PILRα binds an unknown receptor expressed primarily on CD56bright and decidual-NK cells and activates NK cell functions

Identification of Novel Prognostic Biomarkers Relevant to Immune Infiltration in Lung Adenocarcinoma

Background: Programmed death ligand-1 (PD-L1) is a biomarker for assessing the immune microenvironment, prognosis, and response to immune checkpoint inhibitors in the clinical treatment of lung adenocarcinoma (LUAD), but it does not work for all patients. This study aims to discover alternative biomarkers.

Methods: Public data were obtained from The Cancer Genome Atlas (TCGA) and Gene Expression Omnibus (GEO). Weighted gene co-expression network analysis (WGCNA) and gene ontology (GO) were used to determine the gene modules relevant to tumor immunity. Protein–protein interaction (PPI) network and GO semantic similarity analyses were applied to identify the module hub genes with functional similarities to PD-L1, and we assessed their correlations with immune infiltration, patient prognosis, and immunotherapy response. Immunohistochemistry (IHC) and hematoxylin and eosin (H&E) staining were used to validate the outcome at the protein level.

Results: We identified an immune response–related module, and two hub genes (PSTPIP1 and PILRA) were selected as potential biomarkers with functional similarities to PD-L1. High expression levels of PSTPIP1 and PILRA were associated with longer overall survival and rich immune infiltration in LUAD patients, and both were significantly high in patients who responded to anti–PD-L1 treatment. Compared to PD-L1–negative LUAD tissues, the protein levels of PSTPIP1 and PILRA were relatively increased in the PD-L1–positive tissues, and the expression of PSTPIP1 and PILRA positively correlated with the tumor-infiltrating lymphocytes.

Conclusion: We identified PSTPIP1 and PILRA as prognostic biomarkers relevant to immune infiltration in LUAD, and both are associated with the response to anti–PD-L1 treatment.

Roles of Glycans and Non-glycans on the Epithelium and in the Immune System in H1-H18 Influenza A Virus Infections

The large variation of influenza A viruses (IAVs) in various susceptible hosts and their rapid evolution, which allows host/tissue switching, host immune escape, vaccine escape, and drug resistance, are difficult challenges for influenza control in all countries worldwide. Access and binding of the IAV to actual receptors at endocytic sites is critical for the establishment of influenza infection. In this chapter, the progress in identification of and roles of glycans and non-glycans on the epithelium and in the immune system in H1-H18 IAV infections are reviewed. The first part of the review is on current knowledge of H1-H16 IAV receptors on the epithelium including sialyl glycans, other negatively charged glycans, and annexins. The second part of the review focuses on H1-H16 IAV receptors in the immune system including acidic surfactant phospholipids, Sia on surfactant proteins, the carbohydrate recognition domain (CRD) of surfactant proteins, Sia on mucins, Sia and C-type lectins on macrophages and dendritic cells, and Sia on NK cells. The third part of the review is about a possible H17-H18 IAV receptor. Binding of these receptors to IAVs may result in inhibition or enhancement of IAV infection depending on their location, host cell type, and IAV strain. Among these receptors, host sialyl glycans are key determinants of viral hemagglutinin (HA) lectins for H1-H16 infections. HA must acquire mutations to bind to sialyl glycans that are dominant on a new target tissue when switching to a new host for efficient transmission and to bind to long sialyl glycans found in the case of seasonal HAs with multiple glycosylation sites as a consequence of immune evasion. Although sialyl receptors/C-type lectins on immune cells are decoy receptors/pathogen recognition receptors for capturing viral HA lectin/glycans protecting HA antigenic sites, some IAV strains do not escape, such as by release with neuraminidase, but hijack these molecules to gain entry and replication in immune cells. An understanding of the virus-host battle tactics at the receptor level might lead to the establishment of novel strategies for effective control of influenza.

Pregnancy Induces an Immunological Memory Characterized by Maternal Immune Alterations Through Specific Genes Methylation

During pregnancy, the maternal immune system undergoes major adaptive modifications that are necessary for the acceptance and protection of the fetus. It has been postulated that these modifications are temporary and limited to the time of pregnancy. Growing evidence suggests that pregnancy has a long-term impact on maternal health, especially among women with pregnancy complications, such as preeclampsia (PE). In addition, the presence of multiple immunological-associated changes in women that remain long after delivery has been reported. To explain these long-term modifications, we hypothesized that pregnancy induces long-term immunological memory with effects on maternal well-being. To test this hypothesis, we evaluated the immunological phenotype of circulating immune cells in women at least 1 year after a normal pregnancy and after pregnancy complicated by PE. Using multiparameter flow cytometry (FCM) and whole-genome bisulfite sequencing (WGBS), we demonstrate that pregnancy has a long-term effect on the maternal immune cell populations and that this effect differs between normal pregnancy and pregnancy complicated by PE; furthermore, these modifications are due to changes in the maternal methylation status of genes that are associated with T cell and NK cell differentiation and function. We propose the existence of an "immunological memory of pregnancy (IMOP)" as an evolutionary advantage for the success of future pregnancies and the proper adaptation to the microchimeric status established during pregnancy. Our findings demonstrate that the type of immune cell populations modified during pregnancy may have an impact on subsequent pregnancy and future maternal health.

Nectin4 is a novel TIGIT ligand which combines checkpoint inhibition and tumor specificity

BACKGROUND

The use of checkpoint inhibitors has revolutionized cancer therapy. Unfortunately, these therapies often cause immune-related adverse effects, largely due to a lack of tumor specificity.

METHODS

We stained human natural killer cells using fusion proteins composed of the extracellular portion of various tumor markers fused to the Fc portion of human IgG1, and identified Nectin4 as a novel TIGIT ligand. Next, we generated a novel Nectin4 blocking antibody and demonstrated its efficacy as a checkpoint inhibitor in killing assays and in vivo.

RESULTS

We identify Nectin4 to be a novel ligand of TIGIT. We showed that, as opposed to all other known TIGIT ligands, which bind also additional receptors, Nectin4 interacts only with TIGIT. We show that the TIGIT-Nectin4 interaction inhibits natural killer cell activity, a critical part of the innate immune response. Finally, we developed blocking Nectin4 antibodies and demonstrated that they enhance tumor killing in vitro and in vivo.

CONCLUSION

We discovered that Nectin4 is a novel ligand for TIGIT and demonstrated that specific antibodies against it enhance tumor cell killing in vitro and in vivo. Since Nectin4 is expressed almost exclusively on tumor cells, our Nectin4-blocking antibodies represent a combination of cancer specificity and immune checkpoint activity, which may prove more effective and safe for cancer immunotherapy.

The paired receptors TIGIT and DNAM-1 as targets for therapeutic antibodies

One of the most exciting fields in modern medicine is immunotherapy, treatment which looks to harness the power of the immune system to fight disease. A particularly effective strategy uses antibodies designed to influence the activity levels of the immune system. Here we look at two receptors - TIGIT and DNAM-1 - which bind the same ligands but have opposite effects on immune cells, earning them the label `paired receptors'. Importantly, natural killer cells and cytotoxic T cells express both of these receptors, and in certain cases their effector functions are dictated by TIGIT or DNAM-1 signaling. Agonist and antagonist antibodies targeting either TIGIT or DNAM-1 present many therapeutic options for diseases spanning from cancer to auto-immunity. In this review we present cases in which the modulation of these receptors holds potential for the development of novel therapies.