Revealing the Impaired MEchanisms underneath aspirin low-responder patients with DIabetes mellitus

Central hypothesis of this proposal is that patients with type 2 diabetes mellitus (T2DM) showing poor aspirin (ASA) response have an abnormal platelets (PLT) phenotype, mechanistically linked to oxidative stress (OS), leading to accelerated PLT turnover and escape from ASA given once-daily. PLT phenotype of low ASA responder T2DM patients, as reflected by accelerated PLT COX-1 recovery kinetics in the 10-24 hr dosing interval, will be characterized in terms of 1) PLT turnover 2) PLT miRNA and mRNA profiles. The role of OS as potential driver of PLT phenotype heterogeneity and poor ASA response will be assessed in vitro. In particular, activation of the NF-E2-related factor 2 (Nrf2) and its major target gene heme oxygenase-1 (HO-1) will be evaluated in order to understand the interplay between reduced antioxidant defense and shorter duration of aspirin effect. Our preliminary results indicate that human PLT express HO-1 and HO-2, which are inversely related to PLT count and immature PLT fraction in T2DM, in line with the notion that HO-1 dampens PLT production from megakaryocytes (MK). We can speculate that reduced PLT expression of HO-1, favored by enhanced OS and abnormalities in HO-1-targeting miRNAs in diabetes, may in turn accelerate PLT turnover with release of newly generated PLT with unacetylated COX-1. The functional relevance in terms of PLT turnover, response to OS, COX-1 activity, of different miRNAs, mRNAs in normal vs low-responders will be determined in vitro and in silico. Finally, the effect of antioxidant strategies on PLT phenotype and ultimately on ASA response will be assessed in vitro. Completion of the proposed research will identify: a. novel mechanisms underlying PLT hyperactivity and escape from ASA b. novel therapeutic strategies targeting OS c. biomarkers to predict suboptimal ASA response and tailor antiplatelet therapies.