The differential expression of toll like receptors and RIG-1 in the placenta of neonates with in utero infections

Abstract

Novel biomarkers of in utero infections are needed to help guide early therapy. The toll like receptors (TLRs) and retinoic acid-inducible gene 1 (RIG-1) are proteins involved in the initial reaction of the innate immune system to infectious diseases. This study tested the hypothesis that a panel of TLRs and RIG-1 in the placenta could serve as an early biomarker of in utero infections. The TLRs and RIG-1 expression as determined by immunohistochemistry was scored in 10 control placentas (normal delivery or neonatal damage from known non-infectious cause), 8 placentas from documented in utero bacterial infection, and 7 placentas from documented in utero viral infections blinded to the clinical information. The non-infected placentas showed the following profile: no expression (TLR1, TLR3, TLR4, TLR7, TLR8), moderate expression (TLR2), and strong expression (RIG-1). The bacterial and viral infection cases shared the following profile: no to mild expression (TLR 2, TLR7, and RIG1), moderate expression (TLR4), and strong expression (TLR1, TLR3, and TLR8). The histologic findings in the chorionic villi were equivalent in the infected cases and controls, underscoring the need for molecular testing by the surgical pathologist when in utero infection is suspected. The results suggest that a panel of TLRs/RIG-1 analyses can allow the pathologist and/or clinician to diagnose in utero infections soon after birth. Also, treatments to antagonize the effects of TLR1, 3, and 8 may help abrogate in utero neonatal damage.

Keywords: Bacteria; In utero; Placenta; RIG-1; TLR; Viral.