T cell receptor repertoire of infiltrating T cells in lips of Sjögren's syndrome patients

Antigen-driven T cell responses in rheumatic diseases: insights from T cell receptor repertoire studies

Advances in T cell receptor (TCR) profiling techniques have substantially improved our ability to investigate T cell responses to antigens that are presented on HLA class I and class II molecules and associations between autoimmune T cells and rheumatic diseases. Early-stage studies in axial spondyloarthritis (axSpA) identified disease-associated T cell clonotypes, benefiting from the relative genetic homogeneity of the disease. However, both the genetic and the T cell immunological landscape are more complex in other rheumatic diseases. The diversity or redundancy in the TCR repertoire, epitope spreading over disease duration, genetic heterogeneity of HLA genes or other loci, and the diversity of epitopes contributing to disease pathogenesis and persistent inflammation are all likely to contribute to this complexity. TCR profiling holds promise for identifying key antigenic drivers and phenotypic T cell states that sustain autoimmunity in rheumatic diseases. Here, we review key findings from TCR repertoire studies in axSpA and other chronic inflammatory rheumatic diseases including psoriatic arthritis, rheumatoid arthritis, systemic lupus erythematosus and Sjögren syndrome. We explore how TCR profiling technologies, if applied to better controlled studies focused on early disease stages and genetically homogeneous subsets, can facilitate disease monitoring and the development of therapeutics targeting autoimmune T cells, their cognate antigens, or their underlying biology.

Single-Cell Sequencing of T cell Receptors: A Perspective on the Technological Development and Translational Application

T cells recognize peptides bound to major histocompatibility complex (MHC) class I and class II molecules at the cell surface. This recognition is accomplished by the expression of T cell receptors (TCR) which are required to be diverse and adaptable in order to accommodate the various and vast number of antigens presented on the MHCs. Thus, determining TCR repertoires of effector T cells is necessary to understand the immunological process in responding to cancer progression, infection, and autoimmune development. Furthermore, understanding the TCR repertoires will provide a solid framework to predict and test the antigen which is more critical in autoimmunity. However, it has been a technical challenge to sequence the TCRs and provide a conceptual context in correlation to the vast number of TCR repertoires in the immunological system. The exploding field of single-cell sequencing has changed how the repertoires are being investigated and analyzed. In this review, we focus on the biology of TCRs, TCR signaling and its implication in autoimmunity. We discuss important methods in bulk sequencing of many cells. Lastly, we explore the most pertinent platforms in single-cell sequencing and its application in autoimmunity.

CD4+ T cells from patients with primary biliary cholangitis show T cell activation and differentially expressed T-cell receptor repertoires

AIM

Primary biliary cholangitis (PBC) is an autoimmune liver disease with unknown pathogenesis. In PBC, activation of T-cell receptor (TCR) signaling is associated with inflammatory cytokine production through N-Ras upregulation. Although the CD4⁺ T cell TCR repertoire could be associated with PBC pathogenesis, it has not been evaluated. Thus, we analyzed the PBC-CD4⁺ T cell TCR repertoire using next generation sequencing (NGS).

METHODS

Four PBC patients (one treatment-naïve and three receiving ursodeoxycholic acid) and three healthy individuals were enrolled. NRAS expression in CD4⁺ T cells was assessed by quantitative reverse transcription-polymerase chain reaction (qRT-PCR). N-Ras dynamics in CD4⁺ T cells were assessed by qRT-PCR and GTP-N-Ras activation assay. The TCR α- (TRA) and β-chain (TRB) repertoires on CD4⁺ T cells were analyzed by NGS and profiled using hierarchical analysis. Motif analysis was undertaken to elucidate the structure of PBC-specific TCRs.

RESULTS

NRAS was upregulated in PBC relative to control CD4⁺ T cells (P < 0.05), and N-Ras enhanced T cell activation in CD4⁺ T cells. Among 2668 TRAs and 841 TRBs, 20 and 11, respectively, were differentially expressed in PBC compared to that in controls (P < 0.05, fold-change >2). Among them, TRAV29/J22, TRBV6-5/J2-6, and TRBV10-1/J2-1 were expressed in PBC but the expression was negligible in the controls, with more mature and longer forms observed in PBC-CD4⁺ T cells.

CONCLUSIONS

N-Ras was upregulated in PBC-CD4⁺ T cells, and it enhanced TCR activation, indicating that PBC-CD4⁺ T cells were activated by N-Ras upregulation with differentially expressed TCR repertoires on their surfaces.

Insight into pathogenesis of Sjögren's syndrome: Dissection on autoimmune infiltrates and epithelial cells

Sjögren's syndrome (SS) is a chronic autoimmune disease with broad clinical spectrum, extending from benign exocrinopathy to severe systemic disease and lymphoma development. The glandular and extraglandular dysfunction of SS is associated with lymphocytic infiltrates that invade the epithelial structures of affected organs. The in-depth study of autoimmune lesions in the minor salivary glands (MSG), which are the major target-organ of SS responses, revealed that the lymphocytic infiltrates vary in severity and composition among SS-patients, are full-blown at diagnosis and remain unchanged thereafter. Although the pathogenetic pathways underlying SS have not yet elucidated, it is well-established that glandular epithelial cells are central regulators of local autoimmune responses. Moreover, chronic inflammation affects epithelial function and phenotype, which strengthens or weakens their immunoregulatory/secretory function, leading to deterioration of autoimmune phenomena. Herein, the current findings regarding the autoimmune lesions, the role of epithelial cells and their interaction with infiltrating lymphocytic cells are discussed.

Single-cell analysis of glandular T cell receptors in Sjögren's syndrome

CD4⁺ T cells predominate in salivary gland (SG) inflammatory lesions in Sjögren's syndrome (SS). However, their antigen specificity, degree of clonal expansion, and relationship to clinical disease features remain unknown. We used multiplex reverse-transcriptase PCR to amplify paired T cell receptor α (TCRα) and β transcripts of single CD4⁺CD45RA^- T cells from SG and peripheral blood (PB) of 10 individuals with primary SS, 9 of whom shared the HLA DR3/DQ2 risk haplotype. TCRα and β sequences were obtained from a median of 91 SG and 107 PB cells per subject. The degree of clonal expansion and frequency of cells expressing two productively rearranged α genes were increased in SG versus PB. Expanded clones from SG exhibited complementary-determining region 3 (CDR3) sequence similarity both within and among subjects, suggesting antigenic selection and shared antigen recognition. CDR3 similarities were shared among expanded clones from individuals discordant for canonical Ro and La autoantibodies, suggesting recognition of alternative SG antigen(s). The extent of SG clonal expansion correlated with reduced saliva production and increased SG fibrosis, linking expanded SG T cells with glandular dysfunction. Knowledge of paired TCRα and β sequences enables further work toward identification of target antigens and development of novel therapies.

Reduction of T cell receptor diversity in NOD mice prevents development of type 1 diabetes but not Sjögren's syndrome

Non-obese diabetic (NOD) mice are well-established models of independently developing spontaneous autoimmune diseases, Sjögren’s syndrome (SS) and type 1 diabetes (T1D). The key determining factor for T1D is the strong association with particular MHCII molecule and recognition by diabetogenic T cell receptor (TCR) of an insulin peptide presented in the context of I-A^g7 molecule. For SS the association with MHCII polymorphism is weaker and TCR diversity involved in the onset of the autoimmune phase of SS remains poorly understood. To compare the impact of TCR diversity reduction on the development of both diseases we generated two lines of TCR transgenic NOD mice. One line expresses transgenic TCRβ chain originated from a pathogenically irrelevant TCR, and the second line additionally expresses transgenic TCRα^mini locus. Analysis of TCR sequences on NOD background reveals lower TCR diversity on Treg cells not only in the thymus, but also in the periphery. This reduction in diversity does not affect conventional CD4⁺ T cells, as compared to the TCR^mini repertoire on B6 background. Interestingly, neither transgenic TCRβ nor TCR^mini mice develop diabetes, which we show is due to lack of insulin B:9–23 specific T cells in the periphery. Conversely SS develops in both lines, with full glandular infiltration, production of autoantibodies and hyposalivation. It shows that SS development is not as sensitive to limited availability of TCR specificities as T1D, which suggests wider range of possible TCR/peptide/MHC interactions driving autoimmunity in SS.

Primary Sjögren's syndrome complicated by sarcoidosis and psoriasis vulgaris

Abstract Primary Sjögren's syndrome (SS), sarcoidosis (SA), and psoriasis vulgaris (PV) are all chronic diseases of unknown etiology. Recent studies suggest that activated T cells play a central role in their pathogenesis. We describe a case of a Japanese woman with primary SS complicated by SA and PV. To our knowledge, this is the first case in which these three diseases coexist. Although these three disorders may have a common immunopathogenic mechanism, the extreme rarity of their coexistence suggests that distinct etiological mechanisms are also involved and appear to play an important role in triggering and developing each disease.

The role of M3 muscarinic acetylcholine receptor reactive T cells in Sjögren's syndrome: a critical review

CD4+ T cells constitute the majority of infiltrating cells in salivary glands and lachrymal glands of patients with Sjögren's syndrome (SS). The pathophysiology of SS involves T cell recognition of antigens through the T cell antigen receptor, which triggers cytokine production and chronic inflammation. The M3 muscarinic acetylcholine receptor (M3R) molecule is expressed in exocrine glands, such as salivary glands and lachrymal glands, and plays an important role in exocrine secretion. Previous studies indicated the presence of M3R reactive T cells in peripheral blood of 40% of patients with SS and autoantibodies against M3R in sera of 9-100% of the same patients. Thus, M3R is considered a candidate receptor for autoantigen recognition by T and B cells. The relationship between B cell epitopes and the function of anti-M3R antibodies has been reported, suggesting the pathogenic role of anti-M3R antibodies in xerostomia commonly seen in SS patients. We generated new experimental mouse model, M3R-induced sialadenitis (MIS), using Rag1(-/-) mice inoculated with splenocytes from M3R(-/-) mice immunized with M3R synthetic peptides. Mice with MIS developed severe SS-like sialadenitis. Cell transfer experiments using M3R(-/-)xIFNγ(-/-) mice and M3R(-/-)xIL-17(-/-) mice showed that IFNγ and IL-17 are key cytokines in the pathogenesis of sialadenitis. These findings indicate the crucial roles of M3R-reactive Th1 and Th17 cells in autoimmune sialadenitis, and suggest that these cells, in addition to anti-M3R antibodies, are potential targets in new treatments for SS.

Sulfamethoxazole induces a switch mechanism in T cell receptors containing TCRVβ20-1, altering pHLA recognition

T cell receptors (TCR) containing Vβ20-1 have been implicated in a wide range of T cell mediated disease and allergic reactions, making it a target for understanding these. Mechanics of T cell receptors are largely unexplained by static structures available from x-ray crystallographic studies. A small number of molecular dynamic simulations have been conducted on TCR, however are currently lacking either portions of the receptor or explanations for differences between binding and non-binding TCR recognition of respective peptide-HLA. We performed molecular dynamic simulations of a TCR containing variable domain Vβ20-1, sequenced from drug responsive T cells. These were initially from a patient showing maculopapular eruptions in response to the sulfanilamide-antibiotic sulfamethoxazole (SMX). The CDR2β domain of this TCR was found to dock SMX with high affinity. Using this compound as a perturbation, overall mechanisms involved in responses mediated by this receptor were explored, showing a chemical action on the TCR free from HLA or peptide interaction. Our simulations show two completely separate modes of binding cognate peptide-HLA complexes, with an increased affinity induced by SMX bound to the Vβ20-1. Overall binding of the TCR is mediated through a primary recognition by either the variable β or α domain, and a switch in recognition within these across TCR loops contacting the peptide and HLA occurs when SMX is present in the CDR2β loop. Large binding affinity differences are induced by summed small amino acid changes primarily by SMX modifying only three critical CDR2β loop amino acid positions. These residues, TYRβ57, ASPβ64, and LYSβ65 initially hold hydrogen bonds from the CDR2β to adjacent CDR loops. Effects from SMX binding are amplified and traverse longer distances through internal TCR hydrogen bonding networks, controlling the overall TCR conformation. Thus, the CDR2β of Vβ20-1 acts as a ligand controlled switch affecting overall TCR binding affinity.

T cell receptor variable β20-1 harbors a nucleotide binding pocket in the CDR2β loop

Novel aspects of T cells containing TCRVβ20-1 are numerous, ranging from pathogen specific reactivity to specific tissue homing, or possible T cell subsets. Recently, it was demonstrated that TCR itself could become reactive by binding to small molecules free of the pHLA interface. Our work here was to identify a natural ligand binding to an identified pocket on the CDR2β loop of these TCR. Using docking of suspected ligands, we were able to show Guanine and Adenine di- and tri-nucleotides readily bind to the identified site. Comparing these with small molecule sites found on other TCR types, we show this interaction is novel. With further molecular dynamic simulations, these sites are shown to be plausible by conducting simple computational based solubility tests as cross validation. Combined with simple proliferative responses, the identified nucleotides are also shown to have functional consequences by inducing T cell proliferation for CD4/Vβ20-1 + T cells, while failing to induce proliferation in other T cell isolates. Merging computational and simple cell assays, this work establishes a role of nucleotides in T cells found to contain this TCR sub-type.

Pathogenic role of anti-M3 muscarinic acetylcholine receptor immune response in Sjögren's syndrome

M3 muscarinic acetylcholine receptor (M3R) is expressed in exocrine glands (e.g., salivary glands [SGs] and lachrymal glands), and plays a crucial role in exocrine secretion. M3R reactive T cells have been detected in circulating mononuclear cells of 40% of patients with Sjögren's syndrome (SS), and the major T cell epitopes of M3R in those patients with HLA-DR B1×0901 are located in the second loop of M3R. Moreover, autoantibodies (autoAbs) against M3R are also present in sera of around 50% of patients with SS, and several B cell epitopes, such as N-region, 1st, 2nd, and 3rd loop of M3R, have been identified. Functional analysis using human SG cell lines showed that autoAbs against the 2nd loop of M3R suppressed intracellular Ca(2+) influx, suggesting inhibition of saliva secretion. To clarify whether the M3R reactive immune response induces autoimmune sialadenitis (AIS), M3R(-/-) mice were immunized with M3R synthetic peptides and their splenocytes transferred into Rag1(-/-) mice. The recipients developed severe sialadenitis, and cell transfer studies indicated that T cells are key factors in the pathogenesis of AIS. These results indicate that the M3R immune reaction plays a key pathogenic role in AIS, suggesting that M3R molecule acts as an autoantigen in the pathogenesis of SS.

Functional role of M3 muscarinic acetylcholine receptor (M3R) reactive T cells and anti-M3R autoantibodies in patients with Sjögren's syndrome

Sjögren's syndrome (SS) is an autoimmune disease characterized by lymphocytic infiltration into the lachrymal and salivary glands, leading to dry eyes and mouth. Infiltration is also found in the kidneys, lungs, thyroid, and liver. Immunohistochemical studies have shown that most infiltrating lymphocytes are CD4(+) T cell receptor (TCR) alphabeta T cells. The antigen specificity of T cells is decided by TCR expressed on T cells. The usage of TCRalpha and TCRbeta genes have been examined by immunological and molecular biological methods. Autoantigens recognized by T cells infiltrating into salivary glands have been analyzed and several candidates for autoantigens have been clarified. In the present study, we focused on M3 muscarinic acetylcholine receptor (M3R) as a salivary gland-specific autoantigen and clarified T cell epitopes and B cell epitopes on M3R. The functions of anti-M3R antibodies and M3R reactive T cells were also carried out. To clarify whether M3R reactive T cells play a crucial role in the generation of autoimmune sialoadenitis, splenic CD3+T cells form M3R(-/-) mice immunized by M3R peptides were transferred into Rag-1(-/-) mice and sialoadenitis analyzed. The functional role of M3R reactive T cells in the generation of SS was also discussed.

Selective expansion of T cell receptor (TCR) V beta 6 in tonsillar and peripheral blood T cells and its induction by in vitro stimulation with Haemophilus parainfluenzae in patients with IgA nephropathy

IgA nephropathy (IgAN), the most common form of primary glomerulonephritis, is recognized as a disease that often becomes worse during acute tonsillitis. Although many reports have shown that tonsillectomy is an effective treatment for IgAN patients, the immunological evidence has not yet been investigated fully. In this study, we compared the expression of T cell receptor (TCR) V beta families in tonsillar T cells of IgAN patients to those of non-IgAN patients. The reverse transcription-polymerase chain reaction (RT-PCR) and flow cytometric analyses showed that the TCR V beta 6 was used more frequently in tonsillar T cells of IgAN patients than in those of non-IgAN patients (P < 0.01 each). Similarly, the proportions of TCR V beta 6-positive cells in peripheral blood T cells were significantly higher in IgAN patients than in non-IgAN patients (P < 0.05). After tonsillectomy, the proportions decreased in IgAN patients (P < 0.05), but did not in non-IgAN patients. Furthermore, in vitro stimulation with Haemophilus parainfluenzae antigen, which is reported to deposit in the glomerular mesangium of IgAN, enhanced expression of TCR V beta 6 in tonsillar T cells from both IgAN and non-IgAN patients. These results suggest that TCR V beta 6-positive tonsillar T cells might be activated by H. parainfluenzae, move into the kidney through blood circulation and induce glomerulonephritis.

Immunopathogenesis of primary sclerosing cholangitis

Primary sclerosing cholangitis (PSC) is a chronic cholestatic liver disease of unknown etiology;however, lymphocytic portal tract infiltration is suggestive of an immune-mediated basis for PSC. Associations with inflammatory bowel disease--especially ulcerative colitis--and with other auto-immune diseases, together with genetic associations, further suggest that PSC may be an immune-mediated disease. The immunogenetics of PSC have been the subject of active research, and several human leukocyte antigen (HLA)- and non-HLA-associated genes have been implicated in the development of the disease. Lymphocytes derived from the inflamed gut may enter the liver via the enterohepatic circulation to cause hepatic disease.PSC may be triggered in genetically susceptible individuals by infections or toxins entering the portal circulation through a permeable colon and, therefore, evoking an abnormal immune response.

Different effects on the inflammatory lesions in the lacrimal and salivary glands after neonatal thymectomy in IQI/Jic mice, a model for Sjögren's syndrome

Thymectomy on day 3 after birth (D3Tx) is understood to eliminate CD4+CD25+ regulatory T cells (Treg) from the peripheral T cell repertoire in rodents, leading to the activation of autoreactive T cells. Herein, D3Tx was performed in IQI/Jic mice, a model for Sjögren's syndrome characterized by autoimmune infiltrations into the lacrimal and salivary glands. At the age of 16 weeks, very severe lesions were observed in lacrimal tissues from thymectomized mice, suggesting that Treg preserve their immunoregulatory function in young IQI/Jic mice. In contrast, salivary lesions were comparable in the D3Tx and control groups, raising the possibility that either salivary-specific Treg escaped elimination in thymectomized mice or spontaneous lesions in IQI/Jic mice developed independently of the tolerance through Treg.

Analysis of the insertion/deletion related polymorphism within T cell antigen receptor beta variable genes in primary Sjögren's syndrome

OBJECTIVE

To analyse T cell receptor beta variable (TCRBV) gene polymorphisms (insertion/deletion related polymorphism (IDRP) and BV6S7) in primary Sjögren's syndrome (PSS).

METHODS

Genomic DNA was extracted from blood samples from patients fulfilling the modified European criteria for PSS (n = 61). Healthy control blood samples were obtained from the Blood Transfusion Service (n = 121). As a disease control group, samples from patients with systemic lupus erythematosus (n = 42) were analysed. BV6S7 was genotyped using an established PCR/RFLP method. The IDRP was determined by comparison of the intensity of PCR product bands from within BV9S2 and an internal control region (BV9S1), to ascertain whether 0, 1, or 2 copies of the insertion were present.

RESULTS

There was a decrease (p = 0.018) in the proportion of PSS patients with the deleted/deleted genotype. There was no association with specific BV6S7 alleles or genotypes with either the PSS group or the hypergammaglobulinaemic subgroup. There were no significant differences in haplotype frequencies after Bonferroni correction.

CONCLUSIONS

A reduced proportion of patients with PSS have the deleted/deleted genotype. Eighty nine per cent of PSS patients have at least one extra germline copy of BV13S2*1. This may relate to previous observations of increased BV13 specific T cells and mRNA in the salivary glands.

Characterization of the Interstitial Lung and Peripheral Blood T Cell Receptor Repertoire in Cigarette Smokers

T lymphocytes modulate the pulmonary inflammatory response. The aim of this study was to evaluate the clonality within the interstitial lung and peripheral blood T cell receptor (TCR) repertoire in smokers. Interstitial T lymphocytes were isolated from surplus tissue of 16 patients (63 +/- 9 [+/- SD] yr old, 11 male) undergoing surgery due to lung cancer (n = 15) or emphysema. TCR clonality was assessed by PCR amplification followed by spectratyping. Nearly all TCR of interstitial lung lymphocytes showed oligoclonal bands (CD4(+) subset 13/16 patients, 81%; CD8(+) 100%) indicating a specific differentiation. Peripheral blood T lymphocytes (PBL) TCR (especially CD4(+)) had less oligoclonal bands (CD4(+) 31%, CD8(+) 88%). Likewise, more oligoclonal bands were seen in lung TCR (total of 168 bands; 37 CD4(+); 131 CD8(+)), compared with 59 bands in PBL TCR (13 CD4(+); 46 CD8(+)). Intraindividual comparison revealed a more prominent difference in TCR oligoclonality between lung and blood in CD8(+) T cells (median of difference lung minus blood 5; interquartile range 1-10; P = 0.002) compared with CD4(+) T cells (median 2, 0-3, P = 0.039). Thus, TCR oligoclonality is preferentially found in the CD8(+) T cell subset, most distinctive in the lung. These findings indicate a specific interstitial T cell differentiation in response to local stimuli.

Primary sclerosing cholangitis

Primary sclerosing cholangitis (PSC) is a fibrosing disease of the intra- and extra-hepatic bile ducts, and is closely associated with inflammatory bowel disease. It is immune mediated, rather than being a classical autoimmune disease. A range of immune abnormalities have been demonstrated in PSC, in particular the findings of a range of autoantibodies, a portal tract infiltrate of functional T cells, a restricted T-cell receptor repertoire, and aberrant expression of HLA molecules on biliary epithelial cells. The immunogenetics of PSC is currently under study and to date 4 key HLA haplotypes associated with PSC have been developed. The trigger factor for the initiation of the immune response may be the ingress of bacteria or other toxic metabolites into the portal circulation through a diseased and permeable bowel wall.

Genomic absence of the gene encoding T cell receptor Vbeta7.2 is linked to the presence of autoantibodies in Sjögren's syndrome

OBJECTIVE

It is not yet known whether the absence of certain T cell receptor V(beta) (TCRBV) genes (e.g., due to genomic deletion) has functional significance. We examined this question in relation to a known 21.6-kb insertion/deletion-related polymorphism (IDRP) in the human BV locus.

METHODS

New polymerase chain reaction (PCR) genotyping methods were used. Monoclonal antibodies to TCRBV gene products were used to confirm the absence of the relevant proteins. Patients with Sjögren's syndrome (SS) or systemic lupus erythematosus (SLE) were compared with normal controls with regard to TCR genotypes and serologic profiles.

RESULTS

There are 3 known haplotypes (I, D1, D2) and 6 possible genotypes related to the 21.6-kb IDRP. Novel PCR-based methods were used to define these genotypes. In subjects with deleted/deleted (D/D) genotypes, T cells could not express V(beta)7.2 TCRs, as assayed with a new antibody specific for V(beta)7.2. This was the sole significant difference between subjects without the insertion and those with either 1 or 2 copies. Surprisingly, we found that the D/D genotype was associated with primary SS, but only when pathogenic autoantibodies were present.

CONCLUSION

These results suggest that T cells expressing TCRs with V(beta)7.2 are protective against a pathogenic immune response in SS. Thus, genomic polymorphism of TCR genes (along with the correct HLA alleles) determines whether T cells can direct a pathogenic autoimmune response.

Development of autoimmune exocrinopathy resembling Sjögren's syndrome in adoptively transferred mice with autoreactive CD4+ T cells

OBJECTIVE

The pathologic mechanisms responsible for organ-specific tissue damage in primary Sjögren's syndrome (SS) remain unclear, but it has been suggested that the pathology is mediated by autoreactive CD4+ T cells infiltrating the salivary and lacrimal glands. This study was undertaken to investigate whether alpha-fodrin autoantigen-specific autoreactive CD4+ T cells are capable of inducing autoimmune lesions.

METHODS

A total of 45 synthetic alpha-fodrin peptides designed to be 20 amino acid residues in length were generated. To establish an autoreactive T cell line, limiting dilution analysis (LDA) was performed on lymph node cells (LNCs) in the presence of alpha-fodrin peptides. The effects of adoptive transfer of autoreactive CD4+ T cells into normal syngeneic recipients were investigated.

RESULTS

Autoreactive CD4+ T cell lines that recognize synthetic alpha-fodrin peptide, which produced Th1 cytokines and showed cytotoxic activities, were established in a murine model for SS. T cell receptor V(beta) usage and third complementarity-determining region (CDR3) sequences indicated that in some cases V(beta)6-CDR3 genes matched between the tissue-infiltrating T cells and the autoreactive T cell lines. Adoptive transfer of the autoreactive CD4+ T cells into normal syngeneic recipients induced autoimmune lesions quite similar to those of SS.

CONCLUSION

Our data help to elucidate the pathogenic mechanisms responsible for tissue destruction in autoimmune exocrinopathy and indicate that autoreactive CD4+ T cells play a pivotal role in the development of murine SS.

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.

T cell receptor repertoire of T cells in the kidneys of patients with lupus nephritis

OBJECTIVE

To determine the role of T cells in the pathogenesis of lupus nephritis (LN).

METHODS

Renal biopsy specimens from 12 patients with systemic lupus erythematosus were used for the experiments. We analyzed T cell receptor (TCR) Vbeta1-20 family genes on intrarenal T cells and on peripheral blood lymphocytes (PBLs) by nested reverse transcriptase-polymerase chain reaction (PCR) and Southern blot analysis. Nucleotide sequence was determined in the third complementarity-determining region of the TCR Vbeta gene in expanded T cells. Messenger RNA (mRNA) expression levels of Th1 and Th2 cytokines on infiltrating T cells were measured by nested PCR.

RESULTS

The repertoire of TCR Vbeta in intrarenal T cells was relatively restricted compared with that in PBLs. The TCR Vbeta8 and TCR Vbeta20 genes were preferentially expressed in 6 of 12 patients (50%) and the TCR Vbeta9 and TCR Vbeta14 genes were expressed in 5 of 12 patients (42%). Junctional sequences of complementary DNA encoding the TCR Vbeta8 and TCR Vbeta20 genes in intrarenal T cells showed oligoclonal expansion, indicating antigen-driven stimulation. Interleukin-4 (IL-4) and IL-10 mRNA were highly expressed on intrarenal T cells, while interferon-gamma mRNA was not detected.

CONCLUSION

Our findings suggest that T cells infiltrating the kidneys of patients with LN may recognize restricted epitopes on antigens and function as Th2-type T cells.

Conserved CDR 3 region of T cell receptor BV gene in lymphocytes from bronchoalveolar lavage fluid of patients with idiopathic pulmonary fibrosis

Idiopathic pulmonary fibrosis (IPF) is an inflammatory lung disease characterized by the accumulation of inflammatory cells and deposition of collagen, resulting in lung remodelling. High numbers of T cells are present in bronchoalveolar lavage fluid (BALF) of IPF patients, although the characteristics of these cells are yet to be determined. To elucidate the pathogenic mechanisms of IPF, we analysed the T cell receptor (TCR) of BALF lymphocytes in three patients with IPF and three healthy subjects as control. TCR repertoire of BALF lymphocytes and T cell clonality were examined by family PCR and Southern blot analysis, and single-strand conformation polymorphism (SSCP), respectively. We observed that the TCR repertoire in the lung was heterogeneous, both in the control subjects and three patients with IPF. SSCP analysis demonstrated an increase in the number of accumulated T cell clones in BALF of two of the three patients, but not in the healthy subject. Furthermore, junctional sequence analysis showed the presence of conserved amino acid motifs (ETGRSG, LAxG, QGQ, GxQP, GRxG, VAR, PGT, GTI, GGT, TGR, LxLxQ, SGQ) in the TCR-CDR 3 region of BAL lymphocytes in patients with IPF, whereas only two amino acid motifs (VTTG, GGE) were found in the control. Our findings suggest that T cells in BALF of patients with IPF expand oligoclonally in the lung, suggesting antigen stimulation of these cells.

Current issues in Sjögren's syndrome

Sjögren's syndrome is a chronic autoimmune and rheumatic disorder with prominent sicca complaints from the mucous membranes because of lack of proper exocrine secretions. There is no straightforward and simple diagnostic test for Sjögren's syndrome, although several classification criteria have been designed including several oral diagnostic tests. A new set of classification criteria in a joint effort by research groups in Europe and USA has recently been presented. A large number of autoantibodies have been reported in Sjögren's syndrome where, in some cases, the antibodies are correlated with the extent and severity of disease. The finding of serum autoantibodies directed against the muscarinic M3 receptor is an important advance in understanding the pathogenesis of not only the impaired glandular function but also associated features of autonomic dysfunction in some patients. The treatment of primary Sjögren's syndrome is still mainly symptomatic.

Human glomerulonephritis accompanied by active cellular infiltrates shows effector T cells in urine

Leukocyturia is associated with postinfectious glomerulonephritis (GN), interstitial nephritis, and renal allograft rejection. In addition, prominent infiltration of T cells and macrophages is commonly observed in the renal tissues of patients with GN, accompanied by cellular crescent formation and/or interstitial cell infiltration. Because these infiltrating T cells were thought to participate in the development of the diseases and to appear in the urinary space while functioning as effector cells in the renal inflammatory lesion, the study focused on the characterization of T cells that appeared in urine. Freshly voided urine cells were analyzed by flow cytometry to determine their phenotype and by reverse transcriptase-PCR to detect cytokine mRNA. In urine from patients with different forms of GN, including IgA nephropathy, Henoch-Schönlein purpura nephritis, and anti-neutrophil cytoplasmic antibody-associated GN, T cells appeared together with macrophages. The urine T cells were mainly CD45RA(-), CD45RO(+), and CD62L (L-selectin)(-), which are the phenotypic features of effector T cells. In agreement with this finding, T cells infiltrating glomeruli, crescents, and tubulointerstitial lesions were also effector type. Moreover, these urine cells expressed mRNA of the T helper lymphocyte 1 cytokines, interleukin-2, and/or interferon-gamma. These findings suggest that the appearance of effector T cells in urine may reflect the cellular immune reaction that occurs in the kidneys of patients with GN accompanied by active cell infiltration.

Novel immunosuppressive effect of FK506 by augmentation of T cell apoptosis

We have recently reported the accumulation of oligoclonal activated T cells in the spontaneously developed autoimmune pancreatitis in aly/aly mouse. In this study, we examined the effects of FK506 in this mouse model in preventing autoimmune pancreatitis and investigated its action on calcium signalling apoptosis of alymphoplasia (aly) lymphocytes in vitro. Mice were treated with FK506 from 8 to 25 weeks of age. At the age of 15 weeks, minimal mononuclear cell infiltration was observed in the pancreas in both the FK506 treated group and the control group. Furthermore, a marked cell infiltration associated with destruction of acini and partial fatty changes were observed in 25-week-old control mice. In contrast, FK506 treated mice showed almost no tissue destruction or mononuclear cell infiltration at the age of 25 weeks. Furthermore, at 15 weeks of age, most mononuclear cells in FK506-treated mice were TUNEL positive, whereas only a few were positive in control mice. This augmentation of T cell apoptosis by FK506 was confirmed using naive splenocytes activated by PMA and ionomycin in vitro. Finally, a suppressive effect of FK506 on Bcl-2 production but not on Bax production was confirmed by Western blotting. This unique effect of FK506 on the augmentation of T cell apoptosis is probably one of the mechanisms explaining its beneficial effect on aly autoimmune pancreatitis.

Analysis of T-cell subpopulations in T-cell non-Hodgkin's lymphoma of angioimmunoblastic lymphadenopathy with dysproteinemia type by single target gene amplification of T cell receptor- beta gene rearrangements

Angioimmunoblastic lymphadenopathy with dysproteinemia (AILD) is defined in the current lymphoma classifications as a T-cell non-Hodgkin's lymphoma. However, in approximately one third of the cases of this lymphoproliferative disease rearrangements of T-cell receptor (TCR) genes indicating clonal expansion of T cells are not detectable. It is currently believed that these cases may represent early stages of a lymphoma with a minor oligoclonal T-cell population. In the present study, 18 lymph nodes with the characteristic histology of AILD were investigated for clonal T-cell receptor gene rearrangements by analysis of DNA extracted from whole tissue sections. Dominant T-cell clones were detected in 12 of these cases. Single CD4(+) and CD8(+) T cells and proliferating Ki67(+) cells of seven cases were micromanipulated from frozen tissue sections. TCRbeta gene rearrangements were amplified from these cells by polymerase chain reaction and sequenced. In all informative cases, the clonal gene rearrangements were only detected among CD4(+), and not among CD8(+) T cells, indicating that the tumor clones in AILD usually derive from CD4(+) T cells. Minor clonal T-cell populations in those cases in which no clone was found by whole-tissue DNA analysis were not detectable even at single cell resolution. T-cell clones in 4 of 10 cases were found to express similar TCRbeta chains, indicating a potential role of (super) antigen triggering in at least some cases of AILD.

Glandular and extraglandular expression of costimulatory molecules in patients with Sjögren's syndrome

OBJECTIVES

To investigate the expression and regulation of CD80, CD86, and CD28 costimulatory molecules in sialoadenitis and interstitial nephritis in patients with Sjögren's syndrome (SS).

METHODS

Expression of CD80, CD86, and CD28 molecules was studied by immunohistochemical staining of lip biopsy specimens obtained from patients who had sialoadenitis associated with SS, and renal biopsy specimens obtained from patients who had interstitial nephritis associated with SS. To elucidate the mechanism of de novo expression of CD80 and CD86 antigens, their induction by cytokines in human salivary duct cell line (HSG) and renal cortical epithelial cells (HRCE) by cell enzyme linked immunosorbent assay (ELISA) was quantitatively investigated.

RESULTS

In patients with severe sialoadenitis, CD80 and CD86 were strongly expressed on ductal epithelial cells. In contrast, these antigens were not found in the minor salivary glands of normal subjects or of patients with mild sialoadenitis. Some infiltrating cells expressed CD28. In patients who had interstitial nephritis associated with SS, some tubular epithelial cells expressed CD86 but not the CD80 antigen. Unstimulated HSG cells did not express CD80 or CD86. Interferon gamma (IFNgamma) consistently up regulated levels of CD80 and CD86. In contrast, tumour necrosis factor alpha (TNFalpha), interleukin 1beta (IL1beta), IL2, and IL4 had no effect on either CD80 or CD86 levels. Unstimulated HRCE did not express CD80 or CD86. IFNgamma consistently up regulated CD86 expression. No CD80 expression was found on tubular cells. TNFalpha, IL1beta, IL2, and IL4 had no discernible effects.

CONCLUSIONS

Salivary ductal cells in patients with SS can express CD80 and CD86 costimulatory molecules in response to IFNgamma. Tubular epithelial cells in patients who have interstitial nephritis associated with SS express only CD86 molecules. In patients with SS, salivary ductal cells and tubular epithelial cells may activate infiltrating CD28 positive T lymphocytes by presenting antigens to T cells, potentially leading to tissue destruction.

Specific T-cell receptor usage with cytokinemia in Henoch-Schönlein purpura nephritis associated with Staphylococcus aureus infection

OBJECTIVES

We sought to evaluate the mechanism of Henoch-Schönlein purpura nephritis (HSPN) associated with Staphylococcus aureus (S. aureus) infection.

DESIGN

We evaluated six male patients with HSPN associated with S. aureus infection. Routine laboratory examinations, bacteriological examination, histological examination, and analysis of serum cytokine levels were performed in all cases. In addition, peripheral blood mononuclear cells (PBMC) obtained from the six patients and 45 normal individuals were stained with labelled-monoclonal antibodies against six variable parts of the beta-chain (Vbeta) of the T-cell receptor (TCR), and stained cells were analysed by flow cytometry.

RESULTS

Patients with HSPN associated with S. aureus infection showed features of the nephrotic syndrome with rapidly progressive glomerulonephritis, as well as varying degrees of mesangial proliferative glomerulonephritis with crescent formation. Serological examination showed elevated levels of serum IgA and IgG as well as immune complexes after the onset of infection. The percentage of Vbeta-(5.2 + 5.3) and Vbeta 8-positive cells in patients with HSPN were significantly higher than in normal individuals; moreover, specific TCR-Vbeta usage was not observed in patients with HSPN whose S. aureus infection had improved. Serum levels of IL-1beta, IL-2, IL-6, IL-8 and TNF-alpha in patients with HSPN were significantly higher than in normal individuals, and normalized at the healing stage of S. aureus infection.

CONCLUSION

Conventional antigens and/or staphylococcal enterotoxins originated from S. aureus might have been involved in the pathogenesis of HSPN in the present cohort. Therefore, steroid or other immunosuppressive therapies could not be utilized despite the high activity of glomerulonephritis, and as a result the prognoses of these cases of HSPN were serious.

Alternative splicing forms of the human CD1D gene in mononuclear cells

CD1d is a critical molecule for the presentation of lipid antigens to natural killer (NK) T cells. To investigate the molecular complexity of CD1d, alternatively spliced transcripts in peripheral blood mononuclear cells from three healthy subjects were analyzed by PCR and sequencing methods. We found eight alternatively spliced variants of the CD1D gene (V1-V8), seven of which are newly established variants (V2-V8). V1 and V4 are in-frame; however, the other six variants (V2, V3, V5-V8) are out-of-frame. V1, V2, V4, and V5 lack a beta(2)-microglobulin binding site (alpha3 domain), indicating the unstable presentation of the CD1d molecule on the surface. In V2 and V5, the transmembrane region is absent, supporting a soluble CD1d. In the V3-V8 variants, the antigen binding region (alpha1 and alpha2 domains) is partially defective, suggesting incomplete functional products. In contrast, the V1 and V2 transcripts bear the complete antigen binding site, resulting in functional proteins. Especially, the V2 splicing variant might function as an inhibitory soluble CD1d molecule and regulate the presentation of antigens on APC to NKT cells.

Accumulation of common T cell clonotypes in the salivary glands of patients with human T lymphotropic virus type I-associated and idiopathic Sjögren's syndrome

To clarify the pathogenesis of human T lymphotropic virus type I (HTLV-I)-associated Sjögren's syndrome (SS), the TCR Vbeta gene usage by the infiltrating lymphocytes in the target organ was examined. The Vbeta families predominantly used in the labial salivary gland (LSG) from the HTLV-I-seropositive (HTLV-I+) SS patients were more restricted than those from the HTLV-I-seronegative (idiopathic) SS patients, and were commonly Vbeta5.2, Vbeta6, and Vbeta7. The single-strand conformation polymorphism analysis revealed that T cell clonotypes with Vbeta5.2, Vbeta6, and Vbeta7 accumulate in the LSG from the HTLV-I+ and idiopathic SS patients. Among junctional sequences of the most dominant Vbeta7 transcripts, the conserved amino acid motif (QDXG: X is any amino acid) was found in six of the five HTLV-I+ SS patients and was also detected in two of the five idiopathic SS patients. Using the probes specific to the motif, the Vbeta7 transcripts with the motif were detected in the LSG from all of the seven HTLV-I+ and five of the six idiopathic SS patients, but not from eight healthy subjects. The Vbeta7 transcripts with this motif were also detected in the HTLV-I-infected T cell lines obtained from the LSG of an HTLV-I+ SS patient. The accumulation of HTLV-I-infected T cells expressing TCR with the conserved motif was thus indicated. These T cells were commonly present in patients with idiopathic SS and are strongly suggested to most likely be involved in the pathogenesis of both HTLV-I-associated and idiopathic SS.

Clonal expansion of T cells infiltrating in the airways of non-atopic asthmatics

CD4+ T cells are thought to play an important role in airway inflammation in both atopic and non-atopic asthma. However, the mechanism by which T cells are activated in non-atopic asthma, where there is no causative antigen identified, is unknown. To elucidate this issue, we analysed T cell receptor (TCR) Vbeta gene clonotypes of T cells in the bronchoalveolar lavage fluids (BALF) of non-atopic asthmatics using polymerase chain reaction single-strand conformation polymorphism (PCR-SSCP) analysis and a sequencing method. We found that the numbers of TCR Vbeta gene clonotypes of T cells in the BALF of non-atopic asthmatics were significantly increased compared with those of peripheral blood lymphocytes (PBL). We also found that there were several shared amino acid motifs in complementarity-determining region 3 (CDR3) of TCR Vbeta genes from those T cell clones in BALF of non-atopic asthmatics, whereas these shared motifs were not found in the same Vbeta family genes from PBL in the patients. Moreover, a conserved amino acid sequence was detected in two patients who shared a common HLA-DR allele. These results indicate that the infiltrating T cells in the airways of non-atopic asthmatics recognize relatively limited epitopes of antigens and are clonally expanded by antigen-driven stimulation.

Superantigens: mechanisms by which they may induce, exacerbate and control autoimmune diseases

Superantigens are polypeptide molecules produced by a broad range of infectious microorganisms which elicit excessive and toxic T-cell responses in mammalian hosts. In light of this property and the fact that autoimmune diseases are frequently the sequelae of microbial infections, it has been suggested that superantigens may be etiologic agents of autoreactive immunological responses resulting in initiation, exacerbation or relapse of autoimmune diseases. This article relates the biology of superantigens to possible mechanisms by which they may exert these activities and reviews the evidence for their roles in various human and animal models of autoimmune disease. Finally, a mechanism of active suppression by superantigen-activated CD4+ T-cells that could be exploited for therapy as well as prophylaxis of human autoimmune diseases is proposed.

Biased T cell receptor Vbeta gene expression in bronchoalveolar lavage fluid from Japanese patients with sarcoidosis

OBJECTIVE

Sarcoidosis is believed to be one of the T cell-mediated granulomatous diseases with unknown aetiology. We attempt to search for the causative T cell clones of sarcoidosis.

METHODS

We study T cell receptor beta-chain variable region (Vbeta) repertoire in peripheral blood (PB) and bronchoalveolar lavage fluid (BALF) from patients with sarcoidosis, using semi-quantitative reverse transcriptase-polymerase chain reaction method. The expression of 22 kinds of Vbeta genes is examined in 17 patients with sarcoidosis and nine normal subjects.

RESULTS

Compared with control subjects, the group with sarcoidosis exhibits significantly high expressions of the Vbeta2 (P < 0.005, Wilcoxon's test) and Vbeta6 (P = 0.005) genes in BALF. In each BALF sample, the Vbeta2 (P < 0.01, chi2 test) and Vbeta6 (P < 0.01) genes were overexpressed (> 2 SD above the mean value for each Vbeta observed in control subjects) in 11 and 10 of 17 patients with sarcoidosis, respectively. Furthermore, the amino acid sequences of Vbeta6+ complementarity determining region 3 were conserved in one of three patients. There is, however, no disposition of Vbeta gene usage in PB from patients with sarcoidosis compared with control subjects.

CONCLUSIONS

The T lymphocytes with Vbeta2 and/or Vbeta6 are associated with the pathogenesis of sarcoidosis. The possibility exists that these T lymphocytes might be capable of recognizing the restricted antigens, thereby inducing oligoclonal expansion.

A single cell analysis of TCR AV24AJ18+ DN T cells

The T-cell receptor (TCR) BV gene of human TCR AV24+ double-negative (DN) T cells, a novel subset of natural killer (NK) T cells, was investigated by single-cell sorting and single-cell polymerase chain reaction (PCR) methods. Seven of eleven TCR AV24+ DN T-cell clones utilized TCR BV8, three BV9, and one BV6. Six of seven TCR AV24/BV8+ DN T-cell clones had identical TCR beta and alpha chains, indicating that they were the same clone. All three TCR AV24/BV9+ DN T-cell clones also demonstrated the same amino acids in the CDR3 region. These findings strongly suggest that the usage of TCR beta and alpha chains on TCR AV24+ DN T cells is extremely restricted, supporting the notion that these cells recognize highly limited T-cell epitopes on antigens. All TCR AV24+ clones expressed the NKR-P1A mRNA, and so were true NK T cells. IL-2 and IL-4 mRNAs were detected in all clones, suggesting that the majority of these cells were Th0-type T cells. Six clones overexpressed Fas-ligand (Fas-L) mRNA and Fas antigen was detected on all clones at the mRNA level. In conclusion, TCR AV24+ DN T cells might recognize restricted T-cell epitopes on antigens and function as Th0-type T cells, inducer cells to Th1- or Th2-type T cells (regulatory T cells), and as Fas-L-positive cytolytic T cells.

Biased T-cell antigen receptor repertoire in Lyme arthritis

A common concern with many autoimmune diseases of unknown etiology is the extent to which tissue T-lymphocyte infiltrates, versus a nonspecific infiltrate, reflect a response to the causative agent. Lyme arthritis can histologically resemble rheumatoid synovitis, particularly the prominent infiltration by T lymphocytes. This has raised speculation about whether Lyme synovitis represents an ongoing response to the causative spirochete, Borrelia burgdorferi, or rather a self-perpetuating autoimmune reaction. In an effort to answer this question, the present study examined the repertoire of infiltrating T cells in synovial fluid from nine Lyme arthritis patients, before and after stimulation with B. burgdorferi. Using a highly sensitive and consistent quantitative PCR technique, a comparison of the T-cell antigen receptor (TCR) beta-chain variable (Vbeta) repertoires of the peripheral blood and synovial fluid showed a statistically significant increase in expression of Vbeta2 and Vbeta6 in the latter. This is remarkably similar to our previous findings in studies of rheumatoid arthritis and to other reports on psoriatic skin lesions. However, stimulation of synovial fluid T cells with B. burgdorferi provoked active proliferation but not a statistically significant increase in expression of any TCR Vbeta, including Vbeta2 and Vbeta6. Collectively, the findings suggest that the skewing of the TCR repertoire of fresh synovial fluid in Lyme arthritis may represent more a synovium-tropic or nonspecific inflammatory response, similar to that occurring in rheumatoid arthritis or psoriasis, rather than a specific Borrelia reaction.

T cell receptor clonotypes in skin lesions from patients with systemic lupus erythematosus

Systemic lupus erythematosus is an autoimmune disease characterized by the presence of autoantibodies and by lymphocytic infiltration into lesions at several sites such as skin, kidney, and other organs. Immunohistologic studies have clarified that the majority of lymphocytes in the skin are CD4+ alphabeta T cells. In the present work, to clarify the pathologic role of T cells in the skin of systemic lupus erythematosus patients, we analyzed T cell receptor (TCR) clonotypes of T cells infiltrating into skin lesions. TCR Vbeta gene transcripts from T cells from discoid lesions of the skin and peripheral blood lymphocytes of four systemic lupus erythematosus patients were amplified by reverse transcriptase polymerase chain reaction. Southern blot analysis of polymerase chain reaction product demonstrated the heterogeneous TCR Vbeta repertoire of T cells in the skin of systemic lupus erythematosus. Single-strand conformation polymorphism analysis showed several distinct bands for smears of most TCR Vbeta genes from T cells infiltrating the skin, whereas smears with few bands were found for all TCR Vbeta genes from peripheral blood lymphocytes of the same patients. The number of bands encoding each TCR Vbeta gene from the skin was significantly higher compared with peripheral blood lymphocytes. Sequencing analysis showed a Leucine-X-Glycine amino acid motif at position 96-98 in the CDR3 region at the frequency of 23-24% in skin-accumulated T cells from two patients, whereas the frequency of this motif in peripheral T cells was only 0-3%, indicating limited T cell epitopes. In conclusion, T cells infiltrating into the skin of systemic lupus erythematosus patients might recognize restricted T cell epitopes on autoantigens and trigger the autoimmune reaction in skin lesions.

Universal skew of T cell receptor (TCR) V beta usage for Crohn's disease (CrD)

It would be of clear interest and importance to identify T cell populations which correlate with the initiation of some T cell-mediated diseases; however, it is difficult to observe the initial response of T cells in these diseases because of modification due to immunosuppressive treatment. We investigated T cell receptor (TCR) V beta usage in both affected and unaffected mucosa from 16 patients with active Crohn's disease (CrD), undergoing nutritional therapy without any immunomodulatory medications. Semiquantitative reverse transcriptase-polymerase chain reaction showed increased expression of V beta 12 and 13 in the entire mucosa of CrD but not in the controls. This was confirmed by introducing a random cloning method. Such skewing was observed primarily in CD4+ lamina propria lymphocytes. DNA sequence analysis demonstrated a striking clonal expansion of V beta 12 T cells, but the dominant clones were not identical in the patients. These findings suggest the importance of superantigen as well as specific T cell response in the pathogenesis of CrD.

Association of a new allele of the TAP2 gene, TAP2*Bky2 (Val577), with susceptibility to Sjögren's syndrome

OBJECTIVE

To investigate the polymorphisms of TAP (transporters associated with antigen processing) genes among patients with primary Sjögren's syndrome (SS) in order to clarify the potential association of the polymorphisms with disease susceptibility.

METHODS

Polymorphisms of the TAP1 and TAP2 genes in 108 Japanese SS patients were determined by analyzing TAP genes using the polymerase chain reaction-single-stranded conformation polymorphism technique.

RESULTS

The allelic frequency of the TAP1 gene was not significantly different between SS patients and normal subjects. In addition to all known TAP2 alleles, a new allele (Bky2), which had a unique substitution at codon 577 (ATG-->GTG: Met-->Val), was identified in both groups. The allelic frequency of Bky2 was significantly higher in SS patients (12.0%) than in normal subjects (5.1%) (P < 0.05). Moreover, a significantly greater frequency of SS-A antibody was found among SS patients with Bky2 (18 of 23; 78%) than among those without Bky2 (33 of 85; 39%) (P = 0.001).

CONCLUSION

The mutation in TAP2 (Val577) may be involved in SS-A autoantibody production and could be a genetic factor that determines susceptibility to SS.

Analysis of T-cell receptor Vbeta repertoire in liver-infiltrating lymphocytes in chronic hepatitis C

BACKGROUND/AIMS

To examine the T-cell repertoire which is involved in the immunopathogenesis of chronic hepatitis, we analyzed the T-cell receptor Vbeta gene usage in liver-infiltrating lymphocytes by reverse transcription-polymerase chain reaction (RT-PCR) and immunohistochemical technique.

METHODS

Complementary DNA was synthesized from RNA which was extracted from 26 liver biopsy specimens and from peripheral blood lymphocytes from eight subjects, and amplified by RT-PCR. Radioactivity of each amplified product using 32P-labeled primers was measured and the percentage of each Vbeta expression was calculated.

RESULTS

The mean frequency of Vbeta5.1 (11.1%) in liver-infiltrating lymphocytes of chronic hepatitis C was highest among those of all Vbeta regions, and was significantly higher than that in both peripheral blood lymphocytes of chronic hepatitis C and liver-infiltrating lymphocytes of chronic hepatitis B. In the immunohistochemical analysis, Vbeta5.1-positive cells were mostly observed in portal areas where inflammatory reactions occurred. The sequences of the complementarity determining region (CDR)3 on T-cell receptor expressing Vbeta5.1 were examined in six patients with chronic hepatitis C. The sequences were similar to each other and all had one common amino acid (valine) irrespective of different HLA haplotype.

CONCLUSIONS

These data suggest that Vbeta5.1-positive cells are preferentially accumulated in the liver of chronic hepatitis C and are involved in the immunopathogenesis of the disease. Sequence analysis showed that Vbeta5.1-positive cells recognize a common conventional antigen and valine recognized at the same position of the CDR3 may be a key residue in determining an antigen/major histocompatibility complex contact point.

Accelerated onset of age-related autoimmune lesions in MRL/+ mice by ovariectomy

MRL/Mp +/+ (MRL/+) mice, not bearing the lpr gene, are known to have age-related autoimmune lesions in several organs such as pancreas, salivary and lacrimal glands at 30-weeks-old or more. In this study, MRL/+ mice were ovariectomized at 4-weeks-old, and their natural histories were analysed. Ovariectomy (Ovx) of MRL/+ mice led to marked acceleration of organ-specific autoimmune lesions exclusively in the salivary and lacrimal glands at 8-weeks-old or more, whereas no significant inflammatory change was observed in the pancreas. In the vast majority of inflammatory infiltrates, CD3+ CD4+ T cells were predominant in both the salivary and lacrimal glands of Ovx-MRL/+ mice. Up-regulated expression of cytokine genes including IL-1 beta, TNF-alpha, IL-2, interferon (IFN)-gamma, and IL-6 was detected in the salivary gland of Ovx-MRL/+ mice by reverse transcriptase (RT)-PCR analysis. FACS analysis of spleen cells of Ovx-mice revealed increase in I-Ak expression on B220+ cells, and autoantibody production against the salivary gland-specific antigen in sera from Ovx-MRL/+ mice, but not in control mice. These results suggest that age-related autoimmunity in the salivary and lacrimal glands were accelerated in Ovx-MRL/+ mice, and that autoreactive Th1 cells were activated associated with organ-specific autoantibody production.