Placental immune editing switch (PIES): learning about immunomodulatory pathways from a unique case report.

The hypothesis of this work is that, in order to escape the natural immune surveillance mechanisms, cancer cells and the surrounding microenvironment might express ectopically genes that are physiologically present in the placenta to mediate fetal immune-tolerance. These natural "placental immune-editing switch" mechanisms (PIES) may represent the result of millions of years of mammalian evolution developed to allow materno-fetal tolerance. Here, we introduce genes of the immune regulatory pathways that are either similarly over- or under-expressed in tumor vs normal tissue. Our analysis was carried out in primary breast cancer with metastatic homolateral axillary lymph nodes as well as placenta tissue (both uterine decidual tissue and term placenta tissue) from a pregnant woman. Gene expression profiling of paired non-self and self tissues (i.e. placenta/uterus; breast cancer/normal breast tissue; metastatic lymphnode/normal lymphnode tissue) was performed using the PanCancer Immune gene panel, a 770 Nanostring gene expression panel. Our findings reveal overlapping in specific immune gene expression in placenta and cancer tissue, suggesting that these genes might play an important role in maintaining immune tolerance both physiologically (in the placenta) and pathologically (in the cancer setting).