In this episode, Jayson M. Antonio and Ronaldo P. Ferraris discuss their team’s recently published study, "Lacticaseibacillus rhamnosus GG-driven remodeling of arginine metabolism mitigates gut barrier dysfunction." The research reveals a novel probiotic-driven mechanism that links dietary tryptophan with host arginine metabolism. The probiotic Lacticaseibacillus rhamnosus GG, when combined with tryptophan, enhances gut barrier integrity by upregulating argininosuccinate lyase (ASL), a key enzyme in arginine biosynthesis. The study also identifies ASL downregulation and increased serum argininosuccinate levels in a mouse model of colitis, pointing to a promising target for precision probiotic therapies.   Lacticaseibacillus rhamnosus GG-driven remodeling of arginine metabolism mitigates gut barrier dysfunction Jayson M. Antonio, Yue Liu, Panan Suntornsaratoon, Abigail Jones, Jayanth Ambat, Ajitha Bala, Joshua Joby Kanattu, Juan Flores, Sheila Bandyopadhyay, Ravij Upadhyay, Jagannatham Naidu Bhupana, Xiaoyang Su, Wei Vivian Li, Nan Gao, and Ronaldo P. Ferraris American Journal of Physiology-Gastrointestinal and Liver Physiology 2025 329:1, G162-G185