Citations

Abstract An immunoinhibitory role of B7 homologue 1 (B7-H1) expressed by non-T cells has been established; however, the function of B7-H1 expressed by T cells is not clear. Peak expression of B7-H1 on Ag-primed CD8 T cells was observed during the contraction phase of an immune response. Unexpectedly, B7-H1 blockade at this stage reduced the numbers of effector CD8 T cells, suggesting B7-H1 blocking Ab may disturb an unknown function of B7-H1 expressed by CD8 T cells. To exclusively examine the role of B7-H1 expressed by T cells, we introduced B7-H1 deficiency into TCR transgenic (OT-1) mice. Naive B7-H1–deficient CD8 T cells proliferated normally following Ag stimulation; however, once activated, they underwent more robust contraction in vivo and more apoptosis in vitro. In addition, B7-H1–deficient CD8 T cells were more sensitive to Ca-dependent and Fas ligand-dependent killing by cytotoxic T lymphocytes. Activation-induced Bcl-xL expression was lower in activated B7-H1–deficient CD8 T cells, whereas Bcl-2 and Bim expression were comparable to the wild type. Transfer of effector B7-H1–deficient CD8 T cells failed to suppress tumor growth in vivo. Thus, upregulation of B7-H1 on primed T cells helps effector T cells survive the contraction phase and consequently generate optimal protective immunity.

Abstract Purpose: Release of inhibitory coregulatory proteins into the circulation may represent one mechanism by which tumors thwart immune responses. Our objective was to determine whether soluble B7-H1 (sB7-H1) levels in patients with clear cell renal cell carcinoma (ccRCC) are associated with pathologic features and patient outcome. Experimental Design: We developed an ELISA for quantification of sB7-H1 in biological fluids. Biochemical confirmation of the measured analyte as sB7-H1 was done by protein microsequencing using supernates from tumor cell lines. Biological activity of sB7-H1 was assessed in vitro utilizing T-cell apoptosis assays. We tested sB7-H1 levels in the sera from 172 ccRCC patients and correlated sB7-H1 levels with pathologic features and patient outcome. Results: sB7-H1 was detected in the cell supernatants of some B7-H1–positive tumor cell lines. Protein sequencing established that the measured sB7-H1 retained its receptor-binding domain and could deliver proapoptotic signals to T cells. Higher preoperative sB7-H1 levels were associated with larger tumors (P < 0.001), tumors of advanced stage (P = 0.017) and grade (P = 0.044), and tumors with necrosis (P = 0.003). A doubling of sB7-H1 levels was associated with a 41% increased risk of death (P = 0.010). Conclusion: Our observations suggest that sB7-H1 may be detected in the sera of ccRCC patients and that sB7-H1 may systemically impair host immunity, thereby fostering cancer progression and subsequent poor clinical outcome. Clin Cancer Res; 17(7); 1915–23. ©2011 AACR.

Previous linkage analysis of an Asian population proposed possible candidate genes for mandibular prognathism, such as Matrilin-1 (cartilage matrix protein). To investigate the association between the single-nucleotide polymorphisms (SNPs) in Matrilin-1 and mandibular prognathism, we investigated three sequence variants (-158 T>C, 7987 G>A, 8572 C>T) in 164 mandibular prognathism patients and 132 control individuals with a normal occlusion. The results showed that the 8572 TT genotypes in Matrilin-1 showed increased risk of mandibular prognathism (OR = 9.28, 95% Cl = 1.19~197.57, P < 0.05), whereas the 7987 AA genotype showed a protective effect for mandibular prognathism (OR = 0.16, 95% Cl = 0.05~0.47, P < 0.05). Genotyping results showed that the Matrilin-1 polymorphism haplotype TGC (ht4; 158T, 7987G, and 8572C alleles) had a pronounced risk effect for mandibular prognathism compared with controls (OR = 5.16, 95% Cl = 2.03~13.93, P < 0.01). The results suggest that polymorphisms in Matrilin-1 could be used as a marker for genetic susceptibility to mandibular prognathism.

Abstract Agonists of TLR have been explored as vaccine adjuvants for tumor immunotherapy. However, their immunological consequences are not fully understood. Although TLR signaling increases the functional potential of dendritic cells (DCs) for priming T cells, coinduction of potentially negative immunoregulatory capacities may impair effector T cell generation. We examined the expression and function of B7 family costimulatory molecules on DCs after activation with the TLR3 agonist, polyinosinic:polycytidylic acid. We demonstrated that polyinosinic:polycytidylic acid consistently up-regulated both B7-2 and B7-H1 molecules on resident, migratory DCs from spleen and lymph nodes. Depletion or blockade of B7-H1 on activated DCs increased the magnitude of effector CD8 T cell expansion. DC-based or protein-based tumor vaccines, in combination with B7-H1 blockade, induced strong effector CD8 T cell responses, resulting in protective immunity against newly established tumors. Our studies suggest that TLR3 signaling has the potential to up-regulate both positive and negative coregulatory molecules on APCs. Selective blockade of negative regulatory molecules in combination with TLR3 agonist may be an effective strategy for increasing the efficacy of tumor vaccines.

AbstractStromal elements present within the tumor microenvironment may suppress host immunity and promote the growth of malignant lymphocytes in B cell–derived non-Hodgkin lymphoma (NHL). In contrast, little is known about the microenvironment's role in T cell–derived NHL. B7-H1 (PD-L1, CD274), a member of the B7 family of costimulatory/coinhibitory ligands expressed by both malignant cells and stromal cells within the tumor microenvironment, has emerged as an important immune modulator capable of suppressing host immunity. Therefore, B7-H1 expression and function were analyzed in cutaneous and peripheral T-cell NHL. B7-H1 was expressed by tumor cells, monocytes, and monocyte-derived cells within the tumor microenvironment in T-cell NHL and was found to inhibit T-cell proliferation and promote the induction of FoxP3+ regulatory T cells. Collectively, the data presented provide the first evidence implicating B7-H1 in the suppression of host immunity in T-cell lymphoproliferative disorders and suggest that the targeting of B7-H1 may represent a novel therapeutic approach.