Background: Tumor-associated macrophages (TAMs) are classified into two major phenotypes, M1 and M2. M1 TAMs suppress cancer progression, while M2 TAMs promote it. However, little is known regarding the role of TAMs in the development of ovarian cancer. Here, we investigated the relationship between TAM distribution patterns (density, microlocalization, and differentiation) and ovarian cancer histotypes, and we explored whether altered TAM distribution patterns influence long-term outcomes in ovarian cancer patients. Methods: A total of 112 ovarian cancer patients were enrolled in this study, and the subjects were divided into two groups according to their survival (< 5 years vs. ≥ 5 years). Immunohistochemistry and immunofluorescence were used to determine the density, microlocalization, and differentiation status of TAMs in ovarian cancer tissues for each histotype. Kaplan-Meier survival and multivariate Cox regression analyses were used to evaluate the prognostic significance of TAM-related parameters in ovarian cancer.

T-cell costimulation and coinhibition generated by engagement of the B7 family and their receptor CD28 family are of central importance in regulating the T-cell response, making these pathways very attractive therapeutic targets. Here we describe HERV-H LTRassociating protein 2 (HHLA2) as a member of the B7 family that shares 10-18% amino acid identity and 23-33% similarity to other human B7 proteins and phylogenetically forms a subfamily with B7x and B7-H3 within the family. HHLA2 is expressed in humans but not in mice, which is unique within the B7 and CD28 families. HHLA2 protein is constitutively expressed on the surface of human monocytes and is induced on B cells after stimulation with LPS and IFN-γ. HHLA2 does not interact with other known members of the CD28 family or the B7 family, but does bind a putative receptor that is constitutively expressed not only on resting and activated CD4 and CD8 T cells but also on antigen-presenting cells. HHLA2 inhibits proliferation of both CD4 and CD8 T cells in the presence of T-cell receptor signaling. In addition, HHLA2 significantly reduces cytokine production by T cells including IFN-γ, TNF-α, IL-5, IL-10, IL-13, IL-17A, and IL-22. Thus, we have identified a unique B7 pathway that is able to inhibit human CD4 and CD8 T-cell proliferation and cytokine production. This unique human T-cell coinhibitory pathway may afford unique strategies for the treatment of human cancers, autoimmune disorders, infection, and transplant rejection and may help to design better vaccines. Interactions between members of the B7 ligand and CD28 receptor families generate positive costimulation and negative coinhibition, which are of central importance in regulating T-cell responses (1-3). B7-1/B7-2/CD28/CTLA-4 is the most extensively characterized of these pathways. Ligands B7-1 (CD80) and B7-2 (CD86) on antigen-presenting cells (APCs) bind to CD28 on naïve T cells and provide a major costimulatory signal to activate naïve T cells. After the initial activation, coinhibitory molecule cytotoxic T lymphocyte antigen-4 (CTLA-4, CD152) is induced on T cells and engages the same B7-1 and B7-2 ligands to restrain T-cell function. In contrast to the costimulatory activity of CD28, the interaction of B7-1 or B7-2 with CTLA-4 is essential for limiting the proliferative response of recently activated T cells to antigen and CD28-mediated costimulation.During the past decade, several new pathways in the B7 and CD28 families have been identified, including B7h/ICOS, PD-L1/PD-L2/PD-1, B7-H3/receptor, and B7x/receptor. B7h (4) (also called ICOS-L, B7RP-1 (5), GL50 (6), B7H2 (7), LCOS (8), and CD275) binds to the inducible costimulator (ICOS, CD278) on activated T cells (9), which induces strong phosphatidylinositol 3-kinase activity (10, 11) and leads to the expression of transcription factors involved in follicular helper CD4 T (Tfh) differentiation (12). Therefore, the B7h/ICOS pathway provides critical T-cell help to B cells. Deficiencies in this pathway result in substantially reduced numbers of mem...

Purpose HHLA2 (B7H7/B7-H5/B7y) is a newly identified B7 family member that regulates human T cell functions. However, its protein expression in human organs and significance in human diseases are unknown. The objective of this study was to analyze HHLA2 protein expression in normal human tissues and cancers, its prognostic significance, to explore mechanisms regulating HHLA2 expression, and to identify candidate HHLA2 receptors. Experimental Design An immunohistochemistry protocol and a flow cytometry assay with newly generated monoclonal antibodies were developed to examine HHLA2 protein. HHLA2 gene copy number variation was analyzed from cancer genomic data. The combination of bioinformatics analysis and immunological approaches was established to explore HHLA2 receptors. Results HHLA2 protein was detected in trophoblastic cells of the placenta and the epithelium of gut, kidney, gallbladder and breast, but not in most other organs. In contrast, HHLA2 protein was widely expressed in human cancers from the breast, lung, thyroid, melanoma, pancreas, ovary, liver, bladder, colon, prostate, kidney, and esophagus. In a cohort of 50 patients with stage I–III triple negative breast cancer, 56% of patients had aberrant expression of HHLA2 on their tumors, and high HHLA2 expression was significantly associated with regional lymph node metastasis and stage. The Cancer Genome Atlas revealed that HHLA2 copy number gains were present in 29% of basal breast cancers, providing a potential mechanism for increased HHLA2 protein expression in breast cancer. Finally, Transmembrane and Immunoglobulin Domain Containing 2 (TMIGD2) was identified as one of the receptors for HHLA2. Conclusion Wide expression of HHLA2 in human malignancies, association with poor prognostic factors and its T cell coinhibitory capability, suggests that the HHLA2 pathway represents a novel immunosuppressive mechanism within the tumor microenvironment and an attractive target for human cancer therapy.