Background: Glypican-4 (GPC4) is a Glycosylphosphatidylinositol (GPI)-anchored proteoglycan of the endothelial glycocalyx (eGCX), which was recently identified as adipokine. Proatherogenic shear stress and inflammatory mediators facilitate proteolytic shedding of GPC4 resulting in increased serum concentrations, which were shown to be associated with cardiovascular disease. Glycosylphosphatidylinositol-specific phospholipase D1 (GPLD1) is expressed in the liver and hydrolyzes the inositol phosphate linkage in GPI-anchored proteins, thereby releasing the attached protein from the plasma membrane. Thus, GPLD1 may act as sheddase of GPC4. Both, GPC4 and GPLD1, are associated with cardiovascular risk factors, such as obesity or impaired glucose tolerance. We aimed to characterize serum concentrations of GPC4 and GPLD1 in patients with ST-elevation myocardial infarction (STEMI) at two different time points.

Method: 40 STEMI patients (65% men) were included in preliminary analyses. Blood samples were obtained at admission to hospital (time point A) and 6 hours later (time point B). GPC4 and GPLD1 serum concentrations were determined by ELISA.

Results: From admission (time point A) to time point B (6 hours later), GPC4 significantly increased (p=0.002) while GPLD1 significantly decreased (p<0.001). GPC4 as well as GPLD1 strongly correlated between the two time points, but not with each other (p<0.001 each). When stratified by sex, the decrease in GPLD1 from time point A to B occurred in both sexes (p_male<0.0001, p_female<0.0001), while the increase in GPC4 reached statistical significance only in women (p_male=0.5, p_female=0.02). Nevertheless, no gender-specific differences in the serum concentrations of both parameters were observed. While as expected, a high prevalence of traditional cardiovascular risk factors such as BMI, age, diabetes mellitus or serum lipids was observed there was no association of GPC4 or GPLD1 serum concentrations to the individual presence of traditional risk factors.