Amyloid-Journal of Protein Folding Disorders最新文献

Background: Immunoglobulin light chain (LC) amyloidosis is a life-threatening disease complicated by vast numbers of patient-specific mutations. We explored 14 patient-derived and engineered proteins related to κ1-family germline genes IGKVLD-33*01 and IGKVLD-39*01.

Methods: Hydrogen-deuterium exchange mass spectrometry analysis of conformational dynamics in recombinant LCs and their fragments was integrated with studies of thermal stability, proteolytic susceptibility, amyloid formation and amyloidogenic sequence propensity. The results were mapped on the structures of native and fibrillary proteins.

Results: Proteins from two κ1 subfamilies showed unexpected differences. Compared to their germline counterparts, amyloid LC related to IGKVLD-33*01 was less stable and formed amyloid faster, whereas amyloid LC related to IGKVLD-39*01 had similar stability and formed amyloid slower, suggesting different major factors influencing amyloidogenesis. In 33*01-related amyloid LC, these factors involved destabilization of the native structure and probable stabilization of amyloid. The atypical behavior of 39*01-related amyloid LC stemmed from increased dynamics/exposure of amyloidogenic segments in βC'V and βEV that could initiate aggregation and decreased dynamics/exposure near the Cys23-Cys88 disulfide.

Conclusions: The results suggest distinct amyloidogenic pathways for closely related LCs and point to the complementarity-defining regions CDR1 and CDR3, linked via the conserved internal disulfide, as key factors in amyloid formation.

Background: Hereditary transthyretin (TTR) amyloidosis (ATTRv) initially presents as a polyneuropathy and/or a cardiomyopathy. Central nervous system (CNS) pathology in ATTRv amyloidosis, including focal neurological episodes, dementia, cerebrovascular bleeding, and seizures, appears around a decade later. Wild-type (WT) TTR amyloidosis (ATTRwt) causes a cardiomyopathy. CNS pathology risk likely also increases in these patients as cardiomyopathy progresses. Herein, we study tafamidis-mediated TTR kinetic stabilisation in cerebrospinal fluid (CSF).

Methods: Varying tafamidis concentrations (50-1000 nM) were added to CSF from healthy donors or ATTRv patients, and TTR stabilisation was measured via the decrease in dissociation rate.

Results: Tafamidis meglumine (Vyndaqel) can be dosed at 20 or 80 mg QD. The latter dose is bioequivalent to a 61 mg QD dose of tafamidis free acid (Vyndamax). The tafamidis CSF concentration in ATTRv patients on 20 mg Vyndaqel is ∼125 nM. By linear extrapolation, we expect a CSF concentration of ∼500 nM at the higher dose. When tafamidis is added to healthy donor CSF at 125 or 500 nM, the WT TTR dissociation rate decreases by 42% or 87%, respectively.

Conclusions: Tafamidis stabilises TTR in CSF to what is likely a clinically meaningful extent at CSF concentrations achieved by the normal tafamidis dosing regimen.

Background: Cytogenetic abnormalities are common in patients with amyloid light-chain (AL) amyloidosis; some are associated with poorer outcomes. This post hoc analysis of ANDROMEDA evaluated the impact of certain cytogenetic abnormalities on outcomes in this patient population.

Methods: Patients with newly diagnosed AL amyloidosis were randomised 1:1 to daratumumab, bortezomib, cyclophosphamide, and dexamethasone (D-VCd) or VCd. Outcomes were evaluated in the intent-to-treat (ITT) population and in patients with t(11;14), amp1q21, del13q14, and del17p13.

Results: Overall, 321 patients had cytogenetic testing (D-VCd, n = 155; VCd, n = 166); most common abnormalities were t(11;14) and amp1q21. At a median follow-up of 20.3 months, haematologic complete response rates were higher with D-VCd vs VCd across all cytogenetic subgroups and organ response rates were numerically higher with D-VCd vs VCd across most subgroups. Point estimates for hazard ratio of major organ deterioration-PFS and -EFS favoured D-VCd over VCd for all cytogenetic subgroups. Deep haematologic responses (involved minus uninvolved free light chains [FLC] <10 mg/L or involved FLC ≤20 mg/L) were seen in more patients with D-VCd than VCd in all ITT and t(11;14) cohorts.

Conclusions: These results support the use of D-VCd as standard of care in patients with newly diagnosed AL amyloidosis regardless of cytogenetic abnormalities.

Background: Systemic amyloidosis refers to a group of protein misfolding disorders characterized by the extracellular deposition of amyloid fibrils in organs and tissues. For reasons heretofore unknown, amyloid deposits are not recognized by the immune system, and progressive deposition leads to organ dysfunction.

Methods: In vitro and in vivo phagocytosis assays were performed to elucidate the impact of collagen and other amyloid associated proteins (eg serum amyloid p component and apolipoprotein E) had on amyloid phagocytosis. Immunohistochemical and histopathological staining regimens were employed to analyze collagen-amyloid interactions and immune responses.

Results: Histological analysis of amyloid-laden tissue indicated that collagen is intimately associated with amyloid deposits. We report that collagen inhibits phagocytosis of amyloid fibrils by macrophages. Treatment of 15 patient-derived amyloid extracts with collagenase significantly enhanced amyloid phagocytosis. Preclinical mouse studies indicated that collagenase treatment of amyloid extracts significantly enhanced clearance as compared to controls, coincident with increased immune cell infiltration of the subcutaneous amyloid lesion.

Conclusions: These data suggest that amyloid-associated collagen serves as a 'don't eat me' signal, thereby hindering clearance of amyloid. Targeted degradation of amyloid-associated collagen could result in innate immune cell recognition and clearance of pathologic amyloid deposits.

Introduction: The current treatment paradigm of AL amyloidosis lacks effective fibril-directed therapies. Doxycycline has been shown to have anti-fibril properties in preclinical models. In 2012, we reported that posttransplant prophylaxis with doxycycline was associated with improved survival compared to penicillin in patients with haematologic response. We provide here updated results after long-term follow up.

Methods: We included 553 patients who underwent transplant between July 24^th, 1996, and June 24^th, 2014. Doxycycline 100 mg daily was used for prophylaxis in patients with penicillin allergy; since 2013, doxycycline was used as the standard for prophylaxis. Prophylaxis was typically continued for a year after transplant.

Results: The median follow-up from transplant was 12.7 years. Doxycycline was used for prophylaxis in 33% of patients; the rest received penicillin. The median time to next treatment was 6.0 (95%CI; 4.4-8.8) years and 6.0 (95%CI; 4.9-7.1) years in the doxycycline and penicillin groups, respectively (p = .89). The median overall survival was 12.0 (95%CI: 11.0-19.6) years and 11.0 (95%CI: 9.6-12.7) years in the 2 groups, respectively (p = .17). There was a minimal trend towards improved survival with doxycycline among patients with ≥ very good partial response and among patients with organ response that was not statistically significant.

Conclusion: After long-term follow-up, there is no clear evidence to support benefit of doxycycline in the post-transplant setting.

Background: Very small case series of patients with apolipoprotein A1 (ApoA1) amyloidosis are available.

Methods: We described the clinical and echocardiographic characteristics of individuals with the pathogenic APOA1 variant Leu75Pro (p. Leu99Pro), referred for cardiac screening.

Results: We enrolled 189 subjects, 54% men, median age 55 years (interquartile range 42-67), 39% with concomitant renal disease and 31% with liver disease. Median left ventricular ejection fraction was 60% (55-66). Overall, these subjects did not show overt diastolic dysfunction nor left ventricular (LV) hypertrophy. Age correlated with interventricular septal (IVS) thickness (r = 0.484), LV mass index (r = 0.459), E/e' (r = 0.501), and right ventricular free wall thickness (r = 0.594) (all p < 0.001). Some individuals displayed red flags for cardiac amyloidosis (CA), and 14% met non-invasive criteria for CA. Twenty-nine subjects died over 5.8 years (4.1-8.0), with 10 deaths for cardiovascular causes. Individuals meeting echocardiographic criteria for CA had a much higher risk of all-cause death (p = 0.009), cardiovascular death (p = 0.001), cardiovascular death or heart failure (HF) hospitalisation (p < 0.001). Subjects with both renal and liver involvement had a more prominent cardiac involvement, and shortest survival.

Conclusions: Subjects with the APOA1 Leu75Pro variant displayed minor echocardiographic signs of cardiac involvement, but 14% met echocardiographic criteria for CA. Subjects with suspected CA had a worse outcome.

Introduction: Hereditary Transthyretin Amyloidosis is a rare, progressive and life-threatening systemic disease with predominant peripheral and autonomic nervous system involvement caused by mutation of the transthyretin protein. The most common TTR mutation regarding to ATTRv is a substitution of a Methionine for a Valine at position 30 that predisposes TTR to form aggregates and fibrils.

Methods: S100A8 protein levels were measured in plasma samples from ATTRV30M patients and healthy donors. Additionally, S100A8/9 levels were measured in Schwann cells after incubation with human WT or V30M TTR. Moreover, bone marrow derived macrophages of either genetic background were generated and the expression of S100A8/9 was measured in response to toll like receptors agonists.

Results: S100A8/A9 mRNA levels are decreased in HSF V30M mice as compared with the WT. Moreover, S100A8 protein levels were found downregulated in plasma samples from ATTRV30M patients. Furthermore, we provide evidence for a dysregulated S100 expression by Schwann cells in response to TTRV30M and by mutated macrophages in response to toll like receptors agonists.

Conclusion: The presence of TTRV30M impacts S100 expression, possibly contributing to the impaired immune activation of Schwann cells in nerves from ATTRV30M patients. This may be linked to the diminished immune cellular infiltration in these nerves, contributing in this way for the neuronal dysfunction present in the disease.

Background: By stabilizing transthyretin, tafamidis delays progression of amyloidosis due to transthyretin variant (ATTRv) and replaced liver transplantation (LT) as the first-line therapy. No study compared these two therapeutic strategies.

Methods: In a monocentric retrospective cohort analysis, patients with ATTRv amyloidosis treated with either tafamidis or LT were compared using a propensity score and a competing risk analysis for three endpoints: all-cause mortality, cardiac worsening (heart failure or cardiovascular death) and neurological worsening (worsening in PolyNeuropathy Disability score).

Results: 345 patients treated with tafamidis (n = 129) or LT (n = 216) were analyzed, and 144 patients were matched (72 patients in each group, median age 54 years, 60% carrying the V30M mutation, 81% of stage I, 69% with cardiac involvement, median follow-up: 68 months). Patients treated with tafamidis had longer survival than LT patients (HR: 0.35; p = .032). Conversely, they also presented a 3.0-fold higher risk of cardiac worsening and a 7.1-fold higher risk of neurological worsening (p = .0071 and p < .0001 respectively).

Conclusions: ATTRv amyloidosis patients treated with tafamidis would present a better survival but also a faster deterioration of their cardiac and neurological statuses as compared with LT. Further studies are needed to clarify the therapeutic strategy in ATTRv amyloidosis.