Calcitonin gene-related peptide in peripheral blood as a biomarker for migraine

Calcitonin gene-related peptide in newly diagnosed idiopathic intracranial hypertension: a prospective, cross-sectional, case-control study of cerebrospinal fluid and plasma

BACKGROUND

Calcitonin Gene-Related Peptide (CGRP) is involved in migraine pain signaling, and blockage hereof is effective in migraine treatment. Headache in idiopathic intracranial hypertension (IIH) is often migraine-like but the underlying mechanisms are not understood. We report levels of CGRP in plasma and cerebrospinal fluid (CSF) of patients with newly diagnosed IIH to elucidate CGRP involvement in the pathogenesis of headache in IIH.

METHOD

We consecutively enrolled patients suspected of having IIH in a prospective cohort at two Danish tertiary headache centers. Patients are confirmed to have IIH or disproven of it (non-IIH). We included non-IIH with primary headache disorders as headache controls to IIH cases. We also recruited sex-, age- and BMI-matched healthy controls (HC). All participants had CSF and blood drawn and CGRP was analyzed using a validated radioimmunoassay. CSF plasma-ratios were calculated. Between-group levels were compared with ANOVA or Kruskal-Walli's test. In sub-analyses we restricted comparison of HC to non-IIH/IIH with chronic migraine; we also compared IIH with versus without headache. We correlated CGRP to lumbar opening pressure (OP), and BMI, and assessed the correlation between CGRP in plasma and CSF. Generalized or linear regression was applied to adjust for confounding by BMI, age, and active smoking.

RESULTS

Comparing 97 patients with IIH, 52 non-IIH, and 37 HC, we found no between-group differences in CGRP levels in plasma (p = 0.78), CSF (p = 0.79), or in CSF:plasma-ratio (p = 0.13). Adjusting for BMI, age, and smoking yielded similar results. CGRP levels were neither associated with having a migraine phenotype or chronic headache, nor with having any headache versus no headache in IIH. CGRP in plasma correlated with CGRP in CSF (p < 0.0001). CGRP did not correlate with OP or BMI.

CONCLUSION

CGRP levels in plasma and CSF and their ratios were comparable in IIH, non-IIH patients with headache, and sex-, age-, and BMI-matched HC. CGRP in plasma correlated with CGRP in CSF. Due to methodology, we probably measured basal resting CGRP. The role of CGRP in IIH-headache needs further clarification. A headache preventive effect in IIH of anti-CGRP targeted therapy remains a relevant unexplored area.

Treating episodic migraine with precision: the evolving landscape of targeted therapies driven by insights in disease biology

INTRODUCTION

Migraine is a disabling neurological disorder with a complex neurobiology. It appears as a cyclic disorder of sensory processing, affecting multiple systems beyond nociception. Overlapping mechanisms, including dysfunctional processing of sensory input from brain structures are involved in the generation of attacks.

AREAS COVERED

This review provides a comprehensive synthesis on migraine neurobiology, which was additionally informed by search of research databases (PubMed, ClinicalTrials.gov). Findings from the most recent literature are integrated in a pathophysiological framework. By combining mechanistic insights and clinical trial data, this review highlights the trajectory of precision medicine in migraine treatment, offering a perspective on the near future of targeted and individualized therapeutic strategies.

EXPERT OPINION

Recent advances in migraine neurobiology offer potential solutions to longstanding challenges. While targeted CGRP therapies have shown promise by addressing specific mechanisms, the pathophysiology of migraine suggests that combination therapies targeting multiple pathways could be beneficial in migraine prevention. The growing diversity of treatment options presents challenges in therapy selection, underscoring the need for predictive biomarkers. These innovations can optimize treatment strategies and improve patient outcomes. As the field progresses, personalized, multimodal approaches are poised to become the standard of care, significantly advancing precision medicine in this area.

A narrative review of autophagy in migraine

Background and objective

Autophagy is a natural process regulated by autophagy-related genes in eukaryotic cells that involves the degradation of cytoplasmic proteins and old or damaged organelles via the lysosomal pathway to help maintain cell homeostasis. Previous studies have suggested a potential association between autophagy and migraine, while the underlying mechanisms remain unclear. This review seeks to evaluate the possible involvement of autophagy in the pathophysiology of migraine, aiming to clarify its role and implications for future research and therapeutic strategies.

Methods

A search in PubMed was conducted for English-language articles until December 5, 2024. Key terms of "autophagy," "migraine," "microglia," "neurogenic inflammation," "central sensitization," "mitophagy" and "neuropathic pain" in different combinations.

Results

In the context of migraine, the activation of the phosphoinositide 3-kinase (PI3K)/protein kinase B (PKB/Akt) signaling pathway exerts a direct influence on the mammalian target of rapamycin (mTOR), leading to a reduction in autophagy levels. Moreover, the stimulation of purinergic ligand-gated ion channel type 7 receptor (P2X7R) in microglia can hinder autophagy by interfering with the fusion of autophagosomes and lysosomes, which impedes the degradation of substrates within the autophagolysosome. Increased levels of calcitonin gene-related peptide (CGRP) may also modulate autophagy through the Akt/mTOR or protein kinase A (PKA)/mTOR signaling pathways. Additionally, research indicates that mitophagy may be partially impaired in individuals suffering from migraine. Furthermore, autophagy could contribute to the dysregulation of synaptic plasticity by influencing the processes of long-term potentiation (LTP) and long-term depression (LTD), both of which are associated with central sensitization in chronic migraine.

Conclusion

These findings suggest that autophagy may play an important role in the pathophysiology of migraine, particularly in its development and central sensitization. Research on autophagy modulators related to migraine will provide valuable insights for treatment strategies.

Plasma calcitonin gene-related peptide levels in idiopathic intracranial hypertension: an exploratory study

BACKGROUND

Idiopathic intracranial hypertension (IIH) is a debilitating condition characterized by increased intracranial pressure often presenting with chronic migraine-like headache. Calcitonin gene-related peptide (CGRP) plays an important pathophysiological role in primary headaches such as migraine, whilst its role in IIH has not yet been established.

METHODS

This longitudinal exploratory study included patients with IIH, episodic migraine (EM) in a headache-free interval and healthy controls (HC). Blood samples were collected from a cubital vein and plasma CGRP (pCGRP) levels were measured by standardized ELISA.

RESULTS

A total of 26 patients with IIH (mean age 33.2 years [SD 9.2], 88.5% female, median BMI 34.8 kg/m2 [IQR 30.0-41.4]), 30 patients with EM (mean age 27.6 years [7.5], 66.7% female) and 57 HC (mean age 25.3 years [5.2], 56.1% female) were included. pCGRP levels displayed a wide variation in IIH as well as in EM and HC on a group-level. Within IIH, those with migraine-like headache had significantly higher pCGRP levels than those with non-migraine-like headache (F(2,524) = 84.79; p < 0.001) and headache absence (F(2,524) = 84.79; p < 0.001) throughout the observation period, explaining 14.7% of the variance in pCGRP levels. CGRP measurements showed strong intraindividual agreement in IIH (ICC 0.993, 95% CI 0.987-0.996, p < 0.001). No association was found between pCGRP levels and ophthalmological parameters.

CONCLUSIONS

Although interindividual heterogeneity of pCGRP levels is generally high, migraine-like headache seems to be associated with higher pCGRP levels. CGRP may play a role in the headache pathophysiology at least in a subgroup of IIH.

Posttraumatic headache is a distinct headache type from migraine

PURPOSE OF REVIEW

Posttraumatic headache (PTH), a headache that develops within 7 days of a causative injury, is one of the most common secondary headaches, mostly attributed to mild traumatic brain injury (mTBI). Because presence of preinjury headache is a risk factor for developing PTH and PTH symptoms often resemble migraine or tension-type headache, the association between PTH and primary headaches has attracted attention from clinicians and scientists.

RECENT FINDINGS

Recent studies on epidemiological aspects, headache features, risk factors, imaging characteristics, and response to treatment, suggest overlapping features and distinct objective findings in PTH compared to migraine.

SUMMARY

We argue that PTH is distinct from migraine. Therefore, PTH epidemiology, pathophysiology, diagnosis, treatment, and prognosis should continue to be investigated separately from migraine.

Synergism of Anti-CGRP Monoclonal Antibodies and OnabotulinumtoxinA in the Treatment of Chronic Migraine: A Real-World Retrospective Chart Review

BACKGROUND

Many patients with chronic migraine do not achieve clinically meaningful improvement in their headache frequency with monotherapy. The burden associated with chronic migraine calls for a multifaceted treatment approach targeting multiple aspects of migraine pathophysiology.

OBJECTIVE

The aim of this study was to evaluate the effect of concurrent anti-calcitonin gene-related peptide (CGRP) monoclonal antibody (mAb) and onabotulinumtoxinA (onabot) treatment on median monthly migraine days (MMD) in patients with chronic migraine, through a retrospective study.

METHODS

The electronic medical records of Cleveland Clinic patients either concurrently (dual therapy) or consecutively (monotherapy) treated with anti-CGRP mAbs and onabot between June 2018 and November 2021 were extracted. Only adult patients (≥ 18 years of age) were included in this study. MMDs for 194 concurrently treated (86.6% female and a median [interquartile range] age of 51 [41-61] years) and 229 consecutively treated (88.2% female and median age of 47 [IQR 39-57] years) patients were examined at baseline, after first therapy of either anti-CGRP mAb or onabot, and following dual therapy for 3 consecutive months. The reduction of MMDs for each treatment group were compared. The same approach was utilized to compare consecutive monotherapy at separate times (n = 229) and dual-therapy groups.

RESULTS

The initial treatment of the dual-therapy group reduced the median (IQR) MMDs from 30 (30-30) to 15 (12-30) [p < 0.0001]. After initiation of dual therapy, the median MMDs was further decreased from 15 (12-30) to 8 (3-22) [p < 0.0001]. A majority [132/194 (68.0%)] of the dual-therapy patients reported a ≥ 50% reduction in MMD and 90/194 (46.4%) reported a ≥ 75% reduction. For the consecutive monotherapy group, median MMDs changed from a baseline of 30 (25-30) to 15 (8-25) from onabot monotherapy and decreased from 25 (15-30) to 12 (4-25) after anti-CGRP mAb monotherapy. Almost half (113/229 [49.3%] from onabot, and 104/229 [45.4%] from anti-CGRP mAb) of these patients achieved a ≥ 50% reduction in MMDs and a minority (38/229 [16.6%] from onabot, and 45/229 [19.7%] from anti-CGRP mAb) achieved a reduction of ≥ 75%. Additionally, dual therapy showed significant improvement in MMDs compared with monotherapy of either treatment (p < 0.0001).

CONCLUSION

Dual therapy of anti-CGRP mAbs and onabot may be more efficacious than monotherapy, possibly due to their synergistic mechanisms of action.

Expression of NF-κB-associated lncRNAs in different types of migraine

PURPOSE

NF-κB partakes in the pathophysiology of neurologic conditions. We quantified levels of NF-κB-associated genes in 119 patients with migraine versus healthy controls.

METHODS

We measured levels of NF-κB-associated genes in 42 patients with migraine compared with age- and sex-matched controls.

RESULTS

Comparison between patients without aura and controls revealed down-regulation of PACER [expression ratio (95% CI) 0.15 (0.06-0.36), P value < 0.0001]. Similar results were detected when comparing expression of PACER in patients with aura and controls [expression ratio (95% CI) 0.05 (0.02-0.12), P value < 0.0001]. Both DILC and CEBPA were over-expressed in patients with aura [expression ratio (95% CI) 4.9 (2.96-7.83), P value < 0.0001 and expression ratio (95% CI) 3.65 (2.39-5.24), P value < 0.0001, respectively] and in patients without aura compared with controls [expression ratio (95% CI) 3.6 (2.21-5.69), P value < 0.0001 and expression ratio (95% CI) 4.5 (2.53-7.11), P value < 0.0001, respectively]. ADINR was over-expressed in patients with aura [expression ratio (95% CI) 4.98 (3.09-8.33), P value < 0.0001] as well as patients without aura compared with controls [expression ratio (95% CI) 13.15 (7.41-23.58), P value < 0.0001]. Notably, ADINR levels were lower in patients with aura compared with patients without aura. When comparing ATG5 levels in patients with aura and controls, significant up-regulation was detected [expression ratio (95% CI) 4.4 (3.01-6.32), P value < 0.0001]. This pattern was also detected in patients without aura compared with controls [expression ratio (95% CI) 3.5 (2.28-5.35), P < 0.0001]. Finally, expression of DICER1-AS1 was elevated in patients with aura compared with patients without aura [expression ratio (95% CI) 2.47 (1.14-5.85), P = 0.03]. This lncRNA was under-expressed in patients without aura compared with controls [expression ratio (95% CI) 0.4 (0.21-1.31), P = 0.03]. CEBPA, ATG5 and ADINR had the best AUC values for distinguishing patients with aura from controls (AUC values = 0.91, 0.85 and 0.83, respectively). The AUC values for separation between patients without aura and controls were 0.90, 0.86 and 0.75 for CEBPA, ATG5 and ADINR, respectively.

CONCLUSION

Taken together, several genes in the NF-κB pathway has been revealed to be dysregulated in migraineurs and expression of these genes can be used as markers for this neurological condition.

Serum Calcitonin Gene-Related Peptide Is Elevated in Patients With Migraine and Ophthalmoplegia

BACKGROUND

There is ongoing debate about whether the oculomotor (III), trochlear (IV), or abducens (VI) nerve paresis in patients with migraine is directly attributable to migraine (ophthalmoplegic migraine [OM]) or is due to an inflammatory neuropathy (recurrent painful ophthalmoplegic neuropathy [RPON]). As migraine is associated with elevated serum calcitonin gene-related peptide (CGRP) levels, we studied serum CGRP levels among patients with OM/RPON to determine whether they are elevated during and between attacks. This is the first study assessing CGRP levels in the serum of patients with OM/RPON.

METHODS

The aim of this case-control study was to assess serum CGRP levels in patients with ophthalmoplegia and a headache consistent with migraine according to ICHD-3 criteria. Serum CGRP levels were measured during the ictal and interictal phases in 15 patients with OM/RPON and compared with age-matched and sex-matched controls without migraine (12 patients).

RESULTS

The median serum CGRP levels were significantly elevated ( P = 0.021) during the ictal phase (37.2 [36.4, 43.6] ng/L) compared with controls (32.5 [30.1, 37.3] ng/L). Serum CGRP levels during the attack correlated with the total duration of ophthalmoplegia. A CGRP level of 35.5 ng/L in the ictal phase of the attack had a sensitivity of 86.7% and specificity of 75.0% in diagnosing a patient with OM/RPON.

CONCLUSIONS

Elevated serum CGRP levels during the ictal phase of OM/RPON favor migraine as the underlying cause of episodic headache with ophthalmoplegia.

Shared and independent roles of CGRP and PACAP in migraine pathophysiology

The neuropeptides calcitonin gene-related peptide (CGRP) and pituitary adenylate cyclase-activating polypeptide (PACAP) have emerged as mediators of migraine pathogenesis. Both are vasodilatory peptides that can cause migraine-like attacks when infused into people and migraine-like symptoms when injected into rodents. In this narrative review, we compare the similarities and differences between the peptides in both their clinical and preclinical migraine actions. A notable clinical difference is that PACAP, but not CGRP, causes premonitory-like symptoms in patients. Both peptides are found in distinct, but overlapping areas relevant to migraine, most notably with the prevalence of CGRP in trigeminal ganglia and PACAP in sphenopalatine ganglia. In rodents, the two peptides share activities, including vasodilation, neurogenic inflammation, and nociception. Most strikingly, CGRP and PACAP cause similar migraine-like symptoms in rodents that are manifested as light aversion and tactile allodynia. Yet, the peptides appear to act by independent mechanisms possibly by distinct intracellular signaling pathways. The complexity of these signaling pathways is magnified by the existence of multiple CGRP and PACAP receptors that may contribute to migraine pathogenesis. Based on these differences, we suggest PACAP and its receptors provide a rich set of targets to complement and augment the current CGRP-based migraine therapeutics.

Calcitonin Gene-Related Peptide and Adrenomedullin Levels During Ictal and Interictal Periods in Patients With Migraine

Background Peptides related to calcitonin gene-related peptide (CGRP) have been suggested to have a role in migraine. Adrenomedullin (AM) might be a candidate molecule because it is related to pain pathways in the peripheral and central nervous systems and uses the same receptors as CGRP. Methodology In this study, we examined the serum CGRP and AM levels during unprovoked ictal and interictal periods of 30 migraine patients as well as 25 healthy controls. Another focus of this study was on the association of CGRP and AM levels with clinical features. Results Mean serum AM levels were 15.80 pg/mL (11.91-21.43 pg/mL) in the ictal and 15.85 pg/mL (12.25-19.29 pg/mL) in the interictal periods in the migraine group and 13.36 pg/mL (10.84-17.18 pg/mL) in the control group. Mean serum CGRP levels were 2.93 pg/mL (2.45-3.90 pg/mL) in the ictal and 3.25 pg/mL (2.85-4.67 pg/mL) in the interictal periods in the migraine group and 3.03 pg/mL (2.48-3.80 pg/mL) in the control group. There were no statistical differences between ictal and/or interictal AM and CGRP levels (p = 0.558 and p = 0.054, respectively) which were also comparable with the results of the control group (p = 0.230, p = 0.295, p = 0.987, p = 0.139, respectively). Ictal serum CGRP and/or AM levels did not correlate with any of the reported clinical features. Conclusions Serum AM and CGRP levels are similar in interictal and unprovoked ictal periods in migraine patients and as well in controls. These results do not indicate that these molecules do not have a role in migraine pathophysiology. Considering the broad mechanisms of action of peptides in the CGRP family, further studies are needed in larger cohorts.

Migraine and obesity: what is the real direction of their association?

INTRODUCTION

In recent decades, studies have addressed the issue of how migraine and obesity are related and have suggested obesity as a risk factor for migraine headache. However, the exact direction of this relationship remains under debate. In this review, the authors summarize the evidence that have suggested migraine as a risk factor for obesity and overweightness.

AREAS COVERED

This article reviews the results of the previous research published on PubMed and Scopus databases (from 2000 to 2020) concerning the association between migraine and obesity to determine the actual direction of their association. Special attention has been given to the common mechanistic pathways involved in the pathophysiology of migraine and obesity.

EXPERT OPINION

The majority of research conducted thus far has considered obesity as a risk factor for migraine. However, because of the cross-sectional design of available research, we cannot be certain of the proposed direction of this association. There is evidence supporting the hypothesis that obesity can serve as a consequence of migraine through the effects of neuropeptides, inflammatory mediators, adipokines, gut microbiota and modifications in eating behavior and lifestyle. However, the real direction of the relationship between migraine and obesity should be further investigated in large prospective studies.

Preclinical Studies of Posttraumatic Headache and the Potential Therapeutics

Posttraumatic headache (PTH) attributed to traumatic brain injury (TBI) is a secondary headache developed within 7 days after head injury, and in a substantial number of patients PTH becomes chronic and lasts for more than 3 months. Current medications are almost entirely relied on the treatment of primary headache such as migraine, due to its migraine-like phenotype and the limited understanding on the PTH pathogenic mechanisms. To this end, increasing preclinical studies have been conducted in the last decade. We focus in this review on the trigeminovascular system from the animal studies since it provides the primary nociceptive sensory afferents innervating the head and face region, and the pathological changes in the trigeminal pathway are thought to play a key role in the development of PTH. In addition to the pathologies, PTH-like behaviors induced by TBI and further exacerbated by nitroglycerin, a general headache inducer through vasodilation are reviewed. We will overview the current pharmacotherapies including calcitonin gene-related peptide (CGRP) monoclonal antibody and sumatriptan in the PTH animal models. Given that modulation of the endocannabinoid (eCB) system has been well-documented in the treatment of migraine and TBI, the therapeutic potential of eCB in PTH will also be discussed.

Headache-related circuits and high frequencies evaluated by EEG, MRI, PET as potential biomarkers to differentiate chronic and episodic migraine: Evidence from a systematic review

Background

The diagnosis of migraine is mainly clinical and self-reported, which makes additional examinations unnecessary in most cases. Migraine can be subtyped into chronic (CM) and episodic (EM). Despite the very high prevalence of migraine, there are no evidence-based guidelines for differentiating between these subtypes other than the number of days of migraine headache per month. Thus, we consider it timely to perform a systematic review to search for physiological evidence from functional activity (as opposed to anatomical structure) for the differentiation between CM and EM, as well as potential functional biomarkers. For this purpose, Web of Science (WoS), Scopus, and PubMed databases were screened.

Findings

Among the 24 studies included in this review, most of them (22) reported statistically significant differences between the groups of CM and EM. This finding is consistent regardless of brain activity acquisition modality, ictal stage, and recording condition for a wide variety of analyses. That speaks for a supramodal and domain-general differences between CM and EM that goes beyond a differentiation based on the days of migraine per month. Together, the reviewed studies demonstrates that electro- and magneto-physiological brain activity (M/EEG), as well as neurovascular and metabolic recordings from functional magnetic resonance imaging (fMRI) and positron emission tomography (PET), show characteristic patterns that allow to differentiate between CM and EM groups.

Conclusions

Although a clear brain activity-based biomarker has not yet been identified to distinguish these subtypes of migraine, research is approaching headache specialists to a migraine diagnosis based not only on symptoms and signs reported by patients. Future studies based on M/EEG should pay special attention to the brain activity in medium and fast frequency bands, mainly the beta band. On the other hand, fMRI and PET studies should focus on neural circuits and regions related to pain and emotional processing.

Short Report of Longitudinal CGRP-Measurements in Migraineurs During a Hypoxic Challenge

Background

Calcitonin gene related peptide (CGRP) plays a key role in the pathophysiology of migraine and is therefore considered a potential biomarker for primary headache disorders. The challenge remaining is establishing standardized protocols for its assessment in various extracellular compartments and identifying pathological situations associated with an increase in CGRP.

Methods

We performed longitudinal measurements of CGRP plasma levels in 30 volunteers with the diagnosis of episodic migraine with and without aura under controlled circumstances during an induced migraine attack under a hypoxic challenge. Blood samples were collected from a cubital vein and CGRP plasma levels measured using ELISA.

Results

CGRP levels varied significantly between the subjects at baseline (15.48–1,889.31 pg/ml) but were neither associated with socio-demographic data nor with headache/migraine frequency or intensity collected before hypoxic exposure. CGRP levels during hypoxia fluctuated around baseline and increased with prolonged hypoxia but did not differ significantly in subjects with migraine or headache compared to those without. However, subjects experiencing migraine without aura showed significantly higher levels than those with aura. Ictal CGRP levels were increased in females, in subjects with a negative family history regarding headaches, in those older than 30 years of age or with a recent headache attack before the experiment (p < 0.05).

Conclusion

CGRP plasma levels seem to be highly variable even at baseline in migraine patients and increased during hypoxic challenge and migraine attacks. This is the first in human longitudinal measurement of peripheral CGRP levels during induced migraine attacks using a highly standardized protocol.

Is calcitonin gene-related peptide a reliable biochemical marker of migraine?

PURPOSE OF REVIEW

The aim of this study was to provide an overview of clinical studies on calcitonin gene-related peptide (CGRP) measurements in body fluids of migraine patients and to discuss the validity of CGRP measurement as a clinical biomarker of migraine.

RECENT FINDINGS

Several studies have reported increased CGRP levels in venous blood, saliva and tear fluid of migraine patients compared with healthy controls and in migraine patients during attacks compared with the interictal state, suggesting that CGRP may be a feasible biomarker of migraine. However, the findings of studies investigating CGRP levels in migraine patients are generally conflicting and measurements of CGRP levels are challenged by several methodological issues. Reported differences in CGRP levels between patients with chronic migraine relative to episodic migraine have also been inconsistent. There is also a well documented involvement of CGRP in several nonmigraine pain disorders, including cluster headache and common pain conditions such as osteoarthritis.

SUMMARY

Current evidence does not justify the usage of CGRP levels as a biomarker for diagnosing migraine or for determining the severity of the disease in individual patients. However, CGRP measurements could prove useful in the future as clinically relevant biomarkers for predicting the response to therapy, including anti-CGRP migraine drugs.

Tear film and ocular surface neuropeptides: Characteristics, synthesis, signaling and implications for ocular surface and systemic diseases

Ocular surface neuropeptides are vital molecules primarily involved in maintaining ocular surface integrity and homeostasis. They also serve as communication channels between the nervous system and the immune system, maintaining the homeostasis of the ocular surface. Tear film and ocular surface neuropeptides have a role in disease often due to abnormalities in their synthesis (either high or low production), signaling through defective receptors, or both. This creates imbalances in otherwise normal physiological processes. They have been observed to be altered in many ocular surface and systemic diseases including dry eye disease, ocular allergy, keratoconus, LASIK-induced dry eye, pterygium, neurotrophic keratitis, corneal graft rejection, microbial keratitis, headaches and diabetes. This review examines the characteristics of neuropeptides, their synthesis and their signaling through G-protein coupled receptors. The review also explores the types of neuropeptides within the tears and ocular surface, and how they change in ocular and systemic diseases.

Metabolic profile changes in serum of migraine patients detected using 1H-NMR spectroscopy

Background

Migraine is a common brain disorder but reliable diagnostic biomarkers in blood are still lacking. Our aim was to identify, using proton nuclear magnetic resonance (¹H-NMR) spectroscopy, metabolites in serum that are associated with lifetime and active migraine by comparing metabolic profiles of patients and controls.

Methods

Fasting serum samples from 313 migraine patients and 1512 controls from the Erasmus Rucphen Family (ERF) study were available for ¹H-NMR spectroscopy. Data was analysed using elastic net regression analysis.

Results

A total of 100 signals representing 49 different metabolites were detected in 289 cases (of which 150 active migraine patients) and 1360 controls. We were able to identify profiles consisting of 6 metabolites predictive for lifetime migraine status and 22 metabolites predictive for active migraine status. We estimated with subsequent regression models that after correction for age, sex, BMI and smoking, the association with the metabolite profile in active migraine remained. Several of the metabolites in this profile are involved in lipid, glucose and amino acid metabolism.

Conclusion

This study indicates that metabolic profiles, based on serum concentrations of several metabolites, including lipids, amino acids and metabolites of glucose metabolism, can distinguish active migraine patients from controls.

Supplementary Information

The online version contains supplementary material available at 10.1186/s10194-021-01357-w.

Efficacy of calcitonin gene-related peptide (CGRP) receptor blockers in reducing the number of monthly migraine headache days (MHDs): A network meta-analysis of randomized controlled trials

The Global burden of disease study ranked migraine as the sixth most common disorder worldwide in 2016, with significant social and economic sequelae. In this study, we assessed the efficacy of different Calcitonin gene-related peptide (CGRP) receptor blockers as potential pharmacological approaches and compare them to placebo using the systematic review (SR) and network meta-analysis (NMA) approach. We performed a computerized search of SCOPUS, PubMed, Cochrane central, and Embase databases through January 2019 and included randomized controlled trials (RCTs), which were performed on episodic and chronic migraine patients who used Erenumab, Eptinezumab, Fremanezumab, or Galcanezumab. The combined analysis revealed that after six, eight, and twelve weeks of intervention, the medications with the most potent effects in comparison to placebo were Fremanezumab 900 mg, (SMD = -0.55, 95% CI [-0.97, -0.12]); Erenumab 140 mg, (SMD = -0.51, 95% CI [-0.61, 0.41]); and Erenumab 140 mg, (SMD = -0.48, 95% CI [-0.571, 0.39]), respectively. For chronic migraine patients, Fremanezumab 900 mg, Erenumab 140 mg, in addition to Erenumab 70 mg, were associated with the highest efficacy after 6, 8, and 12 weeks, correspondingly. The analysis of combined groups data (Chronic and Episodic) showed that Fremanezumab was the most effective drug after six weeks, where Erenumab was the most effective after 8 and 12 weeks. The current evidence retrieved from this NMA suggests that Fremanezumab was the most effective anti-migraine medication in decreasing MHDs per month after six weeks in both chronic and episodic patients.

CGRP measurements in human plasma - a methodological study

Background

Calcitonin gene-related peptide plasma levels have frequently been determined as a biomarker for primary headaches. However, published data is often inconsistent resulting from different methods that are not precisely described in most studies.

Methods

We applied a well-proven enzyme-linked immunosorbent assay to measure calcitonin gene-related peptide concentrations in human blood plasma, we modified parameters of plasma preparation and protein purification and used calcitonin gene-related peptide-free plasma for standard solutions, which are described in detail.

Results

Calcitonin gene-related peptide levels are stable in plasma with peptidase inhibitors and after deep-freezing. Calcitonin gene-related peptide standard solutions based on synthetic intercellular fluid or pooled plasma with pre-absorbed calcitonin gene-related peptide influenced the measurements but yielded both comprehensible results. In a sample of 56 healthy subjects the calcitonin gene-related peptide plasma levels varied considerably from low (<50 pg/mL) to very high (>500 pg/mL) values. After a 12-hour exposure of these subjects to normobaric hypoxia the individual calcitonin gene-related peptide levels remained stable.

Conclusion

Buffering with peptidase inhibitors and immediate freezing or processing of plasma samples is essential to achieve reliable measurements. Individuals show considerable differences and partly high calcitonin gene-related peptide plasma levels without detectable pathological reason. Thus plasma measurements are suited particularly to follow calcitonin gene-related peptide levels in longitudinal studies.

The use of data for this study was approved by the Ethics Committee of the Medical

University of Innsbruck (https://www.i-med.ac.at/ethikkommission/; EK Nr: 1242/2017).

PACAP Induces Light Aversion in Mice by an Inheritable Mechanism Independent of CGRP

The neuropeptides CGRP (calcitonin gene-related peptide) and PACAP (pituitary adenylate cyclase-activating polypeptide) have emerged as mediators of migraine, yet the potential overlap of their mechanisms remains unknown. Infusion of PACAP, like CGRP, can cause migraine in people, and both peptides share similar vasodilatory and nociceptive functions. In this study, we have used light aversion in mice as a surrogate for migraine-like photophobia to compare CGRP and PACAP and ask whether CGRP or PACAP actions were dependent on each other. Similar to CGRP, PACAP induced light aversion in outbred CD-1 mice. The light aversion was accompanied by increased resting in the dark, but not anxiety in a light-independent open field assay. Unexpectedly, about one-third of the CD-1 mice did not respond to PACAP, which was not seen with CGRP. The responder and nonresponder phenotypes were stable, inheritable, and not sex linked, although there was a trend for greater responses among male mice. RNA-sequencing analysis of trigeminal ganglia yielded hierarchical clustering of responder and nonresponder mice and revealed a number of candidate genes, including greater expression of the Trpc5 and Kcnk12 ion channels and glycoprotein hormones and receptors in a subset of male responder mice. Importantly, an anti-PACAP monoclonal antibody could block PACAP-induced light aversion but not CGRP-induced light aversion. Conversely, an anti-CGRP antibody could not block PACAP-induced light aversion. Thus, we propose that CGRP and PACAP act by independent convergent pathways that cause a migraine-like symptom in mice.SIGNIFICANCE STATEMENT The relationship between the neuropeptides CGRP (calcitonin gene-related peptide) and PACAP (pituitary adenylate cyclase-activating polypeptide) in migraine is relevant given that both peptides can induce migraine in people, yet to date only drugs that target CGRP are available. Using an outbred strain of mice, we were able to show that most, but not all, mice respond to PACAP in a preclinical photophobia assay. Our finding that CGRP and PACAP monoclonal antibodies do not cross-inhibit the other peptide indicates that CGRP and PACAP actions are independent and suggests that PACAP-targeted drugs may be effective in patients who do not respond to CGRP-based therapeutics.

Migraine with Brainstem Aura Accompanied by Disorders of Consciousness

Migraine with brainstem aura (MBA) accompanied by disorders of consciousness (DOC) is a rare subtype of migraine. The pathophysiology of MBA with DOC has not been elucidated yet. Some patients have a family history of migraine, and women are more affected than men. The aura symptoms are diverse; however, when MBA is combined with DOC, the clinical manifestations are more complicated. Coma is the most common clinical manifestation. The overall duration of the patient’s DOC is short and can often return to normal within half an hour. Headache often occurs after regaining consciousness and can also occur at the same time as DOC. The most common headache is located at the occipital region. Although DOC is reversible, considering the current small number of cases, we still need to improve our understanding of the disease to avoid misdiagnosis. The MBA patient’s electroencephalogram and cerebral blood flow perfusion may have transient changes and may return to normal in the interictal period or after the DOC. Although triptans have traditionally been contraindicated in MBA under drug instructions, the evidence of basilar artery constriction, as postulated in MBA, is lacking. Lasmiditan is currently the first and only 5-HT 1F receptor agonist approved by the Food and Drug Administration. The calcitonin gene-related peptide receptor antagonists and monoclonal antibody therapies may be the most promising for future consideration. Here, the pathophysiology, clinical manifestations, diagnostic tools, and treatment progress for MBA with DOC are reviewed.

Mild systemic inflammation enhances response to OnabotulinumtoxinA in chronic migraineurs

The anti-inflammatory effect of OnabotulinumtoxinA (OnabotA) has been a matter of discussion for many years. In chronic migraine, however, increased pro-inflammatory state is associated with good response to OnabotA. We aimed to investigate whether a mild systemic inflammatory state elicited by a common oral infection (periodontitis) could enhance treatment response to OnabotA. In this study, we included 61 chronic migraineurs otherwise healthy treated with OnabotA of which 7 were poor responders and 54 good responders. Before receiving OnabotA therapy, all participants underwent a full-mouth periodontal examination and blood samples were collected to determine serum levels of calcitonin gene-related peptide (CGRP), interleukin 6 (IL-6), IL-10 and high sensitivity C-reactive protein (hs-CRP). Periodontitis was present in 70.4% of responders and 28.6% of non-responders (P = 0.042). Responders showed greater levels of inflammation than non-responders (IL-6: 15.3 ± 8.7 vs. 9.2 ± 4.7 ng/mL, P = 0.016; CGRP: 18.8 ± 7.6 vs. 13.0 ± 3.1 pg/mL, P = 0.002; and hs-CRP: 3.9 ± 6.6 vs. 0.9 ± 0.8 mg/L, P = 0.003). A linear positive correlation was found between the amount of periodontal tissue inflamed in the oral cavity and markers of inflammation (IL-6: r = 0.270, P = 0.035; CGRP: r = 0.325, P = 0.011; and hs-CRP: r = 0.370, P = 0.003). This report shows that in presence of elevated systemic inflammatory markers related to periodontitis, OnabotA seems to reduce migraine attacks. The changes of scheduled inflammatory parameters after treatment and subsequent assessment during an adequate period still need to be done.

α6GABAA Receptor Positive Modulators Alleviate Migraine-like Grimaces in Mice via Compensating GABAergic Deficits in Trigeminal Ganglia

Migraine is caused by hyperactivity of the trigeminovascular system, where trigeminal ganglia (TG) play an important role. This hyperactivity might originate from an underfunctional GABAergic system in TG. To investigate this possibility, we adapted a mouse model of migraine by inducing migraine-like grimaces in male mice via repeated injections of nitroglycerin (NTG, 10 mg/kg, i.p.), once every 2 days, for up to 5 sessions. Migraine-like facial pain scores were measured using the mouse grimace scale. Repeated NTG treatments in mice caused significant increases in migraine-like grimaces that were aborted and prevented by two anti-migraine agents sumatriptan and topiramate, respectively. After 5 sessions of NTG injections, the GABA-synthesizing enzyme, 65-kDa glutamate decarboxylase (GAD65), but not the GABA transporter 1 (GAT1) or the α6 subunit-containing GABAA receptors (α6GABAARs), was downregulated in mouse TG tissues. Taking advantage of the unaffected TG α6GABAAR expression in NTG-treated mice, we demonstrated that an α6GABAAR-selective positive allosteric modulator (PAM), DK-I-56-1, exhibited both abortive and prophylactic effects, comparable to those of sumatriptan and topiramate, respectively, in this migraine-mimicking mouse model. The brain-impermeable furosemide significantly prevented the effects of DK-I-56-1, suggesting its peripheral site of action, likely via preventing α6GABAAR modulation in TG. Results suggest that a decreased GABA synthesis caused by the reduced GAD65 expression in TG contributes to the trigeminovascular activation in this repeated NTG-induced migraine-mimicking model and that the unaltered α6GABAARs in TG are potential targets for migraine treatment. Thus, α6GABAAR-selective PAMs are potential anti-migraine agents for both abortive and preventive therapies.

Eptinezumab for the preventive treatment of migraine

Our knowledge of the pathophysiology of migraine and the molecules implicated in the disorder have evolved over time. Among these, calcitonin gene-related peptide has shown a crucial role that led to the development of therapies specifically targeting the molecule. Four monoclonal antibodies targeting the calcitonin gene-related peptide pathway are currently available after the US FDA approval of eptinezumab for the indication of migraine prevention. This is the only one of the class to be administered intravenously. The pharmacology of eptinezumab and the four studies that led to the approval, two Phase II and two Phase III clinical trials, are reviewed in this paper. Eptinezumab has demonstrated efficacy, tolerability and safety in patients with episodic and chronic migraine. Studies including migraineurs who have failed previous preventives, and comparison with other options administered quarterly, as well as real-world experience data will all be welcome.

How does the brain change in chronic migraine? Developing disease biomarkers

BACKGROUND

Validated chronic migraine biomarkers could improve diagnostic, prognostic, and predictive abilities for clinicians and researchers, as well as increase knowledge on migraine pathophysiology.

OBJECTIVE

The objective of this narrative review is to summarise and interpret the published literature regarding the current state of development of chronic migraine biomarkers.

FINDINGS

Data from functional and structural imaging, neurophysiological, and biochemical studies have been utilised towards the development of chronic migraine biomarkers. These biomarkers could contribute to chronic migraine classification/diagnosis, prognosticating patient outcomes, predicting response to treatment, and measuring treatment responses early after initiation. Results show promise for using measures of brain structure and function, evoked potentials, and sensory neuropeptide concentrations for the development of chronic migraine biomarkers, yet further optimisation and validation are still required.

CONCLUSIONS

Imaging, neurophysiological, and biochemical changes that occur with the progression from episodic to chronic migraine could be utilised for developing chronic migraine biomarkers that might assist with diagnosis, prognosticating individual patient outcomes, and predicting responses to migraine therapies. Ultimately, validated biomarkers could move us closer to being able to practice precision medicine in the field and thus improve patient care.

Galcanezumab for the Management of Migraine: A Systematic Review and Meta-Analysis of Randomized Placebo-Controlled Trials

Introduction Migraine is a frequent neurological condition manifested by several episodes of headache. Calcitonin gene-related peptide (CGRP) has been shown to play a key role in the pathophysiology of migraine. Galcanezumab is a monoclonal antibody that binds CGRP and inhibits its action, without affecting the CGRP receptor. The aim of this study is to carry out a systematic review and meta-analysis of all randomized placebo-controlled trials that evaluated the efficacy of galcanezumab (120 mg or 240 mg) for the management of migraine. Methods We screened four databases (PubMed, SCOPUS, Embase, and Cochrane Central) from inception to October 10, 2020. Studies meeting the following criteria were included: (i) Patients: individuals with migraine, (ii) Intervention: galcanezumab at a dose of 120 mg or 240 mg, (iii) Comparator: placebo, (iv) Outcomes: prespecified efficacy and safety outcomes, and (v) Study design: randomized placebo-controlled trials. Efficacy outcomes included change in migraine headache days (MHDs), change in MHDs with acute medication use, patient global impression of severity (PGI-S) score, migraine-specific quality of life role function-restrictive domain (MSQ RF-R) score, and migraine disability assessment (MIDAS) score. Safety outcomes included frequency of injection-site pain, nasopharyngitis, and upper respiratory tract infection (URTI). Moreover, we used the Cochrane Collaboration's risk of bias tool to assess the risk of bias of the included studies. Review Manager Software, version 5.4.1, was used for statistical analysis. Mean difference and risk ratio with 95% confidence interval were used to analyze continuous and dichotomous outcomes, respectively. We used the fixed-effects and random-effects models to analyze homogeneous and heterogeneous data, respectively. Results A total of six studies comprising 4,023 patients were included in this systematic review and meta-analysis. When compared to placebo, both doses of galcanezumab were highly effective in decreasing MHDs (p<0.001), reducing MHDs with acute medication use (p<0.001), and improving the PGI-S score (p<0.001). On the other hand, MSQ RF-R and MIDAS scores were significantly enhanced only in the 240-mg dose group (p<0.001). With regard to side effects, the rates of injection-site pain and nasopharyngitis did not substantially differ between galcanezumab (inclusive of 120 mg and 240 mg) and placebo groups. Nonetheless, when compared to placebo, galcanezumab 120 mg, but not galcanezumab 240 mg, substantially correlated with a higher rate of URTI. Conclusions Galcanezumab is clinically safe and efficient for the management of migraine, and the use of a higher dose increases its efficacy. Future research directions should be geared toward determining the optimal dose of galcanezumab in the management of patients with migraine. Moreover, head-to-head comparative studies between galcanezumab and other related anti-CGRP receptor monoclonal antibodies are warranted.

Plasma levels of CGRP and expression of specific microRNAs in blood cells of episodic and chronic migraine subjects: towards the identification of a panel of peripheral biomarkers of migraine?

Background

Migraine can manifest with an episodic or a chronic pattern in a continuum of disease severity. Multiple factors are associated with the progression of the pattern from episodic to chronic. One of the most consistently reported factors is the overuse of medications (MO) for the acute treatment of migraine attacks. The mechanisms through which MO facilitates the transformation of episodic migraine (EM) into chronic migraine (CM) are elusive. In order to provide insights into these mechanisms, the present study aims to identify possible peripheral biomarkers associated with the two forms of migraine, and with the presence of MO.

Methods

We evaluated the plasma levels of calcitonin gene-related peptide (CGRP) and the expression of miR-34a-5p and miR-382-5p in peripheral blood mononuclear cells of subjects with EM (n = 27) or CM-MO (n = 28). Subjects in the CM-MO group were also tested 2 months after an in-hospital detoxification protocol.

Results

CGRP, miR-382-5p, and miR-34a-5p levels were significantly higher in CM-MO subjects when compared to EM patients (p = 0.003 for all comparisons). After correcting for age, sex, and disease duration, miRNAs expression was still significantly associated with migraine phenotype (EM vs. CM-MO: p = 0.014 for miR-382-5p, p = 0.038 for miR-34a-5p), while CGRP levels were not (p = 0.115). CGRP plasma levels significantly and positively correlated with miR-382-5p (Spearman’s rho: 0.491, p = 0.001) and miR-34a-5p (Spearman’s rho: 0.303, p =0.025) in the overall population. In the CM-MO group, detoxification significantly decreased CGRP levels and miRNAs expression (p = 0.001). When comparing responders and non-responders to the detoxification, the former group (n = 23) showed significantly higher levels of CGRP at baseline, and significantly lower expression of miR-382-5p after the detoxification.

Conclusions

Our findings identify a potential panel of peripheral markers associated with migraine subtypes and disease severity. CGRP levels as well as miRNAs expression were influenced by MO, and modulated by detoxification in subjects with CM-MO.

Trial registration

The study protocol was registered at www.clinicaltrials.gov (NCT04473976).

Menière's disease caused by CGRP - A new hypothesis explaining etiology and pathophysiology. Redirecting Menière's syndrome to Menière's disease

This paper provides a new hypothetical explanation for the etiopathology and pathophysiology of Menière's Disease (MD), which to date remain unexplained, or incompletely understood. The suggested hypothesis will explain the close connection of MD and Migraine, the coexistence of endolymphatic hydrops (ELH) and Menière attacks and the signs of inflammation detected in the inner ears of MD patients. Although as yet unproven, the explanations provided appear highly plausible and could pave the way for the generation of the first animal model of MD - an invaluable asset for developing new treatment strategies. Furthermore, if proven correct, this hypothesis could redefine and also reset the actual name of Menière's Syndrome to Menière's Disease.

Hejie Zhitong prescription promotes sleep and inhibits nociceptive transmission-associated neurotransmitter activity in a rodent migraine model

BACKGROUND

Migraine is painful disease in which neurotransmitters related to pain transmission play an important role. Hejie Zhitong prescription (HJZT) has been used in the clinic as an effective prescription for the treatment of migraine for many years. Our team aimed to further explore its antimigraine mechanism based on previous research results and to explore the inhibitory effect of HJZT on the transmission of pain related to nitroglycerine (NTG)-induced migraine as well as the synergistic effect of HJZT with pentobarbital sodium on promoting sleep.

METHODS

Sixty mice were randomly assigned to groups and received the corresponding interventions. Sleep latency and sleep time were recorded to calculate the incidence of sleep. Forty-eight Wistar rats were randomly assigned and administered an intervention corresponding to their group. Calcitonin gene-related peptide (CGRP), serotonin (5-HT), substance P (SP), and cholecystokinin (CCK) levels were measured using ELISAs. Levels of the cannabinoid receptor type 1 (CB1R) and cyclooxygenase-2 (COX-2) protein were assessed using immunohistochemistry. The expression of the CGRP and CCK mRNAs in the midbrain and trigeminal ganglion (TG) were measured using real-time quantitative PCR.

RESULTS

HJZT promoted the occurrence of sleep in mice. HJZT downregulated COX-2 expression in the midbrain and TG of rats but upregulated the expression of the CB1R, and decreased the plasma level of the CGRP protein and expression of its mRNA in the midbrain and TG. It also downregulated the expression of the CCK mRNA in the midbrain and TG. The high-dose HJZT treatment increased plasma 5-HT levels, but did not induce changes in the plasma levels of the SP or CCK protein.

CONCLUSIONS

HJZT exerts a synergistic effect with pentobarbital sodium on promoting sleep. As for anti-migraine, HJZT can inhibits the expression of nociceptive transmission-associated neurotransmitters, including 5-HT, CGRP and CCK, which may be related to its upregulation of CB1R and downregulation of COX-2.

Serum CGRP, VIP, and PACAP usefulness in migraine: a case-control study in chronic migraine patients in real clinical practice

Calcitonin gene-related peptide (CGRP), vasoactive intestinal peptide (VIP) and pituitary adenylate cyclase activating polypetide-38 (PACAP-38) have relevant roles in migraine pathophysiology. Their serum levels have been proposed as biomarkers for migraine. Our aim was to assess their diagnostic value in real clinical practice in a cohort of chronic migraine (CM), episodic migraine (EM) and healthy controls (HC). We recruited subjects with CM, EM and HC at two medical centers. Blood samples were drawn under fasting conditions in the interictal period, immediately centrifuged and stored at - 80 ºC. Serum levels were determined by ELISA. Neuropeptide levels, the effect of preventatives, correlations with clinical and demographic variables, and their diagnostic value were studied among clinical categories. 296 age- and sex-matched subjects (101 CM, 98 EM and 97 HC) were included. All three neuropeptide serum levels were higher in CM [median and IQ for CGRP = 18.023 pg/ml (14.4-24.7); VIP = 121.732 pg/ml (48.72-186.72) and PACAP = 204.931 pg/ml (101.08-597.64)] vs EM [CGRP = 14.659 pg/ml (10.29-17.45); VIP = 75.603 pg/ml (28.722-107.10); and PACAP = 94.992 pg/ml (65.77-128.48)] and vs HC [CGRP = 13.988 pg/ml (10.095-17.87); VIP = 84.685 pg/ml (35.32-99.79), and PACAP = 103.142 pg/ml (59.42-123.97)]. Using multinomial modeling, only VIP (OR 1.011, 95% CI  1.003-1.018, p = 0.005) and PACAP (OR 1.003, 95% CI 1.001-1.005, p = 0.002) increased the risk for CM, but not for EM. CGRP did not predict CM or EM. This model could correctly classify only 62/101 (61.38%) of CM, 75/98 (76.53%) of EM, and 5/97 (4.12%) of HC [globally 147/296 (49.8%)]. Individually, PACAP performed the best for classifying clinical categories [global accuracy 150/296 (50.67%)]. In CM, neuropeptide levels were higher in those OnaBT-treated than in no-treated patients. Although interictal serum CGRP and VIP were higher in CM than both EM or HC, their utility to discriminate migraine categories was low. Contrary to other studies, PACAP serum levels were also higher in CM than in EM or HC and had more discriminative capability to distinguish CM from EM and HC. Further investigation is needed for determination technique standardization.

Low plasma levels of calcitonin gene-related peptide in persistent post-traumatic headache attributed to mild traumatic brain injury

OBJECTIVE

To investigate the role of calcitonin gene-related peptide (CGRP) in persistent post-traumatic headache (PTH) attributed to mild traumatic brain injury (TBI).

METHODS

A total of 100 individuals with persistent PTH attributed to mild TBI and 100 age- and gender-matched healthy controls were enrolled between July 2018 and June 2019. Blood was drawn from the antecubital vein and subsequently analyzed using a validated radioimmunoassay for human CGRP. Measurements were performed on coded samples by a board-certified laboratory technician who was blind to clinical information.

RESULTS

CGRP plasma levels were lower in subjects with persistent PTH (mean, 75.8 pmol/L; SD, 26.4 pmol/L), compared with age- and gender-matched healthy controls (mean, 88.0 pmol/L; SD, 34.1 pmol/L) (p = 0.04). No correlation was found of CGRP plasma levels with monthly headache days (r = -0.11; p = 0.27), monthly migraine-like days (r = 0.15; p = 0.13), headache quality (r = -0.14; p = 0.15), or a chronic migraine-like headache phenotype (r = -0.02; p = 0.85).

CONCLUSIONS

CGRP plasma measurements are unlikely a feasible blood-based biomarker of persistent PTH. Future studies should assess whether CGRP plasma measurements can be used to predict development of persistent PTH.

Potential for treatment benefit of small molecule CGRP receptor antagonist plus monoclonal antibody in migraine therapy

Objective

To provide the first clinical report that 2 calcitonin gene-related peptide (CGRP) therapies, a small molecule CGRP receptor antagonist and an anti-CGRP receptor antibody, can be used concomitantly to treat refractory migraine.

Methods

Case reports are presented of 2 patients participating in a long-term safety study of rimegepant 75 mg oral tablets for acute treatment (NCT03266588). After Food and Drug Administration approval of erenumab, both patients started subcutaneous erenumab monthly as allowed per protocol.

Results

Patients were women 44 and 36 years of age with ≥2 decades of self-reported suboptimal response to multiple migraine medications. Patient 1 used rimegepant for 6 months and then started erenumab 70 mg subcutaneous monthly. Despite a response to preventive treatment with erenumab, she experienced substantial relief treating 7 of 7 acute attacks with rimegepant and eliminated regular, frequent use of ibuprofen and a caffeinated analgesic. Patient 2 used rimegepant for 60 days before starting erenumab 140 mg subcutaneously monthly. While on erenumab, 9 of 9 attacks treated with rimegepant responded. She stopped near-daily use of injectable ketorolac and diphenhydramine. While using rimegepant alone or together with erenumab, patients reported no related adverse events.

Conclusions

Rimegepant 75 mg may be effective for acute treatment during concomitant erenumab preventive administration. The mechanism underlying the benefits of concomitant use of a small molecule CGRP receptor antagonist and an anti-CGRP receptor antibody is unknown and requires further study.

ClinicalTrials.gov identifier

NCT03266588.

Classification of evidence

This study provides Class IV evidence that for patients with migraine using erenumab, rimegepant is effective for acute treatment.

Up-regulation of astrocyte excitatory amino acid transporter 2 alleviates central sensitization in a rat model of chronic migraine

Central sensitization is the potential pathogenesis of chronic migraine (CM) and is related to persistent neuronal hyperexcitability. Dysfunction of excitatory amino acid transporter 2 (EAAT2) leads to the accumulation of glutamate in the synaptic cleft, which may contribute to central sensitization by overactivating glutamate N-methyl-D-aspartate receptors and enhancing synaptic plasticity. However, the therapeutic potential of CM by targeting glutamate clearance remains largely unexplored. The purpose of this study was to investigate the role of EAAT2 in CM central sensitization and explore the effect of EAAT2 expression enhancer LDN-212320 in CM rats. The glutamate concentration was measured by high-performance liquid chromatography in a rat model of CM. Then, q-PCR and western blots were performed to detect EAAT2 expression, and the immunoreactivity of astrocytes was detected by immunofluorescence staining. To understand the effect of EAAT2 on central sensitization of CM, mechanical and thermal hyperalgesia and central sensitization-associated proteins were examined after administration of LDN-212320. In addition, the expression of synaptic-associated proteins was examined and Golgi-Cox staining was used to observe the dendritic spine density of trigeminal nucleus caudalis neurons. Also, the synaptic ultrastructure was observed by transmission electron microscope (TEM) to explore the changes of synaptic plasticity. In our study, elevated glutamate concentration and decreased EAAT2 expression were found in the trigeminal nucleus caudalis of CM rats, administration of LDN-212320 greatly up-regulated the protein expression of EAAT2, alleviated hyperalgesia, decreased the concentration of glutamate and the activation of astrocytes. Furthermore, reductions in calcitonin gene-related peptide, substance P(SP), and phosphorylated NR2B were examined after administration of LDN-212320. Moreover evaluation of the synaptic structure, synaptic plasticity-, and central sensitization-related proteins indicated that EAAT2 might participate in the CM central sensitization process by regulating synaptic plasticity. Taken together, up-regulation of EAAT2 expression has a protective effect in CM rats, and LDN-212320 may have clinical therapeutic potential. Cover Image for this issue: https://doi.org/10.1111/jnc.14769.

Circulating Biomarkers in Migraine: New Opportunities for Precision Medicine

Background:

Migraine is the most common neurological disorder and the second most disabling human condition, whose pathogenesis is favored by a combination of genetic, epigenetic, and environmental factors. In recent years, several efforts have been made to identify reliable biomarker(s) useful to monitor disease activity and/or ascertain the response to a specific treatment.

Objective:

To review the current evidence on the potential biological markers associated with migraine.

Methods:

A structured search of peer-reviewed research literature was performed by searching major publications databases up to December 2017.

Results:

Several circulating biomarkers have been proposed as diagnostic or therapeutic tools in migraine, mostly related to migraine’s inflammatory pathophysiological aspects. Nonetheless, their detection is still a challenge for the scientific community, reflecting, at least in part, disease complexity and clinical diagnostic limitations. At the present time, calcitonin generelated peptide (CGRP) represents probably the most promising candidate as a diagnostic and/or therapeutic biomarker, as its plasma levels are elevated during migraine attack and decrease during successful treatment. Other molecules (including some neuropeptides, cytokines, adipokines, or vascular activation markers) despite promising, do not possess the sufficient prerequisites to be considered as migraine biomarkers.

Conclusion:

The characterization of migraine-specific biomarkers would be fundamental in a perspective of precision medicine, enabling risk assessment and tailored treatments. However, speculating on the clinical validity of migraine biomarkers may be premature and controlled clinical trials are presently needed to investigate both the diagnostic and therapeutic value of these biomarkers in migraine.

Monoclonal antibodies for the prevention of migraine

Introduction: Calcitonin Gene-Related Peptide (CGRP) plays a crucial role in migraine pathophysiology. A novel specific treatment strategy for the prevention of migraine incorporates monoclonal antibodies (mAbs) against CGRP and its canonical receptor. Eptinezumab, fremanezumab and galcanezumab block CGRP mediated effects by binding to the peptide, while erenumab blocks the CGRP receptor.Areas covered: Following a brief overview of pharmacological characteristics, we will review phase III trials for the use of CGRP mAbs in the prevention of episodic and chronic migraine.Expert opinion: All four CGRP mAbs demonstrated an excellent safety, tolerability and efficacy profile in migraine patients. Across all trials mAbs showed superior efficacy for the reduction of monthly migraine days compared to placebo with a net benefit of 2.8 days. Neither cardiovascular nor immunological safety concerns have emerged from clinical trials. Fremanezumab, galcanezumab, and erenumab are approved in the USA and Europe. Based on trial data there is no reason why these mAbs should not become first-line therapies in future. For now, we advocate for the use of mAbs in migraine prevention for patients who failed a minimum of two standard oral treatments based on the novelty and costs of this approach. mAbs are also effective in patients with medication overuse and with comorbid depression or anxiety disorders. Taken together, mAbs are likely to usher in a new era in migraine prevention and provide significant value to patients.

Vestibular migraine: An update on current understanding and future directions

BACKGROUND

Vestibular migraine is among the most common causes of recurrent vertigo in the general population. Despite its prevalence and high impact on healthcare cost and utilization, it has remained an under-recognized condition with largely unknown pathophysiology. In the present article, we aim to provide an overview of the current understanding of vestibular migraine.

METHODS

We undertook a narrative literature review on the epidemiology, presentations, clinical and laboratory findings, pathophysiology, and treatments of vestibular migraine.

RESULTS

Currently, the diagnosis of vestibular migraine relies solely on clinical symptoms since clinical tests of vestibular function are typically normal, or difficult to interpret based on inconsistent results reported in earlier studies. The challenges related to diagnosis of vestibular migraine lie in its relatively broad spectrum of manifestations, the absence of typical migraine headaches with vestibular symptoms, and its very recent definition as a distinct entity. Here, we highlight these challenges, discuss common vestibular symptoms and clinical presentations in vestibular migraine, and review the current aspects of its clinical diagnosis and evaluation. The concepts related to the pathophysiology and treatment of vestibular migraine are also discussed.

CONCLUSION

Vestibular migraine is still underdiagnosed clinically. Future studies are needed to address the pathophysiological mechanisms and investigate effective treatment regimens.

Hsa-miR-34a-5p and hsa-miR-375 as Biomarkers for Monitoring the Effects of Drug Treatment for Migraine Pain in Children and Adolescents: A Pilot Study

MicroRNAs (miRs) have emerged as biomarkers of migraine disease in both adults and children. In this study we evaluated the expression of hsa-miR-34a-5p and hsa-miR-375 in serum and saliva of young subjects (age 11 ± 3.467 years) with migraine without aura (MWA), while some underwent pharmacological treatment, and healthy young subjects were used as controls. miRs were determined using the qRT-PCR method, and gene targets of hsa-miR-34a-5p and hsa-miR-375 linked to pain-migraine were found by in silico analysis. qRT-PCR revealed comparable levels of hsa-miRs in both blood and saliva. Higher expression of hsa-miR-34a-5p and hsa-miR-375 was detected in saliva of untreated MWAs compared to healthy subjects (hsa-miR-34a-5p: p < 0.05; hsa-miR-375 p < 0.01). Furthermore, in MWA treated subjects, a significant decrease of hsa-miR-34a-5p and of hsa-miR-375 was documented in saliva and blood compared to MWA untreated ones. Altogether, these findings suggested thathsa-miR-34a-5p and hsa-miR-375 are expressed equally in blood and saliva and that they could be a useful biomarker of disease and of drug efficacy in patients with MWA.

Anti-CGRP and anti-CGRP receptor monoclonal antibodies as antimigraine agents. Potential differences in safety profile postulated on a pathophysiological basis

Calcitonin gene-related peptide (CGRP) is a peptide neurotransmitter with potent vasodilating properties. CGRP is believed to play a primary role in the pathogenesis of migraine. As such, CGRP and its receptors are obvious druggable targets for novel anti-migraine agents. While the development of small-molecule CGRP receptor antagonists started first, none of these agents is yet available in clinical practice. Conversely, both anti-CGRP and anti-CGRP receptor monoclonal antibodies (mABs) completed clinical development, and the first representatives of these 2 classes are available on the market. MABs are approved for prevention of migraine attacks in chronic or episodic migraine, involving long-term treatments. In light of the physiological role exerted by CGRP in the regulation of vascular tone, the potential risks of a long-term inhibition of CGRP functions raised diffuse concerns. These concerns were correctly addressed by the anti-CGRP receptor mABs erenumab with a 5-year open-label clinical trial; however, this study is currently ongoing and results are not yet available, leaving some uncertainty on the profile of erenumab long-term safety. Similar concerns can be raised with direct anti-CGRP mABs, which entrap the peptide preventing receptor activation. However, evidence exists that plasma CGRP is detectable in patients chronically treated with anti-CGRP mABs. Assuming that plasma CGRP is an indirect marker of peptide levels at the vascular receptor sites, such residual CGRP would maintain a physiological level of receptor stimulation, in spite of a well-established anti-migraine activity of the mABs. This might represent a potential advantage in the safety profile of anti-CGRP mABs, but it needs to be confirmed and expanded with data on free plasma CGRP.

The Efficacy of Shinbaro for the Preventive Treatment of Migraine: A Pilot Study

OBJECTIVE

To investigate the therapeutic potential and efficacy of Shinbaro, an herbal medication for inflammatory diseases and bone disorders, as a preventive treatment of migraine.

METHODS

In this prospective, interventional, single-arm, pre-post study, 37 migraine patients took 600mg bid of Shinbaro for 12 weeks. At 4-week intervals, the migraine frequency and the rescue medications frequency were measured from each patient's headache diary. The modified Migraine Disability Assessment (MIDAS) questionnaires to assess migraine associated disabilities were also completed at each visit. The serum calcitonin gene-related peptide (CGRP) concentrations before and after 12 weeks of Shinbaro administration were compared.

RESULTS

The monthly migraine frequency was significantly reduced from 20.5 days at baseline to 16.4 days at week 12 (P =0.003), and 22% of the participants showed ≥ 50% reduction. The frequency reduction was observed by week 4 (P =0.035) and continuously occurred through week 8 (P =0.001) and week 12 (P =0.003). The rescue medications frequency also decreased significantly from 17.4 days at baseline to 13.2 days at week 12 (P =0.035). Lastly, the serum CGRP concentration dropped from 434.6 pg/mL at baseline to 371.4 pg/mL at week 12, which was statistically significant (P <0.001).

CONCLUSIONS

Shinbaro demonstrated prophylactic effects in migraine patients, significantly reducing their mean migraine frequency, rescue medications frequency, and the serum CGRP concentration after 12 weeks of treatment. This study is registered in Clinical Research Information Service, Seoul National University Hospital Clinical Research Institute (IRB No. 1604-138-758).

The effect of orofacial complete Freund's adjuvant treatment on the expression of migraine-related molecules

Background

Migraine is a neurovascular primary headache disorder, which causes significant socioeconomic problems worldwide. The pathomechanism of disease is enigmatic, but activation of the trigeminovascular system (TS) appears to be essential during the attack. Migraine research of recent years has focused on neuropeptides, such as calcitonin gene-related peptide (CGRP) and pituitary adenylate cyclase-activating polypeptide 1–38 (PACAP1–38) as potential pathogenic factors and possible therapeutic offensives. The goal of present study was to investigate the simultaneous expression of CGRP and precursor of PACAP1–38 (preproPACAP) in the central region of the TS in a time-dependent manner following TS activation in rats.

Methods

The right whisker pad of rats was injected with 50 μl Complete Freund’s Adjuvant (CFA) or saline. A mechanical allodynia test was performed with von Frey filaments before and after treatment. Transcardial perfusion of the animals was initiated 24, 48, 72 and 120 h after injection, followed by the dissection of the nucleus trigeminus caudalis (TNC). After preparation, the samples were stored at − 80 °C until further use. The relative optical density of CGRP and preproPACAP was analyzed by Western blot. One-way ANOVA and Kruskal-Wallis followed by Tukey post hoc test were used to evaluate the data. Regression analysis was applied to explore the correlation between neuropeptides expression and hyperalgesia.

Results

Orofacial CFA injection resulted in significant CGRP and preproPACAP release in the TNC 24, 48, 72 and 120 h after the treatment. The level of neuropeptides reached its maximum at 72 h after CFA injection, corresponding to the peak of facial allodynia. Negative, linear correlation was detected between the expression level of neuropeptides and value of mechanonociceptive threshold.

Conclusion

This is the first study which suggests that the expression of CGRP and preproPACAP simultaneously increases in the central region of activated TS and it influences the formation of mechanical hyperalgesia. Our results contribute to a better understanding of migraine pathogenesis and thereby to the development of more effective therapeutic approaches.

Distinguishing and phenotype monitoring of traumatic brain injury and post-concussion syndrome including chronic migraine in serum of Iraq and Afghanistan war veterans

Traumatic Brain Injury (TBI) and persistent post-concussion syndrome (PCS) including chronic migraine (CM) are major health issues for civilians and the military. It is important to understand underlying biochemical mechanisms of these conditions, and be able to monitor them in an accurate and minimally invasive manner. This study describes the initial use of a novel serum analytical platform to help distinguish TBI patients, including those with post-traumatic headache (PTH), and to help identify phenotypes at play in these disorders. The hypothesis is that physiological responses to disease states like TBI and PTH and related bodily stresses are reflected in biomolecules in the blood in disease-specific manner. Leave one out (serum sample) cross validations (LOOCV) and sample randomizations were utilized to distinguished serum samples from the following TBI patient groups: TBI +PTSD + CM + severe depression (TBI "most affected" group) vs healthy controls, TBI "most affected" vs TBI, TBI vs controls, TBI + CM vs controls, and TBI + CM vs TBI. Inter-group discriminatory p values were ≤ 10-10, and sample group randomizations resulted in p non-significant values. Peptide/protein identifications of discriminatory mass peaks from the TBI "most affected" vs controls and from the TBI plus vs TBI minus CM groups yielded information of the cellular/molecular effects of these disorders (immune responses, amyloidosis/Alzheimer's disease/dementia, neuronal development). More specific biochemical disease effects appear to involve blood brain barrier, depression, migraine headache, autoimmunity, and autophagy pathways. This study demonstrated the ability for the first time of a novel, accurate, biomarker platform to monitor these conditions in serum, and help identify biochemical relationships leading to better understanding of these disorders and to potential therapeutic approaches.

Erenumab in chronic migraine with medication overuse: Subgroup analysis of a randomized trial

Objective

To determine the effect of erenumab, a human anti-calcitonin gene-related peptide receptor monoclonal antibody, in patients with chronic migraine and medication overuse.

Methods

In this double-blind, placebo-controlled study, 667 adults with chronic migraine were randomized (3:2:2) to placebo or erenumab (70 or 140 mg), stratified by region and medication overuse status. Data from patients with baseline medication overuse at baseline were used to assess changes in monthly migraine days, acute migraine-specific medication treatment days, and proportion of patients achieving ≥50% reduction from baseline in monthly migraine days.

Results

Of 667 patients randomized, 41% (n = 274) met medication overuse criteria. In the medication overuse subgroup, erenumab 70 or 140 mg groups had greater reductions than the placebo group at month 3 in monthly migraine days (mean [95% confidence interval] −6.6 [−8.0 to −5.3] and −6.6 [−8.0 to −5.3] vs −3.5 [−4.6 to −2.4]) and acute migraine-specific medication treatment days (−5.4 [−6.5 to −4.4] and −4.9 [−6.0 to −3.8] vs −2.1 [−3.0 to −1.2]). In the placebo and 70 and 140 mg groups, ≥50% reductions in monthly migraine days were achieved by 18%, 36% (odds ratio [95% confidence interval] 2.67 [1.36–5.22]) and 35% (odds ratio 2.51 [1.28–4.94]). These clinical responses paralleled improvements in patient-reported outcomes with a consistent benefit of erenumab across multiple measures of impact, disability, and health-related quality of life. The observed treatment effects were similar in the non–medication overuse subgroup.

Conclusions

Erenumab reduced migraine frequency and acute migraine-specific medication treatment days in patients with chronic migraine and medication overuse, improving disability and quality of life.

Clinicaltrials.gov identifier

NCT02066415.

Classification of evidence

This study provides Class II evidence that erenumab reduces monthly migraine days at 3 months in patients with chronic migraine and medication overuse.

Calcified Neurocysticercosis and Headache in an Endemic Village: A Case-Control Study Nested to a Population-Based Cohort

Headache in patients with calcified neurocysticercosis (NCC) is probably common but has been largely overlooked. We aimed to assess the presence, characteristics, and diagnosis of headache across patients with calcified NCC and their matched controls. In this case-control study nested to a population-based cohort, Atahualpa residents aged ≥ 20 years with calcified NCC were identified as case patients and paired 1:1 to age- and gender-matched randomly selected controls. A culturally adapted questionnaire was derived from the EUROLIGHT. Headache diagnosis was established according to the International Classification of Headache Disorders, 3rd edition. Conditional logistic regression models for matched paired data were fitted to assess the independent association between calcified NCC (as the exposure) and headache variables, after adjusting for education, alcohol intake, depression, and epilepsy. The selection process generated 106 case patients and their matched controls. Lifetime headache prevalence (odds ratio [OR]: 4.18; 95% Confidence Interval [CI]: 1.79-9.75; P = 0.001), current headaches (OR: 4.19; 95% CI: 1.92-9.16; P < 0.001), and intense headaches (OR: 9.47; 95% CI: 2.88-31.19; P < 0.001) were more frequent among cases than in controls. In addition, migraine (but not other forms of headache) was more frequent among subjects with calcified NCC (OR: 4.89; 95% CI: 2.36-11.39; P < 0.001). This study shows a robust epidemiological association between headache-particularly migraine-and calcified NCC.

Imprinted Oxide and MIP/Oxide Hybrid Nanomaterials for Chemical Sensors †

The oxides of transition, post-transition and rare-earth metals have a long history of robust and fast responsive recognition elements for electronic, optical, and gravimetric devices. A wide range of applications successfully utilized pristine or doped metal oxides and polymer-oxide hybrids as nanostructured recognition elements for the detection of biologically relevant molecules, harmful organic substances, and drugs as well as for the investigative process control applications. An overview of the selected recognition applications of molecularly imprinted sol-gel phases, metal oxides and hybrid nanomaterials composed of molecularly imprinted polymers (MIP) and metal oxides is presented herein. The formation and fabrication processes for imprinted sol-gel layers, metal oxides, MIP-coated oxide nanoparticles and other MIP/oxide nanohybrids are discussed along with their applications in monitoring bioorganic analytes and processes. The sensor characteristics such as dynamic detection range and limit of detection are compared as the performance criterion and the miniaturization and commercialization possibilities are critically discussed.

Serum apolipoprotein E may be a novel biomarker of migraine

Migraine attacks alter various molecules that might be related to the pathophysiology of migraine, such as serotonin, calcitonin gene-related peptide, and nitric oxide. The underlying pathophysiology of migraine is as yet unclear. We explored key proteins related to the pathogenesis of migraine here. Serum was collected from two patients with migraine with aura (MA) and seven patients with migraine without aura (MO) during attack-free periods and migraine attacks. Samples were analyzed using 2-dimensional gel electrophoresis. Nineteen protein spots were altered between the attack-free versus migraine attack periods. Mass spectrometric analysis was performed to identify the proteins within each of the 19 altered spots. Thirty-six proteins were significantly altered in samples collected during attack-free periods versus migraine attacks. The protein with the statistically most significant MASCOT/Mowse score (268±112) among lipoproteins was apolipoprotein (ApoE). In the MA and MO groups, ApoE protein levels were significantly higher during migraine attack than during the attack-free period (p<0.05). ApoE protein levels were also significantly increased in the MA group during the attack-free period compared to healthy controls and patients with tension type headaches (p<0.01). Migraine alters ApoE levels, especially in MA. ApoE might play an important role in the pathophysiology of migraine, and may act as a diagnostic biomarker of migraine.

Human models of migraine - short-term pain for long-term gain

Migraine is a complex disorder characterized by recurrent episodes of headache, and is one of the most prevalent and disabling neurological disorders. A key feature of migraine is that various factors can trigger an attack, and this phenomenon provides a unique opportunity to investigate disease mechanisms by experimentally inducing migraine attacks. In this Review, we summarize the existing experimental models of migraine in humans, including those that exploit nitric oxide, histamine, neuropeptide and prostaglandin signalling. We describe the development and use of these models in the discovery of molecular pathways that are responsible for initiation of migraine attacks. Combining experimental human models with advanced imaging techniques might help to identify biomarkers of migraine, and in the ongoing search for new and better migraine treatments, human models will have a key role in the discovery of future targets for more-specific and more-effective mechanism-based antimigraine drugs.