Abstract Body (Do not enter title and authors here): Background: Evidence suggests that adipocytes can release extracellular vesicles (EVs) containing mitochondria into the bloodstream, facilitating inter-organ mitochondrial transfer. Clinically, obesity and diabetes are strongly associated with the development of heart failure with preserved ejection fraction (HFpEF). Due to chronic energy stress, white adipocytes from obese or type 2 diabetic (T2D) patients may generate mitochondria that are oxidatively damaged. However, it remains unclear whether these mitochondrial fragments are encapsulated within adipocyte-derived EVs (AdEVs) and transported via the bloodstream to target organs like the heart, potentially contributing to HFpEF.
Hypothesis: We hypothesize that in patients with coronary artery disease (CAD) and concomitant T2D, the plasma levels of mitochondrial fragments within AdEVs are elevated, accompanied by increased oxidative stress, potentially correlating with the severity of HFpEF.
Methods and Results: Peripheral venous blood samples were collected from CAD patients with T2D (n=10) and healthy volunteers (n=10), followed by isolation and purification of small EVs (sEVs) from plasma. Compared to healthy controls, T2D patients exhibited significantly higher levels of oxidative stress in plasma (50±5 vs. 78±6 nmol, carbonylated protein content per plasma unit, P<0.01), which correlated with the severity of HFpEF (NT-proBNP: R²=0.64, P<0.05; E/e': R²=0.54, P<0.05). Additionally, T2D patients showed an increased number of plasma sEVs (4.15E+09 vs. 7.75E+09 particles per plasma unit, P<0.01), with enriched mitochondrial proteins (0.28±0.05 vs. 0.16±0.02 ng, TOMM20 content per sEV concentration unit, P<0.01) and elevated levels of oxidatively damaged proteins (7±2 vs. 12±2 nmol, carbonylated protein content per sEV concentration unit, P<0.01). Moreover, the proportion of AdEVs in the plasma was higher in T2D patients (5.30%±3.65% vs.17.88%±12.91% FABP4+/PKH26+ sEVs per plasma sEV unit, P<0.01). A significant positive correlation was also observed between the quantity of AdEVs and BMI in both groups (R²=0.42, P<0.01), as well as between AdEV content and the severity of HFpEF in T2D patients (NT-proBNP: R²=0.50, P<0.05; E/e': R²=0.50, P<0.05).
Conclusion: T2D patients exhibit an increase in circulating AdEVs containing oxidatively damaged mitochondrial protein fragments. These adipocyte-derived mitochondrial alterations are closely associated with elevated oxidative stress levels and the severity of HFpEF.