Stroke is characterized by deleterious oxidative stress. Selenoprotein enzymes are essential endogenous antioxidants and detailed insight into their role after stroke could define new therapeutic treatments. This systematic review aims to elucidate how blood selenoprotein concentration and activity change in the acute phase of stroke.
We searched PubMed, EMBASE and Medline databases for studies measuring serial blood selenoprotein concentration or activity in acute stroke patients or in stroke patients compared to non-stroke controls. Meta-analyses of studies stratified by type of stroke, blood compartment and type of selenoprotein measurement were conducted.
Eighteen studies and data from 941 stroke patients and 708 non-stroke controls were included in this review. Glutathione peroxidase (GPx) was the only identified selenoprotein and its activity was most frequently measured. Results from 12 studies and 693 patients, showed that, compared to non-stroke controls, in acute ischaemic stroke patients GPx activity increased in haemolysate (standardised mean difference (SMD): 0.27, 95% CI 0.07 to 0.47) but decreased in plasma (mean difference (MD): -1.08 U/L, 95% CI -1.94 to -0.22) and serum (SMD: -0.54, 95% CI -0.91 to -0.17). From four identified studies in 106 acute haemorrhagic stroke patients, GPx activity decreased in haemolysate (SMD: -0.40, 95% CI - 0.68 to -0.13) and remained unchanged in plasma (MD: -0.10 U/L, 95% CI -0.81 to 0.61) and serum (MD: -5.00 U/mL, 95% CI -36.17 to 26.17) compared to non-stroke controls. Results from studies assessing GPx activity in the haemolysate compartment were inconsistent and characterized by high heterogeneity.
Our results suggest a reduction of blood GPx activity in acute ischaemic stroke patients, a lack of evidence regarding a role for GPx in haemorrhagic stroke patients and insufficient evidence for other selenoproteins.