3.1 Heat stress and LPS induced damage and degradation of endothelial glycocalyx
Glycocalyx content Given previous study suggesting the importance of HSPG in accessing the content of endothelial glycocalyx,21 HPSG expression was firstly investigated in HPMEC among 4 groups under heat stress and LPS. Stimulation of heat stress and LPS decreased HSPG expression compared with those in CON group (P< 0.05) (Figure 1A~C ), as indicated by immunofluorescent staining and flow cytometry. Interestingly, HSPG expression was higher in HSPG group whereas lower in UFH group than that in HS+LPS group (P < 0.05) (Figure 1A~C ). These results indicated that heat stroke decreased the content of endothelial glycocalyx, which glycocalyx damage was attenuated by UFH.
Levels of glycocalyx degradation products Considering that SDC-1 and heparin sulfate were identified as the classical degraded products of endothelial glycocalyx, 22 we, therefore, evaluated the expression of them. The results suggested that the expressions of SDC-1 and heparin sulfate were significantly lower in CON group than that in others (P < 0.05) (Figure 1D ). Interestingly, UFH may prevent endothelial glycocalyx from degrading as evidenced by the lower expression in UFH group compared with HS+LPS and HPSE groups (P < 0.05). These results revealed that heat stress and LPS may induce endothelial glycocalyx degradation in HPMEC, which showed a positive correlation with the degree of glycocalyx damage.