Maria Diedrichs-Möhring

ORAL TOLERANCE WITH AN HLA-PEPTIDE MIMICKING RETINAL AUTOANTIGEN AS A TREATMENT OF AUTOIMMUNE UVEITIS

Endogenous uveitis is a T cell mediated autoimmune disease leading to impairment of visual acuity. The association of different uveitis entities with HLA-class I antigens and the discovery of antigenic mimicry between a peptide of uveitis-associated HLA-class I antigens and a peptide of retinal autoantigen led to a new hypothesis for the pathogenesis of uveitis. On the basis of this mechanism an open trial of oral tolerance induction with the HLA-peptide B27PD was initiated for nine patients with long lasting, therapy-refractive uveitis. Within 6 weeks of oral peptide treatment all patients responded with a marked decrease of intraocular inflammation, which allowed a reduction of systemic corticosteroids in seven patients. One patient, who suffered from an acute relapse, responded within 2 weeks, followed by an increase of visual acuity. In addition, two patients discontinued azathioprine immediately prior to oral tolerance induction without the occurrence of relapses. Visual acuity remained unchanged or increased in 14 of 16 eyes. One patient did not finish oral peptide treatment. None of these patients experienced any adverse events. It was concluded that the oral application of highly tolerogenic peptides might be a potent approach for the treatment of autoimmune diseases.

Autoimmune uveitis induced by molecular mimicry of peptides from rotavirus, bovine casein and retinal S-antigen

Antigenic mimicry of infectious agents and autoantigens is a proposed pathomechanism for autoimmune diseases. Here, we describe antigenic mimicry of a peptide from rotavirus, a nutritional protein from bovine milk (αs2‐casein) and a peptide thereof as well as a highly pathogenic peptide from retinal S‐antigen (PDSAg), a major autoantigen in experimental autoimmune uveitis in Lewis rats. Immunization of rats with the peptides and the casein protein induced uveitis, an intraocular inflammation leading to decreased vision and even blindness. The peptides elicited cross‐reactive T cell responses and uveitis in rats and were also recognized by lymphocytes and sera from uveitis patients. Oral tolerization with PDSAg, but not with rotavirus‐ and casein‐derived peptides or caseinprotein, prevented PDSAg‐induced uveitis in rats. Cofeeding of casein with cholera toxin induced uveitis in rats, suggesting that breaking oral tolerance to casein during gastrointestinal infections might also be able to initiate uveitis in humans.

Uveitis in a Patient Treated with Bacille-Calmette-Guérin Possible Antigenic Mimicry of Mycobacterial and Retinal Antigens

PURPOSE To investigate the cellular immune response in uveitis developing after intravesical Bacille-Calmette-Guérin (BCG) applications. DESIGN Experimental study. PARTICIPANTS A 72-year-old HLA-B27-negative patient with bilateral granulomatous anterior uveitis that developed during the third cycle of intravesical BCG applications she was receiving for treatment of bladder carcinoma. METHODS The patients peripheral T cell reactivity to ocular autoantigens was compared with the response to purified protein derivative (PPD) from Mycobacterium tuberculosis. T-cell proliferation and cytokine and chemokine secretion were measured in vitro. MAIN OUTCOME MEASURES Anterior uveitis was treated successfully with topical corticosteroids and cycloplegics. RESULTS The following were demonstrated: proliferation to PPD, interphotoreceptor retinoid-binding protein (IRBP), and IRBP-peptide R16, as well as secretion of proinflammatory cytokines in response to PPD, retinal soluble antigen (S-Ag), IRBP, cellular retinal-binding protein (CRALBP), and some S-Ag and IRBP peptides. CONCLUSIONS These data indicate the generation of a polyclonal autoimmune reaction elicited by BCG. Amino acid sequence alignments revealed homologies between proteins from M. tuberculosis, BCG, and retinal antigens, suggesting antigenic mimicry as a potential cause of uveitis in this patient.

The effect of the CC chemokine receptor antagonist Met-RANTES on experimental autoimmune uveitis and oral tolerance

Lymphocyte trafficking is controlled in part by the actions of chemokines. In rat experimental autoimmune uveitis (EAU) we observed differential therapeutic effects of Met-RANTES, a CCR1/CCR5 receptor antagonist, depending on the retinal antigen peptides inducing the disease and the time of application during the afferent or efferent immune response. CCR1 and/or CCR5 blockade may have inhibitory effects on different phases of the autoimmune response, depending on the antigen specificity of T cells in EAU. In contrast, Met-RANTES enhanced therapeutic oral tolerance independently of orally applied antigen.

Induction of arthritis and uveitis in Lewis rats by antigenic mimicry of peptides from HLA‐B27 and cytokeratin

Ankylosing spondylitis (AS) is highly associated with HLA‐B27. We have previously shown that peripheral blood lymphocytes from AS patients respond to stimulation with a peptide from the sequence of HLA‐B27. Here we report on molecular mimicry of peptides from HLA‐B27 and cytokeratin, the latter being specifically expressed in synovial membranes and eyes, the main targets of the autoaggressive immune response in AS patients. Immunization of rats with these peptides induced an inflammatory response in joints, spine and eyes, resembling the symptoms in AS. Furthermore, both HLA‐B27‐ and cytokeratin‐derived peptides, are effective oral tolerogens: feeding these peptides ameliorated arthritis and uveitis induced with the cytokeratin peptide. Our model might elucidate the role of peptides from the sequence of HLA‐B27 as an antigen of the immune response in AS, introducing a new aspect of antigenic mimicry between HLA‐B27 and tissue‐specific antigens. We propose this as a mechanism directing a systemic autoimmune response to specific target organs by antigenic mimicry of T cell epitopes.

Effector T cells driving monophasic vs. relapsing/remitting experimental autoimmune uveitis show unique pathway signatures

Autoimmune diseases often show a relapsing-remitting course. Here we describe characteristics of the autoreactive T cell response in the Lewis rat model of experimental autoimmune uveitis (EAU), a model for the clinical heterogeneity seen in human uveitis. Depending on the autoantigen used, the experimental disease course can be either monophasic or relapsing/remitting. This appears to be dictated by subtle differences in the T cell effector phenotype elicited. Using transcriptomic profiling and pathway analysis, the molecular basis for the monophasic vs. relapsing/remitting effector T cell phenotype was investigated. CD4+ T cell lines specific for peptide R14 derived from interphotoreceptor retinoid-binding protein (IRBP), which mediate the relapsing disease, were compared to the monophasic disease-inducing lines responding to retinal S-antigen peptide PDSAg. Expression profiles from T cell lines representing each specificity were analyzed using Affymetrix microarrays. Differential gene expression was confirmed and extended by quantitative PCR and verified on the protein level. A set of genes was uniquely upregulated in the R14-specific T cells. Gene ontology analysis demonstrated that these genes were linked to regulatory pathways associated with antigen presentation, lymphocyte activation, regulation of apoptosis and WNT/Hedgehog signaling. R14-specific T cells were further demonstrated to have prolonged survival in vivo, and a Th1-dominated cytokine profile, while the PDSAg-specific T cells lines were more Th17-prone. Our findings suggest that the nature of specific antigens leads to subtle programming of the effector phenotype underlying recurrent inflammation.

Antigen-dependent monophasic or recurrent autoimmune uveitis in rats.

Experimental autoimmune uveitis (EAU) in the Lewis rat has been regarded as an acute and monophasic disease. Uveitis can be induced by immunization with retinal soluble antigen (S-Ag), interphotoreceptor retinoid-binding protein (IRBP) or their peptide derivatives (PDSAg from S-Ag and R14 from IRBP) in CFA as well as by the transfer of activated, antigen-specific T cells. Previously, it has been shown that adoptively transferred, IRBP peptide-specific, but not S-Ag peptide-specific T cells can induce relapsing uveitis in rats. We observed spontaneous recurrences of intra-ocular inflammation even after immunization with R14 in CFA and were able to experimentally re-induce uveitis in rats previously immunized with autoantigen peptide in CFA. The efficiency of re-induction was dependent on the mode of pre-treatment [immunization or adoptive transfer (AT)] as well as on the antigen itself. Primary PDSAg-responses prevented subsequent re-induction of disease much more efficiently than primary R14-mediated EAU. In our model, the suppressive effect of CFA did not play a key role in preventing re-induction or spontaneous relapses. Furthermore, epitope spreading could not be demonstrated as a cause for recurrent inflammation. These data suggest that autoimmune responses with different antigen specificities could underlie similar clinical pictures while being differently regulated, which may help explain the variations in the disease courses in patients and the differential responses to therapeutic modalities.

Rat Models of Autoimmune Uveitis

Experimental autoimmune uveitis (EAU) in Lewis rats is a well-established model for human uveitis. During the last years we used this model to demonstrate extraocular induction of uveitis by antigenic mimicry of environmental antigens with retinal autoantigen and investigated the migration and intraocular reactivation of autoreactive green fluorescent protein (GFP)+ T cells. We could also elaborate several differences between EAU induced with S-antigen peptide PDSAg or R14, a peptide derived from interphotoreceptor retinoid-binding protein, suggesting two differently regulated diseases in the same rat strain. R14-mediated EAU in Lewis rats has been shown to relapse, thus we have a new model to test therapeutic approaches in an ongoing immune response instead of just preventing disease. Finally, we show antigenic mimicry of PDSAg and an HLA-B peptide for oral tolerance induction. After the successful first therapeutic trial this approach will now proceed with international multicenter clinical trials.

Long-Term Follow-Up of Oral Tolerance Induction with HLA-Peptide B27PD in Patients with Uveitis

Abstract: Oral tolerance induction with peptide B27PD had an ameliorating effect in uveitis patients, which was also observed in the five‐year follow‐up period. Repeated treatments with peptide B27PD were also effective. Side effects did not occur in this patient group, not even in patients receiving peptide for up to 42 weeks.

Gamma‐Delta T Cells as Orally Induced Suppressor Cells in Rats: In Vitro Characterization

Abstract: Gamma‐delta T cells from orally tolerized rats adoptively transfer suppression of experimental autoimmune uveitis. In vivo and in vitro these regulatory cells specifically recognize retinal autoantigen peptide PDSAg and its mimotope B27PD, but not other mimicry peptides. Proliferation of γ/δ T cells was MHC class II and CD8 dependent.