The studies outlined in this proposal will focus on the role of transforming growth factor-beta (TGF-beta) in the mechanisms which govern the immune functions of intestinal epithelial cells as related to an inflammatory response at the intestinal mucosa. As a model system, we will use the nontransformed rat intestinal epithelial cell line, IEC-6. We have previously found that TGF-beta could enhance secretory component (SC) and class I major histocompatibility antigen (MHC) expression on IEC-6 cells. TGF-beta was also found to enhance the secretion of the inflammatory cytokine interleukin-6 (IL-6) by IEC-6 cells, as were IL-1alpha, IL-1beta, and TNF-alpha (all inflammatory cytokines themselves) able to induce IL-6 secretion by these cells. Co-stimulation of the IEC-6 cells with TGF-beta and either IL-1 or TNF-alpha resulted in a synergistic enhancement of IL-6 secretion by the IEC-6 cells to levels much greater than that of both cytokines combined. Preliminary results indicate that TGF-beta induced the IEC-6 cells to become more sensitive to IL-1 stimulation, an effect which was partially due to an enhanced expression of IL-1 receptors induced by TGF-beta. However, high levels of both TGF-beta and IL-1beta tended to lower the synergistic effect on IL-6 responses by the IEC-8 cells. In this proposal, we will (10 investigate the effect of TGF-beta on the expression of mRNA for SC as well as the effect of other cytokines in combination with TGF-beta. (2) The regulation of IL-6 secretion by TGF-beta with or without other inflammatory cytokines will be determined using a cytokine specific bioassay, RNA and protein synthesis inhibitors, and mRNA analysis to monitor the induction of and secretion of IL-6. (3) The effect of TGF-beta on the expression of receptors for the inflammatory cytokines will be explored in order to yield insight as to a possible mechanism whereby TGF- beta could enhance the effectiveness of these cytokines to induce IL-6 secretion. (4) The mechanism by which high levels of TGF-beta limit the synergistic effect of TGF-beta and IL-1beta on IL-6 secretion will be studied to determine if IL-6 mRNA or protein synthesis and IL-1 receptor expression are altered by high levels of these cytokines. (5) The effect of TGF-beta on the secretion of other inflammatory cytokines such as IL-1 and TNF-alpha will be assessed by specific assays and mRNA analysis. Finally, (6) the effect of TGF-beta on IL-6 secretion (and possibly the secretion of other cytokines) by IEC-6 cells induced with bacterial lipopolysaccharide will be studied as a model of the response of IEC to bacterial agents. The proposed study should lend valuable insight as to the role of TGF-beta and the intestinal epithelial cell in mucosal inflammatory responses such as those seen with mucosal infections and inflammatory bowel disease.

Agency
National Institute of Health (NIH)
Institute
National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK)
Type
First Independent Research Support & Transition (FIRST) Awards (R29)
Project #
5R29DK044617-04
Application #
2143925
Study Section
General Medicine A Subcommittee 2 (GMA)
Project Start
1992-09-30
Project End
1997-09-29
Budget Start
1994-09-30
Budget End
1995-09-29
Support Year
4
Fiscal Year
1994
Total Cost
Indirect Cost
Name
State University of NY, Binghamton
Department
Biology
Type
Schools of Arts and Sciences
DUNS #
090189965
City
Binghamton
State
NY
Country
United States
Zip Code
13902
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Goodrich, M E; McGee, D W (1999) Preferential enhancement of B cell IgA secretion by intestinal epithelial cell-derived cytokines and interleukin-2. Immunol Invest 28:67-75
Vitkus, S J; Hanifin, S A; McGee, D W (1998) Factors affecting Caco-2 intestinal epithelial cell interleukin-6 secretion. In Vitro Cell Dev Biol Anim 34:660-4
Jiang, Y; McGee, D W (1998) Regulation of human lymphocyte IL-4 secretion by intestinal epithelial cell-derived interleukin-7 and transforming growth factor-beta. Clin Immunol Immunopathol 88:287-96
Goodrich, M E; McGee, D W (1998) Regulation of mucosal B cell immunoglobulin secretion by intestinal epithelial cell-derived cytokines. Cytokine 10:948-55
McGee, D W; Vitkus, S J (1996) IL-4 enhances IEC-6 intestinal epithelial cell proliferation yet has no effect on IL-6 secretion. Clin Exp Immunol 105:274-7
Mascarenhas, J O; Goodrich, M E; Eichelberger, H et al. (1996) Polarized secretion of IL-6 by IEC-6 intestinal epithelial cells: differential effects of IL-1 beta and TNF-alpha. Immunol Invest 25:333-40
McGee, D W; Vitkus, S J; Lee, P (1996) The effect of cytokine stimulation on IL-1 receptor mRNA expression by intestinal epithelial cells. Cell Immunol 168:276-80
McGee, D W; Bamberg, T; Vitkus, S J et al. (1995) A synergistic relationship between TNF-alpha, IL-1 beta, and TGF-beta 1 on IL-6 secretion by the IEC-6 intestinal epithelial cell line. Immunology 86:6-11
McGee, D W; Elson, C O; McGhee, J R (1993) Enhancing effect of cholera toxin on interleukin-6 secretion by IEC-6 intestinal epithelial cells: mode of action and augmenting effect of inflammatory cytokines. Infect Immun 61:4637-44