Characterization of three CpG ODN classes in plasmacytoid dendritic cells (pDCs)

Purpose: Next-generation sequencing (NGS) has revolutionized systems-based analysis of cellular pathways. The goals of this study are to compare distinct immunostimulatory activities of three classes of CpG ODNs in pDCs using RNA-seq. mRNA profiles of murine pDCs induced by three classes of CpG ODNs were generated by RNA-Seq studies. Methods: mRNA profiles of murine pDCs induced by three classes of CpG ODNs were generated by deep sequencing, in triplicate, using Illumina Hiseq Xten. The sequence reads that passed quality filters were analyzed at the transcript isoform level with two methods: HISAT based on Burrows-Wheeler transform and Ferragina-Manzini and Bowtie2 followed by RSEM. Results: Using an optimized data analysis workflow, we mapped > 60 million total clean reads per sample to the mouse genome (build mm10), with a clean reads Q20 score > 98.58% and a mapping rate to the reference genome of each sample varying from 92.3% to 96.56%. The Pearson correlation coefficient between each sample revealed that CpG-A and CpG-C have the highest correlation. A total of 21,573 genes were detected as being expressed. More than 5,000 genes were downregulated and 2,000 genes were upregulated in CpG ODNs stimulated groups relative to control group, with a fold change ≥ 2 and Q value <0.001. Gene Ontology (GO) analysis and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis of differentially expressed genes uncovered several genes that may contribute to characterize the features of three classes of CpG ODNs in pDCs. Conclusions: Our study represents the first detailed analysis of pDC transcriptomes stimulated with three classes of CpG ODNs, with biological replicates, generated by RNA-seq technology. mRNA profiles of murine pDCs stimulated with or without CpG-A, CpG-B or CpG-C were generated by RNA-Seq studies, in triplicate, using Illumina Hiseq Xten.