Anti-inflammatory Activity of MTL-CEBPA, a Small Activating RNA Drug, in LPS-Stimulated Monocytes and Humanized Mice

Excessive or inappropriate inflammatory responses can cause serious and even fatal diseases. The CCAAT/enhancer-binding protein alpha (CEBPA) gene encodes C/EBPα, a transcription factor that plays a fundamental role in controlling maturation of the myeloid lineage and is also expressed during the late phase of inflammatory responses when signs of inflammation are decreasing. MTL-CEBPA, a small activating RNA targeting for upregulation of C/EBPα, is currently being evaluated in a phase 1b trial for treatment of hepatocellular carcinoma. After dosing, subjects had reduced levels of pro-inflammatory cytokines, and we therefore hypothesized that MTL-CEBPA has anti-inflammatory potential. The current study was conducted to determine the effects of C/EBPα saRNA - CEBPA-51 - on inflammation in vitro and in vivo after endotoxin challenge. CEBPA-51 led to increased expression of the C/EBPα gene and inhibition of pro-inflammatory cytokines in THP-1 monocytes previously stimulated by E. coli-derived lipopolysaccharide (LPS). Treatment with MTL-CEBPA in an LPS-challenged humanized mouse model upregulated C/EBPα mRNA, increased neutrophils, and attenuated production of several key pro-inflammatory cytokines, including TNF-α, IL-6, IL-1β, and IFN-γ. In addition, a Luminex analysis of mouse serum revealed that MTL-CEBPA reduced pro-inflammatory cytokines and increased the anti-inflammatory cytokine IL-10. Collectively, the data support further investigation of MTL-CEBPA in acute and chronic inflammatory diseases where this mechanism has pathogenic importance.