Christopher Lee

Hofbauer cells (HBCs) are a population of macrophages found in high abundance within the stroma of the first-trimester human placenta. HBCs are the only fetal immune cell population within the stroma of healthy placenta. However, the functional properties of these cells are poorly described. Aligning with their predicted origin via primitive hematopoiesis, we find that HBCs are transcriptionally similar to yolk sac macrophages. Phenotypically, HBCs can be identified as HLA-DR-FOLR2+ macrophages. We identify a number of factors that HBCs secrete (including OPN and MMP-9) that could affect placental angiogenesis and remodeling. We determine that HBCs have the capacity to play a defensive role, where they are responsive to Toll-like receptor stimulation and are microbicidal. Finally, we also identify a population of placenta-associated maternal macrophages (PAMM1a) that adhere to the placental surface and express factors, such as fibronectin, that may aid in repair.

Cyclooxygenase (COX)-1- and COX-2-deficient mice have unique physiological differences that have allowed investigation into the individual biological roles of the COX isoforms. In the following, the phenotypes of the two COX knockout mice are summarized, and recent studies to investigate the effects of COX deficiency on inflammatory responses and cancer susceptibility are discussed. The data suggest that both isoforms have important roles in the maintenance of physiological homeostasis and that such designations as house-keeping and/or response gene may not be entirely accurate. Furthermore, data from COX-deficient mice indicate that both isoforms can contribute to the inflammatory response and that both isoforms have significant roles in carcinogenesis.