Reactive oxygen species mediate modification of glycocalyx during ischemia-reperfusion injury

Abstract

The glycocalyx (Gcx) is a complex and poorly understood structure covering the luminal surface of endothelial cells. It is known to be a determinant of vascular rheology and permeability and may be a key control site for the vascular injuries caused by ischemia-reperfusion (I/R). We used intravital-microscopy to evaluate the effects of I/R injury on two properties of Gcx in mouse cremasteric microvessels: exclusion of macromolecules (anionic-dextrans) and intracapillary distribution of red blood cells (RBC). In this model, the Gcx is rapidly modified by I/R injury with an increase in 70-kDa anionic-dextran penetration without measurable effect on the penetration of 580-kDa anionic-dextran or on RBC exclusion. The effects of I/R injury appear to be mediated by the rapid production of reactive oxygen species (ROS) because they are ameliorated by the addition of exogenous superoxide dismutase-catalase. Intravenous application of allopurinol or heparin also inhibited the effects of I/R injury, and we interpret efficacy of allopurinol as evidence for a role for xanthine-oxidoreductase (XOR) in the response to I/R injury. Heparin, which is hypothesized to displace XOR from a heparin-binding domain in the Gcx, reduced the effects of I/R. The effects of I/R injury were also partially prevented or fully reversed by the intravascular infusion of exogenous hyaluronan. These data demonstrate: 1) the liability of Gcx during I/R injury; 2) the importance of locally produced ROS in the injury to Gcx; and 3) the potential importance of heparin-binding sites in modulating the ROS production. Our findings further highlight the relations between glycosaminoglycans and the pathophysiology of Gcx in vivo.

Damage of the Endothelial Glycocalyx in Dialysis Patients

“…27 Increased oxidative stress acts as a major contributor to severe atherosclerosis and cardiovascular morbidity and mortality found in these patients, 26 and reactive oxygen species can mediate alterations of the endothelial glycocalyx. 10 Overhydration is another common problem in dialysis patients, especially after loss of RRF; also, hypervolemia can alter the endothelial surface layer potentially through atrial natriuretic peptide, which causes shedding of glycocalyx constituents in blood. 16 Loss of RRF is associated with progressive impairment of endothelial function and is a risk factor of cardiovascular mortality in dialysis patients.…”

“…5 It is involved in mediating shear-induced release of nitric oxide and contributes to the endothelial permeability barrier, the regulation of redox state, and the inhibition of coagulation as well as leukocyte and platelet adhesion. [6][7][8][9] Perturbation of glycocalyx occurs after provocation with inflammatory or atherogenic stimuli (such as ischemia reperfusion, 10 infusion of oxidized LDL, 9,11 administration of TNFa 12 or endotoxin, 13 and during hyperglycemia 14 ) and after stimulation with thrombin, 15 atrial natriuretic peptide, 16 or abnormal blood shear stress. 17,18 Consequences of glycocalyx perturbation include a wide range of vascular abnormalities in experimental models, including increased vascular permeability followed by generation of tissue edema, 19 increased rolling and adhesion of leukocytes, 6 and increased platelet adhesion.…”

The endothelial glycocalyx: a review of the vascular barrier

“…In animal studies, antioxidants rapidly reversed glycocalyx damage, including polyethylene glycol [46], NO [34], adenosine agonists [45], TNF-a inhibitors [43], allopurinol, heparin and hyaluronan [47]. These agents reduced oxidative stress, cellular transudate, glycocalyx shedding and restored glycocalyx volume.…”

Hyaluronidase 1 Deficiency Preserves Endothelial Function and Glycocalyx Integrity in Early Streptozotocin-Induced Diabetes

“…Glycocalyx shedding under severe inflammatory conditions, such as postischemic reperfusion, can be prevented using various treatments, e.g., hydrocortisone, antithrombin, or heparin (35,36). Sulodexide, a mix of heparan sulfate and dermatan sulfate, increases glycocalyx thickness in type 2 diabetes (14).…”