New Gut Treatment Prevents Noise-Induced Hearing Loss

Researchers have developed a novel oral treatment to prevent and repair noise-induced hearing loss (NIHL) by combining magnetic properties from traditional Chinese medicine with contemporary insights into the gut microbiome.

NIHL can result from exposure to sudden, intense sounds like gunshots or continuous loud noises in industrial settings, affecting people of all ages as society becomes more industrialized and urbanized.

Current treatments such as hearing aids and cochlear implants aim to assist hearing but cannot reverse damage to the inner ear’s sound-detecting hair cells. This new treatment approach offers promise in addressing both prevention and repair of NIHL.

Processing Sound in the Inner Ear

However, in healthy ears, sound waves travel through the inner ear to the cochlea, a snail-shaped structure. Hair cells within the cochlea detect these sound waves and begin to move, causing microscopic projections on their surface to bend against an overlying structure.

This bending opens channels, allowing chemicals to enter the cells and generate electrical signals. These signals travel along the auditory nerve to the brain, where they are interpreted as sound.

In cases of noise-induced hearing loss (NIHL), prolonged exposure to loud noises leads to inflammation and the accumulation of damaging reactive oxygen species (ROS) in the hair cells, ultimately resulting in their death.

Traditional Uses of Magnetite and Hematite in Chinese Medicine

For centuries, magnetite and hematite have been utilized in traditional Chinese medicine to treat various neurological conditions, including hearing loss. Magnetite is reputed for its anti-inflammatory properties and ability to enhance blood circulation.

Hematite is believed to promote overall physical and emotional well-being. Both minerals are magnetic, a characteristic that researchers incorporated into their treatment.

They developed a superparamagnetic iron oxide nanoparticle assembly (SPIOCA), which consists of nanoparticles of iron oxide with magnetic properties.

To enable oral administration, SPIOCA was coated with FDA-approved carboxymethyl cellulose (CMC), a water-soluble derivative of cellulose. Importantly, SPIOCA was designed to be pH-responsive, ensuring it could withstand the acidic environment of the stomach without degradation.

Efficacy of SPIOCA in Noise-Induced Hearing Loss (NIHL) Experiments

The researchers conducted experiments on mice to evaluate the efficacy of SPIOCA against noise-induced hearing loss (NIHL). Mice were administered the oral iron treatment and then exposed to white noise (110 dB) for two hours. Administering SPIOCA before noise exposure significantly enhanced the survival of hair cells.

Furthermore, the researchers observed that SPIOCA primarily accumulated in the gut. Upon closer examination, they noted that noise exposure altered the composition of the gut microbiome unfavorably, while treatment with SPIOCA reversed these changes. Specifically, the treatment notably reduced the increase in harmful bacteria associated with inflammation and infection caused by noise exposure.

“In summary, these findings indicate that the beneficial effects of SPIOCA are linked to its ability to modulate the gut microbiome,” explained the researchers.

Gut-Brain Connection and Protection Against Cochlear Inflammation

Previous research has linked the gut to the brain, demonstrating how inflammatory factors from an imbalanced microbiome can disrupt the protective blood-brain barrier (BBB), leading to brain inflammation.

Similarly, the blood-labyrinth barrier (BLB) in the inner ear shields the cochlea from inflammatory substances. Researchers found that SPIOCA inhibited these gut-related inflammatory factors, protecting against cochlear inflammation and damage.

SPIOCA also promoted beneficial gut bacteria like Bacteroides, which produce sphingolipids essential for cell structure and function. Exposure to noise reduced the expression of the sphingolipid receptor S1PR2 in cochlear hair cells, which typically protects against hearing loss. Treatment with SPIOCA reversed this reduction, restoring S1PR2 expression.

Moreover, the researchers concluded that their study unveils a new pathway through which the gut microbiota impacts cochlear inflammation, offering significant insights into hearing protection.

They also highlighted the pioneering restorative impact of iron oxide nanomaterials on imbalanced gut microbiota. By targeting gut microbiota modulation, SPIOCA holds promise as a potent nanomedicine for treating noise-induced hearing loss (NIHL).

Further investigations are required to fully elucidate how SPIOCA influences the gut microbiome and its mechanisms of action.

Read the original article on: New Atlas

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