Increased duodenal expression of transforming growth factor-alpha and epidermal growth factor during experimental colitis in rats

Epidermal growth factor improved alcohol-induced inflammation in rats

The purpose of this study was to investigate the effects of an epidermal growth factor (EGF) intervention on improving the inflammatory response of rats fed an ethanol-containing diet. Eight-week-old male Wistar rats were divided into ethanol (E) and control (C) groups. Rats in the E group were fed an ethanol liquid diet, while rats in the C group were pair-fed an isoenergetic diet without ethanol. After a 4-week ethanol-induction period, both the C and E group were respectively subdivided into 2 groups: a normal liquid diet without (C group, n = 8) or with EGF supplementation (C + EGF, n = 8), and the ethanol-containing diet without (E group, n = 8) or with EGF supplementation (E + EGF group, n = 8). The EGF (30 μg/kg body weight/day) intervention period was carried out for the following 8 weeks. At the end of the experiment, activity of aspartate transaminase (AST) and alanine transaminase (ALT) and hepatic levels of tumor necrosis factor (TNF)-α, interleukin (IL)-1β, IL-6, and IL-10 in group E were significantly higher than those in group C. In addition, alterations in the gut microbiota profile were found in group E. In contrast, activity of AST and ALT and levels of TNF-α, IL-1β, and IL-6 in group E + EGF were significantly lower than those in group E. Significantly lower intestinal permeability and lower numbers of Escherichia coli in the fecal microbial culture were also found in group E + EGF. These results suggest that EGF improved the intestinal integrity by decreasing E. coli colonization and lowering intestinal permeability, which then ameliorated the inflammatory response under chronic ethanol exposure.

Downregulation of serum epidermal growth factor in patients with inflammatory bowel disease. Is there a link with mucosal damage?

BACKGROUND

Epidermal growth factor (EGF) is a multipotent peptide which contributes to epithelial development, inhibition of gastric acid secretion, acceleration of wound healing, and promotion of angiogenesis. The aim of this study is to evaluate serum EGF concentrations in inflammatory bowel disease (IBD) patients, with regard to disease and patients' characteristics.

METHODS

EGF determination was performed by a commercially available enzyme-linked immunosorbent assay. Fifty-two patients with ulcerative colitis (UC), 59 with Crohn's disease (CD), and 55 healthy controls (HC) were included in the study.

RESULTS

Mean ( ± SEM) serum EGF levels were 217.2 ( ± 30.40) pg/mL in UC patients, 324.6 ( ± 37.29) pg/mL in CD patients, and 453.1 ( ± 39.44) pg/mL in HC. Serum EGF levels were significantly lower in UC and CD patients compared to HC (P < 0.0001 and P = 0.0199, respectively). Lower serum EGF levels were observed in UC compared to CD patients (P = 0.0277). Extent of the disease was found to affect serum EGF levels in UC, demonstrating significant reduction in patients with left-sided colitis and pancolitis in comparison with those with proctitis (P = 0.0190 and P = 0.0024, respectively). EGF concentration was not influenced by other characteristics of patients and disease.

CONCLUSIONS

Significantly, lower levels of serum EGF are observed in IBD patients compared to HC, while disease extent plays a key role in regulation of serum EGF in UC. Downregulation of serum EGF may be correlated with different patterns of bowel inflammation, epithelial development, and wound healing in IBD.

Carbachol induces TGF-alpha expression and colonic epithelial cell proliferation in sensory-desensitised rats

OBJECTIVE/BACKGROUND

Signals for the expression of the peptide growth factors epidermal growth factor and transforming growth factor-alpha (TGFalpha) in the gastrointestinal mucosa are largely unknown. We have shown earlier that extrinsic afferents in the gastrointestinal tract induce TGFalpha expression in colonic mucosa via the deliberation of neurotransmitters substance P and calcitonin gene-related peptide. The aim of our present study was to determine the effects of carbachol on mucosal TGFalpha expression and epithelial cell proliferation in vivo.

DESIGN/METHODS

Rats were divided in three groups. Group 1 was treated with vehicle only, group 2 received one single subcutaneous injection of 250 microg/kg of carbachol and animals in group 3 were sensory-desensitised prior to the injection of 250 microg/kg carbachol. TGFalpha expression and epithelial cell proliferation was evaluated by polymerase chain reaction, Western blot analysis and bromodeoxyuridine staining.

RESULTS

Carbachol induced a significant increase in mucosal epithelial cell proliferation and TGFalpha expression. Sensory desensitisation did neither abolish the increased TGFalpha expression nor the increase in epithelial cell proliferation.

CONCLUSION

Parasympathetic pathways are involved in the control of TGFalpha expression in gastrointestinal mucosa as well as in epithelial cell proliferation.

Potential for functional redundancy in EGF and TGFalpha signaling in desmoid cells: a cDNA microarray analysis

Genes that replace or duplicate the function of other genes are considered functionally redundant. In this cDNA microarray study, using an Agilent microarray platform and GeneSifter analysis software, we evaluated (1) the degree of downstream transcriptional redundancy and (2) the level of genetic uniqueness apparent in desmoid tumor cells stimulated in vitro for 3 h or for 24 h with 100 ng/ml of exogenous recombinant human EGF (rhEGF) or with recombinant human transforming growth factor alpha (rhTGFalpha). Our intent was to identify genes costimulated, or genes unique to, desmoid cells stimulated in vitro with rhEGF and rhTGFalpha. This experimental approach demonstrated a 55% transcriptional redundancy in the number of desmoid genes significantly upregulated or downregulated following 3 h of stimulation with rhEGF or with rhTGFalpha, and a 65% transcriptional redundancy following 24 h of growth factor stimulation. Approximately 150 genes costimulated by rhEGF and rhTGFalpha were identified. This study suggests that EGF and TGFalpha retain some level of functional redundancy, possibly resulting from their divergence from a common ancestral gene.