J. K. Olson1, C. J. McCulloh1, J. B. Navarro1, L. Mashburn-Warren1, S. M. Gartner1, S. D. Goodman1, G. E. Besner1 1Nationwide Children’s Hospital,Columbus, OH, USA
Introduction: Probiotic administration for the prevention of necrotizing enterocolitis (NEC) traditionally utilizes planktonic, free-living bacteria and requires repetitive administration for efficacy. We have previously shown that a single-dose probiotic treatment in which Lactobacillus reuteri (Lr) is grown as a biofilm on the surface of biocompatible semi-permeable dextranomer microspheres (DM) prior to administration demonstrates efficacy against NEC, and that loading the lumen of DM with prebiotics such as sucrose (DM-Sucrose) further enhances intestinal protection. In vitro work has shown that sucrose is an inducer of GtfW, an enzyme key to biofilm production, and that maltose is the sole substrate of GtfW. Given that breakdown of the intestinal mucosal barrier is a central component of NEC, we sought to evaluate intestinal mucosal permeability in an experimental model of NEC following administration of this novel probiotic delivery system.
Methods: A neonatal rat model of experimental NEC was employed. Rat pups were delivered via C-section then given a single enteral probiotic/prebiotic treatment. Treatment groups were as follows: (1) sterile water (vehicle control); (2) planktonic Lr; (3) Lr + DM-Sucrose; (4) Lr + DM-Maltose; or (5) unstressed breast fed pups. Pups were then subjected to repeated episodes of stress (hypercaloric feeds and periods of hypoxia/hypothermia). An enteral dose of fluorescein isothiocyanate (FITC)-labeled dextran was administered 48h after birth, pups were sacrificed 4h later, and serum FITC-dextran levels were determined.
Results: Serum FITC-dextran levels in pups exposed to NEC that received sterile water alone were significantly elevated compared to breast fed unstressed pups (32.0 ± 6.5 vs. 2.22 ± 0.3 µg/mL; p=0.003) (Figure 1), indicative of gut barrier breakdown. Serum FITC-dextran levels were statistically unchanged in pups that received a single dose of planktonic Lr (17.3 ± 5.0 µg/mL, p=0.08). However, levels were significantly reduced in pups that received a single dose of either Lr + DM-Sucrose (10.8 ± 1.2 µg/mL, p=0.004) or Lr + DM-Maltose (9.0 ± 3.2 µg/mL, p=0.007). There was no difference in efficacy between Lr + DM-Sucrose and Lr + DM-Maltose (p=0.569).
Conclusion: Intestinal mucosal barrier function is preserved during experimental NEC by the administration of a single dose of Lr coupled with sucrose- or maltose-loaded microspheres to optimize biofilm production. Improved gut barrier function is likely a key element in the enhanced protection against NEC seen with this novel treatment. These results further support the benefits of this novel probiotic delivery system for the clinical prevention of NEC in the future.
