Molecular mechanisms of amyloidosis.
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Amyloid↗
Biomedical subjects
Giampaolo Merlini
Publications and source records attributed to Giampaolo Merlini.
Serum N-terminal pro-brain natriuretic peptide is a sensitive marker of myocardial dysfunction in AL amyloidosis.
BACKGROUND: Brain natriuretic peptide (BNP) is a marker of ventricular dysfunction and can be used to assess prognosis in heart failure and after myocardial infarction. Heart involvement is the most important prognostic factor and causes death in almost all patients with light-chain amyloidosis (AL). We investigated the prognostic value of NT-proBNP and its utility in monitoring amyloid heart dysfunction. METHODS AND RESULTS: NT-proBNP was quantified at diagnosis in 152 consecutive patients seen at the coordinating center of the Italian Amyloidosis Study Group (Pavia) from 1999 throughout 2001. Heart involvement was estimated on the basis of clinical signs, electrocardiography, and echocardiography. NT-proBNP concentrations differed in patients with (n=90, 59%) and without (n=62, 41%) heart involvement (median: 507.8 pmol/L versus 22.1 pmol/L, P=10(-7)). The best cutoff for heart involvement was at 152 pmol/L (sensitivity: 93.33%, specificity: 90.16%, accuracy: 92.05%) and distinguished two groups with different survival (P<0.001). The Cox multivariate model including NT-proBNP was better than models including echocardiographic and clinical signs of heart involvement. NT-proBNP appeared to be more sensitive than conventional echocardiographic parameters in detecting clinical improvement or worsening of amyloid cardiomyopathy during follow-up. CONCLUSIONS: NT-proBNP appeared to be the most sensitive index of myocardial dysfunction and the most powerful prognostic determinant in AL amyloidosis. It adds prognostic information for newly diagnosed patients and can be useful in designing therapeutic strategies and monitoring response. NT-proBNP is a sensitive marker of heart toxicity caused by amyloidogenic light chains.
Adult↗
Molecular and functional bases of self-antigen recognition in long-term persistent melanocyte-specific CD8+ T cells in one vitiligo patient.
Vitiligo patients possess high frequencies of circulating CD8+ T lymphocytes specific for the melanocyte differentiation antigen Melan-A/MART-1. These self-specific T cells exhibit intact functional properties and their T cell receptors are selected for a narrow range of high affinities of antigen recognition, suggesting their important role in the pathogenesis of vitiligo. In order to understand the molecular base for this unexpected, optimal T cell receptor recognition of a self-antigen, a tetramer-guided ex vivo analysis of the T cell receptor repertoire specific for the Melan-A antigen in a patient affected by vitiligo is reported. All T cell receptors sequenced corresponded to different clonotypes, excluding extensive clonal expansions and revealing a large repertoire of circulating Melan-A-specific T lymphocytes. A certain degree of T cell receptor structural conservation was noticed, however, as a single AV segment contributed to the alpha chain rearrangement in 100% of clones and a conserved amino acid sequence was found in the beta chain complementarity determining region 3 of various high affinity cells. We suggest that the conserved alpha chain confers self-antigen recognition, necessary for intrathymic selection and peripheral homeostasis, to many synonymous T cell receptors, whereas the beta chain fine tunes the T cell receptor affinity of the specific cells. In addition, we demonstrate that many high avidity T cell clones from this patient were capable of specifically lysing normal, HLA-matched melanocytes. These autoreactive clones persisted for more than 3 y in the patient's peripheral blood. These data, together with the skin-homing potential of the clones, directly point to the in vivo pathogenic role of melanocyte-specific cytotoxic T lymphocytes in vitiligo.
Antigens, Neoplasm↗
Prognostic markers and criteria to initiate therapy in Waldenstrom's macroglobulinemia: consensus panel recommendations from the Second International Workshop on Waldenstrom's Macroglobulinemia.
This presentation represents consensus recommendations on prognostic markers and criteria to initiate therapy in patients with Waldenstrom's macroglobulinemia (WM), which were prepared in conjunction with the Second International Workshop held in Athens, Greece during September 2002. The panel recommended that initiation of therapy should not be based on the IgM level per se since this may not correlate with the clinical manifestations of WM. The consensus panel agreed that initiation of therapy was appropriate for patients with constitutional symptoms such as recurrent fever, night sweats, fatigue due to anemia, or weight loss. The presence of progressive, symptomatic lymphadenopathy or splenomegaly provide additional reasons to begin therapy. The presence of anemia with a hemoglobin value of <or= 10 g/dL or a platelet count < 100 x 10(9)/L due to marrow infiltration also justifies treatment. Certain complications such as hyperviscosity syndrome, symptomatic sensorimotor peripheral neuropathy, systemic amyloidosis, renal insufficiency, or symptomatic cryoglobulinemia may also be indications for therapy. Recommendations for follow-up of watch-and-wait patients are that those with monoclonal gammopathy of undetermined significance (MGUS) should have serum protein electrophoresis repeated each year. Patients with asymptomatic (smoldering) macroglobulinemia should be evaluated every 6 months. Regarding prognostic markers, hemoglobin and beta(2)-microglobulin levels at diagnosis are important prognostic markers in WM: they influence the timing of treatment and survival. Age is a consistently important prognostic factor for survival. However, the panel felt that current data are inadequate to support the use of any prognostic marker to select the timing and type of therapy, and called for studies on the application of prognostic markers in WM.
Age Factors↗
Prognostic factors in symptomatic Waldenstrom's macroglobulinemia.
We analyze the prognostic value of the presenting features of a series of patients with symptomatic Waldenstrom's macroglobulinemia who were homogeneously treated. A total of 215 patients (119 males) with a median age of 62.6 years (range, 24.9 to 91.6) were retrospectively analyzed. The median overall follow-up was 57.6 months (range, 0.6 to 281): 58 (0.9 to 281) for living patients and 52.2 (0.6 to 261.3) for those who died. All patients were treated with alkylating agent-based chemotherapy. The overall median survival was 77.2 months, without significant differences based on the duration of the previous monoclonal gammopathy of undetermined significance (MGUS) phase. The multivariate Cox analysis performed on the whole population showed that age, hemoglobin level, and serum albumin level predicted survival. The addition of beta(2)-microglobulin, available in the subgroup of 60 patients diagnosed after 1990, in a Cox stepwise selection showed that this parameter was by far the main prognostic determinant. Application of the Dhodapkar, Morel, and Gobbi scoring systems to this population of patients showed that all three stratified the population into groups with significantly distinct prognoses. A prognostic index based on age, hemoglobin, and albumin is capable of identifying various groups of patients with different therapeutic needs.
Adult↗
4'-iodo-4'-deoxydoxorubicin and tetracyclines disrupt transthyretin amyloid fibrils in vitro producing noncytotoxic species: screening for TTR fibril disrupters.
Transthyretin Leu55Pro is one of the most aggressive mutations in familial amyloidotic polyneuropathy, an autosomal dominant disorder characterized by extracellular deposition of fibrillar amyloid protein. This variant has the ability to form fibrils in vitro under physiological conditions (PBS, pH 7.4). We studied by transmission electron microscopy the effect of the drug 4'-iodo-4'-deoxydoxorubicin (I-DOX) on the in vitro assembly of TTR Leu55Pro fibrils by following fibril growth over a 15 day period. Our results showed that I-DOX at a concentration of 10-5 M/100 microg fibrils does not inhibit fibril formation in up to 10 days since fibrils identical to the ones present in the untreated sample were observed. However, after 15 days of treatment, only round particles, resembling soluble native TTR, were observed. We also tested the ability of tetracyclines and nitrophenols to interfere with amyloid fibril formation for 17 days; the group of compounds tested showed fibril disruption activity to different extents: doxycycline and 2,4-dinitrophenol resulted in complete disaggregation of fibrils. The species generated upon I-DOX and tetracyclines treatments were nontoxic, as revealed by the lack of significant caspase-3 activation on a Schwannoma cell line, making them potential therapeutic drugs in TTR-related and other amyloidosis.
Amino Acid Substitution↗
Biological variation of N-terminal pro-brain natriuretic peptide in healthy individuals.
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Adult↗
Guidelines for the analysis of Bence Jones protein.
The detection and quantification of monoclonal free light chains in urine (Bence Jones protein, BJP) are thorny issues for the laboratorian. Immunoelectrophoretic techniques (immunofixation) allow the characterization of the two pathognomonic features of light chains: monoclonality and absence of heavy chains. Immunochemical methods such as nephelometry and turbidimetry are widely used in clinical practice to exclude the presence of BJP. However, these methods are limited by several metabolic and analytical problems. The accuracy of quantitative immunochemical methods is hampered by the heterogeneous molecular forms (fragments and polymers) of BJP and by the lack of reference materials, and the precision of the methods in clinically relevant regions of the dynamic range is poorly defined. Immunoelectrophoretic methods, especially immunofixation, are recommended because of their ability to demonstrate monoclonality and the absence of heavy chains. Immunofixation is also considered the best method to document the disappearance of the monoclonal protein (complete remission). The physiology of immunoglobulins and the clinical relevance of BJP are illustrated in the two appendices to this paper.
Antibodies, Monoclonal↗
Conformational switching and fibrillogenesis in the amyloidogenic fragment of apolipoprotein a-I.
The N-terminal portion of apolipoprotein A-I corresponding to the first 93 residues has been identified as the main component of apolipoprotein A-I fibrils in a form of systemic amyloidosis. We have been able to characterize the process of conformational switching and fibrillogenesis in this fragment of apolipoprotein A-I purified directly from ex vivo amyloid material. The peptide exists in an unstructured form in aqueous solution at neutral pH. The acidification of the solution provokes a collapse into a more compact, intermediate state and the transient appearance of a helical conformation that rapidly converts to a stable, mainly beta-structure in the fibrils. The transition from helical to sheet structure occurs concomitantly with peptide self-aggregation, and fibrils are detected after 72 h. The alpha-helical conformation is induced by the addition of trifluoroethanol and phospholipids. Interaction of the amyloidogenic polypeptide with phospholipids prevents the switching from helical to beta-sheet form and inhibits fibril formation. The secondary structure propensity of the apolipoprotein A-I fragment appears poised between helix and the beta-sheet. These findings reinforce the idea of a delicate balance between natively stabilizing interactions and fatally stabilizing interactions and stress the importance of cellular localization and environment in the maintenance of protein conformation.
Amino Acid Sequence↗
Analysis of V(lambda)-J(lambda) expression in plasma cells from primary (AL) amyloidosis and normal bone marrow identifies 3r (lambdaIII) as a new amyloid-associated germline gene segment.
Primary (AL) amyloidosis is a plasma cell dyscrasia characterized by extracellular deposition of monoclonal light-chain variable region (V) fragments in the form of amyloid fibrils. Light-chain amyloid is rare, and it is not fully understood why it occurs in only a fraction of patients with a circulating monoclonal component and why it typically associates with lambda isotype and lambdaVI family light-chain proteins. To provide insights into these issues, we obtained complete nucleotide sequences of monoclonal V(lambda) regions from 55 consecutive unselected cases of primary amyloidosis and the results were compared with the light-chain expression profile of polyclonal marrow plasma cells from 3 healthy donors (a total of 264 sequences). We demonstrated that: (1) the lambdaIII family is the most frequently used both in amyloidosis (47%) and in polyclonality (43%); (2) both conditions are characterized by gene restriction; (3) a very skewed repertoire is a feature of amyloidosis, because just 2 germline genes belonging to the lambdaIII and lambdaVI families, namely 3r (22% of cases, lambdaIII) and 6a (20%, lambdaVI), contributed equally to encode 42% of amyloid V(lambda) regions; (4) these same 2 gene segments have a strong association with amyloidosis if their prevalences are compared with those in polyclonal conditions (3r, 8.3%, P =.024; 6a, 2.3%, P =.0008, chi2 test); (5) the J(lambda)2/3 segment, encoding the fourth framework region, appears to be slightly overrepresented in AL (83% versus 67%, P =.03), and this might be related to preferential J(lambda)2/3 rearrangement in amyloid (11 of 12 cases) versus polyclonal 3r light chains (13 of 22 cases). These findings demonstrate that V(lambda)-J(lambda) expression is more restricted in plasma cells from amyloidosis than from polyclonal bone marrow and identify 3r as a new disease-associated gene segment. Overusage of just 2 gene segments, 3r and 6a, can thus account for the lambda light-chain overrepresentation typical of this disorder.
Adult↗
A multicenter phase II trial of 4'-iodo-4'deoxydoxorubicin (IDOX) in primary amyloidosis (AL).
INTRODUCTION: 4'-Iodo-4'-deoxydoxorubicin (IDOX) has been reported to bind to and lead to the catabolism of amyloid deposits. A multicenter study attempted to develop a dosing schedule to confirm those results. METHODS: Patients with biopsy-proven amyloidosis were required to have a cardiac ejection fraction > 50%, ventricular septal thickness < 20 mm, serum creatinine < 2.5 mg per dL, bilirubin < or = 2.0 mg per dL, neutrophils > 1,500 per microL, and platelets > 100,000 per microL. IDOX was administered intravenously over 1 hour at a dose of 15 mg per m2 once a week for 4 consecutive weeks. This therapy was repeated every 3 months up to 4 times. RESULTS: Twenty-five previously treated and 15 untreated patients with primary amyloidosis (AL) received therapy. Fifteen patients had > 3 g of protein per day in the urine. Eleven patients had an ejection fraction < 60%. One, 2, 3, 4, and 5 organ systems were involved in 22, 10, 4, 3, and 1 patient, respectively. The median time between diagnosis and initiation of IDOX was 17.4 months. There were 6 responses (15%). Twelve of the patients have died CONCLUSION: IDOX administered in this protocol was insufficiently active at the current dose.
Aged↗
IX International Symposium on Amyloidosis, July 15-21, 2001, Budapest, Hungary.
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Amyloidosis↗
Amyloid fibril protein nomenclature -- 2002.
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Amyloid↗
[Fibril-forming proteins: the amyloidosis. New hopes for a disease that cardiologists must know].
Several proteins share the property of conforming as antiparallel beta-sheets, and forming insoluble amyloid fibrils that deposit in the interstitium of organs/tissues and cause systemic amyloidosis. Cardiac involvement is frequent and constitutes a major predictor of poor outcome. Its typical phenotype is that of restrictive cardiomyopathy. The biochemical classification of the amyloidogenic proteins provides the bases for innovative therapeutic approaches. Primary systemic amyloidosis (AL) is a protein conformation disorder in which monoclonal immunoglobulin light chains (kappa or lambda) produced by clonal plasma cells, are deposited as amyloid in kidneys, heart, liver, and other organs. The recent evidence that chemotherapy reduces or even eradicates the amyloidogenic clone with consequent functional improvement of the affected organs raises new hopes for a treatment, whose key of success is early diagnosis. Heart transplantation can be proposed in patients < 60 years of age in association with autologous stem cell transplantation. In serum amyloid A amyloidosis, fibrils are constituted of the acute phase serum amyloid A protein that is produced in excess in chronic inflammatory diseases such as familial mediterranean fever, autoimmune disorders and chronic infections. The strategy is to treat the underlying inflammatory disease, but new molecules inhibiting amyloid formation and promoting amyloid resorption are facing the clinical scenario and trials are in progress. In transthyretin (TTR) amyloidosis, the non-senile forms are autosomal dominant diseases caused by defective proteins synthesized by mutated TTR genes (more than 70 known mutations with different genotype-phenotype correlations). The treatment is based on transplantation of the TTR-producing liver; exceptionally, liver plus heart or kidney are transplanted. Apolipoprotein A1 amyloidosis is an inherited autosomal dominant disease that benefits from the transplantation of the most impaired organs, usually heart, liver or kidney, either single or combined. The diagnosis of apolipoprotein A1 and TTR amyloidosis relies on positive family history, immunocharacterization of the amyloid fibrils in a tissue biopsy, gene defect detection and absence of light chains in serum and urines. Vice versa, non-familial primary amyloidoses are diagnosed when kappa or lambda light chains are identified with immunofixation in serum or urines. Tissue studies provide the gold standard for the diagnosis and immunocharacterization of amyloid protein. Heart involvement is diagnosed with a multiparametric approach that includes clinical, electrocardiographic and echocardiographic evaluation. The fine-needle biopsy of the periumbilical fat is the preferral procedure for amyloid detection and immunocharacterization of amyloid protein. This approach excludes, with a few exceptions, the need of endomyocardial biopsy.
Amyloidosis↗
Pancreatic involvement during the early phase of shock.
BACKGROUND: There is a lack of data concerning pancreatic involvement during shock. AIM: To evaluate possible pancreatic alterations in the early phase of shock. SETTING: Twelve consecutive patients with shock were studied within 2 hours from the onset of illness. Seven patients died during the hospital stay: 3 within 4 hours from admission, 3 within 4-8 hours and 1 within 12 hours. MAIN OUTCOME MEASURES: Amylase, lipase, C-reactive protein, amyloid A, interleukin 6, procalcitonin and vascular cell adhesion molecule-1 serum concentrations were determined on admission and 4, 8, and 12 hours afterward. All patients underwent imaging studies of the pancreas. RESULTS: None of the patients developed clinical signs or morphological alterations compatible with acute pancreatitis. Serum amylase levels were above the upper reference limit in 7 patients (58.3%) and serum lipase levels in 2 patients (16.7%; P=0.062). There were no significant differences found between survivors and non-survivors in the serum concentrations of all the proteins studied. CONCLUSIONS: In patients with shock, amylase seems to be more frequently elevated than lipase. None of the patients showed pancreatic alterations at imaging techniques.
Aged↗
Electron and immuno-electron microscopy of abdominal fat identifies and characterizes amyloid fibrils in suspected cardiac amyloidosis.
We evaluated the role of electron microscopy and immuno-electron microscopy studies on abdominal fat fine-needle biopsy samples in diagnosis and characterization of cardiac amyloidosis. The series consists of 15 patients with echocardiographic evidence of "restrictive cardiomyopathy" suspected to be due to amyloidosis. Patients underwent: clinical examination, electrocardiography, 2-D and Doppler echocardiography, immunofixation of serum and urine for detection of monoclonal immunoglobulins, and abdominalfat biopsies that were investigated with polarized light (Congo red), electron and immuno-electron microscopy using specific antibodies to kappa and lambda light chains, apolipoprotein A1, serum amyloid A (SAA), and transthyretin (TTR). Ultrastructural study of abdominal fat samples identified amyloid deposits in 15/15 cases. Immuno-electron microscopy specifically stained amyloid fibrils with antibodies anti-lambda (n = 8), -kappa (n = 2), -apolipoprotein A1 (n = 2) and -TTR (n = 3). Immuno-electron microscopy revealed TTR immuno-labelling in 2 patients with accidental monoclonal components, and a A reaction in I patient without monoclonal components. TTR and apolipoprotein A1 positive cases carried missense mutations in the corresponding genes. Our results demonstrate that amyloid deposits are present in the abdominalfat of patients suspected to have cardiac amyloidosis and that immuno-electron microscopy was able to characterize the amyloid protein in all cases.
Abdomen↗