Impacts of conditionally essential amino acids, cysteine, and tyrosine on intestinal inflammation in celiac disease

Celiac disease (CD) is a chronic autoimmune disorder characterized by gluten-induced intestinal inflammation, epithelial barrier dysfunction, and malabsorption of nutrients, including amino acids (AAs). While essential AAs have been extensively studied, the roles of conditionally essential amino acids (CEAAs), cysteine (Cys), and tyrosine (Tyr) in CD pathogenesis remain comparatively underexplored. This review synthesizes current evidence on the contributions of these AAs to intestinal barrier integrity, immune regulation, oxidative stress mitigation, and gut microbiota modulation in CD. Key findings indicate that asparagine (Asn), glycine (Gly), Cys, glutamate (Glu), aspartate (Asp), and glutamine (Gln) contribute to the reinforcement of intestinal barrier integrity. In parallel, Cys and Gly, along with Gln and Asp, play important roles in suppressing oxidative stress, while Gln and Asp have been shown to positively influence the composition and function of the gut microbiota. Serine (Ser) may contribute to gliadin-induced epithelial damage but could also have potential protective effects during treatment. Arginine (Arg), through its metabolism via the inducible nitric oxide synthase (iNOS) and arginase pathways, contributes to immune regulation. This review underscores the therapeutic potential of AAs as adjunctive targets to gluten-free diets (GFD), offering avenues for nutritional interventions, enzyme therapies, and biomarker development. A deeper understanding of AA-mediated mechanisms may pave the way for personalized management strategies to improve clinical outcomes in CD.