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Updated: Mar 24, 2026
Murine Model of Epicutaneously-Induced Immunomodulation
Published on: June 24, 2025
Ciprofloxacin Decreases Collagen in Mouse Tympanic Membrane Fibroblasts
Nicklas C Orobello1, Carolyn O Dirain1, Gregory Schultz1
1Department of Otolaryngology-Head and Neck Surgery, University of Florida, Gainesville, Florida, USA.
Objectives:
To determine how collagen production by tympanic membrane fibroblasts is affected by ciprofloxacin at levels found in eardrops.
Study Design:
Prospective, controlled, and blinded cell culture study.
Setting:
Academic tertiary medical center.
Subjects:
Cell culture of mouse fibroblasts.
Methods:
A primary fibroblast culture was established from mouse tympanic membranes. Fibroblasts were cultured until they were 75% confluent, then treated with dilute hydrochloric acid (control) or ciprofloxacin (0.01% or 0.3%) for 24 or 72 hours for Western blotting and for 24 or 48 hours for cytotoxicity assay. Cells were observed with phase-contrast microscope. Western blotting was performed for collagen type 1 α1 (collagen 1A1) and α-tubulin.
Results:
Fibroblasts treated with 0.01% and 0.3% ciprofloxacin for 24 hours had lower levels of collagen 1A1 (P = .0005 and P < .0001, respectively) and α-tubulin (both P < .0001) than control fibroblasts. Collagen 1A1 and α-tubulin levels were lower in fibroblasts treated with 0.3% than with 0.01% ciprofloxacin (P = .02 and P = .014). After 72 hours, 0.3% ciprofloxacin completely eliminated collagen 1A1 and α-tubulin (P < .001). Cells treated with 0.01% ciprofloxacin for 72 hours also had lower collagen 1A1 (P < .0001) and α-tubulin (P = .005) as compared with the control. Seventy-two-hour incubation in 0.01% or 0.3% ciprofloxacin resulted in lower levels of collagen 1A1 (P = .009 and P < .0001, respectively) and α-tubulin (P = .007 and P < .0001, respectively) than 24-hour incubation. Cytotoxicity assay and phase-contrast microscopy mirrored these findings.
Conclusions:
Treatment of tympanic membrane fibroblasts with 0.3% ciprofloxacin, as found in eardrops, reduces fibroblast viability and collagen and α-tubulin protein levels. These findings could explain tympanic membrane healing problems associated with quinolone eardrops.
Insights
Ciprofloxacin in eardrops significantly reduces collagen production in tympanic membrane fibroblasts. This may explain healing issues associated with quinolone eardrops.
Area of Science:
- Otolaryngology
- Biochemistry
- Cell Biology
Background:
- Tympanic membrane (TM) healing is crucial for auditory function.
- Fibroblasts play a key role in wound repair and collagen synthesis.
- Ciprofloxacin is a common antibiotic in otic preparations.
Purpose of the Study:
- To investigate the impact of ciprofloxacin concentrations found in eardrops on collagen production by TM fibroblasts.
- To assess the effects of ciprofloxacin on fibroblast viability and protein expression.
Main Methods:
- Primary mouse tympanic membrane fibroblasts were cultured.
- Cells were treated with varying concentrations of ciprofloxacin (0.01%, 0.3%) or control for 24 or 72 hours.
- Western blotting was used to quantify collagen type 1 α1 (collagen 1A1) and α-tubulin protein levels.
- Cytotoxicity assays and phase-contrast microscopy were performed.
Main Results:
- Ciprofloxacin treatment significantly decreased collagen 1A1 and α-tubulin levels in a dose- and time-dependent manner.
- Higher ciprofloxacin concentrations (0.3%) and longer exposure (72 hours) led to more pronounced reductions.
- Cytotoxicity assays confirmed reduced fibroblast viability with ciprofloxacin exposure.
Conclusions:
- Ciprofloxacin at concentrations used in eardrops inhibits collagen production and reduces fibroblast viability.
- These findings suggest a potential mechanism for impaired tympanic membrane healing observed with quinolone-based ear drops.
