Assessment of glutathione/glutathione disulphide ratio and S-glutathionylated proteins in human blood, solid tissues, and cultured cells

Daniela Giustarini, Graziano Colombo, Maria Lisa Garavaglia, Emanuela Astori, Nicola Marcello Portinaro, Francesco Reggiani, Salvatore Badalamenti, Anna Maria Aloisi, Annalisa Santucci, Ranieri Rossi, Aldo Milzani, Isabella Dalle-Donne, Free Radical Biology and Medicine, Available online 12 August 2017, ISSN 0891-5849, doi:10.1016/j.freeradbiomed.2017.08.008.

Glutathione (GSH) is the major non-protein thiol in humans and other mammals, which is present in millimolar concentrations within cells, but at much lower concentrations in the blood plasma. GSH and GSH-related enzymes act both to prevent oxidative damage and to detoxify electrophiles. Under oxidative stress, two GSH molecules become linked by a disulphide bridge to form glutathione disulphide (GSSG). Therefore, assessment of the GSH/GSSG ratio may provide an estimation of cellular redox metabolism. Current evidence resulting from studies in human blood, solid tissues, and cultured cells suggests that GSH also plays a prominent role in protein redox regulation via S-glutathionylation.

By immunohistochemistry with anti-GSH antibody, PSSG were also detected in Friedreich's ataxia, an autosomal recessive disorder caused by mutations in the gene encoding frataxin. In particular, in the cervical sections of spinal cord derived from autopsies of individuals with Friedreich's ataxia, immunostaining with anti-GSH antibodies was significantly stronger than in control sections, suggesting a significant increase in PSSG amount in all grey matter neurons, particularly in motor neurons of the anterior horns, as well as in the axonal spinal tracts (mostly in posterior white columns, spinocerebellar and corticospinal tracts). These findings suggest the occurrence of oxidative stress in the spinal cord of patients with Friedreich's ataxia as a consequence of reduced frataxin expression.