Human Anti-Mouse TNFRSF11A monoclonal Antibody, clone SFB072 [PE]

Thymic epithelial cells (TECs) help orchestrate thymopoiesis, and TEC differentiation relies on bidirectional interactions with thymocytes. Although the molecular mediators that stimulate medullary thymic epithelial cell (mTEC) maturation are partially elucidated, the signals that regulate cortical thymic epithelial cell (cTEC) homeostasis remain elusive. Using IL-7 reporter mice, we show that TECs coexpressing high levels of IL-7 (Il7(YFP+) TECs) reside within a subset of CD205(+)Ly51(+)CD40(low) cTECs that coexpresses Dll4, Ccl25, Ccrl1, Ctsl, Psmb11, and Prss16 and segregates from CD80(+)CD40(high) mTECs expressing Tnfrsf11a, Ctss, and Aire. As the frequency of Il7(YFP+) TECs gradually declines as mTEC development unfolds, we explored the relationship between Il7(YFP+) TECs and mTECs. In thymic organotypic cultures, the thymocyte-induced reduction in Il7(YFP+) TECs dissociates from the receptor activator of NF-kappa B-mediated differentiation of CD80(+) mTECs. Still, Il7(YFP+) TECs can generate some CD80(+) mTECs in a stepwise differentiation process via YFP(-)Ly51(low)CD80(low) intermediates. Il7(YFP+) TECs are sustained in Rag2(-/-) mice, even following in vivo anti-CD3 epsilon treatment that mimics the process of pre-TCR beta-selection of thymocytes to the double positive (DP) stage. Using Marilyn-Rag2(-/-) TCR transgenic, we find that positive selection into the CD4 lineage moderately reduces the frequency of Il7(YFP+) TECs, whereas negative selection provokes a striking loss of Il7(YFP+) TECs. These results imply that the strength of MHC/peptide-TCR interactions between TECs and thymocytes during selection constitutes a novel rheostat that controls the maintenance of IL-7-expressing cTECs.

Background: Dendritic Cell-Specific Transmembrane Protein (DC-STAMP) is involved in osteoclastogenesis with a key role in mononucleated osteoclasts fusion. We reported in patients with Paget's disease of bone (PDB) a rare variant (rs62620995) in the TM7574 gene, encoding for DC-STAMP, which changes a highly conserved amino acid, possibly damaging according to in silica predictions. This study aimed at determining the functional effects of this variant on osteoclast phenotype in PUB. Methods: Fifty ml of peripheral blood were collected in pagetic patients carrier of this variant (n = 4) or not (n = 4) and healthy controls (n = 4). Monocytes were collected after Ficoll gradient and cultured in a medium containing RANKL (40 ng/ml) and hMCSF (25 ng/ml). At the end of the differentiation period, we assessed the osteoclast morphology and bone resorption abilities. We quantified gene expression of SOSTM1, DC-STAMP 059, CRE83, LAMP), 0C-STAMP, and NFATC1 genes from cell lysates. Proteins encoded by these genes were investigated by Western Blot. Statistical analyses relied on ANOVA followed by Tukey post-tests. Results: After 21 days of differentiation, the mean number of nuclei per multinucleated cell was significantly higher in pagetic patients carrier of the variant than in healthy controls. Bone resorption abilities were not modified by the variant. qPCR and Western Blot analyses did not provide any differences, but DC-STAMP expression was higher in patients carrier of the variant than in patients non carrier. Conclusions: This TM7SF4 rare variant may have an impact on osteoclast morphology and on DC-STAMP expression during osteoclastogenesis. Further analyses are required to understand the role of this variant during osteoclastogenesis in PDB.