Lysosomal dysfunction and impaired autophagy underlie the pathogenesis of amyloidogenic light chain-mediated cardiotoxicity

AL amyloidosis is the consequence of clonal production of amyloidogenic immunoglobulin light chain (LC) proteins, often resulting in a rapidly progressive and fatal amyloid cardiomyopathy. Recent work has found that amyloidogenic LC directly initiate a cardio-toxic response underlying the pathogenesis of the cardiomyopathy; however, the mechanisms that contribute to this proteotoxicity remain unknown. Using human amyloidogenic LC isolated from patients with amyloid cardiomyopathy, we reveal that dysregulation of autophagic flux is critical for mediating amyloidogenic LC proteotoxicity. Restoration of autophagic flux by pharmacological intervention using rapamycin protected against amyloidogenic light chain protein-induced pathologies including contractile dysfunction and cell death at the cellular and organ level and also prolonged survival in an in vivo zebrafish model of amyloid cardiotoxicity. Mechanistically, we identify impaired lysosomal function to be the major cause of defective autophagy and amyloidogenic LC-induced proteotoxicity. Collectively, these findings detail the downstream molecular mechanisms underlying AL amyloid cardiomyopathy and highlight potential targeting of autophagy and lysosomal dysfunction in patients with amyloid cardiomyopathy

Detection of high molecular weight amyloid protein complexes in patient sera using Biological On-Line Tracer Sedimentation (BOLTS)

The systemic amyloidoses are a rare but deadly class of protein folding disorders with significant unmet diagnostic and therapeutic needs. The current model for symptomatic amyloid progression includes a causative role for soluble toxic aggregates as well as for the fibrillar tissue deposits. Although much research is focused on elucidating the potential mechanism of aggregate toxicity, evidence to support their existence in vivo has been limited. We report the use of a technique we have termed biological on-line tracer sedimentation (BOLTS) to detect abnormal high-molecular-weight complexes (HMWCs) in serum samples from individuals with systemic amyloidosis due to aggregation and deposition of wild-type transthyretin (senile systemic amyloidosis, SSA) or monoclonal immunoglobulin light chain (AL amyloidosis). In this proof-of-concept study, HMWCs were observed in 31 of 77 amyloid samples (40.3%). HMWCs were not detected in any of the 17 nonamyloid control samples subjected to BOLTS analyses. These findings support the existence of potentially toxic amyloid aggregates and suggest that BOLTS may be a useful analytic and diagnostic platform in the study of the amyloidoses or other diseases where abnormal molecular complexes are formed in serum

Blood Proteomic Profiling in Inherited (ATTRm) and Acquired (ATTRwt) Forms of Transthyretin-Associated Cardiac Amyloidosis

Transthyretin-associated forms of cardiac amyloidosis are fatal protein misfolding diseases that can be inherited (ATTRm) or acquired (ATTRwt). An accurate diagnosis of ATTR amyloidosis can be challenging as biopsy evidence, usually from the affected organ, is required. Precise biomarkers for ATTR disease identification and monitoring are undiscovered, disease-specific therapeutic options are needed, and the current understanding of ATTR molecular pathogenesis is limited. The aim of this study was to investigate and compare the serum proteomes in ATTRm and ATTRwt cardiac amyloidosis to identify differentially expressed blood proteins that were disease-specific. Using multiple-reaction monitoring mass spectrometry (MRM-MS), the concentrations of 160 proteins were analyzed in serum samples from ATTRm and ATTRwt patients, and a healthy control group. Patient and control sera were matched to age (≥60 years), gender (male), and race (Caucasian). The circulating concentrations of 123/160 proteins were significantly different in patient vs control sera; TTR and retinol-binding protein (RBP4) levels were significantly decreased (<i>p</i> < 0.03) in ATTRm compared to controls. In ATTRm, 14/123 proteins were identified as unique to that group and found generally to be lower than controls; moreover, the concentrations of RBP4 and 6 other proteins in this group were significantly different (<i>p</i> < 0.04) compared to ATTRwt. Predicted interactions among the 14 proteins unique to ATTRm were categorized as <i>reaction</i> and <i>binding</i> associations. Alternatively, 27 proteins were found to be unique to ATTRwt with associated interactions defined as <i>activation</i>, <i>catalysis</i>, and <i>inhibition</i>, in addition to <i>reaction</i> and <i>binding</i>. This study demonstrates significant proteomic differences between ATTR patient and control sera, and disease-associated variations in circulating levels of several proteins including TTR and RBP4. The identification of serum proteins unique to ATTRm and ATTRwt cardiac amyloidosis may have diagnostic and prognostic utility, and may provide important clues about disease mechanisms

Spontaneous rupture of the liver in a patient with systemic AL amyloidosis undergoing treatment with high-dose melphalan and autologous stem cell transplantation: A case report with literature review

Sunday School entry, view from the south, depicting use of vertical masonry walls to mark entry; In spite of the visual and spatial diversity of Wright's late work, it is possible to identify two common characteristics of this period: surfaces became smooth or lightly textured, with ornament virtually eliminated; and innovative geometric planning grids, incorporating triangles, hexagons and circles, were introduced to generate unusually shaped interior volumes as well as exterior forms. Triangular grids, for example, became the planning module for as many as 100 homes designed between 1936 and 1959 and also for such non-residential buildings as the First Unitarian Church (1947-1951), Shorewood Hills [now Madison], WI, which has a dramatic triangular roof of acute pitch over the sanctuary. [Grove Art Online] "Until the mid-nineteen forties the First Unitarian Society of Madison met in a late 19th century church near Capitol Square but the growth of their congregation necessitated a larger building. Wright's father had been a founding member of the Society and Frank Lloyd Wright, also a member, was the obvious, though not unanimous choice as the architect for the new meeting house. This new structure was built in a scarcely populated hilly area west of downtown Madison, allowing Wright to design a building coordinated with the site. Because of various cost over runs the congregation helped with the actual work, in particular hauling limestone from a nearby quarry. The economic problems this building created were probably worth it since the AIA has designated it as one of Wright's most important buildings and it is on the National Register of Historic Places. The one-floor meeting house is constructed of native limestone, copper, and glass; it is roofed in copper. The original plan is one long wing (running east-west) with an entrance at one short end and a "prow" protruding northward on the north long side, which is the main feature of the auditorium. The meeting house also includes a social area, kitchen, offices, and classrooms." Source: Digital Imaging Project, Mary Ann Sullivan, Bluffton University; http://www.bluffton.edu/~sullivanm/ (accessed 7/14/2008