Selective Modulation of CD4+ T Cells from Lupus Patients by a Promiscuous, Protective Peptide Analog

Abstract

A peptide encompassing residues 131–151 of the spliceosomal U1-70K protein and its analog phosphorylated at Ser140 were synthesized as potential candidates for the treatment of patients with lupus. Studies in the MRL/lpr and (NZB × NZW)F1 lupus models have demonstrated that these sequences contain a CD4+ T cell epitope but administration of the phosphorylated peptide only ameliorates the clinical manifestations of treated MRL/lpr mice. Binding assays with soluble HLA class II molecules and molecular modeling experiments indicate that both peptides behave as promiscuous epitopes and bind to a large panel of human DR molecules. In contrast to normal T cells and T cells from non-lupus autoimmune patients, we found that PBMCs from 40% of lupus patients selected randomly and CFSE-labeled CD4+ T cells proliferate in response to peptide 131–151. Remarkably, however, we observed that phosphorylation of Ser140 prevents CD4+ T cells proliferation but not secretion of regulatory cytokines, suggesting a striking immunomodulatory effect of phosphorylated analog on lupus CD4+ T cells that was unique to patients. The analog might act as an activator of regulatory T cells or as a partial agonist of TCR.

Apoptosis-linked changes in the phosphorylation status and subcellular localization of the spliceosomal autoantigen U1-70K

“…16,17,20,21 In addition, we have previously reported the importance of the phosphorylated Ser140 residue in modulating the autoimmune response. 18,19 Therefore, we propose that the Materials and Methods Antibodies. Antibodies against peptides encompassing residues 131-151, the residues 131-151 with a phosphorylated Ser140 and 183-202 (containing no serine residues) of the U1-70K protein were raised in rabbits.…”

“…16,17 We previously found that a peptide encompassing residues 131-151 in the RRM of the U1-70K protein and phosphorylated at Ser140 (peptide P140) was recognized by CD4 þ T cells from mice and patients with lupus and protected young lupus mice against the disease in contrast to the nonphosphorylated peptide, which was not tolerogenic. 18,19 In addition, for unknown reasons, the apoptotic form of the protein is a preferred target of autoantibodies. 20,21 Consequently, we tried to clarify the pathway leading to an immunogenic protein by evaluating the changes in the phosphorylation status of the U1-70K protein during apoptotic conditions with a particular focus on Ser140.…”

Nucleic acid-associated autoantigens: Pathogenic involvement and therapeutic potential

“…A T-cell epitope located in the RNP1 motif present within the RRM of the U1-70K protein has been characterized using T cells from patients with lupus and MRL-lpr and (NZB Â NZW)F1 mice [168,186,187]. T cells from MCTD patients recognize five distinct epitopes on U1-70K that are also located within the RNA-binding domain [188].…”

Low-Dose Peptide Tolerance Therapy of Lupus Generates Plasmacytoid Dendritic Cells That Cause Expansion of Autoantigen-Specific Regulatory T Cells and Contraction of Inflammatory Th17 Cells

“…These unaltered, native peptide epitopes halt progression of lupus nephritis upon tolerization in high-dose soluble form and importantly for human therapy, the peptides are also effective in delaying/preventing lupus nephritis in subnanomolar doses (ϳ0.37 nM or 1 g), administered s.c. to lupus-prone SNF 1 mice (2,3,15). This dose is 300-to 1000-fold less than peptides from other nucleoproteins or unrelated peptides from Ig V regions (CDR) that are being tried as therapeutic agents (4,5,16,17).…”