Nicotiana benthamiana and Arabidopsis thaliana heat shock protein 90 induce mouse B cells proliferation.

CORIGLIANO, MARIANA G; LAGUÍA BECHER, MELINA; ANGEL, SERGIO O; CLEMENTE, MARINA

Guadalajara

Congreso; VII Encuentro Latinoamericano y del Caribe sobre Biotecnología Agropecuaria; 2010

Fundación REDBIO Internacional

The ability of heat shock proteins (Hsps) to chaperone peptides, interact with antigen-presenting cells and stimulate antigen-presenting cells, makes them a unique starting point for the generation of immune responses. Under this hypothesis that the immunological properties of Hsp90 observed in other organisms are also present in their plant orthologues, we evaluated the ability of the recombinant A. thaliana and N. benthamiana Hsp90s (AtHsp90 and NbHsp90, respectively) to induce proliferation of naive BALB/c mice splenocytes in vitro. AtHsp81.2 and NbHsp90.2 sequences were cloned, over-expressed and purified from E.coli cells. Once their identity was confirmed by mass spectrometry analysis, the stimulation ability of plant rHsp90 on spleen cells from BALB/c mice was examined. As control, Leishmania infantum Hsp83 (LiHsp83) and Toxoplama gondii Hsp28 (TgHsp28) was tested. Plant rHsp90 induced prominent proliferative responses of spleen cells as also observed for LiHsp83, whereas TgHsp28 did not induce this proliferative response. Thus, this proliferative response of spleen cells was specifically induced by plant rHsp90 and LiHsp83. Furthermore, the proliferative capacity of LPS and ConA was evaluated. As expected, both LPS and ConA were able to induce proliferation responses. However, the proliferation capacity of LPS was abolished by the polymyxin-B treatment suggesting that the proliferative capacity of the plant rHsp90s preparations must be attributed to the proteins and not to LPS contamination. Flow cytometry analysis of immune-stimulated cells revealed that stimulation of splenocytes with plant rHsp90s promoted a marked proliferation of the CD19 B cells, while CD3 T cells did not respond. Thus, the results suggested that the main spleen cell population proliferating in response to plant rHsp90s is constituted by B lymphocytes. This work provides the first evidence that spleen cell proliferation can be stimulated by non-pathogen-derived Hsp90.