Jean Roudier

Epstein-Barr virus in autoimmune diseases.

Autoimmune diseases such as systemic lupus erythematosus (SLE), rheumatoid arthritis (RA), and primary Sjögrens syndrome (pSS) are complex disorders with a genetic background and the involvement of environmental factors, including viruses. The Epstein-Barr virus (EBV) is a plausible candidate for playing a role in the pathophysiology of these diseases. Both SLE and RA are characterized by high titers of anti-EBV antibodies and impaired T-cell responses to EBV antigens. Compared with normal subjects, elevated EBV load in peripheral blood has been observed in SLE and RA. EBV DNA or RNA has been evidenced in target organs of RA (synovium) or pSS (salivary glands). Finally, molecular mimicry has been demonstrated between EBV proteins and self antigens in these three conditions. In addition, SLE, RA, and pSS are associated with an increased risk of lymphoma with a potential role for EBV. The influence of new and emergent treatments of these autoimmune diseases (biological therapies) on EBV load and the course of latent EBV infection requires further studies.

Epitopes of human fibrin recognized by the rheumatoid arthritis-specific autoantibodies to citrullinated proteins

Formation of the epitopes recognized by the rheumatoid arthritis (RA)‐specific autoantibodies to citrullinated proteins (ACPA) on filaggrin and on the α‐ and β‐chains of fibrin, their synovial target, requires conversion of their arginyl residues into citrullyl residues, but is also affected by their amino‐acyl environment. Using competition with five citrullinated filaggrin‐derived peptides bearing major ACPA epitopes, we confirmed the close cross‐reactivity between filaggrin and citrullinated fibrin. To identify the sequential epitopes recognized on fibrin by ACPA, 71 citrullinated 15‐mer peptides derived from all the sites of the α‐ and β‐chains of fibrin harboring arginyl residues were tested by ELISA using ACPA‐positive RA sera exhibiting different reactivity profiles to the five filaggrin peptides. We identified 18 fibrin‐derived peptides bearing ACPA epitopes. Regarding the ability of fibrinogen arginyl residues to be citrullinated in vitro, 11 of the peptides likely correspond to in vivo targeted epitopes. Two out of them bear major epitopes and are located in the central globular domain of the protein. In the synovial tissue, fibrin citrullination and ACPA binding could impair fibrin degradation by plasmin. The immunological conflict between ACPA and fibrin could therefore sustain synovial inflammation not only via pro‐inflammatory effector mechanisms but also via impairment of fibrinolysis.

Transfer of the shared epitope through microchimerism in women with rheumatoid arthritis.

OBJECTIVE Rheumatoid arthritis (RA) is an autoimmune disease that affects mostly women and is associated with HLA-DRB1 genes having in common a shared epitope sequence. In parallel, cells and/or DNA originating from pregnancy (microchimerism) persist for decades and could contribute to autoimmunity. The aim of this study was to examine whether microchimerism may be a source of the shared epitope among women with RA. METHODS Women with RA and healthy women who lacked RA-associated genes such as HLA-DRB1*01 (n=33 and n=46, respectively) and/or HLA-DRB1*04 (n=48 and n=64, respectively), were tested for DRB1*01 or DRB1*04 microchimerism by HLA-specific quantitative polymerase chain reaction assays. As controls, alleles not associated with RA (DQB1*02 and DRB1*15/16) were also analyzed. RESULTS Compared with healthy women, women (42% with RA had a higher frequency and higher levels of DRB1*04 microchimerism versus 8%; P=0.00002) as well as DRB1*01 microchimerism (30% versus 4%; P=0.0015). Moreover, no difference in microchimerism was observed for alleles not associated with RA. CONCLUSION Women with RA had microchimerism with RA-associated HLA alleles, but not with non-RA-associated HLA alleles, more often and at higher levels compared with healthy women. These observations are the first to indicate that microchimerism can contribute to the risk of an autoimmune disease by providing HLA susceptibility alleles.

Influence of shared epitope–negative HLA–DRB1 alleles on genetic susceptibility to rheumatoid arthritis

OBJECTIVE Most patients with rheumatoid arthritis (RA) express the shared epitope (SE). It is not known whether SE-negative HLA-DRB1 alleles influence the development of RA. This study examined the influence of SE-negative HLA-DR alleles (DRB1*X) on the development of RA in 3 different French populations. METHODS HLA-DRB1 alleles were defined by polymerase chain reaction with sequence-specific oligonucleotide hybridization or sequence-specific primers. SE-negative alleles were classified according to the electric charge of their P4 pocket. HLA-DRB1 alleles *0103, *0402, *07, *08, *11 (except *1107), *12, and *13 have a neutral or negative P4 charge and are called DRB1*XP4n. HLA-DRB1*03, *0403, *0406, *0407, *0901, *1107, *14, *15, and *16 have a positive P4 charge and are called DRB1*XP4p. RESULTS Among the SE-negative subjects, DRB1 genotypes with 1 or 2 DRB1*XP4n alleles were significantly overrepresented in the control subjects compared with the RA patients, whereas DRB1*XP4p/XP4p genotypes were equally represented in the patients and controls. In single-dose SE-positive subjects, SE/XP4n genotypes were equally represented in the patients and controls. However, SE/XP4p genotypes were significantly overrepresented in the RA patients. CONCLUSION The DRB1*X allele polymorphism influences susceptibility to RA. Alleles that have a neutral or negative electric charge in their P4 pocket (DRB1*XP4n), such as DRB1*0103, *0402, *07, *08, *11 (except *1107), *12, and *13, protect against RA. Alleles that have a positive electric charge in their P4 pocket (DRB1*XP4p), such as DRB1*03, *0403, *0406, *0407, *0901, *1107, *14, *15, and *16, have no influence on the predisposition to RA.

Safety of TNF-blocking agents in rheumatic patients with serology suggesting past hepatitis B state: results from a cohort of 21 patients

IntroductionReactivation of hepatitis B virus (HBV) infection in patients with past infection has been described in 5% to 10% of individuals undergoing immunosuppressive therapies. No data are available to date on the outcome of patients treated by tumour necrosis factor-alpha (TNFα) inhibitors for chronic arthritis with a serological pattern of past HBV infection. The aim of our study was to monitor HBV markers in HBV surface antigen (HBsAg)-negative/anti-HBcAb-positive patients treated with a TNFα inhibitor for inflammatory arthritides.MethodsTwenty-one HBsAg-negative/anti-HBcAb-positive patients were included. HBV serological patterns were compared with those determined before starting TNFα inhibitors. Serum HBV DNA testing by polymerase chain reaction was additionally performed. Spearman correlation analysis was used and P < 0.05 was chosen as the significance threshold.ResultsBefore starting therapy, mean anti-HBsAb titre was 725 IU/L, no patient had an anti-HBsAb titre <10 IU/L, and 18 patients had an anti-HBsAb >100 IU/L. At a mean time of 27.2 months following therapy introduction, mean anti-HBsAb titre was 675 IU/L and anti-HBsAb titre remained >100 IU/L in 17 patients. There was a strong correlation between the first and second anti-HBsAb titres (r = 0.98, P = 0.013). Moreover, no patient had an anti-HBsAb titre below 10 IU/L or HBV reactivation (HBsAg seroreversion or positive HBV DNA detection). However, the anti-HBsAb titre decreased by more than 30% in 6 patients. The mean anti-HBsAb titre at baseline was significantly lower (P = 0.006) and the mean duration of anti-TNFα therapy, although non-significant (P = 0.09), was longer in these six patients as compared to patients without a decrease in anti-HBsAb titre.ConclusionsAnti-TNFα treatments are likely to be safe in patients with past hepatitis B serological pattern. However, the significant decrease of anti-HBsAb titre observed in a proportion of patients deserves HBV virological follow-up in these patients, especially in those with a low anti-HBsAb titre at baseline.

New autoantigens in rheumatoid arthritis (RA): screening 8268 protein arrays with sera from patients with RA

Objective: To identify new IgG autoantibodies in sera from patients with rheumatoid arthritis (RA). Methods: We tested serum samples from 19 patients with RA with given human leukocyte antigen (HLA)-DR genotypes, from 7 patients with spondylarthropathy, 2 patients with lupus, 4 patients with systemic sclerosis and 10 healthy individuals on 8268 human protein arrays. Results: We identified four antigens (peptidyl arginine deiminase 4 (PAD4), protein kinase Cβ1 (PKCβ1), phosphatylinositol 4 phosphate 5 kinase type II γ (PIP4K2C) and v raf murine sarcoma viral oncogene homologue B1 catalytic domain (BRAF)) that were recognised almost uniquely by sera from patients with RA on protein arrays. Using purified proteins, we confirmed that PAD4 and BRAF are recognised almost uniquely by patients with RA. Conclusion: We identified PAD4 and BRAF as RA specific autoantigens.

Paracrine in vivo inhibitory effects of hepatitis B virus X protein (HBx) on liver cell proliferation: An alternative mechanism of HBx-related pathogenesis

The role of the hepatitis B virus X protein (HBx) in the pathogenesis of hepatitis B virus (HBV) infection remains unclear. HBx exhibits pleiotropic biological effects, whose in vivo relevance is a matter for debate. In the present report, we have used a combination of HBx-expressing transgenic mice and liver cell transplantation to investigate the in vivo impact of HBx expression on liver cell proliferation and viability in a regenerative context. We show that moderate HBx expression inhibits liver regeneration after partial hepatectomy in HBx-expressing transgenic mice. We also demonstrate that the transplantation of HBx-expressing liver cells, isolated from HBx transgenic mice, is sufficient to inhibit overall recipient liver regeneration after partial hepatectomy. Moreover, the injection of serum samples drawn from HBx-expressing transgenic mice mimicked the inhibitory effect of HBx on liver regeneration. Finally, the incubation of primary rat hepatocytes with the supernatant of HBx-expressing liver cells inhibits cellular DNA synthesis. Taken together, our results demonstrate a paracrine inhibitory effect of HBx on liver cell proliferation and lead us to propose HBV as one of the few viruses implicated in human cancer which act, at least in part, through paracrine biological pathways.

Association of MHC and rheumatoid arthritis: Association of RA with HLA-DR4 - the role of repertoire selection

Most patients with rheumatoid arthritis (RA) express HLA-DR4, HLA-DR1 or HLA-DR10. These alleles share a common amino acid motif in their third hypervariable regions: the shared epitope. In normals and patients with RA, HLA-DR genes exert a major influence on the CD4 αβ T-cell repertoire, as shown by studies of AV and BV gene usage and by BV BJ gene usage by peripheral blood CD4 αβ T-cells. However, the rheumatoid T-cell repertoire is not entirely under HLA-DR influence, as demonstrated by discrepancies in VB JB gene usage between identical twins discordant for RA and by contraction of the CD4 αβ T-cell repertoire in RA patients. Shared epitope positive HLA-DR alleles may shape the T-cell repertoire by presenting self peptides to CD4 T cells in the thymus. Peptides processed from HLA-DR molecules and encompassing the shared epitope may also be presented by HLA-DQ and select CD4 αβ T cells in the thymus. Thus, shared epitope-positive alleles impose a frame on the T-cell repertoire. This predisposing frame is further modified (by unknown factors) to obtain the contracted rheumatoid repertoire.

A FUNCTION FOR THE QKRAA AMINO ACID MOTIF : MEDIATING BINDING OF DNAJ TO DNAK : IMPLICATIONS FOR THE ASSOCIATION OF RHEUMATOID ARTHRITIS WITH HLA-DR4

The amino acid motif QKRAA, when expressed on HLA-DRB1, carries susceptibility to develop rheumatoid arthritis. This motif is the basis of strong B and T cell epitopes. Furthermore, it is highly overrepresented in protein databases, suggesting that it carries a function of its own. To identify this function, we used QKRAA peptide affinity columns to screen total protein extracts from Escherichia coli. We found that DnaK, the E. coli 70-kD heat shock protein, binds QKRAA. Of interest, DnaK has a natural ligand, DnaJ, that contains a QKRAA motif. We found that QKRAA-containing peptides inhibit the binding of DnaK to DnaJ. Furthermore, rabbit antibody to the QKRAA motif can inhibit binding of DnaJ to DnaK. These data suggest that QKRAA mediates the binding of E. coli chaperone DnaJ to its partner chaperone DnaK.

MOLECULAR MIMICRY REFLECTED THROUGH DATABASE SCREENING : SERENDIPITY OR SURVIVAL STRATEGY ?

Protein databases have been growing fast, and there has been considerable improvement in the computer software used to explore them. Subsequently, database screening commonly yields evidence of molecular mimicry between unrelated proteins. Here, Chantal Roudier and colleagues analyse the statistical significance of such sequence identities.