Synthetic immunomodulation with a CRISPR super-repressor in vivo

In this study we introduce an enhanced CRISPR-based transcriptional repressor to reprogram immune homeostasis in vivo. By a dual fusion of heterochromatin protein 1 (HP1a) and Krüppel associated box (KRAB) to MS2 coat protein and recruitment to a nuclease competent CRISPR complex, we demonstrate transcriptional repression of the Myeloid differentiation primary response 88 (Myd88) gene in vivo. We report that this strategy can effectively modulate host immune response against adeno-associated virus-mediated gene therapy and influence the course of septicemia. For the in vitro RNA seq data, Neuro 2A cells received CRISPR components with full length or truncated gRNAs targeting endogenous Myd88 locus. The goal of the experiment was comparing specificity of the gRNAs. Repression levels were assessed 3 days post transfection using RNA-seq and qRT-PCR. For the in vivo RNA seq data, Cas9 nuclease transgenic mice received AAV1-Myd88-Ms2-HP1aKRAB or AAV1-Myd88-MS2-KRAB through retro-orbital injection. 3 weeks post injection, Myd88 expression levels were assessed in bone marrow by qRT-PCR analysis.