Machine learning models to predict ligand binding affinity for the orexin 1 receptor

The orexin 1 receptor (OX1R) is a G-protein coupled receptor that regulates a variety of physiological processes through interactions with the neuropeptides orexin A and B. Selective OX1R antagonists exhibit therapeutic effects in preclinical models of several behavioral disorders, including drug seeking and overeating. However, currently there are no selective OX1R antagonists approved for clinical use, fueling demand for novel compounds that act at this target. In this study, we meticulously curated a dataset comprising over 1300 OX1R ligands using a stringent filter and criteria cascade. Subsequently, we developed highly predictive quantitative structure-activity relationship (QSAR) models employing the optimized hyper-parameters for the random forest machine learning algorithm and twelve 2D molecular descriptors selected by recursive feature elimination with a 5-fold cross-validation process. The predictive capacity of the QSAR model was further assessed using an external test set and enrichment study, confirming its high predictivity. The practical applicability of our final QSAR model was demonstrated through virtual screening of the DrugBank database. This revealed two FDA-approved drugs (isavuconazole and cabozantinib) as potential OX1R ligands, confirmed by radiolabeled OX1R binding assays. To our best knowledge, this study represents the first report of highly predictive QSAR models on a large comprehensive dataset of diverse OX1R ligands, which should prove useful for the discovery and design of new compounds targeting this receptor.

Revisiting the evolution of Family B1 GPCRs and ligands: Insights from mollusca

Family B1 G protein-coupled receptors (GPCRs) are one of the most well studied neuropeptide receptor families since they play a central role in many biological processes including endocrine, gastrointestinal, cardiovascular and reproduction in animals. The genes for these receptors emerged from a common ancestral gene in bilaterian genomes and evolved via gene/genome duplications and deletions in vertebrate and invertebrate genomes. Their existence and function have mostly been characterized in vertebrates and few studies exist in invertebrate species. Recently, an increased interest in molluscs, means a series of genomes have become available, and since they are less modified than insect and nematode genomes, they are ideal to explore the origin and evolution of neuropeptide gene families. This review provides an overview of Family B1 GPCRs and their peptide ligands and incorporates new data obtained from Mollusca genomes and taking a comparative approach challenges existing models on their origin and evolution.

PACAP sequence modifications modulate the peptide antimicrobial activity against bacterial pathogens affecting aquaculture

The global aquaculture industry has significant losses each year due to disease outbreaks. Antibiotics are one of the common methods to treat fish infections, but prolonged use can lead to the emergence of resistant strains. Aeromonas spp. Infections are a common and problematic disease in fish, and members of this genera can produce antibiotic resistant strains. Antimicrobial peptides (AMPs) have emerged as an alternative method to treat and prevent infections and pituitary adenylate cyclase activating polypeptide (PACAP) is a prominent member of this family. The objective of this research was to study PACAP's direct antimicrobial activity and its toxicity in fish cells. Four synthetic variants of the natural PACAP from Clarias gariepinus were tested in addition to the natural variant. The experimental results show a different antimicrobial activity against A. salmonicida and A. hydrophila of each PACAP variant, and for the first time show dependence on the culture broth used. Furthermore, the results suggest that the underlying mechanism of PACAP antimicrobial activity includes a bacterial membrane permeabilizing effect, classifying PACAP as a membrane disruptive AMP. This study also demonstrated that the five PACAP variants evaluated showed low toxicity in vitro, at concentrations relevant for in vivo applications. Therefore, PACAP could be a promising alternative to antibiotics in the aquaculture sector.

Identification of Subtypes in Triple-negative Breast Cancer Based on Shared Genes Between Immunity and Cancer Stemness

The correlation between triple-negative breast cancer (TNBC) and genes related to immunity and cancer stemness, particularly shared genes, remains unclear. This study aimed to investigate the correlation of immunity and cancer stemness with the molecular subtyping and survival rates in TNBC using bioinformatics approaches. Differential gene analysis was conducted to identify TNBC-associated differentially expressed genes (DEGs). Cancer stem cell (CSC)-related genes were obtained using weighted gene coexpression network analysis. Immune-related gene sets were retrieved from the literature. Venn analysis was performed to identify the shared DEGs between immunity and cancer stemness in TNBC. Cluster analysis and survival analysis based on the expression of these genes were conducted to identify TNBC subtypes with significant survival differences. A total of 5259 TNBC-associated DEGs, 2214 CSC-related genes, 1793 immune-related genes, and 44 shared DEGs between immunity and cancer stemness were obtained. Among them, 3 shared DEGs were closely associated with TNBC survival rates ( P <0.05). Cluster and survival analyses revealed that among 3 subtypes, cluster2 exhibited the best survival rate, and cluster3 showed the worst survival rate ( P <0.05). Dendritic cells were highly infiltrated in cluster2, while plasma cells and resting mast cells were highly infiltrated in cluster3 ( P <0.05). Genes shared by immunity and cancer stemness were capable of classifying TNBC samples. TNBC patients of different subtypes exhibited significant differences in immune profiles, genetic mutations, and drug sensitivity. These findings could provide new insights into the pathogenesis of TNBC, the immune microenvironment, and the selection of therapeutic targets for drug treatment.

The processing intermediate of human amylin, pro-amylin(1-48), has in vivo and in vitro bioactivity

Amylin is released by pancreatic beta-cells in response to a meal and its major soluble mature form (37 amino acid-peptide) produces its biological effects by activating amylin receptors. Amylin is derived from larger propeptides that are processed within the synthesizing beta-cell. There are suggestions that a partially processed form, pro-amylin(1-48) is also secreted. We tested the hypothesis that pro-amylin(1-48) has biological activity and that human pro-amylin(1-48) may also form toxic pre-amyloid species. Amyloid formation, the ability to cross-seed and in vitro toxicity were similar between human pro-amylin(1-48) and amylin. Human pro-amylin(1-48) was active at amylin-responsive receptors, though its potency was reduced at rat, but not human amylin receptors. Pro-amylin(1-48) was able to promote anorexia by activating neurons of the area postrema, amylin's primary site of action, indicating that amylin can tolerate significant additions at the N-terminus without losing bioactivity. Our studies help to shed light on the possible roles of pro-amylin(1-48) which may be relevant for the development of future amylin-based drugs.

Dexmedetomidine promotes colorectal cancer progression via Piwil2 signaling

PURPOSE

α2-adrenoceptor agonist dexmedetomidine (DEX) has been reported to promote tumorigenesis. Stem-cell protein Piwil2 is associated with cancer progression. Whether Piwil2 plays a role in tumor-promoting effects of DEX is unknown.

METHODS

We examined the expression of Piwil2 in human colorectal cancer (CRC) cell lines with/without DEX treatment. We also studied the roles of Piwil2 in proliferation, invasion, migration, as well as expressions of epithelial-mesenchymal transition (EMT)-related proteins in DEX-treated in vitro and in vivo CRC models. And the experiments with genetic and pharmacological treatments were conducted to investigate the underlying molecular mechanism.

RESULTS

RNA-sequencing (RNA-seq) analysis found Piwil2 is one of most upregulated genes upon DEX treatment in CRC cells. Furthermore, Piwil2 protein levels significantly increased in DEX-treated CRC cancer cells, which promoted proliferation, invasion, and migration in both CRC cell lines and human tumor xenografts model. Mechanistically, DEX increased nuclear factor E2-related factor 2 (Nrf2) expression, which enhanced Piwil2 transcription via binding to its promoter. Furthermore, in vitro experiments with Piwil2 knockdown or Siah2 inhibition indicated that DEX promoted EMT process and tumorigenesis through Siah2/PHD3/HIF1α pathway. The experiments with another α2-adrenoceptor agonist Brimonidine and antagonists yohimbine and atipamezole also suggested the role of Piwil2 signaling in tumor-promoting effects via an α2 adrenoceptor-dependent manner.

CONCLUSION

DEX promotes CRC progression may via activating α2 adrenoceptor-dependent Nrf2/Piwil2/Siah2 pathway and thus EMT process. Our work provides a novel insight into the mechanism underlying tumor-promoting effects of α2-adrenoceptor agonists.

Neuroinflammation in Neurodegenerative Disorders: Current Knowledge and Therapeutic Implications

Neurodegenerative disorders (NDs) have become increasingly common during the past three decades. Approximately 15% of the total population of the world is affected by some form of NDs, resulting in physical and cognitive disability. The most common NDs include Alzheimer's disease, Parkinson's disease, amyotrophic lateral sclerosis, and Huntington's disease. Although NDs are caused by a complex interaction of genetic, environmental, and lifestyle variables, neuroinflammation is known to be associated with all NDs, often leading to permanent damage to neurons of the central nervous system. Furthermore, numerous emerging pieces of evidence have demonstrated that inflammation not only supports the progression of NDs but can also serve as an initiator. Hence, various medicines capable of preventing or reducing neuroinflammation have been investigated as ND treatments. While anti-inflammatory medicine has shown promising benefits in several preclinical models, clinical outcomes are often questionable. In this review, we discuss various NDs with their current treatment strategies, the role of neuroinflammation in the pathophysiology of NDs, and the use of anti-inflammatory agents as a potential therapeutic option.

Imaging flow cytometry of tumoroids: A new method for studying GPCR expression

Fluorescence confocal microscopy is commonly used to analyze the regulation membrane proteins expression such as G protein-coupled receptors (GPCRs). With this approach, the internal movement of GPCRs within the cell can be observed with a high degree of resolution. However, these microscopy techniques led to complex and time-consuming analysis and did not allow a large population of events to be sampled. A recent approach termed imaging flow cytometry (IFC), which combines flow cytometry and fluorescence microscopy, had two main advantages to study the regulation of GPCRs expression such as orexins receptors (OXRs): the ability (1) to analyze large numbers of cells and; (2) to visualize cell integrity and fluorescent markers localization. Here, we compare these two technologies using the orexin A (OxA) ligand coupled to rhodamine (OxA-rho) to investigate anti-tumoral OX1R expression in human digestive cancers. IFC has been adapted for cancer epithelial adherent cells and also to 3D cell culture tumoroids which partially mimic tumoral structures. In the absence of specific antibody, expression of OX1R is examined in the presence of OxA-rho. 2D-culture of colon cancer cells HT-29 exhibits a maximum level of OX1R internalization induced by OxA with 19% ± 3% colocalizing to early endosomes. In 3D-culture of HT-29 cells, internalization of OX1R/OxA-rho reached its maximum at 60 min, with 30.7% ± 6.4% of OX1R colocalizing with early endosomes. This is the first application of IFC to the analysis of the expression of a native GPCR, OX1R, in both 2D and 3D cultures of adherent cancer cells.

ADAM19 cleaves the PTH receptor and associates with brachydactyly type E

Brachydactyly type E (BDE), shortened metacarpals, metatarsals, cone-shaped epiphyses, and short stature commonly occurs as a sole phenotype. Parathyroid hormone-like protein (PTHrP) has been shown to be responsible in all forms to date, either directly or indirectly. We used linkage and then whole genome sequencing in a small pedigree, to elucidate BDE and identified a truncated disintegrin-and-metalloproteinase-19 (ADAM19) allele in all affected family members, but not in nonaffected persons. Since we had shown earlier that the extracellular domain of the parathyroid hormone receptor (PTHR1) is subject to an unidentified metalloproteinase cleavage, we tested the hypothesis that ADAM19 is a sheddase for PTHR1. WT ADAM19 cleaved PTHR1, while mutated ADAM-19 did not. We mapped the cleavage site that we verified with mass spectrometry between amino acids 64-65. ADAM-19 cleavage increased Gq and decreased Gs activation. Moreover, perturbed PTHR1 cleavage by ADAM19 increased ß-arrestin2 recruitment, while cAMP accumulation was not altered. We suggest that ADAM19 serves as a regulatory element for PTHR1 and could be responsible for BDE. This sheddase may affect other PTHrP or PTH-related functions.

PACAP key interactions with PAC1, VPAC1, and VPAC2 identified by molecular dynamics simulations

The neuropeptide pituitary adenylate cyclase-activating polypeptide (PACAP) belongs to the glucagon/secretin family. PACAP interacts with the pituitary adenylate cyclase-activating polypeptide receptor type 1 (PAC1) and vasoactive intestinal peptide receptors 1 and 2 (VPAC1 and VPAC2), exhibiting functions in the immune, endocrine, and nervous systems. This peptide is upregulated in numerous instances of brain injury, acting as a neuroprotective agent. It can also suppress HIV-1 and SARS-CoV-2 viral replication in vitro. This work aimed to identify, in each peptide-receptor system, the most relevant residues for complex stability and interaction energy communication via Molecular Dynamics (MD), Free Energy calculations, and Protein-energy networks, thus revealing in detail the underlying mechanisms of activation of these receptors. Hydrogen bond formation, interaction energies, and computational alanine scanning between PACAP and its receptors showed that His1, Asp3, Arg12, Arg14, and Lys15 are crucial to the peptide's stability. Furthermore, several PACAP interactions with structurally conserved positions deemed necessary in GPCR B1 activation, including Arg2.60, Lys2.67, and Glu7.42, were significant for the peptide's stability within the receptors. According to the protein-energy network, the connection between Asp3 of PACAP and the receptors' conserved Arg2.60 represents a critical energy communication hub in all complexes. Additionally, the ECDs of the receptors were also found to function as energy communication hubs for PACAP. Although the overall binding mode of PACAP in the three receptors was found to be highly conserved, Arg12 and Tyr13 of PACAP were more prominent in complex with PAC1, while Ser2 of PACAP was with VPAC2. The detailed analyses performed in this work pave the way for using PACAP and its receptors as therapeutic targets.Communicated by Ramaswamy H. Sarma.

G protein-coupled receptor (GPCR) gene variants and human genetic disease

Genetic variations in the genes encoding G protein-coupled receptors (GPCRs) can disrupt receptor structure and function, which can result in human genetic diseases. Disease-causing mutations have been reported in at least 55 GPCRs for more than 66 monogenic diseases in humans. The spectrum of pathogenic and likely pathogenic variants includes loss of function variants that decrease receptor signaling on one extreme and gain of function that may result in biased signaling or constitutive activity, originally modeled on prototypical rhodopsin GPCR variants identified in retinitis pigmentosa, on the other. GPCR variants disrupt ligand binding, G protein coupling, accessory protein function, receptor desensitization and receptor recycling. Next generation sequencing has made it possible to identify variants of uncertain significance (VUS). We discuss variants in receptors known to result in disease and in silico strategies for disambiguation of VUS such as sorting intolerant from tolerant and polymorphism phenotyping. Modeling of variants has contributed to drug development and precision medicine, including drugs that target the melanocortin receptor in obesity and interventions that reverse loss of gonadotropin-releasing hormone receptor from the cell surface in idiopathic hypogonadotropic hypogonadism. Activating and inactivating variants of the calcium sensing receptor (CaSR) gene that are pathogenic in familial hypocalciuric hypercalcemia and autosomal dominant hypocalcemia have enabled the development of calcimimetics and calcilytics. Next generation sequencing has continued to identify variants in GPCR genes, including orphan receptors, that contribute to human phenotypes and may have therapeutic potential. Variants of the CaSR gene, some encoding an arginine-rich region that promotes receptor phosphorylation and intracellular retention, have been linked to an idiopathic epilepsy syndrome. Agnostic strategies have identified variants of the pyroglutamylated RF amide peptide receptor gene in intellectual disability and G protein-coupled receptor 39 identified in psoriatic arthropathy. Coding variants of the G protein-coupled receptor L1 (GPR37L1) orphan receptor gene have been identified in a rare familial progressive myoclonus epilepsy. The study of the role of GPCR variants in monogenic, Mendelian phenotypes has provided the basis of modeling the significance of more common variants of pharmacogenetic significance.

Identification of potential immunotherapeutic targets and prognostic biomarkers in Graves' disease using weighted gene co-expression network analysis

Graves' disease (GD) is an autoimmune disorder characterized by hyperthyroidism resulting from autoantibody-induced stimulation of the thyroid gland. Despite recent advancements in understanding GD's pathogenesis, the molecular processes driving disease progression and treatment response remain poorly understood. In this study, we aimed to identify crucial immunogenic factors associated with GD prognosis and immunotherapeutic response. To achieve this, we implemented a comprehensive screening strategy that combined computational immunogenicity-potential scoring with multi-parametric cluster analysis to assess the immunomodulatory genes in GD-related subtypes involving stromal and immune cells. Utilizing weighted gene co-expression network analysis (WGCNA), we identified co-expressed gene modules linked to cellular senescence and immune infiltration in CD4+ and CD8+ GD samples. Additionally, gene set enrichment analysis enabled the identification of hallmark pathways distinguishing high- and low-immune subtypes. Our WGCNA analysis revealed 21 gene co-expression modules comprising 1,541 genes associated with immune infiltration components in various stages of GD, including T cells, M1 and M2 macrophages, NK cells, and Tregs. These genes primarily participated in T cell proliferation through purinergic signaling pathways, particularly neuroactive ligand-receptor interactions, and DNA binding transcription factor activity. Three genes, namely PRSS1, HCRTR1, and P2RY4, exhibited robustness in GD patients across multiple stages and were involved in immune cell infiltration during the late stage of GD (p < 0.05). Importantly, HCRTR1 and P2RY4 emerged as potential prognostic signatures for predicting overall survival in high-immunocore GD patients (p < 0.05). Overall, our study provides novel insights into the molecular mechanisms driving GD progression and highlights potential key immunogens for further investigation. These findings underscore the significance of immune infiltration-related cellular senescence in GD therapy and present promising targets for the development of new immunotherapeutic strategies.

Direct interrogation of context-dependent GPCR activity with a universal biosensor platform

G protein-coupled receptors (GPCRs) are the largest family of druggable proteins encoded in the human genome, but progress in understanding and targeting them is hindered by the lack of tools to reliably measure their nuanced behavior in physiologically relevant contexts. Here, we developed a collection of compact ONE vector G-protein Optical (ONE-GO) biosensor constructs as a scalable platform that can be conveniently deployed to measure G-protein activation by virtually any GPCR with high fidelity even when expressed endogenously in primary cells. By characterizing dozens of GPCRs across many cell types like primary cardiovascular cells or neurons, we revealed insights into the molecular basis for G-protein coupling selectivity of GPCRs, pharmacogenomic profiles of anti-psychotics on naturally occurring GPCR variants, and G-protein subtype signaling bias by endogenous GPCRs depending on cell type or upon inducing disease-like states. In summary, this open-source platform makes the direct interrogation of context-dependent GPCR activity broadly accessible.

Protein Kinase A in neurological disorders

Cyclic adenosine 3', 5' monophosphate (cAMP)-dependent Protein Kinase A (PKA) is a multi-functional serine/threonine kinase that regulates a wide variety of physiological processes including gene transcription, metabolism, and synaptic plasticity. Genomic sequencing studies have identified both germline and somatic variants of the catalytic and regulatory subunits of PKA in patients with metabolic and neurodevelopmental disorders. In this review we discuss the classical cAMP/PKA signaling pathway and the disease phenotypes that result from PKA variants. This review highlights distinct isoform-specific cognitive deficits that occur in both PKA catalytic and regulatory subunits, and how tissue-specific distribution of these isoforms may contribute to neurodevelopmental disorders in comparison to more generalized endocrine dysfunction.

The wake and sleep-modulating neurons of the lateral hypothalamic area demonstrate a differential pattern of degeneration in Alzheimer's disease

Background

Sleep-wake dysfunction is an early and common event in Alzheimer's disease (AD). The lateral hypothalamic area (LHA) regulates the sleep and wake cycle through wake-promoting orexinergic and sleep-promoting melanin-concentrating hormone (MCH) neurons. These neurons share close anatomical proximity with functional reciprocity. This study investigated the pattern of neuronal loss (ORX and MCH) in the LHA in AD. Understanding the degeneration pattern of these neurons will be instrumental in designing potential therapeutics to slow down the disease progression and remediate the sleep-wake dysfunction in AD.

Methods

Postmortem human brain tissue of subjects with AD (across progressive stages) and controls were examined using unbiased stereology. Neuronal counting was done using double immunohistochemistry with ORX, pTau (CP13), and MCH, pTau (CP13) labeled neurons on formalin-fixed, celloidin-embedded tissue.

Results

We observed a progressive decline in orexinergic (ORX) neurons and a relative preservation of the melanin-concentrating hormone (MCH) neurons. The decline in ORX neurons was seen from BB 2 (56%, p=0.0634). By the late stage of the disease (BB 5-6), the decline in ORX neurons was 76% (p=0.0043). In contrast, the MCH neurons demonstrated an insignificant decline by BB 6 (25%, p=0.1313).

Conclusions

Our data demonstrated very early substantial ORX neuronal loss in the LHA, while MCH neurons were resilient to AD pTau accumulation. Interventions capable of preventing ORX neuronal loss and inhibiting pTau accumulation in the LHA can reinstate sleep-wake dysfunction in AD and possibly prevent the progression of the disease.

Cluster headache: an update on clinical features, epidemiology, pathophysiology, diagnosis, and treatment

Cluster headache (CH) is one of the worst primary headaches that remain underdiagnosed and inappropriately treated. There are recent advances in the understanding of this disease and available treatments. This paper aims to review CH's recent clinical and pathophysiological findings, diagnosis, and treatment. We performed a narrative literature review on the socio-demographics, clinical presentations, pathophysiological findings, and diagnosis and treatment of CH. CH affects 0.1% of the population with an incidence of 2.07-9.8/100,00 person-years-habitants, a mean prevalence of 53/100,000 inhabitants (3-150/100,000 inhabitants). The male-to-female ratio remains inconclusive, as the ratio of 4.3:1 has recently been modified to 1.3-2.6, possibly due to previous misdiagnosis in women. Episodic presentation is the most frequent (80%). It is a polygenetic and multifactorial entity that involves dysfunction of the trigeminovascular system, the trigeminal autonomic reflex, and the hypothalamic networks. An MRI of the brain is mandatory to exclude secondary etiologies. There are effective and safe pharmacological treatments oxygen, sphenopalatine, and great occipital nerve block, with the heterogeneity of clinical trial designs for patients with CH divided into acute, transitional, or bridge treatment (prednisone) and preventive interventions. In conclusion, CH remains underdiagnosed, mainly due to a lack of awareness within the medical community, frequently causing a long delay in reaching a final diagnosis. Recent advances in understanding the principal risk factors and underlying pathophysiology exist. There are new therapeutic possibilities that are effective for CH. Indeed, a better understanding of this challenging pathology will continue to be a subject of research, study, and discoveries in its diagnostic and therapeutic approach.

Non-canonical G protein signaling

The original paradigm of classical - also referred to as canonical - cellular signal transduction of heterotrimeric G proteins (G protein) is defined by a hierarchical, orthograde interaction of three players: the agonist-activated G protein-coupled receptor (GPCR), which activates the transducing G protein, that in turn regulates its intracellular effectors. This receptor-transducer-effector concept was extended by the identification of regulators and adapters such as the regulators of G protein signaling (RGS), receptor kinases like βARK, or GPCR-interacting arrestin adapters that are integrated into this canonical signaling process at different levels to enable fine-tuning. Finally, the identification of atypical signaling mechanisms of classical regulators, together with the discovery of novel modulators, added a new and fascinating dimension to the cellular G protein signal transduction. This heterogeneous group of accessory G protein modulators was coined "activators of G protein signaling" (AGS) proteins and plays distinct roles in canonical and non-canonical G protein signaling pathways. AGS proteins contribute to the control of essential cellular functions such as cell development and division, intracellular transport processes, secretion, autophagy or cell movements. As such, they are involved in numerous biological processes that are crucial for diseases, like diabetes mellitus, cancer, and stroke, which represent major health burdens. Although the identification of a large number of non-canonical G protein signaling pathways has broadened the spectrum of this cellular communication system, their underlying mechanisms, functions, and biological effects are poorly understood. In this review, we highlight and discuss atypical G protein-dependent signaling mechanisms with a focus on inhibitory G proteins (Gi) involved in canonical and non-canonical signal transduction, review recent developments and open questions, address the potential of new approaches for targeted pharmacological interventions.

Targeting the PACAP-38 pathway is an emerging therapeutic strategy for migraine prevention

INTRODUCTION

The pituitary adenylate cyclase-activating polypeptide-38 (PACAP-38) has emerged as a key mediator of migraine pathogenesis. PACAP-38 and its receptors are predominantly distributed in arteries, sensory and parasympathetic neurons of the trigeminovascular system. Phase 2 trials have tested human monoclonal antibodies designed to bind and inhibit PACAP-38 and the pituitary adenylate cyclase-activating polypeptide type I (PAC1) receptor for migraine prevention.

AREAS COVERED

This review focuses on the significance of the PACAP-38 pathway as a target in migraine prevention. English peer-reviewed articles were searched in PubMed, Scopus and ClinicalTrials.gov electronic databases.

EXPERT OPINION

A PAC1 receptor monoclonal antibody was not effective for preventing migraine in a proof-of-concept trial, paving the way for alternative strategies to be considered. Lu AG09222 is a humanized monoclonal antibody targeting PACAP-38 that was effective in preventing physiological responses of PACAP38 and reducing monthly migraine days in individuals with migraine. Further studies are necessary to elucidate the clinical utility, long-term safety and cost-effectiveness of therapies targeting the PACAP pathway.

Dynamic morphometric changes in the mandibular osteocytic lacunae of ovariectomized rats in response to teriparatide, as revealed by three-dimensional fluorescence analyses: Possible involvement of osteocytic perilacunar remodeling

OBJECTIVES

Teriparatide [TPTD; human parathyroid hormone (hPTH1-34)] is an anti-osteoporotic drug with bone anabolic effects. Clinical and preclinical studies have indicated that TPTD has value in oral and maxillofacial bone therapies, including jawbone regeneration, periodontal tissue repair, and the treatment of medication-related osteonecrosis of the jaw. However, it is unclear whether the craniofacial bones respond to TPTD similarly to the axial and appendicular bones. Recent studies showed that TPTD acts on both osteocytes and osteoblasts. This study aimed to characterize distinct craniofacial bone sites, with a focus on morphometric changes in osteocytic lacunae in ovariectomized rats receiving TPTD.

METHODS

Conventional bone histomorphometric analyses of mandibular and parietal bone sections were conducted. High-resolution confocal imaging-based three-dimensional fluorescence morphometric analyses of osteocytic lacunae in distinct mandibular and parietal bone sites were conducted.

RESULTS

We observed dynamic changes in the morphometric characteristics of osteocytic lacunae specifically in alveolar and other mandibular bone sites upon TPTD administration.

CONCLUSIONS

These findings suggest that osteocytes in mandibular bone (specifically, alveolar bone) have unique functional characteristics of osteocytic perilacunar remodeling.

Serum amyloid A expression in liver promotes synovial macrophage activation and chronic arthritis via NFAT5

Nuclear factor of activated T-cells 5 (NFAT5), an osmo-sensitive transcription factor, can be activated by isotonic stimuli, such as infection. It remains unclear, however, whether NFAT5 is required for damage-associated molecular pattern-triggered (DAMP-triggered) inflammation and immunity. Here, we found that several DAMPs increased NFAT5 expression in macrophages. In particular, serum amyloid A (SAA), primarily generated by the liver, substantially upregulated NFAT5 expression and activity through TLR2/4-JNK signalling pathway. Moreover, the SAA-TLR2/4-NFAT5 axis promoted migration and chemotaxis of macrophages in an IL-6- and chemokine ligand 2-dependent (CCL2-dependent) manner in vitro. Intraarticular injection of SAA markedly accelerated macrophage infiltration and arthritis progression in mice. By contrast, genetic ablation of NFAT5 or TLR2/4 rescued the pathology induced by SAA, confirming the SAA-TLR2/4-NFAT5 axis in vivo. Myeloid-specific depletion of NFAT5 also attenuated SAA-accelerated arthritis. Of note, inflammatory arthritis in mice strikingly induced SAA overexpression in the liver. Conversely, forced overexpression of the SAA gene in the liver accelerated joint damage, indicating that the liver contributes to bolstering chronic inflammation at remote sites by secreting SAA. Collectively, this study underscores the importance of the SAA-TLR2/4-NFAT5 axis in innate immunity, suggesting that acute phase reactant SAA mediates mutual interactions between liver and joints and ultimately aggravates chronic arthritis by enhancing macrophage activation.

The role of immune system in atherosclerosis: Molecular mechanisms, controversies, and future possibilities

Numerous cardiovascular disorders have atherosclerosis as their pathological underpinning. Numerous studies have demonstrated that, with the aid of pattern recognition receptors, cytokines, and immunoglobulins, innate immunity, represented by monocytes/macrophages, and adaptive immunity, primarily T/B cells, play a critical role in controlling inflammation and abnormal lipid metabolism in atherosclerosis. Additionally, the finding of numerous complement components in atherosclerotic plaques suggests yet again how heavily the immune system controls atherosclerosis. Therefore, it is essential to have a thorough grasp of how the immune system contributes to atherosclerosis. The specific molecular mechanisms involved in the activation of immune cells and immune molecules in atherosclerosis, the controversy surrounding some immune cells in atherosclerosis, and the limitations of extrapolating from relevant animal models to humans were all carefully reviewed in this review from the three perspectives of innate immunity, adaptive immunity, and complement system. This could provide fresh possibilities for atherosclerosis research and treatment in the future.

The role of orexin in Parkinson's disease

Emerging evidence has implicated the orexin system in non-motor pathogenesis of Parkinson's disease. It has also been suggested the orexin system is involved in the modulation of motor control, further implicating the orexin system in Parkinson's disease. Parkinson's disease is the second most common neurodegenerative disease with millions of people suffering worldwide with motor and non-motor symptoms, significantly affecting their quality of life. Treatments are based solely on symptomatic management and no cure currently exists. The orexin system has the potential to be a treatment target in Parkinson's disease, particularly in the non-motor stage. In this review, the most current evidence on the orexin system in Parkinson's disease and its potential role in motor and non-motor symptoms of the disease is summarized. This review begins with a brief overview of Parkinson's disease, animal models of the disease, and the orexin system. This leads into discussion of the possible roles of orexin neurons in Parkinson's disease and levels of orexin in the cerebral spinal fluid and plasma in Parkinson's disease and animal models of the disease. The role of orexin is then discussed in relation to symptoms of the disease including motor control, sleep, cognitive impairment, psychological behaviors, and the gastrointestinal system. The neuroprotective effects of orexin are also summarized in preclinical models of the disease.

Elevated CD169 expressing monocyte/macrophage promotes systemic inflammation and disease progression in cirrhosis

Systemic inflammation is related to disease progression and prognosis in patients with advanced cirrhosis. However, the mechanisms underlying the initiation of inflammation are still not fully understood. The role of CD169+ monocyte/macrophage in cirrhotic systemic inflammation was undetected. Flow cytometry analysis was used to detect the percentage and phenotypes of CD169+ monocytes as well as their proinflammatory function in patient-derived cirrhotic tissue and blood. Transcriptome differences between CD169+ and CD169- monocytes were also compared. Additionally, a mouse model with specific depletion of CD169+ monocytes/macrophages was utilized to define their role in liver injury and fibrosis. We observed increased CD169 expression in monocytes from cirrhotic patients, which was correlated with inflammatory cytokine production and disease progression. CD169+ monocytes simultaneously highly expressed M1- and M2-like markers and presented immune-activated profiles. We also proved that CD169+ monocytes robustly prevented neutrophil apoptosis. Depletion of CD169+ monocytes/macrophages significantly inhibited inflammation and liver necrosis in acute liver injury, but the spontaneous fibrin resolution after repeated liver injury was impaired. Our results indicate that CD169 defines a subset of inflammation-associated monocyte that correlates with disease development in patients with cirrhosis. This provides a possible therapeutic target for alleviating inflammation and improving survival in cirrhosis.

Orexins/Hypocretins: Gatekeepers of Social Interaction and Motivation

Ever since the discovery of the brain's orexin/hypocretin system, most research was directed toward unveiling its contribution to the normal functioning of individuals. The investigation of reward-seeking behaviors then gained a lot of attention once the distribution of orexinergic neurons was revealed. Here, we discuss findings on the involvement of orexins in social interaction, a natural reward type. While some studies have succeeded in defining the relationship between orexin and social interaction, the controversy regarding its nature (direct or inverse relation) raises questions about what aspects have been overlooked until now. Upon examining the literature, we identified a research gap concerning conditions influencing the impact of orexins on social behavior expression. In this review, we introduce a number of factors (e.g., stress, orexin's source) that must be considered while studying the role of orexins in social interaction. Furthermore, we refer to published research to investigate the stage at which orexins affect social interaction and we highlight the nucleus accumbens (NAc) shell's role in social interaction and other rewarding behaviors. Finally, the underlying orexin molecular pathway influencing social motivation in particular illnesses is proposed. We conclude that orexin's impact on social interaction is multifactorial and depends on specific conditions available at a time.

Orexin-A alleviates ferroptosis by activating the Nrf2/HO-1 signaling pathway in traumatic brain injury

BACKGROUND

Traumatic Brain Injury (TBI) has high disability and mortality rate. Oxidative stress and ferroptosis are important pathophysiological characteristics after TBI. Orexin-A (OXA) can alleviate neuronal damage in diverse neurological disorders. Nevertheless, the role and mechanism of OXA in TBI stay unknown.

OBJECTIVES

The research investigated protection influence of OXA on TBI and its potential mechanisms.

METHODS

Male Sprague-Dawley rats were randomly grouped into: sham, TBI, TBI + normal saline (NS) and TBI+OXA groups. TBI model was constructed in rat via modified Feeney's approach, and OXA treatment was administered following construction of TBI model.

RESULTS

Relative to TBI+NS group, TBI+OXA group displayed greatly recovered tissue damage and neurological deficits. Additionally, OXA eased oxidative stress as well as ferroptosis in cerebral cortex of rats following TBI. Furthermore, OXA increased Nrf2 expression and regulating factors HO-1 and NQO1 in cerebral cortex of TBI rats.

CONCLUSIONS

Our research found OXA may restrain ferroptosis via Nrf2/HO-1 signaling pathway activation, thereby reducing brain injury after TBI.

The airway neuro-immune axis as a therapeutic target in allergic airway diseases

Recent evidence has increasingly underscored the importance of the neuro-immune axis in mediating allergic airway diseases, such as allergic asthma and allergic rhinitis. The intimate spatial relationship between neurons and immune cells suggests that their interactions play a pivotal role in regulating allergic airway inflammation. Upon direct activation by allergens, neurons and immune cells engage in interactions, during which neurotransmitters and neuropeptides released by neurons modulate immune cell activity. Meanwhile, immune cells release inflammatory mediators such as histamine and cytokines, stimulating neurons and amplifying neuropeptide production, thereby exacerbating allergic inflammation. The dynamic interplay between the nervous and immune systems suggests that targeting the neuro-immune axis in the airway could represent a novel approach to treating allergic airway diseases. This review summarized recent evidence on the nervous system's regulatory mechanisms in immune responses and identified potential therapeutic targets along the peripheral nerve-immune axis for allergic asthma and allergic rhinitis. The findings will provide novel perspectives on the management of allergic airway diseases in the future.

C-terminal peptide of preproorexin enhances brain-derived neurotrophic factor expression in rat cerebrocortical cells and recognition memory in mice

During the production of orexin A and B from preproorexin, a common precursor protein, in hypothalamic orexin neurons, C-terminal peptide (herein called preproorexin C-peptide) is concomitantly produced via post-translational processing. The predicted three-dimensional structure of preproorexin C-peptide is similar among mammalian species, suggestive of a conserved function in the mammalian brain. However, C-peptide has long been regarded as a non-functional peptide. We herein examined the effects of rat and/or mouse preproorexin C-peptide on gene expression and cell viability in cultured rat cerebrocortical cells and on memory behavior in C57BL/6J mice. Rat and mouse C-peptides both increased brain-derived neurotrophic factor (Bdnf) mRNA levels. Moreover, C-peptide enhanced high K+-, glutamate-, and BDNF-induced increases in Bdnf mRNA levels without affecting forskolin-induced Bdnf expression. H-89, a protein kinase A inhibitor, blocked C-peptide-induced Bdnf expression, whereas rolipram, a phosphodiesterase inhibitor, enhanced this effect. Intracellular cyclic AMP concentrations were elevated by C-peptide. These results demonstrate that preproorexin C-peptide promoted Bdnf mRNA expression by a cyclic AMP-dependent mechanism. Eleven amino acids at the N terminus of rat preproorexin C-peptide exerted similar effects on Bdnf expression as full-length preproorexin C-peptide. Preproorexin C-peptide also exerted protective effects against CoCl2-induced neuronal cell death. An intracerebroventricular injection of mouse preproorexin C-peptide induced c-fos and Bdnf expression in the cerebral cortex and hippocampus and enhanced novel object recognition memory in mice. Collectively, the present results show that preproorexin C-peptide is a functional substance, at least in some pharmacological and neuronal settings.

The role of orexin in fatigue and sleep quality in patients with primary Sjögren's syndrome

BACKGROUND

Sleep disorders and fatigue are prevalent symptoms affecting primary Sjögren's syndrome (pSS) patients. This study aimed to assess the sleep quality of pSS patients as well as its relationship to fatigue and orexin level.

METHODS

This is a cross-sectional study evaluating fatigue in pSS using the Fatigue Severity Scale (FSS). Sleep quality was evaluated using the Pittsburg Sleep Quality Index (PSQI). The European Alliance of Associations for Rheumatology (EULAR) Sjögren's Syndrome Disease Activity Index (ESSDAI) and EULAR Sjögren's Syndrome Patient-Reported Index (ESSPRI) were calculated.

RESULTS

Forty-one patients met the sample criteria and were involved in the final report. They were all females, with a mean (± SD) age and median disease duration of 40.87 ± 10.84 and 36 (6-180) months, respectively. The mean ESSDAI was 0.92 ± 1.3, while the mean ESSPRI was 5.8 ± 2.13. Based on the FSS, 32 (78.04%) patients had a positive test with a mean score of 5.07 ± 1.54. The total PSQI score showed that 60.97% had poor sleep, and the orexin level was lower in patients with pSS than in healthy controls. There was no correlation between orexin level and the presence of fatigue nor the PSQI score.

CONCLUSION

In conclusion, serum orexin levels were lower in patients with pSS than healthy controls, It could be related to impairments in sleep and fatigue in patients with pSS.

Endosomal signaling via cAMP in parathyroid hormone (PTH) type 1 receptor biology

Compartmentalization of GPCR signaling is an emerging topic that highlights the physiological relevance of spatial bias in signaling. The parathyroid hormone (PTH) type 1 receptor (PTH1R) was the first GPCR described to signal via heterotrimeric G-protein and cAMP from endosomes after β-arrestin mediated internalization, challenging the canonical GPCR signaling model which established that signaling is terminated by receptor internalization. More than a decade later, many other GPCRs have been shown to signal from endosomes via cAMP, and recent studies have proposed that location of cAMP generation impacts physiological outcomes of GPCR signaling. Here, we review the extensive literature regarding PTH1R endosomal signaling via cAMP, the mechanisms that regulate endosomal generation of cAMP, and the implications of spatial bias in PTH1R physiological functions.

Synthesis and Characterization of a New Carbon-11 Labeled Positron Emission Tomography Radiotracer for Orexin 2 Receptors Neuroimaging

Purpose

Orexin receptors (OXRs) play a crucial role in modulating various physiological and neuropsychiatric functions within the central nervous system (CNS). Despite their significance, the precise role of OXRs in the brain remains elusive. Positron emission tomography (PET) imaging is instrumental in unraveling CNS functions, and the development of specific PET tracers for OXRs is a current research focus.

Methods

The study investigated MDK-5220, an OX2R-selective agonist with promising binding properties (EC50 on OX2R: 0.023 μM, Ki on hOX2R: 0.14 μM). Synthesized and characterized as an OX2R PET probe, [11C]MDK-5220 was evaluated for its potential as a tracer. Biodistribution studies in mice were conducted to assess OX2R binding selectivity, with particular attention to its interaction with P-glycoprotein (P-gp) on the blood-brain barrier.

Results

[11C]MDK-5220 exhibited promising attributes as an OX2R PET probe, demonstrating robust OX2R binding selectivity in biodistribution studies. However, an observed interaction with P-gp impacted its brain uptake. Despite this limitation, [11C]MDK-5220 presents itself as a potential candidate for further development.

Discussion

The study provides insights into the functionality of the OX system and the potential of [11C]MDK-5220 as an OX2R PET probe. The observed interaction with P-gp highlights a consideration for future modifications to enhance brain uptake. The findings pave the way for innovative tracer development and propel ongoing research on OX systems, contributing to a deeper understanding of their role in the CNS.

Conclusion

[11C]MDK-5220 emerges as a promising OX2R PET probe, despite challenges related to P-gp interaction. This study lays the foundation for further exploration and development of PET probes targeting OXRs, opening avenues for advancing our understanding of OX system functionality within the brain.

Unveiling Colitis: A Journey through the Dextran Sodium Sulfate-induced Model

Animal models of inflammatory bowel disease (IBD) are valuable tools for investigating the factors involved in IBD pathogenesis and evaluating new therapeutic options. The dextran sodium sulfate (DSS)-induced model of colitis is arguably the most widely used animal model for studying the pathogenesis of and potential treatments for ulcerative colitis (UC), which is a primary form of IBD. This model offers several advantages as a research tool: it is highly reproducible, relatively easy to generate and maintain, and mimics many critical features of human IBD. Recently, it has also been used to study the role of gut microbiota in the development and progression of IBD and to investigate the effects of other factors, such as diet and genetics, on colitis severity. However, although DSS-induced colitis is the most popular and flexible model for preclinical IBD research, it is not an exact replica of human colitis, and some results obtained from this model cannot be directly applied to humans. This review aims to comprehensively discuss different factors that may be involved in the pathogenesis of DSS-induced colitis and the issues that should be considered when using this model for translational purposes.

Investigation of PACAP38 and PAC1 Receptor Expression in Human Retinoblastoma and the Effect of PACAP38 Administration on Human Y-79 Retinoblastoma Cells

Retinoblastoma represents the most prevalent malignant neoplasm affecting the eyes in childhood. The clear-cut origin of retinoblastoma has not yet been determined; however, based on experiments, it has been suggested that RB1 loss in cone photoreceptors causes retinoblastoma. Pituitary adenylate-cyclase activating polypeptide (PACAP) is a pleiotropic neuropeptide which has been shown to be affected in certain tumorous transformations, such as breast, lung, kidney, pancreatic, colon, and endocrine cancers. This study aimed to investigate potential changes in both PACAP38 and PAC1 receptor (PAC1R) expression in human retinoblastoma and the effect of PACAP38 administration on the survival of a human retinoblastoma cell line (Y-79). We analyzed human enucleation specimens removed because of retinoblastoma for PACAP38 and PAC1R immunostaining and the effect of PACAP38 on the survival of the Y-79 cell line. We described for the first time that human retinoblastoma cells from patients showed only perinuclear, dot-like immunopositivity for both PACAP38 and PAC1R, irrespective of laterality, genetic background, or histopathological features. Nanomolar (100 nM and 500 nM) PACAP38 concentrations had no effect on the viability of Y-79 cells, while micromolar (2 µM and 6 µM) PACAP38 significantly decreased tumor cell viability. These findings, along with general observations from animal studies showing that PACAP38 has strong anti-apoptotic, anti-inflammatory, and antioxidant effects on ocular tissues, together suggest that PACAP38 and its analogs are promising candidates in retinoblastoma therapy.

Methyl Jasmonate Modulates Feeding Behaviors and Hypothalamic Expression of the Orexin 1 Receptor in Rats

Objectives

Active plant ingredients have been successfully used in modern medicine to control appetite and energy hemostasis. This study was designed to evaluate the efficacy of the phytohormone methyl jasmonate (MJ) on food-related behaviors in rats.

Materials and Methods

Adult male Wistar rats were randomly divided into different groups (7 rats) and infused intracerebroventricularly (i.c.v.) with MJ vehicle (DMSO) or MJ (2.5, 5 and 10 μg/rat). Then, the individual rats were placed in an automated open field-like apparatus to assess a 12-h food-related activity in light and dark times. After behavioral tests, immunofluorescence staining of the orexin 1 receptor (Orx1R) was studied in the hypothalamus of rats.

Results

MJ (2.5, 5, and 10 μg/rat) administration significantly decreased food intake in the light and dark phases compared with the control group. Moreover, all the MJ-treated groups exhibited a decrease in visits to food containers at the light and dark times (p < 0.001). In addition, rats infused with MJ at 5 μg and 10 μg spent less time in the ports of food containers in the light and dark phases in comparison with control rats. Time in zone-related to food and locomotor activity was significantly decreased in the MJ (5 μg) groups during the light time and in all MJ-injected groups in the dark time. Moreover, hypothalamic expression of Orx1R in rats treated with MJ (5 μg) was significantly lower as compared to the control group.

Conclusion

Overall, the results indicated the potential of MJ to modulate feeding-related behavior and Orx1R expression in the hypothalamus of rats.

The Healthy and Diseased Retina Seen through Neuron-Glia Interactions

The retina is the sensory tissue responsible for the first stages of visual processing, with a conserved anatomy and functional architecture among vertebrates. To date, retinal eye diseases, such as diabetic retinopathy, age-related macular degeneration, retinitis pigmentosa, glaucoma, and others, affect nearly 170 million people worldwide, resulting in vision loss and blindness. To tackle retinal disorders, the developing retina has been explored as a versatile model to study intercellular signaling, as it presents a broad neurochemical repertoire that has been approached in the last decades in terms of signaling and diseases. Retina, dissociated and arranged as typical cultures, as mixed or neuron- and glia-enriched, and/or organized as neurospheres and/or as organoids, are valuable to understand both neuronal and glial compartments, which have contributed to revealing roles and mechanisms between transmitter systems as well as antioxidants, trophic factors, and extracellular matrix proteins. Overall, contributions in understanding neurogenesis, tissue development, differentiation, connectivity, plasticity, and cell death are widely described. A complete access to the genome of several vertebrates, as well as the recent transcriptome at the single cell level at different stages of development, also anticipates future advances in providing cues to target blinding diseases or retinal dysfunctions.

Direct Binding Methods to Measure Receptor-Ligand Interactions

G-protein-coupled receptors (GPCRs) contribute to numerous physiological processes via complex network mechanisms. While indirect signaling assays (Ca2+ mobilization, cAMP production, and GTPγS binding) have been useful in identifying and characterizing downstream signaling mechanisms of GPCRs, these methods lack measurements of direct binding affinities, kinetics, binding specificity, and selectivity that are important parameters in GPCR drug discovery. In comparison to existing direct methods that use radio- or fluorescent labels, label-free techniques can closely emulate the native interactions around binding partners. Surface plasmon resonance (SPR) is a label-free technique that utilizes the refractive index (RI) property and is applied widely in quantitative GPCR-ligand binding kinetics measurement including small molecules screening. However, purified GPCRs are further embedded in a synthetic lipid environment which is immobilized through different tags to the SPR sensor surface, resulting in a non-native environment. Here, we introduced a methodology that also uses the RI property to measure binding interactions in a label-free, immobilization-free arrangement. The free-solution technique is successfully applied in quantifying the interaction of bioactive lipids to cognate lipid GPCRs, which is not purified but rather present in near-native conditions, i.e., in milieu of other cytoplasmic lipids and proteins. To further consider the wide applicability of these free-solution approaches in biomolecular interaction research, additional applications on a variety of receptor-ligand pairs are imperative.

Unraveling the function and structure impact of deleterious missense SNPs in the human OX1R receptor by computational analysis

The orexin/hypocretin receptor type 1 (OX1R) plays a crucial role in regulating various physiological functions, especially feeding behavior, addiction, and reward. Genetic variations in the OX1R have been associated with several neurological disorders. In this study, we utilized a combination of sequence and structure-based computational tools to identify the most deleterious missense single nucleotide polymorphisms (SNPs) in the OX1R gene. Our findings revealed four highly conserved and structurally destabilizing missense SNPs, namely R144C, I148N, S172W, and A297D, located in the GTP-binding domain. Molecular dynamics simulations analysis demonstrated that all four most detrimental mutant proteins altered the overall structural flexibility and dynamics of OX1R protein, resulting in significant changes in the structural organization and motion of the protein. These findings provide valuable insights into the impact of missense SNPs on OX1R function loss and their potential contribution to the development of neurological disorders, thereby guiding future research in this field.

Multiple Regulatory Signals and Components in the Modulation of Bicarbonate Transporters

Bicarbonate transporters are responsible for the appropriate flux of bicarbonate across the plasma membrane to perform various fundamental cellular functions. The functions of bicarbonate transporters, including pH regulation, cell migration, and inflammation, are highlighted in various cellular systems, encompassing their participation in both physiological and pathological processes. In this review, we focused on recently identified modulatory signaling components that regulate the expression and activity of bicarbonate transporters. Moreover, we addressed recent advances in our understanding of cooperative systems of bicarbonate transporters and channelopathies. This current review aims to provide a new, in-depth understanding of numerous human diseases associated with the dysfunction of bicarbonate transporters.

Direct interrogation of context-dependent GPCR activity with a universal biosensor platform

G protein-coupled receptors (GPCRs) are the largest family of druggable proteins in the human genome, but progress in understanding and targeting them is hindered by the lack of tools to reliably measure their nuanced behavior in physiologically-relevant contexts. Here, we developed a collection of compact ONE vector G-protein Optical (ONE-GO) biosensor constructs as a scalable platform that can be conveniently deployed to measure G-protein activation by virtually any GPCR with high fidelity even when expressed endogenously in primary cells. By characterizing dozens of GPCRs across many cell types like primary cardiovascular cells or neurons, we revealed new insights into the molecular basis for G-protein coupling selectivity of GPCRs, pharmacogenomic profiles of anti-psychotics on naturally-occurring GPCR variants, and G-protein subtype signaling bias by endogenous GPCRs depending on cell type or upon inducing disease-like states. In summary, this open-source platform makes the direct interrogation of context-dependent GPCR activity broadly accessible.

Orexin-A/OX1R is involved in regulation of autophagy to promote cortisol secretion in adrenocortical cell

BACKGROUND

Hypercortisolism has emerged as a prominent clinical condition worldwide caused by biochemical cortisol excess in patients, and optimization treatment is needed urgently in the clinic. Previously, we observed that orexin-A/orexin type 1 receptor (OX1R) promoted cell proliferation, inhibited apoptosis, and increased cortisol release in adrenocortical cells. However, the functions of orexin-A/OX1R on autophagy and its molecular mechanism are not known.

METHODS

Transmission electron microscopy and confocal microscope were performed to detect autophagosomes. Western blot were performed to detect autophagy proteins. The cortisol concentration was assessed with an ELISA.

FINDINGS

Our data demonstrated that orexin-A/OX1R activated the mammalian target of rapamycin/p70 ribosomal protein S6 kinase-1 pathway, thereby inhibiting autophagy in H295R cells and Y-1 cells. Furthermore, the orexin-A/OX1R-mediated suppression of autophagy played a crucial role in cortisol secretion. Mechanistically, the expression of 3β-hydroxysteroid dehydrogenase/isomerase, the rate-limiting enzyme in cortisol synthesis, was increased with autophagy inhibition mediated by orexin-A/OX1R.

INTERPRETATION

This study provided the evidence that orexin-A/OX1R participated in modulating mTOR/p70S6K1/autophagy signaling pathway to promote cortisol secretion in adrenocortical cell. The findings suggest the mechanistic basis for disorders of cortisol secretion, providing the potential therapeutic targets for hypercortisolism treatment. FUND: This work was supported by National Natural Science Foundation of China (32170603, 31871286), the Doctoral Start-up Foundation of Liaoning Province (20180540008, 2019-BS-298), the Natural Science Foundation of Liaoning Province (2019-ZD-0779), and Shenyang Science and Technology Plan Fund Projects (21-173-9-28).

Identification of a novel heterozygous PTH1R variant in a Chinese family with incomplete penetrance

BACKGROUND

Mutations in PTH1R are associated with Jansen-type metaphyseal chondrodysplasia (JMC), Blomstrand osteochondrodysplasia (BOCD), Eiken syndrome, enchondroma, and primary failure of tooth eruption (PFE). Inheritance of the PTH1R gene can be either autosomal dominant or autosomal recessive, indicating the complexity of the gene. Our objective was to identify the phenotypic differences in members of a family with a novel PTH1R mutation.

METHODS

The proband was a 13-year, 6-month-old girl presenting with short stature, abnormal tooth eruption, skeletal dysplasia, and midface hypoplasia. The brother and father of the proband presented with short stature and abnormal tooth eruption. High-throughput sequencing was performed on the proband, and the variant was confirmed in the proband and other family members by Sanger sequencing. Amino acid sequence alignment was performed using ClustalX software. Three-dimensional structures were analyzed and displayed using the I-TASSER website and PyMOL software.

RESULTS

High-throughput genome sequencing and Sanger sequencing validation showed that the proband, her father, and her brother all carried the PTH1R (NM_000316) c.1393G>A (p.E465K) mutation. The c.1393G>A (p.E465K) mutation was novel, as it has not been reported in the literature database. According to the American College of Medical Genetics and Genomics (ACMG) guidelines, the p.E465K variant was considered to have uncertain significance. Biological information analysis demonstrated that this identified variant was highly conserved and highly likely pathogenic.

CONCLUSIONS

We identified a novel heterozygous mutation in the PTH1R gene leading to clinical manifestations with incomplete penetrance that expands the spectrum of known PTH1R mutations.

Neuroimmune communication in allergic rhinitis

The prevalence rate of allergic rhinitis (AR) is high worldwide. The inhalation of allergens induces AR, which is an immunoglobulin E-mediated and type 2 inflammation-driven disease. Recently, the role of neuroimmune communication in AR pathogenesis has piqued the interest of the scientific community. Various neuropeptides, such as substance P (SP), vasoactive intestinal peptide (VIP), calcitonin gene-related peptide (CGRP), nerve growth factor (NGF), and neuromedin U (NMU), released via "axon reflexes" or "central sensitization" exert regulatory effects on immune cells to elicit "neurogenic inflammation," which contributes to nasal hyperresponsiveness (NHR) in AR. Additionally, neuropeptides can be produced in immune cells. The frequent colocalization of immune and neuronal cells at certain anatomical regions promotes the establishment of neuroimmune cell units, such as nerve-mast cells, nerve-type 2 innate lymphoid cells (ILC2s), nerve-eosinophils and nerve-basophils units. Receptors expressed both on immune cells and neurons, such as TRPV1, TRPA1, and Mas-related G protein-coupled receptor X2 (MRGPRX2) mediate AR pathogenesis. This review focused on elucidating the mechanisms underlying neuroimmune communication in AR.

The effect of PACAP administration on LPS-induced cytokine expression in the Atlantic salmon SHK-1 cell line

Recent work has identified pituitary adenylate cyclase activating polypeptide (PACAP) as a potential antimicrobial and immune stimulating agent which may be suitable for use in aquaculture. However, its effects on teleost immunity are not well studied and may be significantly different than what has been observed in mammals. In this study we examined the effects of PACAP on the Atlantic salmon macrophage cell line SHK-1. PACAP was able to increase the expression of LPS-induced il-1β in at concentrations of 1 uM when administered 24h prior to LPS stimulation. Furthermore, concentrations as low as 40nM had an effect when administered both 24h prior and in tandem with LPS. PACAP was also capable of increasing the expression of il-1β and tnf-α in SHK-1 cells challenged with a low dose of heat-killed Flavobacterium columnare. We attempted to get a better understanding of the mechanism underlying this enhancement of il-1β expression by manipulating downstream signaling of PACAP with inhibitors of phosphodiesterase and phospholipase C activity. We found that inducing cAMP accumulation with phosphodiesterase inhibitors failed to recapitulate the effect of PACAP administration on LPS-mediated il-1β expression by PACAP, while use of a phospholipase C inhibitor caused a PACAP-like enhancement in LPS-mediated il-1β expression. Interestingly, the VPAC1 receptor inhibitor PG97-269, but not the PAC1 inhibitor max.d.4, also was capable of causing a PACAP-like enhancement in LPS-mediated il-1β expression. This suggests that fish do not utilize the PACAP receptors in the same manner as mammals, but that it still exerts an immunostimulatory effect that make it a good immunostimulant for use in aquaculture.

The Defined TLR3 Agonist, Nexavant, Exhibits Anti-Cancer Efficacy and Potentiates Anti-PD-1 Antibody Therapy by Enhancing Immune Cell Infiltration

Nexavant was reported as an alternative to the TLR3 agonist of Poly(I:C) and its derivatives. The physicochemical properties, signaling pathways, anti-cancer effects, and mechanisms of Nexavant were investigated. The distinctive characteristics of Nexavant compared to that of Poly(I:C) were demonstrated by precise quantification, enhanced thermostability, and increased resistance to RNase A. Unlike Poly(I:C), which activates TLR3, RIG-I, and MDA5, Nexavant stimulates signaling through TLR3 and RIG-I but not through MDA5. Compared to Poly(I:C), an intratumoral Nexavant treatment led to a unique immune response, immune cell infiltration, and suppression of tumor growth in various animal cancer models. Nexavant therapy outperformed anti-PD-1 antibody treatment in all the tested models and showed a synergistic effect in combinational therapy, especially in well-defined cold tumor models. The effect was similar to that of nivolumab in a humanized mouse model. Intranasal instillation of Nexavant led to the recruitment of immune cells (NK, CD4+ T, and CD8+ T) to the lungs, suppressing lung metastasis and improving animal survival. Our study highlighted Nexavant's defined nature for clinical use and unique signaling pathways and its potential as a standalone anti-cancer agent or in combination with anti-PD-1 antibodies.

Baizhu-Baishao herb pair ameliorates functional constipation and intestinal microflora disorder in rats

BACKGROUND

In China, Rhizoma atractylodis macrocephalae-Paeonia lactiflora Pall (Biazhu-Baishao, BZBS) is a classic herb pair used to treat intestinal stress syndrome, ulcerative colitis and other diseases. However, the mechanism of BZBS in the treatment of functional constipation (FC) has been little studied and remains unclear. In this study, a behavioral investigation, colon tissue morphology, enzyme-linked immunosorbent assay (Elisa) and intestinal microflora analysis have been used to illuminate the potential mechanism of the effects of BZBS on FC in a rat model.

METHODS

A FC rat model was constructed and BZBS was given as treatment. Observations and recordings were made of the fecal moisture content, the defecation time of the first black stool, and the rate of intestinal propulsion. Elisa was used to detect the expression levels of substance P (SP), vasoactive intestinal peptide (VIP), 5-hydroxytryptamine (5-HT) in the colon. To ascertain the composition of the microbial community, a high throughput 16S ribosomal RNA (16S rRNA) gene sequencing technique was employed.

RESULTS

Oral administration of BZBS significantly ameliorated several key excretion parameters, including the time to first black stool defecation, stool water content, and the propulsion rate in the small intestine in FC rats. It increased the expression of SP, VIP and 5-HT in the colon. 16S rRNA gene sequencing results showed that BZBS changed the microbial community structure, decreased the Bacteroidetes/Firmicutes ratio, increased the relative abundance of Blautia and Fusicatenibacter, and decreased the relative abundance of Ruminococcus and Roseburia.

CONCLUSIONS

BZBS effectively alleviates FC and improves dysbacteriosis.

PACAP/PAC1-R activation contributes to hyperalgesia in 6-OHDA-induced Parkinson's disease model rats via promoting excitatory synaptic transmission of spinal dorsal horn neurons

Pain is a common annoying non-motor symptom in Parkinson's disease (PD) that causes distress to patients. Treatment for PD pain remains a big challenge, as its underlying mechanisms are elusive. Pituitary adenylate cyclase-activating polypeptide (PACAP) and its receptor PAC1-R play important roles in regulating a variety of pathophysiological processes. In this study, we investigated whether PACAP/PAC1-R signaling was involved in the mechanisms of PD pain. 6-hydroxydopamine (6-OHDA)-induced PD model was established in rats. Behavioral tests, electrophysiological and Western blotting analysis were conducted 3 weeks later. We found that 6-OHDA rats had significantly lower mechanical paw withdrawal 50% threshold in von Frey filament test and shorter tail flick latency, while mRNA levels of Pacap and Adcyap1r1 (gene encoding PAC1-R) in the spinal dorsal horn were significantly upregulated. Whole-cell recordings from coronal spinal cord slices at L4-L6 revealed that the frequency of spontaneous excitatory postsynaptic currents (sEPSCs) in dorsal horn neurons was significantly increased, which was reversed by application of a PAC1-R antagonist PACAP 6-38 (250 nM). Furthermore, we demonstrated that intrathecal microinjection of PACAP 6-38 (0.125, 0.5, 2 μg) dose-dependently ameliorated the mechanical and thermal hyperalgesia in 6-OHDA rats. Inhibition of PACAP/PAC1-R signaling significantly suppressed the activation of Ca2+/calmodulin-dependent protein kinase II and extracellular signal-regulated kinase (ERK) in spinal dorsal horn of 6-OHDA rats. Microinjection of pAAV-Adcyap1r1 into L4-L6 spinal dorsal horn alleviated hyperalgesia in 6-OHDA rats. Intrathecal microinjection of ERK antagonist PD98059 (10 μg) significantly alleviated hyperalgesia in 6-OHDA rats associated with the inhibition of sEPSCs in dorsal horn neurons. In addition, we found that serum PACAP-38 concentration was significantly increased in PD patients with pain, and positively correlated with numerical rating scale score. In conclusion, activation of PACAP/PAC1-R induces the development of PD pain and targeting PACAP/PAC1-R is an alternative strategy for treating PD pain.

Orexins and Prostate Cancer: State of the Art and Potential Experimental and Therapeutic Perspectives

Prostate cancer (PCa) is the second most common cancer in humans. Peptides have recently been used as targeted therapeutics in cancers, due to their extensive multi-functional applications. Two hypothalamic peptides, orexins A (OXA) and B (OXB) and their specific receptors, orexin receptor 1 (OX1R) and 2 (OX2R), orchestrate several biological processes in the central nervous system and peripheral organs. However, in addition to their role in physiological responses, orexins are involved in numerous inflammatory and/or neoplastic pathologies. The presence and expression of orexins in different cancer models, including prostate cancer, and their role in inducing pro- or anti-apoptotic responses in tumor cell lines, suggest that the orexinergic system might have potential therapeutic action or function as a diagnostic marker in PCa. In addition to the traditional animal models for studying human PCa, the canine model might also serve as an additional tool, due to its clinical similarities with human prostate cancer.

Antioxidant, Anti-Inflammatory and Pro-Differentiative Effects of Chlorogenic Acid on M03-13 Human Oligodendrocyte-like Cells

Chlorogenic acid (CGA), a polyphenol found mainly in coffee and tea, exerts antioxidant, anti-inflammatory and anti-apoptotic effects at the gastrointestinal level. However, although CGA is known to cross the blood-brain barrier (BBB), its effects on the CNS are still unknown. Oligodendrocytes (OLs), the myelin-forming cells in the CNS, are the main target in demyelinating neuroinflammatory diseases such as multiple sclerosis (MS). We evaluated the antioxidant, anti-inflammatory and anti-apoptotic roles of CGA in M03-13, an immortalized human OL cell line. We found that CGA reduces intracellular superoxide ions, mitochondrial reactive oxygen species (ROS) and NADPH oxidases (NOXs) /dual oxidase 2 (DUOX2) protein levels. The stimulation of M03-13 cells with TNFα activates the nuclear factor kappa-light-chain-enhancer of activated B cell (NF-kB) pathway, leading to an increase in superoxide ion, NOXs/DUOX2 and phosphorylated extracellular regulated protein kinase (pERK) levels. In addition, tumor necrosis factor alpha (TNF-α) stimulation induces caspase 8 activation and the cleavage of poly-ADP-ribose polymerase (PARP). All these TNFα-induced effects are reversed by CGA. Furthermore, CGA induces a blockade of proliferation, driving cells to differentiation, resulting in increased mRNA levels of myelin basic protein (MBP) and proteolipid protein (PLP), which are major markers of mature OLs. Overall, these data suggest that dietary supplementation with this polyphenol could play an important beneficial role in autoimmune neuroinflammatory diseases such as MS.

Impact Assessment of Pituitary Adenylate Cyclase Activating Polypeptide (PACAP) and Hemostatic Sponge on Vascular Anastomosis Regeneration in Rats

The proper regeneration of vessel anastomoses in microvascular surgery is crucial for surgical safety. Pituitary adenylate cyclase-activating polypeptide (PACAP) can aid healing by decreasing inflammation, apoptosis and oxidative stress. In addition to hematological and hemorheological tests, we examined the biomechanical and histological features of vascular anastomoses with or without PACAP addition and/or using a hemostatic sponge (HS). End-to-end anastomoses were established on the right femoral arteries of rats. On the 21st postoperative day, femoral arteries were surgically removed for evaluation of tensile strength and for histological and molecular biological examination. Effects of PACAP were also investigated in tissue culture in vitro to avoid the effects of PACAP degrading enzymes. Surgical trauma and PACAP absorption altered laboratory parameters; most notably, the erythrocyte deformability decreased. Arterial wall thickness showed a reduction in the presence of HS, which was compensated by PACAP in both the tunica media and adventitia in vivo. The administration of PACAP elevated these parameters in vitro. In conclusion, the application of the neuropeptide augmented elastin expression while HS reduced it, but no significant alterations were detected in collagen type I expression. Elasticity and tensile strength increased in the PACAP group, while it decreased in the HS decreased. Their combined use was beneficial for vascular regeneration.

A tool kit of highly selective and sensitive genetically encoded neuropeptide sensors

Neuropeptides are key signaling molecules in the endocrine and nervous systems that regulate many critical physiological processes. Understanding the functions of neuropeptides in vivo requires the ability to monitor their dynamics with high specificity, sensitivity, and spatiotemporal resolution. However, this has been hindered by the lack of direct, sensitive, and noninvasive tools. We developed a series of GRAB (G protein-coupled receptor activation‒based) sensors for detecting somatostatin (SST), corticotropin-releasing factor (CRF), cholecystokinin (CCK), neuropeptide Y (NPY), neurotensin (NTS), and vasoactive intestinal peptide (VIP). These fluorescent sensors, which enable detection of specific neuropeptide binding at nanomolar concentrations, establish a robust tool kit for studying the release, function, and regulation of neuropeptides under both physiological and pathophysiological conditions.

From CGRP to PACAP, VIP, and Beyond: Unraveling the Next Chapters in Migraine Treatment

Migraine is a neurovascular disorder that can be debilitating for individuals and society. Current research focuses on finding effective analgesics and management strategies for migraines by targeting specific receptors and neuropeptides. Nonetheless, newly approved calcitonin gene-related peptide (CGRP) monoclonal antibodies (mAbs) have a 50% responder rate ranging from 27 to 71.0%, whereas CGRP receptor inhibitors have a 50% responder rate ranging from 56 to 71%. To address the need for novel therapeutic targets, researchers are exploring the potential of another secretin family peptide, pituitary adenylate cyclase-activating polypeptide (PACAP), as a ground-breaking treatment avenue for migraine. Preclinical models have revealed how PACAP affects the trigeminal system, which is implicated in headache disorders. Clinical studies have demonstrated the significance of PACAP in migraine pathophysiology; however, a few clinical trials remain inconclusive: the pituitary adenylate cyclase-activating peptide 1 receptor mAb, AMG 301 showed no benefit for migraine prevention, while the PACAP ligand mAb, Lu AG09222 significantly reduced the number of monthly migraine days over placebo in a phase 2 clinical trial. Meanwhile, another secretin family peptide vasoactive intestinal peptide (VIP) is gaining interest as a potential new target. In light of recent advances in PACAP research, we emphasize the potential of PACAP as a promising target for migraine treatment, highlighting the significance of exploring PACAP as a member of the antimigraine armamentarium, especially for patients who do not respond to or contraindicated to anti-CGRP therapies. By updating our knowledge of PACAP and its unique contribution to migraine pathophysiology, we can pave the way for reinforcing PACAP and other secretin peptides, including VIP, as a novel treatment option for migraines.