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Inflammatory gene expression by human colonic smooth muscle cells
Sonemany Salinthone1, Cherie A Singer, William T Gerthoffer
1Department of Pharmacology, University of Nevada School of Medicine, Reno, Nevada 89557-0270, USA.
Summary
Human colonic smooth muscle cells synthesize inflammatory mediators like interleukins and chemokines. Their production is regulated by signaling pathways, with p38 MAPK playing a key role.
Area of Science:
- Gastroenterology
- Immunology
- Cell Biology
Background:
- Cytokines and chemokines are key mediators in human colitis, primarily produced by mucosal cells and leukocytes.
- Smooth muscle cells in airways and vasculature also synthesize these inflammatory mediators.
- The potential for colonic smooth muscle cells to produce such mediators remains largely unexplored.
Purpose of the Study:
- To investigate whether human colonic myocytes can synthesize proinflammatory mediators.
- To identify the signaling pathways involved in the regulation of inflammatory gene expression in colonic smooth muscle cells.
Main Methods:
- Isolation of circular smooth muscle strips and cells from human colon.
- Stimulation of myocytes and muscle strips with pro-inflammatory cytokines (IL-1beta, TNF-alpha, IFN-gamma).
- Analysis of mRNA expression for various cytokines, chemokines, and COX-2 using quantitative methods, and assessment of inhibitor effects (MG-132, PP1, SB-203580, PD-98059).
Main Results:
- Human colonic smooth muscle cells demonstrated induced mRNA expression for IL-1beta, IL-6, IL-8, and COX-2 within 2-12 hours post-stimulation.
- RANTES mRNA expression was observed later, appearing at 8 hours and increasing over 20 hours.
- Inhibitors targeting NF-kappaB (MG-132), Src-family kinases (PP1), and p38 MAPK (SB-203580) significantly reduced inflammatory gene expression, while a MAPK/ERK inhibitor (PD-98059) was less effective.
Conclusions:
- Human colonic smooth muscle cells possess the capacity to synthesize and secrete key inflammatory mediators, including interleukins (IL-1beta, IL-6) and chemokines (IL-8, RANTES), and upregulate COX-2 expression.
- The synthesis of these mediators is regulated by multiple signaling pathways, notably NF-kappaB, Src-family kinases, and p38 MAPKs.
- The p38 MAPK pathway appears particularly crucial, as evidenced by the efficacy of SB-203580 in inhibiting inflammatory gene expression in colonic smooth muscle.