Gene expression analysis also indicated that the expression levels of IL 17/IFN γ and M2 related genes ARG1, CD206, MMP9, MMP12, TGF β, IL 4, and IL10 were higher in COPD BALF samples with the presence of P. gingivalis (Fig. 6B). The gene discussed is ARG1; the disease is chronic obstructive pulmonary disease.