Abstract
Purpose :
Innate lymphoid cells (ILCs) play important roles in host defense and inflammation and are classified into three distinct groups of ILC1, ILC2 and ILC3 based on their functions and the expression of specific transcription factors. Very little is known regarding the role of ILCs in HSV-1 infectivity in vitro and in vivo. To better understand the relationship between ILCs and HSV-1 infection, we assessed the relative impact of ILC1, ILC2, and ILC3 on the HSV-1 responses in vitro and in vivo.
Methods :
ILC1, ILC2, and ILC3 from Rag-/- mice were harvested and infected with HSV-1 strain McKrae. Plaque assay was performed to measure HSV-1 infectivity in each cell type. Luminex assay was performed to measure the changes in the profile of cytokine/chemokine produced in the infected cells. Illumina RNA-Seq was used to obtain the transcriptome of ILC1, ILC2 and ILC3 cells before and 24 h after infection and the differentially expressed genes (DEGs) were analyzed. In addition, ILC1-, ILC2-, and ILC3-deficient mice were infected ocularly with the wild type HSV-1 strain McKrae. Virus replication in the eye and the level of latency-reactivation in the trigeminal ganglia (TG) of the infected mice were determined on day 28 post infection.
Results :
Plaque assay results showed that HSV-1 infectivity was dramatically decreased in all three infected cell types compared with RS cells. Luminex assay results showed that HSV-1 infection significantly altered the profile of inflammatory cytokine expression in the ILC2- versus ILC1- or ILC3-infected cells. More genes were upregulated in ILC3 infected cells compared with ILC1 or ILC2 infected cells, while the number of down-regulated genes were similar between the three cell types. More viral genes were detected in ILC3 infected cells and this was followed by ILC2 and then ILC1. Except for lower survival in ILC3-deficient mice, virus replication in the eye, eye disease, latency, reactivation and markers of exhaustion were similar among ILC1, ILC2, and ILC3 deficient mice.
Conclusions :
Our results suggested that: (1) ILCs are refractory to HSV-1 infection; (2) ILC2 are producing more inflammatory cytokines-chemokines than ILC1 or ILC3; (3) more cellular and viral genes are upregulated in ILC3 than in ILC1 or ILC2; and (4) ILCs play no role in protection against virus replication, eye disease, latency or reactivation.
This abstract was presented at the 2019 ARVO Annual Meeting, held in Vancouver, Canada, April 28 - May 2, 2019.