MUC5AC and chronic obstructive pulmonary disease: L. plantarum KF511 reduced immune cell infiltration and the production of mucin, matrix metalloproteinases, cytokines, and chemokines in bronchoalveolar lavage fluid. It also mitigated tissue damage and excessive mucin secretion in the lungs. Additionally, L. plantarum KF511 inhibited the activation of mitogen-activated protein kinases in the lungs of COPD mice and in NCI-H292 cells.