Table 2.

Summary of the effect of amino acid supplementation on IBD in animal models.

Amino Acids	Effects	Animal Models	References
Glutamine	↓body weight loss, colon edema, endothelial adhesion molecules, infiltrating Th cells, PSGL-1, LFA-1, CCR9	C57BL/6 mice; DSS	[10]
	↓epithelium injury and loss, mucosal hypoplasia	Sprague-Dawley rats; acetic acid	[60]
	↓disruption of colonic architecture, submucosal and serosal fibrosis, collagen Iα2, collagen III, TGFβ, phosphorylated Smad3, PDGF, CTGF	Wistar rats; TNBS	[17]
	↑HO-1, GSH ↓MDA, caspase-3, NF-κB	Wistar-albino rats; TNBS	[44]
	↑GSH ↓MDA, caspase-3	Wistar-albino rats; TNBS	[61]
	↓histopathological scores, cytosolic concentration of TBARS, hydroperoxide-initiated chemiluminescence, NF-κB, iNOS, COX-2	Wistars rats; acetic acid	[49]
	↓histopathological scores, cytosolic concentration of TBARS, hydroperoxide-initiated chemiluminescence, MPO, iNOS, COX-2, NF-κB, TNF-α, IFN-γ, phosphorylated forms of STAT1, STAT5, Akt	Wistar rats; TNBS	[62]
	↑Th22 and Treg cell expression ↓Th1/Th17-associated cytokine expression	C57BL/6 mice; DSS	[11]
	↓NF-κB, PI3K-Akt	ICR mice; DSS	[12]
	↑HSP25, HSP70 ↓diarrhea	Sprague-Dawley rats; DSS	[15]
	↓oxidative stress, ER stress, apoptosis	Wistar rats; TNBS	[45]
Glutamate	↑PCNA-positive cells, SOD, Bcl-2 ↓MDA, Bax, caspase-3, TNF-α, IL-1β	Sprague-Dawley rats; TNBS	[63]
Arginine	↑iNOS ↓mucosal permeability, number of MPO-positive neutrophils, and expression of pro-inflammatory cytokine and chemokine	iNOS−/− C57BL/6 mice; DSS	[14]
	↑T-SOD ↓Akt, MLCK	ICR mice; DSS	[12]
	↓body weight loss, colon weights, macroscopic and microscopic damage of colonic tissues	Wistar rats; acetic acid	[64]
Sulphur-containing amino acids	↓colon lesions, cytoskeleton damage, serum amyloid A, TNF-α	BALB/C mice; DSS	[27]
	↑caspase-8 ↓chemokine, neutrophil influx, TNF-α, IL-6, IL-12p40, IL-1β, cFLIP and Bcl-xL	Yorkshire piglets; DSS	[16]
	↑goblet cell number, protein/DNA ratio, claudin-1 ↓IEL number, caspase-3, MPO, MDA, TNF-α	piglets; acetic acid	[54]
	↑GSH, SOD, CAT ↓MPO, MDA	Wistar-albino rats; acetic acid	[65]
	↑PON1,GSH ↓macroscopic colonic damage, histopathologic changes, MPO, ROS, TNF-α, IL-1β	BALB/c mice; DSS	[26]
	↑GSH, SOD ↓MPO, MDA, TNF-α, IL-1β, IL-6	Wistar albino rats; acetic acid	[24]
	↓COX2, PGE2	Sprague-Dawley rats; TNBS	[18]
	↓chronic ulcerative colitis-associated colorectal adenocarcinoma development	C57BL/6J mice; DSS	[66]
Tryptophan	↓body weight loss, frequency of bloody stools, nitrotyrosine content of the colonic tissues	C57black6 mice; DSS	[67]
	↑caspase-8, Bax ↓gut permeability, TNF-α, IL-6, IFN-γ, IL-12p40, IL-1β, IL-17, IL-8, ICAM-1	Piglets; DSS	[68]
	↑Ahr, IL-22, STAT3 ↓colitis symptoms, IL-6, TNF-α, IL-1β, Ccl2, Cxcl1, Cxcl2	C57BL/6 WT and KO mice; DSS	[69]
Glycine	↓diarrhea, body weight loss, ulceration, MPO, IL-1β, TNF-α, CINC, MIP-2	Wistar rats; TNBS/DSS	[70]
Histidine	↓histologic damage, colon weight, TNF-α, IL-6, NF-κB	IL-10−/− mice	[71]

Ahr, aryl hydrocarbon receptor; Akt, protein kinase B; Bcl, B-cell lymphoma; Bax, Bcl-2-associated X protein; CAT, catalase; CCR9, C-C chemokine receptor type 9; cFLIP, FLICE-like inhibitory protein; CINC, cytokine-induced neutrophil chemoattractant; COX-2, cyclooxygenase-2; CTGF, connective tissue growth factor; DSS, dextran sulfate sodium; ER, endoplasmic reticulum; GSH, glutathione; HO-1, heme oxygenase-1; HSP, heat shock protein; ICAM-1, intracellular adhesion molecule-1; ICR, institute for cancer research; IEL, intraepithelial lymphocyte; IFN, interferon; IL, interleukin; iNOS, inducible nitric oxide synthase; LFA, leukocyte function-associated antigen; MDA, malondialdehyde; MIP-2, macrophage inflammatory protein-2; MLCK, myosin light chain kinase; MPO, myeloperoxidase; NF-κB, nuclear factor-κB; PCNA, proliferating cell nuclear antigen; PDGF, platelet-derived growth factor; PGE₂, prostaglandin E₂; PI3K, phosphoinositide-3-kinases; PON1, paraoxonase 1; PSGL, P-selectin glycoprotein ligand; ROS, reactive oxygen species; SOD, superoxide dismutase; STAT, signal transducers and activators of transcription; TBARS, thiobarbituric acid reactive substances; TGF-β, transforming growth factor-β; Th, T-helper; TNBS, trinitrobenzene sulfonic acid; TNF-α, tumor necrosis factor-α; Treg, T regulatory.