NMU DNA methylation in blood is associated with metabolic and inflammatory indices: results from the Moli-sani study

ABSTRACT

Neuromedin U (NMU) is a neuropeptide involved in gut-brain axis, energy balance and immune response. We aimed at analysing the association between NMU epigenetic variability and metabolic indices and the potential mediating role of low-grade inflammation in a general population of Italian adults.

NMU Blood DNA methylation levels at two CpG islands (NMU76 and NMU32) were analysed using pyrosequencing in a randomly selected sub-cohort of 1,160 subjects from the Moli-sani study (≥35years; 49.20% men). Multivariable regressions adjusted for age, sex, smoking, alcohol and vegetable consumption were performed to estimate the associations between methylation and metabolic phenotypes (BMI, waist-to-hip ratio, blood pressure, glucose, HOMA-IR, lipids, lipoprotein(a) and apolipoproteins). Mediation analysis was performed to identify the influence of low-grade inflammation in the association using a composite index based on C reactive protein, granulocyte-to-lymphocyte ratio (GLR), platelet and white blood cell counts (INFLA-score).

Using principal component analysis four methylation factors were identified: NMU76-F1, NMU76-F2, NMU32-F1 and NMU32-F2. NMU76-F1 was FDR significantly associated with total cholesterol (for 1 SD increase: β = 4.5 ± 1.4 mg/dL of, R² = 10.8%, p = 0.001), ApoB (0.03 ± 0.01 g/L, 12.2%, p = 0.0004), with INFLA-score (1.05 ± 0.22, p = 2.7E-6) and GLR (-0.27 ± 0.03, 30.4%, p = 1.3E-20). GLR and lymphocyte numbers mediate the association of NMU76-F1 with cholesterol (24.0% of total effect, Sobel p = 0.013) and ApoB (42.6%, p = 9E-7), respectively.

These findings suggest that NMU promoter methylation patterns could mark a pathway linking lipids with haematopoiesis and systemic inflammation.

KEYWORDS:

• DNA methylation
• low-grade inflammation
• metabolic indices
• neuromedin U
• cardiovascular risk
• white blood cell count
• apolipoprotein B
• granulocyte-to-lymphocyte ratio

Authors’ contributions

AM, BI and FG designed the study and wrote the manuscript. AM performed the methylation experiments; FG performed statistical analyses; BI designed and supervised the methylation experiments; FN designed and performed the methylation experiments; RP and AT performed the sample DNA extraction; AG and AdC provided statistical support; SC managed the databases and provided statistical support; CC, MBD, GdG and LI were at the origin of the conception of the Moli-sani cohort and participated in the design of the study; all authors critically reviewed and approved the manuscript.

Disclosure statement

No potential conflict of interest was reported by the authors

Supplementary material

Supplemental data for this article can be accessed here.

Additional information

Funding

The enrollment phase of the Moli-sani Study was supported by research grants from the Pfizer Foundation (Rome, Italy), the Italian Ministry of University and Research (MIUR, Rome, Italy)–Programma Triennale di Ricerca, Decreto no.1588 and Instrumentation Laboratory, Milan, Italy. Laboratory analyses of the Moli-sani study were partially supported by BiomarCaRE (Biomarkers for Cardiovascular Risk Assessment in Europe): European Commission Seventh Framework Programme FP7/2007-2013 (HEALTH-F2-2011-278913) (L.I.). The work reported in this manuscript was partially supported by the Fondazione Umberto Veronesi, Milan, Italy (2014 Young Investigator Research Programme award to F.G.) and the Italian Ministry of Health (2011 Young Investigator Grant no. 167/GR-2011-02351736 to F.G.) Funders had no role in study design; collection, analysis or interpretation of data, the writing of the manuscript, or the decision to submit the article for publication.