α-Iso-Cubebene Inhibits PDGF-Induced Vascular Smooth Muscle Cell Proliferation by Suppressing Osteopontin Expression

Cardioprotective Potential of Berries of Schisandra chinensis Turcz. (Baill.), Their Components and Food Products

Schisandra chinensis (S. chinensis) berries, originally a component of traditional herbal medicine in China, Korea, and other east Asian countries, are also valuable agents in modern phototherapy. S. chinensis berry preparations, including extracts and their chemical components, demonstrate anti-cancer, hepatoprotective, anti-inflammatory, and antioxidant properties, among others. These valuable properties, and their therapeutic potential, are conditioned by the unique chemical composition of S. chinensis berries, particularly their lignan content. About 40 of these compounds, mainly dibenzocyclooctane type, were isolated from S. chinensis. The most important bioactive lignans are schisandrin (also denoted as schizandrin or schisandrol A), schisandrin B, schisantherin A, schisantherin B, schisanhenol, deoxyschisandrin, and gomisin A. The present work reviews newly-available literature concerning the cardioprotective potential of S. chinensis berries and their individual components. It places special emphasis on the cardioprotective properties of the selected lignans related to their antioxidant and anti-inflammatory characteristis.

Transgenic PDGF-BB sericin hydrogel potentiates bone regeneration of BMP9-stimulated mesenchymal stem cells through a crosstalk of the Smad-STAT pathways

Silk as a natural biomaterial is considered as a promising bone substitute in tissue regeneration. Sericin and fibroin are the main components of silk and display unique features for their programmable mechanical properties, biocompatibility, biodegradability and morphological plasticity. It has been reported that sericin recombinant growth factors (GFs) can support cell proliferation and induce stem cell differentiation through cross-talk of signaling pathways during tissue regeneration. The transgenic technology allows the productions of bioactive heterologous GFs as fusion proteins with sericin, which are then fabricated into solid matrix or hydrogel format. Herein, using an injectable hydrogel derived from transgenic platelet-derived GF (PDGF)-BB silk sericin, we demonstrated that the PDGF-BB sericin hydrogel effectively augmented osteogenesis induced by bone morphogenetic protein (BMP9)-stimulated mesenchymal stem cells (MSCs) in vivo and in vitro, while inhibiting adipogenic differentiation. Further gene expression and protein-protein interactions studies demonstrated that BMP9 and PDGF-BB synergistically induced osteogenic differentiation through the cross-talk between Smad and Stat3 pathways in MSCs. Thus, our results provide a novel strategy to encapsulate osteogenic factors and osteoblastic progenitors in transgenic sericin-based hydrogel for robust bone tissue engineering.

α-Iso-cubebene attenuates neointima formation by inhibiting HMGB1-induced monocyte to macrophage differentiation via suppressing ROS production

α-Iso-cubebene (ICB) is a dibenzocyclooctadiene lignin contained in Schisandra chinensis, a medicinal herb used to improve cardiovascular symptoms. To investigate the mechanisms involved, the effects of ICB on cellular production of reactive oxygen species (ROS) was determined using cultured human THP-1 cells. When THP-1 cells were stimulated with HMGB1, cellular concentration of ROS was increased in dose- and time-dependent manners. These increases were significantly attenuated in cells pretreated with NADPH oxidase inhibitors, diphenyleneiodonium chloride and apocynin, but not by other inhibitors related to ROS generation in monocytes. The expression of constitutively expressed NADPH oxidase (NOX) subunits including NOX1, NOX2, NOX4 and NOX5 was not affected by HMGB1, but HMGB1-induced ROS production was exclusively attenuated in NOX2-deficient cells using siRNA, suggesting an enhanced NOX2 complex assembly. When cells were stimulated with HMGB1, p47phox phosphorylation at ser345, ser359 and ser370 was increased in dose- and time-dependent manners, which were significantly attenuated in ICB (3-10 μg/mL)-pretreated cells. In addition, HMGB1-induced monocyte-macrophage differentiation (MMD) in bone marrow-derived cells isolated from mice were significantly attenuated in cells treated with apocynin and ICB. Also, macrophage infiltration and intimal hyperplasia in the wire-injured femoral artery were significantly attenuated in ICB-treated mice compared to wild-type control mice. The results of this study show that ICB inhibits HMGB1-induced MMD by suppressing ROS production in monocytes, thus suggest that ICB has therapeutic potential for vascular inflammation with subsequent intimal hyperplasia related to vascular injury.

A Pivotal Role for AP-1-Mediated Osteopontin Expression in the Increased Migration of Vascular Smooth Muscle Cells Stimulated With HMGB1

Migration of vascular smooth muscle cells (VSMCs) plays an essential role in the development of vascular remodeling in the injured vasculatures. Previous studies have identified high-mobility group box 1 (HMGB1) as a principal effector mediating vascular remodeling; however, the mechanisms involved have not been fully elucidated. Thus, this study investigated the role of HMGB1 on VSMC migration and the underlying molecular mechanisms involved. VSMCs were ex plant cultured using rat thoracic aorta, and the cellular migration was measured using wound-healing assay. Osteopontin (OPN) mRNA and protein were determined by reverse transcription polymerase chain reaction (RT-PCR) and Western blot, respectively. The OPN promoter was cloned into pGL3 basic to generate a pLuc-OPN-2284 construct. Migration of VSMCs stimulated with HMGB1 (100ng/ml) was markedly increased, which was significantly attenuated in cells pretreated with MPIIIB10 (100–300ng/ml), a neutralizing monoclonal antibody for OPN as well as in cells deficient of OPN. In VSMCs stimulated with HMGB1, OPN mRNA and protein levels were significantly increased in association with an increased promotor activity of OPN gene. Putative-binding sites for activator protein 1 (AP-1) and CCAAT/enhancer-binding protein beta (C/EBPβ) in the indicated promoter region were suggested by TF Search, and the HMGB1-induced expression of OPN was markedly attenuated in cells transfected with siRNA for AP-1. VSMC stimulated with HMGB1 also showed an increased expression of AP-1. Results of this study suggest a pivotal role for AP-1-induced OPN expression in VSMC migration induced by HMGB1. Thus, the AP-1-OPN signaling axis in VSMC might serve as a potential therapeutic target for vascular remodeling in the injured vasculatures.

5-LO-derived LTB4 plays a key role in MCP-1 expression in HMGB1-exposed VSMCs via a BLTR1 signaling axis

Monocyte chemoattractant protein-1 (MCP-1) plays an important role in initiating vascular inflammation; however, its cellular source in the injured vasculatures is unclear. Given the importance of high mobility group box 1 (HMGB1) in tissue injury, we investigated the role of vascular smooth muscle cells (VSMCs) in MCP-1 production in response to HMGB1. In primary cultured rat aortic VSMCs stimulated with HMGB1, the expression of MCP-1 and 5-lipoxygenase (LO) was increased. The increased MCP-1 expression in HMGB1 (30 ng/ml)-stimulated cells was significantly attenuated in 5-LO-deficient cells as well as in cells treated with zileuton, a 5-LO inhibitor. Likewise, MCP-1 expression and production were also increased in cells stimulated with exogenous leukotriene B4 (LTB4), but not exogenous LTC4. LTB4-induced MCP-1 expression was attenuated in cells treated with U75302, a LTB4 receptor 1 (BLTR1) inhibitor as well as in BLTR1-deficient cells, but not in 5-LO-deficient cells. Moreover, HMGB1-induced MCP-1 expression was attenuated in BLTR1-deficient cells or by treatment with a BLTR1 inhibitor, but not other leukotriene receptor inhibitors. In contrast to MCP-1 expression in response to LTB4, the increased MCP-1 production in HMGB1-stimulated VSMC was markedly attenuated in 5-LO-deficient cells, indicating a pivotal role of LTB4-BLTR1 signaling in MCP-1 expression in VSMCs. Taken together, 5-LO-derived LTB4 plays a key role in MCP-1 expression in HMGB1-exposed VSMCs via BLTR1 signaling, suggesting the LTB4-BLTR1 signaling axis as a potential therapeutic target for vascular inflammation in the injured vasculatures.

Mediation of the single-walled carbon nanotubes induced pulmonary fibrogenic response by osteopontin and TGF-β1

PURPOSE OF THE STUDY

A number of in vivo studies have shown that pulmonary exposure to carbon nanotubes (CNTs) may lead to an acute local inflammatory response, pulmonary fibrosis, and granulomatous lesions. Among the factors that play direct roles in initiation and progression of fibrotic processes are epithelial-mesenchymal transition and myofibroblasts recruitment/differentiation, both mediated by transforming growth factor-β1 (TGF-β1). Yet, other contributors to TGF-β1 associated signaling, such as osteopontin (OPN) has not been fully investigated.

MATERIALS AND METHODS

OPN-knockout female mice (OPN-KO) along with their wild-type (WT) counterparts were exposed to single-walled carbon nanotubes (SWCNT) (40 µg/mouse) via pharyngeal aspiration and fibrotic response was assessed 1, 7, and 28 days post-exposure. Simultaneously, RAW 264.7 and MLE-15 cells were treated with SWCNT (24 hours, 6 µg/cm² to 48 µg/cm²) or bleomycin (0.1 µg/ml) in the presence of OPN-blocking antibody or isotype control, and TGF-β1 was measured in supernatants.

RESULTS AND CONCLUSIONS

Diminished lactate dehydrogenase activity at all time points, along with less pronounced neutrophil influx 24 h post-exposure, were measured in broncho-alveolar lavage (BAL) of OPN-KO mice compared to WT. Pro-inflammatory cytokine release (IL-6, TNF-α, MCP-1) was reduced. A significant two-fold increase of TGF-β1 was found in BAL of WT mice at 7 days, while TGF-β1 levels in OPN-KO animals remained unaltered. Histological examination revealed marked decrease in granuloma formation and less collagen deposition in the lungs of OPN-KO mice compared to WT. RAW 264.7 but not MLE-15 cells exposed to SWCNT and bleomycin had significantly less TGF-β1 released in the presence of OPN-blocking antibody. We believe that OPN is important in initiating the cellular mechanisms that produce an overall pathological response to SWCNT and it may act upstream of TGF-β1. Further investigation to understand the mechanistic details of such interactions is critical to predict outcomes of pulmonary exposure to CNT.

α-Isocubebene modulates vascular tone by inhibiting myosin light chain phosphorylation in murine thoracic aorta

α-Iso-cubebene (ICB) is a dibenzocyclooctadiene lignin contained in Schisandra chinensis (SC), a well-known medicinal herb that ameliorates cardiovascular symptoms, but the mechanism responsible for this activity has not been determined. To determine the role played by ICB on the regulation of vascular tone, we investigated the inhibitory effects of ICB on vascular contractile responses by adrenergic α-receptor agonists. In addition, we investigated the role on myosin light chain (MLC) phosphorylation and cytosolic calcium concentration in vascular smooth muscle cells (VSMC). In aortic rings isolated from C57BL/6J mice, ICB significantly attenuated the contraction induced by phenylephrine (PE) and norepinephrine (NE), whereas ICB had no effects on KCl (60 mM)-induced contraction. In vasculatures precontracted with PE, ICB caused marked relaxation of aortic rings with or without endothelium, suggesting a direct effect on VSMC. In cultured rat VSMC, PE or NE increased MLC phosphorylation and increased cytosolic calcium levels. Both of these effects were significantly suppressed by ICB. In conclusion, our results showed that ICB regulated vascular tone by inhibiting MLC phosphorylation and calcium flux into VSMC, and suggest that ICB has anti-hypertensive properties and therapeutic potential for cardiovascular disorders related to vascular hypertension.