A peptide based on the sequence of the CDR3 of a murine anti-DNA mAb is a better modulator of experimental SLE than its single amino acid-substituted analogs

The negative regulators Foxj1 and Foxo3a are up-regulated by a peptide that inhibits systemic lupus erythematosus-associated T cell responses

A peptide (hCDR1) based on the complementarity determining region-1 of an anti-DNA antibody ameliorates systemic lupus erythematosus (SLE) in induced and spontaneous lupus models. Our objectives were to determine the effects of hCDR1 on TCR signaling and on its negative regulators, Foxj1 and Foxo3a. BALB/c mice were immunized with the SLE-inducing anti-DNA antibody, designated 16/6Id, and treated with hCDR1. hCDR1 treatment specifically inhibited IFN-gamma secretion by T cells in association with down-regulated T-bet expression and NF-kappaB activation; however, GATA-3 expression was not affected. Furthermore, TCR signaling (ZAP-70 phosphorylation) was inhibited, and the mRNA expression of the two modulators of Th1 activation, Foxj1 and Foxo3a, was significantly up-regulated. The latter were also elevated in SLE-afflicted (NZBxNZW)F1 mice that were treated with hCDR1. Addition of TGF-beta, which was elevated following treatment with hCDR1, to T cells from 16/6Id immunized mice, up-regulated Foxj1 and Foxo3a mRNA expression, similarly to hCDR1. In contrast, anti-TGF-beta antibodies added to hCDR1-treated T cells abrogated its effect. Thus, hCDR1 elevates TGF-beta, which contributes to the up-regulation of T cell Foxj1 and Foxo3a expression, leading to inhibition of NF-kappaB activation and IFN-gamma secretion, which is required for the maintenance of SLE.

T cell help is required to induce idiotypic-anti-idiotypic autoantibody network after immunization with complementary epitope 289-308aa of La/SSB autoantigen in non-autoimmune mice

Immunotherapies against autoimmune diseases have been of limited success. Preventive vaccines could be developed on the basis to abrogate unwanted immune responses to defined autodeterminants. In this study it is shown that immunization of BALB/c mice with two linear T and B cell epitopes of the human La/SSB autoantigen (spanning the regions 289-308aa and 349-364aa) and their complementary forms specified by the complementary mRNA, results in characteristic B and T cell responses. Mice immunized with the 289-308aa epitope or its complementary peptide elicited specific antibodies against both epitopes. In contrast, mice immunized with the 349-364aa epitope or its complementary peptide mounted antibody titres against the immunizing peptide only. According to these data, the 289-308aa epitope and its complementary form were capable to generate an idiotypic-anti-idiotypic response, which were cross-regulated. Peptide-specific T cell proliferation and cytokine production in vitro revealed the induction of a two-stage T helper response (Th1-->Th2 type) after immunization with either the epitope 289-308 or its complementary peptide. IgG1 was the predominant subclass after immunization with the two forms of epitopes 289-308 and 349-364, while a response of the IgG2b > IgG2a was obtained after the immunization with the complementary form of 349-364 epitope reflecting the TH2/TH1 polarization, respectively. Our data suggest that the complementary peptides of two immunodominant epitopes of human LaSSB can mimic the autoantibodies against these epitopes and establish an active idiotypic-anti-idiotypic network.

Modulation of autoreactive responses of peripheral blood lymphocytes of patients with systemic lupus erythematosus by peptides based on human and murine anti-DNA autoantibodies

Two peptides, based on the sequences of the complementarity-determining regions (CDR) 1 and 3 of a pathogenic murine monoclonal anti-DNA autoatibody that bears the 16/6 idiotype (Id), were shown to either prevent or treat an already established systemic lupus erythematosus (SLE) in two murine models of lupus. Two additional peptides based on the human monoclonal anti-DNA, 16/6 Id were synthesized. This study was undertaken in order to investigate the ability of the CDR-based peptides to immunomodulate SLE-associated responses of peripheral blood lymphocytes (PBL) of SLE patients. PBL of 24 of the 62 SLE patients tested proliferated in vitro following stimulation with the human 16/6 Id. Peptides based on the CDRs of both the human and murine anti-DNA autoantibodies inhibited efficiently and specifically the 16/6 Id-induced proliferation and IL-2 production. The latter inhibitions correlated with an up-regulated production (by 2.5-3.5-fold) of the immunosuppressive cytokine, TGF-beta. Overall, the results of our study demonstrate that the CDR-based peptides are capable of down-regulating in vitro autoreactive T cell responses of PBL of SLE patients. Thus, these peptides are potential candidates for a novel specific treatment of SLE patients.