Analysis of epidermal growth factor signaling in nasal mucosa epithelial cell proliferation involved in chronic rhinosinusitis

Background Aberrant epithelial repair has been observed in chronic rhinosinusitis （CRS） patients; however, the mechanism of epithelial cell repair regulation is unclear. Epidermal growth factor （EGF） plays an important role in regulating epithelial cell repair in lower airway and may be a critical factor in the remodeling processes of CRS. The objective of our research is to evaluate the differences between CRS and normal subjects and between chronic rhinosinusitis without nasal poiys （CRSsNP） and chronic rhinosinusitis with nasal polys （CRSwNP） in the regulation of EGF pathways and the regulating proliferative position of classic Ras/Raf/MEK/ERK pathways. Methods We evaluated the proliferation rates of ethmoidal mucosal cells before and after stimulation with EGF, epidermal growth factor receptor （EGFR） kinase inhibitor AG1478, and extracellular signal-regulated kinase 1/2 （ERKI/2）inhibitor PD98059 using MTT assays. We also analyzed the sinonasal epithelial cells collected from control subjects and patients with CRS subtypes CRSsNP and CRSwNP for the expression of ERK1/2, phosphorylated ERK1/2, P21, P15, and P27 using western blotting analyses. Results The proliferation rates of sinonasal epithelial cells before and after EGF stimulation were lower in CRS patients than in the controls. AG1478 or PD98059 inhibitor treatment of control epithelial cells did not result in a significant difference in proliferation. Although, AG1478 and PD98059,inhibited the proliferation of CRS cells, the degree of proliferation inhibition was markedly different in CRSsNP. AG1478 suppressed the proliferation of CRSwNP epithelial cells, whereas PD98059 had no effect. The ratio of ERK1/2 phosphorylation in CRS cells was lower than that of the control cells. Cyclin-dependent kinase inhibitors were highly expressed in CRS cells compared with that of control cells. ERK1/2 and P27 showed differential expression in CRSsNP and CRSwNP. Conclusions Differences existed in EGF pathways in CRS patients and normal subjects as well as in CRSsNP and CRSwNP. Classical Ras/Raf/MEK/ERK pathway may assume absolute superiority in control cells. Ras/Raf/MEK/ERK classical pathway and other pathways might be active at the same time to stimulate epithelial cell proliferation in CRSsNP. The function of Ras/Raf/MEK/ERK classical pathway was weaker in CRSwNP than in CRSsNP and when the classical pathway was blocked in CRSwNP, some other pathway could have completely compensated the proliferation induced by the Ras/Raf/MEK/ERK pathway.

Association of Down-regulation of CD109 Expression with Up-expression of Smad7 in Pathogenesis of Psoriasis

Transforming growth factor（TGF）-β signaling plays an important role in the pathogenesis of psoriasis. CD109, a novel TGF-β co-receptor, which inhibits TGF-β signaling by enhancing Smad7-dependent degradation of TGF-β type Ⅰ receptor（TGF-β RⅠ）, is abnormally expressed in psoriasis. To date, the expression of Smad7 and the correlation between CD109 and Smad7 expression in psoriasis have not been fully elucidated. This study was designed to investigate the expression and the correlation of CD109 and TGF-β signaling associated proteins in psoriasis and their roles in the pathogenesis of psoriasis. Thirty-two psoriasis specimens were subjected to immunohistochemical staining for CD109, Smad7, TGF-β RⅠ and Ki67. Ten normal skin（NS） specimens served as controls. The positive expression rate（% positive cells） of Smad7 and Ki67 in psoriasis was significantly higher than in NS（62.6%±19.9% vs. 17.2%±4.4%, and 50.7%±14.3% vs. 19.5%±3.2%, respectively, P〈0.001）, and the expression levels of CD109 and TGF-β RⅠ were reduced significantly in psoriasis as compared with NS（8.1%±6.7% vs. 35.8%±6.7% and 27.3%±3.4% vs. 3.0%±3.4%, respectively, P〈0.001）. There were significantly negative correlations between CD109 and Smad7（r=-0.831, P〈0.01）. These findings indicated that CD109 might play a certain role in the pathogenesis of psoriasis. Lower expression of CD109 and TGF-β RⅠ was highly correlated with higher expression of Smad7 and Ki67, suggesting that CD109 may induce the pathogenesis of psoriasis through Smad7-mediated degradation of TGF-β RⅠ, and lead to the termination of TGF-β signaling.