CXCL2 and periodontitis: Mechanistically, periodontitis pathogen Porphyromonas gingivalis (P. gingivalis) relocated in the lung through the respiratory tract and LPS from P. gingivalis promoted the secretion of chemokines CXCL2 and G-CSF of alveolar epithelial cells through NF-κB and p38 MAPK pathways to recruit neutrophils.