg) significantly boosted the number of TCR-reactive Th2 cells. These activated cells secreted cytokines, including IL-10, that are known to inhibit inflammatory Th1 cells. Cytokine release could also be induced in TCR-reactive Th2 cells by direct cell-cell contact with Th1 cells expressing the target V gene. These findings indicate the potential of regulatory Th2 cells to inhibit not only the target Th1 cells, but also bystander Th1 cells expressing different V genes specific for other autoantigens. TCR peptide vaccines have been used in our studies to treat a total of 171 MS patients (6 trials), 484 RA patients (7 trials), and 177 psoriasis patients (2 trials). Based on this experience in 824 patients with autoimmune diseases, TCR peptide vaccination is safe and well tolerated, and can produce significant clinical improvement in a subset of patients that respond to immunization. TCR peptide vaccination represents a promising approach that is well-suited for treating complex autoimmune diseases.

Potential biologic agents for treating rheumatoid arthritis

The encouraging clinical results observed in trials using anti-TNF therapy clearly warrant further studies to determine whether TNF inhibitors are capable of modifying the destructive component of this disease in long-term follow-up studies as well as to assess the safety of long-term use (see the article by Keystone in this issue). It is also reasonable to propose that interfering with the cytokine cascade earlier in the course of disease may be of even greater therapeutic benefit. As the pathogenetic mechanisms in RA are more clearly defined, especially in early disease and in those individuals destined to develop severe disease, the potential of other biologic agents to specifically inhibit these critical pathways may provide better treatments for our patients. Many potential targets in the immune-mediated process of RA are currently being rigorously evaluated in clinical trials. Use of combinations of biologic therapies, perhaps in human patients with RA, should be of considerable interest in future trials.

Toxic shock syndrome toxin-1 accelerated collagen-induced arthritis in mice

The aim of this study was to explore the roles of toxic shock syndrome toxin-1 (TSST-1) in collagen-induced arthritis (CIA). DBA/1 mice were immunized with type II collagen (CII) and treated with TSST-1. Intraperitoneal and intravenous injections of TSST-1 aggravated CIA, enhancing its incidence and severity. CIA was accompanied by an increase in anti-CII IgG Ab levels. Intraperitoneal administration with TSST-1 enhanced IFN-gamma, TNF-alpha, and IL-4 production in DBA/1 mice. We discovered the mRNA expressions of IFN-gamma, IL-2, TNF-alpha, IL-1beta, and iNOS in spleen cells stimulated with TSST-1 in vitro. However, IL-12 and IL-4 mRNA expression were seen constitutively without stimulation. Only a little increase of IL-12 and IL-4 mRNA expression was seen at 2-3 h after treatment with TSST-1. Our experiments demonstrated that CIA was aggravated by the treatment with TSST-1, which may have induced various proinflammatory cytokines and the production of both Th1 and Th2 cytokines.

CD4+ and CD8+ clonal T cell expansions indicate a role of antigens in ankylosing spondylitis; a study in HLA-B27+ monozygotic twins

Ankylosing spondylitis (AS) is a complex genetic disease in which both MHC and non-MHC genes determine disease susceptibility. To determine whether the T cell repertoires of individuals with AS show signs of increased stimulation by exogenous antigens, CD4+ and CD8+ T cell subsets of five monozygotic HLA-B27+ twins (two concordant and three discordant for AS) and CD8+ T cell repertoires of three healthy HLA-B27+ individuals were characterized by TCR beta-chain (TCRB) CDR3 size spectratyping. Selected TCRB-CDR3 spectra were further analysed by BJ-segment analysis and TCRB-CDR3 from expanded T cell clones were sequenced. In an analysis of all data (519/598 possible TCRB-CDR3 spectra), AS was associated with increased T cell oligoclonality in both CD8+ (P = 0.0001) and CD4+ (P = 0.033) T cell subsets. This was also evident when data were compared between individual twins. Nucleotide sequence analysis of expanded CD8+ or CD4+ T cell clones did not show selection for particular TCRB-CDR3 amino acid sequence motifs but displayed sequence homologies with published sequences from intra-epithelial lymphocytes or synovial T cells from rheumatoid arthritis patients. Together, these results provide support for the hypothesis that responses to T cell-stimulating exogenous or endogenous antigens are involved in the induction and/or maintenance of AS.

Skewed T-cell receptor variable gene usage in the synovium of early and chronic rheumatoid arthritis patients and persistence of clonally expanded T cells in a chronic patient

OBJECTIVE

Autoreactive T cells may contribute to the pathogenesis of rheumatoid arthritis (RA). We studied the T-cell receptor (TCR) V-gene repertoire in the blood and synovium of early and chronic RA patients using polymerase chain reaction-enzyme-linked immunosorbent assay to evaluate possible differences between these patient groups.

RESULTS

Over-represented TCR V genes were observed in the synovium, but not in the blood of all RA patients (n = 38). The number of over-represented V genes was higher in the synovium of chronic RA patients (n = 31) than in that of early RA patients (n = 7). The V-gene profile was different among patients, and similar in the two knees for patients with bilateral synovitis (n = 5). The clonal composition of over-represented TCR BV genes in a patient with early RA and a patient with chronic RA was further studied by CDR3 region sequence analysis. A high level of clonal diversity was found in the joints and the blood of the early RA patient, suggesting a polyclonal T-cell expansion. In the chronic RA patient, predominant clonal expansions were observed in the blood and synovium, and some expanded clones were still present 2 yr later.

CONCLUSIONS

The observation of similar T-cell populations in both joints in patients with bilateral synovitis and the persistence of clonally expanded T cells for more than 2 yr in the joints of a chronic RA patient may indicate a pathogenic role for these cells in the disease process.

Camel heavy-chain antibodies: diverse germline V(H)H and specific mechanisms enlarge the antigen-binding repertoire

The antigen-binding site of the camel heavy-chain antibodies devoid of light chain consists of a single variable domain (V(H)H) that obviously lacks the V(H)-V(L) combinatorial diversity. To evaluate the extent of the V(H)H antigen-binding repertoire, a germline database was constructed from PCR-amplified V(H)H/V(H) segments of a single specimen of Camelus dromedarius. A total of 33 V(H)H and 39 V()H unique sequences were identified, encoded by 42 and 50 different genes, respectively. Sequence comparison indicates that the V(H)Hs evolved within the V(H) subgroup III. Nevertheless, the V(H)H germline segments are highly diverse, leading to a broad structural repertoire of the antigen-binding loops. Seven V(H)H subfamilies were recognized, of which five were confirmed to be expressed in vivo. Comparison of germline and cDNA sequences demonstrates that the rearranged V(H)Hs are extensively diversified by somatic mutation processes, leading to an additional hypervariable region and a high incidence of nucleotide insertions or deletions. These diversification processes are driven by hypermutation and recombination hotspots embedded in the V(H)H germline genes at the regions affecting the structure of the antigen-binding loops.

HLA polymorphisms and T cells in rheumatoid arthritis

A dense infiltrate of activated T cells, macrophages, and B cells in the synovial membrane is the cardinal pathological feature of rheumatoid arthritis (RA). Frequently, tissue infiltrating cells acquire a morphological organization reminiscent of secondary lymphoid tissue. The composition of the inflammatory lesions, the production of autoantibodies, and the association of disease risk with genes related to the HLA-D region have all been cited as evidence for a critical role of T cells in disease pathogenesis. Investigations on the precise role of HLA genes in RA have confirmed the importance of this genetic risk factor and have identified a consensus sequence within the HLA-DRBI genes. The observation that HLA polymorphisms are mostly associated with disease progression and severity and that a gene dose effect for HLA-DR genes is operational has challenged the simple model that HLA molecules select and present an arthritogenic antigen. Studies analyzing the repertoire of tissue infiltrating T cells have not been able to identify a dominant and common disease relevant T cell. The infiltrate is diverse in terms of T cell receptor gene usage but consistently includes clonally expanded populations. Recent evidence indicates that RA patients carry expanded CD4 clonotypes which are characterized by deficient CD28 expression and autoreactivity. These autoreactive CD4 T cells are not restricted to the joint, raising the possibility that rheumatoid synovitis is a manifestation of a systemic autoimmune disease. Support for this model has come from studies in T cell receptor (TCR) transgenic animals which develop inflammation of the synovial membrane stimulated by a T cell response to ubiquitously expressed self-MHC molecules. Antigens driving the chronic persistent immune response in RA may not be restricted to the joint but rather may be widely distributed, providing an explanation for the difficulties in identifying arthritogenic antigens directly or indirectly through the selection of joint infiltrating T cells.

Antigen presentation by parenchymal cells: a route to peripheral tolerance?

T-cell activation and the development of efficient immune responses requires the delivery, by the antigen-presenting cell, of two distinct signals. The first results from the engagement of the TCR:CD3:CD4 complex, and the second from the interaction of CD28 with the B7 family of co-stimulatory molecules. In this context, the physiological significance and the functional consequences of antigen presentation by B7-deficient parenchymal cells, which express MHC class II molecules as a result of inflammation, remains a matter of debate. In this paper we have attempted to critically review the often conflicting reports on the functional effects of antigen presentation by epithelial and endothelial cells to T cells, both in vitro and in vivo. Our own findings are summarised in a model which is consistent with the suggestion of an important role for antigen presentation by parenchymal cells in the induction and the maintenance of peripheral tolerance.

Dominant and shared T cell receptor beta chain variable regions of T cells inducing synovial hyperplasia in rheumatoid arthritis

Previously, we demonstrated the presence of at least two distinct subpopulations of patients with rheumatoid arthritis (RA) employing a cell-transfer experiment using severe combined immunodeficient (SCID) mice. One group of patients, whose T cells derived from the rheumatoid joints, induced synovial hyperplasia (SH) in the SCID mice (the positive group). The other group did not display the induction of SH (the negative group). TCR/Vbeta gene usage analysis indicated that some dominant T cell subpopulations were oligoclonally expanding only in the rheumatoid joints, and not in the periphery of the patients of the positive group. Moreover, these T cell subpopulations were not seen in the joints of patients in the negative group or in non-RA patients. In addition, the preferential uses of certain TCR/Vbetas (Vbeta8, Vbeta12, Vbeta13, and Vbeta14) genes were demonstrated in these T cells. In this study, to investigate whether these T cells are driven by a certain antigen(s), the third complementarity determining regions (CDR3s) of TCR/Vbeta, especially Vbeta8 and Vbeta14 PCR products, were cloned and sequenced. As a result, a dominant CDR3 sequence, CASS-PRERAT-YEQ, was found in Vbeta14+ T cells from the rheumatoid joint of a patient (Patient 1) of the positive group with a Vbeta14 skew. The identical CDR3 sequence also predominated in Vbeta14+ T cells from the rheumatoid joint of another patient (Patient 7) of the positive group with a Vbeta14 skew. In addition, in the patients (Patients 4, 7, 8) of the positive group with a Vbeta8 skew, other dominant CDR3 sequences, CASS-ENS-YEQ and CASS-LTEP-DTQ, were found as in the case of Vbeta14. However, no identical CDR3 sequences were detected dominantly in the joints of the patients in the negative group or in non-RA patients. A Vbeta14+ T cell clone (TCL), named G3, with the identical CDR3 sequence, CASS-PRERAT-YEQ, was isolated successfully from Patient 1, and cell transfer of G3 with autologous irradiated peripheral mononuclear cells induced SH in the SCID mice. Taken together, these results suggest that T cells inducing SH, thought to be pathogenic for RA, might be driven by a certain shared antigen(s).

Characterisation of T cell clonotypes that accumulated in multiple joints of patients with rheumatoid arthritis

OBJECTIVE

To investigate whether identical T cell clonotypes accumulate in multiple rheumatoid joints, the clonality of T cells that had infiltrated into synovial tissue (ST) samples simultaneously obtained from multiple joints of patients with rheumatoid arthritis (RA) was analysed.

METHODS

T cell receptor (TCR) beta gene transcripts, amplified by reverse transcription-polymerase chain reaction from ST and peripheral blood lymphocytes of five RA patients, were subjected to single strand conformation polymorphism analysis and DNA sequencing.

RESULTS

Approximately 40% of accumulated T cell clonotypes found in one joint of a patient were found in multiple joints in the same patient. Furthermore, identical amino acid sequences were found in TCR beta junctional regions of these clonotypes from different patients with at least one HLA molecule match.

CONCLUSIONS

The T cell clonotypes accumulating in multiple rheumatoid joints may be involved in the perpetuation of polyarthritis by reacting to antigens common to these multiple joints.

Endogenous presenilin 1 redistributes to the surface of lamellipodia upon adhesion of Jurkat cells to a collagen matrix

Most familial early-onset Alzheimer's disease cases are caused by mutations in the presenilin 1 (PS1) gene. Subcellular localization of the endogenous PS1 is essential for understanding its function, interactions with proteins, and role in Alzheimer's disease. Although numerous studies revealed predominant localization of PS1 to endoplasmic reticulum and Golgi, there are conflicting reports on the localization of PS1 to the cell surface. We found that endogenous PS1 is highly expressed in T lymphocytes (Jurkat cells). Using a variety of methods, we present evidence that endogenous PS1 is localized to the cell surface in addition to intracellular membrane compartments. Moreover, PS1 appeared in high levels on the surface of lamellipodia upon adhesion of the cells to a collagen matrix. The redistribution of PS1 in adhered cells was strikingly similar to that of the well characterized adhesion protein CD44. Cell surface PS1 formed complexes in vivo with actin-binding protein filamin (ABP-280), which is known to form bridges between cell surface receptors and cytoskeleton and mediate cell adhesion and cell motility. Taken together, our results suggest a role of PS1 in cell adhesion and/or cell-matrix interaction.

New therapeutic targets for rheumatoid arthritis

New insights into the pathogenesis of rheumatoid arthritis (RA) and consequently new targets of therapy are covered in a broad overview fashion. Short-term significant beneficial effect on RA disease activity has been established in a small but rapidly growing number of double-blind placebo-controlled trials now including recombinant human IL-1 receptor antagonist, chimeric (mouse/human) monoclonal antibodies (mAb) against TNF alpha (cA2), humanised (human/mouse) anti-TNF alpha mAb (CDP571) and recombinant human TNF-receptor-Fc fusion protein (TNFR:Fc). Placebo-controlled trials of anti-T cells agents such as chimeric anti-CD4 mAb (cM-T412) and anti-CD5 immunoconjugate, did not demonstrate clinical benefit. A placebo-controlled study of the anti-T cell derived cytokine IL-2 (DAB486IL-2) showed only modes clinical improvement. Other anti-T cell approaches such as autologous T cell vaccination and induction of tolerance by oral type II collagen have been unsuccessful. The one controlled trial with an anti-inflammatory cytokine, recombinant human IFN-gamma, showed modest clinical benefits. Controlled trials with IL-4 and IL-10 and with anti-adhesion molecules are awaited.

Selection of hprt mutant T cells as surrogates for dividing cells reveals a restricted T cell receptor BV repertoire in insulin-dependent diabetes mellitus

T cells with somatically acquired mutations in the hypoxanthine-guanine phosphoribosyltransferase (hprt) gene were isolated from patients with insulin-dependent diabetes mellitus (IDDM) as representatives of populations potentially enriched for in vivo activated T cells. TCRB gene V region usage among mutant isolates from individual IDDM patients, but not from normal controls, showed a pronounced preference for BV14 and, to a lesser extent, BV6. Wild-type (nonmutant) isolates did not show such preferences. Extensive in vivo clonal expansions of the BV14 expressing mutant T cells from IDDM patients were revealed by sequence identity of TCRB chain junctional regions. These data support restricted TCRB gene usage in T cell populations enriched for in vivo activated clones in patients with IDDM.

Evidence of T cell receptor beta-chain patterns in inflammatory and noninflammatory bowel disease states

T cell activation, as defined by expression of relevant cell surface molecules, such as the interleukin-2 receptor (CD25), is increased in many chronic relapsing diseases, including inflammatory bowel disease (IBD). These T cells are generally activated through contact of their clonotypic T cell receptor (TCR) with a peptide antigen presented by a major histocompatibility complex molecule. One of the putative antigenic contact sites for the TCR is the third complementarity determining region (CDR3) of the TCR beta-chain variable region (TCRBV). Therefore, analysis of the TCRBV CDR3 provides insight into the diversity of antigens encountered by a given T cell population. This study evaluated the TCRBV CDR3 usage of the activated intestinal lymphocytes from human subjects with IBD, diverticulitis (inflammatory control), and a normal tissue control. Public patterns, as demonstrated by shared TCRBV CDR3 amino acid sequences of activated intestinal T cell subpopulations, were observed. In particular, a public pattern of TCRBV22, a conserved valine in the fifth position, and use of TCRBJ2S1 or TCRBJ2S5 was present in three of four Crohn's disease subjects while not present in the ulcerative colitis subjects. However, the private patterns of TCRBV CDR3 region amino acid sequences were far more striking and easily demonstrated in all individuals studied, including a normal noninflammatory control. Thus we conclude that selective antigenic pressures are prevalent among an individual's activated intestinal lymphocytes.

T cell receptor gene in synovial tissues of rheumatoid arthritis

Rheumatoid arthritis is a chronic and destructive autoimmune joint disease characterized by inflammation of synovial tissue of unknown aetiology. Studies on TCR genes expressed by infiltrating T cells in synovial tissues have attempted to identify mechanism and specificity of the recruitment. T cell infiltrate in rheumatoid arthritis appears to be an association of a polyclonal non specific infiltrate with dominant clones or clonotypes. T cell repertoire in synovial tissue is biased compared to peripheral blood but no TCR V gene can be identified as commonly over-used. Comparison of motifs found in the CDR3 region of dominant clones from different studies has currently failed to identified a commonly motif. The fact that a number of dominant clones or clonotypes is present in different joints and at different times of the disease suggests a selective expansion of T lymphocytes in rheumatoid arthritis synovial membrane. Further investigations are needed to characterize the specificity of these dominant clonotypes.

T cell receptor repertoire in rheumatoid arthritis

CD4+ T cells are a major component of the inflammatory infiltrate in rheumatoid synovitis. Within synovial lesions, clonal CD4+ T cell populations are detectable, supporting the notion of an antigen specific recognition even in the joint. In general, the clonal size of individual T cell clones is small and does not lead to a marked distortion of the synovial T cell receptor (TCR) repertoire. Comparison of TCR sequences derived from different patients has not provided evidence for common sequences. Either multiple antigens are recognized or the TCR repertoire is sufficiently plastic with a multitude of different TCR structures responding to the same antigen(s). However, within one individual, the repertoire of clonal T cell populations is restricted. Identical T cell clones can be identified in different joints and at different timepoints of the disease, emphasizing that the spectrum of antigens recognized is conserved over time and that the T cell response pattern is not subject to evolution. Characterization of antigens involved in the latter stages of the disease may thus provide critical information on disease-initiating events. Recent data have led to the new concept that the role of T cells in rheumatoid arthritis (RA) is not limited to synovial inflammation. Evidence has been provided that the premorbid TCR repertoires of RA patients and normal controls can be distinguished. The T cell repertoire in RA patients is prone to recognize certain microbial products and autoantigens. The selection of this response pattern can only partially be attributed to the disease associated HLA-DRB1 alleles. Additional factors common in RA patients but not in HLA-DR matched control individuals seem to be important in shaping the TCR repertoire. Furthermore, the repertoire of mature T cells in RA patients is characterized by oligoclonality which involves T cells in the peripheral blood compartment. Possibly, these clonal T cell populations react to widespread autoantigens, raising the possibility that RA patients have a defect in controlling peripheral tolerance and an anomaly of lymphoproliferation. In contrast to joint residing CD4+ T cells, expanded clonotypes isolated from the blood of different patients have been described to share TCR beta chain structures. How these characteristic features of the global TCR repertoire in RA patients translate into mechanisms of disease remains to be elucidated.

Specific Vβ T Cell Subsets Are Associated with Cat and Birch Pollen Allergy in Humans

Cognate interaction between TCRs and MHC class II molecules plays an important role in initiating the allergen-specific immune response. Therefore, we analyzed the TCR distribution of human PBLs of 56 atopic and nonatopic (NA) individuals, including 4 monozygotic twin pairs, from two extended and four nuclear families. The expression of 23 Vβ and 3 Vα elements was analyzed. The blood samples of symptomatic birch pollen-sensitized individuals that were taken ≤6 wk after the birch pollen season (n = 8) showed a significantly higher frequency of Vβ16.1+ and Vβ20.1+ T cells compared with the blood samples of birch pollen-sensitized individuals that were obtained out of allergen season (n = 10) or from NA individuals (p &lt; 0.0005 and p &lt; 0.0001, respectively). Allergen-specific lymphocyte proliferation was detected in the allergic individuals, and the distribution of Vβ16.1+ and Vβ20.1+ T cells returned to normal levels after the pollen season. The frequency of these Vβ-expressing T cells correlated with the levels of allergen-specific IgE Abs. In addition, cat-sensitized individuals (n = 8) showed a significantly higher frequency of Vβ17.1-expressing T cells than did NA individuals (p &lt; 0.005). Our results indicate restricted TCR-Vβ gene usage in cat and birch pollen allergies; we suggest that both genetic and environmental factors contribute to TCR-Vβ gene expression and to the development of a specific T cell response.