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

T-cell receptors and collagen induced arthritis in H-2r mice

Mouse strains B10, B10.RIII, RIIIS/J and the F1 and backcross progeny arising from them were tested for susceptibility to porcine type II collagen-induced arthritis (PII-CIA). The clinically severe arthritis of rapid onset that is characteristic of PII-immunized B10.RIII mice developed predominantly in hybrid offspring that had inherited at least one copy of wild type T cell receptor (TCR) genes (V beta b genotype) from the B10 or B10.RIII parent. The results indicate that, in the development of PII-CIA, mice expressing the H-2r/r haplotype preferentially utilize TCR V beta genes that are normally encoded within the TCR V beta genomic deletion region of RIIIS mice (V beta c). After aggressive immunization with PII, the use of alternative TCR V beta genes, encoded outside of the RIIIS deletion region, produced a high IgG antibody response that was cross-reactive with mouse type II collagen (MII) and equivalent to that of B10.RIII mice, but only a very mild, late onset arthritis of 56% (27/48) incidence in RIIIS male mice and 28% (10/35) incidence in RIIIS female mice. In comparison, B10.RIII mice routinely developed early onset of PII-CIA of significantly higher incidence (100%; p < 0.005) and four-fold greater severity, even after milder immunization protocols. The data are compatible with the proposal that the clinically weak CIA response of RIIIs mice may be primarily antibody driven while the severe CIA of B10.RIII mice reflects the added inflammatory effects of collagen-reactive effector-T cells in the joint.(ABSTRACT TRUNCATED AT 250 WORDS)

No restriction of intrathyroidal T cell receptor V alpha families in the thyroid of Graves' disease

Recently it has been reported that the intrathyroidal T cells in Graves' disease display restriction in V alpha T cell receptor (TcR) gene family usage, although this is not found with TcR V beta gene families in the same individuals. We have performed a qualitative analysis of TcR V alpha family usage in 12 patients with Graves' disease by reverse transcription and polymerase chain reaction (PCR) amplification of RNA extracted from isolated, unstimulated intrathyroidal lymphocytes and from snap-frozen whole thyroid specimens. No restriction was observed, with 10-15 V alpha gene families being amplified in all cases. The pattern of usage was similar to that in peripheral blood lymphocytes derived from normal subjects (n = 3) and from patients with Graves' disease (n = 3), as well as that present in the thyroids of patients with non-autoimmune toxic multinodular goitre (n = 4). These results indicated that there is no marked restriction of the unselected intrathyroidal T cell population in patients with Graves' disease who have been treated with antithyroid drugs.

Superantigens and their potential role in human disease

In the past few years, there has been a virtual explosion of information on the viral and bacterial molecules now known as superantigens. Some structures have been defined and the mechanism by which they interact with MHC class II and the V beta region of the T cell receptor is being clarified. Data are accumulating regarding the importance of virally encoded superantigens in infectivity, viral replication, and the life cycle of the virus. In the case of MMTV, evidence also suggests that superantigens encoded by a provirus may be maintained by the host to protect against future exogenous MMTV infection. Experiments in animals have also begun to elucidate the dramatic and variable effects of superantigens on responding T cells and other immune processes. Finally, the role of superantigens in certain human diseases such as toxic shock syndrome, some autoimmune diseases like Kawasaki syndrome, and perhaps some immunodeficiency disease such as that secondary to HIV infection is being addressed and mechanisms are being defined. Still, numerous important questions remain. For example, it is not clear how superantigens with such different structures, for example, SEB, TSST-1, and MMTV vSAG, can interact with MHC and a similar region of the TCR in such basically similar ways. It remains to be determined whether there are human equivalents of the endogenous murine MMTV superantigens. The functional role of bacterial superantigens also remains to be explained. Serious infection and serious consequences from toxin-producing bacteria are relatively rare events, and it is questionable whether such events are involved in the selection pressure to maintain production of a functional superantigen. Hypotheses to explain these molecules, which can differ greatly in structure, include T cell stimulation-mediated suppression of host responses or enhancement of environments for bacterial growth and replication, but substantiating data for these ideas are mostly absent. It also seems likely that only the tip of the iceberg has been uncovered in terms of the role of superantigens in human disease. Unlike toxic shock syndrome, other associations, especially with viral superantigens, may be quite subtle and defined only after considerable effort. The definition of these molecules and mechanisms of disease may result in new therapeutic strategies. Finally, it is apparent that superantigens have dramatic effects on the immune system. One wonders whether these molecules or modifications of them can be used as specific modulators of the immune system to treat disease.

An altered repertoire of T cell receptor V gene expression by rheumatoid synovial fluid T lymphocytes

The pattern of T cell receptor V gene expression by lymphocytes from rheumatoid synovial fluid and paired peripheral blood samples was compared using a polymerase chain reaction (PCR)-based assay. Eight rheumatoid arthritis (RA) patients who had varying durations of disease (from 2 to 20 years) were studied. In all patients there was evidence of a different pattern of V gene expression between the two compartments. Significantly increased expression of at least one V alpha or V beta gene family by synovial fluid T cells was observed in all the patients studied. Three different V alpha (V alpha 10, 15 and 18) and three V beta (V beta 4, 5 and 13) families were commonly elevated. Sequencing of synovial V beta transcripts demonstrated that the basis of increased expression of selected V gene families in the synovial fluid was due to the presence of dominant clonotypes within those families, which constituted up to 53% of the sequences isolated from one particular synovial V gene family. There were considerable differences in the NDJ sequences found in synovial and peripheral blood T cell receptor (TCR) transcripts of the same V beta gene family. These data suggest that the TCR repertoire in the two compartments differs, and that antigen-driven expansion of particular synovial T cell populations is a component of rheumatoid synovitis, and is present in all stages of the disease.

Limited heterogeneity of T cell receptor variable region gene usage in juvenile rheumatoid arthritis synovial T cells

The aim of this study was to determine whether synovial fluid (SF) T cells in patients with juvenile rheumatoid arthritis (JRA) are restricted in their T cell receptor (TcR) gene repertoire. The quantitative polymerase chain reaction (QPCR) was used to compare the transcription of V beta and V alpha gene families in freshly isolated SF T cells, in interleukin-2 receptor-positive (IL-2R+) T cells and in peripheral blood (PB) T cells from 18 patients. Significantly less V beta families are detected in SF when compared with PB (p greater than 0.0003). The TcR V beta gene usage by IL-2R+ T cells was even less heterogeneous when compared with freshly isolated SF T cells (p greater than 0.0002). Freshly isolated SF T cells from the left and the right knees of four patients transcribed the same V beta families. Furthermore, we demonstrate that in SF the distribution of certain TcR V beta gene segments in CD4+ and CD8+ T cells differed from that in PB of the same patient. The TcR V alpha usage was studied in IL-2R+ T cells from six patients who had shown restriction in their SF TcR V beta gene usage. Only two to five TcR alpha transcripts were detected in three of these patients while a broad TcR V alpha usage was seen in the other three patients. Sequence analysis of the SF V beta 20 cDNA clones generated from the IL-2R+ T cells of two patients demonstrated an oligoclonal expansion. Taken together, our data could indicate an antigen- and/or superantigen-driven expansion of selected T cells in the synovial compartment.

Structural aspects of recognition motifs contributing to autoimmune responses

Sequence analysis of autoimmune-associated antibodies has suggested a structural relatedness between genes used to encode autoantibodies and those encoding unrelated antibodies without autoreactive specificities. Subsequently, the basis for cross-reactive idiotypes across germ-line lineages, as well as conserved interspecies cross-reactivities of autoantigens among serologically similar antibodies, may result from evolutionary duplication of particular types of recognition motifs. As a first step toward elucidating structural recognition principles underlying possible cross-reactive epitopes involved in autoimmune pathologies, structural features of selected motifs associated with native ligand binding are examined for their inherent occurrence in antibody and T-cell receptor repertoires. This analysis considers the putative recognition features representative of common motif subsets shared with loop structures in CDR2 and FR3 regions of antibodies such as charge-2x-charge-x-charge or hydrogen bond donor (acceptor)-2x-charge-x-hydrogen bond donor (acceptor) type motifs, where x is any residue that can participate in maintaining a loop conformation. Such tracts encoded in the CRD2 and FR3 regions of heavy chains of antibodies and T-cell receptors (TCRs) associated with autoimmune dysfunction, with non-autoreactive antibodies, and with native host proteins. Such evolutionarily conserved motifs may be targets for complementary interactions involving autoantibodies and receptors.

Mycoplasma arthritidis mitogen. V beta engaged in mice, rats, and humans, and requirement of HLA-DR alpha for presentation

OBJECTIVE

Mycoplasma arthritidis mitogen (MAM) is mitogenic for mouse, rat, and human T cells, and behaves as a superantigen in mice through its capacity to bind to the alpha chain of I-E molecules and engage entire sets of T cells expressing specific V beta. Here, we have attempted to fully characterize the V beta-engaging activities of MAM in mice, and define similar activities in rats and humans.

METHODS

Multiprobe RNase-protection assays and mice transgenic for human DR alpha, DR beta, and DR alpha beta were utilized for this purpose.

RESULTS

MAM-reactive V beta in the mouse included not only the previously reported V beta 6, V beta 8.1, V beta 8.2, and V beta 8.3, but also V beta 5.1. In the rat, engagement of V beta 5.1, V beta 6, V beta 8.1, and V beta 8.2, but not V beta 8.3, was documented, whereas in humans, the engaged V beta included primarily V beta 19.1 (alternatively termed V beta 17.1) and, to a lesser extent, V beta 3.1, V beta 11.1, V beta 12.1, and V beta 13.1. In DR transgenic E alpha- E beta- mice, presentation of MAM and engagement of specific V beta was effected by DR alpha.

CONCLUSIONS

Homologous V beta are engaged by MAM in mice, rats, and humans, presumably through a binding site similar to that proposed previously for other superantigens. MAM presentation primarily via the nonpolymorphic DR alpha makes it unlikely that there is involvement of such a superantigen in the pathogenesis of autoimmune diseases known to be associated with certain DR haplotypes. The possibility cannot be excluded, however, that superantigen-activated T cells may lead to disease by cross-reactions with self-antigens presented by particular DR haplotypes.

T-cell receptor V beta chain expression in patients with juvenile rheumatoid arthritis

The V beta chain repertoire in peripheral blood T-cell was analyzed in 23 patients with juvenile rheumatoid arthritis (JRA). Of these, 15 patients had active disease as defined by tender and swollen joints. The ESR was elevated in all but three patients, C-reactive protein (CRP) was elevated in eight. Three patients were investigated during active and inactive phases of the disease. In the active phase of the disease T-cell composition was characterized by an increased number of CD4+ helper cells due to a marked increase in the CD4+CD45RA+ subgroup (34.0 +/- 10.9%, P < 0.001) and a decrease in CD8+CD29+ T-cells (10.3 +/- 5.6%, P < 0.05) compared to controls (15.4 +/- 10.0% and 17.8 +/- 12.3%, respectively). Using the monoclonal antibodies available to determine T-cell receptor (TCR) expression, patients with active disease demonstrated a significant predominance of T-cells bearing TCRs of the V beta 5 family as determined by flow cytometry (7.6 +/- 6.7 vs 3.4 +/- 1.3 in controls, P = 0.01). In active polyarthritis, up to 24% of peripheral blood T-cells expressed TCRs of the same family. In the majority of JRA patients and especially in non-active disease, no preferential TCRs were found compared to controls. However, even defining only a part of TCRs by immunofluorescence, in certain patients a preferential or dominant expression of a single V beta gene family in the T-cells was found, supporting the concept of an involvement of T-cells in the autoimmune pathogenesis of JRA.