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

Abstract

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

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

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

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

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

Keywords: Biomarkers; CGRP; Detoxification; Headache; Medication overuse; MicroRNA; Migraine; Pain.

Conflict of interest statement

CT received honoraria for the participation to advisory boards or for oral presentations from: Allergan, ElectroCore, Eli-Lilly, Novartis, and Teva. CT has no ownership interest and does not own stocks of any pharmaceutical company. CT serves as Chief Section Editor of Frontiers in Neurology—Section Headache Medicine and Facial Pain and on the editorial board of The Journal of Headache and Pain. GS received honoraria for the participation to advisory boards or for oral presentations from: Eli-Lilly and Novartis. The remaining authors have no conflicts of interest.

Figures

Fig. 1

CGRP plasma levels, and miR-382-5p and miR-34a-5p expression in peripheral blood mononuclear cells of subjects with episodic migraine and chronic migraine with medication overuse. EM: episodic migraine (n = 27); CM-MO: chronic migraine with medication overuse (n = 28). Panel a: comparison of CGRP between EM and CM-MO subjects. Panel b: comparison of miR-382-5p between EM and CM-MO subjects. Panel c: comparison of miR-34a-5p between EM and CM-MO subjects. Box-plots: the distance between the top and bottom of the box represents the interquartile range (IQR: 25th percentile to 75th percentile). The line inside the box represents the median value, while the cross inside the box represents the mean value. The upper and lower whiskers represent the maximum and minimum values respectively (outliers excluded). Black dots above the upper whiskers represent possible outliers (outliers are statistically defined as values outside the 75th percentile + 1.5*IQR). Δ: EM vs. CM-MOH: p < 0.005 (Mann-Whitney Test with post-hoc Bonferroni’s correction). RQ: Relative quantification: 2−∆∆Ct = 2 − (∆Ct gene − ∆Ct housekeeping gene); Ct: cycle threshold

Fig. 2

Changes in CGRP plasma levels and miR-382-5p and miR-34a-5p expression in peripheral blood mononuclear cells of subjects with chronic migraine with medication overuse treated with a detoxification protocol. Study population: n = 28; 30% responders: n = 23; 30% non-responders: n = 5. PBMCs: peripheral blood mononuclear cells. Panel a: changes in CGRP plasma levels after detoxification. Panel b: changes in miR-382-5p expression in PBMCs after detoxification. Panel c: changes in miR-34-5p expression in PBMCs after detoxification. The box in the panels highlights the results of statistical analysis performed with two factors, non-parametric test for repeated measures: factor TIME: T0 vs. T1; factor GROUP: 30% responders vs. non-responders. Dashed lines represent estimates for each patient (red: 30% responders; black: 30% non-responders). Continuous lines represent the mean of the group (red: 30% responders; black: 30% non-responders). T0: baseline evaluation; T1: 2 months after discharge from in-hospital detoxification. RQ: Relative quantification: 2−∆∆Ct = 2 − (∆Ct gene − ∆Ct housekeeping gene); Ct: cycle threshold as defined in methods section