Inhibition Of Calcitonin Gene-related Peptide Research Articles

Calcitonin Gene-Related Peptide Inhibition and Development of Acne and Rosacea

This cohort study investigates whether calcitonin gene-related peptide inhibition is associated with reduced rates of developing acne or rosacea in patients who experience migraines.

CGRP as a potential mediator for the sexually dimorphic responses to traumatic brain injury

BackgroundThe outcomes of traumatic brain injury (TBI) exhibit variance contingent upon biological sex. Although female sex hormones exert neuroprotective effects, the administration of estrogen and progesterone has not yielded conclusive results. Hence, it is conceivable that additional mediators, distinct from female sex hormones, merit consideration due to their potential differential impact on TBI outcomes. Calcitonin gene-related peptide (CGRP) exhibits sexually dimorphic expression and demonstrates neuroprotective effects in acute brain injuries. In this study, we aimed to examine sex-based variations in TBI structural and functional outcomes with respect to CGRP expression.MethodsMale and female Sprague Dawley rats were exposed to controlled cortical impact to induce severe TBI, followed by interventions with and without CGRP inhibition. In the acute phase of TBI, the study centered on elucidating the influence of CGRP on oxidative stress, nuclear factor erythroid 2-related factor 2 (Nrf2) and endothelial nitric oxide synthase (eNOS) signaling in the peri-impact tissue. Subsequently, during the chronic phase of TBI, the investigation expanded to evaluate CGRP expression in relation to lesion volume, microvascular dysfunction, and white matter injury, as well as working and spatial memory, anxiety-like, and depression-like behaviors in subjects of both sexes.ResultsFemale rats exhibited elevated levels of CGRP in the peri-impact brain tissue during both baseline conditions and in the acute and chronic phases of TBI, in comparison to age-matched male counterparts. Enhanced CGRP levels in specific brain sub-regions among female rats correlated with superior structural and functional outcomes following TBI compared to their male counterparts. CGRP inhibition induced heightened oxidative stress and a reduction in the expression of Nrf2 and eNOS in both male and female rats, with the observed alteration being more pronounced in females than in males.ConclusionsThis study marks the inaugural identification of CGRP as a downstream mediator contributing to the sexually dimorphic response observed in TBI outcomes.

Effect of CGRP inhibitors on interictal cerebral hemodynamics in individuals with migraine.

Calcitonin gene-related peptide (CGRP) plays an important role in cerebral vasodilation, so here we aim to quantify the impact of CGRP monoclonal antibody (mAb) therapy on cerebral hemodynamics. In 23 patients with chronic and episodic migraine, cerebral hemodynamic monitoring was performed (1) prior to and (2) 3-months into CGRP-mAb therapy. Transcranial Doppler monitored cerebral blood flow velocity (CBFv) in the middle cerebral artery (MCA) and posterior cerebral artery (PCA), from which cerebrovascular reactivity (CVR) and cerebral autoregulation (CA; Mx-index) were calculated. CA was similar off and on treatment, in the MCA (p = 0.42) and PCA (p = 0.72). CVR was also unaffected by treatment, in the MCA (p = 0.38) and PCA (p = 0.92). CBFv and blood pressure were also unaffected. The subgroup of clinical responders (>50% reduction in migraine frequency) exhibited a small reduction in MCA-CBFv (6.0 cm/s; IQR: 1.1-12.4; p = 0.007) and PCA-CBFv (8.9 cm/s; IQR: 6.9-10.3; p = 0.04). Dynamic measures of cerebrovascular physiology were preserved after 3 months of CGRP-mAb therapy, but a small reduction in CBFv was observed in patients who responded to treatment. Subgroup findings should be interpreted cautiously, but further investigation may clarify if CBFv is dependent on the degree of CGRP inhibition or may serve as a biomarker of drug sensitivity.

Cryo-EM Structure of the Human Amylin 1 Receptor in Complex with CGRP and Gs Protein.

Inhibition of calcitonin gene-related peptide (CGRP) or its cognate CGRP receptor (CGRPR) has arisen as a major breakthrough in the treatment of migraine. However, a second CGRP-responsive receptor exists, the amylin (Amy) 1 receptor (AMY1R), yet its involvement in the pathology of migraine is poorly understood. AMY1R and CGRPR are heterodimers consisting of receptor activity-modifying protein 1 (RAMP1) with the calcitonin receptor (CTR) and the calcitonin receptor-like receptor (CLR), respectively. Here, we present the structure of AMY1R in complex with CGRP and Gs protein and compare it with the reported structures of the AMY1R complex with rat amylin (rAmy) and the CGRPR in complex with CGRP. Despite similar protein backbones observed within the receptors and the N- and C-termini of the two peptides bound to the AMY1R complexes, they have distinct organization in the peptide midregions (the bypass motif) that is correlated with differences in the dynamics of the respective receptor extracellular domains. Moreover, divergent conformations of extracellular loop (ECL) 3, intracellular loop (ICL) 2, and ICL3 within the CTR and CLR protomers are evident when comparing the CGRP bound to the CGRPR and AMY1R, which influences the binding mode of CGRP. However, the conserved interactions made by the C-terminus of CGRP to the CGRPR and AMY1R are likely to account for cross-reactivity of nonpeptide CGRPR antagonists observed at AMY1R, which also extends to other clinically used CGRPR blockers, including antibodies.

Safety and Efficacy of Zavegepant in Treating Migraine: A Systematic Review.

Drugs that act on the calcitonin gene-related peptide (CGRP) pathway herald the dawn of a new era in the management of migraine headaches. The blockade of CGRP alleviates neural inflammation and has been associated with reduced pain sensitization. Zavegepant is a third-generation drug and is the first intranasal CGRP antagonist to be developed. This systematic review aims to assess the safety, efficacy, pharmacokinetics, and tolerability of Zavegepant as an abortive treatment for migraine.Studies that assessed the safety, tolerability, and efficacy of Zavegepant for migraine were identified through a systematic literature review of PubMed, Clinicaltrials.gov, and Cochrane databases in April 2023. Our systematic review yielded a total of six studies that fit our inclusion criteria. Of these, data from only two randomized control trials (RCTs) was homogenous; hence, forest plots of results pooled from the included studies were not reported. The included studies showed that Zavegepant is an efficacious and well-tolerated abortive treatment modality for episodic migraine in adult patients. Zavegepant showed safety and efficacy in migraine treatment according to various parameters throughout the six included studies. These parameters include adverse events, pharmacokinetic properties, CGRP inhibition, effect on blood pressure/electrocardiogram, pain freedom, and freedom from most bothersome symptoms.

Peripheral CCL2-CCR2 signalling contributes to chronic headache-related sensitization.

Migraine, especially chronic migraine, is highly debilitating and still lacks effective treatment. The persistent headache arises from activation and sensitization of primary afferent neurons in the trigeminovascular pathway, but the underlying mechanisms remain incompletely understood. Animal studies indicate that signalling through chemokine C-C motif ligand 2 (CCL2) and C-C motif chemokine receptor 2 (CCR2) mediates the development of chronic pain after tissue or nerve injury. Some migraine patients had elevated CCL2 levels in CSF or cranial periosteum. However, whether the CCL2-CCR2 signalling pathway contributes to chronic migraine is not clear. Here, we modelled chronic headache with repeated administration of nitroglycerin (NTG, a reliable migraine trigger in migraineurs) and found that both Ccl2 and Ccr2 mRNA were upregulated in dura and trigeminal ganglion (TG) tissues that are implicated in migraine pathophysiology. In Ccl2 and Ccr2 global knockout mice, repeated NTG administration did not evoke acute or persistent facial skin hypersensitivity as in wild-type mice. Intraperitoneal injection of CCL2 neutralizing antibodies inhibited chronic headache-related behaviours induced by repeated NTG administration and repetitive restraint stress, suggesting that the peripheral CCL2-CCR2 signalling mediates headache chronification. We found that CCL2 was mainly expressed in TG neurons and cells associated with dura blood vessels, whereas CCR2 was expressed in subsets of macrophages and T cells in TG and dura but not in TG neurons under both control and disease states. Deletion of Ccr2 gene in primary afferent neurons did not alter NTG-induced sensitization, but eliminating CCR2 expression in either T cells or myeloid cells abolished NTG-induced behaviours, indicating that both CCL2-CCR2 signalling in T cells and macrophages are required to establish chronic headache-related sensitization. At cellular level, repeated NTG administration increased the number of TG neurons that responded to calcitonin-gene-related peptide (CGRP) and pituitary adenylate cyclase activating polypeptide (PACAP) as well as the production of CGRP in wild-type but not Ccr2 global knockout mice. Lastly, co-administration of CCL2 and CGRP neutralizing antibodies was more effective in reversing NTG-induced behaviours than individual antibodies. Taken together, these results suggest that migraine triggers activate CCL2-CCR2 signalling in macrophages and T cells. This consequently enhances both CGRP and PACAP signalling in TG neurons, ultimately leading to persistent neuronal sensitization underlying chronic headache. Our work not only identifies the peripheral CCL2 and CCR2 as potential targets for chronic migraine therapy, but also provides proof-of-concept that inhibition of both peripheral CGRP and CCL2-CCR2 signalling is more effective than targeting either pathway alone.

Endogenous Inflammatory Mediators Produced by Injury Activate TRPV1 and TRPA1 Nociceptors to Induce Sexually Dimorphic Cold Pain That Is Dependent on TRPM8 and GFRα3.

The detection of environmental temperatures is critical for survival, yet inappropriate responses to thermal stimuli can have a negative impact on overall health. The physiological effect of cold is distinct among somatosensory modalities in that it is soothing and analgesic, but also agonizing in the context of tissue damage. Inflammatory mediators produced during injury activate nociceptors to release neuropeptides, such as calcitonin gene-related peptide (CGRP) and substance P, inducing neurogenic inflammation, which further exasperates pain. Many inflammatory mediators induce sensitization to heat and mechanical stimuli but, conversely, inhibit cold responsiveness, and the identity of molecules inducing cold pain peripherally is enigmatic, as are the cellular and molecular mechanisms altering cold sensitivity. Here, we asked whether inflammatory mediators that induce neurogenic inflammation via the nociceptive ion channels TRPV1 (vanilloid subfamily of transient receptor potential channel) and TRPA1 (transient receptor potential ankyrin 1) lead to cold pain in mice. Specifically, we tested cold sensitivity in mice after intraplantar injection of lysophosphatidic acid or 4-hydroxy-2-nonenal, finding that each induces cold pain that is dependent on the cold-gated channel transient receptor potential melastatin 8 (TRPM8). Inhibition of CGRP, substance P, or toll-like receptor 4 (TLR4) signaling attenuates this phenotype, and each neuropeptide produces TRPM8-dependent cold pain directly. Further, the inhibition of CGRP or TLR4 signaling alleviates cold allodynia differentially by sex. Last, cold pain induced by both inflammatory mediators and neuropeptides requires TRPM8, as well as the neurotrophin artemin and its receptor GDNF receptor α3 (GFRα3). These results are consistent with artemin-induced cold allodynia requiring TRPM8, demonstrating that neurogenic inflammation alters cold sensitivity via localized artemin release that induces cold pain via GFRα3 and TRPM8.SIGNIFICANCE STATEMENT The cellular and molecular mechanisms that generate pain are complex with a diverse array of pain-producing molecules generated during injury that act to sensitize peripheral sensory neurons, thereby inducing pain. Here we identify a specific neuroinflammatory pathway involving the ion channel TRPM8 (transient receptor potential cation channel subfamily M member 8) and the neurotrophin receptor GFRα3 (GDNF receptor α3) that leads to cold pain, providing select targets for potential therapies for this pain modality.

Inhibition of CGRP signaling impairs fracture healing in mice.

Calcitonin gene-related peptide (CGRP) is a neuropeptide produced by sensory nerves and functions as a pain sensor. It acts by binding to the calcitonin-like receptor (CLR, protein; Calcrl, gene). CGRP inhibition has been recently introduced as therapeutic treatment of migraine-associated pain. Previous studies have shown that CGRP stimulates bone formation. The aim of our study is to determine whether the inhibition of CGRP signaling negatively impacted fracture healing. Using α-smooth muscle actin (αSMA) Cre animals crossed with Ai9 reporter mice, we showed that CGRP-expressingnerves are near αSMA + cells in the periosteum. In vitro experiments revealed that periosteal cells express Calcrl and receptor activity modifying protein 1; and CGRP stimulation increased periosteal cell proliferation. Using a tamoxifen-inducible model αSMACre/CLRfl/fl , we targeted the deletion of CLR to periosteal progenitor cells and examined fracture healing. Microcomputed tomography of fractured femurs showed a reduction in bone mass in αSMACre+/CLRfl/fl female mice relative to controls and callus volume in males. Pharmacological CGRP-CLR inhibition was achieved by subcutaneous delivery of customized pellets with small molecule inhibitor olcegepant (BIBN-4096) at a dose of 10 μg/day. BIBN-4096-treated C57BL/6J mice had a higher latency toward thermal nociception than placebo-treated mice, indicating impaired sensory function through CGRP inhibition. CGRP inhibition also resulted in reduced callus volume, bone mass, and bone strength compared to placebo controls. These results indicate that inhibiting CGRP by deleting CLR or by using BIBN-4096, contributes to delayed bone healing.

CGRP and Shh Mediate the Dental Pulp Cell Response to Neuron Stimulation

Dental pain is a persistent, detrimental public health issue that requires a better understanding of the mechanisms of tooth pain and inflammation in order to develop more effective treatments. Calcitonin gene-related peptide (CGRP) and dental pulp cells are promising candidates for mediating tooth pain and generating reparative dental tissues, respectively, but their behavior in the context of pulpitis remains elusive. The mouse incisor requires Sonic hedgehog (Shh) secreted from sensory nerves to continuously regenerate. However, it is unknown whether sensory nerves also regulate the comparatively nonregenerative mouse molar through CGRP and Shh. This is an important knowledge gap to fill since mouse incisors differ biologically from human teeth, while mouse and human molars are similar. In this work, we identified that molar pulp cells express CGRP receptor and Gli1, a Hedgehog (Hh) signaling protein found to label a dental stem cell population in the mouse incisor. We also observed in a mouse molar injury model that Hh signaling was activated and Shh expression was upregulated in vivo. We then determined in vitro that Shh and CGRP regulate differentiation of primary mouse molar and incisor pulp cells and a human dental pulp stem cell line. Furthermore, conditioned media from stimulated sensory neurons induced Hh signaling activation and inflammatory gene expression in primary molar pulp cells, which was abolished by inhibition of either Shh or CGRP. Our results suggest that CGRP and Shh signaling may promote an inflammatory response after injury in the molar and that activated sensory nerves secrete CGRP and Shh to regulate molar pulp cell expansion and differentiation into odontoblast-like cells for dentin repair. Thus, CGRP/Shh signaling should be considered for new strategies that seek to manage pain or dentin regeneration in the molar.

Efficacy and safety of anti-CGRP(r) monoclonal antibodies in real clinical practice: preliminary analysis after three months of therapy

Monoclonal antibodies inhibiting calcitonin gene related peptide (CGRP) or its receptor have been widely used for migraine prophylactic therapy for the past three years. Evaluation of their efficacy and safety of therapy in real clinical practice is needed.Objective: to evaluate the efficacy and safety of Erenumab, a monoclonal antibody inhibiting the CGRP receptor during three months of therapy.Patients and methods. Sixty-eight patients (58 women and 10 men, mean age 37±10.4 years) with episodic or chronic migraine who were treated with Erenumab were observed. Patients were assessed with MIDAS, WPAI, and HADS scales; the presence of cutaneous allodynia was evaluated with ASC-12 questionnaire. Patients kept a headache diary and marked adverse events during the whole treatment period.Results and discussion. 47 patients (69%) had chronic migraine and 32 (71.9%) had medication overuse headache. In 48 patients (70%) after 3 injections of Erenumab the number of days with migraine decreased by 50% or more. In 7 patients (10%), the reduction in headache days was more than 75%; 20 (29%) did not experience sufficient effect after three months of therapy. Nineteen adverse events were noted in 15 (22%) patients. Severe constipation led to discontinuation of treatment in two patients (3%).Conclusion. The study showed the efficacy and safety of Erenumab for migraine prophylaxis in both patients with episodic and chronic migraine.

CGRP Inhibitors and Oxidative Stress Biomarkers in Resistant Migraine: A Real-Life Study with Erenumab, Fremanezumab, and Galcanezumab

Patients with high-frequency resistant migraine and medication-overuse headache are still the main clinical challenge in tertiary headache centers. The approval of targeted antibodies against the calcitonin gene-related peptide (CGRP) and its receptor represents a powerful instrument. In this study, we observed how biological and clinical features of resistant migraineurs responded to erenumab, fremanezumab, or galcanezumab. We found a reduction in advanced oxidation protein products (AOPP) as a biomarker of improved redox state after six months of treatment. We also found that treatment efficacy was precocious and maintained with high individual responder rates. In particular, seven out of ten patients achieved a reduction of 50% from the baseline at three months, which was maintained at six months, while about one out of our patients experienced a 75% reduction in headache frequency from the first month of treatment. The migraine disability assessment (MIDAS) and the associated fatigue, anxiety, and sleep quality also significantly improved. The allodynia symptom dropped from moderate/severe to mild/absent as a sign of central sensitization reduction. Our study confirmed the safety and efficacy of CGRP inhibition in real-life, high-challenging patients. Additional evidence is needed to understand the role of oxidative stress as a migraine biomarker.

Preventive migraine treatment with eptinezumab reduced acute headache medication and headache frequency to below diagnostic thresholds in patients with chronic migraine and medication‐overuse headache

ObjectiveThis post hoc analysis in patients medically diagnosed with chronic migraine (CM) and medication‐overuse headache (MOH) evaluated reductions in the use of acute headache medication (AHM) and sustained changes in the diagnostic status of CM and MOH following eptinezumab treatment in the PROMISE‐2 study.BackgroundEptinezumab, a monoclonal antibody that inhibits calcitonin gene‐related peptide, is approved in the United States for the preventive treatment of migraine. A previous analysis showed that eptinezumab reduced monthly migraine days and was well tolerated in the subgroup of PROMISE‐2 patients diagnosed with both CM and MOH.MethodsThe phase 3, double‐blind, placebo‐controlled PROMISE‐2 study (NCT02974153) randomized adults with CM to eptinezumab 100 mg, 300 mg, or placebo (administered intravenously every 12 weeks for up to two doses). MOH was prospectively diagnosed at screening by trained physicians based on 3 months of medication history and International Classification of Headache Disorders‐3β criteria. This post hoc analysis evaluated changes in total and class‐specific days of AHM usage, the percentage of patients using AHM at or above MOH diagnostic thresholds, and the percentage of patients experiencing monthly headache and migraine day frequency below diagnostic thresholds for MOH and/or CM.ResultsIn PROMISE‐2, 431/1072 (40.2%) patients with CM were diagnosed with MOH (eptinezumab 100 mg, n = 139; 300 mg, n = 147; placebo, n = 145) and were included in this analysis. Total monthly AHM use decreased from 20.6 days/month at baseline to 10.6 days/month over 24 weeks of treatment (49% decrease) with eptinezumab 100 mg, from 20.7 to 10.5 days/month (49% decrease) with eptinezumab 300 mg, and from 19.8 to 14.0 days/month (29% decrease) with placebo. Numerically greater decreases from baseline with eptinezumab were also observed for individual drug classes. In each study month, the percentages of patients who were below MOH thresholds were numerically higher for both eptinezumab doses compared with placebo, as were the percentages of patients experiencing headache and migraine frequency below CM thresholds. Of patients with available data across the entire treatment period, 29.0% (58/200) of patients treated with eptinezumab stopped meeting and remained below diagnostic thresholds for both CM and MOH during Weeks 1–24, as well as 6.3% (6/96) of patients who received placebo.ConclusionsAcross 24 weeks of treatment, eptinezumab reduced AHM use in patients diagnosed with CM and MOH. More than one‐fourth (29%) of patients treated with eptinezumab did not meet the diagnostic thresholds for either CM or MOH for the entire treatment period.

Kynurenine Pathway of Tryptophan Metabolism in Migraine and Functional Gastrointestinal Disorders

Migraine, the leading cause of disability in the population aged below 50, is associated with functional gastrointestinal (GI) disorders (FGIDs) such as functional nausea, cyclic vomiting syndrome, and irritable bowel syndrome (IBS). Conversely, changes in intestinal GI transit may cause diarrhea or constipation and are a component of the autonomic symptoms associated with pre- and post-dorsal phases of migraine attack. These mutual relationships provoke a question on a common trigger in migraine and FGIDs. The kynurenine (l-kyn) pathway (KP) is the major route for l-tryptophan (l-Trp) metabolism and transforms l-Trp into several neuroactive compounds. Changes in KP were reported in both migraine and FGIDs. Migraine was largely untreatable, but several drugs approved lately by the FDA, including monoclonal antibodies for calcitonin gene-related peptide (CGRP) and its receptor, create a hope for a breakthrough in migraine treatment. Derivatives of l-kyn were efficient in pain relief with a mechanism including CGRP inhibition. KP products are important ligands to the aryl hydrocarbon receptor (AhR), whose activation is implicated in the pathogenesis of GI and migraine. Toll-like receptors (TLRs) may play a role in migraine and IBS pathogeneses, and KP metabolites detected downstream of TLR activation may be an IBS marker. The TLR4 signaling was observed in initiating and maintaining migraine-like behavior through myeloid differentiation primary response gene 88 (MyD88) in the mouse. The aim of this review is to justify the view that KP modulation may provide common triggers for migraine and FGIDs with the involvement of TLR, AhR, and MyD88 activation.

Calcitonin gene-related peptide induces the histone H3 lysine 9 acetylation in astrocytes associated with neuroinflammation in rats with neuropathic pain.

AimsCalcitonin gene‐related peptide (CGRP) as a regulator of astrocyte activation may facilitate spinal nociceptive processing. Histone H3 lysine 9 acetylation (H3K9ac) is considered an important regulator of cytokine and chemokine gene expression after peripheral nerve injury. In this study, we explored the relationship between CGRP and H3K9ac in the activation of astrocytes, and elucidated the underlying mechanisms in the pathogenesis of chronic neuropathic pain.MethodsAstroglial cells (C6) were treated with CGRP and differentially enrichments of H3K9ac on gene promoters were examined using ChIP‐seq. A chronic constriction injury (CCI) rat model was used to evaluate the role of CGRP on astrocyte activation and H3K9ac signaling in CCI‐induced neuropathic pain. Specific inhibitors were employed to delineate the involved signaling.ResultsIntrathecal injection of CGRP and CCI increased the number of astrocytes displaying H3K9ac in the spinal dorsal horn of rats. Treatment of CGRP was able to up‐regulate H3K9ac and glial fibrillary acidic protein (GFAP) expression in astroglial cells. ChIP‐seq data indicated that CGRP significantly altered H3K9ac enrichments on gene promoters in astroglial cells following CGRP treatment, including 151 gaining H3K9ac and 111 losing this mark, which mostly enriched in proliferation, autophagy, and macrophage chemotaxis processes. qRT‐PCR verified expressions of representative candidate genes (ATG12, ATG4C, CX3CR1, MMP28, MTMR14, HMOX1, RET) and RTCA verified astrocyte proliferation. Additionally, CGRP treatment increased the expression of H3K9ac, CX3CR1, and IL‐1β in the spinal dorsal horn. CGRP antagonist and HAT inhibitor attenuated mechanical and thermal hyperalgesia in CCI rats. Such analgesic effects were concurrently associated with the reduced levels of H3K9ac, CX3CR1, and IL‐1β in the spinal dorsal horn of CCI rats.ConclusionOur findings highly indicate that CGRP is associated with the development of neuropathic pain through astrocytes‐mediated neuroinflammatory responses via H3K9ac in spinal dorsa horn following nerve injury.This study found that CGRP act on their astrocytic receptors and lead to H3K9 acetylation (H3K9ac), which are mainly associated with proliferation‐, autophagy‐, and inflammation‐related gene expression. The number of astrocytes with H3K9ac expression is increased after nerve injury. Inhibition of CGRP attenuates the development of neuropathic pain, which was accompanied by the suppression of H3K9ac, CX3CR1, and IL‐1β expression in CCI rats.

Increase in trigeminal ganglion neurons that respond to both calcitonin gene-related peptide and pituitary adenylate cyclase-activating polypeptide in mouse models of chronic migraine and posttraumatic headache.

A large body of animal and human studies indicates that blocking peripheral calcitonin gene-related peptide (CGRP) and pituitary adenylate cyclase-activating polypeptide (PACAP) signaling pathways may prevent migraine episodes and reduce headache frequency. To investigate whether recurring migraine episodes alter the strength of CGRP and PACAP signaling in trigeminal ganglion (TG) neurons, we compared the number of TG neurons that respond to CGRP and to PACAP (CGRP-R and PACAP-R, respectively) under normal and chronic migraine-like conditions. In a mouse model of chronic migraine, repeated nitroglycerin (NTG) administration significantly increased the number of CGRP-R and PACAP-R neurons in TG but not dorsal root ganglia. In TG neurons that express endogenous αCGRP, repeated NTG led to a 7-fold increase in the number of neurons that respond to both CGRP and PACAP (CGRP-R&PACAP-R). Most of these neurons were unmyelinated C-fiber nociceptors. This suggests that a larger fraction of CGRP signaling in TG nociceptors may be mediated through the autocrine mechanism, and the release of endogenous αCGRP can be enhanced by both CGRP and PACAP signaling pathways under chronic migraine condition. The number of CGRP-R&PACAP-R TG neurons was also increased in a mouse model of posttraumatic headache (PTH). Interestingly, low-dose interleukin-2 treatment, which completely reverses chronic migraine-related and PTH-related behaviors in mouse models, also blocked the increase in both CGRP-R and PACAP-R TG neurons. Together, these results suggest that inhibition of both CGRP and PACAP signaling in TG neurons may be more effective in treating chronic migraine and PTH than targeting individual signaling pathways.

Eptinezumab Demonstrated Efficacy in Sustained Prevention of Episodic and Chronic Migraine Beginning on Day 1 After Dosing.

ObjectiveTo determine the onset of preventive efficacy with eptinezumab in patients with migraine.BackgroundEptinezumab is a monoclonal antibody inhibiting calcitonin gene‐related peptide approved as an intravenously administered treatment for the prevention of migraine.MethodsPatients who received eptinezumab 100 mg, eptinezumab 300 mg, or placebo in PROMISE7‐1 (episodic migraine; 100 mg, n = 221; 300 mg, n = 222; placebo, n = 222) or PROMISE7‐2 (chronic migraine; 100 mg, n = 356; 300 mg, n = 350; placebo, n = 366) were included. Testing of the percentage of patients with a migraine on day 1 after dosing was prespecified and alpha‐controlled. In further exploration of this prespecified endpoint, a post hoc closed testing procedure, which controlled the false‐positive (type 1) error rate, provided a statistically rigorous evaluation of migraine prevention onset. The procedure involved up to 84 tests of significance, all of which were performed in sequence until the first nonsignificant result.ResultsFor both studies, all tests for significance for eptinezumab 100 and 300 mg, from days 1‐84 through day 1 alone, achieved nominal significance (P < .05), indicating that eptinezumab was fully effective beginning on day 1. Over each interval, the treatment effect was comparable to the effect over weeks 1‐12. Mean changes from baseline in monthly migraine days for the primary endpoint period ranged from −3.9 to −4.9, −4.1 to −4.9, and −2.2 to −3.2 for eptinezumab 100, 300 mg, and placebo, respectively, in PROMISE7‐1 and from −7.2 to −8.0, −7.9 to −8.2, and −4.3 to −5.6, respectively, in PROMISE7‐2. The difference from placebo (95% confidence interval) in day 1 treatment effect was −2.2 (−4.1, −0.3) and −2.5 (−4.4, −0.6) days/month for eptinezumab 100 and 300 mg, respectively, in PROMISE7‐1, and was −3.8 (−5.6, −2.0) and −4.0 (−5.8, −2.1) days/month for 100 and 300 mg, respectively, in PROMISE7‐2.ConclusionsThe migraine preventive effect of eptinezumab is rapid and sustained in patients with episodic or chronic migraine, with onset of optimal preventive efficacy observed on the day following the initial dose.

WHAT A MIGRAINE! CALCITONIN GENE-RELATED PEPTIDE ANTAGONISM AS A POTENTIAL CAUSE OF INTERSTITIAL PNEUMONITIS

SESSION TITLE: Fellows Diffuse Lung Disease SESSION TYPE: Fellow Case Reports PRESENTED ON: October 18-21, 2020 INTRODUCTION: Calcitonin gene-related peptide (CGRP) is a neuropeptide found in neuroendocrine cells, lymphoid tissue, blood vessels, and sensory C fibers within pulmonary tissue. It is thought to have a homeostatic effect through epithelial repair, vasoregulation, and an anti-inflammatory effect. CGRP is also expressed in multiple other organ systems, including the nervous system. Recently, inhibition of CGRP within the nervous system has been found to be an effective treatment modality for migraines. We present a case of possible drug induced interstitial disease shortly following initiation of galcanezumab, a monoclonal inhibitor of CGRP. CASE PRESENTATION: A 46 year old female with a history of migraines presented to the pulmonary clinic for evaluation following failure of treatment for presumed community acquired pneumonia. The patient reported 4-6 weeks of progressive cough, dyspnea on exertion, and pleuritic chest pain to the point where she was unable to climb a single flight of stairs. Prior plain chest films were revealing for bilateral scattered interstitial opacities concerning for infectious process. A high resolution CT scan was obtained at the time of pulmonary evaluation revealing a non-UIP pattern. Spirometry was revealing for moderately severe restrictive pattern with severe reduction in DLCO without prior studies for comparison. An ILD questionnaire was performed along with a hypersensitivity pneumonitis panel and extensive serological evaluation for a rheumatologic etiology without a causal finding. Further discussion with patient was revealing for recent initiation of galcanezumab shortly before onset of symptoms. Given her negative evaluation to date and marked functional limitation, she was initiated on prednisone for presumed drug induced etiology and galcanezumab was discontinued. Within two weeks, the patient had a significant improvement in symptoms with normal repeat spirometry and only mild reduction in DLCO. She continued to improve with complete symptomatic resolution at four weeks and near resolution radiographically at 12 weeks. DISCUSSION: Drug induced interstitial pneumonitis is a disease of exclusion. With extensive negative evaluation, close temporal association between initiation of drug and her symptoms and rapid improvement with prednisone and cessation of the drug, it is likely that patient had drug induced interstitial disease secondary to initiation of galcanezumab. CONCLUSIONS: Animal models support this possibility by showing decreased CGRP levels in pulmonary tissue exposed to crystalline silica and crocidolite, both known causes of interstitial lung disease. As such, it is plausible that CGRP plays a role within interstitial pulmonary disease and may have been an unintended target in this case. Given these findings, we determined galcanezumab to be the etiology of her interstitial pneumonitis, which would be the first reported case in the literature. Reference #1: Morimoto Y, Ogami A, Nagatomo H, et al. Calcitonin gene-related peptide (CGRP) as hazard marker for lung injury induced by dusts. Inhal Toxicol. 2007;19(3):283-289. doi:10.1080/08958370601069364 DISCLOSURES: No relevant relationships by Tyler Church, source=Admin input No relevant relationships by Arthur Holtzclaw, source=Admin input No relevant relationships by Donovan Mabe, source=Web Response

Optogenetic stimulation of the motor cortex alleviates neuropathic pain in rats of infraorbital nerve injury with/without CGRP knock-down

BackgroundPrevious studies have reported that electrical stimulation of the motor cortex is effective in reducing trigeminal neuropathic pain; however, the effects of optical motor cortex stimulation remain unclear.ObjectiveThe present study aimed to investigate whether optical stimulation of the primary motor cortex can modulate chronic neuropathic pain in rats with infraorbital nerve constriction injury.MethodsAnimals were randomly divided into a trigeminal neuralgia group, a sham group, and a control group. Trigeminal neuropathic pain was generated via constriction of the infraorbital nerve and animals were treated via selective inhibition of calcitonin gene-related peptide in the trigeminal ganglion. We assessed alterations in behavioral responses in the pre-stimulation, stimulation, and post-stimulation conditions. In vivo extracellular recordings were obtained from the ventral posteromedial nucleus of the thalamus, and viral and α-CGRP expression were investigated in the primary motor cortex and trigeminal ganglion, respectively.ResultsWe found that optogenetic stimulation significantly improved pain behaviors in the trigeminal neuralgia animals and it provided more significant improvement with inhibited α-CGRP state than active α-CGRP state. Electrophysiological recordings revealed decreases in abnormal thalamic firing during the stimulation-on condition.ConclusionOur findings suggest that optical motor cortex stimulation can alleviate pain behaviors in a rat model of trigeminal neuropathic pain. Transmission of trigeminal pain signals can be modulated via knock-down of α-CGRP and optical motor cortex stimulation.

Anti-migraine Calcitonin Gene-Related Peptide Receptor Antagonists Worsen Cerebral Ischemic Outcome in Mice.

ObjectiveCalcitonin gene–related peptide (CGRP) pathway inhibitors are emerging treatments for migraine. CGRP‐mediated vasodilation is, however, a critical rescue mechanism in ischemia. We, therefore, investigated whether gepants, small molecule CGRP receptor antagonists, worsen cerebral ischemia.MethodsMiddle cerebral artery was occluded for 12 to 60 minutes in mice. We compared infarct risk and volumes, collateral flow, and neurological deficits after pretreatment with olcegepant (single or 10 daily doses of 0.1–1mg/kg) or rimegepant (single doses of 10–100mg/kg) versus vehicle. We also determined their potency on CGRP‐induced relaxations in mouse and human vessels, in vitro.ResultsOlcegepant (1mg/kg, single dose) increased infarct risk after 12‐ to 20‐minute occlusions mimicking transient ischemic attacks (14/19 vs 6/18 with vehicle, relative risk = 2.21, p < 0.022), and doubled infarct volumes (p < 0.001) and worsened neurological deficits (median score = 9 vs 5 with vehicle, p = 0.008) after 60‐minute occlusion. Ten daily doses of 0.1 to 1mg/kg olcegepant yielded similar results. Rimegepant 10mg/kg increased infarct volumes by 60% after 20‐minute ischemia (p = 0.03); 100mg/kg caused 75% mortality after 60‐minute occlusion. In familial hemiplegic migraine type 1 mice, olcegepant 1mg/kg increased infarct size after 30‐minute occlusion (1.6‐fold, p = 0.017). Both gepants consistently diminished collateral flow and reduced reperfusion success. Olcegepant was 10‐fold more potent than rimegepant on CGRP‐induced relaxations in mouse aorta.InterpretationGepants worsened ischemic stroke in mice via collateral dysfunction. CGRP pathway blockers might thus aggravate coincidental cerebral ischemic events. The cerebrovascular safety of these agents must therefore be better delineated, especially in patients at increased risk of ischemic events or on prophylactic CGRP inhibition. ANN NEUROL 2020;88:771–784

Triptan efficacy does not predict onabotulinumtoxinA efficacy but improves with onabotulinumtoxinA response in chronic migraine patients

Chronic migraine (CM) is a highly disabling primary headache. Botulinum toxin (onabotulinumtoxinA) is effective for treatment of CM, with ~ 50% of patients responding after 24 weeks. A response predictor would prevent unnecessary treatments. Inhibiting calcitonin gene related peptide (CGRP) release from trigeminal nociceptive fibres is one of the modes of acting discussed for onabotulinumtoxinA in CM. Therefore, we hypothesized that the response to triptans might predict response to onabotulinumtoxinA. Contrariwise, onabotulinumtoxinA treatment might affect triptan efficacy. 49 CM patients scheduled for their first onabotulinumtoxinA treatment were included. Before (T0) and three months after (T1) onabotulinumtoxinA treatment, patients rated triptan efficacy and indicated number of headache days/month. At T1, patients additionally rated onabotulinumtoxinA efficacy. Headache days/month were on average reduced by 7.1 ± 7.0 days from T0 to T1 (p < 0.001). Triptan efficacy ratings at T0 did not predict onabotulinumtoxinA efficacy ratings at T1 (p = 0.19) or reduction of headache days (p = 0.37). However, triptan efficacy significantly improved from T0 to T1 in onabotulinumtoxinA responders (p < 0.001) but not in non-responders (p = 1.00). Triptan efficacy did not predict response to onabotulinumtoxinA in CM. However, triptan efficacy increased after successful onabotulinumtoxinA treatment. This supports the hypothesis that efficacy of acute migraine treatment with triptans improves with effective migraine prophylaxis.