Redox Balance of Thiols in the Exhaled Breath Condensate (EBC) in Addition to Blood Samples in Two Populations with Different Exposure to Traffic Related Pollutants

ROSALIA ZANGARI (1), Francesco Cetta (1,2), Valentina Guercio (1), Gianfranco Schiraldi (3), Marco Sala (3), Paolo Laviano (1), Marie Guinea Montalvo(4), Giorgia Giussani (4), Massimo Monti (2), Cinzia Dellanoce (4), Antonio Ballarin Denti (5), Luigi Allegra(3), Roberto Accinni (4)

(1)University of Siena, Siena, Italy (2)Geriatric Institute “Pio Albergo Trivulzio” (PAT), Milan, Italy (3) University of Milan ,Milan, Italy (4)CNR Institute of Clinical Physiology, Milan, Italy (5)University “Cattolica del Sacro Cuore”, Brescia, Italy

     Abstract Number: 2485
     Last modified: February 8, 2010

Abstract
Air-pollution promotes ROS generation and oxidative stress, causing imbalance of the antioxidant endogenous system.
The aim of this study has been to evaluate the role of thiol analysis by HPLC – cysteine (Cys), cysteinylglycine (CG), homocysteine (Hcy) and glutathione (GSH), which are redox balance parameters – for the early recognition of at risk-subjects in a population exposed to environmental pollution. In a heavy polluted city, such as Milan, Italy, a group of subjects (n=38, age 82±9) living in nursing homes for retired people was enrolled and compared to a control population (n=42, age 70±8), living in Aprica, a remote alpine site, (1181 m a.s.l), with low traffic volume, in order to evaluate adverse health effects of traffic related air-pollution.
Methods: Daily levels of PM10, PM2,5 and PM1 were measured both by OPC detectors and HPLC analysis on blood samples was performed for the evaluation of thiols (plasma total and reduced forms PT, PR respectively; erythrocytes total and reduced forms ET, ER respectively). In addition, samples of exhaled
breath concentrate (EBC) were also collected and HPLC analysis was performed for evaluation of thiol levels in the EBC.
Results: There was no evident difference in the GSH levels between the two populations, PR GSH was 2,2 ±1,0 micro-molar in Milan and 1,4 ± 0,8 in Aprica (p=0,026). In fact, GSH alteration is usually a late event, occurring in severe imbalances and no subject in both groups had clinically evident diseases. On the contrary, PT Cys was 459,8 ±152,2 vs 286,3 ±74,8 (p<0,001) and ER Cys 2,5±0,8 vs 1,5 ±0,6 (p<0,001), respectively. The increase in PT and PR Cys (a pro-oxidant) was likely caused by a lower intake into the erythrocyte. In the Milan's group high Hcy levels indicated that it was not being used for cystationine synthesis. Moreover, the excessive presence of P Hcy and P Cys promoted the production of ROS, altering redox state and cell homeostasis.
Data concerning thiol balance analysis from EBC showed: 1) a striking individual variability of the various chromatographic peaks; 2) almost complete absence of reduced species. These data must be interpreted with caution, because they are the first in the literature.
Conclusion: Inhabitants of areas with different traffic volumes show significantly different Cys CG and Hcy levels, even if GSH remains unchanged, suggesting a greater- pro-oxidant effect in more exposed populations, affecting Cys CG and Hcy levels, before GSH alterations. Analysis of thiol redox balance in plasma and erythrocytes is able to distinguish between more and less exposed subjects and could be a useful diagnostic tool for early detection of subjects at higher risk of health effects from environmental pollution.
In particular, thiol analysis in EBC could be a very early marker of redox imbalance, and be used to detect early alterations in predisposed subjects.
This work was supported by the PROLIFE-Prolife, City of Milan, Italy.