Meet the Researcher
Tarabichi earned his medical degree from the Royal College of Surgeons in Ireland-Bahrain. He is currently a research track resident in the University of Iowa Otolaryngology–Head and Neck surgery program and work under the mentorship of Marlan Hansen, M.D. He is working on developing helper-dependent, adenoviral vectors for inner ear gene delivery, and is working on projects investigating cochlear immunity and the role of lymphatics in the response to cochlear implantation. Tarabichi is a recipient of a 2025 Elizabeth M. Keithley, Ph.D. Early Stage Investigator Award.
The Research
University of Iowa
The role of inner ear lymphatics in the foreign body response to cochlear implantation
Cochlear implantation is an effective treatment for patients with severe to profound hearing loss. In response to cochlear implantation, the cochlea mounts an inflammatory response. The degree of inflammation and fibrosis caused by this response has been linked to poor implant performance and loss of remaining natural acoustic hearing. The cochlear immune response has long been thought to be driven primarily by elements of the innate immune system, however recent evidence shows that following noise exposure and drug toxicity an adaptive immune response is mounted in the cochlea. Similarly, our group has produced evidence that an adaptive immune response is also involved in the foreign body response to cochlear implantation. The mounting of an adaptive immune response relies on the presence of lymphatic networks that can deliver antigen presenting cells to draining lymph nodes, allowing them to interact with elements of the adaptive immune system.
While a few studies have attempted to map the network of lymph nodes draining the cochlea; to date, no studies have described or characterized lymphatic vasculature within the cochlea. Preliminary data from our group demonstrates a rich lymphatic network throughout the cochlea. Our overall hypothesis is that a rich lymphatic network exists within the cochlea and that it plays a key role in the cochlear inflammatory response. This work is timely in light of recent literature confirming a “glymphatic” network in the brain that is key to waste clearance and plays a significant role in brain aging and inflammation. Gaining a better understanding of the lymphatic vasculature of the inner ear is therefore key to improving our understanding of cochlear immune response to a variety of insults.
Long-term goal: Long-term goals of this project include the detailed characterization of lymphatic networks within the cochlea and how they are involved in the mechanisms of the cochlear response to mechanical trauma from cochlear implantation, age-related hearing loss, noise damage, and ototoxic drug exposure. We also have aspirations to translate this to human studies and image cochlear lymphatics in the human inner ear. The clinical application that is most in reach for this work is in the field of cochlear implantation. Preserving residual hearing and limiting the fibrosis and neo-ossification in cochlea following cochlear implantation are thought to be key to optimizing implant performance. A plethora of research and industry efforts have been spent to try and improve cochlear implant performance by limiting insertional trauma and resultant inflammation. For instance, dexamethasone delivery and/or elution and use of more flexible and soft cochlear implant materials are two technologies that have been touted as ways to limit the foreign body response. Our work will further elucidate a hitherto unstudied aspect of the cochlear foreign body response that is likely playing a significant role in immune cell trafficking and chronic inflammation. Better understanding lymphatics within the cochlea can help us identify ways of limiting the maladaptive fibrotic efforts have been spent to try and improve cochlear implant performance by limiting insertional trauma and resultant inflammation. For instance dexamethasone delivery and/or elution and use of more flexible and soft cochlear implant materials are two technologies that have been touted as ways to limit the foreign body response. Our work will further elucidate a hitherto unstudied aspect of the cochlear foreign body response that is likely playing a significant role in immune cell trafficking and chronic inflammation. Better understanding lymphatics within the cochlea can help us identify ways of limiting the maladaptive fibrotic response to cochlear implantation.
Lymphatics could also possibly play a role in the pathophysiology of age-related hearing loss. We know that In the brain, impaired lymphatic drainage and metabolite clearance has been linked to aging and neuroinflammation. Furthermore, preclinical studies have shown that this impaired clearance can be pharmacologically targeted. This could have potentially important implications for hearing loss therapeutics if similarly poor clearance of metabolites from the cochlear partitions is linked to age-related hearing loss.