[Kiwi fruit essence reduces radiation-induced lung injury by down-regulating TNF-α and PDGF-B in rats].

Objective To observe the role of tumor necrosis factor-α (TNF-α) and platelet-derived growth factor-B (PDGF-B) in kiwi fruit essence-mediated protection of radiation-induced lung injury (RILI) in rats. Methods 96 male healthy Sprague-Dawley rats were divided into normal control group, model group, and kiwi fruit essence treatment group(60 and 240 mg/kg) by the random number table method, with 24 animals in each group. The whole lungs underwent 6 MV X-ray irradiation (18 Gy) to induce RILI animal models in rats of the latter three groups. On the next day after irradiation, rats in the latter two groups were intragastrically administrated with 60 or 240 mg/kg kiwi fruit essence, once a day. The rats in the normal control and model groups were treated with 9 g/L sodium chloride solution. Eight rats in the latter three groups were randomly sacrificed on days 14, 28, and 56, while normal control rats were sacrificed on day 56 as the overall control. Blood samples were collected and separated. Serum concentrations of TNF-α and PDGF-B were detected using ELISA. The lung tissues were isolated for HE and Masson staining to evaluate alveolitis and pulmonary fibrosis (PF). The hydroxyproline (HYP) content in lung tissues was detected. The mRNA and protein expression of pulmonary TNF-α and PDGF-B were determined by quantitative real-time PCR and immunohistochemistry. Results Compared with the model group, treatment with 60 and 240 mg/kg kiwi fruit essence group significantly reduced alveolitis on days 14 and 28 as well as PF lesions on days 28 and 56. Compared with the normal control group, HYP content in the lung tissue of the model group increased on day 28 and day 56, while TNF-α and PDGF-B levels in the serum and lung tissues increased at each time point. Compared with the model group during the same period, 60 and 240 mg/kg kiwi fruit essence element treatment group reported the diminished levels of serum and pulmonary TNF-α on day 14 and day 28. Consistently, the lung tissue HYP content and serum and pulmonary PDGF-B levels on day 28 and day 56 were reduced. In addition, the above indicators in the 240 mg/kg kiwi fruit essence treatment group were lower than those for the 60 mg/kg kiwi fruit essence treatment group. Conclusion Kiwi fruit essence can alleviate RILI in rats, which is related to the down-regulation of TNF-α expression at the early stage and decreased PDGF-B level at the middle and late stages.

Does platelet-rich plasma freeze-thawing influence growth factor release and their effects on chondrocytes and synoviocytes?

PRP cryopreservation remains a controversial point. Our purpose was to investigate the effect of freezing/thawing on PRP molecule release, and its effects on the metabolism of chondrocytes and synoviocytes. PRP was prepared from 10 volunteers, and a half volume underwent one freezing/thawing cycle. IL-1ß, HGF, PDGF AB/BB, TGF-ß1, and VEGF were assayed 1 hour and 7 days after activation. Culture media of chondrocytes and synoviocytes were supplemented with fresh or frozen PRP, and, at 7 days, proliferation, gene expression, and secreted proteins levels were evaluated. Results showed that in the freeze-thawed PRP the immediate and delayed molecule releases were similar or slightly lower than those in fresh PRP. TGF-ß1 and PDGF AB/BB concentrations were significantly reduced after freezing both at 1 hour and at 7 days, whereas HGF concentration was significantly lower in frozen PRP at 7 days. In fresh PRP IL-1ß and HGF concentrations underwent a significant further increase after 7 days. Similar gene expression was found in chondrocytes cultured with both PRPs, whereas in synoviocytes HGF gene expression was higher in frozen PRP. PRP cryopreservation is a safe procedure, which sufficiently preserves PRP quality and its ability to induce proliferation and the production of ECM components in chondrocytes and synoviocytes.

Dipeptidyl peptidase-4 inhibitor attenuates hepatic fibrosis via suppression of activated hepatic stellate cell in rats.

BACKGROUND: Dipeptidyl peptidase-4 inhibitor (DPP4-I) is clinically used as a new oral antidiabetic agent. Although DPP4 is reportedly associated with the progression of chronic liver diseases, the effect of DPP4-I on liver fibrosis development is still obscure. This study was designed to elucidate the effect of DPP4-I on liver fibrosis development in conjunction with the activated hepatic stellate cells (Ac-HSCs). METHODS: The antifibrotic effect of DPP4-I was assessed in vivo and in vitro using porcine serum-induced experimental liver fibrosis model. DPP4-I, sitagliptin, at a clinically comparable low dose was administered by gavage daily. RESULTS: DPP4-I significantly attenuated liver fibrosis development along with the suppression of hepatic transforming growth factor (TGF)-ß1, total collagen, and tissue inhibitor of metalloproteinases-1 in a dose-dependent manner. These suppressive effects occurred almost concurrently with the attenuation of HSCs activation. Our in vitro studies showed that DPP4-I inhibited platelet-derived growth factor-BB-mediated proliferation of the Ac-HSCs as well as upregulation of TGF-ß1 and α1(I)-procollagen at magnitudes similar to those of the in vivo studies. The inhibitory effects of DPP4-I against HSCs proliferation and fibrogenic gene expression are mediated through the inhibition of the phosphorylation of ERK1/2, p38 and Smad2/3, respectively. CONCLUSIONS: DPP4-I markedly inhibits liver fibrosis development in rats via suppression of HSCs proliferation and collagen synthesis. These suppressive effects are associated with dephosphorylation of ERK1/2, p38 and Smad2/3 in the HSCs. Since DPP4-I is widely used in clinical practice, this drug may represent a potential new therapeutic strategy against liver fibrosis in the near future.

Lipopolysaccharide enhances transforming growth factor ß1-induced platelet-derived growth factor-B expression in bile duct epithelial cells.

BACKGROUND AND AIM: Platelet-derived growth factor (PDGF)-B is a potent profibrogenic mediator expressed by bile duct epithelial cells (BDECs) that contributes to liver fibrosis after bile duct ligation. However, the mechanism of PDGF-B induction in BDECs during cholestasis is not known. Transforming growth factor ß (TGFß) and lipopolysaccharide (LPS) also contribute to the profibrogenic response after bile duct ligation. We tested the hypothesis that LPS and TGFß1 synergistically induce PDGF-B expression in BDECs. METHODS: Transformed human BDECs (MMNK-1 cells) and primary rat BDECs were stimulated with LPS and/or TGFß1, and signaling pathways through which LPS potentiates TGFß1-induced PDGF-B mRNA expression were investigated. RESULTS: Stimulation of MMNK-1 cells with LPS alone did not significantly induce PDGF-B mRNA expression. However, LPS co-treatment enhanced TGFß1 induction of PDGF-B mRNA in MMNK-1 cells and also in primary rat BDECs. Importantly, co-treatment of MMNK-1 cells with LPS and TGFß1 also significantly increased PDGF-BB protein expression. Interestingly, LPS did not affect TGFß1 activation of a SMAD-dependent reporter construct. Rather, stimulation of MMNK-1 cells with LPS, but not TGFß1, increased JNK1/2 phosphorylation. Expression of dominant negative JNK2, but not dominant negative JNK1, inhibited the LPS potentiation of TGFß1-induced PDGF-B mRNA expression in MMNK-1 cells. In addition, LPS treatment caused IκBα degradation and activation of a nuclear factor κB (NFκB)-dependent reporter construct. Expression of an IκBα super repressor inhibited activation of NFκB and attenuated LPS potentiation of TGFß1-induced PDGF-B mRNA. CONCLUSIONS: The results indicate that LPS activation of NFκB and JNK2 enhances TGFß1-induced PDGF-B expression in BDECs.

Upregulation of transforming growth factor-beta1 and vascular endothelial growth factor gene and protein expression in cyclosporin-induced overgrown edentulous gingiva in rats.

BACKGROUND: To examine the effects of cyclosporin A (CsA) on the expression of growth factors in induced gingival overgrowth with limited contributing factors arising from local inflammation caused by bacterial plaque, this study of gingival overgrowth was designed on the edentulous ridge of rats. METHODS: After a 3-week healing period following maxillary molar extractions, 16 five-week-old male Sprague-Dawley rats were assigned to CsA and control groups. Animals in the CsA group were fed 30 mg/kg CsA daily, whereas the control rats received a mineral oil vehicle instead. After 4 weeks, all animals were sacrificed, and the morphology of edentulous ridges was recorded by dental impression. The gingivae on the left-hand side were dissected and stored for mRNA analysis, whereas the gingivae on the right-hand side were fixed in 4% paraformaldehyde for immunohistochemistry (IHC) analysis of transforming growth factor-beta1 (TGF-beta1), platelet-derived growth factor beta (PDGF-beta), insulin-like growth factor-1 (IGF-1), and vascular endothelial growth factor (VEGF). RESULTS: The edentulous gingivae were enlarged and the body weights were reduced in the CsA-treated animals compared to controls. The mRNA expressions of TGF-beta1, IGF-1, and VEGF were higher in the gingivae of the CsA group than in the control group. In addition, a greater mRNA expression (7.21-fold) of VEGF was demonstrated in the CsA group than in the control group by real-time polymerase chain reaction (PCR). The percentages of cells staining positive for TGF-beta1 and VEGF were significantly greater in the CsA rats than in the control rats. CONCLUSIONS: Greater mRNA expression and positive staining for TGF-beta1 and VEGF were observed in the edentulous gingivae of rats that received CsA. Therefore, CsA may upregulate TGF-beta1 and VEGF gene expression and protein secretion in CsA-induced gingival overgrowth.

VEGF-A and FGF-2 synergistically promote neoangiogenesis through enhancement of endogenous PDGF-B-PDGFRbeta signaling.

Combined stimulation with VEGF-A, FGF-2, or PDGF-BB has emerged as a potent strategy for therapeutic angiogenesis, although the mechanisms underlying the synergism of these factors are not well understood. In the present study, we investigated the mechanism of synergism between VEGF-A and FGF-2 by using Matrigel plug assay in vivo and embryonic stem cell (ESC)-derived VEGF receptor 2 (VEGFR2)-positive cells in vitro. Experiments in vitro revealed that, in addition to having direct mitogenic effects, these molecules enhance intercellular PDGF-B signaling in a cell-type specific manner: VEGF-A enhances endothelial PDGF-B expression, whereas FGF-2 enhances mural PDGF receptor beta (PDGFRbeta) expression. Co-stimulation with VEGF-A and FGF-2 caused significant mural cell recruitment in vitro and formation of functional neovasculature in vivo, compared with single-agent stimulation. These effects were abrogated not only by anti-PDGFRbeta neutralizing antibody, but also by exogenous PDGF-BB, which could overwhelm the endogenous PDGF-BB distribution. These findings indicated the importance of preservation of the periendothelial PDGF-BB gradient. Thus, we demonstrated that the directional enhancement of endogenous PDGF-B-PDGFRbeta signaling is indispensable for the synergistic effect of VEGF-A and FGF-2 on neoangiogenesis in adults. The findings provide insights into the mechanisms underlying the effects of co-stimulation by growth factors, which could lead to rational design of therapeutic angiogenic strategies.

Sorafenib: scientific rationales for single-agent and combination therapy in clear-cell renal cell carcinoma.

Clear-cell renal cell carcinoma (RCC) is characterized by the loss of von Hippel-Lindau disease protein and the resultant dysregulation of the vascular endothelial growth factor (VEGF)/VEGF receptor (VEGFR), platelet-derived growth factor-beta (PDGF-beta)/PDGF receptor-beta (PDGFR-beta), and transforming growth factor-alpha (TGF-alpha)/epidermal growth factor receptor (EGFR)/Raf pathways, which contribute to angiogenesis, lymphangiogenesis, and tumor cell growth and survival. Significant advances in the treatment of clear-cell RCC have been derived from agents that target these pathways, including the multiple-kinase inhibitors (MKIs) sorafenib, sunitinib, and AG013736, which target multiple VEGFRs as well as PDGFR-beta. Sorafenib has the added advantage of inhibiting multiple different Raf isoforms, which enables it to target TGF-alpha/EGFR signaling and may also enhance its inhibition of VEGFR and PDGFR-beta. This review will examine the recent advances in our understanding of the biology of clear-cell RCC and show how those advances have helped delineate new targets of opportunity for treatment. It will also present the early clinical results of agents that target the pathways dysregulated in clear-cell RCC, with special emphasis on sorafenib and the other active MKIs, and will describe the scientific rationales for ongoing and future sorafenib-based combination therapy trials in RCC.