Benita Engvall

Cerebrospinal fluid Aβ42 is increased early in sporadic Alzheimer's disease and declines with disease progression

All mutations known to cause familial Alzheimers disease (AD) act by increasing the levels of soluble β‐amyloid peptide (Aβ), especially the longer form, Aβ42. However, in vivo elevation of soluble Aβ in sporadic AD has so far not been shown. In the present study, we used enzyme‐linked immunosorbent assays specific for Aβ42 and Aβ40 to investigate cerebrospinal fluid from sporadic AD at different stages of disease severity, to clarify the roles of Aβ42 and Aβ40 during disease progression. We also evaluated three other groups—one group of patients with mild cognitive impairment who were at risk of developing dementia, a cognitively intact, nondemented reference group diagnosed with depression, and a perfectly healthy control group. We found that Aβ42 is strongly elevated in early and mid stages of AD, and thereafter it declines with disease progression. On the contrary, Aβ40 levels were decreased in early and mid stages of AD. The group of cognitively impaired patients and the depression reference group had significantly higher levels of Aβ42 than the healthy control group, implying that Aβ42 is increased not only in AD, but in other central nervous system conditions as well. Our data also point out the importance of having thoroughly examined control material. The initial increase and subsequent decrease of Aβ42 adds a new biochemical tool to follow the progression of AD and might be important in the monitoring of therapeutics. Ann Neurol 1999;45:504–511

The Arctic mutation interferes with processing of the amyloid precursor protein.

The Arctic amyloid precursor protein (APP) Alzheimer mutation, is located inside the &bgr;-amyloid (A&bgr;) domain. Here, hybrid APP mutants containing both the Swedish and the Arctic APP mutations were investigated. ELISA measurements of cell media showed decreased levels of both A&bgr;40 and A&bgr;42. Similar results were obtained for the Dutch and Italian mutations, whereas the Flemish mutation displayed increased amounts of A&bgr;40 and A&bgr;42. Immunoprecipitation studies revealed increased A&bgr;40/p340 and A&bgr;42/p342 ratios for the Arctic mutation. These results were further verified by quantification revealing decreased levels of &agr;APPs accompanied by increased &bgr;APPs levels in the media. Thus, the pathogenic effects of the Arctic mutation may not only be due to the changed properties of the peptide but also altered processing of Arctic APP.

Cerebrospinal fluid apolipoprotein E (apoE) levels in Alzheimer's disease patients are increased at follow up and show a correlation with levels of tau protein.

Apolipoprotein E (apoE) levels were compared in cerebrospinal fluid (CSF) taken on two occasions, with an average 15 months follow up, from groups of patients with Alzheimers disease (AD: n = 18), mild cognitive impairment (MCI; n = 9) and other dementia disorders (ODD; n = 9). In these groups, CSF apoE levels were between 2-3-fold higher than values for a group of 27 healthy age-matched controls. CSF apoE levels in the AD group were significantly increased at follow up, compared to levels obtained on the first sampling occasion. For the same cases it had been shown previously that CSF tau protein levels were increased at follow up [Blomberg, M., Jensen, M., Basun, H., Lannfelt, L. and Wahlund, L-O., Neurosci. Lett., 214 (1996) 163-166]. The AD, but not MCI, ODD or control groups, also showed statistically significant correlations between CSF apoE and tau protein levels at both the first (r = 0.585, P < 0.01) and follow up (r = 0.695, P > 0.001 ) samplings. It is concluded that CSF measures of both apoE and tau may reflect an intimate relationship between these two proteins in AD and could prove useful in monitoring the progression of this condition.

An efficient and generic strategy for producing soluble human proteins and domains in E. coli by screening construct libraries

The implementation of generic and efficient technologies for the production of recombinant eukaryotic proteins remains an outstanding challenge in structural genomics programs. We have recently developed a new method for rapid identification of soluble protein expression in E. coli, the colony filtration blot (CoFi blot). In this study, the CoFi blot was used to screen libraries where the N‐terminal translation start point was randomized. To investigate the efficiency of this strategy, we have attributed a large number of proteins to this process. In a set of 32 mammalian proteins, we were able to double the success rate (from 34 to 68%) of producing soluble and readily purifiable proteins in E. coli. Most of the selected constructs had their N‐termini close to predicted domain borders and the method therefore provides a mean for experimental “domain foot printing.” Surprisingly, for most of the targets, we also observed expressing constructs that were close to full‐length. In summary this strategy constitutes a generic and efficient method for producing mammalian proteins for structural and functional studies. Proteins 2006.

A novel pathogenic mutation (Leu262Phe) found in the presenilin 1 gene in early-onset Alzheimer's disease

Several mutations causing early-onset familial Alzheimers disease (AD) have been detected in the presenilin 1 (PS-1) gene. Pathogenic mutations have also been described in an homologous gene, presenilin 2 (PS-2). In order to screen for mutations in these genes, cDNA samples from early-onset AD cases were analysed, using single strand conformation polymorphism (SSCP) and direct cDNA sequencing. Two missense mutations in the PS-1 gene were detected, a previously unidentified amino acid substitution Leu262Phe and an earlier reported amino acid substitution Glu318Gly. No disease-related mutations were found in the PS-2 gene.

Gender differences in the T-cell profiles of the airways in COPD patients associated with clinical phenotypes

T lymphocytes are believed to play an important role in the pathogenesis of chronic obstructive pulmonary disease (COPD). How T cells are recruited to the lungs and contribute to the inflammatory process is largely unknown. COPD is a heterogeneous disease, and discriminating disease phenotypes based on distinct molecular and cellular pathways may provide new approaches for individualized diagnosis and therapies. Bronchoalveolar lavage (BAL) and blood samples were obtained from 40 never-smokers, 40 smokers with normal lung function, and 38 COPD patients. T-cell chemokine receptor expression was analyzed with flow cytometry, and soluble BAL cytokines and chemokines were measured using a cytokine multiplex assay. Correlations with gender and clinical characteristics including lung imaging were investigated using multivariate modeling. Th1/Tc1- and Th2/Tc2-associated soluble analytes and T-cell chemokine receptors were analyzed as cumulative Th1/Tc1 and Th2/Tc2 immune responses. A higher expression of chemokine receptor CCR5 on CD8+ T cells in BAL and higher percentage of CXCR3+CD8+ T cells in blood was found in female smokers with COPD compared to those without COPD. CCR5 expression on CD4+ and CD8+ T cells was lower in BAL from male smokers with COPD compared to those without COPD. Among female smokers with COPD, Th1/Tc1 immune response was linked to BAL macrophage numbers and goblet cell density, and Th2/Tc2 response was associated with the measures of emphysema on high-resolution computed tomography. The highly gender-dependent T-cell profile in COPD indicates different links between cellular events and clinical manifestations in females compared to males. Our findings may reveal mechanisms of importance for the difference in clinical course in female COPD patients compared to males.