TNF and chronic obstructive pulmonary disease: In mice with COPD exposed to PM2.5, PM2.5 reduced NAD+/SIRT1 activity to increase the activity of histone acetyltransferases, resulting in elevated expression of pro-inflammatory genes in AM (43), releasing potent proinflammatory factors such as tumor necrosis factor (TNF)-α, IL-1β, and IL-8, causing a large influx of neutrophils from the circulation into the lung tissue (44).