👤 Jean-Philippe Fortin

The induction of nausea and emesis represents a significant barriers to optimizing weight loss medications for the treatment of obesity. Identifying mechanisms that improve tolerability and/or enhance efficacy without induction of emetic neurocircuitry could provide substantial therapeutic benefits. Candidate peptide YY (PYY)-based approaches for obesity treatment are no exception, as PYY-based therapeutics are uniformly associated with nausea and emesis. Recently, interest in glucose-dependent insulinotropic polypeptide receptor (GIPR)-based therapeutics has resurfaced, with some paradoxical findings from several preclinical studies showing that both GIPR agonism and antagonism, when combined with glucagon-like peptide-1 receptor (GLP-1R) agonists, result in greater body weight loss and superior glycemic control compared to GLP-1R agonism alone. Here, we investigated the effects of pharmacological modulation of the GIPR system on the actions of PYY. We found that systemic GIPR agonism attenuated PYY-induced malaise while preserving its anorectic and body weight-lowering effects in rats. Interestingly, GIPR antagonism enhanced PYY-induced hypophagia and body weight loss without compromising its malaise tolerability profile. Furthermore, inhibition of GIPR signaling significantly reduced PYY-induced c-Fos expression in the area postrema (AP) of the hindbrain. Since both NPY2R and GIPR are expressed in the same AP neurons, this suggests a potential neuronal pathway by which GIPR modulates the effects of PYY. Overall, our findings underscore the multifaceted actions of the GIPR system and highlight the therapeutic potential of both GIPR agonism and antagonism in enhancing and improving the effects of PYY-based obesity treatments. Show less

Pain is one of the leading causes of disability worldwide. Despite the various pharmacological treatments available, patients with chronic pain often remain with significant disabilities and unsatisfactory pain control. Cannabis and cannabinoids are sometimes used in the treatment of chronic pain as they have been shown to be useful in a subset of patients. Some of the adverse effects associated with cannabis use, such as cannabis use disorder (CUD) and cannabis-induced psychosis, have been associated with several genetic variants. Despite this, the paucity of the data or the contradictory results for reported variants limits our ability to use them as genetic markers to personalize cannabis treatment tailored to patients’ genetic background. The aim of this genetic association study was to investigate the link between previously reported genes and cannabinoid response in terms of pain response, CUD and risk of psychotic adverse events in patients with chronic pain. Phone or in person interviews were conducted to document participants’ characteristics, cannabis use and effects, concurrent pharmacotherapy and comorbid conditions. Screening for CUD was performed using the Cannabis Use Disorders Identification Test – Revised. Blood or saliva samples were collected for the genotyping of 18 variants in 11 genes ( One hundred participants were recruited, with blood or saliva samples collected from 77 of them. Two single-nucleotide polymorphisms (SNP) in cannabinoid receptor 1 ( These results suggest alternative allele carriers of rs1049353 and rs2023239 could be at an increased risk of psychotic adverse events related to cannabis use, although additional investigation is required to replicate and confirm these findings. The online version contains supplementary material available at 10.1186/s42238-026-00408-w. Show less

The melanocortin-4 receptor (MC4R) is a centrally expressed, class A GPCR that plays a key role in the regulation of appetite and food intake. Deficiencies in MC4R signaling result in hyperphagia and increased body mass in humans. Antagonism of MC4R signaling has the potential to mitigate decreased appetite and body weight loss in the setting of anorexia or cachexia due to underlying disease. Herein, we report on the identification of a series of orally bioavailable, small-molecule MC4R antagonists using a focused hit identification effort and the optimization of these antagonists to provide clinical candidate Show less

Glucagon-like peptide 1 receptor (GLP-1R) agonists decrease body weight and improve glycemic control in obesity and diabetes. Patient compliance and maximal efficacy of GLP-1 therapeutics are limited by adverse side effects, including nausea and emesis. In three different species (i.e., mice, rats, and musk shrews), we show that glucose-dependent insulinotropic polypeptide receptor (GIPR) signaling blocks emesis and attenuates illness behaviors elicited by GLP-1R activation, while maintaining reduced food intake, body weight loss, and improved glucose tolerance. The area postrema and nucleus tractus solitarius (AP/NTS) of the hindbrain are required for food intake and body weight suppression by GLP-1R ligands and processing of emetic stimuli. Using single-nuclei RNA sequencing, we identified the cellular phenotypes of AP/NTS cells expressing GIPR and GLP-1R on distinct populations of inhibitory and excitatory neurons, with the greatest expression of GIPR in γ-aminobutyric acid-ergic neurons. This work suggests that combinatorial pharmaceutical targeting of GLP-1R and GIPR will increase efficacy in treating obesity and diabetes by reducing nausea and vomiting. Show less

The mesencephalic trigeminal nucleus (Mes5) processes oral sensory-motor information, but its role in the control of energy balance remains unexplored. Here, using fluorescent in situ hybridization, we show that the Mes5 expresses the melanocortin-4 receptor. Consistent with MC4R activation in other areas of the brain, we found that Mes5 microinjection of the MC4R agonist melanotan-II (MTII) suppresses food intake and body weight in the mouse. Furthermore, NTS POMC-projecting neurons to the Mes5 can be chemogenetically activated to drive a suppression in food intake. Taken together, these findings highlight the Mes5 as a novel target of melanocortinergic control of food intake and body weight regulation, although elucidating the endogenous role of this circuit requires future study. While we observed the sufficiency of Mes5 MC4Rs for food intake and body weight suppression, these receptors do not appear to be necessary for food intake or body weight control. Collectively, the data presented here support the functional relevance of the NTS POMC to Mes5 projection pathway as a novel circuit that can be targeted to modulate food intake and body weight. Show less

Adolescent idiopathic scoliosis (AIS) is a complex common disorder of multifactorial etiology defined by a deviation of the spine in three dimensions that affects approximately 2% to 4% of adolescents. Risk factors include other affected family members, suggesting a genetic component to the disease. The Show less

Retinopathy of prematurity (ROP) is the primary cause of visual impairment and vision loss in premature infants, which results from the formation of aberrant retinal neovascularization (NV). An emerging body of evidence has shown that Müller cells are the predominant source of vascular endothelial growth factor (VEGF), which also serves as a chemoattractant for monocyte/macrophage lineage. The recruitment of macrophages is increased during retinal NV, and they exert a pro-angiogenic role in ROP. We have shown that lymphocytic microparticles (microvesicles; LMPs) derived from apoptotic human T lymphocytes possess strong angiogenesis-inhibiting properties. Here, we investigated the effect of LMPs on the chemotactic capacity of Müller cells in vitro using rat Müller cell rMC-1 and mouse macrophage RAW 264.7. In addition, the impact of LMPs was determined in vivo using a mouse model of oxygen-induced ischemic retinopathy (OIR). The results revealed that LMPs were internalized by rMC-1 and reduced their cell proliferation dose-dependently without inducing cell apoptosis. LMPs inhibited the chemotactic capacity of rMC-1 on RAW 264.7 via reducing the expression of VEGF. Moreover, LMPs attenuated pathological retinal NV and the infiltration of macrophages in vivo. LMPs downregulated ERK1/2 and HIF-1α both in vitro and in vivo. These findings expand our understanding of the effects of LMPs, providing evidence of LMPs as a promising therapeutic approach for the treatment of retinal NV diseases. Show less

The glucose-dependent insulinotropic polypeptide (GIP) and the glucagon-like peptide-1 (GLP-1) receptors are considered complementary therapeutic targets for type 2 diabetes. Using recombinant membrane-tethered ligand (MTL) technology, the present study focused on defining optimized modulators of these receptors, as well as exploring how local anchoring influences soluble peptide function. Serial substitution of residue 7 in membrane-tethered GIP (tGIP) led to a wide range of activities at the GIP receptor, with [G(7)]tGIP showing enhanced efficacy compared to the wild type construct. In contrast, introduction of G(7) into the related ligands, tGLP-1 and tethered exendin-4 (tEXE4), did not affect signaling at the cognate GLP-1 receptor. Both soluble and tethered GIP and GLP-1 were selective activators of their respective receptors. Although soluble EXE4 is highly selective for the GLP-1 receptor, unexpectedly, tethered EXE4 was found to be a potent activator of both the GLP-1 and GIP receptors. Diverging from the pharmacological properties of soluble and tethered GIP, the newly identified GIP-R agonists, (i.e. [G(7)]tGIP and tEXE4) failed to trigger cognate receptor endocytosis. In an attempt to recapitulate the dual agonism observed with tEXE4, we conjugated soluble EXE4 to a lipid moiety. Not only did this soluble peptide activate both the GLP-1 and GIP receptors but, when added to receptor expressing cells, the activity persists despite serial washes. These findings suggest that conversion of a recombinant MTL to a soluble membrane anchored equivalent offers a means to prolong ligand function, as well as to design agonists that can simultaneously act on more than one therapeutic target. Show less

Glucagon-like peptide 1 (GLP-1) and glucose-dependent insulinotropic polypeptide (GIP) are gut-derived incretin hormones that regulate blood glucose levels. In addition to their widely accepted insulinotropic role, there is evidence that GLP-1 modulates feeding behavior and GIP regulates lipid metabolism, thereby promoting postprandial fat deposition. In this study, we investigated whether naturally occurring polymorphisms in the GLP-1 receptor (GLP-1R) and the GIP receptor (GIP-R) affect the pharmacological properties of these proteins. After transient expression of the receptors in human embryonic kidney 293 cells, basal and ligand-induced cAMP production were assessed by use of luciferase reporter gene assays. Our data reveal that the wild-type GIP-R displays a considerable degree of ligand-independent activity. In comparison, the GIP-R variants C46S, G198C, R316L, and E354Q show a marked decrease in basal signaling that may, at least in part, be explained by reduced cell surface expression. When stimulated with GIP, the C46S and R316L mutants display significantly reduced potency (>1000 and 25- fold, respectively) compared with wild type. Complementary competition binding assays further demonstrate that the C46S variant fails to bind radio-iodinated GIP, whereas all other GIP-R mutants maintain normal ligand affinity. In contrast to the GIP-R, the wild-type GLP-1R lacks constitutive activity. Furthermore, none of the 10 GLP-1R missense mutations showed an alteration in pharmacological properties versus wild type. The extent to which abnormalities in GIP-R function may lead to physiological changes or affect drug sensitivity in selected populations (e.g., obese, diabetic individuals) remains to be further investigated. Show less