Saad Nadeem

 Background: The research on Parkinson’s disease (PD) explores the intricate relationship between the gut microbiota, alpha-synuclein pathology, and neuroinflammation in disease progression.³ The general topic encompasses understanding how the gut-brain axis influences PD pathogenesis and potential therapeutic strategies.² Existing literature highlights gut dysbiosis’s impact on PD and alpha-synuclein’s role in neurodegeneration.³ However, gaps exist in elucidating the mechanisms linking the gut microbiome to PD development and progression.⁴ This literature review aims to bridge this knowledge gap by examining recent studies on the gut-brain connection in PD, alpha-synuclein research, and exploring novel therapeutic approaches targeting the microbiome.⁵ By addressing these gaps, this research contributes to developing personalized interventions for individuals with PD, emphasizing the importance of maintaining a healthy gut microbiome for overall well-being.

Objective: In this narrative review, we investigated the influence of the gut microbiome on alpha-synuclein aggregation and dissemination in Parkinson’s disease and explored the potential of targeted microbiome manipulation as an innovative therapeutic strategy.

Search Methods: An online search in the PubMed database was conducted from 2019 to 2024 using the following keywords: “gut microbiome”, “alpha-synuclein”, “Parkinson’s disease”, “gut-brain axis”.

Results: Lactobacillus plantarum PS128 administration rescued the rotenone-induced reduction in tyrosine hydroxylase-positive (TH+) dopaminergic neurons in the substantia nigra and striatum, indicating a neuroprotective effect.^3,4 Similarly, L. plantarum DP189 treatment led to a substantial reduction in alpha-synuclein aggravation in the substantia nigra of PD mice compared to controls, suggesting neuroprotective potential against PD-related pathology.⁶ Moreover, L. plantarum PS128 effectively suppressed glial cell hyperactivation and attenuated oxidative stress levels in the brain, both closely linked to alpha-synuclein pathology in PD.^3,4 These results underscore the therapeutic promise of Lactobacillus plantarum strains in modulating alpha-synuclein pathology and preserving dopaminergic neurons in PD models ^4,6 Researchers are advancing novel strategies to target alpha-synuclein aggregation and associated neurodegenerative processes in PD by unraveling the mechanisms underlying these probiotic effects.³ These insights contribute to developing tailored therapeutic interventions for PD, emphasizing the importance of microbiome-targeted approaches in addressing alpha-synuclein pathology and enhancing clinical outcomes.^3,4,6

Conclusions: The gut microbiome plays a crucial role in Parkinson’s disease pathogenesis, influencing alpha-synuclein aggregation.² Therapeutic strategies targeting the gut-brain axis aim to slow disease progression and improve outcomes.¹ Psychobiotics like Lactobacillus plantarum show promise in modulating gut-brain communication and reducing alpha-synuclein aggregation, offering innovative treatment avenues for Parkinson’s disease.^3,4

Works Cited:

1. Wallen ZD, Demirkan A, Twa G, et al. Metagenomics of Parkinson’s disease implicates the gut microbiome in multiple disease mechanisms. Nat Commun. 2022;13(1):6958. Published 2022 Nov 15. doi:10.1038/s41467-022-34667-x
2. Zhu M, Liu X, Ye Y, et al. Gut Microbiota: A Novel Therapeutic Target for Parkinson’s Disease. Front Immunol. 2022;13:937555. Published 2022 Jun 24. doi:10.3389/fimmu.2022.937555
3. Fitzgerald E, Murphy S, Martinson HA. Alpha-Synuclein Pathology and the Role of the Microbiota in Parkinson’s Disease. Front Neurosci. 2019;13:369. Published 2019 Apr 24. doi:10.3389/fnins.2019.00369
4. Singh Y, Trautwein C, Romani J, et al. Overexpression of human alpha-Synuclein leads to dysregulated microbiome/metabolites with ageing in a rat model of Parkinson disease. Mol Neurodegener. 2023;18(1):44. Published 2023 Jul 4. doi:10.1186/s13024-023-00628-1
5. Stockdale SR, Draper LA, O’Donovan SM, et al. Alpha-synuclein alters the faecal viromes of rats in a gut-initiated model of Parkinson’s disease. Commun Biol. 2021;4(1):1140. Published 2021 Sep 29. doi:10.1038/s42003-021-02666-1
6. King S. Parkinson’s and the gut – what do we know? what can we do? Invigorate Physical Therapy & Wellness. August 5, 2019. Accessed April 7, 2024. https://www.invigoratept.com/blog/parkinsons-gut-health-microbiome-what-do-we-know.
7. Jemastock. Parkinsons disease cartoon vector image on vectorstock. VectorStock. January 29, 2018. Accessed April 7, 2024. https://www.vectorstock.com/royalty-free-vector/parkinsons-disease-cartoon-vector-19753901.
8. Dr. Ananya Mandal M. Parkinson’s disease pathophysiology. News. July 4, 2023. Accessed April 7, 2024. https://www.news-medical.net/health/Parkinsons-Disease-Pathophysiology.aspx.