Development of Antiviral Innate Immunity During In Vitro Differentiation of Mouse Embryonic Stem Cells

Abstract

The innate immunity of embryonic stem cells (ESCs) has recently emerged as an important issue in ESC biology and in ESC-based regenerative medicine. We have recently reported that mouse ESCs (mESCs) do not have a functional type I interferon (IFN)-based antiviral innate immunity. They are deficient in expressing IFN in response to viral infection and have limited ability to respond to IFN. Using fibroblasts (FBs) as a cell model, the current study investigated the development of antiviral mechanisms during in vitro differentiation of mESCs. We demonstrate that mESC-differentiated FBs (mESC-FBs) share extensive similarities with naturally differentiated FBs in morphology, marker expression, and growth pattern, but their development of antiviral mechanisms lags behind. Nonetheless, the antiviral mechanisms are inducible during mESC differentiation as demonstrated by the transition of nuclear factor kappa B (NFkB), a key transcription factor for IFN expression, from its inactive state in mESCs to its active state in mESC-FBs and by increased responses of mESC-FBs to viral stimuli and IFN during their continued in vitro propagation. Together with our previously published study, the current data provide important insights into molecular basis for the deficiency of IFN expression in mESCs and the development of antiviral innate immunity during mESC differentiation.

The Molecular Basis for the Lack of Inflammatory Responses in Mouse Embryonic Stem Cells and Their Differentiated Cells

“…D3 and DBA mESCs and mESC-differentiated cells (i.e. D3-FBs and DBA-FBs) displayed similar properties as previously characterized (18,26). Most experiments were performed with D3 cells and D3-FBs since D3 cells are a mESC line commonly used in the literature.…”

“…They share extensive similarities with 10T1/2 cells (fibroblasts isolated from a 14-day old embryo) (33,34) in cell marker expression, growth pattern, and morphology, as we have previously characterized (18,26). TNFα-induced NFκB nuclear translocation is clearly demonstrated in D3-FBs, although the fluorescence intensity of NFκB in their nuclei is substantially lower than in 10T1/2 cells (Fig.…”

“…The differentiation, purification, and characterization of mESC-FBs were described in our published studies (18,26). mESC-FBs between passages 10–30 were used for the experiments.…”

“…Previous studies indicated that the lack of IFN expression in ESCs is partly attributable to the absence or low levels of expression of viral RNA receptors (17,19). Our recent study further demonstrated that NFκB is not activated in virus-infected mESCs, which explain the deficiency of IFN expression at the transcriptional level (26). …”

Cutaneous Deficiency of Filaggrin and STAT3 Exacerbates Vaccinia Disease In Vivo

“…In skin with barrier defects, chronic overexpression of activin A may expand the population of pluripotential cells. Although responses of semi-differentiated cells to vaccinia infection have not been previously studied, less differentiated cells may have reduced innate responses and might potentially contribute to a viral replicative niche in the skin [22]. Mucosally-skewed mast cells, recruited and activated by epidermally-derived activin A, are a potential source of anti-inflammatory and pro-fibrotic mediators which may also critically support a viral niche.…”