Palma Mangione

Bio: Palma Mangione is an academic researcher from University College London. The author has contributed to research in topics: Amyloidosis & Amyloid. The author has an hindex of 32, co-authored 70 publications receiving 3295 citations. Previous affiliations of Palma Mangione include University of Pavia.

Antibodies to human serum amyloid P component eliminate visceral amyloid deposits

Abstract: Accumulation of amyloid fibrils in the viscera and connective tissues causes systemic amyloidosis, which is responsible for about one in a thousand deaths in developed countries. Localized amyloid can also have serious consequences; for example, cerebral amyloid angiopathy is an important cause of haemorrhagic stroke. The clinical presentations of amyloidosis are extremely diverse and the diagnosis is rarely made before significant organ damage is present. There is therefore a major unmet need for therapy that safely promotes the clearance of established amyloid deposits. Over 20 different amyloid fibril proteins are responsible for different forms of clinically significant amyloidosis and treatments that substantially reduce the abundance of the respective amyloid fibril precursor proteins can arrest amyloid accumulation. Unfortunately, control of fibril-protein production is not possible in some forms of amyloidosis and in others it is often slow and hazardous. There is no therapy that directly targets amyloid deposits for enhanced clearance. However, all amyloid deposits contain the normal, non-fibrillar plasma glycoprotein, serum amyloid P component (SAP). Here we show that administration of anti-human-SAP antibodies to mice with amyloid deposits containing human SAP triggers a potent, complement-dependent, macrophage-derived giant cell reaction that swiftly removes massive visceral amyloid deposits without adverse effects. Anti-SAP-antibody treatment is clinically feasible because circulating human SAP can be depleted in patients by the bis-d-proline compound CPHPC, thereby enabling injected anti-SAP antibodies to reach residual SAP in the amyloid deposits. The unprecedented capacity of this novel combined therapy to eliminate amyloid deposits should be applicable to all forms of systemic and local amyloidosis.

Removal of the N-terminal hexapeptide from human beta2-microglobulin facilitates protein aggregation and fibril formation.

Abstract: The solution structure and stability of N-terminally truncated beta2-microglobulin (deltaN6beta2-m), the major modification in ex vivo fibrils, have been investigated by a variety of biophysical techniques. The results show that deltaN6beta2-m has a free energy of stabilization that is reduced by 2.5 kcal/mol compared to the intact protein. Hydrogen exchange of a mixture of the truncated and full-length proteins at microM concentrations at pH 6.5 monitored by electrospray mass spectrometry reveals that deltaN6beta2-m is significantly less protected than its wild-type counterpart. Analysis of deltaN6beta2-m by NMR shows that this loss of protection occurs in beta strands I, III, and part of II. At mM concentration gel filtration analysis shows that deltaN6beta2-m forms a series of oligomers, including trimers and tetramers, and NMR analysis indicates that strand V is involved in intermolecular interactions that stabilize this association. The truncated species of beta2-microglobulin was found to have a higher tendency to self-associate than the intact molecule, and unlike wild-type protein, is able to form amyloid fibrils at physiological pH. Limited proteolysis experiments and analysis by mass spectrometry support the conformational modifications identified by NMR and suggest that deltaN6beta2-m could be a key intermediate of a proteolytic pathway of beta2-microglobulin. Overall, the data suggest that removal of the six residues from the N-terminus of beta2-microglobulin has a major effect on the stability of the overall fold. Part of the tertiary structure is preserved substantially by the disulfide bridge between Cys25 and Cys80, but the pairing between beta-strands far removed from this constrain is greatly perturbed.

Hereditary systemic amyloidosis due to Asp76Asn variant β2-microglobulin

Abstract: We describe a kindred with slowly progressive gastrointestinal symptoms and autonomic neuropathy caused by autosomal dominant, hereditary systemic amyloidosis. The amyloid consists of Asp76Asn variant β(2)-microglobulin. Unlike patients with dialysis-related amyloidosis caused by sustained high plasma concentrations of wild-type β(2)-microglobulin, the affected members of this kindred had normal renal function and normal circulating β(2)-microglobulin values. The Asp76Asn β(2)-microglobulin variant was thermodynamically unstable and remarkably fibrillogenic in vitro under physiological conditions. Previous studies of β(2)-microglobulin aggregation have not shown such amyloidogenicity for single-residue substitutions. Comprehensive biophysical characterization of the β(2)-microglobulin variant, including its 1.40-A, three-dimensional structure, should allow further elucidation of fibrillogenesis and protein misfolding.

The solution structure of human β2-microglobulin reveals the prodromes of its amyloid transition

Abstract: β2-microglobulin (β2-m) is the nonpolymorphic light chain of the class I major histocompatibility complex (MHC-I). It consists of 99 residues with a single disulfide bridge between the two Cys residues of the sequence at positions 25 and 80 and folds into the classical β-sandwich motif of the immunoglobulin superfamily, as shown by the crystal structure of MHC-I (Bjorkman et al. 1987). The systemic deposition of β2-m fibrils is associated to dialysis-related amyloidosis (DRA; Gejyo et al. 1985), a disease which arises in individuals with chronic renal failure as the inescapable complication of long-term hemodialysis. More than 90% of patients undergoing dialysis for ∼10 y develop symptoms such as destructive arthropathy, bone fractures, and carpal tunnel. Because of the ensuing physical disabilities, against which treatment (including surgery) is only palliative, and the widespread occurrence of renal failure (∼200,000 individuals are steadily under dialysis in Europe alone), this type of amyloidosis can be regarded as a high-cost social disease. Amyloidoses have been recognized as conformational diseases that arise from the conversion of globular proteins to insoluble fibrillar aggregates. In spite of the diversity of the involved proteins, their amyloid fibrils share a common structure known as cross-β structure, in which partially unfolded conformations aggregate through intermolecular β-strand pairing that are arranged perpendicular to the fiber polymerization axis (Sunde et al. 1997). Analyses of the material extracted from DRA patients have shown that only full-length wild-type β2-m and proteolysis products thereof occur in fibrils (Linke et al. 1987, 1989; Bellotti et al. 1998), along with some glycation (Miyata et al. 1993) and oxidation derivatives (Capeiller-Blandin et al. 1991) and auxiliary proteins (apoE, serum amyloid P component; Miyata et al. 1993). The most abundant species among the truncation products of β2-m (30% of β2-m in ex vivo fibrils) is the form devoid of the six N-terminal residues (ΔN6β2-m). This species was shown to have a higher tendency to self-aggregate than the full-length protein and did not form a fully folded native state at the end of the refolding procedure (Bellotti et al. 1998). A comparative investigation of full-length β2-m and ΔN6β2-m by 1H NMR, electrospray mass spectrometry, and limited proteolysis enabled us to establish the extent and the location of the structural modifications undergone by β2-m upon removal of the N-terminal hexapeptide (Esposito et al. 2000). By analyzing the changes and the persistences of the NMR pattern of both products, some features of the amyloidogenic conformation of β2-m could be suggested, namely, the identity of the β-strands involved in the intermolecular pairing and a model to explain partial unfolding and aggregation of the truncated and full-length species (Esposito et al. 2000). In a subsequent study on the fibrils of β2-m and ΔN6β2-m, overlapping patterns of limited proteolysis were observed with an additional cleavage for the full-length protein fibrils leading to the truncated species (M. Monti et al. 2001, pers. comm.). These findings, while suggesting a mechanism for the occurrence of ΔN6β2-m in vivo, which implies that the only fibrillogenic species is the full-length protein, strongly support the idea that the truncated species features the amyloidogenic conformation of β2-m, as previously anticipated (Esposito et al. 2000; Chiti et al. 2001). Going further along this rationale, we wondered which could be the structural characteristics that drive the transition of β2-m into an amyloidogenic conformation. The protein occurs naturally in the MHC-I complex and is lost from the cell surface into the plasma to reach the kidneys and eventually to be degraded. When the renal function is compromised and dialysis becomes necessary, only a considerable increase of its plasma concentration is steadily detected (25- to 35-fold; Gejyo et al. 1985) before deposition of amyloid fibrils. Although the isolated protein in solution has been studied by NMR (Okon et al. 1992), only a qualitative analysis of its secondary structure was reported that showed, however, a very close analogy with the crystal structure of the protein in the context of the MHC-I complex (Bjorkman et al. 1987; Saper et al., 1991). Because even minor deviations from the crystal structure may affect significantly the stability of a protein that naturally binds to the polymorphic component of human leukocyte antigen, a determination of the tertiary structure of isolated β2-m in solution is useful, provided the proper level of accuracy is reached to perform a meaningful comparison with the crystal structure. Here we present the 3D solution structure of isolated β2-m obtained from 1H NMR data (Protein Data Bank ID 1JNJ) and show that differences with respect to the crystal structure are indeed observed.

Protein Misfolding, Functional Amyloid, and Human Disease

Abstract: Peptides or proteins convert under some conditions from their soluble forms into highly ordered fibrillar aggregates. Such transitions can give rise to pathological conditions ranging from neurodegenerative disorders to systemic amyloidoses. In this review, we identify the diseases known to be associated with formation of fibrillar aggregates and the specific peptides and proteins involved in each case. We describe, in addition, that living organisms can take advantage of the inherent ability of proteins to form such structures to generate novel and diverse biological functions. We review recent advances toward the elucidation of the structures of amyloid fibrils and the mechanisms of their formation at a molecular level. Finally, we discuss the relative importance of the common main-chain and side-chain interactions in determining the propensities of proteins to aggregate and describe some of the evidence that the oligomeric fibril precursors are the primary origins of pathological behavior.

Of Theory and Practice

Abstract: Much has been written about theory and practice in the law, and the tension between practitioners and theorists. Judges do not cite theoretical articles often; they rarely "apply" theories to particular cases. These arguments are not revisited. Instead the Essay explores the working and interaction of theory and practice, practitioners and theorists. The Essay starts with a story about solving a legal issue using our intellectual tools - theory, practice, and their progenies: experience and "gut." Next the Essay elaborates on the nature of theory, practice, experience and "gut." The third part of the Essay discusses theories that are helpful to practitioners and those that are less helpful. The Essay concludes that practitioners theorize, and theorists practice. They use these intellectual tools differently because the goals and orientations of theorists and practitioners, and the constraints under which they act, differ. Theory, practice, experience and "gut" help us think, remember, decide and create. They complement each other like the two sides of the same coin: distinct but inseparable.

Protein Misfolding, Amyloid Formation, and Human Disease: A Summary of Progress Over the Last Decade

Abstract: Peptides and proteins have been found to possess an inherent tendency to convert from their native functional states into intractable amyloid aggregates. This phenomenon is associated with a range of increasingly common human disorders, including Alzheimer and Parkinson diseases, type II diabetes, and a number of systemic amyloidoses. In this review, we describe this field of science with particular reference to the advances that have been made over the last decade in our understanding of its fundamental nature and consequences. We list the proteins that are known to be deposited as amyloid or other types of aggregates in human tissues and the disorders with which they are associated, as well as the proteins that exploit the amyloid motif to play specific functional roles in humans. In addition, we summarize the genetic factors that have provided insight into the mechanisms of disease onset. We describe recent advances in our knowledge of the structures of amyloid fibrils and their oligomeric precursors a...

Molecular mechanisms of amyloidosis.

Abstract: Amyloidosis affects millions of people, as a cause of Alzheimer's disease or a complication of dialysis, and also causes rare conditions. The many forms of the disorder have one underlying principle: misfolded proteins. Prompt, correct diagnosis is essential, especially in the inherited forms of amyloidosis. This article reviews the molecular basis of various types of amyloidosis and proposes new ways of treating these disorders.

Protein aggregation and aggregate toxicity: new insights into protein folding, misfolding diseases and biological evolution

Abstract: The deposition of proteins in the form of amyloid fibrils and plaques is the characteristic feature of more than 20 degenerative conditions affecting either the central nervous system or a variety of peripheral tissues. As these conditions include Alzheimer's, Parkinson's and the prion diseases, several forms of fatal systemic amyloidosis, and at least one condition associated with medical intervention (haemodialysis), they are of enormous importance in the context of present-day human health and welfare. Much remains to be learned about the mechanism by which the proteins associated with these diseases aggregate and form amyloid structures, and how the latter affect the functions of the organs with which they are associated. A great deal of information concerning these diseases has emerged, however, during the past 5 years, much of it causing a number of fundamental assumptions about the amyloid diseases to be re-examined. For example, it is now apparent that the ability to form amyloid structures is not an unusual feature of the small number of proteins associated with these diseases but is instead a general property of polypeptide chains. It has also been found recently that aggregates of proteins not associated with amyloid diseases can impair the ability of cells to function to a similar extent as aggregates of proteins linked with specific neurodegenerative conditions. Moreover, the mature amyloid fibrils or plaques appear to be substantially less toxic than the pre-fibrillar aggregates that are their precursors. The toxicity of these early aggregates appears to result from an intrinsic ability to impair fundamental cellular processes by interacting with cellular membranes, causing oxidative stress and increases in free Ca2+ that eventually lead to apoptotic or necrotic cell death. The 'new view' of these diseases also suggests that other degenerative conditions could have similar underlying origins to those of the amyloidoses. In addition, cellular protection mechanisms, such as molecular chaperones and the protein degradation machinery, appear to be crucial in the prevention of disease in normally functioning living organisms. It also suggests some intriguing new factors that could be of great significance in the evolution of biological molecules and the mechanisms that regulate their behaviour.