Colonic mucosal α-synuclein lacks specificity as a biomarker for Parkinson diseaseAuthor Response

Integrated multi-omics profiling highlights the benefits of resveratrol hydroxypropyl-β-cyclodextrin inclusion complex for A53T transgenic mice through the microbiota-gut-brain axis

Parkinson's disease (PD) is a neurological disorder characterized by motor and gastrointestinal dysfunctions. Resveratrol is a potent antioxidant and anti-inflammatory phytoalexin known for its health-promoting benefits. However, little is known about its potential in treating PD by modulating the microbial gut-brain axis, and its clinical application has been limited due to poor water solubility, rapid metabolism, and limited systemic bioavailability. Our study aimed to evaluate the therapeutic potential of RHSD, a resveratrol-cyclodextrin inclusion complex, in treating PD through the gut-brain axis in human SNCA-transgenic (A53T) mice PD models. Building on our previous study, we prepared RHSD and compared its efficacy with uncoated resveratrol for PD treatment. The study results demonstrated that RHSD exhibited several advantages in improving motor function, alleviating cognitive impairment, restoring intestinal barrier function, and inhibiting neuropathy. Subsequently, a series of analyses, including fecal microbiota metagenomic sequencing, non-target metabolic assays, host transcriptome sequencing, and integrative analysis were performed to reveal the potential therapeutic pathways of RHSD in A53T mice. The metagenomic sequencing results indicated a significant increase in the levels of Lactobacillus murinus, Lactobacillus reuteri, Enterorhabduscaecimuris, Lactobacillus taiwanensis, and Lactobacillus animals following RHSD administration. Furthermore, metabolomics profiling showed that the levels of gut microbiome metabolites were reversed after RHSD treatment, and differential metabolites were significantly correlated with motor function and intestinal function in PD mice. The integrated analysis of microbial metabolites and host transcriptomics suggested that abnormal amino acid metabolism, mitochondrial dysfunction, oxidative stress, and neuroinflammation in the PD model were associated with the diffusion of abnormal metabolites. This study illustrates the profound impact of RHSD administration on rectifying gut microbiota dysbiosis and improving the A53T mouse model. Notably, we observed significant alterations in the proliferation and metabolism of multiple probiotic strains of Lactobacillus. Furthermore, our research supports the hypothesis that microbiota-related metabolites may regulate the transcription of host genes, including dopamine receptors and calcium stabilization. Consequently, our findings underscore the potential of RHSD as a promising therapeutic candidate for the treatment of PD through the modulation of several signaling pathways within the microbiota-gut-brain axis.

The Role of the Gut Microbiota in the Pathogenesis of Parkinson's Disease

It is well-recognized that the gut microbiota (GM) is crucial for gut function, metabolism, and energy cycles. The GM also has effects on neurological outcomes via many mechanisms, such as metabolite production and the gut-brain axis. Emerging evidence has gradually indicated that GM dysbiosis plays a role in several neurological diseases, such as Parkinson's disease (PD), Alzheimer's disease, depression, and multiple sclerosis. Several studies have observed that PD patients generally suffer from gastrointestinal disorders and GM dysbiosis prior to displaying motor symptoms, but the specific link between the GM and PD is not clearly understood. In this review, we aim to summarize what is known regarding the correlation between the GM and PD pathologies, including direct, and indirect evidence.

Similar α-Synuclein staining in the colon mucosa in patients with Parkinson's disease and controls

BACKGROUND

The gut is proposed as a starting point of idiopathic IPD, but the presence of α-synuclein in the IPD colon mucosa is debated.

OBJECTIVES

The objective of this study was to evaluate if α-synuclein in the colon mucosa can serve as a biomarker of IPD.

METHODS

Immunohistochemistry was used to locate and quantify in a blinded approach α-synuclein in the mucosa from biopsies of the right and left colon in 19 IPD patients and 8 controls.

RESULTS

Total α-synuclein was present in all but 1 IPD patients and in all controls; phosphorylated α-synuclein was present in all subjects. There was no intensity difference depending on disease status. Staining of total α-synuclein was stronger in the right colon (p = .04).

CONCLUSIONS

Conventional immunohistochemistry α-synuclein staining in colon mucosal biopsies cannot serve as a biomarker of idiopathic PD. These findings do not contradict the assumption of disease starting in the colon, and a colon segment-specific risk for disease initiation can still be hypothesized. © 2016 International Parkinson and Movement Disorder Society.

Multicenter Assessment of Immunohistochemical Methods for Pathological Alpha-Synuclein in Sigmoid Colon of Autopsied Parkinson's Disease and Control Subjects

BACKGROUND

Conflicting results from studies of Lewy-type α-synucleinopathy (LTS) in colonic biopsies of subjects with Parkinson's disease (PD) prompted a two-part multicenter assessment. The first assessment, now published (Acta Neuropathol Commun 4 : 35, 2016), examined archived colonic biopsies and found that none of the tested methods was adequately sensitive or specific.

OBJECTIVE

As the amount of nervous tissue in typical colonic biopsies may be insufficient, and the clinical diagnosis of PD not completely accurate, the objective of the current study was to use instead full-thickness sections of sigmoid colon from autopsy-proven PD and normal subjects.

METHODS

Seven different immunohistochemical (IHC) methods were used, employing five different primary antibodies and four different combinations of epitope exposure and signal development protocols. Specific staining was defined as being restricted to morphological features consistent with neuronal elements. Stained slides from each subject were independently categorized as being positive or negative for LTS, and their density semi-quantitatively graded, by four raters blinded to diagnosis.

RESULTS

Agreement and mean diagnostic performance varied markedly between raters. With the two most accurate raters, 5 methods achieved diagnostic accuracies of 70% or greater; one method had 100% accuracy and 100% inter-rater agreement. The submucosa had the highest prevalence of pathological LTS staining, followed by the muscularis and mucosa.

CONCLUSIONS

The major conclusion of this study is that, when sufficient submucosa and LTS is present, and when specific staining is defined as being consistent with neuronal morphology, adequately-trained raters may reliably distinguish PD colon from control using suitable IHC methods.

Can Biomarkers Help the Early Diagnosis of Parkinson's Disease?

Parkinson's disease (PD) is a complex neurodegenerative disease with progressive loss of dopamine neurons. PD patients usually manifest a series of motor and non-motor symptoms. In order to provide better early diagnosis and subsequent disease-modifying therapies for PD patients, there is an urgent need to identify sensitive and specific biomarkers. Biomarkers can be divided into four categories: clinical, imaging, biochemical, and genetic. Ideal biomarkers not only improve our understanding of PD pathogenesis and progression, but also provide benefits for early risk evaluation and clinical diagnosis of PD. Although many efforts have been made and several biomarkers have been extensively investigated, few if any have been found useful for early diagnosis. Here, we summarize recent developments in the discovered biomarkers of PD and discuss their merits and limitations for the early diagnosis of PD.

Structure, Distribution, and Genetic Profile of α-Synuclein and Their Potential Clinical Application in Parkinson's Disease

Parkinson’s disease (PD), the second most common neurodegenerative disorder after Alzheimer’s disease, is characterized by the loss of nigral dopaminergic neurons. PD leads to a series of clinical symptoms, including motor and non-motor disturbances. α-synuclein, the major component of Lewy bodies, is a hallmark lesion in PD. In this review, we concentrate on presenting the latest research on the structure, distribution, and function of α-synuclein, and its interactions with PD. We also summarize the clinic applications of α-synuclein, which suggest its use as a biomarker, and the latest progress in α-synuclein therapy.