Chronic lung inflammation affects plasma amino acid concentrations in pigs

Area of Science:

• Animal Nutrition
• Immunology
• Biochemistry

Background:

• Inflammatory processes and immune responses significantly impact protein and amino acid (AA) requirements.
• Understanding these metabolic shifts is crucial for developing nutritional strategies to support growth and immune function simultaneously.

Purpose of the Study:

• To identify specific amino acids (AAs) whose metabolism is altered by chronic lung inflammation in a piglet model.
• To investigate the impact of inflammation on plasma AA concentrations and their utilization.

Main Methods:

• Six pairs of littermate piglets were used, with one receiving complete Freund's adjuvant (CFA) to induce inflammation and the other a saline control (CON).
• Piglets were pair-fed to control for feed intake variations.
• Plasma AA concentrations were measured in both fasted and fed states over 9 days, alongside body temperature, weight gain, and haptoglobin levels.

Main Results:

• CFA injection led to decreased food intake, increased body temperature, and elevated plasma haptoglobin.
• Plasma concentrations of tryptophan, glutamine, proline, glycine, tyrosine, ornithine, and total AAs were lower in CFA than CON pigs.
• Histidine levels were higher in CFA pigs, while serine, arginine, alanine, and asparagine were lower in the fed state only.
• Tryptophan was the only essential AA significantly lower in CFA pigs under both fasted and fed conditions.

Conclusions:

• Chronic lung inflammation differentially affects individual AA metabolism in piglets.
• Results suggest an increased utilization of certain AAs, potentially including tryptophan, during inflammation.
• Activation of tryptophan catabolism via indoleamine 2,3-dioxygenase is a plausible explanation for increased tryptophan utilization.