Secretory Phospholipase A2 in Patients With Sickle Cell Disease Hospitalized for Vaso-Occlusive Pain Episodes.

BACKGROUND

Secretory phospholipase A2 (sPLA2) is an inflammatory mediator linked to acute chest syndrome (ACS) in sickle cell disease (SCD), a serious complication that can develop during an acute vaso-occlusive pain episode (VOE). Plasma sPLA2 levels have been proposed as a potential biomarker for predicting ACS onset.

OBJECTIVE

To assess serial plasma sPLA2 levels in 105 pediatric patients hospitalized for SCD-VOE and determine the effects of arginine therapy compared to placebo.

PROCEDURES: This is a pharmacokinetics/pharmacodynamics and randomized controlled trial of intravenous arginine therapy. Statistical methods included t-tests, chi-square, and correlation analyses.

RESULTS

Mean age was 12.7 ± 3.7 years, 48% were male, 67% had Hb-SS, and 70% were prescribed hydroxyurea. Using a previously established SCD-specific cutoff of 48 ng/mL, presenting sPLA2 levels were elevated in 33% of patients (mean sPLA2 level 85.7 ± 32.9 ng/mL). SPLA2 elevation in the emergency department was more common in patients with ACS compared to those without ACS (64% vs. 30%; p = 0.02; negative predictive value of 94%). Peak sPLA2 levels were significantly higher in febrile (n = 34) versus afebrile patients (n = 71;101.0 ± 45.3 vs. 48.7 ± 35.4 ng/mL; p < 0.0001). Among subjects with elevated baseline sPLA2, arginine therapy resulted in a significant reduction in sPLA2 levels by discharge compared to placebo (-27.8 ± 38.1 ng/mL; p = 0.002; n = 23 vs. -15.0 ± 41.2 ng/mL; p = 0.23; n = 12).

CONCLUSIONS

SPLA2 is an underutilized biomarker of ACS given accumulating evidence of its role. In particular, low levels may identify patients at low risk for ACS. Arginine therapy may modulate inflammation in patients with SCD during VOE and/or ACS.

TRIAL REGISTRATION: ClinicalTrials.gov identifiers: NCT02447874; NCT02536170.