Preliminary Screening and Study of Key Gene Expression in Endometrial Window Period.

Background: Implantation is a highly coordinated event involving both embryonic and endometrial participation. The endometrium expresses a complex array of proteins during the menstrual cycle many of which help to define a period of receptivity collectively known as the "window of implantation." Objective: Using high-throughput RNA sequencing technology analysis to find differentially expressed genes before and after the endometrial window, and search for key marker genes of the membrane implantation window. Design: This was a retrospective study. Setting: This study was performed in the Department of Obstetrics and Gynecology, Taizhou People's Hospital. Participants: Fifty patients with repeated implantation failure in in vitro fertilization were selected and were divided into (1) the normal window group (36 cases); (2) the window forward group (8 cases); and (3) the window backward group (6 cases) based on endometrial biopsy findings. Interventions: Using RNA sequencing technology combined with biological information analysis tools to analyze the differentially-expressed genes in 9 samples. Gene Ontology databases were used for the functional annotation of these differentially-expressed genes. Kyoto Encyclopedia of Genes and Genomes analysis was used to draw a signal path diagram. Primary Outcome Measures: (1) Screening of differentially-expressed genes and (2) functional analysis of the differential genes. Results: A total of 22 differentially-expressed genes related to endometrial receptivity were obtained by transcriptome sequencing. Seven of the 22 differentially-expressed genes have been shown to have a close relationship with the endometrial receptive window period. Further, it was proved that the Wnt signaling pathway and mitogen-activated protein kinase signaling pathway were closely related to endometrial receptivity. Conclusions: The present study identified a series of key genes and pathways that may be involved in the endometrial window period, providing an experimental and theoretical basis for exploring the personalized embryo transfer program.

The role of serum vitamin D in patients with normal ovarian reserve undergoing the first IVF/ICSI cycle.

Background: The debate over the impact of vitamin D in assisted reproduction continues. The purpose of our study was to assess embryo quality and pregnancy outcomes among groups with different levels of vitamin D after the first in vitro fertilization (IVF)/intracytoplasmic sperm injection (ICSI) cycle in patients with normal ovarian reserve (NOR). Methods: Patients in this retrospective cohort study were divided into three groups: severe vitamin D deficiency group (25OH-D < 10 ng/ml), vitamin D deficiency group (10 ng/ml ≤ 25OH-D < 20 ng/ml), and non-vitamin D deficiency group (25OH-D ≥ 20 ng/ml). The primary outcome was clinical pregnancy, while the secondary outcomes were mature oocytes, oocyte fertilization, available cleavage embryos, available blastocysts, biochemical pregnancy, early abortion, and embryo implantation. A modified Poisson regression model and multiple linear regression analysis were conducted for the multivariate analysis. Results: 264 NOR patients undergoing the first IVF/ICSI cycles were included. For the primary outcome, there was no significant difference in clinical pregnancy between the severe vitamin D deficiency group and the other two groups (vitamin D deficiency group: adjusted RR = 1.026; 0.780 - 1.350; P = 0.854; non-vitamin D deficiency group: adjusted RR = 1.092; 0.743 - 1.605; P = 0.652). For all secondary outcomes, no significant differences were observed among the severe vitamin D deficiency, vitamin D deficiency, and non-vitamin D deficiency groups (P > 0.05). Exploratory subgroup analyses concerning the season of embryo transfer, phase of embryo transferred, and endometrial thickness, as well as the sensitivity analysis using logistic regression models for the primary outcome, revealed comparable clinical pregnancy rates among the groups (P > 0.05). Subgroup analysis concerning ovarian stimulation protocol indicated that in the subgroup of gonadotrophin-releasing hormone (GnRH) antagonist protocol, the clinical pregnancy rate of the non-vitamin D deficiency group was significantly higher than that of the other two groups (P < 0.05). Conclusion: Serum vitamin D level was not associated with embryo quality and pregnancy outcomes for patients with NOR. Further studies with greater sample sizes and a longer follow-up period are needed to elucidate the relationships between vitamin D levels and IVF outcomes.

Role of Calcitonin Gene-Related Peptide on the Gastrointestinal Symptoms of Migraine-Clinical Considerations: A Narrative Review.

Calcitonin gene-related peptide (CGRP) is involved in several of the pathophysiological processes underpinning migraine attacks. Therapies that target CGRP or its receptor have shown efficacy as preventive or acute treatments for migraine. Two small-molecule CGRP receptor antagonists (rimegepant and ubrogepant) are approved for the acute treatment of migraine, and four monoclonal antibodies (eptinezumab, erenumab, fremanezumab, and galcanezumab) are approved for migraine prevention; erenumab targets the canonical CGRP receptor, the others CGRP ligand. CGRP plays a role in gastrointestinal nociception, inflammation, gastric acid secretion, and motility. Nausea and vomiting are among the gastrointestinal symptoms associated with migraine, but individuals with migraine may also experience functional upper and lower gastrointestinal comorbidities, such as gastroesophageal reflux disease, gastroparesis, functional diarrhea or constipation, and irritable bowel syndrome. Although gastrointestinal symptoms in migraine can be treatment-related, they may also be attributable to increased CGRP. In this review, we summarize the epidemiological evidence for associations between migraine and gastrointestinal disorders, consider the possible physiological role of CGRP in these associations, and review the clinical occurrence of gastrointestinal events in patients with migraine receiving CGRP-based therapies and other migraine treatments. Because patients with migraine are at an increased risk of comorbid and treatment-related gastrointestinal effects, we also propose a patient-management strategy to mitigate these effects.

Discovery of Selective Pituitary Adenylate Cyclase 1 Receptor (PAC1R) Antagonist Peptides Potent in a Maxadilan/PACAP38-Induced Increase in Blood Flow Pharmacodynamic Model.

Inhibition of the pituitary adenylate cyclase 1 receptor (PAC1R) is a novel mechanism that could be used for abortive treatment of acute migraine. Our research began with comparative analysis of known PAC1R ligand scaffolds, PACAP38 and Maxadilan, which resulted in the selection of des(24-42) Maxadilan, 6, as a starting point. C-terminal modifications of 6 improved the peptide metabolic stability in vitro and in vivo. SAR investigations identified synergistic combinations of amino acid replacements that significantly increased the in vitro PAC1R inhibitory activity of the analogs to the pM IC90 range. Our modifications further enabled deletion of up to six residues without impacting potency, thus improving peptide ligand binding efficiency. Analogs 17 and 18 exhibited robust in vivo efficacy in the rat Maxadilan-induced increase in blood flow (MIIBF) pharmacodynamic model at 0.3 mg/kg subcutaneous dosing. The first cocrystal structure of a PAC1R antagonist peptide (18) with PAC1R extracellular domain is reported.

Azepino-indazoles as calcitonin gene-related peptide (CGRP) receptor antagonists.

Calcitonin gene-related peptide (CGRP) receptor antagonists have been shown clinically to be effective treatments for migraine. Zavegepant (BHV-3500, BMS-742413) is a high affinity antagonist of the CGRP receptor (hCGRP Ki = 0.023 nM) that has demonstrated efficacy in the acute treatment of migraine with intranasal delivery in a Phase 2/3 trial, despite showing low oral bioavailability in rats (FPO = 1.7%). Using zavegepant as a template, we sought to improve oral bioavailability through a series of azepinones which were designed in an attempt to reduce the number of rotatable bonds. These efforts led to the discovery of compound 21 which was able to mostly maintain high affinity binding (hCGRP Ki = 0.100 nM) and in vivo efficacy in the marmoset facial blood flow assay, while greatly improving oral bioavailability (rat FPO = 17%).

Author Correction: Cryo-EM structures of PAC1 receptor reveal ligand binding mechanism.

An amendment to this paper has been published and can be accessed via a link at the top of the paper.

PAC1 receptor blockade reduces central nociceptive activity: new approach for primary headache?

Pituitary adenylate cyclase activating polypeptide-38 (PACAP38) may play an important role in primary headaches. Preclinical evidence suggests that PACAP38 modulates trigeminal nociceptive activity mainly through PAC1 receptors while clinical studies report that plasma concentrations of PACAP38 are elevated in spontaneous attacks of cluster headache and migraine and normalize after treatment with sumatriptan. Intravenous infusion of PACAP38 induces migraine-like attacks in migraineurs and cluster-like attacks in cluster headache patients. A rodent-specific PAC1 receptor antibody Ab181 was developed, and its effect on nociceptive neuronal activity in the trigeminocervical complex was investigated in vivo in an electrophysiological model relevant to primary headaches. Ab181 is potent and selective at the rat PAC1 receptor and provides near-maximum target coverage at 10 mg/kg for more than 48 hours. Without affecting spontaneous neuronal activity, Ab181 effectively inhibits stimulus-evoked activity in the trigeminocervical complex. Immunohistochemical analysis revealed its binding in the trigeminal ganglion and sphenopalatine ganglion but not within the central nervous system suggesting a peripheral site of action. The pharmacological approach using a specific PAC1 receptor antibody could provide a novel mechanism with a potential clinical efficacy in the treatment of primary headaches.

Molecular Insight into Recognition of the CGRPR Complex by Migraine Prevention Therapy Aimovig (Erenumab).

Calcitonin-gene-related peptide (CGRP) plays a key role in migraine pathophysiology. Aimovig (erenumab; erenumab-aooe in the United States) is the only US Food and Drug Administration (FDA)-approved monoclonal antibody (mAb) therapy against the CGRP receptor (CGRPR) for the prevention of migraine. Aimovig is also the first FDA-approved mAb against a G-protein-coupled receptor (GPCR). Here, we report the architecture and functional attributes of erenumab critical for its potent antagonism against CGRPR. The crystal structure of erenumab in complex with CGRPR reveals a direct ligand-blocking mechanism, enabled by a remarkable 21-residue-long complementary determining region (CDR)-H3 loop, which adopts a tyrosine-rich helix-turn tip and projects into the deep interface of the calcitonin receptor-like receptor (CLR) and RAMP1 subunits of CGRPR. Furthermore, erenumab engages with residues specific to CLR and RAMP1, providing the molecular basis for its exquisite selectivity. Such structural insights reveal the drug action mechanism of erenumab and shed light on developing antibody therapeutics targeting GPCRs.

Cryo-EM structures of PAC1 receptor reveal ligand binding mechanism.

The pituitary adenylate cyclase-activating polypeptide type I receptor (PAC1R) belongs to the secretin receptor family and is widely distributed in the central neural system and peripheral organs. Abnormal activation of the receptor mediates trigeminovascular activation and sensitization, which is highly related to migraine, making PAC1R a potential therapeutic target. Elucidation of PAC1R activation mechanism would benefit discovery of therapeutic drugs for neuronal disorders. PAC1R activity is governed by pituitary adenylate cyclase-activating polypeptide (PACAP), known as a major vasodilator neuropeptide, and maxadilan, a native peptide from the sand fly, which is also capable of activating the receptor with similar potency. These peptide ligands have divergent sequences yet initiate convergent PAC1R activity. It is of interest to understand the mechanism of PAC1R ligand recognition and receptor activity regulation through structural biology. Here we report two near-atomic resolution cryo-EM structures of PAC1R activated by PACAP38 or maxadilan, providing structural insights into two distinct ligand binding modes. The structures illustrate flexibility of the extracellular domain (ECD) for ligands with distinct conformations, where ECD accommodates ligands in different orientations while extracellular loop 1 (ECL1) protrudes to further anchor the ligand bound in the orthosteric site. By structure-guided molecular modeling and mutagenesis, we tested residues in the ligand-binding pockets and identified clusters of residues that are critical for receptor activity. The structures reported here for the first time elucidate the mechanism of specificity and flexibility of ligand recognition and binding for PAC1R, and provide insights toward the design of therapeutic molecules targeting PAC1R.

Erenumab (AMG 334), a monoclonal antagonist antibody against the canonical CGRP receptor, does not impair vasodilatory or contractile responses to other vasoactive agents in human isolated cranial arteries.

BACKGROUND: Calcitonin gene-related peptide (CGRP) is a neuronal transmitter present in intracranial sensory nerves, where it is involved in migraine pathophysiology as well as other biological functions. Recently, the fully human monoclonal antibody erenumab (AMG 334), which targets the canonical calcitonin gene-related peptide receptor, showed significant prophylactic efficacy and favourable safety in phase II and III clinical trials for episodic and chronic migraine and is now approved for migraine prevention in several countries. OBJECTIVE: Given that calcitonin gene-related peptide can mediate vasodilation, we investigated the effect of erenumab on vasoactive responses in the presence or absence of various vasodilatory and vasocontractile mediators in a model using isolated human cerebral and meningeal arteries. METHODS: Ring segments of human isolated cerebral and meningeal arteries were mounted in a sensitive myograph. On arterial segments pre-contracted with 30 mM potassium chloride, vasoactive responses to calcitonin gene-related peptide were studied in the presence of different concentrations of erenumab. At the maximal tested inhibitory concentration of erenumab (100 nM), functional arterial relaxation in response to nicardipine or substance P, and the contractile responses to sumatriptan and dihydroergotamine were examined. RESULTS: 30 mM potassium chloride produced a stable contraction of the vessel segments and calcitonin gene-related peptide induced a concentration-dependent relaxation. We observed that (i) erenumab had no direct contractile or relaxant effects per se (by itself), (ii) pre-treatment with erenumab antagonized the calcitonin gene-related peptide-induced relaxation in a competitive manner, (iii) the relaxant responses to nicardipine or substance P were unaffected in the presence of erenumab and (iv) the contraction induced by sumatriptan or dihydroergotamine was not modified by erenumab. CONCLUSION: Our findings demonstrate that erenumab, while not associated with vasoactive properties per se, specifically inhibits calcitonin gene-related peptide-induced relaxation of cranial arteries without impacting vasodilatory responses or contractile responses of endogenous or pharmacological vasoactive compounds.

Characterisation of vasodilatory responses in the presence of the CGRP receptor antibody erenumab in human isolated arteries.

BACKGROUND: Migraine is associated with activation of the trigeminovascular system, release of calcitonin gene-related peptide (CGRP) and dilation of dural arteries. Novel treatments target calcitonin gene-related peptide or its receptor, which are present in all vascular beds, raising cardiovascular concerns. Erenumab is a human CGRP-receptor antibody approved for the prophylactic treatment of migraine. METHODS: We characterised the relaxant responses to CGRP in the absence and presence of erenumab (1 µM) in isolated human middle meningeal, internal mammary and (proximal and distal) coronary arteries. Furthermore, in human internal mammary arteries from cardiovascularly-compromised patients, we assessed the pharmacological specificity of erenumab by investigating whether the vasodilatory responses to acetylcholine, sodium nitroprusside, pituitary adenylate cyclase activating polypeptide-38 (PACAP), vasoactive intestinal peptide and nicardipine, along with the vasoconstrictor responses to dihydroergotamine, were modified by erenumab. RESULTS: Calcitonin gene-related peptide induced concentration-dependent vasodilatory responses in all vessels studied that were significantly antagonised by erenumab. In human internal mammary arteries from cardiovascularly-compromised patients, the responses to acetylcholine, sodium nitroprusside, PACAP, vasoactive intestinal peptide, nicardipine and dihydroergotamine were unaffected by erenumab. CONCLUSION: Erenumab inhibits calcitonin gene-related peptide-induced vasodilatory responses in human middle meningeal arteries, human internal mammary arteries and human coronary arteries. Moreover, erenumab shows functional specificity as no interaction was observed with the relaxant responses to several vasodilators, nor the dihydroergotamine-dependent vasoconstrictor responses.

Effects of monoclonal antagonist antibodies on calcitonin gene-related peptide receptor function and trafficking.

BACKGROUND: Monoclonal antibodies against calcitonin gene-related peptide (CGRP) or its receptor are efficacious for the prevention of migraine headaches. The downstream molecular mechanisms following ligand-receptor blockade by which these antibodies prevent CGRP signaling through CGRP receptors have not been demonstrated. METHODS: Here we produced tool monoclonal functional antagonist antibodies against CGRP and its canonical receptor and developed a novel cellular model using fluorogen-activated protein technology that allows detection of CGRP receptor internalization by flow cytometry and, for an extended time course, visualization by confocal microscopy. RESULTS: Using this cell model we showed that these antagonist antibodies block both CGRP-induced cAMP signaling and CGRP receptor internalization. At least 10-fold higher concentrations of either antibody are necessary to block CGRP receptor internalization compared with cAMP accumulation in our cell model. CONCLUSION: These data reinforce our understanding of how monoclonal functional antagonist antibodies interfere with CGRP signaling.

Nonclinical safety evaluation of erenumab, a CGRP receptor inhibitor for the prevention of migraine.

Calcitonin gene-related peptide (CGRP) and its receptor have been implicated as a key mediator in the pathophysiology of migraine. Thus, erenumab, a monoclonal antibody antagonist of the CGRP receptor, administered as a once monthly dose of 70 or 140 mg has been approved for the preventive treatment of migraine in adults. Due to the species specificity of erenumab, the cynomolgus monkey was used in the pharmacology, pharmacokinetics, and toxicology studies to support the clinical program. There were no effects of erenumab on platelets in vitro (by binding, activation or phagocytosis assays). Specific staining of human tissues with erenumab did not indicated any off-target binding. There were no erenumab-related findings in a cardiovascular safety pharmacology study in cynomolgus monkeys or in vitro in human isolated coronary arteries. Repeat-dose toxicology studies conducted in cynomolgus monkeys at dose levels up to 225 mg/kg (1 month) or up to 150 mg/kg (up to 6 months) with twice weekly subcutaneous (SC) doses showed no evidence of erenumab-mediated adverse toxicity. There were no effects on pregnancy, embryo-fetal or postnatal growth and development in an enhanced pre-postnatal development study in the cynomolgus monkey. There was evidence of placental transfer of erenumab based on measurable serum concentrations in the infants up to 3 months post birth. The maternal and developmental no-observed-effect level (NOEL) was the highest dose tested (50 mg/kg SC Q2W). These nonclinical data in total indicate no safety signal of concern to date and provide adequate margins of exposure between the observed safe doses in animals and clinical dose levels.

Discovery of the Migraine Prevention Therapeutic Aimovig (Erenumab), the First FDA-Approved Antibody against a G-Protein-Coupled Receptor.

In 2018, the United States Food and Drug Administration (FDA) approved Aimovig (erenumab) for the prevention of migraine. Erenumab is the first FDA approved antibody therapeutic against a G-protein-coupled receptor, the canonical receptor of calcitonin gene related peptide (CGRP-R). A novel, epitope-focused antigen was created to reconstruct the extracellular domains of the CGRP-R in a stable conformation. Successful inoculation of XenoMouse animals and careful screening yielded multiple candidate molecules for high potency and exquisite selectivity toward the CGRP-R over related receptors. These efforts led to the discovery of erenumab which has demonstrated the desired efficacy and safety profiles in multiple clinical studies for the prevention of migraine. The innovation developed in the discovery of erenumab furthers the ability to target G-coupled protein receptors using antibody approaches.

PAC1 receptor mRNA and protein distribution in rat and human trigeminal and sphenopalatine ganglia, spinal trigeminal nucleus and in dura mater.

BACKGROUND: To further understand the role of pituitary adenylate cyclase-activating polypeptide 1 (PAC1) receptors in headache disorders, we mapped their expression in tissues of the trigemino-autonomic system by immunohistochemistry and in situ hybridization. METHODS: To optimize screening for monoclonal antibodies suitable for immunohistochemistry on formalin-fixed, paraffin-embedded tissues, we developed a new enzyme-linked immunosorbent assay using formalin-fixed, paraffin-embedded cells overexpressing human PAC1 receptors. 169G4.1 was selected from these studies for analysis of rat and human tissues and chimerized onto a mouse backbone to avoid human-on-human cross-reactivity. Immunoreactivity was compared to PAC1 receptor mRNA by in situ hybridization in both species. RESULTS: 169G4.1 immunoreactivity delineated neuronal cell bodies in the sphenopalatine ganglion in both rat and human, whereas no staining was detected in the trigeminal ganglion. The spinal trigeminal nucleus in both species showed immunoreactivity as especially strong in the upper laminae with both cell bodies and neuropil being labelled. No immunoreactivity was seen in either rat or human dura mater vessels. In situ hybridization in both species revealed mRNA in sphenopalatine ganglion neurons and the spinal trigeminal nucleus, a weak signal in the trigeminal nucleus and no signal in dural vessels. CONCLUSION: Taken together, these data support a role for PAC1 receptors in the trigemino-autonomic system as it relates to headache pathophysiology.

Efficient production of lactulose from whey powder by cellobiose 2-epimerase in an enzymatic membrane reactor.

In this study, the gene encoding cellobiose 2-epimerase from Caldicellulosiruptor saccharolyticus (CsCE) was successfully expressed in Bacillus subtilis WB800. After the fermentation medium optimization, the activity of recombinant strain was 4.5-fold higher than the original medium in a 7.5L fermentor. The optimal catalytic pH and temperature of crude CsCE were 7.0 and 80°C, respectively. An enzymatic synthesis of lactulose was developed using cheese-whey lactose as its substrate. The maximum conversion rate of whey powder obtained was 58.5% using 7.5 U/mL CsCE. The enzymatic membrane reactor system exhibited a great operational stability, confirmed with the higher lactose conversion (42.4%) after 10 batches. To our best knowledge, this is the first report of lactulose synthesis in food grade strain, which improve the food safety, and we not only realize the biological production of lactulose, but also make good use of industrial waste, which have positive impact on environment.

Effects of Shenlian extract on experimental atherosclerosis in ApoE-deficient mice based on ultrasound biomicroscopy.

BACKGROUND: This study directly and dynamically investigated the effects of SL extract (i.e., a combination of Radix Salviae miltiorrhizae and Andrographis paniculata extract) on plaque progression in vivo by high resolution ultrasound biomicroscopy (UBM). METHODS: An atherosclerosis model was established by placing a perivascular collar on the right common carotid artery in apolipoprotein E-deficient (ApoE-/-) mice. Thickness, plaque area and local blood flow were observed by UBM, pathological changes were observed by histochemical staining, and lipid levels were measured by respective commercially available kits. RESULTS: Compared with the model group, the SL extract groups showed reduced wall thickness of the aortic arch (GC: P = 0.001, P = 0.002, and P < 0.001; LC: P < 0.001, P < 0.001, and P < 0.001; BC: P = 0.027, P = 0.017, and P = 0.003; respectively), which presented with retarded plaque progression of the cartoid artery with concordantly increased blood flow (P = 0.002 and P < 0.001) as visualized in vivo by UBM. Histological analysis confirmed the reduction of carotid atherosclerosis. CONCLUSIONS: The SL extract inhibited the formation of atherosclerotic plaques in an ApoE-/- mice model by UBM analysis, and did so by effects that ameliorated local blood flow and improved blood lipid levels.

Immunohistochemical localization of the calcitonin gene-related peptide binding site in the primate trigeminovascular system using functional antagonist antibodies.

Calcitonin gene-related peptide (CGRP) is a potent vasodilator and a neuromodulator implicated in the pathophysiology of migraine. It binds to the extracellular domains of calcitonin receptor-like receptor (CLR) and receptor activity-modifying protein (RAMP) 1 that together form the CGRP receptor. Antagonist antibodies against CGRP and its binding site at the receptor are clinically effective in preventing migraine attacks. The blood-brain barrier penetration of these antagonist antibodies is limited, suggesting that a potential peripheral site of action is sufficient to prevent migraine attacks. To further understand the sites of CGRP-mediated signaling in migraine, we used immunohistochemical staining with recently developed antagonist antibodies specifically recognizing a fusion protein of the extracellular domains of RAMP1 and CLR that comprise the CGRP binding pocket at the CGRP receptor in monkey and man. We confirmed binding of the antagonist antibodies to human vascular smooth muscle cells (VSMCs) of dural meningeal arteries and neurons in the trigeminal ganglion, both of which are likely sites of action for therapeutic antibodies in migraine patients. We further used one of these antibodies for detailed mapping on cynomolgus monkey tissue and found antagonist antibody binding sites at multiple levels in the trigeminovascular system: in the dura mater VSMCs, in neurons and satellite glial cells in the trigeminal ganglion, and in neurons in the spinal trigeminal nucleus caudalis. These data reinforce and clarify our understanding of CGRP receptor localization in a pattern consistent with a role for CGRP receptors in trigeminal sensitization and migraine pathology.

Synthesis and SAR of calcitonin gene-related peptide (CGRP) antagonists containing substituted aryl-piperazines and piperidines.

Calcitonin gene-related peptide (CGRP) is a potent neuropeptide implicated in the pathophysiology of migraine. In the course of seeking CGRP antagonists with improved oral bioavailability, metabolic stability, and pharmacokinetic properties, lower molecular weight, structurally simpler piperidine and piperazine analogs of BMS-694153 were prepared. Several were found to have nM binding affinity in vitro. The synthesis and SAR of these substituted piperidine and piperazine CGRP antagonists are discussed.