Association between the Perioperative Antioxidative Ability of Platelets and Early Post-Transplant Function of Kidney Allografts: A Pilot Study

BACKGROUND: Recent studies have demonstrated that the actions of platelets may unfavorably influence post-transplant function of organ allografts. In this study, the association between post-transplant graft function and the perioperative activity of platelet antioxidants was examined among kidney recipients divided into early (EGF), slow (SGF), and delayed graft function (DGF) groups. METHODOLOGY/PRINCIPAL FINDINGS: Activities of superoxide dismutase, catalase, glutathione transferase (GST), glutathione peroxidase, and glucose-6-phosphate dehydrogenase (G6P) were determined and levels of glutathione, oxidized glutathione, and isoprostane were measured in blood samples collected immediately before and during the first and fifth minutes of renal allograft reperfusion. Our results demonstrated a significant increase in isoprostane levels in all groups. Interestingly, in DGF patients, significantly lower levels of perioperative activity of catalase (p<0.02) and GST (p<0.02) were observed. Moreover, in our study, the activity of platelet antioxidants was associated with intensity of perioperative oxidative stress. For discriminating SGF/DGF from EGF, sensitivity, specificity, and positive and negative predictive values of platelet antioxidants were 81-91%, 50-58%, 32-37%, and 90-90.5%, respectively. CONCLUSIONS: During renal transplantation, significant changes occur in the activity of platelet antioxidants. These changes seem to be associated with post-transplant graft function and can be potentially used to differentiate between EGF and SGF/DGF. To the best of our knowledge, this is the first study to reveal the potential protective role of platelets in the human transplantation setting

Adenine, guanine and pyridine nucleotides in blood during physical exercise and restitution in healthy subjects

Maximal physical exertion is accompanied by increased degradation of purine nucleotides in muscles with the products of purine catabolism accumulating in the plasma. Thanks to membrane transporters, these products remain in an equilibrium between the plasma and red blood cells where they may serve as substrates in salvage reactions, contributing to an increase in the concentrations of purine nucleotides. In this study, we measured the concentrations of adenine nucleotides (ATP, ADP, AMP), inosine nucleotides (IMP), guanine nucleotides (GTP, GDP, GMP), and also pyridine nucleotides (NAD, NADP) in red blood cells immediately after standardized physical effort with increasing intensity, and at the 30th min of rest. We also examined the effect of muscular exercise on adenylate (guanylate) energy charge—AEC (GEC), and on the concentration of nucleosides (guanosine, inosine, adenosine) and hypoxanthine. We have shown in this study that a standardized physical exercise with increasing intensity leads to an increase in IMP concentration in red blood cells immediately after the exercise, which with a significant increase in Hyp concentration in the blood suggests that Hyp was included in the IMP pool. Restitution is accompanied by an increase in the ATP/ADP and ADP/AMP ratios, which indicates an increase in the phosphorylation of AMP and ADP to ATP. Physical effort applied in this study did not lead to changes in the concentrations of guanine and pyridine nucleotides in red blood cells

31st Annual Meeting and Associated Programs of the Society for Immunotherapy of Cancer (SITC 2016) : part two

Background The immunological escape of tumors represents one of the main ob- stacles to the treatment of malignancies. The blockade of PD-1 or CTLA-4 receptors represented a milestone in the history of immunotherapy. However, immune checkpoint inhibitors seem to be effective in specific cohorts of patients. It has been proposed that their efficacy relies on the presence of an immunological response. Thus, we hypothesized that disruption of the PD-L1/PD-1 axis would synergize with our oncolytic vaccine platform PeptiCRAd. Methods We used murine B16OVA in vivo tumor models and flow cytometry analysis to investigate the immunological background. Results First, we found that high-burden B16OVA tumors were refractory to combination immunotherapy. However, with a more aggressive schedule, tumors with a lower burden were more susceptible to the combination of PeptiCRAd and PD-L1 blockade. The therapy signifi- cantly increased the median survival of mice (Fig. 7). Interestingly, the reduced growth of contralaterally injected B16F10 cells sug- gested the presence of a long lasting immunological memory also against non-targeted antigens. Concerning the functional state of tumor infiltrating lymphocytes (TILs), we found that all the immune therapies would enhance the percentage of activated (PD-1pos TIM- 3neg) T lymphocytes and reduce the amount of exhausted (PD-1pos TIM-3pos) cells compared to placebo. As expected, we found that PeptiCRAd monotherapy could increase the number of antigen spe- cific CD8+ T cells compared to other treatments. However, only the combination with PD-L1 blockade could significantly increase the ra- tio between activated and exhausted pentamer positive cells (p= 0.0058), suggesting that by disrupting the PD-1/PD-L1 axis we could decrease the amount of dysfunctional antigen specific T cells. We ob- served that the anatomical location deeply influenced the state of CD4+ and CD8+ T lymphocytes. In fact, TIM-3 expression was in- creased by 2 fold on TILs compared to splenic and lymphoid T cells. In the CD8+ compartment, the expression of PD-1 on the surface seemed to be restricted to the tumor micro-environment, while CD4 + T cells had a high expression of PD-1 also in lymphoid organs. Interestingly, we found that the levels of PD-1 were significantly higher on CD8+ T cells than on CD4+ T cells into the tumor micro- environment (p < 0.0001). Conclusions In conclusion, we demonstrated that the efficacy of immune check- point inhibitors might be strongly enhanced by their combination with cancer vaccines. PeptiCRAd was able to increase the number of antigen-specific T cells and PD-L1 blockade prevented their exhaus- tion, resulting in long-lasting immunological memory and increased median survival

Growth factor content in PRP and their applicability in medicine

This paper reviews available reports on the advantages and possibilities of clinical use of platelet-rich plasma preparations, with particular emphasis on platelet growth factors. Platelets, an important reservoir of growth factors in the body, play an important role in many processes such as coagulation, immune response, angiogenesis and the healing of damaged tissues. Numerous proteins are contained in the alpha-granules of platelets: platelet-derived growth factor (PDGF), transforming growth factor (TGF), platelet factor interleukin (IL), platelet-derived angiogenesis factor (PDAF), vascular endothelial growth factor (VEGF), epidermal growth factor (EGF), insulin-like growth factor IGF and fibronectin. The development of methods and systems for blood and cell sorting (e.g. CAPSS - compact advanced platelet sequestration system Elektromedics 500, PCCS - platelet concentrate collection system Curasan) have made it possible to obtain significant concentrations of platelets (even by 338 percent) and high concentrations of growth factors, in a form of sterile mass that can be used immediately for clinical purposes. Platelet-rich plasma (PRP; autologous platelet-rich plasma - APRP) are platelet concentrates made of autogenous blood with a high number of platelets in a small volume of plasma. The clinical efficacy of platelet concentrates depends mainly on the number of platelets and the concentration of their growth factors, which act as transmitters in most processes in tissues, particularly in healing where they are responsible for proliferation, differentiation, chemotaxis and tissue morphogenesis. They operate as part of autocrine, paracrine and endocrine mechanisms. Growth factors derived from centrifuged blood were first used in patients with chronic skin ulcers. The clinical use of PRP for a wide variety of applications has been reported mostly in oral and maxillo-facial surgery, orthopedic surgery, treatment of soft tissue diseases and injuries, treatment of burns, hard-to-heal wounds, tissue engineering and implantology

Growth factor content in PRP and their applicability in medicine

This paper reviews available reports on the advantages and possibilities of clinical use of platelet-rich plasma preparations, with particular emphasis on platelet growth factors. Platelets, an important reservoir of growth factors in the body, play an important role in many processes such as coagulation, immune response, angiogenesis and the healing of damaged tissues. Numerous proteins are contained in the alpha-granules of platelets: platelet-derived growth factor (PDGF), transforming growth factor (TGF), platelet factor interleukin (IL), platelet-derived angiogenesis factor (PDAF), vascular endothelial growth factor (VEGF), epidermal growth factor (EGF), insulin-like growth factor IGF and fibronectin. The development of methods and systems for blood and cell sorting (e.g. CAPSS - compact advanced platelet sequestration system Elektromedics 500, PCCS - platelet concentrate collection system Curasan) have made it possible to obtain significant concentrations of platelets (even by 338 percent) and high concentrations of growth factors, in a form of sterile mass that can be used immediately for clinical purposes. Platelet-rich plasma (PRP; autologous platelet-rich plasma - APRP) are platelet concentrates made of autogenous blood with a high number of platelets in a small volume of plasma. The clinical efficacy of platelet concentrates depends mainly on the number of platelets and the concentration of their growth factors, which act as transmitters in most processes in tissues, particularly in healing where they are responsible for proliferation, differentiation, chemotaxis and tissue morphogenesis. They operate as part of autocrine, paracrine and endocrine mechanisms. Growth factors derived from centrifuged blood were first used in patients with chronic skin ulcers. The clinical use of PRP for a wide variety of applications has been reported mostly in oral and maxillo-facial surgery, orthopedic surgery, treatment of soft tissue diseases and injuries, treatment of burns, hard-to-heal wounds, tissue engineering and implantology

Platelet lipidomic

Lipids account for 16-19 percent dry platelet matter and includes 65 percent phospholipids, 25 percent neutral lipids and about 8 percent glycosphingolipids. The cell membrane that surrounds platelets is a bilayer that contains different types phospholipids symmetrically distributed in resting platelets, such as phosphatidylserine (PS), phosphatidylethanolamine (PE), phosphatidylcholine, and sphingomyelin. The collapse of lipid asymmetry is exposure of phosphatidylserine in the external leaflet of the plasma bilayer, where it is known to serve at least two major functions: providing a platform for development of the blood coagulation cascade and presenting the signal that induces phagocytosis of apoptotic cells. During activation, this asymmetrical distribution becomes disrupted, and PS and PE become exposed on the cell surface. The transbilayer movement of phosphatidylserine is responsible for the platelet procoagulant activity. Exposure of phosphatidylserine is a flag for macrophage recognition and clearance from the circulation. Platelets, stored at room temperature for transfusion for more than 5 days, undergo changes collectively known as platelet storage lesions. Thus, the platelet lipid composition and its possible modifications over time are crucial for efficacy of platelet rich plasma therapy. Moreover, a number of substances derived from lipids are contained into platelets. Eicosanoids are lipid signaling mediators generated by the action of lipoxygenase and include prostaglandins, thromboxane A2, 12-hydroxyeicosatetraenoic acid. Isoprostanes have a chemical structure similar to this of prostanoids, but are differently produced into the particle, and are ligands for prostaglandins receptors, exhibiting biological activity like thromboxane A2. Endocannabinoids are derivatives from arachidonic acid which could reduce local pain. Phospholipids growth factors (sphingolipids, lysophosphatidic acid, platelet-activating factor) are involved in tissue regenerating process. Finally, a warning concerning the atherogenic role of platelets, although it should not be exerted in a local therapy, is mentioned. The lipid content of plaletets must be taken into account when these particles are concentrated and used for a local therapy, while the different categories of lipid derivatives could improve or affect the quality of the product

Uridine – An Indicator of Post-Exercise Uric Acid Concentration and Blood Pressure

Studies have shown that uridine concentration in plasma may be an indicator of uric acid production in patients with gout. It has been also postulated that uridine takes part in blood pressure regulation. Since physical exercise is an effective tool in treatment and prevention of cardio-vascular diseases that are often accompanied by hyperuricemia and hypertension, it seemed advisable to attempt to evaluate the relationship between oxypurine concentrations (Hyp, Xan and UA) and that of Urd and BP after physical exercise in healthy subjects. Sixty healthy men (17.2±1.71 years, BMI 23.2±2.31 kg m−2, VO2max 54.7±6.48 ml kg−1 min−1) took part in the study. The subjects performed a single maximal physical exercise on a bicycle ergometer. Blood for analyses was sampled three times: immediately before exercise, immediately after exercise, and in the 30th min of rest. Concentrations of uridine and hypoxanthine, xanthine and uric acid were determined in whole blood using high-performance liquid chromatography. We have shown in this study that the maximal exercise-induced increase of uridine concentration correlates with the post-exercise increase of uric acid concentration and systolic blood pressure. The results of our study show a relationship between uridine concentration in blood and uric acid concentration and blood pressure. We have been the first to demonstrate that a maximal exercise-induced increase in uridine concentration is correlated with the post-exercise and recovery-continued increase of uric acid concentration in healthy subjects. Thus, it appears that uridine may be an indicator of post-exercise hyperuricemia and blood pressure.</jats:p