OBJECTIVES

Interleukin (IL)-33 is a novel member of pro-inflammatory cytokine IL-1 family, which plays an important role in the immune response. IL-33 was proved to involve in many inflammatory and allergic diseases, thus the inhibition of this cytokine may be a promising treatment for these diseases. Arms of the study were to generate mouse soluble IL-33 receptor fused with human IgG1 Fc domain (msIL33R-Fc) expressed by Pichia pastoris yeast and to characterize the IL-33 inhibitory activity of this protein.

METHODS

Clone of P. pastoris expressing msIL33R-Fc was established and the recombinant protein was harvested from culture supernatant by protein A sepharose beads. Recombinant msIL33R-Fc was analysed by SDS-PAGE and Western blotting and activity of the protein was investigated using the immunoprecipitation and the bio-assay on EL-4 cells.

KEY FINDINGS

P. pastoris-derived msIL33R-Fc was expressed as a glyco-protein and perhaps in dimeric form. The glycosylation of protein expressed by P. pastoris yeast was more intensive and more heterogeneous compared with the counterpart protein expressed from HEK293 cells. Similar to HEK293-derived protein, msIL33R-Fc from P. pastoris was able to capture IL-33 and to interfere with the interaction between IL-33 and IL-33R in in-vitro condition. In IL-33-stimulated EL-4 cell bio-assay, P. pastoris-derived msIL33R-Fc suppressed IL-33 activity similarly as HEK293-derived msIL33R-Fc did.

CONCLUSIONS

P. pastoris yeast can express and secrete bio-functional fusion protein sIL33R-Fc IgG1 and this expression system may be beneficial in future studies on the fusion protein.