Researchers at Severance Hospital have uncovered a new immune function of Cochlin protein, the hospital said Friday.
The team discovered that the protein inhibits the invasion and proliferation of Pseudomonas aeruginosa (P. aeruginosa), a major cause of chronic otitis media, by helping immune cells find and attack P. aeruginosa.
The inner ear organ of a person’s body is in the innermost part of the ear. However, it is susceptible to infection as various bacteria can invade from the outside, while chronic otitis media is one of the most common diseases of internal organs.
The disease causes inflammation of the inner ear organism, causing damage to the organ and causing hearing loss and dizziness. In recent years, excessive use of antibiotics has revealed that bacteria, which cause chronic otitis media, have antibiotic resistance. Also, there is no knowledge of the mechanism by which the inner ear of a human is immune-reactive against bacteria.
The team, led by Professors Choi Jae-young, Hyun Young-min and Jung Jin-sei at the hospital, conducted the research to identify the physiological mechanisms of how innate immune responses work in the inner ear and to find new antimicrobial substances that can replace existing antibiotics through the activation of core proteins by finding essential proteins that lead to reverse mechanism.
After a decade of research, the team found that a protein called Cochlin leads to a congenital immune response against bacterial invasion from the inner ear after searching for disease-related genes in patients with deafness or chronic otitis media, using next-generation sequencing techniques.
According to the researchers, the Cochlin protein plays a vital role in preserving hearing and maintaining the structure and function of inner ear organisms by inhibiting the invasion and proliferation of P. aeruginosa, which causes various diseases in humans, including chronic otitis media.
“Specifically, the Cochlin protein is intensively secreted in the form of LCCL peptide in the pathway of bacteria that penetrate the inner ear, thereby protecting the cortical organs responsible for hearing,” the team said. “Also, the Cochlin protein tangled and glued the germs together, helping various immune cells to gather and easily identify and eliminate the bacteria.”
In a mice test, the team found Cochlin protein-depleted mice was associated with excessive proliferation of P. aeruginosa and severe hearing loss following the destruction of the inner ear tissue, which confirmed that Cochlin plays a crucial role in the innate immune response in the inner ear.
“The study showed that hearing loss was induced when P. aeruginosa infected the inside of the inner ear,” Professor Jung said. “However, our team discovered that Cochlin could prevent the loss of hearing, which has provided an important clue to the development of new therapies.”
Cell Host & Microbe published the results of the study.