Citrate confers less filter-induced complement activation and neutrophil degranulation than heparin when used for anticoagulation during continuous venovenous haemofiltration in critically ill patients

Background: During continuous venovenous haemofiltration (CVVH), regional anticoagulation with citrate may be superior to heparin in terms of biocompatibility, since heparin as opposed to citrate may activate complement (reflected by circulating C5a) and induce neutrophil degranulation in the filter and myeloperoxidase (MPO) release from endothelium. Methods. No anticoagulation (n = 13), unfractionated heparin (n = 8) and trisodium citrate (n = 17) regimens during CVVH were compared. Blood samples were collected pre- and postfilter; C5a, elastase and MPO were determined by ELISA. Additionally, C5a was also measured in the ultrafiltrate. Results: In the heparin group, there was C5a production across the filter which most decreased over time as compared to other groups (P = 0.007). There was also net production of elastase and MPO across the filter during heparin anticoagulation (P = 0.049 or lower), while production was minimal and absent in the no anticoagulation and citrate group, respectively. During heparin anticoagulation, plasma concentrations of MPO at the inlet increased in the first 10 minutes of CVVH (P = 0.024). Conclusion: Citrate confers less filter-induced, potentially harmful complement activation and neutrophil degranulation and less endothelial activation than heparin when used for anticoagulation during continuous venovenous haemofiltration in critically ill patients

Initiation of peritoneal dialysis in the first weeks after catheter insertion: A comparison of a neutral-pH, low-GDP PD fluid and a conventional PD fluid

Background: Chronic exposure to peritoneal dialysis (PD) fluid is associated with development of functional and structural alterations of the peritoneal membrane. The exact time point at which these changes actually occur is not known. Whether changes to the peritoneum occur immediately after installation of PD fluids and whether there is a difference between neutral-pH, low glucose degradation product (low-GDP) PD fluids and conventional PD fluids is not known either. Materials and methods: We performed an observational study. Markers related to inflammation, fibrosis, mesothelial activation, and cytokines/growth factors were measured in effluents immediately after PD-catheter insertion and during the first days and weeks of PD treatment in patients using either dianeal ® or physioneal®. Results: Peritoneal response was observed instantly upon insertion of the PD catheter and instillation of PD fluids and persisted during daily PD therapy. Particularly during the first contacts of the peritoneum with PD fluids, high levels of cytokines and biomarkers were observed. In general, CA125 is slightly higher with dianeal. There is no difference between the fluids in hyaluronic acid (HA), IL-6, IL-8, MCP-1, VEGF, and TGFβ-1 levels. Conclusion: Implantation of the Tenckhoff catheter and installation of PD fluids induce inflammation, which in the first days resembles an acute inflammatory response. More continuous infusion of PD fluids further enhances peritoneal inflammation. The use of the bicarbonate/ lactate-buffered, neutral-pH, low-GDP PD fluid physioneal exerts lower CA125 levels, lower D/P4 creatinine, but similar inflammatory response compared to conventional dianeal PD fluids in this early stage of PD therapy

Hydathode immunity protects the Arabidopsis leaf vasculature against colonization by bacterial pathogens

Plants prevent disease by passively and actively protecting potential entry routes against invading microbes. For example, the plant immune system actively guards roots, wounds, and stomata. How plants prevent vascular disease upon bacterial entry via guttation fluids excreted from specialized glands at the leaf margin remains largely unknown. These so-called hydathodes release xylem sap when root pressure is too high. By studying hydathode colonization by both hydathode-adapted (Xanthomonas campestris pv. campestris) and non-adapted pathogenic bacteria (Pseudomonas syringae pv. tomato) in immunocompromised Arabidopsis mutants, we show that the immune hubs BAK1 and EDS1-PAD4-ADR1 restrict bacterial multiplication in hydathodes. Both immune hubs effectively confine bacterial pathogens to hydathodes and lower the number of successful escape events of an hydathode-adapted pathogen toward the xylem. A second layer of defense, which is dependent on the plant hormones' pipecolic acid and to a lesser extent on salicylic acid, reduces the vascular spread of the pathogen. Thus, besides glands, hydathodes represent a potent first line of defense against leaf-invading microbes

Comparison of Glyaderm with different dermal substitute matrices in a porcine wound model

BACKGROUND: The closure of extensive burn wounds with widely expanded autologous split-thickness skin grafts (STSG) is associated with undesirable scar formation and contraction, due to the lack of dermis. Various materials for dermal replacement have been developed, either of xenogeneic, allogeneic or synthetic origin and are placed in the wound underneath a thin STSG in order to improve scar quality. In this study, a porcine wound model was used to compare several commercially available acellular dermal substitutes with an acellular dermal substitute prepared from glycerol preserved human skin: Glyaderm(Ⓡ). METHODS: Antigenic components of the allografts were removed by incubation in the 0.06 M NaOH solution. In the first experiments, the dermal substitutes were applied to full thickness wounds and covered simultaneously with STSG. Controls were covered with STSG only. The wound healing response was analyzed for 8 weeks, both macroscopically and histologically. The Mann-Whitney U test was used for statistical analysis. In the second series of experiments, Glyaderm(Ⓡ) was applied in a two-stage procedure in comparison to Integra. The STSG was placed on the dermal substitutes one week later. RESULTS: In the first series, the inflammatory response and myofibroblast influx in Glyaderm(Ⓡ) were limited, indicating possible beneficial outcomes on final wound healing results. The survival of the STSG on the acellular dermis was lower compared to the control wounds. Second series: the take of the STSG was the same as in the controls, but additionally wound contraction was reduced. The application of Glyaderm(Ⓡ) was non-inferior to Integra. CONCLUSION: Glyaderm(Ⓡ) can be successfully used for the reduction of wound contraction when applied in a two-stage procedure

Glycan modification of glioblastoma-derived extracellular vesicles enhances receptor-mediated targeting of dendritic cells

Glioblastoma is the most prevalent and aggressive primary brain tumour for which total tumour lysate-pulsed dendritic cell vaccination is currently under clinical evaluation. Glioblastoma extracellular vesicles (EVs) may represent an enriched cell-free source of tumour-associated (neo-) antigens to pulse dendritic cells (DCs) for the initiation of an anti-tumour immune response. Capture and uptake of EVs by DCs could occur in a receptor-mediated and presumably glycan-dependent way, yet the glycan composition of glioblastoma EVs is unknown. Here, we set out to characterize the glycocalyx composition of glioblastoma EVs by lectin-binding ELISA and comprehensive immunogold transmission electron microscopy (immuno-TEM). The surface glycan profile of human glioblastoma cell line-derived EVs (50–200 nm) was dominated by α-2,3- and α-2,6 linked sialic acid-capped complex N-glycans and bi-antennary N-glycans. Since sialic acids can trigger immune inhibitory sialic acid–binding Ig-like lectin (Siglec) receptors, we screened for Siglec ligands on the EVs. Glioblastoma EVs showed significant binding to Siglec-9, which is highly expressed on DCs. Surprisingly, however, glioblastoma EVs lack glycans that could bind Dendritic Cell-Specific Intercellular adhesion molecule-3-Grabbing Non-integrin (DC-SIGN, CD209), a receptor that mediates uptake and induction of CD4+ and CD8+ T cell activation. Therefore, we explored whether modification of the EV glycan surface could reduce immune inhibitory Siglec binding, while enhancing EV internalization by DCs in a DC-SIGN dependent manner. Desialylation with a pan-sialic acid hydrolase led to reduction of sialic acid expression on EVs. Moreover, insertion of a high-affinity ligand (LewisY) for DC-SIGN resulted in a four-fold increase of uptake by monocyte-derived DCs. In conclusion, we show that the glycocalyx composition of EVs is a key factor of efficient DC targeting and that modification of the EV glycocalyx potentiates EVs as anti-cancer vaccine

Silversulfadiazine cream treatment results in more wound contraction and more itch in a standardized porcine scald model

A variety of dressings is available for the treatment of partial thickness wounds but none has strong evidence supporting their beneficial effect on healing. This may be due to variation in the type and depth of wounds in clinical studies. A standardized porcine wound model is therefore used in this study to compare three dressings commonly used in burn centers.Partial thickness scalds were made on the flanks of pigs. Wounds were treated with SSD (flammazine), a hydrofibre dressing or glycerol preserved pig skin. The healing process was monitored for 8 weeks. Macroscopic parameters were the itch behaviour, cosmetic appearance of the scars and contraction. Microscopic parameters were the inflammatory response, myofibroblast influx and the numbers of nerves. All wounds were closed at day 14 and wound infection did not occur. Treatment with SSD resulted in significant more wound contraction compared to treatment with glycerol preserved pig skin. Animals treated with SSD suffered more from itch (scratching) during the first 2 weeks after wounding. The number of nerves in healing wounds of these animals was significantly higher compared to the other 2 groups. We did not observe differences in the inflammatory respons or myofibroblast differentiation. In our standardized porcine partial thickness wound model, treatment with SSD resulted in less favourable wound healing. Compared to treatment with glycerol preserved allogeneic skin, SSD resulted in more contraction. The higher numbers of nerves may indicate that outgrowth of nerves is faster in wounds treated with SSD

Inorganic phosphate limitation modulates capsular polysaccharide composition in mycobacteria

Mycobacterium tuberculosis is protected by an unusual and highly impermeable cell envelope that is critically important for the successful colonization of the host. The outermost surface of this cell envelope is formed by capsular polysaccharides that play an important role in modulating the initial interactions once the bacillus enters the body. Although the bioenzymatic steps involved in the production of the capsular polysaccharides are emerging, information regarding the ability of the bacterium to modulate the composition of the capsule is still unknown. Here, we study the mechanisms involved in regulation of mycobacterial capsule biosynthesis using a high throughput screen for gene products involved in capsular α-glucan production. Utilizing this approach we identified a group of mutants that all carried mutations in the ATP-binding cassette phosphate transport locus pst. These mutants collectively exhibited a strong overproduction of capsular polysaccharides, including α-glucan and arabinomannan, suggestive of a role for inorganic phosphate (P(i)) metabolism in modulating capsular polysaccharide production. These findings were corroborated by the observation that growth under low P(i) conditions as well as chemical activation of the stringent response induces capsule production in a number of mycobacterial species. This induction is, in part, dependent on σ factor E. Finally, we show that Mycobacterium marinum, a model organism for M. tuberculosis, encounters P(i) stress during infection, which shows the relevance of our findings in vivo

A PERITONEAL DIALYSIS REGIMEN LOW IN GLUCOSE AND GLUCOSE DEGRADATION PRODUCTS RESULTS IN INCREASED CANCER ANTIGEN 125 AND PERITONEAL ACTIVATION

Background: Glucose and glucose degradation products (GDPs) in peritoneal dialysis fluids (PDFs) are both thought to mediate progressive peritoneal worsening. Methods: In a multicenter, prospective, randomized crossover study, incident continuous ambulatory peritoneal dialysis patients were treated either with conventional lactate-buffered PDF (sPD regimen) or with a regimen low in glucose and GDPs: Nutrinealx1, Extranealx1, and Physionealx2 (NEPP regimen; all solutions: Baxter Healthcare, Utrecht, Netherlands). After 6 months, patients were switched to the alternative regimen for another 6 months. After 6 weeks of run-in, before the switch, and at the end of the study, 4-hour peritoneal equilibration tests were performed, and overnight effluents were analyzed for cells and biomarkers. Differences between the regimens were assessed by multivariate analysis corrected for time and regimen sequence. Results: The 45 patients who completed the study were equally distributed over both groups. During NEPP treatment, D-4/D-0 glucose was lower (p <0.01) and D/P creatinine was higher (p = 0.04). In NEPP overnight effluent, mesothelial cells (p <0.0001), cancer antigen 125 (p <0.0001), hyaluronan (p <0.0001), leukocytes (p <0.001), interleukins 6 (p = 0.001) and 8 (p = 0.0001), and vascular endothelial growth factor (VEGF, p <0.0001) were increased by a factor of 2 - 3 compared with levels in sPD effluent. The NEPP regimen was associated with higher transport parameters, but that association disappeared after the addition of VEGF to the model. The association between NEPP and higher effluent levels of VEGF could not be attributed to glucose and GDP loads. Conclusions: Study results indicate preservation of the mesothelium and increased peritoneal activation during NEPP treatment. Whether the increase in VEGF reflects an increase in mesothelial cell mass or whether it points to another, undesirable mechanism cannot be determined from the present study. Longitudinal studies are needed to finally evaluate the usefulness of the NEPP regimen for further clinical use

The P4-ATPase ATP9A is a novel determinant of exosome release.

Extracellular vesicles (EVs) released by cells have a role in intercellular communication to regulate a wide range of biological processes. Two types of EVs can be recognized. Exosomes, which are released from multi-vesicular bodies upon fusion with the plasma membrane, and ectosomes, which directly bud from the plasma membrane. How cells regulate the quantity of EV release is largely unknown. One of the initiating events in vesicle biogenesis is the regulated transport of phospholipids from the exoplasmic to the cytosolic leaflet of biological membranes. This process is catalyzed by P4-ATPases. The role of these phospholipid transporters in intracellular vesicle transport has been established in lower eukaryotes and is slowly emerging in mammalian cells. In Caenorhabditis elegans (C. elegans), deficiency of the P4-ATPase member TAT-5 resulted in enhanced EV shedding, indicating a role in the regulation of EV release. In this study, we investigated whether the mammalian ortholog of TAT-5, ATP9A, has a similar function in mammalian cells. We show that knockdown of ATP9A expression in human hepatoma cells resulted in a significant increase in EV release that was independent of caspase-3 activation. Pharmacological blocking of exosome release in ATP9A knockdown cells did significantly reduce the total number of EVs. Our data support a role for ATP9A in the regulation of exosome release from human cells