Functions and Signaling Pathways of Amino Acids in Intestinal Inflammation

Table 2

The functions and signaling pathways of NEAAs in intestinal inflammation.

Amino acids	Functions	Signaling pathways	References
Glutamine	↑intestinal barrier, anti-inflammation, IgA; ↓proinflammatory cytokines	NF-κB, mTOR; MAPK/ERK	[87–94]
Cysteine	↑tight junctions, intestinal barrier, and homeostasis; ↓TNF-α, IL-1β, IL-6, and IL-8, oxidative stress	NF-κB, Nrf2; mTOR	[25, 45, 95, 96]
Glycine	↑intestinal mucosal barrier; ↓TNF-a, IL-1, and IL6, oxidative stress	NF-κB	[97–101]
Glutamate	↑intestinal mucosal barrier; ↓TNF-α, IL-1 and oxidative stress	Unclear	[102–104]
Proline	↑SOD, tight junction proteins	Unclear	[75, 105–107]
Aspartate/; asparagine	↑intestinal barrier function; ↓proinflammatory cytokines	NF-κB; MAPK	[55, 108–110]
Tyrosine	↑intestinal health and immune function	CaSR	[63]
Alanine	↑intestinal defense and protection function	Unclear	[63]
Serine	↑colonic protection, mucosal healing; ↑mucin synthesis, gut microbiota	Unclear	[75, 111]

Functions of NEAAs in intestinal inflammation mainly rely on NF-κB, Nrf2, MAPK, mTOR, and CaSR signaling pathways. NF-κB: nuclear factor-kappa-B; CaSR: calcium-sensing receptor; mTOR: mechanistic target of rapamycin; MAPK: mitogen-activated protein kinase; Nrf2: transcription factor NF-E2-related factor 2; SOD: superoxide dismutase.