Perspective: Low Risk of Parkinson's Disease in Quasi-Vegan Cultures May Reflect GCN2-Mediated Upregulation of Parkin

The Role of Diet in Parkinson's Disease

The aim of this review is to examine the intersection of Parkinson's disease (PD) with nutrition, to identify best nutritional practices based on current evidence, and to identify gaps in the evidence and suggest future directions. Epidemiological work has linked various dietary patterns and food groups to changes in PD risk; however, fewer studies have evaluated the role of various diets, dietary components, and supplements in the management of established PD. There is substantial interest in exploring the role of diet-related interventions in both symptomatic management and potential disease modification. In this paper, we evaluate the utility of several dietary patterns, including the Mediterranean (MeDi), Mediterranean-DASH Intervention for Neurodegenerative Delay (MIND), Alternative Healthy Eating Index (AHEI), vegan/vegetarian, and ketogenic diet in persons with PD. Additionally, we provide an overview of the evidence relating several individual food groups and nutritional supplements to PD risk, symptoms and progression.

Exercise Improves the Coordination of the Mitochondrial Unfolded Protein Response and Mitophagy in Aging Skeletal Muscle

The mitochondrial unfolded protein response (UPRmt) and mitophagy are two mitochondrial quality control (MQC) systems that work at the molecular and organelle levels, respectively, to maintain mitochondrial homeostasis. Under stress conditions, these two processes are simultaneously activated and compensate for each other when one process is insufficient, indicating mechanistic coordination between the UPRmt and mitophagy that is likely controlled by common upstream signals. This review focuses on the molecular signals regulating this coordination and presents evidence showing that this coordination mechanism is impaired during aging and promoted by exercise. Furthermore, the bidirectional regulation of reactive oxygen species (ROS) and AMPK in modulating this mechanism is discussed. The hierarchical surveillance network of MQC can be targeted by exercise-derived ROS to attenuate aging, which offers a molecular basis for potential therapeutic interventions for sarcopenia.

The Role of Diet and Dietary Patterns in Parkinson's Disease

Parkinson's Disease (PD) is a neurodegenerative disorder associated with diminished nutrition status and decreased quality of life. While the prevalence of PD is expected to increase, no preventative or curative therapy for PD exists at this time. Although nutrition and diet represent modifiable risk factors for reducing chronic disease risk, research on the impact of single nutrients on PD has yielded mixed results. As a result, this single-nutrient approach may be the driving force behind the inconsistency, and a holistic dietary approach may overcome this inconsistency by accounting for the interactions between nutrients. The following review aims to examine the impact of a generally healthy dietary pattern, the protein-restricted diet (PRD), the ketogenic diet (KD), the Mediterranean diet (MD), and the Mediterranean-DASH Intervention for Neurodegenerative Delay (MIND) diet on PD risk, progression, and severity. While most of the included studies support the role of diet and dietary patterns in reducing the risk of PD or alleviating PD severity, the inconsistent results and need for further evidence necessitate more research being conducted before making dietary recommendations. Research on the potential beneficial effects of dietary patterns on PD should also investigate potential risks.

Inhibition of miR-421 Preserves Mitochondrial Function and Protects against Parkinson's Disease Pathogenesis via Pink1/Parkin-Dependent Mitophagy

Mutations in PINK1 and Parkin are a major cause of Parkinson's disease (PD) pathogenesis. In addition, PINK1 and Parkin are two mitochondrial proteins that jointly contribute to mitochondrial homeostasis via mitophagy. Mitochondrial dysfunction is the most significant mechanism underlying PD pathogenesis. Thus, understanding the regulatory mechanism of PINK1 and Parkin expression is beneficial to the treatment of PD. In this study, we found that miR-421 expression was upregulated in mice treated with MPTP, as well as in SH-SY5Y cells treated with methyl-4-phenylpyridine (MPP+). Inhibition of miR-421 alleviated neurodegeneration in MPTP-treated mice and promoted mitophagy in MPP+-treated SH-SY5Y cells. Bioinformatics software predicted that Pink1 is a downstream target protein of miR-421. In addition, miR-421-induced Pink1 and Parkin inhibition negatively modulates mitophagy in MPP+-treated SH-SY5Y cells. In addition, our study confirmed that Pink1/Parkin is responsible for miR-421-regulated cell mitophagy. Overall, this study revealed that miR-421 regulates nerve cell mitophagy through the Pink1/Parkin pathway.

Mitochondria-Microbiota Interaction in Neurodegeneration

Alzheimer’s and Parkinson’s are the two best-known neurodegenerative diseases. Each is associated with the excessive aggregation in the brain and elsewhere of its own characteristic amyloid proteins. Yet the two afflictions have much in common and often the same amyloids play a role in both. These amyloids need not be toxic and can help regulate bile secretion, synaptic plasticity, and immune defense. Moreover, when they do form toxic aggregates, amyloids typically harm not just patients but their pathogens too. A major port of entry for pathogens is the gut. Keeping the gut’s microbe community (microbiota) healthy and under control requires that our cells’ main energy producers (mitochondria) support the gut-blood barrier and immune system. As we age, these mitochondria eventually succumb to the corrosive byproducts they themselves release, our defenses break down, pathogens or their toxins break through, and the side effects of inflammation and amyloid aggregation become problematic. Although it gets most of the attention, local amyloid aggregation in the brain merely points to a bigger problem: the systemic breakdown of the entire human superorganism, exemplified by an interaction turning bad between mitochondria and microbiota.

Cross-Reactivity and Sequence Homology Between Alpha-Synuclein and Food Products: A Step Further for Parkinson's Disease Synucleinopathy

INTRODUCTION

Parkinson's disease is characterized by non-motor/motor dysfunction midbrain neuronal death and α-synuclein deposits. The accepted hypothesis is that unknown environmental factors induce α-synuclein accumulation in the brain via the enteric nervous system.

MATERIAL AND METHODS

Monoclonal antibodies made against recombinant α-synuclein protein or α-synuclein epitope 118-123 were applied to the antigens of 180 frequently consumed food products. The specificity of those antibody-antigen reactions was confirmed by serial dilution and inhibition studies. The Basic Local Alignment Search Tool sequence matching program was used for sequence homologies.

RESULTS

While the antibody made against recombinant α-synuclein reacted significantly with 86/180 specific food antigens, the antibody made against α-synuclein epitope 118-123 reacted with only 32/180 tested food antigens. The food proteins with the greatest number of peptides that matched with α-synuclein were yeast, soybean, latex hevein, wheat germ agglutinin, potato, peanut, bean agglutinin, pea lectin, shrimp, bromelain, and lentil lectin. Conclusions: The cross-reactivity and sequence homology between α-synuclein and frequently consumed foods, reinforces the autoimmune aspect of Parkinson's disease. It is hypothesized that luminal food peptides that share cross-reactive epitopes with human α-synuclein and have molecular similarity with brain antigens are involved in the synucleinopathy. The findings deserve further confirmation by extensive research.

The intestinal luminal sources of α-synuclein: a gastroenterologist perspective

Parkinson's disease is characterized by nonmotor/motor dysfunction, midbrain dopaminergic neuronal death, and α-synuclein (aSN) deposits. The current hypothesis is that aSN accumulates in the enteric nervous system to reach the brain. However, invertebrate, vertebrate, and nutritional sources of aSN reach the luminal compartment. Submitted to local amyloidogenic forces, the oligomerized proteins' cargo can be sensed and sampled by a specialized mucosal cell to be transmitted to the adjacent enteric nervous system, starting their upward journey to the brain. The present narrative review extends the current mucosal origin of Parkinson's disease, presenting the possibility that the disease starts in the intestinal lumen. If substantiated, eliminating the nutritional sources of aSN (eg, applying a vegetarian diet) might revolutionize the currently used dopaminergic pharmacologic therapy.

"Let Food Be Thy Medicine": Gluten and Potential Role in Neurodegeneration

Wheat is a most favored staple food worldwide and its major protein is gluten. It is involved in several gluten dependent diseases and lately was suggested to play a role in non-celiac autoimmune diseases. Its involvement in neurodegenerative conditions was recently suggested but no cause-and-effect relationship were established. The present narrative review expands on various aspects of the gluten-gut-brain axes events, mechanisms and pathways that connect wheat and gluten consumption to neurodegenerative disease. Gluten induced dysbiosis, increased intestinal permeabillity, enteric and systemic side effects, cross-reactive antibodies, and the sequence of homologies between brain antigens and gluten are highlighted. This combination may suggest molecular mimicry, alluding to some autoimmune aspects between gluten and neurodegenerative disease. The proverb of Hippocrates coined in 400 BC, "let food be thy medicine," is critically discussed in the frame of gluten and potential neurodegeneration evolvement.