Immunohistochemical distribution of toll-like receptor 4 in preterm human fetal membrane.

Aim:  Toll-like receptor 4 (TLR-4) is the major receptor used for recognition of specific gram negative bacteria by the host immune system. The role of TLR-4 has been revealed in preterm parturition. This study aims to demonstrate the immunohistochemical expression of TLR-4 with regard to histological layers and anatomical regions of the human fetal membranes. Material and Methods:  Fetal membranes were obtained from the uterine fundus and low segment. Immunohistochemical staining for TLR-4 and hematoxylin and eosin stain were performed. Results:  The chorion expressed significantly higher levels of TLR-4 than the amnion (P = 0.001). There was no difference in the expression of TLR-4 between the uterine fundus and the uterine low segment (P = 0.942). There was no significant difference in TLR-4 expression according to the presence of histological chorioamnionitis (P = 0.444). TLR-4 expression decreased significantly with the progression of gestation (P = 0.002). Conclusions:  The level of expression of TLR-4 did not differ according to anatomic location, but did differ according to the histological layer of the human fetal membranes and gestational age. These results suggest that TLR-4 may be involved in preterm parturition.