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Open Access Highly Accessed Research article

Neuromelanin is an immune stimulator for dendritic cells in vitro

Uwe Oberländer1, Katrien Pletinckx1, Anja Döhler1, Nora Müller1, Manfred B Lutz1, Thomas Arzberger2, Peter Riederer3, Manfred Gerlach4, Eleni Koutsilieri1 and Carsten Scheller1*

Author Affiliations

1 University of Würzburg, Institute of Virology and Immunobiology, Würzburg, Germany

2 University of Munich, Institute of Neuropathology, Munich, Germany

3 University of Würzburg, Clinical Neurochemistry (National Parkinson Foundation Center of Excellence Research Laboratory), Clinic and Policlinic of Psychiatry, Psychosomatics and Psychotherapy, Würzburg, Germany

4 University of Würzburg, Laboratory of Clinical Neurobiology, Department of Child and Adolescent Psychiatry, Psychosomatics and Psychotherapy, Würzburg, Germany

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BMC Neuroscience 2011, 12:116  doi:10.1186/1471-2202-12-116

Published: 15 November 2011

Abstract

Background

Parkinson's disease (PD) is characterized at the cellular level by a destruction of neuromelanin (NM)-containing dopaminergic cells and a profound reduction in striatal dopamine. It has been shown recently that anti-melanin antibodies are increased in sera of Parkinson patients, suggesting that NM may act as an autoantigen. In this study we tested whether NM is being recognized by dendritic cells (DCs), the major cell type for inducing T- and B-cell responses in vivo. This recognition of NM by DCs is a prerequisite to trigger an adaptive autoimmune response directed against NM-associated structures.

Results

Murine DCs were treated with NM of substantia nigra (SN) from human subjects or with synthetic dopamine melanin (DAM). DCs effectively phagocytized NM and subsequently developed a mature phenotype (CD86high/MHCIIhigh). NM-activated DCs secreted the proinflammatory cytokines IL-6 and TNF-α. In addition, they potently triggered T cell proliferation in a mixed lymphocyte reaction, showing that DC activation was functional to induce a primary T cell response. In contrast, DAM, which lacks the protein and lipid components of NM but mimics the dopamine-melanin backbone of NM, had only very little effect on DC phenotype and function.

Conclusions

NM is recognized by DCs in vitro and triggers their maturation. If operative in vivo, this would allow the DC-mediated transport and presentation of SN antigens to the adaptive immune system, leading to autoimmmunity in susceptible individuals. Our data provide a rationale for an autoimmune-based pathomechanism of PD with NM as the initial trigger.