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?

DOI: https://doi.org/10.1186/s10194- 020- 01189- 0

Abstract-Summary The mechanisms through which MO facilitates the transformation of episodic migraine (EM) into chronic migraine (CM) are elusive.

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).

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Subjects in the CM-MO group were also tested 2 months after an in-hospital

detoxification protocol.

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).

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 for- mer group (n = 23) showed significantly higher levels of CGRP at baseline, and significantly lower expression of miR-382-5p after the detoxification.

CGRP levels as well as miRNAs expression were influenced by MO, and modu-

lated by detoxification in subjects with CM-MO.

Extended: As a secondary outcome, we evaluated the changes in CGRP and miR- NAs levels after detoxification in the subjects with CM-MO to gather more insights into the mechanisms that are involved in the improvement of migraine pattern fol- lowing the withdrawal of the overused medications.

The reported changes provide interesting evidences for a biological effect of detoxification and pave the way for future, larger and specifically targeted, investi- gations for the characterization and validation of migraine biomarkers, a necessary step for developing personalized therapeutic approaches.

Background Of multiple concurrent causes, it seems extremely important to investigate in more depth the mechanisms that may be involved in CM-MO.

microRNAs (miRNAs) are involved in the generation and maintenance of chronic pain and several lines of evidence suggest that specific miRNAs may play a role in migraine pain [255–257].

In order to provide further insights on the mediators involved in migraine patho- physiology and chronification, in this study we assayed the plasma levels of CGRP and the expression of miRNAs in peripheral blood mononuclear cells (PBMCs) of patients with EM and CM-MO.

As a secondary outcome, we evaluated the changes in CGRP and miRNAs levels after detoxification in the subjects with CM-MO to gather more insights into the mechanisms that are involved in the improvement of migraine pattern following the withdrawal of the overused medications.

Methods Twenty-seven subjects with EM and 28 subjects with CM-MO were consecutively enrolled among patients attending the outpatient clinics of the Headache Science Centre of the IRCCS Mondino Foundation of Pavia (Italy).

Two months after hospital discharge (T1), the CM-MO patients returned for a follow-up visit, during which clinical data were recorded and a second venous blood sample obtained from their ante-cubital vein.

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2 Mechanisms

Based on a previous study [258], we hypothesized a meaningful difference in peripheral CGRP levels between CM-MO and EM patients of at least 50.0 ± 60.0 pg/ml (effect size of 0.981).

For a statistical power of 80%, a risk of 5% for type 1 errors, and a between groups ratio of 1:1, we calculated a sample size of at least 46 patients (23 subjects with EM and 23 subjects with CM-MO).

Results CGRP plasma levels were higher in the CM-MO group (393.3 ± 242.9 pg/mL) when compared to EM patients (220.4 ± 83.42 pg/mL) (p = 0.003).

The relative expression (RQ) of miR-382-5p in PBMCs was higher in the CM-MO group (14.6 ± 3.2) when compared to EM patients (3.3 ± 0.6) (p = 0.003). CGRP, miR-382-5p, and miR-34a-5p levels correlated positively with monthly migraine days, monthly headache days, days of intake of acute drugs and monthly doses of acute drugs (p < 0.05 for all comparison).

At T1, the levels of CGRP and the expression of miR-34a-5p observed in responders and non-responders were comparable to those of EM patients (p = 0.472, and p = 0.248, respectively), while the expression of miR-382-5p was significantly lower (p = 0.006).

Discussion The main finding of this study is that the levels of CGRP and miRNAs were signifi- cantly higher in CM-MO subjects when compared to EM patients.

Our findings support the notion that our one-week detoxification protocol and the subsequent reduction of doses of acute medications (a pattern observed also in the non-responder group, though not to a statistically significant level) had an impact on peripheral levels of CGRP and miRNAs, even if it did not translate into a clinically relevant improvement in all the subjects.

It is worth noting that the detoxification program reduced CGRP, miR-34a-5p, and miR-382-5p in the CM-MO patients to levels comparable to the EM group, which further underscores the possibility that acute medication overuse actually modifies the biology of migraine.

Conclusions CGRP and miRNAs are associated with each other at the individual level across the migraine spectrum.

The peripheral levels of the molecules correlated with the clinical indicators of

migraine severity, being higher in CM-MO as compared to EM.

Detoxification from medication overuse decreased the peripheral levels of these

molecules in the group of subjects with CM-MO.

Acknowledgement A machine generated summary based on the work of Greco, Rosaria; De Icco, Roberto; Demartini, Chiara; Zanaboni, Anna Maria; Tumelero, Elena; Sances, Grazia; Allena, Marta; Tassorelli, Cristina. 2020  in The Journal of Headache and Pain.

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