Effect of secondhand cigarette smoke, RSV bronchiolitis and parental asthma on urinary cysteinyl LTE4

Cysteinyl leukotrienes promote airway inflammation, bronchoconstriction and mucus hypersecretion. Cigarette smoking and respiratory syncytial virus (RSV) bronchiolitis are known to increase urinary cysteinyl leukotriene E4 (uLTE4), the end product of the cysteinyl leukotriene biosynthetic pathway. We tested the following hypotheses: (1) Secondhand smoke (SHS) exposure increases uLTE4 in well infants and in those hospitalized for RSV bronchiolitis; (2) Length of hospital stay for those with RSV bronchiolitis correlates with uLTE4; and (3) Infants with parent(s) with asthma will have higher uLTE4. Parental asthma for infants hospitalized with RSV bronchiolitis (n = 79) and Well babies (n = 31) was determined by questionnaire. Urine was analyzed for LTE4, cotinine, and creatinine. SHS exposure was determined by cotinine to creatinine ratio. Chi square, or t-tests were used to determine significant differences between two groups. A three-way analysis of variance compared the effects of SHS exposure and parental asthma on uLTE4 in Well versus RSV babies. Independent variables predicting length of hospital stay were determined by stepwise multiple regression. High SHS exposure and RSV significantly increased uLTE4. The SHS induced increase in uLTE4 was seen in infants with no parental asthma but not in those with parental asthma. Length of hospital stay positively correlated with uLTE4. We concluded that SHS exposure may increase the severity of bronchiolitis in RSV-infected infants by enhancing production of cysLTs in infants with no parental asthma. Pediatr Pulmonol. 2008; 43:760–766. © 2008 Wiley-Liss, Inc.