OX40 and 4-1BB delineate distinct immune profiles in sarcoma.

Systemic relapse after radiotherapy and surgery is the major cause of disease-related mortality in sarcoma patients. Combining radiotherapy and immunotherapy is under investigation as a means to improve response rates. However, the immune contexture of sarcoma is understudied. Here, we use a retrospective cohort of sarcoma patients, treated with neoadjuvant radiotherapy, and TCGA data. We explore therapeutic targets of relevance to sarcoma, using genomics and multispectral immunohistochemistry to provide insights into the tumor immune microenvironment across sarcoma subtypes. Differential gene expression between radioresponsive myxoid liposarcoma (MLPS) and more radioresistant undifferentiated pleomorphic sarcoma (UPS) indicated UPS contained higher transcript levels of a number of immunotherapy targets (CD73/NT5E, CD39/ENTPD1, CD25/IL2RA, and 4-1BB/TNFRSF9). We focused on 4-1BB/TNFRSF9 and other costimulatory molecules. In TCGA data, 4-1BB correlated to an inflamed and exhausted phenotype. OX40/TNFRSF4 and 4-1BB/TNFRSF9 were highly expressed in sarcoma subtypes versus other cancers. Despite OX40 and 4-1BB being described as Treg markers, we identified that they delineate distinct tumor immune profiles. This was true for sarcoma and other cancers. While only a limited number of samples could be analyzed, spatial analysis of OX40 expression identified two diverse phenotypes of OX40+ Tregs, one associated with and one independent of tertiary lymphoid structures (TLSs). Patient stratification is of intense interest for immunotherapies. We provide data supporting the viewpoint that a cohort of sarcoma patients, appropriately selected, are promising candidates for immunotherapies. Spatial profiling of OX40+ Tregs, in relation to TLSs, could be an additional metric to improve future patient stratification.

Transferrin expression by placental trophoblastic cells.

Transferrin (TF), a 76-80 kDa glycoprotein, is responsible for the transport of iron to cells within both the fetal and maternal systems, but it does not cross the multiple cell layer barrier of the placenta. Recent findings that both rat and human placental cells produce TF indicated that placental TF may function in some manner to transport or regulate iron passage across this barrier. However, placental production of TF was brought into question because the cell preparations used to identify TF were obtained using dispersed tissue and may have contained non-placental contaminating elements. In this study, cultures of phenotypically distinct cell types containing only placental cells were used to firmly establish whether or not TF is expressed, and if so to begin to identify the cell(s) associated with its synthesis. Utilizing RT-PCR, in situ hybridization, and Western blot analysis, we identified TF mRNA and protein in three trophoblast cell types, HRP-1 (rat), Rcho-1 (rat), and BeWo (human) cells. Additionally, TF mRNA and protein were found in Giant cells, the differentiated form of Rcho-1 cells. When taken together, these results demonstrate clearly that TF is expressed by both differentiated and non-differentiated placental cells, and when viewed in light of previous findings, strengthen the possibility that placental TF may be central to the passage of iron from the mother to the fetus during development.