epidermal-growth-factor and Hyperlipidemias

Alzheimer's disease (AD) is a severe neurodegenerative disorder characterized mainly by accumulation of amyloid-β plaques and neurofibrillary tangles, synaptic and neuronal loss. Blood platelets contain the neurotransmitter serotonin and amyloid-precursor protein (APP), and may thus be useful as a peripheral biomarker for AD. The aim of the present study was to functionally characterize platelets by FACS, to examine alterations in APP expression and secretion, and to measure serotonin levels in hypercholesterolemia mice with AD-like pathology and in two AD mouse models, the triple transgenic AD model (3xTg) and the APP overexpressing AD model with the Swedish-Dutch-Iowa mutations (APP_SweDI). These data are supplemented with epidermal growth factor (EGF) levels and compared with changes observed in platelets of patients with AD. We observed decreased platelet APP isoforms in 3xTg mice and patients with AD when analysed by means of Western blot. In patients, a significant increase of APP levels was observed when assessed by ELISA. Secreted APPβ proved to be altered amongst all three animal models of AD at different time points and in human patients with AD. Serotonin levels were only reduced in 7 and 14 month old 3xTg mice. Moreover, we found significantly lower EGF levels in human AD patients and could thereby reproduce previous findings. Taken together, our data confirm that platelets are dysfunctional in AD, however, results from AD animal models do not coincide in all aspects, and markedly differ when compared to AD patients. We support previous data that APP, as well as EGF, could become putative biomarkers for diagnosing AD in human platelets.

Topics: Aged; Aged, 80 and over; Alzheimer Disease; Amyloid beta-Protein Precursor; Animals; Apoptosis; Biomarkers; Blood Platelets; Case-Control Studies; Cross-Sectional Studies; Disease Models, Animal; Epidermal Growth Factor; Female; Genotype; Humans; Hyperlipidemias; Male; Mice, Transgenic; Phenotype; Serotonin; Species Specificity; Time Factors

Platelets, macrophages, endothelial cells, and smooth muscle cells can all contribute to atherosclerosis. To investigate the molecular events leading to atherosclerosis involving platelets, macrophages, endothelial cells, and smooth muscle cells, we carried out suppression subtractive hybridization (SSH) to generate a profile of genes overexpressed in the aorta and blood cells in high fat diet rats. From 85 random SSH-cDNA clones, we have screened 23 clones by Northern blotting, which were scored as overexpressed in the aorta and blood cells in high fat diet rats compared to normal diet rats. Sequencing showed that the gene corresponded to the known gene in the public databases, previously shown to be overexpressed in atherosclerosis, heparin-binding epidermal growth factor (EGF)-like growth factor (HB-EGF), and local production was seen in vascular smooth muscle and endothelial cells by RT-PCR and Western blotting. These results show that SSH provides a very efficient means to produce a profile of differentially expressed genes in atherosclerosis. The identified gene may provide novel points of therapeutic intervention and pathophysiological mechanisms in atherosclerosis.

Topics: Animals; Aorta; Blood Cells; Diet, Atherogenic; Epidermal Growth Factor; Expressed Sequence Tags; Female; Gene Expression Profiling; Heparin-binding EGF-like Growth Factor; Hyperlipidemias; Intercellular Signaling Peptides and Proteins; Male; Nanotechnology; Oligonucleotide Array Sequence Analysis; Rats; Rats, Sprague-Dawley