Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:3.2.1.108 (lactase)
 2,133 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Using metabolic labeling techniques in human intestinal epithelial cell lines in tissue culture and in situ hybridization techniques in normal and inflamed (Crohn's) intestine, recent studies have shown that there is synthesis of acute phase proteins in enterocytes. Moreover, these studies have shown that acute phase protein biosynthesis in enterocytes is regulated by inflammatory cytokines in a manner characteristic of the physiologic acute phase response. In the course of these studies it was noticed that one inflammatory cytokine, interleukin-6 (IL-6), mediated selective down-regulation of the enterocyte-specific, differentiation-dependent integral membrane protein sucrase-isomaltase (SI) in the Caco2 intestinal epithelial cell line. In the current study we examined the effect of several other inflammatory cytokines interleukin-1 (IL-1 beta), tumor necrosis factor alpha (TNF alpha), and interferon gamma (IFN gamma) on synthesis of SI in Caco2 cells, examined the possibility that inflammatory cytokines affect the synthesis of other enterocyte integral membrane proteins using lactase as a prototype, and examined the possibility that SI gene expression was down-regulated in villous enterocytes in vivo during the local inflammatory response of Crohn's disease. The results show that IL-6 and IFN gamma each mediate a decrease and TNF alpha mediates an increase in synthesis of SI in Caco2 cells. The magnitude of down-regulation by IL-6 and IFN gamma is significantly greater than the up-regulation by TNF alpha. IL-1 beta has no effect on synthesis of SI. Synthesis of lactase is not affected by any of the cytokines. There is a marked specific decrease in SI gene expression in villous enterocytes in acutely inflamed Crohn's ileum as compared to adjacent uninflamed ileum and normal ileum. Taken together, these data show that inflammatory cytokines have specific and selective effects on the expression of the brush border hydrolase SI in tissue culture and in vivo and provide evidence for a previously unrecognized mechanism for disaccharidase deficiency in intestinal inflammation.
 ...
PMID:Regulation of sucrase-isomaltase gene expression in human intestinal epithelial cells by inflammatory cytokines. 855 56

In the present investigation, the authors aimed to evaluate the role of cytokines in intestinal postnatal maturation induced by dietary polyamines. Neonatal rats were administered either saline (8 mumol) orally. Spermine increased interleukin-1 beta (IL-1 beta), IL-6, and TNF-alpha plasma concentration. The maximum concentrations of IL-1 beta, IL-6, and TNF-alpha were, respectively, observed at 4, 4, and 8 h posttreatment. Intraperitoneal (i.p.) injection of IL-1 beta increased the specific activity of sucrase in whole small intestine, whereas the specific activities of maltase and lactase were significantly enhanced only in the jejunum. IL-6 elicited sucrase and increased maltase specific activity in the whole small intestine, but lactase specific activity was not affected. TNF-alpha had no effect on sucrase and maltase specific activity, but a slight augmentation of lactase specific activity was detected in the jejunum. Spermine and spermidine content in the intestine was increased by i.p. injection of IL-1 beta and IL-6. Corticosterone secretion was elevated by single i.p. injection of IL-1 beta, IL-6, or TNF-alpha. These findings suggest that spermine could induce postnatal intestinal development and corticosterone secretion through a cytokine-dependent mechanism.
 ...
PMID:Role of interleukin-1 beta, interleukin-6, and TNF-alpha in intestinal maturation induced by dietary spermine in rats. 922 34

Necrotizing enterocolitis (NEC) is a major inflammatory disease of the premature human intestine that can be prevented by glucocorticoids if given prenatally before the 34th wk of gestation. This observation suggests that a finite period of steroid responsiveness exists as has been demonstrated in animal models. Human intestinal xenografts were used to determine whether a glucocorticoid responsive period exists in the developing human intestine. Developmental responsiveness was measured by lactase activity and inflammatory responsiveness by IL-8, IL-6, and monocyte chemotactic protein-1 (MCP-1) induction after an endogenous (IL-1 beta) or exogenous (LPS) proinflammatory stimulus, respectively. Functional development of ileal xenografts were monitored for 30 wk posttransplantation, and the lactase activity recapitulated that predicted by in utero development. Cortisone acetate accelerated the ontogeny of lactase at 20 wk (immature) but the effect was lost by 30 wk (mature) posttransplant. Concomitant with accelerated maturation, the IL-8 response to both IL-1 beta and LPS was significantly dampened (from 6- to 3-fold) by glucocorticoid pretreatment in the immature but not mature xenografts. The induction of IL-8 was reflected at the level of IL-8 mRNA, suggesting transcriptional regulation. The excessive activation of IL-8 in the immature gut was mediated by a prolonged activation of ERK and p38 kinases and nuclear translocation of NF-kappa B due to low levels of I kappa B. Steroid pretreatment in immature intestine dampens activation of all three signaling pathways in response to proinflammatory stimuli. Therefore, accelerating intestinal maturation by glucocorticoids within the responsive period by accelerating functional and inflammatory maturation may provide an effective preventive therapy for NEC.
 ...
PMID:Glucocorticoid responsiveness in developing human intestine: possible role in prevention of necrotizing enterocolitis. 1559 89