Chaperoned amyloid proteins for immune manipulation: A-synuclein/hsp70 shifts immunity toward a modulatory phenotype

Abstract

a-Synuclein (aSyn) is a 140-residue amyloid-forming protein whose aggregation is linked to Parkinson’s disease (PD). It has also been found to play a critical role in the immune imbalance that accompanies disease progression, a characteristic that has prompted the search for an effective aSyn-based immunotherapy. In this study, we have simultaneously exploited two important features of certain heat-shock proteins (HSPs): their classical ‘‘chaperone’’ activities and their recently discovered and diverse ‘‘immunoactive’’ properties. In particular, we have explored the immune response elicited by immunization of C57BL/6 mice with an aSyn/Hsp70 protein combination in the absence of added adjuvant. Our results show differential effects for mice immunized with the aSyn/Hsp70 complex, including a restrained aSyn-specific (IgM and IgG) humoral response as well as minimized alterations in the Treg (CD4þCD25þFoxp3þ) and Teff (CD4þFoxp3 ) cell populations, as opposed to significant changes in mice immunized with aSyn and Hsp70 alone. Furthermore, in vitro-stimulated splenocytes from immunized mice showed the lowest relative response against aSyn challenge for the ‘‘aSyn/Hsp70’’ experimental group as measured by IFN-g and IL-17 secretion, and higher IL-10 levels when stimulated with LPS. Finally, serum levels of Th1-cytokine IFN-g and immunomodulatory IL-10 indicated a unique shift toward an immunomodulato-ry/immunoprotective phenotype in mice immunized with the aSyn/Hsp70 complex. Overall, we propose the use of functional ‘‘HSP-chaperoned amyloid/ aggregating proteins’’ generated with appropriate HSP-substrate protein combinations, such as the aSyn/Hsp70 complex, as a novel strategy for immune-based intervention against synucleinopathies and other amyloid or ‘‘misfolding’’ neurodegenerative disorders.