ASK1 promotes uterine inflammation leading to pathological preterm birth.

It is widely accepted that enhanced uterine inflammation associated with microbial infection is a main causative factor for preterm birth. However, little is known about the molecular basis by which inflammation is associated with preterm birth. Here, we demonstrate that apoptosis signal-regulating kinase 1 (ASK1), a member of the mitogen-activated protein 3-kinase family, facilitates inflammation-induced preterm birth and that inhibition of ASK1 activity is sufficient to suppress preterm birth. ASK1-deficient pregnant mice exhibited reduced incidence of lipopolysaccharide (LPS)-induced preterm birth. ASK1 was required for the induction of LPS-induced inflammatory responses related to preterm birth, including pro-inflammatory cytokine production in the uterus and peritoneal cavities. In addition, selective suppression of uterine ASK1 activity through a chemical genetic approach reduced the incidence of LPS-induced preterm birth. Moreover, translational studies with human choriodecidua demonstrated that ASK1 was required for LPS-induced activation of JNK and p38 and pro-inflammatory cytokine production. Our findings suggest that ASK1 activation is responsible for the induction of inflammation that leads to preterm birth and that the blockade of ASK1 signaling might be a promising therapeutic target for preventing preterm birth.