Dissecting T-cell heterogeneity in esophageal squamous cell carcinoma reveals the potential role of LAIR2 in antitumor immunity.

Esophageal squamous cell carcinoma (ESCC), one of the most commonly diagnosed and lethal malignant diseases, has a complex tumor ecosystem. An obvious requirement for T-cell-mediated tumor control is the infiltration of tumor-reactive T cells into the tumor. Here, we obtained detailed T-cell compositions in both ESCC tumors and matched peripheral blood mononuclear cells (PBMCs) at single-cell resolution. We demonstrated that T cells in tumors and PBMCs had different compositions and functional states. ESCC tumors were rich in Treg and exhausted T cells but poor in cytotoxic and naïve T cells compared with PBMCs. The exhausted T cells showed higher exhausted signature in tumors than in PBMCs, while the cytotoxic T cells exhibited higher cytotoxic signature in PBMCs than in tumors. Our data indicated an immunosuppressive status and a defect at the level of T-cell priming in the tumor microenvironment. Leukocyte-associated Ig-like receptor-2 (LAIR2), a soluble collagen receptor that prevents the binding of human leukocyte-associated Ig-like receptor-1 (LAIR1) to collagens, was predominantly expressed in proliferating CD8+ T and Treg cells in tumors but in cytotoxic cells in PBMCs. LAIR2 could inhibit tumor metastasis, invasion, and collagen deposition via suppressing transforming growth factor-ß signaling. These findings revealed differential T-cell populations in tumors and PBMCs and provided convincing evidence that LAIR2 acted as a tumor suppressor.

TGF-ß-p-STAT1-LAIR2 axis has a "self-rescue" role for exhausted CD8+ T cells in hepatocellular carcinoma.

BACKGROUND: TGF-ß is related to the function of T cells in the tumor microenvironment. However, the characteristics of TGF-ß affecting the function of CD8+ T cells in hepatocellular carcinoma (HCC) have not been clearly resolved. METHODS: In this study, flow cytometry, mass cytometry, immunohistochemistry, RNA-seq, single-cell RNA-seq, assay for transposase-accessible chromatin with high throughput sequencing, chromatin immunoprecipitation, and dual-luciferase reporter gene assay were used to study the regulatory effect and molecular mechanism of TGF-ß on HCC infiltrating CD8+ T cells. RESULTS: Here, we demonstrated that the overall effect of TGF-ß on CD8+ T cells in HCC was to activate p-p38 to induce exhaustion, but it also initiated cell-intrinsic resistance mechanisms: 1) TGF-ß upregulated the levels of p-STAT1 (S727) and promoted LAIR2 secretion; 2) the TGF-ß-p-STAT1-LAIR2 axis relieved CD8+ T cells from exhaustion, which we called "self-rescue"; 3) this "self-rescue" behavior showed time and dose limitations on TGF-ß stimulation, which was easily masked by stronger inhibitory signals; 4) the function of CD8+ T cells was improved by using TAK-981 to amplify "self-rescue" signal. CONCLUSION: Our study describes a "self-rescue" mechanism of CD8+ T cells in HCC against exhaustion and the good effects from amplifying this signal.

Tumor-Associated Regulatory T Cell Expression of LAIR2 Is Prognostic in Lung Adenocarcinoma.

Cancer development requires a permissive microenvironment that is shaped by interactions between tumor cells, stroma, and the surrounding matrix. As collagen receptors, the leukocyte-associated immunoglobulin-like receptor (LAIR) family allows the immune system to interact with the extracellular matrix. However, little is known about their role in regulating tumor immunity and cancer progression. METHODS: Genetic analysis of resected human lung adenocarcinoma was correlated to clinical-pathological characteristics, gene ontologies, and single cell RNA sequencing (scRNASeq). LAIR2 production was determined in subsets of immune cells isolated from blood leukocytes and lung adenocarcinoma tumor. Functional assays were used to determine the role of LAIR2 in tumorigenesis. RESULTS: LAIR2 expression was adversely prognostic in lung adenocarcinoma. LAIR2 was preferentially produced by activated CD4+ T cells and enhanced in vitro tumor invasion into collagen. scRNASeq analysis of tumor infiltrating T cells revealed that LAIR2 expression co-localized with FOXP3 expressing cells and shared a transcriptional signature with tumor-associated regulatory T (Treg) cells. A CD4+ LAIR2+ Treg gene signature was prognostically significant in the TCGA dataset (n = 439; hazard ratio (HR) = 1.37; 95% confidence interval (CI), 1.05-1.77, p = 0.018) and validated in NCI Director's Challenge lung adenocarcinoma dataset (n = 488; HR = 1.54; 95% CI, 1.14-2.09, p = 0.0045). CONCLUSIONS: Our data support a role for LAIR2 in lung adenocarcinoma tumorigenesis and identify a CD4+ LAIR2+ Treg gene signature in lung adenocarcinoma prognosis. LAIR2 provides a novel target for development of immunotherapies.

Cancer immunotherapy based on blocking immune suppression mediated by an immune modulator LAIR-1.

The leukocyte-associated immunoglobulin-like receptor 1 (LAIR-1) is an inhibitory receptor expressed on the majority of peripheral blood mononuclear cells and is important for the regulation of immune responses. The binding of LAIR-1 to its ligands results in the loss of immune function in the tumor microenvironment (TME) and a reduction in T cell function and immune responses of antigen-presenting cells. Using bioinformatics analysis, we showed that LAIR-1 is broadly upregulated in multiple types of cancer. By designing a LAIR-2-Fc recombinant protein to block the binding of LAIR-1 to its ligand collagen, we observed augmented cytotoxic T cell infiltration and function resulting in antitumor immune responses that eliminated cancer cells. Besides, LAIR-2-Fc fusion protein potentiated the antitumor effect of PD-1/L1 checkpoint blockade therapy. Collectively, our results support the targeting of LAIR-1 for potential immunotherapeutic applications.

Human-specific LAIR2 contributes to the high invasiveness of human extravillous trophoblast cells.

The placenta is a temporary vital organ for intra-uterine development and growth. The anatomical structure of the placenta has evolved substantially, resulting in broad inter-species diversity. In particular, human placental extravillous trophoblast cells (EVTs) have evolved aggressive features, although the mechanism underlying this aggressiveness remains elusive. In the present study, we compared the human and mouse homologous gene databases and obtained 2272 human-specific genes, 807 of which are expressed in the placenta according to the UniGene database. Using the human trophoblast cell line HTR8/SVneo, we further verified the expression and function of one of these genes, the leukocyte-associated immunoglobulin-like receptor 2 (LAIR2). This gene shows increased expression during pregnancy and its reduced expression is associated with pregnancy complications. Although LAIR2 was expressed in the human placenta villus and decidua in the first trimester of pregnancy, it was not expressed in mouse tissues. Knockdown of LAIR2 markedly improved cell viability and inhibited the invasive ability of HTR8/SVneo cells. These data suggest that species-specific genes are pivotal to the evolution of a more aggressive human placenta to match the physiological demands of human development. Further investigation is required to obtain evidence on the function of LAIR2 and other specific genes in the placenta, providing insight on the mechanism, properties, and possible applications of this in humans.

Development of a quantitative ELISA kit for human secreted CD306/LAIR-2 and its application.

AIM: A quantitative ELISA kit for the detection of human secreted CD306/LAIR-2 was developed using monoclonal and polyclonal antibodies which were raised against a highly purified recombinant human secreted CD306/LAIR-2. METHODS: Anti-human secreted CD306/LAIR-2 monoclonal and polyclonal antibodies were raised by immunizing mouse or rabbit with recombinant human secreted CD306/LAIR-2. The monoclonal antibody was purified by protein G affinity, whereas the polyclonal antibody was purified by protein A affinity. The best match pair of antibodies were found and used to develop a double antibody sandwich ELISA kit for the detection of human secreted CD306/LAIR-2 in human samples. RESULTS: A human secreted CD306/LAIR-2 ELISA kit was formulated with highly purified recombinant human secreted CD306/LAIR-2, highly specific monoclonal and polyclonal antibodies. This kit realized the quantitative measurement of recombinant human CD306/LAIR-2 and natural CD306/LAIR-2 in human serum samples. CONCLUSIONS: The developed human secreted CD306/LAIR-2 ELISA kit is a reliable quantitation immunoassay kit.

Development of a quantitative ELISA kit for human secreted CD306/LAIR-2 and its application / 中国天然药物

AIM@#A quantitative ELISA kit for the detection of human secreted CD306/LAIR-2 was developed using monoclonal and polyclonal antibodies which were raised against a highly purified recombinant human secreted CD306/LAIR-2.@*METHODS@#Anti-human secreted CD306/LAIR-2 monoclonal and polyclonal antibodies were raised by immunizing mouse or rabbit with recombinant human secreted CD306/LAIR-2. The monoclonal antibody was purified by protein G affinity, whereas the polyclonal antibody was purified by protein A affinity. The best match pair of antibodies were found and used to develop a double antibody sandwich ELISA kit for the detection of human secreted CD306/LAIR-2 in human samples.@*RESULTS@#A human secreted CD306/LAIR-2 ELISA kit was formulated with highly purified recombinant human secreted CD306/LAIR-2, highly specific monoclonal and polyclonal antibodies. This kit realized the quantitative measurement of recombinant human CD306/LAIR-2 and natural CD306/LAIR-2 in human serum samples.@*CONCLUSIONS@#The developed human secreted CD306/LAIR-2 ELISA kit is a reliable quantitation immunoassay kit.