Project description:Immunoglobulin light chain (LC) amyloidosis (AL) is one of the most common types of systemic amyloidosis. The lack of reliable in vivo models hinders the study of the disease in its physiological context. We developped a transgenic mouse model producing high amounts of a human AL free light chain (LC). While mice exceptionnaly develop spontaneous AL amyloidosis and do not exhibit organ toxicity due to the circulating amyloidogenic LC, a single injection of amyloid fibrils, made up of the variable domain (VL) of the human LC, or soluble VL led to amyloid deposits, mainly in heart. The biochemical composition and the fragmentation pattern of the LC in the fibrils are highly similar to that of human AL fibrils, arguing for a conserved mechanism of amyloid fibrils formation. Amyloidosis positive mice also develop an early cardiac dysfunction, with increased NT-proBNP, diastolic dysfunction and remodeling of the extracellular matrix. Overall, this transgenic mice closely reproduces human cardiac AL amyloidosis and shows that a partial degradation of the LC initiate amyloid fibril formations in vivo. Accumulation of AL amyloid fibrils, rather than the soluble LC, drive the initial cardiac dysfunction. This model fills an important gap for research on AL amyloidosis and preclinical evaluation of new therapies.
Project description:we investigated the N-glycosylation of the amyloid fibrils extracted from the heart of a patient affected by AL amyloidosis, using a proteomic approach to evaluate indirectly the presence of glycans in immunoglobulin light chains.
Project description:AL amyloidosis is a disorder characterized by expansion of clonal plasma cells in the bone marrow and distant end organ damage mediated by misfolded immunoglobulin free light chains. There are currently limited data regarding the functional characteristics of AL amyloidosis plasma cells and their surrounding bone marrow microenvironment. We performed 5’ single cell RNA sequencing on 9 newly diagnosed, treatment naive AL amyloidosis patients and 8 healthy subjects. We identified generalized suppression of normal bone marrow hematopoiesis with distinct expansion of CD16 monocytes and subsets of CD4+ T cells in AL amyloidosis patients. We detected significant transcriptional changes broadly occurring among immune cells with increased interferon α and γ response and decreased TNF-α signaling. T and B cell receptor profiling revealed no overt clonal expansion of B or T cells in AL amyloidosis patients. However, we noted a disproportionate expansion of a distinct population of non-malignant plasma cells in AL amyloidosis patients. Finally, clonal AL amyloidosis plasma cells were identified based on their unique VDJ rearrangement and they showed increased expression of genes involved in proteostasis and antigen processing when compared to autologous, polyclonal plasma cells. Inter-patient transcriptional heterogeneity was evident, with transcriptional states reflective of common genomic translocations easily identifiable. Overall, this study defines the transcriptional characteristics of AL amyloidosis plasma cells and their surrounding bone marrow microenvironment, identifying transcriptional signatures that serve as candidates in early diagnosis in larger studies, and potential molecular targets for therapy.
Project description:In this study, we successfully extracted and resolved the high-resolution structure of amyloid fibrils from biopsy sample obtained from a living AL patient using cryo-EM.
Project description:In this study, we successfully extracted and resolved the high-resolution structure of amyloid fibrils from abdominal fat biopsy sample obtained from a living AL patient using cryo-EM.
Project description:In this study, we successfully extracted and resolved the high-resolution structure of amyloid fibrils from abdominal fat biopsy sample obtained from a living AL patient using cryo-EM.
Project description:We investigated the N- and C-terminome of the LCs proteoforms in fibrils extracted from the hearts of a patient affected by AL amyloidosis, using a proteomic approach based on N- and C-terminal residues derivatization, followed by mapping of fragmentation sites on the structures of fibrillar LCs