Rhinosinusitis

What is rhinosinusitis?

Rhinosinusitis, also known as sinusitis, is a condition characterized by inflammation of the mucous membranes lining the nasal passages and sinuses. The sinuses are air-filled cavities located within the bones of the skull around the nose and eyes. Rhinosinusitis can be acute or chronic and may result from various causes, including infections, allergies, structural abnormalities, or underlying medical conditions.

Acute rhinosinusitis typically develops following a viral upper respiratory infection, such as the common cold, and is characterized by sudden onset symptoms that last for less than 12 weeks. Chronic rhinosinusitis, on the other hand, persists for 12 weeks or longer and may be associated with persistent inflammation, recurrent infections, or structural abnormalities of the sinuses.

What is the relationship between rhinosinusitis and oxidative stress?

The relationship between rhinosinusitis and oxidative stress is a topic of ongoing research, particularly in chronic rhinosinusitis (CRS), where oxidative stress has been implicated in the pathogenesis and progression of the disease. Oxidative stress refers to an imbalance between the production of reactive oxygen species (ROS) and the body’s ability to neutralize them with antioxidants, leading to cellular damage and inflammation. Several mechanisms may link oxidative stress to the development and exacerbation of rhinosinusitis:

• Inflammation: Chronic rhinosinusitis is characterized by persistent inflammation of the nasal and sinus mucosa. Inflammatory cells, such as neutrophils, eosinophils, and macrophages, release ROS as part of the immune response to pathogens or allergens. Excessive ROS production can lead to oxidative stress, which further amplifies the inflammatory cascade, exacerbating tissue damage and inflammation in the sinuses and nasal passages.

• Epithelial Dysfunction: The nasal and sinus epithelium serves as a barrier against environmental insults, pathogens, and allergens. Oxidative stress can disrupt the integrity of the epithelial barrier, impairing its function and allowing for increased penetration of allergens, toxins, and pathogens into the underlying tissues. Epithelial dysfunction contributes to increased susceptibility to infections, prolonged inflammation, and tissue remodeling in chronic rhinosinusitis.

• Mucociliary Clearance: The mucociliary clearance system plays a crucial role in removing mucus, debris, and pathogens from the nasal and sinus cavities. Oxidative stress can impair mucociliary function by damaging cilia, reducing ciliary beat frequency, and altering the composition and viscosity of mucus. Impaired mucociliary clearance leads to mucus stasis, bacterial overgrowth, and recurrent infections, exacerbating the symptoms of rhinosinusitis.

• Antioxidant Defenses: Antioxidant enzymes and molecules, such as superoxide dismutase, catalase, glutathione peroxidase, and vitamins C and E, help neutralize ROS and protect cells from oxidative damage. In chronic rhinosinusitis, the antioxidant defense system may be overwhelmed or dysregulated, leading to increased oxidative stress and tissue injury. Studies have shown alterations in antioxidant enzyme activities and antioxidant molecule levels in the sinonasal mucosa of individuals with CRS.

• Tissue Remodeling: Chronic inflammation and oxidative stress contribute to tissue remodeling processes in the sinonasal mucosa, including fibrosis, angiogenesis, and extracellular matrix remodeling. Oxidative stress-induced changes in signaling pathways, such as nuclear factor kappa B (NF-κB) and mitogen-activated protein kinase (MAPK), can promote tissue fibrosis, glandular hypertrophy, and nasal polyp formation in chronic rhinosinusitis.

Overall, oxidative stress appears to play a significant role in the pathogenesis and progression of rhinosinusitis, particularly in chronic forms of the disease.