Loss of Elastin in Lungs a Potential Biomarker for Both IPF and COPD, Study Suggests

Patricia Inácio, PhD avatar

by Patricia Inácio, PhD |

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Idiopathic pulmonary fibrosis (IPF) and chronic obstructive pulmonary disease (COPD) may share a common disease mechanism — degradation of elastin in the lungs — suggesting its potential as a biomarker for both diseases, research shows.

The study, “Increased circulating desmosine and age-dependent elastinolysis in idiopathic pulmonary fibrosis,” was published in a letter to the editor in the journal Respiratory Research.

Emphysema, a respiratory condition characterized by overinflation of the alveoli (air sacs in the lungs), is caused by an imbalance in enzymes that degrade elastin — a protein making up the alveoli that provides the pressure to allow for easy breathing.

The breakdown of elastin — a process referred to as elastinolysis — is seen in COPD patients, but this process was also reported to occur in the lungs of IPF patients.

Two particular amino acids (protein building blocks), known as desmosine (DES) and isodesmosine, are unique to elastin.

“During the degradation process, elastases liberate DES from elastin fibers,” the researchers wrote, explaining that this leads to an increase in DES levels in the blood of COPD patients.

A recent study reported that elastin degradation is accelerated with aging, a phenomenon especially enhanced in COPD patients. Whether the same is also true for IPF patients remains unknown.

To address this, researchers measured the levels of DES in blood samples of 154 patients from three different IPF groups in Maastricht and Nieuwegein, Netherlands, and Ann Arbor, Michigan. Of these patients, 142 had moderate-to-severe COPD, and 84 were healthy controls. They also correlated the values of participants’ forced vital capacity (FVC), a measure of lung function, with those of circulating DES.

Each group contained both smokers and nonsmokers, and the analysis between groups was adjusted for participants’ ages.

Researchers found a significant correlation between age and the increment in circulating levels of DES in IPF patients.

Both IPF and COPD patients also showed significantly higher circulating DES levels than controls. Higher DES levels in the blood (an average of 507 nanograms per liter) were found in IPF patients and COPD patients (469 ng/L) compared with age-adjusted smoking (269 ng/L) and nonsmoking (236 ng/L) controls.

No significant differences were found within the three IPF groups or between IPF and COPD patients.

These results indicate that “elastinolysis could be a shared pathogenic step between COPD and IPF,” the researchers wrote, suggesting the potential use of high circulating levels of DES as a biomarker in IPF. Previous research suggested this, but only in COPD.

Further research is need to “establish the relevance of accelerated elastin degradation in IPF and to determine whether decelerating this process translates into slower progression of lung fibrosis and better survival for patients with IPF,” the team concluded.

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