Curli-Containing Enteric Biofilms Inside and Out: Matrix Composition, Immune Recognition, and Disease Implications

Area of Science:

• Microbiology
• Immunology
• Biochemistry

Background:

• Enteric bacterial biofilms are complex structures crucial for bacterial survival and virulence.
• Key components include curli amyloid, cellulose, extracellular DNA, O antigen, and surface proteins like BapA.
• These components influence biofilm stability, bacterial transmission, and host immune responses.

Purpose of the Study:

• To evaluate the individual and combined roles of enteric biofilm components in biofilm formation.
• To investigate the impact of enteric biofilms on host immunity and disease pathogenesis.
• To explore the broader biomedical implications of enteric biofilms beyond specific pathogens.

Main Methods:

• Analysis of biofilm matrix composition in enteric bacteria like *Escherichia coli* and *Salmonella* species.
• Assessment of the immunomodulatory effects of biofilm components, including curli and extracellular DNA.
• Investigation of the role of curli in modulating host immune responses and disease models, such as colitis and systemic lupus erythematosus (SLE).

Main Results:

• Enteric biofilm components, particularly curli, enhance matrix stability and bacterial virulence.
• Systemic exposure to biofilms activates innate immune receptors (TLR2, TLR9, NLRP3), inducing inflammation.
• Oral administration of curli ameliorates intestinal damage and reduces colitis severity.
• Enteric biofilms and their components can exacerbate autoimmune diseases like SLE and promote protein aggregation linked to neurodegenerative diseases (e.g., Parkinson's disease).

Conclusions:

• Enteric biofilms are multifaceted structures with significant implications for host health and disease.
• Curli amyloid, a major biofilm component, exhibits dual roles in immunity, inducing inflammation systemically but offering protection when orally administered.
• The findings highlight the potential of targeting enteric biofilms for therapeutic interventions against infectious and autoimmune diseases.
• The widespread presence of curli homologues suggests broad applicability of these findings across numerous bacterial species.