Anticholinergic drugs interact with neuroprotective chaperone L-PGDS and modulate cytotoxicity of Aβ amyloids

Anticholinergic drugs can be used as a treatment for many diseases. However, anticholinergic drugs are also known for their cognition-related side effects. Recently, there has been an increasing number of reports indicating a positive association between exposure to anticholinergic drugs and Alzheimer's disease (AD). Our novel study provides evidence of interactions between two representative anticholinergic drugs [Chlorpheniramine (CPM), a common antihistamine, and Trazodone (TRD), an antidepressant] with neuroprotective amyloid-beta (Aβ) chaperone, lipocalin-type prostaglandin D synthase (L-PGDS) and the amyloid beta-peptide (1–40). Here, we demonstrate that CPM and TRD bind to L-PGDS with high affinity where chlorpheniramine exhibited higher inhibitory effects on L-PGDS as compared to Trazodone. We also show that the interactions between the drug molecules and Aβ(1–40) peptides result in a higher fibrillar content of Aβ(1–40) fibrils with altered fibril morphology. These altered fibrils possess higher cytotoxicity compared to Aβ(1–40) fibrils formed in the absence of the drugs. Overall, our data suggest a mechanistic link between exposure to anticholinergic drugs and increased risk of Alzheimer's disease via inhibition of the neuroprotective chaperone L-PGDS and direct modification of Aβ amyloid morphology and cytotoxicity.Ministry of Education (MOE)Nanyang Technological UniversityPublished versionThe research reported in this publication was supported by the Ministry of Education, AcRF Tier 2, Singapore under grant number M4020231 and funding is provided by Singapore Ministry of Education, AcRF Tier 1, ‘Structural basis of amyloid seeds disaggregation’ to K. P. under grant number of M4012175. Electron microscopy work was undertaken at the NTU Institute of Structural Biology Cryo-EM lab at Nanyang Technological University, Singapore. We thank P. Padmanabhan and Y. Xia for their assistance in MTT cell assays

Liquid-liquid phase separation of short histidine- and tyrosine-rich peptides: sequence specificity and molecular topology

The increasing realization of the prevalence of liquid-liquid phase separation (LLPS) across multiple length scales of biological constructs, from intracellular membraneless organelles to extracellular load-bearing tissues, has raised intriguing questions about intermolecular interactions regulating LLPS at the atomic level. Squid-beak derived histidine (His)- and tyrosine (Tyr)-rich peptides (HBpeps) have recently emerged as suitable short model peptides to precisely assess the roles of peptide motifs and single residues on the phase behavior and material properties of microdroplets obtained by LLPS. In this study, by systematically introducing single mutations in an HBpep, we have identified specific sticker residues that attract peptide chains together. We find that His and Tyr residues located near the sequence termini drive phase separation, forming interaction nodes that stabilize microdroplets. Combining quantum chemistry simulations with NMR studies, we predict atomic-level bond geometries and uncover inter-residue supramolecular interactions governing LLPS. These results are subsequently used to propose possible topological arrangements of the peptide chains, which upon expansion can help explain the three-dimensional network of microdroplets. The stability of the proposed topologies carried out through all-atom molecular dynamics simulations predicts chain topologies that are more likely to stabilize the microdroplets. Overall, this study provides useful guidelines for the de novo design of peptide coacervates with tunable phase behavior and material properties. In addition, the analysis of nanoscale topologies may pave the way to understand how client molecules can be trapped within microdroplets, with direct implications for the encapsulation and controlled release of therapeutics for drug delivery applications.Ministry of Education (MOE)This research was funded by the Singapore Ministry of Education (MOE) through an Academic Research Fund (AcRF) Tier 3 grant (grant no. MOE 2019-T3-1-012)

Release of frustration drives corneal amyloid disaggregation by brain chaperone

TGFBI-related corneal dystrophy (CD) is characterized by the accumulation of insoluble protein deposits in the corneal tissues, eventually leading to progressive corneal opacity. Here we show that ATP-independent amyloid-β chaperone L-PGDS can effectively disaggregate corneal amyloids in surgically excised human cornea of TGFBI-CD patients and release trapped amyloid hallmark proteins. Since the mechanism of amyloid disassembly by ATP-independent chaperones is unknown, we reconstructed atomic models of the amyloids self-assembled from TGFBIp-derived peptides and their complex with L-PGDS using cryo-EM and NMR. We show that L-PGDS specifically recognizes structurally frustrated regions in the amyloids and releases those frustrations. The released free energy increases the chaperone's binding affinity to amyloids, resulting in local restructuring and breakage of amyloids to protofibrils. Our mechanistic model provides insights into the alternative source of energy utilized by ATP-independent disaggregases and highlights the possibility of using these chaperones as treatment strategies for different types of amyloid-related diseases.Ministry of Education (MOE)Published versionThe work is supported by the Ministry of Education, Singapore, under its Academic Research Fund Tier 1 (RG28/19) and Academic Research Fund Tier 3 grant (Project ID: MOE2019-T3-1-012). The authors would like to acknowledge the funding support from SNEC-HREF R1429/12/2017 and SERI Lee –Foundation Pilot Grant R1586/85/ 2018 awarded to JSM and VA respectively. YM acknowledges Singapore MOE Tier 1 grant (RG27/21)

Health-status outcomes with invasive or conservative care in coronary disease

BACKGROUND In the ISCHEMIA trial, an invasive strategy with angiographic assessment and revascularization did not reduce clinical events among patients with stable ischemic heart disease and moderate or severe ischemia. A secondary objective of the trial was to assess angina-related health status among these patients. METHODS We assessed angina-related symptoms, function, and quality of life with the Seattle Angina Questionnaire (SAQ) at randomization, at months 1.5, 3, and 6, and every 6 months thereafter in participants who had been randomly assigned to an invasive treatment strategy (2295 participants) or a conservative strategy (2322). Mixed-effects cumulative probability models within a Bayesian framework were used to estimate differences between the treatment groups. The primary outcome of this health-status analysis was the SAQ summary score (scores range from 0 to 100, with higher scores indicating better health status). All analyses were performed in the overall population and according to baseline angina frequency. RESULTS At baseline, 35% of patients reported having no angina in the previous month. SAQ summary scores increased in both treatment groups, with increases at 3, 12, and 36 months that were 4.1 points (95% credible interval, 3.2 to 5.0), 4.2 points (95% credible interval, 3.3 to 5.1), and 2.9 points (95% credible interval, 2.2 to 3.7) higher with the invasive strategy than with the conservative strategy. Differences were larger among participants who had more frequent angina at baseline (8.5 vs. 0.1 points at 3 months and 5.3 vs. 1.2 points at 36 months among participants with daily or weekly angina as compared with no angina). CONCLUSIONS In the overall trial population with moderate or severe ischemia, which included 35% of participants without angina at baseline, patients randomly assigned to the invasive strategy had greater improvement in angina-related health status than those assigned to the conservative strategy. The modest mean differences favoring the invasive strategy in the overall group reflected minimal differences among asymptomatic patients and larger differences among patients who had had angina at baseline

Initial invasive or conservative strategy for stable coronary disease

BACKGROUND Among patients with stable coronary disease and moderate or severe ischemia, whether clinical outcomes are better in those who receive an invasive intervention plus medical therapy than in those who receive medical therapy alone is uncertain. METHODS We randomly assigned 5179 patients with moderate or severe ischemia to an initial invasive strategy (angiography and revascularization when feasible) and medical therapy or to an initial conservative strategy of medical therapy alone and angiography if medical therapy failed. The primary outcome was a composite of death from cardiovascular causes, myocardial infarction, or hospitalization for unstable angina, heart failure, or resuscitated cardiac arrest. A key secondary outcome was death from cardiovascular causes or myocardial infarction. RESULTS Over a median of 3.2 years, 318 primary outcome events occurred in the invasive-strategy group and 352 occurred in the conservative-strategy group. At 6 months, the cumulative event rate was 5.3% in the invasive-strategy group and 3.4% in the conservative-strategy group (difference, 1.9 percentage points; 95% confidence interval [CI], 0.8 to 3.0); at 5 years, the cumulative event rate was 16.4% and 18.2%, respectively (difference, 121.8 percentage points; 95% CI, 124.7 to 1.0). Results were similar with respect to the key secondary outcome. The incidence of the primary outcome was sensitive to the definition of myocardial infarction; a secondary analysis yielded more procedural myocardial infarctions of uncertain clinical importance. There were 145 deaths in the invasive-strategy group and 144 deaths in the conservative-strategy group (hazard ratio, 1.05; 95% CI, 0.83 to 1.32). CONCLUSIONS Among patients with stable coronary disease and moderate or severe ischemia, we did not find evidence that an initial invasive strategy, as compared with an initial conservative strategy, reduced the risk of ischemic cardiovascular events or death from any cause over a median of 3.2 years. The trial findings were sensitive to the definition of myocardial infarction that was used