Effect of Yuzu (Citrus junos) Seed Limonoids and Spermine on Intestinal Microbiota and Hypothalamic Tissue in the Sandhoff Disease Mouse Model

Oral Ingestion of Yuzu Seed Oil Suppresses the Development of Atopic Dermatitis-like Skin Lesions in NC/Nga Mice

Long-term oral ingestion of unheated yuzu seed oil in humans reduces lipid peroxides in the blood. Moreover, yuzu seed oil contains limonin, which can induce antioxidant and anti-inflammatory effects by activating the transcription factor nuclear factor erythroid 2-related factor 2 (Nrf2). Previously, Nrf2 has been shown to reduce atopic dermatitis (AD). Therefore, we hypothesized that ingesting unheated yuzu seed oil can regulate AD through Nrf2. An AD model was established using NC/Nga mice through repeated local exposure to mite antigens. Unheated and purified yuzu seed oil (100 µL/mice) or water (control, 100 µL/mice) was administered orally once a day using a gastric cannula for rodents for 28 days. On day 28, mice in the unheated yuzu seed oil group exhibited significantly lower clinical skin severity scores and ear thickness than those in the purified yuzu seed oil and water groups. Serum histamine levels remained unaltered among the three AD-induced groups. Serum Dermatophagoides farina body (Dfb)-specific immunoglobulin E (IgE) levels were significantly lower in the unheated yuzu seed oil group. Oral ingestion of yuzu seed oil in NC/Nga AD model mice significantly suppressed dermatitis deterioration and decreased serum IgE levels. Clinical trials (n = 41) have already confirmed that unheated yuzu oil is safe for long-term intake, further suggesting its potential use in improving AD symptoms.

Targeting GM2 Ganglioside Accumulation in Dementia: Current Therapeutic Approaches and Future Directions

Dementia in neurodegenerative diseases, such as Alzheimer's disease (AD), Parkinson's disease (PD), and dementia with Lewy bodies (DLB) is a progressive neurological condition affecting millions worldwide. The amphiphilic molecule GM2 gangliosides are abundant in the human brain and play important roles in neuronal development, intercellular recognition, myelin stabilization, and signal transduction. GM2 ganglioside's degradation requires hexosaminidase A (HexA), a heterodimer composed of an α subunit encoded by HEXA and a β subunit encoded by HEXB. The hydrolysis of GM2 also requires a non-enzymatic protein, the GM2 activator protein (GM2-AP), encoded by GM2A. Pathogenic mutations of HEXA, HEXB, and GM2A are responsible for autosomal recessive diseases known as GM2 gangliosidosis, caused by the excessive intralysosomal accumulation of GM2 gangliosides. In AD, PD and DLB, GM2 ganglioside accumulation is reported to facilitate Aβ and α-synuclein aggregation into toxic oligomers and plaques through activation of downstream signaling pathways, such as protein kinase C (PKC) and oxidative stress factors. This review explored the potential role of GM2 ganglioside alteration in toxic protein aggregations and its related signaling pathways leading to neurodegenerative diseases. Further review explored potential therapeutic approaches, which include synthetic and phytomolecules targeting GM2 ganglioside accumulation in the brain, holding a promise for providing new and effective management for dementia.

Amelioration of Alzheimer's Disease by Gut-Pancreas-Liver-Brain Interaction in an App Knock-In Mouse Model

In this study, we observed disease progression, changes in the gut microbiota, and interactions among the brain, liver, pancreas, and intestine in a mouse model of Alzheimer's disease (AD), in addition to attempting to inhibit disease progression through the dietary supplementation of L-arginine and limonoids. Wild-type mice (WC) and AD mice were fed a normal diet (AC), a diet supplemented with L-arginine and limonoids (ALA), or a diet containing only limonoids (AL) for 12-64 weeks. The normal diet-fed WC and AC mice showed a decrease in the diversity of the gut microbiota, with an increase in the Firmicutes/Bacteroidetes ratio, and bacterial translocation. Considerable bacterial translocation to the pancreas and intense inflammation of the pancreas, liver, brain, and intestinal tissues were observed in the AC mice from alterations in the gut microbiota. The ALA diet or AL diet-fed mice showed increased diversity of the bacterial flora and suppressed oxidative stress and inflammatory responses in hepatocytes and pancreatic cells, bacterial translocation, and neurodegeneration of the brain. These findings suggest that L-arginine and limonoids help in maintaining the homeostasis of the gut microbiota, pancreas, liver, brain, and gut in AD mice.