Exploring the multifactorial aspects of Gut Microbiome in Parkinson's Disease

Pesticides and the Gut Microbiota: Implications for Parkinson's Disease

Parkinson's disease (PD) affects more people worldwide than just aging alone can explain. This is likely due to environmental influences, genetic makeup, and changes in daily habits. The disease develops in a complex way, with movement problems caused by Lewy bodies and the loss of dopamine-producing neurons. Some research suggests Lewy bodies might start in the gut, hinting at a connection between these structures and gut health in PD patients. These patients often have different gut bacteria and metabolites. Pesticides are known to increase the risk of PD, with evidence showing they harm more than just dopamine neurons. Long-term exposure to pesticides in food might affect the gut barrier, gut bacteria, and the blood-brain barrier, but the exact link is still unknown. This review looks at how pesticides and gut bacteria separately influence PD development and progression, highlighting the harmful effects of pesticides and changes in gut bacteria. We have examined the interaction between pesticides and gut bacteria in PD patients, summarizing how pesticides cause imbalances in gut bacteria, the resulting changes, and their overall effects on the PD prognosis.

From the Gut to the Brain: Is Microbiota a New Paradigm in Parkinson's Disease Treatment?

Parkinson's disease (PD) is recognized as the second most prevalent primary chronic neurodegenerative disorder of the central nervous system. Clinically, PD is characterized as a movement disorder, exhibiting an incidence and mortality rate that is increasing faster than any other neurological condition. In recent years, there has been a growing interest concerning the role of the gut microbiota in the etiology and pathophysiology of PD. The establishment of a brain-gut microbiota axis is now real, with evidence denoting a bidirectional communication between the brain and the gut microbiota through metabolic, immune, neuronal, and endocrine mechanisms and pathways. Among these, the vagus nerve represents the most direct form of communication between the brain and the gut. Given the potential interactions between bacteria and drugs, it has been observed that the therapies for PD can have an impact on the composition of the microbiota. Therefore, in the scope of the present review, we will discuss the current understanding of gut microbiota on PD and whether this may be a new paradigm for treating this devastating disease.

Dysbiosis of the Beneficial Gut Bacteria in Patients with Parkinson's Disease from India

Objectives

Recent advancement in understanding neurological disorders has revealed the involvement of dysbiosis of the gut microbiota in the pathophysiology of Parkinson's disease (PD). We sequenced microbial DNA using fecal samples collected from PD cases and healthy controls (HCs) to evaluate the role of gut microbiota.

Methods

Full-length bacterial 16S rRNA gene sequencing of fecal samples was performed using amplified polymerase chain reaction (PCR) products on the GridION Nanopore sequencer. Sequenced data were analyzed using web-based tools BugSeq and MicrobiomeAnalyst.

Results

We found that certain bacterial families like Clostridia UCG 014, Cristensenellaceae, and Oscillospiraceae are higher in abundance, and Lachinospiracea, Coriobacteriaceae and genera associated with short-chain fatty acid production, Faecalibacterium, Fusicatenibacter, Roseburia and Blautia, are lower in abundance among PD cases when compared with the HC. Genus Akkermansia, Dialister, Bacteroides, and Lachnospiraceae NK4A136 group positively correlated with constipation in PD.

Conclusion

Observations from this study support the other global research on the PD gut microbiome background and provide fresh insight into the gut microbial composition of PD patients from a south Indian population. We report a higher abundance of Clostridia UCG 014 group, previously not linked to PD.

New Pieces for an Old Puzzle: Approaching Parkinson's Disease from Translatable Animal Models, Gut Microbiota Modulation, and Lipidomics

Parkinson's disease (PD) is a severe neurodegenerative disease characterized by disabling motor alterations that are diagnosed at a relatively late stage in its development, and non-motor symptoms, including those affecting the gastrointestinal tract (mainly constipation), which start much earlier than the motor symptoms. Remarkably, current treatments only reduce motor symptoms, not without important drawbacks (relatively low efficiency and impactful side effects). Thus, new approaches are needed to halt PD progression and, possibly, to prevent its development, including new therapeutic strategies that target PD etiopathogeny and new biomarkers. Our aim was to review some of these new approaches. Although PD is complex and heterogeneous, compelling evidence suggests it might have a gastrointestinal origin, at least in a significant number of patients, and findings in recently developed animal models strongly support this hypothesis. Furthermore, the modulation of the gut microbiome, mainly through probiotics, is being tested to improve motor and non-motor symptoms and even to prevent PD. Finally, lipidomics has emerged as a useful tool to identify lipid biomarkers that may help analyze PD progression and treatment efficacy in a personalized manner, although, as of today, it has only scarcely been applied to monitor gut motility, dysbiosis, and probiotic effects in PD. Altogether, these new pieces should be helpful in solving the old puzzle of PD.

Gut Microbiota in Autophagy Regulation: New Therapeutic Perspective in Neurodegeneration

Gut microbiota and the brain are related via a complex bidirectional interconnective network. Thus, intestinal homeostasis is a crucial factor for the brain, as it can control the environment of the central nervous system and play a significant role in disease progression. The link between neuropsychological behavior or neurodegeneration and gut dysbiosis is well established, but many involved pathways remain unknown. Accumulating studies showed that metabolites derived from gut microbiota are involved in the autophagy activation of various organs, including the brain, one of the major pathways of the protein clearance system that is essential for protein aggregate clearance. On the other hand, some metabolites are evidenced to disrupt the autophagy process, which can be a modulator of neurodegeneration. However, the detailed mechanism of autophagy regulation by gut microbiota remains elusive, and little research only focused on that. Here we tried to evaluate the crosstalk between gut microbiota metabolites and impaired autophagy of the central nervous system in neurodegeneration and the key to future research regarding gut dysbiosis and compromised autophagy in neurodegenerative diseases.

Role of enteric glia and microbiota-gut-brain axis in parkinson disease pathogenesis

The microbiota-gut-brain axis or simple gut-brain axis (GBA) is a complex and interactive bidirectional communication network linking the gut to the brain. Alterations in the composition of the gut microbiome have been linked to GBA dysfunction, central nervous system (CNS) inflammation, and dopaminergic degeneration, as those occurring in Parkinson's disease (PD). Besides inflammation, the activation of brain microglia is known to play a central role in the damage of dopaminergic neurons. Inflammation is attributed to the toxic effect of aggregated α-synuclein, in the brain of PD patients. It has been suggested that the α-synuclein misfolding might begin in the gut and spread "prion-like", via the vagus nerve into the lower brainstem and ultimately to the midbrain, known as the Braak hypothesis. In this review, we discuss how the microbiota-gut-brain axis and environmental influences interact with the immune system to promote a pro-inflammatory state that is involved in the initiation and progression of misfolded α-synuclein proteins and the beginning of the early non-motor symptoms of PD. Furthermore, we describe a speculative bidirectional model that explains how the enteric glia is involved in the initiation and spreading of inflammation, epithelial barrier disruption, and α-synuclein misfolding, finally reaching the central nervous system and contributing to neuroinflammatory processes involved with the initial non-motor symptoms of PD.

Chalcone Derivatives with a High Potential as Multifunctional Antioxidant Neuroprotectors

A systematic, rational search for chalcone derivatives with multifunctional behavior has been carried out, with the support of a computer-assisted protocol (CADMA-Chem). A total of 568 derivatives were constructed by incorporating functional groups into the chalcone structure. Selection scores were calculated from ADME properties, toxicity, and manufacturability descriptors. They were used to select a subset of molecules (23) with the best drug-like behavior. Reactivity indices were calculated for this subset. They were chosen to account for electron and hydrogen atom donating capabilities, which are key processes for antioxidant activity. The indexes showed that four chalcone derivatives (dCHA-279, dCHA-568, dCHA-553, and dCHA-283) are better electron and H donors than the parent molecule and some reference antioxidants (Trolox, ascorbic acid, and α-tocopherol). In addition, based on molecular docking, they are predicted to act as catechol-O-methyltransferase (COMT), acetylcholinesterase (AChE), and monoamine oxidase B (MAO-B) inhibitors. Therefore, these four molecules are proposed as promising candidates to act as multifunctional antioxidants with neuroprotective effects.

CADMA-Chem: A Computational Protocol Based on Chemical Properties Aimed to Design Multifunctional Antioxidants

A computational protocol aimed to design new antioxidants with versatile behavior is presented. It is called Computer-Assisted Design of Multifunctional Antioxidants and is based on chemical properties (CADMA-Chem). The desired multi-functionality consists of in different methods of antioxidant protection combined with neuroprotection, although the protocol can also be used to pursue other health benefits. The dM38 melatonin derivative is used as a study case to illustrate the protocol in detail. This was found to be a highly promising candidate for the treatment of neurodegeneration, in particular Parkinson's and Alzheimer's diseases. This also has the desired properties of an oral-drug, which is significantly better than Trolox for scavenging free radicals, and has chelates redox metals, prevents the ●OH production, via Fenton-like reactions, repairs oxidative damage in biomolecules (lipids, proteins, and DNA), and acts as a polygenic neuroprotector by inhibiting catechol-O-methyl transferase (COMT), acetylcholinesterase (AChE) and monoamine oxidase B (MAOB). To the best of our best knowledge, CADMA-Chem is currently the only protocol that simultaneously involves the analyses of drug-like behavior, toxicity, manufacturability, versatile antioxidant protection, and receptor-ligand binding affinities. It is expected to provide a starting point that helps to accelerate the discovery of oral drugs with the potential to prevent, or slow down, multifactorial human health disorders.

Flavonoids bridging the gut and the brain: intestinal metabolic fate, and direct or indirect effects of natural supporters against neuroinflammation and neurodegeneration

In recent years, experimental evidence suggested a possible role of the gut microbiota in the onset and development of several neurodegenerative disorders, such as AD and PD, MS and pain. Flavonoids, including anthocyanins, EGCG, the flavonol quercetin, and isoflavones, are plant polyphenolic secondary metabolites that have shown therapeutic potential for the treatment of various pathological conditions, including neurodegenerative diseases. This is due to their antioxidant and anti-inflammatory properties, despite their low bioavailability which often limits their use in clinical practice. In more recent years it has been demonstrated that flavonoids are metabolized by specific bacterial strains in the gut to produce their active metabolites. On the other way round, both naturally-occurring flavonoids and their metabolites promote or limit the proliferation of specific bacterial strains, thus profoundly affecting the composition of the gut microbiota which in turn modifies its ability to further metabolize flavonoids. Thus, understanding the best way of acting on this virtuous circle is of utmost importance to develop innovative approaches to many brain disorders. In this review, we summarize some of the most recent advances in preclinical and clinical research on the neuroinflammatory and neuroprotective effects of flavonoids on AD, PD, MS and pain, with a specific focus on their mechanisms of action including possible interactions with the gut microbiota, to emphasize the potential exploitation of dietary flavonoids as adjuvants in the treatment of these pathological conditions.