Adherence-dependent shifts in the patterns of beta-amyloid peptides secreted by human mononuclear phagocytes.
Cells of the mononuclear phagocyte system are closely associated with vascular and neuritic beta-amyloid deposits in Alzheimer's disease. Using one-dimensional and newly developed two-dimensional Abeta-SDS-PAGE Western immunoblot techniques (1D/2D-Abeta-WIB) we investigated the patterns of Abeta peptides released by primary non-adherent and adherence-activated human mononuclear phagocytes in vitro. An overall increase of total released Abeta peptides (Abeta(total)) was observed in adherence-activated mononuclear phagocyte cultures. 2D-Abeta-WIB revealed that the proportion of Abeta(1-40) decreased significantly to 50.2+/-5.4% (n=10) of Abeta(total) compared to 65.9+/-5.6% (n=7) in non-adherent cultures (p<0.0001, t=5.82). Abeta(1-42) accounted for only 3.0+/-2.1% of Abeta(total) and its proportion did not change significantly upon adherence (2.8+/-0.5% of Abeta(total)). In adherence-activated cultures we detected pronounced shifts in the fractional pattern of released Abeta peptides in favour of N-truncated species. The second most prominent Abeta peptide accounted for as much as 12.7+/-3.0% of Abeta(total) (2.0+/-1.2% in non-adherent cultures; p<0.0001, t=9.00) and was identified as Abeta(2-40) by comigration with a synthetic peptide and by N-terminal-specific antibodies. A strong increase of a further Abeta immunoreactive spot migrating at pI 5.45 was observed. It accounted for 9.2+/-1.7% of Abeta(total) as compared to 1.0+/-0.9% in non-adherent cultures (p<0.0001, t=11.61) and presumably represented a variant of Abeta(2-40) as determined by C-terminal Abeta(40)-specific immunoprecipitation and N-terminal-specific immunodetection. Thus, mononuclear phagocytes might be one source of the N-truncated Abeta peptides regularly found in human plasma and are less likely to contribute substantially to plasma Abeta(1-42).
Department of Psychiatry and Psychotherapy, University of Erlangen-Nuremberg, Schwabachanlage 6, D-91054 Erlangen, Germany. Electronic address: Manuel.Maler@uk-erlangen.de.
Juan Manuel
JM
Maler
Department of Psychiatry and Psychotherapy, University of Erlangen-Nuremberg, Schwabachanlage 6, D-91054 Erlangen, Germany.
Philipp
P
Spitzer
Department of Psychiatry and Psychotherapy, University of Erlangen-Nuremberg, Schwabachanlage 6, D-91054 Erlangen, Germany.
Hans-Wolfgang
HW
Klafki
Department of Psychiatry and Psychotherapy, University of Erlangen-Nuremberg, Schwabachanlage 6, D-91054 Erlangen, Germany; Department of Psychiatry and Psychotherapy, University of Essen, Virchowstr. 174, D-45147 Essen, Germany.
Hermann
H
Esselmann
Department of Psychiatry and Psychotherapy, University of Essen, Virchowstr. 174, D-45147 Essen, Germany.
Mirko
M
Bibl
Department of Psychiatry and Psychotherapy, University of Erlangen-Nuremberg, Schwabachanlage 6, D-91054 Erlangen, Germany.
Piotr
P
Lewczuk
Department of Psychiatry and Psychotherapy, University of Erlangen-Nuremberg, Schwabachanlage 6, D-91054 Erlangen, Germany.
Johannes
J
Kornhuber
Department of Medicine III, Institute for Clinical Immunology, University of Erlangen-Nuremberg, Glückstr. 4a, D-91054 Erlangen, Germany.
Martin
M
Herrmann
Department of Psychiatry and Psychotherapy, University of Erlangen-Nuremberg, Schwabachanlage 6, D-91054 Erlangen, Germany; Department of Psychiatry and Psychotherapy, University of Essen, Virchowstr. 174, D-45147 Essen, Germany.
Jens
J
Wiltfang
D000328:Adult; D000544:Alzheimer Disease / Q000097:blood*; D016229:Amyloid beta-Peptides / Q000097:blood* / Q000737:chemistry / Q000302:isolation & purification; D015153:Blotting, Western; D002478:Cells, Cultured; D015180:Electrophoresis, Gel, Two-Dimensional / Q000379:methods; D004591:Electrophoresis, Polyacrylamide Gel; D006801:Humans; D009000:Monocytes / Q000166:cytology / Q000378:metabolism*; D010446:Peptide Fragments / Q000097:blood / Q000302:isolation & purification; D010586:Phagocytes / Q000166:cytology / Q000378:metabolism*
D016229:Amyloid beta-Peptides; D010446:Peptide Fragments