Immune Activation in Functional Gastrointestinal Disorders.

Area of Science:

• Gastroenterology
• Immunology
• Microbiology

Background:

• Functional gastrointestinal disorders (FGIDs) are heterogeneous, with subtle gastrointestinal (GI) inflammation potentially linking subtypes like functional dyspepsia and irritable bowel syndrome.
• Despite similar symptoms, FGID patients exhibit variations in triggers and disease severity, suggesting underlying differences in disease mechanisms.
• A disruption in GI homeostasis, caused by factors like dysbiosis, impaired barrier function, or immune responses, is hypothesized to underlie the subtle inflammation in FGIDs.

Purpose of the Study:

• To discuss the complex interplay between the immune system, gut microbiota, and the luminal environment in the pathogenesis of FGIDs.
• To propose novel immune pathways, specifically T-helper type 17 responses and innate lymphoid cells, as potential key regulators of subtle GI inflammation in FGIDs.

Main Methods:

• Literature review and synthesis of current research on FGIDs, gut inflammation, and immune system involvement.
• Exploration of the relationship between GI homeostasis, microbiota, and immune responses.
• Identification and discussion of emerging immune pathways implicated in FGID pathogenesis.

Main Results:

• FGIDs are characterized by subtle GI inflammation, potentially stemming from a disturbed homeostatic balance.
• Factors contributing to this imbalance include microbial dysbiosis, compromised gut barrier integrity, genetic susceptibility, and immune reactions to luminal contents.
• Emerging evidence points to T-helper type 17 (Th17) cells and innate lymphoid cells (ILCs) as critical players in regulating the low-grade inflammation observed in FGIDs.

Conclusions:

• The subtle inflammation in FGIDs is intricately linked to the disruption of GI homeostasis.
• Understanding the roles of the immune system, microbiota, and luminal factors is crucial for FGID research.
• Investigating Th17 responses and ILCs offers promising avenues for future research into FGID mechanisms and potential therapeutic targets.