Features of senile cerebral amyloidosis

It is established, on the basis of the autopsy material of I. M. Sechenov First Moscow Medical Institute for 1983-1987 (517 patients who died at the age of 40-89 years), that senile cerebral amyloidosis (SCA) is a local form of senile amyloidosis which occurs in 4.4% persons over 60 years of age. At the autopsy SCA is revealed in 21.4% cases, but the examination of the brain for amyloid increases the percent up to 78.6. Amyloid deposits are observed as senile plaques in the vessels of pia mater, plexus chorioideus and intracerebral vessels. Genetic factors in the SCA development can not be excluded.     

Age incidence of senile brain amyloidosis

Neuropathological examination of 1400 successive autopsies in general and mental hospitals revealed that senile plaques and congophilic angiopathy are age related phenomena. There is, however, a remarkable difference between the two types of manifestation of senile amyloidosis. There was a significantly higher incidence of senile plaques in females. Moreover the increase of the incidence with age was also significantly higher in females. Congophilic angiopathy showed no predominance in females. In total 59% of males and 55% of females with senile plaques suffered from Senile Dementia of the Alzheimer Type (SDAT). SDAT appeared to be also an age related phenomenon characterized by a linear increase with age and a predominance in females.     

Spontaneous amyloidosis in senile NSY mice

Senile Nagoya, Shibata, Yasuda (NSY) mice developed amyloidosis and died from renal failure as a result of amyloidosis. NSY mice were first reported as experimental congenital diabetic mice by Shibata et al. in 1980. This study questioned whether NSY mice died from diabetic nephropathy. The authors of the present study investigated the life span and cause of death in these micde. The life span of NSY mice was found to be 618.7 ± 72.5 days. NSY mice that lived for more than 400 days showed rising blood uread nitrogen and large amounts of amyloid deposits in the glomerulus of the kidneys. NSY mice died of renal amyloidosis. Immunological methods revealed that AApoAll was evident in the amyloid deposits of NSY mice. Apart from the kidneys, amyloid deposition was also found in the tongue, esojphagus, stomach, small intestine, large intestine, rectum, lung, heart and adrenal glands. Amyloid deposits were found to a slight degree In the liver and the spleen. The most dominant amyloid deposition in NSY mice was seen in the glomerulus of the kidneys. From the point of view of amyloid depositional distribution, NSY mice were unique compared with other spontaneous amyloid mice.     

Transmission of amyloidosis in offspring of mice with AApoAII amyloidosis

Pre-existing amyloid fibrils can induce further polymerization of endogenous precursor proteins in vivo. Thus, transmission of amyloid fibrils (AApoAII) may induce a conformational change in endogenous apolipoprotein A-II and accelerate amyloid deposition in mouse senile amyloidosis. To characterize transmissibility, we examined amyloidosis in the offspring of AApoAII-injected mother mice that possessed the amyloidogenic Apoa2(c) allele of the apolipoprotein A-II gene. At 4 months of age, amyloid deposits were detected in the intestines of offspring born from and nursed by amyloid fibril-injected mothers, with intensity of deposition increasing thereafter. No amyloid deposits were detected in the offspring of noninjected control mothers. Accelerated amyloidosis was also observed in offspring born from mothers without injection but nursed by amyloid fibril-injected mothers. However, this was not observed in offspring born from amyloid fibril-injected mothers but nursed by control mothers. This fostering excluded vertical transmission through the placenta, suggesting the presence of factors that accelerate amyloidosis during the nursing period. In addition, milk obtained from amyloid fibril-injected mothers induced AApoAII amyloidosis in young mice, and transmission electron microscopy detected noodle-like amyloid fibrils in milk of amyloid fibril-injected mothers. These results provide important insight into the etiology and pathogenesis of amyloid diseases.     

Transgenic mouse model of AA amyloidosis

AA amyloidosis can be induced in mice experimentally through injection of certain chemical or biological compounds. However, the usefulness of this approach is limited by its dependence on exogenous inflammatory agents that stimulate cytokines to increase the synthesis of precursor serum amyloid A (SAA) protein and the transitory nature of the pathological fibrillar deposits. We now report that transgenic mice carrying the human interleukin 6 gene under the control of the metallothionein-I promoter had markedly increased concentrations of SAA and developed amyloid in the spleen, liver, and kidneys by 3 months of age. At the time of death about 6 months later, organs obtained from these animals had extensive amyloid deposits. This disease process was apparent radiographically using small-animal computer axial tomography and magnetic resonance imaging equipment. The AA nature of the amyloid was evidenced immunohistochemically and was unequivocally established by sequence analysis of protein extracted from the fibrils. The availability of this unique in vivo experimental model of AA amyloidosis provides the means to assess the therapeutic efficacy of agents designed to reduce or prevent the fibrillar deposits found in AA and other types of amyloid-associated disease.     

Inhibition of senile amyloidosis of mice by biscarboxyethyl germanium sesqui-oxide.

A mouse strain, ICR/SLC, was involved in spontaneous amyloidosis with high incidence. The amyloid deposition in this strain was seen mainly in the mucosal propria of duodenum and terminal ileum, liver, spleen, adrenal cortices, and renal glomeruli. The mice, orally administered more than 300 mg/kg of organic germanium for 22 months since 5 weeks old, did not develop amyloidosis. Half of the mice, given 30 mg/kg of organic germanium for 22 months developed amyloidosis. The mice given 5% carboxymethylcellulose, the solvent of organic germanium, were affected with systemic amyloidosis with high frequency. The results showed that the organic germanium successfully inhibited the occurrence of senile amyloidosis with dose response. The agent did not have any apparent relation to the incidence of hepatic cell carcinoma or pulmonary adenoma which is frequently combined with aged mice. Although the actual mechanism involved is not clear, the evidence of the inhibition of senile amyloidosis by organic germanium may give a light to elucidate the pathogenesis of amyloidosis.     

Local senile ocular amyloidosis in the pathogenesis of open-angle glaucoma and pseudo-exfoliative syndrome

A total of 173 biopsy samples of the iris and drainage apparatus obtained at anti-glaucoma operations from 115 patients, aged 32 to 90, with primary open-angle glaucoma and pseudoexfoliative syndrome of different severity degrees were morphologically examined. Similar anatomofunction embryological peculiarities of the eye and brain create prerequisites for the development, in the eye, of processes analogical to Alzheimer's disease. Amyloid angiopathy of the iris is a key element of ischemia, which triggers the mechanisms of apoptosis and lipid peroxidation in the pigment epithelium membranes; this process is accompanied by an intensified synthesis and conformation of fibrous structures of tauprotein and beta-amyloid. Defradation of melanin and proteoglycans leads to the formation of neurotoxic metabolites. The above processes result in suppressing the protective antioxidant reactions as well as in blocking, by fibrous structures, the cellular cytoplasm and extracellular matrix.     

Novel histochemical approaches to the prealbumin-related senile and familial forms of systemic amyloidosis

The immunoperoxidase method, the autoclave method, and a newly developed alkaline-guanidine method were used to distinguish senile (SSA) and familial types (FAP) of prealbumin-related amyloidosis in formalin-fixed, paraffin-embedded tissue sections. Because all the amyloid deposits of SSA and FAP reacted positively with the antiprealbumin antiserum, a classification of the amyloid fibril proteins of FAP and SSA by immunohistochemistry, using polyclonal anti-prealbumin antisera, was not feasible. Both the senile and familial forms of amyloidosis showed unchanged Congophilia after prolonged autoclaving. In the alkaline-guanidine method, FAP amyloids were resistant to incubation for 2 hours. On the other hand, amyloid deposits of SSA lost the Congophilia and green birefringence with 2 hours' alkaline-guanidine treatment. Therefore, the autoclave method combined with the alkaline-guanidine method will considerably facilitate differentiation of SSA and FAP, without specific antisera.     

Immunotherapy of cerebrovascular amyloidosis in a transgenic mouse model

Cerebrovascular amyloidosis is caused by amyloid accumulation in walls of blood vessel walls leading to hemorrhagic stroke and cognitive impairment. Transforming growth factor-β1 (TGF-β1) expression levels correlate with the degree of cerebrovascular amyloid deposition in Alzheimer's disease (AD) and TGF-β1 immunoreactivity in such cases is increased along the cerebral blood vessels. Here we show that a nasally administered proteosome-based adjuvant activates macrophages and decreases vascular amyloid in TGF-β1 mice. Animals were nasally treated with a proteosome-based adjuvant on a weekly basis for 3 months beginning at age 13 months. Using magnetic resonance imaging (MRI) we found that while control animals showed a significant cerebrovascular pathology, proteosome-based adjuvant prevents further brain damage and prevents pathological changes in the blood-brain barrier. Using an object recognition test and Y-maze, we found significant improvement in cognition in the treated group. Our findings support the potential use of a macrophage immunomodulator as a novel approach to reduce cerebrovascular amyloid, prevent microhemorrhage, and improve cognition.     

Spontaneous age-associated amyloidosis in senescence-accelerated mouse (SAM)

Morphological studies on spontaneous systemic amyloidosis were conducted on 222 senescence-accelerated mice (SAM) (P) and on 150 mice in the senescence-resistant series (R).Among the pathologic findings, amyloidosis showed the highest incidence in both SAM (79.7%) and R (32.7%) Although an extensive deposition of amyloid was evident in some aged mice in the R series, a more severe amyloidosis occurred with a higher incidence in the P series. There was a statistical significance between the incidence of amyloidosis and age, in both the P and R series. There were no differences in organ distribution and mode of amyloid deposition between the P and R series or between the sexes. In about 60% of the amyloid-positive cases in the 28 killed SAM and 7 mice in the R series, there were no signs of inflammation or neoplasm.The morphological features in SAM more closely resembled those seen in cases of murine spontaneous senile amyloidosis than the features seen in cases of experimentally induced amyloidosis. This model is expected to be a valuable tool with which to assess the relationship between amyloid deposition and the aging process or senescence, perhaps even cases of human senile amyloidosis.     

Impaired angiogenesis in a transgenic mouse model of cerebral amyloidosis

Abeta peptides are naturally occurring peptides, which are thought to play a key role in the pathophysiology of Alzheimer's disease (AD). In AD cases, levels of soluble and insoluble Abeta peptides increase in the brain as well as in the cerebrovasculature, a phenomenon that does not occur in extra-cranial vessels. There are frequently anomalies in the cerebrovasculature in AD, and despite increases in several pro-angiogenic factors in AD brain, evidence for increased vascularity is lacking; in fact there is evidence to the contrary. It has also been recently shown that Abeta peptides may have profound anti-angiogenic effects in vitro and in vivo. We therefore investigated whether there is evidence for altered angiogenesis in the vasculature in a transgenic mouse model of Abeta amyloidosis (Tg APPsw line 2576). In vitro, the formation of capillary-like structures on a reconstituted extracellular matrix by endothelial cells isolated from Tg APPsw is impaired. Ex vivo, the sprouting of new capillaries from arterial explants (over expressing Abeta) isolated from 9-month-old Tg APPsw is reduced compared to arterial explants isolated from control littermates. In addition, Tg APPsw mice show a reduction in vascular density in the cortex and hippocampus compared to control littermates. Altogether, our data suggest that the over expression of APPsw in the vasculature may oppose angiogenesis.     

Histomorphometric analysis of intramyocardial vessels in primary and senile amyloidosis: epicardium versus endocardium.

BACKGROUND: The literature is unclear as to the frequency and degree of vascular involvement among the various types of cardiac amyloidosis, specifically the senile type. METHODS: We analyzed the intramyocardial vascular involvement, both qualitatively and quantitatively, in 18 patients with autopsy-proven cardiac amyloidosis [11 with primary amyloidosis (AL) and 7 with senile systemic amyloidosis (SSA)]. RESULTS: AL patients (10/11) showed focally transmural vascular involvement by amyloid with thickening of the wall and impingement on the lumens. In SSA patients (6/7), the amyloid deposition was concentrated largely in the adventitia and external media. Histomorphometric analysis revealed that all patients with AL, SSA, and heart failure without amyloidosis had greater luminal areas than normal controls. In addition, the median of the ratio of subendocardial to subepicardial vascular luminal areas was 0.59 in AL patients, 1.17 in SSA patients, 0.94 in heart failure without amyloidosis patients, and 0.89 in normal controls (P=.034). CONCLUSIONS: This study shows that the degree of vascular involvement and wall thickening with subsequent impingement on the lumen is much greater in AL than in SSA. All patients with heart failure, with and without amyloidosis, displayed greater luminal areas than normal controls. Moreover, a twofold dilatation of the vessels in the subepicardium compared to those in the subendocardium was noted only in patients with AL. This may be due to transmural vascular involvement by amyloid in these patients, which concomitantly decreases the transmural ventricular perfusion pressure, leading to compensatory expansion of the subepicardial vessels.     

Serum prealbumin and retinol-binding protein in the prealbumin-related senile and familial forms of systemic amyloidosis

In a series of 13 elderly patients with proven prealbumin-related senile systemic amyloidosis (SSA), depressed serum prealbumin values (110.7 +/- 14.1 micrograms/ml) were found as compared to an age-matched control group (175.1 +/- 20.3 micrograms/ml). As expected, there was a significant correlation between serum prealbumin and serum retinol-binding proteins in both groups of patients. Patients with reactive amyloid protein AA amyloidosis had slightly depressed serum prealbumin concentrations, whereas patients with prealbumin-related familial amyloidosis of Swedish type had prealbumin values within normal limits. Since the serum levels of the acute phase reactants, haptoglobin and amyloid-related serum protein AA, were higher in the group of patients with reactive amyloidosis than in patients with SSA, the depression of the prealbumin levels in SSA is not a result of inflammation. Since SSA is known to contain prealbumin, it is possible that a disturbed prealbumin metabolism in old age results in low prealbumin serum values and deposition of amyloid.     

Amyloid of the seminal vesicles. A distinctive and common localized form of senile amyloidosis.

Amyloid deposits were found subepithelially in the seminal vesicles of 34 of 209 consecutively studied men. The incidence increased with age and was found in 21% of men over 75 years. This senile seminal vesicle amyloidosis (SSVA) is a localized disorder, and the amyloid substance has unique histochemical and immunochemical properties not shared with any other amyloid described until now.     

Oleic acid ameliorates amyloidosis in cellular and mouse models of Alzheimer's disease

Several lines of evidence support protective as well as deleterious effects of oleic acid (OA) on Alzheimer's disease (AD) and other neurological disorders; however, the bases of these effects are unclear. Our investigation demonstrates that amyloid precursor protein (APP) 695 transfected Cos-7 cells supplemented with OA have reduced secreted amyloid-beta (Aβ) levels. An early-onset AD transgenic mouse model expressing the double-mutant form of human APP, Swedish (K670N/M671L) and Indiana (V717F), corroborated our in vitro findings when they were fed a high-protein, low-fat (18% reduction), cholesterol-free diet enriched with OA. These mice exhibited an increase in Aβ40/Aβ42 ratio, reduced levels of beta-site APP cleaving enzyme (BACE) and reduced presenilin levels along with reduced amyloid plaques in the brain. The decrease in BACE levels was accompanied by increased levels of a non-amyloidogenic soluble form of APP (sAPPα). Furthermore, the low-fat/+OA diet resulted in an augmentation of insulin-degrading enzyme and insulin-like growth factor-II. These results suggest that OA supplementation and cholesterol intake restriction in a mouse model of AD reduce AD-type neuropathology.     

Inflammatory responses to amyloidosis in a transgenic mouse model of Alzheimer's disease

Mutations in the amyloid precursor protein (APP) and presenilin-1 and -2 genes (PS-1, -2) cause Alzheimer's disease (AD). Mice carrying both mutant genes (PS/APP) develop AD-like deposits composed of beta-amyloid (Abeta) at an early age. In this study, we have examined how Abeta deposition is associated with immune responses. Both fibrillar and nonfibrillar Abeta (diffuse) deposits were visible in the frontal cortex by 3 months, and the amyloid load increased dramatically with age. The number of fibrillar Abeta deposits increased up to the oldest age studied (2.5 years old), whereas there were less marked changes in the number of diffuse deposits in mice over 1 year old. Activated microglia and astrocytes increased synchronously with amyloid burden and were, in general, closely associated with deposits. Cyclooxygenase-2, an inflammatory response molecule involved in the prostaglandin pathway, was up-regulated in astrocytes associated with some fibrillar deposits. Complement component 1q, an immune response component, strongly colocalized with fibrillar Abeta, but was also up-regulated in some plaque-associated microglia. These results show: i) an increasing proportion of amyloid is composed of fibrillar Abeta in the aging PS/APP mouse brain; ii) microglia and astrocytes are activated by both fibrillar and diffuse Abeta; and iii) cyclooxygenase-2 and complement component 1q levels increase in response to the formation of fibrillar Abeta in PS/APP mice.