# Immune recognition mechanisms of bacterial biofilms in the gut

> **NIH NIH R21** · TEMPLE UNIV OF THE COMMONWEALTH · 2021 · $198,125

## Abstract

Summary
Human intestinal tract is colonized by diverse microbial communities, termed the microbiota.
Microbiota plays an important role in educating the immune system. However, the nature of the
microbe-host interactions that help maintain immune homeostasis is poorly understood. One
feature of the gut microbiota is the formation of multicellular communities, termed biofilms, in the
mucus layer. The formation of biofilms is accompanied by the release of bacterial products that
form an extracellular matrix. Amyloid fibers are an important extracellular matrix component of
biofilms formed by diverse groups of bacteria, including many members of the Proteobacteria,
Bacteroidia and Firmicutes. Conserved beta sheet structure of amyloid fibers is recognized by
receptors of the innate immune system as a conserved molecular pattern (i.e. a so-called
pathogen-associated molecular pattern or PAMP). However, it is not known whether detection of
amyloid fibrils by the innate immune system represents one of the elusive microbe-host
interactions that contribute to immune homeostasis at the mucosal surface. In addition to
amyloids, extracellular bacterial DNA (eDNA) has been shown to be present in several bacterial
biofilms. The objective of this application is to determine the mechanisms by which bacterial
amyloid curli/DNA complexes are recognized by the immune system in the gut. We hypothesize
that the immune system recognizes bacterial amyloid curli/DNA complexes as conserved
molecules common to bacterial biofilms. Curli/DNA complex acts by accessing multiple cellular
compartments and activates multiple PRRs including TLR2, TLR9 and NLRP3 leading to epithelial
barrier reinforcement in the gut by the generation of immunomodulatory cytokines, IL-10 and IL-
18.

## Key facts

- **NIH application ID:** 10135013
- **Project number:** 5R21AI151893-02
- **Recipient organization:** TEMPLE UNIV OF THE COMMONWEALTH
- **Principal Investigator:** Cagla Tukel
- **Activity code:** R21 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2021
- **Award amount:** $198,125
- **Award type:** 5
- **Project period:** 2020-04-01 → 2023-03-31

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/10135013

## Citation

> US National Institutes of Health, RePORTER application 10135013, Immune recognition mechanisms of bacterial biofilms in the gut (5R21AI151893-02). Retrieved via AI Analytics 2026-05-22 from https://api.ai-analytics.org/grant/nih/10135013. Licensed CC0.

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