Microbiome–Metabolomics Insights into the Brain–Gut Homeostasis of d -gal Induced Aging Mice To Reveal the Antiaging Effects of Lactoferrin and Its Digesta

Lactoferrin (LF) plays a positive role in attenuating aging. In this study, LF obtained using different processing methods (freeze-dried: F and spray-dried: S) and its gastrointestinal digesta (XF and XS) were supplemented in d-gal-induced mice to explore their antiaging effects. The results showed that LF and its digesta (LFs) effectively ameliorated cognitive decline. Mechanistically, LFs prevented neuronal and synaptic injury by restoring redox balance, inhibiting the activation of microglia and astrocytes, and activating the cAMP-response element binding protein (CREB)/brain-derived neurotrophic factor (BDNF) pathway. Additionally, LFs increased the tight junction proteins and mucin-2, regulated the gut microbiota, particularly enriching bacteria in Firmicutes and restoring the Firmicutes/Bacteroidota ratio to maintain intestinal homeostasis. Meanwhile, LFs altered phospholipids (PLs) and other metabolites involved in glycerophospholipid metabolism such as arachidonic acid. Correlation analysis showed a significant association among metabolites, microbiota, and behaviors. These results indicated that LF and especially its digesta exert antiaging effects through multitarget pathways involving neuronal protection, neuroinflammation suppression, and microbiota-gut-brain axis regulation.