Diagnosis of cerebral amyloid angiopathy by enzyme-linked immunosorbent assay of cystatin C in cerebrospinal fluid

The protective role of estrogen and its receptors in gentamicin-induced acute kidney injury in rats

AIM

Investigating the impact of 17β-Estradiol/estrogen receptors in gentamicin-induced nephrotoxicity.

MAIN METHODS

Three weeks post-ovariectomy or sham surgery for the Wistar albino female rats, thirty sham rats were randomly grouped (n = 6), received either vehicle or gentamicin; the estrogen receptors down regulator (fulvestrant); gentamicin plus fulvestrant; gentamicin plus the phytoestrogen (genistein). Forty-eight ovariectomized rats were randomly grouped (n = 6), treated with either vehicle or gentamicin; fulvestrant; gentamicin plus fulvestrant; genistein; gentamicin plus genistein; estradiol benzoate; gentamicin plus estradiol benzoate. Just post-treatment termination, the traditional kidney injury biomarkers (serum creatinine and blood urea nitrogen) and novel biomarkers (serum Kidney injury molecule -1, cystatin C, lactate dehydrogenase and, gamma-glutamyl transferase) were determined. Bovine serum albumin labeled with fluorescence isothiocyanate assessed megalin expression/endocytic functionality in the proximal tubules epithelial cells (PTECs). The immunohistochemical investigation for the same-sectioned slides of PTECs assessed the correlation between estrogen receptors α and megalin receptors expression. Histopathological examination of PTECs and subjective scoring system graded the damage markers.

KEY FINDINGS

Estrogen receptor α expression was markedly dimensioned post-ovariectomy, co-localized and inversely correlated to megalin expression. Serum levels of the novel biomarkers were directly proportional to megalin expression in the PTECs and inversely correlated with estrogen receptor α expression. The injury was exaggerated in ovariectomized and intact rats received fulvestrant. Supplementation with estrogen or genistein ameliorated this injury.

SIGNIFICANCE

Estrogen/estrogen receptors have a protective impact on gentamicin-induced acute kidney injury. Estrogen receptors antagonist exacerbate the injury, and oppositely, estrogens or phytoestrogens improve it.

An Improved Assay for Quantitation of Cerebrospinal Fluid Cystatin C Using Liquid Chromatography Tandem Mass Spectrometry

Cystatin C (CST3) is expressed ubiquitously and implicated in several neurological diseases. It can be posttranscriptionally modified. CST3 is usually quantified in a biological sample using antibody-based methods. Posttranscriptional modification can hamper antibody-based detection systems by altering antibody-binding epitope(s). To circumvent this problem, enzymatic digestion and liquid chromatography tandem mass spectrometry (LC-MS/MS) technique can be employed to identify and measure peptides of a target protein in a complex biological mixture. This chapter describes an LC-MS/MS-based method for accurate measurement of CST3 in cerebrospinal fluid (CSF). Here, CSF was directly subjected to trypsin digestion and digested peptides were extracted using a solid-phase extraction column. Extracted peptide samples were directly used for LC-MS/MS-based identification and quantification of CST3 peptides. Comparing the concentration in a set of samples measured by LC-MS/MS with that of immunoassay shows that it was significantly higher when measured by LC-MS/MS method, suggesting it a better quantification method. This approach is particularly well suited when posttranscriptional modification of CST3 is suspected and sample volume of CSF is small.

Quantification of CSF cystatin C using liquid chromatography tandem mass spectrometry

BACKGROUND

Cystatin C (CST3), a ubiquitously expressed cysteine protease inhibitor, is implicated in several neurological diseases. Here, we have developed an accurate CST3 measurement system based on liquid chromatography tandem mass spectrometry (LC-MS/MS).

METHODS

LC-MS/MS based measurement for CSF CST3 was validated by determination of assay precision, accuracy and recovery. The values were compared with those measured by immunoassay. Glycosylation of CST3 in CSF was analyzed by Western blotting and lectin blotting.

RESULTS

Measuring standard CST3 by LC-MS/MS produced a linear standard curve that correlated with assigned values (r²=0.99). Both intra- and inter-assay variation was <10%. Although showed a correlation, the average CST3 concentration measured by LC-MS/MS was significantly higher than that of immunoassay. Western blotting showed the presence of a 25KDa species along with CST3 monomer (14KDa) in CSF. The volume of 25KDa species was decreased by deglycosylation. Lectin blotting revealed a 25KDa glycosylated protein in sialidase-treated CSF, which was decreased by deglycosylation. However, deglycosylation did not alter CST3 concentration measured by immunoassay.

CONCLUSIONS

Our results suggest that LC-MS/MS-based CST3 measurement is a robust method with higher detection ability. Such method could be useful for the diagnosis and monitoring of neurological diseases.

Contribution of cystatin C gene polymorphisms to cerebral white matter lesions

BACKGROUND

Vascular remodeling plays an important role in the development of arteriosclerosis and any of the resulting white matter lesions in the brain. An imbalance between cysteine proteases and the cysteine protease inhibitor cystatin C (CST3) may exacerbate vascular remodeling through degradation of extracellular matrix proteins. Therefore, we evaluated the association between functional polymorphisms in the CST3 gene and the development of cerebral white matter lesions.

METHODS

In a total of 2,676 participants, 3 CST3 genepolymorphisms were genotyped in 92 cases with severe deep white matter hyperintensity (DWMH), and 184 subjects were randomly selected age- and sex-matched controls without any signs of DWMH. The genetic effects of these polymorphisms on DWMH and plasma CST3 levels were examined. CST3 expression vectors were transfected into an astrocytoma cell line and the expression level of CST3 mRNA was analyzed by quantitative RT-PCR. Intracellular and secreted levels of CST3 in the cell culture were quantified by Western blot and ELISA, respectively.

RESULTS

A significant association was found between one CST3 gene haplotype and DWMH (p = 0.002). This haplotype was also associated with lower plasma CST3 levels (p = 0.01). An in vitro transfection study revealed that the +148A allele, which is included in the risk haplotype, significantly reduced the secretion and increased the intracellular accumulation of CST3; however, it had no effect on the mRNA expression.

CONCLUSIONS

Our study shows that polymorphisms in the CST3 gene are significantly associated with the likelihood of DWMH. Substitution of A for G at +148 of the CST3 gene decreased the extracellular availability of CST3 in vitro, which might result in the activation of protease activity.

Cystatin C induces apoptosis and tyrosine hydroxylase gene expression through JNK-dependent pathway in neuronal cells

Cystatin C (CysC), an endogenous cysteine protease inhibitor, has been implicated in the apoptosis and differentiation processes of neuronal cells. In this study, we have investigated the pathway involved in the process. A human neuronal hybridoma cell line (A1 cell) was treated with CysC in both undifferentiated and retinoic acid (RA)-induced differentiated conditions, which decreased overall process length in both conditions. Also, CysC increased apoptotic cell number time-dependently, as revealed by TUNEL assay. Western blot analysis demonstrated that in differentiated A1 cells, CysC treatment decreased Bcl-2 and increased active caspase-9 protein level time-dependently. Immunocytochemistry results revealed that, CysC treatment significantly increased active form of Bax expressing cell number, which co-localized with mitochondria. Mitogen activated protein (MAP) kinase inhibition experiments showed that Bax mRNA induction and Bcl-2 mRNA inhibition by CysC treatment were c-Jun N-terminal kinase (JNK)-dependent. After RA-induced differentiation, choline acetyltransferase (ChAT) and neurofilament (NF) mRNA levels were increased in A1 cells. CysC treatment inhibited NF mRNA level in both undifferentiated and RA-differentiated, and increased TH mRNA in differentiated A1 neurons. Analysis of signal transduction pathway demonstrated that TH gene induction was also JNK-dependent. Thus, our results demonstrated the significance of JNK-dependent pathways on CysC-induced apoptosis and TH gene expression in neuronal cells, which might be an important target in the management of CysC dependent neurodegenerative processes.

Cystatin C expression in ischemic white matter lesions

OBJECTIVES

To study the involvement of cystatin C in the progression of ischemic white matter lesions (WMLs).

MATERIALS AND METHODS

Cystatin C levels in the cerebrospinal fluid (CSF) of patients with cerebrovascular disease, and also in primary and established human neural cell cultures were investigated. For pathologic analysis, cystatin C immunoreactivity was investigated in the white matter of patients with severe WMLs, mild WMLs or controls.

RESULTS

Cystatin C levels in the CSF of patients with Fazekas WML grade 3 [14 with hypertension; W/HT(+) and nine without hypertension; W/HT(-)] were lower than those in 38 patients with grade 0-1 (P = 0.0022 and P < 0.0001 respectively). Immunohistochemical study showed that the cystatin C immunoreactivity was found in astrocytes, and the number of astrocytes in the white matter in the severe WML group was decreased when compared with that in controls (P = 0.0027) and in the mild WML group (P = 0.0024). In human neural cell cultures, treatments with thrombin, matrix metalloproteinases and interleukin 1 beta increased the expression of cystatin C mRNA in human astrocytes and hybrid neurons, but an enzyme-linked immunosorbent assay revealed that only thrombin significantly increased the production and secretion of cystatin C in astrocytes.

CONCLUSIONS

These results suggest that low levels of CSF cystatin C in ischemic WMLs might be due to the decreased number of astrocytes that secrete cystatin C in response to the stimuli of proteases and inflammatory cytokines.

Neuronal cell death induced by cystatin C in vivo and in cultured human CNS neurons is inhibited with cathepsin B

Cystatin C, a cysteine protease inhibitor, is implicated in pathogenesis of late-onset Alzheimer's disease and other neurological disorders. Our recent study showed that cystatin C injection into rat hippocampus induced neuronal cell death in granule cell layer of dentate gyrus in vivo. We further confirmed that cystatin C neurotoxicity was inhibited by simultaneous coapplication of cathepsin B, a cysteine protease. In vitro cytotoxicity was also studied in cultures of human CNS neurons, mixed cultures with astrocytes and A1 human hybrid neurons. Cystatin C induced neuronal cell death in a dose-dependent manner, which accompanied increased number of TUNEL (+) cells, up-regulation of active caspase-3 and DNA ladder. The results of the present study indicate that cystatin C participates in the process of apoptotic neuronal cell death in experimental conditions by means of inhibitory activity of cysteine proteases, and that cystatin C might be involved in the pathogenesis in human neurological disorders including Alzheimer's disease.

Relationship between matrix metalloproteinase-2 activity and cystatin C levels in patients with hepatic disease

OBJECTIVES

A direct relationship between cystatin C levels and the severity of hepatic disease has been revealed in our previous study. This study was aimed to consider whether a correlation exists between matrix metalloproteinases (MMPs), which have been proven to be involved in liver cirrhosis, and cystatin C to reflect the severity of hepatic disease.

DESIGN AND METHODS

A total of 154 consecutive patients with various liver diseases were recruited to determine their serum levels of cystatin C, MMP-2 and-9, together with other hepatic parameters. These were compared with 40 normal controls.

RESULTS

Average levels of MMP-2 and cystatin C were significantly higher in patients while MMP-9 was significantly lower, as compared to controls. A linear regression analysis has revealed a direct relationship between cystatin C and MMP-2 (Y=83.39 + 270.56 X, R=0.38, P< 0.001), as well as between MMP-2 and the severity of liver diseases.

CONCLUSION

This is the first study to demonstrate a correlation between cystatin C and MMP-2, suggesting that there may be certain interactions between cystatin C and MMP-2 in patients with hepatic diseases.

Comparative proteomic analysis of human whole saliva

Human saliva performs a wide variety of biological functions that are critical for the maintenance of the oral health. Various functions include lubrication, buffering, antimicrobial protection, and the maintenance of mucosal integrity. In addition, whole saliva may be analysed for the diagnosis of human systemic diseases, since it can be readily collected and contains identifiable serum constituents. By using proteomic approach, we have established a reference proteome map of human whole saliva allowing for the resolution of greater than 200 protein spots in a single two-dimensional polyacrylamide gel. Fifty-four protein spots, comprised of 26 different proteins, were identifies using N-terminal sequencing, mass spectrometry, and/or computer matching with protein database. Ten proteins, whose levels were significantly different when bleeding had occurred in the oral cavity, were discussed in this study. These 10 proteins include alpha-1-antrypsin, apolipoprotein A-I, cystatin A, SA, SA-III, and SN, enolase I, hemoglobin beta-chain, thioredoxin peroxiredoxin B, as well as a prolactin-inducible protein. The proteomic approach identifies candidates from human whole saliva that may prove to be of diagnostic and therapeutic significance.

Serum cystatin C in patients with head and neck carcinoma

BACKGROUND

The balance between proteinases of various classes and their inhibitors was found to be of critical importance for local invasion and metastasizing of tumor cells. The aim of the present study was to determine the changes in the serum cystatin C concentration in patients with squamous cell carcinoma of the head and neck.

METHODS

In the sera of 34 patients with squamous cell carcinoma of the head and neck, the concentration of cysteine proteinase inhibitor cystatin C was determined using ELISA. The serum samples were collected at diagnosis (group A) and 7 to 407 days (median, 59 days) after the therapy (group B). The sera of 30 healthy blood donors served as controls (group C).

RESULTS

A significant increase in the median concentration of cystatin C was found in the patients' sera (group A: 573 ng/ml, P<0.0001; group B: 551 ng/ml, P<0.0001) compared to control group C (320 ng/ml), whereas no difference was observed between groups A and B (P>0.05). Cystatin C concentrations in the sera of group A correlated with the site of primary tumor (P=0.035), being higher in the patients with non-laryngeal tumors (658 ng/ml) than in those with larynx primaries (529 ng/ml). There was a significant trend (RS=-0.535, P=0.049) towards lower cystatin C concentrations with an increasing time delay in post-treatment serum sampling (group B), which was observed in the patients with no relapse of the disease and a sampling later than 45 days after the completion of therapy.

CONCLUSIONS

These results add to the knowledge of the role of cystatin C in invasive behavior of squamous cell carcinoma of the head and neck, and suggest its potential role as a tumor marker in this particular type of cancer.

Increased cystatin C serum concentrations in patients with hepatic diseases of various severities

BACKGROUND

Indicators for long-term monitor of the progress of hepatic diseases are of great clinical importance. Since elevated cathepsin was observed in liver diseases, the aim of this study is to investigate the involvement of cystatin C, a very potent inhibitor of cathepsin and a recently introduced marker for renal function, and to see the applicability of serum cystatin C being a convenient marker for the progression of liver diseases.

METHODS

One hundred eighty consecutive patients with chronic liver disease of various severities and 45 healthy controls were recruited to determine their serum cystatin C concentrations by N Latex Cystatin C kit, as well as certain relevant clinical values, including alanine transaminase (ALT), aspartate transaminase (AST) and AFP.

RESULTS

Average serum cystatin C concentration of patients with hepatic diseases was significantly higher than that of control (0.0902+/-0.0025 mg/dl vs. 0.067+/-0.007 mg/dl; p<0.001), and a linear regression analysis has revealed a direct relation between cystatin C and the severity of liver diseases (Y=1.172+5.492X, R(2)=0.088, p<0.001).

CONCLUSION

This study suggested that cystatin C may be an applicable monitoring marker for monitoring liver functions and progression of liver fibrosis.

Cathepsin B and H activities and cystatin C concentrations in cerebrospinal fluid from patients with leptomeningeal metastasis

BACKGROUND

Cysteine proteases are involved in the extension of cancer into the subarachnoid space. The presence of cathepsins B and H along with their potent inhibitor cystatin C in the cerebrospinal fluid (CSF) was investigated in patients with leptomeningeal metastasis of cancer (LM).

MATERIALS AND METHODS

CSF samples were obtained in 16 cases of LM (10 solid tumors and 6 leukemia or lymphoma) and compared with 11 cancer cases without involvement of the central nervous system, 12 multiple sclerosis cases and 34 healthy volunteers. The activity of the enzymes was measured, their molecular forms were analyzed by the Western blotting, and the concentration of cystatin C was measured by ELISA. Immunohistochemistry of the leptomeningeal tissues was also performed in six autopsy cases of LM.

RESULTS

High activities of cathepsins B and H along with decreased cystatin C concentration were observed in CSF of LM as compared with three control groups. Western blot analysis revealed higher concentration of the enzyme protein as well as its active forms in samples with higher enzyme activity. Cells metastasizing leptomeningeal tissue were clearly positive in immunohistochemical staining of cathepsins, indicating active production by tumor cells.

CONCLUSION

Production of cathepsins B and H by tumor cells and their high activity along with concomitant decrease of their potent inhibitor, cystatin C, in the CSF might contribute in the process of metastasis and spread of the cancer cells in the leptomeningeal tissues. A high enzyme activity/cystatin C concentration ratio in the CSF could be useful when diagnosing LM in combination with other parameters.

Cerebral amyloid angiopathy associated with hemorrhage: immunohistochemical study of 41 biopsy cases

The relationship between cerebral amyloid angiopathy and hemorrhage was investigated by an immunohistochemical study of biopsy cases to characterize the involvement of amyloid beta-protein, apolipoprotein E, and cystatin C in cerebral amyloid angiopathy associated with hemorrhage. The amyloid-laden vessels were examined in biopsy specimens from 41 surgical cases of sporadic cerebral amyloid angiopathy (36 cases with hemorrhage and 5 cases without hemorrhage), using immunohistochemical staining with antibodies against amyloid beta-protein, apolipoprotein E, cystatin C, and alpha-smooth muscle actin. The relationship between the occurrence, recurrence, and enlargement of the hemorrhage, and the semiquantitative estimation of the cerebrovascular amyloid-related protein deposition was analyzed using Fisher's exact test. Severe amyloid beta-protein (p < 0.013) and apolipoprotein E (p < 0.013) immunoreactivity were risk factors for the occurrence of the hemorrhage. Severe cystatin C immunoreactivity was a risk factor for the occurrence (p < 0.002) and enlargement (p < 0.014) of the hemorrhage, and tended to induce recurrent hemorrhage (p < 0.103). In addition, loss of the vascular smooth muscle was observed in the intensely amyloid-laden vascular walls that showed cystatin C-immunoreactivity. The present study indicates that intense amyloid beta-protein deposition with cystatin C deposition weakens the cerebrovascular walls, and that cystatin C deposition is a strong predictor of hemorrhage in cerebral amyloid angiopathy.

Elevation of serum cystatin C concentrations in patients with chronic liver disease

OBJECTIVE

We examined serum cystatin C concentrations in patients to explore the possible clinical application of cystatin C as a marker of disease severity in cases of chronic liver diseases.

METHODS

Serum cystatin C concentrations were determined by an enzyme-linked immunosorbent assay kit in 103 patients with various chronic liver diseases and compared with concentrations in healthy control volunteers.

RESULTS

The mean cystatin C concentration was 0.68 +/- 0.03 mg/l in chronic hepatitis patients, 1.13 +/- 0.09 mg/l in liver cirrhosis patients and 1.16 +/- 0.10 mg/l in hepatocellular carcinoma patients, all significantly higher than concentrations in the control volunteers (P < 0.0001). Significant correlations were observed between cystatin C concentrations and total bilirubin levels, albumin levels, platelet levels, type IV collagen levels and hyaluronic acid levels. Serum cystatin C concentrations correlated well with histological stages despite the lack of correlation with histological grades.

CONCLUSION

Our results show that serum cystatin C increases with the progression of chronic liver disease and that it is a potential marker for liver fibrosis.

Serum cystatin C, a potent inhibitor of cysteine proteinases, is elevated in asthmatic patients

The effect of asthma pathogenesis on serum cystatin C, a potent inhibitor of cysteine proteinases and a newly proposed marker of the renal function, has not been yet determined. The objectives were to determine the 24-h pattern of cystatin C and creatinine concentrations in sera of asthmatic patients in order to test whether their concentrations might reflect circadian rhythms, the disease severity and the effect of therapy. Serum concentrations of cystatin C and creatinine were determined in steroid-independent and steroid-dependent asthmatics before and after 1 week of treatment with methylprednisolone and cyclosporin A, respectively. Samples were collected every 4 h during a 24-h period. Little or no significant effects of time on cystatin C and creatinine concentrations over a 24-h period were observed in healthy and asthmatic sera. However, significantly higher cystatin C concentrations were found in asthmatic patients compared to controls which suggests its role in the pathogenesis of asthma. Methylprednisolone increased and cyclosporin A decreased serum cystatin C concentrations after 1 week of therapy. Additionally these results support the need for the evaluation of cystatin C as a marker of glomerular filtration rate determination in asthma.

Cerebral amyloid angiopathy: an overview

Cerebral amyloid angiopathy (CAA) is characterized by amyloid deposition in cortical and leptomeningeal vessels. Several cerebrovascular amyloid proteins (amyloid beta-protein (Abeta), cystatin C (ACys), prion protein (AScr), transthyretin (ATTR), gelsolin (AGel), and ABri (or A-WD)) have been identified, leading to the classification of several types of CAA. Sporadic CAA of Abeta type is commonly found in elderly individuals and patients with Alzheimer's disease. Cerebral amyloid angiopathy is an important cause of cerebrovascular disorders including lobar cerebral hemorrhage, leukoencephalopathy, and small cortical hemorrhage and infarction. We review the clinicopathological and molecular aspects of CAA and discuss the pathogenesis of CAA with future perspectives.

Cystatin C--properties and use as diagnostic marker

This chapter focuses on the most well characterized inhibitors—cystatin C—and provide some information on its structure, biochemical properties, its role in normal and abnormal physiological processes, as well as on its use as a diagnostic marker. A major part of the cysteine proteases are evolutionary related to the structurally well–defined cysteine protease papain and are called papain–like cysteine proteases. The biological roles and the cystatin superfamily inhibitors of papain–like cystein proteases are also discussed. The aminoacid sequence and schematic structure of human cystatin C is also presented. The evolutionary relationships among all known inhibitory active human cystatins and kininogen cystatin domains are diagrammatically represented. The distribution of cystatins in body fluids and additional functions attributed to cystatin C are described. The serum or plasma cystatin C is used as a marker for glomerular filtration rate (GFR). The urine cystatin C is used as a marker for proximal tubular damage. The two types of brain hemorrhage associated with Cystatin C amyloid deposits are also demonstrated. The conditions connected with deposition of amyloid β–protein in cystatin C and cerebral hemorrhage is also provided.

Cystatin C deficiency in human atherosclerosis and aortic aneurysms

The pathogenesis of atherosclerosis and abdominal aortic aneurysm involves breakdown of the elastic laminae. Elastolytic cysteine proteases, including cathepsins S and K, are overexpressed at sites of arterial elastin damage, but whether endogenous local inhibitors counterbalance these proteases is unknown. We show here that, whereas cystatin C is normally expressed in vascular wall smooth muscle cells (SMCs), this cysteine protease inhibitor is severely reduced in both atherosclerotic and aneurysmal aortic lesions. Furthermore, increased abdominal aortic diameter among 122 patients screened by ultrasonography correlated inversely with serum cystatin C levels. In vitro, cytokine-stimulated vascular SMCs secrete cathepsins, whose elastolytic activity could be blocked when cystatin C secretion was induced by treatment with TGF-beta(1). The findings highlight a potentially important role for imbalance between cysteine proteases and cystatin C in arterial wall remodeling and establish that cystatin C deficiency occurs in vascular disease.

Instability of the amyloidogenic cystatin C variant of hereditary cerebral hemorrhage with amyloidosis, Icelandic type

A cystatin C variant with L68Q substitution and a truncation of 10 NH2-terminal residues is the major constituent of the amyloid deposited in the cerebral vasculature of patients with the Icelandic form of hereditary cerebral hemorrhage with amyloidosis (HCHWA-I). Variant and wild type cystatin C production, processing, secretion, and clearance were studied in human cell lines stably overexpressing the cystatin C genes. Immunoblot and mass spectrometry analyses demonstrated monomeric cystatin C in cell homogenates and culture media. While cystatin C formed concentration-dependent dimers, the HCHWA-I variant dimerized at lower concentrations than the wild type protein. Amino-terminal sequence analysis revealed that the variant and normal proteins produced and secreted are the full-length cystatin C. Pulse-chase experiments demonstrated similar levels of normal and variant cystatin C production and secretion. However, the secreted variant cystatin C exhibited an increased susceptibility to a serine protease in conditioned media and in human cerebrospinal fluid, explaining its depletion from the cerebrospinal fluid of HCHWA-I patients. Thus, the amino acid substitution may induce unstable cystatin C with intact inhibitory activity and predisposition to self-aggregation and amyloid fibril formation.

No mutations in cystatin C gene in cerebral amyloid angiopathy with cystatin C deposition

To investigate the relationship between cerebral amyloid angiopathy (CAA) and cystatin C, we studied five CAA patients on whose cerebral blood vessels colocalization of cystatin C and beta-protein was recognized immunohistochemically. One patient was suspected as familial CAA and the other patients were sporadic cases. Two patients had low concentration of cystatin C in their cerebrospinal fluid (CSF) as we have previously reported in CAA patients. Enzyme-linked immunosorbent assay (ELISA) revealed that cystatin C and beta-protein have been included at the ratio of about 1:100 in the crude amyloid fibrils of one patient. Using a monoclonal antibody (MAb) against cystatin C, we performed affinity chromatography and immunoblotting on her amyloid fibril fraction. Eluate showed a band with a mol wt of 14,000 and the N-terminal 14 amino acid residues of 14-kDa protein were identical with that of cystatin C. This molecular weight is not identical to that of the truncated form of cystatin C deposited in hereditary cerebral hemorrhage with amyloidosis in Iceland (HCHWA-I), but that of normal cystatin C. DNA sequence analysis of five patients showed no point mutations in the cystatin C gene. Cystatin C and beta-protein colocalization, which was recognized in amyloid lesions of CAA, suggests that cystatin C deposition may be related to beta-protein deposition. We hypothesize that cystatin C deposition in sporadic cerebral amyloid angiopathy with cystatin C deposition (SCCAA) involves a different mechanism from that in HCHWA-I, which may be related to low CSF concentration of cystatin C without amino acid substitutions.

Animal models of cerebral beta-amyloid angiopathy

Cerebral amyloid angiopathy (CAA) is a significant risk factor for hemorrhagic stroke in the elderly, and occurs as a sporadic disorder, as a frequent component of Alzheimer's disease, and in several rare, hereditary conditions. The most common type of amyloid found in the vasculature of the brain is beta-amyloid (A beta), the same peptide that occurs in senile plaques. A paucity of animal models has hindered the experimental analysis of CAA. Several transgenic mouse models of cerebral beta-amyloidosis have now been reported, but only one appears to develop significant cerebrovascular amyloid. However, well-characterized models of naturally occurring CAA, particularly aged dogs and non-human primates, have contributed unique insights into the biology of vascular amyloid in recent years. Some non-human primate species have a predilection for developing CAA; the squirrel monkey (Saimiri sciureus), for example, is particularly likely to manifest beta-amyloid deposition in the cerebral blood vessels with age, whereas the rhesus monkey (Macaca mulatta) develops more abundant parenchymal amyloid. These animals have been used to test in vivo beta-amyloid labeling strategies with monoclonal antibodies and radiolabeled A beta. Species-differences in the predominant site of A beta deposition also can be exploited to evaluate factors that direct amyloid selectively to a particular tissue compartment of the brain. For example, the cysteine protease inhibitor, cystatin C, in squirrel monkeys has an amino acid substitution that is similar to the mutant substitution found in some humans with a hereditary form of cystatin C amyloid angiopathy, possibly explaining the predisposition of squirrel monkeys to CAA. The existing animal models have shown considerable utility in deciphering the pathobiology of CAA, and in testing strategies that could be used to diagnose and treat this disorder in humans.

Simultaneous multiple brain hemorrhage associated with migraine--a case report

A fifty-five-year-old woman with a history of migraine suddenly developed an occipital headache and visual disturbance after a typical migrainous attack. On admission, she had a left homonymous hemianopsia, and computed tomography of the brain demonstrated intracranial hematomas in the occipital subcortices bilaterally. Cerebral arteriography revealed diffuse vasospasm of the intracranial arteries attributed to the migraine. The cystatin C concentration in the cerebrospinal fluid was low, which suggested the existence of cerebral amyloid angiopathy. According to the clinical course and angiographic findings, it is suggested that the vasospasm associated with migraine played an important role in developing multiple brain hemorrhage in this patient.

Cerebral amyloid angiopathy. A review

Cerebral amyloid angiopathy (CAA) is a condition characterized by amyloid deposition in cerebral blood vessels. It occurs most frequently in association with clinical Alzheimer's disease but also occurs in some nondemented elderly people. CAA is a cause of spontaneous cerebral hemorrhage and may therefore present as a sudden unexpected death in an elderly person. The amyloid is deposited in cortical blood vessels, and on hematoxylin-eosin sections takes the form of pink hyaline thickening of arteries and arterioles, often with narrowing of the lumina. For diagnosis apple-green birefringence after Congo red staining is the most widely practiced and reliable tool. CAA-related hemorrhage may also occur in any lobe of the cerebrum close to the external surface and may occur at multiple sites and at the same or different times. CAA-related hemorrhage may occur in the setting of trauma necessitating distinction between the two and raising the question of whether it precipitated trauma or vice versa. Usually CAA-related hemorrhage is infrequent in sites where traumatic hemorrhages occur, and traumatic hemorrhages are often associated with other hemorrhages in sites typical for trauma. Five cases demonstrating many of the clinical and pathological features of CAA-related hemorrhage are presented. In two of the five cases, the hemorrhage followed trauma, suggesting that trauma as a precipitating factor for CAA-related hemorrhage may be more common than is generally recognized. CAA-associated hemorrhage should be considered in the differential diagnosis of cerebral hemorrhage in the elderly whether or not dementia is present.

Brain parenchymal and microvascular amyloid in Alzheimer's disease

Brains of patients with Alzheimer disease/senile dementia of Alzheimer type (AD/SDAT) develop a progressive accumulation of amyloid, which deposits primarily in the form of characteristic parenchymal 'plaques' (senile or neuritic plaques/SP's) and as mural deposits in the walls of capillaries and arterioles (cerebral amyloid angiopathy /CAA). A major component of this amyloid is a small and unique peptide composed of 39-43 amino acids, beta/A4, which is cleaved from a much larger precursor protein (APP) that has several isoforms. Brain amyloid can be detected in autopsy or biopsy brain tissue by classical, immunohistochemical and ultrastructural (including immuno-electron microscopic) methods of varying sensitivity and specificity. Beta/A4 amyloid deposition is remarkably variable (e.g. predominantly parenchymal or vascular, or a mixture of parenchymal and vascular) among patients with AD/SDAT. Despite its abundance in the brains of AD/SDAT patients, the precise role of beta/A4 in the pathogenesis of the neurological deficit, neocortical atrophy and progressive synapse loss associated with AD/SDAT has yet to be determined. However, mutations in the gene that encodes APP are clearly associated with familial AD syndromes in which there is significant brain amyloid deposition. CAA, in addition to its association with AD/SDAT, can result in hemorrhagic and (possibly) ischemic forms of stroke. Work with recently developed transgenic mice which express large amounts of beta/A4 in the central nervous system is likely to elucidate mechanisms by which the protein is selectively or deposited in the brain in a parenchymal or microvascular form, and how it contributes to the pathogenesis of neurodegeneration.

Co-localization of beta/A4 and cystatin C in cortical blood vessels in Dutch, but not in Icelandic hereditary cerebral hemorrhage with amyloidosis

Based on the recent discovery of co-localization of beta/A4 and cystatin C in cortical blood vessels of patients with cerebral hemorrhages due to sporadic amyloid angiopathy and patients with Alzheimer's disease we investigated the presence of these two proteins in the cortical blood vessels of patients suffering from hereditary cerebral hemorrhage with amyloidosis of the Dutch (n = 11) and the Icelandic (n = 2) type. The brains of three patients with sporadic cerebral amyloid angiopathy were also investigated. Blood vessels of the Dutch patients clearly showed immunostaining with beta/A4 as well as with cystatin C antibodies, whereas the blood vessels of Icelandic patients showed only staining with cystatin C. In one of the three sporadic amyloid angiopathy patients co-localization was shown as well. The co-localization of mutated beta/A4 with normal cystatin C in the Dutch patients suggests that cystatin C deposition occurs secondarily to beta/A4 deposition. This is probably also the case in sporadic amyloid angiopathy and Alzheimer's disease. Cystatin C deposition may play a role in the development of cerebral hemorrhages and leukoencephalopathy.