Urinary Leukotriene E4 Levels in Wheezing Infants

Several biomarkers have been developed to address airway inflammation in bronchial asthma (BA), including exhaled nitric oxide, sputum eosinophils. However it is challenging and sometimes considered to be rather invasive to appropriately obtain those biomarkers in young children. Since urine is a non-invasive and easy-to-obtain samples in children, urinary leukotriene E4 (uLTE4) is one of the most potent biomarkers to address airway inflammation in infants. To ask whether uLTE4 can be used for the diagnosis of BA in young children, we determined concentrations of uLTE4 of wheezing children. A total of 184 patients at an outpatient clinic in Saitama prefecture in Japan for wheezing from February 2012 to August 2013 participated in the study. Urine samples were collected and immediately frozen until use. LTE4 was collected with an anti-LTE4 antibody and the concentrations were determined by ELISA. Urine creatinine (uCr) levels were also determined. Since uCr levels differ among different ages, we first corrected all the uCr values with those at corresponding ages. uLTE4 was then normalized to age-corrected uCr levels. Patients consisted of the first wheezers with or without a family history of BA, the first wheezers with RSV infection, intermittent BA, mild persistent BA and controls with fever but not wheezing. uLTE4 levels of the first wheezers with a family history who responded to inhalation of bronchodilator (n=33) and intermittent BA (n=25) were higher (p<0.01) than those of controls. There were no significant differences between uLTE4 in other groups and controls. These results suggest that uLTE4 can be a marker of allergic airway inflammation in young children. We are currently following clinical courses of those patients to ask whether uLTE4 can be a predictive marker for the development of BA.