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NIH MedlinePlus the Magazine, Trusted Health Information from the National Institutes of Health

Feature:
Drug-Induced Hearing Loss

Researchers Study Strategies to Preserve Hearing

Focus on research: Dr. Lisa Cunningham

Lisa L. Cunningham, PhD, Chief, Section on Sensory Cell Biology
Photo Courtesy of: NIDCD

An estimated half million Americans experience hearing loss every year from ototoxic drugs—drugs that can damage hair cells in the inner ear that are essential for hearing. These drugs include some antibiotics and the chemotherapy drug cisplatin for cancer patients. Scientists at the National Institute on Deafness and Other Communication Disorders (NIDCD) are studying strategies to preserve hearing without interfering with the benefits of these often lifesaving drugs. Dr. Lisa Cunningham, Chief, Section on Sensory Cell Biology, spoke with NIH MedlinePlus magazine about the research.

What sparked your interest in hearing loss?

From my earliest days in school, I always liked science. I entered college as a pre-med student but switched to audiology in my junior year. After completing my first research project as part of my audiology training, I was hooked. I loved the feeling of discovery, and knew I would do research for the rest of my life. For my doctoral-level training, I studied neuroscience because I wanted to be able to study hearing at the cellular and molecular levels. My neuroscience training gives me the tools to carry out these fundamental studies, and my audiology background keeps me always searching for ways to translate our research into new therapies.

What are hair cells and why are they important to us?

Hair cells are the cells in the inner ear that convert sound into signals that are interpreted by the brain. They are called hair cells because they have a bundle of projections on them called stereocilia that look like tiny hairs. When sound waves cause the stereocilia to move, the hair cell sends a signal to the brain that tells the brain there was a sound.

What are ototoxic drugs and why are they important?

Ototoxic drugs are medications that cause hearing loss as a side effect. There are two major types. Cisplatin is a drug used to treat cancer—it saves many thousands of lives of both adults and children worldwide. Unfortunately, it also causes significant permanent hearing loss in a proportion of the patients treated with it. The second group of ototoxic drugs is a class of antibiotics called aminoglycosides. They are widely used to treat life-threatening infections. Like cisplatin, they cause hearing loss in many patients.

How do these lifesaving medicines damage hearing?

Cisplatin and aminoglycosides kill the hair cells in the inner ear. Because our hair cells don't grow back after they die, the result is permanent hearing loss.

Have you discovered anything that may help to protect the hair cells?

Our lab and others have developed a variety of strategies to reduce hair cell death and hearing loss from ototoxic drugs in animal studies. For example, for the past several years my lab has focused on a class of protective molecules called heat shock proteins (HSPs).

What are heat shock proteins and how do they help my hearing?

HSPs are found in every cell type—yeast, bacteria, and plant and animal cells. They are robustly activated in cells exposed to dangerous levels of heat and to a wide variety of other cellular stresses, including starvation, oxygen deprivation, free radicals, and more. Once HSPs are activated in response to stress, they can help to keep cells alive and functioning. We have discovered that by activating them, we can protect inner ear hair cells from dying due to ototoxic drugs.

Please describe the benefits of your findings.

Our results advance our understanding of the fundamental processes that occur when the inner ear is under stress. They point to a promising new direction for developing therapies to prevent hearing loss in patients who need lifesaving—but ototoxic—drugs. Our challenge now is to move this discovery from the laboratory to the clinic so it can benefit patients by protecting their hearing. We are working with our colleagues at the NIH Clinical Center to develop studies aimed at reducing hearing loss in patients taking ototoxic drugs.

What do you recommend for patients at risk from ototoxic drugs?

Patients should discuss the potential for drug-induced hearing loss with their doctor. It is very helpful to have a baseline hearing test before beginning therapy with ototoxic drugs. This allows the patient and his or her audiologist to monitor for changes in hearing and keep the medical team informed if these changes occur.

How important is long-term medical research like yours?

Medical research is the reason we have life-saving therapies in the first place. For example, the discovery of cisplatin was a major medical breakthrough. This drug saves the lives of millions of cancer patients and is remarkably successful at curing certain types of tumors in children. Unfortunately, it can also cause severe permanent hearing loss. This can be particularly troublesome for young children socially and in school because hearing is critical to their developing speech and language skills. Our goal is to improve the lives of these children and their families by developing therapies to protect their hearing.

Read More "Drug Induced Hearing Loss" Articles

Researchers Study Strategies to Preserve Hearing / What Is Ototoxicity?

Spring 2016 Issue: Volume 11 Number 1 Page 11-12