Publications

Blinding diseases due to the degeneration of photoreceptors (PhRs), such as geographic atrophy (GA) secondary to dry age-related macular degeneration and retinitis pigmentosa (RP), leave the rest of the retinal circuitry largely intact, albeit unable to respond to light. Gene therapy has been able to revert PhR degeneration, but it can be applied only to a rare mutation affecting a small subset of RP patients. Alternatively, implanted electronic retinal prostheses aim at a larger population by electrically stimulating surviving neurons. However, the treatment is invasive and costly and provides limited resolution. Photopharmacology can develop photoswitchable small molecules to restore vision impairment by conferring light sensitivity to ion channels that are widely expressed in the remaining inner retinal neurons, and a first-in-human clinical trial is ongoing. Here, we have developed novel photoswitchable small-molecule ligands of metabotropic glutamate 6 (mGlu6) receptors, which are located exclusively at the dendrites of ON bipolar cells (postsynaptic to PhRs) and can leverage a privileged position to mimic physiological signals in the remnant retinal circuit. These photoswitchable ligands (prosthe6) thus act as "molecular prostheses" that can restore the light input to the retina via upstream-targeted control of the circuit after PhR degeneration. Prosthe6 compounds are allosteric, drug-like, water-soluble, and display outstanding in vitro properties including full efficacy, nanomolar potency, fast deactivation in ambient white light, and fast reactivation in the dark. In vivo experiments show that they readily recover the saccadic eye movements of blinded zebrafish larvae and restore the innate light-avoidance behavior in the mouse models of blindness (GA and RP). These effects are mediated by mGlu6 receptors in vivo. In addition, at least two compounds (prosthe6-12 and -15) can restore sight by topical administration and display promising safety properties to become potential drug candidates for sight restoration in patients with degenerative blinding diseases.

JTD Keywords: Allosteric modulators, Bipolar cells, Blind mice, Ectopic expression, Gene-therapy, Human rod, Protein-coupled receptors, Restores visual responses, Retinal degeneration, Zebrafish models

Gamma aminobutyric acid type A receptors (GABA(A)Rs) play a key role in the mammalian central nervous system (CNS) as drivers of neuroinhibitory circuits, which are commonly targeted for therapeutic purposes with potentiator drugs. However, due to their widespread expression and strong inhibitory action, systemic pharmaceutical potentiation of GABA(A)Rs inevitably causes adverse effects regardless of the drug selectivity. Therefore, therapeutic guidelines must often limit or exclude clinically available GABA(A)R potentiators, despite their high efficacy, good biodistribution, and favorable molecular properties. One solution to this problem is to use drugs with light-dependent activity (photopharmacology) in combination with on-demand, localized illumination. However, a suitable light-activated potentiator of GABA(A)Rs has been elusive so far for use in wildtype mammals. We have met this need by developing azocarnil, a diffusible GABAergic agonist-potentiator based on the anxiolytic drug abecarnil that is inactive in the dark and activated by visible violet light. Azocarnil can be rapidly deactivated with green light and by thermal relaxation in the dark. We demonstrate that it selectively inhibits neuronal currents in hippocampal neurons in vitro and in the dorsal horns of the spinal cord of mice, decreasing the mechanical sensitivity as a function of illumination without displaying systemic adverse effects. Azocarnil expands the in vivo photopharmacological toolkit with a novel chemical scaffold and achieves a milestone toward future phototherapeutic applications to safely treat muscle spasms, pain, anxiety, sleep disorders, and epilepsy.

JTD Keywords: A receptor, Abecarnil, Affinity, Beta-carboline, Efficacy, Modulator, Optical control, Pain, Site, Subtype

Over the last decades, photopharmacology has gone far beyond its proof-of-concept stage to become a bona fide approach to study neural systems in vivo. Indeed, photopharmacological control has expanded over a wide range of endogenous targets, such as receptors, ion channels, transporters, kinases, lipids, and DNA transcription processes. In this review, we provide an overview of the recent progresses in the in vivo photopharmacological control of neuronal circuits and behavior. In particular, the use of small aquatic animals for the in vivo screening of photopharmacological compounds, the recent advances in optical modulation of complex behaviors in mice, and the development of adjacent techniques for light and drug delivery in vivo are described.

JTD Keywords: brain circuits, circadian rhythm, in vivo photomodulation, in vivo technology, neuronal receptors, Architecture, Azobenzene photoswitches, Brain circuits, Channels, Circadian rhythm, In vivo photomodulation, In vivo technology, Light, Modulator, Neuronal receptors, Optical control, Optogenetics, Pharmacology, Photopharmacology, Receptors, Systems

Sex differences in immune-mediated diseases are linked to the activity of estrogens on innate immunity cells, including macrophages. Tamoxifen (TAM) is a selective estrogen receptor modulator (SERM) used in estrogen receptor-alpha (ER alpha)-dependent breast cancers and off-target indications such as infections, although the immune activity of TAM and its active metabolite, 4-OH tamoxifen (4HT), is poorly characterized. Here, we aimed at investigating the endocrine and immune activity of these SERMs in macrophages. Using primary cultures of female mouse macrophages, we analyzed the expression of immune mediators and activation of effector functions in competition experiments with SERMs and 17 beta-estradiol (E2) or the bacterial endotoxin LPS. We observed that 4HT and TAM induce estrogen antagonist effects when used at nanomolar concentrations, while pharmacological concentrations that are reached by TAM in clinical settings regulate the expression of VEGF alpha and other immune activation genes by ER alpha- and G protein-coupled receptor 1 (GPER1)-independent mechanisms that involve NRF2 through PI3K/Akt-dependent mechanisms. Importantly, we observed that SERMs potentiate cell phagocytosis and modify the effects of LPS on the expression of inflammatory cytokines, such as TNF alpha and IL1 beta, with an overall increase in cell inflammatory phenotype, further sustained by potentiation of IL1 beta secretion through caspase-1 activation.

JTD Keywords: drug repurposing, inflammation, macrophage, nrf2, Afimoxifene, Animals, Apoptosis, Breast-cancer, Cells, cultured, Drug repurposing, Esr1 protein, mouse, Estrogen receptor alpha, Expression, Female, Gper1 protein, mouse, Immunomodulating agents, Inflammation, Inflammation mediators, Lipopolysaccharide, escherichia coli o111 b4, Lipopolysaccharides, Macrophage, Macrophages, peritoneal, Mice, Mice, inbred c57bl, Mice, knockout, Nf-e2-related factor 2, Nfe2l2 protein, mouse, Nrf2, Phagocytosis, Phenotype, Receptors, estrogen, Receptors, g-protein-coupled, Resistance, Selective estrogen receptor modulators, Sex-differences, Signal transduction, Tamoxifen, Tumor-associated macrophages