Measurement of glutathionylated haemoglobin by MAL-DI-ToF mass spectrometry as a biomarker of oxidative stress in heavy smokers and in occupational obese subjects

Glutathionyl-haemoglobin (Hb-SSG) is a minor form of haemoglobin characterized by the presence of a disulfide bond between the β-93 cysteine residue and the thiol group of glutathione. Hb-SSG is naturally present in the erythrocytes at levels comparable to those of glycated haemoglobin and can be measured by MALDI mass spectrometry on very small samples of erythrocytes from peripheral blood. Since Hb-SSG has been recognized as a sensitive biomarker of oxidative stress in several degenerative diseases (diabetes, hyperlipidemia, kidney disease) and in healthy workers exposed to glutathione-depleting toxic agents such as butadiene, we have measured for the first time the levels of Hb-SSG in two groups: healthy heavy cigarette smokers and overweight-obese. For both classes of subjects, the measured levels (6.4%±1.7%, n=30 for smokers; 3.0%±0.8%, n=20 for overweight-obese) are in the upper 97thpercentile of those measured in the Italian general population. Levels in smokers show a small, yet statistically significant dependence on the level of smoking addiction (>20 cig./day vs. ￡20 cig./day: 7.0% ± 1.4% vs. 5.7% ± 1.1%; p < 0.05). This biomarker thus adds to those presently available to rationally assess the extent of biological damage caused by tobacco smoking.