Search

Simple Summary: Cancer immunotherapy has evolved rapidly in the last decade. A newly emerging immunotherapeutic approach utilizes oncolytic viruses to enhance the ability of the body's own immune system to recognize and clear tumor cells. We have recently developed a novel chimeric oncolytic virus and demonstrated its anti-tumoral effects in various preclinical mouse models. To gain mechanistic insights into the immune response to this form of therapy at the cellular level and to identify targets to potentially further improve the therapy, we analyzed the immune cell signature in the tumors, blood, and lymphoid tissue in a syngeneic melanoma mouse model by flow cytometry. Both local and systemic immune responses were observed. Furthermore, selective depletion of cytotoxic T cells indicated that these cells are the main players in mediating the therapeutic response to this novel virotherapy. Background/Objectives: Oncolytic virotherapy is a promising approach in cancer immunotherapy. We have previously described a recombinant hybrid oncolytic virus (OV), VSV-NDV, which has a favorable safety profile and therapeutic immunogenicity, leading to direct oncolysis, abscopal effects, and prolonged survival in syngeneic in vivo tumor models. While OVs are known to mediate systemic anti-tumor immune responses, the detailed characterization of local and systemic immune responses to fusogenic oncolytic virotherapy remains unexplored. Methods and Results: We analyzed immune cell compartments in the spleen, blood, tumor-draining lymph nodes (TDLNs), and tumors over the course of VSV-NDV therapy in a bilateral syngeneic melanoma mouse model. Our results revealed significant local infiltration and activation of T lymphocytes in tumors and globally in the blood and spleen. Notably, in vivo CD8+ T cell depletion led to complete abrogation of the tumor response, highlighting the crucial role of T cells in promoting the therapeutic effects of oncolytic VSV-NDV. In vitro co-culture experiments enabled the interrogation of human immune cell responses to VSV-NDV-mediated oncolysis. Human peripheral blood mononuclear cells (PBMCs) were efficiently stimulated by exposure to VSV-NDV-infected cancer cells, which recapitulates the in vivo murine findings. Conclusions: Taken together, these data characterize a broad anti-tumor immune cell response to oncolytic VSV-NDV therapy and suggest that CD8+ T cells play a decisive role in therapeutic outcome, which supports the further development of this chimeric vector as a multimechanistic immunotherapy for solid cancers. [ABSTRACT FROM AUTHOR]

We present a proof‐of‐concept study for production of a recombinant vesicular stomatitis virus (rVSV)‐based fusogenic oncolytic virus (OV), rVSV‐Newcastle disease virus (NDV), at high cell densities (HCD). Based on comprehensive experiments in 1 L stirred tank reactors (STRs) in batch mode, first optimization studies at HCD were carried out in semi‐perfusion in small‐scale cultivations using shake flasks. Further, a perfusion process was established using an acoustic settler for cell retention. Growth, production yields, and process‐related impurities were evaluated for three candidate cell lines (AGE1.CR, BHK‐21, HEK293SF)infected at densities ranging from 15 to 30 × 106 cells/mL. The acoustic settler allowed continuous harvesting of rVSV‐NDV with high cell retention efficiencies (above 97%) and infectious virus titers (up to 2.4 × 109 TCID50/mL), more than 4–100 times higher than for optimized batch processes. No decrease in cell‐specific virus yield (CSVY) was observed at HCD, regardless of the cell substrate. Taking into account the accumulated number of virions both from the harvest and bioreactor, a 15–30 fold increased volumetric virus productivity for AGE1.CR and HEK293SF was obtained compared to batch processes performed at the same scale. In contrast to all previous findings, formation of syncytia was observed at HCD for the suspension cells BHK 21 and HEK293SF. Oncolytic potency was not affected compared to production in batch mode. Overall, our study describes promising options for the establishment of perfusion processes for efficient large‐scale manufacturing of fusogenic rVSV‐NDV at HCD for all three candidate cell lines. [ABSTRACT FROM AUTHOR]

High-fructose consumption is associated with insulin resistance and diabetic dyslipidemia, but the underlying mechanism is unclear. We show in hamsters that high-fructose feeding stimulated forkhead box O1 (FoxO1) production and promoted its nuclear redistribution in liver, correlating with augmented apolipoprotein C-III (apoC-III) production and impaired triglyceride metabolism. High-fructose feeding upregulated peroxisome proliferator-activated receptor-[gamma] coactivator-l[beta] and sterol regulatory element binding protein-1c expression, accounting for increased fat infiltration in liver. High-fructose-fed hamsters developed hypertriglyceridemia, accompanied by hyperinsulinemia and glucose intolerance. These metabolic aberrations were reversible by fenofibrate, a commonly used anti-hypertriglyceridemia agent that is known to bind and activate peroxisome proliferator-activated receptor-[alpha] (PPAR[alpha]). PPAR[alpha] physically interacted with, but functionally antagonized, FoxO1 in hepatic apoC-III expression. These data underscore the importance of FoxO1 deregulation in the pathogenesis of hypertriglyceridemia in high-fructose-fed hamsters. Counterregulation of hepatic FoxO1 activity by PPAR[alpha] constitutes an important mechanism by which fibrates act to curb apoC-III overproduction and ameliorate hypertriglyceridemia. hypertriglyceridemia; forkhead box O1; peroxisome proliferator-activated receptor-[alpha]; apolipoprotein C-III; very-low-density lipoprotein-triglyceride; microsomal triglyceride transfer protein

Excessive hepatic glucose production is a contributing factor to fasting hyperglycemia in diabetes. Insulin suppresses hepatic glucose production by inhibiting the expression of two gluconeogenic enzymes, phosphoenolpyruvate carboxykinase (PEPCK) and glucose-6-phosphatase (G-6-Pase). The forkhead transcription factor Foxo1 has been implicated as a mediator of insulin action in regulating hepatic gluconeogenesis, and a Foxo1 mutant (Foxo1-[DELTA]256), devoid of its carboxyl domain, has been shown to interfere with Foxo1 function and inhibit gluconeogenic gene expression in cultured cells. To study the effect of Foxo1-[DELTA]256 on glucose metabolism in animals, the Foxo1-[DELTA]256 cDNA was delivered to the livers of mice by adenovirus-mediated gene transfer. Hepatic Foxo1-[DELTA]256 production resulted in inhibition of gluconeogenic activity, as evidenced by reduced PEPCK and G-6-Pase expression in the liver. Mice treated with the Foxo1-[DELTA]256 vector exhibited significantly reduced blood glucose levels. In contrast, blood glucose levels in control vector-treated animals remained unchanged, which coincided with the lack of alterations in the expression levels of PEPCK and G-6-Pase. When tested in diabetic db/db mice, hepatic production of Foxo1-[DELTA]256 was shown to reduce fasting hyperglycemia. Furthermore, we showed that hepatic Foxo1 expression was deregulated as a result of insulin resistance in diabetic mice and that Foxo1-[DELTA]256 interfered with Foxo1 function via competitive binding to target promoters. These results demonstrated that functional inhibition of Foxo1, caused by hepatic expression of its mutant, is associated with reduced hepatic gluconeogenic activity and improved fasting glycemia in diabetic mice. forkhead transcription factor; gluconeogenesis; type 2 diabetes; mice