Plasma 7-ketocholesterol, cholestane-3β, 5α, 6β-triol and malondialdehyde levels in asthma patients

Asthma is a global health problem affecting 1%–18% of the population in different countries. An estimated 300 million people worldwide suffer from asthma, with 250.000 annual deaths attributed to this disease. Particularly, prevalence of allergic asthma gradually increases in the world, depending on air pollution, climatic changes and other environmental stimulants. In allergic conditions, oxidative stress occurs as a result of activation of the immune system. Oxidative stress is known to play a role in asthma as well as other chronic diseases, and there is strong evidences that asthma severity is a determinant. Lipid peroxidation is a form of oxidative stress that involves oxidation of fatty acids by enzymatic and/or non-enzymatic reactions. Oxidation of cholesterol leads to the formation of a large number of oxidation products known as oxysterols. Oxysterols, which resulted from spontaneous or enzymatic oxidation of cholesterol, are potentially non-invasive biomarkers of oxidative stress in vivo. Determination of oxysterol and malondialdehyde (MDA, one of the end products of lipid peroxidation) levels in the blood of patients with allergic asthma can provide information about the role of oxidative stress in the pathogenesis of allergic asthma, and may exhibit new approaches to the diagnosis and treatment processes. In this study, plasma 7-ketocholesterol and cholestane-3β, 5α, 6β-triol levels of total 120 asthma patients (90 females + 30 males) and 120 healthy controls (matched by age and sex) were quantified by LC-MS/MS (liquid chromatography-tandem mass spectrometry) method. In addition, plasma MDA levels were analyzed by spectrophotometric method dpending on the measurement of TBARS (thiobarbituric acid reactive substances). Plasma 7-ketocholesterol (39.45±20.37 ng/mL) and cholestan-3β,5α,6β-triol (25.61±10.13 ng/mL) levels in patients were significantly higher than those in healthy subjects (17.84±4.26 ng/mL (p<0.001) and 10.00±3.90 ng/mL, respectively) (p<0.001). Significant positive correlations were observed between oxysterol levels and MDA and total IgE levels. The plasma MDA was found to be significantly higher in the asthmatics (4.98±1.77 nmol/mL) as compared to healthy controls (1.14±0.31 nmol/mL) (p<0.001). In conclusion, since lipid peroxidation by- and end-products seem to be closely related to the complication of allergic asthma, plasma 7-ketocholesterol, cholestan-3β,5α,6β-triol and MDA levels may represent helpful and valuable biochemical parameters for at least diagnosis and prognosis in asthma. This study provides a strong basis for further studies on the involvement of lipid peroxidation and the roles of oxysterols, especially in allergic asthma.