Developmental susceptibility to intestinal injury by platelet-activating factor in the newborn rat

Effect of platelet activating factor on function of intestinal immunological barrier in young rats

AIM: To investigate the effect of platelet activating factor (PAF) on the content of secretory IgA (SIgA) in intestinal mucosa.

METHODS: The rats were intraperitoneally injected with different concentrations of PAF (50 and 65 µg/kg) at a dose of 1 µL/g. Double antibody-PEG radioimmunoassay was used to determine the amount of SIgA in the intestinal mucosa. The histological changes were detected by hematoxylin and Eosin staining under light microscope.

RESULTS: In the PAF65 group, the histological examination showed edema of the villus, capillary congestion of the lamina propria, extension of the subepithelial lymphatic channel, polymorphonuclear infiltration in enteric cavity, and shedding of the epithelial layer at 0.5, 1.5, and 3 h. Edema of the villus were still shown at 6 and 24 h. In the PAF50 group, edema of the villus, capillary congestion of the lamina propria were showed at 0.5 and 1.5 h. Edema of the villus were still shown at 3, 6 and 24 h. The content of SIgA was obviously decreased in the experimental group than that in the control group (0.31±0.03 mg/L, 0.40±0.10 mg/L, P < 0.01; 0.43±0.13 mg/L, 0.46±0.11mg/L, P < 0.05, in PAF50 group; 0.28±0.07 mg/L, 0.36±0.08 mg/L, P < 0.01, 0.40±0.11 mg/L, 0.42±0.06 mg/L, P < 0.05, in PAF65 group vs 0.66±0.10 mg/L in the control) at 0.5, 1.5, 3 and 6 h, respectively. The SIgA content decreased most at 0.5 h, but then gradually increased.

CONCLUSION: PAF can lead to damages of the intestinal immunologic barrier by decreasing the SIgA content.

Necrotizing enterocolitis in infants with very low birth weight

Necrotizing enterocolitis (NEC) is a disease in which the primary risk factor is prematurity. Despite, and partially as a result of, the tremendous strides neonatal care has taken, it is a major cause of morbidity and mortality of the newborn. The infant with very low birth weight is particularly susceptible, and the management of the condition in this group differs somewhat from other neonates. The outcomes continue to improve, but there are significant sequelae. Prevention, which would be the best "cure," is elusive, in no small part because of the multifactorial nature of the etiology of NEC.

Carboxyl ester lipase activity in milk prevents fat-derived intestinal injury in neonatal mice

Carboxyl ester lipase (bile salt-stimulated lipase) is a pancreatic enzyme capable of hydrolyzing esters of cholesterol and fat-soluble vitamins. It also efficiently digests triglycerides (TG) into free fatty acids and glycerol and is abundant in the milk of humans and several other species. We used the mouse as a model to test the hypothesis that milk-derived carboxyl ester lipase (CEL) digests milk TG and that without its activity milk lipids and their digestion intermediates can disrupt the intestinal epithelium of neonates. CEL protein and enzymatic activity were shown to be abundant in mouse milk. After 24-h administration of the CEL-specific inhibitor, WAY-121,751-5, the small intestines of treated and control neonates were analyzed histologically for signs of fat malabsorption and injury to their villus epithelium. In vehicle-fed controls, TG were digested and absorbed in the duodenum and jejunum, whereas, in inhibitor-fed littermates, large intracellular neutral lipid droplets accumulated in enterocytes of the ileum, resulting in damage to the villus epithelium. Similar results were observed in neonates nursed by CEL knockout females compared with heterozygous controls. The results suggest that lack of CEL activity causes incomplete digestion of milk fat and lipid accumulation by enterocytes in the ileum of neonatal mice.