Some countries have limited the maximum allowable storage duration for red cells to 5 weeks before transfusion. In the US, red blood cells can be stored for up to 6 weeks, but randomized trials have ...not assessed the effects of this final week of storage on clinical outcomes.
Sixty healthy adult volunteers were randomized to a single standard, autologous, leukoreduced, packed red cell transfusion after 1, 2, 3, 4, 5, or 6 weeks of storage (n = 10 per group). 51-Chromium posttransfusion red cell recovery studies were performed and laboratory parameters measured before and at defined times after transfusion.
Extravascular hemolysis after transfusion progressively increased with increasing storage time (P < 0.001 for linear trend in the AUC of serum indirect bilirubin and iron levels). Longer storage duration was associated with decreasing posttransfusion red cell recovery (P = 0.002), decreasing elevations in hematocrit (P = 0.02), and increasing serum ferritin (P < 0.0001). After 6 weeks of refrigerated storage, transfusion was followed by increases in AUC for serum iron (P < 0.01), transferrin saturation (P < 0.001), and nontransferrin-bound iron (P < 0.001) as compared with transfusion after 1 to 5 weeks of storage.
After 6 weeks of refrigerated storage, transfusion of autologous red cells to healthy human volunteers increased extravascular hemolysis, saturated serum transferrin, and produced circulating nontransferrin-bound iron. These outcomes, associated with increased risks of harm, provide evidence that the maximal allowable red cell storage duration should be reduced to the minimum sustainable by the blood supply, with 35 days as an attainable goal.REGISTRATION. ClinicalTrials.gov NCT02087514.
NIH grant HL115557 and UL1 TR000040.
Although red blood cell (RBC) transfusions can be lifesaving, they are not without risk. In critically ill patients, RBC transfusions are associated with increased morbidity and mortality, which may ...increase with prolonged RBC storage before transfusion. The mechanisms responsible remain unknown. We hypothesized that acute clearance of a subset of damaged, stored RBCs delivers large amounts of iron to the monocyte/macrophage system, inducing inflammation. To test this in a well-controlled setting, we used a murine RBC storage and transfusion model to show that the transfusion of stored RBCs, or washed stored RBCs, increases plasma nontransferrin bound iron (NTBI), produces acute tissue iron deposition, and initiates inflammation. In contrast, the transfusion of fresh RBCs, or the infusion of stored RBC-derived supernatant, ghosts, or stroma-free lysate, does not produce these effects. Furthermore, the insult induced by transfusion of stored RBC synergizes with subclinical endotoxinemia producing clinically overt signs and symptoms. The increased plasma NTBI also enhances bacterial growth in vitro. Taken together, these results suggest that, in a mouse model, the cellular component of leukoreduced, stored RBC units contributes to the harmful effects of RBC transfusion that occur after prolonged storage. Nonetheless, these findings must be confirmed by prospective human studies.
Transfusions of RBCs stored for longer durations are associated with adverse effects in hospitalized patients. We prospectively studied 14 healthy human volunteers who donated standard leuko-reduced, ...double RBC units. One unit was autologously transfused “fresh” (3-7 days of storage), and the other “older” unit was transfused after 40 to 42 days of storage. Of the routine laboratory parameters measured at defined times surrounding transfusion, significant differences between fresh and older transfusions were only observed in iron parameters and markers of extravascular hemolysis. Compared with fresh RBCs, mean serum total bilirubin increased by 0.55 mg/dL at 4 hours after transfusion of older RBCs (P = .0003), without significant changes in haptoglobin or lactate dehydrogenase. In addition, only after the older transfusion, transferrin saturation increased progressively over 4 hours to a mean of 64%, and non–transferrin-bound iron appeared, reaching a mean of 3.2μM. The increased concentrations of non–transferrin-bound iron correlated with enhanced proliferation in vitro of a pathogenic strain of Escherichia coli (r = 0.94, P = .002). Therefore, circulating non–transferrin-bound iron derived from rapid clearance of transfused, older stored RBCs may enhance transfusion-related complications, such as infection. The trial was registered with www.clinicaltrials.gov as #NCT01319552.
Investigating the metabolic effects of radiation is critical to understand the impact of radiotherapy, space travel, and exposure to environmental radiation. In patients undergoing hemopoietic stem ...cell transplantation, iron overload is a common risk factor for poor outcomes. However, no studies have interrogated the multiorgan effects of these treatments concurrently. Herein, we use a model that recapitulates transfusional iron overload, a condition often observed in chronically transfused patients. We applied an omics approach to investigate the impact of both the iron load and irradiation on the host metabolome. The results revealed dose-dependent effects of irradiation in the red blood cells, plasma, spleen, and liver energy and redox metabolism. Increases in polyamines and purine salvage metabolites were observed in organs with high oxygen consumption including the heart, kidneys, and brain. Irradiation also impacted the metabolism of the duodenum, colon, and stool, suggesting a potential effect on the microbiome. Iron infusion affected the response to radiation in the organs and blood, especially in erythrocyte polyamines and spleen antioxidant metabolism, and affected glucose, methionine, and glutathione systems and tryptophan metabolism in the liver, stool, and the brain. Together, the results suggest that radiation impacts metabolism on a multiorgan level with a significant interaction of the host iron status.
Summary
Transfusion of storage‐damaged red blood cells (RBCs) increases non‐transferrin‐bound iron (NTBI) levels in humans. This can potentially enhance virulence of microorganisms. In this study, ...Pseudomonas aeruginosa replication and biofilm production in vitro correlated with NTBI levels of transfused subjects (R2 = 0·80; P < 0·0001). Transfusion of stored RBCs into catheterized mice enhanced P. aeruginosa virulence and mortality in vivo, while pre‐administration of apotransferrin reduced NTBI levels improving survival (69% vs 27% mortality; P < 0·05). These results suggest that longer RBC storage, by modulating the bioavailability of iron, may increase the risk of P. aeruginosa biofilm‐related infections in transfused patients.
Alteration of glycoprotein glycans often changes various properties of the target glycoprotein and contributes to a wide variety of diseases. Here, we focused on the N-glycans of amyloid precursor ...protein whose cleaved fragment, β-amyloid, is thought to cause much of the pathology of Alzheimer's disease (AD). We previously determined the N-glycan structures of normal and mutant amyloid precursor proteins (the Swedish type and the London type). In comparison with normal amyloid precursor protein, mutant amyloid precursor proteins had higher contents of bisecting GlcNAc residues. Because N-acetylglucosaminyltransferase III (GnT-III) is the glycosyltransferase responsible for synthesizing a bisecting GlcNAc residue, the current report measured GnT-III mRNA expression levels in the brains of AD patients. Interestingly, GnT-III mRNA expression was increased in AD brains. Furthermore, β-amyloid treatment increased GnT-III mRNA expression in Neuro2a mouse neuroblastoma cells. We then examined the influence of bisecting GlcNAc on the production of β-amyloid. Both β-amyloid 40 and β-amyloid 42 were significantly decreased in GnT-III-transfected cells. When secretase activities were analyzed in GnT-III transfectant cells, α-secretase activity was increased. Taken together, these results suggest that upregulation of GnT-III in AD brains may represent an adaptive response to protect them from additional β-amyloid production.
Background
In mice, refrigerator‐stored red blood cells (RBCs) are cleared by extravascular hemolysis and induce cytokine production. To enhance understanding of this phenomenon, we sought to model ...it in vitro.
Study Design and Methods
Ingestion of refrigerator‐stored murine RBCs and subsequent cytokine production were studied using J774A.1 mouse macrophage cells and primary murine splenic macrophages. Wild‐type and Ccl2‐GFP reporter mice were used for RBC clearance in vivo.
Results
Although J774A.1 cells and primary macrophages preferentially ingested refrigerator‐stored RBCs in vitro, compared to freshly isolated RBCs, neither produced increased cytokines after erythrophagocytosis. In contrast, phagocytosis of refrigerator‐stored RBCs in vivo induced increases in circulating monocyte chemoattractant protein‐1 (MCP‐1) and keratinocyte chemoattractant (KC) and correspondingly increased mRNA levels in mouse spleen and liver. In the spleen, these were predominantly expressed by CD11b+ cells. Using Ccl2‐GFP reporter mice, the predominant splenic population responsible for MCP‐1 mRNA production was tissue‐resident macrophages (i.e., CD45+, CD11b+, F4/80+, Ly6c+, and CD11clow cells).
Conclusion
J774A.1 cells and primary macrophages selectively ingested refrigerator‐stored RBCs by phagocytosis. Although cytokine expression was not enhanced, this approach could be used to identify the relevant receptor–ligand combination(s). In contrast, cytokine levels increased after phagocytosis of refrigerator‐stored RBCs in vivo. These were primarily cleared in the liver and spleen, which demonstrated increased MCP‐1 and KC mRNA expression. Finally, in mouse spleen, tissue‐resident macrophages were predominantly involved in MCP‐1 mRNA production. The differences between cytokine production in vitro and in vivo are not yet well understood.
Iron is essential for both microorganisms and their hosts. Although effects of dietary iron on gut microbiota have been described, the effect of systemic iron administration has yet to be explored. ...Here, we show that dietary iron, intravenous iron administration, and chronic transfusion in mice increase the availability of iron in the gut. These iron interventions have consistent and reproducible effects on the murine gut microbiota; specifically, relative abundance of the
and
genera negatively correlate with increased iron stores, whereas members of the Clostridia class positively correlate with iron stores regardless of the route of iron administration. Iron levels also affected microbial metabolites, in general, and indoles, in particular, circulating in host plasma and in stool pellets. Taken together, these results suggest that by shifting the balance of the microbiota, clinical interventions that affect iron status have the potential to alter biologically relevant microbial metabolites in the host.
Domain structure of Cryptosporidium UDP-polypeptide N-acetyl galactosaminyl transferases, a family of four enzymes that catalyze the synthesis of O-glycans on mucin-like glycoproteins which mediate ...attachment and invasion.
•There are 4 ppGalNAc-Ts each in the genomes of C. parvum, C. hominis and C. muris.•All four contain a catalytic domain and a ricin B lectin domain.•All four ppGalNAc-Ts are differentially expressed during C. parvum infection in vitro.•C. parvum lysates display ppGalNAc-T activity in vitro.
Although mucin-type O-glycans are critical for Cryptosporidium infection, the enzymes catalyzing their synthesis have not been studied. Here, we report four UDP N-acetyl-α-d-galactosamine:polypeptide N-acetylgalactosaminyl transferases (ppGalNAc-Ts) from the genomes of C. parvum, C. hominis and C. muris. All are Type II membrane proteins which include a cytoplasmic tail, a transmembrane domain, a stem region, a glycosyltransferase family 2 domain and a C-terminal ricin B lectin domain. All are expressed during C. parvum infection in vitro, with Cp-ppGalNAc-T1 and -T4 expressed at 24h and Cp-ppGalNAc-T2 and -T3 at 48 and 72h post-infection, suggesting that their expression may be developmentally regulated. C. parvum sporozoite lysates display ppGalNAc-T enzymatic activity against non-glycosylated and pre-glycosylated peptides suggesting that they contain enzymes capable of glycosylating both types of substrates. The importance of mucin-type O-glycans in Cryptosporidium–host cell interactions raises the possibility that Cp-ppGalNAc-Ts may serve as targets for intervention in cryptosporidiosis.
Iron deficiency is the most common nutritional disorder. Children and pregnant women are at highest risk for developing iron deficiency because of their increased iron requirements. Iron-deficiency ...anemia during pregnancy is associated with adverse effects on fetal development, including
low birth weight, growth retardation, hypertension, intrauterine fetal death, neurologic impairment, and premature birth. We hypothesized that pregnant mice fed an iron-deficient diet would have a similar outcome regarding fetal growth to that of humans. To this end, we randomly assigned female
C57BL/6 mice to consume 1 of 4 diets (high-iron-low-bioavailability, high-iron-high-bioavailability, iron-replete, and iron-deficient) for 4 wk before breeding, followed by euthanasia on day 17 to 18 of gestation. Compared with all other groups, dams fed the high-iron-high-bioavailability
diet had significantly higher liver iron. Hct and Hgb levels in dams fed the iron-deficient diet were decreased by at least 2.5 g/dL as compared with those of all other groups. In addition, the percentage of viable pups among dams fed the iron-deficient diet was lower than that of all other
groups. Finally, compared with all other groups, fetuses from dams fed the iron-deficient diet had lower fetal brain iron levels, shorter crown-rump lengths, and lower weights. In summary, mice fed an iron-deficient diet had similar hematologic values and fetal outcomes as those of iron-deficient
humans, making this a useful model for studying iron-deficiency anemia during pregnancy.
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