DETERMINATION OF SERUM METABOLITES AMONG ASTHMA PATIENTS AFFECTED BY SMOG IN SELECTED URBAN AND RURAL AREAS OF DISTRICT FAISALABAD: A GC–MS-BASED METABOLOMIC STUDY

Abstract

South Asia is experiencing a rise in the prevalence of smog as an environmental hazard, and the systemic biochemical effects of chronic exposure in asthma patients are not fully described. The present study aimed to explore metabolic changes in the serum of asthmatic individuals living in two different environments of District Faisalabad, Pakistan, by employing gas chromatography–mass spectrometry (GC–MS). Three groups were used for obtaining serum samples: healthy controls, rural asthma patients and urban asthma patients. The differences between the groups were marked in terms of metabolite profile as revealed by GC–MS. The metabolic complexity was higher in the asthma groups than in the healthy group, as represented by the increase in the number of chromatographic peaks and in signal intensity. The number of chromatographic peaks and the abundance of metabolites were highest in urban asthma patients, reflecting the greatest level of biochemical disturbance in association with chronic exposure to urban air pollution. One-way analysis of variance (ANOVA) revealed significant differences between the groups in serum metabolites. Lactic acid rose from 1.76 ± 0.28 µmol/L in healthy controls to 3.08 ± 0.52 µmol/L in urban asthma patients (F = 9.12, p = 0.0008); palmitic acid increased from 0.89 ± 0.16 to 1.94 ± 0.31 µmol/L (F = 8.45, p = 0.001); and oleic acid rose from 0.72 ± 0.19 to 1.59 ± 0.33 µmol/L (F = 7.36, p = 0.003). Conversely, citric acid declined from 2.18 ± 0.36 to 1.48 ± 0.26 µmol/L (F = 5.72, p = 0.008). The levels of amino acid and glucose derivatives were also markedly increased in the patients with asthma. These findings suggest disruption of energy metabolism together with an increase in oxidative stress and inflammatory activity. Cluster analysis confirmed a clear separation between healthy controls and asthma patients. Altogether, the findings show that smog exposure leads to significant alterations in serum metabolism in asthma patients, and that urban subjects are most strongly affected. The metabolites detected could be used as potential biomarkers for disease monitoring and give mechanistic insights into the biochemical association between air pollution and asthma severity.