In patients with interstitial lung disease, cigarette smoking may sometimes cause the production of ANCA associated antibodies — a hallmark of ANCA-associated vasculitis — without any signs of vessel inflammation, the case of a 57-year-old man suggests.
The case report, “Combined pulmonary fibrosis and emphysema with myeloperoxidase-antineutrophil cytoplasmic antibody positivity that resolved upon smoking cessation,” was published in the journal Respiratory Medicine Case Reports.
The presence of ANCA antibodies is a useful biomarker in the diagnosis of ANCA-associated vasculitis. These antibodies appear at disease onset, and seem to correlate with disease activity.
But is some cases, patients produce ANCA antibodies and have no signs of vasculitis, suggesting that ANCA is being produced in a non-specific manner.
Now, researchers reported the case of a Japanese man whose ANCA levels went back to normal after quitting smoking, suggesting that cigarette smoking was causing the elevated ANCA levels.
The patient was a regular smoker, with a 40-year history of 40 cigarettes daily, and showed abnormal chest X-ray results during a regular checkup.
But his lung function was normal and he had no difficulty in performing physical tasks. He only showed difficulty breathing during vigorous exercise.
Additional computed tomography (CT) scans and blood exams suggested emphysema, a lung disease that damages the lung sacs and causes shortness of breath. Levels of MPO-ANCA antibodies — one of the two most common ANCA antibodies — were also high.
The patient was diagnosed with smoking-related interstitial lung disease, but exams failed to identify any signs of blood vessel inflammation, which characterizes ANCA-associated vasculitis.
But exams found signs of interstitial pneumonia (UIP) in the lungs, which led to a diagnosis of combined pulmonary fibrosis and emphysema (CPFE) with increased MPO-ANCA.
While the patient did not receive any medication, he did stop smoking. Four months later, his ANCA levels were down to normal levels, and no signs of lung disease progression were found.
“Smoking might lead to production of MPO-ANCA and disease activity,” researchers suggested.
His condition remained stable during the next three years of follow-up, and no additional treatment with anti-fibrotic agent or lung transplantation was required.
Previous studies have demonstrated that “elevated ANCA levels are associated with various diseases and conditions, but are not significantly associated with cigarette smoking,” researchers wrote.
However, in light of these new findings, additional studies are warranted to better understand the potential correlation between “ANCA levels, interstitial pneumonia, and cigarette smoking,” they suggested.