Objective To determine the inhibitory effect of a synthetic hexa-peptide GGWSHW (G peptide) derived from thrombospondin-1 (TSP1) on TGF-? activation induced by angiotensin Ⅱ (Ang Ⅱ) in cultured human renal tubular epithelial cells. Methods Human proximal tubular epithelial cell line (HK-2) was cultured in vitro, untreated HK-2 cells were acted as normal control group. HK-2 cells were then stimulated by Ang Ⅱ for 1-24 hours (Ang Ⅱ stimulation group),so that optimal dosage and duration could be chosen.One hour prior to induction,HK-2 cells were pretreated with 10 ?mol/L peptide G (G peptide treated group)or losartan (losartan treated group), the blocker of I type receptor of Ang Ⅱ was acted as inhibitory control.The mRNA and protein levels of TSP1,TGF-?1,FN and PAI-1 were measured by RT-PCR and Western blot. Confocal microscopy and flow cytometry were performed to detect the presence of TSP1, TGF-?1 and co-positive expression of two protein, respectively.The concentrations of total and active TGF-?1 as well as FN and PAI-1 in cell culture supematants were measured by ELISA. Additionally, the expression of Smad2 and p-Smad2 was also examined for the bioactivity of TGF-?1 signaling protein. Results Ang Ⅱ enhanced the expression of TSP1 and TGF-?1 in a temporal-spatial dependent manner. The optimal dosage and duration were 1 ?mol/L and 6 hours,for TSP1,and 0.1 ?mol/L and 12 hours for TGF-?1 respectively.Comparing with untreated HK-2,the co-expression of TSP1 and TGF-?1 induced by A Ⅱ showed a increase of 5.4 folds.In addition,the protein level of p-Smad2 was elevated remarkedly, the mRNA level of FN and PAI-1 was up-regulated by 3 and 1.5 folds, and the concentration was increased by 2.0 and 1.9 folds respectively. Peptide G had less effect on the expression of TSP1 and TGF-?1,whereas it significantly reduced the secretion of active TGF-?1,though total level of TGF-?1 remained up-regulated. Furthermore,comparing with losartan treated group, p-Smad2 expression was reduced by 28.9%, the mRNA level of FN and PAI-1 was decreased by 34.5% and 26% respectively,and the protein levels were reduced by 11.0% and 8.9% respectively. Conclusion The inhibitory peptide derived from TSP1 effectively suppresses TGF-?1 activation through a competitive mechanism and also reduces the secretion of FN and PAI-1 associated with fibrosis.

Optical cochlear implant has been occuring as a new cochlear implant which utilizes laser pulses to stimulate hearing. Compared to electronic cochlear implant, it has demonstrated higher spatial selectivity and less radiation scattering, which could lead to higher fidelity cochlear prostheses. At present, most investigations have focused on experiments in vivo. Although a lot of exciting results have been obtained, the mechanisms of laser stimulation is still open. In this paper, a brief review on the recent new findings of optical cochlear implant is given, and possible mechanisms are discussed. In the end, new experimental proposals are suggested which could help to explore the mechanisms of laser-cochlea stimulation.
Cochlear Implantation ; Cochlear Implants ; Hearing Loss ; rehabilitation ; Humans ; Lasers ; Optics and Photonics