Because both LPS and SAA1 induced the expression of bradykinin receptors and enhanced the induction of PTGS2 expression and PGE2 production by BK and DABK in amnion fibroblasts, we believe that the bradykinin system is also implicated in infection-induced preterm birth given the important role of LPS and SAA1 in infection-induced inflammation (25, 34). Here, PTGS2 is linked to infection.