The load of Chlamydia pneumoniae in the Alzheimer's brain varies with APOE genotype.
Studies from this laboratory have indicated that the intracellular eubacterial respiratory pathogen Chlamydophila (Chlamydia) pneumoniae is commonly found in brain regions displaying characteristic neuropathology in patients with late-onset Alzheimer's disease (AD) but not in congruent samples from non-AD control individuals. In later work, we provided evidence suggesting that some relationship exists between the APOE epsilon4 gene product and the pathobiology of this organism. In the present report, in situ hybridization analyses indicated that the number of C. pneumoniae-infected cells in affected brain regions of epsilon4-bearing AD patients was higher overall than that in congruent brain regions from AD patients lacking that allele. Quantitative real-time PCR analyses of AD brain tissue samples demonstrated that actual bacterial burden in those samples varied over several orders of magnitude, but that samples from epsilon4-bearing patients did have significantly higher bacterial loads than did congruent samples from patients without the allele (ANOVA, p<0.05). These results may explain in part the observations that epsilon4-bearing individuals have a higher risk of developing AD, and that such patients progress more rapidly to cognitive dysfunction than do individuals lacking this allele.
Department of Immunology and Microbiology, Wayne State University School of Medicine, Detroit, MI 48201, USA.
Hervé C
HC
Gérard
Kristin L
KL
Wildt
Judith A
JA
Whittum-Hudson
Zongshan
Z
Lai
Joel
J
Ager
Alan P
AP
Hudson
D000368:Aged; D000369:Aged, 80 and over; D000544:Alzheimer Disease / Q000235:genetics* / Q000382:microbiology* / Q000473:pathology; D001057:Apolipoproteins E / Q000235:genetics*; D001921:Brain / Q000382:microbiology* / Q000473:pathology; D023521:Chlamydophila Infections / Q000382:microbiology*; D016993:Chlamydophila pneumoniae / Q000302:isolation & purification* / Q000472:pathogenicity; D005260:Female; D018628:Gene Dosage; D005838:Genotype; D006801:Humans; D008297:Male; D008875:Middle Aged
D001057:Apolipoproteins E