The cerebral hemorrhage-producing cystatin C variant (L68Q) in extracellular fluids.

A variant of the normal extracellular cysteine protease inhibitor cystatin C (L68Q-cystatin C), is the amyloid precursor in hereditary cystatin C amyloid angiopathy (HCCAA). It has been suggested that the mutation causes cellular entrapment of L68Q-cystatin C in vivo and that the variant protein is not secreted to extracellular fluids. In order to test this hypothesis, we used matrix-assisted laser desorption ionization time-of-flight mass spectrometry in an effort to demonstrate the presence of L68Q- along with wildtype cystatin C in plasma and cerebrospinal fluid (CSF) of HCCAA-patients. Plasma from all five investigated HCCAA-patients contained both L68Q- and wildtype cystatin C. The presence of approximately equal amounts of cystatin C dimers and monomers was demonstrated in plasma from HCCAA-patients, whereas only monomers could be found in normal plasma. L68Q-wildtype-cystatin C heterodimers seem to be present in the dimeric cystatin C population. CSF from six HCCAA-patients also contained cystatin C-dimers and monomers, but the dimeric fraction was minute. CSF from control patients did not contain dimeric cystatin C. These results suggest that the milieu of L68Q-cystatin C is important for its stability and dimerization status and that certain milieus might hinder its further development into oligomers, amyloid fibrils and other precipitating aggregates.

Progressive dementia and leucoencephalopathy as the initial presentation of late onset hereditary cystatin-C amyloidosis. Clinicopathological presentation of two cases.

Hereditary Cystatin-C Amyloidosis (HCCA) is a genetic disorder in Icelandic families in which a defective cystatin-C amyloid protein is deposited in the walls of small and middle sized arteries. Cerebral vessels are most affected, resulting in recurrent cerebral hemorrhages and infarctions, usually with onset of clinical symptoms in the twenties or thirties and a rapidly deteriorating clinical course. The disease can be diagnosed by a skin biopsy in symptomatic patients. We report two patients (father and daughter) who did not have a known family history of the disorder and presented late in life with a progressive dementia, associated with cerebral hemorrhages in the younger patient. Cerebral MRI and CT scans of this patient showed extensive leukoencephalopathic changes. Brain tissue samples from both patients showed immunohistochemical reaction to cystatin-C in small and medium-sized cerebral arteries and extensive cortical and white matter microinfarctions. The amyloid changes were less severe in the older patient and a colocation of beta-amyloid protein and cystatin-C was observed in addition to neurofibrillary tangles and senile plaques. Subcortical and cortical infarctions were also observed. HCCA may present late in life with progressive dementia as the only clinical manifestation, reflecting a multi-infarct syndrome secondary to the amyloidosis. A coexpression of cystatin-C and beta protein may occur as in other cerebral amyloid disorders, probably as age-specific changes.

Presence of non-fibrillar amyloid beta protein in skin biopsies of Alzheimer's disease (AD), Down's syndrome and non-AD normal persons.

A total of 66 skin biopsies from persons with Alzheimer's disease (AD) or Down's syndrome (DS) and from persons without AD were used in this study. The age range was from 7 to 89 years. Positive immunoreactivity of skin biopsies to monoclonal antibody 4G8, which is reactive to amino acid residue 17-24 of synthetic amyloid beta protein (A beta), and 4G8-Fab (the antigen-binding fragment of 4G8 IgG, reactive only to amyloid plaque) was observed in the epidermis-dermis junction or the basement membrane of the epidermis and in some blood vessels of the biopsy skins of 13/18 (72%) AD, 9/10 (90%) DS, and 14/38 (37%) non-AD control cases. The Fisher exact probability test revealed a significant difference (P = 0.0415 one-tailed) in immunoreactivity between AD and age-matched controls. There was also a significant difference (P = 0.0152 one-tailed; P = 0.0200 two-tailed) between DS and age-matched control in the same test. Immuno-gold electron microscopy examination of these cases with positive immunoreactivity revealed that the gold particles were deposited along the basement membrane of the epidermis. Amyloid fibrils were not observed in the regions with gold particles. Results of this study suggest that A beta is associated with the basement membrane of skin and is present in amorphous, non-fibrillar form as soluble A beta.

Tumours in Iceland. 15. Ependymoma. A clinicopathological and immunohistological study.

Thirteen ependymomas reported to the Icelandic Cancer Registry during a 32-year period (1955-1986) were histologically reviewed and reclassified according to the WHO Histological Typing of Tumours of the Central Nervous System. The annual incidence rate of ependymoma was 0.20/100.000. Clinical observations and data on biological behaviour and immunohistochemistry are presented. Four tumours were supratentorial, six infratentorial and three intraspinal. There were ten males and three females with a mean age of 32 years (range 2.5-68). The mean postoperative survival of nine surgically treated patients was 35.5 months. Histologically, eight tumours were classical ependymomas, three anaplastic and two myxopapillary. Of 11 tumours stained for GFAP, nine were positive. Nine of 10 tumours tested were positive for vimentin, five for NSE and four for S-100. None of the 10 tumours showed reactivity with AFP, CEA, chromogranin, desmin, factor VIII, keratin or neurofilament.

[Hereditary cerebral hemorrhage. Dementia with cystatin C amyloidosis]. / Hereditär hjärnblödning. Demens vid cystatin C amyloidos.

Nineteen cases of hereditary cystatin C amyloidosis with cerebral haemorrhage are described. The first haemorrhage occurred between the ages of 20 and 41 years and the period of survival varied from 10 days to 23 years after the first insult. Progressive dementia was a striking clinical symptom in 17 of the patients and in two cases dementia was the first sign. At the last examination severe dementia and pronounced pathological EEG were established in the majority of the patients. Infiltration of amyloid substance positive for anti-cystatin C was found in the proximity of the blood vessels and in their walls. Lesions in the cerebral microvascular system together with haemorrhages and infarcts caused thereby were considered to be an adequate explanation of the dementia in these patients. In view of the discovery of amyloid discharges in tissues outside the CNS it is adjudged more correct to use the name Hereditary Cystatin C Amyloidosis (HCCA).

Skin deposits in hereditary cystatin C amyloidosis.

Clinically normal skin from 47 individuals aged 9-70 years was investigated. Cystatin C amyloid deposits were found in various locations of the skin by light and/or electron microscopy, in all 12 patients with a clinical history of hereditary cystatin C amyloidosis (HCCA). Six asymptomatic individuals, who had the Alu 1 restriction fragment length polymorphism (RFLP) marker reported to cosegregate with the disease, also had cystatin C amyloid deposits in the skin. Three asymptomatic individuals (age 17-46) belonging to the HCCA families were without amyloid in the skin but had Alu 1 RFLP marker. Skin from 12 individuals who served as controls and skin from 14 close relatives of the patients was negative for amyloid. Punch biopsy of the skin is a simple procedure which is of value for the diagnosis of HCCA, even before the appearance of clinical symptoms. This method might also be of use in following progression of the disease.

Dementia in hereditary cystatin C amyloidosis.

Nineteen cases with verified Hereditary Cystatin C Amyloid Angiopathy are presented. All of the cases had one or more cerebrovascular insults starting at the age of 20-41 years and survived from 10 days to 23 years after the first insult. Progressive dementia was a prominent clinical feature in seventeen cases of whom two presented with dementia. At the last examination the majority had severe dementia and severely abnormal EEG. Anti-cystatin C positive amyloid vascular and perivascular infiltrates were found. The resulting damage to the microvasculature of the brain and secondary hemorrhages and infarctions were considered to be an adequate explanation for the dementia in these cases. Skin biopsies can now probably be used to demonstrate cystatin C positive amyloid deposits conclusively in the tissues of these patients.

Dementia with non-hereditary cystatin C angiopathy.

Brain biopsies from two patients with non-hereditary cerebral hemorrhages and eighty autopsied cases with the clinical diagnosis of dementia are presented. The biopsied cases, both males aged 64 and 59, had a sudden onset of cerebral hemorrhage, mild progressive dementia and cystatin C cerebral amyloid angiopathy. Of the autopsied cases 59 had senile plaques and cerebral amyloid angiopathy was also found in 36 of them. Both senile plaques and the blood vessel amyloid stained positively with beta-protein antibodies, and five of them also showed a positive reaction to cystatin C antibodies. These cystatin C positive cases were three males aged 76, 80 and 83, and one female 93 years old and the fifth case was a female aged 47 with Down's syndrome.

Hereditary cystatin C (gamma-trace) amyloid angiopathy of the CNS causing cerebral hemorrhage.

Hereditary CNS amyloid angiopathy occurring in Icelanders is the first human disorder known to be caused by deposition of cystatin C amyloid fibrils in the walls of the brain arteries leading to single or or multiple strokes with fatal outcome. One or more affected members have been verified by histological examination in 8 families containing 127 affected. These originated from the same geographic area. Abnormally low value of cystatin C found in the cerebrospinal fluid of those affected can be used to support or make diagnosis of this disease, also in asymptomatic relatives. By amino acid sequence analysis the amyloid fibrils in the patients are found to be a variant of cystatin C (gamma-trace), a major cysteine proteinase inhibitor. The variant protein has an amino acid substitution (glutamine for leucine) at position 58 in the amyloid molecule. It is postulated that a point mutation has occurred leading to production of amyloidogenic protein causing the disorder.

Immunohistochemical characterization of the amyloid deposits and quantitation of pertinent cerebrospinal fluid proteins in hereditary cerebral hemorrhage with amyloidosis.

Cystatin C, a protein inhibitor of lysosomal cysteine proteinases, was demonstrated by immunohistochemical techniques to be present in the birefringent amyloid deposits of the small arteries in the cerebrum, cerebellum, and leptomeninges of 10 Icelandic individuals with hereditary cerebral hemorrhage with amyloidosis. Specimens from other organs were investigated in one of the patients, and amyloid angiopathy characterized by an immunoreactivity of cystatin C was found in a submandibular lymph node. No immunoreactivity of amyloid fibril protein AA, kappa or lambda immunoglobulin light chain, or prealbumin was observed. Significantly low cerebrospinal fluid concentrations of cystatin C were found in all 9 investigated individuals with hereditary cerebral hemorrhage with amyloidosis. The concentrations of beta 2-microglobulin, albumin, and IgG in the cerebrospinal fluid were within normal limits. Isoelectric focusing showed that cystatin C from the cerebrospinal fluid of 9 patients with hereditary cerebral hemorrhage with amyloidosis had an isoelectric point identical to that of normal individuals. This investigation demonstrates that hereditary cerebral hemorrhage with amyloidosis may be diagnosed by two laboratory methods: immunohistochemical investigation of cystatin C in brain tissue specimens and quantitation of cystatin C in cerebrospinal fluid.