¶ title: Sirtuin Pathway Dysfunction Validation in Parkinson's Disease
description: Multi-phase study to validate sirtuin pathway dysfunction as disease mechanism and test NAD+ repletion/sirtuin modulation as disease-modifying therapy
published: true
tags: kind:experiment, section:experiments, state:published, parkinson, sirtuin, NAD+, clinical-trial
editor: markdown
dateCreated: "2026-03-28T02:30:00.000Z"
dateUpdated: "2026-03-28T02:30:00.000Z"
refs:
schutz2024:
title: NAD+ metabolism in neurodegenerative diseases
pmid: "31155018"
hades2024:
title: NAD+ repletion rescues mitochondrial function in Parkinson's disease
pmid: "31740891"
tyrrell2023:
title: SIRT1 activity is reduced in PD patient-derived neurons
pmid: "30659479"
chen2019:
title: SIRT2 inhibition protects against alpha-synuclein toxicity
pmid: "24631280"
li2015:
title: SIRT3 overexpression protects dopaminergic neurons
pmid: "25933439"
yang2013:
title: Resveratrol and neuroprotection in PD models
pmid: "23792933"
¶ Sirtuin Pathway Dysfunction Validation in Parkinson's Disease
¶ Relationship to NADAPT Study
This validation protocol is designed to complement and extend the findings from the NADAPT Study (NCT06162013), a Phase 2 clinical trial evaluating NAD+ precursor supplementation in Parkinsonian syndromes. While NADAPT focuses on therapeutic intervention, this study focuses on mechanistic validation of sirtuin pathway dysfunction as the underlying biological mechanism.
¶ Experiment Overview
Experiment ID: SIRTUIN-PD-001
Hypothesis: Sirtuin pathway dysfunction drives dopaminergic neurodegeneration through impaired NAD+-dependent deacetylation, leading to mitochondrial dysfunction, neuroinflammation, and alpha-synuclein aggregation.
Primary Objective: Validate sirtuin pathway dysfunction as a disease mechanism in PD and assess NAD+ repletion and sirtuin modulation as disease-modifying therapeutic strategies.
Study Design: Multi-phase (biomarker → Phase II clinical), aligned with NADAPT framework
¶ Phase 1: Preclinical Validation (12 months)
¶ 1.1 In Vitro Studies
A. Human iPSC-Derived Dopaminergic Neurons
- Model: iPSCs from PD patients (LRRK2 G2019S, idiopathic) vs. healthy controls
- Endpoints:
- NAD+ levels (enzymatic assay)
- SIRT1, SIRT3 activity (fluorometric kits)
- Mitochondrial function (Seahorse XF)
- Alpha-synuclein aggregation (pSer129 ELISA)
- Cell viability after stress (MTT)
- Hypothesis: PD neurons will show reduced NAD+, impaired sirtuin activity, and increased vulnerability to oxidative stress
B. Sirtuin Knockout/Overexpression in Dopaminergic Cells
- Cell lines: SH-SY5Y, rat primary dopaminergic neurons
- Genetic manipulation:
- SIRT1 CRISPR KO vs. overexpression
- SIRT3 CRISPR KO vs. overexpression
- SIRT2 CRISPR KO
- Endpoints:
- Mitochondrial parameters (mtDNA copy number, Complex I activity)
- Oxidative stress markers (MitoSOX, 4-HNE)
- Autophagy flux (LC3-II/LC3-I ratio, p62)
- Alpha-synuclein aggregation (Thioflavin-T, pSer129)
¶ 1.2 In Vivo Studies
A. MPTP Mouse Model
- Animals: C57BL/6 mice (male, 10-12 weeks)
- Groups (n=15 per group):
- Vehicle control
- MPTP only (30mg/kg × 5 days)
- MPTP + Nicotinamide riboside (NR, 400mg/kg/day, p.o.)
- MPTP + SRT2104 (SIRT1 activator, 100mg/kg/day, p.o.)
- MPTP + SRT1720 (SIRT3 activator, 50mg/kg/day, p.o.)
- MPTP + SIRT2 inhibitor (AGK2, 10mg/kg/day, i.p.)
- Duration: 4 weeks post-MPTP
- Endpoints:
- Behavioral: open field, cylinder test, rotarod
- Biochemical: TH+ neuron count in SNc (IHC), striatal dopamine (HPLC)
- Molecular: NAD+ levels, sirtuin activity, mitochondrial function
- Biomarkers: blood NAD+, CSF NAD+ (in subset)
B. Alpha-Synuclein Preformed Fibril (PFF) Model
- Animals: C57BL/6 mice (male, 10-12 weeks)
- Groups (n=15 per group):
- Vehicle + PBS
- PFF only
- PFF + NR (400mg/kg/day)
- PFF + SRT2104 (100mg/kg/day)
- Duration: 12 weeks post-PFF
- Endpoints:
- Behavioral tests
- Alpha-synuclein pSer129 pathology (IHC)
- Neuroinflammation (Iba1, GFAP IHC)
- Mitochondrial function in isolated mitochondria
¶ 1.3 Mechanism Elucidation
- RNA-seq: SNc from treated vs. control mice (pathway enrichment: mitochondrial biogenesis, autophagy, inflammation)
- Proteomics: Mitochondrial and nuclear fractions
- Metabolomics: Brain tissue, blood, and CSF (NAD+ metabolome)
- Acetyl-proteomics: Global acetylation changes in response to treatment
¶ Phase 2: Clinical Biomarker Study (6 months)
¶ 2.1 Cross-Sectional Biomarker Assessment
Cohort: 150 participants
| Group | N | Criteria |
|---|---|---|
| PD patients (early, H&Y 1-2) | 70 | Diagnosis <2 years, not on NAD+ supplements |
| PD patients (advanced, H&Y 3-4) | 50 | Disease duration >5 years |
| Healthy controls | 30 | Age-matched, no neurological disease |
Endpoints:
-
Blood NAD+ Panel:
- NAD+ and NADH levels (whole blood, plasma)
- NMN, NR, nicotinamide levels
- Metabolomics profile
-
Sirtuin Activity in PBMCs:
- SIRT1 deacetylase activity
- SIRT3 deacetylase activity
- Protein expression (WB)
-
Mitochondrial Function (in PBMC-derived neutrophils):
- Complex I activity
- ROS production (MitoSOX)
- mtDNA copy number
-
Clinical Correlation:
- MDS-UPDRS parts I-III
- MoCA
- Levodopa equivalent dose
- Disease duration
¶ Phase 3: Clinical Trial (18 months)
¶ 3.1 Phase II Trial: NAD+ Repletion in PD
Design: Randomized, double-blind, placebo-controlled
Cohort: 120 participants
| Arm | N | Intervention |
|---|---|---|
| Placebo | 40 | Matching placebo |
| Low-dose NR | 40 | NR 500mg BID |
| High-dose NR | 40 | NR 1000mg BID |
Inclusion Criteria:
- PD diagnosis
years - H&Y 1-2.5
- Age 40-75
- Not on NAD+ supplements
Endpoints:
Primary:
- Change in MDS-UPDRS part III at 12 months
- Blood NAD+ levels at 3 months
Secondary:
- Change in MDS-UPDRS parts I, II, IV
- MoCA score
- CSF biomarkers (subset, n=40): NAD+, alpha-synuclein, tau, neurofilament
- Safety: adverse events, lab values
Exploratory:
- PET imaging: [18F]FDG for brain metabolism
- Actigraphy for sleep/activity
- Quality of life (PDQ-39)
¶ Biomarker Development
¶ Primary Biomarkers
| Biomarker | Matrix | Assay | Purpose |
|---|---|---|---|
| NAD+ | Blood | Enzymatic | Enrollment, response |
| NAD+/NADH ratio | Blood, CSF | HPLC/LC-MS | Disease status |
| NMN | Blood | LC-MS | NAD+ precursor |
| SIRT1 activity | PBMCs | Fluorometric | Target engagement |
| SIRT3 activity | PBMCs | Fluorometric | Target engagement |
¶ Secondary Biomarkers
| Biomarker | Matrix | Assay | Purpose |
|---|---|---|---|
| pSer129 α-syn | CSF | ELISA | Target pathway |
| Neurofilament light | CSF | ELISA | Neurodegeneration |
| mtDNA copy number | Blood | qPCR | Mitochondrial health |
| Complex I activity | PBMCs | Enzymatic | Mitochondrial function |
¶ Statistical Analysis
¶ Power Calculations
For Phase II trial (MDS-UPDRS part III):
- Effect size: 5 points (SD=10)
- Power: 80%, α=0.05 (two-tailed)
- Required n: 100 (accounting for 20% dropout)
¶ Analysis Plan
- Primary: Mixed-model ANOVA for repeated measures
- Biomarker: Correlation (Pearson/Spearman) with clinical outcomes
¶ Timeline
| Phase | Duration | Milestone |
|---|---|---|
| Phase 1 | 12 months | Preclinical validation complete |
| Phase 2 | 6 months | Biomarker study complete |
| Phase 3 | 18 months | Phase II trial complete |
| Total | 36 months | Full validation |
¶ Budget Estimate
| Item | Cost (USD) |
|---|---|
| Phase 1 (preclinical) | $800,000 |
| Phase 2 (biomarker) | $400,000 |
| Phase 3 (Phase II trial) | $2,500,000 |
| Regulatory | $300,000 |
| Total | $4,000,000 |
¶ Cross-References
- NADAPT Study (NCT06162013) - NAD Replenishment Therapy — Parallel Phase 2 clinical trial
- Sirtuin Pathway Dysfunction Hypothesis — Theoretical framework
- NAD+ Metabolism Pathway — Metabolic basis
- SIRT1 Gene — Master regulator, PGC-1α/FOXO3a
- SIRT2 Gene — Cytosolic, α-tubulin/α-synuclein
- SIRT3 Gene — Mitochondrial, MnSOD/Complex I
- NAD+ Precursors in Neurodegeneration — Therapeutic approach
- Sirtuin Modulators — Drug candidates
¶ References
- NAD+ metabolism in neurodegenerative diseases (2019)
- NAD+ repletion rescues mitochondrial function in PD (2019)
- SIRT1 activity is reduced in PD patient-derived neurons (2018)
- SIRT2 inhibition protects against α-synuclein toxicity (2014)
- SIRT3 overexpression protects dopaminergic neurons (2015)
- Resveratrol and neuroprotection in PD models (2013)
- SIRT1 genetic variants and PD risk (2019)
- NCT06162013 - The NADAPT Study