Maternal and fetal levels of methionine and homocysteine in early human pregnancy

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Interactions between stromal cell--derived keratinocyte growth factor and epithelial transforming growth factor in immune-mediated crypt cell hyperplasia

Immune reactions in the gut are associated with increased epithelial cell proliferation. Here we have studied the role of keratinocyte growth factor (KGF; FGF7) and transforming growth factor-alpha (TGF-alpha) in the epithelial cell hyperplasia seen in explants of fetal human small intestine after activation of lamina propria T cells with the superantigen Staphylococcus aureus enterotoxin B (SEB). After the addition of SEB to the explants there is a 10-fold increase in KGF mRNA by 72 h of culture. KGF transcripts were abundant in the lamina propria using in situ hybridization and the culture supernatants contained elevated amounts of KGF protein. SEB had no direct effect on KGF mRNA and protein production by cultured lamina propria mesenchymal cells, but both were upregulated by TNF-alpha. Accompanying the increase in KGF there was also an increase in TGF-alpha precursor proteins in the culture supernatants and the phosphorylated form of the EGFR receptor was also detected in the tissue. Increased TGF-alpha precursor proteins were also detected in the supernatants of control explants stimulated with KGF alone. The direct addition of KGF and TGF-alpha enhanced epithelial cell proliferation and antibodies against KGF and TGF-alpha partially inhibited SEB-induced crypt hyperplasia. These results suggest molecular cross-talk between the KGF/KGFR and the TGF-alpha/EGFR in immune-mediated crypt cell hyperplasia

A major role for matrix metalloproteinases in T cell injury in the gut

Activated lamina propria T cells responding to luminal Ags are thought to be important in celiac disease and Crohn's disease, and T cells responding to foreign MHC products are also important in intestinal graft-vs-host disease and intestinal transplant rejection. However, the mechanism(s) by which T cells mediate damage in the gut is not known. We have previously shown that activation of lamina propria T cells by PWM in explant cultures of second trimester human small intestine produces severe tissue injury, with epithelial cell shedding and loss of villi. In this study, we have investigated the role of matrix metalloproteinases in this system. Organ culture supernatants of explants stimulated with PWM showed a 3-fold increase in the concentration of interstitial collagenase and a 10-fold increase in stromelysin-1 compared with control explant culture supernatants. Tissue inhibitors of metalloproteinase-1 and -2 concentrations were unchanged. Increased metalloproteinase enzymatic activity was detected by gelatin and casein zymography. Western blotting revealed the active forms of interstitial collagenase and stromelysin-1 in PWM-stimulated culture supernatants. Up-regulation of mRNA for interstitial collagenase, stromelysin-1, and gelatinase-B was also seen. Nanomolar amounts of recombinant stromelysin-1 added directly to explants produced rapid severe tissue injury. PWM-induced mucosal injury was inhibited by a synthetic peptidomimetic inhibitor of matrix metalloproteinases. Mesenchymal cells isolated from the mucosa of human fetal small intestine produced increased amounts of interstitial collagenase, gelatinase A, and stromelysin-1 when stimulated with IL-1beta or TNF-alpha. These results suggest that T cell activation in the lamina propria results in increased production of matrix metalloproteinases, which by degrading the lamina propria matrix represent a major pathway by which T cells cause injury in the gut

Suppression of T cell-mediated injury in human gut by interleukin 10: role of matrix metalloproteinases

BACKGROUND & AIMS: Activation of lamina propria T cells with pokeweed mitogen in human fetal gut explant cultures results in severe mucosal injury. In the same system, Staphylococcus aureus enterotoxin B produces villus atrophy and crypt cell hyperplasia. The aim of this study was to examine the ability of interleukin (IL)-10 to modify these changes. METHODS: Mucosal pathology and lamina propria glycosaminoglycans were assessed histologically, and CD3(+), CD25(+) and alpha-actin smooth muscle-positive cells were determined by immunohistochemistry. Reverse plaque assays and quantitative reverse-transcriptase polymerase chain reaction were used to analyze the cytokine response. Matrix metalloproteinase production was analyzed by Western blotting, in situ hybridization, and zymography. RESULTS: Both experimental enteropathies produced mucosal damage, although injury was greater after pokeweed mitogen activation than S. aureus enterotoxin B. In both cases, the increase in cytokine-secreting cells and transcripts observed after T-cell activation was inhibited by IL-10. IL-10 also inhibited the increase in collagenase and stromelysin-1 in the explant culture supernatants and the loss of glycosaminoglycans. IL-10 decreased metalloproteinase production in control explants and increased matrix. In mesenchymal cells, IL-10 had a minor effect on metalloproteinase production. CONCLUSIONS: IL-10 down-regulates mucosal T-cell activation, metalloproteinase production, and loss of extracellular matrix and prevents mucosal damage in the gut