B cells as effectors and regulators of sex-biased arthritis

B cells have been implicated both with pathogenic as well as protective capabilities in induction and regulation of autoimmune diseases. Rheumatoid arthritis (RA) is an autoimmune disease that occurs more often in women than men. A significant role of B cells as antibody producing and antigen-presenting cells has been demonstrated in RA. Predisposition to RA is associated with the presence of certain HLA class II alleles that share sequences with DRB1*0401. To determine the role of HLA genes and B cells in vivo, we have generated transgenic mice carrying HLA genes, DRB1*0401 and DQ8, known to be associated with susceptibility to RA. Humanized mice can be induced to develop arthritis that mimics human disease in clinical, histopathological and sex bias. Effect of hormones on immune cells and their function has been described in humans and mice and has been suggested to be the major reason for female bias of autoimmune diseases. An immune response to an antigen requires presentation by HLA molecules thus suggesting a critical role of MHC in combination with sex hormones in susceptibility to develop rheumatoid arthritis. Based on our observations, we hypothesize that modulation of B cells by estrogen, presentation of modified antigens by DR4 and production of antigen-specific B cell modulating cytokines leads to autoreactivity in females. These data suggest that considering patient's sex may be crucial in selecting the optimal treatment strategy. Humanized mice expressing RA susceptible and resistant haplotype provide a means to investigate mechanism sex-bias of arthritis and future strategies for therapy.     

To B or not to B: role of B cells in pathogenesis of arthritis in HLA transgenic mice

Population studies have shown that amongst all the genetic factors linked with autoimmune disease development, MHC class II genes are the most significant. Experimental autoimmune arthritis resembling human rheumatoid arthritis (RA) can be induced in susceptible strains of mice following immunization with type II collagen (CIA). We generated transgenic mice lacking endogenous class II molecules and expressing various HLA genes including RA-associated, HLA-DRB1*0401 and HLA-DQ8, and RA-resistant, DRB1*0402, genes. The HLA molecules in these mice are expressed on the cell surface and can positively select CD4+ T cells expressing various Vβ T cell receptors. Endogenous class II invariant chain is required for proper functioning of the class II transgene. Arthritis development in transgenic mice is CD4+ and B cells dependent. Studies in humanized mice showed that B cells are required as antigen presenting cells in addition to antibody producing cells for the development of CIA. The transgenic mice expressing *0401 and *0401/DQ8 genes developed sex-biased arthritis with predominantly females being affected, similar to that of human RA. Further, the transgenic mice produced autoantibodies like rheumatoid factor and anti-cyclic antibodies. Antigen presentation by B cells leads to a sex-specific immune response in DRB1*0401 mice suggesting a role of B cells and HLA-DR in rendering susceptibility to develop arthritis in females.     

DRB1*0402 may influence arthritis by promoting naive CD4+ T‐cell differentiation in to regulatory T cells

HLA‐DRB1*0401 expression in humans has been associated with a predisposition to developing rheumatoid arthritis (RA) and collagen‐induced arthritis (CIA), while HLA‐DRB1*0402 is not associated with susceptibility. Here, we determined if mice transgenic (Tg) for human *0401 have a CD4⁺ T‐cell repertoire that predetermines proinflammatory cytokine production. The data show that both *0401 and *0402 Tg mice can produce TH1/TH17 cytokines, although the kinetics of response may be different. However, in the context of antigen‐specific responses in a CIA model, *0402 Tg mice generate a TH2 response that may explain their resistance to developing arthritis. In addition, a significant subset of naïve CD4⁺ T cells from *0402 Tg mice can be activated in polarizing conditions to differentiate into Treg cells that produce IFN‐γ. *0401 Tg mice harbor memory CD4⁺ T cells that differentiate into IL‐17⁺ cells in various polarizing conditions. Our data suggest that *0401 Tg mice generate a strong immune response to lipopolysaccharide and may be efficient in clearing infection, and may *0401 have been evolutionarily selected for this ability. Autoimmunity, such as RA, could likely be a bystander effect of the cytokine storm that, along with the presence of low Treg‐cell numbers in *0401 Tg mice, causes immune dysregulation.     

HLA DMA and DMB show no association with rheumatoid arthritis in US Caucasians

HLA DM is a heterodimeric molecule functioning in normal antigen presentation; it is encoded by adjacent HLA-region loci, HLA DMA and DMB, located between DP and DQ. Some previous studies have suggested that HLA susceptibility to rheumatoid arthritis (RA) is associated with certain DMA and DMB alleles. Our aim was to examine whether this association is also present in US Caucasians. We studied 288 US Caucasian subjects with rheumatoid arthritis and 263 US Caucasian control subjects. DMA and DMB typing was achieved by PCR amplification followed by sequence-specific oligonucleotide hybridization and by PCR–restriction fragment length polymorphism. There was no frequency difference for DMA alleles or DMB alleles between RA and control subjects, indicating no association. Neither was a difference apparent when data were analysed in subgroups based on shared-epitope DRB1, on the rheumatoid factor test, on radiographic changes of RA, or on sex. DRB1-DQB1-DMB analyses for linkage disequilibrium showed that the DRB1*0401-DQB1*0301 haplotype had the DMB*0103 allele more often than DMB*0101 (estimated haplotype frequencies 0.08 and 0.039 in RA, respectively). In contrast, the DRB1*0401-DQB1*0302 haplotype usually had the DMB*0101 allele (haplotype frequency 0.084 compared to 0.01 for DMB*0103). Thus, neither HLA DMA nor DMB was associated with RA in this population, and not all shared-epitope-bearing haplotypes had the same DMB allele distribution.     

HLA DMA and DMB show no association with rheumatoid arthritis in US Caucasians.

HLA DM is a heterodimeric molecule functioning in normal antigen presentation; it is encoded by adjacent HLA-region loci, HLA DMA and DMB, located between DP and DQ. Some previous studies have suggested that HLA susceptibility to rheumatoid arthritis (RA) is associated with certain DMA and DMB alleles. Our aim was to examine whether this association is also present in US Caucasians. We studied 288 US Caucasian subjects with rheumatoid arthritis and 263 US Caucasian control subjects. DMA and DMB typing was achieved by PCR amplification followed by sequence-specific oligonucleotide hybridization and by PCR-restriction fragment length polymorphism. There was no frequency difference for DMA alleles or DMB alleles between RA and control subjects, indicating no association. Neither was a difference apparent when data were analysed in subgroups based on shared-epitope DRB1, on the rheumatoid factor test, on radiographic changes of RA, or on sex. DRB1-DQB1-DMB analyses for linkage disequilibrium showed that the DRB1*0401-DQB1*0301 haplotype had the DMB*0103 allele more often than DMB*0101 (estimated haplotype frequencies 0.08 and 0.039 in RA, respectively). In contrast, the DRB1 *0401-DQB1 *0302 haplotype usually had the DMB*0101 allele (haplotype frequency 0.084 compared to 0.01 for DMB*0103). Thus, neither HLA DMA nor DMB was associated with RA in this population, and not all shared-epitope-bearing haplotypes had the same DMB allele distribution.     

Genetic susceptibilities for immune expression and liver cell injury in autoimmune hepatitis

Summary: Genetic susceptibility to type 1 autoimmune hepatitis in white northern Europeans is related to female sex, HLA alleles encoding the six amino acid sequence LLEQKR at positions 67–72 of the DRB1 polypeptide, and CTLA-4 gene polymorphism. The principal HLA alleles associated with type 1 autoimmune hepatitis in Britain and North America are DRB1*0301 and DRB1*0401. In this model of susceptibility, lysine at position 71 of the expressed DR molecule is the critical amino acid. In Japan, Argentina and Mexico, susceptibility is linked to DRB1*0405 and DRB1*0404. These two alleles encode arginine at position 71 rather than lysine, but they share the motif LLEQ-R with DRB1*0401 and DRB1*0301. Thus, K or R at position 71 in the context of LLEQ-R may be critical for susceptibility. This "shared motif" or "epitope" may optimize T‐cell recognition of autoantigen, and other alleles that encode lysine at DRb71 may also affect susceptibility and outcome, possibly by increasing the density of lysine or arginine 71 molecules on the surface of antigen-presenting cells. Since the DRB1*0301 allele is part of the extended ancestral 8.1 haplotype, it carries with it additional risk factors for autoimmunity, including TNFA*2 and C4A*Q0. Type 1 autoimmune hepatitis is a polygenic disorder and other yet undefined polymorphic genes may be non-specific immunoregulators. These additional MHC encoded genes and other non-MHC encoded genes may be important determinants of disease susceptibility and severity in type 1 autoimmune hepatitis.     

HLA class II association with rheumatoid arthritis: facts and interpretations

We have reviewed the literature on the association of HLA class II with rheumatoid arthritis (RA). Strong linkage disequilibrium among DQB1, DQA1 and DRB1 alleles makes it difficult to evaluate the individual contribution of each locus. Nonetheless, there is a strong case for the role of DQB1*03 and *04 combined with DQA1*03 in susceptibility to severe RA while DQB1*0501 combined with DQA1*0101 and *0104 weakly predisposes to a mild form of RA. However, it is also clear that DRB1*0401 has a particular role in predisposition to the most severe form of the disease while other DRB1 alleles might provide protection. We would like to propose that in RA, as in type I diabetes, both DQ and DR loci contribute to predisposition to the disease.     

Selection of Self-reactive Peptides Within Human Aggrecan by use of a HLA-DRB1*0401 Peptide Binding Motif

The pathogenesis of joint destruction in rheumatoid arthritis remains ill-defined. Joint destruction is thought to be the result of tissue damage mediated by T cells. The mere presence of articular cartilage appears responsible for sustaining chronic synovitis and thereby forwards a role for cartilage-responsive T cells in RA. Taking advantage of the positive DRB1*0401 association with RA susceptibility, we reasoned that T-cell recognition of autoantigens in RA would be restricted by DRB1*0401-encoded molecules. A DR4 (B1*0401) peptide binding motif was used for the identification of putative T-cell epitopes within human aggrecan, a candidate autoantigen. Thirteen peptides were synthesized and tested for binding DRB1*0401 or 0404-encoded molecules. Selected binders were tested for induction of pro-liferative responses in peripheral blood mononuclear cells from donors carrying the DR4 or DR1 specificity. Both healthy and RA donors responded to human aggrecan-derived peptides, thereby identifying these sequences as T-cell epitopes. Interestingly, responses to aggrecan-derived epitopes were significantly decreased in RA patients compared to controls. This was not due to an overall hyporesponsiveness of RA patients since responses to a recall antigen or mitogen did not differ from controls. The data suggest that in RA, aggrecan-specific T cells may exist in a different stage of activation or may have left the periphery to home to the joint.     

DR4Dw4/DR53 molecules contain a peptide from the autoantigen calreticulin

Abstract: Rheumatoid arthritis (RA) occurs more frequently in HLA-DR4⁺ individuals than in those who do not express this MHC class II molecule. Although the role of this genetic factor in the immunopathology of this autoimmune disease is unclear, the association of RA with HLA-DR4 may indicate that DR4 molecules present autoantigen(s) to T cells. Here we report the analysis of naturally processed peptides, eluted from a mixture of HLA-DR4Dw4 (DRB1*0401) and DR53 (DRB4* 0101) molecules isolated from an RA patient-derived EBV-transformed B cell line. Several (size variants of) self-peptides originating from the autologous molecules HLA-A2, HLA-Cw9, HLA-B62, HLA-DR4Dw4 and HLA-DR53, were identified. We also found a sequence that has no homology to any protein in the SwissProt protein sequence databank, and a peptide identical to an internal fragment of the autoantigen calreticulin. The association of the identified peptides with cells expressing HLA-DR4Dw4/DR53 was confirmed by peptide binding analysis. In agreement with previously described peptide binding motifs for DR4Dw4, most peptides contained an aromatic residue (Phe, Tyr, Trp) at relative position i and a small hydroxyl-containing residue (Ser, Thr) at i+5. Our findings indicate that in RA patient-derived EBV-transformed B cells DR4Dw4/ DR53 molecules present a peptide from the autoantigen calreticulin. Interestingly, autoantibodies against calreticulin have been found in various rheumatic diseases, including rheumatoid arthritis. Thus, the analysis of HLA class II-bound peptides can lead to the identification of putative T helper epitopes, which might be involved in the immunopathology of autoimmune diseases.     

Analysis of synovial T cells reactive with autologous HLA-DR molecules expressed by murine cells

Rheumatoid arthritis (RA) is believed to be an autoimmune disease with participation of autoreactive T cells of still unknown specificities. In this study we concentrate on the analysis of synovial T cells of RA patients (typed DRB1^*0401), which react with autologous peripheral blood mononuclear cells - without the addition of any nominal antigen - in a proliferation assay or by the secretion of lymphokines (IL-2, IL-3). Such T cells were grown as lines or clones by polyclonal stimulation and further analysed for their reactivity with human B cell lines and murine cells expressing HLA-DR molecules. We used L cells or P388D1 macrophage-like cells transfected with DRA and DRB1^*0401 (TP0401) or related natural and artificially constructed variants thereof. TP cells are described in detail in Daubenberger et al, Int. Immunol., vol. 8, 1996. Most autoreactive lines were CD4⁺ (38/44). Many of them reacted with TP0401 cells. The characterizations of restriction patterns and of T cell receptors showed that all of up to 10 TP0401-reactive T cells clones derived from one RA patient were different. We propose that a variety of common intracellular proteins may provide peptides recognized by these autoreactive T cells.     

Cross-Reactivity between the Rheumatoid Arthritis-Associated Motif EQKRAA and Structurally Related Sequences Found in Proteus mirabilis

Cross-reactivity or molecular mimicry may be one of the underlying mechanisms involved in the etiopathogenesis of rheumatoid arthritis (RA). Antiserum against the RA susceptibility sequence EQKRAA was shown to bind to a similar peptide ESRRAL present in the hemolysin of the gram-negative bacterium Proteus mirabilis, and an anti-ESRRAL serum reacted with EQKRAA. There was no reactivity with either anti-EQKRAA or anti-ESRRAL to a peptide containing the EDERAA sequence which is present in HLA-DRB1*0402, an allele not associated with RA. Furthermore, the EQKRAA and ESRRAL antisera bound to a mouse fibroblast transfectant cell line (Dap.3) expressing HLA-DRB1*0401 but not to DRB1*0402. However, peptide sequences structurally related to the RA susceptibility motif LEIEKDFTTYGEE (P. mirabilis urease), VEIRAEGNRFTY (collagen type II) and DELSPETSPYVKE (collagen type XI) did not bind significantly to cell lines expressing HLA-DRB1*0401 or HLA-DRB1*0402 compared to the control peptide YASGASGASGAS. It is suggested here that molecular mimicry between HLA alleles associated with RA and P. mirabilis may be relevant in the etiopathogenesis of the disease.     

Genetic basis for rheumatoid arthritis

Rheumatoid arthritis (RA) is a common disabling disorder of unknown etiology. In the past 2 decades, a number of studies have examined the genetic basis for RA. One major focus of these studies has been to identify genes within the MHC class II (HLA-DR) chromosomal region, which confer susceptibility/resistance to RA. A strong association between HLA-DR4 and adult seropositive RA has been observed in majority of populations. In addition, there is evidence of a positive association between HLA-DR1 and RA. On the basis of prevalence of DR1 (B1*0101) and of subtypes of DR4 (B1*0401, B1*0404 and B1*0405), it has been suggested that a five amino acid sequence motif (QKRAA/QRRAA) from position 70 to 74 in the third hypervariable region of DRbeta1 molecules is associated with susceptibility to RA. These associations between RA and HLA-DR genes are however incomplete in that about 1/4 of patients do not carry RA-susceptibility DRB1 epitope. Since MHC class III region contains genes that are involved in immune response, we have recently examined the role of a number of microsatellites (D6S273, Bat2, TNFa) and HSP70 promoter region alleles in susceptibility to RA. The results demonstrate that two regions in MHC, class II (DRbeta1) and class III (D6S273, HSP70, Bat2, TNFa) more completely define the risk for development of RA.     

DRB1 alleles in polymyalgia rheumatica and rheumatoid arthritis in southern France

To investigate the association of HLA‐DRB1 alleles with polymyalgia rheumatica (PMR) and rheumatoid arthritis (RA), 55 patients with PMR without giant cell arteritis, 203 patients with RA and 230 controls, all from the European population of Marseille, were HLA‐DRB1 genotyped by PCR‐SSO. HLA‐DRB1*01 was significantly increased in both the PMR and RA groups compared to controls (35% versus 17%, P_c < 0.05, and 41% versus 17%, P_c < 0.001, respectively). HLA‐DRB1*04 was significantly increased in the RA group compared to controls (48% versus 23%, P_c < 0.001) but not in the PMR group. HLA‐DRB1*04 subtype frequencies were significantly different between PMR patients and RA patients. Shared epitope‐positive HLA‐DRB1*04 alleles (DRB1*0401, 0404, 0405, 0408) were significantly overrepresented in RA patients compared to PMR patients and shared epitope‐negative HLA‐DRB1*04 alleles were overrepresented in PMR patients compared to RA patients. In conclusion, in the Mediterranean population studied, HLA‐DRB1*01 is associated with RA and PMR whereas HLA‐DRB1*04 is associated with RA only.     

Motif analysis of HLA class II molecules that determine the HPV associated risk of cervical carcinogenesis

In previous studies, the HLA class II haplotype HLA DRB1*0401-DQB1*0301 was shown to correlate with susceptibility to HPV infection, CIN and cervical cancer while DRB1*0101-DQB1*0501 indicated protection. The present study was designed to identify naturally processed peptide sequences bound to the susceptibility and protective HLA DR-DQ molecules, and use this for T-helper epitope prediction from HPV 16. The HLA class II molecules were obtained by immuno-affinity purification of Epstein-Barr virus B lymphoblastoid cell lines (BCL) homozygous for HLA DQA1*0301-DQB1*0301 and HLA DQA1*0101-DQB1*0501. Peptide pools eluted from the HLA molecules were sequenced by Edman degradation. On the basis of the peptide sequence data obtained, the E6, E7, L1 and L2 proteins of HPV 16 were examined to identify sequences which are likely to bind to HLA DQB1*0301 and DQB1*0501. In addition, motif prediction as well as the binding affinity of predicted peptide motifs for HLA DRB1*0401 and DRB1*0101, the DR alleles associated with susceptibility and protection respectively, was accomplished using published data and a prediction algorithm for the naturally processed peptide sequences bound to these molecules. The HLA DQB1*0501 peptide ligand sequence showed that proline gives an outstanding signal at position 2, Asn/Arg at P1, aliphatic/aromatic amino acids in the central portion, a hydrophobic cluster at P5 with a small contribution by small polar residues and another cluster of aromatic residues towards the C-terminus. The HLA DQB1*0301 sequence also showed that proline gives an outstanding signal at position 2, Thr/Arg at P1, aliphatic/aromatic amino acids in the central portion and an aliphatic cluster with a small contribution by small polar residues at P5. There were no differences in the number of HPV peptides that were predicted as being capable of binding to HLA DQB1*0301 and HLA DQB1*0501, but more HPV peptide motifs were predicted to bind with high affinity to HLA DRB1*0101 than DRB1*0401. The results suggest that HPV 16 peptide epitopes bind with higher affinity to the protective than to susceptible HLA DR-DQ molecules which may lead to a more effective immune response.     

Different gene loci within the HLA-DR and TNF regions are independently associated with susceptibility and severity in Spanish rheumatoid arthritis patients

The aim of this study was to investigate whether polymorphisms in the tumor necrosis factor (TNF) and HLA-DRB1 gene regions are independently associated with rheumatoid arthritis (RA) in a population from Lugo region of northwestern Spain. RA patients (n=179) attending hospital outpatient clinics in Lugo, northwestern Spain and matched controls (n=145) were recruited. RA susceptibility in this population was predominantly associated with DRB1*0401, while erosive disease was associated with HLA-DRB1*0101 and DRB1*04. The increase in DRB1*04 was accounted for by an increase in DRB1*0404 and *0405 but not *0401 frequencies. In contrast, *0401 frequency was significantly increased in seropositive patients. The rheumatoid arthritis shared epitope (SE) was associated with increased risk for seropositive and erosive disease and this appeared to operate in a dose-dependent manner. Logistic regression analyses revealed that the TNF microsatellite markers TNFc1 and b3 were associated with RA independently of DRB1*04 and the SE. Carriage of a TNF c1 allele provided an increased risk of RA in SE-negative and SE-heterozygous individuals. TNFc1 and TNFb3 were not associated with erosive or seropositive disease. In contrast, TNF a2 was significantly associated with erosive disease which was independent of DRB1*04 and the SE. Further studies will be needed to establish why (TNFc1) polymorphism seemingly associated with low TNFalpha production, is a risk factor for RA.     

Autoimmunity versus tolerance: analysis using HLAtransgenic mice

On the basis of our extensive studies on collagen induced arthritis in HLA class II transgenic mice, we proposed a hypothesis to explain role of shared epitope in rheumatoid arthritis (RA) association. According to our hypothesis, complementation between both DQ and DR molecules is required for susceptibility or protection from disease. While certain DQ alleles predispose individuals to RA, DRB1 molecule can modulate disease by shaping T-cell repertoire in the thymus by providing self-peptides and presented by DQ molecules. Using Aβo.DQ8 transgenic mice, we tested ability of peptides derived from HV3 of DR molecules, implicated in RA positively or negatively, to activate T cells. While the peptides derived from RA susceptible DR molecule were poor binders and poor in activating T cells, the peptides derived from RA resistant DR molecules were high affinity binders and efficient T-cell activators. Our experiments suggest that high affinity DR peptides could induce tolerance to autoimmunity while the low affinity peptides could be permissive to autoimmunity. Using peptide from DRB1*0402 molecule, known to be associated with resistance to RA, prior to induction of collagen induced arthritis prevents the onset of disease. Thus, self-peptides derived from HLA molecules could potentially generate tolerance or autoimmunity depending on their binding affinity with HLA molecules.     

HLA shared epitope and ACPA: Just a marker or an active player?

Autoantibody production is genetically controlled and anti-citrullinated protein/peptide antibodies (ACPA) are not an exception to the rule. ACPA are highly specific markers of rheumatoid arthritis (RA) and are also associated with a more severe disease course. The production of ACPA is almost invariably observed in HLA-shared epitope (SE) positive patients. The DRB1 alleles sharing SE are those conferring susceptibility to RA. SE alleles behave like immune response genes, controlling both the specificity and the amount of ACPA produced. These data suggest a role of SE in the presentation of citrullinated antigens. The ability of SE alleles to bind selectively to citrullinated sequences as compared to the native counterparts has been demonstrated in the case of peptides derived from several joint associated proteins (vimentin, fibrinogen and cartilage intermediate-layer protein). On the contrary, EBV-derived citrullinated peptides do not display a biologically relevant binding to SE alleles even if the immune response to VCPs is under the genetic control of these alleles (namely *0401 and *0404). Thus, the presentation of citrullinated epitopes does not represent the only molecular mechanisms underlying the HLA-DRB1 effect on ACPA production.     

Autoimmunity versus tolerance: analysis using transgenic mice

On the basis of our extensive studies on collagen induced arthritis in HLA class II transgenic mice, we proposed a hypothesis to explain role of shared epitope in rheumatoid arthritis (RA) association. According to our hypothesis, complementation between both DQ and DR molecules is required for susceptibility or protection from disease. While certain DQ alleles predispose individuals to RA, DRB1 molecule can modulate disease by shaping T-cell repertoire in the thymus by providing self-peptides and presented by DQ molecules. Using A beta o.DQ8 transgenic mice, we tested ability of peptides derived from HV3 of DR molecules, implicated in RA positively or negatively, to activate T cells. While the peptides derived from RA susceptible DR molecule were poor binders and poor in activating T cells, the peptides derived from RA resistant DR molecules were high affinity binders and efficient T-cell activators. Our experiments suggest that high affinity DR peptides could induce tolerance to autoimmunity while the low affinity peptides could be permissive to autoimmunity. Using peptide from DRB1*0402 molecule, known to be associated with resistance to RA, prior to induction of collagen induced arthritis prevents the onset of disease. Thus, self-peptides derived from HLA molecules could potentially generate tolerance or autoimmunity depending on their binding affinity with HLA molecules.     

Functional categorization of HLA-DRB1 alleles in rheumatoid arthritis: the protective effect

Because of past recombination event, human leukocyte antigen (HLA) alleles that are not closely related in overall sequence may come to resemble each other in areas coding for peptide binding regions (PBR) of HLA molecules. Peptide binding is likely to be important for the role of HLA molecules in autoimmune disease. As a result, it has been suggested that a strategy of searching for HLA disease associations that groups alleles in functional categories based on PBR motifs may be more successful than conventional strategies based on studying different alleles. Using such functional categorization, we examined the possibility of discriminating subcategories of HLA-DRB1 alleles associated with rheumatoid arthritis (RA) in a Southern French population. HLA-DRB1 genotyping was performed by polymerase chain reaction with sequence-specific oligonucleotide hybridization or sequence-specific primers. HLA-DRB1 alleles were classified according to a functional categorization that defined seven similar subregion structures or restrictive supertype patterns (RSPs) within pocket 4 of HLA-DR peptide binding groove as the molecular basis for grouping these alleles. HLA-DRB1* RSPs "A," "De," "Q," "Dr," "E," " R," and "a" association with susceptibility or resistance to disease was then studied in 200 RA patients versus 200 controls. DRB1* RSP "A" containing the shared epitope alleles (DRB1*0101, *0102, *0401, *0404, *0405, *0408, *1001, *1402; odds ratio [OR] = 4.35; pc < 0.001) had a predisposing effect, with double-dose effect as expected, OR 6.68 (pc < 0.001). Among the six remaining RSPs, two had significantly protective effect: DRB1* RSP "De" (DRB1*0103, *0402, *1102, *1103, *1301, *1302, *1304; OR = 0.33; p(c) < 0.001), and DRB1* RSP "Q" (DRB1*0701; OR = 0.40; pc < 0.001). One had non-significantly protective effect: DRB1* RSP "Dr" (DRB1*08, *1101, *1104, *1106, *12, *1303, *16; OR = 0.68; p < 0.05, pc = not significant [NS]). Three had neutral effect: HLA-DRB1* RSPs "E" (DRB1*0403, *0407, *0901, *1401; OR = 0.71; p = NS), " R" (DRB1*0301, *0302; OR = 0.76; p = NS), and "a" (DRB1*1501, *1502; OR = 0.94; p = NS). The functional categorization allowed us to discriminate among the HLA-DRB1 alleles those that confer a predisposing effect, a neutral effect, and a protective effect in RA.     

An HLA-DRB1*0402 derived peptide (HV3 65-79) prevents collagen-induced arthritis in HLA-DQ8 transgenic mice.

On the basis of our studies with HLA class II transgenic mice, we had proposed that complementation of HLA-DQ and HLA-DR alleles may determine both disease susceptibility and severity in rheumatoid arthritis (RA). According to our model, certain HLA-DQ alleles, such as HLA-DQ8, predispose individuals to RA, while a self-peptide derived from the third hypervariable region (HV3 65-79) of HLA-DR alleles, such as DRB 1*0402, can protect from disease if presented by the DQ molecule. To test this hypothesis, we examined the immunomodulatory effects of the DRB1*0402 derived peptide (HV3 65-79) on collagen-induced arthritis (CIA) in HLA-DQ8 mice. Co-immunization of the DRB 1*0402 peptide significantly reduced the severity of arthritis (mean score = 1.5+/-0.6 vs 5.2+/-1.4 in controls), whereas multiple doses of the peptide reduced the incidence of disease (3.5% vs 35-60% in controls). Subsequent analysis revealed that the DRB1*0402 peptide mediated protection may be due to the generation of a subset of regulatory cells, which down-regulate collagen-specific pro-inflammatory responses. These results provide additional insights towards understanding the role of MHC class II molecules in RA predisposition.