Gastric Acid Reflux and Sinusitis

Abstract

Two main factors are considered to be involved in the pathogenesis of sinusitis: anatomical abnormalities of the human paranasal sinuses, and factors predisposing to inflammation. Inflammation is usually induced by bacterial infections, virus infections or allergic diseases, influenced by the patient and environmental backgrounds. The major causes of inflammation in Japan used to be bacterial and virus infections, manifesting as typical purulent chronic sinusitis. In recent decades, however, eosinophilic chronic rhinosinusitis (ECRS) has come to be identified as the main cause of sinusitis, and it is known to be refractory to treatment.

Several pathogenetic mechanisms underlying eosinophilic inflammation have been proposed until date, including a possible relation with protease production from Alternaria, super-antigens released from Staphylococcus aureus, local allergic inflammation, and autoimmune responses, including overproduction of IgG4. Gastric acid reflux has also been reported as another cause of persistent sinus inflammation. So far, the correlation between chronic sinusitis and gastric acid reflux has mainly been pointed out from several epidemiological surveys. Some of the suggested mechanisms underlying the development of sinusitis secondary to gastric acid reflux are direct injury of the nasal epithelial cells by the gastric acid contents, Helicobacter pylori colonization or infection of the nasal mucosa, and factors related to vagus nerve reflexes. A series of our studies had revealed that gastric acid stimulation induced interleukin-33 production in the nasal mucosa. A relatively higher prevalence of Helicobacter pylori colonization of the ethmoid sinus mucosa has been reported in chronic sinusitis patients. The clinical effectiveness of anti-reflux therapy using proton pomp inhibitors has also been reported in some of these cases. These results imply the existence of a possible relation between gastric acid reflux and the occurrence of chronic sinusitis. Results of further studies are awaited to obtain a consensus on the causal association between chronic sinusitis and gastric acid reflux.