Fucoidans, sulfated polysaccharides extracted from brown algae, are marine products with the potential to modulate bone formation and vascularization processes. The bioactivity and safety of fucoidans are highly associated with their chemical structure, which may vary with algae species and extraction method. Thus, in depth evaluation of fucoidan extracts in terms of endotoxin content, cytotoxicity, and their detailed molecular biological impact on the individual cell types in bone is needed. In this study, we characterized fucoidan extracts from three different Fucus species including Fucus vesiculosus (Fv), Fucus serratus (Fs), and Fucus distichus subsp. evanescens (Fe) for their chemical features, endotoxin content, cytotoxicity, and bioactive effects on human outgrowth endothelial cells (OEC) and human mesenchymal stem cells (MSC) as in vitro models for bone function and vascularization. Extracts contained mainly high molecular weight (HMW) fucoidans and were free of endotoxins that may cause inflammation or influence vascularization. OEC tolerated fucoidan concentrations up to 200 µg/mL, and no indication of cytotoxicity was observed. The inflammatory response, however, investigated by real-time PCR (RT-PCR) and enzyme-linked immunosorbent assay (ELISA) and endothelial barrier assessed by impedance measurement differed for the individual extracts. MSC in comparison with endothelial cells were more sensitive to fucoidans and showed partly reduced metabolic activity and proliferation at higher doses of fucoidans. Further results for MSC indicated impaired osteogenic functions in alkaline phosphatase and calcification assays. All tested extracts consistently lowered important molecular mediators involved in angiogenesis, such a VEGF (vascular endothelial growth factor), ANG-1 (angiopoietin 1), and ANG-2 (angiopoietin 2), as indicated by RT-PCR and ELISA. This was associated with antiangiogenic effects at the functional level using selected extracts in co-culture models to mimic bone vascularization processes during bone regeneration or osteosarcoma.
Background Sepsis is a critical challenge for the older adults as the immune function is less responsive by aging. Although cell numbers seem preserved in the older adults, macrophages present age-related function decline, which including reduced chemokines, phagocytosis, and autophagy. ABT-263, an inhibitor of the anti-apoptotic protein Bcl-2, is reported had a senolytic effect which can selectively clear the senescent cells in vivo and rejuvenate the aged tissues. Methods We treated the aged (12–16 months) and young (4–6 months) C57BL/6 mouse with ABT-263, then gave the animals cecal slurry injection to induce sepsis to observe the effect of senolytic compound ABT-263 on the survival rate of sepsis. Additionally, we isolated peritoneal macrophages from the aged mouse to investigate the cell function and molecular mechanism. 3-methyladenine (3-MA), a phosphatidylinositol 3-kinases (PI3K) inhibitor, and rapamycin, an autophagy-enhancer, were used to block or mimic the autophagy, respectively. RT-PCR and Western Blot were used to detect autophagy related gene and protein changes in sepsis. EGFP-expressing E. coli was used as a marker to evaluate the phagocytic ability of macrophages. Results The results showed ABT-263 treatment improved the survival rate of sepsis in the aged mouse which related to autophagy, while blocking the autophagy can eliminate this effect. It is revealed that ABT-263 enhanced the phagocytic ability of the peritoneal macrophages by increasing the Trem-2 receptor. Additionally, ABT-263 blocked the binding of Bcl-2 to Beclin-1, thus induced Beclin-1-dependent autophagy. Conclusion ABT-263 enhanced the macrophage function in aged mouse by increasing the Trem-2 receptors and inducing a beclin-1-dependent autophagy, consequently, protected the aged mouse from sepsis.
Abstract. Sepsis is defined as life threatening organ dysfunction arising from a dysregulated host response to infection. The outcomes of sepsis include early mortality, delayed mortality and recovery, and depend on the inflammatory response. Previous studies have demonstrated that regulatory T cells (Tregs) are important in determining the outcome of sepsis, as their suppressive function serves a role in maintaining immune homeostasis. However, Treg-mediated immunosuppression during the course of sepsis remains unclear and little is known about the survival of patients following diagnosis. Studying the survivors of sepsis may explain the mechanisms of natural recovery. Therefore, a 30-day rat model of sepsis survival was established in the current study. Cluster of differentiation CD4 + /CD25 + /forkhead box p3 + Tregs were isolated from the blood and spleens of rats undergoing cecal ligation and puncture or sham surgery, using flow cytometry. Proteomic analysis was performed using nano high-performance liquid chromatography -mass spectrometry. Several different biological pathways associated with uncommon differentially-expressed proteins were identified in the blood and spleen survivor and sham groups. Extracellular-regulated kinase/mitogen-activated protein kinase, as well as integrin and actin cytoskeletal pathway elements, including Ras-related protein 1b, talin 1 and filamin A, were associated with Tregs in the blood. Pathway elements associated with cell cycle regulators in the B-cell translocation gene family of proteins, tumor necrosis factor receptor superfamily member 4, Hippo signaling, P70-S6 kinase 1, phosphatidylinositol 3-kinase/protein kinase B signaling and 1,25-dihydroxyvitamin D3 biosynthesis were associated with Tregs from the spleen including phosphatase 2A activator regulatory factor 4, histone arginine methyltransferase, CD4, major histocompatibility complex class I antigens, 14-3-3 protein θ and nicotinamide adenine dinucleotide phosphate cytochrome P450 reductase. These results explain the mechanism by which Tregs naturally recover and indicates that Tregs in the blood and spleen vary. Differentially-expressed proteins serving a role in these pathways provide additional insight for the identification of new targets for the diagnosis and treatment of sepsis.
Low serum levels of 1α, 25-dihydroxyvitamin D3 (VD3) are associated with a higher mortality in trauma patients with sepsis or ARDS. However, the molecular mechanisms behind this observation are not yet understood. VD3 is known to stimulate lung maturity, alveolar type II cell differentiation, or pulmonary surfactant synthesis and guides epithelial defense during infection. In this study, we investigated the impact of VD3 on the alveolar–capillary barrier in a co-culture model of alveolar epithelial cells and microvascular endothelial cells respectively in the individual cell types. After stimulation with bacterial LPS (lipopolysaccharide), gene expression of inflammatory cytokines, surfactant proteins, transport proteins, antimicrobial peptide, and doublecortin-like kinase 1 (DCLK1) were analyzed by real-time PCR, while corresponding proteins were evaluated by ELISA, immune-fluorescence, or Western blot. The effect of VD3 on the intracellular protein composition in H441 cells was analyzed by quantitative liquid chromatography-mass spectrometry-based proteomics. VD3 effectively protected the alveolar–capillary barrier against LPS treatment, as indicated by TEER measurement and morphological assessment. VD3 did not inhibit the IL-6 secretion by H441 and OEC but restricted the diffusion of IL-6 to the epithelial compartment. Further, VD3 could significantly suppress the surfactant protein A expression induced in the co-culture system by LPS treatment. VD3 induced high levels of the antimicrobial peptide LL-37, which counteracted effects by LPS and strengthened the barrier. Quantitative proteomics identified VD3-dependent protein abundance changes ranging from constitutional extracellular matrix components and surfactant-associated proteins to immune-regulatory molecules. DCLK1, as a newly described target molecule for VD3, was prominently stimulated by VD3 (10 nM) and seems to influence the alveolar–epithelial cell barrier and regeneration.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.