IL-12 Regulates B7-H1 Expression in Ovarian Cancerassociated Macrophages by Effects on NF-κB Signalling

Background and Aim: B7-H1, a co-inhibitory molecule of the B7 family, is found aberrantly expressed inovarian cancer cells and infiltrating macrophage/dendritic-like cells, and plays a critical role in immune evasionby ovarian cancer. IL-12, an inducer of Th1 cell development, exerts immunomodulatory effects on ovariancancer. However, whether IL-12 regulates B7-H1 expression in human ovarian cancer associated-macrophageshas not been clarified. Therefore, we investigated the effects of IL-12 on the expression of B7-H1 in ovariancancer-associated macrophages and possible mechanisms.
Methods: PMA induced THP-1-derived macrophagesor human monocyte-derived macrophages were treated with recombinant IL-12 (rIL-12) or infected withadenovirus carrying human IL-12 gene (Ad-IL-12-GFP) for 24 h, then cocultured with the SKOV3 ovariancancer cell line for another 24 h. Macrophages were collected for real-time PCR and Western blot to detect theexpression of B7-H1, and activation of the NF-κB signaling pathway. Moreover, supernatants were collected toassay for IL-12, IFN-γ and IL-10 by ELISA. In addition, monocyte-derived macrophages treated with IFN-γ werecocultured with SKOV3 and determined for the expression of B7-H1. Furthermore, the expression of B7-H1 inmonocyte-derived macrophages was also evaluated after blocking NF-κB signaling.
Results: The expression ofB7-H1 was significantly upregulated in monocyte-derived macrophages treated with rIL-12 or Ad-IL-12-GFPcompared with the control groups (p<0.05), accompanied by a remarkable upregulation of IFN-γ (p<0.05), amarked downregulation of IL-10 (p<0.05) and activation of NF-κB signaling. However, the upregulation of B7-H1 was inhibited by blocking the NF-κB signaling pathway (p<0.05). Expression of B7-H1 was also increased(p<0.05) in monocyte-derived macrophages treated with IFN-γ and cocultured with SKOV3. By contrast, theexpression of B7-H1 in THP-1-derived macrophages was significantly decreased when treated in the same wayas monocyte-derived macrophages (p<0.05), and IL-10 was also significantly decreased but IFN-γ was almostabsent.
Conclusions: IL-12 upregulates the expression of B7-H1 in monocyte-derived macrophages, which ispossible though inducing the secretion of IFN-γ and further activating the NF-κB signal pathway. However,IL-12 downregulates the expression of B7-H1 in THP-1-derived macrophages, associated with a lack of IFN-γand inhibition of expression of IL-10.