Immunotherapy of rheumatoid arthritis (RA) using oral-dosed native chicken or bovine
type II collagen (nCII) to induce specific immune tolerance is an attractive strategy.
However, the majority of clinical trials of oral tolerance in human diseases including
RA in recent years have been disappointing. Here, we describe a novel recombinant
peptide rcCTE1-2 which contains only two tolerogenic epitopes (CTE1 and CTE2) of chicken
type II collagen (cCII). These are the critical T-cell determinants for suppression
of RA that were first developed and used to compare its suppressive effects with ncCII
on the collagen-induced arthritis (CIA) model. The rcCTE1-2 was produced using the
prokaryotic pET expression system and purified by Ni-NTA His affinity chromatography.
Strikingly, our results showed clearly that rcCTE1-2 was as efficacious as ncCII at
the dose of 50 microg/kg/d. This dose significantly reduced footpad swelling, arthritic
incidence and scores, and deferred the onset of disease. Furthermore, rcCTE1-2 of
50 microg/kg/d could lower the level of anti-nCII antibody in the serum of CIA animals,
decrease Th1-cytokine INF-gamma level, and increase Th3-cytokine TGF-beta(1) produced
level by spleen cells from CIA mice after in vivo stimulation with ncCII. Importantly,
rcCTE1-2 was even more potent than native cCII, which was used in the clinic for RA.
Equally importantly, the findings that the major T-cell determinants of cCII that
are also recognized by H-2(b) MHC-restricted T cells have not previously been reported.
Taken together, these results suggest that we have successfully developed a novel
recombinant peptide rcCTE1-2 that can induce a potent tolerogenic response in CIA.