Joel N. Buxbaum

Variant-Sequence Transthyretin (Isoleucine 122) in Late-Onset Cardiac Amyloidosis in Black Americans

BACKGROUND After the age of 60, isolated cardiac amyloidosis is four times more common among blacks than whites in the United States; 3.9 percent of blacks are heterozygous for an amyloidogenic allele of the normal serum carrier protein transthyretin in which isoleucine is substituted for valine at position 122 (Ile 122). We hypothesized that the high prevalence of transthyretin Ile 122 is at least partially responsible for the increased frequency of senile cardiac amyloidosis among blacks. METHODS Paraffin blocks of cardiac tissue were obtained from an earlier study of 52,370 autopsies in Los Angeles and were examined by immunohistochemical and DNA analyses. Samples were available from 32 of 55 blacks and 20 of 78 whites over 60 years of age with isolated cardiac amyloidosis and from two control groups (228 cases). RESULTS Transthyretin amyloidosis was identified in 31 of the 32 cardiac-tissue samples from the black patients and in 19 of the 20 samples from the white patients. Six of the 26 analyzable DNA samples (23 percent) from the black patients and none of the 19 samples from the white patients were heterozygous for the Ile 122 variant. Four of 125 DNA samples obtained at autopsy (3.2 percent) from a second, more recent, age-matched cohort of blacks without amyloidosis at the same institution were heterozygous for the transthyretin Ile 122 allele. On reexamination the cardiac tissue from these four patients contained small amounts of amyloid not detected at the initial autopsies. All subjects with the Ile 122 variant had ventricular amyloid. CONCLUSIONS 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.

Amyloid fibril protein nomenclature: 2012 recommendations from the Nomenclature Committee of the International Society of Amyloidosis

The Nomenclature Committee of the International Society of Amyloidosis (ISA) met during the XIIIth International Symposium, May 6–10, 2012, Groningen, The Netherlands, to formulate recommendations on amyloid fibril protein nomenclature and to consider newly identified candidate amyloid fibril proteins for inclusion in the ISA Amyloid Fibril Protein Nomenclature List. The need to promote utilization of consistent and up to date terminology for both fibril chemistry and clinical classification of the resultant disease syndrome was emphasized. Amyloid fibril nomenclature is based on the chemical identity of the amyloid fibril forming protein; clinical classification of the amyloidosis should be as well. Although the importance of fibril chemistry to the disease process has been recognized for more than 40 years, to this day the literature contains clinical and histochemical designations that were used when the chemical diversity of amyloid diseases was poorly understood. Thus, the continued use of disease classifications such as familial amyloid neuropathy and familial amyloid cardiomyopathy generates confusion. An amyloid fibril protein is defined as follows: the protein must occur in body tissue deposits and exhibit both affinity for Congo red and green birefringence when Congo red stained deposits are viewed by polarization microscopy. Furthermore, the chemical identity of the protein must have been unambiguously characterized by protein sequence analysis when so is practically possible. Thus, in nearly all cases, it is insufficient to demonstrate mutation in the gene of a candidate amyloid protein; the protein itself must be identified as an amyloid fibril protein. Current ISA Amyloid Fibril Protein Nomenclature Lists of 30 human and 10 animal fibril proteins are provided together with a list of inclusion bodies that, although intracellular, exhibit some or all of the properties of the mainly extracellular amyloid fibrils.

A primer of amyloid nomenclature

The increasing knowledge of the exact biochemical nature of the localized and systemic amyloid disorders has made a logical and easily understood nomenclature absolutely necessary. Such a nomenclature, biochemically based, has been used for several years but the current literature is still mixed up with many clinical and histochemically based designations from the time when amyloid in general was poorly understood. All amyloid types are today preferably named by their major fibril protein. This makes a simple and rational nomenclature for the increasing number of amyloid disorders known in humans and animals.

Amyloid: Toward terminology clarification Report from the Nomenclature Committee of the International Society of Amyloidosis

The modern nomenclature of amyloidosis now includes 25 human and 8 animal fibril proteins. To be included in the list, the protein has to be a major fibril protein in extracellular deposits, which have the characteristics of amyloid, including affinity for Congo red with resulting green birefringence. Synthetic fibrils with amyloid properties are best named ‘amyloid-like’. With increasing knowledge, however, the borders between different protein aggregates tend to become less sharp.

Nomenclature 2014: Amyloid fibril proteins and clinical classification of the amyloidosis

The Nomenclature Committee of the International Society of Amyloidosis (ISA) met during the XIVth Symposium of the Society, April 27–May 1, 2014, Indianapolis, IN, to assess and formulate recommend...

A Diffuse Infiltrative CD8 Lymphocytosis Syndrome in Human Immunodeficiency Virus (HIV) Infection: A Host Immune Response Associated with HLA-DR5

STUDY OBJECTIVE To describe the clinical, immunologic, and immunogenetic features of a diffuse infiltrative lymphocytic disorder resembling Sjögren syndrome in persons infected with human immunodeficiency virus (HIV). DESIGN Clinical case study. SETTING University-affiliated hospitals and outpatient clinics. PATIENTS Consecutive sample of 17 patients. MEASUREMENTS AND MAIN RESULTS All of the 17 patients had bilateral parotid gland enlargement; 14 had xerostomia and 6 had xerophthalmia. Of the 17 patients, 14 had generalized lymphadenopathy, 10 had histologically proved lymphocytic interstitial pneumonitis, 4 had neurologic involvement, and 3 had lymphocytic infiltration of the gastrointestinal tract. Gallium scanning in all of 11 tested patients showed abnormal salivary gland uptake. Minor salivary gland biopsies showed more than 2 lymphocytic foci per 4 mm2 tissue in all of 11 tested patients, the infiltrate consisting predominantly of CD8 cells. Fifteen patients had circulating CD8 lymphocytosis; the principal phenotype of these cells was CD8+ CD29+. Rheumatoid factor and antinuclear antibodies were infrequent, and none of the patients had anti-Ro/SS-A or anti-La/SS-B antibodies. HLA-DR5 was significantly more frequent in the black patients (10 of 12) compared with controls (13 of 45). Only one patient developed an opportunistic infection during 544 patient-months of study, and none has died of AIDS. CONCLUSIONS A distinct syndrome primarily characterized by parotid gland enlargement, sicca symptoms, and pulmonary involvement occurs in HIV infection. This disorder is associated with CD8 lymphocytosis and the presence of HLA-DR5, and appears to be a genetically determined host immune response to HIV.

Monoclonal Immunoglobulin Deposition Disease: Light Chain and Light and Heavy Chain Deposition Diseases and Their Relation to Light Chain Amyloidosis: Clinical Features, Immunopathology, and Molecular Analysis

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.

Transthyretin protects Alzheimer's mice from the behavioral and biochemical effects of Aβ toxicity

Cells that have evolved to produce large quantities of secreted proteins to serve the integrated functions of complex multicellular organisms are equipped to compensate for protein misfolding. Hepatocytes and plasma cells have well developed chaperone and proteasome systems to ensure that secreted proteins transit the cell efficiently. The number of neurodegenerative disorders associated with protein misfolding suggests that neurons are particularly sensitive to the pathogenic effects of aggregates of misfolded molecules because those systems are less well developed in this lineage. Aggregates of the amyloidogenic (Aβ1–42) peptide play a major role in the pathogenesis of Alzheimers disease (AD), although the precise mechanism is unclear. In genetic studies examining protein–protein interactions that could constitute native mechanisms of neuroprotection in vivo, overexpression of a WT human transthyretin (TTR) transgene was ameliorative in the APP23 transgenic murine model of human AD. Targeted silencing of the endogenous TTR gene accelerated the development of the neuropathologic phenotype. Intraneuronal TTR was seen in the brains of normal humans and mice and in AD patients and APP23 mice. The APP23 brains showed colocalization of extracellular TTR with Aβ in plaques. Using surface plasmon resonance we obtained in vitro evidence of direct protein–protein interaction between TTR and Aβ aggregates. These findings suggest that TTR is protective because of its capacity to bind toxic or pretoxic Aβ aggregates in both the intracellular and extracellular environment in a chaperone-like manner. The interaction may represent a unique normal host defense mechanism, enhancement of which could be therapeutically useful.

Transthyretin Pro55, a variant associated with early-onset, aggressive, diffuse amyloidosis with cardiac and neurologic involvement

SummaryMutations in the protein transthyretin cause amyloidosis involving the heart, peripheral nerves, and other organs. A family from West Virginia developed an unusually aggressive form of widespread transthyretin amyloidosis. Single-strand conformation polymorphism analysis revealed a variant in the transthyretin gene, which was found on sequencing to be a T→C transversion at position 2 of codon 55, corresponding to a Leu→ Pro substitution. The variant sequence was confirmed by restriction analysis and polymerase chain reaction (PCR)-primer introduced restriction analysis.

An Adaptable Standard for Protein Export from the Endoplasmic Reticulum

To provide an integrated view of endoplasmic reticulum (ER) function in protein export, we have described the interdependence of protein folding energetics and the adaptable biology of cellular protein folding and transport through the exocytic pathway. A simplified treatment of the protein homeostasis network and a formalism for how this network of competing pathways interprets protein folding kinetics and thermodynamics provides a framework for understanding cellular protein trafficking. We illustrate how folding and misfolding energetics, in concert with the adjustable biological capacities of the folding, degradation, and export pathways, collectively dictate an adaptable standard for protein export from the ER. A model of folding for export (FoldEx) establishes that no single feature dictates folding and transport efficiency. Instead, a network view provides insight into the basis for cellular diversity, disease origins, and protein homeostasis, and predicts strategies for restoring protein homeostasis in protein-misfolding diseases.