Lupus Nephritis (LN), one of the most severe and late-stage manifestation of Systemic
Lupus Erythematosus (SLE), is associated with high morbidity and mortality of SLE
patients. In LN, the damage of resident renal cells including mesangial cells and deposition
of immune complex in glomerular basement membrane with severe kidney inflammation
are generally found. Anti-double-stranded DNA (anti-dsDNA) antibodies are associated to
the pathogenesis of LN. A subset of anti-DNA antibodies are pathogenic and have cellpenetrating ability. Spermatid Nuclear Transition Protein 1 (TNP1) is one of the potential
auto-antigen of LN. I studied the effects of TNP1-synthetic peptide on characteristics of
cell-penetrating (2C10, G2-6) and non-cell-penetrating (G5-8) anti-DNA monoclonal
antibodies in mouse kidney mesangial (SV40 MES-13) cells, kidney epithelial cells
(Renca) and macrophage cells (Raw 264.7). I found that antibodies, 2C10 and G5-8 bound
to the TNP1-peptide with higher affinities, but G2-6 with lower affinity by performing the
direct-binding and competitive ELISA. It was found that TNP1-peptide induced the
cellular changes in the antibody treated cells by performing the flow cytometry,
immunofluorescence microscopy and quantitative RT-PCR; the cell-penetration efficiency
was reduced by 2C10-TNP1-peptide or G2-6-TNP1-peptide complex as compared to
antibody alone. Interestingly, the levels of pro-inflammatory cytokine (interleukin-6 and
interferon-α) enhanced by 2C10 or G2-6 or G5-8 in SV40 MES-13 cells were decreased
when treated with antibody-TNP1-peptide complex, whereas those were increased in
Renca and Raw 264.7 cells. My results indicate that TNP1-peptide has ability to reduce the
cell-penetration efficiency of anti-DNA antibody, and acts in differently among various
cell lines in relation to pro-inflammatory cytokine expression which could be of potential
therapeutic targets in LN. These results suggest, TNP1-peptide has a potential therapeutic
significance in reducing the inflammatory condition by blocking the cell-penetrating and
pathogenic activity of anti-DNA antibodies.
