Increased interictal serum levels of CXCL8/IL-8 and CCL3/MIP-1α in migraine

Multiomic-based immune response profiling in migraine, vestibular migraine and Meniere's disease

Migraine (MI) is the most common neurological disease, affecting with 20% of the world population. A subset of 25% of MI patients showcase concurrent vestibular symptoms, which may classify as vestibular migraine (VM). Meniere's disease (MD) is a complex inner ear disorder defined by episodes of vertigo associated with tinnitus and sensorineural hearing loss with a significant autoimmune/autoinflammatory contribution, which symptoms overlap with VM. Blood samples from 18 patients with MI (5), VM (5) and MD (8) and 6 controls were collected and compared in a case-control study. Droplet-isolated nuclei from mononuclear cells used to generate scRNAseq and scATACseq data sets from MI, VM and MD. MI and VM have no differences in their immune transcriptome; therefore, they were considered as a single cluster for further analyses. Natural Killer (NK) cells transcriptomic data support a polarisation triggered by Type 1 innate immune cells via the release of interleukin (IL)-12, IL-15 and IL-18. According to the monocyte scRNAseq data, there were two MD clusters, one inactive and one driven by monocytes. The unique pathways of the MI + VM cluster were cellular responses to metal ions, whereas MD monocyte-driven cluster pathways showed responses to biotic stimuli. MI and MD have different immune responses. These findings support that MI and VM have a Type 1 immune lymphoid cell response, and that there are two clusters of MD patients, one inactive and one Monocyte-driven.

Neuron-glia crosstalk and inflammatory mediators in migraine pathophysiology

Migraine is a complex neurological disorder with neuroinflammation playing a crucial role in its pathogenesis. This review provides an overview of the neuroinflammation mechanisms in migraine, focusing on both cellular and molecular aspects. At the cellular level, we examine the role of glial cells, including astrocytes, microglia, oligodendrocytes in the central nervous system, and Schwann cells and satellite glial cells in the peripheral nervous system. On the molecular level, we explore the signaling pathways, including IL-1β, TNF-α, IL-6, and non-coding RNAs, that mediate cell interactions or independent actions. Some of the molecular signaling pathways mentioned, such as TNF-α and IL-1β, have been investigated as druggable targets. Recent advancements, such as [11C] PBR28-targeted imaging for visualizing astrocyte activation and single-cell sequencing for exploring cellular heterogeneity, represent breakthroughs in understanding the mechanisms of neuroinflammation in migraine. By considering factors for personalized treatments, estrogen and TRPM8 emerge as promising therapeutic targets regarding sexual dimorphism. These advancements may help bridge the gap between preclinical findings and clinical applications, ultimately leading to more precise and personalized options for migraine patients.

Neuroimmune interactions in the development and chronification of migraine headache

Migraine is highly prevalent and debilitating. The persistent headaches in this condition are thought to arise from the activation and sensitization of the trigeminovascular pathway. Both clinical and animal model studies have suggested that neuroimmune interactions contribute to the pathophysiology of migraine headache. In this review, we first summarize the findings from human studies implicating the dysregulation of the immune system in migraine, including genetic analyses, measurement of circulatory factors, and neuroimaging data. We next discuss recent advances from rodent studies aimed at elucidating the neuroimmune interactions that manifest at various levels of the trigeminovascular pathway and lead to the recruitment of innate and adaptive immune cells as well as immunocompetent glial cells. These cells reciprocally modulate neuronal activity via multiple pro- and anti-inflammatory mediators, thereby regulating peripheral and central sensitization. Throughout the discussions, we highlight the potential clinical and translational implications of the findings.

Causality between multiple autoimmune disorders and migraine and its subtypes: a two-sample Mendelian randomization study

Introduction

Several studies have reported associations between various autoimmune diseases and migraine. Using Mendelian randomization (MR), this study aimed to evaluate the interplay between autoimmune diseases and migraine.

Methods

Here, instrumental variables, exposure factors, and outcome factors for 10 common autoimmune diseases and migraine and its subtypes were screened. This screening utilized comprehensive statistics from Europe's largest genome-wide association study and performed reverse MR analysis on positive results. The causality between autoimmune diseases and migraine was comprehensively assessed using multiple analytical methods. Additionally, sensitivity analyses, such as the horizontal diversity heterogeneity and leave-one-out method, were performed.

Results

Random-effects inverse variance weighting analysis revealed a causal correlation between autoimmune hyperthyroidism and migraine (p = 0.0002), and this association was consistent across both migraine with aura (MA; p = 0.006) and migraine without aura (MO; p = 0.017). In addition, there was a positive causal association between systemic lupus erythematosus (SLE) and MA (p = 0.001) and between hypothyroidism and MO (p = 0.038). There is insufficient evidence to substantiate a causal link between outcomes and other autoimmune-related disorders, and reverse MR results did not reveal a causal relationship between migraines and these autoimmune disorders. The validity of the results was demonstrated by a sensitivity analysis; horizontal pleiotropy and heterogeneity were not observed.

Discussion

This study observed a positive genetic association between autoimmune hyperthyroidism and migraines. In addition, SLE positively affects MA, and hypothyroidism contributes to the incidence of MO. These results have great significance for future research and prevention of migraine.

Mind the Metabolic Gap: Bridging Migraine and Alzheimer's disease through Brain Insulin Resistance

Brain insulin resistance has recently been described as a metabolic abnormality of brain glucose homeostasis that has been proven to downregulate insulin receptors, both in astrocytes and neurons, triggering a reduction in glucose uptake and glycogen synthesis. This condition may generate a mismatch between brain's energy reserve and expenditure, ??mainly during high metabolic demand, which could be involved in the chronification of migraine and, in the long run, at least in certain subsets of patients, in the prodromic phase of Alzheimer's disease, along a putative metabolic physiopathological continuum. Indeed, the persistent disruption of glucose homeostasis and energy supply to neurons may eventually impair protein folding, an energy-requiring process, promoting pathological changes in Alzheimer's disease, such as amyloid-β deposition and tau hyperphosphorylation. Hopefully, the "neuroenergetic hypothesis" presented herein will provide further insight on there being a conceivable metabolic bridge between chronic migraine and Alzheimer's disease, elucidating novel potential targets for the prophylactic treatment of both diseases.

Altered immunity in migraine: a comprehensive scoping review

BACKGROUND

The pathogenesis of migraine remains unclear; however, a large body of evidence supports the hypothesis that immunological mechanisms play a key role. Therefore, we aimed to review current studies on altered immunity in individuals with migraine during and outside attacks.

METHODS

We searched the PubMed database to investigate immunological changes in patients with migraine. We then added other relevant articles on altered immunity in migraine to our search.

RESULTS

Database screening identified 1,102 articles, of which 41 were selected. We added another 104 relevant articles. We found studies reporting elevated interictal levels of some proinflammatory cytokines, including IL-6 and TNF-α. Anti-inflammatory cytokines showed various findings, such as increased TGF-β and decreased IL-10. Other changes in humoral immunity included increased levels of chemokines, adhesion molecules, and matrix metalloproteinases; activation of the complement system; and increased IgM and IgA. Changes in cellular immunity included an increase in T helper cells, decreased cytotoxic T cells, decreased regulatory T cells, and an increase in a subset of natural killer cells. A significant comorbidity of autoimmune and allergic diseases with migraine was observed.

CONCLUSIONS

Our review summarizes the findings regarding altered humoral and cellular immunological findings in human migraine. We highlight the possible involvement of immunological mechanisms in the pathogenesis of migraine. However, further studies are needed to expand our knowledge of the exact role of immunological mechanisms in migraine pathogenesis.

Astrocyte-Microglia Crosstalk: A Novel Target for the Treatment of Migraine

Migraine is a pervasive neurologic disease closely related to neurogenic inflammation. The astrocytes and microglia in the central nervous system are vital in inducing neurogenic inflammation in migraine. Recently, it has been found that there may be a crosstalk phenomenon between microglia and astrocytes, which plays a crucial part in the pathology and treatment of Alzheimer's disease and other central nervous system diseases closely related to inflammation, thus becoming a novel hotspot in neuroimmune research. However, the role of the crosstalk between microglia and astrocytes in the pathogenesis and treatment of migraine is yet to be discussed. Based on the preliminary literature reports, we have reviewed relevant evidence of the crosstalk between microglia and astrocytes in the pathogenesis of migraine and summarized the crosstalk pathways, thereby hoping to provide novel ideas for future research and treatment.

Genetic causal relationship between immune diseases and migraine: a Mendelian randomization study

Background

Migraine has an increased prevalence in several immune disorders, but genetic cause-effect relationships remain unclear. Mendelian randomization (MR) was used in this study to explore whether immune diseases are causally associated with migraine and its subtypes.

Methods

We conducted a two-sample bidirectional multivariate Mendelian randomization study. Single-nucleotide polymorphisms (SNP) for six immune diseases, including rheumatoid arthritis (RA), systemic lupus erythematosus (SLE), type 1 diabetes mellitus (T1D), allergic rhinitis (AR), asthma and psoriasis, were used as genetic instrumental variables. Summary statistics for migraine were obtained from 3 databases: the International Headache Genetics Consortium (IHGC), UK Biobank, and FinnGen study. MR analyses were performed per outcome database for each exposure and subsequently meta-analyzed. Reverse MR analysis was performed to determine whether migraine were risk factors for immune diseases. In addition, we conducted a genetic correlation to identify shared genetic variants for these two associations.

Results

No significant causal relationship was found between immune diseases and migraine and its subtypes. These results were robust with a series of sensitivity analyses. Using the linkage disequilibrium score regression method (LDSC), we detected no genetic correlation between migraine and immune diseases.

Conclusion

The evidence from our study does not support a causal relationship between immune diseases and migraine. The mechanisms underlying the frequent comorbidity of migraine and several immune diseases need to be further elucidated.

Cytokines in primary headache disorders: a systematic review and meta-analysis

BACKGROUND

The role of inflammation and cytokines in the pathophysiology of primary headache disorders is uncertain. We performed a systematic review and meta-analysis to synthesise the results of studies comparing peripheral blood cytokine levels between patients with migraine, tension-type headache, cluster headache, or new daily persistent headache (NDPH), and healthy controls; and in migraine between the ictal and interictal stages.

METHODS

We searched PubMed/Medline and Embase from inception until July 2022. We included original research studies which measured unstimulated levels of any cytokines in peripheral blood using enzyme-linked immunosorbent assay or similar assay. We assessed risk of bias using the Newcastle-Ottawa Quality Assessment Scale. We used random effects meta-analysis with inverse variance weighted average to calculate standardised mean difference (SMD), 95% confidence intervals, and heterogeneity for each comparison. This study is registered with PROSPERO (registration number CRD42023393363). No funding was received for this study.

RESULTS

Thirty-eight studies, including 1335 patients with migraine (32 studies), 302 with tension-type headache (nine studies), 42 with cluster headache (two studies), and 1225 healthy controls met inclusion criteria. Meta-analysis showed significantly higher interleukin (IL)-6 (SMD 1.07, 95% CI 0.40-1.73, p = 0.002), tumour necrosis factor (TNF)-α (SMD 0.61, 95% CI 0.14-1.09, p = 0.01), and IL-8 (SMD 1.56, 95% CI 0.03-3.09, p = 0.04), in patients with migraine compared to healthy controls, and significantly higher interleukin-1β (IL-1β) (SMD 0.34, 95% CI 0.06-0.62, p = 0.02) during the ictal phase of migraine compared to the interictal phase. Transforming growth factor (TGF)-β (SMD 0.52, 95% CI 0.18-0.86, p = 0.003) and TNF-α (SMD 0.64, 95% CI 0.33-0.96, p = 0.0001) were both higher in patients with tension-type headache than controls.

CONCLUSIONS

The higher levels of the proinflammatory cytokines IL-6, IL-8 and TNF-α in migraine compared to controls, and IL-1β during the ictal stage, suggest a role for inflammation in the pathophysiology of migraine, however prospective studies are required to confirm causality and investigate the mechanisms for the increase in cytokine levels identified. Cytokines may also have a role in tension-type headache. Due a lack of data, no conclusions can be made regarding cluster headache or NDPH.

Examining the correlation between salivary cytokine concentrations and CRP in people experiencing social-cognitive stress

OBJECTIVES

The study aims to determine the relationship of migraine and chronic tension-type headache (TTHs) with alterations in the salivary markers of inflammation .

METHODS

The prospective study involved 75 patients . The concentrations of inflammatory markers (CRP, IL-1 β, and IL-6) in migraine and chronic TTH patients were determined in distinct time points: headache-free period (interictal period), during headache (ictal period), day after headache attack. The STAI-Y (State Trait Anxiety Inventory - Y) and BDI (Beck Depression Inventory) questionnaires were used to measure the level of anxiety and depression in the interictal and ictal periods.

RESULTS

The interictal levels of CRP, IL1-β, and IL-6 were significantly higher in headache groups compared to healthy controls (p < 0.001). Differences in the ictal concentrations were even stronger. Twenty-four hours after headache attack, patients with migraine and chronic TTH experienced a decrease in CRP, IL1-β, and IL-6 levels; yet, those levels were still higher compared with the interictal ones. The repeated analysis of variance revealed no significant statistical differences in CRP, IL-β, and IL-6 levels between the migraine and TTH groups over time (p > 0.05). Statistically higher levels of anxiety and depression were seen in unhealthy groups (p < 0.01).

CONCLUSIONS

The relationship of CRP, IL1-β, and IL-6 concentrations with migraine and chronic TTH has been established. No statistically significant differences were found in the dynamics between migraine and chronic TTH groups. There was a direct correlation of migraine and chronic TTH with anxiety and depression.

The effects of nano-curcumin supplementation on Th2/tregulatory axis in migraine patients: a randomized, double-blind, placebo-controlled trial

AIM

In the present study we aimed to investigate the effects of nano-curcumin supplementation on gene expression and serum levels of IL-4 and TGF-β in migraine patients.

METHODS

Forty participants with episodic migraine were randomly allocated to receive 80 mg nano-curcumin (n = 20) or placebo (n = 20) in a randomized double-blind clinical trial for two months. At the beginning and the end of the study, the interictal serum levels and gene expression of IL-4 and TGF-β in peripheral blood mononuclear cells (PBMCs) isolated from migraine patients were measured, using ELISA and real-time PCR methods, respectively.

RESULTS

Intra-group assays showed a significant rise in the gene expression of both IL-4 and TGF-β (p < 0.05) in nano-curcumin group after two months of treatment, however the serum levels were only significantly changed for IL-4 (p < 0.05). On the contrast, inter-group assays revealed no statistical differences between nano-curcumin and placebo group in terms of IL-4 and TGF-β gene expression, while the serum levels of IL-4 was observed to be increased significantly (p = 0.03) following two month nano-curcumin supplementation.

CONCLUSION

The findings of the present trial suggest that the treatment with nano-curcumin could induce significant levels of IL-4, in favour of anti-inflammatory effects, while has a minimal effects on the both gene expression and serum levels of TGF-β. Further studies are required to determine the exact mechanism of action of curcumin in patients with migraine.

Association of Body Mass Index, Blood Pressure, and Interictal Serum Levels of Cytokines in Migraine with and without Aura

The aim of the study was to clarify correlations between body mass index (BMI), blood pressure (BP), and serum levels of cytokines in female migraine patients. A total of 14 migraineurs with aura, and 12 without aura during their interictal period were compared with 25 controls. Interleukin-8 (IL-8), soluble intercellular adhesion molecule-1 (sICAM-1), soluble vascular cell adhesion molecule-1 (sVCAM-1), matrix metalloproteinase-9 (MMP-9), interferon gamma (IFN-γ), monocyte chemoattractant protein-1 (MCP-1), transforming growth factor alpha (TGF-α), and plasminogen activator inhibitor-1 (PAI-1) were measured. Migraineurs have elevated levels of IL-8, but decreased serum levels of PAI-1 and sICAM-1 during the interictal period, regardless of aura. BMI correlates with BP, and also with IFN-γ and MMP-9 only in patients with aura. There are three correlations in migraine patients with aura that are absent in patients without aura: between IL-8 and PAI-1; MMP-9 and IL-8; and IL-8 and sICAM-1. Migraineurs without aura, on the other hand, have correlations that patients with aura do not have (between PAI-1 and MCP-1, sICAM-1; between MMP-9 and sICAM-1, MCP-1; between TGF-α and PAI-1, MMP-9, sICAM-1; between sICAM-1 and MMP-9, PAI-1, MCP-1; as well as between sVCAM-1 and MCP-1). PAI-1, TGF, and MMP-9 could be used as biomarkers to distinguish migraineurs from healthy individuals.

The role of cytokines in migraine: A systematic review

BACKGROUND

Cytokines are important endogenous substances that are involved in immune and inflammatory responses. Neurogenic inflammation has been proposed to play a role in migraine involving altered cytokine levels. Therefore, we aimed to provide a systematic review on the current knowledge on cytokine levels in migraine patients during and outside attacks.

METHODS

Databases of PubMed and Embase were systematically searched for studies investigating cytokine levels in migraine patients during and outside attacks.

RESULTS

Screening yielded identification of 45 articles investigating 18 cytokines in total. We found that the interictal level of the anti-inflammatory cytokine, interleukin 10, was decreased, while the level of transforming growth factor beta 1 was increased in migraine patients compared to controls. Levels of pro-inflammatory cytokines, tumor necrosis factor α and interleukin 6, were increased outside attacks compared to controls. Ictal levels of cytokines were unchanged or varying compared to the interictal state in migraine patients. Three studies reported dynamic cytokines levels during the course of an attack.

CONCLUSION

The findings of the current review underline a possible involvement of cytokines in the proposed inflammatory mechanisms of migraine. However, future studies are needed to expand our knowledge of the exact role of cytokines in the migraine pathophysiology with focus on cytokines TNF-α, IL-1ß, IL-6 and IL-10 while applying refined methodology.

Immunological findings in patients with migraine and other primary headaches: a narrative review

Experimental findings suggest an involvement of neuroinflammatory mechanisms in the pathophysiology of migraine. Specifically, preclinical models of migraine have emphasized the role of neuroinflammation following the activation of the trigeminal pathway at several peripheral and central sites including dural vessels, the trigeminal ganglion, and the trigeminal nucleus caudalis. The evidence of an induction of inflammatory events in migraine pathophysiological mechanisms has prompted researchers to investigate the human leukocyte antigen (HLA) phenotypes as well as cytokine genetic polymorphisms in order to verify their potential relationship with migraine risk and severity. Furthermore, the role of neuroinflammation in migraine seems to be supported by evidence of an increase in pro-inflammatory cytokines, both ictally and interictally, together with the prevalence of Th1 lymphocytes and a reduction in regulatory lymphocyte subsets in peripheral blood of migraineurs. Cytokine profiles of cluster headache (CH) patients and those of tension-type headache patients further suggest an immunological dysregulation in the pathophysiology of these primary headaches, although evidence is weaker than for migraine. The present review summarizes available findings to date from genetic and biomarker studies that have explored the role of inflammation in primary headaches.

Headache and immunological/autoimmune disorders: a comprehensive review of available epidemiological evidence with insights on potential underlying mechanisms

Several lines of evidence support a role of the immune system in headache pathogenesis, with particular regard to migraine. Firstly, alterations in cytokine profile and in lymphocyte subsets have been reported in headache patients. Secondly, several genetic and environmental pathogenic factors seem to be frequently shared by headache and immunological/autoimmune diseases. Accordingly, immunological alterations in primary headaches, in particular in migraine, have been suggested to predispose some patients to the development of immunological and autoimmune diseases. On the other hand, pathogenic mechanisms underlying autoimmune disorders, in some cases, seem to favour the onset of headache. Therefore, an association between headache and immunological/autoimmune disorders has been thoroughly investigated in the last years. The knowledge of this possible association may have relevant implications in the clinical practice when deciding diagnostic and therapeutic approaches. The present review summarizes findings to date regarding the plausible relationship between headache and immunological/autoimmune disorders, starting from a description of immunological alteration of primary headaches, and moving onward to the evidence supporting a potential link between headache and each specific autoimmune/immunological disease.

SCFA Treatment Alleviates Pathological Signs of Migraine and Related Intestinal Alterations in a Mouse Model of NTG-Induced Migraine

Background: There is a growing realization that the gut–brain axis signaling is critical for maintaining the health and homeostasis of the Central Nervous System (CNS) and the intestinal environment. The role of Short-Chain Fatty Acids (SCFAs), such as Sodium Propionate (SP) and Sodium Butyrate (SB), has been reported to counteract inflammation activation in the central and Enteric Nervous System (ENS). Methods: In this study, we evaluated the role of the SCFAs in regulating the pathophysiology of migraine and correlated dysregulations in the gut environment in a mouse model of Nitroglycerine (NTG)-induced migraine. Results: We showed that, following behavioral tests evaluating pain and photophobia, the SP and SB treatments attenuated pain attacks provoked by NTG. Moreover, treatments with both SCFAs reduced histological damage in the trigeminal nerve nucleus and decreased the expression of proinflammatory mediators. Ileum evaluation following NTG injection reported that SCFA treatments importantly restored intestinal mucosa alterations, as well as the release of neurotransmitters in the ENS. Conclusions: Taken together, these results provide evidence that SCFAs exert powerful effects, preventing inflammation through the gut–brain axis, suggesting a new insight into the potential application of SCFAs as novel supportive therapies for migraine and correlated intestinal alterations.

Identification of disease- and headache-specific mediators and pathways in migraine using blood transcriptomic and metabolomic analysis

BACKGROUND

Recent data suggest that gene expression profiles of peripheral white blood cells can reflect changes in the brain. We aimed to analyze the transcriptome of peripheral blood mononuclear cells (PBMC) and changes of plasma metabolite levels of migraineurs in a self-controlled manner during and between attacks.

METHODS

Twenty-four patients with migraine were recruited and blood samples were collected in a headache-free (interictal) period and during headache (ictal) to investigate disease- and headache-specific alterations. Control samples were collected from 13 age- and sex-matched healthy volunteers. RNA was isolated from PBMCs and single-end 75 bp RNA sequencing was performed using Illumina NextSeq 550 instrument followed by gene-level differential expression analysis. Functional analysis was carried out on information related to the role of genes, such as signaling pathways and biological processes. Plasma metabolomic measurement was performed with the Biocrates MxP Quant 500 Kit.

RESULTS

We identified 144 differentially-expressed genes in PBMCs between headache and headache-free samples and 163 between symptom-free patients and controls. Network analysis revealed that enriched pathways included inflammation, cytokine activity and mitochondrial dysfunction in both headache and headache-free samples compared to controls. Plasma lactate, succinate and methionine sulfoxide levels were higher in migraineurs while spermine, spermidine and aconitate were decreased during attacks.

CONCLUSIONS

It is concluded that enhanced inflammatory and immune cell activity, and oxidative stress can play a role in migraine susceptibility and headache generation.

Role of Neuroinflammation and Blood-Brain Barrier Permutability on Migraine

Currently, migraine is treated mainly by targeting calcitonin gene-related peptides, although the efficacy of this method is limited and new treatment strategies are desired. Neuroinflammation has been implicated in the pathogenesis of migraine. In patients with migraine, peripheral levels of pro-inflammatory cytokines, such as interleukin-1β (IL-1β) and tumor necrosis factor-α, are known to be increased. Additionally, animal models of headache have demonstrated that immunological responses associated with cytokines are involved in the pathogenesis of migraine. Furthermore, these inflammatory mediators might alter the function of tight junctions in brain vascular endothelial cells in animal models, but not in human patients. Based on clinical findings showing elevated IL-1β, and experimental findings involving IL-1β and both the peripheral trigeminal ganglion and central trigeminal vascular pathways, regulation of the Il-1β/IL-1 receptor type 1 axis might lead to new treatments for migraine. However, the integrity of the blood-brain barrier is not expected to be affected during attacks in patients with migraine.

Chemokines and Pain in the Trigeminal System

Chemotactic cytokines or chemokines are a large family of secreted proteins able to induce chemotaxis. Chemokines are categorized according to their primary amino acid sequence, and in particular their cysteine residues that form disulphide bonds to maintain the structure: CC, CXC, CX3C, and XC, in which X represents variable amino acids. Among their many roles, chemokines are known to be key players in pain modulation in the peripheral and central nervous systems. Thus, they are promising candidates for novel therapeutics that could replace current, often ineffective treatments. The spinal and trigeminal systems are intrinsically different beyond their anatomical location, and it has been suggested that there are also differences in their sensory mechanisms. Hence, understanding the different mechanisms involved in pain modulation for each system could aid in developing appropriate pharmacological alternatives. Here, we aim to describe the current landscape of chemokines that have been studied specifically with regard to trigeminal pain. Searching PubMed and Google Scholar, we identified 30 reports describing chemokines in animal models of trigeminal pain, and 15 reports describing chemokines involved in human pain associated with the trigeminal system. This review highlights the chemokines studied to date at different levels of the trigeminal system, their cellular localization and, where available, their role in a variety of animal pain models.

Metabolic Aspects of Migraine: Association With Obesity and Diabetes Mellitus

Migraine is a disabling neurovascular disorder, characterized by moderate to severe unilateral headaches, nausea, photophobia, and/or phonophobia, with a higher prevalence in women than in men, which can drastically affect the quality of life of migraine patients. In addition, this chronic disorder is related with metabolic comorbidities associated with the patient's lifestyle, including obesity and diabetes mellitus (DM). Beyond the personal and socioeconomic impact caused by migraine, obesity and DM, it has been suggested that these metabolic disorders seem to be related to migraine since: (i) they are a risk factor for developing cardiovascular disorders or chronic diseases; (ii) they can be influenced by genetic and environmental risk factors; and (iii) while clinical and epidemiological studies suggest that obesity is a risk factor for migraine, DM (i.e., type 1 and type 2 DM) have been reported to be either a protective or a risk factor in migraine. On this basis, and given the high worldwide prevalence of migraine, obesity, and DM, this article provides a narrative review of the current literature related to the association between the etiology and pathophysiology of migraine and these metabolic disorders, considering lifestyle aspects, as well as the possible involvement of neurotransmitters, neuropeptides, and/or sex hormones. While a link between migraine and metabolic disorders has been suggested, many studies are contradictory and the mechanisms involved in this association are not yet sufficiently established. Therefore, further research should be focused on understanding the possible mechanisms involved.

Differential Expression of Cytokine-Coding Genes among Migraine Patients with and without Aura and Normal Subjects

Migraine is a prevalent disorder in humans and represents one of the top 10 causes of years lived with disability. Several genetic and environmental factors are involved in the pathobiology of migraine. A number of studies have underscored the role of dysregulated immune reactions. We compared the expression levels IL-2, IL-4, CXCL8, IL-17, IFN-γ, TGF-β and TNF-α cytokines in blood specimens of patients with migraine and those of healthy persons to identify any possible dysregulation in their expression and to propose mechanisms for this disorder. Expression of INF-γ was suggestively higher in migraine cases than in healthy individuals (posterior beta = 0.35, adjusted P value = 0.017). In addition, expression of this cytokine was lower in female subjects than in male subjects (posterior beta = -0.712, adjusted P value = 0.012). Expression of IL-4, TGF-β and TNF-α was also higher in cases compared with controls (posterior beta = 1.34, adjusted P value = 0.04; posterior beta = 0.849, adjusted P value = 0.036; posterior beta = 0.451, adjusted P value = 0.042, respectively). On the other hand, CXCL8 expression was lower in migraine cases than in controls (posterior beta = -0.78, adjusted P value = 0.039). Expression levels of IL-1B, IL-17 and IL-2 were not meaningfully different between cases and controls. The current study highlights the dysregulation of cytokine-coding genes in the blood of patients with migraine.

Therapeutic implications of cortical spreading depression models in migraine

Migraine is among the most common and disabling neurological diseases in the world. Cortical spreading depression (CSD) is a wave of near-complete depolarization of neurons and glial cells that slowly propagates along the cortex creating the perception of aura. Evidence suggests that CSD can trigger migraine headache. Experimental models of CSD have been considered highly translational as they recapitulate migraine-related phenomena and have been validated for screening migraine therapeutics. Here we outline the essential components of validated experimental models of CSD and provide a comprehensive review of potential modulators and targets against CSD. We further focus on novel interventions that have been recently shown to suppress CSD susceptibility that may lead to therapeutic targets in migraine.

Salivary inflammatory markers in tension type headache and migraine: the SalHead cohort study

OBJECTIVE

To investigate the possible association between salivary CRP, IL-1β, and IL-6 levels, depression/anxiety and migraine, and tension type headache (TTH) in saliva of these patients.

METHOD

A longitudinal prospective study was conducted on 30 migraineurs, 30 TTH patients, and 30 age-matched healthy controls. Anxiety and depression were measured by using the Hamilton Anxiety Rating Scale (HAM-A), and the Beck Depression Inventory (BDI). Salivary IL-6, IL-1β, and CRP were collected in distinct time points as A: headache-free period, B: during headache, C: 1 day after headache attack, and measured by using ELISA kits.

RESULTS

No significant differences were found in time variation of CRP, IL-1β, and IL-6 levels between migraine and TTH (p > 0.05). IL1-β had the highest discriminative value (area under the curve = 0.924, p value < 0.001), and then CRP (area under the curve = 0.763, p value < 0.001) and IL-6 (area under the curve = 0.537, p value = 0.58). CRP and IL-6 were negatively correlated with HAM-A and BDI scores.

CONCLUSION

IL1-β had the highest discriminative value between headache patients and controls compared with CRP and IL-6. CRP and IL-6 were correlated with lower symptom scores of anxiety and depression prior or immediately after the headache period in patients groups.

The serum level of inflammatory markers in chronic and episodic migraine: a case-control study

The exact mechanism of the migraine pathophysiology remained unclear. Although there are some reports showing low-grade inflammation in migraineurs, further studies are needed in this field. Thus, we designed a study to evaluate the serum levels of two main proinflammatory markers in migraine patients. In this case-control research, 43 migraine patients (23 chronic and 20 episodic migraineurs) and 40 age-sex-matched headache-free controls were studied. Demographic, dietary, and anthropometric data, headache characteristics, and serum C-reactive proteins (CRP) and tumor necrosis factor-alpha (TNF-α) assessments were collected. The mean ± SD age of the case and control groups were 36.98 ± 9.91 and 34.84 ± 9.75 years respectively. Compared to control subjects, both episodic and chronic migraineurs had significantly higher median levels of TNF-α (0.24, 0.95, and 1.90 pg/ml, respectively; P value < 0.001). Also, we observed a positive association between the TNF-α levels and the odds of having migraine after considering gender, age, body mass index, and dietary intakes of energy, carbohydrate, protein, fat, and mono and poly unsaturated fatty acids in the multivariable regression models (OR = 2.15; 95% CI 1.31-3.52; P value < 0.001). However, no significant association was demonstrated between migraine and serum CRP (OR = 2.91; 95% CI 0.87-9.78; P value = 0.08). These findings supported that inflammatory state could be related to the pathogenesis of migraine and it can thus be suggested that this effect might be beyond migraine progression. Further detailed studies are needed to investigate the importance of these findings in the pathogenesis of migraine headache.

Acute Zika Virus Infection in an Endemic Area Shows Modest Proinflammatory Systemic Immunoactivation and Cytokine-Symptom Associations

An early immune response to Zika virus (ZIKV) infection may determine its clinical manifestation and outcome, including neurological effects. However, low-grade and transient viremia limits the prompt diagnosis of acute ZIKV infection. We have investigated the plasma cytokine, chemokine, and growth factor profiles of 36 individuals from an endemic area displaying different symptoms such as exanthema, headache, myalgia, arthralgia, fever, hyperemia, swelling, itching, and nausea during early-phase infection. These profiles were then associated with symptoms, revealing important aspects of the immunopathophysiology of ZIKV infection. The levels of some cytokines/chemokines were significantly higher in acute ZIKV-infected individuals compared to healthy donors, including interferon (IFN) gamma-induced protein 10 (IP-10), regulated on activation, normal T cell expressed and secreted (RANTES), IFN-γ, interleukin (IL)-9, IL-7, IL-5, and IL-1ra, including some with predominantly immunoregulatory activity. Of note, we found that higher levels of IP-10 and IL-5 in ZIKV-infected individuals were strongly associated with exanthema and headache, respectively. Also, higher levels of IL-1ra were associated with subjects with arthralgia, whereas those with fever showed lower levels of granulocyte-colony stimulating factor (G-CSF). No correlation was observed between the number of symptoms and ZIKV viral load. Interestingly, only IP-10 showed significantly decreased levels in the recovery phase. In conclusion, our results indicate that acute ZIKV infection in a larger cohort resident to an endemic area displays a modest systemic immune activation profile, involving both proinflammatory and immunoregulatory cytokines and chemokines that could participate of virus control. In addition, we showed that differential cytokine/chemokine levels are related to specific clinical symptoms, suggesting their participation in underlying mechanisms.

Unbalanced plasma TNF-α and IL-12/IL-10 profile in women with migraine is associated with psychological and physiological outcomes

Increased plasma pro-inflammatory and decreased anti-inflammatory cytokines have been implicated in physiological and behavioural aspects of mood- and pain-related disorders, including migraine. In this case-control study, we assessed mood scores, cardiorespiratory fitness (VO_2Peak), and plasma concentrations of TNF-α, IL-1β, IL-6, IL-8, IL-10, and IL-12p70 interictally in women with episodic migraine with/without aura (ICHD-II), taking no preventive medicine, and in healthy women recruited from São Paulo Hospital and local community, respectively. Thirty-seven participants (mean±SD age=34±10 and BMI=26.5±4.9) were assessed. Groups (Control, n=17; Migraine, n=20) showed no differences in age, BMI, and VO_2Peak. Migraine patients showed higher tension (p=0.019) and anxiety scores (p=0.046), TNF-α (p<0.01), and IL-12p70 (p=0.01), while IL-6 (p<0.01), IL-8 (p<0.01), and IL-10 (p<0.01) were decreased compared to control group. Multiple linear regression models showed that migraine was positively associated with TNF-α and IL-12p70, and negatively associated with IL-6, IL-8, and IL-10. Anxiety scores were positively associated with IL-12p70, and VO_2Peak was negatively associated with TNF-α. In conclusion, an exaggeratedly skewed cytokine profile, in particular the TNF-α and 12p70/IL-10 balance may be related to migraine pathomechanisms, and its psychiatric comorbidities and functional capacity. Additional studies are needed to confirm these results.

Serum levels of adiponectin, CCL3/MIP-1α, and CCL5/RANTES discriminate migraine from tension-type headache patients

OBJECTIVES

Inflammatory molecules and neurotrophic factors are implicated in pain modulation; however, their role in primary headaches is not yet clear. The aim of this study was to compare the levels of serum biomarkers in migraine and tension-type headache.

METHODS

This was a cross-sectional study. We measured serum levels of adiponectin, chemokines, and neurotrophic factors in patients with migraine and tension-type headache. Depression and anxiety symptoms, headache impact and frequency, and allodynia were recorded.

RESULTS

We included sixty-eight patients with migraine and forty-eight with tension-type headache. Cutaneous allodynia (p = 0.035), CCL3/MIP-1α (p = 0.041), CCL5/RANTES (p = 0.013), and ADP (p = 0.017) were significantly higher in migraine than in tension-type headache. The differences occurred independently of anxiety and depressive symptoms, frequency and impact of headache, and the presence of pain.

CONCLUSIONS

This study showed higher CCL3/MIP-1α, CCL5/RANTES, and ADP levels in migraine in comparison with tension-type headache. Our findings suggest distinctive roles of these molecules in the pathophysiology of these primary headaches.

Increased Serum CD14 Level Is Associated with Depletion of TNF-α in Monocytes in Migraine Patients during Interictal Period

The aim of the present study was to investigate the levels of circulating CD14 in relation to the expression of tumor necrosis factor alpha (TNF-α) in monocytes, and serum levels of TNF-α and macrophage inflammatory protein-1 (MIP-1) in migraine patients. Numerous studies revealed controversial changes in the components of the immune system during attacks and the interictal period in migraine patients. Our study included 40 migraineurs and 39 controls. The levels of TNF-α, MIP-1 and CD14 were measured in peripheral monocytes and in sera with the Enzyme-Linked Immunosorbent Assay (ELISA) method, and the monocyte expression of TNF-α was also analysed by immunostaining. Serum CD14 concentrations were higher and the expression of TNF-α in monocytes was decreased in migraineurs. The serum MIP-1 level correlated with Verbal Rating Scale (VRS); the MIP-1:CD14 ratio in monocytes correlated with Visual Analogue Scale (VAS); the MIP-1:CD14 ratio correlated with Migraine Severity (MIGSEV)-Pain scores; and serum CD14 concentration correlated with migraine duration in years. Increased serum CD14 and depletion of TNF-α in monocytes can orchestrate other components of the immune system during the interictal period.

Exercise-Induced Change in Plasma IL-12p70 Is Linked to Migraine Prevention and Anxiolytic Effects in Treatment-Naïve Women: A Randomized Controlled Trial

OBJECTIVE

To conduct a randomized controlled trial to evaluate the effect of a 12-week aerobic exercise program for migraine prevention, plasma cytokines concentrations (TNF-α, interleukin [IL]-1β, IL-6, IL-8, IL-10, and IL-12p70), and anxiety in women with migraine.

METHODS

Women with episodic migraine (ICHD-II), aged between 20 and 50 years, who had never taken any prophylactic medication, and were physically inactive in the past 12 months were recruited from the university's hospital and a tertiary headache clinic between March 2012 and March 2015. Migraine attacks were recorded in headache diaries, cytokines were quantified by flow cytometry, and anxiety was assessed by the 7-item General Anxiety Disorder (GAD-7) scale. Blood sampling and psychometric interviews were undertaken on headache-free days.

RESULTS

Twenty participants ([mean ± SD] age 33.8 ± 10.5; BMI 26 ± 5.2) were randomly assigned and received intervention ("trained": n = 10) or entered on a waitlist ("inactive": n = 10). There were no differences between groups regarding patients' characteristics and baseline data. Days with migraine (p = 0.001), IL-12p70 levels (p = 0.036), and GAD-7 score (p = 0.034) were significantly reduced in the trained group after the intervention period, but there were no significant changes in these variables in the inactive group. There was no change in the levels of the other cytokines in either group. There were positive correlations between a reduction in IL-12p70 level and a reduction in the number of days with migraine (R2 = 0.19, p = 0.045), and GAD-7 score (R2 = 0.53, p < 0.001).

CONCLUSION

The clinical and psychological therapeutic effects of aerobic exercise in treatment-naïve women with migraine may involve the downregulation of IL-12p70.

Association between sequence variations of the Mediterranean fever gene and the risk of migraine: a case-control study

Migraine pathogenesis involves a complex interaction between hormones, neurotransmitters, and inflammatory pathways, which also influence the migraine phenotype. The Mediterranean fever gene (MEFV) encodes the pyrin protein. The major role of pyrin appears to be in the regulation of inflammation activity and the processing of the cytokine pro-interleukin-1β, and this cytokine plays a part in migraine pathogenesis. This study included 220 migraine patients and 228 healthy controls. Eight common missense mutations of the MEFV gene, known as M694V, M694I, M680I, V726A, R761H, K695R, P369S, and E148Q, were genotyped using real-time polymerase chain reaction with 5' nuclease assays, which include sequence specific primers, and probes with a reporter dye. When mutations were evaluated separately among the patient and control groups, only the heterozygote E148Q carrier was found to be significantly higher in the control group than in the patient group (P=0.029, odds ratio [95% confidence interval] =0.45 [0.21-0.94]). In addition, the frequency of the homozygote and the compound heterozygote genotype carrier was found to be significantly higher in patients (n=8, 3.6%) than in the control group (n=1, 0.4%) (P=0.016, odds ratio [95% confidence interval] =8.57 [1.06-69.07]). However, there was no statistically significant difference in the allele frequencies of MEFV mutations between the patients and the healthy control group (P=0.964). In conclusion, the results of the present study suggest that biallelic mutations in the MEFV gene could be associated with a risk of migraine in the Turkish population. Moreover, MEFV mutations could be related to increased frequency and short durations of migraine attacks (P=0.043 and P=0.021, respectively). Future studies in larger groups and expression analysis of MEFV are required to clarify the role of the MEFV gene in migraine susceptibility.