Patients with autoimmune interstitial lung disease (ILD) — a frequently fatal chronic inflammatory autoimmune disease that causes scarring of the lungs — often have vitamin D deficiencies, and researchers from the University of Cincinnati believe this may affect the disease’s pathogenesis.
In a study published in the Jan. 4 issue of Chest, researchers analyzed serum 25-hydroxyvitamin D levels in 118 patients from the center to determine whether vitamin D levels influenced disease progression. Among study participants, 67 had connective tissue disease, whereas 51 patients had other causes of lung fibrosis.
“Since vitamin D has implications in other manifestations of autoimmune illnesses [including type 1 diabetes], we wanted to see if it had an effect on the lungs of this patient population,” Brent Kinder, MD, the director of the Interstitial Lung Disease Center at the university, said in a press release.
Kinder and colleagues found that patients who had connective tissue disease-related ILD — including those with rheumatoid arthritis, lupus and scleroderma — were more likely to have vitamin D deficiency (52% vs. 20%; P<.0001) and insufficiency (79% vs. 31%; P<.0001), compared with patients who had other forms of the disease.
Among patients with low vitamin-D levels and connective tissue disease-related ILD the researchers noted reduced lung function, including diminished forced vital capacity (P=0.015) and diffusing capacity for carbon monoxide (P=.004). These associations persisted even after adjusting for potential confounding factors (OR=11.8; P<.0001).
The researchers believe that vitamin D may play a role in worsening lung function in these patients and that supplements may be a safer, less expensive treatment for the illness than existing toxic therapies.
“One of the next steps is to see if supplementation will improve lung function for these patients,” Kinder said.
The researchers called for more clinical trials to “investigate the underlying molecular mechanisms of this observed association,” and additional “prospective controlled interventional studies […] to determine if vitamin D supplementation can ameliorate symptoms and improve outcomes.”