# Impact of antibiotic treatment on Lactobacillus population dynamics and intestinal T cell regulatory function

> **NIH NIH F31** · EMORY UNIVERSITY · 2024 · $48,974

## Abstract

PROJECT SUMMMARY:
Antibiotics are essential medicines to treat bacterial infections. Many broad-spectrum antibiotics, such as
oral ciprofloxacin, are commonly prescribed to treat many gastrointestinal infections. Antibiotics also affect
the microbiota by altering its diversity and function and sometimes promoting dysbiosis. Although previous
studies implied that some beneficial microbes, such as Lactobacilli, have preexisting resistance to various
antibiotics, it is still unclear how commonly prescribed oral antibiotics, like ciprofloxacin, selects for
Lactobacilli species. This proposal addresses this knowledge gap by first examining the effect of
ciprofloxacin exposure in Lactobacilli species. In Aim 1, we will examine the effects of oral ciprofloxacin on
the microbiota by identifying changes in the bacterial taxa from ileum and fecal contents through 16SrRNA
sequencing and assess the Lactobacilli abundance by qPCR. Then, we will examine the resistance
phenotype to ciprofloxacin of different Lactobacilli species using colony forming units and population
analysis profile assays. Our preliminary data suggests that Lactobacillus relative abundance increases
during ciprofloxacin treatment. Additionally, preliminary in vitro data implies that Lactobacillus tends to have
preexisting resistance to ciprofloxacin. Although studies have demonstrated that antibiotics affect the
microbiota and host immune responses, it is still unclear how oral ciprofloxacin alters Lactobacillus species
which affect the regulatory immune response. Foxp3+ Regulatory T cells (Tregs) and intraepithelial
lymphocytes (IELs) are known for their immunoregulatory functions. These cells mediate tolerance against
various stimuli, such as nutrients and microbiota, via anti-inflammatory cytokine expression, like IL-10. Many
beneficial microbes induce Tregs and other IL-10-producing cells. Lactobacillus has been shown to influence
the development of IELs. Additionally, previous studies using antibiotic cocktails have shown that IL-10
production from colonic regulatory T cells decrease during treatment. However, it is still unknown if
ciprofloxacin-selected Lactobacilli induces IL-10 production in IELs, especially in the small intestine. In Aim
2, we will examine the changes in IL-10 production of intestinal T cells during ciprofloxacin treatment by
treating IL-10 reporter mice with ciprofloxacin. Our preliminary flow cytometry data suggests that
ciprofloxacin treatment increases IL-10 production in IELs. Furthermore, preliminary in vitro data suggested
that Lactobacillus induces IL-10 production from macrophages. Therefore, Lactobacillus could also promote
IL-10 production in IELs during ciprofloxacin treatment. Overall, this project will assess how ciprofloxacin
selects for Lactobacillus species that promote IL-10 production in the small intestine. In addition, this work
will provide insight on how commonly prescribed antibiotics affect the microbiota and intestinal regulatory
immune ...

## Key facts

- **NIH application ID:** 10902645
- **Project number:** 1F31AI183823-01
- **Recipient organization:** EMORY UNIVERSITY
- **Principal Investigator:** Dormarie Elisabet Rivera-Rodriguez
- **Activity code:** F31 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2024
- **Award amount:** $48,974
- **Award type:** 1
- **Project period:** 2024-08-01 → 2025-07-31

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/10902645

## Citation

> US National Institutes of Health, RePORTER application 10902645, Impact of antibiotic treatment on Lactobacillus population dynamics and intestinal T cell regulatory function (1F31AI183823-01). Retrieved via AI Analytics 2026-05-24 from https://api.ai-analytics.org/grant/nih/10902645. Licensed CC0.

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