Objective To investigate the role of overexpression of Smad7,the inhibitory factor of TGF-?/Smads signaling,in epithelial-mesenchymal transition (EMT) of peritoneal mesothelial cells.Methods Peritoneal fibrosis rat model was built by daily intraperitoneal injection with 4.25% Dineal (100 ml/kg) and lipopolysaccharide(LPS) (0.6 mg/kg) at day 8,10,12,22,24,26. Smad7 or control empty vectors was transferred at day 0,14 and was induced by doxycline in the daily drinking water (200 mg/L).Rats were sacrificed on day 28 and the expression of TGF-beta/ Smads,?-SMA and E-cadherin was examined.Results Compared with normal rats,empty vector rats showed higher expression of phosphorylated Smad2/3.?-SMA expression was elevated but E-cadherin was reduced.Under electron microscope,the mesothelial cells removed to submesothelial zone and showed large bundles of actin microfilaments and dense bodies within the cytoplasm. Basement membrane was broken.After induction of Smad7 in peritoneal fibrosis rats,the morphology of mesothelial ceils normalized partly,phosphorylated Smad2/3 was reduced.Moreover,expression of E-cadherin was increased,expression of?-SMA was dramatically reduced.Conclusion Inhibition of TGF-?/Smad signaling by Smad7 overexpression may inhibit the epithelial-mesenchymal transition of mesothelial cell,which may provide a new therapeutic method for peritoneal fibrosis by overexpression of Smad7.

AIM: To investigate the effects of antitumor drug paclitaxel(PTX)on the proliferation, apoptosis, cell cycle, cell morphology, and related protein expression of Müller cells, and to evaluate its potential toxicity to the retina.METHODS:Müller cells were cultured in vitro and divided into two groups: control group(normal medium)and PTX group. Retinal Müller cells were treated with different concentrations of PTX(0.005, 0.05, 0.5 and 5mg/L)for varying durations(12, 24, 36, 48 and 72h). The CCK8 method was used to assess the effects of different concentrations of PTX and treatment duration on the proliferation Müller cells. Flow cytometry was employed to investigate the impact of different concentrations of PTX on Müller cells apoptosis and cell cycle arrest. Immunofluorescence was used to observe morphological changes in Müller cells. The effects of PTX on the expression of apoptosis-related proteins and aquaporins were analyzed by Western blot and qRT-PCR.RESULTS: PTX exhibits the ability to inhibit the proliferation of Müller cells when cultured in vitro. The efficacy of this inhibition was found to be dependent on both the concentration of the drug and the duration of the stimulation. Higher concentrations of the drug and longer stimulation times resulted in a weaker ability of the cells to proliferate. Additionally, PTX also induces apoptosis in Müller cells, with increased drug concentrations and longer stimulation times leading to higher apoptosis rates. Flow cytometry analysis demonstrates that PTX arrests Müller cells in the G2-M phase of the cell cycle. Moreover, there is a distinct change in cell morphology, with a shift from the typical appearance characterized by clear and slender fibrous structures to a rounder morphology, accompanied by a significant decrease in cell numbers. Further, our findings reveal that there is a transient increase in the expression of cytoinflammatory factors following drug treatment compared to the control group. However, discontinuation of drug stimulation can alleviate this heightened expression. In treated cells, the expression of the CA XIV protein is upregulated compared to the control group, while the expression of vascular endothelial growth factor(VEGF)is downregulated(P<0.05). Additionally, the levels of inflammatory factors in the PTX group are significantly higher than those in the control group(P<0.05), suggesting that PTX has the potential to disrupt the retinal barrier function.CONCLUSION: PTX affects the proliferation and apoptosis of Müller cells, with the effects dependent on stimulation duration and drug concentration. In addition, PTX blocks the Müller cell cycle at the G2-M phase and alters cell morphology, leading to a transient upregulation of inflammatory factors and affecting the integrity of the retinal barrier. These findings indicate the potential toxicity of the antitumor drug PTX to the retina.