Apolipoprotein E and its receptor LRP in AD and control brain

FOURTH INTERNATIONAL CONFERENCE ON ALZHEIMER’S DISEASE

apparent

at the impact

anti-glial

fihriiiary

region.

site in the cortex.

acidic

protein

immunoreactivity phosphorylated

was increased

protein

2

accumulation

of

200kD was observed throughout

the

was reduced. neurofiiament

And a diffuse

fulfilling the CERAD criteria. &relations between p/A4 immunopositive plaqw and cerebmvascuk amyloid, anti-paired helical filament immunopositive neurons, synqtopbysin-like. immunoreac tivity and APOE genotypes were studied in 22 definite AD @ieMs. Brain areas studied were layers III and V of the frontal and temporal cortice.$ and the hippocampal format& including layers II, III and IV-V of the entorhinal cortex. The present study ConfVms the earlier reports that ~4 frequency iS increased in AD compared to nondemented controls (0.3699 vs. 0.1053; 2=2.X5; p=O.O06). We found no relation in counts of p/A4 plaques and degenerating neurons, the degree of cerebrovascular P/A4 deposition or synaptophysin-like immunoreactivity and APOE genotypes in definite AD.

to

in the same

microtubule-associated

contrast,

By

lmmunoreactivity

ceil bodies and dendrites of some neurons only in the impact site. The

abnormal

perikarya

accumulation

may

represent

neurodegenerative that

disorders.

repetition

of

neuropathological

of

neurofilaments

axonal

mild

injury

often

Taken together, traumatic

in

neuronal

associated

s117

with

these data indicate

brain

injury

may

cause

changes similar to those of AD.

483 Apoiipoprotein E and its Receptor LRP in AD and control brain. GW Rebeck, SD Harr, DK Strickland and BT Hyman. Dept of

481 lmmunocytochemioal

and genotypic polymorphism of apolipoprotein E in senile dementias of the AD and non-AD types.

Wecompared the distribution in 4 lipoprotein

E (apoE)

epitopes

the NINCDS-ADRDA Decoding

of

50 brains

structural revealed:

phenotypes Pre-senile

Damentias

(LED): n = 7, mixed AD-vascular (vest-dem):

demented

(mix-dam):

the 50 brains

selected

wara pan,

to control values. results of genotypic frequencies

.OCOl The

Mabs laballad

3 sequences

major hepattn binding sites (Weisgraber. terminus

(3Hl)

the 2 major indirect

and at residues

hepadn

PAP method

binding

(lD7).

Mabs 3Hl

with dilutions

ware statistically significant which inhibited

2

(6C5), the carboxy-

and lD7

a highly

at or greater than l/l000

= 5.26;

= 52.63, vasc-dem = 5.26.

1336). at the amino-terminus

142-152

in 97

wara: ~41~4 controls

of the apo E molecule,

sites. Test runs provided

iraquancy

and 166 aulopsied

= 23.66 and vascdam

~4k3: controls = 21.65. PSAD = 57.14. SDAT = 41.43. mixdem Compared

by

n E 10. and vascular

distribution,

= 1.03. PSAD = 9.52. SDAT = 6.57, LBD = 16.67. mix-dem

at p<

who fullilted disease (AD).

observations

of apo E genotypk

for both age and geographical

of which

Atzhattef’s

double-blind

demantias

n = 9. The satlent features

matched

patients,

after

areas of 3 apo-

patients

AD (PSAD): n = 10. SDAT: n = 14. Lawy Body

damentias

elderly contmls

oi demented

ctttetia for putative, possibie or pmbaMe

the

2 neuropathologists

vulnerable Bmdmann

selectively

amongst

corrasponded

specific

signal

Both pathological

to

Neurology, Mass. General Hospital, Boston, MA 02114 and Biochemistry Laboratory, American Red Cross, Rockviile. MD 20855. Apolipoprotein E (ApoE) and its receptor in the brain, the low density lipoprotein receptor-related protein (LRP) are associated with senile plaques in AD brain. LRP is a multifunctional receptor, binding and mediating internalization of ApoE complexes, a2macroglobulin, iactoferrin, lipoprotein iipase, tissue piasminogen activator, urokinase piasminogen activator and piasminogen activator inhibitor-l. We have found each of these ligands associated with senile plaques. A physiologic regulator of LRP. the receptor associated protein (RAP), blocks binding and uptake of these LRP ligands. in normal brain, RAP coiocalizes with LRP on pyramidal and granule neurons throughout the hippocampal formation. in AD brain, RAP, unlike LRP, is not present on activated astrocytes or senile plaques. We postulate that the LRP present on activated astrocytes is mediating internalization of these ligands, which include proteinaselproteinase inhibitor complexes, iipases. iron binding molecules and ApoE, which may be acting as a pathological chaperone of l3A4. The LRP present on senile plaques may represent receptor shed from ceil membranes or inactive receptor. which binds but cannot internalize its iigands. These observations account for many of the diverse molecules found associated with senile plaques, and highlight the importance of understanding how OA4 may be normally cleared from the neuropil. Supported by NIH Grants AGO8487 and AG05598.

by the control

sections and controls tested with mrrnal pm-immune swum were made from each block. Results showed

: 1) high atlinity for cerebmvascular

deposition of all 3 Mabs. extensively

co-localized wilh amyloid deposits; by confocal microscopy, the endothelium of several vessels was decorated !n ring-like fashion with extensive permeation

throughout all

other vascular layers. 2) plaque decoration was very significantly dependent on 6C5 epitopes and was motpholcgically heterogeneous. 3) binding 01 6C5 epitopes to swumtibfillary

tangles

markedly

predominated

in the extra-neuronal

sub-sets frequently

recorded within pre u au p layers of the entorhinal cortex. 4) all Mabs provided strong cytoplasmic astrocylic immunoreactivity. 5) brains oi vascular dementia displayed little or no affinity for all Mabs. We conclude that apo E Mabs strongest aftinity was cerebmvascular. We hypothesized

that the more selective plaque 6C5 binding indicated a

stronger atfinity of plaques for hepadn binding sites, compared with astrocytic labelling, which appeared more dependent on numbers oi LDL glial CNS receptor

sitas.

482 PIA4 DEPOSITION, NEURAL DEGENERATION AND SYNAPSE PATHOLOGY IN ALZHBIMER PATIENTS OF DIFFERENT APOLIPOPRIYIEIN B GEN(YI’YPES. 0. Heinonen, S. Helisalmi, H. Soinka, S. Mannermaa, M. Lehtovirta, H. Sorvari, 0. Kosunezn, L. Paljiirvi, M. Ryynllnm, and P. Rielrlcinen Sr. Depts. of Neurology and Pathology, Unit of Clinical Genetics of the Dept. of Gynecology and Obstetrics, Kuopio Univexsity Ho&al, Univ. of Kuopio, FOB 1627, SF70211 Kuopio, FINLAND. IwrcasCd frequency of apolilqnWein B (APOE) allele s4 was reported in patients with lata-oaset sporadic and familkl Al&imer’s disease (AD). Recently, increased amyloid accumulatioa as plaques and cerebrovascular amyloid was qaxted in brains of AD patients homozygous for AFOE ~4. In this study, APOE genotypes wae &&mined in 38 nondemented

controls (26 women/l2 men; 75.8f9.2 years) and 73 patients with AD (49 women/24 rnen;75.3fll.l years). Thirty-two were definite AD cases

484 Exchangeable Apdipoproteins Expression in the Brain and the NB of AD. Steven D Harr, Armando J Mendez, Luciana Uint, G William Rebeck, and Bradley T Hyman. Dept of Neurology and Oept of Medicine, Massachusetts General Hospital and Harvard Medical School, Boston, MA, 02 114, USA. Apolipoprotein E (ApoE) and ApoJ immunostain senile plaques (SP) in Alzheimer’s disease (AD) and bind the hydrophobic Afi amyloid peptide in vitro. They are members of a class of proteins, the exchangeable apolipoproteins, which are characterized by highly conserved amphipathic helical repeat units. These apdipoproteins are contained within high density lipoproteins, which are important in reverse cholesterol transport and lipid clearance. We studied Seven members in this class of lipoproteins - apolipoproteins A-l, A-II, A-IV, C-II, D, E and J - of which ApoA-I and ApoE are the most abundant. Genetic studies have linked two of these apolipoproteins, ApoC-II and ApoE, with AD. We used immunohistochemistry and Western blot analysis to further investigate the role of exchangeable apolipoproteins in the pathogenesis of AD. SP and vascular amyloid in cortex were strongly immunopositive for ApoJ and ApoE. ApoE also stained astrocytes. ApoA-I immunoreactivity was present in many SP, essentially all cerebral vessels, and a minority of neurons in the hippocampal formation. Ape A-II and ApoA-IV also stained a minority of neurons of the hippocampai formation, but were not present in SP or in vessel walls. ApoD immunoreactivity was present in the neuropil, consistent with previous studies that have shown it is produced in astrotytes. ApcC-II did not stain either AD or control tissue. We used Western blot analysis to study the relative levels of apolipoproteins A-l, AIV, C-II, D, E, and J in SDS-soluble protein homogenates of frmtal lobe of AD and contrd tissua. ApoC-II was not detectable in brain homogenates of AD or contrd. In ten AD brains, ApoA-I levels decreased by 27% (~~0.05) in comparison to ten control brains. The levels of the other apolipoproteins did not change between AD and control tissue. Specifically, ApoE protein levels were not found to increase, despite evidence that ApoE mRNA levels are increased in AD. It is possible that ApoE is sequestered in a non-SDS soluble form, or that turnover of ApoE is accelerated in AD. We suggest that several members of the exchangeable apdipoproteins have the ability to bind Ag and