Blocking M1 Repolarization Of M2 THP-1 Macrophages Through Inhibition Of The Type I Interferon Response By Vesicular Stomatitis Virus

ASU Author/Contributor (non-ASU co-authors, if there are any, appear on document)
Melissa Marie Rowe (Creator)
Appalachian State University (ASU )
Web Site:
Darren Seals

Abstract: Matrix protein mutant strains of VSV, such as rM51R-M virus, are currently being investigated as oncolytic agents due to their ability to target and kill cancer cells while also stimulating innate immunity. We seek to examine the ability of rM51R-M virus to modulate tumor promoting M2 macrophages as a means to inhibit the progression of cancer. In the tumor microenvironment, M2 macrophage activity has a suppressive effect on the immune system, which can lead to tolerance of tumor cells. M1 macrophages, in contrast, stimulate an immune response and reduce tumor cell viability. Our lab has previously shown that rM51R-M virus re-educates M2 macrophages to an M1-like phenotype, but the mechanism by which it does so remains unknown. In THP-1 polarized M2 macrophages, we have observed increased levels of IFNa, total STAT1, and p-STAT1 upon infection with rM5IR-M virus. We hypothesize that the ability of rM51R-M virus to stimulate the type I IFN antiviral pathway in M2 macrophages may coerce them to an M1-like phenotype. To test this hypothesis, we seek to examine the effects of the p-STAT1 inhibitor fludarabine on macrophage polarization by rM51R-M virus. M2 macrophages were pretreated with different concentrations of fludarabine (50, 100, or 150 µM), infected with rM51R-M virus (MOI 1 or 10 pfu/cell) for 24 hours, and subjected to immunoblot analysis for total and phosphorylated STAT1. Results indicated that when cells were infected with rM51R-M virus at an MOI of 1, STAT1 phosphorylation was reduced to between 23% (50 µM fludarabine) and 16 % (100 and 150 µM fludarabine) of control levels. Similar results were obtained when cells were infected at an MOI of 10. These results confirm that fludarabine is capable of inhibiting the accumulation of p-STAT1. Therefore, this reagent can be used to reduce type I IFN signaling in order to determine the extent to which this pathway modulates macrophage identity during rM51R-M infection. Such mechanistic insights will be important in understanding the multipotent effects of VSV as an oncolytic agent.

Additional Information

Honors Project
Rowe, M. (2021). Blocking M1 Repolarization Of M2 THP-1 Macrophages Through Inhibition Of The Type I Interferon Response By Vesicular Stomatitis Virus. Unpublished Honors Thesis. Appalachian State University, Boone, NC.
Language: English
Date: 2021
cancer, VSV, macrophage, immunology, oncology

Email this document to