Intestinal alkaline phosphatase deficiency leads to dysbiosis and bacterial translocation in the newborn intestine

BACKGROUND:Intestinal alkaline phosphatase (IAP) has been shown to help maintain intestinal homeostasis. Decreased expression of IAP has been linked with pediatric intestinal diseases associated with bacterial overgrowth and subsequent inflammation. We hypothesize that the absence of IAP leads to dysbiosis, with increased inflammation and permeability of the newborn intestine. METHODS:Sprague-Dawley heterozygote IAP cross-matches were bred. Pups were dam fed ad lib and euthanized at weaning. The microbiotas of terminal ileum (TI) and colon was determined by quantitative real-time polymerase chain reaction (qRT-PCR) of subphylum-specific bacterial 16S ribosomal RNA. RT-PCR was performed on TI for inflammatory cytokines. Intestinal permeability was quantified by fluorescein isothiocyanate-dextran permeability and bacterial translocation by qRT-PCR for bacterial 16S ribosomal RNA in mesenteric lymph nodes. Statistical analysis was done by chi-square analysis. RESULTS:All three genotypes had similar concentrations of bacteria in the TI and colon. However, IAP knockout (IAP-KO) had significantly decreased diversity of bacterial species in their colonic stool compared with heterozygous and wild-type (WT). IAP-KO pups had a nonstatistically significant 3.9-fold increased inducible nitric oxide synthase messenger RNA expression compared with WT (IAP-KO, 3.92 ± 1.36; WT, 1.0 ± 0.27; P = 0.03). IAP-KO also had significantly increased bacterial translocation to mesenteric lymph nodes occurred in IAP-KO (IAP-KO, 7625 RFU/g ± 3469; WT, 4957 RFU/g ± 1552; P = 0.04). Furthermore, IAP-KO had increased permeability (IAP-KO, 0.297 mg/mL ± 0.2; WT, 0.189 mg/mL ± 0.15 P = 0.07), but was not statistically significant. CONCLUSIONS:Deficiency of IAP in the newborn intestine is associated with dysbiosis and increased inflammation, permeability, and bacterial translocation.