(618e) Pegylation Of Interleukin-10 To Enhance Delivery To The Central Nervous System And Therapeutic Efficacy For Neuropathic Pain

Improved delivery of therapeutic proteins to the central nervous system is necessary to enhance current therapeutic strategies for a range of neural disorders. Our work focuses on two key therapeutic proteins, brain derived neurotrophic factor (BDNF) and interleukin-10 (IL10). BDNF has been widely explored for its roles in neural repair, regeneration and proliferation in addition to its emerging role as a factor in pain transmission pathways. Recent findings now demonstrate that IL10 is a potent glial regulator and effectively reverses neuropathic pain. The therapeutic effect of IL10 delivery, however, is limited by the short in vivo half-life of the protein in the cerebrospinal fluid (2 hr.). BDNF is also subject to similar delivery limitations in the central nervous system and exhibits a short in vivo half-life (67 min.) in the cerebrospinal fluid. Reductive alkylation, targeting the N-terminal region of the protein, was utilized to covalently attach activated polyethylene glycol (PEG) to IL10 and BDNF. This work assesses the in vitro and in vivo implications of PEGylating these proteins in order to improve their intrathecal delivery to targeted spinal cord glia. The extent of bio-conjugation as a function of reactant stoichiometry was explored with both of these proteins. In vitro results with BDNF demonstrate that high extents of PEGylation reduce biological activities, while reactions with high primary conjugate formation preserve in vitro biological activity. In vivo distribution assessments show that PEGylation improves the half-life of BDNF in the cerebrospinal fluid by over 2.5 fold (167 min. compared to 63 min. for the control). PEGylation also significantly improves the penetration distance of the protein into the spinal cord tissue. Similar trends have been observed with IL10. These results indicate that protein PEGylation is a viable strategy for improved intrathecal protein delivery to spinal cord tissues. In vivo animal model testing is expected to show that PEGylation of IL10 for improved delivery to activated spinal cord glia will significantly prolong its therapeutic effects on the reversal of neuropathic pain.