Background: Long-chain polyunsaturated fatty acids (PUFAs) are important modulators of red blood cell (RBC) rheology. Dietary PUFAs are readily incorporated into the RBC membrane, improving RBC deformability, fluidity, and hydration. However, enriching the lipid membrane with PUFAs increases the potential for peroxidation in oxidative environments (e.g., refrigerated storage), resulting in membrane damage. Substitution of bis-allylic hydrogens with deuterium ions in PUFAs decreases hydrogen abstraction, thereby inhibiting peroxidation. If lipid peroxidation is a causal factor in the RBC storage lesion, incorporation of deuterated linoleic acid (DLA) into the RBC membrane should decrease lipid peroxidation, thereby improving RBC lifespan, deformability, filterability, and post-transfusion recovery (PTR) after cold storage.Study Design and Methods: Mice associated with good (C57BL/6J) and poor (FVB) RBC storage quality received diets containing 11,11-D2-LA Ethyl Ester (1.0 g/100 g diet; deuterated linoleic acid) or non-deuterated LA Ethyl Ester (control) for 8 weeks. Deformability, filterability, lipidomics, and lipid peroxidation markers were evaluated in fresh and stored RBCs.Results: DLA was incorporated into RBC membranes in both mouse strains. DLA diet decreased lipid peroxidation (malondialdehyde) by 25.4 and 31% percent in C57 mice and 12.9 and 79.9% in FVB mice before and after cold storage, respectively. In FVB, but not C57 mice, deformability filterability, and post-transfusion recovery were significantly improved.Discussion: In a mouse model of poor RBC storage, with elevated reactive oxygen species production, DLA attenuated lipid peroxidation and significantly improved RBC storage quality.

Platelets are stored at room temperature for 5 to 7 days (room temperature–stored platelets [RSPs]). Because of frequent and severe shortages, the US Food and Drug Administration recently approved up to 14-day cold-stored platelets (CSPs) in plasma. However, the posttransfusion function of CSPs is unknown and it is unclear which donors are best suited to provide either RSPs or CSPs. In this study, we sought to evaluate the posttransfusion platelet function and its predictors for platelets stored for the maximum approved storage times (7-day RSPs and 14-day CSPs) in healthy volunteers on acetylsalicylic acid (ASA). We conducted a randomized crossover study in 10 healthy humans. Individuals donated 1 platelet unit, stored at either 22°C or 4°C based on randomization. Before transfusion, participants ingested ASA to inhibit endogenous platelets. Transfusion recipients were tested for platelet function and lipid mediators. Platelet units were tested for lipid mediators only. A second round of transfusion with the alternative product was followed by an identical testing sequence. RSPs reversed platelet inhibition significantly better in αIIbβ3 integrin activation–dependent assays. In contrast, CSPs in recipients led to significantly more thrombin generation, which was independent of platelet microparticles. Lysophosphatidylcholine-O species levels predicted the procoagulant capacity of CSPs. In contrast, polyunsaturated fatty acid concentrations predicted the aggregation response of RSPs. In summary, we provide, to our knowledge, the first efficacy data of extended-stored CSPs in plasma. Our results suggest that identifying ideal RSP and CSP donors is possible, and pave the way for larger studies in the future. This trial is registered at www.ClinicalTrials.gov as #NCT0511102.

Most studies of protein oxidation have typically focused on the reactivity of single amino acid side chains while ignoring the potential importance of adjacent sequences in directing the reaction pathway. We previously showed that hypochlorous acid (HOCl), a specific product of myeloperoxidase, inactivates matrilysin by modifying adjacent tryptophan and glycine (WG) residues in the catalytic domain. Here, we use model peptides that mimic the region of matrilysin involved in this reaction, VVWGTA, VVWATA, and the library VVWXTA, to determine whether specific sequence motifs are targeted for chlorination or oxygenation by myeloperoxidase. Our results demonstrate that HOCl generated by myeloperoxidase or activated neutrophils converts the peptide VVWGTA to a chlorinated product, WG+32(Cl). Tandem mass spectrometry in concert with high resolution ¹H and two-dimensional NMR analysis revealed that the modification required cross-linking of the tryptophan to the amide of glycine followed by chlorination of the indole ring of tryptophan. In contrast, when glycine in the peptide was replaced with alanine, the major products were mono- and dioxygenated tryptophan residues. When the peptide library VVWXTA (where X represents all 20 common amino acids) was exposed to HOCl, only WG produced a high yield of the chloroindolenine derivative. However, when glycine was replaced by other amino acids, oxygenated tryptophan derivatives were the major products. Our observations indicate that WG may represent a specific sequence motif in proteins that is targeted for chlorination by myeloperoxidase.

Purpose of review: Glucose-6-phosphate dehydrogenase (G6PD) deficiency and sickle cell disease (SCD) cause hemolysis, often occurring in individuals of African descent. These disorders co-occur frequently, and possibly interact, altering clinical outcomes in SCD. However, epidemiological investigations of SCD with G6PD deficiency have produced variable results. This contribution reviews the available data about the interaction of G6PD deficiency and SCD. Recent findings: Overall, G6PD deficiency contributes few, if any, effects to laboratory values and clinical outcomes in SCD patients, but may impact transfusion efficacy. This observation is most likely because of the relatively increased G6PD activity in the young red blood cell (RBC) population seen in SCD patients with or without G6PD deficiency. In addition, G6PD deficiency possibly interacts with other genetic modifiers, such as α thalassemia, hemoglobin F levels and SCD haplotype. Summary: Although G6PD deficiency is relatively common, it does not appear to clinically impact patients with SCD. Nonetheless, it is important to evaluate G6PD status in patients with SCD to avoid the use of medications that may cause hemolysis. Future studies evaluating the clinical impact of transfusions from G6PD-deficient RBC donors would be of the greatest benefit to the current literature.

The Surviving Sepsis Campaign: international guidelines for management of sepsis and septic shock 2021 (2021 guidelines) was recently released. The guidelines summarized the evidences from literatures up to July 2019, and composed by 6 parts as "screening and early treatment", "infection", "hemodynamic management", "ventilation", "additional therapies" and "long-term outcomes and goals of care" with a total of 93 items and 99 recommendations. Compared with the 2016 guidelines (96 recommendations), although the total number of recommendations in the 2021 guidelines is similar, the number of "strong recommendations (recommend)" in 2021 guidelines has dropped significantly, as the number of "weak recommendations (suggest)" has increased significantly, and the level of the quality of evidence on which the recommendations are based has been significantly lowered. Furthermore, 2021 guidelines have also markedly deleted or simplified the recommendations regarding infection prevention, acute respiratory distress syndrome (ARDS) treatment, nutritional support and so on. While, the most obvious improvement appears in the segment of "long-term outcomes and goals of care", in which the patients and their families could get help in term of determining their physical rehabilitation and discharge follow-up plans and formulating exact goals of care. 2021 guidelines did not adopt new and emerging therapies or treatments, such as metagenomic next-generation sequencing (mNGS), diaphragm protective ventilation, timing of initiating renal replacement therapy for acute kidney injury, early mobility, endotoxin adsorption, tranexamic acid, E-medicine and telemedicine, big data and artificial intelligence and other new therapies. Collectively, it may suggest the 2021 guidelines tend to be conservative and simplified rather than fairly optimized and logicalized, which may arouse controversy in the future and affect clinician compliance.

Background: Inhaled oxygen is the first-line therapeutic approach for maintaining tissue oxygenation in critically ill patients, but usually exposes patients to damaging hyperoxia. Hyperoxia adversely increases the oxygen tension in the gut lumen which harbors the trillions of microorganisms playing an important role in host metabolism and immunity. Nevertheless, the effects of hyperoxia on gut microbiome and metabolome remain unclear, and metagenomic and metabolomics analysis were performed in this mouse study.Methods: C57BL/6 mice were randomly divided into a control (CON) group exposed to room air with fractional inspired oxygen (FiO₂) of 21% and a hyperoxia (OXY) group exposed to FiO₂ of 80% for 7 days, respectively. Fecal pellets were collected on day 7 and subjected to metagenomic sequencing. Another experiment with the same design was performed to explore the impact of hyperoxia on gut and serum metabolome. Fecal pellets and blood were collected and high-performance liquid chromatography with mass spectrometric analysis was carried out.Results: At the phylum level, hyperoxia increased the ratio of Firmicutes/Bacteroidetes (p = 0.049). At the species level, hyperoxia reduced the abundance of Muribaculaceae bacterium Isolate-037 (p = 0.007), Isolate-114 (p = 0.010), and Isolate-043 (p = 0.011) etc. Linear discriminant analysis effect size (LEfSe) revealed that Muribaculaceae and Muribaculaceae bacterium Isolate-037, both belonging to Bacteroidetes, were the marker microbes of the CON group, while Firmicutes was the marker microbes of the OXY group. Metagenomic analysis using Kyoto Encyclopedia of Genes and Genomes (KEGG) and Carbohydrate-Active enZYmes (CAZy) revealed that hyperoxia provoked disturbances in carbohydrate and lipid metabolism. Fecal metabolomics analysis showed hyperoxia reduced 11-dehydro Thromboxane B2-d4 biosynthesis (p = 1.10 × 10⁻¹¹). Hyperoxia blunted fecal linoleic acid metabolism (p = 0.008) and alpha-linolenic acid metabolism (p = 0.014). We showed that 1-docosanoyl-glycer-3-phosphate (p = 1.58 × 10⁻¹⁰) was the most significant differential serum metabolite inhibited by hyperoxia. In addition, hyperoxia suppressed serum hypoxia-inducible factor-1 (HIF-1, p = 0.007) and glucagon signaling pathways (p = 0.007).Conclusion: Hyperoxia leads to gut dysbiosis by eliminating beneficial and oxygen strictly intolerant Muribaculaceae with genomic dysfunction of carbohydrate and lipid metabolism. In addition, hyperoxia suppresses unsaturated fatty acid metabolism in the gut and inhibits the HIF-1 and glucagon signaling pathways in the serum.