Unravelling the role of beta-CGRP in inflammatory bowel disease and its potential role in gastrointestinal homeostasis.

BACKGROUND: The role of beta calcitonin gene-related peptide (beta-CGRP) in gastrointestinal tract is obscure, but experimental models suggest an effect on the homeostasis of the intestinal mucosa. We measured beta-CGRP circulating levels in a large series of subjects with a recent diagnosis of inflammatory bowel disease (IBD), in order to assess the potential role of this neuropeptide in IBD pathogenesis. METHODS: Morning serum beta-CGRP levels were measured by ELISA (CUSABIO, China) in 96 patients recently diagnosed of IBD and compared with those belonging from 50 matched healthy controls (HC) and 50 chronic migraine (CM) patients. RESULTS: Beta-CGRP levels were lower in patients with IBD (3.1 ± 1.9 pg/mL; 2.9 [2.4-3.4] pg/mL) as compared to HC (4.7 ± 2.6; 4.9 [4.0-5.8] pg/mL; p < 0.001) and to CM patients (4.6 ± 2.6; 4.7 [3.3-6.2] pg/mL; p < 0.001). Beta-CGRP levels in CM were not significantly different to those of HC (p = 0.92). Regarding IBD diagnostic subtypes, beta-CGRP levels for ulcerative colitis (3.0 ± 1.9pg/mL; 2.5 [2.1-3.4] pg/mL) and Crohn's disease (3.3 ± 2.0 pg/mL; 3.2 [2.4-3.9] pg/mL) were significantly lower to those of HC (p < 0.01 and p < 0.05, respectively) and CM (p < 0.01 and p < 0.05, respectively). CONCLUSIONS: We have found a significant reduction in serum beta-CGRP levels in patients with a recent diagnosis of all kinds of IBD as compared to two control groups without active intestinal disease, HC and CM, which may suggest a role for this neuropeptide in the pathophysiology of IBD. Our data indicate a protective role of beta-CGRP in the homeostasis of the alimentary tract.

Differences in circulating alpha-calcitonin gene-related peptide levels in inflammatory bowel disease and its relation to migraine comorbidity: A cross-sectional study.

OBJECTIVE: To analyze the specificity of calcitonin gene-related peptide (CGRP) levels, we measured alpha-CGRP circulating levels in a large series of patients with a recent diagnosis of inflammatory bowel disease (IBD) who were interviewed regarding comorbid headache. BACKGROUND: Several studies have found an association between migraine and IBD. METHODS: In this cross-sectional study performed in an IBD clinic, morning serum alpha-CGRP levels were measured by enzyme-linked immunosorbent assay in 96 patients who were recently diagnosed with IBD and compared to those from 50 similar patients with chronic migraine (CM) and 50 healthy controls (HC). RESULTS: Alpha-CGRP levels were higher in patients with IBD (median [interquartile range] 56.9 [35.6-73.9] pg/mL) and patients with CM (53.0 [36.7-73.9] pg/mL) compared to HC (37.2 [30.0-51.8] pg/mL; p = 0.003; p = 0.019, respectively). Regarding IBD diagnostic subtypes, alpha-CGRP levels for ulcerative colitis (67.2 ± 49.3 pg/mL; 57.0 [35.6-73.4] pg/mL) and Crohn's disease (54.9 ± 27.5 pg/mL; 57.7 [29.1-76.1] pg/mL) were significantly higher than those of HC (p = 0.013, p = 0.040, respectively). Alpha-CGRP levels were further different in patients with IBD with migraine (70.9 [51.8-88.7] pg/mL) compared to HC (p < 0.001), patients with IBD without headache (57.5 [33.3-73.8] pg/mL; p = 0.049), and patients with IBD with tension-type headache but without migraine (41.7 [28.5-66.9] pg/mL; p = 0.004), though alpha-CGRP levels in patients with IBD without migraine (53.7 [32.9-73.5] pg/mL) remained different over HC (p = 0.028). CONCLUSION: Together with CM, circulating alpha-CGRP levels are different in patients with IBD, perhaps reflecting a chronic inflammatory state. IBD is an example of how alpha-CGRP levels are not a totally specific migraine biomarker. However, alpha-CGRP levels were further increased in patients with IBD who have a history of migraine, which reinforces its role as a biomarker in migraine patients, always bearing in mind their comorbidities.

Untangling the mess of CGRP levels as a migraine biomarker: an in-depth literature review and analysis of our experimental experience.

BACKGROUND: Calcitonin gene-related peptide (CGRP) is the most promising candidate to become the first migraine biomarker. However, literature shows clashing results and suggests a methodological source for such discrepancies. We aimed to investigate some of these methodological factors to evaluate the actual role of CGRP as biomarker. METHODS: Previous to the experimental part, we performed a literature review of articles measuring CGRP in migraine patients. Using our 399 bio-bank sera samples, we performed a series of experiments to test the validity of different ELISA kits employed, time of sample processing, long-term storage, sampling in rest or after moderate exercise. Analysis of in-house data was performed to analyse average levels of the peptide and the effect of sex and age. RESULTS: Literature review shows the high variability in terms of study design, determination methods, results and conclusions obtained by studies including CGRP determinations in migraine patients. CGRP measurements depends on the method and specific kit employed, also on the isoform detected, showing completely different ranges of concentrations. Alpha-CGRP and beta-CGRP had median with IQR levels of 37.5 (28.2-54.4) and 4.6 (2.4-6.4)pg/mL, respectively. CGRP content is preserved in serum within the 24 first hours when samples are stored at 4°C after clotting and immediate centrifugation. Storages at -80°C of more than 6 months result in a decrease in CGRP levels. Moderate exercise prior to blood extraction does not modulate the concentration of the peptide. Age positively correlates with beta-CGRP content and men have higher alpha-CGRP levels than women. CONCLUSIONS: We present valuable information for CGRP measurements in serum. ELISA kit suitability should be tested prior to the experiments. Alpha and beta-CGRP levels should be analysed separately as they can show different behaviours even within the same condition. Samples can be processed in a 24-h window if they have been kept in 4°C and should not be stored for more than 6 months at -80°C before assayed. Patients do not need to rest before the blood extraction unless they have performed a high-endurance exercise. For comparative studies, sex and age should be accounted for as these parameters can impact CGRP concentrations.

Increased prevalence of migraine in women with inflammatory bowel disease: A cross-sectional study.

BACKGROUND: Some studies have suggested an association between migraine and inflammatory bowel disease. We determined migraine prevalence in a cohort of patients with inflammatory bowel disease. METHODS: Patients with inflammatory bowel disease aged 18-65 years were interviewed using an ad hoc headache questionnaire. Those who admitted a history of headache in the last year answered the three questions of the ID-Migraine questionnaire. Those who answered "yes" to the three of them were classified as "definite" and those who answered "yes" to two were classified as "probable" migraine. RESULTS: We interviewed 283 patients with inflammatory bowel disease. Of these, 176 (62.2%) had headache. Fifty-nine (20.8%; 95% CI 16.3-26.0%) met migraine criteria either definite (n = 33; 11.7%; 95% CI 8.2-16.0%) or probable (n = 26; 9.2%; 95% CI 6.1-13.2). When divided by gender, 12 men (9.6%; 95% CI 5.1-16.2%) and 47 women (29.8%; 95% CI 22.8-37.5%) met migraine criteria. The prevalence of migraine was increased in inflammatory bowel disease patients from the current cohort (20.8%) versus that reported for our general population for the same age group (12.6%; p < 0.0001). These differences remained significant in female inflammatory bowel disease patients (29.8% versus 17.2% in our general population; p < 0.0001), but not in males (9.6% in inflammatory bowel disease vs 8.0%; p = 0.30). Seventeen patients with inflammatory bowel disease (6.0%; 95% CI 3.54-9.44%) fulfilled chronic migraine criteria. There were no differences in migraine prevalence by inflammatory bowel disease subtypes. CONCLUSION: Migraine prevalence, including chronic migraine, seems to be increased in patients with inflammatory bowel disease. The fact that this association was stronger for women suggests an influence of sex-related factors.