Pharmacological inhibition of heparin-binding EGF-like growth factor promotes peritoneal angiogenesis in a peritoneal dialysis rat model

The Preventive Effect of Endostar on Radiation-induced Pulmonary Fibrosis

BACKGROUND

Radiation-induced pulmonary fibrosis (RIPF) is a long-term complication of thoracic radiotherapy without effective treatment available.

OBJECTIVE

This study aimed to establish a RIPF mouse model and explore the therapeutic effects and mechanisms of recombinant human endostatin (Endostar).

METHODS

C57BL/6 mice received a 16-Gy dose of X-rays to the whole thorax with or without the administration of Endostar for 24 weeks.

RESULTS

Radiation-induced body weight loss was partially attenuated by Endostar (P<0.05). Endostar significantly reduced alveolar inflammation (P<0.05) and pulmonary fibrosis (P<0.001), as indicated by a decrease in the expression levels of collagen I and collagen IV in lung tissue (both P<0.001). Angiogenesis (as shown by CD31 immunohistochemistry) was also decreased (P<0.01). In irradiated mice, Endostar inhibited the transforming growth factor-β1 (TGF-β1)/drosophila mothers against the decapentaplegic 3 (Smad3)/extracellular regulated protein kinases (ERK) signaling pathway (all P<0.05). In vitro, Endostar treatment decreased the radiation-induced expression of TGF-β1, vascular endothelial growth factor (VEGF), p-Smad3, and p-ERK in alveolar epithelial cells and vascular endothelial cells (all P<0.05).

CONCLUSION

Endostar could alleviate RIPF through decreased antiangiogenic activity and inhibition of the TGF-β1/Smad3/ERK pathway.

Effects of sitagliptin on peritoneal membrane: The potential role of mesothelial cell tight junction proteins

BACKGROUND

The roles of tight junction (TJ) proteins in peritoneal membrane transport and peritoneal dialysis (PD) require further characterisation. Dipeptidyl peptidase-4 is expressed in mesothelial cells, and its activity may affect peritoneal membrane function and morphology.

METHODS

Human peritoneal mesothelial cells (HPMCs) were isolated and cultured from omentum obtained during abdominal surgery, and paracellular transport functions were evaluated by measuring transmesothelial electrical resistance (TMER) and dextran flux. Sprague-Dawley rats were infused daily with 4.25% peritoneal dialysate with and without sitagliptin administration for 8 weeks. At the end of this period, rat peritoneal mesothelial cells (RPMCs) were isolated to evaluate TJ protein expression.

RESULTS

In HPMCs, the protein expression of claudin-1, claudin-15, occludin and E-cadherin was decreased by TGF-β treatment but reversed by sitagliptin co-treatment. TMER was decreased by TGF-β treatment but improved by sitagliptin co-treatment. Consistent with this, dextran flux was increased by TGF-β treatment and reversed by sitagliptin co-treatment. In the animal experiment, sitagliptin-treated rats had a lower D2/D0 glucose ratio and a higher D2/P2 creatinine ratio than PD controls during the peritoneal equilibration test. Protein expression of claudin-1, claudin-15 and E-cadherin decreased in RPMCs from PD controls but was not affected in those from sitagliptin-treated rats. Peritoneal fibrosis was induced in PD controls but ameliorated in sitagliptin-treated rats.

CONCLUSION

The expression of TJ proteins including claudin-1 and claudin-15 was associated with transport function both in HPMCs and in a rat model of PD. Sitagliptin prevents peritoneal fibrosis in PD and can potentially restore peritoneal mesothelial cell TJ proteins.

Discovery of an Heparin-Binding Epidermal Growth Factor Domain Antibody from a Phage Library and Analysis of Its Inhibitory Effects in SKOV3 Cells

Objective: Heparin-binding epidermal growth factor (EGF)-like growth factor (HB-EGF), which binds to the EGF receptor, plays an important role in the occurrence and development of inflammation in various diseases. HB-EGF mediates the progression of ovarian cancer and is associated with disease prognosis. Thus, a specific humanized antibody to HB-EGF with high affinity is important. Methods: In this study, a humanized domain antibody (VH) against HB-EGF was discovered through phage display technology. The domain antibody was expressed in HB2151 cells and purified from the supernatant using protein L, and were used to test the its effect in invasion and migration of ovarian cancer SKOV3. Results: A domain antibody against HB-EGF was discovered, with a dissociation constant of ∼30 nM. Functional assays indicated that the domain antibody inhibited the functions of HB-EGF in promoting invasion and migration of SKOV3 cells. Conclusions: The selected domain antibody is a potential tool for developing novel drugs or therapies to combat ovarian cancer.

Tetramethylpyrazine Ameliorates Peritoneal Angiogenesis by Regulating VEGF/Hippo/YAP Signaling

Angiogenesis of human peritoneal vascular endothelial cells (HPVECs), linked to vascular endothelial growth factor (VEGF)/VEGF receptor 2 (VEGFR2) signaling, is a complication of peritoneal fibrosis (PF). Hippo/YAP signaling interacts with VEGF/VEGFR2 signaling, but the effect on peritoneal angiogenesis and PF has not been studied. We tested VEGF/Hippo/YAP inhibition by tetramethylpyrazine (TMP) in PF mice and HPVECs. This treatment ameliorated peritoneal dialysis (PD)–induced angiogenesis and PF. In mice, PF was associated with upregulation of VEGF, and TMP ameliorated submesothelial fibrosis, perivascular bleeding, and Collagen I abundance. In HPVECs, angiogenesis occurred due to human peritoneal mesothelial cells (HPMCs)–conditioned medium, and TMP alleviated HPVECs migration, tube formation, and YAP nuclear translocation. YAP knockdown PF mouse and HPVEC models were established to further confirm our finding. YAP deletion attenuated the PD-induced or VEGF-induced increase in angiogenesis and PF. The amount of CYR61 and CTGF was significantly less in the YAP knockdown group. To study the possibility that TMP could benefit angiogenesis, we measured the HPVECs migration and tube formation and found that both were sharply increased in YAP overexpression; TMP treatment partly abolished these increases. As well, the amount of VEGFR localized in the trans-Golgi network was lower by double immunofluorescence; VEGFR and its downstream signaling pathways including p-ERK, p-P38, and p-Akt were more in HPVECs with YAP overexpression. Overall, TMP treatment ameliorated angiogenesis, PF, and peritoneum injury. These changes were accompanied by inhibition of VEGF/Hippo/YAP.

Experimental models in peritoneal dialysis (Review)

Peritoneal dialysis (PD) is one of the most commonly used dialysis methods and plays an important role in maintaining the quality of life of patients with end-stage renal disease. However, long-term PD treatment is associated with adverse effects on the structure and function of peritoneal tissue, which may lead to peritoneal ultrafiltration failure, resulting in dialysis failure and eventually PD withdrawal. In order to prevent the occurrence of these effects, the important issues that need to be tackled are improvement of ultrafiltration, protection of peritoneal function and extension of dialysis time. In basic PD research, a reasonable experimental model is key to the smooth progress of experiments. A good PD model should not only simulate the process of human PD as accurately as possible, but also help researchers to understand the evolution process and pathogenesis of various complications related to PD treatment. To better promote the clinical application of PD technology, the present review will summarize and evaluate the in vivo PD experimental models available, thus providing a reference for relevant PD research.

Silencing of lncRNA 6030408B16RIK prevents ultrafiltration failure in peritoneal dialysis via microRNA-326-3p-mediated WISP2 down-regulation

Continuous exposure to peritoneal dialysis (PD) fluid results in peritoneal fibrosis and ultimately causes ultrafiltration failure. Noncoding RNAs, including long noncoding RNAs (lncRNAs) and microRNAs (miRNAs), have been reported to participate in ultrafiltration failure in PD. Therefore, our study aimed to investigate the mechanism of lncRNA 6030408B16RIK in association with miR-326-3p in ultrafiltration failure in PD. Peritoneal tissues were collected from uremic patients with or without PD. A uremic rat model with PD was first established by 5/6 nephrectomy. The relationship between lncRNA 6030408B16RIK, miR-326-3p and WISP2 was identified using luciferase reporter, RNA pull-down and RIP assays. After ectopic expression and depletion treatments in cells, expression of α-SMA, phosphorylated β-catenin, FSP1, E-cadherin and Vimentin was evaluated by RT-qPCR and Western blot analyses, and Collagen III and CD31 expression by immunohistochemistry. Ultrafiltration volume and glucose transport capacity were assessed by the peritoneal equilibration test. Expression of lncRNA 6030408B16RIK and WISP2 was up-regulated and miR-326-3p expression was poor in peritoneal tissues of uremic PD patients and model rats. LncRNA 6030408B16RIK competitively bound to miR-326-3p and then elevated WISP2 expression. Silencing of lncRNA 6030408B16RIK and WISP2 or overexpression of miR-326-3p was shown to decrease the expression of α-SMA, phosphorylated β-catenin, FSP1, Vimentin, Collagen III and CD31, while reducing glucose transport capacity and increasing E-cadherin expression and ultrafiltration volume in uremic PD rats. In summary, lncRNA 6030408B16RIK silencing exerts an anti-fibrotic effect on uremic PD rats with ultrafiltration failure by inactivating the WISP2-dependent Wnt/β-catenin pathway via miR-326-3p.