PTGS2 and Arthritis: In a study using a mouse model with collagen-induced arthritis, Haqqi et al. first reported that the supplementation of green tea polyphenols in the drinking water significantly reduced the incidence of arthritis in mice, as shown by (i) decreased type II collagen-specific IgG levels, (ii) the reduced expression of proinflammatory genes (COX2, TNF-α, IFN-γ), (iii) decreased joint infiltration by TNF-α and IFN-γ-producing cells, and (iv) increased neutral endopeptidase activity in arthritic joints [88].