Susceptibility to rheumatoid arthritis (RA) may be due to the presence of shared functional epitopes common to the HLA-DR (3 chains of several RA-associated haplotypes. We have obtained direct evidence for this hypothesis by using the polymerase chain reaction and sequencing the DRBI and DQBI genes from RA patients. A highly conserved epitope present on DR .8 chains of DR4 and DR1 haplotypes was found in 83% of 149 patients with classical or definite RA but was found in only 46% of 100 control individuals (P < 0.0001). Two Dw subtypes of DR4 (Dw4 and Dw14) were associated with disease susceptibility but two other subtypes (DwlO and Dw13) were not. Sequence differences between these subtypes implicate those residues around the putative antigen binding site of the DR (B molecule in the pathogenesis of RA. These data provide a basis for understanding host susceptibility to RA at a molecular level.The polymorphism in class II gene products from the major histocompatibility complex (MHC) is known to be localized in the N-terminal domain of these molecules (1), particularly in discrete regions termed allelic hypervariable regions (AHVRs) (2, 3). These influence peptide binding and T-cell recognition by their position on the a-helices and P-strands that form the sides and floor of the putative antigen binding site (4). AHVRs are often shared between several different class II alleles, suggesting that the polymorphism in these molecules has been in part generated by recombination events that have shuffled these AHVRs between haplotypes (3, 5).Identification of the exact locus within the MHC responsible for particular disease susceptibilities has become more feasible now that sequences are available for most ofthe class II alleles (3, 6). Attribution of susceptibility to a particular locus relies heavily on comparison of sequences between haplotypes that confer susceptibility or protection (7,8). Haplotypes associated with rheumatoid arthritis (RA) share a common third AHVR located between residues 67 and 74 of the ,3 chain of the HLA-DR protein (DRB); this finding has given rise to the shared-epitope hypothesis for susceptibility to this disease (9)(10)(11). This hypothesis holds that the third AHVR of certain DR4 subtypes (Dw4 and. Dw14) MATERIALS AND METHODSPatients and Controls. We recruited 149 Caucasian patients with classical or definite RA (12). All had an erosive arthropathy and had received disease-modifying drugs, but extraarticular features were not a prerequisite for inclusion. IgM rheumatoid factor was assayed (rheumatoid arthritis particle agglutination test; Fujirebio Inc., Tokyo) and considered positive in a titer of >1:40 but negative only if absent on three occasions during active disease. One hundred healthy unrelated Caucasian individuals served as controls for the DR genotyping studies. The frequencies of DR4 subtypes in 178 DR4-positive patients were compared with those in 185 healthy DR4-positive blood donors.Amplification of HLA Class H Alleles. DRB and DQBI alleles were amplified from...

Fibrosis, microvascular fibroproliferative alterations, and autoantibody production are the main features of systemic sclerosis (SSc), and all of them can be explained by cytokine production by activated T cells. However, little is known about the role of T cells in the pathogenesis of SSc, and there is no information on the Ag(s) that elicits such activation. To determine whether T cells infiltrating the skin biopsies of patients with SSc are oligoclonal, β-chain TCR transcripts from T cells infiltrating the skin of five patients with SSc of recent onset were amplified by either Vβ-specific PCR or nonpalindromic adaptor PCR. The resulting PCR products were subsequently cloned and sequenced. High proportions of identical β-chain TCR transcripts ranging from 43 to 90% of those sequenced were found in five patients, strongly suggesting the presence of oligoclonal T cells in these infiltrates. A dominant T cell clone was found to be clonally expanded in skin biopsies obtained from a single patient with SSc at three different times (0, 8, and 13 mo earlier) and from three different skin regions. β-chain TCR transcripts from PBMC from normal donors (methodological control) were unique when compared with each other, typical for polyclonal populations of T cells. The finding of oligoclonal T cells infiltrating the skin of patients with SSc suggests that these T cells have undergone proliferation in situ in the skin and clonal expansion in response to as yet unidentified Ag(s). These results suggest that T cells are involved in the pathogenesis of the disease.

No abstract

Helicobacter pylori (H. pylori) is the main cause of chronic gastritis and a major risk factor for gastric cancer. This pathogen has also been considered a potential trigger of gastric autoimmunity, and in particular of autoimmune gastritis. However, a considerable number of reports have attempted to link H. pylori infection with the development of extra-gastrointestinal autoimmune disorders, affecting organs not immediately relevant to the stomach. This review discusses the current evidence in support or against the role of H. pylori as a potential trigger of autoimmune rheumatic and skin diseases, as well as organ specific autoimmune diseases. We discuss epidemiological, serological, immunological and experimental evidence associating this pathogen with autoimmune diseases. Although over one hundred autoimmune diseases have been investigated in relation to H. pylori, we discuss a select number of papers with a larger literature base, and include Sjögrens syndrome, rheumatoid arthritis, systemic lupus erythematosus, vasculitides, autoimmune skin conditions, idiopathic thrombocytopenic purpura, autoimmune thyroid disease, multiple sclerosis, neuromyelitis optica and autoimmune liver diseases. Specific mention is given to those studies reporting an association of anti-H. pylori antibodies with the presence of autoimmune disease-specific clinical parameters, as well as those failing to find such associations. We also provide helpful hints for future research.

Systemic sclerosis is characterized by extensive fibrosis, microvascular stenosis and autoantibody production. All three characteristics can be accounted for by activation of cells of the immune system. Activation of T cells is antigen-driven and occurs early in the course of the disease, before microscopic evidence of fibrosis. Activated T cells are predominantly of the type 2 T-helper lineage, and produce interleukin-4 and interleukin-13, which induce fibrosis. B cells are also activated early in the course of the disease and, through the production of autoantibodies, cause fibroblasts to adopt a profibrotic phenotype. Macrophages in perivascular infiltrates are activated and produce CC-chemokine ligand 2, transforming growth factor beta and platelet derived growth factor, all of which promote fibrosis and fibroproliferation. These new insights have direct impact on the treatment of patients with systemic sclerosis; therapies that target T cells, B cells and their harmful mediators are a logical approach, and preliminary data are promising.

Objective Breg cells, a regulatory cell subset that produces interleukin‐10 (IL‐10), play a significant role in suppressing autoimmune responses and preventing autoimmunity. This study was undertaken to examine the number and function of Breg cells in patients with systemic sclerosis (SSc), a disease with many autoantibodies. Methods Forty‐five patients with SSc (12 with early SSc, 33 with established disease including 16 with SSc‐associated pulmonary fibrosis [PF]), 12 healthy control subjects, and 10 patients with rheumatoid arthritis (RA)–associated PF were studied. The phenotypes of immature/transitional Breg cells (CD19+CD24highCD38high) and memory Breg cells (CD19+CD27+CD24high) were evaluated by flow cytometry. The function of Breg cells was assessed by measuring the production of IL‐10 after B cell activation. In addition, activation of p38 MAPK and STAT‐3 was measured following stimulation of the cells with B cell receptor (BCR) and Toll‐like receptor 9 (TLR‐9). Results Percentages of memory Breg cells were decreased in patients with early SSc (mean ± SEM 1.85 ± 0.38%), those with established SSc (1.6 ± 0.88%), those with SSc‐associated PF (1.52 ± 0.17%), and those with RA‐associated PF (1.58 ± 0.26%), compared to healthy controls (6.3 ± 0.49%; each P < 0.001). Percentages of transitional Breg cells were also decreased. Expression of IL‐10 by Breg cells after stimulation with TLR‐9 was impaired in patients with SSc, particularly those with SSc‐associated PF. Activation of STAT‐3 and p38 MAPK was impaired in naive and memory B cells from patients with SSc after stimulation with BCR and TLR‐9. Expression of the stimulatory CD19 receptor was increased in B cells and also increased, to a lesser extent, in Breg cells from patients with SSc compared to healthy controls. Percentages of memory B cells were decreased in patients with SSc, particularly in those with SSc‐associated PF. Conclusion This is the first study to demonstrate that Breg cells are phenotypically and functionally impaired in patients with SSc. Furthermore, in SSc, B cells exhibit impaired p38 MAPK and STAT‐3 activation upon stimulation with BCR and TLR‐9. The findings of decreased numbers of Breg cells along with increased expression of CD19 support the idea of B cell autoaggression acting as an immunopathogenic mediator in SSc.

No abstract

Anti-Topo I, anti-CENP, and anti-RNA pol III are the most prevalent autoAbs in SSc. Anti-Topo I and anti-NOR90 abs are associated with ILD and/or PAH.