Distinctive RNA expression profiles in blood associated with white matter hyperintensities in brain.
OBJECTIVE
White matter hyperintensities (WMH) are areas of high signal detected by T2 and fluid-attenuated inversion recovery sequences on brain MRI. Although associated with aging, cerebrovascular risk factors, and cognitive impairment, the pathogenesis of WMH remains unclear. Thus, RNA expression was assessed in the blood of individuals with and without extensive WMH to search for evidence of oxidative stress, inflammation, and other abnormalities described in WMH lesions in brain.


METHODS
Subjects included 20 with extensive WMH (WMH+), 45% of whom had Alzheimer disease, and 18 with minimal WMH (WMH-), 44% of whom had Alzheimer disease. All subjects were clinically evaluated and underwent quantitative MRI. Total RNA from whole blood was processed on human whole genome Affymetrix HU133 Plus 2.0 microarrays. RNA expression was analyzed using an analysis of covariance.


RESULTS
Two hundred forty-one genes were differentially regulated at ± 1.2-fold difference (P < 0.005) in subjects with WMH+ as compared to WMH-, regardless of cognitive status and 50 genes were differentially regulated with ± 1.5-fold difference (P < 0.005). Cluster and principal components analyses showed that the expression profiles for these genes distinguished WMH+ from WMH- subjects. Function analyses suggested that WMH-specific genes were associated with oxidative stress, inflammation, detoxification, and hormone signaling, and included genes associated with oligodendrocyte proliferation, axon repair, long-term potentiation, and neurotransmission.


CONCLUSIONS
The unique RNA expression profile in blood associated with WMH is consistent with roles of systemic oxidative stress and inflammation, as well as other potential processes in the pathogenesis or consequences of WMH.
Department of Neurology and M.I.N.D. Institute, University of California at Davis, Sacramento, CA 95817, USA. huixu@ucdavis.edu
Huichun
H
Xu
Boryana
B
Stamova
Glen
G
Jickling
Yingfang
Y
Tian
Xinhua
X
Zhan
Bradley P
BP
Ander
Dazhi
D
Liu
Renée
R
Turner
Jonathan
J
Rosand
Larry B
LB
Goldstein
Karen L
KL
Furie
Piero
P
Verro
S Claiborne
SC
Johnston
Frank R
FR
Sharp
Charles S
CS
Decarli
D000368:Aged; D000544:Alzheimer Disease / Q000235:genetics / Q000378:metabolism / Q000473:pathology; D001921:Brain / Q000473:pathology*; D016000:Cluster Analysis; D005260:Female; D006728:Hormones / Q000502:physiology; D006801:Humans; D007249:Inflammation / Q000473:pathology; D008279:Magnetic Resonance Imaging; D008297:Male; D046228:Microarray Analysis; D018384:Oxidative Stress / Q000235:genetics / Q000502:physiology; D025341:Principal Component Analysis; D012313:RNA / Q000096:biosynthesis* / Q000097:blood* / Q000235:genetics; D015398:Signal Transduction / Q000235:genetics / Q000502:physiology
D006728:Hormones; D012313:RNA