Differential expression of the amyloid SAA 3 gene in liver and peritoneal macrophages of mice undergoing dissimilar inflammatory episodes

The three active serum amyloid A (SAA) genes of mice, SAA 1, SAA 2, and SAA 3, are coordinately expressed in liver during acute and chronic inflammatory stimulation and experimental amyloidosis. The genes, primarily SAA 3, are also expressed extrahepatically. The apoprotein SAA 2 is the precursor of the amyloid A (AA) fibril protein that is deposited as insoluble fibrils extracellularly in spleen and other organs when amyloidosis occurs secondarily to inflammation. The exact cause of AA fibril formation is unknown. Amyloid enhancing factor is a high m.w. glycoprotein extracted from amyloidotic organs. Administration of amyloid enhancing factor alters experimental inflammation to bring about accelerated deposition of amyloid A fibrils first in spleen and later in other organs. In this study, hepatic and extrahepatic expression of the SAA genes were compared during accelerated amyloidosis relative to inflammation uncomplicated by amyloidosis. Differences in kinetics and pattern of SAA gene expression by resident peritoneal macrophages and liver were detected during four dissimilar inflammatory episodes. Macrophages expressed the SAA 3 gene solely, and to a greater extent in chronic than in acute inflammation. In accelerated amyloid induction, macrophage SAA 3 expression increased as SAA 1 and SAA 2 expression in liver decreased. However, alpha-1-acid glycoprotein expression remained elevated throughout the course of amyloid induction. The greatly increased expression of the SAA 3 gene by macrophages and decreased expression of the SAA 1 and SAA 2 genes in liver during amyloidosis, suggests that altered SAA gene expression may play a pathogenetic role in experimental amyloid deposition.

Differential expression of the amyloid SAA 3 gene in liver and peritoneal macrophages of mice undergoing dissimilar inflammatory episodes

The three active serum amyloid A (SAA) genes of mice, SAA 1, SAA 2, and SAA 3, are coordinately expressed in liver during acute and chronic inflammatory stimulation and experimental amyloidosis. The genes, primarily SAA 3, are also expressed extrahepatically. The apoprotein SAA 2 is the precursor of the amyloid A (AA) fibril protein that is deposited as insoluble fibrils extracellularly in spleen and other organs when amyloidosis occurs secondarily to inflammation. The exact cause of AA fibril formation is unknown. Amyloid enhancing factor is a high m.w. glycoprotein extracted from amyloidotic organs. Administration of amyloid enhancing factor alters experimental inflammation to bring about accelerated deposition of amyloid A fibrils first in spleen and later in other organs. In this study, hepatic and extrahepatic expression of the SAA genes were compared during accelerated amyloidosis relative to inflammation uncomplicated by amyloidosis. Differences in kinetics and pattern of SAA gene expression by resident peritoneal macrophages and liver were detected during four dissimilar inflammatory episodes. Macrophages expressed the SAA 3 gene solely, and to a greater extent in chronic than in acute inflammation. In accelerated amyloid induction, macrophage SAA 3 expression increased as SAA 1 and SAA 2 expression in liver decreased. However, alpha-1-acid glycoprotein expression remained elevated throughout the course of amyloid induction. The greatly increased expression of the SAA 3 gene by macrophages and decreased expression of the SAA 1 and SAA 2 genes in liver during amyloidosis, suggests that altered SAA gene expression may play a pathogenetic role in experimental amyloid deposition.

Plasma pharmacokinetics and urinary excretion of hexamethylene bisacetamide metabolites

In order to further understand the clinical toxicities of hexamethylene bisacetamide (HMBA) and to allow appropriate in vitro studies, we developed a suitable gas chromatographic assay and quantified plasma concentrations and urinary excretion of four metabolites which we had previously identified in urine of patients receiving 5-day HMBA infusions at 4.8-43.2 g/m2/day. 6-Acetamidohexanoic acid (AcHA) was the major plasma metabolite and reached steady state concentration (Css) by 24 h. AcHA Css increased from 0.12 +/- 0.02 (SD) mM at 4.8 g/m2/day to 0.72 mM at 43.2 g/m2/day. The Css AcHA:Css HMBA ratio decreased with increasing HMBA dosage. At dosages below 24 g/m2/day plasma Css of N-acetyl-1,6-diaminohexane (NADAH), the initial metabolite of HMBA, were below the limit of detection of our assay. With HMBA infusions of 24, 33.6, and 43.2 g/m2/day, Css of NADAH were 0.16 +/- 0.05, 0.14 +/- 0.06, and 0.19 +/- 0.04 mM, respectively. Css NADAH:Css HMBA ratios at 24, 33.6, and 43.2 g/m2/day were 0.18 +/- 0.06, 0.08 +/- 0.02, and 0.31 +/- 0.05, respectively. Plasma Css of 1,6-diaminohexane and 6-aminohexanoic acid were below the limit of detection of our assay. Each patient's urinary excretion of NADAH, AcHA, and 1,6-diaminohexane was consistent from day to day. The fraction of dose excreted in urine as AcHA was not affected by HMBA dosage and accounted for 12.7 +/- 3.9% of the daily dose. The percentage of daily HMBA dose accounted for by excretion of NADAH decreased with increasing HMBA dosage (10.8 +/- 6.0% at 4.8 g/m2/day to 4.2 +/- 1.2% at 33.6 g/m2/day). Urinary excretion of 1,6-diaminohexane always accounted for less than 3% of the daily dose. Our results indicate that: (a) plasma concentrations of AcHA alone cannot explain the degree of acidosis observed with toxic doses of HMBA; (b) NADAH is present in plasma at concentrations that we have found to cause differentiation in vitro; and (c) the probable rate-limiting step in HMBA metabolism is the initial deacetylation.

Production of an amino acid sequence-specific antiserum against human amyloid A (AA) and serum amyloid A (SAA) protein

The hydrophilic nonapeptide Ser-Asp-Ala-Arg-Glu-Asn-Ile-Gln-Arg, identical with residues 59-67 of human amyloid protein A (AA) and serum amyloid protein A (SAA), was covalently bound via its carboxyl-terminal end to the carrier-protein keyhole limpet haemocyanin. The complex was injected subcutaneously into ten rabbits. All rabbits produced antisera which, unabsorbed, were specific for AA and SAA. The antisera and their isolated peptide specific antibodies were performance-tested and found to be excellent for demonstration of AA and SAA in immunoblotting and immunohistochemical techniques but unsuitable for immunoprecipitation. Since it is difficult to produce AA- and SAA-specific antisera by procedures earlier described and commercial supplies of good such reagents are unavailable, the easy production of sequence-specific such antisera will facilitate more extended studies of the corresponding antigens for diagnostic and scientific purposes.

Hemodialysis-associated amyloidosis and beta-2 microglobulin. Clinical and immunohistochemical study

The beta-2 microglobulin type of amyloidosis was identified in articular and para-articular tissues of 14 patients with non-amyloid nephropathies undergoing long-term hemodialysis. Ten patients had carpal tunnel syndrome, 13 had juxta-articular radiolucent cysts (complicated by spontaneous fractures of the femoral neck in three), and six had destructive arthropathies of the large joints of the limbs. Massive amyloid deposits were found in the synovium, capsule, ligaments, articular cartilage, and/or bone. They were characterized by Congo red-induced green birefringence that was sensitive to potassium permanganate treatment. They reacted with anti-beta-2 microglobulin antiserum, whereas they did not react with antibodies directed against AA protein, prealbumin, or immunoglobulins. These data suggest that the potentially disabling arthropathy of hemodialysis is due to amyloid lesions. The persistently elevated plasma beta-2 microglobulin levels may play a role in the pathogenesis of this recently recognized complication, and if so, this complication should be preventable.

Lack of amyloid in abdominal fat aspirates from patients undergoing long-term hemodialysis

Recent reports describe the carpal tunnel syndrome (CTS) due to amyloid infiltration of the beta 2 microglobulin protein as a frequent complication of long-term hemodialysis. Carpal synovial and cystic bone lesion amyloid deposits have been reported; however, the extent of systemic amyloid deposition has not been determined. We examined 30 patients undergoing long-term hemodialysis for CTS and performed abdominal fat tissue aspiration for amyloid staining to evaluate the presence of systemic amyloid disease. In this group, CTS was frequent (37%) and its prevalence correlated with the duration of hemodialysis. In all patients, the abdominal fat tissue, stained with Congo red, was negative for amyloid deposits. These results confirm that CTS is a frequent complication of long-term hemodialysis; however, in this study, no detectable amyloid deposits were found in abdominal subcutaneous fat tissue. Thus, abdominal fat aspiration may not be a reliable screening test for hemodialysis-associated amyloidosis.

High-performance sodium dodecyl sulfate polyacrylamide gel capillary electrophoresis of peptides and proteins

High-performance capillary sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) has been developed for the separation and molecular weight (MW) determination of peptides and proteins. In this work, acrylamide was polymerized in fused-silica capillaries of 75 microns I.D. and 10 or 20 cm length. On-line UV detection was employed by placing the capillary in the optical path of the detector. Rapid separations of myoglobin fragments and of a mixture of standard proteins were demonstrated with efficiencies of the order of 40,000 plates for a column, 20 cm in length. Linear plots of log MW vs. mobility for the SDS protein complexes were observed. Variation in the percentage monomer composition (% T) of the polyacrylamide yielded the expected common intercept of log mobility vs. % T, confirming the size separation mechanism in the gel capillaries. The separation of the A and B chains of insulin with a 10-cm column in less than 10 min was also demonstrated.

Survival of patients with primary (AL) amyloidosis. Colchicine-treated cases from 1976 to 1983 compared with cases seen in previous years (1961 to 1973)

Primary amyloidosis has a variable course, but is generally associated with a short life expectancy. To date, no specific therapy has been available. Fifty-three patients with AL amyloidosis seen between 1976 and 1983 were treated with colchicine, and their clinical course and survival were compared with that in 29 other patients seen between 1961 and 1973. Of the variables measured, the treatment, the patient's sex, and the time interval from diagnosis to referral of treatment were significantly associated with length of survival. Median survival for the colchicine-treated patients was 17 months, compared with six months for the non-colchicine-treated patients. A surprising finding was the longer life span in female patients (median eight months versus four and a half months in the non-colchicine-treated group, and 25.5 months versus 10 month in the colchicine-treated group). The study suggests that colchicine has improved the life expectancy in AL amyloidosis. Although it is not a specific therapy, it may be a reasonable form of adjunctive treatment in this complex disorder.

Diagnosis of amyloidosis by abdominal fat aspiration. Analysis of four years' experience

Abdominal fat aspiration samples from 443 consecutive patients were examined for amyloid after Congo red and hematoxylin staining. Of the aspirates from 83 patients known to have systemic amyloid disease prior to the biopsy, 70 (84 percent) were found to yield positive results. The results for four aspirates from patients with localized amyloid disease were negative. Of the aspirates from 356 patients of unknown clinical status referred for analysis by outside physicians, 26 (7 percent) yielded positive results for amyloid. On review of the clinical records of these 26 patients, 11 had proved systemic amyloidosis demonstrated on biopsy of another site; all had a clinical course consistent with amyloid disease. In no case was amyloid found in a fat aspiration sample from a patient without clinical evidence suggestive of systemic amyloid disease. This study supports the proposal that abdominal fat aspiration is the diagnostic procedure of choice in the evaluation of amyloidosis since it requires no specialty consultation or technical expertise, causes minimal patient discomfort, and is accompanied by virtually no risk of morbid complication. A positive result has a high predictive value of amyloid disease in patients of unknown clinical status.

Sensitivity and specificity of the echocardiographic features of cardiac amyloidosis

Thirty-one patients with documented cardiac amyloidosis were compared to 39 control subjects with left ventricular hypertrophy to determine specific 2-dimensional echocardiographic features of amyloid. In 16 patients, increased myocardial echogenicity was present when a single short-axis view was examined, and had a sensitivity of 63% and a specificity of 74% for the diagnosis of amyloidosis. When complete echocardiograms were reviewed (15 patients), an improved sensitivity of 87% and specificity of 81% based on increased echogenicity was seen. Increased atrial septal thickness was present in 60% of amyloid patients and no controls. The combination of increased myocardial echogenicity and increased atrial thickness was 60% sensitive and 100% specific for the diagnosis of amyloidosis. The ratio of electrocardiographic voltage (S in V1 + R in V5 or V6) to left ventricular cross-sectional area also was examined. A ratio of less than 1.5 was 82% sensitive and 83% specific for amyloid (excluding the 2 patients with left bundle branch block), but added little to the diagnosis as determined from the 2-dimensional echocardiogram.

The induction of accelerated murine amyloid with human splenic extract. Probable role of amyloid enhancing factor

Amyloid enhancing factor (AEF) is derived from the tissues of pre-amyloidotic and amyloidotic animals and, when transferred, greatly accelerates amyloid induction in the recipient murine models. It has also been reported that similarly accelerated amyloid induction can be achieved in mice by injection of human splenic homogenates from patients with amyloidosis. The present study has attempted to characterize further the mechanism of this "heterologous transfer of amyloid". Treatment of mice with the "tissue homogenate" or the "AEF extract" of AA-, AL- and A prealbumin-laden human spleens followed by daily subcutaneous casein injections induced amyloidosis in an accelerated fashion. The resultant amyloid deposits in mice had strongly positive immunohistochemical reactions with anti-mouse AA, and negative reaction with anti-human AA or anti-human prealbumin. The results lend support to the idea that accelerated amyloid induction in the recipient mice is unlikely to be due to transfer of human amyloid substance, but rather to formation of "native" murine amyloid under the influence of a human AEF factor similar to or identical with AEF described in mouse-to mouse transfer models.

Renal amyloidosis. Evaluation by gallium imaging

A study has been performed to evaluate the efficacy of gallium imaging in the detection of renal amyloidosis. Ten of the 11 patients who had biopsy-proven renal amyloidosis demonstrated marked uptake in both kidneys. One patient revealed moderate gallium uptake in his kidneys. None of the patients had underlying renal or extrarenal pathology other than amyloidosis, which could account for renal gallium uptake (renal infection, neoplasm, hepatic failure or frequent blood transfusions). Four patients also had extrarenal foci of abnormal gallium uptake, suggesting other sites of amyloid deposits. Our data strongly suggest that gallium imaging has a high sensitivity for detection of renal amyloidosis. Its specificity is enhanced significantly by careful review of the clinical history to exclude other known causes of renal gallium uptake. Potentially, gallium imaging may be used to monitor the progress of patients under experimental therapy.

The association of an elastase with amyloid fibrils

The fibrils of all systemic forms of amyloid (primary, AL; secondary, AA; and hereditary, AF) that had been isolated by the water extraction procedure demonstrated elastolytic enzyme activity when examined in a specific assay using tritiated elastin. The source of this fibril-bound enzyme activity was consistent with human neutrophil elastase (HNE), since it was readily extracted by high salt solutions and inhibited by an elastase-specific chloromethyl ketone inhibitor, human alpha-1-protease inhibitor or by an antibody specific for HNE. The presence of an elastase on the amyloid fibril may suggest physiologic mechanisms of amyloid precursor protein degradation.

Isolation of the amyloid P component from the Engelbreth-Holm-Swarm (EHS) tumor of the mouse

The amyloid P component was isolated from the mouse EHS tumor, a producer of basement membrane-like material. Following collagenase treatment of the tissue homogenate and centrifugation, the supernatant was purified by calcium-dependent binding to agarose, and elution with ethylenediaminetetraacetic acid. Identification of the purified material as the amyloid P component was established by immunodiffusion and electron microscopic appearance as 8.5 nm pentagonal units, frequently assembled into columns. SDS-PAGE gel electrophoresis yielded 25,000 D bands, suggesting that the amyloid P is of the mouse type. It is proposed that the mouse amyloid P component extracted from the tumor is located within the basotubules present in the pericellular matrix.

Histochemical and immunohistochemical characterization of amyloid associated with chronic hemodialysis as beta 2-microglobulin

The carpal tunnel syndrome has been associated with amyloid deposits and is now regarded as a major complication in patients undergoing chronic hemodialysis. The hemodialysis-associated amyloidosis appears to have systemic rather than local involvement, although its full extent is yet to be determined. In an attempt to examine the chemical and immunologic nature of the amyloid, the authors carried out a series of histochemical and immunohistochemical studies with the following results. The amyloid was "sensitive" to the "permanganate treatment," suggesting it was the AA (secondary) type. On immunohistochemistry, however, anti-human AA did not give positive reaction with the amyloid deposits, suggesting that this would be a new form of amyloid. As reported elsewhere, the authors' preliminary results on the amino acid sequence analysis in one specimen have revealed homology of its amino terminal sequence to beta 2-microglobulin. In the present study, anti-beta 2-microglobulin did indeed react positively (with appropriate controls) with the amyloid deposits in the tissues collected from five different patients, confirming the beta 2-microglobulin-related nature of the amyloid. The present observations are significant in two points: (a) they confirm that hemodialysis-associated amyloid is of beta 2-microglobulin origin since it shares same antigenic determinant(s) with it and since the amino acid sequence is homologous; and (b) it adds what many have suspected, i.e., "permanganate-sensitive" amyloid is not specific for the AA type but includes AA and beta 2-microglobulin amyloid deposits at the minimum.

Serum amyloid A protein and C-reactive protein in systemic amyloidosis

In 106 patients with systemic amyloidosis (56 primary, 27 secondary, and 23 familial), serum amyloid A protein (SAA) was measured by solid-phase radioimmunoassay and C-reactive protein (CRP) was measured by rate nephelometry. SAA and CRP concentrations were highly correlated (r = 0.75, P less than 0.001) throughout the normal and abnormal concentration ranges. In systemic amyloidosis, SAA was more sensitive than CRP as an indicator of the acute-phase response, particularly in secondary amyloidosis. Acute-phase proteins are only occasionally increased during the course of familial amyloidosis. The overlap of acute-phase protein levels does not permit reliable separation of primary amyloidosis from secondary amyloidosis solely on the basis of such studies despite the significantly higher SAA and CRP levels in the latter.

In vitro formation of amyloid fibrils from intact beta 2-microglobulin

Prompted by the identification of hemodialysis-associated amyloid protein as beta 2-microglobulin, we attempted to create in vitro amyloid fibrils from the native protein. Beta 2-microglobulin in PBS was slowly dialyzed free of salt and then concentrated. The residue showed Congophilia with green birefringence by light microscopy and polarization, and non-branching fibrils of indeterminate length, measuring 8 to 10 nm in diameter by electron microscopy, thus meeting the morphologic criteria for amyloid. The present study demonstrates the first successful in vitro creation of amyloid fibrils with intact precursor protein molecules and provides supporting evidence that hemodialysis-associated amyloid is constituted from beta 2-microglobulin.

Isolation and characterization of a kappa amyloid fibril protein

The fibril in primary amyloidosis (AL) is composed of a monoclonal light chain or portions thereof. No unique primary structure has been identified that predisposes certain light chains to form amyloid fibrils. Currently, classification of amyloidosis is based on the biochemistry of the amyloid fibril. We determined the NH2-terminal sequence of an amyloid fibril and found it to be of the kappa I immunoglobulin subgroup. No structural alterations were detected to account for the conversion of the light-chain fragment to an amyloid fibril. Antiserum produced to the fibril protein did not react in immunodiffusion with purified LEP or MAG antigens, which are kappa I proteins. This antiserum may be directed to antigenic sites unique to the immunizing protein and is unable to recognize homologous proteins, rendering it unsuitable for immunochemical identification of amyloid deposits of light-chain origin. PAG represents the 10th reported variable kappa I amyloid fibril protein subjected to partial sequence analysis. Antisera that recognize antigenic determinants present in all members of an immunoglobulin subgroup need further development.

The clinical features of elderly-onset rheumatoid arthritis. A comparison with younger-onset disease of similar duration

Patients with elderly-onset rheumatoid arthritis (EORA) may represent a clinical subset of individuals who differ prognostically and therapeutically from patients with younger-onset disease (YORA). In order to test this hypothesis, we reviewed the records of 212 patients with rheumatoid arthritis and grouped them according to age at onset above or below 60 years old. Seventy-eight EORA patients and 134 YORA patients with disease duration of less than or equal to 10 years were used for a comparison of presenting features and disease outcome. Abrupt onset occurred somewhat more frequently in EORA, but was not associated with a significantly different clinical course than was an insidious presentation in this older group. There were no differences between the EORA and YORA groups in terms of mean initial joint score, although the scores for the YORA group had wider variation. An initial clinical presentation resembling polymyalgia rheumatica (PMR) was 4 times as frequent in EORA. Elderly patients were less likely to have subcutaneous nodules or rheumatoid factor at disease onset. At the final examination, the EORA patients had lower joint scores and higher health assessments despite similar courses of treatment. These outcome differences persisted when patients with PMR-like presentations were excluded. Multivariate analyses indicated that joint scores and disease duration made important contributions to a better outcome of EORA, whereas PMR presentation and abrupt onset did not. After an adjustment was made for these 4 features, age at onset was an important contribution to joint score outcome. These results confirm the existence of important differences in onset, clinical features, and prognosis between patients with EORA and those with YORA.

Esophageal manometry in familial amyloid polyneuropathy

The motility of the esophagus was studied by esophageal manometry in eight patients with familial amyloid polyneuropathy. All eight patients had an abnormality of the lower esophageal sphincter. Seven of eight had a borderline or decreased lower esophageal sphincter pressure and the other patient had a non-relaxing lower esophageal sphincter pressure. Six of eight patients had abnormalities of the body of the esophagus consisting of either simultaneous or decreased amplitude of contractions involving the smooth or striated muscle or both. In addition, seven of eight patients had diarrhea and six of these seven patients had evidence for steatorrhea. The manometric abnormalities observed were consistent with deposition of amyloid in smooth and striated muscle as well as in the enteric nervous system. Esophageal manometry appears to be a sensitive technique to determine if the gastrointestinal tract is involved in familial amyloid polyneuropathy.