ABSTRACT
Multiple Sclerosis is an autoimmune disease directed against myelin proteins. The etiology of MS is poorly defined though, with no definitive causative agent yet identified. It has been hypothesized that MS may be a multifactorial disease resulting in the same end product: the destruction of myelin by the immune system. In this report we describe a potential role for heat shock proteins in the pathogenesis of MS. We isolated Hsp70 from the normal appearing white matter of both MS and normal human brain and found this was actively associated with, among other things, immunodominant MBP peptides. Hsp70-MBP peptide complexes prepared in vitro were shown to be highly immunogenic, with adjuvant-like effects stimulating MBP peptide-specific T cell lines to respond to normally sub-optimal concentrations of peptide. This demonstration of a specific interaction between Hsp70 and different MBP peptides, coupled with the adjuvanticity of this association is suggestive of a possible role for Hsp70 in the immunopathology associated with MS.
Subject(s)
Autoantigens/immunology , Brain Chemistry , Epitopes, T-Lymphocyte/immunology , HSP70 Heat-Shock Proteins/immunology , Immunodominant Epitopes/immunology , Multiple Sclerosis/immunology , Myelin Sheath/chemistry , Nerve Tissue Proteins/immunology , Peptide Fragments/immunology , T-Cell Antigen Receptor Specificity , Transcription Factors/immunology , Adjuvants, Immunologic , Amino Acid Sequence , Autoantigens/chemistry , Autoantigens/isolation & purification , Cell Line , Epitopes, T-Lymphocyte/chemistry , Epitopes, T-Lymphocyte/isolation & purification , HSP70 Heat-Shock Proteins/chemistry , HSP70 Heat-Shock Proteins/isolation & purification , Humans , Immunodominant Epitopes/chemistry , Immunodominant Epitopes/isolation & purification , Immunoprecipitation , Molecular Sequence Data , Multiple Sclerosis/metabolism , Multiple Sclerosis/pathology , Myelin Basic Protein , Nerve Tissue Proteins/chemistry , Nerve Tissue Proteins/isolation & purification , Peptide Fragments/chemistry , Peptide Fragments/isolation & purification , Protein Interaction Mapping , Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization , T-Lymphocytes/immunology , Transcription Factors/chemistry , Transcription Factors/isolation & purificationABSTRACT
The hematopoietic stem cell (HSC) compartment is composed of long-term reconstituting (LTR) and short-term reconstituting (STR) stem cells. LTR HSC can reconstitute the hematopoietic system for life, whereas STR HSC can sustain hematopoiesis for only a few weeks in the mouse. Several excellent gene expression profiles have been obtained of the total hematopoietic stem cell population. We have used five-color FACS sorting to isolate separate populations of LTR and STR stem cell subsets. The LTR HSC has the phenotype defined as Lin- Sca+ Kit+ 38+ 34-; two subsets of STR HSC were obtained with phenotypes of Lin- Sca+ Kit+ 38+ 34+ and Lin- Sca+ Kit+ 38- 34+. The microarray profiling study reported here was able to identify genes specific for LTR functions. In the interrogated genes (approximately 12,000 probe sets corresponding to 8,000 genes), 210 genes are differentially expressed, and 72 genes are associated with LTR activity, including membrane proteins, signal transduction molecules, and transcription factors. Hierarchical clustering of the 210 differentially expressed genes suggested that they are not bone marrow-specific but rather appear to be stem cell-specific. Transcription factor-binding site analysis suggested that GATA3 might play an important role in the biology of LTR HSC.
