NCT06487975: Bacillus Subtilis Gut Microbiome Intervention for PD

NCT06487975: Bacillus Subtilis Gut Microbiome Intervention for Parkinson's Disease

Overview

NCT06487975 is a clinical trial investigating the effects of Bacillus Subtilis supplementation on Parkinson's disease (PD) biomarkers. Sponsored by the University of Edinburgh, this trial represents a growing interest in gut-brain axis therapies for neurodegenerative diseases. The study evaluates how modulation of the gut microbiome through probiotic supplementation may affect disease progression and biomarker profiles in PD patients. [@university]

This trial is part of a broader movement toward microbiome-based therapeutics in neurology, recognizing that the gut-brain axis plays a critical role in neurodegenerative processes. The rationale stems from observations that PD patients often exhibit gut dysfunction years before motor symptoms appear, suggesting that the microbiome may be both a therapeutic target and a source of disease biomarkers. [@braak2003]

Gut-Brain Axis in Parkinson's Disease

The gut-brain axis is a bidirectional communication network linking the central nervous system with the enteric nervous system. This connection involves neural, hormonal, and immunological pathways that allow gut microorganisms to influence brain function and behavior. In Parkinson's disease, this axis has emerged as a key player in disease pathogenesis and progression.

Enteric Nervous System and Alpha-Synuclein

NCT06487975: Bacillus Subtilis Gut Microbiome Intervention for Parkinson's Disease

Overview

NCT06487975 is a clinical trial investigating the effects of Bacillus Subtilis supplementation on Parkinson's disease (PD) biomarkers. Sponsored by the University of Edinburgh, this trial represents a growing interest in gut-brain axis therapies for neurodegenerative diseases. The study evaluates how modulation of the gut microbiome through probiotic supplementation may affect disease progression and biomarker profiles in PD patients. [@university]

This trial is part of a broader movement toward microbiome-based therapeutics in neurology, recognizing that the gut-brain axis plays a critical role in neurodegenerative processes. The rationale stems from observations that PD patients often exhibit gut dysfunction years before motor symptoms appear, suggesting that the microbiome may be both a therapeutic target and a source of disease biomarkers. [@braak2003]

Gut-Brain Axis in Parkinson's Disease

The gut-brain axis is a bidirectional communication network linking the central nervous system with the enteric nervous system. This connection involves neural, hormonal, and immunological pathways that allow gut microorganisms to influence brain function and behavior. In Parkinson's disease, this axis has emerged as a key player in disease pathogenesis and progression.

Enteric Nervous System and Alpha-Synuclein

The enteric nervous system (ENS), often called the "second brain," contains millions of neurons that line the gastrointestinal tract. Research has demonstrated that alpha-synuclein pathology can originate in the gut and propagate to the brain via the vagus nerve. This "body-first" hypothesis of PD pathogenesis suggests that misfolded alpha-synuclein initially forms in the gut and then travels retrogradely through vagal nerve fibers to the dorsal motor nucleus of the vagus and eventually to the substantia nigra. [@sampson2016]

Clinical Evidence for Gut Involvement

Multiple clinical observations support the gut-brain connection in PD:

• Constipation: Present in up to 80% of PD patients, often predating motor symptoms by years
• Small intestinal bacterial overgrowth (SIBO): More prevalent in PD patients
• Gut permeability: "Leaky gut" allows bacterial products to enter circulation
• Gastroparesis: Delayed gastric emptying affects medication absorption

Bacillus Subtilis: Mechanism of Action

Spore-Forming Probiotic Properties

Bacillus subtilis is a Gram-positive, spore-forming bacterium that has been used safely as a probiotic for decades. Its spore-forming ability allows it to survive the harsh acidic environment of the stomach and reach the intestines viable. Once in the gut, B. subtilis spores germinate and colonize the intestinal mucosa, exerting beneficial effects through multiple mechanisms.

Key properties of Bacillus subtilis as a probiotic include:

Short-Chain Fatty Acid Production

One of the primary mechanisms through which Bacillus subtilis may benefit Parkinson's disease patients is the production of short-chain fatty acids (SCFAs). These molecules, including butyrate, propionate, and acetate, are produced by bacterial fermentation of dietary fiber and serve as crucial energy sources for colonocytes and signaling molecules throughout the body.

Butyrate

Butyrate is particularly important for gut and brain health:

• Anti-inflammatory effects: Inhibits NF-κB signaling and reduces pro-inflammatory cytokine production
• Epithelial barrier maintenance: Strengthens gut barrier function and reduces permeability
• Neuroprotective properties: Crosses the blood-brain barrier and may protect neurons
• Histone deacetylase inhibition: Alters gene expression toward anti-inflammatory pathways

SCFAs and Neuroinflammation

In Parkinson's disease, neuroinflammation plays a critical role in dopaminergic neuron degeneration. SCFAs, particularly butyrate, have demonstrated anti-inflammatory effects in preclinical models:

• Reduced microglial activation
• Decreased pro-inflammatory cytokines (IL-1β, TNF-α, IL-6)
• Increased anti-inflammatory cytokines (IL-10)
• Protection of dopaminergic neurons in toxin-based PD models

Effects on Alpha-Synuclein

Preclinical research suggests that Bacillus subtilis may directly affect alpha-synuclein aggregation and toxicity:

• Reduced alpha-synuclein misfolding in cellular models
• Decreased肠道炎症-associated alpha-synuclein phosphorylation
• Improved gut motility in alpha-synuclein transgenic mice
• Modulation of gut microbiome composition to reduce pro-inflammatory taxa

Trial Design

Study Objectives

The primary objective of NCT06487975 is to evaluate the safety and efficacy of Bacillus subtilis supplementation on:

Participant Criteria

Inclusion criteria typically include:

• Diagnosis of Parkinson's disease (UK Brain Bank criteria)
• Hoehn & Yahr stage 1-3
• Stable PD medication for at least 4 weeks
• No significant cognitive impairment (MMSE > 24)
• No probiotic or antibiotic use within 4 weeks
• No gastrointestinal disorders

• Previous gastrointestinal surgery
• Active inflammatory bowel disease
• Immunosuppressive therapy
• Active cancer
• Significant liver or kidney disease

Intervention

Participants receive:

• Bacillus subtilis (specific strain and dose to be determined)
• Placebo control group
• Duration: Typically 12-52 weeks
• Administration: Oral supplementation

Outcome Measures

Primary Endpoints

• Change in MDS-UPDRS Part III (Motor) score
• Change in gut microbiome diversity indices
• Safety and tolerability (adverse events)

Secondary Endpoints

• Change in non-motor symptoms (NMS Scale, PDQ-39)
• Inflammatory biomarker levels
• SCFA concentrations in stool and plasma
• Alpha-synuclein aggregation markers
• Gastrointestinal symptom scores

Biomarkers Being Measured

Gut Microbiome Biomarkers

| Biomarker | Significance |
|-----------|-------------|
| Microbiome diversity (Shannon index) | Overall gut health |
| SCFA concentrations | Butyrate, propionate, acetate |
| Tight junction proteins | Gut barrier integrity |
| LPS levels | Systemic inflammation |

Inflammatory Biomarkers

| Biomarker | Relevance |
|-----------|-----------|
| IL-6 | Pro-inflammatory cytokine |
| TNF-α | Neuroinflammation marker |
| IL-1β | Inflammatory response |
| CRP | Systemic inflammation |
| IL-10 | Anti-inflammatory cytokine |

Neurological Biomarkers

| Biomarker | Description |
|-----------|-------------|
| Alpha-synuclein in CSF | Disease progression marker |
| Neurofilament light chain (NfL) | Neurodegeneration marker |
| Tau and p-tau | Alzheimer comorbidity |

Cross-Link: Gut Microbiome in Neurodegeneration

This trial builds on a growing body of evidence linking gut microbiome dysbiosis to neurodegenerative diseases. The Microbiome page provides comprehensive information about the trillions of microorganisms inhabiting the human gastrointestinal tract and their effects on systemic health.

Alzheimer's Disease and Microbiome

The gut-brain axis also plays a role in Alzheimer's disease (AD), where microbiome changes are associated with amyloid deposition and cognitive decline. Similar probiotic interventions are being explored for AD patients.

The Vagus Nerve Connection

The vagus nerve serves as the primary neural conduit between the gut and brain. Alpha-synuclein may travel along this nerve in a prion-like fashion, spreading pathology from the enteric nervous system to the central nervous system.

Clinical Implications

Potential Benefits

If successful, Bacillus subtilis supplementation could offer:

• Disease modification: Addressing upstream pathophysiology
• Complementary therapy: Working alongside dopaminergic medications
• Non-motor symptom relief: Improving GI symptoms, sleep, and mood
• Accessible treatment: Probiotics are generally safe and inexpensive

Challenges and Limitations

Several challenges face microbiome-based PD therapies:

• Individual variability: Gut microbiome composition varies significantly between individuals
• Strain-specific effects: Not all probiotic strains have equivalent effects
• Dosage optimization: Determining optimal dose and duration
• Long-term effects: Sustainability of benefits unknown

Other Microbiome Trials in PD

Several other trials are investigating microbiome modulation in PD:

| Trial | Intervention | Status |
|-------|-------------|--------|
| NCT03015311 | Fecal microbiota transplant | Recruiting |
| NCT04251468 | Probiotic blend | Completed |
| NCT04519294 | Synbiotic | Active |

Preclinical Studies

Animal models have provided the rationale for human trials:

• B. subtilis reduced alpha-synuclein aggregation in mice
• SCFA administration improved motor function in toxin models
• Fecal microbiota transfer from healthy donors improved PD symptoms
• [Parkinson's Disease — Main disease page](/genes/ar)
• [Microbiome — Gut bacteria overview](/companies/overview)
• [Alpha-Synuclein — Target protein](/genes/ar)
• [Neuroinflammation — Inflammatory mechanisms](/genes/nfl)
• [Gut-Microbiome-Targeted Therapeutic — Therapeutic approaches](/genes/ar)
• [Probiotic Therapeutics — Broader probiotic field](/genes/th)

Diagram: Gut-Brain Axis in Parkinson's Disease

External Links

• [ClinicalTrials.gov: NCT06487975](https://clinicaltrials.gov/study/NCT06487975)
• [University of Edinburgh Parkinson's Research](https://www.ed.ac.uk/)
• [Michael J. Fox Foundation - Microbiome Research](https://www.michaeljfox.org/)

References

Pathway Diagram

The following diagram shows the key molecular relationships involving NCT06487975: Bacillus Subtilis Gut Microbiome Intervention for PD discovered through SciDEX knowledge graph analysis: