Co-inhibitory Molecule B7 Superfamily Member 1 Expressed by Tumor-Infiltrating Myeloid Cells Induces Dysfunction of Anti-tumor CD8+ T Cells.

The molecular mechanisms whereby CD8+ T cells become "exhausted" in the tumor microenvironment remain unclear. Programmed death ligand-1 (PD-L1) is upregulated on tumor cells and PD-1-PD-L1 blockade has significant efficacy in human tumors; however, most patients do not respond, suggesting additional mechanisms underlying T cell exhaustion. B7 superfamily member 1 (B7S1), also called B7-H4, B7x, or VTCN1, negatively regulates T cell activation. Here we show increased B7S1 expression on myeloid cells from human hepatocellular carcinoma correlated with CD8+ T cell dysfunction. B7S1 inhibition suppressed development of murine tumors. Putative B7S1 receptor was co-expressed with PD-1 but not T cell immunoglobulin and mucin-domain containing-3 (Tim-3) at an activated state of early tumor-infiltrating CD8+ T cells, and B7S1 promoted T cell exhaustion, possibly through Eomes overexpression. Combinatorial blockade of B7S1 and PD-1 synergistically enhanced anti-tumor immune responses. Collectively, B7S1 initiates dysfunction of tumor-infiltrating CD8+ T cells and may be targeted for cancer immunotherapy.

Expression of the inhibitory B7 family molecule VISTA in human colorectal carcinoma tumors.

Colorectal carcinoma (CRC) is one of the most common malignancies in the world. PD-1/PD-L1 inhibitors have benefited cancer patients with multiple tumor types. However, their efficacy for CRC is low and this treatment in melanoma patients results in adaptive resistance through upregulation of VISTA, another checkpoint inhibitory pathway. Thus, there is an urgent need to explore additional co-inhibitory molecular pathways such as VISTA for CRC treatment. In this study, C10orf54 (encoding VISTA) expression was analyzed by RNA-seq data from 367 CRC patients in human cancer datasets. Moreover, 28 clinical CRC specimens were used to assess VISTA protein expression. Human cancer datasets showed that CRC tumors expressed higher levels of C10orf54 than CD274 (encoding PD-L1). Moreover, C10orf54 mRNA expression was significantly correlated with genes responsible for tumor immune evasion. VISTA protein expression was high in tumors compared with para-tumors and normal tissues, which is similar to PD-L1 expression. However, in contrast to PD-L1, VISTA was mainly expressed by tumor-infiltrating lymphocytes. This study is the first investigation of VISTA expression in human resected CRC tumors, and the results justify the need for future studies on the role of VISTA in anti-CRC immunity in clinical samples.

Regulatory effects of ΔFosB on proliferation and apoptosis of MCF-7 breast cancer cells.

Matrix metalloproteinase-9 (MMP-9) plays a vital role in tumor angiogenesis, cell migration, and invasiveness because it can degrade almost all basement membrane and extracellular matrix components. MMP-9 has been reported in many cancers including breast cancer, lung cancer, and colon cancer. ΔFosB in mammary epithelial cells has been shown to regulate cell proliferation, differentiation, and death. We found that ΔFosB increased the expression of MMP-9 in MCF-7 breast cancer cells. ΔFosB overexpression in MCF-7 cells increased cellular viability and decreased cell apoptosis. SB-3CT, an inhibitor of MMP-9, promoted apoptosis, inhibited cell proliferation, induced cell cycle arrest, and downregulated the expression of antiapoptotic genes Bcl-2 and Bcl-xl in MCF-7 cells. ΔFosB increased the number of MCF-7 cells in G2/M and S phases, upregulated the expression of Bcl-2 and Bcl-xl, and protected MCF-7 cells from apoptosis induced by MMP-9 inhibition. We also found that ΔFosB overexpression in MCF-7 cells inhibited Ca(2+)-induced apoptosis and promoted cell proliferation. Therefore, ΔFosB may be a potential target in breast cancer cell apoptosis by regulating the expression of MMP-9.

A high-throughput method for measurement of glycohemoglobin in blood samples utilizing laser-accelerated proteolysis and MALDI-TOF MS.

Glycosylated hemoglobin A1c (HbA1c) is a useful marker for the diagnosis of diabetes mellitus. Commercial column separation methods for HbA1c measurement were lacking throughput and sometimes interfered with hemoglobin variants. In this work, we developed a high-throughput and specific method for HbA1c by quantitative measurement of N-terminal peptides (NT method). Two thousand specimens could be measured in 8 h. The high-throughput was achieved by using a fast analysis of matrix-assisted laser desorption ionization time of flight mass spectrometry (MALDI-TOF MS) and an efficient proteolysis accelerated by laser irradiation. An intensity ratio of glycosylated to non-glycosylated hemoglobin N-terminal peptides was used to calculate the HbA1c level in blood. Interference from Hb variants of N-terminal peptides could be excluded by a highly accurate mass selection. The coefficient of variation (CV) of intra-assay precision was 9.8 and 9.9%, respectively. The CVs of inter-assay precision over 20 days were 9.1 and 8.4%, respectively. Measurement results were well correlated with the commercially available column method (r = 0.995). The NT method is promising for large-scale screening for diabetes mellitus among people.

Systematic characterization of the tumor microenvironment in Chinese patients with hepatocellular carcinoma highlights intratumoral B cells as a potential immunotherapy target.

Hepatocellular carcinoma (HCC) is an immunogenic malignancy, which exhibits low responsiveness to programmed cell death protein­1 (PD­1)/programmed death ligand­1 (PD­L1) antibodies. Therefore, the identification of novel immunotherapeutic targets to treat HCC is imperative. Systematic characterization of the HCC tumor microenvironment (TME) can provide novel insight into additional therapeutic approaches. In the present study, the RNA­sequencing (RNA­seq) data of 360 patients with HCC were integrated from The Cancer Genome Atlas to assess the expression of membrane spanning 4­domains A1 (MS4A1; encoding CD20) in tumors and normal liver tissues. Immunofluorescence and multiplex tissue fluorescence analyses were performed and combined with flow cytometry staining to measure CD20/CD19 expression at the protein level. In addition, published single cell RNA­seq data of CD45+ cells were derived from 16 treatment­naïve patients from Beijing Shijitan Hospital with HCC to illustrate the characteristics of CD19+ B cells. The results indicated that the HCC TME included nuclear receptor subfamily 4 group A member 2+ (NR4A2) B cells. Patients with HCC and high density of intratumoral B cells demonstrated compromised antitumor immunity manifested by low percentages of cytotoxic CD8+ T cells and high density of regulatory T cells. Furthermore, PD­L1 expression was significantly correlated with the B cell signature marker CD20. The present study indicated that tumor­infiltrating B cells may play a negative role in antitumor immunity and serve as a promising target for HCC immunotherapy, alone or in combination with anti­PD­L1/PD­1 antibodies.

Author Correction: CD36 regulates lipopolysaccharide-induced signaling pathways and mediates the internalization of Escherichia coli in cooperation with TLR4 in goat mammary gland epithelial cells.

A correction has been published and is appended to both the HTML and PDF versions of this paper. The error has not been fixed in the paper.

Inhibition of the B7-H3 immune checkpoint limits tumor growth by enhancing cytotoxic lymphocyte function.

The interaction between tumor and the immune system is still poorly understood. Significant clinical responses have been achieved in cancer patients treated with antibodies against the CTLA4 and PD-1/PD-L1 checkpoints; however, only a small portion of patients responded to the therapies, indicating a need to explore additional co-inhibitory molecules for cancer treatment. B7-H3, a member of the B7 superfamily, was previously shown by us to inhibit T-cell activation and autoimmunity. In this study, we have analyzed the function of B7-H3 in tumor immunity. Expression of B7-H3 was found in multiple tumor lines, tumor-infiltrating dendritic cells, and macrophages. B7-H3-deficient mice or mice treated with an antagonistic antibody to B7-H3 showed reduced growth of multiple tumors, which depended on NK and CD8+ T cells. With a putative receptor expressed by cytotoxic lymphocytes, B7-H3 inhibited their activation, and its deficiency resulted in increased cytotoxic lymphocyte function in tumor-bearing mice. Combining blockades of B7-H3 and PD-1 resulted in further enhanced therapeutic control of late-stage tumors. Taken together, our results indicate that the B7-H3 checkpoint may serve as a novel target for immunotherapy against cancer.

The Effects of Matrix Metalloproteinase-9 on Dairy Goat Mastitis and Cell Survival of Goat Mammary Epithelial Cells.

Matrix metalloproteinase-9 (MMP-9) is a zinc-dependent enzyme, and plays a crucial role in extracellular matrix degeneration, inflammation and tissue remodeling. However, the relationship between MMP-9 and somatic cell count (SCC) in goat milk and the role of MMP-9 in the regulation of mastitis are still unknown. In this study, we found MMP-9 was predominantly expressed in the spleen, intestine and mammary gland. The SCC in goat milk was positively correlated with MMP-9 expression, and staphylococcus aureus could markedly increase MMP-9 expression in goat mammary epithelial cells (GMEC) in dosage and time dependent manner. We also demonstrated that SB-3CT, an inhibitor of MMP-9, promoted apoptosis and inhibited proliferation in GMEC. Thus, MMP-9 may emerge as an easily measurable and sensitive parameter that reflects the number of somatic cells present in milk and a regulatory factor of apoptosis in GMEC.

CD36 regulates lipopolysaccharide-induced signaling pathways and mediates the internalization of Escherichia coli in cooperation with TLR4 in goat mammary gland epithelial cells.

The scavenger receptor CD36 is involved in pathogen recognition, phagocytosis, and pathogen-induced signaling. This study investigated the relationship between CD36 and TLR4 in modifying lipopolysaccharide (LPS)-induced signaling pathways and mediating Escherichia coli (E. coli) endocytosis in primary goat mammary epithelial cells (pGMECs). The manipulation of CD36 expression significantly influenced TLR4 and nuclear factor kappa B (NF-κB) mRNA expression in pGMECs stimulated with LPS for 12 h. NF-κB and activator protein-1 (AP-1) activity was regulated by the manipulation of CD36 expression in LPS-induced pGMECs. However, CD36-mediated AP-1 activation occurred primarily through c-Jun N-terminal kinase (c-JNK). Adaptor proteins and proinflammatory cytokines were also involved in these signaling pathways and acted by regulating CD36 expression in LPS-stimulated cells. Moreover, CD36 cooperated with TLR4 in TLR4-mediated phagocytosis following E. coli simulation, but this complex was not induced by LPS treatment. Our study is the first to illuminate CD36 as a scavenger receptor in ruminants. Additionally, this study indicates that CD36 plays a vital role in the LPS-induced activation of downstream signaling cascades and mediates E. coli phagocytosis via TLR4 in pGMECs, which offers a novel treatment strategy for mastitis.

Gamma-Linolenic Acid Suppresses NF-κΒ Signaling via CD36 in the Lipopolysaccharide-Induced Inflammatory Response in Primary Goat Mammary Gland Epithelial Cells.

Gamma-linolenic acid (GLA) and linoleic acid (LA), which are both n-6 unsaturated fatty acids, play vital roles in lipopolysaccharide (LPS)-induced inflammation. The multi-functional protein scavenger receptor CD36 has also been shown to participate in inflammation. However, the molecular mechanisms underlying the interactions between CD36 and GLA or LA in LPS-induced inflammation remain unclear. We used small interfering RNA and adenoviral systems to manipulate CD36 expression in primary goat mammary gland epithelial cells (pGMECs), and the results showed that nuclear factor kappa B (NF-κB) levels were significantly decreased by CD36 receptor signaling following treatment with GLA but not LA. GLA inhibited NF-κB activation in LPS-induced pGMECs. However, silencing CD36 or deleting its fatty acid-binding domain blocked the anti-inflammatory effects of GLA, resulting in an increase in NF-κB activation and disrupting its localization during LPS-induced inflammation. The activity of the cytokines IL-1ß, IL-6, and TNF-α, which act downstream of NF-κB, was also modulated when CD34 expression was manipulated by the addition of GLA in LPS-induced pGMECs. Our data suggest that GLA, but not LA, may interact with the CD36 fatty acid-binding domain to regulate the activation and localization of NF-κB in LPS-induced pGMECs.