Screening Immunotherapy Targets to Counter Radiation-Induced Neuroinflammation

Galactic cosmic rays (GCR) in space induce increase in cerebral amyloid-β levels and elevated levels of microgliosis and astrocytosis, causing accelerated neurodegeneration from this increased neuroinflammation. Even exposure to low-levels of high-Z high-energy (HZE) radiation (50 cGy) has been shown to induce biochemical and immunohistochemical changes in short-term leading to degradation in cognition, motor skills, and development of space-induced neuropathy. There is lack of effective neuroinflammation countermeasures, and current experimental therapies require invasive intracerebral and intrathecal delivery due to difficulty associated with therapeutic crossover between blood-brain barrier. Here, we present a new countermeasure development approach for neurotherapeutics using high-throughput drug-discovery, target validation, and lead molecule identification with nucleic acid-based molecules. These Nanoligomer™ molecules are rationally designed using a bioinformatics and AI-based ranking method and synthesized as a single-modality combining 6-different design elements to up- or down-regulate gene expression of target gene at will, resulting in elevated or diminished protein expression of intended target. This platform approach was used to perturb and identify most effective upstream regulators and canonical pathways for therapeutic intervention to reverse radiation-induced neuroinflammation. The lead Nanoligomer™ and corresponding target granulocyte-macrophage colony-stimulating factor (GM-CSF) were identified using in vitro cell-based screening in human astrocytes and donor derived peripheral blood mononuclear cells (PBMCs) and further validated in vivo using a mouse model of radiation-induced neuroinflammation. GM-CSF transcriptional downregulator Nanoligomer 30D.443_CSF2 downregulated proinflammatory cytokine GM-CSF (or CSF2) using simple intraperitoneal injection of low-dose (3mg/kg) and completely reversed expression of CSF2 in cortex tissue, as well as other neuroinflammation markers. These results point to the broader applicability of this approach towards space countermeasure development, and potential for further investigation of lead neurotherapeutic molecule as a reversible gene therapy. ### Competing Interest Statement S.S., A.C., and P.N. are employed by the for-profit company Sachi Bioworks where this technology was developed. A.C. and P.N. are the founders of Sachi Bioworks, and P.N. has filed a patent on this technology.