Many ANCA-associated vasculitis patients who have a certain type of autoantibody develop the widened-airway condition known as bronchiectasis, a French study shows.
The question of whether the respiratory tract is the place where ANCA-associated vasculitis develops remains to be seen, however, the researchers said. The hallmark of ANCA-associated vasculitis is inflamed blood vessels. It is an autoimmune disease, or one in which the immune system attacks healthy tissue.
Myeloperoxidase, or MPO, is the autoantibody that researchers identified in the study. An autoantibody is a protein the immune system produces to attack other substances in the body.
The full scientific name of ANCA vasculitis is anti-neutrophil cytoplasmic antibody-associated vasculitis. It stems from white blood cells called B lymphocytes producing antibodies that attack another type of white blood cell called a neutrophil.
The French team titled their study, published in Seminars in Arthritis & Rheumatism, “Bronchiectasis is highly prevalent in anti-MPO ANCA-associated vasculitis and is associated with a distinct disease presentation.”
There are three types of ANCA-associated vasculitis — microscopic polyangiitis, or MPA; granulomatosis with polyangiitis, or GPA; and eosinophilic granulomatosis with polyangiitis, EGPA.
The most common autoantibodies that ANCA-associated vasculitis patients produce are aimed at the proteinase 3 (PR3) and myeloperoxidase (MPO) enzymes.
Many ANCA-associated vasculitis patients develop breathing problems because of the blood vessel disruption that their disease causes. They may also have a non-vasculitis lung disease. Scientists are uncertain if there is an association between the two.
Researchers at Nantes University Hospital wanted to know how many GPA and MPA patients had bronchiectasis. They also wanted to see if there were any links between the airway condition and the progression and outcomes of ANCA-associated vasculitis.
The team looked at the records of 30 MPA and 28 GPA patients treated at Nantes University Hospital between 2005 and 2015.
They discovered that 22 patients, or 38 percent, had bronchiectasis. All 22 were producing myeloperoxidase autoantibodies.
No patients who were producing antibodies against the PR3 enzyme had bronchiectasis.
Researchers also discovered that ANCA-associated vasculities patients were more likely to have bronchiectasis, an airway disease, than an interstitial lung disease, which affects the tissue and space around the lungs’ air sacs. In fact, only six patients had an interstitial lung disease.
Interestingly, the team found that patients with bronchiectasis were considerably older than those without bronchiectasis, and more were women.
Another finding was that whether or not a person had bronchiectasis appeared to have no effect on the progression of a patient’s ANCA-associated vasculitis or their survival.
The team also discovered that severe respiratory tract infections were the most frequent cause of death among patients who were producing myeloperoxidase autoantibodies. In fact, the infections claimed two out of every three patients who died.
An additional discovery was that the survival rates of bronchiectasis and non-bronchiectasis patients with no lung infection were similar.
“This study shows that bronchiectasis is a highly prevalent pre-existing respiratory condition in Caucasian patients” with ANCA-associated vasculitis who are producing myeloperoxidase autoantibodies, the researchers wrote.
“Whether the respiratory tract could be the site of initiation of anti-MPO autoimmunity remains to be investigated,” they wrote.