In-vitro effects of Mycobacterium bovis BCG-lysate and its derived heat shock proteins on cytokines secretion by blood mononuclear cells of rheumatoid arthritis patients in comparison with healthy controls

BackgroundSeveral studies have shown that heat shock protein (HSP)-reactive T cells have an immunoregulatory phenotype indicating that HSPs are able to trigger immunoregulatory pathways, which can suppress immune responses that occur in human inflammatory diseases, such as rheumatoid arthritis (RA). Mycobacterium bovis strain Bacillus Calmette-Guérin (BCG) is rich of HSPs which could be good resources of these regulatory proteins for modulation of immune response.PurposesTo study the effects of BCG-lysate and BCG-derived HSPs on secretion of T regulatory cytokines by PBMCs of RA patients in comparison with healthy controls.MethodsBCG was heat killed and sonicated to have BCG-lysate. BCG-derived HSP65/HSP70 were detected by immunoblotting and purified by preparative SDS-PAGE. PBMCs of 18 RA patients/16 controls collected by Ficoll-paque were stimulated with BCG-lysate/BCG-derived HSP-65/HSP-70. Supernatant of stimulated PBMCs was aspirated for measuring TGF-β, IL-10, IL-4 and IFN-γ with sandwich ELISA.ResultsBCG-lysate augmented the amounts of all the mentioned cytokines as dose dependent significantly. The level of TGF-β in controls was higher than patients (P < 0.05). HSP65 and HSP70 increased TGF-β, IL-10 as dose dependent significantly. HSP65, but not HSP70, increased IL-4. HSP65 did not increase IFN-γ but HSP70 augmented IFN-γ significantly. BCG-lysate increased IFN-γ and IL-4 in RA patients more than healthy controls (P < 0.05).ConclusionAlthough BCG is able to provoke T helper 1 cell mediated immunity, its HSP proteins are able to trigger T regulatory cytokines. Healthy controls were under stronger immune regulations.