O2145: Therapeutic Effects of Orally Administered Chondroitin Sulfate Improves Outcomes of Lung Injury in Necrotizing Enterocolitis Murine Model

Background: Necrotizing enterocolitis (NEC) is a devastating condition of multifactorial etiology that results in a significant systemic inflammatory response—often progressing to requiring intestinal surgical resection. These infants, therefore, are also susceptible to acute lung injury and the development of bronchopulmonary dysplasia with evolving evidence suggesting that there is a causative relationship between the inflammatory signaling pathways that connect the intestine and lung. Chondroitin Sulfate (CS) is a glycosaminoglycan in human breast milk that is often absent in conventional formulas. In a murine model, our lab has shown improvement in intestinal outcomes in NEC with oral CS. We therefore hypothesized that formula supplementation with CS during experimental NEC would also attenuate lung injury via modulation of these signaling pathways.

Methods: NEC was induced in five-day-old mouse pups with gavage formula feeds and intermittent hypoxia and hypothermia in three groups: (1)breast-fed controls, (2)NEC, and (3)NEC+CS (enteral supplementation of 200 mg/kg/d in formula). Animals were euthanized on postnatal day 9. The right lower lobe was stained and assessed for lung injury with two blinded scorers using a previously published scoring system. Terminal ileal segments and the left lung lobe were harvested, and cytokines were measured in tissue homogenates using a multiplex ELISA beaded assay. Kruskal Wallis/ANOVA tests were performed with a p-value < 0.05 considered significant.

Results: The lungs of mice with NEC (3 [1-5]) show significantly worse lung injury compared to breastfed controls (2[1-3])(p=0.0005), with an attenuation of lung injury seen in mice with NEC treated with oral CS(2[1-4]) (p=0.0033) when compared to NEC alone(Figure 1A). A larger ratio of air-space to alveolar area is indicative of poorer terminal bronchiolar differentiation and air-space utilization. Lungs of mice with NEC(1.63 ±0.43) show significantly higher ratios compared to breastfed controls(0.75±0.29)(p < 0.0001), with a lower ratio seen in mice with NEC treated with oral CS(0.87±0.19) (p < 0.0001) when compared to NEC alone(Figure 1B). The lungs and intestines of mice with NEC show a significantly increased T-helper cell-17(Th17) cytokine profile when compared to breast-fed controls as evidenced by elevations in IL-6, TNF-a, and IL-17A, as well as a decrease in IL-10. Administration of oral CS therapy results in an attenuation of IL-6, TNF-a, IL-17A release and an increase in IL-10 and IL-22.

Conclusion: Chondroitin sulfate not only improves intestinal outcomes, but also improves lung injury and terminal bronchiolar differentiation in a murine model of NEC. Oral CS therapy also attenuates the hyper-activation of the Th17 cytokine secretion pathway, which suggests its mechanisms of action. Further research in our lab will clarify the mechanism of immunomodulation of CS as well as the long-term effect of CS therapy in our murine model. However, CS serves as a promising and relatively safe therapy to mitigate the deleterious effects of NEC.