Inducible heat shock protein 70 promotes myelin autoantigen presentation by the HLA class II.
In this study, we investigated the role of the inducible form of heat shock protein 70 (hsp70) in the presentation of the major putative autoantigen in multiple sclerosis, myelin basic protein (MBP), in the context of appropriate MHC class II. By coimmunoprecipitation, we found that MBP is associated with hsp70 in APC in an ATP/ADP-dependent manner. Additionally, using confocal microscopy, hsp70 was detected in the endocytic pathway of APC, where it colocalized with MBP and HLA-DR. The immunodominant epitopes of MBP 85-99 and 80-99 were shown to bind selectively and specifically to hsp70 by surface plasmon resonance. The functional significance of MBP interaction with hsp70 was demonstrated by the detection of enhanced responses of an MBP-specific T cell hybridoma to MBP and MBP 80-99 with increasing levels of hsp70 and reduced responses when hsp70 expression was diminished within APC-expressing DRA*0101, DRB1*1501 (DR1501). However, when MBP 85-99 was used as the stimulus, T cell hybridoma responses were not enhanced by hsp70 overexpression within APC, suggesting that hsp70 contributes to Ag processing rather than Ag presentation. The importance of a direct association between MBP and hsp70 in the presentation pathways was demonstrated by enhanced efficacy of MBP presentation by APC transfected with a plasmid vector encoding a fusion hsp70-MBP protein. This is the first report on the involvement of self-inducible hsp70 in MHC class II-dependent autoantigen processing by APC. It implicates that aberrant self hsp expression may lead to the enhancement/modulation of autoimmune responses.
Mycko
Marcin P
MP
Department of Neurology, Laboratory of Neuroimmunology, Medical University of Lodz, Kopcinskiego Str. 22, 90-153 Lodz, Poland.
Cwiklinska
Hanna
H
Szymanski
Jacek
J
Szymanska
Bozena
B
Kudla
Grzegorz
G
Kilianek
Lukasz
L
Odyniec
Artur
A
Brosnan
Celia F
CF
Selmaj
Krzysztof W
KW
D000595:Amino Acid Sequence; D000818:Animals; D017951:Antigen Presentation / Q000235:genetics / Q000276:immunology*; D000938:Antigen-Presenting Cells / Q000276:immunology / Q000378:metabolism; D001324:Autoantigens / Q000378:metabolism*; D002999:Clone Cells; D015536:Down-Regulation / Q000276:immunology; D011992:Endosomes / Q000378:metabolism; D006684:HLA-DR Antigens / Q000276:immunology / Q000378:metabolism*; D059805:HLA-DR alpha-Chains; D059811:HLA-DRB1 Chains; D018840:HSP70 Heat-Shock Proteins / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D006801:Humans; D019169:Jurkat Cells; D007739:L Cells; D051379:Mice; D008969:Molecular Sequence Data; D004676:Myelin Basic Protein / Q000037:antagonists & inhibitors / Q000235:genetics / Q000276:immunology* / Q000378:metabolism*; D010446:Peptide Fragments / Q000037:antagonists & inhibitors / Q000235:genetics / Q000276:immunology* / Q000378:metabolism*; D011485:Protein Binding / Q000276:immunology; D011993:Recombinant Fusion Proteins / Q000096:biosynthesis; D013347:Subcellular Fractions / Q000276:immunology / Q000378:metabolism; D014162:Transfection; D015854:Up-Regulation / Q000235:genetics / Q000276:immunology
D001324:Autoantigens; D006684:HLA-DR Antigens; D059805:HLA-DR alpha-Chains; D059811:HLA-DRB1 Chains; D018840:HSP70 Heat-Shock Proteins; D004676:Myelin Basic Protein; D010446:Peptide Fragments; D011993:Recombinant Fusion Proteins; C107908:myelin basic protein 85-99