Dataset Information

Cell Damage in Light Chain Amyloidosis: FIBRIL INTERNALIZATION, TOXICITY AND CELL-MEDIATED SEEDING.

ABSTRACT: Light chain (AL) amyloidosis is an incurable human disease characterized by the misfolding, aggregation, and systemic deposition of amyloid composed of immunoglobulin light chains (LC). This work describes our studies on potential mechanisms of AL cytotoxicity. We have studied the internalization of AL soluble proteins and amyloid fibrils into human AC16 cardiomyocytes by using real time live cell image analysis. Our results show how external amyloid aggregates rapidly surround the cells and act as a recruitment point for soluble protein, triggering the amyloid fibril elongation. Soluble protein and external aggregates are internalized into AC16 cells via macropinocytosis. AL amyloid fibrils are shown to be highly cytotoxic at low concentrations. Additionally, caspase assays revealed soluble protein induces apoptosis, demonstrating different cytotoxic mechanisms between soluble protein and amyloid aggregates. This study emphasizes the complex immunoglobulin light chain-cell interactions that result in fibril internalization, protein recruitment, and cytotoxicity that may occur in AL amyloidosis.

SUBMITTER: Marin-Argany M

PROVIDER: S-EPMC5025671 | biostudies-literature | 2016 Sep

REPOSITORIES: biostudies-literature

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Cell Damage in Light Chain Amyloidosis: FIBRIL INTERNALIZATION, TOXICITY AND CELL-MEDIATED SEEDING.

Marin-Argany Marta M Lin Yi Y Misra Pinaki P Williams Angela A Wall Jonathan S JS Howell Kyle G KG Elsbernd Laura R LR McClure Megan M Ramirez-Alvarado Marina M

The Journal of biological chemistry 20160726 38

Light chain (AL) amyloidosis is an incurable human disease characterized by the misfolding, aggregation, and systemic deposition of amyloid composed of immunoglobulin light chains (LC). This work describes our studies on potential mechanisms of AL cytotoxicity. We have studied the internalization of AL soluble proteins and amyloid fibrils into human AC16 cardiomyocytes by using real time live cell image analysis. Our results show how external amyloid aggregates rapidly surround the cells and act ...[more]

PMID: 27462073

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Project description:ObjectiveTo identify changes in the proteome associated with onset and progression of hereditary transthyretin-mediated (hATTR) amyloidosis, also known as ATTRv amyloidosis, we performed an observational, case-controlled study that compared proteomes of patients with ATTRv amyloidosis and healthy controls.MethodsPlasma levels of >1,000 proteins were measured in patients with ATTRv amyloidosis with polyneuropathy who received either placebo or patisiran in a Phase 3 study of patisiran (APOLLO), and in healthy controls. The effect of patisiran on the time profile of each protein was determined by linear mixed model at 0, 9, and 18 months. Neurofilament light chain (NfL) was further assessed with an orthogonal quantitative approach.ResultsLevels of 66 proteins were significantly changed with patisiran vs placebo, with NfL change most significant (p < 10-20). Analysis of changes in protein levels demonstrated that the proteome of patients treated with patisiran trended toward that of healthy controls at 18 months. Healthy controls' NfL levels were 4-fold lower than in patients with ATTRv amyloidosis with polyneuropathy (16.3 pg/mL vs 69.4 pg/mL, effect -53.1 pg/mL [95% confidence interval -60.5 to -45.9]). NfL levels at 18 months increased with placebo (99.5 pg/mL vs 63.2 pg/mL, effect 36.3 pg/mL [16.5-56.1]) and decreased with patisiran treatment (48.8 pg/mL vs 72.1 pg/mL, effect -23.3 pg/mL [-33.4 to -13.1]) from baseline. At 18 months, improvement in modified Neuropathy Impairment Score +7 score after patisiran treatment significantly correlated with reduced NfL (R = 0.43 [0.29-0.55]).ConclusionsFindings suggest that NfL may serve as a biomarker of nerve damage and polyneuropathy in ATTRv amyloidosis, enable earlier diagnosis of patients with ATTRv amyloidosis, and facilitate monitoring of disease progression.Classification of evidenceThis study provides Class III evidence that NfL levels may enable earlier diagnosis of polyneuropathy in patients with ATTRv amyloidosis and facilitate monitoring of disease progression.

Project description:The role of extracellular ?-synuclein (?-syn) in the initiation and the spreading of neurodegeneration in Parkinson's disease (PD) has been studied extensively over the past 10 years. However, the nature of the ?-syn toxic species and the molecular mechanisms by which they may contribute to neuronal cell loss remain controversial. In this study, we show that fully characterized recombinant monomeric, fibrillar or stabilized forms of oligomeric ?-syn do not trigger significant cell death when added individually to neuroblastoma cell lines. However, a mixture of preformed fibrils (PFFs) with monomeric ?-syn becomes toxic under conditions that promote their growth and amyloid formation. In hippocampal primary neurons and ex vivo hippocampal slice cultures, ?-syn PFFs are capable of inducing a moderate toxicity over time that is greatly exacerbated upon promoting fibril growth by addition of monomeric ?-syn. The causal relationship between ?-syn aggregation and cellular toxicity was further investigated by assessing the effect of inhibiting fibrillization on ?-syn-induced cell death. Remarkably, our data show that blocking fibril growth by treatment with known pharmacological inhibitor of ?-syn fibrillization (Tolcapone) or replacing monomeric ?-syn by monomeric ?-synuclein in ?-syn mixture composition prevent ?-syn-induced toxicity in both neuroblastoma cell lines and hippocampal primary neurons. We demonstrate that exogenously added ?-syn fibrils bind to the plasma membrane and serve as nucleation sites for the formation of ?-syn fibrils and promote the accumulation and internalization of these aggregates that in turn activate both the extrinsic and intrinsic apoptotic cell death pathways in our cellular models. Our results support the hypothesis that ongoing aggregation and fibrillization of extracellular ?-syn play central roles in ?-syn extracellular toxicity, and suggest that inhibiting fibril growth and seeding capacity constitute a viable strategy for protecting against ?-syn-induced toxicity and slowing the progression of neurodegeneration in PD and other synucleinopathies.

Dataset Information

Cell Damage in Light Chain Amyloidosis: FIBRIL INTERNALIZATION, TOXICITY AND CELL-MEDIATED SEEDING.

Publications

Cell Damage in Light Chain Amyloidosis: FIBRIL INTERNALIZATION, TOXICITY AND CELL-MEDIATED SEEDING.

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