Development of novel relaxin-3 analogues for blood-brain barrier penetration — ASN Events
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  3. Development of novel relaxin-3 analogues for blood-brain barrier penetration

Development of novel relaxin-3 analogues for blood-brain barrier penetration (#168)

Han Siean Lee 1 , Ross AD Bathgate 2 , Joseph A Nicolazzo 3 , K. Johan Rosengren 1
  1. The University of Queensland, Brisbane, QLD, Australia
  2. Florey Institute of Neuroscience and Mental Health and Department of Biochemistry and Molecular Biology, University of Melbourne, Melbourne, Victoria, Australia
  3. Drug Delivery, Disposition and Dynamics, Monash Institute of Pharmaceutical Sciences, Monash University, Melbourne, Victoria, Australia

Introduction. Relaxin-3 is a novel neuropeptide known to be involved in food intake, arousal, learning and memory. Agonist and antagonist analogues of relaxin-3 have been shown to have high affinity to its cognate receptor, the relaxin family peptide-3 (RXFP3) receptor, expressed predominantly in the brain. Biological functions of relaxin-3 have so far been studied only through intracerebroventricular injections as relaxin-3 analogues do not effectively cross the blood-brain barrier (BBB) after systemic delivery.

Aims. Relaxin-3 peptides were conjugated to sequences known to be BBB penetrant to create relaxin-3 analogues with central nervous system (CNS) permeability. These novel analogues were characterised in terms of toxicity, stability, binding affinity and ability to cross the BBB.       

Methods. Analogues were synthesized using Fmoc-chemistry and was tested for stability in serum stability assay. Toxicity of these peptides towards neuronal cells was assessed using an MTT assay. Ability of analogues to target RXFP3 was investigated by in vitro pharmacological assays using the CHO-Ki cells. In vitro blood-brain barrier assays were employed to determine transport mechanism of the novel relaxin-3 analogues across the BBB.

Results. Relaxin-3 analogues targeting the different pathways across the barrier were synthesized and purified to>95% purity. These analogues showed good stability and toxicity profile. Binding data showed that these novel analogues have high affinity to RXFP3 and improved, yet still low performance in in vitro BBB assays.

Discussion. Our investigations show that relaxin-3 analogues can be modified to be stable and incorporate BBB shuttle sequences without causing significant cell toxicity or losing affinity for RXFP3. However, further optimisation of the sequences may be required for efficient pharmacological targeting of RXFP3 using systemical delivery.