NADPH Oxidase Isoforms in COPD Patients and Acute Cigarette Smoke-Exposed Mice: Induction of Oxidative Stress and Lung Inflammation

Abstract

Cigarette smoke (CS) is a major risk factor for chronic obstructive pulmonary disease (COPD), which represents the third leading cause of death worldwide. CS induces reactive oxygen species (ROS) production, leading to pulmonary inflammation and remodeling. NADPH oxidases (NOXs) represent essential sources of ROS production in the cardiovascular system. Whether and how NOX isoforms are activated in COPD patients and in response to acute cigarette smoke (ACS) remains incompletely understood. In the present study, the expression of NOX isoforms was examined in the lungs of end-stage COPD patients. In addition, mice silenced of NOX1 or NOX4 expression using in vivo RNA interference (RNAi), and NOX2-deficient (NOX2−/y) mice, were exposed to ACS for 1 h using a standard TE-10B smoking machine. In lung sections isolated from COPD patients undergoing lung transplantation, protein expression of NOX1, NOX2, NOX4, or NOX5 was markedly upregulated compared to non-smoking donor controls. Likewise, ACS upregulated protein expression of NOX1, NOX2, and NOX4, production of ROS, inflammatory cell infiltration, and mRNA expression of proinflammatory cytokines TNF-α and KC in the mouse lung. In vivo RNAi knockdown of NOX1 or NOX4 decreased ACS-induced ROS production, inflammatory cell influx, and the expression of TNF-α and KC, which were accompanied by inhibition of the NF-κB-COX-2 axis. Although ACS-induced ROS production was reduced in the lungs of NOX2−/y mice, inflammatory cell influx and expression of NF-κB/COX-2 were increased. Taken together, our results demonstrate for the first time that NOX isoforms 1, 2, 4 and 5 all remain activated in end-stage COPD patients, while NOX1 and NOX4 mediate oxidative stress and inflammatory responses in response to acute cigarette smoke. Therefore, targeting different isoforms of NOX might be necessary to treat COPD at different stages of the disease, which represents novel mechanistic insights enabling improved management of the devastating disease.

The Causal Relationship between Chronic Obstructive Pulmonary Disease and Cardiovascular Diseases: Role of Systemic Inflammation and NF-κB/COX-2 Pathway

“…However, the exact mechanism underlying this phenomenon remains unclear, possibly attributed to the leakage of various proin ammatory markers from the lungs into the bloodstream. These ndings provide evidence for the presence of a systemic in ammatory response in individuals with COPD [44,45] .…”

Cigarette Smoke-Induced Reactive Oxygen Species Formation: A Concise Review

“…Consistent findings have been reported in isolated organ studies, with CS shown to stimulate NOX-dependent ROS production in isolated rat artery [ 123 ]. Evidence from animal studies has corroborated increased NOX activity with elevated basal ROS levels in lung tissue and bronchoalveolar lavage fluid (BALF) cells from CS-exposed mice [ 113 , 124 , 125 ]. These elevations were mitigated by conditional knockdown of NOX1, 2, and 4, and deletion of NOX2.…”

Blackberry consumption protects against e-cigarette-induced vascular oxidative stress in mice

“…39 Similarly, while all NOX isoforms are upregulated in lung tissue sections of patients with COPD, knockdown of NOX4 was more effective at reducing p-p65 expression and downstream TNF-α production in cigarette smoke-exposed mice. 40 Therefore, NOX4 is likely a significant contributor to lung disease progression and may be the main producer of ROS in lung conditions. Though we saw increases in NOX4, we did not observe changes in NT which may be due to the lack of change in NO metabolites in the lung.…”