Systemic poly(ADP-ribose) polymerase-1 activation, chronic inflammation, and oxidative stress in COPD patients

Oxidative stress and systemic inflammation in chronic obstructive pulmonary disease (COPD) strongly suggest a role for the nuclear enzyme poly(ADP-ribose) polymerase-1 (PARP-1, E.C.2.4.2.30) in the disease pathophysiology. PARP-1 is highly activated by reactive oxygen species-induced DNA strand breaks, upon which it forms extensive poly(ADP-ribose) (PAR) polymers from its substrate NAD(+). We hypothesized that in COPD, chronic inflammation and oxidative stress would lead to systemic PARP-1 activation and to a reduced NAD(+) status. In a patient-control study, systemic PARP-1 activation was assessed by immunofluorescent detection of PAR polymers in peripheral blood lymphocytes. The percentage of PAR polymer-positive lymphocytes appeared to be higher in COPD patients (27 +/- 3%) than in healthy age-matched controls (17 +/- 2%, p <.05). Trolox equivalent antioxidant capacity (TEAC) of deproteinized plasma (p <.001), plasma uric acid (p <.05), as well as blood NAD(+) (p <.01) of stable COPD patients were significantly reduced when compared to controls. In addition, levels of proinflammatory cytokines IL-6, IL-8, and sICAM-1 were increased (p <.005) in COPD patients. In this study, evidence was found for the presence of systemic inflammation, chronic oxidative stress, and systemic PARP-1 activation in stable COPD patients. These data support a contribution of oxidative stress-induced PARP-1 activation to the pathophysiology of COPD.