Poster W14 - 5-HT4 GPCR targeting novel nanoformulation for anti-depressant effects

Introduction: Globally around 1 trillion USD loss is estimated due to mental health disorders and in US, it is the second leading cause of death in young children. Anxiety and depression disorders contribute to approximately 50% of these total mental health disorders. Microglia, the immune cells of the brain have consistently been present in a pro-inflammatory state in brain samples of mental health disorder patients and found to be primed, exaggerating the recurrence of trauma resembling early childhood trauma. The presence of the Blood Brain Barrier (BBB) and lack of targeted therapy is a major hurdle in treating these disorders. Nanomedical platforms are often resorted to implement targeted-sustained delivery and enhanced bioavailability. In the past, there has been attempts to encapsulate existing class of drugs like lithium carbonate, Asenapine maleate, Aripiprazole, Haloperidol, etc via nasal delivery or ileum sac, however, were poorly designed to actively cross the BBB.We hypothesize that a nano formulation designed to actively cross the BBB by 5HT4 receptor binding (mediators of anti-depressant effect) and polarize microglia from its pro-inflammatory state to an anti-inflammatory state would be an effective approach to tackle mental health disorders.

The aims for this study is as follows.

1. To develop a nanofromulation with a surface display of tryptamine to target the 5HT4 receptors, evaluation of its immunogenicity, microglia polarization and anti-depressant effects.
2. To evaluate novel downstream targets of tryptamine in silico and in vitro

Materials and

Methods: Liposomes synthesized using solvent evaporation subjected to sequential addition of chloroauric acid, ascorbic acid, and tryptamine were characterized via Fourier transform infrared spectroscopy (FTIR), dynamic light scattering (DLS), elemental map analysis. Targeting 5HT4 was assessed in a receptor positive and negative cell lines. B arrestin levels and molecular markers of depression was analyzed using corticotropin releasing hormone (CRH), glucocorticoid receptor (GR) and phospho-TrKB in BV2.

Results, Conclusions, and Discussions: Our results indicate (i) stable ( < 250 nm, 21 days, 4 °C) and biocompatible surface display of tryptamine anchored via gold nanoparticles in elemental map analysis of SEM and cytotoxicity analysis in populations of both neuron and microglia cells (>80 % cell viability) (ii) polarization of pro-inflammatory microglia cells to anti-inflammatory state with the treatment of 100 µM to 1 mM formulation with reduced pro-inflammatory genes Cox2 and NFKb expression levels (iii) novel targets of tryptamine with roles implicated in mental health disorders using ligand similarity search based on 1NN and Laplacian modified naive Bayesian model e.g.: PDE10a, a known therapeutic target for treating schizophrenia, stress, and anxiety. PDE10a also displayed a decreased expression with respect to the nanoformulation treatment. (iv) ability to selectively cross organ barriers in 5 days post fertilization (sealed hind brain) Danio rerio embryos. We observed an upregulation of β arrestin indicating activation of 5HT4 receptors via nanocarrier binding and decrease in expression levels of CRH and TrKB. Selective targeting studies using 5Ht4 binding indicated a significant receptor mediated uptake as compared to passive uptake in receptor negative cells.

Acknowledgements (Optional): Blazer foundation, MBT program UIC Rockford