Objectives:Levels of stool fatty acid soaps and beneficial bacteria differ between formula-fed and breast-fed infants; addition of specific formula ingredients may reduce these differences. This study evaluated the effects of a term infant formula containing high sn-2 palmitate term infant formula (sn-2) or an identical formula supplemented with oligofructose (OF) at 2 concentrations (sn-2+3 g/L OF, sn-2+5 g/L OF) on stool composition, stool characteristics, and fecal bifidobacteria.Methods:Healthy, term formula-fed infants 7 to 14 days old (n = 300) were randomized in a double-blind manner to receive standard formula (control), sn-2, sn-2+3 g/L OF, or sn-2+5 g/L OF for 8 weeks. Human milk (HM)–fed infants (n = 75) were studied in parallel. Stool samples were collected from all subjects at week 8 for fatty acid soaps and mineral content, and from a subset at baseline and week 8 for bifidobacteria. Stool characteristics were assessed via 3-day diary.Results:The sn-2 group had 46% less stool soap palmitate (P < 0.001) and softer stools than control (20% more mushy soft stools, P = 0.026; 50% fewer formed stools, P = 0.003). Addition of OF resulted in even fewer formed stools versus control (65% fewer for sn-2+3 g/L OF, 79% fewer for sn-2+5 g/L OF), with 5 g/L OF more closely resembling that of HM-fed infants. Both sn-2 (P < 0.05) and sn-2 with OF groups (P < 0.01) had significantly higher fecal bifidobacteria concentrations than control at week 8, not differing from HM-fed infants.Conclusions:High sn-2-palmitate formulas led to reduced stool soaps, softer stools, and increased bifidobacteria, whereas addition of OF further improved stool consistency. Those modifications brought outcomes in formula-fed infants closer to that in HM-fed infants.
Increased nitric oxide (NO) production by inducible nitric oxide synthase (iNOS) has been associated with intestinal inflammation, including human inflammatory bowel disease. However, NO can downregulate endothelial activation and leukocyte adhesion, critical steps in the inflammatory response. Using primary cultures of human intestinal microvascular endothelial cells (HIMEC), we determined the role of NO in the regulation of HIMEC activation and interaction with leukocytes. Both nonselective ( N G-monomethyl-l-arginine) and specific ( N-iminoethyl-l-lysine) competitive inhibitors of iNOS significantly increased binding of leukocytes by HIMEC activated with cytokines and lipopolysaccharide. Increased adhesion was reversible with the NOS substratel-arginine and was not observed in human umbilical vein endothelial cells (HUVEC). Activation of HIMEC significantly upregulated HIMEC iNOS expression and NO production. NOS inhibitors did not augment cell adhesion molecule levels in activated HIMEC but did result in sustained increases in intracellular reactive oxygen species. In addition, antioxidant compounds reversed the effect of NOS inhibitors on HIMEC-leukocyte interaction. Taken together, these data suggest that after HIMEC activation, iNOS-derived NO is an endogenous antioxidant, downregulating leukocyte binding and potentially downregulating intestinal inflammation.
Helicobacter pylori infection causes a Th1-driven mucosal immune response. Cyclooxygenase (COX)-2 is up-regulated in lamina propria mononuclear cells in H. pylori gastritis. Because COX-2 can modulate Th1/Th2 balance, we determined whether H. pylori activates COX-2 in human PBMCs, and the effect on cytokine and proliferative responses. There was significant up-regulation of COX-2 mRNA and PGE2 release in response to H. pylori preparations. Addition of COX-2 inhibitors or an anti-PGE2 Ab resulted in a marked increase in H. pylori-stimulated IL-12 and IFN-γ production, and a decrease in IL-10 levels. Addition of PGE2 or cAMP, the second messenger activated by PGE2, had the opposite effect. Similarly, stimulated cell proliferation was increased by COX-2 inhibitors or anti-PGE2 Ab, and was decreased by PGE2. Our findings indicate that COX-2 has an immunosuppressive role in H. pylori gastritis, which may protect the mucosa from severe injury, but may also contribute to the persistence of the infection.
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