Proinflammatory cytokines, adhesion molecules, and lymphocyte integrin expression in the internal jugular blood of migraine patients without aura assessed ictally

Reactive oxygen species induce procalcitonin expression in trigeminal ganglia glia

OBJECTIVE

To examine calcitonin gene-related peptide (CGRP) gene expression under inflammatory conditions using trigeminal ganglia organ cultures as an experimental system. These cultures have increased proinflammatory signaling that may mimic neurogenic inflammation in the migraine state.

BACKGROUND

The trigeminal nerve sends peripheral pain signals to the central nervous system during migraine. Understanding the dynamic processes that occur within the trigeminal nerve and ganglion may provide insights into events that contribute to migraine pain. A neuropeptide of particular interest is CGRP, which can be elevated and play a causal role in migraine. However, most studies have overlooked a second splice product of the Calca gene that encodes calcitonin (CT), a peptide hormone involved in calcium homeostasis. Importantly, a precursor form of CT called procalcitonin (proCT) can act as a partial agonist at the CGRP receptor and elevated proCT has recently been reported during migraine.

METHODS

We used a trigeminal ganglion whole organ explant model, which has previously been demonstrated to induce pro-inflammatory agents in vitro. Quantitative polymerase chain reaction and immunohistochemistry were used to evaluate changes in messenger ribonucleic acid (mRNA) and protein levels of CGRP and proCT.

RESULTS

Whole mouse trigeminal ganglia cultured for 24 hours showed a 10-fold increase in CT mRNA, with no change in CGRP mRNA. A similar effect was observed in ganglia from adult rats. ProCT immunoreactivity was localized in glial cells. Cutting the tissue blunted the increase in CT, suggesting that induction required the close environment of the intact ganglia. Consistent with this prediction, there were increased reactive oxygen species in the ganglia, and the elevated CT mRNA was reduced by antioxidant treatment. Surprisingly, reactive oxygen species were increased in neurons, not glia.

CONCLUSIONS

These results demonstrate that reactive oxygen species can activate proCT expression from the CGRP gene in trigeminal glia by a paracrine regulatory mechanism. We propose that this glial recruitment pathway may occur following cortical spreading depression and neurogenic inflammation to increase CGRP nociceptive actions in migraine.

Investigation of chemokine receptor CCR2V64Il gene polymorphism and migraine without aura in the Iranian population

Background and Objectives. Migraine is a multifactorial common neurovascular disease with a polygenic inheritance. Inflammation plays an important part in migraine pathophysiology. C-C chemokine receptor 2 (CCR2) is an important chemokine for monocyte aggregation and transendothelial monocyte migration. The aim of our study was to investigate the association of migraine with CCR2V64Il polymorphism in the Iranian population. Methods. We assessed 103 patients with newly diagnosed migraine and 100 healthy subjects. Genomic DNA samples were extracted from peripheral blood and genotypes of CCR2V64Il gene polymorphism were determined. For measuring the severity of headache, every patient filled out the MIGSEV questionnaire. Results. There were no significant differences in the distribution of both 64Il allele and heterozygote (GA) genotype of CCR2 gene polymorphism (P = 0.396; OR = 0.92, 95% CI = 0.50–1.67 and P = 0.388; OR = 0.91, 95% CI = 0.47–1.73, resp.) between case and control groups. There was no significant difference of alleles frequency between three grades of MIGSEV (P = 0.922). Conclusions. In conclusion our results revealed no association between CCR2V64Il polymorphism and susceptibility to migraine and also headache severity in the Iranian population.

Peripheral interleukin-1ß levels are elevated in chronic tension-type headache patients

BACKGROUND

Tension-type headache is the most common form of headache and its chronic form, chronic tension-type headache (CTTH), is one of the most difficult to treat. The etiology of CTTH is not well understood, but is believed to be multifactorial and to vary among individuals. In the present study, the authors sought to identify common mechanisms of CTTH pathology. Empirical studies have implicated various immunomodulatory cytokines as mediators of chronic pain disorders, including CTTH.

OBJECTIVES

To determine the role of peripheral cytokines and genetic factors in the development of CTTH.

METHODS

A panel of cytokines hypothesized to play a role in the pathogenesis of CTTH was measured using cytometric bead arrays and ELISAs in 56 individuals with CTTH and 42 healthy control participants between 18 and 65 years of age.

RESULTS

Levels of interleukin (IL)-1β were significantly elevated in participants diagnosed with CTTH relative to healthy controls, while IL-18 levels were found to be significantly elevated in men with CTTH. Because the levels of these immune mediators were increased in the apparent absence of injury or infection, the authors sought to determine whether genetic changes were responsible for fluctuations in cytokine levels. Polymerase chain reaction and restriction fragment length polymorphism analyses were used to determine individual genotypes at key single nucleotide polymorphism positions in the IL-1B gene. No association was observed between CTTH and single nucleotide polymorphisms in the IL-1β gene.

CONCLUSIONS

These findings suggest that increases in key proinflammatory cytokine levels are associated with CTTH and the pathology of the disorder involves sterile neurovascular inflammation.

Biomarkers associated with migraine and their potential role in migraine management

OBJECTIVE

The focus of this review is to review potential diagnostic and therapeutic biomarkers associated with migraine.

BACKGROUND

Migraine headache is a common disease that affects millions of individuals worldwide. Although well-accepted diagnostic criteria exist for migraine, it is still a complex disorder that remains both underdiagnosed and misdiagnosed. The causes of migraine are likely a mix of genetic, epigenetic, and environmental factors that, together with the individual's life history, translate into the observed clinical heterogeneity. Inherent clinical heterogeneity is an obstacle in developing more effective treatments. The lack of appropriate biomarkers is also an impediment to developing more effective therapeutic/preventive approaches. Ultimately, biomarkers may facilitate the goal of individualized medicine by enabling clinicians to more accurately diagnose and treat migraine and other types of headache.

METHODS

A comprehensive review was conducted of PubMed citations containing the key word "marker" OR "biomarker" combined with "migraine" OR "headache." Other key words included "serum," "saliva," "cerebrospinal fluid," "genes," "blood," and "inflammation." The only restriction was English-language publication. The abstracts of all articles meeting these criteria were reviewed, and full text was retrieved and examined for relevant references.

RESULTS

Data from human studies have begun to identify genetic mutations/polymorphisms and altered levels of specific proinflammatory and neuromodulatory molecules that strongly correlate with migraine as well as symptom severity. Results from a smaller number of studies have identified parameters, such as the neuropeptide calcitonin gene-related peptide (CGRP), which are significantly associated with response to specific treatments for acute migraine attacks and prophylaxis. Epigenetic mechanisms may also be involved in the development of migraine, and understanding environmentally induced genetic changes associated with this disease may eventually guide the development of therapies capable of reversing these pathophysiological changes in gene function.

CONCLUSIONS

The understanding of the etiology of migraine is incomplete. Although the identification and validation of biomarkers has greatly advanced diagnostic precision and measures of therapeutic efficacy in other diseases, there are no currently accepted biomarkers for chronic or episodic migraine. However, the continued investigation and identification of genetic, epigenetic, and molecular biomarkers is likely to facilitate the goal of individualizing medicine by enabling clinicians to more accurately diagnose and treat migraine and other headache disorders.

Migraine and obesity, is there a link?

Obesity and migraine are two frequent conditions found in the general population. In the past years, large-scale studies have established epidemiological links between the two conditions. Migraine prevalence appears to be increased in the obese population, and some characteristics of migraine are affected in the overweight population. More recent but limited data point out an improvement of migraine in the obese population after weight loss. Obesity may facilitate migraine progression to chronic daily headache or chronic migraine. Common physiological mechanisms that would be responsible for both conditions are not fully established. Several hypotheses suggest a common etiological factor for obesity and migraine. This work proposes to review the epidemiological data and to highlight the main hypotheses currently discussed.

TNFα levels and macrophages expression reflect an inflammatory potential of trigeminal ganglia in a mouse model of familial hemiplegic migraine

Latent changes in trigeminal ganglion structure and function resembling inflammatory conditions may predispose to acute attacks of migraine pain. Here, we investigated whether, in trigeminal sensory ganglia, cytokines such as TNFα might contribute to a local inflammatory phenotype of a transgenic knock-in (KI) mouse model of familial hemiplegic migraine type-1 (FHM-1). To this end, macrophage occurrence and cytokine expression in trigeminal ganglia were compared between wild type (WT) and R192Q mutant Ca_V2.1 Ca²⁺ channel (R192Q KI) mice, a genetic model of FHM-1. Cellular and molecular characterization was performed using a combination of confocal immunohistochemistry and cytokine assays. With respect to WT, R192Q KI trigeminal ganglia were enriched in activated macrophages as suggested by their morphology and immunoreactivity to the markers Iba1, CD11b, and ED1. R192Q KI trigeminal ganglia constitutively expressed higher mRNA levels of IL1β, IL6, IL10 and TNFα cytokines and the MCP-1 chemokine. Consistent with the report that TNFα is a major factor to sensitize trigeminal ganglia, we observed that, following an inflammatory reaction evoked by LPS injection, TNFα expression and macrophage occurrence were significantly higher in R192Q KI ganglia with respect to WT ganglia. Our data suggest that, in KI trigeminal ganglia, the complex cellular and molecular environment could support a new tissue phenotype compatible with a neuroinflammatory profile. We propose that, in FHM patients, this condition might contribute to trigeminal pain pathophysiology through release of soluble mediators, including TNFα, that may modulate the crosstalk between sensory neurons and resident glia, underlying the process of neuronal sensitisation.

Prevalence of migraine in patients with celiac disease and inflammatory bowel disease

OBJECTIVE

To assess the prevalence of headache in clinic and support group patients with celiac disease and inflammatory bowel disease (IBD) compared with a sample of healthy controls.

BACKGROUND

European studies have demonstrated increased prevalence of headache of patients with celiac disease compared with controls.

METHODS

Subjects took a self-administered survey containing clinical, demographic, and dietary data, as well as questions about headache type and frequency. The ID-Migraine screening tool and the Headache Impact Test (HIT-6) were also used.

RESULTS

Five hundred and two subjects who met exclusion criteria were analyzed - 188 with celiac disease, 111 with IBD, 25 with gluten sensitivity (GS), and 178 controls (C). Chronic headaches were reported by 30% of celiac disease, 56% of GS, 23% of IBD, and 14% of control subjects (P<.0001). On multivariate logistic regression, celiac disease (odds ratio [OR] 3.79, 95% confidence interval [CI] 1.78-8.10), GS (OR 9.53, 95%CI 3.24-28.09), and IBD (OR 2.66, 95%CI 1.08-6.54) subjects all had significantly higher prevalence of migraine headaches compared with controls. Female sex (P=.01), depression, and anxiety (P=.0059) were independent predictors of migraine headaches, whereas age >65 was protective (P=.0345). Seventy-two percent of celiac disease subjects graded their migraine as severe in impact, compared with 30% of IBD, 60% of GS, and 50% of C subjects (P=.0919). There was no correlation between years on gluten-free diet and migraine severity.

CONCLUSIONS

Migraine was more prevalent in celiac disease and IBD subjects than in controls. Future studies should include screening migraine patients for celiac disease and assessing the effects of gluten-free diet on migraines in celiac disease.

The dura and migraine

This article concerns the possible role of dural changes in migraine pain. The hypothesis that changes in the dura are important in migraine pain has become widely accepted among migraine scientists. A critical examination of the evidence for and against dural involvement in migraine pain shows that in spite of the extensive research that has been carried out on dural physiology and pathophysiology, there is no hard evidence that dural changes actually occur in humans during a migraine. On the contrary, the available evidence appears to indicate that it is unlikely that dural changes are part of the migraine pain process.

Assessment of cochlear and auditory pathways in patients with migraine

PURPOSE

In this study, we aimed to determine the function of the cochlea and peripheral and central auditory pathways with migraine.

MATERIALS AND METHODS

Fifty-eight patients with migraine and 40 healthy subjects were assessed using routine diagnostic audiometry along with transient evoked otoacoustic emissions (TOAEs), distortion product otoacoustic emissions (DPOAEs), and auditory brainstem response (ABR) at high and low repetition rate frequencies.

RESULTS

Nearly two thirds of patients with migraine had one or more abnormalities in electrophysiological testing. Compared with control subjects, patients reported significant lowering of TOAEs amplitude at frequencies of 1 kHz (right: P = .0003; left: P = .002), 3 kHz (right: P = .025), and 4 kHz (right: P = .019); prolonged wave III latency (right: P = .009); and I-V interpeak latency (IPL) (left: P = .024) at high repetition rate frequencies. Significant correlations were identified between age, duration of illness and frequency of migraine and TOAEs total response and at amplitude of 4 kHz, amplitudes of DPOAEs at 1, 1.5, 2, 3, and 5 kHz and I, III and wave latencies and I-V IPL of ABR at high rate frequencies.

CONCLUSIONS

These data suggest that subclinical changes in cochlear function and auditory pathways are associated with chronic migraine. It is possible that migraine could be accompanied by compromise of blood supply of auditory system.

Adverse childhood experiences are associated with migraine and vascular biomarkers

OBJECTIVES

Migraine is a risk factor for stroke in young women. Biomarker studies implicate endothelial activation as a possible mechanism. Emerging relationships of childhood adversity with migraine, and with inflammation, a component of endothelial activation, suggest that it may play a role in the migraine-stroke association. Our objective is to evaluate the relationship between adverse childhood experiences (ACEs), migraine, and vascular biomarker levels in premenopausal women.

METHODS

Vascular and metabolic biomarkers from women 18-50 years, including 125 with migraine (interictal) and 50 without migraine, were evaluated. An ACE questionnaire was later collected by mail (response rate 80.6%, 100 migraineurs, 41 controls).

RESULTS

Migraineurs and controls were demographically similar. Migraineurs reported adversity more commonly than controls (71% vs 46%, odds ratio [OR] = 1.53, 95% confidence interval 1.07-2.17). Average ACE scores were elevated in migraineurs as compared with controls (2.4 vs 0.76, P < .001). ACE scores correlated with headache frequency (0.37, P = .001) and younger age of headache onset (-0.22, P = .04). It also correlated with body mass index (r = 0.43, P = .0001), von Willebrand factor activity (r = 0.21, P = .009), tissue plasminogen activator antigen (r = 0.28, P = .004), prothrombin activation fragment (r = 0.36, P = .001), high-sensitivity C-reactive protein (r = 0.98, P = .0001), transforming growth factor-beta1 (r = 0.28, P = .003), tissue necrosis factor-alpha (r = 0.20, P = .03), interleukin-6 (r = 0.22, P = .03), adiponectin (r = -0.29, P = .003), and nitrate/nitrite concentration (r = -314, P = .001). Logistic regression analyses (adjusted for vascular risk factors and migraine) demonstrated an association of childhood adversity with inflammatory factors (high-sensitivity C-reactive protein, interleukin-6, and tissue necrosis factor-alpha).

CONCLUSIONS

In young women, adverse childhood events are associated with migraine, particularly chronic and transformed migraine, and with vascular biomarkers, especially inflammatory biomarkers. These findings implicate early life stress as a link between migraine and endothelial activation.

Sensitization of dural afferents underlies migraine-related behavior following meningeal application of interleukin-6 (IL-6)

BACKGROUND

Migraine headache is one of the most common neurological disorders, but the pathophysiology contributing to migraine is poorly understood. Intracranial interleukin-6 (IL-6) levels have been shown to be elevated during migraine attacks, suggesting that this cytokine may facilitate pain signaling from the meninges and contribute to the development of headache.

METHODS

Cutaneous allodynia was measured in rats following stimulation of the dura with IL-6 alone or in combination with the MEK inhibitor, U0126. The number of action potentials and latency to the first action potential peak in response to a ramp current stimulus as well as current threshold were measured in retrogradely-labeled dural afferents using patch-clamp electrophysiology. These recordings were performed in the presence of IL-6 alone or in combination with U0126. Association between ERK1 and Nav1.7 following IL-6 treatment was also measured by co-immunoprecipitation.

RESULTS

Here we report that in awake animals, direct application of IL-6 to the dura produced dose-dependent facial and hindpaw allodynia. The MEK inhibitor U0126 blocked IL-6-induced allodynia indicating that IL-6 produced this behavioral effect through the MAP kinase pathway. In trigeminal neurons retrogradely labeled from the dura, IL-6 application decreased the current threshold for action potential firing. In response to a ramp current stimulus, cells treated with IL-6 showed an increase in the numbers of action potentials and a decrease in latency to the first spike, an effect consistent with phosphorylation of the sodium channel Nav1.7. Pretreatment with U0126 reversed hyperexcitability following IL-6 treatment. Moreover, co-immunoprecipitation experiments demonstrated an increased association between ERK1 and Nav1.7 following IL-6 treatment.

CONCLUSIONS

Our results indicate that IL-6 enhances the excitability of dural afferents likely via ERK-mediated modulation of Nav1.7 and these responses contribute to migraine-related pain behavior in vivo. These data provide a cellular mechanism by which IL-6 in the meninges causes sensitization of dural afferents therefore contributing to the pathogenesis of migraine headache.

Restless legs syndrome--theoretical roles of inflammatory and immune mechanisms

Theories for restless legs syndrome (RLS) pathogenesis include iron deficiency, dopamine dysregulation and peripheral neuropathy. Increased prevalence of small intestinal bacterial overgrowth (SIBO) in controlled studies in RLS and case reports of post-infectious RLS suggest potential roles for inflammation and immunological alterations. A literature search for all conditions associated with RLS was performed. These included secondary RLS disorders and factors that may exacerbate RLS. All of these conditions were reviewed with respect to potential pathogenesis including reports of iron deficiency, neuropathy, SIBO, inflammation and immune changes. A condition was defined as highly-associated if there was a prevalence study that utilized an appropriate control group. Small case reports were recorded but not included as definite RLS-associated conditions. Fifty four diseases, syndromes and conditions have been reported to cause and/or exacerbate RLS. Of these, 38 have been reported to have a higher prevalence than age-matched controls, 9 have adequate sized reports and have general acceptance as RLS-associated conditions and 7 have been reported in case report form. Overall, 42 of the 47 RLS-associated conditions (89%) have also been associated with inflammatory and/or immune changes. In addition, 43% have been associated with peripheral iron deficiency, 40% with peripheral neuropathy and 32% with SIBO. Most of the remaining conditions have yet to be studied for these factors. The fact that 95% of the 38 highly-associated RLS conditions are also associated with inflammatory/immune changes suggests the possibility that RLS may be mediated or affected through these mechanisms. Inflammation can be responsible for iron deficiency and hypothetically could cause central nervous system iron deficiency-induced RLS. Alternatively, an immune reaction to gastrointestinal bacteria or other antigens may hypothetically cause RLS by a direct immunological attack on the central or peripheral nervous system.

Local action of the proinflammatory cytokines IL-1β and IL-6 on intracranial meningeal nociceptors

BACKGROUND

Peripheral nociceptive action of the proinflammatory cytokines IL-1β and IL-6 has been implicated in the pathogenesis of numerous pain syndromes. An increase in the level of these cytokines in jugular venous blood has been reported during migraine attacks, suggesting their potential involvement in mediating the intracranial headache of migraine.

METHODS

In this work we examined, using in vivo single-unit recording of meningeal nociceptors in the trigeminal ganglion of anesthetized rats, whether the peripheral actions of IL-1β and IL-6 can promote the activation and sensitization of nociceptors that innervate the intracranial meninges, two neural processes that are believed to play a key role in promoting the intracranial throbbing pain of migraine.

RESULTS

We found that meningeal application of IL-1β leads to the activation and mechanical sensitization of about 70% and 45% of the nociceptors respectively. In contrast, IL-6 was a very poor modulator of meningeal nociceptors' response properties affecting overall only about 20% of the nociceptors.

CONCLUSIONS

Our study provides for the first time in vivo electrophysiological evidence that meningeal action of IL-1β can promote the activation and increased mechanosensitivity of intracranial meningeal nociceptors and that IL-6 generally lacks these properties. Future studies are required to examine the mechanism that plays a role in mediating the nociceptive effects of IL-1β on meningeal nociceptors, which may serve as a target for migraine therapy.

Significant differences in gene expression of GABA receptors in peripheral blood leukocytes of migraineurs

Migraine is a debilitating neurovascular disorder, with a substantial genetic component. The exact cause of a migraine attack is unknown; however cortical hyperexcitability is thought to play a role. As Gamma-aminobutyric Acid (GABA) is the major inhibitory neurotransmitter in the brain, malfunctioning of this system may be a cause of the hyperexcitability. To date, there has been limited research examining the gene expression or genetics of GABA receptors in relation to migraine. The aim of our study was to determine if GABA receptors play a role in migraine by investigating their gene expression using profile in migraine affected individuals and non-affected controls by Q-PCR. Gene expression of GABA(A) receptor subunit isoforms (GABRA3, GABRB3, GABRQ) and GABA(B) receptor 2 (GABBR2) was quantified in mRNA obtained from peripheral blood leukocytes from 28 migraine subjects and 22 healthy control subjects. Analysis of results showed that two of the tested genes, GABRA3 and GABBR2, were significantly down regulated in migraineurs (P=0.018; P=0.017), compared to controls. Results from the other tested genes did not show significant gene expression variation. The results indicate that there may be specific GABA receptor gene expression variation in migraine, particularly involving the GABRA3 and GABBR2 genes. This study also identifies GABRA3 and GABBR2 as potential biomarkers to select migraineurs that may be more responsive to GABA agonists with future investigations in this area warranted.

The biological basis of headache

This article covers the remarkable recent decades as clinicians and scientists have grappled with understanding headache. It is a challenge to understand how a 'normal' brain can become dysfunctional, incapacitating an individual, and then become 'normal' again. Does the answer lie in the anatomy, electrical pathways, the chemistry or a combination? How do the pieces fit together? The components are analyzed in this article. Animal models have provided potential answers. However, these processes have never been proven in man. The dynamic imaging of pain and headache is rapidly evolving and providing new insights and directions of research.

Intravenous dexamethasone versus morphine in relieving of acute migraine headache

Inflammation is thought to play a significant role in the underlying pathophysiology of migraine headaches which could be controlled by corticosteroids. The present study was conducted to determine and compare the pain relieving effect of dexamethasone versus morphine on patients with acute migraine headache. During this double blinded clinical trial study, 190 patients who met the International Headache Society definition of acute migraine headache were evaluated at emergency department of Tabriz Imam Reza Hospital. After giving informed consent, patients were randomly enrolled into two groups: Receiving either 8 mg dexamethasone (group A) or 0.1 mg kg(-1) morphine (group B) intravenously. Severity of the headache was determined using Visual Analog Scale (VAS) scoring method at baseline (VAS-A), 10 min (VAS-B), 60 min (VAS-C) and 24 h (VAS-D) after intervention. The mean age of patients was 44.17 +/- 16.20 years, 61.57% male and 38.43% female. The mean of VAS-A and VAS-B scores was not statistically different between two groups (p = 0.236 and p = 0.481), but the mean of VAS-C and VAS-D scores in the group A were significantly lower than the group B (p = 0.017, p = 0.010). In long-term (1 h and 24 h after administration), dexamethasone reduces the severity of acute migrant headache more than morphine.

Soluble CD40 ligand and prolactin levels in migraine patients during interictal period

The relationship of migraine with cardiovascular diseases has been clarified by many studies, and currently, migraine is suggested to be a systematic vasculopathy. Inflammation, thrombosis and impaired vascular reactivity are the underlying pathophysiological mechanisms of the vasculopathy. In the present study, we aimed to investigate the relationship between prolactin levels and subclinical atherosclerosis risk factors such as soluble CD40 ligand (sCD40L) and high-sensitivity CRP (hsCRP) in migraine patients during interictal period. Fifty female migraine patients and age-matched 25 female control cases were enrolled in the study. Migraine diagnosis was settled according to the ICHD-II diagnostic criteria. A questionnaire was completed about the existence of vascular risk factors. Serum samples were used to measure sCD40L, hsCRP and prolactin levels. No difference was found between the prolactin levels of the migraine patients and the controls. The sCD40L levels were significantly higher in migraine patients (p < 0.001). High-sensitivity CRP levels showed no difference between the groups. There was no correlation between prolactin, sCD40L, and hs-CRP levels in migraine patients. We consider that the migraine patients are prone to subclinical atherosclerosis, but this tendency is independent of prolactin levels.

Childhood abuse and migraine: epidemiology, sex differences, and potential mechanisms

Migraine and maltreatment are both common conditions that are more prevalent in women. Epidemiological evidence supports an association between childhood abuse and headache, as well as pain in general, although some controversy exists based on methodological concerns of studying the influence of remote, traumatic, stigmatizing events in an often depressed population. There is a growing scientific body of knowledge regarding the neurobiological effects of abuse on brain function and structure that suggest a possible role of early life stress in the pathogenesis of migraine, and a differential impact based on sex. Advances in our understanding of the basic mechanisms by which an adverse environment interacts with and changes the genome, may suggest new treatment strategies.

Post-traumatic stress disorder and migraine: epidemiology, sex differences, and potential mechanisms

Migraine is a common, often disabling disorder associated with a significant personal and societal burden. The presence of post-traumatic stress disorder (PTSD) may increase this disability substantially. Migraine and PTSD are both up to 3 times more common in women than in men. The divergence in prevalence rates of migraine and PTSD that occurs between the sexes after puberty suggests that gonadal hormones play an important role. In addition, the preponderance of PTSD in women may be related to their higher rates of interpersonal trauma, the most common cause of PTSD. However, recent data suggest that although the odds of PTSD are increased in both women and men with episodic migraine, this association is stronger in men than women. In this paper, we examine the epidemiology of PTSD and migraine, with an emphasis on the known sex differences. We then discuss the neurobiological changes associated with PTSD, the current hypotheses for the mechanisms relating PTSD and migraine, and the treatment implications of these findings.

Elevated S100B and neuron specific enolase levels in patients with migraine-without aura: evidence for neurodegeneration?

Although migraine has mainly been considered as a benign disease, there is cumulative evidence of silent changes in the brain, brainstem, or cerebellum and subtle subclinical cerebellar dysfunction. In this study, in order to investigate a possible neuronal and/or glial damage at the cellular level in migraine, we measured and compared serum levels of S100B which is a protein marker of glial damage or activation, and neuron specific enolase (NSE) which is a marker of neuronal damage, in migraine patients and control subjects. Serum levels of S100B and NSE were measured in blood samples from 41 patients with migraine-without aura taken during a migraine attack (ictal) and in the attack-free period between migraine attacks (interictal) and 35 age- and sex-matched controls. Patients with migraine-without aura had significantly higher ictal serum levels of S100B and NSE (P < 0.05, for both) than control subjects; whereas in the interictal phase, there was a significant increment only in S100B levels (P < 0.05) compared to controls. On the other hand, serum levels of S100B and NSE in ictal and interictal blood samples did not differ significantly. The findings of increased ictal serum S100B and NSE levels together with increased interictal levels of S100B suggested that migraine might be associated with glial and/or neuronal damage in the brain and a prolonged disruption of blood-brain barrier. Increased interictal serum levels of S100B might point out to an insidious and slow damaging process in migraine patients.

Beyond the serotonin hypothesis: mitochondria, inflammation and neurodegeneration in major depression and affective spectrum disorders

For many years, a deficiency of monoamines including serotonin has been the prevailing hypothesis on depression, yet research has failed to confirm consistent relations between brain serotonin and depression. High degrees of overlapping comorbidities and common drug efficacies suggest that depression is one of a family of related conditions sometimes referred to as the "affective spectrum disorders", and variably including migraine, irritable bowel syndrome, chronic fatigue syndrome, fibromyalgia and generalized anxiety disorder, among many others. Herein, we present data from many different experimental modalities that strongly suggest components of mitochondrial dysfunction and inflammation in the pathogenesis of depression and other affective spectrum disorders. The three concepts of monoamines, energy metabolism and inflammatory pathways are inter-related in many complex manners. For example, the major categories of drugs used to treat depression have been demonstrated to exert effects on mitochondria and inflammation, as well as on monoamines. Furthermore, commonly-used mitochondrial-targeted treatments exert effects on mitochondria and inflammation, and are increasingly being shown to demonstrate efficacy in the affective spectrum disorders. We propose that interactions among monoamines, mitochondrial dysfunction and inflammation can inspire explanatory, rather than mere descriptive, models of these disorders.

IL-1β stimulates COX-2 dependent PGE₂ synthesis and CGRP release in rat trigeminal ganglia cells

OBJECTIVE

Pro-inflammatory cytokines like Interleukin-1 beta (IL-1β) have been implicated in the pathophysiology of migraine and inflammatory pain. The trigeminal ganglion and calcitonin gene-related peptide (CGRP) are crucial components in the pathophysiology of primary headaches. 5-HT1B/D receptor agonists, which reduce CGRP release, and cyclooxygenase (COX) inhibitors can abort trigeminally mediated pain. However, the cellular source of COX and the interplay between COX and CGRP within the trigeminal ganglion have not been clearly identified.

METHODS AND RESULTS

1. We used primary cultured rat trigeminal ganglia cells to assess whether IL-1β can induce the expression of COX-2 and which cells express COX-2. Stimulation with IL-1β caused a dose and time dependent induction of COX-2 but not COX-1 mRNA. Immunohistochemistry revealed expression of COX-2 protein in neuronal and glial cells. 2. Functional significance was demonstrated by prostaglandin E2 (PGE(2)) release 4 hours after stimulation with IL-1β, which could be aborted by a selective COX-2 (parecoxib) and a non-selective COX-inhibitor (indomethacin). 3. Induction of CGRP release, indicating functional neuronal activation, was seen 1 hour after PGE(2) and 24 hours after IL-1β stimulation. Immunohistochemistry showed trigeminal neurons as the source of CGRP. IL-1β induced CGRP release was blocked by parecoxib and indomethacin, but the 5-HT1B/D receptor agonist sumatriptan had no effect.

CONCLUSION

We identified a COX-2 dependent pathway of cytokine induced CGRP release in trigeminal ganglia neurons that is not affected by 5-HT1B/D receptor activation. Activation of neuronal and glial cells in the trigeminal ganglion by IL-β leads to an elevated expression of COX-2 in these cells. Newly synthesized PGE(2) (by COX-2) in turn activates trigeminal neurons to release CGRP. These findings support a glia-neuron interaction in the trigeminal ganglion and demonstrate a sequential link between COX-2 and CGRP. The results could help to explain the mechanism of action of COX-2 inhibitors in migraine.

Risk factors of migraine-related brain white matter hyperintensities: an investigation of 186 patients

Brain white matter hyperintensities are more prevalent in migraine patients than in the general population, but the pathogenesis and the risk factors of these hyperintensities are not fully elucidated. The authors analyzed the routine clinical data of 186 migraine patients who were referred to the Outpatient Headache Department of the Department of Neurology, Medical School, University of Pécs, Hungary between 2007 and 2009: 58 patients with white matter hyperintensities and 128 patients without white matter hyperintensities on 3 T MRI. Significant associations between the presence of white matter hyperintensities and longer disease duration (14.4 vs. 19.9 years, p = 0.004), higher headache frequency (4.1 vs. 5.5 attacks/month, p = 0.017), hyperhomocysteinemia (incidence of hyperintensity is 9/9 = 100%, p = 0.009) and thyroid gland dysfunction (incidence of hyperintensity is 8/14 = 57.1%, p = 0.038) were found. These data support the theory that both the disease duration and the attack frequency have a key role in the formation of migraine-related brain white matter hyperintensities, but the effects of comorbid diseases may also contribute to the development of the hyperintensities.

Endothelium-dependent vasodilatation in migraine patients

BACKGROUND

Endothelial dysfunction could be involved in the pathophysiology of migraine. The results obtained from a few studies on endothelial dysfunction in migraine are controversial. We investigated brachial flow-mediated dilatation (FMD), which reflects systemic endothelial dysfunction, in migraine patients without comorbidities. By employing strict inclusion criteria we avoided the possible changes to FMD from confounding factors.

METHODS

Forty migraine patients without comorbidities (20 with and 20 without aura) and 20 healthy subjects were included. FMD of brachial arteries and carotid intima-media thickness were measured by using standard procedures.

RESULTS

We did not find any difference in FMD between migraine patients and healthy subjects (p = .96). Also, no differences were found among healthy subjects, migraine patients with aura and without aura (p = .99).

CONCLUSION

Our study showed that systemic endothelial function is not impaired in migraine patients without comorbidities, neither in those with or without aura. Considering these findings, the investigation of cerebral endothelial function would be useful in a further investigation of the role of endothelial (dys)function in migraine pathophysiology.

Migraine may be a risk factor for the development of complex regional pain syndrome

The aim was to assess the relative frequency of migraine and the headache characteristics of complex regional pain syndrome (CRPS) sufferers. CRPS and migraine are chronic, often disabling pain syndromes. Recent studies suggest that headache is associated with the development of CRPS. Consecutive adults fulfilling International Association for the Study of Pain criteria for CRPS at a pain clinic were included. Demographics, medical history, and pain characteristics were obtained. Headache diagnoses were made using International Classification of Headache Disorders, 2nd edn criteria. Migraine and pain characteristics were compared in those with migraine with those without. anova with Tukey post hoc tests was used to determine the significance of continuous variables and Fisher's exact or χ(2) tests for categorical variables. The expected prevalence of migraine and chronic daily headache (CDH) was calculated based on age- and gender-stratified general population estimates. Standardized morbidity ratios (SMR) were calculated by dividing the observed prevalence of migraine by the expected prevalence from the general population. The sample consisted of 124 CRPS participants. The mean age was 45.5 ± 12.0 years. Age- and gender-adjusted SMRs showed that those with CRPS were 3.6 times more likely to have migraine and nearly twice as likely to have CDH as the general population. Aura was reported in 59.7% (74/124) of participants. Of those CRPS sufferers with migraine, 61.2% (41/67) reported the onset of severe headaches before the onset of CRPS symptoms Mean age of onset of CRPS was earlier in those with migraine (34.9 ± 11.1 years) and CDH (32.5 ± 13.4 years) compared with those with no headaches (46.8 ± 14.9 years) and those with tension-type headache (TTH) (39.9 ± 9.9 years), P < 0.05. More extremities were affected by CRPS in participants with migraine (median of four extremities) compared with the combined group of those CRPS sufferers with no headaches or TTH (median 2.0 extremities), P < 0.05. The presence of static, dynamic and deep joint mechano-allodynia together was reported by more CRPS participants with migraine (72.2%) than those with no headaches or TTH (46.2%), P ≤ 0.05. Migraine may be a risk factor for CRPS and the presence of migraine may be associated with a more severe form of CRPS. Specifically: (i) migraine occurs in a greater percentage of CRPS sufferers than expected in the general population; (ii) the onset of CRPS is reported earlier in those with migraine than in those without; and (iii) CRPS symptoms are present in more extremities in those CRPS sufferers with migraine compared with those without. In addition, as we also found that the presence of aura is reported in a higher percentage of those CRPS sufferers with migraine than reported in migraineurs in the general population, further evaluation of the cardiovascular risk profile of CRPS sufferers is warranted.

Tumor necrosis factor-α induces sensitization of meningeal nociceptors mediated via local COX and p38 MAP kinase actions

The proinflammatory cytokine TNF-α has been shown to promote activation and sensitization of primary afferent nociceptors. The downstream signaling processes that play a role in promoting this neuronal response remain however controversial. Increased TNF-α plasma levels during migraine attacks suggest that local interaction between this cytokine and intracranial meningeal nociceptors plays a role in promoting the headache. Here, using in vivo single unit recording in the trigeminal ganglia of anesthetized rats, we show that meningeal TNF-α action promotes a delayed mechanical sensitization of meningeal nociceptors. Using immunohistochemistry, we provide evidence for non-neuronal localization of the TNF receptors TNFR1 to dural endothelial vascular cells and TNFR2 to dural resident macrophages as well as to some CGRP-expressing dural nerve fibers. We also demonstrate that meningeal vascular TNFR1 is co-localized with COX-1 while the perivascular TNFR2 is co-expressed with COX-2. We further report here for the first time that TNF-α evoked sensitization of meningeal nociceptors is dependent upon local action of cyclooxygenase (COX). Finally, we show that local application of TNF-α to the meninges evokes activation of the p38 MAP kinase in dural blood vessels that also express TNFR1 and that pharmacological blockade of p38 activation inhibits TNF-α evoked sensitization of meningeal nociceptors. Our study suggests that meningeal action of TNF-α could play an important role in the genesis of intracranial throbbing headaches such as migraine through a mechanism that involves at least part activation of non-neuronal TNFR1 and TNFR2 and downstream activation of meningeal non-neuronal COX and the p38 MAP kinase.

Anti-inflammatory plasma cytokines in children and adolescents with migraine headaches

Studies have shown fluctuations of cytokine levels in patients with migraine headaches; however, further studies are needed to verify these results. Our previous studies suggest increased levels of pro-inflammatory cytokines, such as IL-1alpha, sTNF-RI and TNF-alpha, in children with migraine headaches. In this study, we analyzed anti-inflammatory cytokines interleukin-4 (IL-4), interleukin-10 (IL-10) and interleukin-13 (IL-13) in plasma from children and adolescents with migraine and tension-type headaches during the interictal period. The study group consisted of 35 children and adolescents between 8-18 years old, suffering from migraine headaches with or without aura. The control group consisted of 33 patients suffering from episodic tension-type headaches. IL-4 was detected in 17.1% of patients with migraine headaches and in 28.6% of patients with tension-type headaches. IL-13 was detected in 17.1% of patients with migraine headaches and in 15.2% of patients with tension-type headaches. IL-10 was only detected in 3 of 68 (4.4%) patients. Any significant correlations between measurable cytokine levels and age, gender, aura, duration of disease, frequency and severity of headaches were determined. Any significant fluctuations of selected anti-inflammatory cytokines during the headache-free period in children with migraine and tension-type headaches have been found, immune dysfunction in migraineurs could not be excluded.

Vascular risk factors, endothelial function, and carotid thickness in patients with migraine: relationship to atherosclerosis

Recent studies indicated that migraine is associated with specific vascular risk profile. However, the functional and structural vascular abnormalities in migraine are rarely addressed. We evaluated the vascular risk factors, endothelial function, and carotid artery (CA)-intima-media thickness (IMT), segregators of preclinical atherosclerosis, in migraineurs. This preliminary study included 63 adults with headache (migraine with aura [n=14], migraine without aura [n=24], transformed migraine [n=6], and tension headache [n=19]) and 35 matched healthy subjects. The following vascular risks were assessed: body mass index (BMI), systolic blood pressure (SBP) and diastolic blood pressures (DBP), serum levels of C-reactive protein, fasting glucose, fasting insulin, total cholesterol, and triglycerides. Plasma endothelin (ET)-1, a vasoactive peptide produced by vascular smooth muscle cells and marker for endothelial injury and atherosclerosis, was measured. Endothelial-dependent vasoreactivity was assessed using brachial artery flow-mediated dilatation (FMD) in response to hyperemia. CA-IMT, structural marker of early atherosclerosis, was measured. Compared with control subjects, SBP, DBP, glucose, insulin, ET-1, and CA-IMT were elevated with migraine. FMD% was inversely correlated with SBP (P < .001), DBP (P < .01), glucose (P < .001), and insulin levels (P < .01). CA-IMT was correlated with BMI (P < .05), SBP (P < .01), total cholesterol (P < .01), triglycerides (P < .001), glucose (P < .001), insulin (P < .01), and FMD% (P < .05). In multivariate analysis, ET-1 was correlated with duration of illness, SBP, DBP, glucose, insulin, IMT, and FMD%. We conclude that endothelial injury, impaired endothelial vasoreactivity, and increased CA-IMT occur with migraine and are associated with vascular risk factors that strongly suggest that migraine could be a risk for atherosclerosis.

Calcitonin gene-related peptide: A molecular link between obesity and migraine?

Epidemiological studies have begun to suggest obesity is a risk factor for chronic migraine, although no causal relationship has been established and risk factors for progression from episodic to chronic migraine remain unknown. The neuropeptide calcitonin gene-related peptide (CGRP) plays a important role in the pathophysiology of migraine. Here, the potential role of CGRP as a molecular link between obesity and migraine is reviewed. A mechanistic association is supported by several lines of evidence: 1) common markers are elevated in obesity and migraine, 2) adipose tissue secretes proinflammatory cytokines and adipocytokines that have been implicated in migraine pathophysiology and 3) elevated levels of CGRP have been found in plasma of obese individuals. We propose that CGRP released from trigeminal neurons may represent a biological link between obesity and migraine. Enhanced trigeminal CGRP production in obese susceptible individuals may lower the threshold necessary to trigger migraine attacks, leading to more frequent episodes and eventually to chronic migraine.

Cytokine polymorphism in patients with migraine: some suggestive clues of migraine and inflammation

OBJECTIVE

There are contrasting results obtained in migraineurs concerning the levels and the role of both pro-inflammatory and anti-inflammatory cytokines. In this study, the association of the occurrence and clinical characteristics of migraine with the polymorphisms of tumor necrosis factor alpha (TNF-alpha) -308 G/A (rs1800629), interleukin-1alpha (IL-1alpha) +4845 G/T (rs17561), IL-1beta+3953 C/T (rs1143634) and interleukin-1 receptor antagonist variable number tandem repeat (IL-1RA VNTR) genes were studied. We also investigated the genetic linkage between these genes.

DESIGN, SETTING, PATIENTS

Sixty-seven patients with migraine without aura (MwoA) and 96 unrelated, age- and sex-matched migraine-free, healthy control subjects from the same geographic area were investigated.

RESULTS

We observed significant differences in the genotypic distribution of the TNF-alpha-308 G/A and IL-1beta+3953 C/T polymorphism for migraineurs compared with controls (P = 0.004). Frequency of the TNF-alpha-308 GG genotype was higher in the control group than MwoA group (82.1% vs 55.2%). Differences in the distribution of the allele frequencies were also observed, being the TNF-alpha-308 G allele overrepresented in control group and TNF-alpha-308 A allele in MwoA group. In addition, there was a significant increase of the IL-1beta+3953 T allele in MwoA cases compared with controls (P = 0.004).

CONCLUSIONS

In conclusion, the present results indicate the possible contribution of TNF-alpha and IL-1beta gene polymorphisms to migraine headache generation in MwoA patients.

The primary headaches as a reflection of genetic darwinian adaptive behavioral responses

OBJECTIVE

The objective of this study is to present a view of the primary headaches as genetically determined behavioral responses consistent with sickness behavior and defense reaction, respectively.

BACKGROUND AND DESIGN

A review of the literature bearing on the behavioral, humoral, and functional imaging aspects of the primary headaches shows that migraine and cluster headache (CH) are pain conditions characterized by different behaviors during the attacks. Here it is postulated that the behavioral responses to migraine and CH are evolutionary conserved reactions consistent with sickness behavior and defense reaction.

RESULTS

The sickness behavior observed during migraine attacks is a pan-mammalian adaptive response to internal and external stressors, characterized by withdrawal and motor quiescence, sympatho-inhibition and lethargy, in which visceral pain signals a homeostatic imbalance of the body and/or brain. In contrast, the defense reaction in CH consists of a fight-or-flight reaction, with motor restlessness and agitation, in which pain is exteroceptive in kind.

CONCLUSION

These different behavioral responses are thus specific to different kinds of pain, distinguished by the behavioral significance of the pain (visceral pain in migraine vs exteroceptive pain in CH), and imply brain matrices involving different networks in the brainstem, hypothalamus, and forebrain regions that engender evolutionarily conserved adaptive genetic responses. Cytokines play an important role in their development. Predictions and limitations of the hypothesis are discussed together with implications for genetic studies on headaches.

Migraine and obesity: epidemiology, mechanisms, and implications

Adipose tissue is a dynamic neuroendocrine organ that is involved in multiple physiological and pathological processes, and when excessive, results in obesity. Clinical and population-based data suggest that migraine and chronic daily headache are associated with obesity, as estimated by anthropometric indices. In addition, translational and basic science research shows multiple areas of overlap between migraine pathophysiology and the central and peripheral pathways regulating feeding. Specifically, neurotransmittors such as serotonin, peptides such as orexin, and adipocytokines such as adiponectin and leptin have been suggested to have roles in both feeding and migraine. In this article, we first review the definition and ascertainment of obesity. This is followed by a review of the clinical and population-based studies evaluating the associations between obesity and chronic daily headache and migraine. We then discuss the central and peripheral pathways involved in the regulation of feeding, where it overlaps with migraine pathophysiology, and where future research may be headed in light of these data.

A critical view on the role of migraine triggers in the genesis of migraine pain

A number of distinct endogenous and exogenous factors have been implicated in migraine precipitation but the exact nature of the triggering process itself and its relationship to the genesis of the headache remains largely speculative. In this article, we examine the potential sites and downstream cascades through which migraine triggers might exert their action to promote the activation of the migraine pain pathway. We further look at the laterality of the headache as a potential indicator for the site of migraine pain initiation and examine the question of triggering factor specificity in relation to the current understanding of migraine pathophysiology.

Migraine as a systemic vasculopathy

Epidemiological studies suggests that migraine is associated with disorders of the cerebral, coronary, retinal, dermal and peripheral vasculature. There is evidence that migraine is associated with endothelial dysfunction, both as a cause and a consequence. Endothelial dysfunction, a vascular risk factor, is characterized by endothelial activation and impaired vascular reactivity. Plasma and genetic biomarkers for these conditions have been identified. The clinical significance lies in the potential for the rapid identification of migraineurs at increased risk of ischaemic stroke and vascular disease through ascertainment of endothelial dysfunction biomarkers. It is uncertain whether stroke, myocardial infarction and other vasculopathies can be prevented by migraine prophylaxis, endothelial repair, platelet inhibition or a combination of these strategies.

Prophylactic drugs and cytokine and leptin levels in children with migraine

The study objective was to evaluate levels of the cytokines tumor necrosis factor alpha, interleukin-1beta, and interleukin-6 and of leptin, and then to determine the relationship between these levels and clinical responses in children with migraine after prophylactic therapy with one of four drugs. In all, 77 children who needed prophylactic drugs were treated with cyproheptadine, amitriptyline, propranolol, or flunarizine. Serum levels of the cytokines and leptin were measured before and 4 months after the treatment. Results were compared by drug for headache frequency, severity, and duration, the PedMIDAS score, and levels of each cytokine and of leptin. Each of the four drugs not only decreased the frequency and duration but also the severity of headache, and the PedMIDAS score. None of the drugs was found to be superior to others in terms of reduction in cytokine levels (P > 0.05). Both cyproheptadine and flunarizine (but not amitriptyline and propranolol) caused an increase in leptin levels (P < 0.05). These data suggest that cytokine levels are related to clinical responses, and might help in objective evaluation of clinical response in migraine. To our knowledge, the present study is the first trial to compare the effects of prophylactic drugs, cytokine levels, and leptin levels in children with migraine.