The assessment of elderly black patients with unexplained heart disease should include a consideration of transthyretin amyloidosis, particularly that related to the Ile 122 allele.

Monoclonal immunoglobulin deposition occurs in tissues as Congo Red binding fibrils in light chain amyloidosis, as less structured deposits in light chain deposition disease, and as similar but distinct deposits in light and heavy chain deposition disease. The nonamyloid forms were found in 13 patients who had evidence of plasmacytic dyscrasia by the immunohistochemical detection of immunoglobulin light chains of kappa or lambda class (with or without staining for a single heavy chain isotype) and by the absence of amyloid P component in tissue sections that did not show the birefringence characteristic of amyloid after Congo Red staining. All but two of the patients presented with proteinuria with or without azotemia. Clinical syndromes involving other organ systems were less common but occasionally severe. Four patients had overt multiple myeloma. Three others had hypercalcemia and mild bone marrow plasmacytosis but no lytic lesions. Analyses of immunoglobulin synthesis in bone marrow cells from seven patients showed excess light chains in all and incomplete light chains or heavy chain fragments in six, regardless of whether an intact monoclonal protein or related subunit was in the serum or urine. The fibrillar (amyloidotic) and nonfibrillar forms of monoclonal immunoglobulin deposition occur either in overt multiple myeloma or in the course of less neoplastically aggressive plasmacytic dyscrasias. Bone marrow cells from patients with either type produce immunoglobulin fragments that are related to those deposited in the affected tissues.

Immunohistochemical analysis of brains of patients with Alzheimer disease (AD) revealed that the cysteine proteinase inhibitor cystatin C colocalizes with amyloid beta-protein (Abeta) in parenchymal and vascular amyloid deposits. No evidence of cerebral hemorrhage was observed in any of the brains studied. Immunoelectron microscopy demonstrated dual staining of amyloid fibrils with anti-Abeta and anti-cystatin C antibodies. Cystatin C immunoreactivity was also observed in amyloid deposits in the brain of transgenic mice overexpressing human beta amyloid precursor protein. Massive deposition of the variant cystatin C in the cerebral vessels of patients with the Icelandic form of hereditary cerebral hemorrhage with amyloidosis is thought to be responsible for the pathological processes leading to stroke. Anti-cystatin C antibodies strongly labeled pyramidal neurons within cortical layers most prone to amyloid deposition in the brains of AD patients. Immunohistochemistry with antibodies against the carboxyl-terminus of Abeta(x-42) showed intracellular immunoreactivity in the same neuronal subpopulation. It remains to be established whether the association of cystatin C to Abeta plays a primary role in amyloidogenesis of AD or is a late event in which the protein is bound to the previously formed Abeta amyloid fibrils.

Administration of the aromatic polycyclic dione compounds hypericin or pseudohypericin to experimental animals provides protection from disease induced by retroviruses that give rise to acute, as well as slowly progressive, diseases. For example, survival from Friend virus-induced leukemia is significantly prolonged by both compounds, with hypericin showing the greater potency. Viremia induced by LP-BM5 murine immunodeficiency virus is markedly suppressed after infrequent dosage of either substance. These compounds affect the retroviral infection and replication cycle at least at two different points: (i) Assembly or processing of intact virions from infected cells was shown to be affected by hypericin. Electron microscopy of hypericin-treated, virusproducing cells revealed the production of particles containing immature or abnormally assembled cores, suggesting the compounds may interfere with processing of gag-encoded precursor polyproteins. The released virions contain no detectable activity of reverse transcriptase. (ii) Hypericin and pseudohypericin also directly inactivate mature and properly assembled retroviruses as determined by assays for reverse transcriptase and infectivity. Accumulating data from our laboratories suggest that these compounds inhibit retroviruses by unconventional mechanisms and that the potential therapeutic value of hypericin and pseudohypericin should be explored in diseases such as AIDS.We recently reported (1) that two naturally occurring polycyclic aromatic diones, hypericin and pseudohypericin, possess antiretroviral activity. The two compounds, which are derived from the plants of the Hypericum genus (St. Johnswort) (2-5), markedly suppress the spread of murine retrovirus infections both in vivo and in vitro (1). We have now compared the mechanisms of action and the therapeutic potentials of different doses of these agents in two murine retroviral systems. In the Friend virus system (6-8) the compounds can preclude the onset of acute Friend virusinduced erythroleukemia. In the other system a more slowly progressing, fatal form of murine immunodeficiency is induced by the LP-BM5 virus (9, 10); hypericin and pseudohypericin prevent development of significant viremia and minimize disease in mice infected with the LP-BM5 virus.

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SUMMARY:The human serum protein transthyretin (TTR) is highly fibrillogenic in vitro and is the fibril precursor in both autosomal dominant (familial amyloidotic polyneuropathy [FAP] and familial amyloidotic cardiomyopathy [FAC]) and sporadic (senile systemic amyloidosis [SSA]) forms of human cardiac amyloidosis. We have produced mouse strains transgenic for either wild-type or mutant (TTRLeu55Pro) human TTR genes. Eighty-four percent of C57Bl/6xDBA/2 mice older than 18 months, transgenic for the wild-type human TTR gene, develop TTR deposits that occur primarily in heart and kidney. In most of the animals, the deposits are nonfibrillar and non-Congophilic, but 20% of animals older than 18 months that bear the transgene have human TTR cardiac amyloid deposits identical to the lesions seen in SSA. Amino terminal amino acid sequence analysis and mass spectrometry of the major component extracted from amyloid and nonamyloid deposits revealed that both were intact human TTR monomers with no evidence of proteolysis or codeposition of murine TTR. This is the first instance in which the proteins from amyloid and nonfibrillar deposits in the same or syngeneic animals have been shown to be identical by sequence analysis. It is also the first time in any form of amyloidosis that nonfibrillar deposits have been shown to systematically occur temporally before the appearance of fibrils derived from the same precursor in the same tissues. These findings suggest, but do not prove, that the nonamyloid deposits represent a precursor of the fibril. The differences in the ultrastructure and binding properties of the deposits, despite the identical sizes and amino terminal amino acid sequences of the TTR and the dissociation of deposition and fibril formation, provide evidence that in vivo factors, perhaps associated with aging, impact on both systemic precursor deposition and amyloid fibril formation. (Lab Invest 2001, 81:385-396).

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We have shown previously that the 5' ends of the genes for the ca5(IV) and ca6(IV) collagen chains lie head-to-head on