Functional Bowel Disorders Are Associated with a Central Immune Activation.

Area of Science:

• Neurogastroenterology
• Immunology
• Microbiome research

Background:

• High prevalence of gastrointestinal comorbidity in depression and neurological disorders suggests brain-gut axis involvement.
• Functional gastrointestinal disorders (FGID) are common in these patient groups, highlighting the need to understand underlying mechanisms.

Purpose of the Study:

• To explore associations between FGID and inflammatory markers in the central nervous system (CNS) and peripheral system.
• To investigate the role of tryptophan metabolism and gut microbiota in FGID associated with neurological conditions.

Main Methods:

• FGID classification using Rome III criteria and symptom severity assessed by IBS symptom severity score (IBS-SSS).
• Analysis of serum and cerebrospinal fluid (CSF) for interleukins (IL), chemokines, growth factors, tryptophan, and kynurenine.
• Fecal analysis for short-chain fatty acids (SCFA).

Main Results:

• Irritable Bowel Syndrome (IBS) associated with elevated CSF tryptophan and kynurenine, and reduced IL-10.
• IBS symptom severity correlated with increased CSF tumor necrosis factor and decreased IL-10.
• Fecal propionic acid minus butyric acid negatively associated with CSF IL-10.

Conclusions:

• FGID are linked to proinflammatory immune activation within the CNS.
• Disturbed tryptophan metabolism, potentially mediated by fecal microbiota, is associated with FGID.
• Findings suggest a significant role for the gut-brain axis in FGID pathogenesis.