The reason why inflammation persists in COPD patients even after long-term smoking cessation is currently unknown . The above loop breaking results may provide novel insight into the aforementioned smoking cessation effects. After cigarette smoking cessation, the disease remains if these positive feedback loops continuously work to cause the tissue damage. But when TD is reduced due to smoking cessation to such an extent that these positive feedback loops are unable to drive tissue damage further, COPD will be suppressed.