Poster Session 1 - B9
1Andrada Naghi, 1Güínever Eustáquio Do Império, 1,2,3Stephen G Matthews
1 Physiology, University of Toronto, ON, Canada; 2 OBGYN & Medicine; 3 Fraser Mustard Institute for Human Development, University of Toronto, Toronto, ON, Canada.
INTRODUCTION: Early life viral exposure and it’s resulting inflammation has been associated with long-term brain structural defects and behavioural consequences in children. In this way Zika virus, a single-stranded RNA virus has recently been associated with microcephaly. Astrocytes (ASTs) play an essential role in this brain viral response through release of the pro-inflammatory cytokines IL-6, IL-1β and TNFα. This inflammation gets rid of the viral threat however can also elicit negative consequences such as blood-brain barrier breakdown. Therefore, we aim to investigate the ability of ASTs to respond to viral mimics, namely ssRNA40 (mimicking single-stranded RNA viruses) and Poly (I:C) (mimicking double-stranded RNA viruses) and to characterize this pro-inflammatory response. METHODS: Primary ASTs were extracted from PND14 guinea pig cortex. Cells were exposed to ssRNA40 at 2.5 ug/mL and Polyinosinic:polycytidylic acid (Poly (I:C)) at 10 ug/mL and 25 ug/mL for 24 hours. Quantitative reverse transcription PCR was completed to measure the expression of toll-like receptors (TLRs) 3, 7, and 8, and the pro-inflammatory cytokines IL-6, IL-1β and TNFα. Cell viability was assessed by trypan blue dye exclusion assay. RESULTS: There were no changes in cell viability after 24 hours ssRNA40 or Poly (I:C) exposure. ASTs increase IL-1β mRNA expression after 2.5 ug/mL ssRNA40 at 24 hours (p<0.05) and trend towards an increase in IL-1β mRNA expression after Poly (I:C). ASTs do not express TLR7. ASTs exhibit no change in TLR3 expression after ssRNA40 or Poly (I:C). ASTs do not express TNFα. ASTs exhibit no change in IL-6 mRNA expression after ssRNA40 or Poly (I:C). CONCLUSIONS: ASTs exhibit a moderate response to viral mimics seen through no change in TLR expression and minimal pro-inflammatory cytokine release. These findings provide insight into the potential mechanism of astrocytic response to viral mimics. Future work needs to be done to elucidate the contribution of this response to blood-brain barrier function.