Persistent Symptoms and IFN-γ-Mediated Pathways after COVID-19.

Area of Science:

• Immunology
• Metabolic Medicine
• Post-COVID Conditions

Background:

• Post-COVID-19 patients frequently report persistent symptoms like fatigue, neurological issues, and insomnia.
• Immune system dysregulation and altered amino acid metabolism are hypothesized contributors to these long-term effects.

Purpose of the Study:

• To investigate inflammatory markers and amino acid metabolism (tryptophan and phenylalanine) in patients with persistent symptoms after COVID-19.
• To explore the association between these metabolic changes, symptom persistence, and physical functioning.

Main Methods:

• Cross-sectional analysis of 142 patients approximately 60 days post-acute, PCR-confirmed COVID-19.
• Measurement of inflammatory parameters (neopterin, C-reactive protein) and amino acid levels/ratios (tryptophan, phenylalanine, tyrosine, kynurenine).
• Assessment of symptom persistence (pain, gastrointestinal issues, anosmia, sleep disturbance, neurological symptoms) and physical functioning.

Main Results:

• Over 48% of patients experienced persistent symptoms, with women affected more frequently.
• Elevated inflammatory markers (neopterin, CRP) and enhanced tryptophan catabolism were common.
• A higher phenylalanine/tyrosine ratio correlated with lower physical functioning in women; specific amino acid changes related to symptom improvement.

Conclusions:

• Women exhibit a higher prevalence of persistent symptoms post-COVID-19.
• Immune-mediated alterations in tryptophan and phenylalanine metabolism are associated with long-term symptoms and reduced physical functioning.
• These findings highlight the role of metabolic changes in the pathophysiology of post-COVID conditions.