332 Association of sphingolipid de novo synthesis with airway response to magnesium

Abstract

OBJECTIVES/GOALS: MgSO4 is a frequently used to treat asthma exacerbations. Its role in the management of pediatric asthma remains controversial. Our objective is to demonstrate that the response of the small (peripheral) airways depends on airway de novo sphingolipid synthesis, clinically and experimentally. The small airways are the main site of asthma pathology. METHODS/STUDY POPULATION: We investigated airway reactivity in response to MgSO4 in murine small airways and children 1. Precision-cut lung slices (PCLS): Using heterozygous knockouts mice of one of the Sptlc2 subunit of the serine palmitoyl-CoA transferase (SPT) which results in reduced tissue sphingolipid levels compared to wild-type control littermates (Sptlc2+/+). We compared small airway dilation to MgSO4 in Sptlc2+/- and Sptlc2+/+ mice. This was assessed by directly visualization of small airway contractility in PCLS from Sptlc2+/- mice using video phase-contrast microscopy 2. Clinical response to MgSO4 in children by using a respiratory score before and after the treatment. The response to MgSO4 was the correlated to asthma-associated 17q21 specific single nucleotide polymorphisms (SNPs) from DNA isolated from buccal swabs RESULTS/ANTICIPATED RESULTS: Sphingolipid-mediated activity alters magnesium response in small airways. We assessed whether downregulation of SPT could lead to alterations in MgSO4-induced small airway dilation and in MgSO4 responsiveness in mouse tracheal rings and found that the magnesium-induced relaxation of airways pre-contracted with methacholine was impaired in Sptlc+/- mice compared to the control group (p=<0.05) Clinical response to MgSO4 in children with status asthmaticus. A respiratory score was assessed in a cohort of 5 to 21-year-old who received IV MgSO4. An increase of 3 or more points was considered positive. Only 32% of the patients showed a favorable improvement to the medication, showing variability of response between individuals. The correlation of sphingolipid-deficient SNPs and MgSO4 responsiveness is ongoing DISCUSSION/SIGNIFICANCE: This suggest that decreased SPT activity in the respiratory track alters the response of the airways to magnesium. Connecting decreased de novo SL synthesis to alterations in cellular magnesium homeostasis provides a mechanistic link to differential airway reactivity to MgSO4 in pediatric asthma management.