Recent clinical results for PD-1 blockade therapy have demonstrated durable tumor control with minimal immune-related adverse effects. PD-L1 is induced in non-lymphoid tissue cells and tumor cells, in addition to tissue-recruiting immune cells, under inflammatory conditions triggered by several cytokines, especially IFN-γ, and exogenous stimuli delivered by pathogen-associated molecular patterns. Receptor-mediated signaling molecules that affect the cell cycle, proliferation, apoptosis, and survival (including NF-κB, MAPK, PI3K, mTOR, and JAK/STAT) are involved in PD-L1 induction. PD-L1 expression in tumor cells is also triggered by the signals described above, but in some instances, intrinsic cell alteration associated with carcinogenesis contributes to PD-L1 induction. The tumor suppressor genes PTEN and Lkb1 and epithelial-mesenchymal transition-related molecules are also involved in the regulation of PD-L1 expression. Notably, squamous cell carcinoma of the head and neck (SCCHN) often exhibits both host immunosuppression and cytogenetic alternations of tumor cells. Precise understanding of how PD-L1 expression is controlled will allow the development of effective approaches to PD-1 blockade therapy for patients with SCCHN.
The B7 family member B7-H3 (CD276) plays important roles in immune responses. However, the function of B7-H3 remains controversial. We found that murine B7-H3 specifically bound to Triggering receptor expressed on myeloid cells (TREM)-like transcript 2 (TLT-2, TREML2). TLT-2 was expressed on CD8 + T cells constitutively and on activated CD4 + T cells. Stimulation with B7-H3 transfectants preferentially up-regulated the proliferation and IFN-γ production of CD8 + T cells. Transduction of TLT-2 into T cells resulted in enhanced IL-2 and IFN-γ production via interactions with B7-H3. Blockade of the B7-H3:TLT-2 pathway with a mAb against B7-H3 or TLT-2 efficiently inhibited contact hypersensitivity responses. Our results demonstrate a direct interaction between B7-H3 and TLT-2 that preferentially enhances CD8 + T cell activation.
Notch signaling plays critical roles in various cell types by regulating cell fate determination and differentiation. Here, we investigated the ability to control differentiation of human periodontal ligament derived mesenchymal stem cells using modified surfaces containing the affinity immobilized Notch ligand, Jagged-1. After seeding human periodontal ligament derived mesenchymal stem cells (HPDLs) on Jagged-1 modified surfaces, expression of Notch signaling target genes, Hes-1 and Hey-1, was higher than those exposed to soluble Jagged-1 or control surfaces. Upregulation of Notch signaling target genes was attenuated after treatment with the γ secretase inhibitor. Upon seeding the cells on Jagged-1 immobilized surface and maintained in osteogenic medium, alkaline phosphatase enzymatic activity and mineralization as well as mRNA expression of alkaline phosphatase (ALP), collagen type I (COL I) and osteopontin (OPN) were significantly increased compared to those of controls. However, osteocalcin (OCN) mRNA expression level was decreased when cells were exposed to Jagged-1 modified surfaces. HPDLs on Jagged-1 modified surfaces expressed lower TWIST2 mRNA levels than the control, suggesting that the mechanism whereby Jagged-1 enhances osteogenic differentiation of HPDLs may occur through Notch signaling and TWIST regulation. In summary, an alteration of biomaterial interface using Notch ligands illustrates a promising system to control HPDLs differentiation toward osteogenic lineage.
B7-H1 (CD274) is a T-cell coinhibitory molecule that is also often induced on human carcinoma cells, where its expression has been implicated in immune escape. Under inflammatory conditions, B7-H1 is also inducible in normal epithelial cells but little is known about its involvement in conversion of normal cells to tumor cells. Here, we show that skin-specific expression of B7-H1 accelerates inflammatory carcinogenesis in a methylcholantrene (MCA)-induced model of squamous cell carcinoma (SCC). Inflammatory responses induced by MCA or phorbol ester TPA were clearly inhibited in B7-H1 transgenic mice (B7-H1tg mice). Antibody-mediated blockade of either B7-H1 or the related molecule PD-1 revealed that their ability to limit inflammation relied on ligand interactions made by B7-H1 or PD-1. Skin keratinocytes derived from B7-H1tg mice exhibited constitutive reduction of E-cadherin, and SCC induced in B7-H1tg mice also showed loss of E-cadherin along with elevated expression of the transcription factors Slug and Twist that drive epithelial-mesenchymal transition (EMT). Our results indicate that upregulation of B7-H1 in skin epithelial cells promotes EMT and accelerates carcinogenesis, revealing insights into the significance of B7-H1 overexpression on solid tumor cells and hinting at a close relationship between EMT and immune escape signaling pathways in cancer. Cancer Res; 71(4); 1235-43. Ó2010 AACR.
Induction of the co-stimulatory molecule CD86 on dendritic cells (DCs) in the peripheral tissues is a critical event in triggering antigen-specific immune responses. In this study, we propose a new small interfering RNA (siRNA)-based therapy using cream-emulsified CD86 siRNA, targeting DCs for murine contact hypersensitivity (CH) and atopic dermatitis (AD)-like disease. Topical application of CD86 siRNA efficiently inhibited CH and markedly decreased the numbers of infiltrating CD86(+) or major histocompatibility complex (MHC) class II(+) cells in murine ear skin. The total number of cells, the percentage of hapten-carrying DCs, and their CD86 expression in the regional lymph nodes (RLNs) also significantly decreased. These results suggest that the silencing of CD86 in local DCs inhibits the recruitment and migration of DCs into the skin and RLNs, respectively, resulting in reduced antigen-specific local inflammation. The therapeutic efficacy of the CD86 siRNA was confirmed in AD-prone NC/Nga mice. Treatment produced marked amelioration in the clinical manifestations of AD and reduced the antigen-specific production of interleukin-4 (IL-4) and serum immunoglobulin E (IgE) and IgG1. Our results suggest that the targeting of cutaneous DCs by CD86 siRNA may be a promising strategy in the treatment of allergic skin disease.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.