Phenolic Compounds from the Leaves and Twigs of Osteomeles schwerinae That Inhibit Rat Lens Aldose Reductase and Vessel Dilation in Zebrafish Larvae.

Three new phenolic biphenyl derivatives (1-3) and one new lignan glycoside (4) were isolated from the leaves and twigs of Osteomeles schwerinae. The structures of the new compounds were established by spectroscopic data interpretation. The inhibitory effects of 1-4 on rat lens aldose reductase in vitro were examined, and compounds 1-3 markedly inhibited the enzyme with IC50 values of 3.8 to 13.8 µM. In addition, the effects of these isolates on the dilation of hyaloid-retinal vessels induced by high glucose (HG) in zebrafish larvae were investigated. Compound 1 was the most effective in reducing HG-induced dilation of hyaloid-retinal vessels.

Gas6 stimulates angiogenesis of human retinal endothelial cells and of zebrafish embryos via ERK1/2 signaling.

AIM: To determine if growth arrest-specific 6 (Gas6) plays an important role in the regulation of angiogenesis in human retinal microvascular endothelial cells (HRMECs) and in vessel development of zebrafish. METHODS: Proliferation, wound-healing cell migration, and tube formation were measured in HRMECs treated with recombinant human Gas6 (rhGas6). Sprague-Dawley rat aortas in Matrigels were treated with rhGas6, and microvessel sprouting emanating from arterial rings was analyzed. Transgenic zebrafish embryos (flk:GFP) were microinjected with rhGas6 at 50 hours post-fertilization (hpf), and ectopic sprouting of subintestinal vessels (SIVs) was observed under a confocal microscope. Morpholino oligonucleotides (MOs) were microinjected to knockdown gas6 in zebrafish embryos, and intersegmental vessel impairment was observed. The effect of the extracellular signal-regulated kinase (ERK1/2) inhibitor on the migration of HRMECs and on vessel development in zebrafish embryos was tested. RESULTS: rhGas6 stimulated proliferation, migration, and tube formation in HRMECs in a dose-dependent manner. In rat aortas, rhGas6 induced vessel outgrowth, and the sprouting length was longer than that of controls. The rhGas6-microinjected zebrafish embryos had significantly increased vessel outgrowth in the SIVs. Recombinant human vascular endothelial growth factor (rhVEGF) served as a positive control. Knockdown of gas6 inhibited angiogenesis in the developing vessels of zebrafish. The ERK1/2 inhibitor inhibited HRMEC migration and intersegmental vessel formation in zebrafish embryos. CONCLUSIONS/INTERPRETATIONS: These data suggest that Gas6 plays a pivotal role in proliferation, migration, and sprouting of angiogenic endothelial cells in the retina and in zebrafish embryos. Furthermore, Gas6 induced angiogenic processes are induced via phosphorylation of ERK1/2.

Effects of Allium victorialis leaf extracts and its single compounds on aldose reductase, advanced glycation end products and TGF-ß1 expression in mesangial cells.

BACKGROUND: Accumulating evidences suggest that aldose reductase (AR) inhibitors and advanced glycation end product (AGE) formation inhibitors may prevent chronic hyperglycemia-induced long-term complication in diabetes. Transforming growth factor-beta1 (TGF-ß1) plays an important role in the development of diabetic nephropathy. Allium species have been utilized in folk medicine throughout the world for the treatment of various physical disorders. However, the benefits of Allium victorialis (A. victorialis) against diabetic complications, especially nephropathy, have yet to be explored. In the present study, we investigated the protective effect of the compounds isolated from A. victorialis leaf on diabetic nephropathy. METHODS: In vitro AR activity, AGEs formation, and AGE-receptor for AGEs (RAGE) binding in human RAGE (hRAGE)-overexpressing cells were tested. High glucose-induced transforming growth factor-beta1 (TGF-ß1) expression was also examined in mouse kidney mesangial cells (MMCs) cultured under high glucose. RESULTS: Of the isolated eight compounds from A. victorialis leaf extracts tested, quercitrin exhibited the most pronounced inhibitory effects on AR activity (IC50 value of 0.17 µM) and AGEs formation (IC50 value of 4.20 µM). Furthermore, quercitrin disrupted AGE-RAGE binding in a concentration-dependent manner in hRAGE-overexpressing cells. Additionally, of the eight compounds tested, ferulic acid significantly reduced high glucose-induced TGF-ß1 expression and secretion in MMCs. CONCLUSIONS: Our results suggest that active compounds isolated from A. victorialis leaf exhibit inhibitory effects on AR activity in rat lenses and AGE formation. Further, ferulic acid reduces TGF-ß1 mRNA expression and secretion in MMCs under diabetic conditions. Thus, A. victorialis is a good candidate for the development of treatments for diabetic nephropathy.

Induction of myeloma-specific cytotoxic T lymphocytes ex vivo by CD40-activated B cells loaded with myeloma tumor antigens.

We investigated to establish CD40-activated B cells (CD40-B cells) as alternative antigen-presenting cells (APCs) for the induction of myeloma-specific cytotoxic T lymphocytes (CTLs). To generate CD40-B cells, peripheral blood mononuclear cells were co-cultured with CD40L-transfected J558 cells in the presence of IL-4, insulin, transferrin, and cyclosporine for 14 days, and pulsed with myeloma lysates. The CD40-B cells consistently expressed high levels of CD80, CD86, CD54, CCR7, and HLA-DR. The CD40-B cells produced IL-12, IFN-gamma, and IL-6 during the culture period, but not IL-10. In addition, the CD40-B cells showed potent allogeneic T-cell stimulatory capacities that depended on the dose ratio and had the potential to polarize naïve T cells into Th1 subsets. The CD40-B cells loaded with tumor lysates induced strong target-specific CTLs, based on large numbers of IFN-gamma secreting cells and higher cytotoxic activity against target cells compared to the CD40-B cells without the tumor lysates. These results suggest that CD40-B cells loaded with myeloma lysates might provide alternative APCs for cellular immunotherapy in patients with myeloma.

The dysfunction and abnormal signaling pathway of dendritic cells loaded by tumor antigen can be overcome by neutralizing VEGF in multiple myeloma.

We investigated whether dendritic cells (DCs) from multiple myeloma (MM) patients were affected by loading tumor antigens and whether the defective DC function associated with MM could be overcome by the neutralization of VEGF. MM-specific DCs were generated by loading tumor lysates from myeloma cells at diagnosis or relapsed/progressive state, respectively. DCs loaded with tumor lysates showed lower phenotypic maturation, less T cell stimulatory capacity, less cytotoxic T lymphocyte activities, and highly abnormal cytokine secretions of IL-6 and IL-12, compared to myeloma lysate-unloaded DCs. The levels of VEGF, phospho-STAT3 and phospho-ERK1/2 in DCs were significantly higher with loading myeloma lysates. After the neutralization of VEGF activity, the DC function, signal transduction and cytokine production returned to normal. The defective function of DC in patients with MM is significantly affected by loading tumor antigens, correlating with abnormal STAT3 and the NF-kappaB signaling pathway, and neutralization of VEGF can overcome this DC dysfunction through the elimination of abnormal signal transduction.