F. Adiliaghdam1, M. Gharedaghi1, S. Yan1,2,3, S. R. Hamarneh1, S. A. Morrison1, L. G. Rahme1,2,3, R. A. Hodin1 1Massachusetts General Hospital,General Surgery,Boston, MA, USA 2Shriners Hospitals For Children,Boston, MA, USA 3Harvard School Of Medicine,Department Of Microbiology And Immunobiology,Boston, MA, USA
Introduction: Burn patients are at increased risk for systemic sepsis and multi-organ failures. Burn-induced gut barrier dysfunction and bacterial translocation is thought to be one of the sources of bacterial presence in the blood stream. Previously, we have shown that IAP detoxifies bacterial pro-inflammatory factors, prevents endotoxemia, enhances gut barrier functions, and preserves intestinal microbial homeostasis. We have hypothesized that supplemental intestinal alkaline phosphatase (IAP) could be used as a therapeutic modality to prevent gut-derived sepsis.
Methods: 6-week old CD-1 mice were divided into 4 groups (n=5 in each group). We inflicted a 30% total body surface area burn on the back of mice +/- intradermal Pseudomonas aeruginosa (PA) infection mid-eschar of burn site to induce gut barrier dysfunction. IAP or vehicle were administered orally by gastric gavage in a dose of 200U per gavage at 3 and 12 hours post infection. The results were compared to a non-burned control group that underwent a sham procedure. The change in intestinal permeability was assessed by measuring FITC-Dextran 20kD presence in the blood stream at 6 hours post gavage. Bacterial burden in the blood and in intestinal samples was assessed. Intestinal inflammation and cytokine levels were also measured using ELISA.
Results:TThe experimental group underwent the burn procedure and infection had significantly higher intestinal permeability to FITC-Dextran compared to burn alone or control group mice. (p = 0.01) Oral IAP supplementation significantly reduced the gut barrier dysfunction seen in the treated group. (FITC-Dextran concentration in blood: 0.255 µg/ml in infected group compared to 0.074 µg/ml in IAP treated group, p = 0.04) Consistently, infected mice showed significantly lower serum endotoxin levels in IAP-treated group (2.69 ± 0.60 EU/ml) compared to infected and no treated group (17.51 ± 6.14 EU/ml, p = 0.003). IAP treatment reduced the bacterial load in the blood of burn and infected mice (6.3 x 105 CFU/ml of blood in infected group compared to 4.2 x 103 CFU/ml in IAP treated infected mice) and in the ileal tissue (1.4 x 106 CFU/g of ileal tissue in infection group compared to vs 2.8 x 104 CFU/g in IAP group, p = 0.049). Lastly, the burn procedure combined with infection resulted in significant levels of intestinal inflammation, as evidenced by elevated levels of TNF-a in the intestinal tissue. IAP treatment reduced TNF-a level.
Conclusion:IAP is a major regulator of the gut mucosal barrier and is able to ameliorate burn-induced gut barrier dysfunction. It appears that IAP functions through preventing intestinal inflammation. Oral IAP supplementation may represent a novel approach to prevent sepsis in burn patients.