187. Intestinal Mycobiome | Small Intestinal Fungal Overgrowth, Biofilm Formation & Microbial Persistence, and Intestinal Barrier Integrity

In this episode, we detail Small Intestinal Fungal Overgrowth (SIFO), with a focus on fungal biofilm formation and its role in promoting microbial persistence and evasion of host immune responses. We discuss the phenotypic plasticity of Candida species, as well as biofilm matrices adherent to the intestinal mucosa. We further highlight common symptoms of SIFO as well as the effects of hypochlorhydria, reduced pancreatic enzyme and bile output, impaired motility, diminished commensal bacterial populations, and weakened mucosal immunity.

Topics:

1. Introduction

- Focus on the gut mucosal barrier.

- Emphasis on Small Intestinal Fungal Overgrowth (SIFO) and biofilms.

2. Intestinal Barrier Anatomy

- The mucosa: epithelium, lamina propria, and a thin band of smooth muscle.

- The epithelial layer.

- Covered by protective mucus composed of mucin glycoproteins secreted by goblet cells.

- In the small intestine: less dense mucus.

3. Epithelial Integrity

- Tight junctions.

- Paracellular barrier preventing uncontrolled antigen passage.

4. Lamina Propria

5. Overview of Small Intestinal Fungal Overgrowth (SIFO)

- SIFO involves fungal overgrowth in the small intestine, commonly Candida species.

- Small intestines: Low microbial density due to motility, gastric acid, bile acids, immune surveillance, and more.

- Contributing factors: hypochlorhydria, impaired motility, reduced digestive enzymes, diminished competitive flora, lowered immunity, and more.

6. Candida Pathogenicity

- Candida exhibits phenotypic plasticity: yeast and hyphal forms.

- Biofilm formation.

7. Biofilm Formation

- Biofilms are structured communities of microbes within a self-produced extracellular matrix.

- Resistance to antimicrobials and immune defenses.

- Can develop on intestinal mucosa and in various other regions.

8. SIFO and SIBO Overlap

- Root causes and overlap between SIFO and Small Intestinal Bacterial Overgrowth (SIBO).

- Common symptoms.

9. Gastric Acid in More Detail

- Stomach epithelium includes mucous, parietal, chief, and enteroendocrine cells

- Parietal cells secrete hydrochloric acid.

- HCl denatures proteins and aids in inhibiting pathogens.

- Hypochlorhydria: possible causes.

10. Downstream Effects of Low Acid

11. Gut Motility in More Detail

- Motility involves rhythmic smooth muscle contractions.

- Enteric nervous system (ENS): myenteric and submucosal plexuses.

- Dysautonomia and motility.

12. SIFO Contributing Factors

13. Candida Regulation

- Candida generally remains in unicellular yeast form under homeostatic regulation.

- Controlled by microbial competition, host defenses, antifungal peptides, and more.

14. Role of Mucus and sIgA

- Mucosal immunity (including sIgA) aids in regulating Candida populations.

- Low sIgA levels (due to stress, immune suppression, dysbiosis,…) weaken defense

15. Conclusion

- Mucosal barrier structure.

- SIFO and Candida.

- Biofilm formation, microbial persistence, and mucosal disruption.

- SIFO and SIBO.

- Multifactorial nature of fungal dysbiosis, types of biofilms, and small intestinal overgrowth.

Thank you to our episode sponsor:

1. OmneDiem®'s