The Function and Oncological Significance of PD-L1 and its Antibodies

The PD-L1 protein, also known as programmed death-ligand 1 is a protein encoded in the CD274 gene. Specifically, PD-L1 belongs to the immunoglobulin superfamily of proteins, and it is a transmembrane protein that allows nutrients across the cell membrane 11. PD-L1 works in close connection with T cells (thymus cells) and B cells (bone marrow or bursa-derived cells)1. PD-L1 binds to the PD-L receptor on T cells to regulate and sometimes inhibit (in the case of cancer) the activated T cells, B cells, and myeloid cells. Once their activation is inhibited by PD-L1, the T-cells are unable to fight foreign substances in the body like infections, diseases, and cancers, thus allowing cancerous tumors to grow without check3. Elevated levels of PD-L1 have been found in a variety of cancers, including melanoma, non-small cell lung cancer (NSCLC), Hodgkin’s lymphoma, bladder cancer, renal cell carcinoma (RCC), head and neck squamous cell carcinoma (HNSCC), breast cancer, Merkel cell carcinoma, hepatocellular carcinoma (HCC) and gastric cancer (GC)4. Among other information, this study also examines the protein sequence of PD-L1, alignments of the sequence, the structure, functional domains, gene expression, copy number, and mutation profiles.

Ranaviruses Bind Cells from Different Species through Interaction with Heparan Sulfate

Ranavirus cross-species infections have been documented, but the viral proteins involved in the interaction with cell receptors have not yet been identified. Here, viral cell-binding proteins and their cognate cellular receptors were investigated using two ranaviruses, Andrias davidianus ranavirus (ADRV) and Rana grylio virus (RGV), and two different cell lines, Chinese giant salamander thymus cells (GSTC) and Epithelioma papulosum cyprinid (EPC) cells. The heparan sulfate (HS) analog heparin inhibited plaque formation of ADRV and RGV in the two cell lines by more than 80% at a concentration of 5 μg/mL. In addition, enzymatic removal of cell surface HS by heparinase I markedly reduced plaque formation by both viruses and competition with heparin reduced virus-cell binding. These results indicate that cell surface HS is involved in ADRV and RGV cell binding and infection. Furthermore, recombinant viral envelope proteins ADRV-58L and RGV-53R bound heparin-Sepharose beads implying the potential that cell surface HS is involved in the initial interaction between ranaviruses and susceptible host cells. To our knowledge, this is the first report identifying cell surface HS as ranavirus binding factor and furthers understanding of interactions between ranaviruses and host cells.

Interaction between Two Iridovirus Core Proteins and Their Effects on Ranavirus (RGV) Replication in Cells from Different Species

The two putative proteins RGV-63R and RGV-91R encoded by Rana grylio virus (RGV) are DNA polymerase and proliferating cell nuclear antigen (PCNA) respectively, and are core proteins of iridoviruses. Here, the interaction between RGV-63R and RGV-91R was detected by a yeast two-hybrid (Y2H) assay and further confirmed by co-immunoprecipitation (co-IP) assays. Subsequently, RGV-63R or RGV-91R were expressed alone or co-expressed in two kinds of aquatic animal cells including amphibian Chinese giant salamander thymus cells (GSTCs) and fish Epithelioma papulosum cyprinid cells (EPCs) to investigate their localizations and effects on RGV genome replication. The results showed that their localizations in the two kinds of cells are consistent. RGV-63R localized in the cytoplasm, while RGV-91R localized in the nucleus. However, when co-expressed, RGV-63R localized in both the cytoplasm and the nucleus, and colocalized with RGV-91R in the nucleus. 91R△NLS represents the RGV-91R deleting nuclear localization signal, which is localized in the cytoplasm and colocalized with RGV-63R in the cytoplasm. qPCR analysis revealed that sole expression and co-expression of the two proteins in the cells of two species significantly promoted RGV genome replication, while varying degrees of viral genome replication levels may be linked to the cell types. This study provides novel molecular evidence for ranavirus cross-species infection and replication.

Activated protein C targets immune cells and rheumatoid synovial fibroblasts to prevent inflammatory arthritis in mice

Objectives To investigate whether activated protein C (APC), a physiological anticoagulant can inhibit the inflammatory/invasive properties of immune cells and rheumatoid arthritis synovial fibroblasts (RASFs) in vitro and prevent inflammatory arthritis in murine antigen-induced arthritis (AIA) and CIA models. Methods RASFs isolated from synovial tissues of patients with RA, human peripheral blood mononuclear cells (PBMCs) and mouse thymus cells were treated with APC or TNF-α/IL-17 and the following assays were performed: RASF proliferation and invasion by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) and cell invasion assays, respectively; cytokines and signalling molecules using ELISA or western blot; Th1 and Th17 phenotypes in human PBMCs or mouse thymus cells by flow cytometry. The in vivo effect of APC was evaluated in AIA and CIA models. Results In vitro, APC inhibited IL-1β, IL-17 and TNF-α production, IL-17-stimulated cell proliferation and invasion and p21 and nuclear factor κB activation in RASFs. In mouse thymus cells and human PBMCs, APC suppressed Th1 and Th17 phenotypes. In vivo, APC inhibited pannus formation, cartilage destruction and arthritis incidence/severity in both CIA and AIA models. In CIA, serum levels of IL-1β, IL-6, IL-17, TNF-α and soluble endothelial protein C receptor were significantly reduced by APC treatment. Blocking endothelial protein C receptor, the specific receptor for APC, abolished the early or preventative effect of APC in AIA. Conclusion APC prevents the onset and development of arthritis in CIA and AIA models via suppressing inflammation, Th1/Th17 phenotypes and RASF invasion, which is likely mediated via endothelial protein C receptor.

Single-Cell Analysis Identifies Thymic Maturation Delay in Growth-Restricted Neonatal Mice

Fetal growth restriction (FGR) causes a wide variety of defects in the neonate which can lead to increased risk of heart disease, diabetes, anxiety and other disorders later in life. However, the effect of FGR on the immune system, is poorly understood. We used a well-characterized mouse model of FGR in which placental Igf-2 production is lost due to deletion of the placental specificIgf-2P0promotor. The thymi in such animals were reduced in mass with a ∼70% reduction in cellularity. We used single cell RNA sequencing (Drop-Seq) to analyze 7264 thymus cells collected at postnatal day 6.We identified considerable heterogeneity among the Cd8/Cd4 double positive cells with one subcluster showing marked upregulation of transcripts encoding a sub-set of proteins that contribute to the surface of the ribosome. The cells from the FGR animals were underrepresented in this cluster. Furthermore, the distribution of cells from the FGR animals was skewed with a higher proportion of immature double negative cells and fewer mature T-cells. Cell cycle regulator transcripts also varied across clusters. The T-cell deficit in FGR mice persisted into adulthood, even when body and organ weights approached normal levels due to catch-up growth. This finding complements the altered immunity found in growth restricted human infants. This reduction in T-cellularity may have implications for adult immunity, adding to the list of adult conditions in which thein uteroenvironment is a contributory factor.

Resolution of primary hyperparathyroidism following surgical removal of cervical thymus

Recent research has emphasized the capacity of thymus cells of producing parathyroid hormone (PTH) if adequately stimulated, and have investigated the role of the so-called “thymic PTH”, produced by the medullary thymic epithelial cells (m-TECs). To the best of our knowledge, only a single case of well-documented PTH secretion from a thymoma causing primary hyperparathyroidism (PHTP) has been reported in the literature so far. We report here the case of a female patient with PHTP who underwent neck exploration for a suspected parathyroid adenoma. After surgery, a normalization of serum PTH concentration was observed, but the histological examination of the surgically excised mass revealed exclusively normal thymus tissue. The present case provides additional evidence of PHTP caused by an ectopic thymus.