Functional amino acids provide great potential for treating autophagy-related diseases by regulating autophagy. The purpose of the autophagy process is to remove unwanted cellular contents and to recycle nutrients, which is controlled by many factors. Disordered autophagy has been reported to be associated with various diseases, such as cancer, neurodegeneration, aging, and obesity. Autophagy cannot be directly controlled and dynamic amino acid levels are sufficient to regulate autophagy. To date, arginine, leucine, glutamine, and methionine are widely reported functional amino acids that regulate autophagy. As a signal relay station, mammalian target of rapamycin complex 1 (mTORC1) turns various amino acid signals into autophagy signaling pathways for functional amino acids. Deficiency or supplementation of functional amino acids can immediately regulate autophagy and is associated with autophagy-related disease. This review summarizes the mechanisms currently involved in autophagy and amino acid sensing, diverse signal transduction among functional amino acids and autophagy, and the therapeutic appeal of amino acids to autophagy-related diseases. We aim to provide a comprehensive overview of the mechanisms of amino acid regulation of autophagy and the role of functional amino acids in clinical autophagy-related diseases and to further convert these mechanisms into feasible therapeutic applications.

Piglet diarrhea caused by weaning stress will increase the mortality rate and seriously affect swine industry production efficiency. Probiotic supplementation has been reported to effectively alleviate weaning diarrhea by inhibiting the colonization of pathogenic microorganisms; however, the underlying mechanisms remain unclear. In this study, we isolated a strain of Bacillus velezensis and conducted a series of in vivo and in vitro experiments to explore its effects on weaned piglets. The piglets were fed for a 28-day period, and the results showed that dietary supplementation of B. velezensis 411 significantly alleviated weaning diarrhea (p = 0.019) and improved the average daily gain (ADG) of piglets throughout the experimental period (p = 0.004). The intestinal antioxidant capacity of piglets was also significantly enhanced. Whole-genome sequencing revealed that B. velezensis 411 contains a protein-encoding circular chromosome, which is involved in biological processes such as sporulation and antibiotic secretion. Supplementation with B. velezensis 411 significantly increased the abundance of Akkermansia in intestine samples and significantly decreased the abundance of pathogenic bacteria, including Escherichia coli and Staphylococcus aureus, in piglets (p < 0.05). The transcriptomic results suggest that B. velezensis 411 supplementation may alter the composition of intestinal microorganisms through regulating the expression of MPEG1. Collectively, dietary B. velezensis can relieve diarrhea in piglets and improve their production performance by influencing the antioxidant capacity of the intestines and the balance of the intestinal flora. This study provides valuable insights into the potential application of Bacillus velezensis in mitigating weaning-associated issues in piglets.

(1) This study explored Lacticaseibacillus rhamnosus MS27, a newly isolated strain, as a potential probiotic candidate for alleviating the onset and severity of ulcerative colitis (UC). (2) L. rhamnosus MS27 was isolated and subjected to biochemical identification, antibiotic sensitivity testing, and antibacterial activity assessment. Dextran sulfate sodium (DSS) colitis model mice were used to evaluate its alleviating effects. In this study, 16S rRNA microbiome and eukaryotes reference transcriptome analyses were conducted to investigate its impact on intestinal microbial ecology and potential molecular mechanisms. (3) L. rhamnosus MS27 exhibits high acid tolerance at pH 3.23 and maintains a high viable bacterial count for 24 h. It can utilize sucrose, lactose, maltose, inulin, esculin, salicin, and mannitol but not raffinose, and it is sensitive to carbenicillin, erythromycin, tetracycline, chloramphenicol, clindamycin, and penicillin. It effectively increases the abundance of beneficial microbes, particularly Akkermansia, Muribaculaceae, and Limosilactobacillus reuteri (p < 0.05), while significantly reducing microorganisms linked to human pathogens causing diarrhea and gastroenteritis (p < 0.05). Transcriptomic analysis demonstrated that the expression levels of Igkv16-104 and C1qtnf3 were significantly downregulated in the presence of L. rhamnosus MS27 treatment compared to DSS treatment alone (p < 0.05). Further analysis revealed significant differences in genes related to immune functions, antigen presentation, and immune cell markers, indicating potential protein–protein interaction networks, particularly among genes of the major histocompatibility complex (MHC). (4) L. rhamnosus MS27, as a novel strain, demonstrates a significant capacity to alleviate inflammatory phenotypes. L. rhamnosus MS27 exhibits distinctive metabolic characteristics in lactic acid utilization, acetic acid and oleic acid production. Furthermore, it contributes to systemic homeostasis regulation by modulating Turicibacter to link intestinal microbiota composition with host immune function.