Reactive oxygen species (ROS) are produced by living organisms as a result of normal cellular metabolism and environmental factors, such as air pollutants or cigarette smoke. ROS are highly reactive molecules and can damage cell structures such as carbohydrates, nucleic acids, lipids, and proteins and alter their functions. The shift in the balance between oxidants and antioxidants in favor of oxidants is termed “oxidative stress.” Regulation of reducing and oxidizing (redox) state is critical for cell viability, activation, proliferation, and organ function. Aerobic organisms have integrated antioxidant systems, which include enzymatic and nonenzymatic antioxidants that are usually effective in blocking harmful effects of ROS. However, in pathological conditions, the antioxidant systems can be overwhelmed. Oxidative stress contributes to many pathological conditions and diseases, including cancer, neurological disorders, atherosclerosis, hypertension, ischemia/perfusion, diabetes, acute respiratory distress syndrome, idiopathic pulmonary fibrosis, chronic obstructive pulmonary disease, and asthma. In this review, we summarize the cellular oxidant and antioxidant systems and discuss the cellular effects and mechanisms of the oxidative stress.

Background: Chronic spontaneous urticaria (CSU) in childhood is infrequent, and information about the disease in children is limited. We attempted to investigate its etiologic factors, natural course, and predictors of prognosis. Methods: All children aged ≤18 years followed for CSU during an 8-year period were analyzed retrospectively, and the final outcomes were queried via a telephone interview. Results: One hundred patients (male/female ratio 1.27) with a median age of 9.2 years (range 0.7–17.2) at symptoms onset were evaluated. The median follow-up was 2.5 years (range 0.2–18.1). An autologous serum skin test was positive in 46.7% of the subjects (n = 45), with a female predominance (71.4%) (p = 0.023). In 13.8% of the children, ANA titers were over 1/100. Food allergy (n = 1), thyroid autoantibodies (n = 3), possible collagen disease (n = 1), and drug usage (deferoxamine) (n = 1) were found to be associated factors. Infections could not be confirmed as the cause of CSU. Recovery was seen in 16.5, 38.8, and 50.0% of the children after 12, 36, and 60 months, respectively. Though in multivariate analysis none of the factors, including age, gender, autologous serum skin test positivity, the presence of angioedema, or other allergic diseases, appeared to predict the prognosis, in univariate analysis being female and being older than 10 years of age predicted an unfavorable prognosis. Conclusion: The etiology of CSU in children is mainly related to an autoreactive background, as in adults. CSU has a favorable prognosis, and resolution is seen in half of the children within 5 years. Girls older than 10 years may have an unfavorable prognosis.

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Asthma is a chronic inflammatory lung disease that results in airflow limitation, hyperreactivity, and airway remodeling. There is strong evidence that an imbalance between the reducing and oxidizing systems favoring a more oxidative state is present in asthma. Endogenous and exogenous reactive oxygen species, such as superoxide anion, hydroxyl radical, hypohalite radical, and hydrogen peroxide, and reactive nitrogen species, such as nitric oxide, peroxynitrite, and nitrite, play a major role in the airway inflammation and are determinants of asthma severity. Asthma is also associated with decreased antioxidant defenses, such as superoxide dismutase, catalase, and glutathione. In this review, we will summarize the current knowledge and discuss the current and future strategies for the modulation of oxidative stress in asthma.

An imbalance between the production of reactive oxygen species and the capacity of antioxidant defense mechanisms favoring oxidants is called oxidative stress and is implicated in asthmatic inflammation and severity. Major reactive oxygen species that are formed endogenously include hydrogen peroxide, superoxide anion, hydroxyl radical, and hypohalite radical; and the major antioxidants that fight against the endogenous and environmental oxidants are superoxide dismutase, catalase, and glutathione. Despite the well-known presence of oxidative stress in asthma, studies that target oxidative burden using a variety of nutritional, pharmacological, and environmental approaches have generally been disappointing. In this review, we summarize the current knowledge on oxidative stress and antioxidant imbalance in asthma. In addition, we focus on possible biomarkers of oxidative stress in asthma and on current and future treatment strategies using the modulation of oxidative stress to treat asthma patients.