Treatment of Acute Liver Injury through Selective Tropism of High Mobility Group Box 1 Gene-Silenced Large Peritoneal Macrophages

Tissue-resident macrophages (TRMs) are attractive cells to therapeutically deliver oligonucleotide and other gene-expression modifying modalities to treat a wide array of diseases ranging from inflammatory to autoimmune, and even cancer. Here, we focus on TRMs located inside the peritoneal cavity lining the abdomen that selectively express a transcription factor GATA6 called large peritoneal macrophages (GLPMs) and successfully demonstrate functional GLPM-selective delivery of a Cy5-fluorophore-labeled siRNA encapsulated in C12–200 cationic-lipidoid-based nanoparticles (siRNA-Cy5 (C12–200)). Despite being TRMs, GLPMs possess a specific migratory ability to peritoneally located liver tissue upon injury incited by acetaminophen (APAP) overdose in mice. A rapid, liver injury-driven tropism of GLPMs carrying siRNA-Cy5 (C12–200) was seen via systemic circulation, which was elegantly demonstrated by using a noninvasive live-cell tracking technique called diffuse in vivo flow cytometry (DiFC). Finally, RNAi-mediated silencing of a well-known pro-inflammatory damage-associated molecular pattern (DAMP) High Mobility Group Box-1 (HMGB1) gene in GLPMs led to the mitigation of liver injury and inflammation via prevention of GLPM modulation to a pro-inflammatory state, which further translated into significant protection from APAP-driven liver injury and a reduction in liver circulating pro-inflammatory cytokines owing to a muted inflammatory response to acute liver injury. Moreover, silencing HMGB1 by a GalNAc-conjugated hepatocyte-targeting siRNA did not reciprocate the findings, further solidifying our results. Together, our data suggested that GLPMs act as delivery carriers by rapidly bringing lipid nanoparticle-encapsulated RNAi modalities to the injured liver and have emerged as a therapeutically viable strategy to address inflammatory diseases, especially those that are more acute in nature.