Backgrounds: Oxidative stress is produced at the wound site, and excessive oxidative stress causes poor wound healing which can lead to dysfunction of the organ. The vocal fold is a vibratory mucosa in the voice box, and creates voice by high frequency vibration such as 100Hz to 800Hz. It can be injured by excessive voicing (vocal abuse), traume, and inflammation. It should be important to control oxidative stress during wound healing of the vocal fold to maintain the vibratory function keeping voice.

Materials and methods: Patients that underwent surgery to the vocal fold due to vocal fold lesions were enrolled in this study. They were seprated into 2 groups: a group treated by anti-oxidant, Twendee X, before and after the surgery (TWX group), and another group with no anti-oxidanta therapy (Control). Post-operative vocal functions were evaluated up to 3 months. The study was approved by institutional IRB.

Results: TWX group showed better vibratory properties with better phonatory function as compared to the control group.

Conclusion: TWX proved to be effective to improve wound healing of the vocal fold after surgery possibly due to reduction of post-operative oxidative stress.

Dysphagia is a big issue for a large number of patients with cerebrovascular and other neurodegenerative diseases. Animal models are essential for understanding the pathophysiology of these conditions and developing effective treatments. In this study, we developed an animal model with attenuated pharyngeal constriction during swallowing using denervation of the pharyngeal branch of the vagus nerve. Our findings suggest that the pharyngeal area and pharyngeal transit duration during the pharyngeal stage of swallowing were increased compared to those in sham-operated and control animals. We investigated the potential of the anti-oxidant Twendee X in preventing oxidative stress caused by denervation-induced muscle damage, which could suppress muscle atrophy. Hence, we tested the effect of oral application of the Twendee X on swallowing function in the dysphagia model animals.

Our results indicate that Twendee X administration resulted in less increase in the pharyngeal area and pharyngeal transit duration compared to those in the dysphagia animal model. The thyropharyngeal muscles were also thicker than those in the nerve-sectioned animals. Overall, our findings suggest that Twendee X may have a possible role in preventing oxidative stress by the denervation of the pharyngeal constrictor muscle, leading to the suppression of denervation-induced muscle atrophy. Further studies are necessary to ascertain the clinical effects of Twendee X on bulbar paralysis in stroke patients. This study provides important insights into the potential use of Twendee X as a treatment for dysphagia patients.

The vocal fold vibrates in high frequency to create voice sound. The vocal fold has a sophisticated histological “layered structure” that enables such vibration. As the vibration causes fricative damage to the mucosa, excessive voicing can cause inflammation or injury to the mucosa. Chronic inflammation or repeated injury to the vocal fold occasionally induces scar formation in the mucosa, which can result in severe dysphonia, which is difficult to treat. Oxidative stress has been proven to be an important factor in aggravating the injury, which can lead to scarring. It is important to avoid excessive oxidative stress during the wound healing period. Excessive accumulation of reactive oxygen species (ROS) has been found in the injured vocal folds of rats during the early phase of wound healing. Antioxidants proved to be useful in preventing the accumulation of ROS during the period with less scar formation in the long-term results. Oxidative stress is also revealed to contribute to aging of the vocal fold, in which the mucosa becomes thin and stiff with a reduction in vibratory capacity. The aged voice can be characterized as weak and breathy. It has been confirmed that ROS gradually increases in rat vocal fold mucosa with age, which may cause further damage to the vocal fold. Antioxidants have also proved effective in avoiding aging of the vocal fold in rat models. Recently, human trials have shown significant effects of the antioxidant Twendee X for maintaining the voice of professional opera singers. In conclusion, it is suggested that oxidative stress has a great impact on the damage or deterioration of the vocal folds, and the use of antioxidants is effective for preventing damage of the vocal fold and maintaining the voice.

Vocalization is a complex laryngeal function that involves intricate neuronal networks in the brain. This function depends on vocal fold vibration, which requires adequate subglottic pressure, vocal fold adduction, and tension. However, excessive use of vocal folds can damage the tissue structure of the vocal folds, as well as the laryngeal and respiratory muscles, possibly due to oxidative stress. Therefore, we conducted a study investigating whether vocal loading could lead to functional deterioration of the vocal-related muscles. 

Thus, we achieved an animal model, in which excessive vocal fold use induces hoarseness, produced by repetitive forced vocalization triggered by electrical stimulation of the midbrain periaqueductal grey in guinea pigs.

To examine oxidative stress of the laryngeal and respiratory muscles of vocal-loaded animals, we then compared the formation of malondialdehyde protein adducts of the laryngeal and respiratory muscles for a representative vocal-loaded animal with a control animal. The intralaryngeal and expiratory respiratory muscles showed higher levels of malondialdehyde in a vocal-loaded animal.

While additional experiments are required to substantiate this hypothesis, these results may give a new perspective on evaluating vocal fatigue in individuals who use their voices excessively. They may also help identify potential interventions or treatments for vocal disorders.

Airway reflexes such as coughing, sneezing, and the expiration reflex are essential in preventing foreign body from staying in the airway. These defensive reflexes should be appropriately activated against foreign bodies entering both the upper and lower airways. However, excessive responses to airway stimulation can lead to further airway distress and result in complications such as an overactive cough reflex and sneezing.

Allergic airway diseases, such as asthma and allergic rhinitis (AR), are typically chronic and are occasionally characterized by excessive and prolonged Th2 responses to inhaled allergens. They are assumed to be linked to oxidative stress. Asthma is associated with decreased antioxidant defenses, such as superoxide dismutase, catalase, and glutathione. Patients with AR have systemically elevated oxidative stress and systemically elevated serum total antioxidant status levels. Concomitant use of nasal steroids and antihistamines significantly decreases total oxidative stress in AR patients. Significant improvement in clinical outcome was observed in subjects who received antioxidants along with intranasal steroid fluticasone furoate. Other treatments that have been reported to improve symptoms of respiratory allergic diseases by enhancing antioxidant status include hydrogen-rich saline, crocin, curcumin, and silymarin. 

Interleukin (IL)-4 and IL-13 are critical cytokines in the induction of the pathogenic Th2 responses. They induce periostin in the airway tract that is highly expressed in chronic inflammatory diseases―asthma, atopic dermatitis, eosinophilc chronic sinusitis/chronic rhinosinusitis with nasal polyp, and allergic conjunctivitis. 

In this presentation, we will briefly review previous studies regarding airway disorders linked to oxidative stress. We will also introduce our recent project regarding airway hyperresponsiveness and the involvement of periostin in respiratory allergic diseases using periostin-knockout mice and respiratory allergic models. Further studies are necessary to evaluate the possibility of anti-oxidative treatment for the hypersensitivity caused by allergic airway inflammation.