Diabetes mellitus (DM) is associated with excess mortality, that is mainly, though not exclusively attributable to increased cardiovascular disease (CVD) risk. Unfortunately, such increased risk is not accurately estimated by the multivariable prediction models based upon traditional CVD risk factors. There is, therefore, the need to identify novel biomarkers able to improve the performance of existing algorithms. Recently, attention has been focused on circulating microRNAs (miRNAs).
This project is aimed at evaluating the association of circulating miRNAs with a composite endpoint (all-cause mortality, nonfatal acute myocardial infarction, nonfatal stroke) in patients with type 2 DM (T2DM) from the Sapienza University Mortality and Morbidity Event Rate (SUMMER) Study in Diabetes.
The SUMMER Study in Diabetes is an observational, prospective, multicenter, cohort study comprising 5,000 T2DM patients recruited in the years 2014-2018, who will be followed for at least 5 years. At baseline, traditional CVD risk factors have been assessed, together with prevalence of CVD events, nephropathy and retinopathy. Based on the present follow-up duration and a preliminary estimate of 3% yearly incidence rate of the composite outcome, by June 30, 2019 315 cases will be collected and matched with 315 controls using a propensity score matching for the UKPDS risk score variables. The entire mirnome will be analyzed in a "discovery" case-control sample (n=24 each) by nest generation sequencing. Then, the 10 most dysregulated miRNAs (plus 6 miRNA reported to be associated with myocardial infarction in the general population) will be validated in a "validation" nested case-control sample (n=315 each) by qRT-PCR.
This project is expected to provide evidence of an association between individual miRNAs and the composite CVD outcome. This information will allow improving CVD risk prediction in T2DM patients and eventually indicate new research directions and future therapeutic strategies.
The novelty of this research proposal lies in the evaluation of the entire circulating mirnome to identify additional biomarkers for improving prediction of all-cause mortality and CVD events in patients with T2DM. In addition, this proposal uses an innovative two-step strategy. The first step consists of the "discovery" of the circulating miRNAs associated with a composite CVD outcome (all-cause mortality, non-fatal AMI, non-fatal stroke) by analyzing the entire mirnoma by NGS. The second step consists of the "validation" by qRT-PCR of the 10 most dysregulated (either up or down-regulated) miRNAs, as derived from the discovery sample, and 6 miRNA, previously shown to be associated with AMI in the general population (regardless of whether they are included in the 10 miRNAs derived from the discovery sample). Another strength of this proposal is the use of blood samples from the well-characterized patients with T2DM from the SUMMER cohort, which will allow to match cases and controls for multiple parameters such as the UKPDS risk score variables.
This project is expected to provide evidence of an association between individual miRNAs and the composite outcome, including all-cause mortality and major CVD event, in patients with T2DM. Our hypothesis is that this information might improve risk prediction in individuals with T2DM by ameliorating the performance of multivariable prediction models based upon multiple traditional CVD risk factors. This will allow identifying and treating in a timely and appropriate manner those individuals carrying a relative high risk of death and/or CVD events. In addition, identifying the miRNAs associated with our composite outcome will allow gaining insights into the molecular pathways involved in macrovascular complications of T2DM, thus eventually indicating new research directions and future therapeutic strategies.
In conclusion, this project has the potential to pave the way for innovative personalized medicine for prediction and prevention of mortality and CVD events in patients with T2DM.