Aging Compounds May Contribute to COPD

Advanced glycation endproducts (AGEs) accumulate differently in various parts of the body in people with chronic obstructive pulmonary disease (COPD), Dutch researchers found.

Their study was published in the journal Respiratory Research on April 26, 2016. It was conducted by Susan J.M. Hoonhorst, of the University Medical Center Groningen, in Groningen, Netherlands, and colleagues.

The researchers begin by describing the compounds known as "AGE"s.

“AGEs are a heterogeneous and complex group of compounds that are irreversibly formed by non-enzymatic glycation and oxidation of proteins and lipids.”

AGEs normally accumulate with aging, and they increase in conditions with inflammation and oxidative stress. The researchers further explain, “AGEs cause local tissue damage by affecting protein structure, by formation of crosslinks between molecules, or by binding the receptor for AGEs (RAGE).”

Previous studies have seemed to indicate that AGEs are “involved in the pathology of COPD,” according to the authors. In order to further investigate the possible link between AGEs, RAGE, and COPD, the researchers collected data from two studies. Participants had mild to severe COPD, were between the ages of 40 and 75 years, and a control group of young, healthy smokers, and nonsmokers was recruited through advertising.

Blood samples, bronchial biopsies and skin autofluorescence (SAF) were used to measure AGEs and RAGE in different parts of the body. The study showed that AGEs accumlated more in the skin of COPD patients, but that the elevation was consistent regardless of the stage of the disease. In contract, bronchial biopsies showed no difference in the AGEs of COPD patients and healthy controls, and the same was true of both plasma and sputum.

There are limitations to this study, including the fact that only 12 out of 97 patients had sputum samples, as well as the cross-sectional design of the study.

However, the researchers note, “This study is unique because of its large population of healthy smokers and never-smokers and a large group of COPD patients of all severities, as well as the availability of different tissues from each participant.” They suggest that additional studies, particularly longitudinal studies, should be completed in order to investigate changes in AGE levels over time.