Red cell proteasome modulation by storage, redox metabolism and transfusion.

BACKGROUND: Proteasomes are proteolytic complexes with prominent roles in the control of protein homeostasis and cellular viability. However, little is known about the effects of storage and glucose-6-phosphate dehydrogenase deficiency (G6PD-) on the activity and topology of red blood cell (RBC) proteasomes. MATERIALS AND METHODS: We investigated the concentration (by GeLC-MS proteomics analysis and immunoblotting), activity (by using peptide substrates and proteasome inhibitors), and subcellular/extracellular distribution (following cell fractionation and isolation of extracellular vesicles, respectively) of RBC proteasomes in fresh blood and RBCs from control and G6PD- donors following storage in leukoreduced units. RBC proteasome activity was also tested in transfusion-mimicking conditions in vitro. RESULTS: Stored RBCs were characterised by decreased cytosolic proteasome activity compared to fresh RBCs but increased membrane activity and protein concentration levels. Active proteasomes along with other "repair or destroy" proteins are recruited to the membrane during storage. A proportion of them is released in the supernatant in soluble form or inside extracellular vesicles. Significantly increased enzymatic activity and release of proteasomes were observed in G6PD- vs control RBCs. Similar variations were observed in stress protein biomarkers at the G6PD- membrane. The proteasome profile (mainly the caspase-like activity) had significant correlations with the G6PD- metabolome and quality markers of the RBC units. The storage-induced modifications in the proteasome activities were only partly restored in transfusion-mimicking conditions. DISCUSSION: Storage conditions and G6PD deficiency affect (individually and in synergy) the abundance, distribution, activity, and release of RBC proteasomes. The partial irreversibility of these effects in transfusion-mimicking conditions demands further investigation of their clinical impact on transfusion outcomes.

Current Practice in FFP Preparation and Use in Greece: A National Survey

Objective: Fresh frozen plasma (FFP) transfusion is widely used in modern clinical settings. Practices regarding its use vary due to lack of guidelines from randomized trials. The aim of this study was to assess both the current practices regarding FFP production, use, and wastage and the implementation of quality control (QC), female donor plasma production policies, and use of pharmaceutical hemostatic agents in Greece. Materials and Methods: The study was conducted during February-April 2018. For the first part of the study, data including FFP transfusion indication, hospital department, diagnosis, FFP units/transfusion episode, ABO compatibility, blood donor's sex, and reasons for discarding were collected. For the second part, questionnaire data were analyzed. Results: According to data from 20 Greek hospitals, 12655 FFP units were transfused to 2700 patients during 5069 transfusion episodes in the studied period of time. Most patients were hospitalized in internal medicine, general surgery, and intensive care unit departments. Each patient received on average 4.69 units (2.5 units/episode). Transfusion requests were in accordance with international guidelines in 63.44% of cases and 99.04% of the units were given to ABO-identical patients. Main reasons for discarding included failure to meet quality requirements (30.06%), female donors (22.17%), and other causes (27.26%). Among 96.9% of all transfusion services across the country, 28.26% perform QC according to the directions of the European Directorate for the Quality of Medicines & Health Care and 68.83% discard plasma from female donors. Pharmaceutic hemostatic agents are used in 37.23% of the hospitals. Conclusion: This is the first national survey regarding FFP production and transfusion in Greece. Staff of internal medicine, general surgery, and ICU departments, where most FFP-transfused patients are hospitalized, should be regularly involved in training on contemporary transfusion guidelines. Upcoming centralization of FFP production and inventory management could help in homogenizing practices regarding FFP use and improve product quality. Strengthening the use of pharmaceutic hemostatic agents could improve patients' management.