Generation of KS-133 as a Novel Bicyclic Peptide with a Potent and Selective VIPR2 Antagonist Activity that Counteracts Cognitive Decline in a Mouse Model of Psychiatric Disorders

Comorbid health outcomes in patients with schizophrenia: an umbrella review of systematic reviews and meta-analyses

There is no comprehensive umbrella review exploring the connection between schizophrenia and various health outcomes. Therefore, we aimed to systematically review existing meta-analyses about schizophrenia-associated comorbid health outcomes and validate the evidence levels. We performed an umbrella review of meta-analyses of observational studies to explore comorbid health outcomes in individuals with schizophrenia. Searches were conducted across PubMed/MEDLINE, EMBASE, ClinicalKey, and Google Scholar up to September 5, 2023, targeting meta-analyses of observational studies related to comorbid health outcomes in individuals with schizophrenia. We applied AMSTAR2 for data extraction and quality assessment, adhering to PRISMA guidelines. Evidence credibility was evaluated and categorized by evidence quality. Our protocol was registered with PROSPERO (CRD42024498833). Risk and protective factors were analyzed and presented through equivalent odds ratios (eRR). In this umbrella review, we analyzed 9 meta-analyses, including 88 original articles, covering 21 comorbid health outcomes with over 66 million participants across 19 countries. Patients with schizophrenia showed significant associations with multiple health outcomes, including asthma (eRR, 1.71 [95% CI, 1.05-2.78], class and quality of evidence [CE] = non-significant), chronic obstructive pulmonary disease (1.73 [1.25-2.37], CE = weak), pneumonia (2.63 [1.11-6.23], CE = weak), breast cancer of female patients (1.31 [1.04-1.65], CE = weak), cardiovascular disease (1.53 [1.12-2.11], CE = weak), stroke (1.71 [1.30-2.25], CE = weak), congestive heart failure (1.81 [1.21-2.69], CE = weak), sexual dysfunction (2.30 [1.75-3.04], CE = weak), fracture (1.63 [1.10-2.40], CE = weak), dementia (2.29 [1.19-4.39], CE = weak), and psoriasis (1.83 [1.18-2.83] CE = weak). Our study underscores the imperative for an integrated treatment approach to schizophrenia, highlighting its broad impact across respiratory, cardiovascular, sexual, neurological, and dermatological health domains. Given the predominantly non-significant to weak evidence levels, further studies are needed to reinforce our understanding.

Cyclic Peptides KS-133 and KS-487 Multifunctionalized Nanoparticles Enable Efficient Brain Targeting for Treating Schizophrenia

Establishing drug delivery systems (DDSs) for transporting drugs from peripheral tissues to the brain is crucial for treating central nervous system diseases. We previously reported the interactions of (1) KS-133, a selective antagonist peptide, with vasoactive intestinal peptide receptor 2 (VIPR2), a drug target for schizophrenia, and (2) KS-487, a selective binding peptide, with the cluster IV domain of low-density lipoprotein receptor-related protein 1 (LRP1), which is involved in crossing the blood-brain barrier. We developed a novel DDS-based strategy for treating schizophrenia using KS-487 as a brain-targeting peptide and KS-133 as a drug. Dibenzocyclooctyne-KS-487 was conjugated with N3-indocyanine green (ICG) using a click reaction and administered intravenously into mice. Fluorescence was clearly observed from ICG in the brains of the mice. Nanoparticles (NPs) encapsulating ICG and displaying KS-487 were prepared and subcutaneously administered to mice, resulting in a significant accumulation of ICG in the brain. Pharmacokinetic analysis of NPs containing KS-133 and displaying KS-487 (KS-133/KS-487 NPs) revealed the time-dependent transport of KS-133 into the brain. KS-133/KS-487 NPs were subcutaneously administered to mouse models of schizophrenia, which significantly improved cognitive dysfunction. This is the first study to demonstrate the potential therapeutic efficacy of a multifunctionalized multipeptide NP in inhibiting VIPR2.

Lipid bilayer membrane permeability mechanism of the K-Ras(G12D)-inhibitory bicyclic peptide KS-58 elucidated by molecular dynamics simulations

Peptides are mid-size molecules (700-2000 g/mol) and have attracted particular interest as therapeutic modalities as they are superior in controlling protein-protein interactions, a process that is a typical drug target category, compared with small molecules (<500 g/mol). In 2020, we identified KS-58 (1333 g/mol) as a K-Ras(G12D)-inhibitory bicyclic peptide and suggested its cell membrane permeability. However, the membrane permeability mechanism had not been elucidated. In this study, we aim to clarify the mechanism by molecular dynamics (MD) simulations. Initially, we simulated the molecular conformations of KS-58 in water (a polar solvent) and in chloroform (a non-polar solvent). The identified stable conformations were significantly different in each solvent. KS-58 behaves as a chameleon-like molecule as it alters its polar surface area (PSA) depending on the solvent environment. It was also discovered that orientation of Asp's side chain is a critical energy barrier for KS-58 altering its conformation from hydrophilic to lipophilic. Taking these properties into consideration, we simulated its lipid bilayer membrane permeability. KS-58 shifted toward the inside of the lipid bilayer membrane with altering its conformations to lipophilic. When the simulation condition was set in deionized form of that carboxy group of Asp, KS-58 traveled deeper inside the cell membrane. PSA and the depth of the membrane penetration correlated. In vitro data suggested that cell membrane permeability of KS-58 is improved in weakly acidic conditions leading to partial deionization of the carboxy group. Our data provide an example of the molecular properties of mid-size peptides with membrane accessibility and propose an effective metadynamics approach to elucidate such molecular mechanisms by MD simulations.

Blockade of vasoactive intestinal peptide receptor 2 (VIPR2) signaling suppresses cyclin D1-dependent cell-cycle progression in MCF-7 cells

Vasoactive intestinal peptide (VIP) receptor 2 (VIPR2) is a G protein-coupled receptor that binds to Gαs, Gαi, and Gαq proteins to regulate various downstream signaling molecules, such as protein kinase A (PKA), phosphatidylinositol 3-kinase (PI3K), and phospholipase C. In this study, we examined the role of VIPR2 in cell cycle progression. KS-133, a newly developed VIPR2-selective antagonist peptide, attenuated VIP-induced cell proliferation in MCF-7 cells. The percentage of cells in the S-M phase was decreased in MCF-7 cells treated with KS-133. KS-133 in the presence of VIP decreased the phosphorylation of extracellular signal-regulated kinase (ERK), AKT, and glycogen synthase kinase-3β (GSK3β), resulting in a decrease in cyclin D1 levels. In MCF-7 cells stably-expressing VIPR2, KS-133 decreased PI3K activity and cAMP levels. Treatment with the ERK-specific kinase (MEK) inhibitor U0126 and the class I PI3K inhibitor ZSTK474 decreased the percentage of cells in the S phase. KS-133 reduced the percentage of cells in the S phase more than treatment with U0126 or ZSTK474 alone and did not affect the effect of the mixture of these inhibitors. Our findings suggest that VIPR2 signaling regulates cyclin D1 levels through the cAMP/PKA/ERK and PI3K/AKT/GSK3β pathways, and mediates the G1/S transition to control cell proliferation.

Increased pituitary adenylate cyclase-activating peptide genes expression in the prefrontal cortex in schizophrenia in relation to suicide

Introduction

Pituitary adenylate cyclase-activating peptide (PACAP) is a stress-related neuropeptide that is produced in several brain areas. It acts by 3 receptors: PACAP type-1 (PAC1), vasoactive intestinal peptide (VIP) -1 and -2 (VPAC1 and 2). Data on polymorphisms in PACAP and PAC1 indicate a relationship of the PACAP system with schizophrenia (SCZ).

Methods

The prefrontal cortex was chosen to measure PACAP-gene related expression changes, since this is a central structure in the symptoms of schizophrenia (SCZ). We investigated alterations in the expression of the PACAP-related genes by qPCR in the human dorsolateral prefrontal cortex (DLPFC) and anterior cingulate cortex (ACC) of 35 SCZ patients and 34 matched controls in relation to SCZ, suicide, gender and medication.

Results

The ACC revealed an upregulation in PACAP, PAC1, VPAC1 and VPAC2 in SCZ suicide (S) completers compared to controls. An increase in PACAP, VPAC1 and VPAC2 expression was also present in the ACC in SCZ-S compared to SCZ patients who died naturally (SCZ-N). In the DLPFC, an increase in PAC1 was found in SCZ-N patients compared to SCZ-S and controls. Moreover, an increase in all PACAP-related genes was present in SCZ-N male patients compared to SCZ-N females. Concluding, expression changes were found in PACAP-related genes in relation to SCZ, suicide and gender. In particular, there was a higher PACAP-related gene expression in SCZ patients in the ACC in relation to suicide and in DLPFC in relation to SCZ.

Discussion

These findings suggest a potential link between PACAP and the pathophysiology of SCZ and suicide. Further research is needed to understand the functional significance and potential clinical applications of these changes.

The VIPR2-selective antagonist KS-133 changes macrophage polarization and exerts potent anti-tumor effects as a single agent and in combination with an anti-PD-1 antibody

We have previously demonstrated that KS-133 is a specific and potent antagonist of vasoactive intestinal peptide receptor 2 (VIPR2). We have also shown that vasoactive intestinal peptide-VIPR2 signaling affects the polarity and activation of tumor-associated macrophages, which is another strategy for cancer immunotherapy apart from the activation of effector T cells. In this study, we aimed to examine whether the selective blockade of VIPR2 by KS-133 changes the polarization of macrophages and induces anti-tumor effects. In the presence of KS-133, genetic markers indicative of tumor-aggressive M1-type macrophages were upregulated, and conversely, those of tumor-supportive M2-type macrophages were downregulated. Daily subcutaneous administration of KS-133 tended to suppress the growth of CT26 tumors (murine colorectal cancer-derived cells) implanted subcutaneously in Balb/c mice. To improve the pharmacological efficacy and reduce the number of doses, we examined a nanoformulation of KS-133 using the US Food and Drug Administration-approved pharmaceutical additive surfactant Cremophor® EL. KS-133 nanoparticles (NPs) were approximately 15 nm in size and stable at 4°C after preparation. Meanwhile, KS-133 was gradually released from the NPs as the temperature was increased. Subcutaneous administration of KS-133 NPs once every 3 days had stronger anti-tumor effects than daily subcutaneous administration of KS-133. Furthermore, KS-133 NPs significantly enhanced the pharmacological efficacy of an immune checkpoint-inhibiting anti-PD-1 antibody. A pharmacokinetic study suggested that the enhancement of anti-tumor activity was associated with improvement of the pharmacokinetic profile of KS-133 upon nanoformulation. Our data have revealed that specific blockade of VIPR2 by KS-133 has therapeutic potential for cancer both alone and in combination with immune checkpoint inhibitors.

Vasoactive intestinal peptide receptor 2 signaling promotes breast cancer cell proliferation by enhancing the ERK pathway

Vasoactive intestinal peptide (VIP) receptor 2 (VIPR2) is a class B G protein-coupled receptor with the neuropeptide VIP as a ligand. Increased VIPR2 mRNA expression and/or VIPR2 gene copy number has been documented in several cancers including breast carcinoma. However, the pathophysiological role of increased VIPR2 in the proliferation of breast cancer cells remains largely unknown. In this study, we found that VIPR2 overexpression in MCF-7 and MDA-MB-231 cells, human breast cancer cell lines, promoted cell proliferation. Increased VIPR2 also exacerbated intraperitoneal proliferation of breast cancer MDA-MB-231 cells in a tumor nude mouse model in vivo. Treatment with KS-133, a VIPR2-selective antagonist peptide, significantly inhibited VIP-induced cell proliferation in VIPR2-overexpressing MCF-7 and MDA-MB-231 cells. Overexpressed VIPR2 caused increases in the levels of cAMP and phosphorylated extracellular signal-regulated kinase (ERK), which involves a VIPR2 signaling pathway through Gs protein. Additionally, phosphorylation of vasodilator-stimulated phosphoprotein (Ser157) and cAMP response element binding protein (Ser133) in VIPR2-overexpressing MCF-7 cells was greater than that in control cells, suggesting the increased PKA activity. Moreover, an inhibitor of mitogen-activated protein kinase kinase, U0126, attenuated tumor proliferation in exogenous VIPR2-expressing MCF-7 and MDA-MB-231 cells at the same level as observed in EGFP-expressing cells treated with U0126. Together, these findings suggest that VIPR2 controls breast tumor growth by regulating the cAMP/PKA/ERK signaling pathway, and the excessive expression of VIPR2 may lead to an exacerbation of breast carcinoma.

Generation of KS-487 as a novel LRP1-binding cyclic peptide with higher affinity, higher stability and BBB permeability

The blood–brain barrier (BBB) is a major hurdle in drug discovery for central nervous system (CNS) disorders. Particularly, mid-size molecules and macromolecules (e.g., peptides and antibodies) that modulate intractable drug targets such as protein-protein interaction are prevented from entering the CNS via BBB. The receptor-mediated transcytosis (RMT) pathway has been examined to deliver these molecules to CNS. Among the receptors, low-density lipoprotein receptor-related protein 1 (LRP1) has been emerged as one of the promising receptors for RMT. Although several LRP1-binding peptides have been reported, no drugs are available on the market based on the combination of reported LRP1-binding peptides and therapeutic molecules. One reason may be stability in vivo and BBB-permeability of the peptides. The present study aims to identify a novel LRP1-binding peptide for RMT, where we successfully generated a 15-mer cyclic peptide named KS-487. It explicitly bound to Cluster 4 domain of LRP1 with the binding EC₅₀ value of 10.5 nM and was relatively stable in mouse plasma within 24 h. Moreover, its high BBB permeability was demonstrated using in vitro rat and monkey BBB models. By 24 h incubation, 13% and 17% of the added amount of KS-487 (10 μM) penetrated rat BBB and monkey BBB, respectively. KS-487 would be a potential candidate for the LRP1-mediated transcytosis-based drug delivery to CNS, as these values were significantly higher than those of the known LRP1-binding peptides—Angiopep-2 and L57.

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KS-487 exhibited higher BBB-permeability in vitro than Angiopep-2 and L57.

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About 28% of KS-487 remained intact after 24 h incubation in mouse plasma.

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About 15% of KS-487 crossed in vitro rat- and monkey-BBBs after 24 h incubation.

Vasoactive intestinal peptide–VIPR2 signaling regulates tumor cell migration

Phosphoinositide metabolism is critically involved in human cancer cell migration and metastatic growth. The formation of lamellipodia at the leading edge of migrating cells is regulated by metabolism of the inositol phospholipid PI(4,5)P₂ into PI(3,4,5)P₃. The synthesized PI(3,4,5)P₃ promotes the translocation of WASP family verprolin homologous protein 2 (WAVE2) to the plasma membrane and regulates guanine nucleotide exchange factor Rac-mediated actin filament remodeling. Here, we investigated if VIPR2, a receptor for vasoactive intestinal peptide (VIP), has a potential role in regulating cell migration via this pathway. We found that silencing of VIPR2 in MDA-MB-231 and MCF-7 human breast cancer cells inhibited VIP-induced cell migration. In contrast, stable expression of exogenous VIPR2 promoted VIP-induced tumor cell migration, an effect that was inhibited by the addition of a PI3-kinase (PI3K)γ inhibitor or a VIPR2-selective antagonist. VIPR2 stably-expressing cells exhibited increased PI3K activity. Membrane localization of PI(3,4,5)P₃ was significantly attenuated by VIPR2-silencing. VIPR2-silencing in MDA-MB-231 cells suppressed lamellipodium extension; in VIPR2-overexpressing cells, VIPR2 accumulated in the cell membrane on lamellipodia and co-localized with WAVE2. Conversely, VIPR2-silencing reduced WAVE2 level on the cell membrane and inhibited the interaction between WAVE2, actin-related protein 3, and actin. These findings suggest that VIP–VIPR2 signaling controls cancer migration by regulating WAVE2-mediated actin nucleation and elongation for lamellipodium formation through the synthesis of PI(3,4,5)P₃.