Inflammatory bowel disease (IBD) is a chronic relapsing - remitting inflammatory disease of the gastrointestinal tract, which has been classified into two subtypes: Crohn's disease (CD) and ulcerative colitis [1]. This disease has a profound impact on the physical well-being and overall quality of life, affecting both children and adults [2,3]. Common symptoms include weight loss, abdominal pain, rectal bleeding, anemia, diarrhea, and fatigue [4]. Management of IBD is complex and requires a comprehensive approach that includes pharmacological treatments, nutritional support, surgical interventions, and lifestyle modifications [5]. Among these treatments, nutritional therapy is an important aspect of IBD management. It focuses on correcting malnutrition, maintaining a balanced diet, and considering enteral nutrition.

Daily diet is often cited by the IBD as a trigger or modulator of symptoms, and there is a growing scientific interest in understanding the role it plays in disease management [6]. Although no specific diet has been universally endorsed for the treatment of IBD, certain dietary patterns and components have been associated with either exacerbating or alleviating symptoms [7]. The Western diet, characterized by high consumption of processed foods, sugars, fats, and meats, correlates with a higher incidence of in the stage of IBD onset and progression [8]. Conversely, diets rich in fruits, vegetables, and fiber are associated with a reduced risk of developing IBD [9]. The Mediterranean diet, which includes a high intake of plant-based foods, whole grains, and fish, along with moderate consumption of dairy and poultry, has been suggested to be beneficial for patients with IBD [10]. In short, nutritional dietary interventions have shown some efficacy in managing symptoms, although research findings are mixed, and further studies are required. In short, the primary functions of energy metabolism are production of ATP and regulation of both apoptosis and immune responses [11]. Disturbances of these functions have been noted in patients with IBD, indicating a significant connection between this disease and energy metabolism [12]. Intestinal cells of IBD patients have lower energy levels compared with cells from healthy subjects. Due to their normally high energy consumption, intestinal cells tend to be easily affected by declines in energy production [11,13]. It is worth noting that some amino acids play critical roles in the pathophysiology and management of IBD. Generally, IBD patients often suffer from malnutrition due to malabsorption and increased nutrient requirements. Amino acid-based formulas or peptide-based enteral nutrition can be used to support gut healing and provide essential nutrition. Some studies suggest that supplementation with specific amino acids, such as glutamine, may have protective effects on the gut barrier and potentially help in the management of IBD [14]. Glutamic acid is an intermediary in the cytokine chain reaction, which can reduce the level of inflammatory cytokines in the injured tissues and serum, suggesting that after the intake of glutamic acid, the chemotaxis and infiltration of lymphocytes at the injured site are reduced, thus contributing to the alleviation of intestinal injury. Leucine is involved in the regulation of immune function. Lack of leucine may result in damage to the animal's immune organs, including the thymus, spleen, and lymph nodes, as well as decreased levels of immune protein expression. In conclusion, certain amino acids play multifaceted roles in the pathophysiology of IBD and are essential components of both the disease process and its management.

Leucine-rich and glutamine-rich proteins or bioactive peptides are known to possess properties conducive to self-renewal and high differentiation potential, playing a crucial role in the repair and regeneration of damaged intestinal mucosal tissue. Glutamic acid has been recognized as integral to growth, development, metabolism, and various physiological and biochemical processes in both healthy and diseased states. As an essential amino acid, leucine is involved in maintaining the integrity of intestinal tight junctions; however, the molecular mechanisms responsible for its effects in the context of IBD have yet to be fully elucidated. This experimental study aims to further explore the roles and molecular mechanisms of leucine and glutamic acid in the regulation of intestinal tight junctions.