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BackgroundMajor depressive disorder is one of the most commonly diagnosed mental illnesses worldwide, with a higher prevalence in women than in men. Although currently available pharmacological therapeutics help many individuals, they are not effective for most. Animal models have been important for the discovery of molecular alterations in stress and depression, but difficulties in adapting animal models of depression for females has impeded progress in developing novel therapeutic treatments that may be more efficacious for women.MethodsUsing the California mouse social defeat model, we took a multidisciplinary approach to identify stress-sensitive molecular targets that have translational relevance for women. We determined the impact of stress on transcriptional profiles in male and female California mouse nucleus accumbens (NAc) and compared these results with data from postmortem samples of the NAc from men and women diagnosed with major depressive disorder.ResultsOur cross-species computational analyses identified Rgs2 (regulator of G protein signaling 2) as a transcript downregulated by social defeat stress in female California mice and in women with major depressive disorder. RGS2 plays a key role in signal regulation of neuropeptide and neurotransmitter receptors. Viral vector-mediated overexpression of Rgs2 in the NAc restored social approach and sucrose preference in stressed female California mice.ConclusionsThese studies show that Rgs2 acting in the NAc has functional properties that translate to changes in anxiety- and depression-related behavior. Future studies should investigate whether targeting Rgs2 represents a novel target for treatment-resistant depression in women.

Oxytocin is a neuropeptide that can produce anxiolytic effects and promote social approach. However, emerging evidence shows that under some conditions, oxytocin can instead induce anxiety-related behaviors. These diverse effects of oxytocin appear to be mediated by circuit-specific actions. Recent data showed that inhibition of oxytocin receptors (OTRs) in the bed nucleus of the stria terminalis (BNST) was sufficient to increase social approach and decrease social vigilance in female California mice (Peromyscus californicus) exposed to social defeat stress. As a member of the G-protein coupled receptor family, OTRs can induce distinct downstream pathways by coupling to different G-protein isoforms. We show that infusion of carbetocin, a biased OTR-Gq agonist, in the BNST reduced social approach in both female and male California mice. In both females and males, carbetocin also increased social vigilance. To gain insight into cell types that could be mediating this effect, we analyzed previously published single-cell RNAseq data from the BNST and nucleus accumbens (NAc). In the NAc, we and others showed that OTR activation promotes social approach behaviors. In the BNST, Oxtr was expressed in over 40 cell types, that span both posterior and anterior subregions of the BNST. The majority of Oxtr-expressing neurons were GABAergic. In the anterior regions of BNST targeted in our carbetocin experiments, Cyp26b1-expressing neurons had high average Oxtr expression. In the NAc, most Oxtr+ cells were D1 dopamine receptor-expressing neurons and interneurons. These differences in Oxtr cell type distribution may help explain how activation of OTR in BNST versus NAc can have different effects on social approach and social vigilance.

Oxytocin is currently being considered as a novel therapeutic for anxiety disorders due to its ability to promote affiliative behaviors. In the nucleus accumbens (NAc) activation of oxytocin receptors (OTR) promotes social approach (time spent near an unfamiliar individual). Here, we show that stressful social experiences reduce the expression of NAc OTR mRNA, coinciding with decreases in social approach. Social stressors also increase social vigilance, characterized as orienting to an unfamiliar individual without approaching. Vigilance is a key component of behavioral inhibition, a personality trait that is a risk factor for anxiety disorders. To understand whether NAc OTR can modulate both social approach and vigilance, we use pharmacological approaches to assess the impact of activation or inhibition of NAc OTR downstream pathways on these behaviors. First, we show that in unstressed male and female California mice, inhibition of OTR by an unbiased antagonist (L-368,899) reduces social approach but does not induce social vigilance. Next, we show that infusion of Atosiban, an OTR-Gq antagonist/OTR-Gi agonist, has the same effect in unstressed females. Finally, we show that Carbetocin, a biased OTR-Gq agonist, increases social approach in stressed females while simultaneously inhibiting social vigilance. Taken together these data suggest that OTR in the NAc differentially modulate social approach and social vigilance, primarily through an OTR-Gq mechanism. Importantly, pharmacological inhibition of OTR alone is insufficient to induce vigilance in unstressed mice, suggesting that mechanisms modulating social approach may be distinct from mechanisms modulating social vigilance.

Background: Development of anti-drug antibodies (ADAs) and neutralizing antibodies (NAbs) to monoclonal antibodies may adversely impact pharmacokinetics, efficacy, and/or safety. Objective: To describe incidence, titer, and persistence of dupilumab ADAs and NAbs, and their effects on pharmacokinetics, efficacy, and safety in patients with atopic dermatitis (AD). Methods: This analysis included seven phase 3 randomized, placebo-controlled (N=2,992) and two long-term open-label extension (N=2,287) trials of subcutaneous dupilumab in adults and pediatric patients with moderate-to-severe AD. ADA, NAb, and dupilumab concentration in serum were assessed using validated immunoassays. ADA impacts on efficacy (EASI) and safety were assessed. Results: Treatment-emergent ADAs were observed in up to 8.6% (aged ≥18 years), 16.0% (12-17 years), 5.3% (6-11 years), and 2.0% (6 months to 5 years) dupilumab-treated patients. Among dupilumab-treated patients, ≤3.7% had persistent responses, <1% had high titers (≥10,000), and ≤5.1% were NAb-positive. NAbs were more common in patients with moderate- and high-titer ADA responses. High-titer ADAs, while infrequent, were the variable most associated with lower dupilumab concentrations in serum and loss of efficacy, independent of NAb status. Efficacy was generally similar in ADA-positive and -negative patients. For most patients with high- or moderate-titer ADAs, titers decreased and efficacy improved over time with continued dupilumab treatment. ADA-positive and -negative patients had similar incidences of treatment-emergent and serious treatment-emergent adverse events. One patient with high-titer ADAs developed serum sickness. Conclusion: In patients with AD, ADAs and NAbs had minimal impact on dupilumab concentration, efficacy, and safety, except for high-titer ADAs in a small number of patients. Clinical trial registration: ClinicalTrials.gov, identifiers (NCT02277743, NCT02277769, NCT02260986, NCT02395133, NCT01949311, NCT03054428, NCT03345914, NCT02612454, and NCT03346434). [ABSTRACT FROM AUTHOR]

Itepekimab, a monoclonal antibody against interleukin‐33, has demonstrated clinical utility in previous studies in patients with asthma and chronic obstructive pulmonary disease. An autoinjector (AI) has been developed for administering itepekimab to facilitate further development. This study compared pharmacokinetics of single 300‐mg itepekimab subcutaneous administration via an AI versus a prefilled syringe (PFS). Of 90 healthy volunteers enrolled in this Phase 1, parallel‐design, randomized study and stratified by body weight (50 to <70 kg, ≥70 to <80 kg, ≥80 to 100 kg) and injection site (abdomen, thigh, or arm), 84 completed the study. Systemic exposure of itepekimab was similar for both groups. Point estimates for geometric mean ratios of pharmacokinetic parameters for AI versus PFS groups were 1.01 for maximum serum concentration, 1.06 for area under the serum concentration‐time curve to the last quantifiable concentration, and 1.04 for area under the serum concentration‐time curve extrapolated to infinity. The exposure was similar for both devices in each body weight and injection site subgroup. Overall, systemic exposure of 300‐mg single‐dose itepekimab in healthy participants was comparable when administered subcutaneously via an AI device and PFS, with an acceptable safety profile in both device groups. [ABSTRACT FROM AUTHOR]

Allergic disease prevalence has increased globally with the subset of type 2 inflammatory diseases playing a substantial role. Type 2 inflammatory diseases may differ in clinical presentation, but they exhibit shared pathophysiology that is targeted by the unique pharmacology of dupilumab. Dupilumab binds to the interleukin (IL)‐4 receptor alpha subunit (IL‐4Rα) that blocks IL‐4 and IL‐13 signaling, two key drivers of type 2 inflammation. Herein, we review the mechanism of action and pharmacology of dupilumab, and the clinical evidence that led to the regulatory approvals of dupilumab for the treatment of numerous type 2 inflammatory diseases: atopic dermatitis, asthma, chronic rhinosinusitis with nasal polyposis, eosinophilic esophagitis, and prurigo nodularis. [ABSTRACT FROM AUTHOR]

Interleukin‐33 (IL‐33) is a proinflammatory alarmin cytokine released by damaged epithelial tissue cells that initiates and amplifies both type 1 and type 2 inflammatory cascades. A role for IL‐33 in atopic dermatitis (AD; a chronic, relapsing type 2 inflammatory disease of the skin) has been proposed. Itepekimab is a novel human IgG4P monoclonal antibody against IL‐33, currently in clinical development for chronic obstructive pulmonary disease (COPD). Two global phase II studies—a dose‐ranging itepekimab monotherapy study (NCT03738423) and a proof‐of‐concept study of itepekimab alone and in combination with dupilumab (NCT03736967)—were conducted in patients with moderate‐to‐severe AD to assess safety, tolerability, pharmacokinetics, pharmacodynamics, and efficacy; both studies were terminated following an interim analysis of the proof‐of‐concept study, which failed to demonstrate the efficacy of itepekimab. In these two studies, itepekimab exhibited linear and dose‐proportional pharmacokinetics. Pharmacodynamics of total IL‐33 indicated that itepekimab saturated binding to the target in serum at 300 mg q2w and q4w doses, and decreased blood eosinophil counts. Concentration–time profiles of itepekimab and total IL‐33 were similar for itepekimab with or without dupilumab, and between East Asian and non‐East Asian subgroups. Itepekimab was generally well tolerated, both alone and in combination with dupilumab. The lack of clinical efficacy for itepekimab observed in these studies suggests that IL‐33 may not be a key pathogenic driver in moderate‐to‐severe AD. [ABSTRACT FROM AUTHOR]