Published Online: April 2, 2014
Cigarette smoking and exposure to secondhand smoke have long been known to exacerbate respiratory diseases such as asthma and sinusitis. While a number of mechanisms have been identified to account for this, much remains to be understood as to how smoke causes inflammation. Vitamin D3 has anti-inflammatory and anti-bacterial effects. An increasing number of reports in upper and lower airway diseases have found an association between vitamin D3 deficiency and more severe inflammation. Furthermore, several reports have shown that patients with chronic rhinosinusitis with nasal polyps are more likely to be vitamin D3 deficient, which is associated with more severe disease and increased bone erosion. The purpose of this study was to examine the relationship between cigarette smoking and sinus tissue regulation of vitamin D3 in patients with chronic rhinosinusitis.
Recently published by The Journal of Allergy and Clinical Immunology (JACI), this study by Mulligan and colleagues examined the impact of cigarette smoke exposure on circulating vitamin D3 levels and its activation in the sinus mucosa. Patients enrolled in this study were controls free of sinus disease and those with chronic rhinosinusitis without nasal polyps or chronic rhinosinusitis with nasal polyps. Blood, hair (used to determine smoking status), and sinonasal tissue was collected at the time of endoscopic sinus surgery. Cultures of primary human sinonasal epithelial cells were established and treated with cigarette smoke extract and/or physiological doses of vitamin D3.
Active smoking or exposure to environmental tobacco smoke was associated with reduced levels of vitamin D3 in the blood stream and sinus tissue in all patients. Analysis of sinus tissue demonstrated decreased gene expression for the gene that activates vitamin D3 in patients with polyps. Smoke exposure further reduces the expression of this key gene in all patient groups. Lastly, addition of the active form of vitamin D3 back to sinonasal epithelial cells—the cells lining the respiratory tract—was able to block the inflammatory effects of cigarette smoke.
In conclusion, exposure to cigarette smoke impairs sinus vitamin D3 activation and is associated with more severe vitamin D3 deficiency both in healthy patients and patients with chronic rhinosinusitis. Individuals who are active smokers, exposed to secondhand smoke, or who have chronic sinusitis with nasal polyps may be at higher risk for vitamin D3 deficiency. Impaired vitamin D3 activation by cigarette smoke represents a novel mechanism by which cigarette smoke induces its pro-inflammatory effects.
The Journal of Allergy and Clinical Immunology (JACI) is an official scientific journal of the AAAAI, and is the most-cited journal in the field of allergy and clinical immunology.