👤 Charles Benson

Tirzepatide, a single-molecule dual glucose-dependent insulinotropic polypeptide (GIP)/glucagon-like peptide-1 (GLP-1) receptor (R) agonist, has shown superiority in the reduction of blood glucose and body weight, above selective GLP-1R agonists, but the contribution of GIP to these effects remains incompletely understood. To characterize the preclinical and in-human effects of a long-acting GIPR agonist monotherapy in healthy participants and patients with type 2 diabetes (T2D). A long-acting GIPR agonist (LY3537021) was characterized in vitro and in Long-Evans diet-induced obese rats and Wistar rats. Next, a phase 1, randomized, placebo-controlled, single ascending dose (SAD)/multiple ascending dose (MAD) study explored the safety, tolerability, pharmacokinetics, and pharmacodynamics of LY3537021 in healthy participants and participants with T2D in Singapore. In vitro, LY3537021 demonstrated potency greater than native GIP and selectivity for the GIPR. In vivo in rats, chronic treatment with LY3537021 resulted in weight loss and improved glycemic control during a glucose tolerance test. The phase 1 clinical study enrolled 85 healthy participants and patients with T2D (SAD, n = 47 [aged 25-64 years]; MAD, n = 38 [aged 25-69 years]; average baseline BMI was 25.9-27.0 kg/m In vivo studies demonstrated that LY3537021 reduced body weight and improved glycemia during a glucose challenge in rats. The phase 1 study demonstrated that the long-acting GIPR agonist LY3537021 was well tolerated, induced weight loss, and improved glucose control in humans. These observations better define the therapeutic benefit of long-acting GIPR agonists and support a distinct contribution of GIP agonism to the benefits observed with multi-agonist peptides that act via the GIPR. Future studies are needed in more diverse populations and in cohorts with overweight/obesity to confirm these findings. GOV: NCT04586907. Show less

Inflammation has emerged as a prominent feature of bipolar disorder (BD) pathophysiology, drawing attention to brain barriers known to regulate immune-brain interactions. While perturbation of the blood-brain barrier has been reported in BD, the blood-cerebrospinal fluid (CSF) barrier formed largely by the choroid plexus (ChP) remains underexamined. To address this gap in knowledge, we used a multiplex array to measure cytokine protein abundance in postmortem ChP tissue from individuals with BD and unaffected controls, revealing elevated levels of CCL2 and SPP1, factors associated with monocyte and macrophage recruitment and activation. In contrast, expression of cytokines involved in tissue homeostasis, trophic support, and immune signaling, including OSM, IGF-1, CX3CL1, TGFB3, GDNF, LIF, BDNF, SCF, and FGFs, was reduced. Several cytokines, including CCL2 and PLGF, exhibited condition-specific divergent age trajectories. Bulk RNA sequencing of the same cohort revealed a modest set of differentially expressed genes, including transcripts associated with oxidative stress, mitochondrial function, and immune regulation that were upregulated in BD. Notably, the BD CSF biomarker NELL2 was downregulated in the ChP. Gene set enrichment analysis highlighted activation of inflammatory and cellular stress pathways, as well as reduced expression of junction-related gene programs. These findings suggest a shift in ChP function in BD characterized by increased pro-inflammatory signaling and reduced trophic and barrier-supportive activity. Together, these data identify the ChP as an active site of immune dysregulation in BD and support the broader notion of brain barrier dysfunction in mood disorder pathology. Show less

Herpes Zoster in humans is the result of varicella zoster virus (VZV) infection. Injecting rats with varicella zoster virus produces pain similar to herpes zoster "shingles" pain in humans. . In a previous study, orofacial pain was induced by injecting the whisker pad of male rats with VZV and the pain response increased after attenuating neurexin 3 (Nrxn3) expression in the central amygdala. Neurons descend from the central amygdala to the lateral parabrachial nucleus and orofacial pain signals ascend to the lateral parabrachial nucleus. GABAergic neurons within the central amygdala regulate pain by inhibiting activity within the lateral parabrachial nucleus. Attenuating Nrxn3 expression in the central amygdala increased GABA release in the lateral parabrachial nucleus suggesting Nrxn3 controls pain by regulating GABA release. Nrxn3 can also control synaptic connections between neurons, and we hypothesized that Nrxn3 knockdown in the central amygdala would reduce the number of GABAergic synaptic connections in the lateral parabrachial nucleus and increase VZV associated pain. To test this idea, the number of synaptic connections between GABAergic cells of the central amygdala and excitatory or dynorphin positive neurons within the lateral parabrachial nucleus were quantitated after infusion of a virus expressing synaptophysin. Synaptophysin is a synaptic vesicle protein that labels neuronal synaptic connections. These connections were measured in rats with and without whisker pad injection of VZV and knockdown of Nrxn3 within the central amygdala. Orofacial pain was measured using a place escape avoidance paradigm. GABAergic synaptic connections were reduced in the lateral parabrachial nucleus after Nrxn3 knockdown. Rats with a reduction in the number of connections had an increase in VZV associated orofacial pain. Immunostaining with the pain marker prodynorphin indicated that the reduction in GABAergic connections was primarily associated with prodynorphin positive neurons. The results suggest Nrxn3 reduces VZV associated orofacial pain, in part, by enhancing synaptic connections between GABA cells of the central amygdala and pain neurons within the lateral parabrachial nucleus. Show less

With an increasing prevalence of obesity, there is a need for new therapies to improve body weight management and metabolic health. Multireceptor agonists in development may provide approaches to fulfill this unmet medical need. LY3437943 is a novel triple agonist peptide at the glucagon receptor (GCGR), glucose-dependent insulinotropic polypeptide receptor (GIPR), and glucagon-like peptide-1 receptor (GLP-1R). In vitro, LY3437943 shows balanced GCGR and GLP-1R activity but more GIPR activity. In obese mice, administration of LY3437943 decreased body weight and improved glycemic control. Body weight loss was augmented by the addition of GCGR-mediated increases in energy expenditure to GIPR- and GLP-1R-driven calorie intake reduction. In a phase 1 single ascending dose study, LY3437943 showed a safety and tolerability profile similar to other incretins. Its pharmacokinetic profile supported once-weekly dosing, and a reduction in body weight persisted up to day 43 after a single dose. These findings warrant further clinical assessment of LY3437943. Show less

Short repeated sequences of 3-6 nucleotides are causing a growing number of over 50 microsatellite expansion disorders, which mainly present with neurodegenerative features. Although considered rare diseases in relation to the relatively low number of cases, these primarily adult-onset conditions, often debilitating and fatal in absence of a cure, collectively pose a large burden on healthcare systems in an ageing world population. The pathological mechanisms driving disease onset are complex implicating several non-exclusive mechanisms of neuronal injury linked to RNA and protein toxic gain- and loss- of functions. Adding to the complexity of pathogenesis, microsatellite repeat expansions are polymorphic and found in coding as well as in non-coding regions of genes. They form secondary and tertiary structures involving G-quadruplexes and atypical helices in repeated GC-rich sequences. Unwinding of these structures by RNA helicases plays multiple roles in the expression of genes including repeat-associated non-AUG (RAN) translation of polymeric-repeat proteins with aggregating and cytotoxic properties. Here, we will briefly review the pathogenic mechanisms mediated by microsatellite repeat expansions prior to focus on the RNA helicases eIF4A, DDX3X and DHX36 which act as modifiers of RAN translation in C9ORF72-linked amyotrophic lateral sclerosis/frontotemporal dementia (C9ORF72-ALS/FTD) and Fragile X-associated tremor/ataxia syndrome (FXTAS). We will further review the RNA helicases DDX5/17, DHX9, Dicer and UPF1 which play additional roles in the dysregulation of RNA metabolism in repeat expansion disorders. In addition, we will contrast these with the roles of other RNA helicases such as DDX19/20, senataxin and others which have been associated with neurodegeneration independently of microsatellite repeat expansions. Finally, we will discuss the challenges and potential opportunities that are associated with the targeting of RNA helicases for the development of future therapeutic approaches. Show less

Varicella zoster virus (VZV) induces orofacial pain and female rats show greater pain than male rats. During the proestrus phase of the estrous cycle the VZV induce pain response is attenuated in female rats. A screen of gene expression changes in diestrus and proestrus female rats indicated neurexin 3α (Nrxn3α) was elevated in the central amygdala of proestrus rats vs. diestrus rats. GABAergic neurons descend from the central amygdala to the lateral parabrachial region and Nrxn3α is important for presynaptic γ-Aminobutyric acid (GABA) release. Thus, we hypothesized that the reduced orofacial pain in male rats and proestrus female rats is the result of increased Nrxn3α within the central amygdala that increases GABA release from axon terminals within the parabrachial and inhibits ascending pain signals. To test this hypothesis Nrxn3 α expression was knocked-down by infusing shRNA constructs in the central amygdala. Then GABA release in the parabrachial was quantitated concomitant with measuring the pain response. Results revealed that knockdown of Nrxn3α expression significantly increases the pain response in both male rats and proestrus female rats vs. diestrus rats. GABA release was significantly reduced in the parabrachial of male and proestrus female rats after Nrxn3α knockdown. Neuronal activity of excitatory neurons was significantly inhibited in the parabrachial after Nrxn3α knockdown. These results are consistent with the idea that Nrxn3 within the central amygdala controls VZV associated pain by regulating GABA release in the lateral parabrachial that then modulates ascending orofacial pain signals. Show less

Hypertrophic cardiomyopathy (HCM) is characterized by left ventricular hypertrophy (LVH) in the absence of predisposing cardiovascular conditions. Pathogenic variants in at least 16 cardiac sarcomeric genes have been implicated in HCM, most of which act in a dominant-negative fashion. However loss-of-function (haploinsufficiency) is the most common disease mechanism for pathogenic variants in MYBPC3, suggesting that MYBPC3 complete deletion may play a role in HCM pathogenesis. Here, we investigate MYBPC3 complete deletion as a disease mechanism in HCM by analyzing two unrelated patients with confirmed diagnosis of HCM that tested negative by Sanger sequencing analysis. MYBPC3 complete deletion was investigated by Multiplex ligation-dependent probe amplification (MLPA) and microarray analyses. The mechanism of deletion was investigated by interrogating the SINEBase database. Patient-1 was diagnosed with nonobstructive HCM in his mid-40s while undergoing assessment for palpitations, and patient-2 with obstructive HCM in his late-20s while undergoing systolic heart murmur assessment for an unrelated illness. MLPA testing revealed a heterozygous deletion of all MYBPC3 exons in both patients. Subsequent microarray testing confirmed these deletions which extended beyond the 5' and 3' ends of MYBPC3. Genomic assessment suggested that these deletions resulted from Alu/Alu-homologous recombination. Our results demonstrate that haploinsufficiency resulting from MYBPC3 complete deletion, potentially mediated by Alu recombination, is an important disease mechanism in cardiomyopathy and emphasizes the importance of copy number variation analysis in patients clinically suspected of HCM. Show less

Current guidelines recommend initiating family screening for hypertrophic cardiomyopathy (HCM) after age 10 or 12 years unless early screening criteria are met. The aim was to evaluate if current screening guidelines miss early onset disease. Children who underwent family screening for HCM before age 18 years were analysed. Major cardiac events (MaCEs) were defined as death, sudden cardiac death (SCD), or need for major cardiac interventions (myectomy, implantable cardioverter-defibrillator insertion, transplantation). Of 524 children screened, 331 were under 10 years of age, 9.9% had echocardiographic evidence of HCM, and 1.1% were symptomatic at first screening. The median (interquartile range) age at HCM onset was 8.9 (4.7-13.4) years, and at MaCE was 10.9 (8.5-14.3) years with a median time to MaCE from HCM onset of 1.5 (0.5-4.1) years. About 52.5% phenotype-positive children and 41% with MaCEs were <10 years old. Only 69% children with early HCM met early screening criteria. Cox regression identified male gender, family history of SCD, and pathogenic variants in MYH7/MYBPC3 as a predictor of early onset HCM and MaCEs. A third of children not eligible for early screening by current guidelines had phenotype-positive HCM. MYH7 and MYBC3 mutation-positive patients were at highest risk for developing early HCM and experiencing an event or requiring a major intervention. Our findings suggest that younger family members should be considered for early clinical and genetic screening to identify the subset in need of closer monitoring and interventions. Show less

Children with hypertrophic cardiomyopathy (HCM) experience sudden cardiac death (SCD) and other life-threatening events. We assessed if affected gene and variant burden predict outcomes. Patients <18 years old with primary HCM with a pathogenic variant or variant of uncertain significance in cardiomyopathy genes were included. Association of gene and variant number and type with freedom from major adverse cardiac events (MACE), that is, ICD insertion, myectomy, aborted SCD, transplantation or death, was assessed by Cox regression. A total of 98 of 155 gene-tested patients carried a non-benign variant. The primary affected gene was MYH7 in 35% (MYH7+) and MYBPC3 in 49% (MYBPC3+). MYH7+ patients had earlier disease onset and higher risk of MACE (hazard ratio 2.7, 95% CI 1.3-5.7). Risk of MACE was also higher in patients with multiple variants (n = 16) (HR 2.5, CI: 1.1-5.9) compared to a propensity score-matched single variant subset, after adjustment for primary gene, and in patients with de novo (n = 18) vs inherited variants (HR 5.7, CI: 2.6-12.7). Affected gene (eg, MYH7), higher variant burden and de novo variant status are independently associated with earlier onset and higher frequency of adverse outcomes in pediatric HCM, highlighting the importance of genetic risk stratification in HCM. Show less