PD-L1 expression is regulated by both DNA methylation and NF-kB during EMT signaling in non-small cell lung carcinoma

Tumor cells, which undergo Epithelial-mesenchymal transition (EMT) acquire increased capacities of proliferation, invasion and have the ability to generate metastases by escaping the immune system during their systemic migration. To escape the immune system, cancer cells may induce tolerance or resist elimination by immune effectors via multiple mechanisms and we hypothesized that EMT may control the expression of immune checkpoint inhibitors, then promoting immune evasion. PD-L1 (programmed cell death ligand 1) but not PD-L2 nor Galectin 9 or Death receptor (DR4, DR5 and Fas) and ligands (FasL and TRAIL) expression was up-regulated during cytokine-driven EMT in a reversible manner. Moreover PD-L1 is overexpressed in VIMENTIN positive NSCLC tissues. We also demonstrated that the expression of PD-L1 required both TNFα and TGFβ1. Indeed, TGFβ1 decreased DNMT1 content and that resulted in PD-L1 promoter demethylation whereas TNFα induced the NF-κB pathway that promoted expression of demethylated PD-L1 promoter.

An alternative splicing variant in Clcn7-/- mice prevents osteopetrosis but not neural and retinal degeneration

The ubiquitously expressed chloride channel 7 (CLCN7) is present within the ruffled border of osteoclasts. Mutations in the CLCN7 gene in humans (homologous to murine Clcn7) are responsible for several types of osteopetrosis in humans, and deficiencies in CLCN7 can present with retinal degeneration and a neuronal storage disease. A previously reported Clcn7(-/-) mouse showed diffuse osteopetrosis accompanied by severe retinal and neuronal degeneration. In contrast, the authors produced a novel Clcn7(-/-) mutant where mice did not develop osteopetrosis but still developed lethal neural and retinal degeneration. In these mice, there was a rapid progressive loss of the outer nuclear layer and photoreceptor layers of the retina. Laminar degeneration and necrosis of neurons in layers IV and V of the cerebral cortex and in the CA2/CA3 regions of the hippocampus were associated with intraneuronal accumulations of autofluorescent granules (periodic acid-Schiff positive). The extensive reactive gliosis was always associated with the accumulation of intraneuronal cytoplasmic material. The authors found, through quantitative real time polymerase chain reaction analyses, that an alternate Clcn7 transcript (previously identified only in bone marrow) showed minimal expression in the brain and eye but moderate expression in bone, which correlates with rescue of the osteopetrotic phenotype in the face of continued retinal and neuronal degeneration. Findings in this knockout mouse model prove that osteopetrotic compression of the brain is not responsible for neuronal and retinal degeneration in CLCN7-deficient mice; rather, they suggest that neurotoxicity is most likely due to lysosomal dysfunction as a result of the functional lack of this chloride channel in the central nervous system and eye.

Poly-L-glutamate, an anionic polymer, enhances transgene expression for plasmids delivered by intramuscular injection with in vivo electroporation

Intramuscular (i.m.) injection of plasmids followed by electropermeabilization is an efficient process to deliver genes into skeletal myofibers that permits proteins to be produced and secreted at therapeutically relevant levels. To further improve skeletal muscle as a bioreactor, we identified a formulation that elevates transgene expression in myofibers after i.m. injection and electroporation. With secreted placental alkaline phosphate (SEAP) as reporter gene, plasmid formulated with poly-L-glutamate produced two- to eight-fold higher levels of SEAP in mouse serum than plasmid in saline. Various concentrations and molecular weights of poly-L-glutamate were similarly effective, but 6 mg/ml of 15-50 kDa poly-L-glutamate consistently yielded the highest expression levels. The poly-L-glutamate formulation was effective in two different muscle groups in mice at various plasmid doses for several transgenes, including an erythropoietin (EPO) gene, for which expression was elevated four- to 12-fold in comparison to animals that received EPO plasmid in saline. Transgene expression was localized to myofibers. Poly-L-glutamate may improve transgene expression in part by increasing plasmid retention in skeletal muscle. Poly-L-glutamate did not enhance gene transfer in the absence of electroporation. Therefore, the polymer is a novel formulation that specifically enhances the transfer and expression of genes delivered with electroporation.

Safety toxicity study of plasmid-based IL-12 therapy in Cynomolgus monkeys

We have investigated the potential toxicity of hlL-12 DNA plasmid formulated with 5% polyvinylpyrrolidone (PVP) administered twice weekly via subcutaneous injections to Cynomolgus monkeys for four weeks, and have evaluated recovery from any effects of the test article over a four-week treatment-free period. Doses of the formulated hIL-12 plasmid were selected based on anti-tumour efficacy studies previously conducted in mice. The duration of the study and the frequency of dosing were designed to support clinical trials. No clinical signs indicative of an adverse effect of administration of formulated hIL-12 plasmid were observed. There were no apparent effects of the formulated hIL-12 plasmid on body weights or on serum chemistry, haematology, coagulation or urinalysis parameters. No treatment-elated ocular abnormalities were evident. In addition, examination of the electrocardiograms from all monkeys at the pre-study, week-4, and week-8 time points did not reveal any treatment-related effects. No treatment-related gross lesions were noted at days 28 or 57. Slight histopathological changes associated with high doses of PVP vehicle were observed at both time points. These results suggested that the administration of formulated hIL-12 plasmid at a dose level up to 18 mg kg(-1) dose twice per week for four weeks to experimentally naïve Cynomolgus monkeys did not result in significant toxicity. These results support further testing of this gene therapy in clinical trials.

LFA-1 is sufficient in mediating neutrophil emigration in Mac-1-deficient mice

To better define the specific function of Mac-1 (CD11b) versus LFA-1 (CD11a) and the other CD11 integrins in vivo, we have disrupted murine CD11b by targeted homologous recombination in embryonic stem cells and generated mice which are homozygous for a mutation in CD11b. A null mutation was confirmed by Southern blotting, RNase protection assay, immunohistochemistry, and flow cytometry. Neutrophils isolated from mice deficient in Mac-1 were defective in adherence to keyhole limpet hemocyanin-coated glass, iC3b-mediated phagocytosis, and homotypic aggregation. When challenged by thioglycollate intraperitoneally, Mac-1-deficient mice had similar levels of neutrophil accumulation in the peritoneal cavity at 1, 2, and 4 h. Treatment with mAb to LFA-1 blocked 78% of neutrophil accumulation in Mac-1-deficient mice and 58% in wild-type mice. Neutrophil emigration into the peritoneal cavity 16 h after the implantation of fibrinogen-coated disks was not reduced in Mac-1-deficient mice whereas neutrophil adhesion to the fibrinogen-coated disks was reduced by > 90%. Neutrophils from Mac-1-deficient mice also showed reduced degranulation. Our results demonstrate that Mac-1 plays a critical role in mediating binding of neutrophils to fibrinogen and neutrophil degranulation, but is not necessary for effective neutrophil emigration, which is more dependent upon LFA-1.