Age-associated decline in RAB-10 efficacy impairs intestinal barrier integrity

The small GTPase RAB-18 is involved in regulating development/diapause by recruiting the intestinal cholesterol transporter NCR-1 onto the apical side in Caenorhabditis elegans

RAB family proteins, which are small GTPases, are integral to the process of eukaryotic membrane trafficking. In the nematode, Caenorhabditis elegans, 31 RAB proteins have been identified through genome sequencing. Using an RNAi screen specifically targeting C. elegans rab genes, we identified multiple genes that are involved in the regulation of larval development, in particular, the rab-18 gene. Our molecular genetic studies resulted in several findings. First, RAB-18 predominantly functions in the intestine to regulate larval development by modulating steroid hormone signaling. Second, the C. elegans cholesterol transporter NCR-1 is a target of RAB-18 in the intestine. Third, the membrane trafficking of NCR-1 to the apical side in intestinal cells is particularly influenced by RAB-18. Finally, RAB-18 and NCR-1 possibly co-localize on membrane vesicles. Our study is the first to demonstrate the relationship between a RAB protein and a cholesterol transporter, in which the RAB protein probably drives the transporter to the apical membrane in the intestine to regulate cholesterol uptake. This study provides insight into the molecular mechanisms underlying human disease stemming from a transport defect of cholesterol and its derivative.

Entomopathogenic Bacillus cereus impairs the fitness of the spotted-wing drosophila, Drosophila suzukii

Drosophila suzukii is a notorious pest which causes devastating damage to thin-skinned fruits, and the larvae feed on the fruit, causing extensive agricultural economic loss. The current application of insecticides to manage this pest results in serious resistance and environmental hazards, so an alternative strategy for D. suzukii biocontrol is urgently needed. Here, we reported that entomopathogenic Bacillus cereus has the potential to biocontrol D. suzukii. We isolated and identified the bacterial strain, B. cereus H1, that was detrimental to the fitness of both D. suzukii progenies and parents. D. suzukii was robustly repelled to depositing eggs on the halves with metabolites of B. cereus H1. Both males and females of D. suzukii were susceptible to B. cereus H1. B. cereus H1 significantly arrested larval development with at least 40% lethal larvae. The median lethal time (LT50) of males and females of D. suzukii challenged with B. cereus H1 was 3 and 2 d, respectively. Moreover, B. cereus H1 disrupted the intestinal integrity and pH value of D. suzukii and resulted in an increase in bacterial load of guts and hemolymph. Mechanistically, infection of B. cereus H1 led to the activation of the dual oxidase (DUOX)-ROS-Jun N-terminal kinase (JNK) pathway. The findings showed that the entomopathogen B. cereus H1 could potentially act as a biological control agent against D. suzukii, advancing fundamental concepts of integrated pest management programs against D. suzukii.

Galacto-Oligosaccharides and the Elderly Gut: Implications for Immune Restoration and Health

The increasing prevalence of noncommunicable diseases in the aging population has been correlated with a decline in innate and adaptive immune responses; hence, it is imperative to identify approaches to improve immune function, prevent related disorders, and reduce or treat age-associated health complications. Prebiotic supplementation is a promising approach to modulate the gut microbiome and immune system, offering a potential strategy to maintain the integrity of immune function in older individuals. This review summarizes the current research on prebiotic galacto-oligosaccharide (GOS) immunomodulatory mechanisms mediated by bacterial-derived metabolites, including short-chain fatty acids and secondary bile acids, to maintain immune homeostasis. The potential applications of GOS as immunotherapy for age-related disease prevention in older individuals are also highlighted. This aligns with the global shift toward proactive healthcare and emphasizes the significance of early intervention in directing an individual's health trajectory.

Apple polysaccharide improves age-matched cognitive impairment and intestinal aging through microbiota-gut-brain axis

The Apple polysaccharides (AP), extracted from the fruit of apple, has been used to treat multiple pathological diseases. In this study, we evaluated the effects of AP on cognitive impairment and intestinal aging in naturally aging mice. As a result, it was found that AP could improve spatial learning and memory impairment in aging mice through the Morris water maze experiment. Additionally, AP intervention can upregulate the expression of nerve growth factor (BDNF), postsynaptic marker (PSD95), and presynaptic marker (SYP) proteins. Moreover, AP can enhance total antioxidant capacity, reduce the level of pro-inflammatory cytokine, and inhibit the activation of the NF-κB signaling pathway, exerting anti-inflammatory and antioxidant functions. And the administration of AP restored intestinal mucosal barrier function, reduced the expression of aging and apoptosis related proteins. The administration of AP also altered the gut microbiota of mice. At the genus level, AP decreased the abundance of Helicobacter and Bilophila, while increased the abundance of Lactobacillus and Bacteroides. In summary, these data demonstrate that AP treatment can alleviate cognitive impairment, oxidative stress, and inflammatory reactions, repair the intestinal mucosal barrier, reduce intestinal aging, and alter specific microbial characteristics, ultimately improving the health of the elderly.